Browsing by Subject "Cost accounting"

Now showing 1 - 6 of 6

Open Access
Concurrent consideration of product design, process planning and production planning activities
(1998) Adil, Gajendra Kumar
In manufacturing engineering, product design, process planning and production planning activities are often considered independently. However, in order to effectively respond to changes in business situations, such as changes in demand forecast, product mix and technology, it is desirable to consider them concurrently. For this purpose, a large-scale linear programming model has been developed. The model considers minimization of the sum of processing cost, late shipment cost and inventory holding cost as the objective, and concurrently selects product designs, and generates process plans and production plans. The number of columns in the formulation can be large and, hence, an efficient column generation scheme is developed to solve the model. The model and solution procedure are illustrated with examples.
Open Access
Designing a road network for hazardous materials shipments
(Elsevier, 2007) Erkut, E.; Alp, O.
We consider the problem of designating hazardous materials routes in and through a major population center. Initially, we restrict our attention to a minimally connected network (a tree) where we can predict accurately the flows on the network. We formulate the tree design problem as an integer programming problem with an objective of minimizing the total transport risk. Such design problems of moderate size can be solved using commercial solvers. We then develop a simple construction heuristic to expand the solution of the tree design problem by adding road segments. Such additions provide carriers with routing choices, which usually increase risks but reduce costs. The heuristic adds paths incrementally, which allows local authorities to trade off risk and cost. We use the road network of the city of Ravenna, Italy, to demonstrate the solution of our integer programming model and our path-addition heuristic.
Open Access
Near-optimal modified base stock policies for the capacitated inventory problem with stochastic demand and fixed cost
(World Scientific Publishing, 2014) Özener, O. Ö.; Güllü, R.; Erkip, N.
In this study, we investigate a single-item, periodic-review inventory problem where the production capacity is limited and unmet demand is backordered. We assume that customer demand in each period is a stationary, discrete random variable. Linear holding and backorder cost are charged per unit at the end of a period. In addition to the variable cost charged per unit ordered, a positive fixed ordering cost is incurred with each order given. The optimization criterion is the minimization of the expected cost per period over a planning horizon. We investigate the infinite horizon problem by modeling the problem as a discrete-time Markov chain. We propose a heuristic for the problem based on a particular solution of this stationary model, and conduct a computational study on a set of instances, providing insight on the performance of the heuristic.
Open Access
The relationship between different price indexes: a set of evidence from inflation targeting countries
(I O S Press, 2006) Akdi, Y.; Berument, Hakan; Cilasun, S. M.; Olgun, H.
The possible long-run relationships between the Consumer Price Index and the Wholesale Price Index are analyzed for three inflation targeting countries - Canada, Sweden and the UK - using three different statistical techniques. The Engle-Granger test finds cointegration only for Sweden. The Johansen's test and the model-free and seasonality robust periodogram based test conclusively show that the two price indexes are not cointegrated in the three countries included in the sample. Hence, the values of these indexes may consistently diverge over time. However, the two price indexes move together in the short run. These findings have some implications for the success of inflation targeting monetary policies. © 2006 - IOS Press and the authors. All rights reserved.
Open Access
A simulation-based support tool for data-driven decision making: operational testing for dependence modeling
(IEEE, 2014) Biller, B.; Akçay, Alp; Çorlu, C.; Tayur, S.
Dependencies occur naturally between input processes of many manufacturing and service applications. When the dependence parameters are known with certainty, the failure to factor the dependencies into decisions is well known to waste significant resources in system management. Our focus is on the case of unknown dependence parameters that must be estimated from finite amounts of historical input data. In this case, the estimates of the unknown dependence parameters are random variables and simulations are designed to account for the dependence parameter uncertainty to better support the data-driven decision making. The premise of our paper is that there are certain cases in which the assumption of an independent input process to minimize the expected cost of input parameter uncertainty becomes preferable to accounting for the dependence parameter uncertainty in the simulation. Therefore, a fundamental question to answer before capturing the dependence parameter uncertainty in a stochastic system simulation is whether there is sufficient statistical evidence to represent the dependence, despite the uncertainty around its estimate, in the presence of limited data. We seek an answer for this question within a data-driven inventory-management context by considering an intermittent demand process with correlated demand size and number of interdemand periods. We propose two new finite-sample hypothesis tests to serve as the decision support tools determining when to ignore the correlation and when to account for the correlation together with the uncertainty around its estimate. We show that a statistical test accounting for the expected cost of correlation parameter uncertainty tends to reject the independence assumption less frequently than a statistical test which only considers the sampling distribution of the correlation-parameter estimator. The use of these tests is illustrated with examples and insights are provided into operational testing for dependence modeling.
Open Access
Tool magazine arrangement and operations sequencing on CNC machines
(Elsevier, 1996-02) Avcı, S.; Aktürk, M. S.
two-phase approach is developed to solve the tool magazine arrangement and operations sequencing problems. The overall aim is to minimize the total manufacturing cost by utilizing the benefits of tool sharing concept and loading duplicate tools due to a possible decrease in tooling and tool operating costs while maintaining the feasibility in terms of precedence, tool magazine capacity, tool life covering and tool availability constraints due to tool contention among the operations for a limited number of tool types, because the absence of such crucial constraints may lead to infeasible results. Furthermore, the proposed approach can provide an effective decision making tool for the short term operational decisions of FMS. Copyright © 1996 Elsevier Science Ltd