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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.
21

Techno-economic modelling of CO2 capture systems for Australian industrial sources.

Ho, Minh Trang Thi, Chemical Sciences & Engineering, Faculty of Engineering, UNSW January 2007 (has links)
Australia is recognising that carbon capture and storage (CCS) may be a feasible pathway for addressing increasing levels of CO2 emissions. This thesis presents a preliminary economic assessment and comparison of the capture costs for different Australian CO2 emission sources. The capture technologies evaluated include solvent absorption, pressure swing adsorption (PSA), gas separation membranes and low temperature separation. The capture cost estimated for hydrogen production, IGCC power plants and natural gas processing is less than A$30/tonne CO2 avoided. CO2 capture cost for iron production ranges from A$30 to A$40 per tonne CO2 avoided. Higher costs of A$40 to over A$80 per tonne CO2 avoided were estimated for flue gas streams from pulverised coal and NGCC power plants, oil refineries and cement facilities, and IDGCC synthesis gas. Based on 2004 and 2005 EU ETS carbon prices (A$30 to A$45 per tonne CO2 avoided), the cost of capture using current commercially available absorption technology may deter wide-scale implementation of CCS, in particular for combustion processes. A sensitivity analysis was undertaken to explore the opportunities for reducing costs. The high cost for capture using solvent absorption is dependent on the energy needed for solvent regeneration and the high capital costs. Cost reductions can be achieved by using new low regeneration energy solvents coupled with recycling the waste heat from the absorption process back to the steam cycle, and using low cost ???fit-for-purpose??? equipment. For membrane and PSA technologies, the capture costs are dominated by the flue gas and post-capture compressors. Operating the permeate or desorption stream under vacuum conditions provides significant cost reductions. Improvements in membrane and adsorbent characteristics such as the adsorbent loading or membrane permeability, CO2 selectivity, and lower prices for the membrane or adsorbent material provide further cost benefits. For low partial pressure CO2 streams, capture using low temperature ???anti-sublimation??? separation can be an alternative option. Low costs could be achieved by operating under low pressures and integrating with external sources of waste heat. Applying the cost reductions achievable with technology and process improvements reduces the capture and CCS costs to a level less than current carbon prices, making CCS an attractive mitigation option.
22

Wireless optimisation based on economic criteria.

Hew, Siew Lee January 2007 (has links)
The rapid growth in demand due to the emergence of mobile communication services with variable rates, coupled with the resource scarcity of mobile air interface, has encouraged researchers to find technological solutions to increase spectral efficiency in order to support different levels of Quality of Service (QoS). Radio resource management (RRM) plays a major role in QoS provisioning and congestion control for wireless networks. The main problem with the congestion control mechanisms provided by current RRM schemes is that they are mostly reactive, triggered only when congestion occurs. The common, traditional solution to congestion has been for system planners to over-engineer a network by assigning more resources than are necessary. This approach is very costly because busy periods are usually brief, causing the network to be often under-utilised outside of these periods. Current static, usage-based pricing models also fail to assist in traffic shaping to even out loads. Economic modelling offers a new perspective into current RRM schemes and enables efficient utilisation of scarce resources and congestion prevention based on concepts such as utility, price, Pareto optimality and game theory. Dynamic pricing has been proposed as a mechanism to encourage users to adapt their resource consumption level according to network conditions. A good pricing model can provide the necessary positive incentives to increase users’ arrival rate when the network load is relatively low and negative incentives for users to defer their usage when the load is relatively high. In this dissertation, we propose an economic framework for pricing and RRM for 3G and beyond systems. Our aim is two-fold: to calculate an optimal integrated dynamic pricing and RRM policy; and to allocate scarce network resources in a fair and Pareto-optimal manner. The optimal integrated dynamic pricing and RRM policy is computed based on the stochastic distribution of users’ budget, arrivals, handoffs and departures. Our results show that the integrated policy is superior in terms of average reward improvement and congestion prevention to current schemes that use static pricing models. In interferencebased networks such as WCDMA, we suggest users be charged according to their noise rise factor, i.e. an estimate of the amount of interference generated by the call. This interference-based pricing model improves on the conventional load-based model in by delivering higher revenue and lower call blocking and handoff probabilities. Using the axiomatic bargaining concepts from cooperative game theory, we derive a class of fair and Pareto-optimal bargaining solutions that allocate wireless resources based on users’ minimum and maximum rate requirements. We propose two models: symmetric and asymmetric. In the latter, resource is allocated according to the price paid by the users. An important significance of the asymmetric bargaining model is that this solution is still Pareto-optimal and fair according to the users’ bargaining power. Our approach is also a departure from current works using noncooperative game theory that can only achieve an inefficient outcome, i.e. the Nash equilibrium; or cooperative game theory that focus on only one solution on the Pareto-optimal boundary. By analysing a range of bargaining solutions instead of specific ones, operators can proceed to select the best outcome out of these Pareto-optimal solutions based on criteria like revenue. / Thesis (Ph.D) -- University of Adelaide, School of Electrical and Electronic Engineering, 2007
23

