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Publication Metadata only Bearing fault detection via wavelet packet decomposition with spectral post processing(IEEE, 2007) Eren, Levent; Teotrakool, Kaptan; Devaney, Michael J.; Bahcesehir University; University of Missouri System; University of Missouri ColumbiaWe present a method for detecting motor bearing fault conditions via wavelet packet decomposition (WPD) of induction motor current. This method involves the decomposition of motor current into equally spaced frequency bands by using all pass implementation of Elliptic IIR half-band filters in the filter bank structure to obtain wavelet packet coefficients (WPC). Then, the bias in WPCs for each frequency band is removed to suppress leakage from adjacent frequency bands. Fourier analysis is applied to wavelet packet coefficients to provide higher frequency resolution within each frequency band. The changes in the energy levels of frequency bands in which motor fault related current frequencies lie are monitored to detect motor fault conditions.Publication Metadata only On state reduction of incompletely specified finite state machines(PERGAMON-ELSEVIER SCIENCE LTD, 2007) Goren, Sezer; Ferguson, F. Joel; Bahcesehir University; University of California System; University of California Santa CruzState reduction of incompletely specified finite state machines (ISFSMs) is an important task in optimization of sequential circuit design and known as an NP-complete problem. Removal of redundant states reduces the logic, because of this, chip area decreases. In addition, test generation is easier when the sequential circuit is irredundant. In this paper, we present a heuristic for state reduction of ISFSMs. The proposed heuristic is based on a branch-and-bound search technique and identification of sets of compatible states of a given ISFSM specification. We have obtained results as good as the best exact method in the literature but with significantly better run-times. (c) 2006 Elsevier Ltd. All rights reserved.Publication Metadata only The impact of market orientation on NSD and financial performance of hospital industry(EMERALD GROUP PUBLISHING LTD, 2008) Lonial, Subhash C.; Tarim, Mehves; Tatoglu, Ekrem; Zaim, Selim; Zaim, Halil; Bahcesehir University; University of Louisville; Marmara University; Fatih UniversityPurpose - The principal aim of this study is to determine the critical factors of market orientation (MO) and to measure its effect on new service development (NSD) and financial performance of hospital industry in Turkey. Design/methodology/approach - Drawing on a self-administered questionnaire, the data were collected from a sample of privately-held general hospitals within the city of Istanbul in Turkey. Based on theoretical considerations, a model was proposed to examine the interrelationships among MO, NSD-performance and financial performance. Findings - Data analysis reveals that while MO has a strong and positive effect on NSD-performance, it has no significant effect on financial performance. Also a strong and positive relationship was noted between NSD-performance and financial performance. Finally, the findings also provided evidence for the mediating role of NSD-performance in. the relationship between MO and financial performance in the hospital industry. Research limitations/implications - First, due to relatively small sample size, a caution should be exercised when interpreting the results. Second, the data were collected from hospitals in Turkey, which may restrict to some extent generalizability of findings. Third, we relied on the subjective evaluations of senior, executives. It would therefore be useful to replicate the results with objective measures of performance indicators. Practical implications - Although there is compelling evidence that MO has a positive effect on business performance, it alone may not be able to produce superior performance. Many hospitals are committed to MO and new services development. The framework clearly indicates that a strong commitment to both the NSD-performance and marketing areas is essential for improving the financial performance of hospitals. Also, to remain competitive in today's healthcare industry, hospital managers should all keep pace with the daily changes in the market place and stay attuned to NSD activities and quality management practices. Originality/value - The main thrust of this study is to investigate whether the relationship between MO and financial performance is mediated by NSD-performance in hospital industry. This constitutes the novelty of this research as most prior empirical research investigating a mediating mechanism through which MID affects firm performance largely focused on other factors with no or little emphasis being placed on NSD activities or NSD-performance in healthcare context.Publication Metadata only A direct-sequence spread-spectrum communication system for integrated sensor microsystems(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2005) Aydin, N; Arslan, T; Cumming, DRS; University of Edinburgh; University of GlasgowSome of the most important challenges in health-care technologies have been identified to be development of noninvasive systems and miniaturization. In developing the core technologies, progress is required in pushing the limits of miniaturization, minimizing the costs and power consumption of microsystems components, developing mobile/wireless communication infrastructures and computing technologies that are reliable. The implementation of such miniaturized systems has become feasible by the advent of system-on-chip technology, which enables us to integrate most of the components of a system on to a single chip. One of the most important tasks in such a system is to convey information reliably on a multiple-access-based environment. When considering the design of telecommunication system for such a network, the receiver is the key performance critical block. The paper describes the application environment, the choice of the communication protocol, the implementation