Cryptography is the art of devising codes and ciphers

Cryptography is the art of devising codes and ciphers, and cryptoanalysis is the art of breaking them. Cryptology is the combination of the two. In the literature of cryptology, information to be encrypted is known as plaintext, and the parameters of the encryption function that transforms are collectively called a key.
Cryptology took on many forms in the centuries between the fall of Rome and the dawn of the Industrial Age. By the late 19th century, with the advent of the telegraph and wireless radio, cryptology took its permanent place as an important component of commercial, military and diplomatic communications. Rudimentary mechanical and electromechanical encoding inventions developed at the turn of the 20th century and through World War I laid the foundation for stronger and more efficient cipher devices.
With the dawn of the computer age, the possibilities for encryption methods and devices expanded exponentially. Machines with blazing fast computing power gave cryptographers the ability for the first time to design complicated encryption techniques.
The next great evolution in cryptology came with the introduction of microprocessor-powered computers. The rapid deployment of increasingly powerful desktops quickened the pace of cryptographic development, since even a moderately skilled computer user could break many of the algorithms in use.
Cryptology is more deeply rooted in every part of our communication and computing world than when it was first employed by ancient peoples. We use it to protect everything from e-mail to e-commerce transactions to personal diaries. As our dependency upon technology increases, so too will our dependency upon cryptography. After all, we all have things we want to keep secret.

Contactless Energy Transfer System (CETS)

Most mains operated equipment in use today is connected to the supply via plugs and sockets. These are generally acceptable in benign environments but can be unsafe or have limited life in the presence of moisture. In explosive atmospheres and in undersea applications special connectors must be used. This paper describes a technique, the Contactless Energy Transfer System (CETS), by which electrical energy maybe transmitted, without electrical connections or physical contact, through non-magnetic media of low conductivity. CETS, which has been used to transfer upto 5KWs across a 10mm gap, employs high frequency magnetic coupling and enables plug in power connections to be made in wet or hazardous environmental conditions without the risk of electric shock, short-circuiting or sparking. Energy may be transmitted without the necessity for accurately manufactured “plug and socket” mechanisms and may be transmitted from source to load even when there is a relative motion. Load source voltage matching may be made inherent to the system.

Condition monitoring of transformer: Electrical Seminar Topic

Transformers are a large part of the component structure of the electricity system. Knowing the condition is essential to meeting the goals of maximizing return on investment and lowering total cost associated with transformer operation.

In order to reconcile both decreasing maintenance spending and reliable service, condition based maintenance (CBM) is often proposed. The successful application of CBM lies in obtaining information transformers, so that, on the one hand, a critical condition will be noted early enough to take measures and on the other hand, so that only minimal maintenance is being applied to transformers still in good condition.

The paper covers the following areas.
• General aspects of aging in transformers.
• An overview of condition monitoring methodology with partial discharge patterns in focus.
• Partial discharge measurement and diagnostics on power transformer using a multi channel digital PD detector.

Brush-less servomotor

A brush-less servomotor has been developed by using interdisciplinary mechatronics engineering. A mechanical switching device (commutator) is replaced by electronic circuits and controllers resulting in maintenance free and high performance servo drive.
The brush-less servomotor is an ac motor, in all respects and is in fact called the ac servomotor. Combined with a dedicated control device, the performance of the brush-less servomotor is found to be equal to the performance of the high performance dc servo motor.
The rotational speed of dc servomotor is generally varied by changing the voltage applied to the armature. As the armature voltage is nearly proportional to the rotational speed, the speed can be slowed down as much as is required by lowering the applied voltage. On the other hand the rotational speed of the ac motor is generally varied by changing the frequency. However the frequency has its limits of variation. A wide range of speed variation, which is a feature of servomotors, cannot be obtained by using only a simple inverter.
In dc motor when the current flows in the electrical conductor, after passing through the brushes and the commutator in the magnetic field generated by permanent magnets N and S, torque is generated. For getting a stable torque proportional to current, the line of magnetic force should intersect the c of current at right angles in a dc motor. This is enabled by the use of rectifiers (a commutator and brushes).
In ac motors slip ring is used instead of a commutator and a power source of alternating current makes the rotor rotate continuously at the rotational speed corresponding to the applied frequency. But the brushes of the ac motors can be eliminated by changing the revolving armature structure in to revolving field type.

Axial-field electrical machines abstract

Axial-field electrical machines offer an alternative to the conventional machines. In the axial-field machine, the air gap flux is axial in direction and the active current carrying conductors are radially positioned. This paper presents the design characteristics, special features, manufacturing aspects and potential applications for axial-field electrical machines. The experimental from several prototypes, including d.c. machines, synchronous machines and single-phase machines are given. The special features of the axial-field machine, such as its planar and adjustable air gap, flat shape, ease of diversification, etc., enable axial-fled machines to have distinct advantages over conventional machines in certain applications, especially in special purpose applications.

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AUTOMATIC SOLAR TRACKER .Electrical seminar topics

A new control scheme for a single – phase diode clamped rectifier is proposed to achieve a unity power factor, balanced neutral point voltage and constant DC-bus voltage. Four power switches are used in the rectifier to generate a three-level PWM wave form on the rectifier terminal voltage.The line current command is derived from a DC-link voltage regulator and an output power estimator. The hysteresis current Controller is used to track the line current command. To balance the neutral-point voltage, a capacitor voltage compensator is employed. The main advantages of using a three-level instead of a two-level PWM scheme are that the blocking voltage of each power switch is clamped to half the DC-bus voltage (if the off –state resistance of  power switches is equal),and the voltage  harmonic on the AC  side of rectifier is reduced.

AUTOMATED DISTRIBUTION SYSTEM With Full seminar Report

Distribution systems are usually composed of radial feeders. Each feeder is divided into load sections with sectionalizing switches and is usually connected to other feeders via normally open tie switches.

 When a fault occurs in the distribution system, it is firstly detected by protection relays, then a circuit breaker is opened and de-energizes the feeder where the fault exists. By operating sectionalizing switches, the faulted section is isolated and the un-faulted sections disconnected are re-energized after reclosing the circuit breaker.

As automation is introduced into the distribution systems, the above switching operations can become automated. Recent advances in digital technology have made possible the development of Distribution Automation System (DAS). The DAS offers many new opportunities for improved system operation. It provides an integrated system approach to monitoring, protection, and control.

 Distribution automation includes wide spread functions, among which feeder automation is an important aspect. By controlling line switches installed on the feeder, feeder automation functions can be accomplished by identifying and isolating permanent feeder faults and restoring service to the un-faulted feeder sections sequentially and automatically, and thus reduce significantly customer outage time. The distribution automation discussed in this paper is restricted to fault isolation, reconfiguration, and service restoration switching operations.
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