Techno-economic modelling of CO2 capture systems for Australian industrial sources.

Ho, Minh Trang Thi, Chemical Sciences & Engineering, Faculty of Engineering, UNSW January 2007 (has links)
Australia is recognising that carbon capture and storage (CCS) may be a feasible pathway for addressing increasing levels of CO2 emissions. This thesis presents a preliminary economic assessment and comparison of the capture costs for different Australian CO2 emission sources. The capture technologies evaluated include solvent absorption, pressure swing adsorption (PSA), gas separation membranes and low temperature separation. The capture cost estimated for hydrogen production, IGCC power plants and natural gas processing is less than A$30/tonne CO2 avoided. CO2 capture cost for iron production ranges from A$30 to A$40 per tonne CO2 avoided. Higher costs of A$40 to over A$80 per tonne CO2 avoided were estimated for flue gas streams from pulverised coal and NGCC power plants, oil refineries and cement facilities, and IDGCC synthesis gas. Based on 2004 and 2005 EU ETS carbon prices (A$30 to A$45 per tonne CO2 avoided), the cost of capture using current commercially available absorption technology may deter wide-scale implementation of CCS, in particular for combustion processes. A sensitivity analysis was undertaken to explore the opportunities for reducing costs. The high cost for capture using solvent absorption is dependent on the energy needed for solvent regeneration and the high capital costs. Cost reductions can be achieved by using new low regeneration energy solvents coupled with recycling the waste heat from the absorption process back to the steam cycle, and using low cost ???fit-for-purpose??? equipment. For membrane and PSA technologies, the capture costs are dominated by the flue gas and post-capture compressors. Operating the permeate or desorption stream under vacuum conditions provides significant cost reductions. Improvements in membrane and adsorbent characteristics such as the adsorbent loading or membrane permeability, CO2 selectivity, and lower prices for the membrane or adsorbent material provide further cost benefits. For low partial pressure CO2 streams, capture using low temperature ???anti-sublimation??? separation can be an alternative option. Low costs could be achieved by operating under low pressures and integrating with external sources of waste heat. Applying the cost reductions achievable with technology and process improvements reduces the capture and CCS costs to a level less than current carbon prices, making CCS an attractive mitigation option.
24

