5916 research outputs found
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FSO link attenuation measurement in extreme winter conditions for secure 5G applications
No full textThe functionality of Free Space Optical (FSO) communication links is highly influenced by meteorological conditions such as precipitation, snowfall, and fog. In this study, we establish an FSO link and conduct experimental measurements to evaluate the link performance under extreme winter conditions in the city of Astana, with the goal of facilitating secure 5G applications. During the measurement period, the lowest recorded temperature was -19.3 °C, with an average of -7 °C. We present the path loss for a link with a distance of 212 meters under various weather conditions (snow, clear sky, cloudy, overcast), visibility, humidity, and air pressure levels. We also record wind speed and snowfall rate. The obtained path loss data is subsequently compared with analytical approximations previously reported in the literature.Scientific and Technical Projects - Ministry of Education and Science of the Republic of Kazakhstan ; Nazarbayev Universit
Computational investigation of dual filler-incorporated polymer membranes for efficient CO2 and H2 separation: MOF/COF/Polymer mixed matrix membranes
No full textMixed matrix membranes (MMMs) composed of two different fillers such as metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs) embedded into polymers provide enhanced gas separation performance. Since it is not possible to experimentally consider all possible combinations of MOFs, COFs, and polymers, developing computational methods is urgent to identify the best performing MOF-COF pairs to be used as dual fillers in polymer membranes for target gas separations. With this motivation, we combined molecular simulations of gas adsorption and diffusion in MOFs and COFs with theoretical permeation models to calculate H2, N2, CH4, and CO2 permeabilities of almost a million types of MOF/COF/polymer MMMs. We focused on COF/polymer MMMs located below the upper bound due to their low gas selectivity for five industrially important gas separations, CO2/N2, CO2/CH4, H2/N2, H2/CH4, and H2/CO2. We further investigated whether these MMMs could exceed the upper bound when a second type of filler, a MOF, was introduced into the polymer. Many MOF/COF/polymer MMMs were found to exceed the upper bounds showing the promise of using two different fillers in polymers. Results showed that for polymers having a relatively high gas permeability (≥104 barrer) but low selectivity (≤2.5) such as PTMSP, addition of the MOF as the second filler can have a dramatic effect on the final gas permeability and selectivity of the MMM. Property-performance relations were analyzed to understand how the structural and chemical properties of the fillers affect the permeability of the resulting MMMs, and MOFs having Zn, Cu, and Cd metals were found to lead to the highest increase in gas permeability of MMMs. This work highlights the significant potential of using COF and MOF fillers in MMMs to achieve better gas separation performances than MMMs with one type of filler, especially for H2 purification and CO2 capture applications.European Union’s Horizon 2020Publisher versio
Türkiye'de yüksek sismik bölgelerde bulunan kendinden ankrajlı tankların sismik performansı
No full textThis study examines the seismic performance of three unanchored industrial liquid storage tanks that are located in the Kocaeli industrial area, which has a significant earthquake risk. One of the tanks is an existing tank in an industrial facility located in the region, while the other two were designed to have different anchorage ratios. The finite element analysis software ABAQUS was used to build 3-D finite element models in order to assess the seismic performance of the tanks. The seismic behaviour of the tanks was studied by performing time-history analyses using the recorded earthquake records that were scaled for the tank location. The spring-mass model, on which the developed tank models are based, models liquid content as two-point masses that were spring-adjusted to the tank wall. This approach was based on American Petroleum Institute (API 650). Tank-liquid interaction, base uplift, tank sliding off its foundation, damage to the tank's wall shell plates as well as bottom base plates, and the tank earthquake performance were all analysed. In addition, the effects of different friction coefficients between tank base and its foundation on tank seismic performance were studied. The seismic analyses were carried out using data related to eleven earthquakes. This data was scaled to meet the seismic design spectrum for the tank location and chosen in compliance with the Turkish Building Earthquake Code. Tank base sliding, base uplift and material damage were monitored to assess potential tank damages. The main objective of the study was to investigate the effects of tank anchorage ratio on seismic performance of unanchored tanks located in high seismic regions. This was achieved by performing time history analysis of the tanks using 11 earthquake records. Also, tank base uplift and sliding over the foundation failure modes were also evaluated on the basis of the effect of anchorage ratio on tanks. The second objective of the research was to examine the impact of friction between the tank base plate and tank