5916 research outputs found
Sort by
Reassessment of bill management by batteries with various TOU tariffs: A pilot project from Turkey
No full textYesilirmak Distribution System Operator, one of Turkey's leading distribution system operators, carried out a pilot project with the support of the university in order to be technically ready when its customers want to manage their bills through batteries and to understand the challenges and benefits of batteries in the network operation. This study describes the creation of the electrical connection diagram of the battery, the completion of the financial analysis under different tariffs, and the development of a mathematical model for bill management optimization at the planning stage of the pilot project, which was completed based on the prediction that the behind-the-meter batteries will increase in the near future. While energy storage systems change the grid consumption curves of customers by Time-of-Use (TOU) tariffs, they also provide a certain amount of savings in bills
The rise of mobile Marketing: A decade of research in review
No full textParalleling the growing space mobile phones take in today's consumers' daily routines, academic mobile marketing research has been growing at an increasing pace recently. The presence of multiple players in the mobile eco-system and the wide range of topics under investigation, coupled with the fragmented nature of the mobile marketing domain, call for an updated unifying framework. Accordingly, this review looks at the last decade of mobile marketing research and provides an overview by offering an integrated framework and an extensive review of the research in this domain. Based on a database of 178 articles published in top marketing journals over the last decade, we formulate a framework that is based on (1) the transformation of consumer behavior considering the shifts in users' lifestyles, (2) the effects of mobile on the transformation of existing and the emergence of new businesses, and (3) the integration of mobile within the existing channel mix and its interaction with other channels. In this framework, we first classify each article under various research themes, type of data collection, and their dependent and independent variables. We then synthesize the extant literature in each of the sub-research topics under our framework: the mobile transformations of consumers and businesses, mobile applications, mobile channel deployment and integration, mobile advertising and promotions, promotions, how mobile facilitates consumer-to-business connections, and mobile data. This review provides insights on the recent evolution of the mobile marketing field as well as presenting avenues for future research
Otizm spektrum bozukluğunda çocuk yetiştiren babaların tecrübeleri: Nitel araştırma
No full textThe purpose of this study was to describe the experiences of fathers who have an only-child with Autism Spectrum Disorder (ASD) using Ambiguous Loss framework. Sample was consisted of 10 fathers, one father being the pilot of the study. Main foci of the research were whether ambiguous loss is a contributing factor in relation with stress levels of fathers raising a child with ASD. Moreover, whether their personal experiences of ambiguous loss impacted family systems through boundary ambiguity was also explored. Semi-structured interviews were conducted with each father. The qualitative method of thematic analysis gave rise to 2 super-ordinate themes, 9 themes and 10 subthemes. First super-ordinate theme "Process of Acceptance" included 5 themes and 8 sub-themes: 1) "konduramama": straining self to accept ASD; 2) incomprehensibility of ASD; 3) emotional processes, 3a) feelings of guilt, 3b) pendulum of hope, 3c) concern for future; 4) receiving proper education, 5) making peace with ASD, 5a) increasing knowledge of disorder, 5b) reframing the situation, 5c) solution-orientedness, 5d) maintaining stability, 5e) attributions to something greater. This theme explained the stress increasing factors that fed fathers' inner conflict regarding the acceptance or rejection of the ASD and the ambiguity it brings. Moreover, those factors helping fathers to deal with the stress was explained. It is seen that most fathers were resilient enough to learn to live with the stress that their ambiguous loss brought. The second super-ordinate theme was "Impact on Family Life" and it included 5 themes and 2 sub-themes as follow: 6) shaping the world around ASD; 7) impact on couple relationship, 7a) emotional turmoil, 7b) positive emotional shift; 8) father as an outside support system; 9) estrangement of relationships. The fathers' experiences confirmed that ambiguous loss has increased their stress on their acceptance process of the disorder as well as on their family lives. Moreover, the boundary ambiguity was seen to be the main stressor on the impact on family life. It created an ambiguity on the roles and identities of the family member by changing the structure of the family in various ways. Ambiguous loss provides a unique understanding to the losses that are hard