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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

Estimation of shutdown schedule to remove fouling layers of heat exchangers using risk-based inspection (RBI)

Elwerfalli, A., Alsadaie, S., Mujtaba, Iqbal M. 28 March 2022 (has links)
Yes / Oil and Gas plants consist of a set of heat exchangers, which are used in recovering the waste heat from product streams to preheat the oil. The heat transfer coefficient of exchangers declines considerably during the operation period due to fouling. Fouling in heat exchangers is a complex phenomenon due to the acceleration of many layers of chemical substances across tubes of heat exchangers resulting from chemical reactions and surface roughness. In this paper, the fouling process was determined as a critical failure in the heat exchanger. Failure is an accelerated fouling layer across the heat exchanger tubes, which can be the reason for the clogging of tubes. Hence, a risk assessment was conducted using the Risk-Based Inspection (RBI) approach to estimate the probability of fouling in heat exchangers. The results showed that the RBI approach can be used successfully to predict the suitable time to shut down the plant and conduct the fouling cleaning process.
2

DIGITAL SWITCH SUSTAINMENT PROGRAM

Youssef, Ahmed H., McNamee, Stuart A., Bowman, Dalphana 10 1900 (has links)
International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper describes the status of the Edwards Digital Switch (EDS) [1] and the success of the Digital Switch Sustainment Program (DSSP); a multi-service program aimed at cost-effective means for providing maintenance and development of an advanced digital switching system. This digital communications switching system is deployed at the mission control centers of Edwards AFB, Eglin AFB, and China Lake Naval Air Warfare Center (NAWC). Each system provides the test ranges with mission-critical voice communications and Time Space Position Information (TSPI) switching. Through user-friendly Graphical User Interfaces (GUIs), the switch provides exceptional resource management of radios, telephones, user positions, secure communications, radars, trackers, 4-wire Ear & Mouth (E&M) devices, subscriber services, and other equipment. Developed using commercial equipment, such as the Lucent Technologies Digital Access and Cross-Connect System (DACS) II, the digital switch can integrate and interface with the technologies of other test ranges and customers. The DSSP sustaining engineering contract, a $10M contract awarded in 1997, is a multi-service effort in supporting cost effective maintenance and enhancement for the systems’ software and hardware. Eglin and China Lake have agreed to participate in a Digital Switch Working Group (DSWG) to ensure that this configuration management is in place and that all players follow the same system migration path. These ranges and other interested ranges that agree to purchase systems off the contract and participate in the working group will continue to derive benefits by reducing overhead and eliminating the duplication of effort involved in separate endeavors.
3

On the development of a maintenance approach for factory of the future implementing Industry 4.0

Algabroun, Hatem January 2017 (has links)
The objective of this thesis is to develop a maintenance approach that fulfills the requirements of Industry 4.0. It explores the role and importance of maintenance activities in today’s industry. Then, it develops the features and tasks required to be performed by maintenance to fulfill the demands of Industry 4.0. Finally, it develops a reference model to be used in designing maintenance system for Industry 4.0. To perform these studies, real data were collected and applied as well as a typical scenario was implemented. The results achieved in the papers of this thesis are 1) a mathematical representation and application of a model that identifies, analyses and prioritizes economic weakness in working areas related to production, 2) a model that analyses, identifies and prioritizes failures that impact the competitive advantages and profitability of companies, 3) characterization of a suitable maintenance technique for Industry 4.0 and 4) a reference model i.e. a framework, that could be utilized to develop a maintenance approach for Industry 4.0. The conclusion of this thesis confirms that maintenance has a significant impact on companies’ competitive advantages, other working areas and profitability. To achieve a suitable maintenance technique for Industry 4.0, this technique must be able to monitor, diagnose, prognosis, schedule, assist in execution and present the relevant information. In order to perform these tasks several features must be acquired, the most important features are to be: digitized, automated, intelligent, able to communicate with other systems for data gathering and monitoring, openness, detect deviation in the condition at an early stage, cost- effective, flexible for adding new CM techniques, provide accurate decisions and scalable. The developed framework could be used as a base to design a maintenance system for Industry 4.0. This study contributes to our understanding of the maintenance importance in today’s industry and how to develop a maintenance approach for Industry 4.0.
4

