5916 research outputs found
Sort by
Thermal and optical performance characterization of bare and phosphor converted LEDs through package level immersion cooling
No full textIncreased demand for high flux electronics requires creative and affordable thermal management approaches to meet the performance and lifetime expectations. In the present study, optical and thermal improvements of a new package level liquid coolant encapsulation that directly targets heat generation zones are studied for bare and phosphor converted LEDs. As heat both at chip and phosphor composite regions are being generated, a series of detailed experimental and theoretical characterization is performed in order to examine the capability of the new cooling method. The findings can be used to extend the application of precisely controlled liquid packing on the heat source region of optoelectronic components. This method has shown a 15% reduction in thermal resistance and a 7% increase in power conversion efficiency of LED packages. The capacity of this method is mainly limited to the thermal conductivity of the coolant while a significant ability for improvement can be expected by utilizing thermally conductive particles such as hexagonal boron nitride inside the coolant.EVATEG Center ; Ozyegin University ; TÜBİTA
The political economy of the board of directors: The case of Turkish Airlines (1956–2020)
No full textTurkish Airlines, the first civil airline organization in Turkey, has positioned itself as a flag carrier. The aim of this chapter is to examine the board of directors of THY, which has changed over time. For this purpose, a single case study approach was designed to allow in-depth analysis of the composition of the board. The findings of this study indicate that Turkish Airlines has changed its board members to comply with the changes in the environment. This study contributes to resource dependence theory literature by revealing the factors influencing the board of directors of Turkish Airlines
Hisse senetlerinde işlem otomasyonu için derin güçlendirme öğrenme yaklaşımı
No full textDeep Reinforcement Learning (DRL) algorithms can scale to previously intractable problems. The automation of profit generation in the stock market is possible using DRL, by combining the financial assets price "prediction" step and the "allocation" step of the portfolio in one unified process to produce fully autonomous system capable of interacting with its environment to make optimal decisions through trial and error. In this study, a continuous action space approach is adopted to give the trading agent the ability to gradually adjust the portfolio's positions with each time step (dynamically re-allocate investments), resulting in better agent-environment interaction and faster convergence of the learning process. In addition, the approach supports the managing of a portfolio with several assets instead of a single one. This work represents a novel DRL model to generate profitable trades in the stock market, effectively overcoming the limitations of supervised learning approaches. We formulate the trading problem as a Partially Observed Markov Decision Process (POMDP) model, considering the constraints imposed by the stock market, such as liquidity and transaction costs. More specifically, we design an environment that simulates the real-world trading process by augmenting the state representation with ten different technical indicators and sentiment analysis of news articles for each stock. We then solve the formulated POMDP problem using the Twin Delayed Deep Deterministic Policy Gradient (TD3) algorithm and achieved a 2.68 Sharpe ratio on the test dataset. From the point of view of stock market forecasting and the intelligent decision-making mechanism, this study demonstrates the superiority of deep reinforcement learning in financial markets over other types of machine learning such as supervised learning and proves the credibility and advantages of strategic decision-making using DRL.Deep Reinforcement Learning (DRL) algoritmaları, daha önceki zorlu sorunlara ölçeklenebilir.Hisse senedi piyasasında kâr üretiminin otomasyonu, finansal varlıkların fiyat "tahmin" adımı ve portföyün "tahsis" adımını tek bir birleşik süreçte birleştirerek, deneme yanılma yoluyla optimal kararlar almak için çevresiyle etkileşime girebilen tamamen özerk bir sistem üretmek için DRL kullanılarak mümkündür. Bu çalışmada, alım-satım aracısına portföyün pozisyonlarını her zaman adımı için kademeli olarak ayarlama (yatırımları dinamik olarak yeniden tahsis etme) özelliği vermek için sürekli bir eylem alanı yaklaşımı benimsenmiştir, bu da daha iyi aracı-ortam etkileşimi ve öğrenme sürecinin daha hızlı yakınsaması ile sonuçlanmıştır. Ayrıca yaklaşım, tek bir varlık yerine birkaç varlık içeren bir portföyün yönetilmesini destekler. Bu çalışma, denetimli öğrenme yaklaşımlarının sınırlamalarını etkin bir şekilde aşarak borsada karlı işlemler oluşturmak için yeni bir DRL modelini temsil etmektedir. Ticaret problemini, likidite ve işlem maliyetleri gibi hisse senedi piyasasının getirdiği kısıtlamaları dikkate alarak Partially Observed Markov Decision Process (POMDP) modeli olarak formüle ediyoruz. Daha spesifik olarak, her hisse senedi için on farklı teknik gösterge ve haber makalelerinin duygu analizi ile durum temsilini artırarak gerçek dünyadaki ticaret sürecini simüle eden bir ortam tasarlıyoruz. Daha sonra formüle edilmiş POMDP problemini Twin Delayed Deep Deterministic Policy Gradient (TD3) algoritmasını kullanarak çözdük ve test veri setinde 2.68 Sharpe oranı elde ettik. Hisse senedi piyasası tahmini ve akıllı karar verme mekanizması açısından bu makale, finansal piyasalarda derin pekiştirmeli öğrenmenin denetimli öğrenme gibi diğer makine öğrenimi türlerine göre üstünlüğünü göstermekte, aynı zamanda DRL yaklaşımının güvenilirliğini ve stratejik karar vermenin avantajlarını kanıtlamaktadır