to capture. The results can inform interventions in couple and family therapies such as normalizing and externalization of the stressful father and families' experiences. Future studies can focus more on social relationship component of ASD from a paternal and familial context. Limitations and further information is discussed.Bu çalışmanın amacı Belirsiz Kayıp çerçevesini kullanarak çocuğu Otizm Spektrum Bozukluğu (OSB) olan, tek çocuklu babaların deneyimlerini anlatmaktır. Örneklem 10 babadan oluşmakta olup, 1 baba çalışmanın pilotudur. Araştırmanın ana odaklarından ilki, belirsiz kaybın ASD'li bir çocuğu yetiştiren babaların stres düzeylerine katkıda bulunan bir faktör olup olmadığıdır. Ikinci odağı ise, belirsiz kayıp deneyimlerinin sınır belirsizliği yoluyla aile sistemlerini etkileyip etkilemediğidir. Her baba ile yarı yapılandırılmış görüşmeler yapılmıştır. Nitel bir araştırma yöntemi olan tema analizi ile 2 üst düzey tema, 9 tema ve 10 alt tema ortaya konmuştur. İlk üst düzey tema olan "Kabul Süreci", 5 tema ve 8 alt temayı içermektedir. Bunlar sırasıyla: 1) "konduramama": ASD'yi kabul etmek için kendini zorlama; 2) ASD'nin anlaşılmazlığı; 3) Duygusal süreçler, 3a) Suçluluk duygusu, 3b) Umut sarkaçı, 3c) Ggelecek için endişe; 4) Uygun eğitimi almak, 5) ASD ile barış yapmak, 5a) OSB bilgisini arttırmak, 5b) Durumu yeniden çerçevelendirmek, 5c) Çözüm odaklılık, 5d) İstikrarı korumak, 5e) Daha büyük bir şeye atıflar. Bu tema, babalara ASD'nin kabulü veya reddi ve getirdiği belirsizlikler ile ilgili iç çatışmaların besleyen stress faktörleri ile beraber, strese yardımcı faktörleri açıklamaktadır. Çoğu babanın belirsiz kayıplarının getirdiği stresle yaşamayı öğrenecek kadar dirençli olduğu görülmektedir. İkinci üst düzey tema olan "Aile Hayatı Üzerindeki Etki" ise 5 tema ve 2 alt tema içermektedir: 6) Dünyayı OSB çevresindeki şekillendirmek; 7) Çift ilişkisine etkisi, 7a) Duygusal kargaşa, 7b) Olumlu duygusal değişimler; 8) Dış destek sistemi olarak baba; 9) İlişkilerde uzaklaşma. Babaların deneyimleri, belirsiz kaybın, OSB'nin aile yaşamları üzerindeki stresini de arttırdığını doğruladı. Ayrıca, sınır belirsizliğinin aile hayatı üzerindeki etkisinin ana stres unsurlarından olduğu görülmektedir. Sınır belirsizliğinin ailenin yapısını çeşitli şekillerde değiştirerek aile üyelerinin rolleri ve kimlikleri konusunda bir belirsizlik yarattığı ortaya konmuştur. Belirsiz kayıp, fark edilmesi zor olan kayıplara benzersiz bir anlayış sağlamaktadır. Sonuçlar, babaların ve ailelerin mücadelesinin normalleştirilmesi ve dışsallaştırılması gibi, çift ve aile terapilerinde sıklıkla kullanılan müdahaleleri şekillendirebilir. Gelecekteki çalışmalar, baba ve ailesel bağlamdan ASD'nin sosyal ilişki bileşenine daha fazla odaklanabilir. Sınırlılıklar ve daha fazla detay yazının geri kalanında tartışılmaktadır
Üç faz çiftyönlü elektrikli araç şarj devresinin modellenmesi ve simülasyonu
No full textThe aim of this research is to investigate how an electric vehicle (EV) charger with controllers performs and affects the EV battery, integrated to the grid. At present, typical applications of EV chargers usually include only charging of the vehicle battery providing unidirectional power flow between the power grid and EV. The proposed three-phase grid connected EV charger system enables bidirectional power flow, sending unused energy in EV battery back to the electricity grid in the scope of V2G operation in addition to conventional charging of the battery. The EV charger circuit consists of two stages, one of which is three-phase AC/DC PWM converter and the other is synchronous DC/DC converter, between which a DC link capacitor having 800V rated bus voltage is inserted. Also, a Li-ion battery pack with the nominal voltage of 500V is used for the system. LCL filter is utilized for AC/DC part of the charger to attenuate line current ripples and the other components are selected based on the theoretical analysis performed as well. Two-loop control algorithms, of which design parameters are calculated using some detailed mathematical analysis, are implemented for both AC/DC converter and DC/DC one to achieve tight voltage & current regulations for the EV charger. Then the performance of the bidirectional EV charger circuit is evaluated via some simulation work in Matlab/Simulink based on closed-loop operation and harmonic contents for grid side. Simulation results are discussed to analyze the closed-loop performance of the EV charger system during various conditions and the developed theory regarding control system design is verified. Harmonics & THD values of line currents are also investigated for various battery voltage levels using the obtained results. In addition, loss analysis is performed to show that the bidirectional EV charger system can operate with high efficiency values.Bu çalışmanın amacı, şebekeye bağlı bir elektrikli araç şarj devresinin kontrolcü ile birlikte nasıl bir performans gösterdiğini ve araç bataryasını nasıl etkilediğini incelemektir. Günümüzde elektrikli araç şarj istasyonlarının tipik uygulamaları genellikle şebeke ve araç arasında