• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 880
  • 716
  • 199
  • 121
  • 108
  • 96
  • 64
  • 41
  • 19
  • 19
  • 16
  • 10
  • 6
  • 6
  • 6
  • Tagged with
  • 2644
  • 909
  • 582
  • 360
  • 299
  • 293
  • 262
  • 240
  • 182
  • 166
  • 155
  • 152
  • 145
  • 141
  • 133
  • 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.
181

Att återvinna ett fartyg : En undersökning av en miljövänlig fartygsåtervinningsindustri

Rosenberg Holma, Milka January 2014 (has links)
Syftet med förelagda undersökning var att karlägga de krav som ställs vid återvinning av han-delsfartyg i de nya regelverk som antagits av IMO och EU med målet att åstadkomma en miljövänlig fartygsåtervinningsindustri. Fokus har legat på de krav som de aktuella regel-verken ställer på fartygsägare och fartygsåtervinningsanläggningar, främst beträffande hantering och bortskaffning av de miljöfarliga material som finns ombord på fartyg. Med dessa krav som utgångspunkt har det redogjorts för hur ett återvinningsförfarande organiseras för att uppfylla de miljökrav som regelverken ställer. Resultatet av undersökningen pekar på att det med dagens teknik och kunskap i allra högsta grad är möjligt att åstadkomma miljövänlig återvinning av handelsfartyg. De problem och utmaningar som resultatet pekar på ligger på ett annat plan än det rent praktiska, bland annat lyfts den långsamma process som implementering av regelverk är fram som en utmaning för fartygsåtervinningsindustrin. Slutdiskussionen handlar till största delen om implementering av lagstiftningen, men också om hanteringen av fartyget och de material som finns ombord, samt om definitionsfrågor rörande ägendeskap. Vidare diskuteras rollen för andra aktörer inom sjöfartsnäringen och de åtgärder som dessa skulle kunna vidta för att åstadkomma en miljövänlig fartygsåtervinning innan de aktuella regelverken träder i kraft och blir bindande. Avslutningsvis ges förslag på fortsatt forskning som handlar om den problematik som diskuterats, men också om de aspekter som inte rymdes inom ramen för denna undersökning. / The purpose of this thesis was to outline the legal requirements set by the IMO and EU in order to establish an environmentally sound ship recycling industry. The emphasis has mainly been on the two large parties involved in the industry; the ship owner and the ship recycling facility. The requirements for these two parties are mainly focused on the handling and disposal of hazardous materials found onboard end-of-life ships. With an analysis of these requirements as a starting point, a ship recycling scenario has been analyzed and discussed. The result shows that, with today’s technology and knowledge it is possible to establish an environmentally sound ship recycling industry. Though, there are some obstacles along the way, which are of a more administrative nature. Amongst these, the first and most important one is the implementation of the regulations in order to set a worldwide standard for environmentally sound ship recycling. The conclusion of this thesis is divided into two parts: one part where the results of the findings is summarized and one part where the different requirements are discussed. The main focus in the discussion is the future for an environmentally sound ship recycling industry and what needs to be done during the existing gap before the legal requirements enter into force. Finally some examples for future research are given. These are mainly questions that were raised during the discussion, but also some of the aspects that were excluded from this thesis.
182

