The principal of Built-in-test and self-test has been widely applied to the design and testing of complex, mixed-signal electronic systems, such as integrated circuits (IC s) and multifractional instrumentation . A system with BIT is characterized by its ability to identify its operation condition by itself, through the testing and diagnosis capabilities built into its in structure. To ensure reliable performance, testability needs to be incorporated into the early stage of system and product design. Various techniques have been developed over the past decades to implement the BIT technique. In the semiconductor, the objective of applying BIT is to improve the yield of chip fabrication, enable robust and efficient chip testing and better scope with the increasing circuit complexity and integration density.a
Tuesday, September 1, 2009
Current approaches to intrusion detection systems
Most current approaches to the process of detecting intrusions utilize some form of rule-based analysis. Rule-Based analysis relies on sets of predefined rules that are provided by an administrator, automatically created by the system, or both. Expert systems are the most common form of rule-based intrusion detection approaches. The early intrusion detection research efforts realized the inefficiency of any approach that required a manual review of a system audit trail. While the information necessary to identify attacks was believed to be present within the voluminous audit data, an effective review of the material required the use of an automated system.
The use of expert system techniques in intrusion detection mechanisms was a significant milestone in the development of effective and practical detection-based information security systems.
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Electronics
Intrusion Detection Systems
The timely and accurate detection of computer and network system intrusions has always been an elusive goal for system administrators and information security researchers. The individual creativity of attackers, the wide range of computer hardware and operating systems, and the ever changing nature of the overall threat to target systems have contributed to the difficulty in effectively identifying intrusions. While the complexities of host computers already made intrusion detection a difficult endeavor, the increasing prevalence of distributed network-based systems and insecure networks such as the Internet has greatly increased the need for intrusion detection.
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Electronics
ANN for misuse detection
Because of the increasing dependence which companies and government agencies have on their computer networks the importance of protecting these systems from attack is critical. A single intrusion of a computer network can result in the loss or unauthorized utilization or modification of large amounts of data and cause users to question the reliability of all of the information on the network. There are numerous methods of responding to a network intrusion, but they all require the accurate and timely identification of the attack.
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Electronics
Monday, August 31, 2009
Drawbacks of Ultrasonic motors
Electromagnetic motors rely on the attraction and repulsion of magnetic fields for their operation. Without good noise suppression circuitry, their noisy electrical operation will affect the electronic components inside it. Surges and spikes from these motors can cause disruption or even damage in nonmotor related items such as CRTs and various types of receiving and transmitting equipments. Also , electromagnetic motors are notorious for consuming high amount of power and creating high ambient motor temperatures.
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electrical
Monday, July 20, 2009
Isoloop Magnetic Couplers
Couplers, also known as "isolators" because they electrically isolate as well as transmit data, are widely used in industrial and factory networks, instruments, and telecommunications. Every one knows the problems with optocouplers. They take up a lot of space, are slow, optocouplers age and their temperature range is quite limited. For years, optical couplers were the only option. Over the years, most of the components used to build instrumentation circuits have become ever smaller. Optocoupler technology, however, hasn't kept up. Existing coupler technologies look like dinosaurs on modern circuit boards.
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electrical
Thursday, July 2, 2009
RMI System
The charter of the Integrated Media Systems Center (IMSC) at the University of Southern California (USC) is to investigate new methods and technologies that combine multiple modalities into highly effective, immersive technologies, applications and environments. One of the results of these research efforts is the Remote Media Immersion (RMI) system. The goal of the RMI is to create and develop a complete aural and visual environment that places a participant or group of participants in a virtual space where they can experience events that occurred in different physical locations.
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Electronics
Wednesday, July 1, 2009
Biological Computers
Biological computers have emerged as an interdisciplinary field that draws together molecular biology, chemistry, computer science and mathematics. The highly predictable hybridization chemistry of DNA, the ability to completely control the length and content of oligonucleotides, and the wealth of enzymes available for modification of the DNA, make the use of nucleic acids an attractive candidate for all of these nanoscale applications
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computer
Ultraconductors
Superconductivity is the phenomenon in which a material losses all its electrical resistance and allowing electric current to flow without dissipation or loss of energy. The atoms in materials vibrate due to thermal energy contained in the materials: the higher the temperature, the more the atoms vibrate. An ordinary conductor's electrical resistance is caused by these atomic vibrations, which obstruct the movement of the electrons forming the current. If an ordinary conductor were to be cooled to a temperature of absolute zero, atomic vibrations would cease, electrons would flow without obstruction, and electrical resistance would fall to zero.
been demonstrated to date.
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electrical
Ultrasonic Motor
All of us know that motor is a machine which produces or imparts motion, or in detail it is an arrangement of coils and magnets that converts electric energy into mechanical energy and ultrasonic motors are the next generation motors.
In 1980,the world's first ultrasonic motor was invented which utilizes the piezoelectric effect in the ultrasonic frequency range to provide its motive force resulting in a motor with unusually good low speed, high torque and power to weight characteristics.
Electromagnetism has always been the driving force behind electric motor technology. But these motors suffer from many drawbacks. The field of ultrasonic seems to be changing that driving force.
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electrical
Surge current protection using superconductors
Damage from a short circuit is a constant threat to any electric power system. Insulation damaged by aging an accident or lightning strike can unloose immense fault currents practically the only limit on their size being the impedance of the system between their location and power sources. At their worst, faults can exceed the largest current expected under normal load - the nominal current by a factor of 100 producing mechanical and thermal stresses in proportion to the square of the current's value.
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electrical
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