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Numerical analysis of entropy generation in concentric curved annular ducts
Haydar Kucuk 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.9
The entropy generation has been numerically investigated in concentric curved annular square ducts under constant wall temperature boundary condition. The problem has been assumed to be steady, hydrodynamically and thermally fully developed and incompressible laminar flow with constant physical properties. The solutions of discretized equations for continuity, momentum and energy have been obtained by using an elliptic Fortran Program based on the SIMPLE algorithm. Solutions have been achieved for i) Dean numbers ranging from 3.6 to 207.1, ii) Annulus dimension ratios of 5.5, 3.8, 2.9 and 2.36, and iii) Prandtl number of 0.7. In this regard, local entropy generation as well as overall entropy generation in the whole flow field has been analyzed in detail. Moreover, the effects of Dean number and annulus dimension ratio on entropy generation arising from the friction and heat transfer have been investigated. Accordingly, it is concluded that the effect of volumetric entropy generation that is a result of fluid frictional irreversibility can be neglected as compared with volumetric entropy generation due to heat transfer irreversibility. As Dean number increases, the distribution of volumetric entropy generation coming out from the heat transfer irreversibility is formed by the temperature field, which is depending on the curvature.
Almost Menger property in fuzzy topological spaces
A. Haydar Es 원광대학교 기초자연과학연구소 2021 ANNALS OF FUZZY MATHEMATICS AND INFORMATICS Vol.22 No.1
In this paper, the concept of fuzzy Mengerness, fuzzy almost Mengerness and fuzzy nearly Mengerness introduced and studied. Every fuzzy Menger space is fuzzy nearly Menger space and every fuzzy nearly Menger space is fuzzy almost Menger space. We give some characterizations of almost Menger space in terms of fuzzy regular open sets or fuzzy regular closed sets.
Zaman, Haydar U,Hun, Park Deuk,Khan, Ruhul A,Yoon, Keun-Byoung SAGE Publications 2014 Journal of thermoplastic composite materials Vol.27 No.3
<P>In this study, polypropylene (PP)/organoclay nanocomposites were prepared by melt-compounding PP with three levels of clay loading (3, 5 and 7 wt%), using two different compatibilizers with various contents (5, 10 and 15 wt %), maleic anhydride-grafted polypropylene (PPMA) and hexamethylenediamine-modified maleic anhydride-grafted polypropylene (PPHMA). Effects of structure, mechanical properties and crystallization behaviors of the compatibilizers on the clay dispersion and the amount of clay on the microstructure and mechanical properties of the nanocomposites were investigated. The PPHMA compatibilized system conferred higher mechanical properties than the PPMA compatibilized case. It was found that the PPHMA yielded better clay dispersion and more exfoliated structure compared with the PPMA. Microstructural characterization of the samples was also characterized by transmission electron microscopy. Differential scanning calorimetry results indicate that the addition of compatibilizer increased the crystallization temperature as a result of heterogeneous nucleation effect of clay on PP.</P>
APPLICATIONS OF CLASS NUMBERS AND BERNOULLI NUMBERS TO HARMONIC TYPE SUMS
Goral, Haydar,Sertbas, Doga Can Korean Mathematical Society 2021 대한수학회보 Vol.58 No.6
Divisibility properties of harmonic numbers by a prime number p have been a recurrent topic. However, finding the exact p-adic orders of them is not easy. Using class numbers of number fields and Bernoulli numbers, we compute the exact p-adic orders of harmonic type sums. Moreover, we obtain an asymptotic formula for generalized harmonic numbers whose p-adic orders are exactly one.
Ali Haydar Kayhan,Ahmet Demir 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.60 No.6
Modern performance-based design methods require ways to determine the factual behavior of structures subjected to earthquakes. Drift ratio demands are important measures of structural and/or nonstructural damage of the structures in performance-based design. In this study, global drift ratio and interstory drift ratio demands, obtained by nonlinear time history analysis of three generic RC frames using code-compatible ground motion record sets, are statistically evaluated. Several ground motion record sets compatible with elastic design spectra defined for the local soil classes in Turkish Earthquake Code are used for the analyses. Variation of the drift ratio demands obtained from ground motion records in the sets and difference between the mean of drift ratio demands calculated for ground motion sets are evaluated. The results of the study indicate that i) variation of maximum drift ratio demands in the sets were high; ii) different drift ratio demands are calculated using different ground motion record sets although they are compatible with the same design spectra; iii) the effect of variability due to random causes on the total variability of drift ratio demands is much larger than the effect of variability due to differences between the mean of ground motion record sets; iv) global and interstory drift ratio demands obtained for different ground motion record sets can be accepted as simply random samples of the same population at %95 confidence level. The results are valid for all the generic frames and local soil classes considered in this study.
Cournot duopoly and tacit collusion under fairness and reciprocal preferences
Iris Haydar Doruk 한국계량경제학회 2017 계량경제학보 Vol.28 No.4
This paper studies the impact of fairness and reciprocity on collusion between firms competing in quantities in infinitely repeated games. A reciprocal firm responds to unkind behavior of rivals with unkind actions (destructive reciprocity), while at the same time, it responds to kind behavior of rivals with kind actions (constructive reciprocity). The paper shows that when firms are reciprocal, collusive quantity profiles are easier to sustain for reasonable perceptions of fair quantities of rivals. However, if only very low quantities deemed as fair, then sustaining collusion could be more difficult when the firms have fairness concerns.
The status of NORMs in natural environment adjacent to the Rooppur nuclear power plant of Bangladesh
Md Abu Haydar,Md Mehade Hasan,Imrose Jahan,Kanij Fatema,Md Idris Ali,Debasish Paul,Mayeen Uddin Khandaker 한국원자력학회 2021 Nuclear Engineering and Technology Vol.53 No.12
The Rooppur Nuclear Power Plant (RNPP), the first nuclear power plant in Bangladesh with a capacity of2.4 GWe, is under construction on the bank of the river Padma, at Rooppur in Bangladesh. Measurementof background radioactivity in the natural environment adjacent to RNPP finds great importance forfuture perspectives. Soil and sediment samples collected from upstream and downstream positions ofthe Padma River (adjacent to RNPP) were collected and analyzed by HPGe gamma-ray spectrometry forprimordial radionuclides. The average activity concentrations (in Bqkg 1) of 226Ra, 232Th and 40K radionuclides in soil samples were found to be 44.99 ± 3.89, 66.28 ± 6.55 and 553 ± 82.17 respectively. Respective values in sediment samples were found to be 44.59 ± 4.58, 67.64 ± 7.93, 782 ± 108. Relevantradiation hazard indices and dosimetric parameters were calculated and compared with the worldaverage data recommended by US-EPA. Analytical results show non-negligible radiation hazards to thesurrounding populace. Measured data will be useful to monitor any change of background radioactivityin the surrounding environment of RNPP following its operation for the generation of nuclear energ