A mathematical model for equitable in-country COVID-19 vaccine allocation
No full textGiven the scarcity of COVID-19 vaccines, equitable (fair) allocation of limited vaccines across the main administrative units of a country (e.g. municipalities) has been an important concern for public health authorities worldwide. In this study, we address the equitable allocation of the COVID-19 vaccines inside countries by developing a novel, evidence-based mathematical model that accounts for multiple priority groups (e.g. elderly, healthcare workers), multiple vaccine types, and regional characteristics (e.g. storage capacities, infection risk levels). Our research contributes to the literature by developing and validating a model that proposes equitable vaccine allocation alternatives in a very short time by (a) minimising deviations from the so-called ‘fair coverage’ levels that are computed based on weighted pro-rata rations, and (b) imposing minimum coverage thresholds to control the allocation of vaccines to higher priority groups and regions. To describe the merits of our model, we provide several equity and effectiveness metrics, and present insights on different allocation policies. We compare our methodology with similar models in the literature and show its better performance in achieving equity. To illustrate the performance of our model in practice, we perform a comprehensive numerical study based on actual data corresponding to the early vaccination period in Turkey.Norges ForskningsrådPublisher versio
Analysis of the CP structure of the Yukawa coupling between the Higgs boson and τ leptons in proton-proton collisions at s√ = 13 TeV
No full textThe first measurement of the CP structure of the Yukawa coupling between the Higgs boson and τ leptons is presented. The measurement is based on data collected in proton-proton collisions at s = 13 TeV by the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb−1. The analysis uses the angular correlation between the decay planes of τ leptons produced in Higgs boson decays. The effective mixing angle between CP-even and CP-odd τ Yukawa couplings is found to be −1 ± 19°, compared to an expected value of 0 ± 21° at the 68.3% confidence level. The data disfavour the pure CP-odd scenario at 3.0 standard deviations. The results are compatible with predictions for the standard model Higgs boson.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); NKFIA (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); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS, RFBR, and NRC KI (Russia); MESTD (Serbia); SEIDI, CPAN, PCTI, and FEDER (Spain); MOSTR (Sri Lanka); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR, and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (U.S.A.).
Individuals have received support from the Marie-Curie programme 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 Deutsche Forschungsgemeinschaft (DFG), under Germany's Excellence Strategy -EXC 2121 "Quantum Universe" -390833306, and under project number 400140256 - GRK2497; the Lendulet ("Momentum") Programme 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
Observation of B0 → ψ (2S)K0Sπ+π− and B0s → ψ (2S)K0S decays
No full textUsing a data sample of root s = 13 TeV protonproton collisions collected by the CMS experiment at the LHC in 2017 and 2018 with an integrated luminosity of 103 fb(-1), the B-s(0) -> psi(2S)K-S(0) and B-0 -> psi(2S)K-S(0) pi(+) pi(-) decays are observed with significances exceeding 5 standard deviations. The resulting branching fraction ratios, measured for the first time, correspond to B(B-s(0) -> psi(2S)K-S(0))/B(B-0 Zeta -> psi(2S)K-S(0)) = (3.33 +/- 0.69(stat) +/- 0.11 (syst) +/- 0.34 (f(s)/f(d))) x 10(-2) and B(B-0 -> psi(2S)K-S(0) pi(+) pi(-))/B(B-0 -> psi(2S)K-S(0)) = 0.480 +/- 0.013 (stat) +/- 0.032 (syst), where the last uncertainty in the first ratio is related to the uncertainty in the ratio of production cross sections of B-s(0) and B-0 mesons, f(s)/f(d).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); NKFIA (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); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS, RFBR, and NRC KI (Russia); MESTD (Serbia); MCIN/AEI and PCTI (Spain); MOSTR (Sri Lanka); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR, and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA). Rachada-pisek Individuals have received support from the Marie-Curie programme 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 doorWetenschap 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 -EXC2121 "Quantum Universe" -390833306, and under project number 400140256-GRK2497; the Lendulet ("Momentum") Programme 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 L(Portugal); the National Priorities Research Program by Qatar National Research Fund; the Ministry of Science and Higher Education, projects no. 0723-2020-0041 and no. FSWW-2020-0008, and the Russian Foundation for Basic Research, project No.19-42-703014 (Russia); MCIN/AEI/10.
