Actualmente las empresas se encuentran en un entorno competitivo y complejo enfrentándose a un camino largo que sobrellevar para el aseguramiento de sus inventarios y así poder ser más efectivas y competitivas. Para reforzar este aspecto se requiere de diversas estrategias de gestión donde la logística se convierte en un detalle fundamental y que precisamente se debe aprovechar para sacar ventaja, siendo el sistema de aprovisionamiento de inventarios el primer eslabón clave que potencializar para alcanzar los objetivos de una empresa, de aquí se desprende la necesidad de la empresa Korea Motos S.R.L. la cual presente diversas deficiencias en el ámbito logístico que les demanda sobrecostos, sobre stocks, perdidas e incluso daños por la inadecuada gestión del sistema de aprovisionamiento. De lo mencionado, se desprende el objetivo general que fue evaluar el sistema de aprovisionamiento y su aplicación en la gestión de la empresa Korea Motos S.R.L., para su desarrollo de utilizó una metodología con enfoque mixto, de diseño no experimental y nivel descriptivo. La población de enfoque fue la empresa en sí, cuya muestra fue el sistema de aprovisionamiento. El principal resultado obtenido es la carencia de un manejo apropiado en el sistema de aprovisionamiento, presentando múltiples deficiencias en ámbitos de compras, gestión de proveedores y almacenamiento, por tal motivo se estableció políticas y procedimientos a seguir con el fin de mejorar cada aspecto que involucra el sistema de aprovisionamiento. / Currently, are in a competitive and complex environment, facing a long way to go in order to secure their inventories and thus be able to be more effective and competitive. To reinforce this aspect, various management strategies are required where logistics becomes a fundamental detail and that should be used precisely to take advantage, with the inventory supply system being the first key link to potentiate to achieve the objectives of a company. , hence the need for the company Korea Motos S.R.L. which presents various deficiencies in the logistics field that demands cost overruns, over stocks, losses and even damages due to inadequate management of the supply system. From the above, the general objective is clear, which was to evaluate the supply system and its application in the management of the Korea Motos S.R.L. company, for its development a methodology with a mixed approach, nonexperimental design and descriptive level was used. The focus population was the company itself, whose sample was the supply system. Among the results obtained, it is stated that the company lacks proper management in the supply system, presenting multiple deficiencies in the areas of purchases, supplier management and storage, for this reason policies and procedures were established to be followed to improve each aspect that involves the supply system.

Samhällets ökande konsumtion via e-handel är ett faktum, vilket i allra högsta grad berör ämnet logistik. Det finns därav anledning för företag som bedriver e-handel och har ett lager att förbättra sin lagerstruktur och därmed effektivisera sina lagerprocesser. Denna studie använder värdeflödesanalys för att kartlägga kärnprocesserna plockprocessen och packprocessen för e-handelsföretaget Spelexperten Sultana AB, som säljer sällskapsspel och leksaker. Studien syftar till att identifiera ineffektiviteter och tidsslöseri och därefter presentera förbättringsåtgärder för att förbättra företagets lagerstruktur i sin helhet. Studien omfattas av en mixad metodansats som kombinerar kvalitativ och kvantitativ data genom en fallstudie. Primärdata samlas in genom dokumentgranskning, observationer och ostrukturerade intervjuer. Sekundärdata samlas in i form av tidigare forskning och litteratur vilket utgör studiens teoretiska referensram. Resultatet visar på förekomst av icke värdeskapande aktiviteter och spillaktiviteter i form av tidsslöseri vilka presenteras i en nutida lägesbeskrivning. Genom förbättringsåtgärder som baseras på den teoretiska referensramen presenteras en framtida lägesbeskrivning i två olika scenarion; ett realistiskt och ett idealt. Slutsatsen konstaterar att värdeflödesanalys inom ramen för Lean är ett lämpligt och användbart verktyg som kan användas för att kartlägga processer i syfte att presentera förbättringsåtgärder för ett företags lagerstruktur. / The increasing consumption through e-commerce is a fact, which is significantly correlated with the field of logistics. Hence, there is a reason for companies that are engaged in e-commerce and are operating a warehouse to improve their warehouse structure and thus streamline their warehousing processes. This study uses a value stream analysis to map the picking process and the packing process, which are both core processes for the e-commerce company Spelexperten Sultana AB, that sells board games and toys. The study aims to identify inefficiencies and waste of time and thereafter present actions of improvement to enhance the overall warehouse structure. The study uses a mixed-method approach that combines qualitative and quantitative data through a case study. Primary data is collected by reviewing documents, observations and unstructured interviews. Secondary data is collected in the form of previously done research together with literature, that forms the studies theoretical framework. The results show the presence of non value-adding and waste activities in the form of wastage of time, which are presented in a current state description. Through actions of improvement that are based in the theoretical framework a future state description is provided in two scenarios: one realistic and one ideal. The conclusion asserts that value stream mapping within the framework of Lean is an appropriate and useful tool for mapping processes with the aim of presenting actions of improvement for a company’s warehouse structure.

