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On the low-cycle fatigue behavior of a multi-phase high entropy alloy with enhanced plasticity
No full textA multi-phase non-equiatomic FeCrNiMnCo high entropy alloy (HEA) was fabricated using vacuum induction melting. Thermo-mechanical treatments consisting of cold rolling and annealing at 750 °C and 850 °C were employed to improve the mechanical properties of the HEA in focus. Tensile experiments revealed that yield strength and ultimate tensile strength levels can be enhanced significantly after thermo-mechanical processing (TMP). At the same time, ductility remains at an adequate level. Strain-controlled low-cycle fatigue (LCF) experiments were carried out in order to assess the mechanical properties of this HEA under cyclic loading conditions. At the same strain amplitude, the stress levels of the processed samples were considerably higher than that of the as-received counterpart. Similarly, fatigue lives of the former could surpass the base condition at the strain amplitudes of 0.2% and 0.4%; however, at the higher strain amplitudes, cyclic softening was observed. Electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) results revealed that phase transformation from face-centered cubic (FCC) to body-centered cubic (BCC/B2) took place at a higher occurrence with increasing strain amplitude (0.2% to 0.6%). Furthermore, transmission electron microscopy (TEM) studies confirm that upon tensile deformation additional plasticity mechanisms, i.e., deformation twinning and phase transformation, contribute to the overall mechanical behavior of the multi-phase HEA.Deutsche Forschungsgemeinschaf
Makine öğrenmesi ile türk hisse senetleri piyasasında getiri tahmini
No full textIn this study I compare machine learning methods for predicting the stock returns of individual Turkish stocks listed in the Istanbul Stock Exchange (Borsa Istanbul). As the main machine learning model I use the Instrumented Principal Component Analysis (IPCA) and as a benchmark model I use Fama-French Factor Model. The IPCA model generates the stock-level expected returns based on observable stock-level and firm-level characteristics and latent common factors estimated within the model. Within the model stock-level characteristics determine the factor betas, namely the covariances of stock returns with the latent common factors. I estimate versions of the benchmark Fama-French models between 3 to 5 factors. The versions of the IPCA models use between 3 and 6 factors and use 10 characteristics. The sample covers all stocks in the XUTUM Index and the sample period includes forecasts between 2010 and 2022. Using a panel data of 252 firms listed in the Borsa Istanbul XUTUM Index and I analyze the comparative performance of the IPCA and Fama-French models. More specifically, I look at the in sample and out of sample performances of the models by comparing the realized and predicted series of returns for each individual stock. I find that the IPCA model significantly outperforms the Fama-French model by obtaining significantly higher out of sample R-squared levels and correlation of return forecasts and realized returns. The performance difference between Fama-French and IPCA models is more pronounced in the Turkish stock market compared to results of (Kelly, Pruitt and Su 2018) for the US stock market. Therefore, my results imply that the use of asset pricing models based on machine learning techniques may provide better results in emerging stock markets.Bu çalışmada, İstanbul Menkul Kıymetler Borsası'nda (Borsa İstanbul) işlem gören Türk hisse senetlerinin hisse senedi getirilerini tahmin etmek için makine öğrenimi yöntemleri karşılaştırılmıştır. Ana makine öğrenimi modeli olarak Enstrümanlı Temel Bileşen Analizini (IPCA) ve kıyaslama modeli olarak Fama-French Faktör Modelini kullanılmıştır. IPCA modeli, model içinde tahmin edilen gözlemlenebilir stok düzeyi ve firma düzeyi özellikleri ve gizli ortak faktörlere dayalı olarak stok düzeyinde beklenen getirileri üretir. Modelde stok düzeyi özellikleri faktör betalarını, yani hisse senedi getirilerinin gizli ortak faktörlerle kovaryanslarını belirler. Hisse senedi tahmini karşılaştırmalı analizi için 3 ila 5 faktör Fama-French modelleri kullanılmıştır. IPCA modelinde 3 ila 6 faktör kullanılmış ve 10 karakteristik kullanır. Örneklem, BIST TUM Endeksindeki tüm hisse senetlerini kapsıyor ve örnekleme