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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

Holistic environmental assessment of oil and gas field development

Salter, Edward Robert Edmund January 2000 (has links)
This study has developed a new life-of-field, goal orientated process of analysis called Holistic Environmental Assessment (HEA). HEA assesses the total environmental risk associated with a proposed oil and gas field development. It prioritises environmental risks and identifies cost effective strategies to reduce them. For the first time the process was applied to a real 'case study' field development programme to test its effectiveness. The application identified that it is a useful tool to help design eco-efficient and costeffective oil and gas field developments. Furthermore, it was discovered that much of the information required by HEA could be obtained in a quick and user-friendly format. The new assessment process was developed after a review of the interaction of the offshore oil and gas industry with the environment, and techniques employed to evaluate this interaction. The review identified that the industry interacts with the environment in a number of different ways, and that the level of interaction transgresses the boundaries of sea, air and land locally, regionally and internationally. Legislation and public concern demand no damage to the environment from offshore oil and gas field exploration and development. UK environmental legislation and people's expectations for environmental performance are in a state of change. This change, coupled with the uncertainty over how resilient the environment is to perturbation, and the increasing risk of environmental liability presents a need for operators to clearly manage environmental information and assess total environmental risk. It was discovered that Environmental Assessment, Lifecycle Analysis and Cost Benefit Analysis, when used separately, failed to assess total environmental risk, but when used in combination under the HEA process could. Many organisations, such as the British Medical Association, European Oilfield Speciality Chemicals Association, the Royal Ministry of Petroleum and Energy (Norway) and Shell Expro, now recognise that a holistic approach is essential to assess total environmental risk. The author proposes that HEA would be effective as a software tool to analyse different environmental risk mitigation systems. This would facilitate the identification of a system that steers an operator towards the triple bottom line of Sustainable Development.
2

Studies on 4D printing Thermo-responsive PNIPAM-based materials

Shun, Li 30 April 2021 (has links)
No description available.
3

Dynamic Deformation and Shear Localization in Friction-Stir Processed Al0.3CoCrFeNi and Fe50Mn30Co10Cr10 High-Entropy Alloys

Macdonald, Neil 08 1900 (has links)
High entropy alloys (HEAs) are a relatively new class of solid solution alloys that contain multiple principal elements to take advantage of their high configurational entropy, sluggish diffusion, lattice distortion, and the cocktail effect. In recent development, work hardening mechanisms known as twinning induced plasticity (TWIP) and transformation induced plasticity (TRIP) have been found active in Al0.3CoCrFeNi (molar fraction) and Fe50Mn30Co10Cr10 (at %) HEA compositions. Friction-stir processing was done to increase the mechanical properties and improve the microstructure of the alloys for the purpose of high strain rate performance. Quasi-static tensile tests as well as top-hat geometry Split-Hopkinson pressure bar tests were conducted to view the mechanical properties as well as view the microstructural evolution at dynamic strain rates. Overall, the Al0.3CoCrFeNi condition after friction-stir processing and heat treatment has proved to have the best mechanical properties, and selecting from the conditions in this study, Al0.3CoCrFeNi has better shear localization resistance.
4