La presente investigación se centra en el control interno en la gestión de inventarios de las empresas comerciales. La investigación tuvo como propósito brindar información respecto a estas variables de manera que permita sincerar los stocks de los repuestos y autopartes, con esto se manejaría de manera oportuna y confiable la información contable. Asimismo, su objetivo general fue el análisis de la incidencia del sistema control interno en la gestión de inventarios de la empresa Charapo repuestos & autopartes E.I.R.L, Chiclayo – 2022. La investigación es de enfoque mixto, nivel descriptivo, tipo aplicada, diseño no experimental y transversal, la muestra estuvo compuesta por el área de almacén y el área de ventas, el muestreo es no probabilístico. Los resultados obtenidos son los siguientes: Se conocieron los aspectos generales de la empresa, en el cual se identifica que no tiene una visión y misión definida, no tiene una estructura organizacional detallada, además presenta deficiencias en su proceso de adquisición, almacenamiento y venta, de igual forma se encontró que el control interno es confiable el 38%; además, se realizaron indicadores de liquidez y gestión donde se concluye que los indicadores no son óptimos, porque su rotación de inventarios es baja, lo cual puede afectar su liquidez; del mismo modo, se elaboró políticas de control interno. En conclusión, la empresa no presenta un control interno confiable y su gestión de inventarios no es eficiente, por ende, se elaboraron políticas de control interno. / This research focuses on internal control in inventory management of commercial companies. The purpose of the research was to provide information regarding these variables in a way that allows honesty of the stocks of spare parts and auto parts, with this the accounting information would be handled in a timely and reliable manner. Likewise, its general objective was the analysis of the incidence of the internal control system in the inventory management of the company Charapo spare parts & autoparts E.I.R.L, Chiclayo – 2022. The research has a mixed approach, descriptive level, applied type, non-experimental design and transversal, the sample was composed of the warehouse area and the sales area, the sampling is non-probabilistic. The results obtained are the following: The general aspects of the company were known, in which it is identified that it does not have a defined vision and mission, it does not have a detailed organizational structure, and it also presents deficiencies in its acquisition, storage and sale process. Likewise, it was found that internal control is reliable 38%; In addition, management indicators were carried out where it is concluded that the indicators are not optimal, because their inventory rotation is low, which can affect their liquidity; Likewise, internal control policies were developed. In conclusion, the company does not have reliable internal control and its inventory management is not efficient, therefore, internal control policies were developed.