Economic modelling using computational intelligence techniques

Khoza, Msizi Smiso 09 December 2013 (has links)
M.Ing. ( Electrical & Electronic Engineering Science) / Economic modelling tools have gained popularity in recent years due to the increasing need for greater knowledge to assist policy makers and economists. A number of computational intelligence approaches have been proposed for economic modelling. Most of these approaches focus on the accuracy of prediction and not much research has been allocated to investigate the interpretability of the decisions derived from these systems. This work proposes the use of computational intelligence techniques (Rough set theory (RST) and the Multi-layer perceptron (MLP) model) to model the South African economy. RST is a rule-based technique suitable for analysing vague, uncertain and imprecise data. RST extracts rules from the data to model the system. These rules are used for prediction and interpreting the decision process. The lesser the number of rules, the easier it is to interpret the model. The performance of the RST is dependent on the discretization technique employed. An equal frequency bin (EFB), Boolean reasoning (BR), entropy partition (EP) and the Naïve algorithm (NA) are used to develop an RST model. The model trained using EFB data performs better than the models trained using BR and EP. RST was used to model South Africa’s financial sector. Here, accuracy of 86.8%, 57.7%, 64.5% and 43% were achieved for EFB, BR, EP and NA respectively. This work also proposes an ensemble of rough set theory and the multi-layer perceptron model to model the South African economy wherein, a prediction of the direction of the gross domestic product is presented. This work also proposes the use of an auto-associative Neural Network to impute missing economic data. The auto-associative neural network imputed the ten variables or attributes that were used in the prediction model. These variables were: Construction contractors rating lack of skilled labour as constraint, Tertiary economic sector contribution to GDP, Income velocity of circulation of money, Total manufacturing production volume, Manufacturing firms rating lack of skilled labour as constraint, Total asset value of banking industry, Nominal unit labour cost, Total mass of Platinum Group Metals (PGMs) mined, Total revenue from sale of PGMs and the Gross Domestic Expenditure (GDE). The level of imputation accuracy achieved varied with the attribute. The accuracy ranged from 85.9% to 98.7%.
25

Provision of environmental goods on private land: a case study of Australian wetlands

Whitten, Stuart Max, Business, Australian Defence Force Academy, UNSW January 2003 (has links)
The management of natural resources located on private lands often involves a perceived conflict between the mix of private and public benefit outputs they produce. Governments have tended to respond through legislation to restrict and redirect private decisions about resource management. However, the legislative response faces a lack of information about the costs and benefits of alternative management and policy instruments. A pertinent example of this debate is the management of wetlands on private lands. The goal in this thesis is to advance the design of policy relating to the production of environmental outputs on private lands. This goal is achieved by first estimating the welfare impacts of alternative private land management strategies on the wider community. These estimates are used as inputs into the development of alternative policy instruments that are then evaluated in terms of their potential cost-effectiveness in influencing private management. Two case studies of wetland management on private land in Australia are presented ??? the Upper South East Region of South Australia, and, the Murrumbidgee River Floodplain in New South Wales. The conceptual approach described in the first part of the thesis includes a description of the resource management problem and the strengths and weaknesses of the alternative decision frameworks widely employed in Australia. Identification of the cause and nature of transaction costs in the management process is the focus in this discussion. The welfare impacts of alternative wetland management strategies are investigated through the construction of a bio-economic model for each of the case study areas. The approach integrates biophysical analysis of changing wetland management with the value society places on wetlands. Outputs from this process are used in the development of a range of policy instruments directed towards influencing wetland management. The impact of poorly quantified and uncertain transaction costs on the potential cost-effectiveness of these options is evaluated using threshold policy analysis. The empirical results show that the perception of a conflict between the private and public values generated by resource management is accurate. For example, scenarios changing wetland management in the Upper South East of South Australia on the Murrumbidgee River floodplain in New South Wales were shown to generate net benefits of $5.2m and $5.1m respectively. Hence, changing wetland management could generate increased community welfare. The potential for these findings to be translated into wetland policy is less conclusive. Policies directed towards wetland management (in part or in whole) incur a range of transaction costs and deliver differential wetland protection benefits. Ten ???best bet??? policies are identified, but more information is required to determine conclusively whether a net benefit results to the wider community when transaction costs are included.
26

Provision of environmental goods on private land: a case study of Australian wetlands

