Relay Devices Research Articles

Congestion control of bluetooth radio system by piconet restructuring

Bluetooth is a low-cost and short-range wireless communication technology. Two or more bluetooth devices connected form a piconet and two or more piconets connected form a scatternet through relay devices. Without the consideration of traffic flows, a scatternet may operate with serious congestion problem. Congestion problem can be resolved by either reduced traffic flows or increased bandwidth provision. In bluetooth, new piconet can be dynamically constructed to increase system bandwidth. However, as the number of piconet is increased, collision problem among piconets becomes a serious problem. The objective of this paper is to resolve the congestion problems in a scatternet through piconet restructuring which perform both flow analysis and distributed role-switching technique. Advantages of the proposed piconet restructuring mechanism includes the following: (1) the communication bottleneck can be released; (2) the communication path is shortened; (3) the transmission latency is reduced; and (4) the lifetime of piconets can be increased. Experimental results demonstrated that the proposed method could effectively increase the transmission efficient in each piconet and increase the performance of an entire scatternet.

UNIFICATION RELAY - EFFECTIVE WAY OF INCREASING THE RELIABILITY OF SYSTEMS ROLLING STOCK MANAGEMENT IN MODERN CONDITIONS

In this article the following problems have been dwelled upon: the level of standardization of relays in the rolling stock operation schemes and the possibility of its significant increase, the latter task being important for two reasons: the control systems operational costs reduction and improvement of repairability of the relay devices.

PREDICTING TRANSIENT INSTABILITY OF POWER SYSTEMS BASED ON HYBRID SYSTEM REACHABILITY ANALYSIS

This paper shows a novel method for predicting transient instability of power systems based on reachability analysis of hybrid systems. The analysis is performed by computing reachable sets of unsafe sets in nonlinear hybrid automata that represent both continuous electro-mechanical dynamics of generators and discrete operations by relay devices. The unsafe sets here are subsets of system states in which power systems show unacceptable operations such as stepping-out of generators. Then the transient instability of power systems can be estimated by investigating whether a system state exists in the reachable sets or not. The estimation is possible at any onset of accidental faults such as line and plant trips. This paper demonstrates the proposed method through an analysis of single-machine infinite bus system.

Text enhanced telephpony

A system is described for assisting the hard of hearing in the use of the telephone, the system termed here text enhanced telephony or TET. The hard of hearing user uses a TET device or appliance which permits the user to speak and to hear the words spoken by the other party, the TET device also supplying to the user a text character stream of the words spoken by the other party. The TET system uses the system of voice-to-text relays, already in existence to assist the deaf community communicate with hearing persons over the telephone, to translate the spoken voice into a text stream. The TET relay and TET device are capable of separating voice and digital communications frequencies carrying text so that voice and a text communications stream of the words spoken by the voice can be carried over a common telephone line. The devices can also be capable of automated capabilities such that the devices can automatically configure a three-party relay call without the need for the user's instructions.

Issues of judgement and value in television studies

The common critical understanding of television is that it is primarily a medium for communication rather than for artistic accomplishment. The conceptualization of television as a relay device tends to downplay its successes as a medium for artistic expression. This paper argues that our judgement of television begins with the acknowledgement that different kinds of television will demand appropriately different kinds of critical attention. In order to explore the ramifications of this observation, the paper focuses on recent television dramas - in particular ER and other medical dramas - as indicative of artistic accomplishment.

School effectiveness: new managerialism, quality and the Japanization of education

School effectiveness is a microtechnology of change. It is a relay device, which transfers macro policy into everyday processes and priorities in schools. It is part of the growing apparatus of performance evaluation. Change is brought about by a focus on the school as a site-based system to be managed. There has been corporate restructuring in response to the changing political economy of education. There are now new work regimes and radical changes in organizational cultures. Education, like other public services, is now characterized by a range of structural realignments, new relationships between purchasers and providers and new coalitions between management and politics. In this article, we will argue that the school effectiveness movement is an example of new managerialism in education. It is part of an ideological and technological process to industrialize educational productivity. That is to say, the emphasis on standards and standardization is evocative of production regimes drawn from industry. There is a belief that education, like other public services can be managed to ensure optimal outputs and zero defects in the educational product.