foundation on tanks seismic performance. For this purpose, the tank's seismic performance was evaluated by considering two different friction coefficients. The findings of this study contribute new and valuable insights into the existing literature on the seismic performance of unanchored tanks and the effects of anchorage ratio on their seismic performance. In addition, the study provided a better understanding of the effects of unanchored tanks base friction on their seismic performance. Consequently, these findings will contribute to procedures used for seismic design of unanchored tanks and enhance the seismic performance of tanks at highly seismic regions.Bu çalışmada, deprem riskinin yüksek olduğu Kocaeli sanayi bölgesinde bulunan tehlikeli sıvı ihtiva eden üç adet ankrajsız sanayi tankının deprem yükleri altındaki performansı incelenmiştir. Tanklardan biri bölgedeki bir endüstri tesisinde mevcutken diğer ikisi farklı ankraj oranlarına sahip olarak tasarlanmıştır. Tankın deprem performansını belirlemede ABAQUS sonlu elemanlar programı kullanılarak 3D model oluşturulmuştur. Tankların deprem davranışını incelemek için zaman tanım alanında analiz metodu kullanılmıştır. Deprem kayıtları tankların konumuna göre ölçeklenmiştir. Geliştirilen tank modellerinin temel aldığı kütle-yay modeli, sıvı içeriğini iki nokta kütlesi olarak modeller ve bu kütlesel noktalar tank duvarına yaylarla bağlanır. Tank analiz modeli API 650 yönetmeliğine dayanmaktadır. Tank-sıvı etkileşimi, taban yükselmesi, tankın tabanından kayması, tank duvar kabuk plakalarının ve taban plakalarının hasarı ve tankın deprem performansı tümüyle analiz edildi. Ayrıca, tank tabanı ile temel arasındaki farklı sürtünme katsayılarının tank deprem performansı üzerindeki etkileri de incelendi. Deprem analizleri, on bir farklı deprem verisini kullanılarak gerçekleştirildi. Bu veriler, tankın bulunduğu bölge için deprem tasarım spektrumunu karşılamak üzere ölçeklendirildi ve Türkiye Bina Deprem Yönetmeliğine uygun olarak seçildi. Potansiyel tank hasarlarını değerlendirmek için tank taban kayması, taban yükselmesi ve malzeme hasarı takip edildi. Çalışmanın temel amacı, yüksek deprem riski taşıyan bölgelerde konumlanan ankrajsız tankların deprem performansına ankraj oranının etkilerini incelemekti. Tankların deprem yükleri altındaki yapısal davranışları zaman tanım alanında dinamik analizlerle belirlenmiştir. Ayrıca, tank taban yükselmesi ve temel kayması gibi başarısızlık modları da ankraj oranının tanklar üzerindeki etkisi temel alınarak değerlendirildi. Araştırmanın ikinci amacı, tank taban plakası ile temel arasındaki sürtünmenin tank deprem performansı üzerindeki etkisini incelemekti. Bu amaçla, tankın deprem performansı, iki farklı sürtünme katsayısı dikkate alınarak değerlendirildi. Bu çalışmanın bulguları, ankrajsız tankların deprem performansı ve ankraj oranının etkileri konusundaki mevcut literatüre yeni ve değerli katkılar sağlamaktadır. Ayrıca, bağlanmamış tankların temel taban sürtünmesinin deprem performansı üzerindeki etkisini daha iyi anlaşılmasını sağlamaktadır. Sonuç olarak, bu bulgular, ankrajsız tankların deprem tasarımında kullanılan prosedürlere katkıda bulunacak ve yüksek deprem riskli bölgelerde tankların deprem performansını artıracaktır
Değişen kaynak dosyalarını daha önce çözülen hatalar ile ilişkilendirerek test senaryosu seçimi
No full textSoftware continuously changes to address new requirements and to fix defects. Regression testing is performed to ensure that the applied changes do not adversely affect existing functionality. The increasing number of test cases makes it infeasible to execute the whole regression test suite. Test case selection is adopted to select a subset of the test suite, which is associated with the changed parts of the software. These parts are assumed to be error-prone. We present and evaluate a test case selection approach in the context of black-box regression testing of embedded systems. In this context, it is challenging to relate test cases with a set of distinct source code elements to be able to select those test cases associated with the modified parts of the source code. We analyze previously fixed defects for this purpose. We relate test cases that detect these defects with the source files that are previously modified for fixing them. Then, we select test cases related with source code files that are modified in the subsequent revision. The strength of this relation is determined as the number of changes associated with fixed defects previously detected by the same test cases. We conduct a case study on 3 real projects from the consumer electronics domain. Results show that it is possible to detect from 65% up to 85% of the defects detected by the whole test suite by selecting from 30% up to 70% of the test cases.Yazılım, yeni gereksinimleri karşılamak ve kusurları gidermek için sürekli olarak değişmektedir. Regresyon testleri, uygulanan değişikliklerin mevcut işlevselliği olumsuz etkilemediğinden emin olmak için yapılmaktadır. Artan test senaryoları, regresyon testlerinin tamamının yapılmasını elverişsiz hale getirmektedir. Test senaryosu seçimi ile, yazılımın değişen parçaları ile ilişkili olan test senaryolarının seçilmesi benimsenmektedir. Bu tezde, regresyon testlerinde kara kutu test yaklaşımı ile gömülü sistemler üzerinde test senaryo seçimi için bir yaklaşım sunulmaktadır. Bu kapsamda, yazılımdaki