5916 research outputs found
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Study of dijet events with large rapidity separation in proton-proton collisions at s√ = 2.76 TeV
No full textThe cross sections for inclusive and Mueller-Navelet dijet production are measured as a function of the rapidity separation between the jets in proton-proton collisions at s = 2.76 TeV for jets with transverse momentum pT> 35 GeV and rapidity |y| 20 GeV is introduced to improve the sensitivity to the effects of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) evolution. The measurement is compared with the predictions of various Monte Carlo models based on leading-order and next-to-leading-order calculations including the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi leading-logarithm (LL) parton shower as well as the LL BFKL resummation.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. 14.W03.31.0026 and no. FSWW-2020-0008, and the Russian Foundation for Basic Research, project No.19-42-703014 (Russia); the Programa Estatal de Fomento de la Investigacion Cientifica y Tecnica de Excelencia Maria de Maeztu, grant MDM-2015-0509 and the Programa Severo Ochoa del Principado de Asturias; 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
Dynamic opto-electro-thermal characterization of solid state lighting devices: measuring the power conversion efficiency at high current densities
No full textSolid state lighting devices with high power densities require accurate characterization, as the rise of chip temperature impacts its optical, electrical, and lifetime characteristics. A detailed experimental study is performed in order to analyze opto-electro-thermal behavior as new high-power devices like laser diodes (LDs) are becoming of interest. The outline of this article was inspired by two major issues identified in previous experimental approaches. First, there is some debate in the literature about the linearity of the temperature coefficient of the forward voltage. Second, there is a limited number of experimental reports on the temperature dependence of power conversion efficiency. We have shown that prior variations are the result of a diversity in the selection of electrical parameters during thermal calibrations, as both linear and non-linear relationships for temperature coefficient of voltage can be obtained. On the other hand, it was discovered that report scarcity for temperature-dependent studies can be related to the use of passive approaches for temperature-dependent measurements. In temperature-controlled environments, short pulses with high current densities may not ensure the thermal equilibrium of the device under test due to small thermal capacitance. This issue, as well as the lengthy process of passive measurements can be addressed by implementing a dynamic measurement method presented in this study. Finally, linear power conversion efficiency trends with junction temperature are demonstrated for both blue light emitting diodes and LDs at high current densities.EVATEG Center ; Ozyegin University ; TÜBİTA
Hospital service levels during drug shortages: Stocking and transshipment policies for pharmaceutical inventory
No full textIn this study, we consider a health network that faces uncertain supply disruptions in the form of regional, nationwide, or worldwide drug shortages. Each hospital observes stochastic demand and if the drug is unavailable, patients leave and receive care in another network. As these instances of unavailability diminish the brand value, health networks look for inventory sharing mechanisms among hospitals to mitigate the effect of uncertain supply disruptions. In line with this expectation, we propose a proactive inventory sharing approach for critical drugs to investigate the effect of the inventory-related parameters on service levels.TÜBİTA
Rejection sensitivity and mental well-being: The positive role of friendship quality
No full textPrevious research shows a link between rejection sensitivity (RS) and various psychological disorders; however, its relation to the positive psychological construct of mental well-being remains unstudied. This study investigates the relationship between RS and mental well-being while taking the role of friendship quality into consideration for 323 emerging adults using decision tree analysis. In training (R2 =.29) and test trees (R2 =.18), RS had the strongest relationship with mental well-being where those higher in RS had lower mental well-being scores. For those lower in RS, higher combined (same-sex and opposite-sex) friendship quality was associated with higher mental well-being. Whereas for those higher in RS, higher same-sex friendship quality was associated with higher mental well-being. As our findings indicate, friendship quality may play a buffering role for emerging adults, keeping their mental well-being at more preferable levels especially for those with higher RS. Implications for future studies and interventions to boost friendship quality are discussed
On the full dispersion Kadomtsev–Petviashvili equations for dispersive elastic waves
No full textFull dispersive models of water waves, such as the Whitham equation and the full dispersion Kadomtsev–Petviashvili (KP) equation, are interesting from both the physical and mathematical points of view. This paper studies analogous full dispersive KP models of nonlinear elastic waves propagating in a nonlocal elastic medium. In particular we consider anti-plane shear elastic waves which are assumed to be small-amplitude long waves. We propose two different full dispersive extensions of the KP equation in the case of cubic nonlinearity and ”negative dispersion”. One of them is called the Whitham-type full dispersion KP equation and the other one is called the BBM-type full dispersion KP equation. Most of the existing KP-type equations in the literature are particular cases of our full dispersion KP equations. We also introduce the simplified models of the new proposed full dispersion KP equations by approximating the operators in the equations. We show that the line solitary wave solution of a simplified form of the Whitham-type full dispersion KP equation is linearly unstable to long-wavelength transverse disturbances if the propagation speed of the line solitary wave is greater than a certain value. A similar analysis for a simplified form of the BBM-type full dispersion KP equation does not provide a linear instability assessment
Aerosol attenuation model for high altitude UAV-based FSO links
