Expanding product variety and high customer service provision are both major challenges for manufacturers to compete in the global operating environment. In addition to reduce cost and response customers¡¦ needs quickly, redesigning products and processes so as to delay the point of product differentiation is becoming an emerging means to meet these challenges. Consequently, this is the concept of postponement. The principle of postponement calls for redesigning products and processes so that the stages of the production process in which a common process is used are prolonged. Once orders are received, manufacturers finish the final operation to address the demands of mass customization. However, the product / process redesign will produce additional costs and the trade-off between costs will make enterprises hesitate to change the points of differentiation. Moreover, when the outside conditions change, the framework of total costs also changes and the operating decisions must be reconsidered again. In this paper, we develop a simple model that captures the costs and benefits associated with the redesign strategy in various scenarios. We apply this model to discuss the following three key questions: (1). In each scenario, where is the point of differentiation in the production process¡H (2). How should a firm design its processes to lower the total cost when changing is impossible or too costly in the fast changing environment¡H (3). If an agile firm can change its mode of production to respond to the ever changing environment, how should it adjust the pattern of postponement to lower the total cost¡H Since there are wide varieties of postponement, we focus our model to analyze two different product / process redesign approaches, namely, standardization and modular design, that are motivated by many real examples. We also compare these two approaches in all respects to provide more explicit principles and directions for enterprises. Finally, we draw the following conclusions. First, in determining the stage at which the point of differentiation should occur, the key variables are the investment cost per operation and the additional cost, including the processing cost and inventory holding cost, that are resulted from postponement. The trade-off between those variables will determine the optimal postponement strategy. In the case when outside condition is unfavorable for firms, it may not be advisable to apply the principle of postponement. On the hand, when the condition is beneficial, postponement is a better choice.

Emerging technologies and business models have contributed to the improvement of transportation systems and services towards a more sustainable approach to mobility. Shared mobility has become widespread as a viable solution to the increasing demand for transportation. Many cities worldwide have implemented shared mobility service and demonstrated that it could offer numerous environmental and operational benefits. However, their implementation in rural and suburban areas that feature lower population density and dispersed travel demand is not receiving the same attention. This research considers four suburban communities to evaluate the operation of a fleet of shared mobility as a potential substitute for the currently fix-route public transportation services. For each area, four scenarios were defined to consider different powertrain technologies. These scenarios include the Internal Combustion Engine, Battery Electric, and two Autonomous Electric Vehicles scenarios. While assessing the efficiency of the fleet composition system, four vehicle sizes are considered. Further, an optimized routing solution for serving the known travel demand is utilized to calculate the total cost of fleet ownership, which accounts for the purchase price, energy consumption, CO2, and driver labour costs. The results highlight potential benefits of adopting a fleet of shared Autonomous Electric Vehicles for the case studies and show approximately 67-68% and 69-70% savings compared to a shared fleet of conventional and Battery Electric vehicles, respectively, mainly due to the omission of the driver costs. In the absence of operationally safe Autonomous Electric Vehicles, the more conservative scenario of employing a fleet of shared Autonomous Electric Vehicles with the presence of safety attendants could result in 6-8% and 13-14% savings compared to a shared fleet of conventional and Battery Electric vehicles. Nevertheless, the results indicate low utilization rates for the fleet attributed to the inconsistency in demand throughout the day. The results provided in this research can inform policymakers and service providers and be used for further evaluations of such transportation services. / Thesis / Master of Applied Science (MASc) / In pursuit of more equitable, sustainable, and connected transportation services in rural and suburban areas, this research investigates the quantitative benefits and costs of operating a ride-sharing service for four suburban areas located in Hamilton, Ontario. The study considers and compares several options in vehicle sizes and technologies to provide a better ground of knowledge for service providers and policymakers.

