5916 research outputs found
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Bio-realistic neural network implementation on loihi 2 with izhikevich neurons
No full textNeuromorphic systems are designed to emulate the principles of biological information processing, with the goals of improving computational efficiency and reducing energy usage. A critical aspect of these systems is the fidelity of neuron models and neural networks to their biological counterparts. In this study, we implemented the Izhikevich neuron model on Intel's Loihi 2 neuromorphic processor. The Izhikevich neuron model offers a more biologically accurate alternative to the simpler leaky-integrate and fire model, which is natively supported by Loihi 2. We compared these two models within a basic two-layer network, examining their energy consumption, processing speeds, and memory usage. Furthermore, to demonstrate Loihi 2's ability to realize complex neural structures, we implemented a basal ganglia circuit to perform a Go/No-Go decision-making task. Our findings demonstrate the practicality of customizing neuron models on Loihi 2, thereby paving the way for constructing spiking neural networks that better replicate biological neural networks and have the potential to simulate complex cognitive processes.Intel's Neuromorphic Research Community (INRC) ; ITU Scientific Research Projects OfficePublisher versio
Direct online booking competence of five-star hotels: Model development on web/mobile sites
No full textHotel businesses focus on diversifying the tools on their hotel web and mobile sites to drive higher returns, conversions, and profit. This orientation has also converged with the pandemic effects. In response to these challenges and opportunities, this study aims to propose a model for assessing the direct online booking competence of hotel businesses via their web and mobile sites. Designed as a multiple case study including 22 hotels, the study proposes an assessment framework (web and mobile site-based direct online booking competence) with an extensive checklist of 107 items in six dimensions (informative and experiential content, user interface, promotional, mobile, and crisis communication). The framework is also effective to classify hotels according to their web and mobile site-based direct online booking competence such as optimal, effective, functional, dynamic, and practical performers with reference to their strengths and weaknesses. The framework serves as a comprehensive assessment tool for hotel businesses to evaluate their position in relation to their competitors and improve their direct online booking competence. Potential customers also consider the necessity of all the index items in hotel web and mobile sites; however, promotional competence followed by mobile and crisis communication is regarded as the most critical dimension.Publisher versio
Intersubjectivity as an analytical concept to study human-animal interaction in historical context: street dogs in Late Ottoman period
No full textHuman knowledge pertaining to human-animal interaction is constructed by the human author, albeit the presence of animal subjects. Such a human lens is pronounced when studying human-animal interactions across history, whose nonhuman animal subjects are not only absent, and therefore eliminating the possibility of conducting empirical studies in situ, but also their experiences are filtered by the interpretative lens of human authors of extant historical accounts as well as contemporary human analysts who interpret these accounts. This article draws upon such epistemological limitations of understanding nonhuman animal presence in historical accounts and offers human-animal intersubjectivity as an analytical concept, involving generative iterability and indistinctive boundaries that emphasise intersubjective openness and relationality, to trace and disclose the continuity of human-animal co-existence. The article’s historical scope is the Late Ottoman period characterised by a sense of temporal and spatial disorientation and reorientation for humans as well as street dogs during its modernisation processes.Publisher versio
Silikon ve InGaAs tabanlı tek foton dedektörlerinin karakterizasyonu ve ticarileştirilmesi.
