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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

Maintenance models for repairable systems with general degree of repair

Bhurtun, Rakesh 02 April 2009 (has links)
Abstract unable to load
2

Sensor Deployment and Coverage Maintenance by a Team of Robots

Li, Qiao January 2015 (has links)
Wireless sensor and robot networks (WSRNs) are an integration of wireless sensor network (WSNs) and multi-robot systems. They comprise of networked sensor and mobile robots that communicate via wireless links to perform distributed sensing and actuation tasks in a region of interest (ROI). In addition to gathering and reporting data from the environment, sensors may also report failures of neighboring sensors or lack of coverage in certain neighborhood to nearby mobile robot. Once an event has been detected, robots coordinate with each other to make a decision on the most appropriate way to perform the action. Coverage can be established and improved in different ways in wireless sensor and robot networks. Initial random sensor placement, if applied, may be improved via robot-assisted sensor relocation or additional placement. One or more robots may carry sensors and move within the ROI; while traveling, they drop sensors at proper positions to construct desired coverage. Robots may relocate and place spare sensors according to certain energy optimality criteria. This thesis proposes a solution, which we call Election-Based Deployment (EBD), for simultaneous sensor deployment and coverage maintenance in multi-robot scenario in failure-prone environment. To our knowledge, it is the first carrier-based localized algorithm that is able to achieve 100% coverage of the ROI with multiple robots in failure-prone environment since it combines both sensor deployment and coverage maintenance process. We can observe from the simulation results that EBD outperforms the existing algorithms and balances the workload of robots while reducing the communication overhead to a great extent.
3

High-Maintenance Friendships and Adjustment in Late Adolescents and Young Adults in a College Setting: A Mixed Methods Analysis

Fedigan, Shea Kelly January 2017 (has links)
Thesis advisor: James R. Mahalik / Objectives. Adolescent friendships play a particularly critical role in one’s physical, social, and emotional development. Difficult, inequitable, friendships in late adolescence and young adulthood are particularly concerning as the experience one has in these formative friendships can negatively impact one’s physical and psychological development (Ehrlich, Hoyt, Sumner, McDade, & Adam, 2015; Engels & Bogt, 2001; Hartup, 1996; Parker, Rubin, Erath, Wojslawowicz, & Buskirk, 2006). The goal of this dissertation was to examine one particular type of problematic and inequitable peer relationship experienced in late adolescence and young adulthood, colloquially termed a “high-maintenance” friendship. Specifically, this study examined the association between high-maintenance friendships and social emotional adjustment in late adolescents and young adults in a college setting and had four overarching purposes. First, it provided a preliminary definition for the construct of high-maintenance friendships among late adolescents and young adults in a college setting. Second, it explored late adolescents’ and young adults’ beliefs around why they have stayed in friendships that were high-maintenance. Third, the study applied the principles of interdependence theory to high-maintenance friendships and examined whether individual-level factors such as self-esteem, behavioral expectations, attachment style, loneliness, and gender were linked to the likelihood that one will stay in a high-maintenance friendship. Fourth, the study explored whether the degree to which a high-maintenance friendship impacted one’s emotional well-being (i.e., making them upset) was associated with one’s likelihood of staying in the high-maintenance friendship. Method. Participants were 256 late adolescents and young adults from a mid-size, elite, private university in the Northeastern United States (Mage = 19.09 years; 53.1% female). A mixed method, two-phase, exploratory, sequential design was implemented across two phases. The first phase implemented a qualitative content analysis in an effort to identify, develop, and define the construct high-maintenance friendships. The second phase of the study utilized a series of hierarchical linear regression analyses to explore the relationships between individual level characteristics and one’s likelihood of staying in high-maintenance friendships. Results. Qualitative analyses yielded a three-factor model, suggesting that late adolescents and young adults conceptualize the most salient characteristics of a high-maintenance friendship as: 1. one sidedness, 2. requiring substantial effort, and 3. general high expectations. Additionally, qualitative analyses generated a four-factor model of environmental obstacles that late adolescents and young adults recognized as why they stayed in a high-maintenance friendship: 1. positive friendship qualities, 2. shared experiences, 3. shared contexts, and 4. decrease in high-maintenance behavior over time. Quantitative analyses challenged the study’s hypotheses and indicated that lower levels of emotional closeness expectations and lower levels of avoidant attachment style predict to increased likelihood of staying in a cross-sex high-maintenance friendship. Quantitative analysis also indicated that the more a participant endorsed that the high-maintenance friendship impacted their emotional well-being, the less likely they were to stay in the friendship. Conclusions. The findings across the four phases of this study extend the current literature on difficult peer friendships in late adolescence and young adulthood by highlighting that: (a) high-maintenance friendships are inequitable, but those who experience social emotional distress in the friendship tend to not stay in the friendships, (b) there may be an optimal level of tolerable inequity which one can have in a close friendship without experiencing social emotional distress, and (c) there may be ways to increase one’s social emotional resilience and to restore an optimum level of inequity, even in problematic, high-maintenance friendships. / Thesis (PhD) — Boston College, 2017. / Submitted to: Boston College. Lynch School of Education. / Discipline: Counseling, Developmental and Educational Psychology.
4