<p> Codes with a tree structure find wide use in data compression and error correction. It is generally impractical to view and weigh all the branches in a code tree, so a search algorithm is employed which considers some but not others in a predetermined fashion. Traditionally, the efficiency of code tree search algorithms has been measured by the number of tree branches visited for a given level of performance. This measure does not indicate the true consumption of resources. Cost functions are defined based on the number of code tree paths retained, S, the length of the paths, L, and the number of code tree branches searched per branch released as output, E[C]. Using these cost functions, most of the existing algorithms as well as some new algorithms proposed here are compared.</p> <p> These new algorithms include three metric-first algorithms. The first one, the merge algorithm, uses, in addition to the main list used by the stack algorithm, an auxiliary list to store paths. The merge algorithm reduces the dependence on S for the product resource cost from O(S^2) for the stack algorithm to O(S^4/3 ) for the merge algorithm. A generalization of this algorithm reduces the product cost to O(S log S). The second algorithm uses a class of height-balanced trees, known as AVL trees, to store code tree paths, resulting in an alternate method to the merge algorithm achieving O(S log S) cost.</p> <p> The third algorithm, using the concepts of dynamic hashing and trie searching, provides important modifications to the Jelinek bucket algorithm by incorporating dynamic splitting and merging of buckets. This strategy provides a balanced data structure and reduces the product cost still further compared to the first two algorithms.</p> <p> We next turn to analysis of the number of nodes visited during a search. Using the theory of multitype branching processes in random environments an equation for node computation is derived for asymmetric source coding by the single stack algorithm. This equation is shown to be the stochastic analog of an equation for symmetric sources. Simulation results, obtained by encoding the Hamming source by the single stack algorithm, are used to optimize the performance of the algorithm with respect to the bias factor, stack length, and limit on computation. A modification to the algorithm that raises the barrier during forward motion provides a better distortion performance.</p> <p> The metric-first stack algorithm is used to encode a voiced speech sound. From experimental evidence, it is shown how to optimize the algorithm's SNR performance with respect to the algorithm's storage, execution time, and node computation. For each of these, the optimal parameterizing of the algorithm differs markedly. Similarities are pointed out between the results for speech and earlier theoretical results for the binary i.i.d. source with Hamming distortion measure. It is shown that metric-first algorithms may perform better with "real life" sources like speech than they do with artificial sources, and in view of this the algorithms proposed here take on added significance.</p> / Thesis / Doctor of Philosophy (PhD)

O hidrogênio molecular (H2) é um gás muito útil nas indústrias químicas e petroquímicas por conta de sua facilidade de reação com outros elementos químicos. Nas refinarias é o principal insumo no processo de remoção do enxofre de diversos combustíveis como a gasolina e óleo diesel, tendo sua demanda aumentada por conta de novas legislações ambientalmente mais restritivas. O hidrogênio é normalmente encontrado na natureza associado a outros elementos químicos, como a água ou os hidrocarbonetos, sendo necessária a aplicação de processos específicos para sua obtenção. Considerada a rota mais econômica para a produção de hidrogênio, o processo de reforma a vapor do gás natural é avaliado pela aplicação da metodologia de análise exergética e termoeconômica, a fim de determinar a eficiência exergética do processo e o custo de produção do hidrogênio. Este custo de produção é muito sensível ao custo do gás natural, fato que pode prejudicar a competitividade desta rota de produção e, consequentemente, abrir a possibilidade de investir na produção de hidrogênio através de tecnologias alternativas. A unidade de geração de hidrogênio estudada está presente em uma das refinarias da Petrobras e sua produção destina-se à remoção do enxofre presente no óleo diesel. Uma planta síntese do processo foi elaborada e as eficiências exergéticas dos componentes foram determinadas. Em seguida, foi realizada uma análise econômica para determinar o custo de construção, operação e manutenção da planta. Com base nos resultados obtidos, aplicou-se a metodologia de análise termoeconômica para determinar o custo de produção de hidrogênio. Dois tipos de custo foram determinados, o custo atual (ou atualizado) de produção, que indica o custo corrente (2010) do produto, e o custo nivelado, que leva em consideração a produção total prevista ao longo vida útil da planta. Para um custo de gás natural igual a 9,11 US$/GJ, o custo de produção do hidrogênio em base exergética foi igual a 17,36 US$/GJ (2.093,13 US$/t) para o valor atual e 25,35 US$/GJ (3.056,97 US$/t) para o valor nivelado. Por fim, estes valores são comparados com outros custos de produção de hidrogênio presentes na literatura. / Pure hydrogen (H2) is an useful gas in chemical and petrochemical industries because it reacts easily with several other elements. On refineries, hydrogen is used to sequestrate sulphur from diesel and gasoline. Emission restrictions regard to fossil fuels are rising the world hydrogen demands. In spite of its abundance, hydrogen is normally found associated with other chemical species like water or hidrocarbons like methane or butane. Some especific processes are required to obtain pure hydrogen. Considered the most economic production route, the natural gas reforming process is analyzed by exergetic and thermoeconomic methods in order to determine the efficiencies and the hydrogen production cost. The hydrogen production cost is very sensitive to the cost of natural gas, which has suffered constant increases due to rising demand. This fact opens the possibility of using technologies that were previously considered economically unviable. The hydrogen unit studied was constructed in one of the Petrobras refineries, and the hydrogen produced is for the removal of sulfur in diesel oil. Based on project documents exergetic efficiencies of each component were determined. After that, an economic analysis was conducted in order to determine the construction, operation and maintenance costs of the whole plant. Two types of cost were determined, the actual cost production, which indicates the current cost product (2010), and the levelized cost, which takes into account the total production over life of the plant. Considering a natural gas cost equal to 9.11 US$/GJ, it was obtained an actual hydrogen production cost of 17.36 US$/GJ (2,093.13 US$/t) and a levelized cost of 25.35 US$/GJ (3,056.97 $/t). These values were compared with some hydrogen production costs presents on scientific papers and related references.

