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Games with switching costs and endogenous references
No full textWe introduce a game-theoretic model with switching costs and endogenous references. An agent endogenizes his reference strategy, and then taking switching costs into account, he selects a strategy from which there is no profitable deviation. We axiomatically characterize this selection procedure in one-player games. We then extend this procedure to multiplayer simultaneous games by defining a Switching Cost Nash Equilibrium (SNE) notion, and prove that (i) an SNE always exists; (ii) there are sets of SNE, which can never be a set of Nash equilibrium for any standard game; and (iii) SNE with a specific cost structure exactly characterizes the Nash equilibrium of nearby games, in contrast to Radner's (1980) ε-equilibrium. Subsequently, we apply our SNE notion to a product differentiation model, and reach the opposite conclusion of Radner (1980): switching costs for firms may benefit consumers. Finally, we compare our model with others, especially Köszegi and Rabin's (2006) personal equilibrium.Publisher versio
A new voltammetric sensor for penicillin G using poly(3-methylthiophene)-citric acid modified glassy carbon electrode
No full textIn this study, an effective voltammetric sensor was developed for determination of penicillin G by electropolymerization of 3-methylthiophene with citric acid on glassy carbon electrode. Penicillin G selective electrode was prepared in water:acetonitrile (1:1) mixture containing 0.1 M sodium perchlorate as electrolyte medium with cyclic voltammetry. Then, the electrochemical behavior of penicillin G on poly(3-methylthiophene) based membrane modified electrode was investigated by cyclic voltammetry, differential pulse voltammetry and differential pulse stripping voltammetry techniques. When the penicillin G responses of the modified glassy carbon electrode were compared with the bare glassy carbon electrode responses, it was seen that the selectivity and sensitivity of the penicillin G responses of the modified electrode significantly increased. A linear calibration graph for penicillin G was obtained in the concentration range of 0.07 to 4.0 mM with the prepared electrode. The R2 value was calculated as 0.9999 from the linear calibration curve. The limit of detection and limit of quantitation of the poly(3-methylthiophene)-citric acid modified glassy carbon electrode for penicillin G were calculated as 8 μM and 28 μM, respectively. In addition, the developed electrode for the detection of PeG was applied to milk samples. The recovery efficiency of the poly(3-methylthiophene)-citric acid modified glassy carbon electrode was obtained in the range of 93 % and 103 % for three different milk samples. As a result; the modified electrode can be used for residue penicillin detection in food and biological samples.İnönü Universit
Deep reinforcement learning approach for trading automation in the stock market
No full textDeep Reinforcement Learning (DRL) algorithms can scale to previously intractable problems. The automation of profit generation in the stock market is possible using DRL, by combining the financial assets price 'prediction' step and the 'allocation' step of the portfolio in one unified process to produce fully autonomous systems capable of interacting with their environment to make optimal decisions through trial and error. This work represents a DRL model to generate profitable trades in the stock market, effectively overcoming the limitations of supervised learning approaches. We formulate the trading problem as a Partially Observed Markov Decision Process (POMDP) model, considering the constraints imposed by the stock market, such as liquidity and transaction costs. We then solve the formulated POMDP problem using the Twin Delayed Deep Deterministic Policy Gradient (TD3) algorithm reporting a 2.68 Sharpe Ratio on unseen data set (test data). From the point of view of stock market forecasting and the intelligent decision-making mechanism, this paper demonstrates the superiority of DRL in financial markets over other types of machine learning and proves its credibility and advantages in strategic decision-making.Publisher versio
Acil sağlık sistemleri için blockchain tabanlı güvenlik mekanizması