No full textThis thesis delves into the intricacies of quenching circuitry, specifically tailored for free-running single photon detectors working within the visible and near-infrared spectra. It embarks on a comprehensive exploration, commencing with an in-depth analysis of designing quenching circuitry customized for Silicon and InGaAs avalanche photodiodes (APDs). This investigation thoroughly examines the merits and drawbacks of various quenching circuit topologies, elucidating their diverse applications. The challenges inherent in Silicon and InGaAs APDs are examined, highlighting optimization strategies for quenching and resetting circuitry while navigating electronic intricacies. Moreover, an emphasis is placed on developing a CubeSat compatible, miniaturized design, detailing its schematic blueprint. The thesis explicitly covers the processes of designing, testing, debugging, and characterizing these detectors from both electronic and optical standpoints, providing detailed insights into the experimental outcomes. Parameters such as dead time, timing jitter, afterpulsing, and photon detection efficiency are scrutinized, elucidating their electronic ramifications on the designs. Comprehensive explanations are provided regarding the testing and characterization methodologies employed. Furthermore, the thesis showcases three distinct single photon detector schematics and their corresponding PCB designs. It outlines the development of two disparate high voltage amplifier designs, crafted to meet the requisite parameters for these detectors, all of which have evolved into viable commercial products. v This comprehensive exploration combines theoretical insights with practical implementations, culminating in a refined understanding of quenching circuitry intricacies tailored explicitly for free-running single-photon detectors. The resulting designs and methodologies represent a gathering of interdisciplinary knowledge, offering profound implications for the advancement of single photon detection technologies.Bu tez, görünür ve yakın kızılötesi spektrum içinde çalışan tetiklemesiz (free running) tek foton detektörleri için özel olarak tasarlanmış sönümleme devrelerinin inceliklerine inmektedir. Silikon ve InGaAs çığ fotodiyotları (APD'ler) için özelleştirilmiş sönümleme devrelerinin tasarımını derinlemesine analiz ederek kapsamlı bir keşifle başlamaktadır. Bu araştırma, çeşitli sönümleme devre topolojilerinin artılarını ve eksilerini ayrıntılı olarak inceleyerek çeşitli uygulamalarını açıklamaktadır. Silikon ve InGaAs APD'lerde bulunan zorluklar, elektronik karmaşıklıklara değinerek, sönümleme ve resetleme devrelerinin optimizasyon stratejilerini vurgulayarak incelemektedir. Ayrıca, küp uydu uyumlu, inyatürize edilmiş bir tasarımın geliştirilmesine odaklanarak, şematik tasarımı detaylandırılmaktadır. Tez, bu detektörlerin elektronik ve optik açılardan tasarlanması, test edilmesi, hata ayıklanması ve karakterize edilmesi süreçlerini ayrıntılı bir şekilde ele almakta olup, deneysel sonuçlara dair detaylı iç görüler sunmaktadır. Ölü zaman, zamansal belirsizlik, artçı sinyal ve foton algılama verimliliği gibi parametreler ve tasarımlar üzerindeki elektronik etkileri açıklayarak incelenmektedir. Kullanılan test ve karakterizasyon metodolojileri hakkında kapsamlı açıklamalar sunulmaktadır. Ayrıca, tez üç farklı tek foton detektörü şemasını ve bunların karşılık gelen PCB tasarımlarını sergilemektedir. Bu detektörlerin gereksinim duyduğu parametreleri karşılamak üzere hazırlanan iki farklı yüksek voltajlı amplifikatör tasarımının geliştirilmesini ayrıntılı olarak ele alır, ve hepsi başarılı ticari ürünlere dönüşmüştür. Bu kapsamlı araştırma, teorik bilgileri pratik uygulamalarla birleştirerek, tetiklemesiz tek vii foton detektörleri için özel olarak tasarlanmış sönme devrelerinin inceliklerinin rafine bir anlayışla birleşmesini anlatmaktadır. Ortaya çıkan tasarımlar ve metodolojiler, disiplinler arası bir bilgi birikimini temsil eder ve tek foton algılama teknolojilerinin gelişimi için derin etkiler sunmaktadır
Servikal omurga destek sistemi tasarımına yönelik titreşim odaklı çoklu cisimler dinamik modelinin geliştirilmesi.
No full textNeck injuries, a common issue with various causes, can range from mild discomfort to severe disability. Despite the abundance of biomechanical models of the cervical spine in the literature, their capabilities for modal and frequency response analysis are limited. A comprehensive head-cervical spine model was developed to address this gap, enabling frequency domain analysis. A multi-body dynamics model with 20 degrees-of-freedom was created using ADAMS software's frequency response analysis capabilities. This model incorporates various elements, including vertebrae, ligaments, and active and passive muscles. Validation was conducted against OpenSim data and existing experimental findings. The model was then employed to conduct a Design of Experiments (DoE) study, where key design factors of a conceptual neck support system were varied. Two vibration objective functions