This research is based on the case study of P company¡¦s daily operation and business data, to construct its cost evaluation and decision making model. The goal of this research is to fully understand and to model the decision making processes of these small to middle size companies(SME Business) that provide integration services to their customers. The outcomes of this research can be used in prediction as well as optimization of cost evaluation and risk management. The research finds out, through evaluation and modeling, it is possible to reveal the interaction among cost factors, to estimate the lowest cost based on historical data, and to manage risks by coordinating the business partners, in order to make the highest profit from the project. The conclusions of this research are: 1. The high technical and know-how service industrials are relative new and comprehensive in terms of different business domains. Therefore, the risk of cost change is always higher than the other industrials. An accurate decision making model and to estimate project cost precisely is crucial for the business. 2. The case study of P company demonstrates the possibility of using common tools like Microsoft Excel, to manage large multifaceted business data in order to construct an accurate cost decision making model. This may provide a viable and practical solution for small sized businesses that do not have database systems for their decision making application. 3. It is suggested by this research that there are four easy construct, simple use decision making models, which are proven to be useful to lower the risk of budget decision making and to reduce the bias and deviation when these decision is simply based on personal working experience.

Cette thèse traite de la coopération et de la gouvernance climat dans l'ère post Copenhague. Son objectif est de caractériser l'évolution du régime climatique, prenant appui sur les positions de l'Union européenne, la Chine et les États-Unis, qui peuvent être désignés, à la fois en tant que gros émetteurs, économies majeures et grandes puissances. Deux déterminants sont considérés structurants pour cette analyse : les coûts d'atténuation des émissions et les coûts d'adaptation. Le point de départ de notre thèse se trouve dans l'évolution polarisée du régime climatique. Le fait le plus marquant de cette « métamorphose » est le passage, en 2009, de l'approche top-down à une approche bottom-up.Pour ce faire, nous mobilisons un cadre théorique hybride, qui comprend l'Économie politique internationale et l'économie du changement climatique. L'apport combiné de ces deux approches permet d'analyser la politique internationale du climat à travers l'économie de l'environnement et inversement, de renseigner l'incidence que ces relations peuvent avoir sur la logique économique. Nous proposons une approche spécifique de la coopération, basée sur la théorie du « k-groupe » de Duncan Snidal (1985).Dans ce cadre coopératif minilatéral, la thèse que nous soutenons est qu'il est possible d'avoir un k-groupe pour le climat et que celui-ci peut avoir un effet bénéfique sur la mise en place du régime climat. Nous argumentons que ce groupe peut être considéré comme un « club of the relevant » et que, pour former un k-groupe, il est nécessaire que les pays constituent une « coalition of the willing ». Ce qui structure la capacité et la volonté de l'action, ce sont principalement les coûts que cela implique, coûts d'atténuation et d'adaptation. En même temps, l'engagement de ce groupe se base sur le conditionnement. Le dispositif incitatif est constitué par l'idée d'une coopération de plus en plus large, qui atténue le problème du passager clandestin.Les résultats de recherche sont appréciés à la lumière de l'aboutissement de la COP 21. Si le k-groupe fonctionne, c'est que les trois pays décident d'aller de l'avant et acceptent d'endosser des coûts d'atténuation plus importants que les autres pays. Cet engagement collectif déclencherait un mouvement vertueux qui imposerait au régime climat un leadership partagé entre ces trois pays, ouvrant la voie