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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Development of BEMS Diagnostic and Intelligent Expert Technology for Air-conditioning Systems

Dai, Chi-fu 11 June 2012 (has links)
When central HVAC systems are under commercial operation, all operational parameters, including chilled water supply temperature, return water temperature, chilled water flow rate, and power consumption as the key factors in affecting system energy efficiency.However, in Taiwan there is still lacking of the regression equations of chillers under local weather conditions, and has to rely on manual operation based on experiences. This is also the major short-comings in implementing TAB, and is the best way to renovate the green buildings to make them more intelligent. In this study, theoretical analysis and experimental investigation will be applied simultaneously. In selecting cases from the BeeUp program, actual operational data including COP can be fitted into experimental model to facilitate TAB engineering via BEMS system, in achieving system efficiency. Through the execution of this project, it is identified that the exhibition buildings with 10 hours cooling load, can achieve 7% energy savings. The good result obtained in this project , including the thermal energy storage HVAC system and the heat pump system can be widely adapted to obtain significant energy conservation effect.
2

Application of communication theory to health assessment, degradation quantification, and root cause diagnosis

Costuros, Theodossios Vlasios 15 October 2013 (has links)
A review of diagnostic methods shows that new techniques are required that quantify system degradation from measured response. Information theory, developed by Claude E. Shannon, involves the quantification of information defining limits in signal processing for reliable data communication. One such technique considers information theory fundamentals forming an analogy between a machine and a communication channel to modify Shannon`s channel capacity concept and apply it to measured machine system response. The technique considers the residual signal (difference between a measured signal induced by faults from a baseline signal) to quantify degradation, perform system health assessment, and diagnose faults. Similar to noise hampering data transmission, mechanical faults hinder power transmission through the system. This residual signal can be viewed as noise within the context of information theory, to permit application of information theory to machines to construct a health measure for assessment of machine health. The goal of this dissertation is to create and study metrics for assessment of machine health. This dissertation explores channel capacity which is grounded and supported by proven theorems of information theory, studies different ways to apply and calculate channel capacity in practical industry settings, and creates methods to assess and pinpoint degradation by applying the channel capacity based measures to signals. Channel capacity is the maximum rate of information that can be sent and received over a channel having a known level of noise. A measured signal from a machine consists of a baseline signal exemplary of health, intrinsic that contaminates all measurements, and signals generated by the faults. Noise, the difference between the measured signal and the baseline signal, consists of intrinsic noise and "fault noise". Separation between fault and intrinsic (embedded in the measurement) noise shows channel capacity calculations for the machine require minimal computational efforts, and calculations are consistent in the presence of intrinsic white noise. Considering the response average or DC component of a signal in the channel capacity calculations adds robustness to diagnostic results. The method successfully predicted robot failures. Important to system health assessment is having a good baseline response as reference. The technique is favorable for industry because it applies to measurement data and calculations are done in the time domain. The technique can be used in semi-conducting industry as a tool monitoring system performance and lowering fab operating cost by extending component use and scheduling maintenance as needed. With a window running average channel capacity the technique is able to locate the fault in time. / text
3

Um framework para auxílio na criação de diagnosticadores de falhas em sistemas. / A framework to aid in the creation of fault diagnosis systems.

PONTES, Renata França de. 01 August 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-08-01T19:01:53Z No. of bitstreams: 1 RENATA FRANÇA DE PONTES - DISSERTAÇÃO PPGCC 2008..pdf: 2190175 bytes, checksum: 6c38a98f2e18daaac164700a18ac2cc3 (MD5) / Made available in DSpace on 2018-08-01T19:01:53Z (GMT). No. of bitstreams: 1 RENATA FRANÇA DE PONTES - DISSERTAÇÃO PPGCC 2008..pdf: 2190175 bytes, checksum: 6c38a98f2e18daaac164700a18ac2cc3 (MD5) Previous issue date: 2008-03-28 / Este trabalho tem como objetivo facilitar a criação de diagnosticadores de falhas baseados em modelos de sistemas. Existem diversos diagnosticadores que utilizam os mesmos métodos em sua criação. A solução sugerida é a implementação de um framework que utilize a estrutura em comum existente nesses tipos de diagnosticadores e que possa reaproveitar os métodos de diagnóstico de falhas utilizados pelos mesmos. O trabalho mostra que este reaproveitamento traz mais facilidade e rapidez na construção desses diagnosticadores. / This work aims to facilitate the creation of Fault diagnosticians based on model system. Several diagnosticians use the same methods in their creation. The suggested solution is the implementation of a framework that uses the existing common structure between these diagnosticians, and that can reuse the fault diagnosis methods. This reuse would make the diagnostician construction easier and quicker.
4

Diagnostický systém papírenského stroje / Diagnostic system of paper machine

Škrobánek, Martin January 2020 (has links)
This master thesis deals with the technical diagnostics, focusing mainly on vibration diagnostics. This problematice is described in the first part of this work on a theoretical level. The next part describes the paper machine, diagnostic system and the measuring points are classified into databases. The practical part of this work consists of a proposal for the methodology of vibration diagnostics for a paper machine, the procedure for measuring and evaluating the measured values. Part of the work is also a practical example of the measurement of the central cylinder, on which the procedure is tested, and the compilation of new limit values.
5

Measuring Airport Efficiency with Fixed Asset Utilization to Minimize Airport Delays

Widener, Scott D. 22 October 2010 (has links)
Deregulation of the airlines in the United States spawned a free-for-all system which led to a variety of agents within the aviation system all seeking to optimize their own piece of the aviation system, and the net result was that the aviation system itself was not optimized in aggregate, frequently resulting in delays. Research on the efficiency of the system has likewise focused on the individual agents, primarily focusing on the municipalities in an economic context, and largely ignoring the consumer. This paper develops the case for a systemic efficiency measurement which incorporates the interests of the airlines and the consumers with those of the airport operating municipalities in three different Data Envelopment Analysis (DEA) models: traditional Charnes-Cooper-Rhodes and Banker-Charnes-Cooper models, and a Directional Output Distance Function model, devised and interpreted using quality management principles. These models were combined to allow the resulting efficiencies of the operating configurations of the given airport to predict the efficiency of the associated airport. Based upon regression models, these efficiency measurements can be used as a diagnostic for improving the efficiency of the entire United States airspace, on a systemic basis, at the individual airport configuration level. An example analysis using this diagnostic is derived in the course of the development and description of the diagnostic and two additional case studies are presented.

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