			Home About us Contact

Planning Period (planning + period)

Distribution by Scientific Domains

Business, Economics, Finance and Accounting	60%

Selected Abstracts

Short-term harvest planning including scheduling of harvest crews

INTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 5 2003
J. Karlsson
Abstract The problem we consider is short-term harvesting planning for a total planning period of 4,6 weeks where we want to decide the harvest sequences or schedules for harvest crews. A schedule is an order or sequence of harvest areas assigned to each crew. The harvesting of areas is planned in order to meet industrial demand. The total cost includes harvesting, transportation, and storage. One considerable cost is due to the quality reduction of logs stored at harvest areas. There are a number of restrictions to be considered. Areas are of varying size and the composition of assortments in each area is different. Each harvest team has different skills, a different home base, and different production capacity. Another aspect is the road network. There is a cost related to road opening (restoring, snow removal). In this paper, we develop a mixed integer programming (MIP) model for the problem. The schedules are represented by 0/1 variables. With a limited number of schedules, the problem can be solved by a commercial MIP solver. We have also developed a heuristic solution approach that provides high-quality integer solutions within a distinct time limit to be used when more schedules are used. Computational results from a major Swedish forest company are presented. [source]

Economic Impacts of Technology, Population Growth And Soil Erosion At Watershed Level: The Case Of the Ginchi in Ethiopia

JOURNAL OF AGRICULTURAL ECONOMICS, Issue 3 2004
B.N. Okumu
A dynamic bio-economic model is used to show that, without technological and policy intervention, soil loss levels, income and nutrition could not be substantially or sustainably improved in a highland area of Ethiopia. Although cash incomes could rise by more than 40% over a twelve-year planning period, average per ha soil losses could be as high as 31 tonnes per ha. With the adoption of an integrated package of new technologies, however, results show the possibility of an average two-and-a-half-fold increase in cash incomes and a 28% decline in aggregate erosion levels even with a population growth rate of 2.3%. Moreover, a minimum daily calorie intake of 2000 per adult equivalent could be met from on-farm production with no significant increases in erosion. However, higher rates of growth in nutritional requirements and population introduce significant strains on the watershed system. From a policy perspective, there is a need for a more secure land tenure policy than currently prevailing to facilitate uptake of the new technology package, and a shift from the current livestock management strategy to one that encourages livestock keeping as a commercial enterprise. It would also imply a shift to a more site-specific approach to land management. [source]

An asymptotically optimal greedy heuristic for the multiperiod single-sourcing problem: The cyclic case

NAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 5 2003
H. Edwin Romeijn
The dynamics of the environment in which supply chains evolve requires that companies frequently redesign their logistics distribution networks. In this paper we address a multiperiod single-sourcing problem that can be used as a strategic tool for evaluating the costs of logistics network designs in a dynamic environment. The distribution networks that we consider consist of a set of production and storage facilities, and a set of customers who do not hold inventories. The facilities face production capacities, and each customer's demand needs to be delivered by a single facility in each period. We deal with the assignment of customers to facilities, as well as the location, timing, and size of inventories. In addition, to mitigate start and end-of-study effects, we view the planning period as a typical future one, which will repeat itself. This leads to a cyclic model, in which starting and ending inventories are equal. Based on an assignment formulation of the problem, we propose a greedy heuristic, and prove that this greedy heuristic is asymptotically feasible and optimal in a probabilistic sense. We illustrate the behavior of the greedy heuristic, as well as some improvements where the greedy heuristic is used as the starting point of a local interchange procedure, on a set of randomly generated test problems. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 412,437, 2003 [source]

A single-period inventory placement problem for a serial supply chain

NAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 6 2001
Chia-Shin Chung
Abstract This article addresses the inventory placement problem in a serial supply chain facing a stochastic demand for a single planning period. All customer demand is served from stage 1, where the product is stored in its final form. If the demand exceeds the supply at stage 1, then stage 1 is resupplied from stocks held at the upstream stages 2 through N, where the product may be stored in finished form or as raw materials or subassemblies. All stocking decisions are made before the demand occurs. The demand is nonnegative and continuous with a known probability distribution, and the purchasing, holding, shipping, processing, and shortage costs are proportional. There are no fixed costs. All unsatisfied demand is lost. The objective is to select the stock quantities that should be placed different stages so as to maximize the expected profit. Under reasonable cost assumptions, this leads to a convex constrained optimization problem. We characterize the properties of the optimal solution and propose an effective algorithm for its computation. For the case of normal demands, the calculations can be done on a spreadsheet. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48:506,517, 2001 [source]

Joint Assessment of Optimal Sales Force Sizes and Sales Call Guidelines: A Management-Oriented Tool

CANADIAN JOURNAL OF ADMINISTRATIVE SCIENCES, Issue 3 2005
René Y. Darmon
Abstract Sales force sizing and sales effort allocation methods vary from simplistic rules of thumb to sophisticated analytical procedures. The former methods are easy to understand and implement, but they are typically inaccurate and probably invalid. The latter procedures may provide more accurate and valid results, but they are more difficult to explain to management and require data collection and analysis that are often quite elaborate. This paper proposes a method of optimal estimation of total sales effort level and time allocation that combines the advantages of both approaches. For each customer segment, this method accounts for the so far neglected, but relevant, optimal call effort allocation between number of calls per account during a planning period and length of sales calls. A case study illustrates this method. Résumé Les méthodes de détermination de la taille et de l'allocation des efforts de vente vont des règles empiriques les plus simples aux procédures analytiques les plus complexes. Les premières sont faciles à comprendre et à appliquer, mais elles sont imprècises et souvent non valides. Les autres méthodes peuvent donner des résultats plus exacts, mais elles sont plus difficiles à expliquer aux managers et nécessitent souvent une collecte et une analyse de données fort laborieuses. Le présent article propose une méthode d'estimation optimale de la taille et de l'allocation des efforts de vente qui combine les avantages des deux approches. Pour chaque segment de la clientèle, la méthode rend compte de l'allocation optimale (souvent négligée, mais pertinente), de l'effort de vente entre le nombre de visites à faire à un client pendant une période de planification et la longueur des visites. Un cas concret illustre la méthode. [source]