aux autres. Si le k-groupe ne fonctionne pas, c'est parce que nos acteurs considèrent les coûts à court terme trop importants au regard de leurs propres intérêts et au regard du risque du free riding de la part des autres États. Compte tenu de la conjoncture économique dans laquelle se trouvent nos trois acteurs, ce scénario apparait comme étant probable.Enfin, dans notre modèle de l'analyse de la coopération nous privilégions le tandem Europe-Chine. Nous montrons que cette coopération tripartite devrait se construire à partir de ce binôme, du moment où, à la différence des États-Unis, c'est l'Europe qui apparait comme étant plus volontaire. La Chine, l'acteur incontournable du climat, qui risque de subir les conséquences du changement climatique de plein fouet, a plus d'intérêt à se rallier à l'Europe si elle souhaite obtenir un accord qui ne soit pas basé uniquement sur des contributions (nationales) minimales. / Our research focuses on the cooperation and climate governance in the post-Copenhagen era. Its main purpose is to observe and define the evolution of the climate regime, based on the positions of the European Union, China and the United States. These three countries can be considered as big emitters, major economies, as well as great powers. Two main drivers are taken into account in our analysis: mitigation and adaptation costs to climate change. The starting point for our research is to be found in the polarized evolution of the climate regime. The most illustrative aspect of this “metamorphosis” is the shift, in 2009, from the top-down to the bottom-up architecture of the climate regime.Thus, we resort to a hybrid theoretical background, which consists of both international political economy and climate change economy. The joint contribution of the two approaches allows us to analyze international political economy with climate economy as an input, as well as the impact of international relations on the main economic framework of climate change. Our research is based on a specific cooperation model, known as the “k-group” theory, as developed by Duncan Snidal (1985).Within this framework of minilateral cooperation, the thesis that we defend is that it is possible to have a climate k-group which may have a trigger effect in order to obtain an ambitious regime. The starting point for our argument is that this group can be considered as a “club of the relevant”, and that what it needs to achieve in order to constitute a k-group is to establish a “coalition of the willing”. The capacity and the willingness to act are mainly influenced by the costs they have to bear, that is the costs to mitigate their emissions and to adapt to the climate change consequences. Meanwhile, the group's collective commitment depends on other countries' actions. More precisely, the incentive mechanism is built on the idea that cooperation is meant to widen, in order to eventually prevent free riding.Our main results are to be regarded in the light of the COP 21 outcome. If the k-group works, it is because our three countries decide to move forward and accept to bear mitigation costs that are higher than those of other countries'. Their collective commitment should trigger a virtuous dynamic which would impose on climate regime a collective leadership of these three countries, thus leaving the others with no other way than to follow. If the k-group does not work, it is because our three actors consider upfront costs too high with respect to their own interests, as well as to the risk of free riding (if the others do not go along). Given our three actors' economic and political context, this scenario seems likely.Finally, we rather favor in our work the Europe-China tandem. We argue that the k-group should be built on this joint cooperation, since, unlike the United States, Europe appears to be more willing to endorse an ambitious regime, whereas China seems an unavoidable actor. Thus, China, which faces a major impact of climate change, should play along with Europe if it wishes to obtain an agreement that is not solely based on minimal (national) contributions.