Challenges of supplying electric power to a large industrial customer in rural areas

As the economy in rural areas changes, many local leaders are attracting new large industrial clients into the area. When a large industrial business does locate in a service area, the rural electric cooperative is faced with many issues: the impact of the new load on existing system infrastructures; the potential issue of power quality on its system; and its impact on its customers. This requires that, before a large industrial customer is added, careful studies are made regarding rates, interconnection guidelines, and protection issues. The new customer may require state-of-the-art relay devices and fast-track-type installations to meet startup demands. The complexity of the new systems and fast-track construction may require the cooperative to augment its staff with added expertise. This paper discusses these challenges of supplying electric power to a large industrial customer in rural areas.

The Audion-detector And Amplifier

Notwithstanding the now wide-spread use of the Audion as a detector in radio telegraph and telephone service few accounts of independent research into the nature of this instrument, or even cursory descriptions of its operation, seem to have been recorded, since the original paper presented before the American Institute of Electrical Engineers in 1906. At that time, pending patent applications prevented the presentation of a detailed description of certain forms and improvements which are to-day common knowledge among radio engineers. It is my purpose herein to outline briefly the subsequent development of the Audion, both as a radio detector and as an amplifier of minute electric impulses. The improved Audion, containing one hot and two independent cold electrodes, is described, and its action as a sensitive detector in radio telegraph and telephone work outlined. Its actiont is shown to be not that of a simple rectifier or valve, but that of a true relay device. The secondary circuit of a radio receiving transformer is connected in shunt between the grid electrode and the filament. The telephone receiver and dry battery are connected between the plate electrode and filament. There appears to be no known limit of sensitiveness below which the effect of minute received energy fails to be registered. The device is constant and reliable, requiring only initial adjustments of battery voltages. The Audion is incontestably a potential operated device.

Sliding mode control for a class of chaotic systems

This paper proposes a bang-bang type sliding mode control technique to stabilize a class of chaotic systems whose nonlinearity vanishes on a sliding surface. The technique can be realized with practical relay devices, since it takes only two-level control signals. Furthermore, we show that the control system is robust to the model uncertainties. To check the theoretical results, we try to stabilize the Lorentz system on numerical simulations.

Protection of Series Compensated Lines : Filtering Based on Artificial Neural Networks

Abstract The aim of this paper is to emphasize the advantages of using Artificial Neural Networks in protection of series compensated high voltage transmission lines. It is known that the presence of series capacitors on high voltage power lines causes some additional problems in fault distance measurement which are, up to now, not yet totally solved. It is shown that a filtering based ANN approach significantly improves the performances of the protection relay devices.

GIC mitigation: a neutral blocking/bypass device to prevent the flow of GIC in power systems

The design of a neutral blocking/bypass device which can be installed in power transformer neutral-ground connections to block the flow of geomagnetically induced currents (GICs) is described. The device consists of standard distribution capacitors which provide the GIC blocking function. The capacitors are rapidly bypassed by a combination of sparkgap and circuit breaker to solidly ground the neutral during power system disturbances. The sparkgap provides the fast operating response speed, while the circuit breaker provides a secure metallic bypass of the capacitor. Simulation indicates that the bypass device operation will occur rapidly (on the order of 1 ms or less) and will both prevent ferroresonant overvoltages and preserve proper relay and protective device operation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

System configuration for microcomputer-controlled, low-temperature differential thermal analysis

A microcomputer-based differential thermal analysis system is described. It consists of a 16-bit, 48-channel data acquisition unit, relay output device, and signal-processing software. With this system, several aluminum block heat sinks, each containing five samples and a temperature reference, can be programmed independently to produce different, highly accurate freezing rates. Temperature deviation is ± 0.1°C at any given temperature along the ramp. Drift (> 1°C) from any temperature setpoint during a prolonged hold (up to 10 h) was not observed. The system is sensitive enough to detect exotherms from both floral buds and xylem tissue. Output is acquired from each sample as a millivolt differential in comparison to a reference sample and the signal is displayed using signal processing software. Acquisition of signal noise during any run of samples was negligible, relative to the millivolt output obtained from the exothermic events occurring during the freezing of water within a given sample of tissue. The latter software can be used to interactively analyze and compare collected data and also obtain hard-copy plots of the thermograms.

