In this study, we investigate degradation of ZnO varistors and their effects on electronic boards... more In this study, we investigate degradation of ZnO varistors and their effects on electronic boards. We propose a model showing how the varistor clamping voltage Vv changes by time for different stress levels. To evaluate the model, we exploit measured experimental test data as well as field return data with over 1000 board failures. Varistors in-use are usually subjected to a long-term AC or DC voltage stress and surge which may lead to degradation of the varistors with an increase of the Vv parameters. We show that degraded varistors cause dramatic failures of other components in the same power block of the electronic board. We perform experiments on varistor degradation and failing mechanisms by applying 8/20 us, 2ms and accelerated AC voltage test methodologies. We also simulate the relation of the varistor degradation with other components in time domain. istors. The tests show us a continuous and fast decreasing trend in the Vv parameter for current levels above a certain thresh...
Springer Tracts in Nature-Inspired Computing, 2021
The truss sizing optimization problem, where the cross-sectional areas of truss members are optim... more The truss sizing optimization problem, where the cross-sectional areas of truss members are optimized, is a nonlinear and complex problem. The problem becomes quite challenging especially when a large number of variables exist. Metaheuristics proved to be working efficiently for this problem type. Flower pollination algorithm (FPA) is a recently developed metaheuristic search algorithm, and it has been successfully applied to structural optimization problems in the literature. In this paper, the formulation of FPA is enhanced to improve its local and global searching capabilities for better performance. For this purpose, a hybrid algorithm is developed by imitating the algorithmic structure of FPA while the mutation and crossover operators of differential evolution (DE) with elitism strategy are replaced with Levy flights of FPA to explore search space more efficiently and exploitation ability of FPA is improved with the addition of mutation factor and crossover operator of DE working in the local search formula of FPA. The performance of the proposed algorithm is tested with benchmark truss sizing optimization problems and the results are compared with other metaheuristics. The results show that hybrid FPA improves the capabilities of the original one, produces more robust solutions than both FPA and DE, generates quite competitive results for the test problems compared to the previous studies with different algorithms. Therefore, the hybrid FPA proves to be a promising optimization algorithm alternative for engineering practice.
Comparing the data across the departments revealed no systematic differences based on the absorbe... more Comparing the data across the departments revealed no systematic differences based on the absorbed dose protocol each department followed. There may be a slight difference in the determination of relative output of the different applicators depending on the ion chamber used for output factor measurements, but with limited data available this remains inconclusive. The 90% and 85% dose to water range of x-rays agree between the departments within 1 mm for similar beam qualities, even though different methods were used to determine the depth dose deposition. Conclusions. A national comparison of kV radiotherapy units was conducted, and overall the units were found very similar. No systematic differences were observed based on the calibration protocol, but the available data hint that the choice of ion chamber for calibration measurements may have a small effect on the determination of output factors.
We report here a female fetus with anencephaly, omphalocele and unilateral radial aplasia. The co... more We report here a female fetus with anencephaly, omphalocele and unilateral radial aplasia. The combination of two of these three malformations were reported in a number of patients diagnosed as Gershoni-Barush syndrome, ORR phenotype, VATER association, Schisis association, OEIS complex, Schinzel phocomelia syndrome and Acalvaria but they have not been reported all together in the same patient up to date. We hypothesize that, some or all these syndromes given above may be related etiologically.
ICIASF 2001 Record, 19th International Congress on Instrumentation in Aerospace Simulation Facilities (Cat. No.01CH37215)
The subject of the experimental investigation presented in this paper is to measure the dynamic s... more The subject of the experimental investigation presented in this paper is to measure the dynamic stability derivatives of a generic combat aircraft model in the Ankara Wind Tunnel by using the direct forced oscillation technique. The model, used for the tests is the AGARD, Standard Dynamic Model (SDM). The aerodynamic loads acting on the model are measured with a five
Özet Bu makalede neoadjuvan kemoterapi (KT) ve konvansiyonel radyoterapi (RT) ile tedavi edilen n... more Özet Bu makalede neoadjuvan kemoterapi (KT) ve konvansiyonel radyoterapi (RT) ile tedavi edilen nazofarenks karsinomlu (NFK) hastalarda plazma hemoglobin (hb) konsantrasyonunun tedavi sonuçlarına etkisinin araştırılması amaçlanmıştır. 1989-1996 ...
Bu çalışmada, son 18 yılda nazofarenks karsinomu tanısı ile izlenen 50 çocuk hasta demografik, kl... more Bu çalışmada, son 18 yılda nazofarenks karsinomu tanısı ile izlenen 50 çocuk hasta demografik, klinik ve tedavi sonuçları açısından retrospektif olarak incelenmiştir. Yaşları 5-16 yaş arasında değişen 32 erkek 18 kız hasta, aynı süre içinde başvuran tüm nazofarenks ...
