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Papers by Gadi Rabinowitz

SIAM Review, 2000

ABSTRACT We propose a globally convergent method for the numerical solution of a class of continu... more ABSTRACT We propose a globally convergent method for the numerical solution of a class of continuous nonlinear knapsack problems arising, e.g., in chemical production service facilities.

ISSM 2005, IEEE International Symposium on Semiconductor Manufacturing, 2005., 2005

ABSTRACT The purpose of this article is to define and quantify the bubble phenomenon in a semicon... more ABSTRACT The purpose of this article is to define and quantify the bubble phenomenon in a semiconductors fab. A "local bubble" is a relatively acute local and temporal WIP congestion. The local bubble is empirically identified and its impact on the local cycle time distribution is assessed. We then estimate its marginal impact on the overall line cycle time and cost. Finally, a novel visualization of the bubble progression is proposed

Journal of the Chinese Institute of Industrial Engineers, 1999

A new form of partial backorder policy (PB2) using two explicit backorder control limits and a in... more A new form of partial backorder policy (PB2) using two explicit backorder control limits and a intermediate time when dealing with shortages is introduced and parameterc analyses of various cost parameters of this policy are numerically explored. The traditional backorder policy, the lost sales policy, and a partial backorder policy using a single backorder control limit, called PB1, are special cases of PB2; hence a PB2 policy provides a unified frame work for studying different policies dealing with shortages. We provide an example where a PB2 policy produces a cost savings of 3.36% over the best of the pure backorder, the lost sales and the PB1 policies. Without the time dependent backorder cost, our PB2 policy will reduce to the PB1 policy. A cost savings of 6.63% is realized. This cost savings could be quite substantial for a firm with very large volume of business.

Quality and Reliability Engineering International, 2001

The reliability of a multi-attribute deteriorating production system is controlled using versatil... more The reliability of a multi-attribute deteriorating production system is controlled using versatile identical inspection facilities. An attribute state is dichotomous (up designates proper function versus down). A product item is conforming if all the system attributes are up when it is produced. When a system attribute is detected as down it is restored back to an up state. Inspection of an attribute can rely on observations of the system, recently produced items, or both. Inspection policy determines the inspection capacity, frequency of inspecting each attribute and inspection schedule. These decisions involve a tradeoff between the cost of inspectors and the loss associated with the proportion of non-conforming items due to lack of adequate inspection. Three models are introduced, analyzed and solved. In the first model, inspection and restoration are perfect, product attribute is up (down) when the system attribute is up (down), and restoration is immediate. The assumptions of perfect inspection and restoration are relaxed in the second model. The third model relaxes in addition the assumption of immediate restoration. An efficient heuristic solution scheme is provided for solving these models. Sensitivity of the solution to system parameters is studied. Numerical experiments provide some insights regarding the combined effect of imperfect production, inspection and restoration, in various conditions of inspection and restoration durations. assumptions were made by most of the authors: each inspection facility can be allocated to only one attribute; the rate of defects generation in each attribute is fixed over time; and the loss from shipping non-conforming items is proportional to their fraction. The last assumption is in contrast with practical experience (see ) that suggests a convex dependency due to loss of goodwill and market share. These assumptions explain the fixed inspection allocation policy and the irrelevancy of inspection schedule and process quality control by the works surveyed by the above-mentioned reviews. On [12, p. 161], possible inspection and test strategy problems in flow lines are discussed. They develop a variety of stochastic models for manufacturing systems, some of which involve inspection. Yet, conforming to the preceding literature, they do not mention or model the use and schedule of inspection for detecting malfunction production attributes.

Omega, 1988

Abstract This paper suggests a conceptual scheme to represent the knowledge base of Management Sc... more Abstract This paper suggests a conceptual scheme to represent the knowledge base of Management Science/Operations Research (MS/OR). Such a scheme could be utilized within the framework of a Decision Support System (DSS). Its purpose is to facilitate ...