değişen kaynak kodları ile test senaryoları arasında bir ilişki olduğunu ve bu değişen kaynak kodları ile test senaryoları seçmenin mümkün olduğu iddia edilmektedir. Hataları tespit eden test senaryoları, bunları düzeltmek için önceden değiştirilmiş kaynak dosyaları ile ilişkilendirilmektedir. Ardından, bir sonraki yazılımda değiştirilen kaynak kod dosyaları ile ilgili test senaryoları seçilmektedir. Ayrıca, değişen dosya birden fazla hata ile ilgili olabileceği için, değişen kod ve test senaryosu arasındaki ilişki her bir test senaryosu için farklı olarak tanımlanmaktadır. Bu tezde tüketici elektroniği alanında faaliyet gösteren 3 gerçek proje üzerinde çalışılmaktadır. Sonuçlar, test senaryolarının %30'u ile %70'i arasında seçim yaparak tüm test senaryoları tarafından tespit edilen hataların %65'inden %85'ine kadar tespit edilmesinin mümkün olduğunu göstermektedir
Breaking the stalemate in the study of the relationship of mutual military buildups, arms races, and militarized disputes: The Greece-Turkey/Ottoman Empire cases
No full textThe most recent surveys on the study of the connection between mutual military buildups, arms races, and military interstate disputes (MID) warn of research projects, especially in the case of the Greece-Turkey dyad, that have reached a stalemate. This is due to the difficulty of capturing motivations, which constitute the main variable that turns mutual military buildups into arms races. Using the Greece-Ottoman Empire and Greece-Turkey dyads as proof-of-concept cases, we advance a novel approach for analyzing the interrelation between mutual military buildups, arms races, and MIDs that can overcome that stalemate. We suggest a two-stage approach that focuses on the dyad as a unit of analysis. In the first stage, which we preset here, we use rivalry to divide dyad history into periods of differing subsistence military spending. We then locate periods of mutual military buildups in the different rivalry periods of a dyad history. We argue that this process provides a more nuanced and detailed grasp on the presence of mutual military buildups in a dyad. It also provides the foundation for the future second stage of analysis, where qualitative research can focus on the specific periods of mutual military buildups to unearth indicators of motivation.Hellenic Foundation for Research and InnovationPublisher versio
Search for CP violating top quark couplings in pp collisions at √s = 13 TeV
No full textResults are presented from a search for CP violation in top quark pair production, using proton-proton collisions at a center-of-mass energy of 13 TeV. The data used for this analysis consist of final states with two charged leptons collected by the CMS experiment, and correspond to an integrated luminosity of 35.9 fb−1. The search uses two observables, O1 and O3, which are Lorentz scalars. The observable O1 is constructed from the four-momenta of the charged leptons and the reconstructed top quarks, while O3 consists of the four-momenta of the charged leptons and the b quarks originating from the top quarks. Asymmetries in these observables are sensitive to CP violation, and their measurement is used to determine the chromoelectric dipole moment of the top quark. The results are consistent with the expectation from the standard model.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 à 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 Hellenic Foundation for Research and Innovation (HFRI), Project Number 2288 (Greece); the Deutsche Forschungsgemeinschaft (DFG), under Germany’s Excellence Strategy — EXC 2121 “Quantum Universe” — 390833306, and under project number 400140256 — GRK2497; the Hungarian Academy of Sciences, the New National Excellence Program — ÚNKP, the NKFIH research grants K 124845, K 124850, K 128713, K 128786, K 129058, K 131991, K 133046, K 138136, K 143460, K 143477, 2020-2.2.1-ED-2021-00181, and TKP2021-NKTA-64 (Hungary); the Council of Science and Industrial Research, India; the Latvian Council of Science; the Ministry of Education and Science, project no. 2022/WK/14, and the National Science Center, contracts Opus 2021/41/B/ST2/01369 and 2021/43/B/ST2/01552 (Poland); the Fundação para a Ciência e a Tecnologia, grant CEECIND/01334/2018 (Portugal); the National Priorities Research Program by Qatar National Research Fund; MCIN/AEI/10.13039/501100011033, ERDF “a way of making Europe”, and the Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu, grant MDM-2017-0765 and Programa Severo Ochoa del Principado de Asturias (Spain); the Chulalongkorn Academic into Its 2nd Century Project Advancement Project, and the National Science, Research and Innovation Fund via the Program Management Unit for Human Resources & Institutional Development, Research and Innovation, grant B05F650021 (Thailand); the Kavli Foundation; the Nvidia Corporation; the SuperMicro Corporation; the Welch Foundation, contract C-1845; and the Weston Havens Foundation (USA); 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); NK-FIH (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); MES and NSC (Poland); FCT (Portugal); MESTD (Serbia); MCIN/AEI and PCTI (Spain); MOSTR (Sri Lanka); Swiss Funding Agencies (Switzerland); MST (Taipei); MHESI and NSTDA (Thailand); TUBITAK and TENMAK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA).Publisher versio
Re-thinking the surface design: How to prevent playground related extremity injuries in children
