Showing papers on "Condition monitoring published in 1982"

Error rate monitoring for digital communications

Abstract: The error rate is an important measure of performance in digital communications system, since it gives an indication of the quality of the received information. This paper provides a tutorial overview of methods of error monitoring under four broad classifications, namely, test sequences, parameter measurements, violation detection, and pseudo-error monitoring. A brief discussion of several approaches towards performance monitoring and the definition of error rate parameters is also given. The various methods are described and compared; but, no one monitor is singled out as the "best" since the final choice depends largely on the specific requirements of a given application.

Damage-detection monitoring method for offshore platforms is field-tested.

Abstract: There is a clear need to develop new methods for condition monitoring and inspection of offshore platforms. Two key reasons for this are the unreliability and the high cost of visual inspection-currently the most commonly used method. Among the inspection and monitoring methods now available, those based on vibration analysis seem to hold the greatest promise. A joint effort by two French firms has resulted in field-testing two new methods on a living quarters platform in the Arabian Gulf. This work describes the concepts, equipment, and operating procedures developed, and the significant results obtained. Full-scale experiments using vibro-detection and modal analysis, as described, have demonstrated these techniques possess considerable capability for purposes of structural integrity monitoring and potential as design aids.

Instrument Failure Detection in Partially Observable Systems

Abstract: Instrument failure detection using the dedicated observer scheme (DOS) depends on partial state observability through each instrument which is monitored. For instrument fault detection by the DOS technique, a quantitative measure of partial state observability is established for each instrument and used to determine a necessary condition on the output structure of the system. This measure, called the internal redundancy of the instrument, indicates the complexity of the logic required for failure detection, and it also indicates where some hardware redundancy can be introduced into the system to improve the fault detection capability of the DOS. The principles developed are applied to a simulation of the pitch axis autopilot of the A7 jet aircraft.

Condition monitoring of turbogenerators

Abstract: New methods and instruments have been developed to monitor the condition of turbogenerators. These instruments could help to improve the reliability of generation equipment

Condition monitoring system for rotating machinery on ships

Abstract: This paper describes a condition monitoring system developed by The Ship Research Institute of Norway for the Royal Netherlands Navy. A computer system will be used for control and surveillance of the "platform systems" aboard a new class of submarines now under construction for the Navy. By implementing a condition monitoring system using the same computers and sensors as the control and surveillance system the additional cost for the condition monitoring system will be relatively low. The condition monitoring system is divided into a performance monitoring and a vibration monitoring module. The performance monitoring part accepts thermodynamic data from the on-line control and primary surveillance systems which is processed into easy to understand health parameters. The vibration monitoring system comprises both monitoring and diagnostic modes. The presentation of information is based on graphic techniques using VDU and CRT screens. The information is presented in both tabulated and graphical forms.

Real-time monitoring of machine tools via Walsh-Hadamard tranform

Abstract: Real-time machine monitoring is an open problem in machine tool industry. The presence of unmanned production systems increases the demands on such equipments. Success can be expected only by joint application of signal processing and pattern recognition methods. In real-time applications the speed of the system is of vital importance. In this respect the use of Walsh-Hadamard transform in preprocessing stage of the recognition system is investigated. Fourier and walsh transform of measured vibration data is compared. The paper gives an overview of the applicable methods of classification and feature selection . A multiprocessor-based real-time monitoring system is outlined, which system is under development.

Signature Analysis Extended: A System Approach to Machinery Dynamics

Abstract: Summary Signature analysis has a definite function and role to play in understanding machinery dynamics and maintaining the health of operating systems. It does not, however, provide all the answers. Experimental modal analysis can be used to extend the reach of signature analysis by providing a more fundamental understanding of machinery dynamics. Combined experimental and analytical techniques for system analysis can take a further step in understanding and designing better machinery. These techniques allow the engineer to see how various components or subsystems interact, even before total system hardware is available. They also can provide valuable load information so that better, more efficient component design may be done. The broad application of system analysis technology is just beginning to take place. Developments in hardware and user-oriented software have taken some of the “black-magic” out of the technology and have made it something that can be used as a routine tool. Many areas are open for development and are actively being pursued. A number of particular interest are:5 coupling of equipment dynamics with dynamic fluid forces created in attached piping; continuation of development of techniques for flexible rotor balancing using a system model, modal data base, and future instrumentation developments;6 additional refinement techniques for coupling of foundation dynamics with equipment dynamics; additional insight in the use of computerized condition monitoring systems by identifying the optimal locations for instrumentation and insight into the proper monitoring system diagnostics.

Development of plant condition monitoring techniques and their application

Abstract: Different maintenance strategies are listed and their merits discussed. The paper then concentrates on the condition monitoring approach to maintenance and the development of monitoring techniques is presented.

Method for dividing the working-cycle of a machine-tool.

Abstract: System for automatic condition monitoring of machine-tools in operation. The workingcycle is divided into phases, where different reference values may be valid for the parameters that are monitored, e.g. the current consumption of motors. When a new phase is to be initiated this is stated by the operator. Furthermore, there is a possibility to get impulses for phase changing from generators positioned on the machine-tool or the control system. Unambiguousness regarding where in the working-cycle a change of reference values (phase change) occurs is obtained in that the monitoring systems add pulses from pulse generators coupled to the feeding axes of the machine-tool. The monitoring is synchronized with the working-cycle in that the starting pulse of the detail programme is fed to the monitoring system. By deviations from the valid reference values, obtained from recording, ALARM or STOP signals are obtained in dependence of the type of deviation.