Seamless roaming and guaranteed communication using a synchronized single-hop multi-gateway 802.15.4e TSCH network

Industrial wireless sensor networks (WSNs) are being used to improve the efficiency, productivity and safety of industrial processes. An open standard that is commonly used in such cases is IEEE 802.15.4e. Its TSCH mode employs a time synchronized based MAC scheme together with channel hopping to alleviate the impact of channel fading. Until now, most of the industrial WSNs have been designed to only support static nodes and are not able to deal with mobility. In this paper, we show how a single-hop, multi-gateway IEEE 802.15.4e TSCH network architecture can tackle the mobility problem. We introduce the Virtual Grand Master (VGM) concept that moves the synchronization point from separated Backbone Border Routers (BBRs) towards the backbone network. With time synchronization of all BBRs, mobile nodes can roam from one BBR to another without time desynchronization. In addition to time synchronization, we introduce a mechanism to synchronize the schedules between BBRs to support fast handover of mobile nodes.Comment: Short paper version of a paper submitted to Ad-Hoc Networks Journal by Elsevie

Synthesis of ZnO Nanowires and Their Photovoltaic Application: ZnO Nanowires/AgGaSe 2

In this investigation, hydrothermal technique was employed for the synthesis of well-aligned dense arrays of ZnO nanowires (NWs) on a wide range of substrates including silicon, soda-lime glass (SLG), indium tin oxide, and polyethylene terephthalate (PET). Results showed that ZnO NWs can be successfully grown on any substrate that can withstand the growth temperature (~90°C) and precursor solution chemicals. Results also revealed that there was a strong impact of growth time and ZnO seed layer deposition route on the orientation, density, diameter, and uniformity of the synthesized nanowires. A core-shell n-ZnO NWs/p-AgGaSe2 (AGS) thin film solar cell was fabricated as a device application of synthesized ZnO nanowires by decoration of nanowires with ~700 nm thick sputtering deposited AGS thin film layer, which demonstrated an energy conversion efficiency of 1.74% under 100 mW/cm2 of simulated solar illumination

Understanding Syrian parents’ educational involvement in their children's primary education in Turkey

Parental involvement in education is significant for children's schooling experience and their cognitive and academic development. It also plays a role in refugee children's success and integration in the host country. However, understanding refugee parents’ educational involvement can be a complex issue because of their different cultural beliefs and unique challenges as refugees. Drawing on 20 in-depth interviews with Syrian parents in Turkey, this study examines how they are involved in their children's primary education. The findings indicate that the type and degree of parents’ involvement are shaped by their capabilities, resources, and challenges. Focusing only on parents’ perspectives, this study fills a gap in understanding Syrian parents’ involvement in their children's education in Turkey. Syrian parents were interested and involved in their children's education, but home-based involvement, the most frequent type, is often invisible to school staff. They were less involved in other ways because of a variety of challenges and a lack of capabilities and resources

Uncertainties shaping parental educational decisions:The case of Syrian refugee children in Turkey

Around a million school-aged minors from Syria have been living in Turkey with temporary protection status over an unanticipated extended period. This prolonged temporariness leads to uncertainties and unpredictabilities for Syrian families regarding how long they will be staying in Turkey. Drawing on 17 interviews with Syrian mothers and 3 couples, this study examined the ways in which uncertainties shaped parental decisions on minors' education. The findings indicated that uncertainties played a key role in shaping the educational decisions of Syrian parents, particularly in their children's Turkish language acquisition and educational performance. This study not only fills the gap in understanding the effects of uncertainties in parental educational decisions emanated from a prolonged temporariness, but also argues that living in an uncertain context causes hurdles in language acquisition which has major educational and social consequences for children

Synchronous Machine Modeling Precision and Efficiency in Electromagnetic Transients

