![The stochastic dynamic production/inventory lot-sizing problem with service-level constraints [An article from: International Journal of Production Economics]](http://ecx.images-amazon.com/images/I/51H0DAK3DML.jpg)
Product Description
This digital document is a journal article from International Journal of Production Economics, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
This paper addresses the multi-period single-item inventory lot-sizing problem with stochastic demands under the ”static-dynamic uncertainty” strategy of Bookbinder and Tan (Manage. Sci. 34 (1988) 1096). In the static-dynamic uncertainty strategy, the replenishment periods are fixed at the beginning of the planning horizon, but the actual orders are determined only at those replenishment periods and will depend upon the demand that is realised. Their solution heuristic was a two-stage process of firstly fixing the replenishment periods and then secondly determining what adjustments should be made to the planned orders as demand was realised. We present a mixed integer programming formulation that determines both in a single step giving the optimal solution for the ”static-dynamic uncertainty” strategy. The total expected inventory holding, ordering and direct item costs during the planning horizon are minimised under the constraint that the probability that the closing inventory in each time period will not be negative is set to at least a certain value. This formulation includes the effect of a unit variable purchase/production cost, which was excluded by the two-stage Bookbinder-Tan heuristic. An evaluation of the accuracy of the heuristic against the optimal solution for the case of a zero unit purchase/production cost is made for a wide variety of demand patterns, coefficients of demand variability and relative holding cost to ordering cost ratios. The practical constraint of non-negative orders and the existence of the unit variable cost mean that the replenishment cycles cannot be treated independently and so the problem cannot be solved as a stochastic form of the Wagner-Whitin problem, applying the shortest route algorithm.
Buy this at Amazon
Product Features
![Optimal allocation of work in assembly lines for lots with homogenous learning [An article from: European Journal of Operational Research]](http://ecx.images-amazon.com/images/I/51G4P0G7AGL.jpg)
Product Description
This digital document is a journal article from European Journal of Operational Research, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
This paper deals with the problem of allocating work to the stations of an assembly line to minimize the makespan of a lot of products with a low overall demand. There is no buffer permitted in between the stations, and the line operates under homogeneous learning (i.e., under the same learning rate for all stations). We show that in the presence of learning, the optimal makespan requires imbalanced allocation of work to stations. The level of savings in the optimal makespan value due to the imbalanced loading of work over the balanced loading case are demonstrated as a function of the value of the learning constant, number of stations on the line as well as lot size. These savings can be quite significant under the case of low overall demand.
Buy this at Amazon
Product Features
Product Description
This digital document is a journal article from European Journal of Operational Research, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Multi-item inventory models with stock dependent demand and two storage facilities are developed in a fuzzy environment where processing time of each unit is fuzzy and the processing time of a lot is correlated with its size. These are order-quantity reorder-point models with back-ordering if required. Here possibility and crisp constraints on investment and capacity of the small storehouse respectively are considered. The models are formulated as fuzzy chance constrained programming problem and is solved via generalized reduced gradient (GRG) technique when crisp equivalent of the constraints are available. A genetic algorithm (GA) is developed based on fuzzy simulation and entropy where region of search space gradually decreases to a small neighborhood of the optima and it is used to solve the models whenever the equivalent crisp form of the constraint is not available. The models are illustrated with some numerical examples and some sensitivity analyses have been done. For some particular cases results observed via GRG and GA are compared.
Buy this at Amazon
Product Features
![Global review of health care surveys using lot quality assurance sampling (LQAS), 1984-2004 [An article from: Social Science & Medicine]](http://ecx.images-amazon.com/images/I/519EPRSDSHL.jpg)
Product Description
This digital document is a journal article from Social Science & Medicine, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
We conducted a global review on the use of lot quality assurance sampling (LQAS) to assess health care services, health behaviors, and disease burden. Publications and reports on LQAS surveys were sought from Medline and five other electronic databases; the World Health Organization; the World Bank; governments, nongovernmental organizations, and individual scientists. We identified a total of 805 LQAS surveys conducted by different management groups during January 1984 through December 2004. There was a striking increase in the annual number of LQAS surveys conducted in 2000-2004 (128/year) compared with 1984-1999 (10/year). Surveys were conducted in 55 countries, and in 12 of these countries there were 10 or more LQAS surveys. Geographically, 317 surveys (39.4%) were conducted in Africa, 197 (28.5%) in the Americas, 115 (14.3%) in the Eastern Mediterranean, 114 (14.2%) in South-East Asia, 48 (6.0%) in Europe, and 14 (1.8%) in the Western Pacific. Health care parameters varied, and some surveys assessed more than one parameter. There were 320 surveys about risk factors for HIV/AIDS/sexually transmitted infections; 266 surveys on immunization coverage, 240 surveys post-disasters, 224 surveys on women’s health, 142 surveys on growth and nutrition, 136 surveys on diarrheal disease control, and 88 surveys on quality management. LQAS surveys to assess disease burden included 23 neonatal tetanus mortality surveys and 12 surveys on other diseases. LQAS is a practical field method which increasingly is being applied in assessment of preventive and curative health services, and may offer new research opportunities to social scientists. When LQAS data are collected recurrently at multiple time points, they can be used to measure the spatial variation in behavior change. Such data provide insight into understanding relationships between various investments in social, human, and physical capital, and into the effectiveness of different public health strategies in achieving particular behavioral outcomes.