No full textElectronic health records (EHRs) play a crucial role in today's healthcare industry, these records include sensitive and private healthcare data assets which are prone to the breach of security and confidentiality. These potential data breaches may have lots of consequences such as violating patient's privacy, unauthorized access to EHR, data alteration and putting the patient's life in danger. Recently proposed EHR systems have came along with strong security features for preserving the patient's safety and security. However, there is still issues regarding access control management to Personal Health Records (PHRs). In previously presented systems patient plays the main role in controlling the access to the system. And this rises an uncertainty in emergency conditions, while the patient is incapable of issuing any access permission. In this study we suggest a new framework for maintaining medical healthcare records (MHRs) in emergency conditions by a secure and private access control architecture that is designed and employed based on a permissioned blockchain hyperledger sawtooth. Leveraging unique properties of blockchain our system manages to provide a tamper-proof and secure access to patient's medical data in a short period of time in an emergency scenario. For performance analysis the proposed architecture is implemented through hyperledger sawtooth blockchain network. The numerical results of our experiment demonstrated the feasibility and superiority of our proposed architecture in compared with the similar proposed healthcare systems concerning response time, memory consumption, throughput and overall privacy and security.Elektronik sağlık kayıtları (ESK'ler) günümüz sağlık endüstrisinde çok önemli bir rol oynamaktadır, bu kayıtlar güvenlik ve gizliliğin ihlaline açık hassas ve özel sağlık veri varlıklarını içermektedir. Bu olası veri ihlallerinin hastanın mahremiyetinin ihlali, ESK'ye yetkisiz erişim, veri değişikliği ve hastanın hayatını tehlikeye atma gibi birçok sonucu olabilir. Son zamanlarda önerilen ESK sistemleri, hastanın güvenliğini korumak için güçlü güvenlik özellikleri ile birlikte geliyor. Ancak, Kişisel Sağlık Kayıtlarına (KSK'ler) erişim kontrolü yönetimi ile ilgili hala sorunlar bulunmaktadır. Daha önce sunulan sistemlerde, sisteme erişimi kontrol etmede hasta ana rolü oynar, ve bu acil durumlarda bir belirsizliğe yol açarken, hasta herhangi bir erişim izni veremez. Bu çalışmada, Hyperledger Sawtooth blockzincir ile tasarlanan güvenli ve özel bir erişim kontrol mimarisi sunarak acil durumlarda tıbbi sağlık kayıtlarının (TSK'ler) tutulması için yeni bir çerçeve öneriyoruz. Blok zincirinin benzersiz özelliklerinden yararlanan sistemimiz, acil bir senaryoda hastanın tıbbi verilerine kısa sürede güvenli bir erişim sağlar. Simülasyonumuzun sayısal sonuçları, yanıt süresi, bellek tüketimi, verim, genel gizlilik ve güvenlik açısından benzer sağlık sistemleriyle karşılaştırıldığında önerilen mimarimizin performansının daha iyi olduğunu ve kullanılabilirleğini gösterir
Positioning aerial relays to maintain connectivity during drone team missions
No full textApproaches that aim to maintain the connectivity of unmanned aerial vehicles (UAVs) or drones either utilize cellular networks or propose to jointly optimize connectivity needs with other mission tasks. Therefore, most solutions either rely on existing infrastructure or are optimized for specific applications. Use of UAVs to assist the connectivity of ground nodes is commonly proposed. In this work, we deploy UAVs as relays to support mission-oriented UAV networks in order to decouple the mission and communication tasks. We propose a modular relay positioning and trajectory planning algorithm that guarantees connectivity of the UAV mission team with minimum number of relays and feasible trajectories, where the cost, network structure and setup can be changed, allowing its use for different types of missions, without relying on infrastructure. We propose different approaches to relay position decisions and compare the proposed schemes with an ideal scheme and a Voronoi-based benchmark scheme. Our results show that different solutions are applicable for achieving fewer number of relay nodes, higher utilization or lower number of hops between the nodes. With the proposed scheme the maximum number of relays in the air can be reduced by up to 40% and utilization can be increased up to 50% in comparison to the benchmark scheme, with less average traveled distances and average velocities for the relay nodes. These advantages come with a cost of higher maximum number of hops compared to the benchmark
Search for higgsinos decaying to two Higgs bosons and missing transverse momentum in proton-proton collisions at s√ = 13 TeV