No full textPublic playgrounds are specially designed spaces for children to play and develop; however, falls are significant causes of children’s injury and are one of the most common mechanisms of injury in emergency departments. The study aims to survey the playground-related mechanism and incidence of extremity injuries in children and rethink the falling surface as designable equipment. The retrospective observational study enrolled 90 children who are injured in playgrounds and visited the emergency department in Istanbul between 2019 and 2020. Later, an observational study was conducted in public playgrounds within the neighborhood boundaries of the emergency department. The results show that the most common playground equipment related to the injury is slides and the most common surfacing material is rubber. The majority of total injuries were classified as upper extremity, and wrist fractures were the predominant injury type. The result of this study shows even with impact-absorbent surfacing such as rubber, fractures occur in children who fall from a certain height. To prevent these falls, rethinking the surface as designable equipment under high play equipment may help slow the fall.Publisher versio
Reducing charging costs for electric vehicles with bi-directional charging
No full textElectric vehicles (EVs) have gained popularity as eco-friendly and energy-efficient modes of transportation. How-ever, the high cost of charging infrastructure remains a significant barrier to the widespread adoption of EVs. Bidirectional charging (BDC) is a promising solution that allows EVs to charge from the grid and supply excess power back to the grid. In this paper, we present a simulation-based study of BDC using MATLAB/Simulink and Simscape to explore the potential of BDC to reduce charging costs. We modeled an EV charging station equipped with BDC capabilities and evaluated the cost savings achieved through BDC under two different scenarios. Our findings suggest that BDC has the potential to reduce charging costs significantly, making EVs more economically viable
Illumination-guided inverse rendering benchmark: Learning real objects with few cameras
No full textThe realm of 3D computer vision and graphics has experienced exponential growth recently, enabling the creation of realistic virtual environments and digital representations of real-world objects. Central to this progression are 3D reconstruction methods that facilitate the virtualization of shape, color, and surface details of real objects. Current methods predominantly employ neural scene representations, which despite their efficacy, grapple with limitations such as necessitating a high number of captured images and the complexity of transforming these representations into explicit geometric forms. An alternative strategy that has gained traction is the deployment of methods such as physically-based differentiable rendering (PBDR) and inverse rendering. These approaches require fewer viewpoints, yield explicit format results, and ensure a smoother transition to other representation methods. To meaningfully assess the performance of different 3D reconstruction methods, it is imperative to utilize benchmark scenes for comparison. Despite the existence of standard objects and scenes within the literature, there is a noticeable deficiency in real-world benchmark data that concurrently captures camera, illumination, and scene parameters — all critical to high-fidelity 3D reconstructions using PBDR and inverse rendering-based methods. In this research, we introduce a methodology for capturing real-world scenes as virtual scenes, integrating illumination parameters alongside camera and scene parameters to enhance the veracity of virtual representations. In addition, we introduce a set of ten real-world scenes, along with their virtual counterparts, designed as benchmarks. These benchmarks encompass a fundamental variety of geometric constructs, including convex, concave, plain, and mixed surfaces. Additionally, we demonstrate the 3D reconstruction results of state-of-the-art 3D reconstruction methods employing PBDR in real-world scenes, using both established methodologies and our proposed one
A survey of decision support mechanisms for negotiation
No full textThis paper introduces a dependency analysis and a categorization of conceptualized and existing economic decision support mechanisms for negotiation. The focus of our survey is on economic decision support mechanisms, although some behavioural support mechanisms were included, to recognize the important work in that area. We categorize support mechanisms from four different aspects: (i) economic versus behavioral decision support, (ii) analytical versus strategical support, (iii) active versus passive support and (iv) implicit versus explicit support. Our survey suggests that active mechanisms would be more effective than passive ones, and that implicit mechanisms can shield the user from mathematical complexities. Furthermore, we provide a list of existing economic support mechanisms.H2020 ICT48 ; Italian Ministry for Universities and Research ; Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung ; Fonds National de la Recherche Luxembourg ; CHIST-ERA ; Ministerie van Onderwijs, Cultuur en Wetenschap ; Nederlandse Organisatie voor Wetenschappelijk Onderzoek ; TÜBİTA