Y. Nukman

A hybrid approach for fuzzy multi-attribute decision making in machine tool selection with consideration of the interactions of attributes

Global economic competition has spurred the manufacturing sector to improve and invest in modern equipment to satisfy the needs of the market. In particular, machine tool selection is the most important problem; it plays a primary role in the improvement of productivity and flexibility in the manufacturing environment and involves the imprecise, vague and uncertain information. This paper presents the hybrid approach of the fuzzy ANP (Analytic Network Process) and COPRAS-G (COmplex PRoportional ASsessment of alternatives with Grey relations) for fuzzy multi-attribute decision-making in evaluating machine tools with consideration of the interactions of the attributes. The fuzzy ANP is used to handle the imprecise, vague and uncertain information from expert judgments and model the interaction, feedback relationships and interdependence among the attributes to determine the weights of the attributes. COPRAS-G is employed to present the preference ratio of the alternatives in interval values with respect to each attribute and calculate the weighted priorities of the machine alternatives. Alternatives are ranked in ascending order by priority. As a demonstration of the proposed model, a numerical example is implemented based on the collected data and the literature. The result is then compared with the rankings provided by other methods such as TOPSIS-G, SAW-G and GRA. Moreover, a sensitivity analysis is conducted to verify the robustness of the ranking. The result highlights that the hybrid approach of the fuzzy ANP and COPRAS-G is a highly flexible tool and reaches an effective decision in machine tool selection.

State of the Art of the Concurrent Engineering Technique in the Automotive Industry

In this article a study of state of the art of the concurrent engineering technique in the automotive industry is presented. The importance and benefits of concurrent engineering in automotive industry are highlighted. The study in the areas of concurrent engineering tools, especially the information technology tools such as finite element analysis, computer-aided design and expert systems, is carried out. The use of concurrent engineering techniques in the development of the automotive engine and transmission, chassis and body is finally described.

Laser Lap Joining of Dissimilar Materials: A Review of Factors Affecting Joint Strength

Laser joining of dissimilar materials has been the subject of intensive studies in the past decade or thereabout. This is mainly due to the several benefits it offers when used to manufacture various electromechanical components for automotive, aerospace, electronics, and biomedical applications. There are many possible variations of joining dissimilar materials; this article, however, considers the main engineering materials in use today, namely, metal, polymer, ceramic, glass, and silicon. The strength of the joints determined by, inter alia, the material combinations, joining technique, and material treatment is crucial for the above mentioned applications if safety and reliability requirements are to be adhered to. Undoubtedly, the challenges posed by such complex selection of materials and process factors are unquantifiable and as such have been given a critical review in this article. The relationship between some important laser processing parameters and joint strength are also discussed. Furthermore, it has been observed that the joint strength can also be influenced by factors such as bubbles morphology, material preparation/treatment, depth of molten pool and formation of chemical bonds, and intermetallic phases and their effects are also reviewed and discussed. This article is concluded with an outlook providing the summary and key findings of the authors.

An Integrated Approach of Fuzzy Linguistic Preference Based AHP and Fuzzy COPRAS for Machine Tool Evaluation

Globalization of business and competitiveness in manufacturing has forced companies to improve their manufacturing facilities to respond to market requirements. Machine tool evaluation involves an essential decision using imprecise and vague information, and plays a major role to improve the productivity and flexibility in manufacturing. The aim of this study is to present an integrated approach for decision-making in machine tool selection. This paper is focused on the integration of a consistent fuzzy AHP (Analytic Hierarchy Process) and a fuzzy COmplex PRoportional ASsessment (COPRAS) for multi-attribute decision-making in selecting the most suitable machine tool. In this method, the fuzzy linguistic reference relation is integrated into AHP to handle the imprecise and vague information, and to simplify the data collection for the pair-wise comparison matrix of the AHP which determines the weights of attributes. The output of the fuzzy AHP is imported into the fuzzy COPRAS method for ranking alternatives through the closeness coefficient. Presentation of the proposed model application is provided by a numerical example based on the collection of data by questionnaire and from the literature. The results highlight the integration of the improved fuzzy AHP and the fuzzy COPRAS as a precise tool and provide effective multi-attribute decision-making for evaluating the machine tool in the uncertain environment.

Enhancement and Prediction of Heat Transfer Rate in Turbulent Flow Through Tube With Perforated Twisted Tape Inserts: A New Correlation

An experimental investigation has been carried out for turbulent flow in a tube with perforated twisted tape inserts. The mild steel twisted tape inserts with circular holes of different diameters (i.e., perforation) are used in the flow field. An intensive laboratory study is conducted for heat transfer and pressure drop characteristics in the tubes for turbulent flow with various airflow rates. Heat transfer and pressure drop data are engendered for a wide range Reynolds number (1.3 × 10 4 ―5.2 × 10 4 ). Tube wall temperature, pressure drop, air velocity and its temperature are measured both for plain tube and for tube with perforated twisted tape inserts. Heat transfer coefficients, Nusselt number, pumping power, and heat transfer effectiveness are calculated for both cases. Experimental results showed that perforated twisted inserts of different geometry in a circular tube enhanced the heat transfer rate with an increase in friction factor and pumping power for turbulent flow. The pumping power, heat transfer coefficient, and effectiveness in the tube with the twisted tape inserts are found to increase up to 1.8, 5.5, and 4.0 times of those for the plain tube for same Reynolds number, respectively. Finally, a correlation is developed for prediction of the heat transfer rate for turbulent flow through a circular tube with perforated twisted tape inserts.