Övergå till högre stålhållfasthet / Switch to higher steel strength

Shahin, Firas, Karlsson, Rickard January 2017 (has links)
Detta projekt handlar om en övergång till högre stålhållfasthet. Övergången sker från stålhållfastheten S355 till S690 i HEA-profiler för pelare samt vindbockar. Valet att genomföra detta projekt kommer ifrån att det skulle vara intressant att se om det finns några vinster med att övergå till högre stålhållfasthet. Under projektets gång kunde det konstateras att mindre stålprofiler kunde väljas vid val av S690 istället för den traditionella S355. För just denna specifika stålhall som undersöktes minskades pelarstorleken med tre pelarprofiler. Medan för vindbockarna kunde endast en pelarprofil minskas. Vid användning av stålhållfastheten S690 uppnås tvärsnittklass 4 för ett fåtal HEA-profiler. Detta medför till mer omfattande dimensioneringsutförande jämfört med stålhållfastheten S355 som endast når tvärsnittsklass 3 som högst. Det föreligger för tillfället ett ekonomiskt incitament för att välja högre stålhållfasthet enligt de approximerade kostnadsanalyser som verkställdes under projektets gång. Med den högre stålhållfastheten blir stålmängden lägre för stålhallen. Detta medför mindre transporter till byggarbetsplatsen, vilket är gynnsamt både ur ett miljöperspektiv och ekonomiskt perspektiv. / This project is about a transition to higher steel strength. The transition is from steel strength S355 to S690 in HEA- profiles for column and wind trestles. The choice to do this project comes from the fact that it would be interesting to see if there are any profits in switching to higher steel strength. During the project process it was found that smaller steel profiles could be chosen when S690 was selected instead of the traditional S355. For this particular steel hall the column size was reduced by three column profiles and for the wind trestles only one profile could be reduced. When the steel strength S690 is used, the cross class 4 is obtained for a few HEA- profiles. This leads to more extensive dimensioning performance compared to the steel strength S355 which reaches only the cross class 3 as the highest. At present there is an financial incentive to choose higher steel strength according to the approximate cost analyzes carried out during the project process. With the higher steel strength, the steel amount becomes lower for the steel hall. This leads to less transport to the construction site. Which is beneficial both for an environmental perspective and economic perspective.
5

The Phase composition and microstructure of AlχCoCrFeNiTi alloys for the development of high-entropy alloy systems

Lindner, Thomas, Löbel, Martin, Mehner, Thomas, Dietrich, Dagmar, Lampke, Thomas 26 June 2017 (has links) (PDF)
Alloying aluminum offers the possibility of creating low-density high-entropy alloys (HEAs). Several studies that focus on the system AlCoCrFeNiTi differ in their phase determination. The effect of aluminum on the phase composition and microstructure of the compositionally complex alloy (CCA) system AlxCoCrFeNiTi was studied with variation in aluminum content (molar ratios x = 0.2, 0.8, and 1.5). The chemical composition and elemental segregation was measured for the different domains in the microstructure. The crystal structure was determined using X-ray diffraction (XRD) analysis. To identify the spatial distribution of the phases found with XRD, phase mapping with associated orientation distribution was performed using electron backscatter diffraction. This made it possible to correlate the chemical and structural conditions of the phases. The phase formation strongly depends on the aluminum content. Two different body-centered cubic (bcc) phases were found. Texture analysis proved the presence of a face-centered cubic (fcc) phase for all aluminum amounts. The hard η-(Ni, Co)3Ti phase in the x = 0.2 alloy was detected via metallographic investigation and confirmed via electron backscatter diffraction. Additionally, a centered cluster (cc) with the A12 structure type was detected in the x = 0.2 and 0.8 alloys. The correlation of structural and chemical properties as well as microstructure formation contribute to a better understanding of the alloying effects concerning the aluminum content in CCAs. Especially in the context of current developments in lightweight high-entropy alloys (HEAs), the presented results provide an approach to the development of new alloy systems.
6

Inventory Control of WEEE (Waste of Electronic and Electrical Equipment) Reverse Logistics in parts of China : The HEA (household electrical appliances) manufacturers’ perspective

