tech info

Microwave oven

2009-08-27T11:07:00.000-07:00

Cooking food with microwaves was discovered accidentally in the 1940s. Percy Spencer, a self-taught engineer, was building magnetrons for radar sets with the company Raytheon. He was working on an active radar set when he noticed that a peanut chocolate bar he had in his pocket started to melt. The radar had melted his chocolate bar with microwaves. The first food to be deliberately cooked with Spencer's microwave was popcorn, and the second was an egg, which exploded in the face of one of the experimenters.To verify his finding, Spencer created a high density electromagnetic field by feeding microwave power into a metal box from which it had no way to escape. When food was placed in the box with the microwave energy, the temperature of the food rose rapidly.

Basic microwave ovens heat food quickly and efficiently, but do not brown or bake food in the way conventional ovens do. This makes them unsuitable for cooking certain foods, or to achieve certain effects. Additional kinds of heat sources can be added to microwave packaging, or into combination microwave ovens, to add these additional effects
In the 1960s, Litton bought Studebaker's Franklin Manufacturing assets, which had been manufacturing magnetrons and building and selling microwave ovens similar to the Radarange. Litton then developed a new configuration of the microwave, the short, wide shape that is now common. The magnetron feed was also unique. This resulted in an oven that could survive a no-load condition indefinitely. The new oven was shown at a trade show in Chicago, and helped begin a rapid growth of the market for home microwave ovens. Sales volume of 40,000 units for the US industry in 1970 grew to one million by 1975. Market penetration in Japan, which had learned to build less expensive units by re-engineering a cheaper magnetron, was faster.

Microwave ovens are generally used for time efficiency in both industrial applications such as restaurants and at home, rather than for cooking quality, although some modern recipes using microwave ovens rival recipes using traditional ovens and stoves. Professional chefs generally find microwave ovens to be of limited usefulness because browning, caramelization, and other flavour-enhancing reactions cannot occur due to the temperature range.On the other hand, people who want fast cooking times can use microwave ovens to prepare food or to reheat stored food (including commercially available pre-cooked frozen dishes) in only a few minutes. Microwave ovens are also useful for the ease in which they can perform some traditionally cumbersome kitchen tasks, such as softening butter or melting chocolate. Popcorn is one example of a very popular item with microwave oven users.

A consideration for rating the efficiency of a microwave oven is to assess how much energy is wasted by using other forms of cooking. For example, when heating water for a coffee, a microwave oven heats just the mugful of water itself. When using a kettle, an element heats the kettle itself plus the water plus any extra water which is then left unused in the kettle. Depending upon the size of the kettle and the amount of excess water, the efficiency of microwave ovens can be quite comparable. Cooking in conventional ovens entails heating the internal structure of the oven to cooking temperature and, additionally, it involves maintaining that temperature against convective and radiative losses of heat for a longer time than is usual with a microwave oven. The efficiencies of conventional cooking methods can be difficult to quantify but tend to be lower.

Food and cookware taken out of a microwave oven is rarely much hotter than 100 °C (212 °F). Cookware used in a microwave oven is often much cooler than the food because the cookware is transparent to microwaves; the microwaves heat the food directly and the cookware is indirectly heated by the food. Food and cookware from a conventional oven, on the other hand, are the same temperature as the rest of the oven; a typical cooking temperature is 180 °C (360 °F). That means that conventional stoves and ovens can cause more serious burns.

Due to this phenomenon, microwave ovens set at too-high power levels may even start to cook the edges of the frozen food, while the inside of the food remains frozen. Another case of uneven heating can be observed in baked goods containing berries. In these items, the berries absorb more energy than the drier surrounding bread and also cannot dissipate the heat due to the low thermal conductivity of the bread. The result is frequently the overheating of the berries relative to the rest of the food. The low power levels which mark the "defrost" oven setting are designed to allow time for heat to be conducted from areas which absorb heat more readily to those which heat more slowly. More even heating will take place by placing food off-centre on the turntable tray instead of exactly in the centre.

DISC BRAKE TECH.

2009-08-27T10:53:00.000-07:00

A brake disc, usually made of cast iron or ceramic composites is connected to the wheel and/or the axle.Disk brake is a device for slowing or stopping the rotation of a wheel.Friction causes the disc and attached wheel to slow or stop. Brakes (both disc and drum) convert friction to heat, but if the brakes get too hot, they will cease to work because they cannot dissipate enough heat.

Modern-style disc brakes first appeared on the low-volume Crosley Hotshot in 1949, although they had to be discontinued in 1950 due to design problems.Chrysler's Imperial also offered a type of disc brake from 1949 through 1953, though in this instance they were enclosed with dual internal-expanding, full-circle pressure plates. Reliable modern disc brakes were developed in the UK by Dunlop and first appeared in 1953 on the Jaguar C-Type racing car.
Disc brakes offer better stopping performance than comparable drum brakes, including resistance to "brake fade" caused by the overheating of brake components, and are able to recover quickly from immersion (wet brakes are less effective). Unlike a drum brake, the disc brake has no self-servo effect and the braking force is always proportional to the pressure placed on the braking pedal or lever.

Disc brakes were most popular on sports cars when they were first introduced, since these vehicles are more demanding about brake performance. Discs have now become the more common form in most passenger vehicles, although many (particularly light weight vehicles) use drum brakes on the rear wheels to keep costs and weight down as well as to simplify the provisions for a parking brake. As the front brakes perform most of the braking effort, this can be a reasonable compromise.The design of the disc varies somewhat. Some are simply solid cast iron, but others are hollowed out with fins or vanes joining together the disc's two contact surfaces (usually included as part of a casting process). This "ventilated" disc design helps to dissipate the generated heat and is commonly used on the more-heavily-loaded front discs.

Discs may also be slotted, where shallow channels are machined into the disc to aid in removing dust and gas. Slotting is the preferred method in most racing environments to remove gas, water, and de-glaze brake pads. Some discs are both drilled and slotted. Slotted discs are generally not used on standard vehicles because they quickly wear down brake pads; however, this removal of material is beneficial to race vehicles since it keeps the pads soft and avoids vitrification of their surfaces.
New technology now allows smaller brake systems to be fitted to bicycles, mopeds and now even mountain bikes. The market for mountain bike disc brakes is very large and has huge variety, ranging from simple, mechanical (cable) systems, to highly expensive and also powerful, 6-pot hydraulic disc systems, commonly used on downhill racing bikes. Improved technology has seen the creation of the first vented discs for use on mountain bikes. The vented discs are similar to that seen on cars and have been introduced to help prevent heat fade on fast alpine descents. The first use of disc brakes on mountain bikes utilized mechanical braking systems which did not offer solid braking power, which is why disc brakes were not popular among mountain bikers until hydraulic disc brakes were presented. Most mountain bike brake rotors are made from stainless steel and are very thin. Some use a two-piece floating rotor style, and some lightweight rotors are made from aluminum.

2009-08-27T05:23:00.000-07:00

A hybrid electric vehicle (HEV) is a hybrid vehicle that combines a conventional internal combustion engine propulsion system with an electric propulsion system. The presence of the electric powertrain is intended to achieve better fuel economy than a conventional vehicle. A hybrid electric vehicle is also a form of electric vehicle; a variety of types of HEV exist, and the degree to which they function as EVs varies as well. The most common form of HEV is the hybrid electric car, an automobile driven by a gasoline internal combustion engine (ICE) and electric motors powered by batteries.

The first gasoline-electric hybrid car was released by the Woods Motor Vehicle Company of Chicago in 1917. The hybrid was a commercial failure, proving to be too slow for its price, and too difficult to service. The hybrid-electric vehicle would not become widely available until the release of the Toyota Prius in Japan in 1997, followed by the Honda Insight in 1999. While initially perceived as unnecessary due to the low cost of gasoline, worldwide increases in the price of petroleum caused many automakers to release hybrids in the late 2000s; they are now perceived as a core segment of the automotive market of the future. Worldwide sales of hybrid vehicles produced by Toyota reached 1.7 million vehicles in January 2009. The second-generation Honda Insight was the top-selling vehicle in Japan in April 2009, marking the first occasion that an HEV has received the distinction. American automakers have made development of hybrid cars a top priority.

A more recent working prototype of the HEV was built by Victor Wouk (one of the scientists involved with the Henney Kilrowatt, the first transistor-based electric car). Wouk's work with HEVs in the 1960s and 1970s earned him the title as the "Godfather of the Hybrid". Wouk installed a prototype hybrid drivetrain (with a 16 kW electric motor) into a 1972 Buick Skylark provided by GM for the 1970 Federal Clean Car Incentive Program, but the program was stopped by the United States Environmental Protection Agency (EPA) in 1976 while Eric Stork, the head of the EPA at the time, was accused of a prejudicial coverup.

The varieties of hybrid electric designs can be differentiated by the structure of the hybrid vehicle drivetrain, the fuel type, and the mode of operation.
In 2007, several automobile manufacturers announced that future vehicles will use aspects of hybrid electric technology to reduce fuel consumption without the use of the hybrid drivetrain. Regenerative braking can be used to recapture energy and stored to power electrical accessories, such as air conditioning. Shutting down the engine at idle can also be used to reduce fuel consumption and reduce emissions without the addition of a hybrid drivetrain. In both cases, some of the advantages of hybrid electric technology are gained while additional cost and weight may be limited to the addition of larger batteries and starter motors. There is no standard terminology for such vehicles, although they may be termed mild hybrids.
The 2000s saw development of plug-in hybrid electric vehicles (PHEVs), which can be recharged from the electrical power grid and do not require conventional fuel for short trips. The Renault Kangoo was the first production model of this design, released in France in 2003.

Anti-Rootkits

2008-10-05T03:43:00.000-07:00

Anti-Rootkit is an application that finds and removes any rootkit that is hidden on your computer using advanced rootkit detection technology.Rootkits in Windows systems are particularly insidious because they are able to be completely invisible to antispyware programs.There are numerous specialized anti-rootkit products available for the detection and removal of these types of malicious programs. Anti-Rootkit can even remove Trojans and Rootkits that are hiding inside NTFS Alternate Data Streams.

Note that, on demand anti-rootkits vary in terms of options for removal. Some will only show hidden files/drivers/processes/registry keys but will not remove them.Others will show hidden files/drivers/processes/registry keys but will offer only remove known rootkits.Most of the stand alone anti-rootkit released by AV companies are relatively new.Many will eventually be incorporated into future products to extend anti-rootkit abilities.Surprisingly, most of the current offerings that specifically target rootkits are freeware or open source.

ROOT KITS

2008-10-05T03:34:00.000-07:00

A Root kit is a collection of tools (programs) that enables administrator-level access to a computer or computer network.Also known as "kernel mode Trojans," root kits are far more sophisticated than the usual batch of Windows backdoor programs that irk network administrators today. The difference is the depth at which they control the compromised system.Conventional backdoors like BO2K operate in "user mode", which is to say, they play at the same level as any other application running on the compromised machine. That means that other applications - like anti-virus scanners - can easily discern evidence of the backdoor's existence in the Window's registry or deep among the computer's files.

In contrast, a root kit hooks itself into the operating system's Application Program Interface (API), where it intercepts the system calls that other programs use to perform basic functions, like accessing files on the computer's hard drive. The root kit is the man-in-the-middle, squatting between the operating system and the programs that rely on it, deciding what those programs can see and do.

It uses that position to hide itself. If an application tries to list the contents of a directory containing one of the root kit's files, the malware will censor the filename from the list. It'll do the same thing with the system registry and the process list.

Despite their increasingly sophisticated design, the current crop of Windows root kits are generally not completely undetectable,because it relies on a device driver, booting in "safe mode" will disable its cloaking mechanism, rendering its files visible.

Intrusion detection system

2008-10-02T08:26:00.000-07:00

An intrusion detection system (IDS) monitors network traffic for unwanted attempts at accessing, manipulating, and/or disabling of services.In some cases the IDS may also respond to anomalous or malicious traffic by taking action such as blocking the user or source IP address from accessing the network.

There are IDS that detect based on looking for specific signatures of known threats- similar to the way antivirus software typically detects and protects against malware- and there are IDS that detect based on comparing traffic patterns against a baseline and looking for anomalies.
Host Intrusion Detection Systems are run on individual hosts or devices on the network. A HIDS monitors the inbound and outbound packets from the device only and will alert the user or administrator of suspicious activity is detected.A signature based IDS will monitor packets on the network and compare them against a database of signatures or attributes from known malicious threats. This is similar to the way most antivirus software detects malware. The issue is that there will be a lag between a new threat being discovered in the wild and the signature for detecting that threat being applied to your IDS. During that lag time your IDS would be unable to detect the new threat.

Wireless IDSs can be purchased through a vendor or developed in-house. There are currently only a handful of vendors who offer a wireless IDS solution - but the products are effective and have an extensive feature set.A wireless IDS can be centralized or decentralized. A centralized wireless IDS is usually a combination of individual sensors which collect and forward all data to a central management system, where the wireless IDS data is stored and processed. Decentralized wireless intrusion detection usually includes one or more devices that perform both the data gathering and processing/reporting functions of the IDS. The decentralized method is best suited for smaller WLANs due to cost and management issues. The cost of sensors with data processing capability can become prohibitive when many sensors are required. Also, management of multiple processing/reporting sensors can be more time intensive than in a centralized model.

OSSTMM

2008-10-02T08:16:00.000-07:00

The Open Source Security Testing Methodology Manual (OSSTMM) is a peer-reviewed methodology for performing security tests and metrics.The OSSTMM is a great resource for systems administrators who want to evaluate the security of a wide range of systems in an ordered and detailed way.It is a guide for evaluating how secure systems are. It contains detailed instructions on how to test systems in a methodological way, and how to evaluate and report on the results.

The OSSTMM consists of six section :-

* Information Security
* Process Security
* Internet Technology Security
* Communications Security
* Wireless Security
* Physical Security

An OSSTMM audit is an accurate measurement of security at an operational level, void of assumptions and anecdotal evidence. A proper methodology makes for a valid security measurement which is consistent and repeatable. An open methodology means that it is free from political and corporate agendas. An open source methodology allows for free dissemination of information and intellectual property. The OSSTMM is the collective development of a true security test and the computation of factual security metrics.The primary purpose of the OSSTMM is to provide a scientific methodology for the accurate characterization of security through examination and correlation in a consistent and reliable way. This manual is adaptable to most IS audits, penetration tests, ethical hacking, security assessments, vulnerability assessments, red-teaming, blue-teaming, posture assessments, war games, and security audits.

Firewalls

2008-10-02T08:08:00.000-07:00

A personal firewall is an application which controls network traffic to and from a computer, permitting or denying communications based on a security policy.A firewall is something, either a piece of hardware or software that is intended to stop people getting their fingers on your property. Similar to a physical device, a firewall ringfences your computer system and in the process protects you from a variety of destructive threats that could cause you to suffer a loss of information, data, or a security breach that could damage your reputation or finances. It's either a hardware device or a software program that filters your internet connection so that your internal private network is kept separate from the outside world, the Internet.