dönemi, 2010 ile 2022 arasındaki tahminleri içeriyor. Borsa İstanbul BIST TUM Endeksi'nde yer alan 252 firmanın panel verilerini kullanarak IPCA ve Fama-French modellerinin karşılaştırmalı performansları analiz edilmiştir. Daha spesifik olarak, her bir hisse senedinin gerçekleşen ve tahmin edilen seri getirilerini karşılaştırarak modellerin örnek içi ve örnek dışı performanslarına bakılmıştır. IPCA modelinin, örnek R-kare düzeylerinden ve getiri tahminleri ile gerçekleşen getirilerin korelasyonundan önemli ölçüde daha yüksek elde ederek Fama-French modelinden önemli ölçüde daha iyi performans gösterdiğini bulunmuştur. Fama-French ve IPCA modelleri arasındaki performans farkı, ABD borsası için (Kelly, Pruitt and Su 2018) sonuçlarına kıyasla Türkiye borsasında daha belirgindir. Bu nedenle, sonuçlarım, makine öğrenimi tekniklerine dayalı varlık fiyatlandırma modellerinin kullanımının gelişmekte olan ülke borsalarında daha iyi sonuçlar sağlayabileceğini ima ediyor
Optimal sizing and techno-enviro-economic feasibility assessment of solar tracker-based hybrid energy systems for rural electrification in Sudan
No full textHybrid power systems (HPS) based on photovoltaic (PV), diesel generators (DG), and energy storage systems (ESS) are widely used solutions for the energy supply of off-grid or isolated areas. The main hybridizing challenges are reliability, investment and operating costs, and carbon emissions problems. Since HPS are usually sized to provide energy continuously, it is essential to use the solar energy potential close to full capacity, especially on cloudy days. One of the prominent solutions to overcome these challenges is integrating solar tracking systems (STS). This article focuses on the optimal sizing of HPS based on PV-DG-ESS utilizing STS by analyzing technical, economic, and environmental aspects. Optimization is performed with the MILP solved via Gurobi, considering the net present cost (NPC) and loss of power supply probability (LPSP) objectives. The results indicate that horizontal and dual solar trackers can provide up to 50% better energy harvest performance and reduce NPC by up to 7%. It is also found that there is no significant difference in cost reduction between both systems. Moreover, STS is feasible if the cost is less than 375 USD and 250 USD for Sudan and South Sudan, respectively
(Non-)deport to discipline: The daily life of Afghans in Turkey
No full textThis study contributes to discussions on the politics of (non-)deportability by focusing on the case of Afghans, the largest migrant community without a right to protection in Turkey, itself the country hosting the most refugees. This article examines how the politics of (non-)deportation is shaped and practiced for Afghans and the types of everyday strategies they employ to deal with deportability. We first argue that the politics of deportation in Turkey is predominantly shaped by the needs of the informal labour market, which accounts for one-third of the total labour force. Our findings suggest that forced labour and the hypermobility of Afghans is both tolerated and hidden by the state, while Afghans' fear of deportability operates as a disciplining apparatus. Second, we argue that, when spectacles of deportation are performed, three crucial factors help Afghans avoid deportation, namely their qawm-based (ethnic or kinship) background, the involvement of Afghan associations, and street-level negotiations with the authorities.Embassy of Switzerland in Turkey ; Swiss ConfederationPublisher versio
To stay or not to stay: How to convince the very first guest of a resort property
No full textHotel openings in resort destinations have several challenges to overcome and manage, such as: (i) the completion of the hotel project; (ii) preparation of hotel operations for the customer experience; (iii) pre-opening tasks and procedures to test the technical and functional performance of all the service units; and (iv) organization of site visits to marketing and sales partners. The conflicts between the hotel operation and project teams and the delays in openings due to planning defects or unexpected problems may prolong this period with multiple issues for managing executives to deal with. This case addresses the possible challenges of such a period and helps learners comprehend and analyse the situational aspects to seek the best possible solutions to overcome these challenges
