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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.
11

Heating and Ventilation of Highly Energy Efficient Residential Buildings: Environmental Assessment of Technology Alternatives

Sørnes, Kari January 2011 (has links)
The aim of this study was to determine the level of environmental impact and primary energy resulting from demands placed on residential ventilation and heating systems; a conventional residential house built to the 2007 Norwegian building code with a standard heating system was compared against three technology scenarios used in a passive house of the equivalent size. Both houses have wooden framework and cladding and are projected by the Norwegian building company Norbohus. An economical evaluation of the heating systems was also done. The alternative heating option for the conventional house, Stord TEK 07, was based on current Norwegian energy consumption patterns; a combination of electricity and firewood is used to meet heating demand. This heating mix was also modeled as an option for the heating requirements of the passive house, named Stord Passive S1. Additionally, a solar collector system (Stord Passive S2) and an air-to-water heat pump (Stord Passive S3) were modeled for the passive house. Finally, a balanced mechanical ventilation system was evaluated for both buildings. The life-cycle assessment method used was the ReCiPe method and the electricity used in the operation phase was based on the Nordic electricity mix.The results of this study indicate that Stord TEK 07 has the largest emission output in relation to output of CO2-eq, presented in the impact category “Climate change”. From a life-cycle perspective, the heating system requirements of a Stord TEK 07 house are 47.5 and 45 percent higher than the renewable energy solutions of passive house scenarios S2 and S3, respectively. Total life-cycle primary energy requirements in the Stord TEK 07 house were almost twice that of the renewable solutions in the passive house. Using the Norwegian standard heating system of Stord TEK 07 in a passive house as was done in Stord Passive S1, also results in a large improvement; output of CO2-eq and use of primary energy was reduced by 34-35 percent. Stord TEK 07 has also the highest emission output in most of the other impact categories and the largest present value costs, when building constructing costs are excluded. The heat pump solution, Stord Passive S3, has the lowest impact in most categories; however, the solar collector system Stord Passive S2, had lower output of CO2-eq. Stord Passive S2 has also lower present value costs then the air-water heat pump Stord Passive S3.A balanced ventilation system with 80 percent heat recovery was studied for both the houses. The benefit of heat recovery is recognizable in all the impact categories considered. The energy consumption and potential harmful emissions resulting from the electrical energy used by fans during the life cycle far exceed the environmental impacts that result from manufacture and transportation of the ventilation unit. The study revealed that the heat-recovery system must have efficiency greater than 15 percent to achieve reduction concerning output of CO2-eq and use of primary energy for Stord TEK 07; this requirement increases to 42 percent in houses built to the passive house standard house, Stord Passive.
12

Masteroppgave i vassdragsteknikk : Sammenlikning av små elvekraftverk og kraftverk med magasin / Master Thesis in Hydro Power

