No presente trabalho são aplicadas ferramentas estatísticas quantitativas clássicas no setor de telefonia móvel brasileiro a fim de comparar os seus resultados. Uma metodologia é proposta para a aplicação destas ferramentas de um modo prático em uma de uma operadora de telefonia celular brasileira. Após são aplicados os métodos de previsão às séries históricas de demanda de acessos da telefonia móvel brasileira, estratificadas de acordo com as tecnologias utilizadas (TDMA, CDMA e GSM), no período de agosto de 2002 a julho de 2007. De acordo com o desempenho, são obtidos os modelos de cada método estatístico proposto. Entre estes, se escolheu aquele que melhor descreveu cada série e previsões foram geradas. Os modelos ARIMA apresentaram o melhor desempenho dentre os métodos aplicados nas séries estudadas. / The activity of planning ahead their systems in an appropriate manner is fundamental to telecommunication sector agents in order to manage the resources allocation and to meet the quality requirements in the provision of mobile telephony services. As the networks and production systems deployment takes time, there is the need of a service demand forecast. Therefore, in this study, classical quantitative statistics tools are applied to the Brazilian mobile telephony sector to compare their results. A methodology for the application of such tools in a practical way within a business environment of this sector is proposed. Afterwards, forecasting methods are applied to the time series referred to Brazilian mobile telephony demand, stratified according to the technologies (TDMA, CDMA and GSM) in the period from August 2002 to July 2007. The models of each statistical method proposed, based on the performance results, are obtained and, among these methods, it is chosen a model that best described each time series. The ARIMA model had the best performance among the methods applied in the time series studied and forecasts were made.

[pt] Esta dissertação teve como objetivo o desenvolvimento e a implantação de uma metodologia de previsão de vendas e dimensionamento de lotes de encomenda num distribuidor atacadista de produtos químicos. Para tanto, abordou técnicas quantitativas de previsão de demanda de curto prazo e medidas de variância dos erros de previsão a fim de suportar decisões empresariais na aplicação da metodologia, capazes de projetar padrões passados num cenário futuro. A aplicação da metodologia possibilitará à empresa a formalização de um processo atualmente subjetivo, outorgando maior precisão na previsão de vendas, redução de custos com estoque e uma base mais concreta para alocação de recursos financeiros. / [en] This thesis has as objective the developing and implantation of a methodology for forecasting sales and design of batch ordering in a wholesale distributor of chemical products. For this purpose, it approached short term quantitative techniques of demand forecast and measures of variance of forecast errors in order to support business decisions on the application of the methodology, able to design past patterns on a future scenario. The application of the methodology will enable the company the formalization of a process currently subjective, granting a greater accuracy in forecasting sales, reduction in the inventory costs and a more concrete basis for resource allocation.

As intensas evoluções do mercado forçam as empresas a adequarem seus negócios abordando novos meios estratégicos para se manterem competitivas diante de seus concorrentes. O objetivo do trabalho é analisar novos arranjos produtivos encontrados no segmento automobilístico que se destacam por necessitar de uma forma cada vez melhor de relacionamento com seus clientes através de uma modelagem do sistema para disponibilizar a visibilidade do estoque nos diversos estágios como: antes da produção, durante a produção, durante o transito, quando estocados nos pátios e até possibilitando a colocação de pedido para itens que não estão disponíveis nos estágios anteriores citados. O trabalho também aborda um estudo de previsão de demanda que utiliza modelos matemáticos sobre a média da quantidade de vendas apuradas em determinado período de tempo e um comparativo com o método dos mínimos quadrados. A consequência do engajamento dos pedidos nas etapas anteriores da real disponibilidade física dos produtos para comercialização e entrega, propõe otimizar os níveis de estoque em quantidades mais baixas do que o modelo atual. Os cenários são simulados e visam contribuir como ferramenta para demonstrar a viabilidade de um novo modelo de política de comercialização dos produtos. / The intense Market developments force companies adapt their business by addressing new strategic means to remain competitive in the face of its competitors. The objective is to analyze new production arrangements found in the automotive sector that need to stand out by an ever better relationship with its customers through a modeling system to provide inventory visibility in different stages such as: before production, during production, during transit, when stored in the courtyards and even allowing for the placement of order for items that are not available in earlier stages cited. The paper also discusses a study of demand forecasting which uses mathematical models to average volumes calculated requests in a given time period and a comparison with the least squares method. The result of the engagement of requests in previous stages of actual physical availability of products for sale and delivery, proposes optimize inventory levels in amounts lower than the current model. The scenarios are simulated and aim to contribute as a tool to demonstrate the feasibility of a new model of political marketing.