of the transmitter and receiver circuitry, and research work carried out on studying the impact of input data characteristics and internal data path complexity on area and power performance of the receiver. We provide results using a test data recorded from a pH sensor. The results demonstrate satisfying functionality, area, and power constraints even when a degree of programmability is incorporated in the system.Publication Metadata only TQM and market orientation's impact on SMEs' performance(EMERALD GROUP PUBLISHING LTD, 2006) Demirbag, Mehmet; Koh, S. C. Lenny; Tatoglu, Ekrem; Zaim, Selim; University of Sheffield; Bahcesehir University; Fatih UniversityPurpose - The principal aim of this study is to determine the impact of market orientation (MO) and implementation of total quality management (TQM) on organizational performance of SMEs. Design/methodology/approach - Based on theoretical considerations, a model is proposed linking the MO and TQM constructs to the organizational performance construct. Exploratory and confirmatory factor analyses empirically verified and validated the underlying dimensions of MO, TQM and organizational performance. Structural equation modeling was employed to test the model drawing on a sample of 141 SMEs operating in the Turkish textile industry. Findings - Data analysis reveals that, while MO has a strong and positive impact on the extent of TQM implementation, it has no significant impact on organizational performance. Similarly, a strong and positive relationship was noted between the level of TQM implementation and organizational performance. It has also been found that the MO has a positive and significant impact on organizational performance through only a mediating role of TQM implementation. Research limitations/implications, - The data were collected from textile manufacturers in Turkey, which may restrict to some extent generalizability of findings to other industries or firms operating in more stable environments. Given the limitations associated with perceptual measures, findings should be interpreted with some degree of caution. Finally, an implementation of alternative scales on the same sample would provide further insights into the causal links between MO, TQM and organizational performance Practical implications - SMEs should consider TQM as a facilitating management tool for improving organizational performance in relatively more dynamic environments. Market-oriented SMEs may not realize an increased performance gains with a successful MO implementation but, when TQM is implemented alongside MO, better financial performance can be achieved. As increasing number of SMEs are being involved in global markets, a double track approach (MO at business level and TQM implementation at functional level) to improve product and management quality becomes inevitable. Originality/value - A triangulation of MO, TQM and organizational performance outperforms two-way relationship of MO and organizational performance. Direct and indirect effect of each construct on organizational performance was discovered. SMEs should consider TQM as having a mediating role to improve organizational performance under a given set of market orientation.Publication Metadata only Hybrid analytical hierarchy process model for supplier selection(EMERALD GROUP PUBLISHING LTD, 2008) Sevkli, Mehmet; Koh, S. C. Lenny; Zaim, Selim; Demirbag, Mehmet; Tatoglu, Ekrem; Fatih University; University of Sheffield; Bahcesehir UniversityPurpose - This paper aims to propose a new approach called analytical hierarchy process weighted fuzzy linear programming model (AHP-FLP) for supplier selection. Design/methodology/approach - A hybrid method of supplier selection, AHP-FLP is applied to a real industry case. The weights of the various criteria, taken as local weights from a given judgment matrix, are calculated using analytical hierarchy process (AHP) that are also considered as the weights of the fuzzy linear programming model. This new model is compared with the classical AHP method. Findings - This study concluded that the AHP-FLP method outperforms the AHP method for supplier selection with respect to restricted supplier selection criteria. Drawing on a real case, Supplier 1 was identified to be the best supplier through the AHP model under no restrictions, which contradicts the finding that Supplier 2 was selected as the best supplier by the AHP-FLP model subject to constraints. Research limitations/implications - More research is definitely called for within the context of studying a more complex supply chain with multiple supply network and nodes. There is also a crucial need for investigating other hybrid methods to find the optimum supplier. Practical implications - The findings of this study indicate that the weights of supplier selection criteria calculated by the AHP-FLP model are in line with the actual supplier selection decision of purchasing managers. Since the AHP-FLP model is relatively more difficult to implement compared with the crisp AHP, its application will be more appropriate for high-value components where stringent purchasing criteria are required. In contrast, AHP remains an appropriate approach for relatively lower value components (C class). Originality/value - The novelty of this study lies in the application of a hybrid approach to a real industry case. This study has dealt with one of the most important subjects in supply chain management, providing a better decision for supplier selection using appropriate quantitative techniques.Publication Metadata only The impact of supply chain management practices on performance of SMEs(EMERALD GROUP PUBLISHING LTD, 2007) Koh, S. C. Lenny; Demirbag, Mehmet; Bayraktar, Erkan; Tatoglu, Ekrem; Zaim, Selim; University of Sheffield; Bahcesehir University; Bahcesehir University; Fatih UniversityPurpose - The purpose of this study is to determine the underlying dimensions of supply chain management (SCM) practices and to empirically test a framework identifying the relationships among SCM practices, operational performance and