• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 656
  • 549
  • 144
  • 42
  • 23
  • 22
  • 18
  • 14
  • 12
  • 9
  • 6
  • 5
  • 5
  • 4
  • 4
  • Tagged with
  • 1704
  • 1704
  • 534
  • 511
  • 510
  • 499
  • 249
  • 165
  • 161
  • 148
  • 148
  • 145
  • 133
  • 122
  • 120
  • 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.
1061

Relationship Between Budget and Project Success Factors in the Ghanaian Building Construction Sector

Aggor, Kenneth Kwame 01 January 2017 (has links)
In developing countries, 60% of project management professionals appear to lack knowledge that timely completion, budget fidelity, and high quality are critical success factors for completion of construction initiatives. Based on the theories of iron triangle, accident causation, scientific management, and strategic management, the purpose of this correlational study was to examine the relationship between project budget and the independent variables of time, quality, safety, environmental impact, and site disputes in the Greater Accra Region of Ghana. One hundred and sixteen project managers, randomly selected from the population of construction professionals in the Greater Accra Region of Ghana, completed the survey entitled the Six Key Performance Indicators developed by Ngacho and Das (2014). The results of the multiple linear regression analysis indicated a weak positive correlation exists between the independent variables (time, quality, safety, environmental impact, and site disputes) and project budget, F(1, 114) = 37.08, p < 0.001. Time recorded the highest beta (β = .50) followed by site dispute (β = .29), environment (β = .22), quality (β = .06), and safety (β = .04). Attention to key performance indicators associated with time, dispute, and environmental impact could improve project outcomes in the Ghanaian construction sector. The study findings could be useful to improve the quality of projects and may benefit the lives of professionals and community members in the area.
1062

Carbon nanotube synthesis and detection : limiting the environmental impact of novel technologies / Limiting the environmental impact of novel technologies

Plata, Desirée L January 2009 (has links)
Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering; and the Woods Hole Oceanographic Institution), 2009. / Includes bibliographical references. / Driven by commercial promise, the carbon nanotube (CNT) industry is growing rapidly, yet little is known about the potential environmental impacts of these novel materials. In particular, there are no methods to detect CNTs in environmental matrices (e.g.,sediment) and thus, there is no way to study their transport or gauge ecological exposure. Thermal methods were developed to quantify CNTs in coastal sediments down to 10 ug per sample, which is sufficient to for CNTs in laboratory air, but not sufficient to measure contemporary levels of CNTs in the environment (which were estimated to be present at pg g' sediment levels using a dynamic mass balance model). In addition to the CNTs themselves, potential impacts of CNT production were assessed by monitoring emissions from a representative synthesis. An ethene-fed chemical vapor deposition process generated several compounds of environmental concern, including the greenhouse gas, methane, the hazardous pollutants, benzene and 1,3-butadiene, and toxic polycyclic aromatic hydrocarbons. By identifying critical CNT precursors (alkynes), I delivered these compounds without thermal pre-treatment and achieved rapid CNT growth. This approach reduced carbonaceous emissions by more than an order of magnitude, and lowered initial feedstock requirements and energetic demands by at least 20%, without sacrificing CNT yield. / by Desirée L. Plata. / Ph.D.
1063

Eco-design of Emerging Photovoltaic (PV) Cells

Celik, Ilke January 2018 (has links)
No description available.
1064

Stakeholder perceptions of public participation in development projects: a case study of the social impacts of the Mooi Mgeni Transfer Scheme Phase II