Whitten, Stuart Max, Business, Australian Defence Force Academy, UNSW January 2003 (has links)
The management of natural resources located on private lands often involves a perceived conflict between the mix of private and public benefit outputs they produce. Governments have tended to respond through legislation to restrict and redirect private decisions about resource management. However, the legislative response faces a lack of information about the costs and benefits of alternative management and policy instruments. A pertinent example of this debate is the management of wetlands on private lands. The goal in this thesis is to advance the design of policy relating to the production of environmental outputs on private lands. This goal is achieved by first estimating the welfare impacts of alternative private land management strategies on the wider community. These estimates are used as inputs into the development of alternative policy instruments that are then evaluated in terms of their potential cost-effectiveness in influencing private management. Two case studies of wetland management on private land in Australia are presented ??? the Upper South East Region of South Australia, and, the Murrumbidgee River Floodplain in New South Wales. The conceptual approach described in the first part of the thesis includes a description of the resource management problem and the strengths and weaknesses of the alternative decision frameworks widely employed in Australia. Identification of the cause and nature of transaction costs in the management process is the focus in this discussion. The welfare impacts of alternative wetland management strategies are investigated through the construction of a bio-economic model for each of the case study areas. The approach integrates biophysical analysis of changing wetland management with the value society places on wetlands. Outputs from this process are used in the development of a range of policy instruments directed towards influencing wetland management. The impact of poorly quantified and uncertain transaction costs on the potential cost-effectiveness of these options is evaluated using threshold policy analysis. The empirical results show that the perception of a conflict between the private and public values generated by resource management is accurate. For example, scenarios changing wetland management in the Upper South East of South Australia on the Murrumbidgee River floodplain in New South Wales were shown to generate net benefits of $5.2m and $5.1m respectively. Hence, changing wetland management could generate increased community welfare. The potential for these findings to be translated into wetland policy is less conclusive. Policies directed towards wetland management (in part or in whole) incur a range of transaction costs and deliver differential wetland protection benefits. Ten ???best bet??? policies are identified, but more information is required to determine conclusively whether a net benefit results to the wider community when transaction costs are included.
27

Provision of environmental goods on private land: a case study of Australian wetlands

Whitten, Stuart Max, Business, Australian Defence Force Academy, UNSW January 2003 (has links)
The management of natural resources located on private lands often involves a perceived conflict between the mix of private and public benefit outputs they produce. Governments have tended to respond through legislation to restrict and redirect private decisions about resource management. However, the legislative response faces a lack of information about the costs and benefits of alternative management and policy instruments. A pertinent example of this debate is the management of wetlands on private lands. The goal in this thesis is to advance the design of policy relating to the production of environmental outputs on private lands. This goal is achieved by first estimating the welfare impacts of alternative private land management strategies on the wider community. These estimates are used as inputs into the development of alternative policy instruments that are then evaluated in terms of their potential cost-effectiveness in influencing private management. Two case studies of wetland management on private land in Australia are presented ??? the Upper South East Region of South Australia, and, the Murrumbidgee River Floodplain in New South Wales. The conceptual approach described in the first part of the thesis includes a description of the resource management problem and the strengths and weaknesses of the alternative decision frameworks widely employed in Australia. Identification of the cause and nature of transaction costs in the management process is the focus in this discussion. The welfare impacts of alternative wetland management strategies are investigated through the construction of a bio-economic model for each of the case study areas. The approach integrates biophysical analysis of changing wetland management with the value society places on wetlands. Outputs from this process are used in the development of a range of policy instruments directed towards influencing wetland management. The impact of poorly quantified and uncertain transaction costs on the potential cost-effectiveness of these options is evaluated using threshold policy analysis. The empirical results show that the perception of a conflict between the private and public values generated by resource management is accurate. For example, scenarios changing wetland management in the Upper South East of South Australia on the Murrumbidgee River floodplain in New South Wales were shown to generate net benefits of $5.2m and $5.1m respectively. Hence, changing wetland management could generate increased community welfare. The potential for these findings to be translated into wetland policy is less conclusive. Policies directed towards wetland management (in part or in whole) incur a range of transaction costs and deliver differential wetland protection benefits. Ten ???best bet??? policies are identified, but more information is required to determine conclusively whether a net benefit results to the wider community when transaction costs are included.
28

