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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

Progress towards a total synthesis of (+-)-Longithorone C

Zakarian, Joseph E. January 2007 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.
42

Préparation et caractérisation de nouveaux catalyseurs de métathèse asymétrique

Fournier, Pierre-André January 2007 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.
43

Isomerisation and ring closing metathesis reactions towards benzo-fused heterocyclic compounds

Aderibigbe, Blessing Atim 01 November 2006 (has links)
Student Number : 0410864E - MSc dissertation - School of Chemistry - Faculty of Science / The aim of the project described in this dissertation is to explore the application of ring closing metathesis (RCM) to the synthesis of 6-, 7-, 8- and 9-membered N,N-, N,O- and O,O-benzo-fused heterocyclic compounds which are interesting structural motifs in medicinal chemistry. In recent times, their structures have been widely used as molecular scaffolds. Some of these heterocycles have been identified as antitumour agents, antibiotics and anti-HIV agents. In our laboratories, a variety of 6-, 7- and 8-membered nitrogen- and oxygen- containing benzo-fused rings have been synthesized through ruthenium-mediated isomerisation and RCM in moderate to good yields. The first step in the present project was N-protection of suitable 2-aminophenols or o-phenylenediamines followed by allylation. Rutheniummediated isomerisation followed by RCM was then used for the synthesis of the 6- membered ring system tert-butyl 4H-1,4-benzoxazine-4-carboxylate 91 and the 7- membered ring system tert-butyl 1,5-benzoxazepine-5(4H)-carboxylate 103 while only RCM was used for the 8-membered ring systems, di(tert-butyl) 2,3,4,5-tetrahydro-1,6- benzodiazocine-1,6-carboxylate 130, di(tert-butyl) 2,5-dihydro-1,6-benzodiazocine-1,6- dicarboxylate 129, 1,6-dibenzoyl-1,2,5,6-tetrahydro-1,6-benzodiazocine 132, 7-methoxy- 2,5-dihydro-1,6-benzodioxocine 137 and the 9-membered ring system 1,6-bis[(4- methylphenyl)sulfonyl]-2,5,6,7-tetrahydro-1H-1,6-benzodiazonine 159. In the synthesis of the 7-membered ring systems, based on established methodology, we encountered problems with the RCM from suitable benzylamine or benzyl alcohol precursors. The reasons for this are not clear but we suspect this could be as a result of electronic and kinetic factors. Nevertheless, we were able to synthesize a 7-membered ring system, tert-butyl 1,5-benzoxazepine-5(4H)-carboxylate 103, from a readily available precursor using a different methodology. Approaches to the synthesis of the 8-membered ring systems, di(tert-butyl) 2,3,4,5- tetrahydro-1,6-benzodiazocine-1,6-carboxylate 130, di(tert-butyl) 2,5-dihydro-1,6- benzodiazocine-1,6-dicarboxylate 129, 1,6-dibenzoyl-1,2,5,6-tetrahydro-1,6- benzodiazocine 132 and 7-methoxy-2,5-dihydro-1,6-benzodioxocine 137, as described in this dissertation, made extensive use of RCM in moderate to good yields, but the deprotection of the Boc group after hydrogenation proved to be a problem. The synthesis of the 9-membered nitrogen containing benzo-fused compounds, 1,6- bis[(4-methylphenyl)sulfonyl]-2,5,6,7-tetrahydro-1H-1,6-benzodiazonine 159 by RCM was successful but in the synthesis of the N,O-benzo-fused compound by RCM, we suspect that polymerization, which is a side reaction in RCM reactions that are slow, occurred. In the synthesis of the 9-membered O,O-benzo-fused compounds, we only isolated the starting material. The final approach in this dissertation involved the use of ruthenium-mediated isomerisation to afford internal isomerisation of the double bond within the heterocyclic rings of the 8-membered and 9-membered benzo-fused compounds previously prepared in our laboratory. This gave a mixture of regioisomers of 10-methoxy-2,3-dihydro-1,6- benzodioxocine 163 and 7-methoxy-2,3-dihydro-1,6-benzodiazocine 164, 1,6-bis[(4- Methylphenyl)sulfonyl]-1,2,3,6-tetrahydro-1,6-benzodiazocine 166, a regioisomeric mixture of 6-[(4-methylphenyl)sulfonyl]-3,6-dihydro-2H-1,6,-benzoxazocine 161 and 6-[(4-methylphenyl)sulfonyl]-5,6-dihydro-4H-1,6,-benzoxazocine 162, and the 9- membered benzo-fused ring system, 1,6-bis[(4-methylphenyl)sulfonyl]-2,3,6,7- tetrahydro-1H-1,6-benzodiazonine 170. The yields were good and the solid state structures of these isomerised compounds were examined by X-ray crystallography. Xray diffraction was also performed on the solid state 8- and 9-membered benzo-fused ring systems. We also compared the crystal structures of the 8- and 9-membered benzo-fused compounds with their isomerised compounds.
44