Variation in energy expenditures between growing steers with divergent residual feed intakes

White, Monte Blaine III 12 April 2006 (has links)
Objectives of this study were to determine if variation in energy expenditures contributed to differences in feed efficiency between low and high RFI steers. Nine steers with the lowest and highest residual feed intakes (RFI) were selected from 169 Braunvieh-sired crossbred steers that were individually fed a pelleted roughage-based diet for 77 d. Following the RFI measurement period, heat production (HP) measurements were obtained using indirect calorimetry while steers were fed the same roughage diet (RD) and on a high-concentrate diet (CD). Linear regression analyses of log HP or retained energy on ME intake were used to determine energy partitioning. Motion and lying activity were measured concurrently with HP on the RD and CD. During the RFI measurement period, low RFI steers had lower (P < 0.01) RFI (-1.7 vs. 1.6 ± 0.17 kg/d), DMI (7.7 vs. 10.2 ± 0.42 kg/d) and feed:gain ratio (F:G; 7.2 vs. 10.6 ± 0.60), but similar final BW and ADG compared to high RFI steers. However, there were smaller differences in DMI (8.4 vs. 9.7 ± 0.38 kg/d; P < 0.05; 7.56 vs. 8.16 ± 0.31; P = 0.19) and F:G (10.0 vs. 10.9 ± 0.40; P = 0.36; 6.5 vs. 7.5 ± 0.30; P < 0.05) between low and high RFI steers, on the RD and CD, respectively. ME for maintenance (MEm; kg .75 d–1) and the partial efficiencies of ME used for maintenance and gain were similar for low and high RFI steers. Likewise, no differences were found in fasting HP or fed HP. Motion activity was lower (P < 0.05) for low RFI steers compared to high RFI steers during fasting HP. Covariate analysis of HP at the same activity level yielded similar results. At slaughter, weights of lung and trachea (P < 0.05), spleen (P < 0.05) and adrenal gland (P = 0.07) were higher for low RFI cattle. The lack of differences in energy partitioning between divergent RFI steers may have been the result of alterations in feeding behavior or stress imposed by adapting steers to calorimetry chambers.
5

Identifiering av faktorer som kan påverka produktionseffektivitet : En fallstudie / Identification of factors that can affect production efficiency : A case study

