Scopus İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://gcris.khas.edu.tr/handle/20.500.12469/1248

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Citation Count: 5
A 1-kW wireless power transfer system for electric vehicle charging with hexagonal flat spiral coil
(Tubitak Scientific & Technical Research Council Turkey, 2021) Aydin, Emrullah; AydemIr, M. Timur
Wireless power transfer (WPT) technology is getting more attention in these days as a clean, safe, and easy alternative to charging batteries in several power levels. Different coil types and system structures have been proposed in the literature. Hexagonal coils, which have a common usage for low power applications, have not been well studied for high and mid power applications such as in electric vehicle (EV) battery charging. In order to fill this knowledge gap, the self and mutual inductance equations of a hexagonal coil are obtained, and these equations have been used to design a 1 kW WPT system with hexagonal coils for a mid-power stage EV charging. The theoretical and simulation results have been validated with an implementation in the laboratory and a DC-to-DC power efficiency of 85% is achieved across a 10 cm air gap between the perfect aligned coils. The misalignment performance of the system was observed for different positioning of the secondary coil, and the output power variation is given. In addition, the effect of shielding on magnetic field exposition of a driver sitting in an EV was obtained, and these simulation results were compared in order to check the compliance with international health standards.
Citation Count: 4
Accurate indoor positioning with ultra-wide band sensors
(Tubitak, 2020) Arsan, Taner
Ultra-wide band is one of the emerging indoor positioning technologies. In the application phase, accuracy and interference are important criteria of indoor positioning systems. Not only the method used in positioning, but also the algorithms used in improving the accuracy is a key factor. In this paper, we tried to eliminate the effects of off-set and noise in the data of the ultra-wide band sensor-based indoor positioning system. For this purpose, optimization algorithms and filters have been applied to the raw data, and the accuracy has been improved. A test bed with the dimensions of 7.35 m x 5.41 m and 50 cm x 50 cm grids has been selected, and a total of 27,000 measurements have been collected from 180 test points. The average positioning error of this test bed is calculated as 16.34 cm. Then, several combinations of algorithms are applied to raw data. The combination of Big Bang-Big Crunch algorithm for optimization, and then the Kalman Filter have yielded the most accurate results. Briefly, the average positioning error has been reduced from 16.34 cm to 7.43 cm.
Citation Count: 9
Affective modulation of working memory maintenance: The role of positive and negative emotions
(University of Economics and Human Sciences in Warsaw, 2021) Gökçe, Ahu; Zinchenko,A.; Annac,E.; Conci,M.; Geyer,T.
The present study investigated the impact of task-irrelevant emotional images on the retention of information in spatial working memory (WM). Two experiments employed a delayed matching-to-sample task where participants had to maintain the locations of four briefly presented squares. After a short retention interval, a probe item appeared and participants were required to indicate whether the probe position matched one of the previously occupied square positions. During the retention interval, task-irrelevant negative, positive, or neutral emotional pictures were presented. The results revealed a dissociation between negative and positive affect on the participants’ ability to hold spatial locations in WM. While negative affective pictures reduced WM capacity, positive pictures increased WM capacity relative to the neutral images. Moreover, the specific valence and arousal of a given emotional picture was also related to WM performance: While higher valence enhanced WM capacity, higher levels of arousal in turn reduced WM capacity. Together, our findings suggest that emotions up- or down-regulate attention to items in WM and thus modulate the short-term storage of visual information in memory. © 2021 University of Finance and Management in Warsaw. All rights reserved.
Citation Count: 10
An analysis of international relations academics in Turkey and their approaches to the field: TRIP 2014 faculty survey results;
(International Relations Council of Turkey, 2016) Aydın, Mustafa; Hisarlioğlu,F.; Yazgan,K.
Despite the increasing interest in the studies inquiring the limits, autonomous character of and the interactions between the International Relations (IR) discipline and other academic fields, the scope and scale of empirical research on these issues are relatively small. In order to contribute to the discussion on the limits and peculiarities of the IR discipline and to shed light on the development, current status and major characteristics of the IR studies in Turkey, its place in the global IR discipline and the views of IR scholars on major issues on the global, regional and national agenda, two surveys were conducted by the International Relations Council of Turkey (IRCT) in 2007 and 2009. Later on, the IRTC collaborated with the Institute for the Theory and Practice of International Relations at the College of William and Mary to conduct further surveys in 2011 and 2014. This paper presents findings of the last survey on Turkey, based on the worldwide research simultaneously conducted in 31 different countries in September 2014. © 2016, International Relations Council of Turkey. All rights reserved.