were selected to evaluate the parametric designs from the DoE matrix. The first function identifies the maximum value of the head's frequency response, while the second measures overall vibration within the frequency range of interest. In a case study, the model's capabilities were demonstrated, identifying optimum design parameters for the neck support system. This powerful model, particularly its capacity to calculate vibration-related performance metrics, has the potential to make significant contributions across various industries. Applications range from designing anti-vibration devices to reduce fatigue in the automotive and aerospace sectors to enhancing rehabilitation systems in healthcare, ultimately improving patient exercise effectiveness.Boyun yaralanmaları, çeşitli nedenlere sahip yaygın bir sorun olup hafif rahatsızlıktan ciddi sakatlığa kadar değişebilir. Literatürde boyun sistemmin biyomekanik modellerinin bolca bulunmasına rağmen, bu modellerin modal ve frekans tepki analiz yetenekleri sınırlıdır. Bu boşluğu doldurmak amacıyla kapsamlı bir baş-boyun sistem modeli geliştirilmiş ve frekans alanı analizi olanaklı hale getirilmiştir. 20 serbestlik derecesine sahip çoklu cisimler dinamiği modeli, ADAMS yazılımının frekans tepki analiz yetenekleri kullanılarak oluşturulmuştur. Bu model, omurlar, bağlar ve aktif ve pasif kaslar gibi çeşitli unsurları içermektedir. Doğrulama, OpenSim verileri ve mevcut deneysel bulgulara karşı gerçekleştirilmiştir. Model daha sonra parametrik tasarım çalışması yapmak için kullanılmış, bir kavramsal boyun destek sisteminin önemli tasarım faktörlerini değiştirme olanağı sunmuştur. DoE matrisinden parametrik tasarımları değerlendirmek için iki titreşim amaç fonksiyonu seçilmiştir. İlk fonksiyon başın frekans tepkisinin maksimum değerini tanımlarken, ikincisi ilgi alanındaki frekans aralığı içindeki genel titreşimi ölçmektedir. Bir vaka çalışmasında, modelin yetenekleri gösterilmiş ve boyun destek sistemi için optimum tasarım parametreleri tanımlanmıştır. Geliştirilen model, özellikle titreşimle ilgili performans metriklerini hesaplama kapasitesi sayesinde, çeşitli endüstrilerde önemli katkılarda bulunma potansiyeline sahiptir. Uygulamalar, otomotiv ve havacılık sektörlerinde yorgunluğu azaltmak amacıyla titreşimi önleyici cihazlar tasarlama işlerinden sağlık sektöründe rehabilitasyon sistemlerini geliştirerek hastaların egzersiz etkililiğini artırmaya kadar geniş bir yelpazeye yayılmaktadır
A deterministic fluid model for production and energy mode control of a single machine
No full textImproving machines' energy efficiency through dynamic energy mode control to meet demand requirements with minimal energy consumption is a promising approach. This study considers a machine operating in working, idle, off, and warmup energy modes with different energy consumption in each mode. A deterministic fluid model is developed to analyze an energy mode control policy that determines when to keep the machine working, off or idle, and switch to other modes based on the inventory/backlog level to minimize the total energy, inventory, and backlog costs. This approach facilitates the derivation of closed-form expressions for the optimal thresholds and the associated costs. This modeling approach allows us to prove that a policy that operates the machine between the working and off modes or the working and idle modes is always better than a hybrid policy that operates the machine in working, off, and idle modes simultaneously. We use the solution of the deterministic fluid model to propose an approximate policy for machines with stochastic production, warmup, and demand processes. We compare the results of the proposed approximation method with the optimal solution of a stochastic system where the production and warmup times are exponential and the demand inter-arrival times have Erlang distribution. The optimal solution for the stochastic system is determined by solving a Markovian Decision Process (MDP). Our numerical experiments show that the proposed approximation method predicts the optimal policy type for the stochastic case with a 89.3% accuracy, and the average error between the optimal cost and the cost obtained with the approximation method is 1.37% for 729 different cases tested. Furthermore, the computational efficiency of the proposed approximation is around 250 times better than the effort to determine the optimal policy using an MDP approach. We propose this approximation method where the control parameters are given in closed form as an easy-to-implement and effective policy to control energy modes to minimize the total energy, inventory, and backlog costs. Furthermore, we present the deterministic fluid modeling approach as a versatile approach to analyze energy mode control problems.TÜBİTAKPublisher versio
Strategic in/visibility of Turkish egg donors: Reproductive labor, secrecy, and stigma in the transnational bioeconomy
