Thursday, July 26, 2007

Gear

A gear is a wheel with teeth around its circumference, the purpose of the teeth being to mesh with similar teeth on another mechanical device possibly another gear wheel so that force can be transmitted between the two strategies in a direction tangential to their surfaces. A non-toothed wheel can transmit some tangential force but will slip if the force is large; teeth put off slippage and permit the transmission of large forces.

A gear can mesh with any device having teeth friendly with the gear's teeth. Such devices include racks and other non-rotating policy; however, the most common condition is for a gear to be in mesh with another gear. In this case revolution of one of the gears necessarily causes the other gear to rotate. In this way, rotational motion can be transferred from one position to another. While gears are sometimes used simply for this reason to transmit rotation to another shaft perhaps their most significant feature is that, if the gears are of asymmetrical sizes, a mechanical advantage is also achieved, so that the rotational speed, and torque, of the second gear are dissimilar from that of the first. In this way, gears provide a means of increasing or decreasing a turning speed, or a torque.

Friday, July 20, 2007

Inductor

An inductor is a passive electrical device working in electrical circuits for its property of inductance. Inductance is an consequence which results from the magnetic field that forms around a current carrying conductor. Electrical current through the conductor creates a magnetic flux relative to the current. A change in this current creates a change in magnetic flux that, in turn, generates an electromotive force that acts to oppose this change in current. Inductance is a calculate of the generated emf for a unit modify in current. An inductor with an inductance of 1 henry produces an emf of 1 V when the current through the inductor changes at the rate of 1 ampere per second. The number of turns, the area of each loop/turn, and what it is wrapped around influence the inductance.

An inductor opposes changes in the current. An ideal inductor would offer no resistance to a constant direct current, however, only superconducting inductors have truly zero electrical resistance. Inductors are used expansively in analog circuits and signal processing.

Monday, July 16, 2007

IPL

IPL is Initial program load, used in operating system. In computing, booting is a bootstrapping method that starts operating systems when the user turns on a computer system. A boot series is the set of operations the computer performs when it is switched on that loads an operating system.

Most computer systems can only complete code found in the memory (ROM or RAM). Modern operating systems are stored on hard disks, or occasionally on Live CDs, USB flash drives, or other non-volatile storage devices. When a computer is first power-driven on, it doesn't have an operating system in memory. The computer's hardware alone cannot perform complex measures such as loading a program from disk, so an apparent paradox exists, to load the operating system into memory, one appears to need to have an operating system already loaded. The System/360 IPL function reads 24 bytes from an operator-specified or pre-configured machine into memory starting at location zero. The second and third groups of eight bytes are treated as Channel Command Words (CCWs) to maintain loading the startup program. When the I/O channel instructions are complete, the first group of eight bytes is then loaded into the Program Status Word (PSW) register and the startup program begins completing at the designated location.

Tuesday, July 10, 2007

Electronics

Electronics is the learn of the flow of charge through different materials and devices such as, semiconductors, resistors, inductors, capacitors, nano-structures, and vacuum tubes. All applications of electronics involve the transmission of either information or power. Although measured to be a theoretical branch of physics, the design and structure of electronic circuits to solve practical problems is an e Most analog electronic appliances, such as radio receivers, are constructed from combinations of a few types of basic circuits. Analog circuits use a continuous range of voltage as contrasting to discrete level as in digital circuits. The number of different analog circuits so far devised is huge, especially because a circuit can be defined as anything from a single component, to systems containing thousands of mechanism.