Showing papers by "Yaşar University published in 2013"
TL;DR: In this article, the authors theoretically analyzed entropy generation, heat transfer enhancement capabilities and pressure drop of an absorbing medium with suspended nanoparticles (Al2O3, CuO, SiO2, TiO2 dispersed in water) inside a flat plate solar collector.
136 citations
TL;DR: In this article, the effect of different nanoparticle shapes (such as cylindrical, bricks, blades, platelets, and spherical) on the performance of a shell and tube heat exchanger operating with nanofluid analytically was studied.
134 citations
TL;DR: In this paper, the performance assessment of porous baffles inserted solar air heaters (SAHs) using energy and exergy analysis methods was carried out using the first and second laws of thermodynamics.
127 citations
TL;DR: In this paper, a case study based on hybrid wind-solar renewable energy system is conducted and its results are presented. And the maximum efficiencies of the wind turbine, solar PV panel, electrolyzer, PEMFC are calculated as 26.15%, 9.06%, 53.55%, and 33.02% through energy analysis, and 71.70, 9.74, 53.60%, and33.44% through exergy analysis, respectively.
100 citations
TL;DR: In this article, the authors reviewed the previously conducted studies and applications in terms of design, performance assessment, heat transfer enhancement techniques, experimental and numerical works, thermal heat storage, effectiveness and recent advances.
Abstract: Solar air heating (solar collector) is a renewable heating technology and provides heat using solar energy. With fuel costs and other factors, solar air heaters (SAHs) are getting more attention. The energetic and exergetic performance of SAHs is influenced by a number of factors. The present study reviews the previously conducted studies and applications in terms of design, performance assessment, heat transfer enhancement techniques, experimental and numerical works, thermal heat storage, effectiveness compassion and recent advances. It may be concluded that energy analysis method has been used in a number of studies while exergy analysis method has been applied to the relatively low numbers of systems. Energy efficiencies of solar air collectors reviewed varied from 47% and 89%. It is expected that this comprehensive study will be very beneficial to everyone involved or interested in the energetic and exergetic design, simulation, analysis, test and performance assessment of SAHs.
90 citations
TL;DR: A variable iterated greedy algorithm (IG) with differential evolution (vIG_DE) designed to solve the no-idle permutation flowshop scheduling problem and computational results show that all three IG variants represent state-of-art methods for the NIPFS problem.
87 citations
TL;DR: In this paper, a discrete artificial bee colony algorithm was proposed to solve the no-idle permutation flowshop scheduling problem with the total tardiness criterion, where idle time is not allowed on machines.
85 citations
TL;DR: In this paper, the results of energy and exergetic analyses of T56 turboprop engine at various power loading operation modes (75, 100, military and takeoff) were presented.
76 citations
26 May 2013
TL;DR: A taxonomy of the best known techniques to realize genus 2 based cryptography, which includes fast formulas on the Kummer surface and efficient 4-dimensional GLV decompositions, is given.
Abstract: In this paper we highlight the benefits of using genus 2 curves in public-key cryptography. Compared to the standardized genus 1 curves, or elliptic curves, arithmetic on genus 2 curves is typically more involved but allows us to work with moduli of half the size. We give a taxonomy of the best known techniques to realize genus 2 based cryptography, which includes fast formulas on the Kummer surface and efficient 4-dimensional GLV decompositions. By studying different modular arithmetic approaches on these curves, we present a range of genus 2 implementations. On a single core of an Intel Core i7-3520M (Ivy Bridge), our implementation on the Kummer surface breaks the 120 thousand cycle barrier which sets a new software speed record at the 128-bit security level for constant-time scalar multiplications compared to all previous genus 1 and genus 2 implementations.
68 citations
TL;DR: In this paper, an exergoeconomic and environmental impact analyses, through energy, exergy, and sustainability assessment methods, are performed to investigate a hybrid version renewable energy (including wind and solar) based hydrogen and electricity production system.
59 citations
TL;DR: In this paper, a gas engine heat pump (GEHP) drying system was analyzed using both conventional and advanced exergy analyses and the results showed that most of the exergy destructions in the system components were avoidable and these avoidable parts can be reduced by design improvements.
TL;DR: In this article, the authors argue that the correlation of religion with reduced corruption is conditional on the extent to which political institutions are democratic, and that the nature of this relationship is contingent on the presence of democratic institutions.
Abstract: Critically considering scholarship relating religiosity to ethical behaviour, we contend that religion is systematically related to levels of corruption, and that the nature of this relationship is contingent on the presence of democratic institutions. In democracies, where political institutions are designed to inhibit corrupt conduct, the morality provided by religion is related to attenuated corruption. Conversely, in systems lacking democratic institutions, moral behaviour is not tantamount to staying away from corrupt ways. Accordingly, in non-democratic contexts, religion would not be associated with decreased corruption. Time-series cross-sectional analyses of aggregate data for 129 countries for 12 years, as well as individual level analyses of data from the World Values Surveys, strongly corroborate the predictions of our theory. The correlation of religion with reduced corruption is conditional on the extent to which political institutions are democratic.