Orientador: Prof. Dr. Harki Tanaka / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Biomédica, 2015. / Esse trabalho visou realizar um estudo para auxiliar gestores de tecnologias médicas por meio da denição de critérios de avaliação de tecnologia em saúde na escolha de um equipamento de mamograa. O gestor de tecnologias médicas na atualidade encontra no mercado três tipos de tecnologias de mamograa diferentes: mamograa convencional, mamograa computadorizada e mamograa digital. Primeiramente foi realizado um estudo sobre a cadeia de imagem de cada tecnologia. A partir do conhecimento da cadeia de imagem de cada tecnologia, foi possível identicar cada processo característico de todas as tecnologias e com isso identicar a especicidade do custo gerado por essas modalidades em cada ponto. Alguns valores como custo de aquisição, custo de manutenção e custo de insumos foram coletados da Bolsa Eletrônica de Compras do Estado de São Paulo e no Diário Ocial da União. Características relacionadas à epidemiologia, sensibilidade e especicidade foram coletadas em estudos cientícos. Um estudo sobre a desinstalação e descarte foi realizado, levando-se em consideração as diretrizes para cada tecnologia. A m de nos aproximar da realidade do funcionamento de um mamógrafo, as diferentes tecnologias em mamograa foram inseridas em um contexto de uma clínica de imagens radiológicas. Para auxiliar a análise econômica foram desenvolvidas planilhas de cálculo eletrônico. A vida útil considerada para cada equipamento foi de 10 anos. O custo que representou maior impacto econômico foi o de recursos humanos em todas as tecnologias. A mamograa que apresentou o menor custo por exame foi a mamograa computadorizada sem impressão do lme (CRP), embora o custo de aquisição dos seus equipamentos seja aproximadamente quatro vezes maior que a mamograa convencional. A mamograa computadorizada quando existe a impressão do lme apresentou o maior valor por exame. Os estudos de acurácia e sensibilidade mostraram que a mamograa digital tem um pequeno ganho apenas em mulheres abaixo de 50 anos quando comparada à mamograa convencional. / This study aimed to help medical technology managers to choose mammography equipment through criteria of health technology assessment. The manager of medical technologies nds on the market today three dierent types of mammography technologies: conventional mammography, computerized mammography and digital mammography. First, we conducted a study on the image chain for each technology. From the knowledge of the image chain for each technology, it was possible to identify each characteristic process of all technologies and thereby identifying the specicity of the costs generated by such arrangements on each point. Some values as acquisition cost, maintenance cost and cost of inputs were collected from Electronic Trading Platforms of São Paulo state and in the Ocial Gazette of Brazil. Characteristics related to epidemiology, sensitivity and specicity were collected in scientic studies. A study on uninstalling and disposal was carried out, taking into account the guidelines for each technology. In order to approach the reality of the operation of a mammography unit, the dierent technologies in mammography were inserted in a context of clinical radiological images. To assist the economic analysis, electronic spreadsheets were developed. The lifetime considered for each equipment was 10 years. The greater economic impact was the cost of human resources in all technologies. A mammogram that showed the lowest cost per exam was computerized mammography without screen-lm (CRP), although the cost of purchasing of the equipment is approximately four times higher than conventional mammography. Computerized mammography, when there is the impression of the lm, has the highest cost per exam. The accuracy and sensitivity studies have shown that digital mammography has a small gain only in women under 50 years of age, when compared to conventional mammography.

O hidrogênio molecular (H2) é um gás muito útil nas indústrias químicas e petroquímicas por conta de sua facilidade de reação com outros elementos químicos. Nas refinarias é o principal insumo no processo de remoção do enxofre de diversos combustíveis como a gasolina e óleo diesel, tendo sua demanda aumentada por conta de novas legislações ambientalmente mais restritivas. O hidrogênio é normalmente encontrado na natureza associado a outros elementos químicos, como a água ou os hidrocarbonetos, sendo necessária a aplicação de processos específicos para sua obtenção. Considerada a rota mais econômica para a produção de hidrogênio, o processo de reforma a vapor do gás natural é avaliado pela aplicação da metodologia de análise exergética e termoeconômica, a fim de determinar a eficiência exergética do processo e o custo de produção do hidrogênio. Este custo de produção é muito sensível ao custo do gás natural, fato que pode prejudicar a competitividade desta rota de produção e, consequentemente, abrir a possibilidade de investir