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Lot Size (lot + size)

Distribution by Scientific Domains

Business, Economics, Finance and Accounting	33%

Selected Abstracts

Optimal manufacturer's pricing and lot-sizing policies under trade credit financing

INTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 6 2006
Jinn-Tsair Teng
Abstract In this paper, we extend Goyal's economic order quantity (EOQ) model to allow for the following four important facts: (1) the manufacturer's selling price per unit is necessarily higher than its unit cost, (2) the interest rate charged by a bank is not necessarily higher than the manufacturer's investment return rate, (3) the demand rate is a downward-sloping function of the price, and (4) an economic production quantity (EPQ) model is a generalized EOQ model. We then establish an appropriate EPQ model accordingly, in which the manufacturer receives the supplier trade credit and provides the customer trade credit simultaneously. As a result, the proposed model is in a general framework that includes numerous previous models as special cases. Furthermore, we provide an easy-to-use closed-form optimal solution to the problem for any given price. Finally, we develop an algorithm for the manufacturer to determine its optimal price and lot size simultaneously. [source]

Production to order and off-line inspection when the production process is partially observable

NAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 8 2007
Abraham Grosfeld-Nir
Abstract This study combines inspection and lot-sizing decisions. The issue is whether to INSPECT another unit or PRODUCE a new lot. A unit produced is either conforming or defective. Demand need to be satisfied in full, by conforming units only. The production process may switch from a "good" state to a "bad" state, at constant rate. The proportion of conforming units in the good state is higher than in the bad state. The true state is unobservable and can only be inferred from the quality of units inspected. We thus update, after each inspection, the probability that the unit, next candidate for inspection, was produced while the production process was in the good state. That "good-state-probability" is the basis for our decision to INSPECT or PRODUCE. We prove that the optimal policy has a simple form: INSPECT only if the good-state-probability exceeds a control limit. We provide a methodology to calculate the optimal lot size and the expected costs associated with INSPECT and PRODUCE. Surprisingly, we find that the control limit, as a function of the demand (and other problem parameters) is not necessarily monotone. Also, counter to intuition, it is possible that the optimal action is PRODUCE, after revealing a conforming unit. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007 [source]

Resource allocation with lumpy demand: To speed or not to speed?

NAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 3 2004
Bintong Chen
Abstract In the classical EPQ model with continuous and constant demand, holding and setup costs are minimized when the production rate is no larger than the demand rate. However, the situation may change when demand is lumpy. We consider a firm that produces multiple products, each having a unique lumpy demand pattern. The decision involves determining both the lot size for each product and the allocation of resources for production rate improvements among the products. We find that each product's optimal production policy will take on only one of two forms: either continuous production or lot-for-lot production. The problem is then formulated as a nonlinear nonsmooth knapsack problem among products determined to be candidates for resource allocation. A heuristic procedure is developed to determine allocation amounts. The procedure decomposes the problem into a mixed integer program and a nonlinear convex resource allocation problem. Numerical tests suggest that the heuristic performs very well on average compared to the optimal solution. Both the model and the heuristic procedure can be extended to allow the company to simultaneously alter both the production rates and the incoming demand lot sizes through quantity discounts. Extensions can also be made to address the case where a single investment increases the production rate of multiple products. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004. [source]

Agglomeration Economies, Division of Labour and the Urban Land-rent Escalation: A General Equilibrium Analysis of Urbanisation

AUSTRALIAN ECONOMIC PAPERS, Issue 2 2002
Guang-Zhen Sun
A general equilibrium model with increasing return to labour specialisation and economies of transaction agglomeration is developed to address the residential land-rent escalation associated with the urbanisation process, which is in turn endogenised as a result of the evolution of the division of labour. The interplay among the geographical pattern of transactions, trading efficiency and the network size of the division of labour plays a crucial role in our story of urbanisation. We show that: as transaction conditions are improved, the equilibrium level of division of labour and individuals specialisation levels increase; the urban land-rent increases absolutely as well as relative to that in the rural area, the relative per capita lot size of residence in the urban and rural areas decreases; the diversity of occupations in the urban area and the population share of urban residents increase; and the productivity of all goods and per capital real income increase. [source]

A comparative simulation study of work processes in autonomous production cells

HUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 1 2002
Christopher Schlick
An approach to human-centered design and assessment of work processes in flexible manufacturing systems with the help of dynamic task networks is presented. To model and simulate the task networks, the method of timed colored Petri Nets is used. Two task networks are developed. The first task network is a model of work processes in Autonomous Production Cells (APCs). The second task network represents work processes in conventional Computer Numerically Controlled (CNC)-based manufacturing systems. The material processing technology is associated with 5-axis milling. The values of attributes of task elements were acquired empirically on a fine-grained level with reference to a sample milling order. Comparative hypotheses regarding time-on-task, supervisory control functions, levels of cognitive control, human error (HE), and labor division were then formulated. To test these hypotheses, several simulation experiments were conducted. The results from inferential statistics show that single-operator APCs have a 30% higher efficiency in relation to total time-on-task. Moreover, the level of cognitive control is significantly shifted toward rule- and knowledge-based behavior. Surprisingly, the simulation of minor HE does not demonstrate a significantly worse performance from APCs. A simulated labor division among central process planner and production operator allows an additional efficiency improvement of approximately 15%. However, the labor division has two important drawbacks: first, a sequential incompleteness of operators' task spectrum occurs; second, the operator has to cope with hierarchical task incompleteness. Finally, a sensitivity analysis was carried out to investigate the effects of varying lot sizes and number of processed orders. © 2002 John Wiley & Sons, Inc. [source]