Standards in sustainable engineering and design

Plant, Alexander Victor Charles January 2012 (has links)
The financial and environmental costs associated with the manufacture and consumption of products may be reduced through design for efficient production, service life extension and post-consumer value recovery. In response to today’s need to design with consideration for the whole product life cycle, British Standards Institution (BSI) published BS 8887-1 (2006) Design for Manufacture, Assembly, Disassembly and End-of-life processing (MADE). Original research into the distribution and use of this first part of the MADE series is reported in this thesis. The organizations that accessed BS 8887-1 were categorised using their Standard Industrial Classification (SIC) code. The results are presented graphically in multilevel charts using the hierarchical structure of the SIC system. The study found that the majority of standards users that purchased or downloaded BS 8887-1 were companies in the manufacturing sector and particularly electronics producers. Educational institutions also showed high levels of interest in the standard. For the first time, the use of BS 8887-1 in practice has been investigated. The purpose was to discover if, why and how it is being used and to identify examples of its application in design practice. This was accomplished through semi-structured interviews with design practitioners from both industry and academia, thus helping to explain the results of the earlier SIC study. The information gathered through the interviews shows how BS 8887-1 has informed the design process and how it has been used in combination with various design and management techniques e.g. Advanced Product Quality Planning (APQP). These studies suggest that demand for the standard has been stimulated by the introduction of Extended Producer Responsibility (EPR) legislation, especially the Waste Electrical and Electronic Equipment (WEEE) directive. Importantly, the use of BS 8887-1 has been found to be helpful in winning new business and reducing the costs associated with manufacture, product maintenance and waste management. Based on the result of the qualitative research, a new model of the use of standards in the New Product Development (NPD) process is presented. The research was proposed by the Chairman of the BSI technical committee responsible for the BS 8887 series. The beneficiaries are BSI, industry and academia, since the investigation has shown BS 8887-1 to be of value, and has informed the continuing development of this series of standards. The thesis concludes by arguing for BS 8887 to become the basis of an International Organization for Standardization (ISO) standard in order to reach a wider audience. It also identifies a need for the standard’s design requirements to be supported with additional supplementary interpretation expanding on, and adding detail to, the information in the standard itself. Influenced by this research, at the time of writing a new BSI working group was being formed to consider developing BS 8887 as an ISO standard. BSI had also begun the process of commissioning a handbook to assist designers in the practical application of BS 8887 in industrial design.
183

Scotland's rubbish : domestic recycling, policy and practice in everyday life

Stewart, Fraser Andrew January 2011 (has links)
This thesis examines the relationships people have with rubbish in everyday life. Focusing on domestic recycling policy and practice, environmental concern and action is explored as a sociological problem in a way that moves beyond the individualising paradigms that dominate environmental discourse for behavioural change. In its place, this thesis argues that better explanation may reside in the social context of embedded practices, and how they get enacted in daily life. Beginning with a historical overview and evaluation of current policy, this thesis re-imagines domestic recycling as a complex socio-technical system involving the engagement of different actors. Conducted at the boundaries of sociology, this thesis draws on empirical and theoretical ideas that extend across disciplines. Methodologically the research has been grounded on a principle of mixed methods pragmatism, exploiting the Sequential Explanatory mixed methods research design. Conducted across two phases, Phase One involved the secondary analysis of the Scottish Household Survey and Phase Two the collection and analysis of qualitative data using the Diary- Interview method. The first phase was a macro- analysis of recycling practices in Scotland. The main results of this analysis are presented in Chapter 4, which built a Binary Logistic Regression model, using the Scottish Household Survey, to predict the characteristics of Scottish households likely to engage in recycling behaviour. In addition to identifying the social and structural dimensions of recycling in Scotland, this analysis also enabled a research site to be selected for Phase Two of the study. Chapters 5 and 6 respond to the macro- analysis by accounting for the micro- aspects of recycling practices by looking at the problem inductively. Using qualitative data analysed in Phase Two, these two chapters are based on the idea that how people value the environment is relevant for understanding contemporary recycling practices. Chapter 5 considers the explanatory usefulness of environmental ethics, values and citizenship for explaining why some households engage in environmental behaviour, but others do not. In Chapter 6 these arguments are developed further with a more detailed discussion about how household recycling practices get enacted in everyday life. Using evidence from the data, this chapter considers why commitment to ‘doing’ recycling varies between people and examines recycling as formed, cultivated and maintained habitual behaviour. Taken together the three data chapters try to show that, rather than be an inconsequential feature of normal domestic life, recycling is a practice deeply-rooted in wider social patterns and structural forces. In the final chapter, all of the micro- and macro- findings are integrated together and concluded, along with some reflections on the multidimensionality of contemporary recycling practices in the home, and what this might mean for policy and future research.
184

Mechanical recycling of automotive composites for use as reinforcement in thermoset composites

