• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1563
  • 467
  • 180
  • 131
  • 77
  • 64
  • 45
  • 29
  • 27
  • 26
  • 25
  • 18
  • 17
  • 13
  • 13
  • Tagged with
  • 2991
  • 487
  • 465
  • 444
  • 417
  • 329
  • 319
  • 315
  • 287
  • 272
  • 272
  • 267
  • 256
  • 229
  • 227
  • 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.
381

The mothership - a mixed-use high-density proposal to combat urban sprawl

Bowley, Wesley 30 September 2019 (has links)
The built environment is responsible for a large portion of total energy use and emissions. A large portion comes from the buildings themselves, but also the transportation system to move people around. As global populations grow, and more people migrate to cities, it is critically important that new city growth is done in the most sustainable manner possible. The typical North American pattern of urban growth is urban sprawl, characterized by single use type zoning, low density, transportation system dominated by personal vehicles, and poor public transit. Urban sprawl has numerous downsides, including poorer energy efficiency in buildings and infrastructure, more congestion and higher emission from vehicles, as well as many negative health effects. This thesis presents the concept of a Mothership, a large, high-density mixed-use building designed to combat urban sprawl and minimize energy use and emissions of the built environment. A mothership is designed to provide all the amenities and housing of a typical suburb for 10,000 people. The analysis in this thesis employ building simulation tools to model various mothership designs and analyse the operational and embodied energy and carbon emissions for each design, and compare it to base cases of more traditional building use types such as single detached homes, and different types of apartment buildings. The effect of high-performance building envelopes and other building materials on operational and embodied energy and emissions are analysed. A multi objective optimization analysis is performed to determine which technologies and combinations of technologies provide the lowest cost solution to meet the mothership’s energy demands while also minimizing emissions. The mothership’s effect on transportation emissions is also investigated. The building’s mixed-use nature allows trips to be satisfied within walking distance in the building. The high concentration of people makes for a good anchor load for public transportation, so the emissions reductions of implementing a bus rapid transit system from the mothership to the central business district is estimated. To reduce transportation emissions further, the effect of an electric car share fleet for mothership residents use is also quantified. The energy system of a mothership is optimized, along with base cases of single detached homes, under numerous scenarios. These scenarios are designed to explore how the energy system changes in an attempt to answer a series of research questions. Some of the measures explored are a high carbon tax, net metering, and emissions limits of net zero, and negative emissions with two different electrical grid carbon intensities. Results showed that a highly insulated, timber framed mothership can achieve very high reductions in energy use and emissions. Overall it showed reductions of 71%, 73%, and 74% in operational energy, embodied energy and embodied carbon respectively, over a baseline case of single detached homes. It was estimated that transportation emissions could be reduced by 58% through the mixed-use development reducing the number of trips and electrically powered transportation vehicles and bus rapid transit. This gives a combined total emissions reduction of 61%. Energy system optimization showed that the mothership design in achieved far lower costs and emissions (4 and 8.7 times lower respectively) than the base case of single detached homes. Of the mothership cases examined, the most expensive case was the one which had a carbon tax, with an annualized cost of $4.3 million. The case with the lowest annualized cost was one with, among other factors, a net zero carbon emissions restriction (annualized cost of $3.08 million. Many of the cases had negative operating costs due to the sale of renewable energy or carbon credits. This illustrates that the integration of renewable energy technologies is not only beneficial for reducing emissions but can also act as an income pathway for energy systems. / Graduate
382