Ahlqvist, Carl, Meijer, Niklas January 2015 (has links)
Tillverkande företag möter idag en allt hårdare konkurrens genom den globalisering av marknaden som sker. En global marknad med flera konkurrenter, ökad produktdifferentiering och höga tillverkningskostnader ställer stora krav på företag att arbeta kostnadseffektivt. För att vara konkurrenskraftig och driva en lönsam produktion krävs att förretag har en stor kännedom om hur sina tillverkningsprocesser fungerar, har en hög driftsäkerhet och kan utnyttja sin anläggnings kapacitet.   Grunden till studien är det industriella lönsamhetsproblem som finns i Sverige, där företag får allt svårare att kunna producera kvalitativa produkter till ett konkurrenskraftigt pris. Fallstudien utförs på ett företag som tillverkar komponenter för fordonsindustrin, med syftet att skapa en ökad förståelse kring de faktorer som leder till produktionsstörningar och har stor effekt på produktionseffektiviteten i ett flöde. För att sedan kunna motverka dessa och utnyttja företagets kapacitet på bättre sätt och skapa en hög konkurrenskraft och lönsamhet.   Utifrån analysmodell studeras och beskrivs först nuläget hos fallföretaget. Därefter sker en analys av nuläget då empiri jämförs med relevant teori. Analysen redovisar sedan genom mätvärden de faktorer som leder till störningar i produktionsflödet och påverkar produktionseffektiviteten. Slutligen utvärderas faktorerna och en redogörelse för vad de beror på klargörs. Det resultat som fallstudien påvisar är de väsentliga faktorer som påverkar produktionseffektiviteten, samt att de underliggande orsakerna till dessa bör motverkas för att skapa en högre driftsäkerhet och produktionseffektivitet i flödet. Granskning av faktorer och orsaker skapar ett underlag för förbättringar som bör tillämpas för att bibehålla en lönsam produktion och konkurrenskraft. Fallstudiens syfte är att identifiera och skapa förståelse för vilka faktorer som påverkar produktionseffektivitet på ett tillverkande företag. Målsättningen är att skapa en bild av det nuvarande tillståndet på företaget och utifrån detta ta fram empirin. Empiri och utvalda teorier leder således till en analys som ska identifiera och sammanställa de faktorer som är väsentliga att motverka för att förbättra driftsäkerheten och produktionseffektiviteten på fallföretaget. I slutsatsen redovisas hur företaget kan arbeta för att motverka och minska faktorernas påverkan på produktionseffektiviteten. / Manufacturing industries are today facing increasing competition through the globalization of the market that takes place. A global market with several competitors, increased product differentiation and the high cost of production makes great demands on companies to work cost effectively. To be competitive and operate a profitable production requires companies to have a great knowledge of how their manufacturing processes work, has a high reliability and can use their facility's capacity.   The basis for the study is the industrial profitability problems in Sweden, where companies find it increasingly difficult to produce quality products at a competitive price. The case study performed in a company which manufactures components for the automotive industry, with the aim to create a better understanding of the factors that lead to production disruptions and has great effect on the production efficiency of a flow. In order to be able to counter them and exploit the capacity of a better way and create a high level of competitiveness and profitability.   Based on the analytical study and first described the present situation of the case now. This is followed by an analysis of the current situation where empiricism is compared with the relevant theory. The analysis then reports the measured values ​​of the factors that lead to disturbances in the production flow and affect production efficiency. Finally, the evaluation factors and an explanation of what they are due to be clarified. It results that the case study demonstrates the significant factors affecting production efficiency, as well as the underlying causes of these should be tackled in order to create a higher level of reliability and production efficiency in the flow. Examination of factors and causes creates a basis for the improvements that should be applied to maintain profitable production and competitiveness.
6

Ilgalaikės nuomos prekybos sistemos priežiūros modeliai / Maintenance models of PAT system

