In this Master Thesis, a model of a video coding system that uses the transportation plan taken from the calculation of the Kantorovich distance is developed. The coder uses the transportation plan instead of the differential image and sends it through blocks of transformation, quantization and coding. The Kantorovich distance is a rather unknown distance metric that is used in optimization theory but is also applicable on images. It can be defined as the cheapest way to transport the mass of one image into another and the cost is determined by the distance function chosen to measure distance between pixels. The transportation plan is a set of finitely many five-dimensional vectors that show exactly how the mass should be moved from the transmitting pixel to the receiving pixel in order to achieve the Kantorovich distance between the images. A vector in the transportation plan is called an arc. The original transportation plan was transformed into a new set of four-dimensional vectors called the modified difference plan. This set replaces the transmitting pixel and the receiving pixel with the distance from the transmitting pixel of the last arc and the relative distance between the receiving pixel and the transmitting pixel. The arcs where the receiving pixels are the same as the transmitting pixels are redundant and were removed. The coder completed an eleven frame sequence of size 128x128 pixels in eight to ten hours.

Previamente à cada estimativa ou simulação geoestatística os domínios geológicos do depósito devem ser modelados, o que tradicionalmente é feito de forma manual por um geomodelador, em um processo laborioso, demorado e subjetivo. Por essa razão novas técnicas conhecidas como métodos implícitos veem surgindo. Essas técnicas fornecem algoritmos que substituem o processo de digitalização manual dos métodos explícitos por alguma forma de procedimento automático. Essa dissertação visita alguns métodos implícitos bem estabelecidos com atenção especial à modelagem geológica implícita com funções distância assinalada. Um estudo de caso em um banco de dados real é apresentado e a aplicabilidade do método discutida. Embora não substitua por completo um geomodelador experiente, o método provou ser capaz de gerar modelos geológicos semi-automáticos realistas a partir dos dados amostrais, e se mostra útil principalmente nas fases iniciais da pesquisa mineral. / Prior to every geostatistical estimation or simulation study there is a need for delimiting the geologic domains of the deposit, which is traditionally done manually by a geomodeler in a laborious, time consuming and subjective process. For this reason, novel techniques referred to as implicit modelling have appeared. These techniques provide algorithms that replace the manual digitization process of the traditional methods by some form of automatic procedure. This dissertation covers a few well established implicit methods currently available with special attention to the signed distance function methodology. A case study based on a real dataset was performed and its applicability discussed. Although it did not replace an experienced geomodeler, the method proved to be capable in creating semi-automatic geological models from the sampling data, especially in the early stages of exploration.

Previamente à cada estimativa ou simulação geoestatística os domínios geológicos do depósito devem ser modelados, o que tradicionalmente é feito de forma manual por um geomodelador, em um processo laborioso, demorado e subjetivo. Por essa razão novas técnicas conhecidas como métodos implícitos veem surgindo. Essas técnicas fornecem algoritmos que substituem o processo de digitalização manual dos métodos explícitos por alguma forma de procedimento automático. Essa dissertação visita alguns métodos implícitos bem estabelecidos com atenção especial à modelagem geológica implícita com funções distância assinalada. Um estudo de caso em um banco de dados real é apresentado e a aplicabilidade do método discutida. Embora não substitua por completo um geomodelador experiente, o método provou ser capaz de gerar modelos geológicos semi-automáticos realistas a partir dos dados amostrais, e se mostra útil principalmente nas fases iniciais da pesquisa mineral. / Prior to every geostatistical estimation or simulation study there is a need for delimiting the geologic domains of the deposit, which is traditionally done manually by a geomodeler in a laborious, time consuming and subjective process. For this reason, novel techniques referred to as implicit modelling have appeared. These techniques provide algorithms that replace the manual digitization process of the traditional methods by some form of automatic procedure. This dissertation covers a few well established implicit methods currently available with special attention to the signed distance function methodology. A case study based on a real dataset was performed and its applicability discussed. Although it did not replace an experienced geomodeler, the method proved to be capable in creating semi-automatic geological models from the sampling data, especially in the early stages of exploration.