TL;DR: In this article, an advanced exergy analysis was applied to a pilot-scale heat pump drying system used in food drying for the first time to evaluate its performance at different drying temperatures.
Abstract: Exergy analysis has been used as a powerful tool to study and optimize various types of energy systems. However, the methodology of splitting the exergy destructions (the so-called advanced exergy analysis) allows for a further understanding of the exergy destruction values to improve the system efficiency. In this study, advanced exergy analysis was applied to a pilot-scale heat pump drying system used in food drying for the first time to evaluate its performance at different drying temperatures. The results showed that inefficiencies within the compressor and condenser were mainly due to the internal operating conditions and the efficiencies in the evaporator and heat recovery system could be improved by structural improvements of the whole system and remaining system components.
TL;DR: In this article, a comprehensive field study was conducted to develop a valid and reliable social innovation instrument at individual level, and a reliable and valid social innovation scale was employed unidimensionally with eight items.
20 Aug 2013
TL;DR: In this article, the authors explored the potential for using genus 2 curves over quadratic extension fields in cryptography, motivated by the fact that they allow for an 8-dimensional scalar decomposition when using a combination of the GLV/GLS algorithms.
Abstract: This paper explores the potential for using genus 2 curves over quadratic extension fields in cryptography, motivated by the fact that they allow for an 8-dimensional scalar decomposition when using a combination of the GLV/GLS algorithms. Besides lowering the number of doublings required in a scalar multiplication, this approach has the advantage of performing arithmetic operations in a 64-bit ground field, making it an attractive candidate for embedded devices. We found cryptographically secure genus 2 curves which, although susceptible to index calculus attacks, aim for the standardized 112-bit security level. Our implementation results on both high-end architectures (Ivy Bridge) and low-end ARM platforms (Cortex-A8) highlight the practical benefits of this approach.
TL;DR: In this article, the authors compared exergy destructions of a geothermal district heating system (GDHS) using both conventional and advanced exergetic analysis methods to identify the potential for improvement and the interactions among the components.
TL;DR: The capacitated supply scenario is formulated as a network flow problem embedded in a stochastic optimization problem, which is solved through a sample average approximation method and finds that, depending on the production capacity, system behavior can vary drastically.
TL;DR: In this paper, the performance of greenhouse heating systems with EAHEs in closed loop mode is evaluated. And the overall energy efficiency is determined to be 72.10% while the overall exergy efficiency value is calculated to be 19.18% at a reference state temperature of 0.
TL;DR: In this article, a single machine scheduling problem with deteriorating processing time of jobs and multiple preventive maintenances which reset deteriorated processing time to the original processing time was studied. And the authors proposed a number of heuristics and design genetic algorithms for the problems.
Abstract: In this paper, we study a single machine scheduling problem with deteriorating processing time of jobs and multiple preventive maintenances which reset deteriorated processing time to the original processing time. In this situation, we consider three kinds of problems whose performance measures are makespan, total completion time, and total weighted completion time. First, we formulate integer programming formulations, and using the formulations, one can find optimal solutions for small problems. Since these problems are known to be NP-hard and the size of real problem is very large, we propose a number of heuristics and design genetic algorithms for the problems. Finally, we conduct some computational experiments to evaluate the performance of the proposed algorithms.
TL;DR: In this paper, a green industrial service buying approach for the industrial customers of logistics centers is proposed, which combines green purchasing literature with previousely developed environmental performance indicators (EPIs).
Abstract: The rapidly globalizing world trade requires longer supply chains with higher attention on the environmental effects of logistics activities. Latest international conventions related with environmental regulations reinforce governments and corporations to adhere to environmental protection precautions. An effort to decrease the negative environmental effects of logistics activity is the geographical concentration of logistics companies which are called logistics centers. This study aims to provide a green industrial service buying approach for the industrial customers of logistics centers. The study combines green purchasing literature with previousely developed environmental performance indicators (EPIs) and develops a green industrial buying model for logistics centers. The model provides a framework for potential residents of a logistics center and supports their industrial buying processes. The model also serves as an input for green industrial service design in a logistics center.
TL;DR: In this article, the exergetic and thermoeconomic analyses of thermal energy storage (TES) systems, such as latent, sensible and thermochemical options coupled with different units for building heating applications under varying reference (dead-state) temperatures of 8, 9, and 10, respectively, were investigated.
TL;DR: The aim of this paper is to present a stochastic maximum principle for an optimal control problem of switching systems, in which the dynamic of the constituent processes takes the form of stoChastic differential equations.
Abstract: The aim of this paper is to present a stochastic maximum principle for an optimal control problem of switching systems. It presents necessary conditions of optimality in the form of a maximum principle for stochastic switching systems, in which the dynamic of the constituent processes takes the form of stochastic differential equations. The restrictions on transitions for the system are described through equality constraints.