A Review of Manufacturing Resources Planning Models Under Different Uncertainties: State-of-The-Art and Future Directions

The main purposes of this paper are to enhance the understanding of manufacturing resources planning models under uncertain conditions by documenting the current state of affairs, and to stimulate a fruitful future research direction by identifying gaps between the relevant issues and the literature available in reputable journals. This paper is a comprehensive and up-to-date review of the existing literature on manufacturing resource planning models under uncertainty. The authors have found that the combined effects/ impacts of the uncertainty factors on the system parameters have yet to be thoroughly studied. So far no research has been conducted into developing mathematical model(s) to study the uncertainty issues holistically in multi-period, multiple product, and multi-stage environments for manufacturing resources planning in association with commonality. OPSOMMING Die primere doel van hierdie artikel is om die insig in vervaardigingshulpbronbeplanning onder onsekerheid te bevorder. Die huidige stand van sake word ondersoek en gapings word uitgewys aan die hand van literatuur beskikbaar in gesaghebbende joernale. Die outeurs bevind in die studie dat die sisteemparameters en die invloed van onsekerheid daarop nog nie voldoende bestudeer is nie. Geen navorsing is nog onderneem om wiskundige modelle te ontwikkel om op holistiese wyse die impak van onsekerheid in multi-periode, veelvoudige produk en multi-stadium omgewing te bestudeer nie.

Concurrent Decisions on Design Concept and Material Using Analytical Hierarchy Process at the Conceptual Design Stage

There is an increased study for considering the precise decisions on the design concept (DC) and material concurrently at the early stage of development of product. Inappropriate decisions on DC and material always lead to huge cost involvement and ultimately drive toward premature component or product failure. To overcome this problem, concurrent engineering (CE) is an approach which allows designers to consider early decision making (EDM) need to be implemented. To illustrate the use of CE principle at the early stage of design process, a concept selection framework called concurrent DC selection and materials selection (CDCSMS) was proposed. In order to demonstrate the proposed CDCSMS framework, eight DC s and six different types of composite materials of automotive bumper beam have been considered. Both of these decisions were then verified by performing various scenarios of sensitivity analysis by using analytical hierarchy process through utilizing Expert Choice software.

A Fuzzy Logic-Based Prediction Model for Kerf Width in Laser Beam Machining

In laser beam machining, the main concern is the machining quality as kerf width of the end product. It is essential for industrial applications to cut the workpiece with minimum kerf width. However, it is difficult to develop a precise functional relationship between input and output variables in laser machining. Therefore, an effort has been conducted to build up an intelligent fuzzy expert system (FES) model to predict the kerf width in CO2 laser cutting. The employed input parameters were assisting gas pressure, laser power, cutting speed, and standoff distance. The fuzzy logic was performed on fuzzy toolbox in MATLAB R2009b by employing Mamdani technique. In total, 81 experiments were carried out and experimental results were used for training and testing of the developed fuzzy model. Relative error and goodness of fit were used to investigate the accuracy of the prediction ability and the values of 3.852% and 0.994, respectively, were found to be satisfactory. This paper will extend knowledge about the prediction of kerf width by using FES model.

Application of Taguchi method to analyse the impacts of common process and batch size in multistage production system under uncertain conditions

The work desires: 1) to determine the optimum level of batch size in bottleneck facility; 2) to analyse the effect of common processes on throughput and cycle time in a multistage production system under machine breakdown and quality uncertainty. In this research, the authors developed simulation models for multistage production system under common processes in an uncertain situation created by machine breakdown and quality variation. Few simulation models are developed based on a live case from a company. The models are verified and validated with the historical data from the company and by face validity. Taguchi approaches for orthogonal array are used in designing experiments. The experimental settings are executed in WITNESS, a simulation package. It is observed that the variation in level of common process in the system has significant impact on the production quantity and cycle time. There is strong interaction among the common process and the batch size in lancing stations. The production quantity is elevated and cycle time is least when the batch size in bottleneck facility is 12 and two common processes are used. [Received 27 October 2009; Revised 4 February 2010; Revised 11 May 2010; Accepted 14 May 2010]

An Integrated MCDM Model for Conveyor Equipment Evaluation and Selection in an FMC Based on a Fuzzy AHP and Fuzzy ARAS in the Presence of Vagueness

The conveyor system plays a vital role in improving the performance of flexible manufacturing cells (FMCs). The conveyor selection problem involves the evaluation of a set of potential alternatives based on qualitative and quantitative criteria. This paper presents an integrated multi-criteria decision making (MCDM) model of a fuzzy AHP (analytic hierarchy process) and fuzzy ARAS (additive ratio assessment) for conveyor evaluation and selection. In this model, linguistic terms represented as triangular fuzzy numbers are used to quantify experts’ uncertain assessments of alternatives with respect to the criteria. The fuzzy set is then integrated into the AHP to determine the weights of the criteria. Finally, a fuzzy ARAS is used to calculate the weights of the alternatives. To demonstrate the effectiveness of the proposed model, a case study is performed of a practical example, and the results obtained demonstrate practical potential for the implementation of FMCs.