The selection of a suitable model for efficiency analysis is one of the most important issues in policy analysis. Given the recent interest in the use of distance functions as alternative representation of production technology, this study compares the empirical performances of the parametric stochastic input distance function to its nonparametric counterpart, data envelopment analysis. A further comparison is made between the alternatives of a distance and production function frontiers. It further integrates efficiency scores from the consistent approaches in order to evaluate the performance of the sampled farm households and for analysis of policy impacts on technical, allocative and cost efficiency. The usefulness of the proposed methodology is applied to smallholder maize production in Benue State Nigeria. The maize subsector has featured in a number of Nigeria’s policy initiatives, the most current of which involves doubling of its production and productivity through promotion of improved technologies such as hybrid seed, inorganic fertilizer, pesticides, herbicides, and better management practices. Despite the policy initiatives, maize productivity has remained low raising questions about the efficiency of resource use by farmers and the benefits of Nigeria’s technology policy. The study used data obtained from a field survey for the 2008/2009 agricultural year. A multistage stratified sampling technique was employed in selection of respondents. A total of 240 maize farm households were randomly selected and interviewed using structured questionnaires. Results from all the approaches indicated considerable technical, allocative and cost inefficiency under both traditional and improved maize technology. Technical efficiency estimates range from 80 to 87 percent. Allocative efficiency estimates range from 53 to 74 percent while cost efficiency estimates range from 45 to 62 percent. The results from all the approaches indicated that inefficiency in maize production in Benue State is dominated by cost inefficiency suggesting the immense potential of enhancing production through improvement in overall efficiency. The overall consistency check shows that technical, allocative and cost efficiency measures from the three distance functions were consistent whereas similar conclusions could not hold when these were compared to the production frontier especially for technical efficiency estimates. Given the consistency of results from the parametric and non-parametric distance functions, an integrated input distance model was developed for providing final efficiency estimates and analysis of policy impacts. The results show that both traditional and improved technology users were technically, allocatively and cost inefficient. The average technical, allocative and cost efficiency are 84.2, 65.7 and 54.5 percent, respectively implying that there is a possibility of raising maize production by 45.5 percent through overall efficiency improvement. Under the integrated approach, the study revealed that hybrid seeds, inorganic fertilizer and conservation practices have positive and significant impact on farm efficiency. Other determinants of efficiency include education, age, household size, land size, credit, and membership in a farmer group. The findings justify the need for further public investment in maize technology development and proper implementation of the relevant policies in order to enhance the efficiency with which maize has been produced thereby increasing its productivity, food security and farm incomes and subsequently reducing poverty in Nigeria. / Thesis (PhD)--University of Pretoria, 2011. / Agricultural Economics, Extension and Rural Development / unrestricted

L’objectif à moyen terme de ce travail est d’explorer quelques formulations des problèmes d’identification de forme et de reconnaissance de surface à partir de mesures ponctuelles. Ces problèmes ont plusieurs applications importantes dans les domaines de l’imagerie médicale, de la biométrie, de la sécurité des accès automatiques et dans l’identification de structures cohérentes lagrangiennes en mécanique des fluides. Par exemple, le problème d’identification des différentes caractéristiques de la main droite ou du visage d’une population à l’autre ou le suivi d’une chirurgie à partir des données générées par un numériseur. L’objectif de ce mémoire est de préparer le terrain en passant en revue les différents outils mathématiques disponibles pour appréhender la géométrie comme variable d’optimisation ou d’identification. Pour l’identification des surfaces, on explore l’utilisation de fonctions distance ou distance orientée, et d’ensembles de niveau comme chez S. Osher et R. Fedkiw ; pour la comparaison de surfaces, on présente les constructions des métriques de Courant par A. M. Micheletti en 1972 et le point de vue de R. Azencott et A. Trouvé en 1995 qui consistent à générer des déformations d’une surface de référence via une famille de difféomorphismes. L’accent est mis sur les fondations mathématiques sous-jacentes que l’on a essayé de clarifier lorsque nécessaire, et, le cas échéant, sur l’exploration d’autres avenues. / The mid-term objective of this work is to explore some formulations of shape identification and surface recognition problems from point measurements. Those problems have important applications in medical imaging, biometrics, security of the automatic access, and in the identification of Lagrangian Coherent Structures in Fluid Mechanics. For instance, the problem of identifying the different characteristics of the right hand or the face from a population to another or the follow-up after surgery from data generated by a scanner. The objective of this mémoire is to prepare the ground by reviewing the different mathematical tools available to apprehend the geometry as an identification or optimization variable. For surface identification it explores the use of distance functions, oriented distance functions, and level sets as in S. Osher and R. Fedkiw ; for surface recognition it emphasizes the construction of Courant metrics by A. M. Micheletti in 1972 and the point of view of R. Azencott and A. Trouvé in 1995 which consists in generating deformations of a reference surface via a family of diffeomorphisms. The accent will be put on the underlying mathematical foundations that it will attempt to clarify as necessary, and, if need be, on exploring new avenues.