Eficiência global dos equipamentos como instrumento de apoio à redução de custo de manutenção: uma survey na indústria de manufatura / Overall equipment effectiveness as support instrument in reducting maintenance costs: a survey in the manufacturis industry

Silva, Glauco Roberto Pereira 28 June 2016 (has links)
Submitted by Nadir Basilio (nadirsb@uninove.br) on 2016-09-19T16:08:08Z No. of bitstreams: 1 Glauco Roberto Pereira Silva.pdf: 1708203 bytes, checksum: ca08ce102b8eb3c727f8ce1f156f6daf (MD5) / Made available in DSpace on 2016-09-19T16:08:08Z (GMT). No. of bitstreams: 1 Glauco Roberto Pereira Silva.pdf: 1708203 bytes, checksum: ca08ce102b8eb3c727f8ce1f156f6daf (MD5) Previous issue date: 2016-06-28 / The Brazilian manufacturing industries have faced stiff global competition from factories in Europe, USA and Asia, requiring the same monitoring crucial factors to remain competitive. In general, these companies have performance indicators considered key in comparison units. However, the academic literature in the context of maintenance costs, little has addressed specifically on the impact of the use of OEE - Overall Equipment Effectiveness, indicator used to measure the overall effectiveness of equipment and production systems - in reducing maintenance costs. This work questions the extent to which manufacturing companies in Brazil know the impact on the results of production systems, and more particularly about the cost of maintenance. It also presents the objective of understanding the understanding of business impacts on the TPM and OEE bring about the management of maintenance and the costs of this activity. To achieve this goal, we used an exploratory survey as a practical exemplification, illustrating the results of applying the proposed concepts in industrial maintenance activities in manufacturing companies. The aforementioned results demonstrated that both the TPM and the OEE bring effective contributions to increase productivity, quality and competitiveness, and reduce maintenance costs, and that most of the companies studied have clarity that. / As indústrias de manufatura brasileiras têm enfrentado acirrada competição global com empresas da Europa, USA e Ásia, exigindo das mesmas o monitoramento de fatores cruciais para se manter competitivas. De maneira geral, essas empresas possuem um conjunto de indicadores de desempenho considerados como chave na comparação entre unidades. No entanto, a literatura acadêmica, no contexto dos custos de manutenção, pouco tem abordado, especificamente, sobre o reflexo do uso do OEE - Overall Equipment Effectiveness, indicador utilizado para medir a efetividade geral dos equipamentos e dos sistemas de produção - na redução de custos de manutenção. O presente trabalho questiona em que medida as empresas de manufatura no Brasil conhecem os impactos sobre os resultados dos sistemas de produção e, mais particularmente sobre o custo de manutenção. Apresenta ainda como objetivo compreender a compreensão das empresas sobre os impactos que o TPM e o OEE trazem sobre a gestão da manutenção e sobre os custos dessa atividade. Para atingir tal objetivo, utilizou-se uma survey exploratória como uma exemplificação prática, ilustrando os resultados da aplicação dos conceitos propostos nas ações de manutenção industrial em empresas de manufatura. Os resultados apontados demonstraram que tanto o TPM e quanto OEE trazem contribuições efetivas para aumentar a produtividade, qualidade e competitividade, e reduzir custos de manutenção, e que a maior parte das empresas estudadas têm clareza disso.
5

LIVSCYKELKOSTNAD (LCC) : En jämförelse mellan en tvärspänd plattbro i limträ och en samverkansbro / LIFE CYCLE COST (LCC) : A comparison between a prestressed glulam deck bridge and a composite bridge