No full textDrawing on ethnographic fieldwork in a Northern Cypriot clinic, I examine how practices of secrecy function as strategic tools for invisibilization in the lived realities of Turkish egg donors engaged in an illicit, gendered, and stigmatized form of reproductive labor, both within and across national borders. Combining feminist studies of reproductive labor with an analysis of secrecy, stigma, and dirty work, I adopt a notion of secrecy as an embodied social practice to explore ethnographically how secrecy is integral to the bioavailability of Turkish egg donors. Secret practices enable these young women to intimately navigate gendered moral, health, socio-legal, and financial concerns within the challenging wider context of restrictive reproductive biopolitics, a legally ambigious cross-border biomedical market, fragile socio-economic conditions, and a heteropatriarchal sexual culture in Turkey. For Turkish egg donors, who opt for strategic invisibilization, moral and financial concerns sometimes override health and legal considerations. Secrecy sustains this transnational bioeconomy while simultaneously concealing its exploitative harms and risks.Kuzey Kıbrıs’taki bir klinikteki etnografik saha çalışmasına dayanarak, Türkiyeli yumurta donörlerinin gündelik yaşamlarının gerçekliği içerisinde gizlilik pratiklerinin nasıl stratejik araçlar olarak işlediğini inceliyorum. Bu pratikler, hem ulusal sınırlar içinde hem de dışında, cinsiyet temelli ve damgalanmış üreme emeğini yasadışı bir şekilde yürütüldüğü durumlarda görünmez kılmayı sağlar. Üreme emeği üzerine yapılmış feminist çalışmalarla gizlilik, damgalama ve pis iş analizini birleştirerek, gizlilik kavramını Türkiyeli yumurta donörlerinin biyoyararlanımında nasıl temel bir rol oynadığını etnografik olarak araştırıyorum. Gizlilik pratikleri, bu genç kadınların, Türkiye'deki kısıtlayıcı üreme biyopolitikaları, yasal olarak belirsiz bir sınır ötesi biyomedikal piyasa, kırılgan sosyo-ekonomik koşullar ve heteropatriyarkal bir cinsel kültür bağlamında cinsiyete dayalı ahlaki, sağlık, sosyo-hukuki ve finansal kaygıları yakından yönetmelerini sağlar. Stratejik görünmezliğe başvuran Türkiyeli yumurta donörleri için, bazen ahlaki ve finansal kaygılar sağlık ve yasal kaygıların önüne geçer. Gizlilik, bu ulusötesi biyoekonomiyi sürdürürken aynı zamanda sürece içkin olan sömürücü zararları ve riskleri örtbas eder.National Science Foundation (NSF
Kum ile radyatif soğutma.
No full textPassive radiative cooling is one of the upcoming technologies likely to help decrease the negative impacts of climate crises and reduce energy consumption in buildings. The principle of radiative cooling involves radiating heat from the surface of a building into space, thus reducing the reliance on air conditioning systems. Understanding the fundamentals of passive radiative cooling is important for thermal management related to buildings and industrial applications. The principle of radiative cooling in buildings involves selectively reflecting incident radiating heat from the surroundings and selectively emitting energy from a surface to the surroundings to achieve minimum heat load on the system. In the case of buildings, solar radiation incident on roofs can be reflected or absorbed. The absorbed heat is either transferred to the surrounding air by convection or it will be emitted back to the sky. If a surface is desired to be radiatively cooled it must have a large reflection of solar energy at the visible wavelength range and the highest radiation emission at the atmospheric window range (8-13 µm wavelength range) as discussed in detail in the thesis. This technique can significantly help reduce greenhouse gas emissions as it will help decrease air-conditioner use in warm climates during the summer months. Recently, the use of nanoparticles and different structures has been considered for passive radiative cooling applications. In this study, we investigate the radiative cooling properties of sand particles experimentally and compare their performance with other materials including silicon dioxide, titanium dioxide, and zinc oxide. Scanning electron microscopy (SEM) is used to analyze the morphology of the surface of sand the particles, and the other materials used in the study for comparison. Fourier transform infrared spectroscopy (FT-IR) experiments were conducted in order to measure the absorbance and transmittance percentage of the samples. In addition, the absorption coefficient was calculated from the FT-IR measurements. The absorption coefficient of the sand samples showed a high ratio (in the units of 1/m which was approximately between 0.4⨯10^4 and 0.8⨯10^4 for all the pellet samples at the atmospheric window range. Also, the behavior of the absorption profiles of the sand sample and ZnO were very similar in their ratios, especially in the atmospheric window range. Also, we observed that the emission shows the highest peaks at 6.78 µm, 9.24 µm, 11.69 µm, and 14.05 µm for all sand pellet samples. Thus, the properties of sand samples experimentally studied in this work show that they can be used for radiative cooling due to their abundance and thermal properties with better