Optimal Design of District Energy Systems: a Multi-Objective Approach

Wang, Cong January 2016 (has links)
The aim of this thesis is to develop a holistic approach to the optimal design of energy systems for building clusters or districts. The emerging Albano university campus, which is planned to be a vivid example of sustainable urban development, is used as a case study through collaboration with the property owners, Akademiska Hus and Svenska Bostäder. The design addresses aspects of energy performance, environmental performance, economic performance, and exergy performance of the energy system. A multi-objective optimization approach is applied to minimize objectives such as non-renewable primary energy consumptions, the greenhouse gas emissions, the life cycle cost, and the net exergy deficit. These objectives reflect both practical requirements and research interest. The optimization results are presented in the form of Pareto fronts, through which decision-makers can understand the options and limitations more clearly and ultimately make better and more informed decisions. Sensitivity analyses show that solutions could be sensitive to certain system parameters. To overcome this, a robust design optimization method is also developed and employed to find robust optimal solutions, which are less sensitive to the variation of system parameters. The influence of different preferences for objectives on the selection of optimal solutions is examined. Energy components of the selected solutions under different preference scenarios are analyzed, which illustrates the advantages and disadvantages of certain energy conversion technologies in the pursuit of various objectives. As optimal solutions depend on the system parameters, a parametric analysis is also conducted to investigate how the composition of optimal solutions varies to the changes of certain parameters. In virtue of the Rational Exergy Management Model (REMM), the planned buildings on the Albano campus are further compared to the existing buildings on KTH campus, based on energy and exergy analysis. Four proposed alternative energy supply scenarios as well as the present case are analyzed. REMM shows that the proposed scenarios have better levels of match between supply and demand of exergy and result in lower avoidable CO2 emissions, which promise cleaner energy structures. / <p>QC 20160923</p>
383

Functional diversity and ecosystem-level processes in a short-tussock grassland

Mason, Norman, n/a January 2006 (has links)
Increased functional diversity has been linked to an increase in ecosystem level processes (ELPs), such as productivity, ecosystem reliability and invasion resistance. However, there has been no exact definition of functional diversity and it is not known which indices are appropriate for its measurement. Consequently, continuous indices have rarely been applied in examination of relationships between functional diversity and ELPs and little is known of the mechanisms linking functional diversity to ELPs. This thesis begins by providing an exact definition of functional diversity, identifying its primary components and devising appropriate continuous indices for the measurement of these components. These indices are used to examine relationships between functional diversity and three ELPs - biomass production, the reliability of biomass production and invasion resistance. Initially these examinations are conducted using a mechanistic community assembly and dynamic model. This model is based on physiological and morphological character data for species occurring in the short-tussock grassland communities of the Luggate field experiment, in the southern South Island, New Zealand. Finally, relationships between functional diversity, mean annual community cover and the reliability of cover are examined in the Luggate field experiment. Functional composition (i.e. the actual functional characters of the species within a community) appeared to exercise the greatest influence on ecosystem reliability in the community assembly and dynamic model. However, there was evidence that functional diversity increased the reliability of productivity via the co-variance effect. Functional composition also exercised the greatest influence over mean annual productivity in the model, almost completely accounting for the negative relationship between functional diversity and mean annual productivity. These results are respectively analogous to the positive and negative selection effects seen in species richness / ELP relationships. Both functional diversity and functional composition influenced community invasion resistance in the model. Here, increased functional diversity acted to increase community resistance to invasion. In the Luggate field experiment, neither functional diversity nor functional composition was related to mean annual cover, though species richness was positively related to it. Increased functional diversity acted to increase the reliability of cover. However, this did not appear to occur via the co-variance effect, but as a result of increased functional diversity increasing consistency in the species composition of experimental plots through time. These results demonstrate that studies examining functional diversity must account for the effects of species identity. A framework is proposed to accommodate selection effects associated with functional diversity / ELP relationships. The usefulness of the co-variance effect as a testable mechanism linking functional diversity to ecosystem reliability in the field is questionable, as there is no objective way of measuring it.
384