El Ladki, Inaya, Gümüs, Leylafer January 2018 (has links)
This essay is a bachelor thesis written for the Degree Program in Constructional Engineering and Design at The Royal Institute of Technology (KTH). This thesis was an assignment given by WSP Sweden and their bridge and water department. The purpose of this report is to conduct an examination on the Life Cycle Cost (LCC) on a prestressed glulam deck bridge and a composite bridge in the early stages of the design phase. This report illuminates the factors that are most crucial in a LCC-calculation for the selected overpasses, and provides an overview regarding which overpass is most efficient from an economic standpoint. The LCC has been calculated based on an 80-year lifespan for the prestressed glulam deck bridge and a 120-year lifespan for the composite bridge. The cost of investment, operating, maintaining and finally the demolition cost was all considered as well. The bridge works that were examined are real life projects in an early stage of the design phase with plans to be built. In the results, the LCC-analysis shows a clear difference in life cycle costs between the prestressed glulam deck bridge and the composite bridge and show that the cost of investment is the most decisive cost during the bridges’ lifespans. The LCC-calculations show that the total life cycle cost for a prestressed glulam deck bridge is higher than the composite bridges’ total life cycle cost.
6

Cost Effective Maintenance for Competitve Advantages

Alsyouf, Imad January 2004 (has links)
This thesis describes the role of cost effective maintenance in achieving competitive advantages. It explores by means of a survey which maintenance practices are used, and how maintenance policies are selected in Swedish industries. Also, it suggests a model for selecting the most cost effective maintenance policy, and how to improve the effectiveness of condition based maintenance decision-making. Finally it discusses how to assess the impact of maintenance practices on business strategic objectives. The main results achieved in the thesis are 1) A better understanding of maintenance organisation, management, systems and maintenance status in Swedish industry. For example, it was found that about 70% of Swedish companies still consider maintenance as a cost centre. Preventive and predictive maintenance approaches are also emphasised. 2) Most Swedish firms, i.e. about 81%, use the accumulated knowledge and experience within the company as a method for maintenance selection. Besides, about 31% use a method based on modelling the time to failure and optimisation. About 10% use failure mode effect and criticality analysis (FMECA) and decision trees and only 2% use multiple criterion decision-making (MCDM). However, the most used maintenance selection method is not the one most satisfactory to its users. Furthermore, about 30% use a combination of at least two methods. 3) A practical model for selecting and improving the most cost effective maintenance policy was developed. It is characterised by incorporating all the strengths of the four methods used in industry. 4) A mechanistic model for predicting the value of vibration level was verified both at the lab and in a case study. 5) A model for identifying, assessing, monitoring and improving the economic impact of maintenance was developed and tested in a case study. Thus it was proved that maintenance is no longer a cost centre, but could be a profit-generating function. To achieve competitive advantages, companies should do the right thing, e.g. use the most cost effective maintenance policy, and they should do it right, e.g. ensure that they have the right competence. Furthermore, they should apply the never-ending improvement cycle, i.e. Plan-Do-Check-Act, which requires identifying problem areas by assessing the savings and profits generated by maintenance and monitoring the economic impact of the applied maintenance policy. Thus, they would know where investments should be allocated to eliminate the basic reasons for losses and increase savings. The major conclusion is that proper maintenance would improve the quality, efficiency and effectiveness of production systems, and hence enhances company competitiveness, i.e. productivity and value advantages, and long-term profitability.
7

Maintenance impact on company´s profitability and competitiveness : Underhålls påverkan i företags lönsamhet och konkurrens