13039/501100011033, ERDF "a way of making Europe", and the Programa Estatal de Fomento de la Investigacion Cientifica y Tecnica de ExcelenciaMaria de Maeztu, grantMDM-20170765 and Programa Severo Ochoa del Principado de Asturias (Spain); 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 (USA).Publisher versio
İleri düzey fiziksel katman özellikleri ve var olan kablosuz haberleşme teknolojilerine entegrasyonu ile görünür ışıkla haberleşme
No full textOptical wireless communication systems that operate in the visible light frequency band (390-700 nm) are called as visible light communication (VLC). VLC systems are based on the principle of modulating light emitting diodes (LEDs) at very high speeds without any adverse effects on the human eye and illumination levels. LEDs, utilized as VLC access points (APs), are increasingly used both indoors (e.g., home and office lighting, etc.) and outdoors (e.g., street lights, traffic lights, vehicle front/rear lights, etc.). The dual use of LEDs for both lighting and communications purposes is a revolutionary solution and has the potential to open a new era in wireless communications. In this context, VLC has attracted industrial attention and related international standardization works have already begun. In this dissertation, high-speed VLC systems with high link reliability are developed. Under the consideration of dual functionality to support both illumination and communication, advanced physical layer (PHY) techniques including adaptive transmission, orthogonal frequency division multiplexing (OFDM), multiple-input multiple-output (MIMO), and massive MIMO with beamforming are explored in order to meet the targeted high data speeds and link reliability. To utilize the multiple LEDs available within an indoor room environment for MIMO transmissions, a coordinated and joint signal processing mechanism has to be deployed. For this purpose, a centralized platform where baseband units (BBUs) are separated from the VLC APs and shifted to a centralized unit (CU) in which all signal processing units work is first proposed. Then, two different advanced PHY techniques are designed and run over the proposed platform. Firstly, adaptive bit and power loading for OFDM based VLC system with MIMO mode switching between repetition coding and spatial multiplexing is designed. The adaptive algorithm design as an optimization problem where the aim is to maximize data rate through the proper selection of modulation order, power level, and MIMO mode, while satisfying a targeted bit error rate, is formulated and resolved. As a second advanced PHY technique, massive MIMO transmission is explored. In order to obtain the full benefits of massive MIMO, channel state information must be available in transmitter side. Estimation of downlink (DL) channel through DL pilot signals leads huge pilot overhead in both DL and uplink (UL) and makes the implementation of massive MIMO system infeasible if not properly designed. Therefore, the analysis is done under the consideration of limited number of DL pilot signals. Different pilot arrangements (PAs) in spatial, frequency, and time domains where interpolation is performed to obtain global channel matrix taking advantage of the indoor environment geometry and layout of luminaries are proposed. An adaptive selection of PAs to balance DL and UL data rates regarding to varying network conditions is further designed. Centralized platform benefits to integrate VLC with existing wireless communication technologies (such as millimeter wave (MMW) transmission) in a heterogeneous network architecture as well. In the centralized platform, similar to VLC network, BBU is separated from MMW AP and located inside the same CU. Through the benefiting from global view of overall network architecture, an adaptive vertical (between MMW and VLC APs) and horizontal (between VLC APs) handover protocol is further designed to increase the overall network performance. The protocol includes technology specific offset parameters whose values are