Türkay Dereli

Dynamic optimization of multipass milling operations via geometric programming

Abstract This paper outlines the development of an optimization strategy to determine the optimum cutting parameters for multipass milling operations like plain milling and face milling. The developed strategy is based on the “maximum production rate” criterion and incorporates eight technological constraints. The optimum number of passes is determined via dynamic programming, and the optimal values of the cutting conditions are found based on the objective function developed for the typified criterion by using a non-linear programming technique called “geometric programming”. This paper also underlies the importance of using optimization strategies rather than handbook recommendations as well as pointing out the superiority of the multipass over the single-pass optimization approach.

PROJECT TEAM SELECTION USING FUZZY OPTIMIZATION APPROACH

With their high potential, high motivation, great problem-solving ability and flexibility, project teams are important work structures for the business life. The success of these teams is highly dependent upon the people involved in the project team. This makes the project team selection an important factor for project success. The project team selection can be defined as selecting the right team members, which will together perform a particular project/task within a given deadline. In this article, an analytical model for the project team selection problem is proposed by considering several human and nonhuman factors. Because of the imprecise nature of the problem, fuzzy concepts like triangular fuzzy numbers and linguistic variables are used. The proposed model is a fuzzy multiple objective optimization model with fuzzy objectives and crisp constraints. The skill suitability of each team candidate is reflected to the model by suitability values. These values are obtained by using the fuzzy ratings method. The suitability values of the candidates and the size of the each project team are modeled as fuzzy objectives. The proposed algorithm takes into account the time and the budget limitations of each project and interpersonal relations between the team candidates. These issues are modeled as hard-crisp constraints. The proposed model uses fuzzy objectives and crisp constraints to select the most suitable team members to form the best possible team for a given project. A simulated annealing algorithm is developed to solve the proposed fuzzy optimization model. Software based on C + + computer programming language is also developed to experiment on the proposed model in forming project teams.

A survey on the methods and tools of concurrent new product development and agile manufacturing

Companies in either manufacturing or servicing have to be restructured or re-organized in order to overcome with challenges of the 21st century in which customers are not only satisfied but also delighted. In this competitive environment, organizations should use a flexible, adaptive and responsive paradigm that can be entitled by a unique term: agile manufacturing (AM). An AM system is able to develop a variety of product at low cost and in a short time period. For this, it has some of useful enabling technologies and physical tools. Among these, concurrent engineering (CE) is a systematic approach to the integrated, concurrent design of product and their related processes, including manufacture and support. It is then a useful and beneficial approach to reduce the development time and manufacturing cost, while simultaneously improving the quality of a product in order to better respond to the customer expectations. The aim of this study is to underline the synergistic impact of new product development (NPD) and CE, (which can be called CNPD), and to survey their methods and tools in association with the AM.

Optimisation of process planning functions by genetic algorithms

This paper introduces optimisation modules of a process planning system called OPPS-PRI (Optimised Process Planning System for PRIsmatic parts) which has been developed together with its interfaces to provide a complete CAD/CAM integration. Primary objective of this work is to develop an intelligent and integrated CAD/CAM system for shop-floor use that can be used by an average operator and to produce globally optimised results (process plans and part programs). For this purpose, in this work, an attempt has been made to include the impact and potential of artificial intelligence (AI) in process planning applications and to optimise all events in an integrated CAD/CAM environment. GAs were extensively used in the development of process planning facilities and in the optimisation issues, in order to include profits of AI techniques into the system.

A novel approach based on DEMATEL method and patent citation analysis for prioritizing a portfolio of investment projects

A novel approach is proposed for prioritizing a portfolio of investment projects.The proposed approach uses the DEMATEL method and patent citation analysis.The proposed approach reflects the governments perspective.A case study from Turkey is presented to demonstrate the proposed approach. The aim of this article is to propose a novel approach based on a method called Decision-Making Trial and Evaluation Laboratory (DEMATEL) and patent citation analysis for prioritizing the portfolio of investment projects. The proposed approach reflects the governments perspective and takes into account two important prioritization criteria. They are: (i) the decreasing rate of foreign trade deficits in the country and (ii) the potential to attract new investments which are not considered in the literature before. A case study from Turkey is presented to demonstrate the benefits of the proposed approach. The findings show that the proposed approach can be used easily and efficiently to prioritize investment projects among available project proposals.