Al-Najjar, Hamid January 2007 (has links)
<p>Abstract</p><p>The aim of this thesis is to show the company the importance and the necessity of the maintenance, trough highlighting its role and impact on company’s profitability and competitiveness, and that’s happened within the analysing of the plant to figure out the failures and short stoppages, find out the causes behind them, convert them into money and the last step is to find out the most suitable and cost effective maintenance strategy based on some important factors such as economy, and quality to probably eliminate or reduce the number of failures and short stoppages. According to the analysis, capacity verifying data collection which the company has done during a random working daily shift and a technical faults list about the possibly failures and short stoppages which occur during the operation, it shows that there are some downtime due to management, operation and logistic, but the main focus was on the technical faults which has correlation with maintenance. In the result it shows which technical and mechanical problems the machines usually faces, the causes behind them, how much it cost the company when they breaks down and finally some suggestions and recommendations about how these problems can probably be solved based on economy and quality.</p> / <p>Sammanfattning</p><p>Syftet med denna rapport är att visa hur viktigt och nödvändigt det är med att underhålla företagens maskiner och utrustningar, därför att det har stor påverkan på företagens lönsamhet och konkurrens och det skedde genom att analysera företagens produktions process, lista ut haverier och avbrott, hitta orsakerna som ligger bakom det, konvertera det till pengar och försöka lösa problemen genom att hitta den mesta lämpligaste underhåll strategi baserande på ekonomi och kvalitet. Enligt analysen som utfördes genom studiet, kapacitet verifiering data insamlingen som företaget gjorde under en slumpmässig arbetsdag skift och ett tekniskt fel lisat på eventuella avbrott och haverier. Det visade sig att det finns vissa stopp tider som har samband med management, operation, och logistik, men uppgiften är mer fokuserad på de tekniska problemen som har samband med underhåll. I resultatet ser man vilka tekniska och mekaniska problem som brukar angripa maskinerna, orsakerna som ligger bakom de, hur mycket det kostar företaget för varje maskin när den är ur funktionen, samt några förslag på eventuella lösningar och rekommendationer baserande på ekonomi och kvalitet.</p>
8

Maintenance impact on company´s profitability and competitiveness : Underhålls påverkan i företags lönsamhet och konkurrens

Al-Najjar, Hamid January 2007 (has links)
The aim of this thesis is to show the company the importance and the necessity of the maintenance, trough highlighting its role and impact on company’s profitability and competitiveness, and that’s happened within the analysing of the plant to figure out the failures and short stoppages, find out the causes behind them, convert them into money and the last step is to find out the most suitable and cost effective maintenance strategy based on some important factors such as economy, and quality to probably eliminate or reduce the number of failures and short stoppages. According to the analysis, capacity verifying data collection which the company has done during a random working daily shift and a technical faults list about the possibly failures and short stoppages which occur during the operation, it shows that there are some downtime due to management, operation and logistic, but the main focus was on the technical faults which has correlation with maintenance. In the result it shows which technical and mechanical problems the machines usually faces, the causes behind them, how much it cost the company when they breaks down and finally some suggestions and recommendations about how these problems can probably be solved based on economy and quality. / Syftet med denna rapport är att visa hur viktigt och nödvändigt det är med att underhålla företagens maskiner och utrustningar, därför att det har stor påverkan på företagens lönsamhet och konkurrens och det skedde genom att analysera företagens produktions process, lista ut haverier och avbrott, hitta orsakerna som ligger bakom det, konvertera det till pengar och försöka lösa problemen genom att hitta den mesta lämpligaste underhåll strategi baserande på ekonomi och kvalitet. Enligt analysen som utfördes genom studiet, kapacitet verifiering data insamlingen som företaget gjorde under en slumpmässig arbetsdag skift och ett tekniskt fel lisat på eventuella avbrott och haverier. Det visade sig att det finns vissa stopp tider som har samband med management, operation, och logistik, men uppgiften är mer fokuserad på de tekniska problemen som har samband med underhåll. I resultatet ser man vilka tekniska och mekaniska problem som brukar angripa maskinerna, orsakerna som ligger bakom de, hur mycket det kostar företaget för varje maskin när den är ur funktionen, samt några förslag på eventuella lösningar och rekommendationer baserande på ekonomi och kvalitet.

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