• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 252
  • 113
  • 44
  • 44
  • 36
  • 27
  • 19
  • 18
  • 10
  • 10
  • 7
  • 5
  • 4
  • 3
  • 2
  • Tagged with
  • 705
  • 112
  • 94
  • 79
  • 71
  • 67
  • 63
  • 62
  • 56
  • 51
  • 38
  • 36
  • 34
  • 34
  • 33
  • 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.
211

Noncompliance, monitoring and the economic theory in carbon trading market

Mihal, Daniela 11 August 2008 (has links)
Addressing climate change is a major undertaking. Agricultural soil has the potential to assist in decreasing the concentration of GHGs in the atmosphere by storing CO2 in the soil. Carbon offset markets have been suggested as a cost effective means of reducing GHG emissions. Farmers can increase their soil sink potential by applying Beneficial Management Practices (BMPs) that enhance carbon sequestration through improvements to soil, nutrient and livestock management practices (Fulton et. al., 2005). Whether or not a market for carbon offsets will emerge depends on a number of factors which mainly are related to the profitability of the BMPs and the costs of implementing a carbon contract. Provided that a market for carbon offsets emerges, the effectiveness of the market depends, in part, on the degree to which buyers and sellers in the market comply with the terms of the contracts they sign. The resource costs associated with monitoring and verification may result in incomplete monitoring. As long as monitoring is not perfect, non-compliance will be an issue. <p>The analysis that will be performed in this thesis introduces non-compliance in the economic analysis of carbon-offset market. The purpose of this work is to examine the overall cost effectiveness of the carbon-offset market when introducing non-compliance. <p>Firstly the theoretical model investigates the incentives for different farmers to participate in the carbon offsets market as well as incentives for engaging in cheating. The model recognizes farmers heterogeneity with respect to cost differences and examines the economic determinants of farmers non-compliance as well as the consequences of non-compliance on the performance of the carbon-offset market. Results support the standard finding that the extent of producers non-compliance decreases with an increase in the audit probability and/or an increase in the penalty per unit of non-compliance. In addition, the number of producers participating in the carbon offsets market is shown to increase with an increase in the carbon-offset price.<p> The analysis then introduces intermediaries in the market that will take care of trading carbon offsets as well as monitoring producers. The traders role in this study is played by an IOF (investor owned-firm) or a PA (producers association). Within the IOF, the analysis focuses on the monopoly and oligopoly structures. The key role of the traders is to guarantee, based on the amount of monitoring that is undertaken, that the emitters purchase only carbon offsets that actually correspond to sequestered carbon. The analysis then examines three cases for the group that monitors farmers compliance a group owned by for-profit traders, a government-run agency and a group owned by the PA trader. This part of the thesis examines what impact the involvement of the traders in the carbon-offset market has on non-compliance, as well as how the structure of the monitoring group affects non-compliance and the amount of carbon offsets traded in the market. The results of the analysis show that the monitoring groups always undertake sufficient monitoring to ensure that full compliance is achieved thus, while non-compliance is possible, it does not occur in equilibrium. The finding suggests that the formation of a government monitoring agency can potentially increase traded output and lower the price paid by emitters, still these changes are likely to be small, particularly when the trading sector is monopolistic. The overall analysis in this chapter shows that the optimal amount of enforcement, and as a result the cost effectiveness of a carbon-offset market, depends on the nature of the organization that undertakes the enforcement. <p>The next consideration of the thesis is the heterogeneity attributed to the timing of sequestration by different farmers. The analysis focuses on the carbon offsets pooling by considering two structures for the aggregator: a for-profit aggregator and a producers association. Pooling resources enables the farmers to benefit from economies of scale. The pricing schedule used by the aggregator is a two-part tariff. The two-part tariff is used as a way of providing an incentive for the farmers sequestering large amounts of carbon to participate in the pool. The study considers two alternatives for the coefficients that might be used to decide on the amount of carbon offsets to which each farmer will be entitled: default coefficient and custom coefficients. Each situation is modeled in a principal agent framework. <p>The analysis examines how the aggregator will target the monitoring service for different group of farmers. The investigation reveals that, under different scenarios, a PA or a FPA (for-profit aggregator) might lead to the formation of a heterogeneous pool or a homogeneous pool of each type. <p>The last issue investigated in this dissertation is the coexistence of a FPA and a PA in the default coefficient case. The analysis show that both aggregator structures can exist together in the market in the same time if the savings in the monitoring costs made possible by the PA are smaller than the cost of organizing the pool. If this condition is not satisfied the FPA cannot survive in the market and the producers association will dominate. <p>In addition to providing a better understanding of how the carbon-offset market may perform when introducing non-compliance, the results of this study can assist in assessing the cost effectiveness of the carbon-offset market when enforcement is undertaken by different organizations. Furthermore, the last consideration of the pooling option might help in selecting which type of pool a heterogeneous or a homogeneous one might perform better under different alternatives.
212