The firewall thinks about packets of information, and these are dealt with individually, and if they're not safe, then they are not allowed through. Firewalls can protect individuals and their personal pc's when they connect to the web, and they can also protect computers within a large organisation or business. The company will have an internal network and the firewall keeps this safe by providing a barrier through which all information has to pass, and if it's not safe, it's stopped, or blocked.
Hackers will probe networks and personal web connections and will try to make a connection, maybe by FTP or telnet, and try to gain control of the machines by using security holes and breaches. These security breaches or exploits can cause a great deal of trouble and this is why it is important to have a firewall, even if it is rudimentary. Spyware, browser hijackers, viruses, Trojan horses, worms, phishing, and spam can all be defeated by firewalls. Firewalls use packet filtering, a proxy service and stateful inspection to control data traffic in to and out of a network. They allow the filtering of IP addresses, domain names and protocols, and differentiate between telnet, snmp, smtp, icmp, udp, ftp, http, tcp and IP data transmissions.

Firewalls can either be software based, or they can be a piece of physical hardware that acts as a gateway.They can protect you from hackers who try to log on to your computer using remote login software, they help to avoid application backdoors, smtp session hijacking, and this is a great way to stop junk email spamming. Operating system bugs, denial of service attacks, email bombs, macros and viruses are all defeated by effective firewall solutions. They also act as a proxy server or part of a dmz or demilitarized zone. A good firewall keeps personal data in and hackers out. Out of the box it makes your PC invisible on the Internet so that hackers can not find it. The programs intelligent intrusion prevention technology blocks suspicious Internet traffic, and easy-to-use privacy controls prevent personal information from being sent out without your knowledge.

Software Patching

2008-10-02T08:00:00.000-07:00

A patch is a small piece of software designed to fix problems with or update a computer program or its supporting data.Software patching is an increasingly important aspect of today’s computing environment as the volume, complexity, and number of configurations under which a piece of software runs have grown considerably. Software architects and developers do everything they can to build secure, bug-free software products. To ensure quality, development teams leverage all the tools and techniques at their disposal.

Most software will be used for many years in an ever-changing user environment. This can place new compatibility demands on software and introduce new security vulnerabilities not originally envisioned. Whatever their source, problems can be found in any piece of software and must be addressed with patches.While readers are likely familiar with many of the issues addressed here, my intention is to provide an overview of patching that will help frame one’s thinking when tackling these problems rather than to suggest specific solutions to the problems themselves. The primary focus is on security patches, but the issues discussed are equally applicable to nonsecurity-related defects in any software.
In many cases, security researchers and hackers find vulnerabilities missed during the development cycle, but software vendors find some themselves after the product ships. In the best case, those who find a problem will notify the vendor immediately, before publicly announcing the vulnerability. Other times they do not, however. In some cases they even post exploit code publicly prior to availability of a fix, thereby greatly increasing the risk to users of the affected component.Regardless of the source of the vulnerability, the software vendor has a responsibility to research the issue and, if valid, produce a patch to address the problem and distribute it as widely as possible.Developing a patch requires a thorough understanding of the problem beyond what the finder reported. In some cases, the vulnerability is a simple code flaw that may be easy to fix. In other cases, it may be a much more difficult architectural issue or a problem with how two components interact.

Business Process Outsourcing

2008-10-02T07:39:00.000-07:00

BPO is the process of hiring another company to handle business activities for you. It is distinct from information technology (IT) Outsourcing which focuses on hiring a third-party company or service provider to do IT-related activities, such as application management and application development, data center operations, or testing and quality assurance.

In the early days, BPO usually consisted of outsourcing processes such as payroll. Then it grew to include employee benefits management. Now it encompasses a number of functions that are considered "non-core" to the primary business strategy.Now it is common for organizations to outsource financial and administration (F&A) processes, human resources (HR) functions, call center and customer service activities and accounting and payroll.

These outsourcing deals frequently involve multi-year contracts that can run into hundreds of millions of dollars. Often, the people performing the work internally for the client firm are transferred and become employees for the service provider. Dominant outsourcing service providers in the BPO fields (some of which also dominate the IT outsourcing business) include US companies IBM, Accenture, and Hewitt Associates, as well as European and Asian companies Capgemini, Genpact, TCS, Wipro and Infosys.

Also coming into use is the term BTO -- business transformation outsourcing. This refers to the idea of having service providers contribute to the effort of transforming a business into a leaner, more dynamic, agile and flexible operation.

What is Outsourcing?

2008-10-02T07:34:00.000-07:00

Outsourcing is contracting with another company or person to do a particular function. Almost every organization outsources in some way.An insurance company, for example, might outsource its janitorial and landscaping operations to firms that specialize in those types of work since they are not related to insurance or strategic to the business. The outside firms that are providing the outsourcing services are third-party providers, or as they are more commonly called, service providers.

Although outsourcing has been around as long as work specialization has existed, in recent history, companies began employing the outsourcing model to carry out narrow functions, such as payroll, billing and data entry. Those processes could be done more efficiently, and therefore more cost-effectively, by other companies with specialized tools and facilities and specially trained personnel.

Currently, outsourcing takes many forms. Organizations still hire service providers to handle distinct business processes, such as benefits management. But some organizations outsource whole operations. The most common forms are information technology outsourcing (ITO) and business process outsourcing (BPO).

Business process outsourcing encompasses call center outsourcing, human resources outsourcing (HRO), finance and accounting outsourcing, and claims processing outsourcing. These outsourcing deals involve multi-year contracts that can run into hundreds of millions of dollars.

VZ Navigator

2008-09-14T05:00:00.000-07:00

The simplest definition of VZ Navigator is that it's a GPS on a cellphone. You see a detailed map, updated in real time, of where you are and directions to where you're going. While that's the easiest way to describe it, it doesn't do VZ Navigator justice. There are plenty of additional options and features that go way beyond the capabilities of a conventional GPS.

The version I tested was VZ Navigator 2.8.0.80, which I was told was pre-release beta code. However, it was impressively and happily bug-free, and performed fine. Currently, the service is available on the Motorola v325, though I'm told it will soon be available on all new Verizon phones with location tracking capabilities. A picture of the Motorola v325 is on the left.
Here you can change certain GPS options, from metric unit display, download options, and changing the voice and detail of the VZ Navigator voice announcer. Also use this menu to tweak, customize and skin (to a very limited extent) your interface. This is also the location of a "Check for Updates" tool and basic "About" information.
Note that if VZ Navigator is turned on and is in navigation mode (telling you where you are and where you're going), it's getting constant updates to update your location, and is sucking battery life the entire time. Just remember to turn off VZ Navigator when you're done with it. Battery consumption, however, was very acceptable. The Motorola v325's standard battery is a 880 mAh 3.6v Lithium Ion unit. Fairly small and tiny, but so is the v325 itself.

How to avoid phishing

2008-08-14T10:46:00.000-07:00

If you receive an unexpected e-mail saying your account will be shut down unless you confirm your billing information, do not reply or click any links in the e-mail body.
Before submitting financial information through a Web site, look for the "lock" icon on the browser's status bar. It means your information is secure during transmission.
If you are uncertain about the information, contact the company through an address or telephone number you know to be genuine.
If you unknowingly supplied personal or financial information, contact your bank and credit card company immediately.

2008-08-14T10:36:00.000-07:00

Creating a replica of an existing Web page to fool a user into submitting personal, financial, or password data.
Phishing is the term coined by hackers who imitate legitimate companies in e-mails to entice people to share passwords or credit-card numbers. Recent victims include Charlotte's Bank of America, Best Buy and eBay, where people were directed to Web pages that looked nearly identical to the companies' sites. The term had its coming out this week when the FBI called phishing the "hottest, and most troubling, new scam on the Internet."It used to be that you could make a fake account on AOL so long as you had a credit card generator. However, AOL became smart. Now they verify every card with a bank after it is typed in.

The term phishing comes from the fact that Internet scammers are using increasingly sophisticated lures as they "fish" for users' financial information and password data.
Hackers have an endearing tendency to change the letter "f" to "ph," and phishing is but one example. The f-to-ph transformation is not new among hackers, either. It first appeared in the late 1960s among telephone system hackers, who called themselves phone phreaks.

The challenges of WiMAX service activation

2008-08-14T10:31:00.000-07:00

On cellular networks, the operator retains primary control over the devices operating on its network, but WiMAX will change this.

In traditional cellular networks, the operator retains primary control over the devices operating on its network, with most devices being directly supplied to the subscriber through the operator's retail stores or partners, and pre-provisioned with the operator's software or SIM card.
WiMAX will change this. Subscribers buying a WiMAX-enabled device will be able to choose the device model they prefer and buy it from an operator-independent retailer. Separating the device distribution model from the service delivery model will result in a strong supply chain of devices needed for successful uptake of mobile applications.
This represents a new operating model for the WiMAX operator - one that reduces the pressure to subsidize devices, maintain extensive inventory, and sell non-core devices to subscribers.

A range of devices operating on the network can create complex challenges for customer support staff.
The ability to push firmware to the device enables users to keep their devices updated, reducing customer support workload and cost for the operator. Ideally, device management, including firmware updates and device configuration, should be tied to the plan preferences of each subscriber and to an automated identification of the device.

The ability to set different priority levels for subscribers becomes a requirement. Because WiMAX can support a range of applications such as VoIP, videoconferencing, or video on demand (VoD), the operator needs the ability to set QoS prioritization. Subscribers need to be able to change their profiles and seamlessly download the required configuration settings to their devices.

WIMAX

2008-08-14T10:29:00.000-07:00

WiMAX is a wireless digital communications system intended for wireless "metropolitan area networks". WiMAX can provide broadband wireless access (BWA) up to 30 miles (50 km) for fixed stations, and 3 - 10 miles (5 - 15 km) for mobile stations. In contrast, the WiFi/802.11 wireless local area network standard is limited in most cases to only 100 - 300 feet (30 - 100m).

With WiMAX, WiFi-like data rates are easily supported, but the issue of interference is lessened. WiMAX operates on both licensed and non-licensed frequencies, providing a regulated environment and viable economic model for wireless carriers.

WiMAX can be used for wireless networking in much the same way as the more common WiFi protocol. WiMAX is a second-generation protocol that allows for more efficient bandwidth use, interference avoidance, and is intended to allow higher data rates over longer distances.

The IEEE 802.16 standard defines the technical features of the communications protocol. The WiMAX Forum offers a means of testing manufacturer's equipment for compatibility, as well as an industry group dedicated to fostering the development and commercialization of the technology.

WiMax.com provides a focal point for consumers, service providers, manufacturers, analysts, and researchers who are interested in WiMAX technology, services, and products. Soon, WiMAX will be a very well recognized term to describe wireless Internet access throughout the world.

How was the Phoenix Mission born?

2008-03-08T08:52:00.000-08:00

In the mid to late ’90s, at Dan Goldin’s insistence, what was then called the Human Exploration program at HQ and the Science Office put together a joint mission to Mars scheduled for launch in 2001. It was a lander mission based on a second copy of the Mars Polar Lander (scheduled for 1998). It had an interesting payload that included instruments selected for relevance to human exploration (including MECA and an oxygen production unit). Dr. Chris McKay had been on the committee that had helped develop the plan for this mission and was a supporter of the mission and the connection to human exploration. Dr. Chris McKay had no direct involvement in any of the instruments selected. None of the instruments on which Dr. Chris McKay was a P.I. or a Co-I. were selected.

When Polar Lander crashed in 1998, NASA HQ understandably canceled the 2001 mission, since it was based on the same lander.

Forward to 2002 and the first call for ideas for a Scout mission to Mars. NASA held a workshop in Pasadena to hear ideas for Scout missions and promised to provide seed funding for a few selected ideas.

Carol Stoker and Dr. Chris McKay thought it would be useful to push the 2001 lander concept. We proposed a Scout mission called Ameba. Here is our summary:
“Ameba is an integrated lander mission that would complement the 2007 lander to investigate the chemical, geological and biological properties of the Martian dust characterize the environment on Mars, and collect data relevant to future robotic and human exploration mission. The existing 2001 lander and its existing soil-analysis instruments form the baseline payload. The following basic questions will be answered by Ameba at low cost and with reduced mission risk: Are there any indications of carbon chemistry and oxidants relevant to life? Are there geological signs that Mars had significant quantities of surface water, or hydrothermal activity? What are the mineralogical and mechanical properties of the dust? How will the soil interact with living organisms? What are the radiation and electrostatic properties of the environment that may be detrimental to life?”

Peter Smith and Mike Hecht were Co-I’s, NASA Ames was the lead institution and would manage the mission, and Dr. Chris McKay was the P.I. At the time of this review of Scout ideas, the word within NASA was HQ would “never let the 2001 lander fly.” Many people thought they were wasting our time trying to reuse that hardware and those instruments.

We were not selected for seed funding at this point, but NASA Ames agreed to provide us with in-house support to develop a proposal for the real Scout competition.

However, soon after the real Scout competition started it was clear that HQ was deciding that essentially all planetary missions would have to be managed by JPL. (In fact the four Scouts selected a year later for further study were all JPL managed). In light of this, Carol and Dr. Chris McKay had a meeting to review the prospects for Ameba and concluded that it had no chance of being selected with an Ames lead. We (correctly) concluded that the only way the 2001 lander would fly again if it was proposed with a highly qualified and experienced member of the original 2001 team as P.I. and with JPL as the managing institution. Peter Smith was the obvious choice. We both know Peter well and we just called him up and had a three-way teleconference, and Peter agreed to be the P.I. Peter did several important things that made the proposal successful: He steered the science rationale into line with the selection criterion combining parts of the 2001 and 1998 landers, he worked effectively with the instrument teams and JPL, and he presented the mission to HQ. The rest, as they say, is history.

Phoenix - Scouting for Water on the Red Planet

2008-03-08T08:49:00.000-08:00

Phoenix is a robotic spacecraft that will be used for a space exploration mission to Mars. The scientists conducting the mission will use instruments aboard the Phoenix lander to search for environments suitable for microbial life on Mars, and to research the history of water on the red planet. Phoenix is scheduled to launch in August 2007 and land on Mars in May 2008. The multiagency program is headed by the Lunar and Planetary Laboratory at the University of Arizona, under the direction of NASA. The program is a partnership of universities from the U.S., Canada, Switzerland and Germany; NASA; the Canadian Space Agency; and the aerospace industry. Phoenix will land in the planet’s water-ice-rich northern polar region and use its robotic arm to dig into the arctic terrain.