Management Science, 1988

An optimal decision and control model was developed and used for dual purpose allocation of water... more An optimal decision and control model was developed and used for dual purpose allocation of water from a reservoir. The model was constructed for the Hazbani-Dan Water System in the Upper Galilee (Israel). In this system about half of the Dan River water enters and is stored in a reservoir and is then released via a 70'' pipe either to

Management Science, 1992

A two-stage decision and control model for the operation of the power station in the Hazbani-Dan ... more A two-stage decision and control model for the operation of the power station in the Hazbani-Dan Water System (Israel) was developed and implemented. In this system, river water is stored and then either consumed by agricultural farms or released to a hydroelectric power station. Under management policy, agricultural consumption is taken as a constraint. The problem was solved via a

Journal of Water Resources Planning and Management, 1991

International Journal of Production Research, 2003

ABSTRACT One would expect a continuous production planning and control system to be more sensitiv... more ABSTRACT One would expect a continuous production planning and control system to be more sensitive to information inaccuracy than a periodic one. In practice, a major source of information inaccuracy is the updating rate of the perceived system state. This phenomenon is particularly significant in global firms that must employ appropriate technology and procedures for updating the corporate information throughout its branches. The study compares 'Push' and 'Pull' strategies for production planning and control under different updating rates for inventory information. For this purpose, we propose a Pull control mechanism for an environment characterized by inaccurate information. Then we construct a simulation model for a specific flow-shop production process that can be controlled by either the Pull or Push approach. The simulation results show a significant domination of the Pull strategy over Push. The results confirm that the Pull approach protects the flow of materials against machine and market variations, which were known, and also against a lack of information, which is new. The Pull strategy is less sensitive to the information updating rate since it smoothes the materials' flow and thus the inventory information gaps (known versus actual) are much smaller.

International Journal of Production Economics, 1996

Previous research on the newsboy problem is based on the assumption that in case of a shortage, u... more Previous research on the newsboy problem is based on the assumption that in case of a shortage, unsatisfied demand is lost. Such an assumption is inappropriate for items that have a close substitute. In this paper, we formulate a two-item newsboy problem with substitutability (TINPS). Upper and lower bounds on the optimal order quantities of the two items are derived. Since analytical solutions to the problem are difficult to obtain, a Monte Carlo simulation is used to identify the optimal solution to the TINPS. Order quantities identified by the simulation provide higher expected profit than would have been obtainable without considering substitutability.

The International Journal of Advanced Manufacturing Technology, 1995

This paper presents a two-stage model for industrial robot operation and selection in a multi-pro... more This paper presents a two-stage model for industrial robot operation and selection in a multi-product manufacturing system. The quality of the production process is related to robot repeatability and the output rate is related to robot speed. Robot repeatability deteriorates with increased speed. In the second stage, a one-period robot operational model maximises the expected profit of a risk-neutral decision maker, leading to optimal robot speed and production quantity decisions. Using the optimal speeds and quantities of the operational model and taking into account demand uncertainties, the first stage robot selection model is solved.

IIE Transactions, 2011

ABSTRACT This article proposes a stochastic attention allocation and reactive scheduling model to... more ABSTRACT This article proposes a stochastic attention allocation and reactive scheduling model to prevent illegal border crossings. To intercept infiltrators, a limited pool of security agents is dynamically assigned to heterogeneous frontier segments that transmit erratic signals of crossing attempts by independent trespassers. The frontier segments may differ in terms of rates of crossing attempts, ease of crossing, and reliability of the detection systems. Due to the huge complexity of the agent scheduling decision, a relaxed Markovian model is proposed whose solution is a set of optimal steady-state allocation rates for sending security agents to any frontier segment where a crossing attempt is apparently taking place. This solution is used to derive a heuristic policy for dispatching security agents among the frontier segments based on the evolving signals. Simulation experiments demonstrate that the proposed heuristic outperforms other scheduling policies. Border crossing is just one example of a viable application for this attention allocation model, which can be extended and customized for a wide variety of other scenarios.