Markowitz, Chelsea January 2016 (has links)
Thesis (M.A.(Development Studies))--University of the Witwatersrand, Faculty of Humanities, School of Social Sciences, 2016. / Public participation has become an integral component of development projects, and is encouraged in the South African constitution as well as national laws governing the development and management of the environment. Especially in large infrastructure projects such as dams and water transfer systems, community participation is essential, as these projects leave great social and environmental footprints, with the benefits often accruing far beyond the immediately affected areas. Yet, there is little consensus on how this participation should manifest or what it should hope to achieve. This study sought to examine public participation processes through a case study of a dam and pipeline project, the Mooi Mgeni Transfer Scheme Phase II, particularly in terms of its social impacts. The study draws from the perspectives of all stakeholders involved, namely the various project authorities (government architects, implementing company, engineers, construction contractors), the interested and affected community members, and the independent authorities hired to monitor different aspects of the project. This study found that differing views of participation among these different actors greatly affected the participation that manifested in the project. While project authorities’ primary focus for participation was as a means to achieve project goals, community members expected that participation directly benefit them, whether through mitigating impacts or maximising benefits. These differences are complicated by conflicting conceptions of participation in South African legislation, and scant conflict management mechanisms. These conflicting views of participation led to conflict in participatory spaces, and resistance against the project. This study examines five participatory spaces, namely Environmental Impact Assessment public participation meetings, Environmental Monitoring Committee meetings, the engagement with marginalised communities, the engagement with expropriated landowners, and the engagement with relocated informal farm workers. The analysis illuminates the way that power manifests in participatory spaces and can work for or against community goals, and also the effectiveness of different community strategies to leverage their interests. It finds that trust between project authorities and community members is often lacking, but can significantly reduce conflict when it is present. When conflict does arise, if community members are able to upset the project from proceeding, they can make significant inroads in achieving their interests. However, marginalised contingents of the community are faced with ingrained disempowerment in participatory spaces which is difficult to overcome / GR2017
1065

Environmental Impact of Concrete Structures - with Focus on Durability and Resource Efficiency

Al-Ayish, Nadia January 2017 (has links)
Concrete is essential for the construction industry with characteristic properties that make it irreplaceable in some aspects. However, due to the large volumes consumed and the energy intense cement clinker production it also has a notable climate impact. In order to reach the international and national sustainability goals it is therefore important to reduce the climate impact of concrete structures. There are many ways to influence the environmental impact of concrete and a detailed analysis is one of the actions that could push the industry and the society towards a sustainable development. The purpose of this research is to evaluate the environmental impact of concrete structures and the built environment and to highlight the possibilities to reduce that impact with choice of concrete mix and innovative design solutions. A life cycle assessment (LCA) was carried out to analyze the environmental impact of two thin façade solutions with innovative materials and to evaluate influences of different greenhouse gas reducing measures on concrete bridges. The influence of supplementary cementitious materials (SCM) in terms of climate impact and durability was also analyzed. The results indicate that SCMs have a twofold effect on the climate impact of reinforced concrete structures. Not only do they reduce the greenhouse gases through cement clinker replacement but also by an improvement of durability regarding chloride ingress. Currently, this is not considered in the regulations, which makes it difficult to foresee in LCA at early design stages. The results also show great possibilities to reduce the climate impact through different measures and design alternatives and the need for further development of products and solutions. / <p>QC 20171002</p>
1066

Structural strengthening and sustainability improvements of existing buildings – A case study