No full textFree space optical (FSO) communication is well positioned to address connectivity needs in ground-UAV, inter-UAV and UAV-ground links. An accurate performance analysis of airborne FSO links requires the use of proper path loss models. While earlier studies have successfully modeled attenuation arising from rain, drizzle, fog, and snow, aerosols have received less attention. Aerosols are tiny particles suspended in the atmosphere. They can be found drifting in Earth's atmosphere from the stratosphere to the troposphere to the Earth's surface. In this paper, we conduct extensive simulations in MODTRAN to determine the extinction coefficient values for aerosol over the wavelength from 350 nm to 1550 nm including typical wavelengths (e.g., 690 nm, 780nm, 850nm, and 1550 nm) used in commercial FSO systems. Non-linear curve fitting is then used to obtain new closed-form expressions for extinction coefficients.TÜBİTA
Rateworkspace: BIM integrated post-occupancy evaluation system for office buildings
No full textThe feedback obtained from occupants regarding their comfort needs and performance of buildings is critical for assessing occupant satisfaction, identifying the operation and maintenance (O&M) issues in time and for improving resource efficiency in buildings. Current facility management (FM) systems and occupant feedback collection practices, however, have limitations in supporting effective decision-making in FM, as they lack the necessary contextual data related to the occupant feedback (e.g., building geometry, systems, elements). Building Information Modeling (BIM)-enabled FM systems are used for combining different types of FM information with building models; however, occupant feedback is still not effectively utilized in FM since it is not integrated with BIM. In this study, a BIM integrated post-occupancy evaluation system prototype is developed for: (1) collecting occupant feedback along with the contextual information related to the feedback items in a structured way, and (2) presenting this information as integrated with BIM to the facility managers. This enables conducting spatio-temporal queries and supports effective decision-making by visualizing the collected feedback. The prototype was designed by using qualitative shadowing with FM teams to identify information needs and use case analysis to determine how contextual data integrated with BIM could be collected from office occupants who are non-technical persons with limited information on building models. This paper identifies the FM query categories that are required to process the occupant feedback and describes the RateWorkSpace prototype developed for office buildings. The deployment of the prototype in a real-world office demonstrates that the proposed system is applicable, practical, usable, and that real-time building performance data can be both collected and analysed with the developed system. This has the potential to increase the effectiveness of the FM and O&M processes, and help to create office spaces with optimized energy use and occupant comfort that also supports occupant well-being and productivity.TÜBİTAKPublisher versio
Association between children’s temperament and learning behaviors: contribution of relationships with parents and teachers
No full textThe present study is an investigation of the contributions of child temperament (persistence and reactivity), parent-child (closeness and conflict), and teacher-child relationship (closeness and conflict), to pre-school children's learning behaviours with a focus on the moderating role of these relationships between child temperament and learning behaviours. Participants were 140 children (59 girls) aged 39 to 77 months (M = 62.57, SD = 8.53). Child temperament and parent-child relationships were reported by parents. Teacher-child relationships and learning behaviours were reported by teachers. Results from regression analyses accounting for the nesting structure of the data showed that reactivity, parent-child conflict, and teacher-child conflict were negatively, and persistence and teacher-child closeness were positively related to children’s learning behaviours. In addition, when the parent-child conflict was at average or high levels, children with higher reactivity displayed lower levels of learning behaviours. The findings highlight that both temperament and relationships with parents and teachers are important for children’s learning behaviours
An explainable credit scoring framework: A use case of addressing challenges in applied machine learning
No full textWhile Machine Learning (ML) classification algorithms can accurately classify a borrower's credit risk, the determinants of the credit score cannot be interpreted clearly by customers, decision makers and auditors. The lack of transparency of black-box credit scoring mechanisms reduces the trust in the banking system and has serious implications for the financing and growth of businesses. Recent regulations in the European Union and the United States require that credit decision mechanism should by explainable and transparent. We present a framework for developing an explainable credit scoring model. Our scientific novelty is to follow a simple and parsimonious Surrogate approach for credit scoring. This approach estimates an explainable white-box model that effectively fits to the in-sample forecasts of the most accurate 'black-box' model. We implement the Surrogate credit risk framework using check transactions data provided by a Turkish bank. We find that the Surrogate tree's performance is sufficiently close to performance of the most accurate black-box XGBoost model. Overall, our findings show that it is possible to develop a high-performing explainable credit scoring model with a minimal decrease in model accuracy
Effort estimation for architectural refactoring of data tier software
No full textArchitectural refactoring requires substantial effort. We introduce an approach and a tool to predict this effort prior to refactoring. We focus on PL/SQL programs that are developed as data access tiers of business software. There are two types of common refactoring needs for these programs. First, some of the modules might need to be migrated to a separate database. Second, some of the modules in the data tier might need to be migrated to the application tier. In both cases, the refactoring effort is proportional to the amount of coupling between the migrated modules and the rest of the modules in the database. Our tool can parse PL/SQL programs to reveal this coupling based on an analysis of SQL queries. Unlike prior studies, our tool can analyze queries that are created dynamically and that use multiple tables as well as PL/SQL-specific features. We evaluate our approach with an industrial PL/SQL program from the telecommunications domain. Our results are approved to be accurate by domain experts.TÜBİTA