Citation Count: 0
Analyzing multiple pricing decisions for substitutes under stochastic demand: An experiment
(John Wiley & Sons Ltd, 2022) Ayvaz-Cavdaroglu, Nur; Buyukboyaci, Muruvvet
This study investigates how individuals choose prices for two substitutes under stochastic demand in an airline setting. We design two treatments: symmetrical and asymmetrical, meaning the demand distribution of the two flights having the same size of support or not. Several insights are obtained. First, the decision makers' price choices are closer to the theoretical benchmarks in the symmetrical setting. Next, the subjects do not want to overprice and fly with empty seats, exhibiting loss aversion with reference point. Finally, the subjects often treat the flights as independent rather than interrelated and price them separately, using an anchoring-and-adjusting heuristic.
Citation Count: 0
Archival Lives of Popular Culture: Our Introduction
(WILEY, 2021-01) Altınay, Rustem Ertuğ; Jokic, Olivera
[Abstract Not Available]
Citation Count: 2
Aryl butenoic acid derivatives as a new class of histone deacetylase inhibitors: synthesis in vitro evaluation and molecular docking studies
(Scientific Technical Research Council Turkey-Tubitak, 2014) Yelekçi, Kemal; Seven, özlem; Eymur, Guluzar; Tatar, Gamze Bora; Erden, Didem Dayangaç; Yelekçi, Kemal; Yurter, Hayat; Demir, Ayhan S.
New aryl butenoic acid derivatives have been synthesized by combining hydroxy- or methoxy-substituted phenyl rings as the capping group with a double bond in the short linker as well as metal binding groups enoic ester and salts bearing either methyl or morpholine. These compounds have been shown to possess promising histone deacetylase inhibition activities via in vitro fluorometric assay and molecular docking studies.
Citation Count: 0
Assesment of soft error sensitivity of power flow analysis
(Gazi Univ, Fac Engineering Architecture, 2023) Yetkin, Emrullah Fatih
Today's power systems are large and interconnected to each other with many buses, lines, loads, and generators. Even the solution of a single snapshot of the system for specific conditions requires the solution of systems of equations with large sizes. Thus, to obtain the results in a reasonable time for large problems like electrical power flow simulations, modern large computational environments should be employed. However, because of the increasing number of components in the modern computational environment, the possibility of soft errors also increases. Soft errors can be defined as failures arising from several fluctuations due to x-rays, cosmic particle effects, etc. These types of errors usually appear at any time of computation as a bit-flip in any floating-point operations. In this paper, we will investigate the soft-error effects on large-scale power flow simulations. Generally, power flow calculations are performed by using Newton Raphson Method. The system is modeled by nonlinear equations and the solution process requires a linear solver is employed to take the inverse of the Jacobian matrix at each iteration. In this study, the soft-error sensitivity of the numerical methods used in load flow was examined, and the problems that may be encountered were revealed.
Citation Count: 0
Attractiveness Differentially Affects Direct Versus Indirect Face Evaluations in Two Cultures
(Sage Publications Inc, 2023) Cassidy, Brittany S.; Saribay, S. Adil; Yuksel, Huseyin; Kleisner, Karel
Although decades of research have identified facial features relating to people's evaluations of faces, specific features have largely been examined in isolation from each other. Recent work shows that considering the relative importance of these features in face evaluations is important to test theoretical assumptions of impression formation. Here, we examined how two facial features of evolutionary interest, facial attractiveness and facial-width-to-height ratio (FWHR), relate to evaluations of faces across two cultures. Because face evaluations are typically directly measured via self-reports, we also examined whether these features exert differential effects on both direct and indirect face evaluations. Evaluations of standardized photos naturally varying in facial attractiveness and FWHR were collected using the Affect Misattribution Procedure in the United States and Turkey. When their relative contributions were considered in the same model, facial attractiveness, but not FWHR, related to face evaluations across cultures. This positive attractiveness effect was stronger for direct versus indirect evaluations across cultures. These findings highlight the importance of considering the relative contributions of facial features to evaluations across cultures and suggest a culturally invariant role of attractiveness when intentionally evaluating faces.