adjusted on-the fly based on already available network performance metrics (e.g., data rates, number of connected user equipment).Görünür ışık frekans bandında (390-700 nm) çalışan optik kablosuz iletişim sistemleri, görünür ışıkla haberleşme (visible light communication, VLC) olarak adlandırılır. VLC sistemleri, insan gözü ve aydınlatma seviyeleri üzerinde herhangi bir olumsuz etki yaratmadan, ışık yayan diyotların (light emitting diode, LED) çok yüksek hızlarda modüle edilmesi prensibine dayanmaktadır. VLC erişim noktası (access point, AP) olarak kullanılan LEDlerin hem iç mekanlarda (örn. ev ve ofis aydınlatması vb.) hem de dış mekanlarda (örn. sokak lambaları, trafik ışıkları, aracın ön/arka ışıkları vb.) kullanımı giderek artmaktadır. LEDlerin hem aydınlatma hem de haberleşme amaçları için ikili kullanımı, devrim niteliğinde bir çözümdür ve kablosuz iletişimde yeni bir dönem açma potansiyeline sahiptir. Bu bağlamda, VLC endüstriyel ilgiyi çekmiş ve ilgili uluslararası standardizasyon çalışmaları çoktan başlamıştır. Bu tezde, yüksek bağlantı güvenilirliğine sahip, yüksek veri hızlı VLC sistemleri geliştirilmiştir. Hem aydınlatmayı hem de iletişimi destekleyen ikili işlevsellik göz önünde bulundurularak, hedeflenen yüksek veri hızlarını ve bağlantı güvenilirliğini karşılamak için; adaptif iletim, dikey frekans bölmeli çoklama (orthogonal frequency division multiplexing, OFDM), çok girişli çok çıkışlı (multiple-input multiple-output, MIMO) ve hüzmeleme (beamforming) ile yoğun (massive) MIMO iletim dahil olmak üzere gelişmiş fiziksel katman teknikleri araştırılmıştır. MIMO iletim amacıyla birden fazla sayıda LEDleri kullanmak için, koordineli ve ortak bir sinyal işleme mekanizması kurulmalıdır. Bu amaçla ilk olarak, merkezi (centralized) bir platform önerilmiştir. Bu platformda, temel bant birimleri (baseband unit, BBU) LEDlerden ayrılıp; tüm sinyal işleme birimlerinin birlikte çalıştığı, merkezi birime (centralized unit, CU) kaydırılmıştır. Ardından, iki farklı gelişmiş PHY tekniği tasarlanmış ve önerilen platform üzerinde çalıştırılmıştır. İlk olarak, bit ve güç yükleme (bit and power loading) özelliğine sahip, tekrarlı kodlama (repetition coding) ve uzamsal çoklama (spatial multiplexing) arasında MIMO mod geçişi yapabilen OFDM tabanlı VLC sistemi tasarlanmıştır. Hedeflenen bit hata oranını karşılarken, veri hızını en üst düzeye çıkarmayı amaçlayan adaptif algoritma; modülasyon tipine, güç seviyesine ve MIMO moduna bağlı olan bir optimizasyon problemi olarak formüle edilmiş ve çözülmüştür. İkinci ileri PHY tekniği olarak, yoğun MIMO iletimi araştırılmıştır. Yoğun MIMOnun tüm avantajlardan yararlanmak için; kanal durumu bilgisi, verici tarafında mevcut olmalıdır. Aşağı (downlink, DL) kanal referans sinyalleri yoluyla DL kanalın tahmini, hem DL hem de yukarı (uplink, UL) kanalda büyük bir sinyalleşme yüküne neden olur ve düzgün tasarlanmadığı takdirde yoğun MIMO sisteminin uygulanmasını mümkün kılmaz. Bundan dolayı analiz, sınırlı sayıda referans sinyalini dikkate alarak yapılmıştır. Küresel kanal matrisini elde etmek için, iç ortam geometrisinden ve LEDlerin düzeninden yararlanarak enterpolasyonun yapıldığı, uzamsal, frekans ve zaman alanlarında farklı referans sinyal düzenlemeleri önerilmiştir. Bunların değişen ağ koşullarına göre adaptif bir seçimi, DL ve UL veri hızları arasında denge sağlamak amacıyla, ayrıca tasarlanmıştır. Merkezi platform, heterojen ağlarda VLCyi var olan kablosuz haberleşme teknolojilerle (örn. milimetre dalga (milimeter wave, MMW) iletimi) entegre etme sürecine de birçok fayda sağlar. Merkezi platform yapısında, VLC ağında olduğu gibi; BBU, MMW APden ayırılıp ve aynı CU içine yerleştirilir. Bu sayede, tüm network farkında ağ mimarisinden yararlanarak, adaptif dikey (MMW ve VLC APler arasında) ve yatay (VLC APler arasında) geçiş (handover) mekanizması, ağ performansını artırmak için tasarlanmıştır. Geçiş mekanizmaları teknolojiye özgü ofset parametreleri içerir ve bu parametreler, CUda halihazırda bulunan ölçülere göre (örn. veri hızları, bağlı kullanıcı ekipmanı sayısı) anında ayarlanmıştır