El presente estudio aborda la importancia del control eficiente en el área de almacén y su impacto en la rentabilidad de las empresas. En el contexto peruano, gran parte de las organizaciones enfrentan dificultades para implementar un control adecuado en esta área, lo cual puede ocasionar problemas como precios altos, deterioro y obsolescencia de materiales, generando pérdidas y desvalorización de existencias. Se resalta que los riesgos de control representan la probabilidad de eventos no deseados que pueden dificultar la capacidad de la empresa para enfrentar situaciones propias de sus actividades. La empresa Mabara Contratistas Generales de responsabilidad limitada, ubicada en Chiclayo, se convierte en el foco de este estudio debido a su ineficiente gestión del almacén, lo cual podría estar afectando su rentabilidad. Se identifican problemas como la mala distribución del almacén, la falta de un manual de políticas y procedimientos, la inadecuada infraestructura, la gestión financiera deficiente, el robo de materiales y la toma errónea de decisiones. A través de la identificación de riesgos de control y la implementación de medidas adecuadas, se busca mejorar la eficiencia y eficacia en el manejo de los recursos y, por ende, lograr resultados económicos satisfactorios. / The present study addresses the importance of efficient control in the warehouse area and its impact on the profitability of companies. In the Peruvian context, a large number of organizations face difficulties in implementing adequate control in this area, which can lead to issues such as high prices, material deterioration, and obsolescence, resulting in losses and devaluation of stocks. It is emphasized that control risks represent the probability of undesired events that can hinder a company's ability to deal with activities inherent to its operations. Mabara Contratistas Generales, a limited liability company located in Chiclayo, becomes the focus of this study due to its inefficient warehouse management, which may be affecting its profitability. Problems such as poor warehouse distribution, lack of a manual for policies and procedures, inadequate infrastructure, poor financial management, material theft, and erroneous decision-making are identified. Through the identification of control risks and the implementation of appropriate measures, the aim is to improve efficiency and effectiveness in resource management, thus achieving satisfactory economic results.

L’objet de cette recherche est la modélisation et l'étude de l'impact de la prise en compte des perturbations et des erreurs sur les politiques de réapprovisionnement pour un e-détaillant. Une des principales incertitudes en gestion de stock est l’écart entre la quantité en stock lue dans le système d’information et la quantité réellement disponible dans le système physique. A travers une étude empirique nous avons montré que l’impact de ce type d’erreurs est important dans le cas du e-détaillant. Dans ce contexte, le système d’information joue le premier rôle dans le processus de satisfaction de la demande puisque c’est sur la confrontation entre la demande du client final et les quantités figurant dans le Système d’Information que repose la promesse de vente. A l’exception de quelques contributions, les perturbations en gestion des stocks ont été principalement étudiées dans le contexte du détaillant. Nous avons étudié l’impact de ces perturbations sur la politique de stockage dans un contexte e-détaillant en faisant l’hypothèse d’une modélisation multiplicative des erreurs afin d’optimiser le profit du e-détaillant, et proposé deux modèles de réapprovisionnement, mono- et deux- périodes. Pour le premier, nous avons proposé une extension du modèle classique de vendeur de journaux au contexte de e-détaillant/fournisseur, avec un processus de demande sujet à des perturbations. Une étude analytique nous a permis de comparer l’impact de deux types de modélisation des erreurs, additive et multiplicative. Le deuxième modèle est une extension du premier au cas deux périodes. Avec sa résolution exacte, nous avons démontré que le comportement des quantités optimales était non monotone et qu’une politique myopique n’est pas optimale pour le cas multi-périodes. Grace à une étude numérique nous avons pu proposer des recommandations pour les managers, quant aux quantités à commander pour les deux périodes. Un troisième modèle de réapprovisionnement étudie l’impact des perturbations pour un problème multi-périodes avec minimisation des coûts et en considérant deux taux de service à atteindre, l’un sur la satisfaction des demandes et l’autre sur la satisfaction des ventes. Dans ce contexte, nous avons étudié et discuté plusieurs stratégies d’alignement dont réalisation d’inventaires et déploiement de technologie RFID. / The aim of this PhD research is to study the impact of the inventory inaccuracy issue on replenishment policies under the wholesaling / e-retailing context. The inventory inaccuracy is defined as a discrepancy between the quantity shown by the Informational System and the quantity actually Physically available for sales. Such discrepancy has as root many sources of errors such as execution, transaction, misplacement, supply unreliability or shrinkage errors. We provide empirical evidence on the wide presence of inventory inaccuracies through one