A classroom management and interpersonal skills programme for teachers

Crossing, Helen, n/a January 1982 (has links)
Accountability has become a key issue in the delivery of human services, and counsellors have been challenged to demonstrate that what they do makes a difference and that what they do meets the needs of the system in which they work. Thus proponents of the consultancy model such as Dinkmeyer (1973) have urged counsellors to move from the crisis-oriented approach in which only a few benefit from counsellor services to a consultative role which involves the counsellor with the total system. In 1979 the author was appointed to the Metropolitan West District of Sydney. This is an area with many social problems such as high unemployment, single parent families and families receiving social welfare benefits. Many students attending school are adversely affected by their home environment. To compound the problem a difference in value systems exists between home and school, which is a source of frustration to both teachers and students. As a result many children were referred for counselling because they were behaviour problems in the classroom. It was not possible for the counsellor to see all the students referred so other strategies needed to be employed. From discussions with teachers concerning the management of students who were behaviour problems it became apparent that teacher training had left them ill-equipped to deal with the student behaviours they were facing. A Classroom Management and Interpersonal Skills programme was designed and presented to a group of Primary school teachers in one of the schools to which the author was appointed. Evaluation of the effectiveness of the programme was based on the statistical analysis of pretest and post-test measures of teachers and students of those teachers participating in the programme. In addition to reporting on outcomes of the programme this study provides a theoretical rationale for its development. The statistical evidence does not strongly support the effectiveness of the programme. However there are some trends, particularly in the teacher data, which suggest that the programme was effective in bringing about teacher attitude change towards students. Teachers' written evaluations of the programme, together with informal feedback, indicate the programme was successful in providing some of the answers to behaviour problems which occur in the classroom. A corollary to the presentation of the programme has been a reduction in the number of children referred to the author as "behaviour problems". This has provided more time to work with infant children and parents, both counsellor functions which the administrative staff see as significant, and to continue in the role as a consultant to teachers.
385

Waste Management with Focus on Waste incineration with energyrecovery in Chisinau Municipality, Moldova

Gunnarsson, Martin, Johannesson, Rickard January 2010 (has links)
<p>The amount of waste in the world increases every year due to an improved living standard andgrowing population. The problem is especially large in poor countries where the ability tohandle the waste is limited due to financial and management problems. If instead wastematerial is seen as a resource it can help reduce the amount of waste on landfill. Byincinerating waste and recover the energy it would also help reducing greenhouse gasemissions from landfill and give electric and thermal energy.Chisinau Municipality in the Republic of Moldova today lacks several important parts fora satisfying waste management. Today most of the waste generated in Chisinau municipalityends up at the municipality landfill. The current contract to use the landfill expires on the 31December 2010, if the municipality won’t be able to renew the contract they have to look forother ways to deal with the waste problem. As the dominating source for energy in Chisinau isimported natural gas, an effective way to reduce the use of gas for electricity and thermalenergy production would be to use waste material for incineration with energy recovery.Therefore, the goal with this thesis is to evaluate the possibility to extract energy from coincinerationof sewage sludge and waste material generated in Chisinau. To reach this goal thesituation in Chisinau where studied on site for two months, quantities and composition of thewaste material was investigated. Based on the data gathered on the waste, a suitabletechnology for the waste-to-energy (WTE) plant is proposed. The proposal is made based onthe assumption that a WTE plant would not be established until 2025.The result shows that the waste material in Chisinau can be used for co-incineration ofwaste and sludge. The calorific value of the waste material was determined to 7.87 MJ per kg.The suggested WTE plant has the total power of 138 MW, the result based on that all wastematerial available 2025 are incinerated. Annually this makes it possible to recover 1152 TJ(320 GWh) electric power and 2650 TJ (736 GWh) heat, based on 8000 operating hoursannually.Even if a WTE plant sounds like a good investment it is a long time before a plant couldoperational. Much is to be made in the waste management to have well-functioninginfrastructure that will work together with an incineration plant. Furthermore, the data used inthis study regarding the quantities is very uncertain and further studies in affected areas arenecessary before a WTE plant can be established.</p> / <p>Den totala mängden avfall i världen ökar varje år som följd av ökad folkmängd ochlevnadsstandard. Problemet är extra påtagligt i fattiga länder med begränsade ekonomiskaresurser för att ta hantera avfallet. Om avfallet istället skulle ses som en resurs skulle detkunna reducera andelen avfall som läggs på deponi. Genom att förbränna avfallet medenergiåtervinning skulle också växthusgaserna från deponering minska och samtidigt geelektrisk och termisk energi.Chisinau kommun i Republiken Moldavien saknar idag flera vitala delar iavfallshanteringen. Idag slutar den största delen av avfallet som produceras i Chisinaukommun på den kommunala deponin. Kontraktet för att använda deponin löper ut den sistadecember 2010, om Chisinau kommun inte tillåts förnya kontraktet är det nödvändigt att sesig om efter nya lösningar för avfallshanteringen. Eftersom den dominerande källan för energii Chisinau är importerad gas, skulle ett effektivt sätt att reducera gasanvändningen vid el ochtermisk energiproduktion att förbränna avfall med energiåtervinning.Av den orsaken är målet med studien att utvärdera möjligheterna att utnyttjasamförbränning med energiåtervinning av avfall och avloppsslam från Chisinau kommun. Föratt nå detta mål har den nuvarande situationen i Chisinau kommun studerats på plats under tvåmånaders tid, detta för att undersöka vilka mängder avfall som årligen produceras och huravfallets fraktionsfördelning ser ut. Baserat på de data som samlats in föreslogs en lämpligavfallsförbränningsanläggning. Förslaget är baserat på antagandet att enavfallsförbränningsanläggning inte är etablerad förrän tidigast 2025.Resultatet visar att det är möjligt att samförbränna avloppsslam och avfall i Chisinau. Detkalorimetriska värmevärdet för avfallet och slammet har bestämts till 7.87 MJ per kg. Det irapporten presenterade förslag på kraftvärmeverk för avfallsförbränning kommer att ha entotal effekt av 138 MW, resultatet är baserat på att allt tillgängligt kommunalt avfall 2025förbränns. Kraftvärmeverket beräknas årligen utvinna TJ (320 GWh) elektrisk energi och2650 TJ (736 GWh) termisk energi, beräknad på 8000 drifttimmar årligen.Även om en avfallsförbränningsanläggning låter som en god investering så ligger detlångt fram i tiden innan en sådan anläggning är möjlig att etablera. Först måste en brafungerande infrastruktur som fungerar tillsammans med avfallsförbränningsanläggningenupprättas. Vidare bör poängteras att de data som använts i denna studie gällandeavfallsmängder är ytterst osäkra och ytterligare studier inom området krävs innan enavfallsförbränningsanläggning kan etableras.</p>
386