Reliability-centred maintenance for electric power distribution systems

Bertling, Lina January 2002 (has links)
No description available.
45

Upprättande av underhållsplan för rullkanal LRQ på SKF, gällande pressutrustning : Examensarbete i flygteknik

Pettersson, Lars January 2010 (has links)
Denna rapport behandlar arbetet kring att ta fram åtgärder för förebyggande underhåll på en kanal för tillverkning av rullar till rullager, vid SKF i Göteborg. Målet har varit att upprätta ett grundläggande underhållsprogram, med fokus främst på operatörsunderhåll, med syftet att få ner antalet oplanerade driftstopp. Upplägget var att först knyta samman den kunskap som fanns samlad på företaget, många av kanalens maskiner var av äldre modell och har funnits i produktionen i många år, varför det visade sig finnas många personer med erfarenhet på dem på olika positioner. Samtal fördes med främst operatörer, tekniker och mekaniker, då det är dessa personer som arbetar närmast och mest med maskinerna, i syfte att isolera de mest frekventa felområdena. Analysen resulterade i en lista med förslag på åtgärder, vilken gicks igenom grundligt med, på maskinerna, kunnig och erfaren  personal.  Detta  ledde till att listan så småningom kom att omfatta till synes relevanta underhållspunkter, med förslag på åtgärd, intervall och utförare. Nästa steg var att gå djupare i komponentnivå på en enstaka maskin, den viktigaste och mest kritiska på kanalen, nämligen själva pressen, med vilken man pressar råmaterial, kallat kuts, till rullar. Vilka efter slipning/polering monteras tillsammans med ytter- och innerring till att bilda ett komplett rullager. Pressen var av modell äldre, från någon gång under 70-talet, en tid då man hade en helt annan underhållsfilosofi,  vilket  för med sig att underlag för förebyggande underhåll är bristfällig i sin natur, eller saknas helt. Analysen utfördes i form av en så kallad RCM-analys, en process där man bryter ner maskinen på komponentnivå och genom en FMEA-kategorisering avgör huruvida komponenten är kritisk på någon av punkterna; tillgänglighet, produktivitet, kvalitet, säkerhet, miljö eller ekonomi. Utifrån detta tar man fram åtgärder till de kritiska komponenterna. Tillsammans med punkterna från det första steget bildades en ganska omfattande lista med underhållsåtgärder, vilket innefattade åtgärd, intervall och utförare. Sista steget innan implementering var att sammanställa åtgärdslistan i ett av företaget standardiserat format, vilket innebär att man vill kunna skriva ut åtgärderna tillsammans med bilder för att sätta i pärmar och förvara i kanalen, för lätt åtkomst för kanalens personal. Själva slutresultatet,  tillika underhållsprogrammet, återfinns i bilaga C och D i denna rapport.
46

Reliability-centred maintenance for electric power distribution systems

Bertling, Lina January 2002 (has links)
No description available.
47

Progress towards a total synthesis of (+-)-Longithorone C

Zakarian, Joseph E. January 2007 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal
48

Préparation et caractérisation de nouveaux catalyseurs de métathèse asymétrique

Fournier, Pierre-André January 2007 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal
49