case study of wholesaling organizations. In e-retailing context customers’ demands are remotely satisfied based on the inventory level shown in the information system. The main interest of the research community was about studying the inaccuracy under the retail context. After motivating our research empirically and by the literature review, we develop three inventory frameworks subject to inventory inaccuracies under the wholesaling / e-retailing context with different configurations of the stochastic errors describing the inaccuracy issue. The error configuration could be additive for some sources of inaccuracies such as transaction as well as multiplicative (also known as stochastically proportional) for other sources such as shrinkage. Our first inventory framework aims to extend single-period (Newsvendor) model to the e-retailing/wholesaling context subject to inaccuracy. In Addition, to providing managerial insights, we compare the behavior of the optimal ordering strategies under the additive and the multiplicative error settings. Our second inventory framework is an extension of the former to the case of two selling periods. By solving exactly the two-period problem, we show that the behavior of the optimal ordering quantities is not monotonic, and conclude that a myopic policy could not be optimal. Thanks to a numerical study, we derive some interesting managerial insights about the management of the error risk between the two selling periods. Thanks to the theoretical results of our second inventory framework, we propose a third framework dealing with the inventory inaccuracy issue under a multi-period setting by assuming cost minimizing as a target but also by considering two Cycle Service Level constraints to achieve, the former for the demand satisfaction and the latter for the sales commitment satisfaction. We provide a comprehensive numerical study by comparing several policies as making inspection and RFID deployment.

Spare parts are, for many companies, a complex product to logistically handle. This is in part due to the varying characteristics and sporadic demand patterns of spare parts. Obstacles can often arise when companies utilize the same approach to their spare parts stock as they do with their general warehouse manufacturing inventory. By using the same approach, companies risk neglecting the widespread variation of the spare parts. With the help of established routines, a clear set of guidelines and factors, the chances of a successful handling of spare parts inventory is increased. The study is a qualitative case study with the purpose of identifying specific factors and to make recommendations of models for companies to take into account when evaluating and storing spare parts. Through unstructured/semi-structured interviews conducted with four case company employees, information was gathered which was used to assist in identifying these specific factors and models for companies. A theoretical frame of reference was produced through analyzing research articles and was compared to the compiled empirical data in an analysis. The departments within the case study based their work on single factor which were considered important for each specific department, without inter-departmental communication. The factors that were identified in the study include service, competitive advantage, tied up capital, size capacity, complexity, sales frequency and material. Four of these were considered to be a priority for the case company. The study showed that different models for spare parts management and outsourcing could be implemented in the case company. By integrating the different models for spare parts management and outsourcing, combined with communication, a new model has been proposed for handling the spare parts storage. / Reservdelar är för många företag en komplex produkt att hantera utifrån dess varierande egenskaper och sporadiska efterfrågemönster. Problematiken härstammar ofta från att många företag hanterar reservdelslager utifrån samma förutsättningar som dess allmänna lagerhantering, därigenom försummas reservdelarnas olika egenskaper. Förutbestämda riktlinjer och faktorer krävs vid hantering av reservdelar och en viktig komponent för att lyckas med detta är kommunikation. Arbetet är en kvalitativ fallstudie med syftet att ta fram faktorer och rekommendationer av modeller att ta hänsyn till vid värdering och lagerhantering av reservdelar. För att besvara syftet och frågeställningarna utfördes ostrukturerade/semistrukturerade intervjuer med fyra medarbetare på fallföretaget. En teoretisk referensram togs fram genom litteratursökningar som sedan ställdes i en jämförelse mot den sammanställda empirin i en analys. Studien visade att de olika avdelningarna på fallföretaget främst utgått från en enda faktor som ansetts vara viktig för den specifika avdelningen. Utifrån de framtagna faktorerna i studien; service, konkurrensfördel, kapitalbindning, fyllnadsgrad, komplexitet, försäljningsfrekvens och material, ansågs fyra av dessa vara av prioritet för fallföretaget. Studien visade att olika modeller för reservdelshantering och outsourcing skulle kunna implementeras på fallföretaget. Genom att integrera de olika modellerna för reservdelshantering och outsourcing, kombinerat med kommunikation, har en ny modell föreslagits för hantering av reservdelslager.