A Time Series Forecast of the Electrical Spot Price : Time series analysis applied to the Nordic power market

Lindberg, Johan January 2011 (has links)
In this report six different models for predicting the electrical spot price on the Nordic power exchange, Nord Pool, are developed and compared. They are evaluated against the already existing model as well as the naive test, which is a forecast where the last week’s observations are used as a prognosis for the coming week. The models developed are constructed so that the models for different time resolutions are combined to create a full model. Harmonic regression with a linear trend are used to identify a yearly trend while SARIMAX/SARIMA time series models are used on a daily and hourly basis to reveal dependencies in the data.   The model with the best prediction performance is shown to be a SARIMAX model with temperature as exogenous variable on a daily resolution, together with a SARIMA model on an hourly resolution. With an average MAPE of 12.69% and a MAPE2 of 6.90% it has the smallest prediction error out of all of the competing models when doing one week forecasts on the whole year 2009.
213

Liu Xiaodong 刘小东 Xiao Dou Hanging Out at the Pool Hall

Sikström Nilsson, Anne-Charlotte January 2011 (has links)
Hometown Boy är ett projekt av konstnären Liu Xiaodong. Tillsammans med en grupp medarbetare besökte han sin barndomsstad  Jincheng i nordöstra Kina, en stad han lämnade för trettio år sedan.. Resultatet visades på UCCA, Ullens Center for Contemporary Art i Beijing. Lius verk synliggjorde individer från en marginaliserad arbetarklass som inte ofta ges utrymme inom porträttkonsten. Mitt syfte har varit att tolka Lius Xiao Dou Hanging Out at the Pool Hall bland annat utifrån ett marxistisktfeministiskt förhållningssätt. Som metod har jag utgått ifrån bildanalyser av verken samt litteraturstudier. Jag fann bl a att dukstorleken tidigare var relaterad till idolporträtt i Kina och viktiga, gärna klassiska, teman i ett historiskt Europa. Jag fann vidare en diskrepans mellan Lius barndomsvänner och dem som dominerar musei- och galleribesök, vilket  jag ser som ett klassmöte där publiken ges möjlighet att studera de avvikande. Liu styr representationen av Xiao Dou. Han förflyttar henne till en manlig sfär och ger henne manliga attribut. I Jincheng Airport ser vi en passiv sida av Xiao Dou. Att Liu valt att avbilda Xiao Dou på dessa sätt kan vara för att väcka publikens intresse genom att rikta uppmärksamheten mot kvinnans situation på landsbygden och hur hon styrs av rådande ideologier och hur det i sin tur begränsar hennes möjligheter. Ändå funderar jag om publiken ser detta eller om vi fastnar i den fysiska representationen av Xiao Dou med för kort klänning i fel rum, en representation som i Xiao Dou Hanging Out at the Pool Hall fallit offer för en mans öga.
214

Effekt av biotopvård på öringpopulationen i två vattendrag

Sahlberg, Tony January 2010 (has links)
I have done a follow up study of the restoration of two rivers, Röälven and Grundan, in order to evaluate the effects of the restoration on the endemic population of trout. Both rivers have been used for timber floating during many years throughout the 20th century, and because of this, had all obstacles such as rocks and wood parts removed. In 2004-2005 both rivers were restored, and rocks and wood were put back into the rivers. Spawning grounds were created and boulder dams were constructed to promote the streaming water. The result showed that the trout population of both rivers increased after the restoration, but also that the trout population of Röälven increased more than that of Grundan. My conclusion is that the way the restoration is of a river contributes to the result.
215