NASA selected the University of Arizona to lead the Phoenix mission back in August 2003, hoping it would be the first in a new line of smaller, low-cost “Scout” missions in the agency’s exploration of Mars (the cost is about $75 million cheaper than the Spirit/Opportunity rovers, and less than a third the cost of the Viking landers of 1976). The selection was the result of an intense two-year competition with proposals from other institutions. The $325-million NASA award is more than six times larger than any other single research grant in University of Arizona history.

The Mission has a collaborative approach to space exploration. As the very first of NASA’s Mars Scout class, Phoenix combines legacy and innovation in a framework of a true partnership: government, academia and industry. Scout-class missions are led by a scientist, known as a Principal Investigator (PI), whose role is to manage all the scientific data gathered by the spacecraft and lead the mission’s technical and scientific teams.

Pathfinder Airbags in

Phoenix is a partnership of universities, NASA centers and the aerospace industry. The science instruments and operations will the University of Arizona’s responsibility. The Jet Propulsion Laboratory in Pasadena, California, operated under contract by Caltech for NASA, will manage the project and provide mission design and control. Lockheed Martin Space Systems in Denver, Colorado, will build and test the spacecraft. The Canadian Space Agency will provide a meteorological station, including an innovative laser-based atmospheric sensor. The co-investigator institutions include Malin Space Science Systems, Max Planck Institute for Solar System Research, NASA Ames Research Center, NASA Johnson Space Center, Optech Incorporated and SETI Institute, to name just a few.

The lander will land the same way the Viking landers did, slowed primarily by landing rockets, shifting from a recent trend of using air bags for softening landings, as was demonstrated in the Pathfinder, Spirit and Opportunity missions, as well as Europe’s ill fated probe—the Beagle 2. In 2007, a report was filed at the American Astronomical Society by Washington State University professor Dirk Schulze-Makuch that made a claim that rocket exhaust contaminated the Viking landing sites, potentially killing any life that may have been there. The hypothesis was made long after any modifications to Phoenix could be made without delaying the mission significantly. One of the investigators on the Phoenix mission, NASA astrobiologist Chris McKay merely stated that the report “piqued his interest.” Experiments conducted by Nilton Renno, mission co-investigator from the University of Michigan, and his students, have specifically looked at the how much surface dust will be kicked up when Phoenix lands. It was determined, however, that the robotic arm could reach undisturbed soil, for sampling and analyzing.

The Future of BMI

2008-03-08T08:43:00.000-08:00

Utah's electrode array

One of the next challenges in the field of BMI prosthetics is making them feel like normal limbs. A normal limb has a sense of touch and proprioception, the process by which sensory feedback to the brain transmits the location and position of the body's muscles, allowing us to be aware of the arm’s position without having to look. This is accomplished by an array of receptors in the muscles and joints, as well as mechanical receptors in the skin, that enable us to know when we are touching an object. The next generation of prosthetic arms will have proprioception and “feeling,” generating feedback pulses to the brain or to nerve endings that will result in their bearers having an almost natural feel to their bionic limb.

It seems that today, more than ever, BMIs that can operate bionic prosthetics are within our grasp. The Defense Advanced Research Project Agency (DARPA) set an ambitious goal of releasing a fully functioning bionic arm for Food and Drug Administration (FDA) approval by 2009. This arm will have far more degrees of freedom than any other available prosthetic, and in 2011 DARPA is planning to release a prosthetic that has nearly all the motion ability and dexterity of a normal limb, including touch and proprioception. Theoretically, an amputee using this arm will be able to play the piano.

Normann artificial vision

A future type of BMI for patients with paralyzed limbs or spinal cord injuries will send efferent motor impulses directly to the muscles of the limb. Unlike the situation of amputees, in spinal cord injuries, the muscles are functional but nerve impulses aren’t able to get there. A muscle-stimulating BMI will be able to bypass the severed point and directly innervate the muscle through small electric currents. Robotic arms and hands approaching the agility and sensitivity of the human hand already exist and have been covered recently by TFOT.

BMI technologies are not only confined to prosthetic and paralyzed limbs. In the future, BMIs may allow blind people to see using an artificial picture-capturing device, much like a camera. Several methods for visual prosthetics have already been used successfully with patients. These methods use a computer chip implanted on the retina that is fed by a miniature camera on a patient's glasses. The chip stimulates the optic nerves, transmitting a picture to the brain. Devices used today allow patients to see vague shapes or distinguish light from dark, but future devices, such as the Cortical Visual Prosthesis being developed allow improved synthetic vision.

Professor Eilon Vaadia

The John A. Moran Eye Center at the University of Utah has developed a chip , but it could also be applied to other BMI applications. The chip contains an array of electrodes that can be individually stimulated, are small enough to be inserted into brain tissue without much damage, and at the same time are strong enough to withstand the insertion procedure. Some of these implants have been successfully implanted in blind people with positive results. Future generations of these types of devices will lead to improved resolution, and ultimately restoration of sight to the blind.

What we are witnessing today is only the tip of the iceberg of the great potential BMIs hold for medical, military, recreation, and other purposes in the future. BMI research is on the threshold where science meets science fiction. There will surely be exciting news emerging from this field in the very near future.

Noninvasive Brain-Machine Interface (BMI)

2008-03-08T08:40:00.000-08:00

BMIs can be divided into two main groups: invasive and noninvasive. Noninvasive BMIs rely on reading the brain's activity without actually piercing the brain surface. The EEG is one of the earliest noninvasive BMIs, measuring the combined activity of massive groups of brain neurons through voltage differences between different parts of the brain. The EEG is performed by placing approximately 20 electrodes on the scalp; these electrodes are connected by wires to an amplifier, through which the signal is converted to a digital reading, which can then be filtered by a computer to remove any artificial interference. Once connected to the EEG, the subject can be shown different stimuli, and the brain’s electrical patterns in response to the stimuli can be studied.

Some EEG BMIs rely on the subject’s ability to develop control of their own brain activity using a feedback system, whereas others use algorithms that recognize EEG patterns that appear with particular voluntary intentions. Virtual-reality systems have been used to supply patients with efficient feedback systems, and subjects have been able to navigate through a virtual-reality setting by imagining themselves walking or driving. These systems can also be used for gaming TFOT.

EEG-based BMIs have been implemented to help patients suffering from body paralysis, such as the motor-neuron disease ALS. By generating certain brain patterns that are then read by the EEG, patients are able to control a computer cursor and indicate their intentions, and thereby communicate with the external world. EEGs are also reported to have enabled severely disabled tetraplegic patients grasp an object using a paralyzed hand. In these cases, the patient generated certain brain waves that were detected by an EEG and converted into external electrical muscle stimulation, which allowed the contraction of the muscles and movement of the paralyzed limb.

EEGs have many shortcomings, due to much overlapping of electrical activity in the brain as well as electrical artifacts. To achieve better resolution, electrodes can be inserted between the skull and the brain, without piercing the brain tissue, and can allegedly achieve a higher resolution of brain activity. Although noninvasive BMI techniques can improve the quality of life for some disabled patients by allowing them a limited and slow capacity of communication, they are unlikely to hold the solution for allowing patients to perform complex tasks that involve multiple degrees of freedom, such as controlling a robotic arm. These activities will be more likely achieved through invasive techniques.

Brain-Machine Interface

2008-03-08T08:38:00.000-08:00

The majority of motor functions in our body are driven by electrical currents originating in the brain motor cortex and conducted through the spinal cord and peripheral nerves to the muscles, where the electrical impulse is converted to motion by the contraction and retraction of specific muscles. For example, to bend the arm at the elbow joint, the biceps muscle contracts and the triceps relaxes. This seemingly simple movement is the result of the cumulative activity of many brain cells in the area of the cortex in charge of arm movement. The neurons, following a cognitive decision to bend the arm, generate an electric impulse through the peripheral nerves, causing the correct muscles to contract or relax.

The term used for neuronal activity is "action potential." Action potential occurs when an electric impulse shoots through the long shaft of the neuron, called the axon. Each neuron has one axon but is connected to many other neurons through chemical connections called synapses, and can influence other neurons or be influenced itself by the activity of adjacent neurons, creating an extremely complex network of neural cells.

The action potential in a neuron can be measured by inserting an extremely thin electrode adjacent to the axon, where the passing electric current can be detected. The electrode measures the neuron’s rate of action potential in one second, thus measuring its activity.

Most neuroscientists agree that the rate or frequency of the firing constitutes a sort of code for brain activity. For instance, if a certain group of neurons fires action potentials at a high frequency together, the result is the movement of a limb.

The Basis of Palm Vein Technology

2008-03-08T08:35:00.000-08:00

An individual first rests his wrist, and on some devices, the middle of his fingers, on the sensor's supports such that the palm is held centimeters above the device's scanner, which flashes a near-infrared ray on the palm. Unlike the skin, through which near-infrared light passes, deoxygenated hemoglobin in the blood flowing through the veins absorbs near-infrared rays, illuminating the hemoglobin, causing it to be visible to the scanner. Arteries and capillaries, whose blood contains oxygenated hemoglobin, which does not absorb near-infrared light, are invisible to the sensor. The still image captured by the camera, which photographs in the near-infrared range, appears as a black network, reflecting the palm's vein pattern against the lighter background of the palm.

An individual's palm vein image is converted by algorithms into data points, which is then compressed, encrypted, and stored by the software and registered along with the other details in his profile as a reference for future comparison. Then, each time a person logs in attempting to gain access by a palm scan to a particular bank account or secured entryway, etc., the newly captured image is likewise processed and compared to the registered one or to the bank of stored files for verification, all in a period of seconds. Numbers and positions of veins and their crossing points are all compared and, depending on verification, the person is either granted or denied access.

How Secure is the Technology?

On the basis of testing the technology on more than 70,000 individuals, Fujitsu declared that the new system had a false rejection rate of 0.01% (i.e., only one out of 10,000 scans were incorrect denials for access), and a false acceptance rate of less than 0.00008% (i.e., incorrect approval for access in one in over a million scans). Also, if your profile is registered with your right hand, don't log in with your left - the patterns of an individual's two hands differ. And if you registered your profile as a child, it'll still be recognized as you grow, as an individual's patterns of veins are established in utero (before birth). No two people in the world share a palm vein pattern - even those of identical twins differ (so your evil twin won't be able to draw on your portion of the inheritance!)

Potential Applications

The new technology has many potential applications (some of which are already in use) such as an ultra secure system for ATMs and banking transactions, a PC, handheld, or server login system, an authorization system for front doors, schools, hospital wards, storage areas, and high security areas in airports, and even facilitating library lending, doing away with the age-old library card system. Fujitsu is planning to continue the development of the palm vein technology, shrinking the scanner to fit a mobile phone. Fujitsu hopes that its success might usher in a new age in personal data protection techniques, which is especially important when sales of Smartphones and other handhelds are skyrocketing.

Palm Vein Technology

2008-03-08T08:27:00.000-08:00

How secure are your assets? Can your personal identification number be easily guessed? As we increasingly rely on computers and other machines in our daily lives, ensuring the security of personal information and assets becomes more of a challenge. If your bank card or personal data falls into the wrong hands, others can profit at your expense. To help deal with this growing problem, Fujitsu has developed a unique biometric security technology that puts access in the palm of your hand and no one else's.

Fujitsu's palm vein authentication technology consists of a small palm vein scanner that's easy and natural to use, fast and highly accurate. Simply hold your palm a few centimeters over the scanner and within a second it reads your unique vein pattern. A vein picture is taken and your pattern is registered. Now no one else can log in under your profile. ATM transactions are just one of the many applications of this new technology.

Fujitsu's technology capitalizes on the special features of the veins in the palm. Vein patterns are unique even among identical twins. Indeed each hand has a unique pattern. Try logging in with your left hand after registering with your right, and you'll be denied access. The scanner makes use of a special characteristic of the reduced hemoglobin coursing through the palm veins — it absorbs near-infrared light. This makes it possible to take a snapshot of what's beneath the outer skin, something very hard to read or steal.

Besides the high accuracy of a false rejection rate of 0.01% and a false acceptance rate of less than 0.00008 %(as of February, 2005), Fujitsu's contactless palm vein authentication offers a range of advantages over other biometric technologies.

"Fingerprint scans and face recognition ID methods are associated with the police by some people on a psychological level," says Shigeru Sasaki, director of Fujitsu's Media Solutions Laboratory. (Interview date: Feb 2nd, 2005) "In public areas, others don't like the thought of touching what everyone else has touched for sanitary reasons. This is why we created a contactless palm vein scanner."

"Fingerprint scans and face recognition ID methods are

The near-infrared rays in the palm vein scanner have no effect on the body when scanning. To protect the privacy and personal information of the user, the registered biometric information itself can be stored in bank cards. Bank of Tokyo-Mitsubishi ATMs in Japan are already equipped with palm vein scanners developed by Fujitsu. Users access their accounts by having a scan of their palm compared to a pre-registered scan stored on their bank card. This is expected to help reduce the growing cases of bank card thefts and fraudulent financial transactions.

Amid the heightened security climate in recent years and fears of terrorism, there has been a surge in demand for accurate biometric authentication methods. Meanwhile, recent bank card forgery cases in Japan have numbered in the hundreds, involving dozens of financial institutions and hundreds of millions of yen. Victims are usually unaware their money is being stolen until it's too late.

Bank card security isn't just the responsibility of the end user. Financial institutions around the world are being urged to take a greater role in preventing bank card fraud by improving card security. Japan's Financial Services Agency, for instance, has called on banks to implement added security measures such as introducing biometric identification systems.

Fujitsu's palm vein authentication technology will help stop this new wave of crime, and can also be adapted for use in access to secure areas as well as online transactions, customer identification and claiming baggage.

Laser design

2008-01-26T00:34:00.000-08:00

The term design can have two different meanings. In some cases, it is meant to be a detailed description of a device, including e.g. used parts, how they are put together, important operation parameters, etc. In other cases, the term denotes the process leading to such a description. This article assumes the first mentioned meaning and discusses some important aspects for the design of laser devices, such as e.g. diode-pumped solid state lasers, or similar devices such as e.g. optical parametric oscillators. A separate article on laser development gives additional information, in particular on the role which a laser design plays within the process of laser development, and how this process can be optimized.

Defining the Design Goals

Before a design is made, the design goals must be carefully evaluated. These should include not only the central performance parameters such as output power and wavelength; many more details can be relevant:

optimum performance, e.g. in terms of output power, power efficiency, beam quality, brightness, intensity and/or phase noise, long-term stability (e.g. of the output power or the optical frequency), timing jitter, etc.
compact and convenient setup, ease of operation (e.g. simple turn-on procedure, simple wavelength tuning, no need for realignment)
maximum flexibility (e.g. for changing operation parameters)
reliability, low maintenance requirements, simple and cost-effective error analysis, maintenance and repair
minimum sensitivity to vibrations, temperature changes, electromagnetic interference, aging of components
low production cost, i.e., low number of parts, simple alignment and testing, avoiding the use of parts which are expensive, sensitive, or difficult to obtain

It is certainly advisable to carefully work out the list of these requirements for the particular case before investing any significant resources in laser development, because it can easily be much more expensive and time-consuming to introduce additional properties into an already existing device.