Error bounds of pair distribution function analysis in characterization of thermal disorder in nanocrystals
No full textN/
Street vendors' adaptive strategies and the dynamic nature of urban space: Developing an integrative framework in Kano, Nigeria
No full textThis thesis attempts to develop a framework that integrates street vendors within the urbanscape. Spaces within the cities are increasingly becoming scares and valuable, resulting in increased competition for them. Coupled with the desire by city administrators and capital interest in create an ideal vision for a city, street vendors are, as a result, pushed away for potentially viable vending locations. However, as is in the global south, vendors are critical services provider to both the formal and informal sector. Additionally, the methods up till now employed to redress these gaps are falling short. Different approached have been taken, such as the design/planning approach, the inclusivity/people/procedural approach, the organisational approach. All have set out strategies for incorporating street vendors, from the mundanity spatial allocation, rethinking vending instrument design, to suggesting urban planning/design process. Despite their attempts, hostile actions and evictions have continued, emphasising their ineffectiveness at integration. Conversely, the number of vendors is increasing despite hostilities. This has created a vicious circle, one counterproductive to the cities, vendors, and users. Within this regard, set to create an alternative, integrative framework informed by the everyday experience of vendors, and the perception of professional and urban users. Taking Kano as a site of investigation, three streets (MM-Way, DEL and SSA) were selected using space syntax methods in conjunction with other qualitative criteria. Street vendors' (ambulatory and non-ambulatory) behavioural mapping was conducted to ascertain the categories and type of vending activities along each street, as well as study their spatial practices and external influences exerted on them. In the philosophical tradition of constructivism, vendors selected through snowball sampling were interviewed and thematically analysed to gain more in-depth knowledge into their adaptive strategies while operating. Users and professional views were sought out to establish the perception of each group towards street vending within the city. The result showed views in a converging, diverging and equivalence range among users and professional. This is translated as an opportunity for co-opting allies. Combining the date with literature regarding integrative approaches, a multidisciplinary framework was developed that placed street vendor's spatial techniques as the entry frame for proposing integration into new and existing geographies. A combination of the result shows that the framework can act as a retrofit, the views espoused by the participant as gauges in evaluating the diversity of participation processes while avoiding tokenism. Finally, street vendors design adaptions were domesticated within the resistance narrative complementary to the conceptions developed within urban sociology.Bu tez, sokak satıcılarını urbanscape ile bütünleştiren bir çerçeve geliştirmeye çalışmaktadır. Şehirlerin içindeki alanlar giderek daha korkutucu ve değerli hale geliyor, bu da onlar için artan rekabetle sonuçlanıyor. Şehir yöneticilerinin arzusu ve bir şehir için ideal bir vizyon yaratma arzusuyla birleştiğinde, sokak satıcıları, sonuç olarak, potansiyel olarak uygulanabilir satış yerleri için itiliyor. Bununla birlikte, küresel güneyde olduğu gibi, satıcılar hem resmi hem de gayri resmi sektör için kritik hizmet sağlayıcılarıdır. Ek olarak, bu boşlukları kapatmak için şimdiye kadar uygulanan yöntemler yetersiz kalıyor. Tasarım / planlama yaklaşımı, kapsayıcılık / insanlar / prosedür yaklaşımı, örgütsel yaklaşım gibi farklı yaklaşımlar benimsenmiştir. Hepsi, sokak satıcılarını, gündelik mekansal tahsisattan, otomat enstrüman tasarımını