Changcheng, Yao, Le, Zhang January 2011 (has links)
Title: Inventory Control of WEEE (Waste of Electronic and Electrical Equipment) Reverse Logistics in parts of China  --The HEA (household electrical appliances) manufacturers’ perspective   Background: With economic development, the requirement of public for enterprises and products has become increasingly rational. Price is no longer the only consideration of public, they also pay attention to other factors, such as energy conservation. The manufacturers face enormous challenges because of the late start of products recycling in China. So enterprises start to build their own recycling logistics system in order to have more competitive for themselves.   Purpose: The purpose is to describe the methods of inventory controls in the case HEA manufacturers and the problems of inventory controls, find out what problems exsist in the case manufacturers, then analyze what are the origins of these issues for HEA manufacturers as well as propose how these issues can be alleviated, and what methods would be suitable. By solving these research questions, the thesis tries to offer some suggestions about inventory control improvement not only to the cases, but also wider to the whole HEA manufacturers in China.   Method: Multiple - case study as research method has been applied. Specifically, two case companies, Chinese HEA manufacturers, have been selected. Two telephone focused interviews combined with open-ended interviews have been conducted with two related managers. The empirical evidence has been analyzed by using with-in case study and cross-case analysis method, then model analysis is applied.     Results, conclusion: First, the methods are not good enough in the two case companies, a new model is built to help inventory control in the case companies. Second, from external and internal perspective, the origins to cause the problems are a lot, but the main causes are environmental factors, and in busy seasons of these companies. Besides, for doing reverse logistics is a capital costing job, none of the enterprises would like to step in. and reverse logistics is in an uncertainty environment, doing so need to make sure everything clearly and orderly, or costs will be a large amount. The best way of improving inventory control of WEEE reverse logistics in China is that the enterprises standing together to restore the orders.   Limitations and drawbacks: For one thing, there are not enough previous studies references in China, this brought some difficulties of supporting the view points in the thesis. Two empirical cases are not persuasive enough to represent the whole China due to the limitation of the authors’ knowledge and the huge area of China. Nevertheless, the ideal model in model analysis is not that complicated, which means, for more complex problems and processes, the model would be lame.
7

Expression of wild type and variants of human apolipoprotein A-I in Pichia pastoris / Expression de type sauvage et des variantes de l’Apolipoprotéine A-I humaine chez Pichia pastoris

Janakiraman, Vignesh Narasimhan 11 December 2015 (has links)
Les lipoprotéines de haute densité (High Density Lipoprotein, HDL) permet deréduction de risque de maladies cardio-vasculaires principalement en raison de leurcapacité à éliminer le cholestérol accumulé des artères (via transport inverse ducholestérol). Les effets protecteurs des HDL sont médiés par l'apolipoprotéine AI(ApoA1), qui est le La protéine la plus importante quantitativement du HDL. L’ApoA1favorise l'efflux de cholestérol vers le foie pour l'excrétion. Une augmentation desniveaux plasmatiques de l’ApoA1 est généralement acceptée d'êtrecardioprotecteur, ce qui en fait un potentiel thérapeutique. Deux variantes naturelle(mutants) de l’ApoA1, Milano et Paris, sont caractérisées par une mutationponctuelle unique a permis l'introduction d'un résidu cystéine. Populations avecApoA1-Milano ont été rapportés d'avoir un système cardiovasculaire, même avec defaibles niveaux de plasma de ApoA1 et HDL. Il est donc d'intérêt pour générerrecombinante de type sauvage et des variantes de ApoA1 humaine pour desapplications thérapeutiques potentielles. Dans cette étude, de type sauvagerhApoA1 a été produit chez P. pastoris et purifié par chromatographie en modemixte en une seule étape. Par la suite, un processus intégré a été le développementde la production et la récupération rapide de type sauvage rhApoA1 chez P. pastorispar chromatographie par lit expansée. En outre, les variantes de l'ApoA1, Milano &Paris, ont été générées par mutagenèse dirigée et ont été exprimés chez P. pastoris.Les motifs d’adsorption de rhApoA1-Milano et rhApoA1-Paris ont été comparés àcelle de type sauvage ApoA1 et les différences ont été discutées. / The high-density lipoprotein (HDL) complex helps reduce the risk of cardiovasculardisorders mainly due to its ability to remove accumulated cholesterol from arteriesvia reverse cholesterol transport. These protective effects of HDL are known to bemediated by Apolipoprotein A-I (ApoA1), which is the major protein component ofHDL. ApoA1 is a lipid binding protein and promotes cholesterol efflux fromperipheral tissues to the liver for excretion. An increase in the plasma levels ofApoA1 is generally accepted to be cardioprotective, making it a potentialtherapeutic. Two naturally occuring variants of ApoA1, namely the Milano & Parismutants, are characterised by a single point mutation resulting in the introduction ofa Cysteine residue. Populations with ApoA1-Milano have been reported to have ahealthier cardiovascular system even with low plasma levels of ApoA1/HDL. It ishence of interest to generate recombinant wild type and variants of human ApoA1for potential therapeutic applications. In this study, wild type rhApoA1 was producedin P. pastoris and purified by mixed-mode chromatgraphy in a single step.Subsequently, an integrated process has been development for the production andrapid recovery of wild type rhApoA1 in Pichia pastoris. This has paved way to theestablishment of a scalable integrated process that could be further developed toindustrial levels. In addition, the cysteine variants of ApoA1, Milano & Paris, havebeen generated by site directed mutagenesis and have been successfully expressedin P. pastoris. The binding patterns of rhApoA1-Milano and rhApoA1-Paris have beencompared with that of wild-type ApoA1 and the differences have been discussed.
8