na produção de hidrogênio através de tecnologias alternativas. A unidade de geração de hidrogênio estudada está presente em uma das refinarias da Petrobras e sua produção destina-se à remoção do enxofre presente no óleo diesel. Uma planta síntese do processo foi elaborada e as eficiências exergéticas dos componentes foram determinadas. Em seguida, foi realizada uma análise econômica para determinar o custo de construção, operação e manutenção da planta. Com base nos resultados obtidos, aplicou-se a metodologia de análise termoeconômica para determinar o custo de produção de hidrogênio. Dois tipos de custo foram determinados, o custo atual (ou atualizado) de produção, que indica o custo corrente (2010) do produto, e o custo nivelado, que leva em consideração a produção total prevista ao longo vida útil da planta. Para um custo de gás natural igual a 9,11 US$/GJ, o custo de produção do hidrogênio em base exergética foi igual a 17,36 US$/GJ (2.093,13 US$/t) para o valor atual e 25,35 US$/GJ (3.056,97 US$/t) para o valor nivelado. Por fim, estes valores são comparados com outros custos de produção de hidrogênio presentes na literatura. / Pure hydrogen (H2) is an useful gas in chemical and petrochemical industries because it reacts easily with several other elements. On refineries, hydrogen is used to sequestrate sulphur from diesel and gasoline. Emission restrictions regard to fossil fuels are rising the world hydrogen demands. In spite of its abundance, hydrogen is normally found associated with other chemical species like water or hidrocarbons like methane or butane. Some especific processes are required to obtain pure hydrogen. Considered the most economic production route, the natural gas reforming process is analyzed by exergetic and thermoeconomic methods in order to determine the efficiencies and the hydrogen production cost. The hydrogen production cost is very sensitive to the cost of natural gas, which has suffered constant increases due to rising demand. This fact opens the possibility of using technologies that were previously considered economically unviable. The hydrogen unit studied was constructed in one of the Petrobras refineries, and the hydrogen produced is for the removal of sulfur in diesel oil. Based on project documents exergetic efficiencies of each component were determined. After that, an economic analysis was conducted in order to determine the construction, operation and maintenance costs of the whole plant. Two types of cost were determined, the actual cost production, which indicates the current cost product (2010), and the levelized cost, which takes into account the total production over life of the plant. Considering a natural gas cost equal to 9.11 US$/GJ, it was obtained an actual hydrogen production cost of 17.36 US$/GJ (2,093.13 US$/t) and a levelized cost of 25.35 US$/GJ (3,056.97 $/t). These values were compared with some hydrogen production costs presents on scientific papers and related references.

A leishmaniose visceral zoonotica (LVZ) e uma das mais importantes doenc¸as parasitárias emergentes. Em particular, o Brasil é considerado um dos principais centros endêmicos para esta doença. Apesar da publicação de manuais de controle da leishmaniose visceral e dos investimentos aplicados na organizacão de serviços e no desenvolvimento de atividades preventivas e de controle, os vetores e os reservatórios em áreas urbanas são os maiores desafios para os programas de controle. Isto se deve (1) `a necessidade por melhor compreensão do comportamento do vetor no meio urbano; (2) `as dificuldades operacionais para realizar atividades em tempo suficiente para obter resultados de impacto; e (3) ao alto custo envolvido nessas atividades. O principal objetivo deste estudo foi elaborar um modelo de otimização para o controle da leishmaniose, baseado em 5 parâmetros de controle que correspondem `as seguintes estratégias: (I) controle vetorial, (II) eliminação de cães positivos, (III) uso de coleiras impregnadas com inseticida, (IV) vacinação canina e (V) tratamento canino. Este modelo foi construído a partir de um sistema composto por 17 equações diferenciais, sendo que 4 representam a dinâmica da doenc¸a sobre a população humana (humanos suscetíveis (xh), latentes (lh), clinicamente doentes (yh) e recuperados (zh)), 10 para a populacão de cães (cães suscetíveis (xd e xCd ), latentes (ld e lCd ), clinicamente doentes (yd e yCd ), recuperados (zd e zCd ) e vacinados (vd e vCd ), onde o índice C representa as categorias com a aplicação da coleira inseticida) e 3 para a população de vetores (mosquitos não-infectados (s1), infectados (mas não-infectivos) (s2), infectados e infectivos (s3)). Para a an´alise econômica dessas estratégias, foram estimados os custos de cada uma delas por cão (ou, no caso do controle vetorial, por casa tratada). Considerando a simulação sem a introdução das estratégias de controle, as densidades de equilíbrio endêmico para as categorias foram: xh = 0, 394, lh = 0, 0305, yh = 0, 00167, zh = 0, 574, xd = 0, 314, ld = 