Niknafs, Pardis January 2022 (has links)
In Sweden, a large share of residential buildings was built more than 50 years ago. Consequently, old materials, poor maintenance, and corrosion can affect the structural performance of these buildings. Additionally, these buildings do not meet the latest energy efficiency and Eurocode regulations. Building retrofits can improve structural strength and resident safety, as well as the energy efficiency of the buildings. Common retrofitting methods are unsustainable in terms of costs, duration, and disruptions to resident’s lives. A sustainable method for structural and energy upgrades is needed in order to retrofit such kind of structures in an efficient way. This master thesis aims to identify an innovative structural and energy retrofitting solution for reinforced concrete buildings that are reaching the end of their service life as well as to provide an environmental impact assessment of this whole process. A multi-family building built in 1972 in Ronneby, Sweden, with reinforced concrete load-bearing walls and slabs was considered as a case study. An integrated retrofitting strategy based on an addition of cross-laminated timber (CLT) panels, insulation, and claddings to the external walls to increase the horizontal load-bearing capacity and energy efficiency of the building was applied in this study. Steel tubes and fiber-reinforced polymers (FRP) are used to increase the load-bearing capacity of the internal load-bearing walls and slab compared to the original ones, mostly for vertical loads. For the structural analysis based on the Eurocode regulations, the software RFEM was used to model and analyze the building before and after retrofitting. In addition to that, dynamic thermal simulation was performed with VIP-Energy software to analyze the service life energy consumption before and after retrofitting of the building. Life cycle assessment following the European standard SS-EN 15978 was used to assess the environmental impacts including global warming potential (GWP), acidification potential (AP), and eutrophication potential (EP). The environmental impact of the existing building was compared with the retrofitted case, during a 50-year service life. The results show that after the retrofitting in the load-bearing walls, the internal shear forces induced by wind loads decreased by 38%. Also, the load-bearing capacity of the slabs was increased by 350% in the critical areas. Regarding GWP, AP and EP all decreased by 30% in the retrofitted case. The results indicate that by retrofitting the building, structural performance and safety increase, and moreover the environmental impact of the building is minimized.
1067

HUR PÅVERKAS MILJÖN NÄR ICKE FÖRNYBARA BYGGMATERIAL ERSÄTTS MED FÖRNYBARA? - GÖR DET NÅGON SKILLNAD? / HOW IS THE ENVIRONMENT AFFECTED BY CHANGING NON RENEWABLE TO RENEWABLE BUILDING MATERIAL? - Does it make any difference?

Pettersson, Anna, Dolmaya, Milad January 2022 (has links)
According to Boverket - The Swedish National Board of Housing, Building and Planning, 21 percent of greenhouse emissions are caused by the Swedish building industry. To make a change the building industry should focus more on sustainable building. The main cause of greenhouse emissions within the construction sector is caused by extracting the raw materials, transport, and manufacturing of material. To build sustainably, nonrenewable materials can be changed to renewable materials to reduce greenhouse emissions. An example is to change plastic with windproof board. Wood is a good example of a renewable material.  In this study, the house Astrid, which is a turnkey house from Älvsbyhus, was analysed. The house Astrid has a living area of 107 m2 including three rooms and a kitchen. The purpose is to get a wooden house which is equivalent to the house Astrid when it comes to energy performance, but with a lower greenhouse emission by changing nonrenewable material to wood products. The method used was to firstly inventory the house Astrid and to be able to see which materials that could be changed. Through research and gathering information, alternative material and other relevant facts were found. Then the average heat transfer coefficient - Um was calculated. Where Um for both houses must be equal to be able perform the materials change without affecting the construction. Afterwards, an Environmental Product Declaration- EPD were used to see the different products' environmental impact.  The results showed that the Um became the same which means that the energy performance is equal both houses. The renewable materials contributed to reducing the greenhouse emission of the new house. The conclusion shows that the studied materials’ environmental impact for the house Astrid decreased with up to 41 percent. / Idag står byggbranschen för 21 procent av växthusgasutsläppen i Sverige enligt Boverket. För att åstadkomma en förändring bör byggbranschen inrikta sig mer på hållbart byggande. Det som orsakar växthuseffekten främst inom byggsektorn är utvinning av råvara, transport och tillverkning av material. För att bygga hållbart kan icke förnybara material bytas mot förnybara, som till exempel plast mot vindskyddsskiva, för att minska växthuseffekten. Trä är ett bra exempel på ett förnybart material. I studien kommer typhuset Astrid, som är ett nyckelfärdigt hus från Älvsbyhus, att undersökas. Typhuset Astrid har en boarea på 107 m2 med tre rum och kök. Där syftet är att få ett trähus som är likvärdigt typhuset Astrid i energiprestanda, men med en lägre växthuseffekt genom att byta icke förnybara material mot träprodukter. Metoden som användes var att först inventera typhuset Astrid samt att se vilka byggmaterial som går att byta ut. Genom litteraturstudier hittades alternativa material samt övriga relevanta fakta. Sedan beräknades den genomsnittliga värmegenomgångskoeffiecient – Um. Där Um för båda husen ska vara lika stort för att kunna genomföra materialbytet utan att påverka konstruktionen. Därefter användes miljövarudeklaration- EPD, för att se de olika produkternas miljöpåverkan.  Resultaten visade att Um blev detsamma vilket innebär att energiprestandan är likvärdig för båda husen. De förnybara materialen bidrog med att sänka det nya husets växthuseffekt. Slutsatsen visar att de studerade materialens miljöpåverkan för typhuset Astrid minskade med upp till 41 procent.
1068

