AXSIS (Yeditepe Üniversitesi)
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Comparison of partition evaluation measures in an adaptive partitioning algorithm for global optimization
No full textAn adaptive partitioning algorithm with random search is proposed to locate the global optimum of multimodal functions. Partitioning algorithms divide the feasible region into nonoverlapping partitions in order to restrict and direct the search to the most promising region expected to contain the global optimum. In such a scheme a partition evaluation measure is required to assess sub-regions in order to re-partition the most promising sub-region and intensify the search within that area. This study provides computational results on several classes of partition evaluation measures used in the assessment of samples taken from all partitions. Among the partition evaluation classes used in our comparison are fuzzy, statistical, and deterministic interval estimation measures. Performance in terms of solution quality is reported on an extensive set of 77 test functions collected from the literature.The Yeditepe University Open Access System is a compendium of indexed publications. Copyright and usage rights may be held by publishers and/or authors. The collection was established for the scientific publications prepared by Yeditepe University academicians and is to be found in the institutional archive
A simulation game to analyze impact of information technologies on supply chain management
No full textThe impact of information technologies on the functions of the firms and on the supply chain management was studied using simulation game. The effects of the information technologies used in order processing, inventory management, advertisement, and purchasing business processes were also investigated. The basic parameters of the firm to see the effects of these information technologies are procurement decision, inventory management, demand forecast, fulfillments, and net income.The Yeditepe University Open Access System is a compendium of indexed publications. Copyright and usage rights may be held by publishers and/or authors. The collection was established for the scientific publications prepared by Yeditepe University academicians and is to be found in the institutional archive
Fundamental noise studies in flame atomic magneto-optic rotation and atomic absorption spectrometry
No full textA study of inherent noise sources present in a purpose built flame atomic magneto-optic rotation (AMOR) spectrometer system was carried out with a view to identifying their sources. Two different optical configurations were employed, a crossed polariser and a 45° offset polariser configuration. The offset polariser configuration was operated in both an AMOR and atomic absorption (AA) mode for the noise measurements. Two main interference frequencies were found to occur in all the optical measurement modes. An interference flame feature frequency (15.5 Hz -39.0 Hz) which arose from an organ-pipe effect in the gas flow through the flame cooling sheets. The second interference frequency (at 100 Hz) was thought to arise due to modulation of the analytes magneto-optic properties due to ripple on the electromagnet d.c. power supply. Photon noise and fluctuation noise were found to be present as background noise. The fluctuation noise was dominant at higher analyte concentrations. The characteristics and origins of fluctuation noise are discussed and investigated for each measurement mode. The noise spectra of the conventional AA measurements were compared with those of the contemporary AMOR measurements, to ascertain any differences in noise power spectra which may affect the signal-to-noise ratio.The Yeditepe University Open Access System is a compendium of indexed publications. Copyright and usage rights may be held by publishers and/or authors. The collection was established for the scientific publications prepared by Yeditepe University academicians and is to be found in the institutional archive
Nth-order lowpass current transfer function synthesis using CCII based unity gain current followers
No full textA new filter circuit is proposed for the realisation of nth-order lowpass current-mode transfer function with unity gain by the active-RC circuit containing a minimum number of capacitors, n resistors and n+1 current conveyors. All of the current conveyors are either of the inverting or the noninverting type and they act as unity gain current followers. This makes the proposed circuit simple and attractive for current-mode operation.The Yeditepe University Open Access System is a compendium of indexed publications. Copyright and usage rights may be held by publishers and/or authors. The collection was established for the scientific publications prepared by Yeditepe University academicians and is to be found in the institutional archive
Evaluation of the Slope of the Articular Eminence and the Transverse Angle of the Glenoid Fossa in an Anatolian Population
No full textThe purpose of this study was to compare a computer-aided method specially programmed for the measurement of the posterior angle of the articular eminence with formerly used methods, to investigate the angulation differences at different depths of slices, and to evaluate correlation with the transverse angulation. Three slices (central, medial, and lateral) at various depths of the glenoid fossa belonging to 64 dry skulls and two measurement methods were used In this study. The angulation of the articular eminence were measured and the transverse angle of each fossa calculated. No statistical difference was found between the articular eminence results of the two methods. According to the results, the one factor ANOVA central slice was found to be statistically steeper than the other two slices (p<0.05) (central = 60.33 ± 10.19, medial = 58.26 ± 8.6, lateral 5828 ± 10.1). No correlation was found between the transverse angle of the inclination of the posterior slope angulation. It was concluded that the computer-aided method is more reliable and accurate and is much easier to use when compared to the manual method. An additional important finding of this study is that the inclination of the articular eminence should be evaluated at various depths of the temporomandibular joint
MaROS: A virtual processing environment for mobile hosts