Le « transshipment (latéral) d’urgence » au sein des réseaux de distribution consiste à organiser les transferts de stocks entre les détaillants pour faire face aux situations de rupture. Sa mise en œuvre amène à arrêter une stratégie appropriée et à harmoniser ses paramètres avec la politique et paramètres de gestion des stocks, dans l’objectif de garantir un taux de satisfaction des demandes clients au moindre coût. Le présent travail se situe dans ce contexte et s’est focalisé sur l’analyse des apports de la mise en œuvre du transshipment d’urgence dans un système de pilotage de flux tirés par des demandes clients probabilistes, avec des politiques locales de gestion de stock du type (R, s, S). Notre étude a porté sur trois structures différentes de réseau : système de stock à deux échelons et à deux détaillants, avec coût unitaire de transshipment ; système de stock à deux échelons et à détaillants multiples, avec coût fixe de transshipment ; système de stock multi échelons à deux détaillants, avec coût fixe de transshipment. Pour chacune de ces structures, nous avons analysé le comportement du système pour différentes combinaisons des paramètres d’entrée (délais d’approvisionnement, écarts types de la demande et nombre des détaillants) et des paramètres de coût (commande, possession, rupture et transshipment). Nous avons visé à déterminer, sur un horizon fini de périodes, les seuils de stocks (s et S chez les détaillants et chez le centre de distribution) qui minimisent le coût total du système tout en garantissant un taux de service désiré. Dans ce cadre, quatre politiques de transshipment (« tout ou rien », « complete pooling standard », « complete pooling plafonné » et « complete pooling conditionné ») ont été explorées. L’étude est d’abord ébauchée selon une approche analytique puis approfondie par l’élaboration et l’expérimentation de modèles dont la résolution est basée sur la simulation-optimisation / The lateral emergency transshipment in distribution systems consists in organizing inventory transferts between retailers to face shortage situations. Its implementation leads to adopt an appropriate transhipment policy and harmonize its parameters with inventory policy parameters and inventory control policy. The objective is to ensure a desired service level at minimum cost. Thie work is situated in this context and focused on the analysis of emergency transhipment benefits in distribution systems faced to random customers demand. Each retailer used an (R,s,S) inventory control policy. Our study is related to three different distribution systems structure : two echelons two retailers inventory system with unit transhipment cost; two echelons multi retailers inventory system with fixed transhipment cost; multi echelons multi retailers inventory system with fixe transhipment cost. For each of these structures we analyzed the sensibility of system behaviour to input parameters. Our objective is to determine on a finite horizon the inventory parameters (s, S) that minimize total cost under service level condition.