Exploration des facteurs qui influencent la mise en œuvre de la méthode HEA pour la sélection des ménages bénéficiaires des programmes de filets sociaux au Mali.

Dukuze Muziranenge, Marie-Aline Brigitte 09 1900 (has links)
Partout dans le monde, l’identification des personnes ou ménages bénéficiaires d’interventions sociales demeure un défi. Dans les pays où la majorité de la population travaille dans le secteur informel, vit d’une agriculture de subsistance et/ou vit sous le seuil de la pauvreté, le ciblage des personnes devant bénéficier d’une intervention fait appel à des méthodes différentes dont la vérification du revenu et la classification de la pauvreté sur base monétaire. En 2014, un projet-pilote intitulé Cadre commun des filets sociaux au Nord Mali (CCFS) a été mis en place au Mali. L’objectif de ce projet est d’identifier les populations en insécurité alimentaire et nutritionnelle et leur fournir une assistance (transferts monétaires, assistance alimentaire et prévention de la malnutrition pour les femmes enceintes et les enfants), particulièrement en périodes de soudure pastorale et agricole. La méthode de ciblage Household Economy Approach (HEA) est une des méthodes utilisées pour sélectionner les ménages bénéficiaires des transferts monétaires au Nord Mali. L’objectif de cette recherche est d’identifier les facteurs et le contexte qui influencent la mise en œuvre de la méthode HEA. Deux villages dans une commune agricole et deux sites de fraction dans une commune pastorale ont été choisis comme sites. Des entretiens (48 entretiens (12 effectués par l’étudiante et 36 par l’ONG de recherche)) et une collecte de 15 documents ont été réalisés. À l’aide des 23 facteurs du cadre d’analyse de la mise en œuvre de Durlak et Dupré (2008), une analyse thématique a été effectuée à l’aide du logiciel © QDA Miner. Les résultats démontrent que l’identification des ménages bénéficiaires des transferts monétaires au Nord Mali repose essentiellement sur le ciblage géographique et communautaire. Les facteurs qui influencent le processus de ciblage sont liés à la faible connaissance de la méthode HEA, à la lassitude et la faible motivation des personnes impliquées, à la gestion top down et au manque de transparence dans les processus décisionnels au niveau des structures organisationnelles, aux logiques de domination et relations de pouvoir au sein des communautés ainsi qu’aux enjeux liés au financement et aux rapports hégémoniques existants dans le monde de l’aide humanitaire et de l’aide publique au développement. La difficile coordination multisectorielle des acteurs de la protection sociale vient appuyer le besoin en recherches nouvelles sur la mise en place du régime social unifié (RSU) au Mali. / Around the world, the identification of people or households benefiting from social interventions remains a challenge. In countries where the majority of the population works in the informal sector, lives on subsistence agriculture and/or lives below the poverty line, targeting people who have to benefit from an intervention requires methods that are different from income verification and from the classification of poverty on a monetary basis. In 2014, an experimental project entitled Cadre commun des filets sociaux au Nord Mali (CCFS) was implemented in Mali. The objective of this project is to identify the populations who suffer from food and nutritional insecurity and provide them with assistance (cash transfers, food assistance and prevention of malnutrition for pregnant women and children), particularly during pastoral and agricultural lean periods. The Household Economy Approach (HEA) targeting method is one of the methods used to select beneficiary households for cash transfers in Northern Mali. The purpose of this research is to identify the factors and the context that influence the implementation of the HEA method. Two villages in an agricultural commune and two fractional sites in a pastoral commune were chosen as sites. Interviews (48 interviews (12 carried out by the student and 36 by research NGOs)) and a collection of 15 documents were conducted. Using the 23 factors in the Durlak and Dupré Implementation Analysis Framework (2008), a thematic analysis was conducted using the software © QDA Miner. The results show that the identification of households receiving cash transfers in Northern Mali is mainly based on geographical and community targeting. The factors that influence the targeting process are related to the low knowledge of the HEA method, to the weariness and low motivation of the people involved, to top down management and lack of transparency in the decision-making processes at the level of organizational structures, to the logic of domination and power relations within communities, and finally to the issues of funding and hegemonic relationships in the world of humanitarian aid and development cooperation. The difficult multisectoral coordination of social protection actors comes to support the need for new research on the establishment of a household registration system in Mali.
9