Palmer, James Alexander Thomas January 2009 (has links)
The aim of this research was to investigate the potential use of recycled glass fibre composite materials as a replacement for virgin reinforcing materials in new thermoset composites. Specifically the closed-loop mechanical recycling of composites used heavily in the automotive sector known as dough and sheet moulding composites, DMC and SMC respectively, are investigated. The recycling of glass reinforced thermoset polymer composite materials has been an area of investigation for many years and composites used in the automotive industry are of particular interest due to legislative and social pressures on the industry. The mechanical recycling process and then collection of useful fibrous grades of recycled materials, recyclate, by a novel air separation technique were investigated first. The properties of these recyclate fibres were characterised and compared directly with the properties of virgin glass fibres they were to be used to replace. Single fibre tensile tests were employed to compare the strengths of the fibres and single fibre pull-out tests were used to investigate the strength of the interface between the fibres and a polyester matrix. These tests showed the recyclate fibres to be weaker and have a poorer interface with the polyester matrix than the virgin glass fibres. Understanding the properties of the recyclate materials meant their reformulation into new composites could be carefully considered for the production of new high performance materials. Two grades of the collected recyclate materials were then reformulated in to new DMC and SMC composites, replacing percentages of the virgin glass fibre reinforcement. The mechanical properties of the resulting manufactured composites were characterised throughout for direct comparison against one another and an unmodified control material, using both three-point flexural tests and Charpy impact tests. Through the modification of existing manufacturing techniques and the development of novel production equipment it has been possible to successfully manufacture both DMC and SMC composites with the recyclate materials used to replace virgin glass fibres. Virgin glass fibres have successfully been replaced by recyclate materials without disrupting standard production techniques and with minimal reduction of the mechanical properties of the resulting composites. As the loadings of recyclate materials used were greatly increased both the flexural and impact strengths were significantly degraded and it was found that chemical modification of the composite could be used to improve these formulations. It has been shown that the recyclate materials should be considered and treated as a distinct reinforcing ingredient, separately from the remaining virgin glass fibres.
185

Recycling as play: encouraging recycling through a participatory design process with children

Santoro, Amanda January 1900 (has links)
Master of Landscape Architecture / Landscape Architecture/Regional and Community Planning / Jason S. Brody / Recycling in many cities faces dilemmas with accessibility and education, especially within the public realm, which leads to a lack of participation in this sustainable activity. The City of Kansas City, Missouri does not currently provide recycling solutions for multi-family and commercial businesses and has minimal to non-existent recycling infrastructure within its downtown’s public realm. Envisioning a new recycling system for a city requires many entities to come together in the design process. However, the city, landscape architects, and other designers frequently overlook incorporating children into the participatory community design process, even though children have knowledge, experiences, and ideas to offer (Speak, 2000). Incorporating many avenues of community input can benefit the design outcomes, and children should be included in the participatory design process when it engages their built environment. The Kansas City Design Center (KCDC) produced a vision plan and conceptual site designs for downtown Kansas City’s recycling system. Community input was part of the KCDC studio project’s design process by utilizing a series of advisory council meetings, professional reviews, and open houses. This report integrated another form of community involvement into the project by working with children on designing urban space and playful infrastructure focused on encouraging participation in recycling. A series of design charrettes were conducted with 5th grade students from Kansas City’s urban charter school Crossroads Academy due to the school’s focus on immersion in the urban environment. The students’ design charrette ideas added a new perspective to how urban space and recycling infrastructure could encourage participation. These ideas and perspectives were shared with classmates and utilized to further design development in the recycling project's streetscape "Links" strategy. As the project developed, the researcher observed how the children's ideas impacted the "Links" strategy design coming through in playful ground plane designs, interactive elements, concepts of place-making, and considerations for a variety of users. The participatory process with the children was most influential on those involved directly with the children's process. This allowed the children's ideas to become inherent base knowledge when designing. Engaging youth’s imaginative minds in the design process for urban space and recycling infrastructure sparked new playful perspectives on how to encourage participation and led to meaningful recycling design outcomes within the public realm.
186

Building spaces & communities: the process of improving Kansas City's recycling system with community input

Heermann, Lauren January 1900 (has links)
Master of Landscape Architecture / Landscape Architecture/Regional and Community Planning / Jason S. Brody / Kansas City has the opportunity to expand its recycling programs and infrastructure through a participatory design process conducted at the Kansas City Design Center (KCDC). Because participatory design techniques can allow researchers to include members of the community in the planning process, project outcomes can generally be more successful. In the example of the recycling and composting project led by students at the KCDC, an advisory committee made of professionals and members of the community represented many stakeholder interests. Because of the wide array of feedback from the community, the process of design for the studio was not linear, but rather, it transformed over a period of research, design, further research, and redesign. The students first approached local recycling issues within the scope of a document written for grant funding. However as students responded to feedback from the advisory committee, the final proposals were altered to better address truer community needs. Other aspects for how to communicate and respond to critical feedback was also realized. This report aims to discover how participatory design aided this project and made its outcomes and delivery more agreeable to the larger population.
187

Avaliação do comportamento de pavimentos com camada reciclada de revestimentos asfálticos a frio com emulsão modificada por polímero. / Mechanical behavior and performance of cold recycled asphalt mixtures produced with polymer modified emulsion.