O ambiente competitivo atual tem colocado pressão no processo de tomada de decisão no mundo corporativo. Os trade-offs das prioridades competitivas discutidos na elaboração da estratégia como custo, qualidade, serviço e flexibilidade já não são suficientes. Estes trade-offs, embora importantes no curto prazo, devem ser compatibilizados de modo que as empresas que tenham o melhor balanço entre eles devam ter resultado superior. Um dos trade-offs bastante discutido é o equilíbrio entre serviço e estoque. A percepção é que seja improvável alcançar excelência no serviço sem ter um considerável nível de estoque. Deste cenário nasce então o paradoxo do uso de sistemas MRP (Material Requirement Planning) versus sistemas JIT (Just in Time), ou melhor, sistemas empurrados versus puxados, já que a escolha por um ou outro sistema tem ligação íntima com a gestão de estoque. Se por um lado os sistemas MRP são largamente utilizados, via softwares ERP, por outro sistemas JIT têm trazido importantes melhorias nos resultados. Embora muitas empresas considerem a adoção exclusiva de um ou outro sistema, algumas delas têm adotado um processo híbrido com o objetivo de tirar o melhor de cada sistema e gerar assim desempenho superior. O objetivo deste trabalho é investigar como as empresas inseridas em mercados caracterizados pela concentração de demanda no final do mês (fenômeno conhecido como hockey-stick), e baixo acerto nas previsões de demanda, estão aplicando suas estratégias de planejamento de produção e seus ERP. Se por um lado a baixa acurácia nas previsões causa um problema na aplicação de estratégias empurradas de planejamento, pois requer um alto estoque de segurança associado, por outro a concentração de embarque dificulta a adoção de uma estratégia puramente puxada, já que o sistema não tem a estabilidade necessária. Para cumprir com este objetivo seis estudos de caso foram conduzidos e os resultados encontrados, suportados pela teoria, sugerem o aparecimento de um modelo híbrido eficaz para planejamento no ambiente estudado assim como o aparecimento de um sistema DSS (Decision Support System). Outra contribuição desta pesquisa foi identificar, em um dos casos, uma empresa que conseguiu atacar de maneira eficaz o fenômeno em sua causa raiz neutralizando assim seus efeitos. / The highly competitive environment of modern times has put pressure on the decision-making process in the corporate world. The trade-offs of competitive priorities such as cost, quality, service and flexibility are no longer enough. These trade-offs, albeit important in the short term, must be matched so that companies that have the best balance between them should have superior results. One of the tradeoffs widely discussed is the balance between service level and inventory. The perception is that excellence is not likely to be achieved in service without having a significant level of inventory. From this scenario comes the paradox of using MRP systems (Material Requirement Planning) versus JIT systems (Just in Time), or rather \"pushed\" systems versus \"pulled\" systems since the option for one or the other system has a close connection with inventory management. On the one hand, MRP systems are widely used in industry through ERP software; on the other hand, JIT systems have obtained better results. While many companies consider adopting one or another system, some of them adopt a hybrid process with the goal of taking the best of each system and generate superior performance. The purpose of this research is to investigate how companies inserted in markets characterized by sales peak at the end of the month (hockey-stick phenomenon), and low accuracy in demand forecasts, are applying their production planning strategies and their ERP. Low forecast accuracy causes a problem in applying pushed strategies as it requires a high safety stock associated. Conversely, the sales peak hinders the adoption of a purely pull strategy since the system does not have the necessary stability. To meet this goal, six case studies were conducted and the results found and supported by the theory suggest the emergence of an effective hybrid model for planning in the environment studied as well as the appearance of a DSS (Decision Support System). Another contribution of this research was to identify in one of the cases a company that managed to effectively tackle the phenomenon in the root cause, neutralizing its effects.

