Ateekh Ur Rehman

Evaluation of reconfigured manufacturing systems: an AHP framework

The market dynamics are undergoing changes almost continuously and new technologies are emerging which lead to new generation machines. The concept of RMS, although started at the machine level, has now spread to almost all the components of the manufacturing systems. Emerging technologies in the form of machine tool, material handling, tooling, automation etc., guide the reconfiguration exercise. A number of configurations are considered while making the change, guided either by local factors or in rare cases, by optimisation models. The modifications identified are put to use with the hope that everything would be fine and as expected. This approach is risk prone as the system may later encounter different scenarios, which were not considered earlier. Therefore, unless the alternative configurations are evaluated and compared to assess the pros and cons of each alternative under different situations, one may not reap the potential benefit of the concept like RMS. The study reported in this paper attempts to extend help in this direction.

The evaluation of manufacturing systems using concordance and disconcordance properties

The organisations that are in pursuit of reconfigurations are often presented with a number of options and, hence, face the problem of evaluating the feasible alternative configurations before choosing the best one. The problem becomes more dominant if the conditions wanting reconfigurations change from time to time. There are a variety of factors which may either support or oppose a particular alternative. Therefore, there is a need for an appropriate methodology to evaluate the different configurations. This paper presents an approach for the assessment of alternative configurations using multiple criteria. This paper considers a manufacturing system which produces 30 products using different conventional machines and process plans for each product. This system is simulated using ProModel 6.2. Subsequently, eight different alternative configurations were developed and simulated, each under 24 experiments. The simulated results that pertain to 216 experiments were subjected to analyses to establish the competitiveness of the alternative configurations. For this, the Elimination and Choice-Translating Algorithm (ELECTRE) was used. The details of the simulation models, the analysis of the results, the ELECTRE approach and the drawn inference are presented in the paper.

A model to derive software maintenance policy decision

The problem of software maintenance is gaining considerable importance both for the user industry and the service providers. The area of equipment maintenance is very well developed one, but the same is not true for the software maintenance. In this paper, a model is developed and solved for deriving software maintenance decision. This model uses two criteria of maximum availability and minimum maintenance cost to make a decision between corrective maintenance and preventive maintenance. The model was used to obtain the appropriate maintenance policy and also for performing sensitivity analysis, the results of which are presented in this paper. The model presented in this paper has significant potential for application and further research.

Microchannels Fabrication in Alumina Ceramic Using Direct Nd:YAG Laser Writing

Ceramic microchannels have important applications in different microscale systems like microreactors, microfluidic devices and microchemical systems. However, ceramics are considered difficult to manufacture owing to their wear and heat resistance capabilities. In this study, microchannels are developed in alumina ceramic using direct Nd:YAG laser writing. The laser beam with a characteristic pulse width of 10 µs and a beam spot diameter of 30 µm is used to make 200 µm width microchannels with different depths. The effects of laser beam intensity and pulse overlaps on dimensional accuracy and material removal rate have been investigated using different scanning patterns. It is found that beam intensity has a major influence on dimensional accuracy and material removal rate. Optimum parameter settings are found using grey relational grade analysis. It is concluded that low intensity and low to medium pulse overlap should be used for better dimensional accuracy. This study facilitates further understanding of laser material interaction for different process parameters and presents optimum laser process parameters for the fabrication of microchannel in alumina ceramic.

Multi-criteria grey relational approach to evaluating reconfigurable manufacturing configurations

In response to highly dynamic markets, manufacturing industries need alternative feasible manufacturing strategies. The strategy currently adopted is to reconfigure the existing manufacturing system. The conditions to reconfigure existing configurations change from time to time. An attempt is made to identify and apply an approach to evaluate these configurations. The paper proposes a grey relational decision-making approach. The approach takes into account multiple performance measures. The ProModel 6.2 simulation platform is adopted to examine the performance of each feasible alternative manufacturing configuration.

Optimizing Fiber Parameters Coupled with Chemical Treatment: PROMETHEE Approach

In order to combat issues related to expansive soils, chemical stabilization augmented with use of synthetic fibers is gaining focus in recent times. However, in most of these applications, the practicing field engineers face difficulty in selecting the right mix of fiber size, fiber dosage and stabilizer content. The decision becomes more typical, as the target is to achieve or enhance multiple geotechnical properties which differ with fiber dosage and stabilizer content based on governing mechanisms. Addressing these issues, in this study an attempt is made to present an approach for selecting fibre dosage and lime mix for a typical expansive semi-arid soil. In this article, the effect of randomly oriented polypropylene fiber inclusion in enhancing various geotechnical properties of a typical expansive semi-arid soil is studied. The addition of lime is considered in order to ensure proper bonding between clay particles and discrete fiber elements. PROMETHEE is adopted in order to assist in multi-criteria decision-making process. The approach evaluates multiple geotechnical properties for possible alternatives viz., untreated soil; lime treated soil and other including combinations of fiber dosage and fiber size in the presence of lime. The response measures being the targeted geotechnical properties which include, linear shrinkage tests, unconfined compression strength test, California Bearing Ratio behavior, compressibility characteristics and hydraulic conductivity. The study revealed the best possible alternative considering all the selected response measures.

An approach to evaluating alternatives for wind power plant locations

Multi-criteria decision approaches are preferred for achieving multi-dimensional sustainable renewable energy goals. A more critical issue faced by the wind power industry is the selection of a location to tap prospective energy, which needs to be evaluated on multiple measures. In this paper, the aim is to assess and rank alternative wind power plant locations in Saudi Arabia. The approach presented here takes multiple criteria into consideration, such as wind speed, wind availability, site advantages, terrain details, risk and uncertainty, technology used, third party support, projected demand, types of customers, and government policies. A comparative analysis of feasible alternatives that satisfy all multi- criteria objectives is carried out. The results obtained are subjected to sensitivity analysis. Concepts such as ‘threshold values’ and ‘attribute weights’ make the approach more sensitive.

A multistage methodology catering to different failure modes for estimating the failure intensity of software: an empirical study

Managing and measuring software reliability is one of the important problems in the software industry. Software reliability measurement issue becomes complex where the software experiences multiple failure modes. In reality, the complexity involved in reliability computation is dependent upon several factors, among them the most relevant ones are related to the failure process and how the failure is corrected. A study conducted in a software company revealed that, while testing the software product, certain types of failures are corrected while the test program is in progress and the others are corrected only at the end of the test program. The company wanted to estimate the failure intensity and the overall mean time between failures, taking into account the realities of the business practice in vogue. A methodology was proposed to meet this requirement and was tested using the data provided by the company. The details of the method in terms of the steps involved and how the method was used are presented in this paper.