Convergence of a linearly regularized nonlinear wave equation to the p-system
No full textWe consider a second-order nonlinear wave equation with a linear convolution term. When the convolution operator is taken as the identity operator, our equation reduces to the classical elasticity equation which can be written as a p-system of first-order differential equations. We first establish the local well-posedness of the Cauchy problem. We then investigate the behavior of solutions to the Cauchy problem in the limit as the kernel function of the convolution integral approaches to the Dirac delta function, that is, in the vanishing dispersion limit. We consider two different types of the vanishing dispersion limit behaviors for the convolution operator depending on the form of the kernel function. In both cases, we show that the solutions converge strongly to the corresponding solutions of the classical elasticity equation.Publisher versio
Search for a high-mass dimuon resonance produced in association with b quark jets at √s=13 TeV
No full textA search for high-mass dimuon resonance production in association with one or more b quark jets is presented. The study uses proton-proton collision data collected with the CMS detector at the LHC corresponding to an integrated luminosity of 138 fb−1 at a center-of-mass energy of 13 TeV. Model-independent limits are derived on the number of signal events with exactly one or more than one b quark jet. Results are also interpreted in a lepton-flavor-universal model with Z′ boson couplings to a bb quark pair (gb), an sb quark pair (gbδbs), and any same-flavor charged lepton (gℓ) or neutrino pair (gν), with |gν| = |gℓ|. For a Z′ boson with a mass
= 350 GeV (2 TeV) and |δbs| < 0.25, the majority of the parameter space with 0.0057 < |gℓ| < 0.35 (0.25 < |gℓ| < 0.43) and 0.0079 < |gb| < 0.46 (0.34 < |gb| < 0.57) is excluded at 95% confidence level. Finally, constraints are set on a Z′ model with parameters consistent with low-energy b → sℓℓ measurements. In this scenario, most of the allowed parameter space is excluded for a Z′ boson with 350 <
< 500 GeV, while the constraints are less stringent for higher
hypotheses. This is the first dedicated search at the LHC for a high-mass dimuon resonance produced in association with multiple b quark jets, and the constraints obtained on models with this signature are the most stringent to date.SC (Armenia), 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); NKFIH (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 (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 Science Committee, project no. 22rl-037 (Armenia); 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 (IWTBelgium); 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 -UNKP, 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 Fundacao para a Ciencia 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 Investigacion Cientifica y Tecnica de Excelencia Maria 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; theWelch Foundation, contract C-1845; and theWeston Havens Foundation (U.S.A.).Publisher versio
Konut yapıları için sel kayıp ve güçlendirme analizleri
No full textFlooding events are the most frequent natural disasters that cause significant physical damage on the built-infrastructure, leading to severe economic losses and social disruptions on communities. To measure and increase disaster resilience of communities, reliable assessment of direct physical losses (i.e., repair cost and time associated with flood damage) of building structures under the hazard actions is the first main and essential ingredient. To mitigate disasters effectively, sophisticated approaches are also needed to support citizens to give risk-based decisions on disaster retrofit actions. This study presents an assembly-based framework that first develops models to estimate physical flood losses for typical single-family and multi-family residential buildings in Europe, with a focus on houses in UK. Considering several residential building types with or without basement, flood damage potential of each nonstructural and content components of the buildings were examined for various flood depths. Relative losses associated with flood-repair cost and time for each damaged component were obtained considering the individual failure limit of the component. Next, all components were assembled to estimate the total losses on houses in terms of both