L’objectif à moyen terme de ce travail est d’explorer quelques formulations des problèmes d’identification de forme et de reconnaissance de surface à partir de mesures ponctuelles. Ces problèmes ont plusieurs applications importantes dans les domaines de l’imagerie médicale, de la biométrie, de la sécurité des accès automatiques et dans l’identification de structures cohérentes lagrangiennes en mécanique des fluides. Par exemple, le problème d’identification des différentes caractéristiques de la main droite ou du visage d’une population à l’autre ou le suivi d’une chirurgie à partir des données générées par un numériseur. L’objectif de ce mémoire est de préparer le terrain en passant en revue les différents outils mathématiques disponibles pour appréhender la géométrie comme variable d’optimisation ou d’identification. Pour l’identification des surfaces, on explore l’utilisation de fonctions distance ou distance orientée, et d’ensembles de niveau comme chez S. Osher et R. Fedkiw ; pour la comparaison de surfaces, on présente les constructions des métriques de Courant par A. M. Micheletti en 1972 et le point de vue de R. Azencott et A. Trouvé en 1995 qui consistent à générer des déformations d’une surface de référence via une famille de difféomorphismes. L’accent est mis sur les fondations mathématiques sous-jacentes que l’on a essayé de clarifier lorsque nécessaire, et, le cas échéant, sur l’exploration d’autres avenues. / The mid-term objective of this work is to explore some formulations of shape identification and surface recognition problems from point measurements. Those problems have important applications in medical imaging, biometrics, security of the automatic access, and in the identification of Lagrangian Coherent Structures in Fluid Mechanics. For instance, the problem of identifying the different characteristics of the right hand or the face from a population to another or the follow-up after surgery from data generated by a scanner. The objective of this mémoire is to prepare the ground by reviewing the different mathematical tools available to apprehend the geometry as an identification or optimization variable. For surface identification it explores the use of distance functions, oriented distance functions, and level sets as in S. Osher and R. Fedkiw ; for surface recognition it emphasizes the construction of Courant metrics by A. M. Micheletti in 1972 and the point of view of R. Azencott and A. Trouvé in 1995 which consists in generating deformations of a reference surface via a family of diffeomorphisms. The accent will be put on the underlying mathematical foundations that it will attempt to clarify as necessary, and, if need be, on exploring new avenues.

This dissertation examines to what extent off-farm diversification may be an appropriate and accessible tool to mitigate the adverse effects from market failures and incompleteness in the crop and farm income insurance market. While the influence of the nonfarm sector has long been recognized as a primary force in shaping farm structure, off-farm income is rarely acknowledge as a risk management tool for operators and households of commercial farms. The dissertation develops a dynamic model that includes capital market imperfections, economies of scale in farm production, and the presence of adjustment costs in labor allocation decisions. The model provides a realistic characterization of the environment defining income and financial risks faced by farm operators, as well as the risk management alternatives available to them. It is found that introducing off-farm labor can substantially mitigate the adverse effects of farm income risk on farm operators' and households' welfare, even for larger commercial farms. However, the diversification of labor by the main operator seems to impose labor and managerial constraints that can reduce the intensity and technical efficiency of the farm production. Alternatively, diversification at the household level through the allocation of spousal labor off the farm provides benefits in mitigating the adverse effects of farm income risk on farm production and efficiency, and on operators and households welfare. It thus provides an efficient risk management alternative that is consistent with most rationales that are invoked to justify farm policies. Results suggest that the increasing incidence and importance of off-farm income within the farm population of most OECD countries is highly relevant in the design of effective farm policies This form of diversification can reduce the need and effectiveness of farm income stabilization polices. While it has been argued elsewhere that broader economic policies had a large influence in closing the income gap between farm and urban households, such policies may also have a role to play in addressing farm income risk issues and, in some cases, may represent more sustainable and efficient policy alternatives.