No full textResults are presented from a search for physics beyond the standard model in proton-proton collisions at s = 13 TeV in channels with two Higgs bosons, each decaying via the process H → bb ¯ , and large missing transverse momentum. The search uses a data sample corresponding to an integrated luminosity of 137 fb−1 collected by the CMS experiment at the CERN LHC. The search is motivated by models of supersymmetry that predict the production of neutralinos, the neutral partners of the electroweak gauge and Higgs bosons. The observed event yields in the signal regions are found to be consistent with the standard model background expectations. The results are interpreted using simplified models of supersymmetry. For the electroweak production of nearly mass-degenerate higgsinos, each of whose decay chains yields a neutralino (χ~10) that in turn decays to a massless goldstino and a Higgs boson, (χ~10) masses in the range 175 to 1025 GeV are excluded at 95% confidence level. For the strong production of gluino pairs decaying via a slightly lighter (χ~20) to H and a light (χ~10), gluino masses below 2330 GeV are excluded.BMBWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, FAPERGS, and FAPESP (Brazil); MES and BNSF (Bulgaria); CERN; CAS, MoST, and NSFC (China); MINCIENCIAS (Colombia); MSES and CSF (Croatia); RIF (Cyprus); SENESCYT (Ecuador); MoER, ERC PUT and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRI (Greece); NKFIA (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); MES (Latvia); LAS (Lithuania); MOE and UM (Malaysia); BUAP, CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI (Mexico); MOS (Montenegro); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS, RFBR, and NRC KI (Russia); MESTD (Serbia); MCIN/AEI and PCTI (Spain); MOSTR (Sri Lanka); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR, and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (U.S.A.). Individuals have received support from the Marie-Curie program and the European Research Council and Horizon 2020 Grant, contract Nos. 675440, 724704, 752730, 758316, 765710, 824093, 884104, and COST Action CA16108 (European Union); the Leventis Foundation; the Alfred P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the F.R.S.-FNRS and FWO (Belgium) under the "Excellence of Science-EOS"-be.h project n. 30820817; the Beijing Municipal Science & Technology Commission, No. Z191100007219010; the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Deutsche Forschungsgemeinschaft (DFG), under Germany's Excellence Strategy -EXC 2121 "Quantum Universe" -390833306, and under project number 400140256-GRK2497; the Lendulet ("Momentum") Program and the Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences, the New National Excellence Program UNKP, the NKFIA research grants 123842, 123959, 124845, 124850, 125105, 128713, 128786, and 129058 (Hungary); the Council of Science and Industrial Research, India; the Latvian Council of Science; the Ministry of Science and Higher Education and the National Science Center, contracts Opus 2014/15/B/ST2/03998 and 2015/19/B/ST2/02861 (Poland); the Fundacao para a Ciencia e a Tecnologia, grant CEECIND/01334/2018 (Portugal); the National Priorities Research Program by Qatar National Research Fund; the Ministry of Science and Higher Education, projects no. 07232020-0041 and no. FSWW-2020-0008, and the Russian Foundation for Basic Research, project No. 19-42-703014 (Russia); MCIN/AEI/10.
13039/501100011033, ERDF "a way of making Europe", and the Programa Estatal de Fomento de la Investigacion Cientifica y Tecnica de Excelencia Maria de Maeztu, grant MDM-2017-0765 and Programa Severo Ochoa del Principado de Asturias (Spain); the Stavros Niarchos Foundation (Greece); the Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University and the Chulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand); the Kavli Foundation; the Nvidia Corporation; the SuperMicro Corporation; the Welch Foundation, contract C-1845; and the Weston Havens Foundation (U.S.A.).Publisher versio
Customer prioritization, product complexity and business ties: implications for job stress and customer service performance
No full textPurpose: Drawing on the theoretical lens of the job demands-resources model, this study builds upon and tests a conceptual model that links customer prioritization, product complexity, business ties, job stress and customer service performance. Conceptualizing customer prioritization and product complexity as job demands and business ties as personal job resources, this research explicates the mediating process by which customer prioritization and product complexity affect customer service performance through job stress and its boundary conditions. The purpose of this paper is to offer a theoretical framework in which business ties moderates the mediated relations of customer prioritization and product complexity to customer service performance. Design/methodology/approach: Structural equation modeling and a moderated mediation analysis were used on a unique multi-level, multi-respondent data set of 248 participants from 124 small and medium-sized enterprises in Turkey. Findings: This study finds that both customer prioritization and product complexity increase job stress. In addition, this paper finds that business ties have a bitter-sweet nature as a personal resource and reverse the relation of customer prioritization to job stress while strengthening the negative direct relation of product complexity to job stress. Finally, this study finds that the indirect relation of customer prioritization to customer service performance through job