Lofthus, Sigrid Jacobsen January 2012 (has links)
Det siste tiåret har småkraftutbygginger økt kraftig. Små kraftverk har generelt blitt oppfattet som mindre kontroversielt enn større magasinkraftverk, men lite er gjort for å sammenligne disse to kraftverkstypene når det gjelder nytteverdi og miljøpåvirkning. Målet med denne rapporten var å gjøre en sammenligning av et større magasinkraftverk og flere små elvekraftverk med tanke på produksjon, økonomi, naturinngrep, miljøvirkning og samfunnsnytte. Videre var det ønskelig å gjøre en mer generell vurdering av små kraftverk og et større magasinkraftverk, med utgangspunkt i de analyserte kraftverkene. Studieområdet var Kvannevatn og Sagelva i Rana kommune, der det i dag står tre små elvekraftverk, Kvannevatn kraftverk, Sagelva I og Sagelva II. Minikraft AS, som er eier av disse elvekraftverkene, søkte tidligere om å få bygge et større magasinkraftverk. Sammenligningen tar utgangspunkt i dagens små elvekraftverk og et tenkt tilfelle med kun det planlagte magasinkraftverket. Analysen av magasinkraftverket ble basert på dataprogrammet nMAG2004 som er en simuleringsmodell for drift og kraftproduksjon i vannkraftsystemer. Simuleringene forutsetter informasjon om blant annet magasin, kraftstasjoner, energimarkedet, restriksjonsdata, operasjonsstrategi og hydrologiske data. De hydrologiske dataene for både magasinkraftverket og de små kraftverkene ble basert på en nærliggende målestasjon, Bredek.For å strukturere de ulike konsekvensene ved en planlagt magasinkraftutbygging, ble Samla plan-metoden benyttet. Den kategoriserer konsekvensene inn i primære virkninger, fysiske virkninger, det levende miljø og til slutt brukerinteressene. Metoden ga også et grunnlag for å fastsette en miljøbasert minstevannføring. Ved å bruke Samla plan-metoden ble fisk og den estetiske opplevelsen av elva vurdert til å være de viktigste verdiene i Sagelva for å sette et miljøbasert krav til minstevannføring. Disse verdiene ville mest sannsynlig ikke blitt ivaretatt ved den minstevannføringen som var planlagt basert på tradisjonelle beregninger til å være 0,035 m3/s om vinteren, og 0,135 m3/s om sommeren. Kravet til en miljøbasert minstevannføring ble satt ved hjelp av building block-metoden som baseres på at hvert definerte behov utgjør en building block i vannføringsregimet (Alfredsen, Harby, Linnansaari, & Ugedal, 2011).Resultatene fra denne masteroppgaven viser at magasinkraftverket har mulighet til å slippe en miljøbasert vannføring og fortsatt ivareta en lønnsom produksjon. Den miljøbaserte minstevannføringen for magasinkraftverket ble satt til 0,15 m3/s fra september til og med april, 0,5 m3/s i mai, 1,5 m3/s i juni og juli, og 0,5 m3/s i august. Denne minstevannføringen ville imidlertid ikke vært forenlig med god produksjon for de små elvekraftverkene. Magasinkraftverket kan også produsere kraft gjennom hele året på grunn av reguleringsmuligheten, noe de tre elvekraftverkene ikke har mulighet til. Det ble derfor konkludert med at magasinkraftverket har større samfunnsnytte enn de tre små kraftverkene med tanke på leveringssikkert. Basert på studiet av de tre elvekraftverkene og magasinkraftverket i Sagelva kan det videre konkluderes med at man ikke kan bevare viktige verdier i et vassdrag ved å sette et minstevannføringskrav gjennom et standardisert «skrivebords-studie». Siden hvert eneste vassdrag er unikt, er det rimelig å anta at disse verdiene må kartlegges og vurderes spesielt for hvert vassdrag, og at krav til minstevannføring bør settes spesielt ut i fra hvilke verdier som skal ivaretas.Ut ifra beregninger viste det seg at det opprinnelig planlagte magasinkraftverket ikke var optimalisert, da bare 2-3 meter av en reguleringshøyde på 10 meter ble utnyttet i et normalår. I tillegg ville flomtapet i et normalår være stort. Dette gjorde at sammenligningen av det planlagte magasinkraftverket og de små kraftverkene basert på produksjonen ville bli misvisende, ettersom magasinkraftverket ikke var optimalisert.På grunn av den dårlige utnyttelsen av magasinet som var planlagt opprinnelig, ble det utført en ny beregning av magasinkraftverket. Denne beregningen optimaliserer ikke magasinkraftverket fullstendig, men var ment til å gi en indikasjon på hvilket potensiale det har. Resultatene fra denne beregningen viste at magasinkraftverket har potensialet til å produsere større mengder kraft enn de tre små elvekraftverkene, men at en optimalisering av magasinkraftverket er nødvendig.
13

Case Study Analysis of Running Distributed Generators in Island Mode : Effects on Reliability of Supply