repair cost and time. Furthermore, this study performed benefit analyses on flood-retrofit approaches to find the optimal solutions minimizing the associated losses. Results show that water-contact can give severe damage and losses on non structural building items and building content items. Also, retrofit actions are found to give more effective reductions in losses and repair times if the key ones are applied together, comparing to their effectiveness as an individual action.Sel olayları, inşa yapılarında önemli fiziksel hasara neden olan ve topluluklar üzerinde ciddi ekonomik kayıplara ve sosyal bozulmalara yol açan en sık görülen doğal afetlerdir. Toplulukların afet direncini ölçmek ve artırmak için, afet eylemleri altında bina yapılarının doğrudan fiziksel kayıplarının (yani, sel hasarı ile ilişkili onarım maliyeti ve süresi) güvenilir bir şekilde değerlendirilmesi ilk ana ve gerekli bileşendir. Ayrıca, afetleri etkili bir şekilde azaltmak için, vatandaşların afet güçlendirme eylemleri hakkında riske dayalı kararlar vermelerini destekleyen sofistike yaklaşımlara ihtiyaç vardır. Bu çalışma, ilk olarak, İngiltere'deki evlere odaklanarak, Avrupa'daki tipik tek aileli ve çok aileli konut binaları için fiziksel sel kayıplarını tahmin eden modeller geliştiren birleştirme tabanlı bir çerçeve sunmaktadır. Bodrumlu veya bodrumsuz birçok konut bina tipleri göz önüne alınarak, binaların her bir yapısal olmayan ve içerik bileşeninin sel hasar potansiyeli çeşitli sel derinliklerinde incelenmiştir. Her hasarlı bileşen için sel onarım maliyeti ve süresi ile ilişkili göreceli kayıplar, bileşenin bireysel hasar limiti dikkate alınarak elde edilmiştir. Daha sonra, tüm bileşenler hem onarım maliyeti hem de onarım zamanı açısından konutlardaki toplam kayıpları tahmin etmek için birleştirilmiştir. Ayrıca, bu çalışma, ilgili kayıpları en aza indirgeyen en uygun çözümleri bulmak için sele karşı güçlendirme yaklaşımları üzerinde fayda analizleri yapmıştır. Sonuçlar, sel suyu temasının yapısal olmayan konut binası elemanları ve konut içerisindeki eşyalar üzerinde ciddi hasar ve kayıplar verebileceğini göstermektedir. Ayrıca, güçlendirme eylemlerinin, önemli olanları birlikte uygulanırsa, bireysel bir eylem olarak etkinliklerine kıyasla, kayıplarda ve onarım sürelerinde daha etkili azalmalar sağladığı bulunmuştur
Search for resonant and nonresonant production of pairs of dijet resonances in proton-proton collisions at √s = 13 TeV
No full textA search for pairs of dijet resonances with the same mass is conducted in final states with at least four jets. Results are presented separately for the case where the four jet production proceeds via an intermediate resonant state and for nonresonant production. The search uses a data sample corresponding to an integrated luminosity of 138 fb(-1) collected by the CMS detector in proton-proton collisions at root s = 13 TeV. Model-independent limits, at 95% confidence level, are reported on the production cross section of four-jet and dijet resonances. These first LHC limits on resonant pair production of dijet resonances via high mass intermediate states are applied to a signal model of diquarks that decay into pairs of vector-like quarks, excluding diquark masses below 7.6 TeV for a particular model scenario. There are two events in the tails of the distributions, each with a four-jet mass of 8 TeV and an average dijet mass of 2 TeV, resulting in local and global significances of 3.9 and 1.6 standard deviations, respectively, if interpreted as a signal. The nonresonant search excludes pair production of top squarks with masses between 0.50 TeV to 0.77 TeV, with the exception of a small interval between 0.52 and 0.58 TeV, for supersymmetric R-parity-violating decays to quark pairs, significantly extending previous limits. Here, the most significant excess above the predicted background occurs at an average dijet mass of 0.95 TeV, for which the local and global significances are 3.6 and 2.5 standard deviations, respectively.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).
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 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 - uNKP, 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 FundacAo para a Ciencia 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 Investigacion Cientifica y Tecnica de Excelencia Maria 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).Publisher versio