stress is contingent on business ties. Specifically, this paper finds that high levels of business ties negate the indirect relation of customer prioritization to customer service performance while low levels of business ties exacerbate the negative effects of customer prioritization to customer service performance, channeled through job stress. Practical implications: The findings demonstrate the critical role that personal networks play in reducing job stress and enhancing customer service performance for small and medium-sized enterprises that adopt customer-centric strategies such as customer prioritization. Nevertheless, the results suggest that the managers need to cognizant of the undesirable consequences of business ties may have on job stress when boundary-spanners handle a wide range of products/services that are technically complex. Accordingly, this study recommends small and medium-size enterprise managers and owners should be cautious in resource allocation to establish informal, personal ties with suppliers, competitors, customers and other market collaborators. Originality/value: This paper offers a deeper perspective of the relations of customer prioritization and product complexity to job stress and customer service performance. This study also specifies business ties as a personal coping resource, which decreases the undesirable consequences when used in small and medium enterprises that adopt customer-centric strategies.American University of Sharja
Türkiye'de ev dekorasyonu objelerinin yeni lüksü: 2000'lerden günümüze tüketim motivasyonları ve statü ilişkilerini anlamak için kuramsal bir çerçeve
No full textIn the 2000s, changing socio-economic and political structures of Turkey have affected luxury consumption practices. A new modern conservative class has emerged in Turkey. The conservative lifestyle has gained a new dimension within the scope of a universal modernity perception and gained visibility in the public sphere. Luxury consumption styles of the conservative lifestyle have been reaestheticized in universal aesthetic discourse and spread among the upper and middle class. Thus, the decorative objects of the luxury traditionally inspired modern and/or innovative have become a popular and trendy taste. The literature review about this specific topic reveals that there is a theoretical gap in analyzing the luxury decorative objects of traditionally inspired modern and/or innovative. To fill this gap, the thesis aims at two aspects. Firstly, the theory of "modest conspicuous" aestheticism was obtained in the light of Veblen's theory of the leisure class and Bourdieu's theory of distinction. The theory was formed through the decorative objects of the Hiref and Armaggan luxury decoration brands. It has been determined that the traditional motives were articulated on the modern form. Secondly these home decorative objects, one of the luxury consumption practices of modern and tradition-preserving lifestyle, were examined through this theoretical perspective. The standpoint that conservatism is a mediator factor to establishing domination by the upper class has been analyzed through the design of these objects. Thus, it has been determined that the conservative, which is preserving traditional, design discourse functions as a tool in maintaining the dominance of the upper class.Türkiye'de 2000'li yıllar içinde değişen sosyal, ekonomik ve siyasi yapılar, lüks tüketim pratiklerini etkilemiştir. Türkiye'de yeni bir modern muhafazakâr sınıf ortaya çıkmıştır. Muhafazakâr yaşam tarzı, evrensel bir modernite anlayışı kapsamında yeni bir boyut ve kamusal alanda görünürlük kazanmıştır. Muhafazakâr yaşam tarzının lüks tüketim stilleri ise evrensel estetik söylem bağlamında yeniden estetize edilerek üst ve orta sınıf içinde yayılmıştır. Böylece, gelenekselden ilham alan modern ve/veya yenilikçi lüksün dekoratif objeleri, popüler ve modaya uygun bir tat haline geldi. Bu spesifik konuyla ilgili literatür taraması, gelenekselden ilham alan modern ve/veya yenilikçi lüks dekoratif nesnelerin analizinde teorik bir boşluk olduğunu ortaya koymaktadır. Bu boşluğu doldurmak için tez iki yönü hedeflemektedir. İlk olarak, "mütevazı göze çarpan" estetizm teorisi, Veblen'in aylak sınıfın teorisi ve Bourdieu'nun ayrım teorisi ışığında elde edilmiştir. Teori, lüks dekorasyon markalarından olan Hiref ve Armaggan markalarının dekoratif objeleri üzerinden oluşturulmuştur. Geleneksel motiflerin modern form üzerine eklemlendiği tespit edilmiştir. İkinci olarak modern ve gelenekleri koruyan yaşam tarzının lüks tüketim pratiklerinden biri olan bu ev dekoratif objeleri bu teorik bakış açısıyla incelenmiştir. Muhafazakârlığın üst sınıf tarafından tahakküm kurmada aracı faktör olduğu görüşü, bu objelerin tasarımı aracılığıyla analiz edilmiştir. Böylece gelenekseli koruyan muhafazakar tasarım söyleminin üst sınıfın egemenliğini sürdürmede bir araç olarak işlev gördüğü tespit edilmiştir