The application of expansion foam on liquefied natural gas (LNG) to suppress LNG vapor and LNG pool fire thermal radiation

Suardin, Jaffee Arizon 15 May 2009 (has links)
Liquefied Natural Gas (LNG) hazards include LNG flammable vapor dispersion and LNG pool fire thermal radiation. A large LNG pool fire emits high thermal radiation thus preventing fire fighters from approaching and extinguishing the fire. One of the strategies used in the LNG industry and recommended by federal regulation National Fire Protection Association (NFPA) 59A is to use expansion foam to suppress LNG vapors and to control LNG fire by reducing the fire size. In its application, expansion foam effectiveness heavily depends on application rate, generator location, and LNG containment pit design. Complicated phenomena involved and previous studies have not completely filled the gaps increases the needs for LNG field experiments involving expansion foam. In addition, alternative LNG vapor dispersion and pool fire suppression methodology, Foamglas® pool fire suppression (PFS), is investigated as well. This dissertation details the research and experiment development. Results regarding important phenomena are presented and discussed. Foamglas® PFS effectiveness is described. Recommendations for advancing current guidelines in LNG vapor dispersion and pool fire suppression methods are developed. The gaps are presented as the future work and recommendation on how to do the experiment better in the future. This will benefit LNG industries to enhance its safety system and to make LNG facilities safer.
216

Effects of Carbon Nanotube Coating on Bubble Departure Diameter and Frequency in Pool Boiling on a Flat, Horizontal Heater

Glenn, Stephen T. 2009 August 1900 (has links)
The effects of a carbon nanotube (CNT) coating on bubble departure diameter and frequency in pool boiling experiments was investigated and compared to those on a bare silicon wafer. The pool boiling experiments were performed at liquid subcooling of 10 degrees Celsius and 20 degrees Celsius using PF-5060 as the test fluid and at atmospheric pressure. High-speed digital image acquisition techniques were used to perform hydrodynamic measurements. Boiling curves obtained from the experiments showed that the CNT coating enhanced critical heat flux (CHF) by 63% at 10 degrees Celsius subcooling. The CHF condition was not measured for the CNT sample at 20 degrees Celsius subcooling. Boiling incipience superheat for the CNT-coated surface is shown to be much lower than predicted by Hsu's hypothesis. It is proposed that bubble nucleation occurs within irregularities at the surface of the CNT coating. The irregularities could provide larger cavities than are available between individual nanotubes of the CNT coating. Measurements from high-speed imaging showed that the average bubble departing from the CNT coating in the nucleate boiling regime (excluding the much larger bubbles observed near CHF) was about 75% smaller (0.26 mm versus 1.01 mm)and had a departure frequency that was about 70% higher (50.46 Hz versus 30.10 Hz). The reduction in departure diameter is explained as a change in the configuration of the contact line, although further study is required. The increase in frequency is a consequence of the smaller bubbles, which require less time to grow. It is suggested that nucleation site density for the CNT coating must drastically increase to compensate for the smaller departure diameters if the rate of vapor creation is similar to or greater than that of a bare silicon surface.
217

Control of Vapor Dispersion and Pool Fire of Liquefied Natural Gas (LNG) with Expansion Foam

Yun, Geun Woong 2010 August 1900 (has links)
Liquefied Natural Gas (LNG) is flammable when it forms a 5 – 15 percent volumetric concentration mixture with air at atmospheric conditions. When the LNG vapor comes in contact with an ignition source, it may result in fire and/or explosion. Because of flammable characteristics and dense gas behaviors, expansion foam has been recommended as one of the safety provisions for mitigating accidental LNG releases. However, the effectiveness of foam in achieving this objective has not been sufficiently reported in outdoor field tests. Thus, this research focused on experimental determination of the effect of expansion foam application on LNG vapor dispersion and pool fire. Specifically, for evaluating the use of foam to control the vapor hazard from spilled LNG, this study aimed to obtain key parameters, such as the temperature changes of methane and foam and the extent reduction of vapor concentration. This study also focused on identifying the effectiveness of foam and thermal exclusion zone by investigating temperature changes of foam and fire, profiles of radiant heat flux, and fire height changes by foam. Additionally, a schematic model of LNG-foam system for theoretical modeling and better understanding of underlying mechanism of foam was developed. Results showed that expansion foam was effective in increasing the buoyancy of LNG vapor by raising the temperature of the vapor permeated through the foam layer and ultimately decreasing the methane concentrations in the downwind direction. It was also found that expansion foam has positive effects on reducing fire height and radiant heat fluxes by decreasing fire heat feedback to the LNG pool, thus resulting in reduction in the safe separation distance. Through the extensive data analysis, several key parameters, such as minimum effective foam depth and mass evaporation rate of LNG with foam, were identified. However, caution must be taken to ensure that foam application can result in initial adverse effects on vapor and fire control. Finally, based on these findings, several recommendations were made for improving foam delivery methods which can be used for controlling the hazard of spilled LNG.
218