Submitted by Maicon Juliano Schmidt (maicons) on 2015-05-20T13:25:28Z No. of bitstreams: 1 2014 - Timoteo Andre Stuker.pdf: 2292716 bytes, checksum: 2f422b087fcce44075984f39efd5f016 (MD5) / Made available in DSpace on 2015-05-20T13:25:28Z (GMT). No. of bitstreams: 1 2014 - Timoteo Andre Stuker.pdf: 2292716 bytes, checksum: 2f422b087fcce44075984f39efd5f016 (MD5) Previous issue date: 2014-09-12 / Nenhuma / Para produtos de moda, a demanda é de difícil previsão por modelos lineares ou polinomiais e o ciclo de vida dos produtos é curto. Os varejistas são obrigados a tomarem as decisões de sortimento de produtos e quantidades de compra e estoques bem antes da época da venda, quando apenas informações limitadas e imprecisas estão disponíveis. As decisões são tomadas basicamente confiando em dados qualitativos e questões subjetivas. Os erros na previsão da demanda associados a esse modelo de tomada de decisão se aproxima de 50%. No entanto, as previsões de demanda podem ser melhoradas atualizando as previsões com base nas vendas iniciais. Nesse contexto, o objetivo do presente trabalho é propor um modelo de previsão de demanda baseado no aprendizado com as vendas iniciais para uma cadeia de suprimentos de um varejista de calçados. O modelo foi aplicado em uma rede de varejo calçadista brasileira, na coleção de Verão 2013/2014. O modelo de previsão de demanda foi proposto em duas etapas: (i) a primeira que utilizou dados históricos de vendas agregados por subgrupo de produtos, por loja; e (ii) a segunda que utilizou dados das vendas iniciais para desagregar a previsão por subgrupo na previsão por produtos e cores. Para gerar a previsão de longo prazo foi utilizado o modelo logístico. A Razão de Incremento Semanal (RIS), que é a previsão de vendas semanal por subgrupo dividida pela quantidade de produtos vendidos, foi utilizada como dados de entrada para decompor a previsão em produtos e cores. Além dessa informação, são entradas a quantidade vendida na primeira semana e a quantidade de produtos em estoque. A partir da modificação do cálculo da cobertura de estoques para incluir o RIS, tem-se a previsão de demanda atualizada. A previsão também considera a demanda de substituição e a quebra de grade. Os resultados encontrados demonstraram que o modelo de previsão de demanda atualizado com os dados de vendas obteve desempenho superior ao modelo de previsão original. O modelo de previsão de longo prazo se mostrou adequado para dois dos três subgrupos de produtos analisados. As métricas para medição do desempenho preditivo do modelo utilizadas foram o APE (absloute percentual errors ou erro percentual absoluto) e o MAPE* (média absoluta percentual dos erros ajustada). Foram considerados dois horizontes de previsão, seis e oito semanas. O desempenho do modelo conforme a métrica APE para seis semanas de horizonte de previsão foi de 55,199 para o modelo e de 207,511 para o modelo de previsão original. Já para oito semanas de horizonte de previsão foi de 51,232 para o modelo e de 93,212 para o modelo de previsão original. Conforme a métrica MAPE* para seis semanas de horizonte de previsão, o modelo apresentou resultados de 87,598 e o modelo de previsão original apresentou 239,777. E para oito semanas de horizonte de previsão o resultado foi de 88,454 para o modelo e de 167,515 para o modelo de previsão original. Como o modelo foi aplicado somente a um caso, o mesmo não pode ser considerado como validado. Não se pode esperar que os mesmos resultados sejam encontrados em casos diferentes. / For fashion products, the demand is very unpredictable and life cycle of products is short. Retailers are required to make decisions in the assortment and quantities of purchases and inventory a long time before the time of sale, when only limited and inaccurate information is available. Decisions are made relying primarily on qualitative data and subjective issues. Errors in demand forecast associated with this model of decision-making can approach 50%. However, demand forecasts can be improved by updating the predictions based on early sales. In this context, the aim of this work is to propose a demand forecast model based on learning with early sales for a footwear retailer supply chain. The model was applied in a Brazilian footwear retailer in the 2013/2014 Summer Collection. The demand forecasting model was proposed in two stages: (i) the first stage that used historical data aggregated by subgroup, considering product sales per store; and (ii) the second stage that used data from early sales to disaggregate the demand forecast into products and colors. To generate long-term forecast the logistic model was used. The Weekly Increment Proportion (WIP), which is the weekly demand forecast per subgroup divided by the number of products sold, was used as input data to decompose the demand forecast into products and colors. In addition to this information, the other entries are the quantity sold in the first week and the quantity of products in stock. Modifying the inventory turnover calculation to include WIP, we have the updated demand forecast. The forecast also considers the substitution demand and broken grade. The results demonstrated that the demand forecast model based on learning with early sales obtained higher results than original demand forecast model. The long-term forecast model was adequate for two of the three product subgroups analyzed. The metrics for measuring the predictive performance of the model used were APE (absolute percentual errors) and the MAPE* (adjusted mean absolute percentage error). Two forecast horizons were considered, six and eight weeks. The model performance according to the metric APE forecasting six weeks was 55,199 for the model and 207,511 for the original model prediction. Forecasting eight weeks it was 51,232 for the model and 93.212 for the original model prediction. According to the metric MAPE* forecasting six weeks, the model presented a result of 87.598 and the original model presented 239.777. And forecasting eight weeks the result was 88.454 for the model and 167.515 for the original model prediction. As the model was applied to only one case, it cannot be considered validated. The same results are not expected in different cases.