The Phase composition and microstructure of AlχCoCrFeNiTi alloys for the development of high-entropy alloy systems

Lindner, Thomas, Löbel, Martin, Mehner, Thomas, Dietrich, Dagmar, Lampke, Thomas 26 June 2017 (has links)
Alloying aluminum offers the possibility of creating low-density high-entropy alloys (HEAs). Several studies that focus on the system AlCoCrFeNiTi differ in their phase determination. The effect of aluminum on the phase composition and microstructure of the compositionally complex alloy (CCA) system AlxCoCrFeNiTi was studied with variation in aluminum content (molar ratios x = 0.2, 0.8, and 1.5). The chemical composition and elemental segregation was measured for the different domains in the microstructure. The crystal structure was determined using X-ray diffraction (XRD) analysis. To identify the spatial distribution of the phases found with XRD, phase mapping with associated orientation distribution was performed using electron backscatter diffraction. This made it possible to correlate the chemical and structural conditions of the phases. The phase formation strongly depends on the aluminum content. Two different body-centered cubic (bcc) phases were found. Texture analysis proved the presence of a face-centered cubic (fcc) phase for all aluminum amounts. The hard η-(Ni, Co)3Ti phase in the x = 0.2 alloy was detected via metallographic investigation and confirmed via electron backscatter diffraction. Additionally, a centered cluster (cc) with the A12 structure type was detected in the x = 0.2 and 0.8 alloys. The correlation of structural and chemical properties as well as microstructure formation contribute to a better understanding of the alloying effects concerning the aluminum content in CCAs. Especially in the context of current developments in lightweight high-entropy alloys (HEAs), the presented results provide an approach to the development of new alloy systems.
10

Einfluss der Struktur und Herstellungsroute auf das tribologische Verhalten thermisch gespritzter Hochentropielegierungen

Löbel, Martin 28 April 2021 (has links)
Hochentropielegierungen stellen einen neuen Entwicklungsansatz metallischer Werkstoffe ohne ein eigenschaftsbestimmendes Hauptelement dar. Die zielgerichtete Übertragung der bisher überwiegend an Massivwerkstoffen ermittelten Eigenschaften in die Beschichtungstechnik erfordert die Kenntnis der bestimmenden Einflussfaktoren. Für die Schichtherstellung werden die Verfahren des thermischen Spritzens betrachtet. Hierfür wird eine geeignete Prozessroute ermittelt. Die detaillierten Untersuchungen zu den Prozess-Struktur-Eigenschaftsbeziehungen erfolgen an Legierungen mit variabler Struktur. Diese werden anhand von thermodynamischen Parametern sowie Untersuchungen an schmelzmetallurgisch hergestellten Massivwerkstoffen ausgewählt. Zur Bewertung des Einflusses der Größe der Strukturmerkmale, der Heterogenität und möglicher Ungleichgewichtszustände werden schmelz- und pulvermetallurgisch hergestellte Massivwerkstoffe als Referenz betrachtet. Die geplanten Forschungsarbeiten tragen zu einem Verständnis der Prozess-Struktur-Eigenschaftsbeziehung von Hochentropielegierungen bei. Weiterhin wird eine geeignete Prozessroute für die pulvermetallurgische Verarbeitung sowie für Anwendungen in der Oberflächentechnik ermittelt.

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