A renewable energy source, sugar cane ethanol, fuels many Brazilian automobiles. We demonstrated the economic advantage of decentralized distribution directly from the producing mills over the federally mandated practice of centralized, multi-product (ethanol plus fossil fuels) distribution in the producing region of Southeastern Brazil. In the investment analysis, we evaluated logistics costs using a transshipment (LP) model. The quantitative results of our study influenced the client organization, Grupo COSAN/Bom Jesus, to begin lobbying efforts to change federal regulations. The government approved deregulation in July 1993. This changed a Brazilian paradigm; instead of fuel distribution being concentrated in a few big companies, there would be increased competition in the ethanol arena. Currently, Grupo COSAN/Bom Jesus has begun a joint venture with a fossil fuel distributor to invest in this new distribution scheme.
Ao longo das últimas duas décadas, o setor público viu-se sob maior pressão para melhorar seu desempenho e demonstrar maior transparência e avaliação de resultados. Historicamente, o setor público brasileiro apresenta uma estrutura departamental e burocrática, o que dificulta a coordenação das atividades e diminui a eficiência e a eficácia de seus serviços. Diante desta realidade, algumas instituições brasileiras do setor público vêm buscando melhorias em sua forma de operar. Neste contexto, este trabalho tem como objetivo propor um modelo de aperfeiçoamento de processos administrativos para Instituições Públicas de Ensino Superior (IPES) brasileiras, baseado em estudo de múltiplos casos. A coleta de dados foi realizada por meio de observação, análise documental e entrevistas semiestruturadas. Considerando que na literatura existem poucos relatos sobre aperfeiçoamento de processos no setor público brasileiro, os resultados obtidos neste trabalho consistem em contribuição para a teoria, uma vez que abrangem fatores específicos do setor público e sua influência sobre programas de melhoria. Além disso, diante da grande necessidade de melhoria dos processos do setor, a descrição dos casos e a análise de seus resultados apresentam aplicação prática, uma vez que proporcionam uma base para trabalhos futuros.
This paper presents three approaches to support decision-making for production planning, sales and inventory problems. They work in a situation with: non-stationary probabilistic demand; production capacity in regular hours and overtime; shortage leads to lost sales; limited internal storage space; and ordering costs resulting from machine preparation are negligible. In the first approach, we consider the problem as linear and deterministic. In the second, safety inventories are used to fill a probabilistic demand, but the possibility of stockout is not considered. The third approach estimates shortage resulting from demand uncertainty. The last two approaches use iterative processes to re-estimate unit holding cost, which is the basis to calculate safety inventories in each period of the horizon. Using Microsoft Excel Solver, with linear programming and nonlinear search functions, a hypothetical example (but strongly based on real-life companies) and some scenarios permit concluding that developing more realistic and complex models may not provide significant benefits. KEYWORDS | Inventory, non-stationary probabilistic demand, aggregate production planning, sales and operations mathematical models, no ordering costs.
Resumo Este estudo mostra a vantagem econômica da distribuição descentralizada de álcool etíli-co, diretamente a partir das usinas produtoras, contra a política usualmente utilizada de distribuição de vários produtos (álcool, gasolina e óleo diesel) com o intermédio de bases de distribuição. A análise de investimentos utilizou um modelo de distribuição baseado em programação linear para avaliar os custos logísticos. Os resultados quantitativos do estudo influenciaram o cliente do estudo (um dos produtores de álcool) a iniciar esforços para que o governo brasileiro alterasse as regulamentações restritivas, o que foi feito em julho de 1993.Palavras-chave: logística -distribuição de combustíveis, estudo de localização.
Palavras-chaves: estoques, simulação, administração de materiais, varejo IntroduçãoEste trabalho tem como objeto a administração de estoques de bens de varejo com algumas características específicas intrínsecas e de mercado. Os bens cuja administração é estudada neste trabalho são bens de consumo não perecíveis (ao menos no horizonte de algumas semanas), com demanda significativa e ciclo de vida longo, como bolachas, sabonetes, farinha de trigo, leite condensado, etc.Os mercados em que tais produtos são considerados são aqueles em que há várias opções para o consumidor final, de forma que, quando um determinado varejista não tem o bem disponível no momento desejado pelo cliente, este pode, sem custos
This study aims to present an alternative technique of exponential smoothing to estimate the demand for items with intermittent and seasonal demand. The usual technique would aggregate demand periods (months in quarters, for instance) to calculate a seasonality factor for the set of periods. The estimate for the set would be divided by the number of periods comprising it to calculate the demand per period. This technique recalculates the basis and seasonality factor for each set, and provides equal estimates for all periods within the set. The alternative herein presented also recalculates seasonal factors for every set of periods, but recalculates the demand basis for each period, allowing better monitoring of demand behavior. Based on a real-life case, the results obtained by the two techniques mentioned above and by others that do not explicitly consider seasonality were compared: simple moving average, no-seasonality exponential smoothing, Croston’s, and Syntetos-Boylan. The latter two were developed specifically for intermittent demands without seasonality. The techniques that consider seasonality performed better for estimation errors. The suggested technique, in the example, showed less bias, although with somewhat lower accuracy than exponential smoothing with seasonality and period aggregation.
This paper aims to compare different models to support decision making in production planning (and, consequently, in sales and inventory), in an environment where product demands are variable and uncertain, it is possible to produce at normal hours and overtime, loss of sales is consequence of stockouts, there is limit to internal storage, with possible and more expensive external storage, and ordering costs are non-negligible. At first, we present a linear and deterministic model, with known demand and without shortage. In the second model, safety stocks are calculated to meet a probabilistic demand, but it is not yet considered the possibility of shortage. The third model includes shortage calculation as a consequence from demand uncertainty. The last two models use an iterative process to re-estimate the unit cost of storage, needed to calculate safety stocks in each period of the planning horizon. The models were implemented in MSExcel, making use of linear programming and search functions available in the software. As the original problem, data of the examples are based on real companies. The study allows concluding that, in the problem analyzed, linear models, simpler and faster to execute, may be sufficient to support good decisions.
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