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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.
41

Siting and Maintenance of Weather Stations

Brown, Paul, Russell, Bruce 09 1900 (has links)
5 pp. / Revised / A growing number of equipment manufacturers are providing weather stations and computer software that help the groundskeeper with irrigation management decisions. The level of sophistication of this equipment varies, but all systems use the weather station to estimate a parameter known as evapotranspiration (ET). ET is the scientific term for the more common terms water use or consumptive use. Effective utilization of ET information in irrigation management can assist in efforts to manage limited and/or expensive water supplies more effectively, provided the stations are 1) sited and installed correctly, and 2) properly maintained. The purpose of this bulletin is to provide turf facilities information and guidance on siting and maintenance of automated weather stations.
42

A framework for fault management in telecommunications networks

Wells, Nigel Thomas January 1999 (has links)
No description available.
43

Cost analysis and optimal maintenance planning for monotone, repairable systems

Sandve, Kjell January 1996 (has links)
No description available.
44

Generic FMECA analyses of lift systems : improved FMECA and FTA techniques are used for generic analyses of lift systems; design deficiencies relating to reliability, safety and availability are identified

Hadad, A. A. B. January 1991 (has links)
No description available.
45

Predictive Maintenance of Circuit Breakers

Leung , Tat Wai (Alan) January 2007 (has links)
For predictive maintenance of circuit breakers, a number of variables must be considered in order to assess the genuine working condition of a circuit breaker [CB]. This thesis selects vibration signatures obtained on the operating mechanisms and arcing chambers as a source of monitoring breaker conditions. The task of analyzing the behavior of a circuit breaker is perennial and difficult but the thesis has an attempt to tackle this problem. Experiments have been devised to monitor CBs; however, these have limitations details of which will be discussed. For example, each circuit breaker has its own unique vibration signature and the shape of the vibration may be different even though breakers confront similar problems. CBs have decades-long service life spans and failure rates are relatively low. Those that fail are not necessarily saved and there have been relatively few samples to base evidence upon. There are different vibration analysis algorithms available including Dynamic Time Warping [DTW], Resolution Ratio [RR], Discrete Envelope Statistics [DES], event time extraction, Chi-square based shape methods, and fractal theory. Some of these algorithms are based on acoustic properties of materials and rely on assessing extracted time component and the frequency components are extracted. This research applies multi-resolution analysis [MRA] to decomposed signals to in order to assess different sub-wave levels so that wave features may be captured and modeled. There are many ways to analyze the waves. This thesis uses optimizing fuzzy rules with genetic algorithm [GA] as the proposed method. The simuation part of the thesis uses spring performance as an example of how vibration signature analysis may be implemented. Spring vibrations are evaluated by two classification algorithms: Dynamic Time Warping [DTW] and multi-resolution analysis [MRA] with optimizing fuzzy rules with genetic algorithm [GA]. The first method is competent to identify the faulty cases from the normal ones by looking at the deviation of the vibration signature frequency content. In contrast, it is not capable to identify the degree of how bad it performs from looking at the frequency variation. For the second method, it is capable of not only classifying the abnormal cases from the normal cases, but also distinguishing the vibration signatures into different category so that the spring condition can be retrieved immediately. Fuzzy rules is capable of classify a new case to a category and genetic algorithm is an effective tool to minimize the applicable fuzzy rules. The accuracy of the identification is very satisfactory, which is over 90%. Consequently, the proposed algorithm is very useful for asset management purpose of breaker since the lifespan of the spring is known. Diagnostic technicians are able to make decision on the replacement scheme of the spring. There are some areas that this research uncovered that suggests further study is mandated. For example, there are other parameters that can be monitored and compared other than spring constant such as valve position in trip coil and close coil, acceleration parameter in changeover valves, damping in hydraulic cylinders and mechanical linkages, gas pressure in primary contacts and breaker resistance in line system.
46

The International Space Station comparative maintenance analysis model (CMAM)

Soldon, Brian T. 09 1900 (has links)
Approved for public release; distribution is unlimited / The National Aeronautic and Space Administration (NASA) and its prime contractors currently use a software tool called RMAT (the Reliability and Maintainability Assessment Tool) for the forecasting of Orbital Replacement Unit (ORU) failure rates and associated maintenance demands for the International Space Station (ISS). This thesis introduces a new model: CMAM (the Comparative Maintenance Analysis Tool), which was developed to replicate some of the basic functionality of RMAT in order to provide a comparative look at RMAT results. The CMAM program, developed in Visual Basic.net and dynamically linked to a Microsoft ACCESS database, focuses on a representative set of critical Orbital Replacement Units (ORUs that represent key items that require both internal and external maintenance in both pressurized and un-pressurized storage) and generated failure rate data for each critical ORU. The results of the CMAM model are then compared with the failure rates generated by RMAT program for the same set of critical ORUs. These two independently developed sets of data are then analyzed against historic failure rates for these ISS parts. / Major, United States Army
47

