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Parallel Simulated Annealing Algorithms in Global Optimization

Onbaşoglu, E. | Özdamar, L.

Article | 2001 | Journal of Global Optimization19 ( 1 ) , pp.27 - 50

Global optimization involves the difficult task of the identification of global extremities of mathematical functions. Such problems are often encountered in practice in various fields, e.g., molecular biology, physics, industrial chemistry. In this work, we develop five different parallel Simulated Annealing (SA) algorithms and compare them on an extensive test bed used previously for the assessment of various solution approaches in global optimization. The parallel SA algorithms consist of various categories: the asynchronous approach where no information is exchanged among parallel runs and the synchronous approaches where soluti . . .ons are exchanged using genetic operators, or where solutions are transmitted only occasionally, or where highly coupled synchronization is achieved at every iteration. One of these approaches, which occasionally applies partial information exchanges (controlled in terms of solution quality), provides particularly notable results for functions with vast search spaces of up to 400 dimensions. Previous attempts with other approaches, such as sequential SA, adaptive partitioning algorithms and clustering algorithms, to identify the global optima of these functions have failed without exception Daha fazlası Daha az

Effects of different canal files on zip formation.

Kaptan, RFU | Yircali, UA

Conference Object | 2001 | JOURNAL OF DENTAL RESEARCH80 ( 4 ) , pp.1287 - 1287

Uncertainty Modelling in Software Development Projects (With Case Study)

Özdamar, L. | Alanya, E.

Article | 2001 | Annals of Operations Research102 ( 01.04.2020 ) , pp.157 - 178

A project scheduling model tailored specifically for software development projects is proposed in this study. The model incorporates uncertainties related to activity durations and network topology. The first type of uncertainty exists due to error-prone coding which might result in elongated task durations caused by validation and debugging sessions. Furthermore, in practice, macro-activities represent groups of sub-tasks in order to simplify the planning and monitoring of the project. Due to the aggregation, it is more difficult to be precise on the duration of a macro-activity. The uncertainty related to the network topology is d . . .ue to common database design issues or program modules shared among parallel tasks in the project network. These tasks become associated with each other through uncertain Start-to-Start (SS) precedence relationships. On the other hand, SS lags may also be the outcome of technological precedence relationships among pairs of activities. However, the imprecision underlying the work content of a predecessor activity leads to uncertain SS lags. Software development projects are human-intensive projects and hence, the duration of a task depends on the skill of the person assigned to the job as well as his/her learning rate. Thus, a task may be realized by alternative staff members which results in different expected task durations. Hence, a realistic model proposed for software development projects should incorporate staff assignment features under the uncertainties discussed above. In this study, we develop a mathematical model for software development projects and propose heuristic solution methods to be used by the project co-ordinator in preparing the project plan. The heuristic algorithms developed here are tested on real data provided by a consulting firm undertaking software development projects from manufacturing companies in Turkey Daha fazlası Daha az

Photophysical properties of 5H-dibenzo[a,d]cycloheptene in solution

Bayrakçeken, Fuat | Jomehri, B.B. | Yaman, A.

Article | 2001 | Journal of the Indian Chemical Society78 ( 5 ) , pp.234 - 236

A number of photophysical properties of 5H-dibenzo[a,d]cycloheptene have been measured including the decay parameters of the lowest excited singlet and triplet states. Molecules were excited in a two-step process. In the first step, S1 is created which undergoes intersystem crossing to T1, then T-T absorption creates an excited triplet molecule which returns to the first excited singlet level by intersystem crossing. The recreated first excited singlet state decays back to the ground state by emitting B-type of delayed fluorescence.

Comparison of serum and bronchoalveolar lavage fluid sialic acid levels between malignant and benign lung diseases

Isitmangil, T. | Isitmangil, G. | Budak, Y. | Aydilek, R. | Celenk, M.K.

Article | 2001 | BMC Pulmonary Medicine1 , pp.234 - 236

Background: It is known that tissue and serum sialic acid levels may be altered by malignant transformation. In this study, sialic acid levels were determined in bronchoalveolar lavage fluid (BAL) and serum in two groups of patients with lung cancer and non-malignant diseases of the lung. Methods: Colorimetric methods were used for determination sialic acid in serum and in BAL samples. Flexible bronchoscopy was used to obtain the latter. Results: Sialic acid levels in bronchoalveolar lavage fluid and serum did not show any statistically significant difference between subjects with malignant and the non-malignant lung diseases (p > 0 . . ..05). Sialic acid levels were also unrelated to the stage and localization of the tumor (p > 0.05). Conclusions: Sialic acid levels do not appear to be a good marker for discriminating malignant from non-malignant diseases of the lung. © 2001 Isitmangil et al; licensee BioMed Central Ltd Daha fazlası Daha az

Electronic spectra and excited state properties of triptycene in solution

Bayrakçeken, Fuat | Yaman, A.