Important Aspects of Laser Designs

Of course, the properties of the designed laser device are largely determined by the design details, not only by the used parts. Some aspects are particularly important:

general design parameters, e.g. resonator length (influencing compactness, tuning issues, frequency stability, etc.), pump intensity, etc.
selection of gain medium (e.g. a laser crystal) and pump source, suitable choice of geometry (e.g. rod or thin disk, side pumping or end pumping), doping concentration, crystal length, etc.
pump setup (e.g. for diode-pumped lasers), influencing output power and beam quality, long-term stability, and the ease of exchanging pump diodes
optimum type of laser resonator (e.g. as linear or ring laser, with monolithic or with discrete elements) and optimized resonator design, influencing aspects like the number of parts, the output power and beam quality, alignment tolerances, sensitivity to thermal lensing, mechanical stability and drifts
selection and placement of laser mirrors and intracavity components for wavelength tuning, generation of short pulses via mode locking, dispersion compensation, frequency stabilization, etc.
mechanical housing, influencing mechanical stability, efficiency of cooling and temperature drifts, ease of maintenance, and safety issues
electronic equipment, e.g. for stabilizing the output power, controlling the laser wavelength, monitoring the status of pump diodes or temperatures, ensuring safe operation
proper documentation, including a part list (possibly with suppliers), mechanical designs, alignment and testing procedures, design ideas, possibly optional extensions and limitations for modifying operation parameters

This list, which is certainly not yet complete, shows that proper laser designs are not a trivial matter, but are essential for achieving full customer satisfaction, cost efficiency, and flexibility for future developments.

Laser applications

2008-01-26T00:30:00.000-08:00

Lasers are sources of light with very special properties, as discussed in the article on laser light. For that reasons, there is a great variety of laser applications. The following sections give an overview.

Manufacturing

Lasers are widely used in manufacturing, e.g. for cutting, welding, soldering, surface treatment, marking, micromachining, pulsed laser deposition, lithography, alignment, etc. In most cases, relatively high optical intensities are applied to a small spot, leading to intense heating, possibly evaporation and plasma generation. Essential aspects are the high spatial coherence of laser light, allowing for strong focusing, and often also the potential for generating intense pulses.

Laser processing methods have many advantages, when being compared to mechanical approaches. They allow to fabricate very fine structures with high quality, avoiding mechanical stress as caused e.g. by mechanical drills and blades. A laser beam with high beam quality can be used to drill very fine and deep holes, e.g. for injection nozzles. A high processing speed is often (but not always) achieved, and it can also be advantageous to process materials without touching them.

Medical Applications

There is a wide range of medical applications. Often these relate to the outer parts of the human body, which are easily reached with light; examples are eye surgery and vision correction (LASIK), dentistry, dermatology (e.g. photodynamic therapy of cancer), and various kinds of cosmetic treatment such as tattoo removal or hair removal.

Lasers are also used for surgery (e.g. of the prostate), exploiting the possibility to cut tissues while causing only a low amount of bleeding.

Very different types of lasers are required for medical applications, depending on the optical wavelength, output power, pulse format, etc. In many cases, the laser wavelength is chosen so that certain substances (e.g. pigments in tattoos or caries in teeth) absorb light more strongly than surrounding tissue, so that they can be more precisely targeted.

Medical lasers are not always used for therapy. Some of them rather assist the diagnosis e.g. via methods of laser microscopy or spectroscopy (see below).

Metrology

Lasers are widely used in optical metrology, e.g. for extremely precise position measurements with interferometers, for long-distance range finding and navigation.

Laser scanners are based on collimated laser beams, which can read e.g. bar codes or other graphics over some distance. It is also possible to scan three-dimensional objects, e.g. in the context of crime scene investigation (CSI).

Optical sampling is a technique applied for the characterization of fast electronic microcircuits, microwave photonics, terahertz science, etc.

Lasers also allow for extremely precise time measurements and are therefore essential ingredient of optical clocks which will soon outperform the currently used atomic cesium clocks.

Fiber-optic sensors, often probed with laser light, allow for the distributed measurement of temperature, stress, and other quantities e.g. in oil pipelines and wings of airplanes.

Data Storage

Optical data storage e.g. in compact disks (CDs), DVDs, HD-DVDs, blu-ray disks and magneto-optical disks, is nearly always relying on a laser source, which has a high spatial coherence and can thus be used to address very tiny spots in the recording medium, allowing a very high density data storage. Another case is holography, where the temporal coherence can also be important.

Communications

Optical fiber communications, extensively used particularly for long-distance optical data transmission, mostly relies on laser light in optical glass fibers. Free-space optical communications e.g. for inter-satellite communications is based on higher power lasers, generating collimated laser beams which propagate over large distances with small beam divergence.

Displays

Laser projection displays containing RGB sources can be used for cinemas, home videos, flight simulators, etc., and are often superior to other displays concerning possible screen dimensions, resolution and color saturation. Further reductions of manufacturing costs will be essential for deep market penetration.

Spectroscopy

Laser spectroscopy is useful e.g. in atmospheric physics and pollution monitoring (e.g. trace gas sensing with differential absorption LIDAR technology). It also plays a role in medicine (e.g. cancer detection), biology, and various types of fundamental research, partly related to metrology (see above).

Microscopy

Laser microscopes and setups for coherence tomography provide images e.g. of biological samples with very high resolution, often in three dimensions. It is also possible to realize functional imaging.

Various Scientific Applications

Laser cooling makes it possible to bring clouds of atoms or ions to extremely low temperatures. This has applications in fundamental research as well as for industrial purposes.

Laser guide stars are used in astronomical observatories in combination with adaptive optics for atmospheric correction. They allow a substantially increased image resolution even in cases where a sufficiently close-by natural guide star is not available.

Military Applications

There are various military laser applications. In relatively few cases, lasers are used as weapons; the "laser sword" has become quite popular via films, but not in practice. Some high power lasers are currently developed for potential use on the battle field, or for destroying missiles, projectiles and mines.

In other cases, lasers function as target designators or laser sights (essentially laser pointers emitting visible or invisible laser beams), or as irritating or blinding (normally not directly destroying) countermeasures e.g. against heat-seeking anti-aircraft missiles. It is also possible to temporarily or permanently blind soldiers with laser beams, although the latter is forbidden by rules of war.

There are also many laser applications which are not specific for military use, e.g. in areas like range finding, LIDAR, and optical communications.

Open source robot control software

2008-01-15T06:24:00.000-08:00

OROCOS (Open RObot COntrol Software) is an effort to start up an open source robot control software project. Broad discussions are being held about what experiences, code and tools can be re-used from other projects, what open standards should be integrated into the project and what organizational structure is most appropriate for the project. Goals of the project are to develop robot control software as follows:

Under open source and/or free software license(s)
As modular as possible
Of the highest quality (from both technical and software engineering perspectives)
Independent of (but compatible with) commercial robot manufacturers
For all sorts of robotic devices and computer platforms
Localized for all programming languages
Featuring configurable software components for kinematics, dynamics, planning, sensing, control, hardware interfacing, etc.

The project aims to become more than just a copy of existing commercial robot controllers or robot simulation/programming packages. The OROCOS project wants to develop shareable libraries, stand-alone components (sometimes referred to as software agents), and a configurable run-time environment from which to eliminate and control all distributed robotics systems. These types of projects are useful in several ways:

For re-using code
For use as an independent sub-system
For copying their organizational structure
For learning from the experience of managing an open source project
For designing and developing extensible and reusable software

Open source matrix libraries

The following are open source matrix libraries that satisfy the above-mentioned requirements. Octave is recommended, since it is GPL-licensed and delivers all required functionality.

GNU Octave: GNU Octave is a high-level language, primarily intended for numerical computations. It provides a convenient command line interface for solving linear and nonlinear problems numerically, and for performing other numerical experiments using a language that is mostly compatible with Matlab. It is easily extensible and customizable via user-defined functions written in Octave's own language, or using dynamically loaded modules written in C++, C, Fortran, or other languages.

GNU Octave is freely distributed software. You may redistribute it and/or modify it under the terms of the GNU General Public License (GPL) as published by the Free Software Foundation. More detailed information about GNU Octave can be found by visiting the Octave Web site (see Resources).

GSL (GNU Scientific Library) GSL is an ongoing effort to develop a modern extensive and ANSI C library for numerical computing. The GNU Scientific Library (GSL) is a collection of routines for numerical computing. The routines are written from scratch by the GSL team in ANSI C, and are meant to present a modern Applications Programming Interface (API) for C programmers, while allowing wrappers to be written for very high level languages.

GSL is free software. It is distributed under the terms of the GNU General Public License. Visit Red Hat's Web site (see Resources) for more information concerning GSL.

Real time kernels

Real-Time Linux (RTLinux) RTLinux(TM) is a hard real-time operating system that handles time-critical tasks and runs Linux as its lowest priority execution thread. In RTLinux, the kernel shares one or more processors with standard Linux. This allows the system to run accurately timed applications performing data acquisition, systems control and robotics, while still serving as a standard Linux workstation. Version 3.0 (final) is available on the Web at ftp.rtlinux.com (see Resources).

RTLinux.org is the non-commercial RTLinux site for the open source user and developer community. Their sister site, RTLinux.com (see Resources), discusses commercial support and development.

eCos (embedded Configurable operating system): eCos is an open source real-time operating system for deeply embedded applications. It meets the requirements of the embedded space that Linux cannot yet reach. Linux currently scales upwards from a minimal size of around 500 kilobytes of kernel and 1.5MB of RAM, before taking into consideration application and service requirements. The eCos open source project can be found at their Web site (see Resources).

RTEMS (GPL License): RTEMS is an open source real-time operating system and environment for C, C++ and Ada95. It is distributed under the terms of the GNU General Public License.

Visit the RTEMS site (see Resources) for downloads and more detailed information about RTEMS.

Utilities and tools

ROBOOP (A robotics object oriented package in C++): This package is an object-oriented toolbox in C++ for robotics simulation. Technical references and downloads are provided in the Resources.

CORBA: A real-time communications and object request broker software package for embedding distributed software agents. Each independent piece of software registers itself and its capabilities to the ORB, by means of an IDL (Interface Definition Language). Visit their Web site (see Resources) for technical information, downloads, and documentation for CORBA.

TANGO/TACO: This software might be useful for controlling a robotics system with multiple devices and tools. TANGO is an object oriented control system based on CORBA. Device servers can be written in C++ or Java. TACO is object oriented because it treats all (physical and logical) control points in a control system as objects in a distributed environment. All actions are implemented in classes. New classes can be constructed out of existing classes in a hierarchical manner, thereby ensuring a high level of software reuse. Classes can be written in C++, in C (using a methodology called Objects in C), in Python or in LabView (using the G programming language).

TACO was designed to be portable and runs on a large number of platforms (for example, Linux, Solaris, HP-UX, Windows/NT, Windows/95, and OS9). To download the source code and other technical documents visit their web site (see Resources).

Controllers

Task Control Architecture: The Task Control Architecture (TCA) simplifies building task-level control systems for mobile robots. "Task-level" refers to the integration and coordination of perception, planning, and real time control to achieve a given set of goals (tasks). TCA provides a general control framework, and is intended to control a wide variety of robots. TCA provides a high-level machine-independent method for passing messages between distributed machines (including between Lisp and C processes). TCA provides control functions, such as task decomposition, monitoring, and resource management, that are common to many mobile robot applications. The Resources section provides technical references and download information for Task Control Architecture.

EMC (Enhanced Machine Controller): The EMC software is based on the NIST Real time Control System (RCS) methodology, and is programmed using the NIST RCS Library. The RCS Library eases the porting of controller code to a variety of UNIX and Microsoft platforms, providing a neutral application programming interface (API) to operating system resources such as shared memory, semaphores and timers. The EMC software is written in C and C++, and has been ported to the PC Linux, Windows NT, and Sun Solaris operating systems.

Darwin2K: Darwin2K is a free, open source toolkit for robot simulation and automated design. It features numerous simulation capabilities and an evolutionary algorithm capable of automatically synthesizing and optimizing robot designs to meet task-specific performance objectives.

Languages

RoboML (Robotic Markup Language): RoboML is used for standardized representation of robotics-related data. It is designed to support communication language between human-robot interface agents, as well as between robot-hosted processes and between interface processes, and to provide a format for archived data used by human-robot interface agents.

ROSSUM: A programming and simulation environment for mobile robots. The Rossum Project is an attempt to help collect, develop, and distribute software for robotics applications. The Rossum Project hopes to extend the same kind of collaboration to the development of robotic software.

XRCL (Extensible Robot Control Language): XRCL (pronounced zircle) is a relatively simple, modern language and environment designed to allow robotics researchers to share ideas by sharing code. It is an open source project, protected by the GNU Copyleft.

Open System Architecture for Controls within Automation Systems (OSACA): OSACA is a joint European project that aims to improve the competitiveness of the manufacturers of machine tools and control systems in the world market. The main goal of the project is to specify system architecture for open control systems, which is manufacturer independent.

Mechanical platforms -- the hardware base of robots

2008-01-15T06:23:00.000-08:00

A robot consists of two main parts: the robot body and some form of artificial intelligence (AI) system. Many different body parts can be called a robot. Articulated arms are used in welding and painting; gantry and conveyor systems move parts in factories; and giant robotic machines move earth deep inside mines. One of the most interesting aspects of robots in general is their behavior, which requires a form of intelligence. The simplest behavior of a robot is locomotion. Typically, wheels are used as the underlying mechanism to make a robot move from one point to the next. And some force such as electricity is required to make the wheels turn under command.

Motors

A variety of electric motors provide power to robots, allowing them to move material, parts, tools, or specialized devices with various programmed motions. The efficiency rating of a motor describes how much of the electricity consumed is converted to mechanical energy. Let's take a look at some of the mechanical devices that are currently being used in modern robotics technology.

DC motor: Permanent-magnet, direct-current (PMDC) motors require only two leads, and use an arrangement of fixed- and electro-magnets (stator and rotor) and switches. These form a commutator to create motion through a spinning magnetic field.

AC motor: AC motors cycle the power at the input-leads, to continuously move the field. Given a signal, AC and DC motors perform their action to the best of their ability.

Stepper motor: Stepper motors are like a brushless DC or AC motor. They move the rotor by applying power to different magnets in the motor in sequence (stepped). Steppers are designed for fine control and will not only spin on command, but can spin at any number of steps-per-second (up to their maximum speed).