yeniden düşünmeye ve kentsel planlama / tasarım sürecini önermeye kadar dahil etmek için stratejiler belirlemiştir. Tüm girişimlerine rağmen, entegrasyondaki etkisizliklerini vurgulayan düşmanca eylemler ve tahliyeler devam etti. Tersine, düşmanlıklara rağmen satıcıların sayısı artıyor. Bu, şehirlere, satıcılara ve kullanıcılara ters etki eden bir kısır döngü yarattı. Bu bağlamda, satıcıların günlük deneyimlerinden ve profesyonel ve şehirli kullanıcıların algısından bilgilendirilen alternatif, bütünleştirici bir çerçeve oluşturmaya ayarlayın. Kano bir araştırma alanı olarak alınarak, diğer nitel kriterlerle birlikte uzay sözdizimi yöntemleri kullanılarak üç cadde (MM-Way, DEL ve SSA) seçildi. Sokak satıcılarının (ambulatuvar ve ambulatuvar olmayan) davranışsal haritalaması, her bir cadde boyunca otomat faaliyetlerinin kategorilerini ve türlerini belirlemek, ayrıca mekansal uygulamalarını ve üzerlerine uygulanan dış etkileri incelemek için yapıldı. Felsefi yapılandırmacılık geleneğinde, kartopu örneklemesi yoluyla seçilen satıcılarla mülakatlar yapıldı ve çalışma sırasında uyarlanabilir stratejileri hakkında daha derinlemesine bilgi edinmek için tematik olarak analiz edildi. Her bir grubun şehir içinde satışta satışa yönelik algısını oluşturmak için kullanıcılar ve profesyonel görüşler araştırıldı. Sonuç, kullanıcılar ve profesyoneller arasında yakınsayan, uzaklaşan ve denklik aralığında görüşler gösterdi. Bu, müttefiklerle işbirliği yapmak için bir fırsat olarak çevrilir. Tarihi, bütünleştirici yaklaşımlarla ilgili literatürle birleştirerek, sokak satıcısının mekansal tekniklerini yeni ve mevcut coğrafyalara entegrasyonu önermek için giriş çerçevesi olarak yerleştiren çok disiplinli bir çerçeve geliştirildi. Sonuçların bir kombinasyonu, çerçevenin bir güçlendirme işlevi görebileceğini, katılımcı tarafından belirteççilikten kaçınırken katılım süreçlerinin çeşitliliğinin değerlendirilmesinde ölçüt olarak benimsenen görüşler olduğunu göstermektedir. Son olarak, sokak satıcılarının tasarım uyarlamaları, kentsel sosyolojide geliştirilen kavramları tamamlayan direnç anlatısı içinde evcilleştirildi
Exploring covalent organic frameworks for H2S+CO2 separation from natural gas using efficient computational approaches
No full textCovalent organic frameworks (COFs) are emerged as strong adsorbent candidates for industrial gas separation applications due to their highly porous structures. In this work, we explored H2S+CO2 capture potentials of synthesized and computer-generated COFs from a natural gas mixture using an efficient, multi-level computational screening approach. We computed the adsorption data of a six-component natural gas mixture, CH4/C2H6/CO2/C3H8/H2S/H2O, for 580 synthesized COFs by performing Grand Canonical Monte Carlo (GCMC) simulations under industrially relevant conditions. H2S+CO2 selectivities and working capacities of COFs were computed to be 0.4-12.4 (0.2-8.5) and 0.01-5.36 (0.04-2.5) mol/kg at pressure-swing adsorption (vacuum-swing adsorption) condition. NPN-3 was identified as the best performing COF due to the competitive adsorption of H2S+CO2 over C2H6 and C3H8 as revealed by density functional theory (DFT) calculations. Structural (pore sizes, porosities, and topologies) and chemical properties (linker units and heats of gas adsorption) of the best-performing synthesized COFs were used to efficiently screen the very large number of hypothetical COFs (hypoCOFs). Results showed that isosteric heats of adsorption can be used to discover high performing hypoCOFs for H2S+CO2 separation from natural gas. Finally, we compared COFs, hypoCOFs, zeolites, carbon nanotubes, metal organic frameworks (MOFs) and concluded that several synthesized and computer-generated COFs can outperform traditional adsorbents in terms of H2S+CO2 selectivities. Our results provide molecular-level insights about the potential of COFs for natural gas purification and direct the design and development of new COF materials with high H2S+CO2 selectivities.European Union's Horizon 2020Publisher versio