Reliable Centered Maintenance (RCM) Reliable and Risk Centered Maintenance (RRCM) in Offshore Wind Farms (Case Study- Sweden)

Manouchehrabadi, Maryam Kharaji January 2011 (has links)
Wind power, as a source of renewable energy, is growing very fast. Especially so, is consideration given to offshore wind farms where expansion is due in part to limited social and visual impact, reduced noise effect of turbines, and at the same time higher production of offshore wind turbines. Maintenance is always a considerable and costly part of the wind power investment, especially for offshore projects, but it could not improve as fast as the increasing wind industry in the world. The operation and maintenance management of wind farms should have always a reliable and structured planning to have an economical investment. At the beginning of the growth of wind industry, companies tried to transfer responsibilities of the failure and loss of production to the insurance companies, but it cannot be continued any more. These days even the insurance companies ask about regular inspection or condition monitoring. In other words, they ask for a reliable strategy for operation and maintenance. Both preventative and corrective maintenance are used in offshore wind farms. Preventive maintenance is usually performed at the first sign of failure, and in so doing it helps reduce costs associated from lost production. Having a perfect preventive maintenance program is not easy and it usually needs more inspection and online monitoring. To select a suitable strategy, data should be gathered from different stakeholders who are involved in the project. The stakeholders could be turbine designers, construction companies, transportation companies, operation staff, etc. The reason is that each group has the data which could help to define a reliable strategy of maintenance. Reliability includes measurements, e.g., failure rate, repair time, and availability. Reliability is the ability of components or system to perform their function under given operational condition and for a predicted period of time. However always preventive maintenance especially for offshore wind farm is faced with uncertainty due to bad weather, access difficulty, and logistic limitation. Reliability Centered Maintenance (RCM) is a systematic qualitative technique that balances preventive and corrective maintenance. It chooses the right preventive maintenance activities for the right component at the right time to reach the most cost efficient solution. This research points out that RCM, as an experienced methodology in other industries, could be a good method for scheduled preventive maintenance in offshore wind power for purposes of lowering cost while improving reliability and safety. RCM implementation is always facing with uncertainty. Engaged uncertainty to RCM is known as Reliability and Risk Centered Maintenance RRCM and it could lead maintenance process to an optimal preventive schedule with minimum uncertainty.
50

Development of a maintenance plan for the STEPWISE project at Swerea MEFOS

Hassabelnaby, Aly January 2018 (has links)
Process plants come with a wide variety of engineering challenges. Each process has uniqueoperating conditions that require careful operation and maintenance programs to keep the process equipment in a condition that is safe for operation. A pilot-scale plant was built in Luleå to demonstrate the possibility of carbon dioxide removal from blast furnace gas usingthe Sorption Enhanced Water Gas Shift (SEWGS) technology. One of the challenges facingthe SEWGS pilot plant was the lack of a maintenance plan which was the motivation for this thesis. The aim of this thesis was to create a maintenance plan for the SEWGS pilot plant. Studying the process conditions of the pilot plant was the starting point since an understanding of the unique operating conditions was necessary for creating a maintenance plan for the pilot plant’s equipment. The Reliability-centered maintenance (RCM) method was chosen to create the maintenance plan. The study began with determining the objectives and contents of the analysis. The next step was a functional failure analysis in the form of a Failure Mode and Effect Criticality Analysis (FMECA) covering all the equipment in the plant. Afterwards the failure consequences were assessed based on a criticality assessment matrix to determine which equipment necessitate the performance of maintenance activities. The maintenance plan was created based upon the criticality of the equipment and the selected maintenance activities were based on the recommendations of manufacturers. The failure analysis found that the blast furnace gas compressor is the most critical for the process. The boiler and superheater have been found to be highly critical due to the dangerous safety consequences of their failure. In addition, all pressure safety valves have been found to be highly critical due to the hidden nature of their failure. The maintenance plan addresses these critical items and other less critical items while some non-critical items have been removed from the plan due to the negligible consequences of their failure.

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