Servomotors: Servomotors are closed-loop devices. Given a signal, they adjust themselves until they match the signal. Servos are used in radio control airplanes and cars. They are simple DC motors with gearing and a feedback control system.

Driving mechanisms

Gears and chains: Gears and chains are mechanical platforms that provide a strong and accurate way to transmit rotary motion from one place to another, possibly changing it along the way. The speed change between two gears depends upon the number of teeth on each gear. When a powered gear goes through a full rotation, it pulls the chain by the number of teeth on that gear.

Pulleys and belts: Pulleys and belts, two other types of mechanical platforms used in robots, work the same way as gears and chains. Pulleys are wheels with a groove around the edge, and belts are the rubber loops that fit in that groove.

Gearboxes: A gearbox operates on the same principles as the gear and chain, without the chain. Gearboxes require closer tolerances, since instead of using a large loose chain to transfer force and adjust for misalignments, the gears mesh directly with each other. Examples of gearboxes can be found on the transmission in a car, the timing mechanism in a grandfather clock, and the paper-feed of your printer.

Power supplies

Power supplies are generally provided by two types of battery. Primary batteries are used once and then discarded; secondary batteries operate from a (mostly) reversible chemical reaction and can be recharged several times. Primary batteries have higher density and a lower self-discharge rate. Secondary (rechargeable) batteries have less energy than primary batteries, but can be recharged up to a thousand times depending on their chemistry and environment. Typically the first use of a rechargeable battery gives 4 hours of continuous operation in an application or robot.

Electronic control

There are two major hardware platforms in a robot. The mechanical platform of unregulated voltages, power and back-EMF spikes, and the electronic platform of clean power and 5-volt signals. These two platforms need to be bridged in order for digital logic to control mechanical systems. The classic component for this is a bridge relay. A control signal generates a magnetic field in the relay's coil that physically closes a switch. MOSFETs, for example, are highly efficient silicon switches, available in many sizes like the transistor that can operate as a solid state relay to control the mechanical systems.

On the other hand, larger sized robots may require a PMDC motor in which the value of the MOSFET's "on" resistance Rds(on) results in great increases in the heat dissipation of the chip, thereby significantly reducing the chip's heat temperature. Junction temperatures within the MOSFET and the coefficients of conduction of the MOSFET package and heat sink are other important characteristics of PMDC motors.

There are two broad families of transistor: bipolar junction transistors (BJT) and field-effect transistors (FET). In BJT devices, a small current flow at the base moderates a much larger current between the emitter and collector. In FET devices, the presence of an electrical field at the gate moderates the flow between the source and drain.

Sensors

Robots react according to a basic temporal measurement, requiring different kinds of sensors.

In most systems a sense of time is built-in through the circuits and programming. For this to be productive in practice, a robot has to have perceptual hardware and software, which updates quickly. Regardless of sensor hardware or software, sensing and sensors can be thought of as interacting with external events (in other words, the outside world). The sensor measures some attribute of the world. The term transducer is often used interchangeably with sensor. A transducer is the mechanism, or element, of the sensor that transforms the energy associated with what is being measured into another form of energy. A sensor receives energy and transmits a signal to a display or computer. Sensors use transducers to change the input signal (sound, light, pressure, temperature, etc.) into an analog or digital form capable of being used by a robot.

Logical sensors: One powerful abstraction of a sensor is a logical sensor, which is a unit of sensing or module that supplies a particular percept. It consists of the signal processing, from the physical sensor, and the software processing needed to extract the percept.

Proprioceptive sensors: Proprioception is dead reckoning, where the robot measures a signal originating within itself.

Proximity sensors: A proximity sensor measures the relative distance between the sensor and objects in the environment.

Infrared (IR) sensors: Another type of active proximity sensor is an infrared sensor. It emits near-infrared energy and measures whether any significant amount of the IR light is returned.

Bump and feeler sensors: Another popular class of robotic sensing is tactile, or touch-based, done with a bump and feeler sensor. Feelers or whiskers are constructed from sturdy wires. A bump sensor is usually a protruding ring around the robot consisting of two layers.

Introduction to robotics technology

2008-01-15T06:22:00.000-08:00

The word "robot" originates from the Czech word for forced labor, or serf. It was introduced by playwright Karel Capek, whose fictional robotic inventions were much like Dr. Frankenstein's monster -- creatures created by chemical and biological, rather than mechanical, methods. But the current mechanical robots of popular culture are not much different from these fictional biological creations. Basically a robots consists of:

A mechanical device, such as a wheeled platform, arm, or other construction, capable of interacting with its environment
Sensors on or around the device that are able to sense the environment and give useful feedback to the device
Systems that process sensory input in the context of the device's current situation and instruct the device to perform actions in response to the situation

In the manufacturing field, robot development has focused on engineering robotic arms that perform manufacturing processes. In the space industry, robotics focuses on highly specialized, one-of-kind planetary rovers. Unlike a highly automated manufacturing plant, a planetary rover operating on the dark side of the moon -- without radio communication -- might run into unexpected situations. At a minimum, a planetary rover must have some source of sensory input, some way of interpreting that input, and a way of modifying its actions to respond to a changing world. Furthermore, the need to sense and adapt to a partially unknown environment requires intelligence (in other words, artificial intelligence).

From military technology and space exploration to the health industry and commerce, the advantages of using robots have been realized to the point that they are becoming a part of our collective experience and every day lives.

They function to relieve us from danger and tedium:

Safety: Robotics have been developed to handle nuclear and radioactive chemicals for many different uses including nuclear weapons, power plants, environmental cleanup, and the processing of certain drugs.
Unpleasantness: Robots perform many tasks that are tedious and unpleasant, but necessary, such as welding or janitorial work.
Repetition and precision: Assembly line work has been one of the mainstays of the robotics industry. Robots are used extensively in manufacturing and, more glamorously, in space exploration, where minimum maintenance requirements are emphasized.

benefits of IT

2007-12-30T06:13:00.000-08:00

For an organization to improve its business process using technology, an IT department is mandatory for management and support of the infrastructure.

An IT department is required for these areas of technology to provide value to the business, because maintenance tasks must be performed by technically competent staff.

		End-User Technical Support
		Desktop Management
		Network Management
		Voice and Data Communications
		Business Applications
		Strategic Technology Planning
		Project Management

Besides using technology efficiently, an IT department will also provide a business with lower costs, higher productivity and higher efficiency in other areas. The IT department does this by:

Avoids losing revenues

Lost sales from customers being unable to make purchases

Decreases costs

Payroll for employees being idle

Paying a technician to fix the problem

Increases productivity because employees will spend less time idle

Increases efficiency by assuring that persons handling technology issues are knowledgeable in the area

Increases productivity by allowing employees to focus on core competencies rather than technology issues

Reduces risk of financial, technological and data losses caused by disasters

Increases return on investment (ROI) and business value realized from technology projects

Improves equipment efficiency with planned maintenance activities

Types of technology

2007-12-16T10:31:00.000-08:00

To many of us, the term technology conjures up visions of things such as computers, cell phones, spaceships, digital video players, computer games, advanced military equipment, and other highly sophisticated machines. Such perceptions have been acquired and reinforced through exposure to televised reports of fascinating devices and news articles about them, science fiction books and movies, and our use of equipment such as automobiles, telephones, computers, and automatic teller machines.
While this focus on devices and machines seems to be very prevalent among the general population, many educators also hold a similar perspective. Since Pressey developed the first teaching machine in 1926 (Nazzaro, 1977), technology applications in public schools and post-secondary education institutions have tended to focus on the acquisition and use of equipment such as film projectors, audio and video tape recorders, overhead projectors, and computers.

Since the early 1960s, however, a trend has emerged that is changing the way we perceive technology in education. At that time, educators began considering the concept of instructional technology. Subsequently, after considerable deliberation, a Congressional Commission on Instructional Technology (1970) concluded that technology involved more than just hardware. The Commission concluded that, in addition to the use of devices and equipment, instructional technology also involves a systematic way of designing and delivering instruction.

With the rapid development of microcomputer technology, increased research on instructional procedures, and the invention of new devices and equipment to aid those with health problems, physical disabilities, and sensory impairments, the latter third of the 20th century has borne witness to a very dramatic evolution. The current perspective is a broad one in which six types of technology are recognized: the technology of teaching, instructional technology, assistive technology, medical technology, technology productivity tools, and information technology (Blackhurst & Edyburn, 2000).

TECHNOLOGY OF TEACHING

The technology of teaching refers to instructional approaches that are very systematically designed and applied in very precise ways. Such approaches typically include the use of well-defined objectives, precise instructional procedures based upon the tasks that students are required to learn, small units of instruction that are carefully sequenced, a high degree of teacher activity, high levels of student involvement, liberal use of reinforcement, and careful monitoring of student performance.
Instructional procedures that embody many of these principles include approaches such as direct instruction (Carnine, Silbert, & Kameenui, 1990), applied behavior analysis (Alberto & Troutman, 1995; Wolery, Bailey, & Sugai, 1988), learning strategies (Deshler & Schumaker, 1986), and response prompting (Wolery, Ault, & Doyle, 1992). Most often, machines and equipment are not involved when implementing various technologies of teaching; however, they can be, as will be seen later.
MEDICAL TECHNOLOGY
The field of medicine continues to amaze us with the advances constantly being made in medical technology. In addition to seemingly miraculous surgical procedures that are technology-based, many individuals are dependent upon medical technology to stay alive or otherwise enable people to function outside of hospitals and other medical settings. It is not uncommon to see people in their home and community settings who use medical technology.
For example, artifical limbs and hip and knee implants can help people function in the environment. Cochlear implants can often improve the hearing of people with auditory nerve damage. Some devices provide respiratory assistance through oxygen supplementation and mechanical ventilation. Others, such as cardiorespiratory monitors and pulse oximeters are used as surveillance devices that alert an attendant to a potential vitality problem. Nutritive assistive devices can assist in tube feeding or elimination through ostomies. Intravenous therapy can be provided through medication infusion and kidney function can be assumed by kidney dialysis machines (Batshaw & Perret, 1992). In addition to keeping people alive, technologies such as these can enable people to fully participate in school, community, and work activities.

GSM Technology

2007-12-10T05:13:00.000-08:00

What is GSM?

GSM (Global System for Mobile communications) is an open, digital cellular technology used for transmitting mobile voice and data services. GSM differs from first generation wireless systems in that it uses digital technology and time division multiple access transmission methods. GSM is a circuit-switched system that divides each 200kHz channel into eight 25kHz time-slots. GSM operates in the 900MHz and 1.8GHz bands in Europe and the 1.9GHz and 850MHz bands in the US. The 850MHz band is also used for GSM and 3GSM in Australia, Canada and many South American countries. GSM supports data transfer speeds of up to 9.6 kbit/s, allowing the transmission of basic data services such as SMS (Short Message Service). Another major benefit is its international roaming capability, allowing users to access the same services when travelling abroad as at home. This gives consumers seamless and same number connectivity in more than 210 countries. GSM satellite roaming has also extended service access to areas where terrestrial coverage is not available.

Did you know that you can be instantly contactable on your usual number in over 100 countries world wide, when you travel with your GSM phone using your own number?

The major advantage of GSM technology is that it allows you to use your GSM phone when you travel outside your own country or region. This is known as roaming.

Roaming is the ability to use your own GSM phone number in another GSM network. You can roam to another region or country and use the services of any network operator in that region that has a roaming agreement with your GSM network operator in your home region/country.

A roaming agreement is a business agreement between two network operators to transfer items such as call charges and subscription information back and forth, as their subscribers roam into each other's areas.

General Packet Radio Services (GPRS)

2007-12-10T05:07:00.000-08:00

- General Packet Radio Services (GPRS) is a packet-based wireless communication service that promises data rates from 56 up to 114 Kbps and continuous connection to the Internet for mobile phone and computer users. The higher data rates allow users to take part in video conferences and interact with multimedia Web sites and similar applications using mobile handheld devices as well as notebook computers. GPRS is based on Global System for Mobile (GSM) communication and complements existing services such circuit-switched cellular phone connections and the Short Message Service (SMS).

In theory, GPRS packet-based services cost users less than circuit-switched services since communication channels are being used on a shared-use, as-packets-are-needed basis rather than dedicated to only one user at a time. It is also easier to make applications available to mobile users because the faster data rate means that middleware currently needed to adapt applications to the slower speed of wireless systems are no longer be needed. As GPRS has become more widely available, along with other 2.5G and 3G services, mobile users of virtual private networks (VPNs) have been able to access the private network continuously over wireless rather than through a rooted dial-up connection.

GPRS also complements Bluetooth, a standard for replacing wired connections between devices with wireless radio connections. In addition to the Internet Protocol (IP), GPRS supports X.25, a packet-based protocol that is used mainly in Europe. GPRS is an evolutionary step toward Enhanced Data GSM Environment (EDGE) and Universal Mobile Telephone Service (UMTS).

The Great Technology War: LCD vs. DLP

2007-12-10T04:58:00.000-08:00

Introduction

If you are new to the world of digital projectors, you won't have to shop around the market very long before discovering that "LCD" and "DLP" somehow refers to two different kinds of projectors. You might not even know what LCD and DLP are before asking the obvious question "which one is better?"

The answer is simple. Sort of. LCD and DLP each have unique advantages over the other. Neither one is perfect. So it is important to understand what each one gives you. Then you can make a good decision about which will be better for you.

By the way, there is a third very significant light engine technology called LCOS (liquid crystal on silicon). It is being developed by several vendors, most notably JVC and Hitachi. Several outstanding home theater projectors have been manufactured with this technology, and JVC's LCOS-based DLA-SX21 is currently on our list of Highly Recommended Home Theater Projectors. However the discussion of LCOS technology is beyond the scope of this article. For more on LCOS click here.

The Technical Differences between LCD and DLP

LCD (liquid crystal display) projectors usually contain three separate LCD glass panels, one each for red, green, and blue components of the image signal being fed into the projector. As light passes through the LCD panels, individual pixels ("picture elements") can be opened to allow light to pass or closed to block the light, as if each little pixel were fitted with a Venetian blind. This activity modulates the light and produces the image that is projected onto the screen.

DLP ("Digital Light Processing") is a proprietary technology developed by Texas Instruments. It works quite differently than LCD. Instead of having glass panels through which light is passed, the DLP chip is a reflective surface made up of thousands of tiny mirrors. Each mirror represents a single pixel.

In a DLP projector, light from the projector's lamp is directed onto the surface of the DLP chip. The mirrors wobble back and forth, directing light either into the lens path to turn the pixel on, or away from the lens path to turn it off.

In very expensive DLP projectors, there are three separate DLP chips, one each for the red, green, and blue channels. However, in DLP projectors under $20,000, there is only one chip. In order to define color, there is a color wheel that consists of red, green, blue, and sometimes white (clear) filters. This wheel spins between the lamp and the DLP chip and alternates the color of the light hitting the chip from red to green to blue. The mirrors tilt away from or into the lens path based upon how much of each color is required for each pixel at any given moment in time. This activity modulates the light and produces the image that is projected onto the screen.