TL;DR: In this paper, the causal relationship between technological and social innovations was examined and the impact of entrepreneurial characteristics on social innovation was also analyzed based on a comprehensive field study including 767 university students from 10 universities from different regions of Turkey.
Abstract: The term innovation has sometimes been used as a synonym for technological innovation until the concept of social innovation attracted academic attention. Since then, these two types of innovation have been investigated individually. It can be claimed that, despite the great importance of social innovation studies, technological innovation studies received more attention. In addition, there are limited studies that have examined technological and social innovation together. The aim of this study was to examine the causal relationship between technological and social innovations. The impact of entrepreneurial characteristics on social innovation was also analyzed. This study was based on a comprehensive field study including 767 university students from 10 universities from different regions of Turkey. Regression analyses and structural equation modeling confirmed that social and technological innovation were related to one another, and both were correlated with a particular constellation of personal chara...
TL;DR: In this paper, an energy and exergy assessment of a perlite expansion furnace in a plaster factory is performed, where chemical properties of the perlite and its application areas are described.
TL;DR: This article investigated the individual level factors that influence support for social redistribution and social policy in Turkey by focusing on the role of core values and religiosity, and found that self-transcendence and conservation values enhance support for government provision of social safety nets.
Abstract: This paper investigates the individual level factors that influence support for social redistribution and social policy in Turkey by focusing on the role of core values and religiosity. The analysis of data from Round 4 of European Social Surveys shows that self-transcendence and conservation values enhance support for government provision of social safety nets. Different aspects of religiosity have different effects on attitudes toward redistribution and social policy, with self-identified religiosity having a positive and social religious behavior having a negative effect on support for government responsibility in providing social insurance.
TL;DR: In this article, a solar-assisted biomass gasification system for hydrogen production was investigated and the performance of the entire system was evaluated through both energy and exergy efficiencies, and the environmental impact of these systems is evaluated through calculating the specific greenhouse gas (GHG) emissions.
TL;DR: The purpose of this review is to shed light on the development and evaluation of the models proposed for predicting bankruptcy in terms of conceptualization, country distribution, sector specification, time dimension, variables used and findings reported.
Abstract: Default modelling is a general term used for several interrelated fields of risk management. Bond defaults, credit (loan) defaults, firm defaults and country defaults are examples of this kind. The scope and reason for existence of this study is to focus mainly on firm default. The purpose of this review is to shed light on the development and evaluation of the models proposed for predicting bankruptcy in terms of conceptualization, country distribution, sector specification, time dimension, variables used and findings reported. The current review includes firm default studies published in business fields such as accounting, economics, finance and management science. This review is distinct in that it seeks (i) to give a comprehensive examination of the models, (ii) to compare and contrast the features of the models and (iii) to show with a solid argument where future research should be focused.
19 Dec 2013
TL;DR: In this study, a general variable neighborhood search (GVNS) is presented to solve no-idle permutation flowshop scheduling problem (NIPFS), where idle times are not allowed on machines.
Abstract: In this study, a general variable neighborhood search (GVNS) is presented to solve no-idle permutation flowshop scheduling problem (NIPFS), where idle times are not allowed on machines. GVNS is a metaheuristic, where inner loop operates a variable neighborhood descend (VND) algorithm whereas the outer loop carries out some perturbations on the current solution. We employ a simple insert and swap moves in the outer loop whereas iterated greedy (IG) and iterated local search (ILS) algorithms are employed in the VND as neighborhood structures. The results of the GVNS algorithm are compared to those generated by the variable iterated greedy algorithm with differential evolution (vIG_DE). The performance of the proposed algorithm is tested on the Ruben Ruiz’ benchmark suite that is presented in http://soa.iti.es/rruiz. Computational results showed that the GVNS algorithm further improved 85 out of 250 best solutions found so far in the literature.
TL;DR: In this paper, Turkish security discourses connected to the meta-geography of the Broader Middle East and North Africa (BMENA) before and after the developments of the Arab Spring are analyzed.
Abstract: This article critically analyses Turkish security discourses connected to the meta-geography of the Broader Middle East and North Africa (BMENA) before and after the developments of the Arab Spring...
TL;DR: In this article, the authors explored which metrics are considered important in measuring marketing performance in Turkish firms and examined the effects of sectoral differences and market dynamism, and the relationship between the importance attached to metrics and firm performance.
Abstract: This study explores which metrics are considered important in measuring marketing performance in Turkish firms. In addition, the study examines the effects of sectoral differences and market dynamism, and the relationship between the importance attached to metrics and firm performance. The data collected from a sample of 145 Turkish firms via a structured questionnaire derived from the literature reveals that the most importance is attached to consumers’ attitudes metrics. Economic value added and customer lifetime value are the least important metrics in performance evaluation. No significant relationship occurs between the importance that executives attach to metrics and firm performance. Managerial implications and future research opportunities will be presented at the end. The study is, as far as is known, the first attempt at aiming to explore marketing metrics in Turkey, and one of a limited number of studies in emerging economies.