0, 165, yd = 0, 0163, zd = 0, 505, s1 = 0, 709, s2 = 0, 0858 e s3 = 0, 205. No estado de equilibrio endêmico, o número de reprodutibilidade basal foi estimado em R0 = 4, 50 e o n´umero diário de casos humanos notificados, em R = 3, 58 × 10-6/dia. Considerando a avaliação do impacto das estratégias de controle, o controle vetorial mostrou ser a estrat´egia que causa a diminuição mais rápida sobre o núumero diário de casos humanos notificados e, consequentemente, foi tambem a que mais reduz os custos m´edico-hospitalares. Entretanto, ´e a estratégia que exige o maior investimento. Por outro lado, a estrat´egia de eliminar cães positivos foi considerada a de menor custo. Dado que essas estratégias de controle atuam em pontos distintos na cadeia epidemiológica, o planejamento de um controle envolvendo a ação simultânea delas poderia não apenas apresentar resultados de controle mais interessantes, como tambem poderia otimizar ainda mais os investimentos sobre o controle da leishmaniose visceral / Zoonotic visceral leishmaniasis (ZVL) is one of the most important emerging parasitic diseases. Brazil, in particular, is considered one of the countries in which this disease is most endernic. Despite the publication of visceral leishmaniasis control guidelines and the investment in health services and controljpreventive activities, the vectors and reser- voirs in urban areas are the major challenge for those control programs. This is due to (1) the need for better comprehension regarding the vector behavior in the urban envi- ronment; (2) the operating difficulties in perforrning the activities in time to reach good results; and (3) the high cost of those activities. The main objective of this study was to elaborate an optirnization model for leishmaniasis control. This model is based on 5 con- trol parameters that correspond to the following strategies: (I) vector population control, (11) elirnination of positive dogs, (111) use of insecticide-impregnated dog collars, (IV) dog vaccination and (V) dog treatment. This model was elaborated using an equation system, composed of 17 differential equations, 4 of which represent the disease dynarnic on hu- man population (susceptible (Xh), latent (Ih), clinically ill (Yh) and recovered humans (Zft)), 10 for dog population (susceptible (Xd and xcd), latent (ld and Icd), clinically ill (Yd and Ycd), recovered (Zd and zcd) and vaccinated dogs (Vd and vcd), where C represents the categories using the insecticide-impregnated dog collars) and 3 for vector population (non-infected (SI), infected but not infective (S2), infected and infective sandflies (S3)). For econornic analysis of those control strategies, we estimated the cost of them per dog (in the case of vector control population, it was estimated per treated house). Regarding the nume- rical simulations without the control strategies, the endernic equilibrium densities were: Xh = 0.394, Ih = 0.0305, Yh = 0.00167, Zh = 0.574, Xd = 0.314, Id = 0.165, Yd = 0.0163, Zd = 0.505, SI = 0.709, S2 = 0.0858 and S3 = 0.205. In endernic equilibrium state, the basic reproduction number and the rate of reported human cases per day were estimated as 1%0 = 4.50 and R = 3.58 x 1O-6/day, respectively. Considering the impact evaluation of controI strategies, the vector population control was the strategy that resulted in a fas- ter decrease in the rate of human reported cases per day and, consequently, in the larger reduction of medical and hospital costs too. However, the investment (that is, the cost) of the vector population control was the highest one. On the other hand, the investment in elirninating positive dogs was considered the lowest one. Since those control strategies operate at different points within the epiderniological chain, the planning a control, while taking into account the simultaneous action of these strategies, could not only result in a more interesting control strategy, but could also improve the optirnization of investments on visceralleishmaniasis control

A leishmaniose visceral zoonotica (LVZ) e uma das mais importantes doenc¸as parasitárias emergentes. Em particular, o Brasil é considerado um dos principais centros endêmicos para esta doença. Apesar da publicação de manuais de controle da leishmaniose visceral e dos investimentos aplicados na organizacão de serviços e no desenvolvimento de atividades preventivas e de controle, os vetores e os reservatórios em áreas urbanas são os maiores desafios para os programas de controle. Isto se deve (1) `a necessidade por melhor compreensão do comportamento do vetor no meio urbano; (2) `as dificuldades operacionais para realizar atividades em tempo suficiente para obter resultados de impacto; e (3) ao alto custo envolvido nessas atividades. O principal objetivo deste estudo foi elaborar um modelo de otimização para o controle da leishmaniose, baseado em 5 parâmetros de controle que correspondem `as seguintes estratégias: (I) controle vetorial, (II) eliminação de cães positivos, (III) uso de coleiras impregnadas com