tek yönlü güç transferi sağlayarak sadece araç bataryasını şarj etmeyi içermektedir. Önerilen şebekeye bağlı üç faz elektrikli araç sarj sistemi aracın şarj edilmesinin yanında araç bataryasında kullanılmayan enerjiyi elektrik şebekesine göndermekte ve "araçtan şebekeye" konsepti ile iki yönlü güç transferini mümkün kılmaktadır. Elektrikli araç şarj devresi AC/DC PWM dönüştürücü ve DC/DC senkron çevirici olmak üzere iki kısımdan oluşmaktadır. Bu iki dönüştürücü arasında 800V nominal gerilim değerinde DC link kondansatör bulunmaktadır. Ayrıca sistem için çıkışta 500V değerinde Li-ion batarya kullanılmaktadır. Akım dalgalanmalarını sönümlemek için ise şarj devresinin AC/DC tarafında LCL filtreden yararlanılmıştır. Şarj sisteminin sıkı gerilim ve akım regülasyonunu sağlamak amacıyla çift döngü kontrol algoritması hem AC/DC çevirici hem de DC/DC dönüştürücü için uygulanmaktadır. İlgili kontrol algoritmalarının parametreleri detaylı matematiksel analizlere dayanarak hesaplanmıştır. Daha sonra çift yönlü elektrikli araç şarj sisteminin performansı kapalı çevrim çalışma ve şebeke tarafındaki harmonik içerikleri bakımından bazı simülasyon çalışmaları kapsamında Matlab/Simulink üzerinde incelendi. Simülasyon sonuçları elektrikli araç şarj sisteminin çeşitli koşullar altındaki kapalı çevrim performansını değerlendirmek için ele alındı ve kontrol sistemlerinin tasarımına ilişkin geliştirilen teori doğrulandı. Ayrıca şebeke akımlarının harmonikleri ve THD değerleri elde edilen sonuçlara göre çeşitli batarya gerilim değerleri için incelendi. Ek olarak şarj sisteminin yüksek verimlilikle çalıştığını göstermek için kayıp analizi yapıldı
Handling epistemic and aleatory uncertainties in probabilistic circuits
No full textWhen collaborating with an AI system, we need to assess when to trust its recommendations. If we mistakenly trust it in regions where it is likely to err, catastrophic failures may occur, hence the need for Bayesian approaches for probabilistic reasoning in order to determine the confidence (or epistemic uncertainty) in the probabilities in light of the training data. We propose an approach to Bayesian inference of posterior distributions that overcomes the independence assumption behind most of the approaches dealing with a large class of probabilistic reasoning that includes Bayesian networks as well as several instances of probabilistic logic. We provide an algorithm for Bayesian inference of posterior distributions from sparse, albeit complete, observations, and for deriving inferences and their confidences keeping track of the dependencies between variables when they are manipulated within the unifying computational formalism provided by probabilistic circuits. Each leaf of such circuits is labelled with a beta-distributed random variable that provides us with an elegant framework for representing uncertain probabilities. We achieve better estimation of epistemic uncertainty than state-of-the-art approaches, including highly engineered ones, while being able to handle general circuits and with just a modest increase in the computational effort compared to using point probabilities.United States Department of Defense US Army Research Laboratory (ARL) ; U.K. Ministry of Defenc
Multi-user massive MIMO visible light communications with limited pilot transmission
No full textVisible light communication (VLC) building on the existing illumination infrastructure utilizes light emitting diode (LED) luminaries as wireless transmitters. To achieve data rates on the order of gigabits per second in VLC systems, multiple-input multiple-output (MIMO) transmission has been identified as a key technology. In this paper, we consider a centralized network architecture where the ceiling LED luminaries act as transmitter elements of a distributed massive MIMO VLC system. To obtain the full benefits of massive MIMO, channel state information must be available at the transmitter side. Downlink (DL) channel estimation in a massive MIMO system requires huge pilot overhead in DL as well as feedback overhead in uplink. This makes the implementation of massive MIMO system infeasible if not properly designed. In our study, we address the design of massive MIMO VLC systems with a limited number of DL pilot signals. We explore different DL pilot patterns (PPs) in frequency, time, and spatial domains where interpolation is performed to obtain the global channel matrix taking advantage of the indoor environment geometry and layout of luminaries. We then present data rate results for different DL PPs under the consideration of varying number of active user equipments through Monte-Carlo simulations
FIFA oyun verisi kullanarak futbolda oyuncu piyasa değerini belirleyen faktörlerin tespiti