REDUCTION OF THE COSTS IN A HOUSE IN VALBO THAT USES ELECTRICITY AS ENERGY SOURCE : Study of the installation of a heat pump or connection to the district heating

OrdeÑana, Ianire January 2008 (has links)
<p>The analyzed building in this project is located in Valbo, 9016 Stiftelsev 6. This house is a property of Gavlegårdarna, and it is being used as a house for disabled people. The building consists on five apartments, with one patient in each apartment. Some social workers help those patients in everything they need, making their living in the house as easy as possible.</p><p>The aim of this project is to find out the best option of reducing the energy consumption in this house. There are some alternatives to reduce the energy or the energy costs as; efficiency measures, load management and energy conversion.</p><p>This project is focused on the energy conversion for reducing the energy consumption. As it is the best option for obtaining a considerable reduction in the annual costs.</p><p>First of all the energy balance of the house is analyzed. By studying the energy balance it is possible to find out how the energy consumption of the house is divided. On one hand there is the heat supplied and on the other hand the heat losses.</p><p>As it was said before this project is focused in the reduction of the energy consumption by means of converting to another energy supplying method. Two alternatives have been studied: the installation of a heat pump and the connection to the district heating of Gävle.</p>
387

Assessment of waste and biofuel resources for district heating in the region of Gävle in Sweden