Citation Count: 2
Bargaining with nonanonymous disagreement: Decomposable rules
(Elsevier Science Bv, 2011) Kıbrıs, Özgür; Tapkı, İpek Gürsel
We analyze bargaining situations where the agents' payoffs from disagreement depend on who among them breaks down the negotiations. We model such problems as a superset of the standard domain of Nash (1950). We first show that this domain extension creates a very large number of new rules. In particular, decomposable rules (which are extensions of rules from the Nash domain) constitute a nowhere dense subset of all possible rules. For them, we analyze the process through which "good" properties of rules on the Nash domain extend to ours. We then enquire whether the counterparts of some well-known results on the Nash (1950) domain continue to hold for decomposable rules on our extended domain. We first show that an extension of the Kalai-Smorodinsky bargaining rule uniquely satisfies the Kalai and Smorodinsky (1975) properties. This uniqueness result, however, turns out to be an exception. We characterize the uncountably large classes of decomposable rules that survive the Nash (1950), Kalai (1977), and Thomson (1981) properties. (C) 2011 Elsevier B.V. All rights reserved.
Citation Count: 1
Bayesian estimation of discrete-time cellular neural network coefficients
(TUBITAK Scientific & Technical Research Council Turkey, 2017) Şenol, Habib; Özmen, Atilla; Şenol, Habib
A new method for finding the network coefficients of a discrete-time cellular neural network (DTCNN) is proposed. This new method uses a probabilistic approach that itself uses Bayesian learning to estimate the network coefficients. A posterior probability density function (PDF) is composed using the likelihood and prior PDFs derived from the system model and prior information respectively. This posterior PDF is used to draw samples with the help of the Metropolis algorithm a special case of the Metropolis--Hastings algorithm where the proposal distribution function is symmetric and resulting samples are then averaged to find the minimum mean square error (MMSE) estimate of the network coefficients. A couple of image processing applications are performed using these estimated parameters and the results are compared with those of some well-known methods.
Citation Count: 6
Between anchors and aspirations: a new family of bargaining solutions
(Springer, 2019) Keskin, Kerim; Keskin, Kerim; Özcan-Tok, Elif
We study the salience and power of reference points in determining the effective anchors and aspirations in bargaining problems. Along this line we enrich the analysis of the standard bargaining model with two new parameters: the first parameter can be interpreted as the effectiveness (or salience) of the reference point in determining the anchor whereas the second parameter can be interpreted as its effectiveness in shaping agents' aspirations. Utilizing these parameters we provide a unifying framework for the study of bargaining problems with a reference point. The two-parameter family of bargaining solutions we obtain encompasses some well-known solutions as special cases. We offer multiple characterizations for each individual member of this family as well as two characterizations for the whole solution family in bilateral bargaining problems.
Citation Count: 13
Capital Flows and Credit Expansions in Turkey
(Sage Publications Inc, 2014) Orhangazi, Özgür
Literature on capital flows identifies various channels through which capital inflows could create financial fragility and economic instability in developing and emerging economies. Domestic credit expansion is one such channel. Capital inflows can lead to rapid expansion of domestic credit even create credit bubbles and thus result in an increased fragility of the economy. I analyze the link between private capital inflows and bank credit to the private sector in the case of Turkey between 2003 and 2013 and ask whether surges in private capital inflows accelerate growth of credit. I employ a logit model to investigate the link between capital inflows and periods of rapid credit expansion. The findings suggest that net private capital inflows after controlling for other determinants of credit are positively correlated with periods of rapid credit expansion.