Provision of environmental goods on private land: a case study of Australian wetlands

Whitten, Stuart Max, Business, Australian Defence Force Academy, UNSW January 2003 (has links)
The management of natural resources located on private lands often involves a perceived conflict between the mix of private and public benefit outputs they produce. Governments have tended to respond through legislation to restrict and redirect private decisions about resource management. However, the legislative response faces a lack of information about the costs and benefits of alternative management and policy instruments. A pertinent example of this debate is the management of wetlands on private lands. The goal in this thesis is to advance the design of policy relating to the production of environmental outputs on private lands. This goal is achieved by first estimating the welfare impacts of alternative private land management strategies on the wider community. These estimates are used as inputs into the development of alternative policy instruments that are then evaluated in terms of their potential cost-effectiveness in influencing private management. Two case studies of wetland management on private land in Australia are presented ??? the Upper South East Region of South Australia, and, the Murrumbidgee River Floodplain in New South Wales. The conceptual approach described in the first part of the thesis includes a description of the resource management problem and the strengths and weaknesses of the alternative decision frameworks widely employed in Australia. Identification of the cause and nature of transaction costs in the management process is the focus in this discussion. The welfare impacts of alternative wetland management strategies are investigated through the construction of a bio-economic model for each of the case study areas. The approach integrates biophysical analysis of changing wetland management with the value society places on wetlands. Outputs from this process are used in the development of a range of policy instruments directed towards influencing wetland management. The impact of poorly quantified and uncertain transaction costs on the potential cost-effectiveness of these options is evaluated using threshold policy analysis. The empirical results show that the perception of a conflict between the private and public values generated by resource management is accurate. For example, scenarios changing wetland management in the Upper South East of South Australia on the Murrumbidgee River floodplain in New South Wales were shown to generate net benefits of $5.2m and $5.1m respectively. Hence, changing wetland management could generate increased community welfare. The potential for these findings to be translated into wetland policy is less conclusive. Policies directed towards wetland management (in part or in whole) incur a range of transaction costs and deliver differential wetland protection benefits. Ten ???best bet??? policies are identified, but more information is required to determine conclusively whether a net benefit results to the wider community when transaction costs are included.
29

A Spatially Explicit Agent-Based Model of Human-Resource Interaction on Easter Island / En rumsligt explicit agentbaserad modell av interaktionen mellan människor och resurser på Påskön