Hegvik, Anders January 2012 (has links)
As a consequence of increased government efforts to reduce local Norwegian CO_2-emissions the development of small distributed generators have increased. This development is assumed to continue, but at an increasing incremental cost due to the inferior profitability of remaining prospects. To maintain profitability of smaller and high cost distributed generators, cost savings must be implemented. Quality of supply is a significant factor in determining potential profitability. Hence, a significant potential in cost reduction lies in increasing quality of supply. This can be achieved by utilizing the decentralized nature of these power producers by enabling intended island operation. By enabling these generators to run in intended island mode, they are able to supply their local grid with power when fallout of the main grid or other components occurs. This increases the uptime for local customers and therefore increases quality of supply. Five different grids are modeled in PowerFactory based on collected empirical data for the evaluation of the potential for islanding in Norway. With these models different cases utilizing islanding schemes are simulated and the reliability of these configurations compared to a base case representing normal operations. The results from this analysis suggest big reductions in the reliability indices “Energy Not Supplied” and “System Average Interruption Frequency” are possible. In the thesis the reductions achieved are in the 10%-60% range of the base case. The estimated savings earned from increased reliability of supply does not justify the assumed investment needed, but the numbers are not conclusive. Better estimates of expenses and assessing other grids with better prerequisites for islanding could indicate to be profitability.
14

Lærere i lønnskamp - holdninger til status og lønn gjennom media 1986-1988

Steiro, Andreas January 2014 (has links)
No description available.
15

Implementing Hydropower Scheduling in a European Expansion Planning Model

Brovold, Sondre Heen January 2014 (has links)
This Master’s thesis proposes a method for implementing an enhanced hydropower planning formulation in a long-term expansion planning model. The motivation for this work is the important role that hydropower plays in a generation investment environment. In a time where penetration of intermittent renewable energy sources like wind and solar power is heavily increasing, new challenges in the continuous balancing of supply and demand are also introduced. Hydropower and its use of reservoirs as power batteries can respond more or less immediately to such fluctuations. As such, a detailed framework for hydropower scheduling is highly relevant.The presented implementation is carried out in an already-existing expansion planning model for Europe called EMPIRE, which is written in Mosel Xpress. This is a two-stage stochastic optimization model whose objective function is to minimize the total net present value of expected operational costs and investment costs for generation and transmission capacities.The main feature of the proposed framework involves penalization of hydropower through water values. This necessitates a complete hydropower scheduling representation where each reservoir is divided into segments which are assigned a fictitious marginal cost. The inclusion of water values enables comparability with the short-run marginal cost for competitive technologies and introduces the important aspect of conserving water for other periods of the year. Data from SINTEF Energy Research has been used for this purpose.Results from optimization runs in the time span from 2010 to 2060 for an EU 20-20-20 like policy scenario show that the original hydropower availability is too relaxed, thereby causing an overvaluation of this technology. The revamped cost representation by means of water values leads to a lower utilization of hydropower relative to the original model. An earlier deployment of solar power is carried out to replace the lower generation, with a capacity difference between the final and original models peaking at 45% in 2040. Total costs in the system are therefore increased. For both models extensive investments in intermittent renewables are taking place, amounting to 47% of the total capacity in 2060.
16

Mind design : steps to an ecology of human-machine systems

Hoff, Thomas January 2003 (has links)
<p>We have, within the last years, witnessed horrifying tragedies within the transportation domain. Planes fall down, trains crash, boats sink, and car accidents are one of the most frequent causes of death throughout the world.</p><p>What is more, technology seems also to fail in settings that are more mundane. In his book "the trouble with computers: Usefulness, usability, and productivity", T.K. Landauer shows that the productivity has, within the western world, decreased by about 50% from the period 1950-1973 to the period from 1973 to 1993, and claims that this effect is mostly due to the introduction of technology. Even closer to home, technology is still anxiety provoking for most people. One of many everyday observations to support this fact can be seen at the airports. Have you wondered why most people line up, even for hours, without daring to go near the automatic check-in machines?</p><p>What has become of the grandiose promises from the heydays of artificial intelligence? What happened to the mind-machines of Newell and Simon? Where is HAL 9000? The distance between the massive technology positivism observed in the west, and the contemporary role of technology in the society, is, I believe, one of the largest paradoxes of our time.</p><p>What is particularly interesting to note, is that the parody of the AI of the 60s, seems to be recycled every now and again, both within entertainment, the financial world, and within academia. At the turn of the century, we have seen the popularity of movies like The Matrix, we have seen high hopes become sober reality at NASDAQ, and the reductionism of Newell and Simon is alive and well, in disguise of the magic buzzword connectionism. Universities around the world are now buying MRI – scanners on the thousands. We are, yet again (!), on the verge of discovering the mysteries of the mind.</p><p>The slogan "Vorsprung Durch Technic" used by Audi displays something that lies deep within the western mind, namely the tendency to define ourselves and our culture in terms the inherent qualities of technology; precision, logic, rationality, reliability, punctuality, determination and power. Technology is, in many respects, the totem of the western culture. Maybe this thesis should have been about Techno-Totemism. But it is not.</p><p>This thesis, on the other hand, attempts to explore what technology might have looked like, had it not been for techno-totemism, i.e. the prevailing idea within western culture and sciences, that humans are literally machines. This notion makes engineers design technological products as if humans actually were machines, or worse imperfect machines. The imperfect machine metaphor leads directly to the notion of "human error", which is often used in a particularly stupid fashion.</p><p>In this work I lean, on the contrary, on aspects of human cognition that are not machine-like whatsoever, and advocate a change in design focus, from an emphasis on technology to an emphasis on ecology. I have attempted to present my programme positively; that is, to give indications on how, in practical, real life settings, such an approach might be carried out. At certain points, however, it has been necessary to point out the difference of my approach from the traditional cognitive-based Human Factors tradition, to make my points explicit. I apologize to cognitivists and human factors specialists for occasionally making a straw man of their theory. There are many excellent contributions made by these traditions, which are not reflected in this thesis.</p>
17