Silva, Amanda Helena Marcandali da 18 April 2011 (has links)
Esta pesquisa avaliou a técnica de reciclagem a frio in situ com emulsão modificada por polímero de revestimentos asfálticos deteriorados, por meio de análises dos resultados de ensaios laboratoriais e avaliações de trecho experimental executado na Rodovia Régis Bittencourt, atualmente sob concessão do Grupo OHL Brasil. Os ensaios laboratoriais foram conduzidos a fim de se verificar a influência da variabilidade dos agregados fresados, e o efeito do teor e do tipo de emulsão asfáltica (modificada por polímero e convencional) na dosagem de misturas recicladas a frio, utilizando resultados de comportamento mecânico como parâmetros de avaliação. Os ensaios de laboratório mostraram a eficiência das emulsões modificadas por polímero sobre as convencionais e a importância do período de cura nas propriedades mecânicas. Valores de módulo de resiliência determinados em laboratório ficaram próximos aos módulos das camadas em campo obtidos por retroanálise estrutural, oscilando entre 1.000 a 1.500 MPa. A concepção do experimento de campo permitiu variar a espessura da camada reciclada (80, 110 e 150 mm) e o tipo de revestimento asfáltico sobre esta, (microrrevestimento asfáltico a frio e concreto asfáltico com 40 mm de espessura), resultando em seis segmentos analisados. O acompanhamento da execução contribuiu para compreender as vantagens e limitações do grupo de equipamentos utilizados em campo para a reciclagem. O monitoramento dos segmentos experimentais permitiu verificar que a solução de reciclagem asfáltica in situ traz uma melhoria para a condição estrutural e funcional dos pavimentos. As deflexões são reduzidas pela reciclagem a frio e as bacias de deflexão mostram um aumento no raio de curvatura, ressaltando a melhoria estrutural decorrente da reciclagem. O estudo de campo, que incluiu o acompanhamento por mais de 2 anos de vida em serviço permitiram concluir que a reciclagem asfáltica a frio de revestimentos deteriorados pode ser empregada para tráfego pesado, podendo ser executada em diferentes espessuras, variando de acordo com o estado da camada deteriorada e das deflexões da estrutura remanescente antes da reciclagem. O microrrevestimento asfáltico a frio pode ser executado sobre a camada reciclada asfáltica, sendo eficiente por tempo limitado, dependendo das deflexões obtidas após restauração; após certo período deve ser executada uma camada de concreto asfáltico como reforço. As observações de pista mostraram que a drenagem adequada dos pavimentos é uma característica fundamental para o bom desempenho da solução de reciclagem a frio. / This research evaluated in situ cold recycling with emulsion modified by deteriorated asphaltic coating polymer, by analyzing the lab tests results and evaluating Rodovia Régis Bittencourts experimental stretch, currently under Grupo OHL Brasils concession. The lab tests were conducted in order to verify the milled aggregates variety and the effect of the asphaltic emulsions (modified by polymer or conventional) content and type on the cold recycled mixtures dosage, utilizing mechanical behavior results as evaluation parameters. The lab tests show the polymer modified emulsions efficiency over the conventional and the importance of the healing period for the mechanical properties. Lab determined resilience module values were close to the field modules acquired via structural back-analysis, oscillating between 1,000 to 1,500 MPa. The field experiments conception permitted variation of recycled layer thickness (80, 110, and 150 mm) and its type of asphaltic coating (cold asphaltic micro-coating and 40 mm thick asphaltic concrete), resulting in six analyzed segments. The monitoring of the execution contributed to the comprehension of the advantages and limitations of the equipment used for recycling in the field. In monitoring the experimental stretches, there was positive verification that the in situ asphaltic recycling solution brought about better structural and functional condition to the pavements. Deflections were reduced by the cold recycling, and the deflection basins show an increase in curvature radius, thus enhancing structural improvements due to recycling. The field study, that includes monitoring for over 2 years of service life, conclude that the cold asphaltic recycling of deteriorated coatings can be used for heavy traffic, being executable in different thicknesses, varying according to the deteriorated layers state and remnant structure deflections prior to recycling. The cold asphaltic micro-coating can be executed over the asphaltic recycled layer, with limited time efficiency, depending on the acquired deflection after restoration; after a determined period of time, an asphaltic concrete layer must be executed for strengthening. Track observations show that the pavements adequate drainage is a fundamental characteristic for the cold recycling solutions performance.
188