Citation Count: 7
Capitalism Crisis and Class: The United States Economy after the 2008 Financial Crisis
(Sage Publications Inc, 2014) Orhangazi, Özgür; Orhangazi, Özgür
The literature on the outcomes of the financial crisis in low- and middle-income countries in the post-1980 era presents three broad findings: first the burden of crises falls disproportionately on labor in general and low-income segments of the society in particular. Wages and the labor share of income fall unemployment increases the power of labor declines and income inequality and poverty increase. Capital on the other hand recovers quickly and gains more ground. Second government policies favor capital especially financial capital at the expense of the larger public. Crises also present opportunities for further deregulation and liberalization in financial markets and the rest of the economy. Third following financial crises foreign capital inflows may increase as international capital seeks to take advantage of the crisis and acquire assets at fire-sale prices. The 2008 U.S. financial crisis provides an opportunity to extend this analysis to a leading high-income country. By examining the experience of the United States after the financial crisis in terms of the questions and issues typically raised in examinations of low- and middle-income countries this paper makes an original contribution while at the same time contributing to the gradually emerging literature on the consequences of the U.S. financial crisis. We first look at the distributional effects of the financial crisis and compare this with the impacts of the crisis on capital. Then we investigate the changes in income shares of labor and capital before shifting our attention to changes in inequality and poverty. Next we focus on the role of government policies through an analysis of government taxation and spending policies. Finally we examine the changes in capital inflows before concluding with a discussion of our overall findings and further research areas.
Citation Count: 1
Cervical spine injuries in children
(2004) Hamzaoglu, A.; Mirzanli, C.
Cervical spine injuries in children and adolescents are rare. Common mechanisms include motor vehicle accidents, sports injuries, fall from height, and gunshot injuries. Cervical spine injuries are classified by Allen and Ferguson according to the period they occur, as infantile, early juvenile, and late juvenile. Anatomically, two main types are defined as occipitoatlantal (upper cervical) and subaxial injuries. The purpose of this paper is to review cervical spine injuries in children and adolescents with respect to epidemiology, injury mechanisms, diagnosis, clinical and radiologic aspects, and treatment in the light of the current literature.
Citation Count: 13
Characteri̇zati̇on of mps capped cds quantum dots and formati̇on self-assembled quantum dots thi̇n fi̇lms on a glass substrate
(National Institute R and D of Materials Physics, 2011) Koç,K.; Tepehan,F.Z.; Tepehan,G.G.
Colloidal, powdered and thin film forms of MPS capped CdS quantum dots have been produced by combination of colloidal chemistry and sol-gel method. Nanoparticles were self-assembled directly on a glass substrate using spin coating method without introducing any matrix. Colloidal, powdered and thin film forms were characterised by absorbance, photolimunescence, XRD, FT-IR, HRTEM and AFM measurements. The HRTEM images give a grain size of 2.5-3.0 nm and this is in agreement with the values found in the absorbance and XRD measurement. Average size of the quantum dots increase with increasing of heat treatment temperature due to Oswald ripening.
Citation Count: 15
A comparative analysis on housing policies in turkey and Lithuania
(Taylor & Francis, 2007) Yetgin, Feyzullah; Lepkova, Natalija
The housing sector is a very important sector in the national economy worldwide. The greater importance of the housing sector is broadly defined to include financing upgrading repairs management valuation taxation and population. The article presents a comparative analysis on housing policies in Turkey and Lithuania. The housing strategies -their differences and similarities - of Turkey and Lithuania are presented in the article. Strategic principles and preferences of housing are analysed in the countries under investigation. Some economic aspects are underlined. The policies of social housing of investigated countries are presented. The housing problems of both analysed countries are described. Special attention is paid to sustainable housing and social cohesion in housing. © 2007 Taylor & Francis Group LLC. All rights reserved.
Citation Count: 0
Comparative classification performances of filter model feature selection algorithms in EEG based brain computer interface system
(Gazi Univ, Fac Engineering Architecture, 2023) Ballı, Tuğçe; Balli, Tugce; Yetkin, E. Fatih
Brain-computer interface (BCI) systems enable individuals to use a computer or assistive technologies such as a neuroprosthetic arm by translating their brain electrical activity into control commands. In this study, the use of filter-based feature selection methods for design of BCI systems is investigated. EEG recordings obtained from a BCI system designed for the control of a neuroprosthetic device are analyzed. Two feature sets were created; the first set was band power features from six main frequency bands (delta (1.0-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), beta (12-25 Hz), high-beta (25-30Hz) and gamma (30-50 Hz)) and the second set was band power features from ten frequency sub-bands (delta (1-4 Hz), theta (4-8 Hz), alpha1 (8-10 Hz), alpha2 (10-12 Hz), beta1 (12-15 Hz), beta2 (15-18 Hz), beta3 (18-25 Hz), gamma1 (30-35 Hz), gamma2 (35-40 Hz), gamma3 (40-50 Hz)). Ten filter-based feature selection methods are investigated along with linear discriminant analysis, random forests, decision tree and support vector machines algorithms. The results indicate that feature selection methods leads to a higher classification accuracy and eigen value centrality (Ecfs) and infinite feature selection (Inffs) methods have consistently provided higher accuracy rates as compared to rest of the feature selection methods.