Steiglechner, Peter January 2020 (has links)
The history of Easter Island, with its cultural and ecological mysteries, has attracted the interests of archaeologists, anthropologists, ecologists, and economists alike. Despite the great scientific efforts, uncertainties in the available archaeological and palynological data leave a number of critical issues unsolved and open to debate. The maximum size reached by the human population before the arrival of Europeans and the temporal dynamics of deforestation are some of the aspects still fraught with controversies. By providing a quantitative workbench for testing hypotheses and scenarios, mathematical models are a valuable complement to the observational-based approaches generally used to reconstruct the history of the island. Previous modelling studies, however, have shown a number of shortcomings in the case of Easter Island, especially when they take no account of the stochastic nature of population growth in a temporally and spatially varying environment. Here, I present a new stochastic, Agent-Based Model characterised by (1) realistic physical geography of the island and other environmental constraints (2) individual agent decision-making processes, (3) non-ergodicity of agent behaviour and environment, and (4) randomised agent-environment interactions. I use the model and the best available data to determine plausible spatial and temporal patterns of deforestation and other socioecological features of Easter Island prior to the European contact. I further identify some non-trivial connections between microscopic decisions or constraints (like local confinement of agents' actions or their adaptation strategy to environmental degradation) and macroscopic behaviour of the system that can not easily be neglected in a discussion about the history of Easter Island before European contact. / Påsköns historia har, med dess kulturella och ekologiska mysterier, väckt intressen hos arkeologer, antropologer, ekologer och ekonomer. Trots de stora vetenskapliga ansträngningarna lämnar osäkerheten i de tillgängliga arkeologiska och palynologiska data ett antal kritiska frågor olösta och öppna för debatt. Den maximala storleken som den mänskliga befolkningen nådde före européernas ankomst, och avskogningens tidsmässiga dynamik, är några av de aspekter som fortfarande är fyllda med kontroverser. Genom att tillhandahålla en kvantitativ arbetsbänk för att testa hypoteser och scenarier är matematiska modeller ett värdefullt komplement till de observationsbaserade metoder som vanligtvis används för att rekonstruera öns historia. Tidigare modelleringsstudier har emellertid visat ett antal brister i fallet med Påskön, särskilt när de inte tar hänsyn till den stokastiska karaktären av befolkningsökningen i en tillfällig och rumsligt varierande miljö. Här presenters en ny stokastisk, agentbaserad modell som kännetecknas av (1) realistisk fysisk geografi av ön och andra miljömässiga begränsningar, (2) individuella beslutsprocesser av agenter, (3) icke-ergodicitet av agentens beteende och miljö och (4) randomiserade agent-miljöinteraktioner. Modellen används tillsammans med de bästa tillgängliga data för att bestämma rimliga rumsliga och temporära mönster av avskogning och andra socioekologiska egenskaper på Påskön före européers ankoms. Vidare identifieras några icke-triviala förbindelser mellan mikroskopiska beslut eller begränsningar (till exempel lokal inneslutning av agentens handlingar eller deras anpassningsstrategi till miljöförstöring) och makroskopiskt beteende hos systemet som inte lätt kan försummas i en diskussion om påsköns historia före europeisk kontakt.
30

Investissement direct étranger et tourisme international / Foreign direct investment and international tourism

Bourdarias-Pham, Vân 06 June 2016 (has links)
Cette étude porte sur l’investissement direct étranger et le tourisme international. Il s’agit d’une étude simultanée sur la demande touristique internationale à la fois en termes d’arrivées et de recettes ; ces éléments n’ont fait l’objet que de peu de travaux antérieurs, en raison de la spécificité du tourisme et les lacunes des données statistiques. Ce travail comporte deux parties. La première partie est divisée en deux chapitres. Le premier chapitre présente une analyse économique des IDE, y compris le secteur du tourisme et du tourisme international. Dans le deuxième chapitre, les principaux déterminants de l’IDE et du secteur touristique sont étudiés. La deuxième partie concerne les applications économétriques et le classement typologique des déterminants des IDE ; elle comporte deux chapitres. Dans le premier chapitre, les données statistiques, la méthodologie concernant les statistiques descriptives, et les modèles économétriques sont étudiés afin de démontrer le lien d’interdépendance et d’interaction. Le deuxième chapitre est consacré à l’analyse des tests des pays concernés. L’association des résultats des tests économétriques avec une étude de la monographie de chaque pays, permet d’établir un classement des déterminants d’IDE à destination touristique. / This work focuses on foreign direct investment and international tourism. It is a simultaneous study in tourism demand international both in terms of arrivals and revenue; These elements have been little the subject of earlier work, due to the specificity of tourism and the shortcomings of statistical data. This work consists of two parts. The first is divided into two chapters. In the first chapter, it comes to the economic analysis of the IDE, including the sector of tourism and international tourism. In the second chapter, the main determinants of FDI and tourism are studied. The second part concerns the econometric applications and the classification of the typology of the determinants of FDI; it includes two chapters. In the first chapter, statistical data, the methodology for descriptive statistics and econometric models are studied in order to demonstrate the link of interdependence and the relationship of interaction. The second chapter is devoted to the analysis of tests of the countries concerned. By combining the results of econometric tests, a study of the product monograph of each country, it is permitted to establish a ranking of the determinants of FDI to tourist destination.

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