inseticida, (IV) vacinação canina e (V) tratamento canino. Este modelo foi construído a partir de um sistema composto por 17 equações diferenciais, sendo que 4 representam a dinâmica da doenc¸a sobre a população humana (humanos suscetíveis (xh), latentes (lh), clinicamente doentes (yh) e recuperados (zh)), 10 para a populacão de cães (cães suscetíveis (xd e xCd ), latentes (ld e lCd ), clinicamente doentes (yd e yCd ), recuperados (zd e zCd ) e vacinados (vd e vCd ), onde o índice C representa as categorias com a aplicação da coleira inseticida) e 3 para a população de vetores (mosquitos não-infectados (s1), infectados (mas não-infectivos) (s2), infectados e infectivos (s3)). Para a an´alise econômica dessas estratégias, foram estimados os custos de cada uma delas por cão (ou, no caso do controle vetorial, por casa tratada). Considerando a simulação sem a introdução das estratégias de controle, as densidades de equilíbrio endêmico para as categorias foram: xh = 0, 394, lh = 0, 0305, yh = 0, 00167, zh = 0, 574, xd = 0, 314, ld = 0, 165, yd = 0, 0163, zd = 0, 505, s1 = 0, 709, s2 = 0, 0858 e s3 = 0, 205. No estado de equilibrio endêmico, o número de reprodutibilidade basal foi estimado em R0 = 4, 50 e o n´umero diário de casos humanos notificados, em R = 3, 58 × 10-6/dia. Considerando a avaliação do impacto das estratégias de controle, o controle vetorial mostrou ser a estrat´egia que causa a diminuição mais rápida sobre o núumero diário de casos humanos notificados e, consequentemente, foi tambem a que mais reduz os custos m´edico-hospitalares. Entretanto, ´e a estratégia que exige o maior investimento. Por outro lado, a estrat´egia de eliminar cães positivos foi considerada a de menor custo. Dado que essas estratégias de controle atuam em pontos distintos na cadeia epidemiológica, o planejamento de um controle envolvendo a ação simultânea delas poderia não apenas apresentar resultados de controle mais interessantes, como tambem poderia otimizar ainda mais os investimentos sobre o controle da leishmaniose visceral / Zoonotic visceral leishmaniasis (ZVL) is one of the most important emerging parasitic diseases. Brazil, in particular, is considered one of the countries in which this disease is most endernic. Despite the publication of visceral leishmaniasis control guidelines and the investment in health services and controljpreventive activities, the vectors and reser- voirs in urban areas are the major challenge for those control programs. This is due to (1) the need for better comprehension regarding the vector behavior in the urban envi- ronment; (2) the operating difficulties in perforrning the activities in time to reach good results; and (3) the high cost of those activities. The main objective of this study was to elaborate an optirnization model for leishmaniasis control. This model is based on 5 con- trol parameters that correspond to the following strategies: (I) vector population control, (11) elirnination of positive dogs, (111) use of insecticide-impregnated dog collars, (IV) dog vaccination and (V) dog treatment. This model was elaborated using an equation system, composed of 17 differential equations, 4 of which represent the disease dynarnic on hu- man population (susceptible (Xh), latent (Ih), clinically ill (Yh) and recovered humans (Zft)), 10 for dog population (susceptible (Xd and xcd), latent (ld and Icd), clinically ill (Yd and Ycd), recovered (Zd and zcd) and vaccinated dogs (Vd and vcd), where C represents the categories using the insecticide-impregnated dog collars) and 3 for vector population (non-infected (SI), infected but not infective (S2), infected and infective sandflies (S3)). For econornic analysis of those control strategies, we estimated the cost of them per dog (in the case of vector control population, it was estimated per treated house). Regarding the nume- rical simulations without the control strategies, the endernic equilibrium densities were: Xh = 0.394, Ih = 0.0305, Yh = 0.00167, Zh = 0.574, Xd = 0.314, Id = 0.165, Yd = 0.0163, Zd = 0.505, SI = 0.709, S2 = 0.0858 and S3 = 0.205. In endernic equilibrium state, the basic reproduction number and the rate of reported human cases per day were estimated as 1%0 = 4.50 and R = 3.58 x 1O-6/day, respectively. Considering the impact evaluation of controI strategies, the vector population control was the strategy that resulted in a fas- ter decrease in the rate of human reported cases per day and, consequently, in the larger reduction of medical and hospital costs too. However, the investment (that is, the cost) of the vector population control was the highest one. On the other hand, the investment in elirninating positive dogs was considered the lowest one. Since those control strategies operate at different points within the epiderniological chain, the planning a control, while taking into account the simultaneous action of these strategies, could not only result in a more interesting control strategy, but could also improve the optirnization of investments on visceralleishmaniasis control