This thesis employs a parametric input distance function that incorporates both desirable and undesirable outputs to provide a more complete representation of the production technology. Based on the Shephard (1970) theory of duality, we derive the shadow prices of undesirable outputs in the Czech energy sector on the data over the period 2002 - 2007. The medians of our shadow prices estimates are 8374, 1198, 2805, 6051 and 8549 € per ton of PM, SO2, NOx, CO and VOC, respectively. We decompose shadow prices estimates and test the hypotheses that the marginal abatement cost decline over time; that marginal abatement cost rice with the declining emission level; and that marginal abatement cost rice with declining emission rate. Key Words: shadow prices, distance function, undesirable outputs, marginal abatement cost JEL classification: C61, D24, Q53

This thesis investigates three major aspects of energy consumption rebound effects (RE) in three papers. More specifically, the issues addressed are (i) the magnitude of economy-wide rebound effect (ii) the role of energy policy instruments in mitigating it and (iii) its channels of impact. The research begins with the estimation of cross-country economy-wide rebound effects for a panel of 55 countries over the period 1980 to 2010. A two-stage approach is utilized in which energy efficiency is first estimated from a stochastic input distance frontier (SIDF). The estimated energy efficiency is then used in a second stage dynamic panel model to derive short-run and long-run RE for an array of developing and developed countries. The cross-country point estimates indicate substantial RE magnitudes across sampled countries during the period under consideration, although a positive and encouraging finding is the declining RE trend across most of the sampled countries during the study period. The second paper contains an RE benchmark for 19 EU countries, as well as an investigation of the effects of two energy policy instruments (energy taxes and ener-gy R&D) on RE performance over the period 1995 to 2010. The results indicate that RE performance improved over the sample period, reinforcing the results from paper one. In addition, there is also some evidence suggesting that binding market-based instruments such as energy taxes have been more effective in restricting RE than in-direct instruments such as energy R&D during the period under consideration. This is consistent across both estimated model specifications. An important observation from the first essay is the slightly larger average RE across the non-OECD countries. For this reason, the last empirical chapter evaluated the channels through which RE stimulated energy use across productive sectors of major developing/emerging economies, namely Brazil, Russia, India, Indonesia and China. To achieve this, the essay relied on duality theory to decompose changes in energy demand into substitution and output effects through the estimation of a trans-log cost function using data spanning 1995-2009. Findings reveal that energy use elasticities across sampled sectors/countries are dominated by substitution effects. One intriguing result that also emerges from this analysis is the role of economies of scale and factor accumulation, rather than technical progress, in giving rise to eco-nomic growth and energy consumption in these countries during the period under consideration.

This thesis consists of five papers, four of them basically concerning environmental issues, while the fifth paper addresses the issue of measuring output from the educational sector. The first paper starts from the fact that industrial activity causes environmental damage. Therefore, public authorities are called upon to regulate the behavior of producers by, e.g., legislating maximally allowed emission levels, which give rise to abatement costs. In this paper, marginal abatement costs (MACs) are estimated and a procedure to empirically analyze why MACs may vary between producers is suggested. The main focus is on whether the MACs in the Swedish pulp industry reveal that differences between counties in, e.g., economical characteristics, were influential when the authority, during 1983-1990, restricted 12 geographically scattered plants regarding emissions. The result indicates that county differences were influential. The second paper analyses and suggests a procedure for testing the Porter hypothesis. Part of this hypothesis is based on the argument that increased environmental stringency not only brings a cleaner environment, but also makes the polluting producers aware of the opportunity of using resources more efficiently. The particular test suggested considers whether there is a positive correlation between producers’ technical output efficiency and environmental stringency, approximated by a regulatory intensity index. It is empirically applied on 12 Swedish pulp plants during 1983-1990. No support for the Porter hypothesis is found in this particular case. The third paper deals with the climate policy issue. Under the Kyoto Protocol, the European Union agreed to reduce its emission of greenhouse gases by 8 percent in comparison with the level in 1990. The Burden-Sharing Agreement (BSA) further redistributes the 8 percent reduction target among the member states. This paper evaluates the BSA both from an economical and a political perspective, i.e., whether cost-efficiency and equity, respectively, were considered when the BSA was settled. The empirical result indicates that both efficiency and equity were considered as important to the BSA. The fourth paper evaluates the Swedish Producer Responsibility Ordinance (PRO), fully implemented in 1994, which states that sorted out, domestically collected waste paper, must be recycled by the paper industry and, therefore, cannot be incinerated by the heating industry in purpose of recovering energy. The result indicates that this policy has contributed to inefficient waste paper allocation among some of the paper producers. The result further indicates that the priority made by the PRO, i.e., that waste paper recycling is preferable to incineration, should be reconsidered. The fifth paper relates the empirical attempts of measuring output from the educational sector to theoretical results about the welfare significance of a comprehensive Net National Product (NNP) measure. It is shown that economic theory provides a more focused way of interpreting such output estimates. The paper also contains estimates of the output from the Swedish educational sector. Among the results, it is shown that the private gross output value produced by higher education is approximately 2 percent of GDP. Furthermore, the private rate of return on investments in higher education in Sweden is calculated to 8.6 percent.