Framtagning av metod för analys av livslängdsdata / Application of Reliability Engineering

Adle, Tobias January 2017 (has links)
Husqvarna AB has as of today an extensive research and development department.This department serves to control the active product as well as the upcoming ones.The way that is done is through two different sets of tests. The first one being a longterm endurance test with aimed to unveil the durability of a product. Second and finalsort of test is a more one dimensional one. The aim is to determine different specificunits of interest like for example Newton (N). Today the R&D department has a great knowledge within normal distributed data andsomewhat less when it comes to the opposite, so called none normal distributed data.When endurance is of interest the likelihood of that to be of the latter sort is morecommon than not. For now no complete method has been appointed to make iteasier to process a situation of this kind. Studying ever unique case individually, bylooking at the data, has been the way to go. This causes an inconsistency in theanalysis and makes it purely based on which individual that has done it. Lastly it mayalso, unintentionally, ignore the large picture of how a product has progressed. To solve these problems this thesis work was put together to propose and conduct amethod. To form this method was an ongoing process throughout the whole thesisperiod. Ideas and thoughts were put forward to be reviewed and discussed. After aseries of tweaks to steer it towards the overall goal the method was finalized. Themethod that was put forward was firmly tested. Also a wide laboration in what themethod actually meant was done. The result was a method to be applied on none normal distributed data. This methodhas three parts. The first being the report where everything is embraced. The secondpart is a short manual for an operator to use. Last part is an example where themethod is put to use.
48

Process Maturity : A Component of Process Management

Dahlin, Gunnar January 2017 (has links)
To be able to meet an increased competition through for instance globalization, and shorter product lifecycles, focus on performance control is central for organizations, where for instance processes and stakeholder orientation are central when continuously improving the operation of the organization. The purpose of this thesis is to contribute to the knowledge of how process maturity can be linked to process management. The following research questions have been formulated:  How does process theories relate to the integration of management systems?  How are process theories used within the field of process maturity? Which are the key elements in a process maturity model? Regarding the first research question a literature review was conducted in order to find out how organizations are working with integration of management systems. The main focus of this study was how integration of management systems relates to processes and stakeholder involvement. Secondly a literature review has been conducted on the concept of process maturity. The main aim was to find maturity models focusing on processes and process management, examine the structure of the maturity models used and explore how process management is described within different maturity models. Thirdly a conceptual model for measuring process maturity has been constructed. The content of this model has mainly been based on findings from the literature review conducted on articles on process maturity as well as a literature review of Process Management literature.
49

Dynamická správa entit / Dynamic Maintenance of Entities

Mizera, Jiří January 2013 (has links)
Title: Dynamic Maintenance of Entities Author: Jiří Mizera Department: The Department of Software Engineering Supervisor: doc. Ing. Karel Richta CSc. Supervisor's e-mail address: richta@ksi.mff.cuni.cz Abstract: The aim of my master thesis is to create a tool for dynamical administration of entities and modules. Common application consists of modules operating with certain data. The user experience shows the need of changing the data structure or changing and adding the modules. Propose a solution which enables such dynamical administration and demonstrate it on the prototype. This system should generate fields for inputing, editing or deleting new entries automatically, also including control of individual attributes. At the same time the system considers also losing saved data and the possibility of data transformation to the new version of the system. Keywords: entity, maintenance, module, data
50

An analysis of the prediction accuracy of the U.S. Navy repair turn-around time forecast model / Analysis of the prediction accuracy of the United States Navy repair turn-around time forecast model

Santos, William O. 06 1900 (has links)
Approved for public release; distribution is unlimited / This thesis examines the forecast accuracy of repair times for a subset of repairable U.S Navy inventory items. Forecasts are currently calculated using the Uniform Inventory Control Program (UICP) on a quarterly basis. The UICP model use the time of repairs completed in the current quarter to update a "file" value in order to forecast the repair times for the following quarter. Forecasts are calculated separately for repairable items grouped into families. This thesis demonstrates that aggregation repairs by their completion dates, as currently done by the UICP model, causes forecast to be affected by the nature of the repair arrival process. The more that this process differs from a Poisson process, the more that the forecast values are affected. Using bootstrap simulations, the effect of the repair process on the forecasting is quantified. This thesis also explores alternatives to the UICP model for forecasting repair times. In particular, an approach that utilizes repairs that have not been completed by the end of the current quarter is developed. / Captain, Brazilian Army

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