Article | 2001 | Journal of the Indian Chemical Society78 ( 6 ) , pp.298 - 300

Absorption, emission and some excited state lifetimes are measured at room temperature and at 77 K in solution. B-Type delayed fluorescence decay time is reported for the first time for triptycene. The results are compared with the findings of photolysis, flash photolysis and laser flash photolysis experiments.

Nickel and Chromium Levels in the Saliva and Serum of Patients with Fixed Orthodontic Appliances

Agaoglu, G. | Arun, T. | Izgü, B. | Yarat, A.

Article | 2001 | Angle Orthodontist71 ( 5 ) , pp.375 - 379

The aim of this study was to evaluate the concentrations of nickel and chromium ions in salivary and serum samples from patients treated with fixed orthodontic appliances. A second aim of this study was to determine any significant changes in these concentrations during any period of the treatment time. Saliva and blood samples were collected from 100 patients ranging in age from 12 to 33 years. Twenty samples from each group were obtained. The groups were as follows: In the first group, saliva and blood samples were collected before insertion of the fixed appliances. In the second, third, fourth, and fifth groups, samples were coll . . .ected at 1 week, 1 month, 1 year, and 2 years after appliance insertion. The serum was prepared by centrifuging the blood samples at 3000 rpm for 10 minutes. The fixed appliances consisted of an average of 4 bands and 20 bonded brackets. No palatal or lingual appliances welded to bands or extraoral auxiliary appliances were used. The spectrophotometric determinations were carried out using electrothermal atomic absorption spectrophotometry. The results indicated certain differences in the amounts of nickel and chromium released from fixed orthodontic appliances during different periods of treatment. The Mann-Whitney U-test from the SPSS statistics program was used to analyze the significance of the differences between no-appliance samples and those obtained with the appliances present. In the serum, there were statistically significant increases in ion concentration in the second-year groups. In saliva samples, nickel and chromium reached their highest levels in the first month and decreased to their initial level in the rest of the groups. It can be concluded that fixed orthodontic appliances release measurable amount of nickel and chromium when placed in the mouth, but this increase doesn't reach toxic levels for nickel and chromium in the saliva and serum Daha fazlası Daha az

A cross-cultural study of managerial work values in Singapore

Dicle, I.A. | Dicle, U.

Article | 2001 | Journal of Asia-Pacific Business3 ( 1 ) , pp.63 - 82

Integrating expert knowledge in environmental site characterization

Demirhan, M. | Özdamar, L.

Article | 2001 | IEEE Transactions on Systems, Man and Cybernetics Part C: Applications and Reviews31 ( 3 ) , pp.344 - 351

The site characterization issue is the most essential task to be undertaken prior to the reclamation of a potentially contaminated site and it is composed of sampling, laboratory analysis, and data evaluation phases. We are primarily concerned with the data evaluation phase and we utilize a recently developed adaptive areal partitioning algorithm to characterize the site. Here, we enhance this approach by integrating expert knowledge (expert belief) into the fuzzy areal assessment scheme which derives information from sample data. We propose to allocate an adaptive weight to expert belief during the assessment. We compare the belief . . .-integrated approach with the nonintegrated one on synthetically generated sites where both uniform and biased sampling have been applied independently. In biased sampling, the zones claimed to be highly contaminated (by the expert) are allocated a higher sampling density. We demonstrate that the belief-integrated approach outperforms the nonintegrated one both when the expert is correct or mistaken in his/her judgment irrespective of the sampling methodology Daha fazlası Daha az

Derivation of low-sensitivity current-mode CCII-based filters

S. Özoguz | C. Acar | A. Toker | E.O. Güneş

Article | 2001 | IEE Proceedings: Circuits, Devices and Systems148 ( 3 ) , pp.115 - 120

Two transformation methods for obtaining new topologies from a given current-mode CCII filter are presented. These topologies realise the same transfer function as the initial filter for ideal CCIIs, but they can be derived in such a way that their active sensitivity with respect to a particular active parameter becomes zero. In this way, from a filter suffering from large active sensitivities, one may systematically obtain new filters with better active sensitivities.

Comparison of partition evaluation measures in an adaptive partitioning algorithm for global optimization

Özdamar, L. | Demirhan, M.

Article | 2001 | Fuzzy Sets and Systems117 ( 1 ) , pp.47 - 60

An 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 par . . .titions. 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 Daha fazlası Daha az

Porcelain inlays and onlays.

Gürel, G.

Article | 2001 | Dental clinics of North America45 ( 1 ) , pp.47 - 60

Dentistry has been witness to tremendous changes in technology, introducing new techniques and materials. New procedures are being performed faster, are more reliable, are painless, and are more esthetic. These changes not only have been extremely motivational for dentists, but also for patients. Patients are aware that esthetic approaches in dentistry can change one's appearance, and are coming to the dentist willingly.

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