Customized Pull Systems for Single-Product Flow Lines

Traditionally pull production systems are managed through classic control systems such as Kanban, Conwip, or Base stock, but this paper proposes ‘customized’ pull control. Customization means that a given production line is managed through a pull control system that in principle connects each stage of that line with each preceding stage; optimization of the corresponding simulation model, however, shows which of these potential control loops are actually implemented. This novel approach may result in one of the classic systems, but it may also be another type: (1) the total line may be decomposed into several segments, each with its own classic control system (e.g., segment 1 with Kanban, segment 2 with Conwip); (2) the total line or segments may combine different classic systems; (3) the line may be controlled through a new type of system. These different pull systems are found when applying the new approach to a set of twelve production lines. These lines are configured through the application of a statistical (Plackett-Burman) design with ten factors that characterize production lines (such as line length, demand variability, and machine breakdowns).Pull production / inventory;sampling;optimization;evolutionary algorithm

Stability of queueing-inventory systems with different priorities

We study a production-inventory system with two customer classes with different priorities which are admitted to the system following a flexible admission control scheme. The inventory management is according to a base stock policy and arriving demand which finds the inventory depleted is lost (lost sales). We analyse the global balance equations of the associated Markov process and derive structural properties of the steady state distribution which provide insights into the equilibrium behaviour of the system. We derive a sufficient condition for ergodicity using the Foster-Lyapunov stability criterion. For a special case we show that the condition is necessary as well

Resource and cost management

Educational lecture notes contains the fundamentals of a general theory of resource and cost management, classification of costs for decision-making, methods of constructing cost functions of the enterprise, analysis of the relationship between costs, volume and profits, the methods and systems of cost calculation, principles of cost management system. Designed for students directions 073 «Management» and 076 «Entrepreneurship, trade and exchange activity»

Scheduling a Make-To-Stock Queue: Index Policies and Hedging Points

A single machine produces several different classes of items in a make-to-stock mode. We consider the problem of scheduling the machine to regulate finished goods inventory, minimizing holding and backorder or holding and lost sales costs. Demands are Poisson, service times are exponentially distributed, and there are no delays or costs associated with switching products. A scheduling policy dictates whether the machine is idle or busy, and specifies the job class to serve in the latter case. Since the optimal solution can only be numerically computed for problems with several products, our goal is to develop effective policies that are computationally tractable for a large number of products. We develop index policies to decide which class to serve, including Whittle's "restless bandit" index, which possesses a certain asymptotic optimality. Several idleness policies, which are characterized by hedging points, are derived, and the best policy is obtained from a heavy traffic diffusion approximation. Nine sample problems are considered in a numerical study, and the average suboptimality of the best policy is less than 3%

Inventory Modelling for a Manufacturer of Sweets: An Evaluation of an Adjusted Compund Renewal Approach for B-Items With A Relative Short Production Lead Time

In this paper we are especially interested how to optimize the production/inventory control for a manufacturer of sweets, under the following circumstances: short production lead times in combination with an intermittent demand pattern for the so-called B-taste items. As for A-taste items a compound renewal approach appeared appropriate to control inventory/production, we formulated and tested an adjusted compound renewal approach for B-taste items, because a certain condition was not satisfied for those items. For several experiments where the condition was not satisfied and the adjusted approach was compared with the unadjusted one, it then appears that the difference in performance was small. So the first two moments with the compound renewal model appear to be more robust than the restriction given in the literature.production/inventory control;compound renewal demand processes