The Advantages of LCD Technology

One benefit of LCD is that it has historically delivered better color saturation than you get from a DLP projector. That's primarily because in most single-chip DLP projectors, a clear (white) panel is included in the color wheel along with red, green, and blue in order to boost brightest, or total lumen output. Though the image is brighter than it would otherwise be, this tends to reduce color saturation, making the DLP picture appear not quite as rich and vibrant. However, some of the DLP-based home theater products now have six-segment color wheels that eliminate the white component. This contributes to a richer display of color. And even some of the newer high contrast DLP units that have a white segment in the wheel are producing better color saturation than they used to. Overall however, the best LCD projectors still have a noteworthy performance advantage in this area.

LCD also delivers a somewhat sharper image than DLP at any given resolution. The difference here is more relevant for detailed financial spreadsheet presentations than it is for video. This is not to say that DLP is fuzzy--it isn't. When you look at a spreadsheet projected by a DLP projector it looks clear enough. It's just that when a DLP unit is placed side-by-side with an LCD of the same resolution, the LCD typically looks sharper in comparison.

A third benefit of LCD is that it is more light-efficient. LCD projectors usually produce significantly higher ANSI lumen outputs than do DLPs with the same wattage lamp. In the past year, DLP machines have gotten brighter and smaller--and there are now DLP projectors rated at 2500 ANSI lumens, which is a comparatively recent development. Still, LCD competes extremely well when high light output is required. All of the portable light cannons under 20 lbs putting out 3500 to 5000 ANSI lumens are LCD projectors.

The Weaknesses of LCD Technology

LCD projectors have historically had two weaknesses, both of which are more relevant to video than they are to data applications. The first is visible pixelation, or what is commonly referred to as the "screendoor effect" because it looks like you are viewing the image through a screendoor. The second weakness is not-so-impressive black levels and contrast, which are vitally important elements in a good video image. LCD technology has traditionally had a hard time being taken seriously among some home theater enthusiasts (understandably) because of these flaws in the image.

However, in many of today's projectors these flaws aren't nearly what they used to be. Three developments have served to reduce the screendoor problem on LCD projectors. First was the step up to higher resolutions, first to XGA resolution (1,024x768), and then to widescreen XGA (WXGA, typically either 1280x720 or 1365x768). This widescreen format is found, for example, on the Sanyo PLV-70 and Epson TW100, (two more products currently on our Highly Recommended list). Standard XGA resolution uses 64% more pixels to paint the image on the screen than does an SVGA (800x600) projector. The inter-pixel gaps are reduced in XGA resolution, so pixels are more dense and less visible. Then with the widescreen 16:9 machines, the pixel count improves by another quantum leap. While an XGA projector uses about 589,000 pixels to create a 16:9 image, a WXGA projector uses over one million. At this pixel density, the screendoor effect is eliminated at normal viewing distances.

Second, the inter-pixel gaps on all LCD machines, no matter what resolution, are reduced compared to what they use to be. So even today's inexpensive SVGA-resolution LCD projectors have less screendoor effect than older models did. And it is virtually invisible on the Panasonic PT-L300U, which is a medium resolution widescreen format of 960x540.

The third development in LCDs was the use of Micro-Lens Array (MLA) to boost the efficiency of light transmission through XGA-resolution LCD panels. Some XGA-class LCD projectors have this feature, but most do not. For those that do, MLA has the happy side effect of reducing pixel visibility a little bit as compared to an XGA LCD projector without MLA. On some projectors with this feature, the pixel grid can also be softened by placing the focus just a slight hair off perfect, a practice recommended for the display of quality video. This makes the pixels slightly indistinct without any noticeable compromise in video image sharpness.

Now when it comes to contrast, LCD still lags behind DLP by a considerable margin. But recent major improvements in LCD's ability to render higher contrast has kept LCD machines in the running among home theater enthusiasts. All of the LCD projectors just mentioned have contrast ratios of at least 800:1. They produce much more snap, better black levels, and better shadow detail than the LCD projectors of years past were able to deliver.

Health Risks due to infrared

2007-12-07T23:02:00.000-08:00

Imagine for a moment going about your daily routine without electricity. You probably awoke to an electric clock radio/alarm, showered under warm water supplied via an electric hot water heater, drank a couple of cups of coffee from your automatic electric coffee maker, listened to the weather on the electric powered TV or radio - and the list goes on and on. We live in an electrical environment!

Electricity is all around you and while you cannot see electricity, you can certainly appreciate the results. However, any time electric current travels through a wire, the air, or runs an appliance, it produces an electromagnetic field. It is important to remember that electromagnetic fields are found everywhere that electricity is in use. While researchers have not established an ironclad link between the exposure to electromagnetic fields and ailments such as leukemia, the circumstantial evidence concerns many people.

The evidence also suggests that we need to use some common sense when dealing with electricity. In scientific terms, your body can act as an antenna, as it has a higher conductivity for electricity than does air. Therefore, when conditions are right you may have experienced a small "tingle" of electric current from a poorly grounded electric appliance. As long as these currents are very small there isn't much danger from electric fields, except for potential shocks. Your body, however, also has a permeability almost equal to air, thus allowing a magnetic field to easily enter the body. Unfortunately your body cannot detect the presence of a strong magnetic field, which could potentially do much more harm.

In terms of wireless technology, there are no confirmed health risks or scientific dangers from infrared or radio frequency, with two known exceptions:

point-to-point lasers which can cause burns or blindness
prolonged microwave exposure which has been linked to cancer and leukemia

Therefore, most health concerns related to electromagnetic fields are due to electricity in our day-to-day use, such as computer monitors and TVs. These dangers, if any, are already in the home and work place, and the addition of wireless technology should not be seen as an exceptional risk. We might be rightfully worried or concerned about the electric power grid two blocks from our home or school, but at the same time, we sleep each night with our head only a few feet from an AC powered clock radio, which may be far worse due simply to proximity. We might be also be worried about the magnetic radiation or magnetically induced electrical fields which surround us from the fluorescent light fixtures and high voltage, high frequency lighting we sit under at work and at home. The real danger, however, is that we normally position ourselves too close to the electromagnetic field source (computer monitor, TV, etc.). Remember that the strength of the electromagnetic field (EMF) decreases as the square of the distance from the field source. Therefore, if we are 2 meters away from the source, the EMF strength is reduced to 1/4, but if we move 8 meters away from the source, the EMF strength is reduced to 1/64 of its original strength.

Safety

There are a few things you can do to make your home and work environment a safer "electronic" place. The first thing to consider when possible is to buy Federal Communications Commission (FCC) Class B rated equipment. The FCC classifies computer equipment for its potential to generate radio frequency pollution. Class B emits less radio frequency pollution than Class A, and is more suitable for the residential environment. Unfortunately, while Class B emits less radio frequency pollution, there is nothing in the FCC classes regarding magnitude or level of the pollution.

Other potential risks exist in high voltage (e.g. power) components such as display monitors, computer power supplies, etc. If possible select low power units, shielded units, etc. and operate them at lower resolutions. For example, VGA resolution has a lower refresh scan rate than SVGA, and thus lower magnetic field pollution. If you are adding internal cards to your computers, don't tamper with the computer by removing any internal shielding, covers, etc. Any metal shielding inside your computer was probably put there for a purpose, although to you it may look like a harmless spacer!

If you are really concerned, you can purchase formal safety testing tools or hire a consultant to do formal testing for EMF. There are also cheap tools you can utilize to test for the presence of strong radio or magnetic fields. For example, the presence of a strong magnetic field will deflect a compass needle from pointing north, or the presence of a strong radio frequency field will distort an AM radio's ability to clearly tune in a station. Simple tools like these can be used to screen for strong EMF.

Security

Electromagnetic frequencies currently have little legal status for protection and as such, can be freely intercepted by motivated individuals. This doesn't mean wireless transmission is easily breached, as security varies by the type of wireless transmission method. As presented earlier in the advantages and disadvantages of infrared versus radio frequency transmission, what might be considered an advantage to one method for transmission could turn out to be a disadvantage for security. For example, because infrared is line-of-sight it has less transmission range but is also more difficult to intercept when compared to radio frequency. Radio frequency can penetrate walls, making it much easier to transmit a message, but also more susceptible to tapping.

A possible solution to security issues will likely be some form of data encryption. Data encryption standards (DES) are also being quickly developed for the exchange of information over the Internet, and many of these same DES will be applied to wireless technology.

An Introduction to Infrared Technology

2007-12-07T22:59:00.000-08:00

As next-generation electronic information systems evolve, it is critical that all people have access to the information available via these systems. Examples of developing and future information systems include interactive television, touchscreen-based information kiosks, and advanced Internet programs. Infrared technology, increasingly present in mainstream applications, holds great potential for enabling people with a variety of disabilities to access a growing list of information resources. Already commonly used in remote control of TVs, VCRs and CD players, infrared technology is also being used and developed for remote control of environmental control systems, personal computers, and talking signs.

For individuals with mobility impairments, the use of infrared or other wireless technology can facilitate the operation of information kiosks, environmental control systems, personal computers and associated peripheral devices. For individuals with visual impairments, infrared or other wireless communication technology can enable users to locate and access talking building directories, street signs, or other assistive navigation devices. For individuals using augmentative and alternative communication (AAC) devices, infrared or other wireless technology can provide an alternate, more portable, more independent means of accessing computers and other electronic information systems.

In this presentation/paper, an introduction to wireless communication in general is first presented. A discussion specific to infrared technology then follows, with advantages and disadvantages of the technology presented along with security, health and safety issues. The importance of establishing a standard is also discussed with relevance to the disability field, and future uses of infrared technology are presented.

Wireless Communication

Wireless communication, as the term implies, allows information to be exchanged between two devices without the use of wire or cable. A wireless keyboard sends information to the computer without the use of a keyboard cable; a cellular telephone sends information to another telephone without the use of a telephone cable. Changing television channels, opening and closing a garage door, and transferring a file from one computer to another can all be accomplished using wireless technology. In all such cases, information is being transmitted and received using electromagnetic energy, also referred to as electromagnetic radiation. One of the most familiar sources of electromagnetic radiation is the sun; other common sources include TV and radio signals, light bulbs and microwaves. To provide background information in understanding wireless technology, the electromagnetic spectrum is first presented and some basic terminology defined.

The electromagnetic spectrum classifies electromagnetic energy according to frequency or wavelength (both described below). As shown in Figure 1, the electromagnetic spectrum ranges from energy waves having extremely low frequency (ELF) to energy waves having much higher frequency, such as x-rays.

[Figure 1 description: The electromagnetic spectrum is depicted in Figure 1. A horizontal bar represents a range of frequencies from 10 Hertz(cycles per second) to 10 to the 18th power Hertz. Some familiar allocated frequency bands are labeled on the spectrum. Approximate locations are as follows. (Exponential powers of 10 are abbreviated as 10exp.)

10 Hertz: extremely low frequency or ELF.
10exp5 Hertz: AM radio.
10exp8 Hertz: FM radio.
10exp10 Hertz: Television.
10exp11 Hertz: Microwave.
10exp16 Hertz: Infrared (frequency range is below the visible light spectrum).
10exp16 Hertz: Visible Light.
10exp16 Hertz: Ultraviolet (frequency range is above the visible light spectrum).
10exp18 Hertz: X-rays.]

A typical electromagnetic wave is depicted in Figure 2, where the vertical axis represents the amplitude or strength of the wave, and the horizontal axis represents time. In relation to electromagnetic energy, frequency is:

the number of cycles a wave completes (or the number of times a wave repeats itself) in one second
expressed as Hertz (Hz), which equals once cycle per second
commonly indicated by prefixes such as
a. Kilo (KHz) one thousand
b. Mega (MHz) one million
c. Giga (GHz) one billion
directly related to the amount of information that can be transmitted on the wave

[Figure 2 description: A sine wave is depicted in the graph in Figure 2. The horizontal axis of the graph represents time, and the vertical axis of the graph represents amplitude. One cycle (or one complete sine wave) is labeled on the graph.]

[Figure 3 description: Graphs of three different sine waves are depicted in Figure 3. The horizontal axis, with values ranging from 0 to 1, represents time in seconds. The vertical axis, with values ranging from -1 to 1, represents arbitrary amplitude. The first graph in the figure depicts a sine wave with a frequency of 1 cycle per second. As shown, the energy wave makes a complete cycle from 0 to its maximum positive value, then through to its maximum negative value, then back to 0. The second graph in the figure depicts a sine wave with a frequency of 2 cycles per second. The sine wave therefore makes 2 complete cycles of moving from 0 to its maximum positive value, through to its maximum negative value, and back to 0, in the same time that the wave in the first graph completes 1 cycle. The third graph in the figure depicts a sine wave with a frequency of 3 cycles per second. The sine wave therefore completes 3 full cycles in the same amount of time that the wave in the first graph completes 1 cycle.]

Figure 3 illustrates energy waves completing one cycle, two cycles and three cycles per second. Generally, the higher the range of frequencies (or bandwidth), the more information can be carried per unit of time.

The term wavelength is used almost interchangeably with frequency. In relation to electromagnetic energy, wavelength is:

the shortest distance at which the wave pattern fully repeats itself
expressed as meters
commonly indicated by prefixes such as
a. Kilo (km) 10exp3
b. Milli (mm) 10exp-3
c. Nano (nm) 10exp-9
inversely proportional to frequency

Figure 4 depicts an infrared energy wave and a radio energy wave, and illustrates the two different energy wavelengths. As is expected based on the electromagnetic spectrum, the infrared wave is higher frequency and therefore shorter wavelength than the radio wave. Conversely, the radio wave is lower frequency and therefore longer wavelength than the infrared wave. Anyone who has listened to the radio while driving long distances can appreciate that longer wavelength AM radio waves carry further than the shorter wavelength FM radio waves.

[Figure 4 description: Figure 4 depicts a radio frequency energy wave superimposed upon an infrared energy wave, and illustrates the inverse relationship between frequency and wavelength. The infrared energy wave completes nearly 5 and a half cycles in the time that the radio frequency wave completes 2 cycles. The wavelengths of the infrared wave and the radio wave are labeled, and the infrared wavelength is less than half the wavelength of the radio wave.]

Other terms commonly used in describing wireless communication include transmitter, receiver, and transceiver. In any type of wireless technology, information must be sent (or transmitted) by one device and captured (or received) by another device. The transmitter takes its input - a voice or stream of data bits for example, creates an energy wave that contains the information, and sends the wave using an appropriate output device. As an example, a radio transmitter outputs its energy waves using an antenna, while an infrared transmitter uses an infrared light- emitting diode (LED) or laser diode. The electromagnetic energy waves are captured by the receiver, which then processes the waves to retrieve and output the information in its original form. Any wireless device having the circuitry to both transmit and receive energy signals is referred to as a transceiver. Depending on the communication protocol being used, a device may be capable of only transmitting or receiving information at one time, or it may be capable of both transmitting and receiving information at the same time.