Measuring the Potential to Adopt Self Governance for the Management of a Common Pool Resource

Colin Castillo, Sergio 2011 December 1900 (has links)
Self governance has proved to be a suitable instrument for the management of a common pool resource like fisheries. Under self governance, individuals organize themselves for the use of a resource, to deal with problems derived from the free access: overexploitation and low profit levels. Although there is a large amount of research devoted to investigate the common pool resources and self governance, there are two areas that represent a gap in the current research. One, what are the main variables related to likely self governance adoption? Two, how is the potential for self governance related to the economic efficiency of the resource users? Unlike most of previous research that involves ex-post analysis, this is an ex-ante assessment of the potential for self governance for management of a common pool resource: a small-scale fishery located in Mexico. This research hypothesizes a positive relationship between fisher's technical efficiency and the likely adoption of self governance for the management of the fishery. Taking a set of theoretical conditions, this research assesses the fishers' perception on the adoption of self governance. Further, a stochastic frontier analysis is applied to estimate the technical efficiency of each fisher. Finally, a relationship between the potential for self governance with technical efficiency, revenue, and other variables such as education and fisher experience is explored. The results show no significant effect of technical efficiency and revenue on the potential for self governance, as well a weak positive effect of fisher experience on the likelihood for self governance adoption. The findings of this research may be useful to improve the efficiency of the fishing activity and encourage the adoption of self governance in the study site. The method proposed in this research is based on attitudes of the fishers, and it represents a step toward understanding apriori whether self governance would be implementable or not. Thus, as an ex-ante assessment, it is hoped to help predicting individual's behavior to deal with the overexploitation and low income levels derived from the use of a common pool resource.
219

Electricity liberalization and the study of independent power plant operating

Chen, Li-Fen 21 June 2000 (has links)
Electricity Liberalization Independent Power Plant Project Finance Electricity Pool Biletral Contract
220

CFD-Calculations to a Core Catcher Benchmark

Willschütz, Hans-Georg 31 March 2010 (has links) (PDF)
There are numerous experiments for the exploration of the corium spreading behaviour, but comparable data have not been available up to now in the field of the long term behaviour of a corium expanded in a core catcher. The difficulty consists in the experimental simulation of the decay heat that can be neglected for the short-run course of events like relocation and spreading, which must, however, be considered during investigation of the long time behaviour. Therefore the German GRS, defined together with Battelle Ingenieurtechnik a benchmark problem in order to determine particular problems and differences of CFD codes simulating an expanded corium and from this, requirements for a reasonable measurement of experiments, that will be performed later. First the finite-volume-codes Comet 1.023, CFX 4.2 and CFX-TASCflow were used. To be able to make comparisons to a finite-element-code, now calculations are performed at the Institute of Safety Research at the Forschungszentrum Rossendorf with the code ANSYS/FLOTRAN.For the benchmark calculations of stage 1 a pure and liquid melt with internal heat sources was assumed uniformly distributed over the area of the planned core catcher of a EPR plant. Using the Standard-k-e-turbulence model and assuming an initial state of a motionless superheated melt several large convection rolls will establish within the melt pool. The temperatures at the surface do not sink to a solidification level due to the enhanced convection heat transfer. The temperature gradients at the surface are relatively flat while there are steep gradients at the ground where the no slip condition is applied. But even at the ground no solidification temperatures are observed. Although the problem in the ANSYS-calculations is handled two-dimensional and not three-dimensional like in the finite-volume-codes, there are no fundamental deviations to the results of the other codes.

Page generated in 0.593 seconds