Mind design : steps to an ecology of human-machine systems

Hoff, Thomas January 2003 (has links)
We have, within the last years, witnessed horrifying tragedies within the transportation domain. Planes fall down, trains crash, boats sink, and car accidents are one of the most frequent causes of death throughout the world. What is more, technology seems also to fail in settings that are more mundane. In his book "the trouble with computers: Usefulness, usability, and productivity", T.K. Landauer shows that the productivity has, within the western world, decreased by about 50% from the period 1950-1973 to the period from 1973 to 1993, and claims that this effect is mostly due to the introduction of technology. Even closer to home, technology is still anxiety provoking for most people. One of many everyday observations to support this fact can be seen at the airports. Have you wondered why most people line up, even for hours, without daring to go near the automatic check-in machines? What has become of the grandiose promises from the heydays of artificial intelligence? What happened to the mind-machines of Newell and Simon? Where is HAL 9000? The distance between the massive technology positivism observed in the west, and the contemporary role of technology in the society, is, I believe, one of the largest paradoxes of our time. What is particularly interesting to note, is that the parody of the AI of the 60s, seems to be recycled every now and again, both within entertainment, the financial world, and within academia. At the turn of the century, we have seen the popularity of movies like The Matrix, we have seen high hopes become sober reality at NASDAQ, and the reductionism of Newell and Simon is alive and well, in disguise of the magic buzzword connectionism. Universities around the world are now buying MRI – scanners on the thousands. We are, yet again (!), on the verge of discovering the mysteries of the mind. The slogan "Vorsprung Durch Technic" used by Audi displays something that lies deep within the western mind, namely the tendency to define ourselves and our culture in terms the inherent qualities of technology; precision, logic, rationality, reliability, punctuality, determination and power. Technology is, in many respects, the totem of the western culture. Maybe this thesis should have been about Techno-Totemism. But it is not. This thesis, on the other hand, attempts to explore what technology might have looked like, had it not been for techno-totemism, i.e. the prevailing idea within western culture and sciences, that humans are literally machines. This notion makes engineers design technological products as if humans actually were machines, or worse imperfect machines. The imperfect machine metaphor leads directly to the notion of "human error", which is often used in a particularly stupid fashion. In this work I lean, on the contrary, on aspects of human cognition that are not machine-like whatsoever, and advocate a change in design focus, from an emphasis on technology to an emphasis on ecology. I have attempted to present my programme positively; that is, to give indications on how, in practical, real life settings, such an approach might be carried out. At certain points, however, it has been necessary to point out the difference of my approach from the traditional cognitive-based Human Factors tradition, to make my points explicit. I apologize to cognitivists and human factors specialists for occasionally making a straw man of their theory. There are many excellent contributions made by these traditions, which are not reflected in this thesis.

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