The above described terminology is relevant in all forms of wireless communication, regardless of the band of electromagnetic energy (radio, infrared, etc.) being used. Although radio and ultrasound waves have frequent application in wireless communication, the remainder of the presentation/paper is devoted more specifically to infrared (IR) technology. Infrared technology is highlighted because of its increasing presence in mainstream applications, its current and potential usage in disability-related applications, and its advantages over other forms of wireless communication.

Nanorobotics

2007-12-05T02:37:00.000-08:00

Nanorobotics is an emerging field that deals with the controlled manipulation of objects with nanometer-scale dimensions. Typically, an atom has a diameter of a few Ångstroms (1 Å = 0.1 nm = 10^-10 m), a molecule's size is a few nm, and clusters or nanoparticles formed by hundreds or thousands of atoms have sizes of tens of nm. Therefore, Nanorobotics is concerned with interactions with atomic- and molecular-sized objects-and is sometimes called Molecular Robotics. We use these two expressions, plus Nanomanipulation, as synonyms in this article.

Molecular Robotics falls within the purview of Nanotechnology, which is the study of phenomena and structures with characteristic dimensions in the nanometer range. The birth of Nanotechnology is usually associated with a talk by Nobel-prize winner Richard Feynman entitled "There is plenty of room at the bottom", whose text may be found in [Crandall & Lewis 1992]. Nanotechnology has the potential for major scientific and practical breakthroughs. Future applications ranging from very fast computers to self-replicating robots are described in Drexler's seminal book [Drexler 1986]. In a less futuristic vein, the following potential applications were suggested by well-known experimental scientists at the Nano4 conference held in Palo Alto in November 1995:

Cell probes with dimensions ~ 1/1000 of the cell's size
Space applications, e.g. hardware to fly on satellites
Computer memory
Near field optics, with characteristic dimensions ~ 20 nm
X-ray fabrication, systems that use X-ray photons
Genome applications, reading and manipulating DNA
Nanodevices capable of running on very small batteries
Optical antennas

Nanotechnology is being pursued along two converging directions. From the top down, semiconductor fabrication techniques are producing smaller and smaller structures-see e.g. [Colton & Marrian 1995] for recent work. For example, the line width of the original Pentium chip is 350 nm. Current optical lithography techniques have obvious resolution limitations because of the wavelength of visible light, which is in the order of 500 nm. X-ray and electron-beam lithography will push sizes further down, but with a great increase in complexity and cost of fabrication. These top-down techniques do not seem promising for building nanomachines that require precise positioning of atoms or molecules.

Alternatively, one can proceed from the bottom up, by assembling atoms and molecules into functional components and systems. There are two main approaches for building useful devices from nanoscale components. The first is based on self-assembly, and is a natural evolution of traditional chemistry and bulk processing-see e.g. [Gómez-López et al. 1996]. The other is based on controlled positioning of nanoscale objects, direct application of forces, electric fields, and so on. The self-assembly approach is being pursued at many laboratories. Despite all the current activity, self-assembly has severe limitations because the structures produced tend to be highly symmetric, and the most versatile self-assembled systems are organic and therefore generally lack robustness. The second approach involves Nanomanipulation, and is being studied by a small number of researchers, who are focusing on techniques based on Scanning Probe Microscopy (abbreviated SPM, and described later in this article).

A top-down technique that is closely related to Nanomanipulation involves removing or depositing small amounts of material by using an SPM. This approach falls within what is usually called Nanolithography. SPM-based Nanolithography is akin to machining or to rapid prototyping techniques such as stereolithography. For example, one can remove a row or two of hydrogen atoms on a silicon substrate that has been passivated with hydrogen by moving the tip of an SPM in a straight line over the substrate and applying a suitable voltage. The removed atoms are "lost" to the environment, much like metal chips in a machining operation. Lines with widths in the order of 10 to 100 nm have been written by these techniques-see e.g. [Wiesendanger 1994] for a survey of some of this work. In this article we focus on Nanomanipulation proper, which is akin to assembly in the macroworld.

Nanorobotics research has proceeded along two lines. The first is devoted to the design and computational simulation of robots with nanoscale dimensions-see [Drexler 1992] for the design of robots that resemble their macroscopic counterparts. Drexler's nanorobot uses various mechanical components such as nanogears built primarily with carbon atoms in a diamondoid structure. A major issue is how to build these devices, and little experimental progress has been made towards their construction.

The second area of Nanorobotics research involves manipulation of nanoscale objects with macroscopic instruments. Experimental work has been focused on this area, especially through the use of SPMs as robots. The remainder of this article describes SPM principles, surveys SPM use in Nanomanipulation, looks at the SPM as a robot, and concludes with a discussion of some of the challenges that face Nanorobotics research.

Figure 3 - The initial pattern of 15 nm Au balls (left) and the "USC" pattern obtained by nanomanipulation (right).

Figure 4 - The "USC" pattern viewed in perspective

Nanotechnology

2007-12-05T02:33:00.002-08:00

Manufactured products are made from atoms. The properties of those products depend on how those atoms are arranged. If we rearrange the atoms in coal we can make diamond. If we rearrange the atoms in sand (and add a few other trace elements) we can make computer chips. If we rearrange the atoms in dirt, water and air we can make potatoes.

Todays manufacturing methods are very crude at the molecular level. Casting, grinding, milling and even lithography move atoms in great thundering statistical herds. It's like trying to make things out of LEGO blocks with boxing gloves on your hands. Yes, you can push the LEGO blocks into great heaps and pile them up, but you can't really snap them together the way you'd like.

In the future, nanotechnology will let us take off the boxing gloves. We'll be able to snap together the fundamental building blocks of nature easily, inexpensively and in most of the ways permitted by the laws of physics. This will be essential if we are to continue the revolution in computer hardware beyond about the next decade, and will also let us fabricate an entire new generation of products that are cleaner, stronger, lighter, and more precise.

It's worth pointing out that the word nanotechnology has become very popular and is used to describe many types of research where the characteristic dimensions are less than about 1,000 nanometers. For example, continued improvements in lithography have resulted in line widths that are less than one micron: this work is often called "nanotechnolog." Sub-micron lithography is clearly very valuable (ask anyone who uses a computer!) but it is equally clear that conventional lithography will not let us build semiconductor devices in which individual dopant atoms are located at specific lattice sites. Many of the exponentially improving trends in computer hardware capability have remained steady for the last 50 years. There is fairly widespread belief that these trends are likely to continue for at least another several years, but then conventional lithography starts to reach its limits.

If we are to continue these trends we will have to develop a new manufacturing technology which will let us inexpensively build computer systems with mole quantities of logic elements that are molecular in both size and precision and are interconnected in complex and highly idiosyncratic patterns.Nanotechnology will let us do this.

When it's unclear from the context whether we're using the specific definition of nanotechnology (given here) or the broader and more inclusive definition (often used in the literature), we'll use the terms molecularnanotechnology or "molecular manufacturing."

Whatever we call it, it should let us

Get essentially every atom in the right place.
Make almost any structure consistent with the laws of physics that we can specify in molecular detail.
Have manufacturing costs not greatly exceeding the cost of the required raw materials and energy.

Nanotechnology

2007-12-05T02:33:00.001-08:00

Whatever we call it, it should let us

Get essentially every atom in the right place.
Make almost any structure consistent with the laws of physics that we can specify in molecular detail.
Have manufacturing costs not greatly exceeding the cost of the required raw materials and energy.

Introduction to Multithreading, Superthreading and Hyperthreading

2007-12-05T02:28:00.000-08:00

Introduction

Back in the dual-Celeron days, when symmetric multiprocessing (SMP) first became cheap enough to come within reach of the average PC user, many hardware enthusiasts eager to get in on the SMP craze were asking what exactly (besides winning them the admiration and envy of their peers) a dual-processing rig could do for them. It was in this context that the PC crowd started seriously talking about the advantages of multithreading. Years later when Apple brought dual-processing to its PowerMac line, SMP was officially mainstream, and with it multithreading became a concern for the mainstream user as the ensuing round of benchmarks brought out the fact you really needed multithreaded applications to get the full benefits of two processors.

Even though the PC enthusiast SMP craze has long since died down and, in an odd twist of fate, Mac users are now many times more likely to be sporting an SMP rig than their x86-using peers, multithreading is once again about to increase in importance for PC users. Intel's next major IA-32 processor release, codenamed Prescott, will include a feature called simultaneous multithreading (SMT), also known as hyper-threading. To take full advantage of SMT, applications will need to be multithreaded; and just like with SMP, the higher the degree of multithreading the more performance an application can wring out of Prescott's hardware.

Intel actually already uses SMT in a shipping design: the Pentium 4 Xeon. Near the end of this article we'll take a look at the way the Xeon implements hyper-threading; this analysis should give us a pretty good idea of what's in store for Prescott. Also, it's rumored that the current crop of Pentium 4's actually has SMT hardware built-in, it's just disabled. (If you add this to the rumor about x86-64 support being present but disabled as well, then you can get some idea of just how cautious Intel is when it comes to introducing new features. I'd kill to get my hands on a 2.8 GHz P4 with both SMT and x86-64 support turned on.)

SMT, in a nutshell, allows the CPU to do what most users think it's doing anyway: run more than one program at the same time. This might sound odd, so in order to understand how it works this article will first look at how the current crop of CPUs handles multitasking. Then, we'll discuss a technique called superthreading before finally moving on to explain hyper-threading in the last section. So if you're looking to understand more about multithreading, symmetric multiprocessing systems, and hyper-threading then this article is for you.

As always, if you've read some of my previous tech articles you'll be well equipped to understand the discussion that follows. From here on out, I'll assume you know the basics of pipelined execution and are familiar with the general architectural division between a processor's front end and its execution core. If these terms are mysterious to you, then you might want to reach way back and check out my "Into the K7" article, as well as some of my other work on the P4 and G4e.

Conventional multithreading

Quite a bit of what a CPU does is illusion. For instance, modern out-of-order processor architectures don't actually execute code sequentially in the order in which it was written. I've covered the topic of out-of-order execution (OOE) in previous articles, so I won't rehash all that here. I'll just note that an OOE architecture takes code that was written and compiled to be executed in a specific order, reschedules the sequence of instructions (if possible) so that they make maximum use of the processor resources, executes them, and then arranges them back in their original order so that the results can be written out to memory. To the programmer and the user, it looks as if an ordered, sequential stream of instructions went into the CPU and identically ordered, sequential stream of computational results emerged. Only the CPU knows in what order the program's instructions were actually executed, and in that respect the processor is like a black box to both the programmer and the user.

The same kind of sleight-of-hand happens when you run multiple programs at once, except this time the operating system is also involved in the scam. To the end user, it appears as if the processor is "running" more than one program at the same time, and indeed, there actually are multiple programs loaded into memory. But the CPU can execute only one of these programs at a time. The OS maintains the illusion of concurrency by rapidly switching between running programs at a fixed interval, called a time slice. The time slice has to be small enough that the user doesn't notice any degradation in the usability and performance of the running programs, and it has to be large enough that each program has a sufficient amount of CPU time in which to get useful work done. Most modern operating systems include a way to change the size of an individual program's time slice. So a program with a larger time slice gets more actual execution time on the CPU relative to its lower priority peers, and hence it runs faster. (On a related note, this brings to mind one of my favorite .sig file quotes: "A message from the system administrator: 'I've upped my priority. Now up yours.'")

Clarification of terms: "running" vs. "executing," and "front end" vs. "execution core."

For our purposes in this article, "running" does not equal "executing." I want to set up this terminological distinction near the outset of the article for clarity's sake. So for the remainder of this article, we'll say that a program has been launched and is "running" when its code (or some portion of its code) is loaded into main memory, but it isn't actually executing until that code has been loaded into the processor. Another way to think of this would be to say that the OS runs programs, and the processor executes them.

The other thing that I should clarify before proceeding is that the way that I divide up the processor in this and other articles differs from the way that Intel's literature divides it. Intel will describe its processors as having an "in-order front end" and an "out-of-order execution engine." This is because for Intel, the front-end consists mainly of the instruction fetcher and decoder, while all of the register rename logic, out-of-order scheduling logic, and so on is considered to be part of the "back end" or "execution core." The way that I and many others draw the line between front-end and back-end places all of the out-of-order and register rename logic in the front end, with the "back end"/"execution core" containing only the execution units themselves and the retire logic. So in this article, the front end is the place where instructions are fetched, decoded, and re-ordered, and the execution core is where they're actually executed and retired.

Preemptive multitasking vs. Cooperative multitasking

While I'm on this topic, I'll go ahead and take a brief moment to explain preemptive multitasking versus cooperative multitasking. Back in the bad old days, which wasn't so long ago for Mac users, the OS relied on each program to give up voluntarily the CPU after its time slice was up. This scheme was called "cooperative multitasking" because it relied on the running programs to cooperate with each other and with the OS in order to share the CPU among themselves in a fair and equitable manner. Sure, there was a designated time slice in which each program was supposed to execute, and but the rules weren't strictly enforced by the OS. In the end, we all know what happens when you rely on people and industries to regulate themselves--you wind up with a small number of ill-behaved parties who don't play by the rules and who make things miserable for everyone else. In cooperative multitasking systems, some programs would monopolize the CPU and not let it go, with the result that the whole system would grind to a halt.

Preemptive multi-tasking, in contrast, strictly enforces the rules and kicks each program off the CPU once its time slice is up. Coupled with preemptive multi-tasking is memory protection, which means that the OS also makes sure that each program uses the memory space allocated to it and it alone. In a modern, preemptively multi-tasked and protected memory OS each program is walled off from the others so that it believes it's the only program on the system.

Benefits of wireless tech.

2007-12-03T11:24:00.000-08:00

The benefits of networking (either wired or wireless) in homes are:

file sharing - Network file sharing between computers gives you more flexibity than using floppy drives or Zip drives. Not only can you share photos, music files, and documents, you can also use a home network to save copies of all of your important data on a different computer. Backups are one of the most critical yet overlooked tasks in home networking.
printer / peripheral sharing - Once a home network is in place, it's easy to then set up all of the computers to share a single printer. No longer will you need to bounce from one system or another just to print out an email message. Other computer peripherals can be shared similarly such as network scanners, Web cams, and CD burners.
Internet connection sharing - Using a home network, multiple family members can access the Internet simultaneously without having to pay an ISP multiple accounts.

You will notice the Internet connection slows down when several people share it, but
broadband Internet can handle the extra load with little trouble. Sharing dial-up Internet
connections works, too. Painfully slow sometimes, you will still appreciate having shared
dial-up on those occasions you really need it.

multi-player games - Many popular home computer games support LAN mode where
friends and family can play together, if they have their computers networked.