The Atoyac River : A study about its problems and possible futuresolutions from a sustainable perspective

The, Stephanie, Blomqvist, Anton January 2017 (has links)
Because of extensive industrial and domestic wastewater discharge, the Atoyac river has become one of Mexico's most polluted rivers. The aim of the paper is to investigate the contaminations of the river due to the different polluters and what impacts it has on the environment and society. Further the paper aims to identify necessary solutions in order to restore the river to its natural state, within a sustainable point of view, by using the model of sustainable development proposed by Peter Glavič and Rebeka Lukman (2007). The study is based on literature reviews, where it was concluded that the Atoyac river is polluted by different contaminations such as BOD, coliforms, metals, heavy metals and toxic chemicals, which has affected the environment, ecosystem services, people's health and agriculture in a negative way. There is an understanding that violating social and environmental aspects will also have an impact on the economy in the long run in form of sick work force, loss of necessary ecosystem services and the cost for repairing the environmental damages. It was investigated that if change and effective actions are to be achieved within a sustainable development approach, methods/tools such as Purification, Polluters Pays Principle, Pollution Control, Waste Minimization, Cleaner Production, Environmental Legislation and Environmental Engineering, suggested by Glavič and Lukman(2007) need to be assimilated. These tools were connected to an earlier stage of suggested potential solutions of big variety. The paper also concludes that the progress towards sustainability in the case of the Atoyac river and Mexico in general lies on a very fundamental level and still has a long way to go. / På grund av omfattande utsläpp av industriellt och privat avloppsvatten har floden Atoyac blivit en av Mexikos mest förorenade floder. Syftet med denna rapport är att utvärdera flodens många föroreningar och se vilka konsekvenser dessa har för miljön och samhället. Utöver detta identifieras nödvändiga lösningar för att återställa floden till dess naturliga skick inom ett hållbarhetsperspektiv, genom att använda modellen för hållbar utveckling som föreslagits av Peter Glavič och Rebeka Lukman (2007). Rapporten är baserad på litteraturstudier, och detta ledde till slutsatsen att Atoyac är förorenat av olika föroreningar som BOD, koliforma bakterier, metaller, tungmetaller och giftiga kemikalier, vilka har påverkat miljön, ekosystemtjänster, människors hälsa och jordbruket på ett negativt sätt. Det är även tydligt att den negativa effekten på samhället och miljön även kommer att påverka ekonomin på lång sikt i form av sjukskrivningar, förlust av ekosystemtjänster samt kostnader för att reparera miljöskador. Om en förändring ska uppnås inom ramen för en hållbar utvecklingsstrategi, föreslås metoder/verktygså som Purification, Polluters Pays Principle, Pollution Control, Waste Minimization, Cleaner Production, Environmental Legislation and Environmental Engineering som Glavič och Lukman föreslagit (2007). I denna studie drar man även slutsatsen att Atoyac, och även Mexiko i allmänhet, har en lång väg kvar att gå för att uppnå en hållbar situation.
1069