No full textComputing and communications are inherently more complex for mobile users, who must contend with less reliable network connections and limited power resources. To compensate for this, the programmers need application development platforms that adequately and transparently handle the functionality and limitations of the resources available on the mobile device. During the lifetime of a mobile application, resource constraints of the machine change. Because of these constraints, system facilities that are provided in traditional computing environments, such as dependence on static resources and continuous connectivity, cannot be relied on. This article is a report on MaROS system, a virtual processing environment for mobile machines. MaROS offers a recoverable and relocatable object infrastructure that facilitates the dynamic division of responsibilities between mobile client and a fixed mobile service provider. The communication model provides reliable disconnected operations and virtual ports. The system also has the ability to recover its current state after a voluntary shutdown.The Yeditepe University Open Access System is a compendium of indexed publications. Copyright and usage rights may be held by publishers and/or authors. The collection was established for the scientific publications prepared by Yeditepe University academicians and is to be found in the institutional archive
A note on a partitioning algorithm for global optimization with reference to Tang's statistical promise measure
No full textThis note briefly describes a partitioning algorithm (FRACTOP) for global optimization, which, in the search for the global optimum of simple bounded multimodal functions, evaluates nonoverlapping partitions of the feasible region by random search. Fuzzy measures are used in the assessment of samples taken from all partitions, and the partition with the highest tendency of containing the global optimum is repartitioned to refine the search in that region. The performance of FRACTOP where fuzzy measures are imbedded is compared with a statistical promise measure proposed by Tang. Computational results are reported on an extensive set of 77 test functions collected from the literature. © 2000 IEEE.The Yeditepe University Open Access System is a compendium of indexed publications. Copyright and usage rights may be held by publishers and/or authors. The collection was established for the scientific publications prepared by Yeditepe University academicians and is to be found in the institutional archive
A fuzzy areal assessment approach for potentially contaminated sites
No full textThis article describes a new fuzzy areal site assessment approach in the detection of contaminated zones within a site which is under environmental investigation. Conventional techniques utilized in this field are mostly interpolation based. These methods interpolate the contaminant concentration values at unobserved locations using observed values. Unlike these interpolation techniques, the motivation of the approach introduced here consists of partitioning a given site into smaller sections. Partitioning is carried out iteratively where subregions of interest are divided into further smaller regions. This re-partitioning scheme leads to a dynamic grouping of observations, since areas of differing sizes and boundaries contain different sets of samples. The potential of an area to contain contaminated zones is assessed by a fuzzy measure which converts the data values in that area into an aggregate grade normalized on [0, 1]. Thus, this approach does not assume concentration values at unobserved locations, rather, an areal potential is evaluated. (C) 2000 Elsevier Science Ltd. All rights reserved.The Yeditepe University Open Access System is a compendium of indexed publications. Copyright and usage rights may be held by publishers and/or authors. The collection was established for the scientific publications prepared by Yeditepe University academicians and is to be found in the institutional archive
Experiments with new stochastic global optimization search techniques
No full textIn this paper several probabilistic search techniques are developed for global optimization under three heuristic classifications: simulated annealing, clustering methods and adaptive partitioning algorithms. The algorithms proposed here combine different methods found in the literature and they are compared with well-established approaches in the corresponding areas. Computational results are obtained on 77 small to moderate size (up to 10 variables) nonlinear test functions with simple bounds and 18 large size test functions (up to 400 variables) collected from literature. Scope and purpose Global optimization techniques aim at identifying the global optimum solution of a function which need not be convex or differentiable. In this paper, we consider stochastic global optimization search techniques. Among them, one can name probabilistic search methods such as simulated annealing, genetic algorithms, controlled random search and clustering methods. Another class of global optimization methods considered here are adaptive partitioning algorithms which aim at reducing the search space around the global optimum by consecutive partitioning iterations of a promising subregion into smaller and smaller subspaces. Here, we specifically investigate simulated annealing, clustering methods and adaptive partitioning algorithms. Besides implementing some well-established techniques in these fields, we develop new techniques which also lead to hybrid methods combined with existing ones. In an adaptive partitioning algorithm proposed here a new partition evaluation measure of fuzzy nature is developed. Furthermore, both simulated annealing and random search are used for collecting samples in the adaptive partitioning algorithm. We conduct a study on an extensive set of test problems and compare the performances of these algorithms. (C) 2000 Elsevier Science Ltd. All rights reserved.; In this paper several probabilistic search techniques are developed for global optimization under three heuristic classifications: simulated annealing, clustering methods and adaptive partitioning algorithms. The algorithms proposed here combine different methods found in the literature and they are compared with well-established approaches in the corresponding areas. Computational results are obtained on 77 small to moderate size (up to 10 variables) nonlinear test functions with simple bounds and 18 large size test functions (up to 400 variables) collected from literature.The Yeditepe University Open Access System is a compendium of indexed publications. Copyright and usage rights may be held by publishers and/or authors. The collection was established for the scientific publications prepared by Yeditepe University academicians and is to be found in the institutional archive
New floating FDNR circuit using differential voltage current conveyors
No full textA new floating FDNR circuit is proposed using two differential voltage current conveyors and a minimum number of passive elements. Since passive elements are all grounded, this circuit is suitable for fully integrated circuit design. Moreover it does not require any element matching condition. It has a good sensitivity performance due to tracking errors. Finally the proposed FDNR circuit can be controlled through a grounded resistor.The Yeditepe University Open Access System is a compendium of indexed publications. Copyright and usage rights may be held by publishers and/or authors. The collection was established for the scientific publications prepared by Yeditepe University academicians and is to be found in the institutional archive