The Master’s thesis provides an analysis of problems related to physical distribution of a selected group of products in a production company. It contains proposal that facilitates meeting the customers’ demands for quantity and time and contributes to the competitive advantage of the company in the market.

La presente tesis se realizó en una empresa metalmecánica que se dedica a la fabricación y servicio técnico de intercambiadores de calor para diferentes mercados de la industria peruana. En el desarrollo del presente proyecto, se identificó mediante herramientas como el diagrama de Pareto y el diagrama del árbol para ambas unidades de negocio de la empresa metalmecánica, como problema principal el bajo nivel de cumplimento de entregas a tiempo de los intercambiadores de calor a sus clientes, tomando como prioridad, las causas que están generando este problema son las constantes rupturas de stock y error en los pronósticos. Por ello, se propone un plan de mejora en la gestión de inventario utilizando una clasificación ABC multicriterio de materiales del almacén en función a los criterios que se van a desarrollar en la presente tesis, además de definir un stock mínimo de materiales dentro del almacén y lote óptimo compra de los materiales directos. Por otro lado, para reducir el error de pronóstico, se realizó un análisis de demanda para la selección de los métodos de pronósticos cuantitativos que se ajustan a la empresa. Con su implementación se espera mejorar los indicadores logísticos de la empresa, reducir el tiempo de producción de la empresa y establecer un tiempo de entrega de los productos finales más competitivo en el mercado. / This thesis was carried out in a metalworking company that is dedicated to the manufacture and technical service of heat exchangers for different markets of the Peruvian industry. In the development of this project, tools such as the Pareto diagram and the tree diagram for both business units of the metalworking company were identified as the main problem with the low level of fulfillment of timely deliveries of heat exchangers to their Customers, taking as a priority, the causes that are generating this problem are the constant stock breaks and forecast errors. Therefore, an improvement plan in inventory management is proposed using a multi-criteria ABC classification of warehouse materials based on the criteria that will be developed in this thesis, in addition to defining a minimum stock of materials within the warehouse and Optimal purchase lot of direct materials. On the other hand, to reduce the forecasting error, a demand analysis was performed for the selection of quantitative forecasting methods that fit the company. With its implementation, it is expected to improve the logistics indicators of the company, reduce the production time of the company and establish a delivery time for the most competitive end products in the market. / Trabajo de Suficiencia Profesional

A tool to model both current rail and future high-speed rail (HSR) corridors has been presented in this work. The model is designed as an addition to the existing TSAM (Transportation System Analysis Model) capabilities of modeling commercial airline and automobile demand. TSAM is a nationwide county to county multimodal demand forecasting tool based on the classical four step process. A variation of the Box-Cox logit model is proposed to best capture the characteristic behavior of rail demand in US. The utility equation uses travel time and travel cost as the decision variables for each model. Additionally, a mode specific geographic constant is applied to the rail mode to model the North-East Corridor (NEC). NEC is of peculiar interest in modeling, as it accounts for most of the rail ridership. The coefficients are computed using Genetic Algorithms. A one county to one station assignment is employed for the station choice model. Modifications are made to the station choice model to replicate choices affected by the ease of access via driving and mass transit. The functions for time and cost inputs for the rail system were developed from the AMTRAK website. These changes and calibration coefficients are incorporated in TSAM. The TSAM model is executed for the present and future years and the predictions are discussed. Sensitivity analysis for cost and speed of the predicted HSR is shown. The model shows the market shift for different modes with the introduction of HSR. Limited data presents the most critical hindrance in improving the model further. The current validation process incorporates essential assumptions and approximations for transfer rates, short trip percentages, and access and egress distances. The challenges for the model posed by limited data are discussed in the model. / Master of Science

