The very fundamenta & basic

Passive RFID Tags vs. Active RFID Tags An RFID tag is a small device that can be attached to or incorporated into a product and transmit data to a reader using radio waves. RFID tags have antennas that allow then to receive and respond to radio-frequency queries from an RFID transceiver. RFID tags come in two varieties: active and passive. Active RFID tags have a built-in power supply, such as a battery, as well as electronics that perform specialized tasks. By contrast, passive RFID tags do not have a power supply and must rely on the power emitted by an RFID reader to transmit data. Thus, if a reader is not present, the passive tag cannot communicate and data. Active tag can communicate in the absence of a reader. Passive RFID Tags Passive tags are comprised of three elements: an integrated circuit or chip, an antenna, and a substrate. The RFID chip stores data and performs specific tasks. Depending on its design, the chip may be read-only (RO), write-once, read-many (WORM), or read-write (RW). Typically, RFID chips carry 96 bits of memory but can range from 2 to 1000 bits. Attached to the chip is the antenna, whose purpose is to absorb radio-frequency (RF) waves from the reader’s signal and to send and receive data. Passive RFID tag performance is strongly dependent on the antenna’s size: the larger the antenna, the more energy it can collect and then send back out. Larger antennas, therefore, have higher read ranges (although not as high as those of active tags). Antenna shape is also important to the performance of the tag. Low-and high-frequency (LF and HF, respectively) antennas are usually coils because these frequencies are predominantly magnetic in nature. Ultrahigh-frequency (UHF) antennas, on the other hand, look similar to old fashioned TV antennas (rabbit ears) because ultrahigh frequencies are solely electric in nature. The third component of a passive RFID tag is called a substrate, which is commonly a Mylar or plastic film. Both the antenna and the chip are attached to the substrate, which may be thought of as the “glue” that holds all of the tag’s pieces together. In contrast to active RFID tags, passive tags are usually smaller and less expensive. Active RFUD Tags Like passive RFID tags, active tags have both a microchip and an antenna. The chip, however, are usually larger in size and have greater capabilities than the RFID chips in passive tags. Active tags have two additional components that differentiate them from passive tags: an on-board power supply and on-board electronics. The power supply is usually a battery, although it can also be solar. The built-in power supply allows the tags to transmit data to a reader on its own, without the need to draw power from the reader itself like passive tags do. In addition, active tags can be read from distances of 100 feet or more, whereas passive tags can only be read from up to about 20 feet. On-board electronics may consist of sensors, microprocessors, and input/output ports, all of which are powered by the tag’s on-board power source. The electronics allow active RFID tags to be used in a wider range of applications than passive tags. For instance, perishable foot products may be tagged with sensors that collect data than can then be used to determine expiry dates and warn the end user that the item may be spoiled. Even though many products have expiration dates printed on them; these dates are valid only if the product is stored under the optimal conditions (temperature, humidity, exposure to light, etc.) for that type of product. Thus, the product may expire before the printed date if it is not stored properly. An RFID tag equipped with a temperature sensor might be able to predict the actual expiration date of a carton of milk, for example, which may be very different from the printed date. Whether you choose to use active or passive tags in your RFID system will likely depend on both your particular application and your budget.

Mexico invests in highway work

A healthy US$5.5 billion budget will be invested by Mexico's federal government on nationwide highway infrastructure projects during 2008. One of the key projects is for a bypass connecting Amozoc with Perote in Puebla and Veracruz states respectively, reports Business News Americas. Other projects include work in the northern part of Mexico City and the Morelia-Salamanca highway, linking Michoacán state with Guanajuato state. In 2008 southeastern Veracruz state will renovate a number of highways as well as maintaining feeder roads. One of the state's priorities is the bypass for capital Xalapa, with construction scheduled to start in late March or early April. Another project due for development is the Laguna Verde-Gutiérrez Zamora stretch of the Tuxpan-Tampico highway, which will connect Veracruz with neighboring Tamaulipas state to the north. Key tasks are the construction and modernisation of toll-free national highways, maintaining the federal network and developing the rural road network. Toll highway construction is another target and there are 11 projects under construction at different stages in their respective concession processes and all of them are scheduled for completion in 2008. Amongst those scheduled for works completion soon are the Amozoc-Perote highway, linking the states of Puebla and Veracruz; the Tepic-Villa Unión highway, connecting eastern Nayarit and Sinaloa states; and the Morelia-Salamanca highway, between the states of Michoacán and Guanajuato. Significant investments are also scheduled for the 221km Arco Norte of the Mexico City beltway, which is due for completion in December having started in January 2006. Recently awarded concessions include the Arriaga-Ocozocoautla highway in southern Chiapas state, which started in December 2007.

Congestion hits Dubai's GDP

Traffic congestion in Dubai results in annual losses of US$1.25 billion, equivalent to 3.15% of GDP. According to Dr Abdul Malek Ebrahim Abu Shaikh, head of Transportation Studies and Planning at the Roads and Transport Authority (RTA), transport policy and concomitant legislation have to strike a balance between demand and supply. He points out that at 541 cars/1000 population, Dubai has higher car ownership than New York (444), London (345) and Singapore (111). Furthermore, if current purchase trends continue, Dubai will have 5.3 million registered cars by 2020. As a result, measures will have to be taken to discourage car usage and promote public transport. Under consideration are limits on the number of driving licences to be issued, an increase in vehicle registration fees and higher road tax. There is currently insufficient road capacity, which is the main cause of congestion. However the number of roads now crossing the Dubai Creek will have increased from 40 to 47 by the end of 2008, while nine new ring roads will be in place by 2020. Existing road projects are absorbing $2.178 billion of new investment.