Citation Count: 7
A comparison of erythrocyte superoxide dismutase and catalase activity in patients with hepatitis C infection
(2002) Bayındır, Yaar; Karabulut, Aysun Bay; Sönmez, Emine; Gözükara, Engin M.
Hepatitis C virus (HCV) infection remains important due to difficulties in treatment up to a chronic state. It is considered that free radicals, lipid peroxidation and antioxidant defense play a role in various tissue damages, just as in certain types of viral hepatitis. Since only limited data has been reported concerning oxidative stress in viral hepatitis, a comparative study was planned for patients with hepatitis C. In this study, we searched for erythrocyte superoxide dismutase (SOD) and catalase (CAT) activities in patients with HCV infection who had received and not received recombinant interferon alpha. Four groups of patients [Group 1: 15 healthy, volunteers served as a control group; Group II: 10 patients with acute HCV infection; Group III: 15 untreated patients with chronic HCV infection; and Group IV: 15 patients who completed six months of interferon therapy (9 million U/week)] were included in the study. In Group I, SOD activity (as means ± standard deviation) was 2213.29 ± 152.01 U/g Hb; in Group II, 2643.03 ± 142.44 U/g Hb; in Group III, 1135.79 ± 122.27 U/g Hb; and in Group IV, 1734.78 ± 183.72 U/g Hb. The difference between the groups was statistically significant (p < 0.05). Erythrocyte means ± standard deviation CAT levels in Group I were 252.10 ± 61.09 K/g Hb; in Group II, 253.37 ± 29.68 K/g Hb; in Group III, 291.80 ± 72.54 K/g Hb; and in Group IV 220.43 ± 36.39 K/g Hb. The difference between Groups I, II and III was not statistically significant (p > 0.05), but was for Groups III and IV (p < 0.005) In conclusion, erythrocyte SOD activity increased in acute hepatitis C patients, but decreased in chronic hepatitis C patients, and this decrease was reversed when treated with interferon.
Citation Count: 10
Comparison of intraoperative transit-time flow measurement with early postoperative magnetic resonance flow mapping: In off-pump coronary artery surgery
(2003) Sanisoglu,I.; Guden,M.; Balci,C.; Sagbas,E.; Duran,C.; Akpinar,B.
The purpose of this prospective study was to evaluate graft patency of off-pump coronary artery surgery intraoperatively by transit-time flow measurement and to compare this technique with postoperative magnetic resonance flow mapping. Twenty patients (13 men and 7 women; mean age, 67.9 ± 7.6 yr) underwent off-pump coronary artery surgery. Intraoperative transit-time flow measurement of grafts was performed measuring maximum, minimum, and mean flows. For each graft, the pulsatile index was calculated by dividing the difference between the maximum and the minimum flow by the mean flow. In the early postoperative period (1st week), magnetic resonance flow mapping was performed using phase contrast flow quantification. Mean intraoperative flow values and mean magnetic resonance flow mapping values were compared. At the same postoperative session, contrast-enhanced magnetic resonance angiography was performed to evaluate graft patency. In 20 patients, a total of 49 coronary graft flows were assessed with intraoperative transit-time flow measurement and postoperative magnetic resonance flow mapping. Upon comparison, there was a strong correlation between techniques, with stable and statistically significant differences between the intraoperative and postoperative flow mapping values. One saphenous vein graft was revised intraoperatively, due to graft failure. Our data suggest that the combined use of intraoperative transit-time flow measurement and postoperative magnetic resonance flow analysis has a potential role in the assessment of graft patency in off-pump coronary artery surgery, although more study is required.

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