We study the benefits of resource flexibility, considering two different flexibility structures. First, we want to understand the impact of the firm's pricing strategy on its resource investment decision, considering a partially flexible resource. Secondly, we study the benefits of a flexible resource strategic approach, considering a resource flexibility structure that has not been studied in the previous literature. First, we study the capacity investment decision faced by a firm that offers two products/services and that is a price-setter for both products/services. The products offered by the firm are of varying levels (complexities), such that the resources that can be used to produce the higher level product can also be used to produce the lower level one. Although the firm needs to make its capacity investment decision under high demand uncertainty, it can utilize this limited (downward) resource flexibility, in addition to pricing, to more effectively match its supply with demand. Sample applications include a service company, whose technicians are of different capabilities, such that a higher level technician can perform all tasks performed by a lower level technician; a firm that owns a main plant, satisfying both end-product and intermediate-product demand, and a subsidiary, satisfying the intermediate-product demand only. We formulate this decision problem as a two-stage stochastic programming problem with recourse, and characterize the structural properties of the firm's optimal resource investment strategy when resource flexibility and pricing flexibility are considered in the investment decision. We show that the firm's optimal resource investment strategy follows a threshold policy. This structure allows us to understand the impact of coordinated decision-making, when the resource flexibility is taken into account in the investment decision, on the firm's optimal investment strategy, and establish the conditions under which the firm invests in the flexible resource. We also study the impact of demand correlation on the firm's optimal resource investment strategy, and show that it may be optimal for the firm to invest in both flexible and dedicated resources when product demand patterns are perfectly positively correlated. Our results offer managerial principles and insights on the firm's optimal resource investment strategy as well as extend the newsvendor problem with pricing, by allowing for multiple resources (suppliers), multiple products, and resource pooling. Secondly, we study the benefits of a delayed decision making strategy under demand uncertainty, considering a system that satisfies two demand streams with two capacitated and flexible resources. Resource flexibility allows the firm to delay its resource allocation decision to a time when partial information on demands is obtained and demand uncertainty is reduced. We characterize the structure of the firm's optimal delayed resource allocation strategy. This characterization allows us to study how the revenue benefits of the delayed resource allocation strategy depend on demand and capacity parameters, and the length of the selling season. Our study shows that the revenue benefits of this strategy can be significant, especially when demand rates of the different types are close, while resource capacities are much different. Based on our analysis, we provide guidelines on the utilization of such strategies. Finally, we incorporate the uncertainty in demand parameters into our models and study the effectiveness of several delayed capacity allocation mechanisms that utilize the resource flexibility. In particular, we consider that demand forecasts are uncertain at the start of the selling season and are updated using a Bayesian framework as early demand figures are observed. We propose several heuristic capacity allocation policies that are easy to implement as well as a heuristic procedure that relies on a stochastic dynamic programming formulation and perform a numerical study. Our study determines the conditions under which each policy is effective. / Ph. D.

Research has validated the contribution of information sharing to performance improvement. It has also suggested that flexibility is a highly important competitive priority for those companies where demand is volatile. Several studies argue that flexibility has been recognized as a key enabler for supply chain responsiveness. However, the impact of information sharing on supplier flexibility is still unexplored, especially for the companies that operate in agile business environments such as in the automotive industry where flexibility is a strategic requirement to manage demand uncertainty. In agile supply chains, such as in the automotive industry, information sharing can play an important role in responding to demand variability. In such settings, the demand volumes generally fluctuate, and hence create production-scheduling problems for the upstream suppliers such as first-tier suppliers. Interestingly, the impact of demand fluctuations on suppliers is higher than that of Original Equipment Manufacturers (OEMs). The aim of this doctoral thesis is to investigate the role of information sharing between OEMs and first-tier suppliers, in enhancing supplier flexibility. Particularly, the research focuses on exploring the relationship between sharing demand schedules and inventory data, and volume and delivery flexibility. The questions on whether information sharing between OEMs and first-tier suppliers affect supplier flexibility remain unanswered. The following research questions have emerged:  RQ1: How does information sharing between OEMs and first-tier suppliers affect the latter's responsiveness to fluctuating demand? RQ2: What is the relationship between information sharing of OEMsʼ demand forecasts and inventory data, and suppliers’ volume and delivery flexibility? RQ3: What factors should OEMs consider to improve the sharing of demand forecasts with suppliers? The empirical part of this thesis comprises three individual studies that constitute the empirical foundations of the research problem. Each study analyzes one research question using its own methodological approach. Hence, different research methods for collecting and analyzing data were used to address the research questions. Applying different research methods is deemed advantageous because it allows for methodological rigorousness in this doctoral thesis. This thesis contributes to the body of knowledge in three dimensions—theory, method, and context. First, it contributes to the academic field of operations and supply chain management by developing a model to explain how information sharing could affect suppliers’ delivery performance. The model provides a measurement scale to measure the level of information sharing between OEMs and suppliers, and its impact on suppliers’ delivery flexibility. Second, this thesis contributes to the methods by using state-of-the-art techniques, which is partial least squares structural equation modeling (PLS-SEM) including consistent PLS, and applying advanced concepts to empirically test the proposed model. Third, this thesis has a managerial contribution to examine the concept of information sharing and flexibility at the supplier level. Investigating the problem at the supplier level may enable managers to improve short-term decisions, such as production scheduling decisions, internal production, and inventory processes, and evaluate collaboration practices with OEMs. This doctoral thesis is organized in a monograph format comprising five chapters: Introduction, Literature review, Methodology, Empirics, and Conclusion. As an outcome, several scientific articles have emerged from this thesis and have been submitted for consideration for publication in peer-reviewed journals and international conferences in the field of operations and supply chain management. These articles are listed and appended at the end of this dissertation. / <p>QC 20160302</p>