Günlük tütün teslimatı için bölünmüş teslimatlı araç rotalama problemi
No full textOne of the Turkey's largest cigarette manufacturer, located in Izmir, receives distributors' orders from all over Turkey every day. Processed and packed cigarettes are distributed to all distributors in different locations by trucks or trailers. The planning process includes the distribution of which vehicle and order the distributor will be sent, which means the problem of vehicle routing. In this study, a mixed integer linear programming model (MILP), consisting of heterogeneous vehicle fleet and split delivery, was developed to produce a solution to the vehicle routing planning problem involving the distribution of an average of 30,000 cigarette boxes delivered by 30 different vehicles daily. The purpose of the mathematical model is to minimize total shipping fixed and variable costs, including fuel costs, the cost of using each vehicle, the cost of visiting the distributor, and the extra vehicle costs (bridge or highway).The purpose of the mathematical model consist of heterogeneous split delivery that minimize fixed and variable costs by determining the most appropriate route of the tobacco company which is distributing cigarette to distributors. The objective of the mixed integer linear programming model (MILP) is to minimize the total transportation costs, which includes the fuel costs, fixed cost of using each vehicle, the cost of visiting a distributor and the extra vehicle costs (bridge or highway). To solve larger instances of the problem, which cannot be solved efficiently with the exact method, located based clustering heuristic algorithm is developed. Experimental results show that the developed algorithm performs well and produces quality results in shorter times and meets the performance targets of the company in question.Türkiye'nin büyük sigara üreticilerinden biri, İzmir de bulunan fabrikasından, her gün ülkenin dört bir yanındaki distribütörlerinden aldığı sigara siparişlerini, ertesi gün deposundan sevk etmektedir. İşlenmiş ve kutulara yerleştirilmiş sigaralar tırlar ve kamyonlar yardımı ile distribütörlere dağıtılmaktadır. Distribütör siparişlerinin hangi araçla ve sırayla gönderiminin planlaması, araç rotalama problemini ortaya çıkarmaktadır. Bu çalışmada, günlük sevk edilen ortalama 30.000 sigara kutusunun, 30 farklı araçla dağıtımını içeren araç rotalama planlaması problemine çözüm üretebilmek için, en uygun dağıtım rotaları belirleyen, heterojen araç filo ve bölünmüş teslimattan oluşan tamsayı karışık doğrusal programlama modeli (TKDP) geliştirildi. Matematiksel modelin amacı, yakıt maliyetlerini, her bir aracı kullanma maliyetini, distribütörü ziyaret etme maliyetini ve ekstra araç maliyetlerini (köprü veya otoyol) içeren toplam nakliye sabit ve değişken maliyetlerini en aza indirmektir. Modele ek olarak, istenilen sürede etkin bir şekilde çözülemeyen büyük örneklerini çözmek için konum tabanlı kümeleme sezgisel (KTKS) yöntem geliştirilmiştir. Sonuçlar, geliştirilen algoritmanın müşteri sayısı arttığında iyi performans gösterdiğini, daha kısa sürede kaliteli sonuçlar ürettiğini, söz konusu şirkete uygulanabilir olduğunu ve maliyet avantajı sağladığını göstermektedir
Uncertainty assessment for detection of spoofing attacks to speaker verification systems using a Bayesian approach
No full textThere has been tremendous progress in automatic speaker verification systems over the last decade. Still, spoofing attacks pose a significant challenge to their deployment. Even though there are various attack techniques such as voice conversion and speech synthesis, replay attacks pose one of the most important types since they can be done without significant expertise in speech technology. Moreover, replay attacks are hard to detect because they are done with simple replay of the original audio. The problem has gained more attention since the introduction of the ASV spoof 2017 challenge, which included a well-designed database with realistic replay attack conditions. Even though many different deep network types and acoustic features were proposed since the challenge, one key issue, which is model uncertainty around the neural networks’ decision is largely ignored. This is a result of using the softmax function with the cross-entropy loss, which is widely used in many domains. Here, we propose using evidential deep learning, which is a recently proposed method that is rapidly gaining popularity, for assessing the model uncertainty around the network's decision. Experimental results show that the investigated network architectures perform better in terms of equal error rate with the new loss function. Moreover, reliability of measured uncertainty is shown by filtering samples out of the test set using the Bayesian uncertainty measure, which resulted with a consistent decrease in EER with decreasing threshold