JOURNAL OF INDUSTRIAL ENGINEERING INTERNATIONAL
Year:2009 | Volume:5 | Issue:9|Papers Count:8

The revenue management concept and techniques are applied to model the coordination of supply chain elements. The fundamental premise of this approach is synchronization of a group of business entities consisting of a manufacturer and multiple suppliers to achieve an optimal supply chain capacity plans. The output of the supply chain can be various products and thus it is measured in terms of capacity. In our paper, the demand is stochastic. As a result, the chain faces uncertainty when it comes to determine the volume of contract between manufacturer and suppliers. The model developed in this paper provides the basis for long-term contracts between manufacturer and its supply network for coordinated and non-coordinated supply relationship. It also provides decision rules to increase flexibility in responding to consumer demand shifts without cost overlays in resource utilization, while increasing the overall capacity utilization and market share. The collaboration framework versus independency of supply chain members is introduced to investigate the rules for competition through optimal demand management and capacity allocation. An important result is that the models are robust, as they are independent of demand distribution function. We also study the effect of a supplier who supplies two competitive chains on capacity and price basis. Our analysis of supply-chain shows that at the presence of uncertainty of demand collaborative chains are more robust to capacity reservation plan comparing to independent identities as far as capacity is concerned. The robustness of a supply network to support the chain leader (manufacturer) is also measured and the trade off for sustainable network is proposed.

This paper discusses the performance evaluation and availability analysis of ammonia synthesis unit of a fertilizer plant. The fertilizer plant is a complex and repairable engineering system comprises of various units viz. shell gasification and carbon recovery, desulphurization, co-shift conversion, decarbonation, nitrogen wash and ammonia synthesis etc. One of the most important functionaries of a fertilizer plant is ammonia synthesis unit. This unit consists of five subunits arranged in series and parallel configurations. For the evaluation of performance and analysis of availability, a performance evaluating model has been developed with the help of mathematical formulation based on Markov Birth-Death process using probabilistic approach. The findings of this paper are therefore, considered to be useful for the analysis of availability and determination of the best possible maintenance strategies in a fertilizer plant concerned.

Multivariate Process Capability Indices (MPCI) show how well a manufacturing process can meet specification limits when quality characteristics enclose a relative correlation. Process capability is an important and commonly used metric for assessing and improving the quality of a production process. When quality characteristics of a product are correlated then an attractive comes close to MPCI methods, which are not usually an easy task to carry out. In this investigation after a full reviewing of the MPCI, a simple method to estimate product capability indices based on ridge regression models in the presence of priority for quality characteristics is presented. The technique is demonstrated for evaluation of product capability through the use of an example which shows performance of the proposed method.

In this paper, an attempt has been made to investigate the reflectance of various colours and effects of varying colours on human working and production. Different colours have different reflectance and energy associated with it. Colours play a significant role in the colour scheme of the houses, offices, factories etc. The colours may be seen on walls, tabletops, equipment, machines etc. In the experiment, assembly shops of electric meter and plastic toys were selected for study. Four experiments were conducted with different colours and observations taken for eyestrain and production. The significant effects were noticed on the effects of colours. Colours not only improve the aesthetic value of the product or the facility, but also affect human working and hence, productivity.

Product mix problem (PMP) is one of the most important and complicated problems in production systems. Different approaches have been applied to solve this problem, among them, theory of constraints (TOC) has been widely considered since 1990s. This paper develops a distinguished algorithm to solve product mix problems that is efficient both in single and multi-bottleneck problems. At first, the new algorithm uses a mathematical model to aggregate different priorities assigned to products by different bottlenecks and finds an initial solution. Then tries to improve the solution by solving a set of linear inequalities. It is shown that the new approach obtains better solutions than the previous algorithms.

This paper gives a new application of DEA to evaluate the scheduling solutions of parallel processing. It evaluates the scheduling solutions of parallel processing using the non-convex DEA model, FDH model. By introducing each solution of parallel processing scheduling as a DMU with some relevant inputs and outputs this paper shows that how the most efficient schedule(s) can be identified.

This paper will investigate the optimum portfolio for an investor, taking into account 5 criteria. The mean variance model of portfolio optimization that was introduced by Markowitz includes two objective functions; these two criteria, risk and return do not encompass all of the information about investment; information like annual dividends, S&P star ranking and return in later years which is estimated by using data from a longer history. Thus portfolio selection is a typical multi-objective decision making (MODM) problem. It is well known that Goal Programming (GP), based on preemptive priorities and target values, has been successful in solving MODM problems. In this paper we rank objectives of the MODM model according to weights elicited from Decision Maker’s (DM) preferences. Then we obtain goals from DM’s opinion. As a guidance for DM, we revise these goals consistent with ranking of objectives by a Linear Programming model in a way that new goals remain as close as possible to DM’s goals. After obtaining the goals we solve our MODM problem by a Lexicographic Goal Programming (LGP) model which is constructed by prioritizing objectives. Finally we illustrate our proposed LGP model by a numerical example.

Rice Husk Ash (RHA) is natural Pozzolan containing reactive silica and/or aluminum. When the material is mixed with lime in powdered form and in the presence of water, it will set and harden like cement. This work uses Osadebe’s optimization model to optimize the shear modulus of concrete made from RHA. The strengths predicted by the model are in good agreement with their corresponding experimentally obtained values. With the model, any desired strength of hardened concrete, given any mix proportions, is easily evaluated. The average Poisson ratio and mean shear strength for the concrete are found to be 0.26 and 5.5 N/mm2 respectively.