[pt] A necessidade de integração entre os vários componentes de uma cadeia de suprimento e o SEOP (Sales and Operations Planning) são conceitos amplamente conhecidos pelas empresas, entretanto muitas vezes é difícil alinhar os conceitos teóricos às necessidades e aos processos reais das empresas. O foco deste trabalho é o planejamento operacional da cadeia logística de abastecimento de petróleo e derivados de uma empresa petrolífera. A empresa utiliza um modelo de programação linear determinístico para elaboração do plano. Foram monitorados os desvios entre o realizado e o planejado de diversos parâmetros que influenciam no plano, como preços internacionais, volume de produção de petróleo, demanda de alguns derivados e disponibilidades de unidades de refinaria. Após análise desses desvios, utilizou-se o modelo de programação linear da empresa para elaborar uma série de sensibilidades, retroalimentando o modelo, com a utilização dos erros médios das variáveis. Por fim são agrupadas as informações sobre realizado x planejado x sensibilidade (plano modificado) à incerteza. Os resultados mostram que o plano modificado considerando à incerteza das variáveis através dos erros médios históricos possibilita um planejamento mais robusto, onde o resultado deixa de ser um valor ótimo determinístico e se apresenta como uma faixa de valores bons. / [en] The need for integration between the various components of the supply chain and the SEOP (Sales and Operations Planning) are concepts widely known by the companies, however it is often difficult to align theoretical concepts to the real needs and processes of companies. The focus of this work is the operational planning of the logistics supply chain of petroleum and derivatives of an oil company. The company uses a deterministic linear programming model for development of the plan. The parameters´ deviations between real and planning data, which influence the plan, as international prices, volume of oil production, demand for some oil derivatives and availability of refinery units were monitored. After analyzing of these deviations, we used the linear programming model of the company to develop a range of sensitivities, feeding back the model, using the mean errors of the variables. Finally the information of real x plan x modified plan (planned sensitivity) with uncertainty are grouped. The results show that the modified plan considering the uncertainty of the variables through the historical average errors enables a more robust planning, where the result is no longer a deterministic optimal value and it presents itself as a good range of values.

[pt] Esta dissertação teve como objetivo propor o desenvolvimento e estabelecimento de um método de gerenciamento de estoque de peças de uniformes a ser implantado através de uma solução de TI que possa vir a ser utilizado por todos os Gerentes dos PDU´s (Postos de Distribuição de Uniformes) e pelo Gerente de Fardamento da Marinha. Com esse fulcro, foram apresentadas técnicas de segmentação de materiais, de previsão de demanda de curto prazo, de gerenciamento de estoque (método de ponto de pedido e método de revisão periódica) e técnicas de cálculo de estoque de segurança para determinado nível de serviço. Adicionalmente, com o intuito de possibilitar a comparação entre políticas de estoques distintas, foram estudados três importantes classes gerais de custos que são: os custos de pedido, de manutenção do inventário e de falta de estoques. Como resultado, foram apresentadas algumas reformulações necessárias a serem implementadas na atual ferramenta de TI utilizada pela Marinha para gerenciar o estoque. Uma vez implantada, essa ferramenta irá permitir aos Gerentes, conhecedores das nuances do mercado, melhores condições para a tomada de decisões relativas aos seus estoques. / [en] The objective of this dissertation is to develop and establish an inventory management method for uniforms through IT solutions that can be used by all inventory managers at uniform distribution points. With this in mind, studies were conducted on techniques for material classification, short term demand forecasting, inventory management (continuous review method and periodic review method) as well as techniques for calculating safety stock to achieve the desired the service level. Additionally, this proposal allows us to compare and contrast different inventory policies on the basis of three principal cost criteria. Those criterion are: acquisition cost, inventory maintenance, and inventory loss. As a result, recalculations were proposed to the IT solution that is currently being used by the Brazilian Navy to effectively manage stock levels. Once implemented, these tools will allow inventory managers, the technical experts of the navy, to make the best decisions with the best information possible.