Buy this at Amazon
Product Features
Product Description
This digital document is a journal article from European Journal of Operational Research, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Previous research on the joint vendor-buyer problem focused on the production shipment schedule in terms of the number and size of batches transferred between the two parties. It is a fact that transportation cost is a major part of the total operational cost. However, in most joint vendor-buyer models, the transportation cost is only considered implicitly as a part of fixed setup or ordering cost and thus is assumed to be independent of the size of the shipment. As such, the effect of the transportation cost is not adequately reflected in final planning decisions. There is a need for models involving transportation cost explicitly for better decision-making. In this study we analyze the vendor-buyer lot-sizing problem under equal-size shipment policy. We introduce the complete solution of the problem in an explicit and extended manner that has not existed in the literature. We incorporate transportation cost explicitly into the model and develop optimal solution procedures for solving the integrated models. All-unit-discount transportation cost structures with and without over declaration have been considered. Numerical examples are presented for illustrative purpose.
Buy this at Amazon
Product Features
![Characteristics of washed-off pollutants and dynamic EMCs in parking lots and bridges during a storm [An article from: Science of the Total Environment, The]](http://ecx.images-amazon.com/images/I/51C6TCVNX8L.jpg)
Product Description
This digital document is a journal article from Science of the Total Environment, The, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Given the importance of water quality in drinking water sources, the Korean Ministry of Environment is designing and instigating the total maximum daily load (TMDL) program for major large rivers. For the successful implementation of this program, nonpoint pollutants resulting from various land uses should be controlled. Especially, paved areas such as parking lots and bridges are stormwater intensive land uses because of their high imperviousness and high pollutant mass emissions from vehicular activity. Vehicle emissions from these paved areas include various pollutants such as heavy metals, oil, grease and particulates. This research was conducted to investigate the magnitude and nature of the stormwater emissions with the goal of quantifying stormwater pollutant concentrations and mass emission rates from a parking lot and a bridge. Two monitoring sites in Kongju city were equipped with an automatic rainfall gauge and an automatic flow meter for measuring rainfall, water quality and runoff flow. This study presents the concentration changes during storm occurrence and event mean concentrations (EMCs) in the parking lot and bridge. The first flush criteria, a new concept explaining the relationship between EMC and the first flush effect, is also suggested using dynamic EMCs.
Buy this at Amazon
Product Features
Product Description
This digital document is a journal article from European Journal of Operational Research, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Delayed incentives in the form of mail-in cash rebates are very popular among manufacturers, and more recently, among retailers. One of the main advantages of rebates is that while they increase demand, a small proportion of consumers redeem them. In this paper, we formulate and solve models for jointly determining the optimal price, rebate face value, and the optimal order quantity for a price and rebate sensitive deterministic demand. The models show that under realistic conditions, offering rebates can have significant pricing and inventory policy implications and can lead to a significant increase in profit.
Buy this at Amazon
Product Features
![Loss of customer goodwill in the uncapacitated lot-sizing problem [An article from: Computers and Operations Research]](http://ecx.images-amazon.com/images/I/41SS7GZHX6L.jpg)
Product Description
This digital document is a journal article from Computers and Operations Research, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Loss of customer goodwill in uncapacitated single level lot-sizing is studied with a mixed integer programming model extending the well-known Wagner-Whitin (WW) model. The objective is to maximize profit from production and sales of a single good over a finite planning horizon. Demand, costs, and prices vary with time. Unsatisfied demand cannot be backordered. It leads to the immediate loss of profit from sales. Previous models augment the total cost objective by this lost profit. The difference of the proposed model is that unsatisfied demand in a given period causes the demand in the next period to shrink due to the loss of customer goodwill. A neighborhood search and restoration heuristic is developed that tries to adjust the optimal lot sizes of the original no-goodwill-loss model to the situation with goodwill loss. Its performance is compared with the WW solution, and with the commercial solver CPLEX 8.1 on 360 test problems of various period lengths.
Buy this at Amazon
Product Features
Product Description
This digital document is a journal article from Computers and Operations Research, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Lot-sizing problems are cornerstone optimization problems for production planning with time varying demand. We analyze the quality of bounds, both lower and upper, provided by a range of fast algorithms. Special attention is given to LP-based rounding algorithms.
Buy this at Amazon
Product Features
Product Description
This digital document is a journal article from European Journal of Operational Research, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Previous papers have presented the impact of various aspects, such as forecasting techniques, centralising information, and (s,S) ordering policy, on the variability of orders in a supply chain. In this paper we observe several properties of two traditional lot sizing rules, the Silver Meal (SM) and the least unit cost (LUC) on the variability of orders created by a supply chain channel receiving demand with stochastic variability from its downstream channel. Analytical models have been developed to compare the mean and variance of both order interval and order quantity produced by the two rules under relatively low demand variability. We show that, although the two rules appear to be very similar, they exhibit interestingly different behaviour. The SM rule is shown to produce a series of orders with more stable interval between orders but with more variable order quantities. Conversely, the LUC rule results in more stable order quantities but more variable order intervals. The study also reveals that addition of an appropriate amount of extra quantity to an order could significantly reduce order variability. With an increasing concern on the amplification of order variability in supply chains recently, the results provide interesting insights on the choice of lot sizing rules to be applied by a channel of a supply chain in determining ordering policies.
Buy this at Amazon
Product Features