Moshe Eben-chaime - Academia.edu (original) (raw)

Papers by Moshe Eben-chaime

IV International Symposium on Applications of Modelling as an Innovative Technology in the Agri-Food-Chain: Model-IT, 2008

Springer eBooks, 2014

Quality is a principle issue in production management (PM). No process is perfect and the product... more Quality is a principle issue in production management (PM). No process is perfect and the production of defective items is unavoidable. Very few studies regard the effect of the existence of defective items (EEDI) in production processes. Further, quality has been studied in isolation to high extent, of other PM domains. In this study, defect rates together with the assembly ratios of the bill of material are embedded in process charts. This facilitates the analysis of the EEDI in assembly operations and enables to quantify them. Apparently, defect rates grow dramatically in assembly operations due to the mutual effects of the assembly's components. Hence prior quality assurance effort is motivated

Computers & Industrial Engineering, Apr 1, 1998

The machine interference queueing model has numerous applications in different areas. Yet it is s... more The machine interference queueing model has numerous applications in different areas. Yet it is seldom used due, mainly, to the complexity of the associated calculations. In this paper, a simple and easy-to-implement spreadsheet application of the model is presented. This application calculates state probabilities and mean values for key parameters: machine utilization, operators’ load and system throughput. The application is

International Journal of Production Economics, Aug 1, 1997

Most operations management studies of automatic warehousing systems investigate single-machine sy... more Most operations management studies of automatic warehousing systems investigate single-machine systems in isolation of the total system which includes other related functions. In this paper, we overcome these limitations and investigate an integrative model of a warehouse, ...

Management Science, Nov 1, 1996

Linear weighing is a common approach to handle multiple criteria and the “knapsack” is a well-kno... more Linear weighing is a common approach to handle multiple criteria and the “knapsack” is a well-known combinatorial optimization problem. A knapsack problem with two linearly weighted, objective criteria is considered in this paper. For better support, it is important to provide the decision maker with information that covers the whole range of alternatives. Toward this goal, an algorithm for the construction of a parametric solution to the problem, i.e., for any combination of weights, is developed, which is based on finding a longest path in a network which compactly represents all feasible solutions to the knapsack problem. Exploiting the special structure of the knapsack model, the algorithm efficiently constructs the parametric solution in time that is linear in the product of the number of variables, the resource limit (right-hand side of the constraint), and the (finite) number of vectors which constitute the solution. The amount of memory required is linear in the product of the number of variables and the resource limit. Results of computational study are reported. The results are used to assess the efficiency of the algorithm and characterize its behavior with respect to the parameter values.

Acta horticulturae, Dec 1, 2008

Production Planning & Control, 1995

04.pdf comprehension of a machine from ... We then considered the implications of this model for ... more 04.pdf comprehension of a machine from ... We then considered the implications of this model for hypermedia manual design by ... theory because its operation involves ...

International Journal of Computer Integrated Manufacturing, 1996

Automatic warehouses, for the most part, have been studied in isolation. This paper departs from ... more Automatic warehouses, for the most part, have been studied in isolation. This paper departs from this approach by proposing an integrative model in which warehouse activities interact with other functions of the total system. The model has been simulated under three modes of operation: Single command, dual command (DC), and hybrid. Simulation results confirm that the length of stay of unit loads outside the warehouse affects performance and also suggests that, under the DC mode, the warehouse may lose stability. Hence, the hybrid mode is proposed as an alternative. The hybrid mode outperforms the DC mode on most performance measures, except that the length of the storage queue at high throughput levels is longer. Finally, saving opportunities, via a reduction in the number of storage/ retrieval machines, are discussed.

Procedia CIRP, 2015

This work closes a knowledge gap, which hindered the exploration of the relationships between com... more This work closes a knowledge gap, which hindered the exploration of the relationships between complexity and quality in full. Recent decades are characterized by rapid technological progress, which has been followed by elevated product complexity. Many repercussions of this growing complexity have already been considered, but the work has not yet been completed and this study adds a significant contribution. While not the sole, the most straightforward expression of product's complexity level is the number of components, which are assembled to make this product-the more components, the higher the complexity. In serial manufacturing processes, each item moves individually, but items are joined together, serially or in parallel, in assemblies. There, mutual effects exist-a single defective component suffices to disqualify a whole assembled unit! Surprisingly, few studies have considered the effects of defective items on the production process. Particularly, there appears to be no study that quantifies these mutual effects among components which arrive from different sources with different defect rates. Thus, this study appears to be a first attempt to analyze and quantify these effects. Evidently, the mutual effects among their components amplify assemblies' defect rates dramatically, to the extent that defects due to common or random causes become significant. This hypothesis is supported by both the result of this study and field data from the industry. This is a price of advanced products-increased complexity which sets hurdles on the preservation of quality; a price that should be considered in the course of product design. However, the present analysis reveals that setting quality assurance activities just prior to assembly operations reduces the mutual effects among components. Consequently, process design can be used to overcome undesirable repercussions of increased product complexity, thereby increase the yield of the production process.