Alonso, Laura January 2008 (has links)
<p>Fuel availability and security of supply are two of the most important factors in the well functioning of a company like Gävle Energi. Another important factor is the price of the fuels used. The transportation cost plays also an important role when purchasing fuels from different sources. Currently the fuels used in Gävle Energi are mainly woody biofuels, but waste and peat could also be used in the future.</p><p>The aim of this thesis is to provide an overview of the different available biofuels in the region of Gävle. The fuels considered in the study are:</p><p>- Bark</p><p>- Forest Residues</p><p>- Wood waste</p><p>- Pellets and Briquettes</p><p>- Garbage/waste materials</p><p>- Peat</p><p>The research is focused on the physical properties of the fuels, their price and transportation cost, environmental and legislation issues and the availability in the region of Gävle. A 10-year perspective is defined for an estimated availability of the different fuels in te region.</p>
388

Energy audit and saving analysis of a building : Study of heat pump installation and district heating connection

Urtasun, Cristina January 2008 (has links)
<p>The object of analysis in the present document is a residential house in Sätra. This building has a hydronic space heating system with radiators spread around the house and a heating recovery system ventilation which also use water for reheating. Water for space heating, ventilation and hot tap water is nowadays heated in an electric boiler.The aim of this project is to make a diagnosis of the current situation, evaluate different alternatives for supplying hot water to the house, and to study costs and possible savings by comparing the actual facilities with the proposals done.</p>
389

Heat Pump System using Waste Energy for a District Heating Application

Vivas, David January 2008 (has links)
<p>Nowadays, reducing energy usage as well as reducing environmental impacts due to energy efficiency measurements is very common in the industrial sector. The objective of these measurements is to achieve better sustainable energy systems.</p><p>Sandvik Materials Technology (SMT) AB, one of the business areas of the enterprise Sandvik AB, is not an exception in that field.</p><p>The aim of this thesis project is to analyze how to use waste energy from the cooling of a steel plant for an internal district heating (DH) system within the industrial area of SMT AB located in Sandviken, Sweden. In order to reduce the energy use, the economic cost and the environmental impacts within the industrial area.</p><p>In order to achieve the aim has been studied the heat pump devices as the system to transfer the waste heat from the cooling of the steel plant to the DH system. Therefore, after the introduction to the project (part 1: Introduction) and the explanation of the aim</p><p>(part 2: Aim, methodology and delimitations), the basics of the heat pumps are studied and explained (part 3: Heat pumps theoretical study). After that, the knowledge acquired in part 3 is applied to define and calculate the heat pump system which fulfill the required</p><p>objectives achieving the greatest energy, economical and environmental impacts reductions (part 4: Heat pump practical study).</p><p>The achieved results show that there is a great opportunity to reduce the energy use within the industrial area (until 45300 MWh per year), the economical cost (until 2 millions euros per year) and the 2 CO emissions (until 2.3 millions of 2 CO kg per year1).</p><p>Therefore, the conclusion is that it must be taken into account to build the heat pump system and also that the effort of finding possible energy efficiency measurements within the industrial sector must be one priority for all the industrial companies, not only because the possible potential economical reductions, but also because of the potential environmental impacts reductions.</p>
390

Sustainable Energy : Implications of Charcoal Use in Babati Households & Possibilities to Use Alternative Energy Sources

Jämting, Hanna January 2008 (has links)
<p>This thesis investigates social impacts of charcoal use in households in the Tanzanian town Babati. In Tanzania a majority of the population use charcoal and firewood as their main energy source. A part from the environmental problems connected to charcoal use; there are also considerable social impacts on women’s daily lives. Cooking and collection of wood fuel are time-consuming and restricts the possibilities for women to work and study. The thesis includes an investigation on how the Tanzanian government tackles problems connected to charcoal use, social as well as environmental. The result shows that the Tanzanian government is working with charcoal related problems to some extent but as previous studies shows there are still more that can be done. The main efforts made concentrate on information campaigns and promotion of more energy efficient equipments. One important problem is however that wood fuel is the cheapest available energy source and hence the incentives to start using other, more sustainable, energy sources are very small. The thesis also investigates possibilities for Babati households to substitute charcoal use with renewable energy sources available in the town. The result shows that the possibilities to use renewable energy currently are very limited and mainly affordable to richer households.</p>

Page generated in 0.0529 seconds