Katutis, Artūras 25 May 2004 (has links)
Software engineering is defined as the application of the systemic, disciplined, quantifiable approach to the development, operation, and maintenance of software. It is the application of engineering to software. The classic life-cycle paradigm for software engineering includes: system engineering, analysis, design, code, testing, and maintenance. Maintenance is needed to ensure that the system continues to satisfy user requirements. The system changes due to corrective and non-corrective maintenance. According to Martin and McClure, maintenance must be performed in order to: • Correct errors; • Correct design flaws; • Interface with other systems; • Make enhancements; • Make necessary changes to the system; • Make changes in files or databases; • Improve the design; • Convert programs so that different hardware, software, system features, and telecommunications facilities can be used. Accordingly, software must evolve and be maintained. This paper addresses the maintenance portion of PAT life-cycle. There are several improved architecture models presented witch make maintenance and evolution of PAT easier. Among the presented architecture models there is one model (with five layers) witch was adapted to the system. The new system’s efficiency was compared with the old one’s. This paper also contains a new architecture model witch could be adapted to the new systems. The main purpose of this architecture is to separate graphical user interface from system’s business logics... [to full text]
7

Volymbaserat underhåll / Volume based maintenance

Axelsson, Patrik, Korhonen, Sanna January 2021 (has links)
Examensarbetet utfördes på Scania Industrial Maintenance. Historiskt på Scania har intervallerna för det förebyggande underhållet (FU) på produktionsutrustningen bestämts baserat på kalenderdatum. Då kalenderdatum inte tar hänsyn till produktionsutrustningens faktiska användning så anpassas inte underhållet efter användningen. Detta kan leda till att för mycket eller för lite underhåll utförs i förhållande till användandet. Om för mycket underhåll utförs är detta kostsamt eftersom arbete och utbyten av reservdelar utförs i onödan. Samtidigt som för lite underhåll leder till att maskinerna går sönder när dom är planerade att användas vilket är väldigt kostsamt för företaget. På grund av detta önskar Scania att övergå till att utöver det kalenderbaserade intervallet även kunna bestämma intervallerna för det förebyggande underhållet baserat på produktionsvolymen. Målet med arbetet var att ta fram metoder samt process vilka beskriver hur Scanias fabriker i Södertälje, inom ramen för Future Powertrain Program (FPP), ska övergå till ett underhållsintervall baserat på volym. Dessa metoder ska sedan testas i två piloter, en pilot på Scanias axel- och växellådsmontering och den andra piloten på Scanias motorbearbetning. För att öka projektgruppens kunskap inom de ämnen vilka innefattades av projektet utfördes litteraturstudier på rapporter, artiklar och i faktaböcker. Litteraturstudier utfördes även under arbetets gång på sådant som inte täckts av arbetets initiala litteraturstudie. Utöver litteraturstudien har även en dokumentstudie utförts på företagets interna dokument och omfattade bland annat beredningsprocessen och instruktioner för Maximo vilket är det underhållsystem som används på Scania. Vidare utfördes även intervjuer av personal på Scania IM och Scania under arbetets gång då projektmedlemmarna önskade få insikt i verksamheten och de befintliga arbetssätten. Genom att avgränsa arbetet har fokuset legat på att realisera teorin på ett mindre område för att undersöka ifall denna omställning är möjlig att genomföra. De utvalda pilotområdena på DT och DM studerades i avseende på både organisation och produktionsutrustning. Dessa studier tillsammans med projektets litteraturstudie och dokumentstudie låg sedan som grund vid framtagandet av metoderna. De inom projektet framtagna metoderna testades i pilot på de utvalda områdena och utrustningarna. Piloterna vilka utfördes inom projektet var lyckade och Scania har som avsikt att inte återgå utan i stället utvidga områdena där projektets framtagna metoder ska användas. Resultatet av detta arbete är att det kommer utföras ett mer exakt underhåll i förhållande till det kalenderbaserade