En möjlighet till en hållbar byggbransch : Jämförelsestudie mellan stommaterialen KL-trä och prefabricerad betong / An Opportunity for a Sustainable Construction Industry : Comparative Study between CLT and Prefabricated Concrete as Frame Material

Paananen, Linnea, Burom Injonglan, Gamm January 2019 (has links)
Byggbranschen står idag för cirka 21 procent av Sveriges totala årliga utsläpp av växthusgaser. En stor utmaning är att kunna uppnå klimatlagens mål som innebär att Sverige inte ska ha några nettoutsläpp av växthusgaser i atmosfären de kommande decennierna. Samtidigt ökar behovet av fler bostäder i samband med en ökad befolkning. Betong är det material som dominerar dagens industriella byggande av flervåningshus och i samband med den tidigare svenska lagen som förbjöd träkonstruktioner med fler än två våningar är träbyggandet i Sverige inte lika etablerat i samma utsträckning som betongkonstruktioner. För att öka förståelsen och kunskapen om träkonstruktioner bland aktörer i byggbranschen som exempelvis beställare, är syftet att jämföra en KL-trästomme och en prefabricerad betongstomme utifrån skillnader i miljöpåverkan, materialkostnad och byggtid. Med handlingar från ett referensprojekt med KL-trästomme erhållna av Bjerking har en undersökning av stommens materialåtgång utförts, för att sedan kunna ersättas med en prefabricerad betongstomme. Med hjälp av materialåtgången för respektive stomme har jämförelsestudien slutförts. Resultatet visar att KL-trästommen har mindre miljöpåverkan och total materialkostnad jämfört med den prefabricerade betongstommen, dock är inte alla material i KL-trästommen inräknade i studien. De uteslutna materialen är enligt uppgift kostsamma vilket i slutändan kan medföra att stommen i KLträ blir det dyrare alternativet. Byggtiden som i detta fall är tiden för stommontage uppskattades till cirka en arbetsvecka per våningsplan för båda stommarna, men det krävs mindre arbetskraft för KLträstommen. Slutsatsen är att KL-trä är det mest miljövänliga stommaterialet för att bygga referensprojektet i Kajstaden eftersom att det bidrar minst till miljöpåverkan. Den prefabricerade betongstommen är mer fördelaktig om en mindre materialkostnad är det som prioriteras. Om en kortare byggtid med mindre arbetskraft önskas är KL-trästommen mer gynnsam. I framtiden bör den viktigaste parametern vid val av stommaterial vara det med minst miljöpåverkan för att byggbranschen ska bli mer hållbar. / The construction industry is currently responsible for about 21 percent of Sweden’s total annual emission of greenhouse gases. A major challenge is to be able to achieve the goals of the climate change act, which means that Sweden will not have any net emissions of greenhouse gases in the atmosphere in the coming decades. At the same time, the need for more housing increases in connection with an increased population. Concrete is the construction material that dominates today’s industrial construction of multi-storey buildings and in connection with the earlier Swedish law that prohibited wooden structures with more than two stories, wood construction in Sweden is not as developed to the same extent as concrete structures. In order to increase understanding and knowledge of CLT structures among operators in the construction industry, such as clients, the purpose is to compare a CLT structure and a prefabricated concrete frame based on differences in environmental impact, material cost and construction time. With documents from a reference project with CLT structure obtained by the company Bjerking, an investigation of the construction’s material consumption has been accomplished, in order to be replaced with a prefabricated concrete frame. The comparative study has been completed using the material consumption for each frame. The results shows that the CLT structure has less environmental impact and total material cost compared to the prefabricated concrete frame, however, not all materials in the CLT structure are included in the study. The excluded materials are reportedly costly, which in the end means that the CLT structure can become the more expensive alternative. The construction time, which in this case is the time for the frame assembly, was estimated to be about one working week per storey for both frames, but less workers is required for the CLT structure. The conclusion is that the CLT structure is the most environmentally-friendly frame material for building the reference project in Kajstaden because it contributes least to the environmental impact. The prefabricated concrete frame is more advantageous if a lower material cost is the priority. If a shorter construction time with less workers is desired, the CLT structure is more favorable. In the future, the most important parameter in the choice of frame material should be the one with least environmental impact for the construction industry to become more sustainable.
1070