Quality and Reliability Engineering International, Mar 23, 2016

A central element of quality assurance is inspections. Inspections, however, are imperfect and pr... more A central element of quality assurance is inspections. Inspections, however, are imperfect and prone to errors. Devastating effects of inspection error type Irejection of conforming items, are considered in this note. When several inspections are performed along a serial process, the number of falsely rejected items is similar in magnitude to (or even larger than) the number of defective items. Moreover, to compensate for this loss, more units should enter the process and consequently, more units turn defective. The quality community seems to be unaware of these effects, certainly of the last one, despite their practical significance.

Journal of Manufacturing Systems, Jul 1, 2015

The focus of this study is a known and disturbing actual problem. The industry will soon celebrat... more The focus of this study is a known and disturbing actual problem. The industry will soon celebrate a century of quality awareness and efforts. Still, according to field data, many new products exit the manufacturing systems defective. This study proposes mutual effects among assembly's components as an explanation to this phenomenon-many defective new products. While each item in a serial manufacturing process moves individually, items are joined to others in assemblies. There, a single defective component suffices to disqualify a whole assembled unit! Surprisingly, few studies have focused on the repercussions of defective items on production. Particularly, there appears to be no study that quantifies these mutual effects of components which arrive from different sources with different defect rates. Thus, this study is also a first attempt to analyze and quantify these mutual effects. Apparently, the mutual effects of their components amplify the defect rates of assemblies dramatically, to the extent that defects due to common or random causes become significant.

Total quality management & business excellence, Apr 1, 2013

‘If we have quality problems and therefore a defect rate greater than zero, the total costs of pr... more ‘If we have quality problems and therefore a defect rate greater than zero, the total costs of production actually decrease.’ Furthermore, ‘although at first this might sound surprising, the decreasing total costs of production for poorer quality levels are to be expected.’ This was concluded in a paper published in this journal. In this note it is argued that this conclusion is misleading in suggesting that poor quality might be of economical advantage. The contrary is demonstrated – production costs actually grow dramatically due to poor quality.

Military Operations Research, 1996

Athens Journal of Business & Economics

In this short paper some common conventions regarding revenue curves are questioned and revenue i... more In this short paper some common conventions regarding revenue curves are questioned and revenue is contrasted with profit. It turned out that obeying the law of demand – non-increasing demand function, is insufficient to characterize the revenue curve. Non-increasing demand function may result in increasing and/or decreasing revenue curves, concave and/or convex revenue curve and even curves with multiple local extreme points. Fortunately, a sufficient condition is found, which enables to better characterize the revenue curve. Based on this result, it is shown that the quantity that maximizes the profit differs from the quantity that maximizes the revenue. Further, the difference can be substantial and the profit is more sensitive to quantity changes than the revenue. Keywords: demand, revenue, profit, firms

IISE Transactions, 2021

For this demonstration, the OPC of Figure 1 is used. Only the inspection of activity 2 is inactiv... more For this demonstration, the OPC of Figure 1 is used. Only the inspection of activity 2 is inactive, and it is assumed that arriving quality to the leaf operations, {10, 11, 13, 14}, is perfect. In the presence of a single OPC, the index k is omitted for convenience. In phase 1, Equation (1) is applied. It starts with activity 14, which is an operation.

Journal of dairy science, 2009

Engineering tools and mathematical optimization are applied in this study to plan the work of the... more Engineering tools and mathematical optimization are applied in this study to plan the work of the agents of the cow artificial insemination service (inseminator) in Israel. Time is crucial in insemination as the chances of conception decline with increasing delay between the start of estrus and insemination. About 1,090 artificial inseminations of cows are performed daily in Israel. They involve 412 farms in 283 villages, and are performed by 29 inseminators; the work plan should balance the work load among the inseminators. To this end, the working time of an inseminator in each village is required. Thus, a model to predict the working time in a village was developed. Subsequently, a mathematical optimization model was designed and solved, which aims to allocate customers to trips and to determine the itinerary of each trip to minimize total distance/time. The main benefits included a 21.4% reduction in total traveling time and a 55% reduction in the difference between the lengths ...

Proceedings of the International Conference on Industrial Engineering and Operations Management

No process is perfect and defective items are produced in any process, but in commercial operatio... more No process is perfect and defective items are produced in any process, but in commercial operations there are sales targets and/or orders to deliver. Therefore, a very basic rule is the compensation principle: a compensating unit must be produced for any defective unit. A common method for coping with defective items is to perform cleaning – inspect the items and remove defective units. Inspections however are error prone and the destructive effect of false rejections in serial processes is presented. In assemblies, there are mutual relationships among the components and the yield – the ratio of the number of conforming units to the total number of units diminishes very rapidly in the presence of defective components. Yet, it turns out that cleaning of defective assembly components prior to the assembly, improves quality and reduces waste simultaneously. Keywords—Assembly, defect rate, inspection errors, yield.