Rejuvenation of Reclaimed Asphalt Pavement (RAP) in Hot Mix Asphalt Recycling with High RAP Content

O'Sullivan, Karen A. 26 April 2011 (has links)
This study aims to understand intermingling process between rejuvenators and aged asphalt binders in reclaimed asphalt pavement (RAP) materials during RAP recycling operations in pavement construction. This study presents results of a laboratory study on the use of rejuvenators to recycle age hardened asphalt binders in RAP. Laboratory Hot Mix Asphalt (HMA) samples were prepared with RAP millings from one specific pavement and a commercial rejuvenator, with 80 to 90 percent RAP content. The following mixes with various amount of the rejuvenator were evaluated: a control mix prepared from burned RAP aggregate and virgin asphalt binder, another control mix prepared with heated RAP, a recycled RAP mix with 1% rejuvenator (at the weight of the total mix), a recycled RAP mix with 0.5% rejuvenator, and a recycled RAP mix with 0.5% rejuvenator and 0.5% virgin asphalt binder. Dynamic modulus test results of laboratory prepared samples were obtained for a range of temperatures over an eleven-week period of accelerated aging at 60ºC in an inert gas oven and a conventional convection oven. Accelerated aging protocol was used to evaluate the intermingling process associated with diffusion mechanism between the rejuvenator and aged asphalt binder while an argon inert gas oven provides an environment where oxidation-related ageing and hardening in rejuvenated asphalt binders can be eliminated. The dynamic modulus data of six distinct mixes were statistically analyzed and compared to the results reported in the literature for virgin and low percentage recycled mixes. Collected data suggest that the use of rejuvenator is a viable option for recycling HMA with high RAP material content.
189

The effect of pretreatments on the rate of enzymatic hydrolysis of wheat straw and its structural features

Gharpuray, Mahendra M. January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
190

Microstructure characterization and corrosion properties of two recycled aluminium alloys AA5050 and AA6011

Jordan, Aaron January 2017 (has links)
The influence of recycling on aluminium alloys and subsequent influence on the microstructure and corrosion performances have been investigated. The investigation was commenced by taking two block cast, recycled aluminium alloys (AA5050 and AA6011) and rolling them into 1mm gauge plate. In the case of AA6011, the plate was subjected to subsequent solution heat treatment and artificial aging steps, in order to attain certain temper specifications. To replicate the automotive paint bake industrial practice, a sample was subjected to a 2% tensile stretch followed by heat treatment for 30 minutes at 180˚C. Microstructural observations revealed Al-Fe-Mn-Si intermetallics to be the dominant secondary phase in both alloys. The size, distribution and composition of these were unaffected by artificial aging. Mg2Si was found in a coarse, localised form in both alloys also, albeit in much less amounts in AA5050. The presence of this phase was likely due to poor homogenisation during thermomechanical processing. HR-TEM of AA6011 revealed needle/rod shaped precipitates, aligning in the [001]Al lattice direction. This is consistent with β''/β' hardening precipitates consisting of magnesium and silicon. Circumstantial evidence was found for the copper-containing Q phase precipitate also. An additional, unidentified precipitate was observed, nucleating on the {111} habit plane of the aluminium matrix. The high iron content of AA6011 retarded the precipitation hardening response by capturing elements associated with hardening precipitates in the Al-Fe-Mn-Si intermetallics. Electrochemical corrosion experiments revealed the materials had a high susceptibility to localised corrosions, with the open circuit potential and breakdown potential possessing similar values. Atmospheric corrosion experiments showed that artificial aging had a large influence on the preferred corrosion mechanism. Non-heat treated samples showed susceptibility for pitting corrosion. This was particularly true for the -T4P temper, which showed large scale pitting. Heat treated samples saw an introduced susceptibility to intergranular corrosion. This was attributed to precipitation at grain boundaries, which would then form a microgalvanic couple with adjacent depleted zones. In the case of the -T8P temper, tensile stretching introduced defects into the sub-grain microstructure. This resulted in intergranular corrosion fronts of increased width, where grains with higher stored energy undergo preferential dissolution alongside the grain boundary attack. Overall, the detrimental effects of high iron content need to be overcome before AA5050 and AA6011 can be seriously considered for use in the automotive industry. However, the corrosion performance of AA6011-T8P is encouraging.

Page generated in 0.0787 seconds