Internet telephone service - So-called Voice over IP (VoIP) services allow you to make and receive phone calls through your home network across the Internet, saving you money.
home entertainment - Newer home entertainment products such as digital video recorders (DVRs) and video game consoles now support either wired or wireless home networking. Having these products integrated into your network enables online Internet gaming, video sharing and other advanced features.

Although you can realize these same benefits with a wired home network, you should
carefully consider building a wireless home network instead, for the following reasons:

1. Computer mobility. Notebook computers and other portable devices are much affordable than they were a few years ago. With a mobile computer and wireless home network, you aren't chained to a network cord and can work on the couch, on your porch, or wherever in the house is most convenient at the moment.

2. No unsightly wires. Businesses can afford to lay cable under their floors or inside walls. But most of us don't have the time or inclination to fuss with this in our home. Unless you own one of the few newer homes pre-wired with network cable, you'll save substantial time and energy avoiding the cabling mess and going wireless.

3. Wireless is the future. Wireless technology is clearly the future of networking. In building a wireless home network, you'll learn about the technology and be able to teach your friends and relatives. You'll also be better prepared for future advances in network technology coming in the future.

The Methodologies

2007-12-03T11:17:00.000-08:00

XP (Extreme Programming)

Of all the lightweight methodologies, this is the one that has got the most attention. Partly this is because of the remarkable ability of the leaders of XP, in particular Kent Beck, to get attention. It's also because of the ability of Kent Beck to attract people to the approach, and to take a leading role in it. In some ways, however, the popularity of XP has become a problem, as it has rather crowded out the other methodologies and their valuable ideas.

The roots of XP lie in the Smalltalk community, and in particular the close collaboration of Kent Beck and Ward Cunningham in the late 1980's. Both of them refined their practices on numerous projects during the early 90's, extending their ideas of a software development approach that was both adaptive and people-oriented.

The crucial step from informal practice to a methodology occurred in the spring of 1996. Kent was asked to review the progress of a payroll project for Chrysler. The project was being carried out in Smalltalk by a contracting company, and was in trouble. Due to the low quality of the code base, Kent recommended throwing out the entire code base and starting from scratch his leadership. The result was the Chrysler C3 project (Chrysler Comprehensive Compensation) which since became the early flagship and training ground for XP.

The first phase of C3 went live in early 1997. The project continued since and ran into difficulties later, which resulted in the canceling of further development in 1999. As I write this, it still pays the original 10,000 salaried employees.

XP begins with four values: Communication, Feedback, Simplicity, and Courage. It then builds up to a dozen practices which XP projects should follow. Many of these practices are old, tried and tested techniques, yet often forgotten by many, including most planned processes. As well as resurrecting these techniques, XP weaves them into a synergistic whole where each one is reinforced by the others.

One of the most striking, as well as initially appealing to me, is its strong emphasis on testing. While all processes mention testing, most do so with a pretty low emphasis. However XP puts testing at the foundation of development, with every programmer writing tests as they write their production code. The tests are integrated into a continuous integration and build process which yields a highly stable platform for future development.

On this platform XP builds an evolutionary design process that relies on refactoring a simple base system with every iteration. All design is centered around the current iteration with no design done for anticipated future needs. The result is a design process that is disciplined, yet startling, combining discipline with adaptivity in a way that arguably makes it the most well developed of all the adaptive methodologies.

XP has developed a wide leadership, many of them springing from the seminal C3 project. As a result there's a lot of sources for more information. The best summary at the moment is written by an outsider, Jim Highsmith, whose own methodology I'll cover later. Kent Beck wrote Extreme Programming Explained the key manifesto of XP, which explains the rationale behind the methodology and enough of an explanation of it to tell folks if they are interested in pursuing it further.

Two further books are in the works. Three members of the C3 project: Ron Jeffries, Ann Anderson, and Chet Hendrickson are writing Extreme Programming Installed, an explanation of XP based on the C3 experience. Kent Beck and I are writing Planning Extreme Programming, which discusses how you do planning in this adaptive manner.

As well as books, there are a fair number of web resources. Much of the early advocacy and development of the XP ideas occurred on Ward Cunningham's wiki web collaborative writing environment. The wiki remains a fascinating place to discover, although its rambling nature does lead you into being sucked in. To find a more structured approach to XP, it's best to start with two sites from C3 alumni: Ron Jeffries's xProgramming.com and Don Wells's extremeProgramming.org. Bill Wake's xPlorations contains a slew of useful papers. Robert Martin, the well known author on C++ and OO design has also joined the list of XP promoters. His company, ObjectMentor, has a number of papers on its web site. They also sponsor the xp discussion egroup.

Open Source

You may be surprised by this heading. After all open source is a style of software, not so much a process. However there is a definite way of doing things in the open source community, and much of their approach is as applicable to closed source projects as it is to open source. In particular their process is geared to physically distributed teams, which is important because most adaptive processes stress co-located teams.

Most open source projects have one or more maintainers. A maintainer is the only person who is allowed to commit a change into the source code repository. However people other than the maintainer may make changes to the code base. The key difference is that other folks need to send their change to the maintainer, who then reviews it and applies it to the code base. Usually these changes are made in the form of patch files which make this process easier. The maintainer thus is responsible for coordinating the patches and maintaining the design cohesion of the software.

Different projects handle the maintainer role in different ways. Some have one maintainer for the whole project, some divide into modules and have a maintainer per module, some rotate the maintainer, some have multiple maintainers on the same code, others have a combination of these ideas. Most open source folks are part time, so there is an issue on how well such a team coordinates for a full time project.

A particular feature of open source development is that debugging is highly parallelizable. So many people can be involved in debugging. When they find a bug they can send the patch to the maintainer. This is a good role for non-maintainers since most of the time is spent finding the bug. It's also good for folks without strong design skills.

The process for open-source isn't well written up as yet. The most famous paper is Eric Raymond's The Cathedral and the Bazar, which while an excellent description is also rather brief. Klaus Fogel's book on the CVS code repository also contains several good chapters on open-source process that would be interesting even to those who never want to do cvs update.

Transition To Digital TV Technology Causes Confusion

2007-12-03T11:12:00.001-08:00

There's a good chance that a lot of people who have heard about the mandatory transition to digital TV for over the air TV broadcasts that's scheduled for February 17, 2009 is confused about it in any of several different ways. The first thing to be confused about is what will actually be happening with the transition. Fortunately, that's relatively easy to understand. Basically, there are two different formats in which TV programming can be transmitted. The older format is called the analog format and it doesn't make use of computer technology in order to encode or decode the TV programming. TV broadcasters have been using the analog format to send TV programming over the air ever since TV was first introduced back in the middle of the twentieth century.
Digital TV is them more modern and higher tech method of transmitting TV. With Digital TV, all of the video and audio that makes up the picture and sound of the TV programming is converted into digital computer data before being transmitted. Once the digital TV programming has been received, a digital tuner converts it back into the TV programming.

The next thing that many people are confused about is why anyone would want to bother converting from analog TV transmissions to digital TV. After all, if it means getting a new TV set or having to buy a special converter box in order to keep watching an older TV set, why would anyone want to spend the money. Actually, in answer to that question, money is exactly one of the reasons for the conversion to all digital transmission. The consumer electronics industry stands to make a lot of money from people buying new TV sets and digital receiver boxes in preparation of the conversion and has been lobbying Congress for years in an attempt to mandate the change.

In addition to the fact that the consumer electronics industry stands to make a lot of money from the change, the adoption of digital TV stands to provide a lot of technical benefits as well. For example, there are a lot of things that can be done to a digital signal that simply can't be done to an analog one. For example, it can be compressed so that it takes up less bandwidth. Digital TV tuners routinely clean out any interference that crops up during transmission (at least to a point), and that makes the sound and picture quality of digital TV programming much higher than that of analog TV. The fact that most TV stations are transmitting both digital and analog signals right now also means that converting everything over to analog TV will free up a lot of the broadcasting frequencies. The FCC will then designate some of those frequencies to emergency response to that authorities can more effectively respond to terrorist strikes and natural disasters.

Of course like anything else, digital TV has its downsides as well. Besides having to buy digital TV's and digital receivers, more Americans might also have to buy TV antennas if they want to keep watching TV over the air. That's because, while the quality of an analog transmission fades with distance, but can still remain watchable long after it has started to fade, digital TV signals will be crystal clear and then just turn into noise almost right away. Digital TV simply requires better reception to view.

Hopefully this article clarifies many aspects of the conversion to digital TV transmission.

Comcast Re-engineers Cable TV For The 21st Century

2007-12-03T11:10:00.000-08:00

Cable TV has developed a reputation for being inferior to satellite TV. One could argue that this reputation was deserved at one point, but since then the cable TV industry has undergone a major transformation that has brought it to the point where it's arguably superior to satellite TV. Comcast is one example of a cable TV company that has brought cable TV up to twenty first century standards.
The biggest change that Comcast made when it revamped its cable TV service was to convert its transmission format from the older, less efficient analog format to Digital TV. Digital TV alone gives Comcast an edge in a number of different ways. The most obvious edge that Comcast gets from digital TV is the clearer picture. This clearer picture has to do with the fact that a certain amount of interference crops up anytime that video is transmitted more than a few feet- even when its transmitted over underground cables. That interference can then be cleaned out of a digital signal by the digital receiver so that the resulting picture is as clean as the source recording. Though it's less obvious, digital TV also delivers superior quality sound as well.

The real advantage that the adoption of digital TV gave to Comcast was the ability to compress video so that more channels could be transmitted over the same cables. This allowed Comcast to increase the number of channels that it could offer over three times. Now the biggest programming plan from Comcast offers very close to three hundred channels. A new technology that this company is in the process of implementing- a technology call Switched Digital Video- will allow Comcast to make even better use of its existing bandwidth. Switched Digital Video will allow Comcast to send just the channel that a viewer is watching to any given viewer at any given time. That's a lot more efficient than sending all of the available channels to each and every viewer all the time and letting the individual receivers sort out what actually gets displayed on the screen. This technology will remove all practical limits on the number of channels that a cable TV company can offer.

Switched Digital Video has shown up just in time because of the surge of interest in HDTV programming and the rampant competition among TV service providers to deliver the most High Def channels to their subscribers. Under the older transmission method- the "shotgun approach"- HDTV channels were extremely difficult to deliver because of the fact that they are up to ten times more data intensive than normal TV and video can only be compressed so much. The bandwidth required to transmit the number of HDTV channels that viewers will soon demand would have crippled a cable system of the past, but thanks to Comcast's implementation of Switched Digital Video technology, the bandwidth requirements of HDTV will be irrelevant. This makes Comcast a good choice for this king of TV now and in the years to come.

All of this makes the cable TV industry in general, and Comcast specifically, worth a good deal of consideration.

HDTV Displays Take Advantage of Fascinating Technology

2007-12-03T11:06:00.000-08:00

HDTV has gotten a lot of interest among home entertainment enthusiasts and normal people alike, and it's really no wonder. After all, who could not be excited about bringing all of the best parts of the commercial movie theater experience into their own homes. The HDTV experience includes the same wide screen format that most major motion pictures are filmed in, a higher resolution picture than standard definition televisions are capable of providing, and the theater quality sound format of Dolby Digital 5.1 Surround Sound.
Of course, the technology that goes into making HDTV sets is also really fascinating. After all, how often do you get to buy something called a plasma screen TV or a technology called digital light processing.

While HDTV sets use a variety of very different technologies to provide you with a large, high quality picture, there are a number of things that all of the technologies have in common. For example, they all have to be able to create pictures with extremely high resolutions which means being able to cram lots of pixels onto the TV screen. The more pixels are used, the higher the resolution of the picture. Some HDTV sets are capable of creating pictures with resolutions as high as 1080p, while other HDTV sets barely qualify as high definition by only being able to render pictures with resolutions of 720p.

Plasma screen HDTV's are the ones that probably get the most attention because of the fact that they combine a brilliant variety of colors with a really cool sounding name. Plasma screens are made up of numerous pockets of gas- one pocket of gas for each pixel- and when an electrical current is applied to a pocket of gas, the pocket of gas glows. The color and intensity with which the gas pocket glows is determined by the voltage and amperage of the electrical current that's applied to it. The fact that plasma screens have a reputation for very high contrast comes from the fact that a total absence of electrical current produces a total absence of light and color for a very deep black.

Despite their reputation for providing a great picture and the appeal of their name, plasma screens are probably the least suitable for most people's purposes. For one thing, they aren't very versatile when it comes to looking good in a variety of lighting conditions- they just don't glow brightly enough to look good in rooms with high levels of light and they lose their brightness with time. Most models are also inappropriate for use at higher altitudes because they'll emit an annoying humming sound at elevations above six thousand feet. To top things off, plasma screen HDTV's are also energy hogs.

LCD screens don't sound as cool, but they are better for a greater variety of uses. They use less energy then many other technologies and they are bright enough to be used in a variety of lighting conditions, plus their brightness doesn't fade over time. LCD screens have the disadvantages of not being able to display very deep black and blurring while displaying objects that move fast on their screens. Of course, it's worth taking into account that both of these problems are more traditional problems than current problems as they've both been minimized over the years through more advanced application of technology.

Of course these are the two most popular HDTV display technologies, but there are lots of other exciting technologies to explore as well.

Web-enabled system to open Remedy Helpdesk Tickets

2007-12-02T07:19:00.000-08:00

Our Client Needed:

Customized web interface to open Call Center tickets with Remedy Helpdesk software.
Ability to open Call Center tickets via email.
Web-enabled status and update screens for previously opened tickets.

Solution:

Integrated Remedy Arweb software into user’s browser interface providing look and feel of main web site.
Browser interface allowed users to add tickets, check status, and add additional action item information to the ticket.
Created email template that allows for input into customized Remedy schemas to open ticket with call center.

TechInfo provides technical experts that deliver Enterprise IT Solutions.

2007-12-02T07:18:00.000-08:00

TechInfo provides subcontractor personnel in the following key areas:

COTS configuration and integration
Software Architects, Software Development
Database Design and Development
Enterprise Systems Design
O&M Staffing

TechInfo is a leader in providing computer solutions for business and government. TechInfo delivers enterprise-enabled solutions on a variety of platforms including Solaris, HP-UX, and Linux, and Microsoft Server 2003. Our architects have experience using the RUP, UML, and CMMI processes to build enterprise solutions. Our development personnel have expertise utilizing the latest development languages and COTS products including:

Java, J2EE, EJB, JDBC, JSP, Servlets, EJB, Portlets
.Net, ASP, XML, COM, VB,
Oracle, SQL Server, MySQL
BEA, EMC/Documentum, Microsoft, HP, and much more