underhållet. Projektgruppen kunde även konstatera att säkerheten i verkstäderna skulle kunna höjas vid tillämpning av projektets framtagna metoder. Detta då underhållet som utförs på t.ex. nödstopp eller andra säkerhetsfunktioner utförs i proportion med utrustningens användning, därmed kan säkerheten säkerställas även vid höga produktionstakter. Metoderna framtagna inom projektet tar hänsyn till ifall utrustningen omfattas av garanti eller myndighetskrav. Dessutom tar de hänsyn till förebyggande underhållets längd och om FU:t omfattar ronder, underhåll för operatörer (UFO), periodiska utbyten eller säkerhet. Alla dessa faktorer påverkar vilka åtgärder som ska vidtas på det kalenderstyrda och volymbaserade FU:t vilket resulterar i en anpassad och förbättrad FU plan. / The thesis project was performed at Scania Industrial Maintenance. Historically, the intervals of the preventive maintenance for the production equipment have been determined based on calendar dates. As the calendar date does not take the actual use of the production equipment into account the maintenance is not adapted to this use. This could lead to either too much or too little maintenance is being performed in relation to the use of the equipment. When too much maintenance is performed, work and replacement of spare parts are performed when not needed which brings unnecessary costs for the company. At the same time, too little maintenance will instead lead to breakdowns when the machines are planned to be used, which could be very costly for the company. Because of this, Scania now wishes to proceed to determine the intervals for the preventive maintenance based on the production volume. The objective of the work was to develop methods and processes that describe how Scania's factories in Södertälje, within the framework of the Future Powertrain Program (FPP), will transition to a maintenance interval based on volume. These methods shall then be tested in two pilots, one pilot at Scania's axle and gearbox assembly and the other pilot at Scania's engine processing. To increase the project group's knowledge of subjects covered by the project, literature studies were carried out on reports, articles and in fact books. Literature studies were also performed during the course of the work on subjects that were not covered by the work's initial literature study. In addition to the literature study, a document study was also performed on the company's internal documents and included, among other things, the preparation process and instructions for Maximo, which is the maintenance system used at Scania. The project group also conducted interviews with staff at Scania IM and Scania during the work as the project members wanted to gain insight into the business and the existing ways of work. By delimiting the work, the focus has been on realizing the theory on a smaller area to investigate whether this transition is possible to implement. The selected pilot areas located at DT and DM were studied with regards to both organization and production equipment. These studies, together with the project groups literature study and document study, were then used when developing the methods. The methods developed within the project were tested in pilots on selected areas and equipment. The pilots that were carried out within the project were successful and the aim for Scania now is not to return to calendar-based maintenance but instead expand the use of themethods developed by this project. The result of this work is that a more accurate maintenance will be performed in relation to the calendar-based maintenance. The project group could also state that the safety in the workshops could be increased when applying the project's developed methods. This is because the maintenance performed on e.g. emergency stops or other safety functions are performed in relation to the use of the equipment. The methods developed within the project takes into account whether the equipment is covered by warranty or regulatory requirements. They also take into account the length of the PM and whether the PM includes routes, operator maintenance, periodic exchanges or security. These factors decides which measures needs to be taken on the calendar-controlled and volume-based PM, which results in an adapted and improved PM plan.
8