performance.Pasif radyatif soğutma, iklim krizlerinin olumsuz etkilerini azaltmaya ve binalardaki enerji tüketimini düşürmeye yardımcı olması muhtemel yeni teknolojilerden biridir. Radyatif soğutma prensibi, ısının bir binanın yüzeyinden uzaya yayılmasını ve böylece klima sistemlerine olan bağımlılığın azaltılmasını içerir. Pasif radyatif soğutmanın temellerini anlamak, binalar ve endüstriyel uygulamalarla ilgili termal yönetim için önemlidir. Binalarda radyatif soğutma prensibi, sistem üzerinde minimum ısı yükü elde etmek için çevreden gelen ısının seçici olarak yansıtılmasını ve bir yüzeyden çevreye seçici olarak enerji yayılmasını içerir. Binalar söz konusu olduğunda, çatılara gelen güneş radyasyonu yansıtılabilir veya absorbe edilebilir. Absorbe edilen ısı ya konveksiyon yoluyla çevredeki havaya aktarılır ya da gökyüzüne geri yayılır. Bir yüzeyin radyatif olarak soğutulması isteniyorsa, tezde ayrıntılı olarak tartışıldığı gibi, görünür dalga boyu aralığında güneş enerjisini büyük ölçüde yansıtması ve atmosferik pencere aralığında (8-13 µm dalga boyu aralığı) en yüksek radyasyon emisyonuna sahip olması gerekir. Bu teknik, yaz aylarında sıcak iklimlerde klima kullanımını azaltmaya yardımcı olacağından sera gazı emisyonlarının azaltılmasına önemli ölçüde yardımcı olabilir. Son zamanlarda, pasif radyatif soğutma uygulamaları için nanopartiküllerin ve farklı yapıların kullanımı düşünülmektedir. Bu çalışmada, kum partiküllerinin radyatif soğutma özelliklerini deneysel olarak araştırıyor ve performanslarını silikon dioksit, titanyum dioksit ve çinko oksit gibi diğer malzemelerle karşılaştırıyoruz. Taramalı elektron mikroskobu (SEM), kum parçacıklarının ve çalışmada karşılaştırma için kullanılan diğer malzemelerin yüzey morfolojisini analiz etmek için kullanılmıştır. Örneklerin absorbans ve geçirgenlik yüzdesini ölçmek için Fourier dönüşümlü kızılötesi spektroskopisi (FT-IR) deneyleri yapılmıştır. Ayrıca, FT-IR ölçümlerinden soğurma katsayısı hesaplanmıştır. Kum numunelerinin soğurma katsayısı, atmosferik pencere aralığında tüm pelet numuneleri için yaklaşık 0.4⨯10^4 yaklaşık 0.8⨯10^4 arasında olan yüksek bir oran (1/m birimlerinde) göstermiştir. Ayrıca, kum numunesi ve ZnO'nun soğurma profillerinin davranışı, özellikle atmosferik pencere aralığında, oranlarında çok benzerdi. Ayrıca, emisyonun tüm kum pelet örnekleri için 6.78 µm, 9.24 µm, 11.69 µm ve 14.05 µm 'de en yüksek pikleri gösterdiği gözlemlenmiştir. Dolayısıyla, bu çalışmada deneysel olarak incelenen kum numunelerinin özellikleri, bollukları ve daha iyi performansa sahip termal özellikleri nedeniyle radyatif soğutma için kullanılabileceklerini göstermektedir
Direct and indirect contributions of child temperament, parenting stress, and bedtime routines to children's sleep behaviors during the Covid-19 pandemic
No full textThe current study examined the direct and indirect contributions of children's temperament (reactivity, persistence, and rhythmicity), parenting stress, and bedtime routines to Turkish children's sleep behaviours during the COVID-19 pandemic. The sample was 313 mothers of children between 16 and 84 months (M = 52.42, SD = 12.36). Mothers reported their children's sleep behaviours, children's bedtime routines, parenting stress, and children's temperament. Multivariate path analyses were run to test the direct and indirect effects. Results indicated that parenting stress was negatively related to children's sleep behaviours. Further, it was found that consistency of bedtime routine environments was positively associated with children's sleep behaviours. For the indirect associations, children's temperament (rhythmicity and reactivity) was indirectly associated with children's sleep behaviours via the consistency of bedtime routines. Findings underline the importance of child temperament, parenting stress, and bedtime routines for children's sleep behaviours. The implications of the findings are discussed in light of previous research and the Bioecological model of human development in considering their functioning during the COVID-19 pandemic
Polarization and autocratization
No full textThe chapter examines the relationship between polarization and autocratization in contemporary democracies, introducing a typology of this relationship. It reviews the evolution of the literature from ideological to affective to pernicious polarization, and from spatial to process definitions, and the mechanisms by which each is purported to affect democracy and its erosion. Beyond the proliferation of conceptions of polarization, key debates include whether elites or mass polarization is the bigger threat to democracy, and the role of institutions. The chapter concludes that the lack of consensus on the definition and measurement of polarization continues to hamper generalized conclusions on the relationship between polarization and autocratization. Further research is needed on interventions that can mitigate anti-democratic attitudes and behavior at voter and elite levels, as well as whether polarization can also be a remedy to autocratization