Clinical Evaluation of a New Pump Interface Module (PIM) Safety Device

The Pump Interface Module (PIM) is a new safety device intended to be used in conjunction with a Cobe Air Emboli Protection System (AEPS) and a roller or centrifugal pump. The PIM is a relay device that upon receiving an alarm signal from the AEPS, interrupts line voltage, thus stopping the arterial pump. The purpose of this clinical trial was to verify the utility and user advantages of the PIM when employed with a variety of pumps. The study first involved ex vivo tests using the bovine model. These tests looked at different AEPS positioning, different blood flows, and simulation of a variety of clinical conditions. The clinical study evaluated the PIM using five different types of pumps during 160 open heart procedures. The pumps used were a Cinco (n = 28), Sarns 5000 (n = 47), Sarns 7000 (n = 33), Biomedicus 520 (n = 27), and Biomedicus 540 (n = 25). In all instances the PIM immediately stopped the arterial pump when an alarm signal was received from the AEPS system. The PIM is an effective and practical safety device for use with the tested pumps.

Reliability evaluation of protection devices in electrical power systems

Electrical power is transmitted and distributed by a complex and integrated network which is exposed to various types of faults. These faults are usually short-circuits which occur between phases and between phases and earth. To protect the system against these faults, protection systems, based on automatic relay devices, are incorporated into the power system. This paper discusses the principles of these relay systems and describes techniques that have been developed in order to evaluate the reliability of the devices. The paper also discusses the principles of monitoring and self-checking within the relay to reduce the probability of an undetected dormant failure. All the concepts and techniques are illustrated by the analysis of a typical distance protection relay.

An inexpensive 28-V timer circuit using solid state and relay devices

An easily constructed 28-V dc timer circuit is described. The circuit is as precise, reliable, and versatile as some commercially available units, but is much less expensive to construct.

METHOD OF PROGRAM SYNTHESIS FOR FAILSAFE INTERLOCKING DEVICE IN RAILWAY SIGNALLING

The functions are analyzed of conventional interlocking relay devices used for train control. It is indicated which parts should be designed on the failsafe basis. A method is also proposed for synthesizing a failsafe logic system which is fed with non-failsafe inputs. A universal digital computer program using an interlocking matrix is proposed for the failsafe logic system. The effectiveness of the proposed method has been confirmed by field tests and 20,000-hour test operations.

Unitized modular system of radioisotope relay devices

Unitized modular system of radioisotope relay devices

Satellite repeater system for advanced aircraft/ground communications

This paper considers the application of satellite relay techniques to provide communication paths for aircraft-ground communication over the ocean. It considers the feasibility of a communication system design for air traffic control (ATC) utilizing the reflex repeater as the basic satellite-borne relay device. Implementation of satellite relay techniques would permit continuous line-of-sight operation for reliable ATC digital data links and voice transmission. The paper describes the basic use of the relay system, the repeater electronics, and the communication link parameters required to accommodate the satellite-aircraft link geometries. Examples of typical aircraft-ground link calculations are presented, and the basic supersonic aircraft communication requirements and satellite contact profiles are discussed.

On Measures of Logic Performance: Logic Quantum, Factor, and Figure of Merit

A basic logic operation is considered of transferring a logic decision from one point to another point. A certain energy level, WL, corresponding to decision threshold and a time delay, TL, are encountered in the transfer process. The product, WLTL, is a logic quantum, HL. If the logic transfer takes place through an intermediate device, a logic factor, FL, can be introduced to describe the reduction in logic quanta that the device can produce under optimum conditions. Optimization is carried out, as for instance with ideal transformers, to match the logic source to the device and the device to the logic detector. The condition FL = 1 marks a boundary between a useful and a uselessd evice, and a logicf igure of merit, TPH,in units of time corresponds to the fastest source-detector combination such that FL = 1. Logic performance is considered in some detail for a particular linear model of a device. Nonlinear devices and relay devices are considered in less detail, although some numerical calculations are given for a current-switch, two-transistor computer device. The logic figure of merit represents a unique measure of high-speed logic performance and is therefore valuable in comparing devices including associated circuitry on a common basis.

Problem of classifying relay devices with nuclear radiation sources

The examples dealt with above cover the most typical kinds of functions n(t) in various types of instruments. If functions n(t) differ from the above, it becomes necessary to use general formulas (4)–(6). The integrals used in applying these formulas are not always expressed in elementary functions, but they can always be calculated by means of approximate methods.