Modèle de coût d’exploitation-maintenance et gestion en coût global des bâtiments hospitaliers : application en ingénierie hospitalière / Operation cost model and whole life cycle cost for healthcare facility management : application of hospital engineering

Sliteen, Samer 23 November 2011 (has links)
Le contexte hospitalier actuel exhorte les établissements de santé à une gestion plus rigoureuse et objective des ressources dans le but de maitriser leur performance. Le patrimoine immobilier des établissements publics de santé contribue à la qualité des soins demandée, à la qualité d'accueil des patients et des conditions de travail du personnel. Aujourd'hui, les hôpitaux demeurent conçus et réalisés sans aucune anticipation des coûts futurs d'exploitation-maintenance. Ces coûts qui représentent indéniablement une valeur importante du budget global de fonctionnement, sont pourtant méconnus. Afin de palier à la faiblesse des moyens de financement public, l'administration a comme recours la mise en place d'une nouvelle procédure de contrats de Partenariat Public Privé. Or celle-ci ne dispose pas d'un minimum d'informations en terme de connaissances sur les dépenses d'exploitation-maintenance actuelles de son patrimoine. Dans ce contexte, le coût global constitue une approche innovante dans la gestion des projets immobiliers.La problématique développée dans ce travail de thèse est donc d'approfondir les connaissances en amont des coûts d'exploitation-maintenance des bâtiments hospitaliers. Elle apporte un éclairage sur la relation entre les coûts d'exploitation-maintenance et l'activité hospitalière. Elle propose ainsi une réponse plus adaptée et plus opérationnelle à la question de l'estimation de ces coûts d'exploitation-maintenance en aidant le maître d'ouvrage à prendre en compte l'activité de soin et les choix architecturaux dans son projet. Cela revient à proposer une méthode d'aide à la décision pour construire un bâtiment hospitalier qui minimise les dépenses futures de fonctionnement. Cette méthode s'appuie sur un modèle d'estimation et sur un observatoire des coûts d'exploitation-maintenance réel de 37 établissements publics de santé. / The current situations of hospitals require more efficient management in order to control their performance. The real estates of public hospitals contribute to the quality of required healthcare, the quality of patient care and working conditions of healthcare staff.Today, hospitals are designed and built without anticipating of future evolution of operation and maintenance costs. These costs that are an important contribution to the value of the overall operating budget are underestimated and far unknown.To overcome the lack of public finance, the government has so used the Public Private Partnership Contracts as a new procedure. Yet the government does not have a minimum of information about operating and maintenance expenses of its real estates. In this context, the Whole Life Cycle Costing is an innovative approach in managing public healthcare real estate projects.The problem developed in this thesis is to expend is to expend the knowledge of operation and maintenance costs of healthcare real estates. This thesis highlights the relationship between operating and maintenance costs and hospital activity. It proposes a more efficient response in the issue of estimating these costs by helping the director to take into account the healthcare activity and the architectural choices. It provides a decision making tool for designing and building a new hospitals for minimizing future costs of operation.This method is based on a model for estimating costs and on an observatory of real operation and maintenance costs of 37 public hospitals.
9

Návrhy na zlepšení hospodaření s dlouhodobým hmotným majetkem / Improvement Proposals for Long Term Asset Management of a Company

Bělehrádek, Tomáš January 2016 (has links)
Master thesis deals with the management of tangible fixed assets in the company Ecolab Hygiene s.r.o. which is engaged in purchase and sale of cleaning, desinfectant and sanitazing detergents, rental and repairs of cleaning machines and equipement. Introductory part is focused on theoretical bases. Second part of the thesis is focused on analysis of tanglibe fixed assets in the company and property maintenance. Based on analysis established knowledge there are subsequently weaknesses identified. In the final part solutions are proposed including their economic aspect whose implementation should have possitive impact on the current status improvement.
10

Kondiční závislost druhotných ornamentů a výběr partnera u koroptve polní Perdix perdix) / Condition dependence of secondary ornamentation and mate choice in Grey Partridges

Gabrielová, Barbora January 2012 (has links)
This study focuses on relationships between individual condition, measures of ornament expression and mate choice in the Grey Partridge (Perdix perdix). It is based on the correlative data as well as results of manipulative experiments. I found positive correlation between the size of melanin- and carotenoid-based ornaments in partridges. The size and the redness of the carotenoid skin patch, and the size of the melanin-based feather ornamentation were associated with several measures of immunity and overall body condition (complement activity, ratio of immature erythrocytes, heterophil/leucocyte ratio, response to novel antigen). Furthermore, data from natural populations indicate that the expression of carotenoid-based ornamentation is associated with sexual attractiveness (measured as the ability to obtain a social mate) in partridges. Data from captive individuals indicate that carotenoid supplementation improves the redness of carotenoid-based ornament, while the stimulation of the immune system under increasing concentrations of supplemented carotenoids has no measurable effect on condition and physiological state. This seems to contradict predictions of the 'Carotenoid maintenance hypothesis'. Overall, results better understanding the role of carotenoid and melanin-based ornamentation in signaling...

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