Storskalig svensk textilåtervinning : Aktuella problem och rekommendationer för framtiden

Zhang, Rui Liang, Rask, Lukas January 2017 (has links)
Textilindustrin står inför nya utmaningar till följd av den ökande globala textilkonsumtionenoch den ökande avfallsmängden. På grund av bomullens resursintensiva och miljöfarligaproduktion ökar förväntningarna att kunna möta framtidens textilefterfrågan med mindreresursintensiva och mer miljövänliga alternativ. Idag saknar vi en storskalig svensktextilåtervinning och det ökade textilavfallet kan samtidigt hanteras med hjälp av cirkulärekonomi. Genom en uppskalning av en kemisk återvinningsprocess utan stora materialförlusterkan hållbarare alternativ till bomull erhållas samtidigt som textilavfallet hanteras på ett effektivtsätt. Återvinningsprocessen omvandlar bomull till dissolvingmassa (en typ av textilmassa) förviskosproduktion. Därför undersöker vi i detta projekt vilka problem som finns och anger vårarekommendationer för att kunna realisera en sådan textilåtervinning för svenska textilflöden påen större skala, sett ur ett resurseffektivitets- och miljöperspektiv.Vi har genomfört ett kvalitativt projekt med stor vikt på litteratur. Kompletterande intervjuerhar genomförts för att identifiera och kartlägga olika steg i återvinningscykeln. Dessutom hartextilindustrins utveckling analyserats. Utifrån analysen har slutsatser dragits om hur framtidenssituation kan bli för cellulosabaserade textilier. Insamling, sortering, mekanisk och kemiskåtervinning har identifierats som huvudkomponenter och vår slutsats är att dessa behöverutvecklas gemensamt för en fungerande, resurseffektiv och miljövänlig textilåtervinning. Dettagörs för att undvika olika flaskhalsar i återvinningscykeln. Därmed kan en cirkulär ekonomiuppnås. Utifrån analysen konstateras att textilindustrin ändrar karaktär och blir allt merkemibaserad, likt ett bioraffinaderi, där man tar tillvara på alla restprodukter. / The textile industry is facing new challenges as a result of increasing global textile consumptionand the increasing volume of waste. Due to the resource-intensive and environmentallyhazardous production of cotton, expectations are increasing to meet future demand for textileproducts with less resource-intensive and more environmentally friendly alternatives. Todaywe lack a large-scale Swedish textile recycling and the increased amount of textile waste canbe handled by means of circular economy. By scaling up a chemical recycling process withoutmajor material losses more sustainable alternatives to cotton can be obtained while managingthe waste efficiently. The recycling process converts cotton into dissolving pulp (a type oftextile pulp) for viscose production. Thus, we will during this project investigate the problemsthat exist and give our recommendations to implement such a textile recycling for Swedishtextile flows on a larger scale, viewed from a resource efficiency and environmentalperspective.We have made a qualitative study with emphasis on literature studies. Additional interviewshave been conducted to identify and map out various steps in the recycling process. In addition,the development of the textile industry has been analyzed. Based on this analysis, conclusionshave been drawn about how the future situation may be for cellulose-based textiles. Collection,sorting, mechanical and chemical recycling have been identified as main components in therecycling process and our conclusion is that they need to be developed simultaneously for aresource efficient and environmentally friendly textile recycling. The purpose is to avoiddifferent bottlenecks in the recycling process. A circular economy could therefore be achieved.Based on our analysis, a conclusion can be drawn that the textile industry is changing itscharacter and is becoming more chemically intensive, similar to a biorefinery, where allresidues are used.

Page generated in 0.0338 seconds