In this note we study two cryptographic notions introduced in recent years: zero-knowledge proof systems [GMR] and instance-hiding schemes [AFK]. Addressing an open problem of [BFS] and extending the work in [AFK], we...
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Interlocks have been in use ever since protective relaying schemes were implemented for power devices like generators, transformers, transmission lines, etc. Although the science of protective relaying has undergone m...
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programmable logic controllers (PLC) have been widely used in industrial process control, due to their low cost, high reliability and integrated logic functions. This paper reports the development of the multi-level b...
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The International Electrotechnical Commission is currently standardising four compatible languages for designing and implementing programmable logic controllers (PLCs). The language family includes a diagrammatic nota...
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The International Electrotechnical Commission is currently standardising four compatible languages for designing and implementing programmable logic controllers (PLCs). The language family includes a diagrammatic notation that supports the idea of software ICs to encourage graphical design techniques and systematic software reuse. This paper presents an interactive system with a graphical interface for constructing and validating PLC software. The semantics of a graphical design is defined by a mapping associating each design with an executable formal specification. The specification provides the basis for rigorous proofs and early tests of critical properties of a new design. A realistic example illustrates these features.
In accelerated cable life testing of power cables, cable samples are usually subjected to elevated voltages and temperatures in the presence of water in order to promote aging of the insulation and premature failures ...
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In accelerated cable life testing of power cables, cable samples are usually subjected to elevated voltages and temperatures in the presence of water in order to promote aging of the insulation and premature failures through the treeing mechanism. Failure to accurately control and monitor these accelerating factors can have adverse effects on test results and can lead to erroneous conclusions. In Part I of this paper, a new and improved accelerated cable life test is described. Through the use of programmable logic controllers (PLCs), very precise and consistent control of the accelerated aging process has been achieved. A computer has been utilized to make continuous real-time data acquisition and storage of key operating parameters possible. This precise control and monitoring methodology has permitted the study of the synergistic effects of voltage and temperature on the accelerated aging of full-sized cables in the laboratory.
Single-pass translation of unrestricted relay ladder logic (RLL) into an AND/OR Boolean form is described. A data representation of the ladder is specified for supporting computer-aided entry and flow displays, as wel...
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Single-pass translation of unrestricted relay ladder logic (RLL) into an AND/OR Boolean form is described. A data representation of the ladder is specified for supporting computer-aided entry and flow displays, as well as the translation. The representation separates downward and upward vertical flow channels to simplify interpretation. The vertically separated representation can be derived during interactive keyboard entry of the model, without placing added demands on the user. The translation algorithm is explained in structured pseudocode and with a series of graphic translation examples. A dynamic data structure is given for the target AND/OR tree form. Algorithmic descriptions are done in the readable syntax of Modula-2, with pseudocode in place of specialized constructions.
In this paper, we identify the database issues associated with programmable logic controllers (PLC), special-purpose computers used in scientific and industrial applications, e.g., in factories in manufacturing enviro...
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This paper introduces an algorithm for converting relay ladder logic (RLL) programs for programmable logic controllers (PLCs) into sequential function chart (SFC) programs. Since an SFC (a standardization of Grafcet) ...
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The application of programmable logic controllers (PLCs) is possible to realize the protection against the earth-one-phase faults in elctric lines with isolated neutral. A methodologie is proposed to obtain the replac...
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In this project we examined ways in which systems may be implemented on programmable logic controllers. PLC systems exhibit a number of unique features, our objective was to create a practical approach to modelling sy...
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