Multi-criteria decision making methods based weighted SERVQUAL scales to measure perceived service quality in hospitals: a case study from Turkey

The main objectives of this study are to: (i) measure hospital service quality by using analytic hierarchy process (AHP) and analytic network process (ANP) as a multi-criteria decision making method to acquire the relationship and the level of the importance among service quality measurement (SERVQUAL) dimension; (ii) find perceived service quality with respect to different hospital classes (A, B and C) in Istanbul, Turkey; (iii) compare AHP- and ANP-based weighted SERVQUAL scales with the unweighted SERVQUAL scale for public hospital service quality in terms of different hospital classes (A–B and C). First, four hospitals are selected randomly for each class and then, a questionnaire based on the SERVQUAL model is conducted for each class to measure perceived service quality with respect to five major criteria, namely tangible, reliability, responsiveness, assurance and empathy, from patients’ viewpoints at hospitals. Next, the second questionnaire based on ANP is developed to evaluate the importance of criteria and construct the relations among the criteria. The study sample contains 281 outpatients totally. Three important findings are obtained in this study. First, there is a significant difference among different hospital classes regarding the perceived service quality. Second, according to the patients, the most important service quality dimensions are empathy, the knowledge of employees, sympathetic and reassuring employees, services provided at the time promised to do so, and safe feeling of patients in interactions with hospital employees. Thirdly, the, perceived service quality through the AHP- and ANP-based SERVQUAL scale is higher than that with the unweighted SERVQUAL scale.

A note on the use of STEP for interfacing design to process planning

This short note demonstrates the use of standard for exchange of product data (STEP) for interfacing design to process planning via a compact feature recogniser. The methodology used in development of the interface (feature recogniser) makes use of both automatic feature-recognition and feature-based design technologies in order to combine their advantages, and the STEP for the non-problematic and full information exchange. Using the abilities of the STEP, a generic configuration scheme is developed in which the features are treated as a combination of faces to which geometrical and/or technical information is glued (associated). By this way, the designer is only forced to identify the functional parts of the features when designing the part, which may simplify the component design and result in the effective memory utilisation. The feature recogniser was implemented in C on a PC and tested on a large number of examples with positive results.

An analysis of the papers published in Total Quality Management & Business Excellence from 1995 through 2008

In this article, a content analysis is performed for the papers that appeared in Total Quality Management and Business Excellence. A total of 1132 papers which appeared in the volumes from 6 to 19 are analysed into several different dimensions. Country origins and academic unit of authors (engineering/basic sciences/management sciences, etc.), research methods (library search/conceptual study/case study/simulation/field survey, etc.) and unit of analyses (individual/company/firm/regional/national/international level) are included in this analysis. In addition to those attributes, keywords of the papers and the content of case studies (manufacturing/service/information technology) are computed as well. Association mining has also been performed to determine the consequential relationships among the attributes.

Integration of Internet and web-based tools in new product development process

New product development is considered to be vital for a companys long-term survival. In todays rapidly changing production environments customers are asking for highly customised products with affordable prices. A new production era that is known as mass customisation has already started in many sectors. The customer should become an integral part of the product design process in such an environment. The integration of Internet and web-based tools for customer data collection, communication and data processing is inevitable in order to speed up the production process and cut down the costs. This paper deals with management of product development with focus on synthesising new technology based concepts related to product development, and discusses their use in the various stages of product development process. It also provides guidelines for successfully implementing technology oriented new product development practices with a customisation perspective.

OPPS-ROT: an optimized process planning system for rotational parts

Abstract This paper presents an optimised process planning system for rotational parts. The model of a part is drawn by using a CAD module prepared for this purpose. After the feature recognition module, machining operations are determined and the cutting tools are selected by using the knowledge base and machining topology. An optimum sequence of operations is found by minimising the number of tool changes and tool travelling distance to decrease the cost per operation. The optimum cutting conditions are determined and stored in a CAD/CAM data base, accordingly. The part programs are then automatically generated in standard ISO codes on the basis of specific CNC lathe controllers. The generated part programs as well as tool paths can also be verified by graphical simulation prior to actual machining. The system is intelligent and requires little manual intervention. It is implemented with C + + on a personal computer.