RÉSUMÉ L’objectif principal de cette thèse est l’élaboration d’une méthode de modélisation de la machine synchrone plus performante et plus précise, et des algorithmes pour le calcul et la solution des transitoires électromagnétiques. Le pas d’intégration numérique est un facteur clef pour ces aspects. La possibilité d’utiliser des pas plus grands permet d'augmenter la vitesse des calculs et donc d'étendre le champ d'application des méthodes de type électromagnétique. Cette thèse propose quatre modèles de façon à améliorer la précision du modèle dq0 classique tout en maintenant son efficacité. Trois de ces modèles utilisent le dq0 avec une précision accrue de la modélisation. Parmi les modèles précis se retrouve le dq0 avec des pas d'intégration intermédiaires. L’efficacité est maintenue par la restriction du modèle à l’usage durant des intervalles transitoires, là où la précision du modèle classique dq0 diminue. Ces modèles fournissent une modélisation précise tout en maintenant la vitesse du dq0 classique. Cependant, ils sont conçus spécialement pour les cas typiques d'étude de stabilité transitoire de réseau, et leur précision se détériore quand l’exactitude du modèle est nécessaire pour une grande partie de l’intervalle de simulation complète. Le meilleur modèle nommé PD-dq0 est obtenu en appliquant la transformation de ‘’Park’’ aux équations discrétisées dans le domaine des phase. Les études d’évaluation de la précision et de l’efficacité démontrent que le modèle PD-dq0 est supérieur aux autres modèles proposés dans la littérature. L’analyse de précision est effectuée avec les contraintes de précision du réseau environnant. Donc, ce travail contribue également à une meilleure évaluation de la précision numérique et de l’efficacité des engins de simulation étudiés.---------ABSTRACT The main objective of this dissertation is the establishment of more efficient and more precise synchronous machine modeling approaches and solution algorithms for the computation of electromagnetic transients (EMT). Numerical integration time step size is a key factor in both aspects. The capability to use larger time steps in EMT-type simulation methods also contributes to the extension of such methods into the efficient simulation of electromechanical transients. In this thesis, four new models are proposed in order to improve the precision of the classical dq0 model while maintaining its efficiency. Three of them use the classical dq0 model with increased accuracy. The most accurate models are: dq0 with internal intermediate time step usage, phase-domain and voltage behind reactance. Efficiency is maintained by restricting the accurate model usage to the transient intervals where the precision of the classical dq0 formulation decreases. This approach provides accuracy while maintaining classical dq0 computational speed. However, these three models are designed for typical transient stability cases and their performance deteriorates when the accurate model usage is needed for a large portion of the complete simulation interval. The last forth model proposed in this thesis is obtained by applying Park’s transformation to the discretized equations of the phase-domain model. This model maintains the precision of the phase-domain model and eliminates its computational inefficiencies through a constant admittance matrix. Unlike the first three models, its efficiency does not change with simulated system and phenomenon. Precision and efficiency assessment studies demonstrate that this model is superior in both aspects and should be chosen for the computation of both electromagnetic and electromechanical transients in the same computational framework

In Debt to the State: Lived Experiences of Indebtedness in State-led Housing Projects in Istanbul

Over the last couple of decades, global debt has soared. Withdrawal of state welfare provision, expansion of financial markets, and dependency of people on credit for basic needs have led to increased indebtedness. Household debts are piling up across the world, in the form of mortgages, student loans, medical debts, credit card debts, and more. Although debt is often seen as a financial transaction in the form of borrowing and repayment, scholars recognize that debt is also a power relationship inseparable from an overall set of interdependencies and a social experience ingrained with subjectivities, obligations and aspirations. Our lives are shaped by the ebb and flow of debt relations. Nevertheless, the lived experiences of indebtedness, everyday negotiations of debts, with regards to power, conflict and consent, and the embodied and emotional labour of caring for debts are still understudied areas. This dissertation draws from ethnographic research conducted in 2019 that focuses on state-led, debt-based housing provision for low-income groups in Turkey. The research examines lived experiences of indebtedness in mass housing projects developed by the state’s Mass Housing Administration (TOKI). The ethnographic fieldwork employs multiple qualitative methods including in-depth interviews with TOKI mass housing estate residents, semi-structured interviews with key informants, public officials, and local actors, as well as focus groups, participant observation and document analysis. By tracing the experiences of indebted households, as well as the narratives created through the state’s housing policy and practice, this research interrogates (1) how ‘debt to state’ is manifested and experienced (2) how the Turkish state’s housing policy operates and shapes gender relations of homemaking and homeownership (3) how debts are cared for in the context of state-led housing provision for low-income groups in Turkey. I share the findings of this research in three empirical and one theoretical article-based chapters. Chapter Three proposes a feminist direction for financialization research in economic geography informed by Social Reproduction Theory. The chapter argues that as austerity regimes exacerbate debt-based finance and household indebtedness across the world, debts are cared for within the social reproductive capacities of home, while the capacity to care for others depletes through precarity and debt. The chapter offers a framework for ‘caring for debts’ by broadening our conceptualizations of subjectivity formation in financialization research and incorporating an embodied understanding of finance and debt. Chapter Four examines debt-based housing provision and lived experiences of indebtedness in low-income mass housing estates to understand how policy shapes relations of everyday finance, debt, real estate, and politics. The paper shows that as households mitigate current debt burdens with the hope of future financial gains in real estate, ‘debt to state’ plays a significant role in establishing consent around the neoliberal transformation of urban land. The results of this paper offer insights into how neoliberal housing policies rely upon and rework local communities and networks of labour and politics. Chapter Five puts a gender lens on TOKI’s ‘social’ housing provision through feminist critical policy analysis and reveals that the political economy of TOKI’s housing policy and practice not only produces gendered outcomes but also contributes to the reproduction of patriarchal property relations and fixing them in the urban space. Finally, Chapter Six examines the conditions of women's labour in TOKI housing estates and contributes to feminist economic geography by theorizing caring for debts as women’s work. My research contributes to the dialogue between urban economic geography and feminist political economy in the domain of financialization, offers avenues for geographical research that are empirically attuned to lived experiences and embodied subjectivities of everyday finance and debt. Accordingly, this work contributes to diverse theories of debt by flipping the narrative of debt as a personal responsibility to a broader understanding of debt as a systemic and structural problem in neoliberal society. Also, my research provides a gender lens on housing policy and contributes to feminist economic geography and labour studies in the domain of women’s labour by theorizing ‘caring for debts’ as women’s work. My practical contribution is a better understanding of the politics of debts to state, and insight for urban advocates to consider alternative ways of resisting isolation and disenfranchisement in an indebted society