No full textFutbol, son onyıllarda dünyadaki en popüler sporlardan biri haline gelmiştir. Artan popülerliği ile birlikte futbol, büyüyen milyar dolarlık bir pazar halini almıştır. Büyük Avrupa liglerindeki üst düzey oyuncuların transferleri için yüksek meblağlar ödenmektedir. Bu durum, futbolcuların piyasa değerlerine dikkat çekilmesine sebep olmuştur. Bu alandaki ucu açık konulardan birisi ise futbol oyuncularının piyasa değerlerini belirleyen faktörlerin tespitidir. Daha önce bu faktörlerin bir kısmı üzerine araştırmalar yapılmış olmasına rağmen odak noktası genellikle saha içi istatistikler olmuştur. Bu tez kapsamında benzersiz bir veri seti kullanılmakta ve futbol oyuncularının FIFA 2015, 2016, 2017 ve 2018 oyunlarındaki esas özellik ve niteliklerine odaklanılmaktadır. Oyuncu piyasa değerleri "transfermarkt.com" adresinden temin edildi. 2014-2015, 2015-2016, 2016-2017 ve 2017-2018 sezonlarının her biri için Avrupa'nın en büyük 5 liginde (İngiliz Premier Ligi, İspanyol La Liga, Alman Bundes Liga, İtalyan Serie A ve Fransız Lig 1) en az doksan dakika sahada kalan futbolcular analiz edildi. Çeşitli değişken seçme metotları kullanılıp Sıradan En Küçük Kareler modelleri oluşturularak defans, orta saha ve hücum bölgelerindeki spesifik alt pozisyonlarda oynayan oyuncuları değerli kılan en önemli demografik, takımsal, fiziksel, teknik ve mental özellik ve nitelikler her sezon için tespit edildi. Farklı alt pozisyonlarda (Stoper, Bek, Merkezi Defansif Orta Saha, Merkezi Orta Saha, Kanatçı ve Forvet) oynayan oyuncuları değerli kılan farklı özellikler ve nitelikler olduğu gösterildi. Her 4 sezon ve 6 alt pozisyon için oluşturulan Sıradan En Küçük Kareler modellerinin çıktıları paylaşıldı
CWT-DPA: Component-wise waiting time for BC-enabled data plane authentication
No full textSoftware-Defined Networking (SDN) is a promising networking paradigm that brings central management and network programmability to improve existing networking systems. However, SDN has several security threats due to its untrusted control and data planes. Blockchain (BC) technology has recently provided a fault-tolerant, decentralized, and immutable ledger among untrusted parties. While the integration between SDN and BC enhances the security, it suffers from performance degradation when applied to SDN's data plane. In traditional BC-SDN approaches, such as our previous work DPSEC (Latah and Kalkan, 2020), every switch has to wait for the final commitment of each submitted transaction, which significantly decreases the performance of the BC-SDN model. In this work, we enhance the performance of BC-SDN data plane approaches by separating switch-related and host-related transactions and propose a different waiting strategy for each type of data plane transaction. We also propose a batching technique to enhance the average latency for high-load scenarios. In addition, SDN switches and controllers utilize lattice-based signatures and Key Encapsulation Methods (KEMs) to protect against quantum adversaries. We compare the performance of CWT-DPA with existing solutions such as SSL/TLSv1.3, DPSEC (Latah and Kalkan, 2020), and AuthFlow (Mattos and Duarte, 2016)
Experimental impact analysis of the refrigerator cable design on disturbance power test
No full textThe ever-increasing variety of electronic products brings with it many tests and controls. Especially for a product such as a refrigerator, which has an important place in the lives of users and works non-stop for almost its entire life, all compatibility tests that may affect the end-user must be carried out. Electromagnetic compatibility (EMC) tests are the most critical of these tests. In this study, the effect of the disturbance power test, one of the EMC tests, on the changing properties of the product was investigated. The effect of three different cable structures used in the refrigerator on the disturbance power test was investigated. These tests are carried out to cover 10 different frequencies in three products using different cable structures. Tables containing the oscilloscope results of these tests and the margin values corresponding to the frequencies are included in the document. In addition, visuals containing the differences between each cable structure and cable have been added. The results and analyzes of these tests are included in the report
Simulation-based design and locomotion control implementation for a lower body exoskeleton
No full textThis paper proposes a simulation-based design and locomotion control methodology for an exoskeleton that is aimed at providing assistance to users with ambulatory difficulties. To increase the power-to-weight ratio while satisfying design constraints, we made use of simulation tools to recursively update the initial mechanical design for a finer solution. To this end, a coupled human-exoskeleton model was constructed in MSC ADAMS environment using an average human model and the initial design of the robot. Following this step, dynamic walking control simulations were carried out to determine actuator torques and loading. Using the loading data obtained via simulation experiments, certain mechanical links were optimized such that the portions with no stress concentration were removed without violating safety. Finally, two distinct control implementations were conducted: i) stand-to-sit motion, ii) dynamic walking. As a result, we obtained dynamically consistent motion behavior for both cases, adequately validating the proposed methodology.TÜBİTA