In this study, we investigate degradation of ZnO varistors and their effects on electronic boards... more In this study, we investigate degradation of ZnO varistors and their effects on electronic boards. We propose a model showing how the varistor clamping voltage Vv changes by time for different stress levels. To evaluate the model, we exploit measured experimental test data as well as field return data with over 1000 board failures. Varistors in-use are usually subjected to a long-term AC or DC voltage stress and surge which may lead to degradation of the varistors with an increase of the Vv parameters. We show that degraded varistors cause dramatic failures of other components in the same power block of the electronic board. We perform experiments on varistor degradation and failing mechanisms by applying 8/20 us, 2ms and accelerated AC voltage test methodologies. We also simulate the relation of the varistor degradation with other components in time domain. istors. The tests show us a continuous and fast decreasing trend in the Vv parameter for current levels above a certain thresh...
Springer Tracts in Nature-Inspired Computing, 2021
The truss sizing optimization problem, where the cross-sectional areas of truss members are optim... more The truss sizing optimization problem, where the cross-sectional areas of truss members are optimized, is a nonlinear and complex problem. The problem becomes quite challenging especially when a large number of variables exist. Metaheuristics proved to be working efficiently for this problem type. Flower pollination algorithm (FPA) is a recently developed metaheuristic search algorithm, and it has been successfully applied to structural optimization problems in the literature. In this paper, the formulation of FPA is enhanced to improve its local and global searching capabilities for better performance. For this purpose, a hybrid algorithm is developed by imitating the algorithmic structure of FPA while the mutation and crossover operators of differential evolution (DE) with elitism strategy are replaced with Levy flights of FPA to explore search space more efficiently and exploitation ability of FPA is improved with the addition of mutation factor and crossover operator of DE working in the local search formula of FPA. The performance of the proposed algorithm is tested with benchmark truss sizing optimization problems and the results are compared with other metaheuristics. The results show that hybrid FPA improves the capabilities of the original one, produces more robust solutions than both FPA and DE, generates quite competitive results for the test problems compared to the previous studies with different algorithms. Therefore, the hybrid FPA proves to be a promising optimization algorithm alternative for engineering practice.
Comparing the data across the departments revealed no systematic differences based on the absorbe... more Comparing the data across the departments revealed no systematic differences based on the absorbed dose protocol each department followed. There may be a slight difference in the determination of relative output of the different applicators depending on the ion chamber used for output factor measurements, but with limited data available this remains inconclusive. The 90% and 85% dose to water range of x-rays agree between the departments within 1 mm for similar beam qualities, even though different methods were used to determine the depth dose deposition. Conclusions. A national comparison of kV radiotherapy units was conducted, and overall the units were found very similar. No systematic differences were observed based on the calibration protocol, but the available data hint that the choice of ion chamber for calibration measurements may have a small effect on the determination of output factors.
We report here a female fetus with anencephaly, omphalocele and unilateral radial aplasia. The co... more We report here a female fetus with anencephaly, omphalocele and unilateral radial aplasia. The combination of two of these three malformations were reported in a number of patients diagnosed as Gershoni-Barush syndrome, ORR phenotype, VATER association, Schisis association, OEIS complex, Schinzel phocomelia syndrome and Acalvaria but they have not been reported all together in the same patient up to date. We hypothesize that, some or all these syndromes given above may be related etiologically.
ICIASF 2001 Record, 19th International Congress on Instrumentation in Aerospace Simulation Facilities (Cat. No.01CH37215)
The subject of the experimental investigation presented in this paper is to measure the dynamic s... more The subject of the experimental investigation presented in this paper is to measure the dynamic stability derivatives of a generic combat aircraft model in the Ankara Wind Tunnel by using the direct forced oscillation technique. The model, used for the tests is the AGARD, Standard Dynamic Model (SDM). The aerodynamic loads acting on the model are measured with a five
Özet Bu makalede neoadjuvan kemoterapi (KT) ve konvansiyonel radyoterapi (RT) ile tedavi edilen n... more Özet Bu makalede neoadjuvan kemoterapi (KT) ve konvansiyonel radyoterapi (RT) ile tedavi edilen nazofarenks karsinomlu (NFK) hastalarda plazma hemoglobin (hb) konsantrasyonunun tedavi sonuçlarına etkisinin araştırılması amaçlanmıştır. 1989-1996 ...
Bu çalışmada, son 18 yılda nazofarenks karsinomu tanısı ile izlenen 50 çocuk hasta demografik, kl... more Bu çalışmada, son 18 yılda nazofarenks karsinomu tanısı ile izlenen 50 çocuk hasta demografik, klinik ve tedavi sonuçları açısından retrospektif olarak incelenmiştir. Yaşları 5-16 yaş arasında değişen 32 erkek 18 kız hasta, aynı süre içinde başvuran tüm nazofarenks ...
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