SCM-related organizational performance with special emphasis on small and medium size enterprises (SMEs) in Turkey. Design/methodology/approach - Data for the study were collected from a sample of 203 manufacturing SMEs operating in the manufacture of fabricated metal products and general purpose machinery (NACE codes 28 and 29) within the city of Istanbul in Turkey. The research framework was tested using partial least squares method, which is a variance-based structural equation modeling approach. Findings - Based on exploratory factor analysis (EFA), SCM practices were grouped in two factors: outsourcing and multi-suppliers (OMS), and strategic collaboration and lean practices (SCLP). The results indicate that both factors of SCLP and OMS have direct positive and significant impact on operational performance. In contrast, both SCLP and OMS do not have a significant and direct impact on SCM-related organizational performance. Also, as the direct relationship between the two performance-constructs was found significant, both factors of SCM practices have an indirect and significant positive effect on ORG through OPER. Research limitations/implications - Perhaps, the most serious limitation of this study was its narrow focus on Turk ish manufacturing SMEs, thus precluding the generalization of findings to other emerging countries as well as other sectors such as service and government sectors that may benefit from a sound SCM strategy. Practical implications - By developing and validating a multi-dimensional construct of SCM practices and by exhibiting its value in improving operational performance of SMEs, it provides SCM managers with useful tool for evaluating the efficiency of their current SCM practices. Second, the analysis of the relationship between SCM practices and operational performance indicates that SCM practices might directly influence operational performance of SMEs. Originality/value - This paper adds to the body of knowledge by providing new data and empirical insights into the relationship between SCM practices and performance of SMEs operating in Turkey.Publication Metadata only Systems dynamics modelling of a manufacturing supply chain system(ELSEVIER SCIENCE BV, 2007) Ozbayrak, Mustafa; Papadopoulou, Theopisti C.; Akgun, Melek; Bahcesehir University; Brunel University; Maltepe UniversitySupply chains are multifaceted structures focusing on the integration of all the factors involved in the overall process of production and distribution of end products to the customers. Growing interest in supply chain systems has highlighted the need to adopt appropriate approaches that can ensure the efficient management of their complexity, enormity and broadness of scope. With the main aim of supply chain management being to optimise the performance Of Supply chains, attention is mainly drawn to the development of modelling frameworks that call be utilised to analyse and comprehend the dynamic behaviour of supply chains. While there have been only a few supply chain modelling attempts reported in the literature, this paper proposes a modelling framework that is used to simulate the operation of a supply chain network of moderate complexity. The proposed model comprises four echelons and is build around a central medium-sized manufacturing company operating as a typical Make-to-Order (MTO) system. The developed model was built using a systems dynamics (SD) approach. The operations performed within a supply chain are a function of a great number of key variables which often seem to have strong interrelationships. The ability of understanding the network as a whole, analysing the interactions between the various components of the integrated system and eventually supplying feedback without decomposing it make systems dynamics ail ideal methodology for modelling supply chain networks. The objective of the paper is to model the operation of the supply chain network under study and obtain a true reflection of its behaviour. The modelling framework is also used to study the performance of the system under the initial conditions considered and compare it with that obtained by running the system under eight different scenarios concerning commonly addressed real-life operational conditions. The modelling effort has focused oil measuring the supply chain system performance ill terms of key metrics such as inventory, WIP levels, backlogged orders and customer satisfaction at all four echelons. The study concludes with the analysis of the obtained results and the conclusions drawn from contrasting the system's performance under each investigated scenario to that of the benchmark model. (c) 2007 Elsevier B.V. All rights reserved.Publication Metadata only Novel information-theoretic clustering algorithm for robust, unsupervised classification(IEEE, 2007) Temel, Turgay; Aydin, Nizamettin; Fatih University; Bahcesehir UniversityA new information-theoretic, unsupervised, subtractive clustering algorithm is proposed. The algorithm eliminates threshold constraint to detect possible cluster members. Cluster centers are formed with minimum entropy. Instead of using a fixed-threshold, a decision region is formed with the use of maximum mutual information. Cluster members are chosen with a relative-cost assigned in partitions of data set. The algorithm yields more reliably distributed cluster numbers in statistical sense, hence reducing further computation for validation, which is justified for a set of synthetic data.Publication Metadata only Full-information rate distance-4 block codes(IEEE, 2006) Altay, Goekmen; Ucan, Osman Nuri; Altay, Nejla; Bahcesehir University; Istanbul UniversityA new linear block code construction technique is proposed [1]. It generates all the even codes of length greater than 8 with full information rate for Hamming distance-4. The codes generated by the proposed method include the extended Hamming codes and the Reed Muller codes of distance-4. The generator matrix has useful properties such as lowest density, quasi-cyclic and regular.
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