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-04-28T12:47:41Z No. of bitstreams: 1 FILIPE BORTOLINI_.pdf: 6329595 bytes, checksum: 3dd8331791bb827a0806c8da5947b553 (MD5) / Made available in DSpace on 2016-04-28T12:47:41Z (GMT). No. of bitstreams: 1 FILIPE BORTOLINI_.pdf: 6329595 bytes, checksum: 3dd8331791bb827a0806c8da5947b553 (MD5) Previous issue date: 2015-11-20 / Nenhuma / A melhoria no planejamento de operações é uma das preocupações constantes das refinarias de petróleo, e a gestão eficiente dos estoques em parques de tancagem é um ponto fundamental nesse contexto. No entanto, são poucos os trabalhos que tratam especificamente deste assunto e as ferramentas de simulação existentes são caras e não refletem a realidade de muitas refinarias. A gestão ineficiente ou o dimensionamento inadequado dos parques de tancagem, por sua vez, podem gerar uma série de prejuízos. Um parque superdimensionado gera custos de gestão e manutenção, além dos custos do estoque. Um parque subdimensionado pode gerar perdas devido a desabastecimentos e degradação de produtos, entre outros. Às situações em que o subdimensionamento gera impactos na produção, com ou sem perdas financeiras, dá-se a denominação de stress em parques de tancagem. Esse trabalho descreve a implantação de uma ferramenta que possibilita a quantificação do stress em parques de tancagem. Essa quantificação é feita com o apoio de uma heurística baseada em dados relativos às movimentações, manutenções e níveis de estoque dos tanques. Também descreve a forma de cálculo de cinquenta e nove variáveis relacionadas às movimentações dos tanques. A influência que essas variáveis têm na formação de situações de stress foi analisada através do uso de redes neurais artificiais. Essa influência foi quantificada em cinco diferentes cenários, considerando-se a existência ou não de um ciclo de certificação de produto e a natureza das variáveis analisadas. Como resultado, identifica-se que as variáveis relacionadas ao tempo de esvaziamento, tempo de tanque parado em nível baixo e tempo de enchimento são as prevalentes na criação de situações de stress em parques de tancagem no contexto analisado. Também são mapeados e formalizados os fluxos dos algoritmos para determinação das etapas do ciclo de um tanque, e é definida uma fórmula para a determinação do nível de stress em um parque de tancagem em um determinado período de tempo. / The improvement in operations planning is a constant concern of oil refineries, and the efficient management of inventories in tank farm sites is a key point in this context. However, there are few studies that deal specifically with this issue and existing simulation tools are expensive and do not reflect the reality of many refineries. The inefficient management or improper sizing of tank farm sites, in turn, can generate significant financial losses. A oversized tank farm generates management and maintenance costs, in addition to inventory costs. An undersized tank farm can generate losses due to shortages and degradation of products, among others. The situations in which the undersizing generates impact in operations, with or without financial losses, is defined as stress in tank farm sites. The present study describes the implementation of a tool that allows the quantification of stress in tank farm sites. This measurement is made using a heuristic based on data on the inventory movimentation, maintenance status and inventory levels of the tanks. It also describes the calculation method of fifty-nine variables related to the movimentation of inventory. The influence of these variables on the formation of stress situations was analyzed using artificial neural networks. This influence was quantified in five different scenarios, considering whether or not a product certification cycle and the nature of the variables. As a result, it is identified that the variables related to emptying time, tank downtime at low level and fill time are prevalent in creating stressful situations in tank farm sites in the analyzed context. They are also mapped and formalized flows of algorithms to determine the stages of a tank cycle, and is defined a formula for determining the stress level in a tankage park at a given time.