266 research outputs found
Estimation of Radio Frequency Impairments and Channels for Multi-Carrier 5G and Beyond 5G Systems
No full textSimultaneous Communication and Power Transfer for WBAN/WPAN Applications
No full textWireless body and personal area networks have become commonplace in recent years in industrial, medical, and consumer-based applications, allowing a collection of devices such as medical sensors to be distributed around a person’s body or within their direct vicinity, to communicate with each other or a network controller to provide convenient personal services. Distributed devices are typically compact and can even be located within the human body. This produces several bottlenecks relating to RF ability and power availability which are addressed here.
In this thesis, two antennas are developed. The first is designed for implantable and ingestible applications offering robust wideband performance, covering all the useable licenced operating bands, in the complex material characteristic environment of the human body. The radiation characteristics of the proposed antenna outperform other published work with a smaller size, achieved through the novel application of split-ring resonators. The second is an off-body antenna which concurrently provides appropriately polarised bands for indoor and outdoor localisation and data communication. For its minimised size and wide bandwidth, this antenna also outperforms other antennas for WPAN applications published in the literature.
Two methods for simultaneous wireless information and power transfer have been proposed in this work, based on novel theoretical ideas and hardware implementations. A symbol splitting system separates the information- and non-information- carrying components of a signal, using each for data reception and energy harvesting, respectively. The second method makes use of the characteristic of the requisite rectifier in the power conversion from RF to DC, recycling the inevitable third harmonic for data reception. The hardware required to achieve both methodologies utilise couplers and each architecture has been proven feasible through simulation and measurement. They provide comparable performance to other published systems, offering a compact, efficient, and convenient route to simultaneous wireless information and power transfer
Time Synchronization and Its Applications in Wireless Sensor Networks
No full textTime synchronization is an essential component of wireless sensor networks (WSNs) that play a key role in the thriving Internet of Things (IoT), supporting IoT applications from large-scale monitoring & event detection to collaborative interactions. The large-scale applications based on resource-constrained sensor nodes promote the development of WSN time synchronization towards the three major aspects of lower energy consumption, lower computational complexity, and higher multi-hop time synchronization accuracy. It is these three aspects that we focus on in our contributions to the development of WSN time synchronization, which are presented in this thesis together with their applications to optimal bundling and node identification
SOLAR PHOTOVOLTAIC POWER INTERMITTENCY UNDER PASSING CLOUDS: CONTROL, FORECASTING, AND EMULATION
No full text
A Near-field Wireless Power Transfer System with Planar Split-ring Loops for Medical Implants
No full textEducational Expectations, Academic Performance, and Common Mental Disorders: A Longitudinal Analysis of Chinese Adolescents
No full textThis doctoral thesis is presented in the format of a publication-based thesis, comprising a series of interlinked peer-reviewed papers that collectively investigate the complex relationships between educational expectations, academic performance, and mental health among Chinese adolescents. Through these connected publications, the thesis systematically explores the prevalence, correlates, and consequences of common mental disorders within the Chinese educational context, offering both empirical insights and practical recommendations for intervention.
The mental health of children and adolescents has increasingly become a focal point of global health and educational research. Common mental disorders (CMDs) such as anxiety and depression among adolescents have garnered attention due to their rising prevalence and significant impact on academic performance. These issues are especially pressing in East Asian contexts like China, where academic pressure is intense, and societal expectations regarding academic success are high. This research delves into the intersection of educational expectations, academic performance, and adolescent mental health within the Chinese educational system.
The necessity for this research is underscored by the growing body of evidence linking mental health disorders with academic underachievement. Adolescents struggling with anxiety or depression often face difficulties in concentrating, retaining information, and engaging in academic activities, leading to a cycle of poor performance and increased psychological distress. Moreover, misaligned educational expectations—whether overly high or unrealistically low—can exacerbate these issues, placing students in a constant state of stress.
In light of this context, this publication-based thesis seeks to fill the gap in the literature by examining both the prevalence of CMDs and their relationship with academic performance in China. Additionally, it also intends to explore the role of educational expectations in shaping these outcomes. The findings will not only provide valuable insights into the mental health challenges faced by Chinese adolescents but also offer evidence-based recommendations for implementing mental health support in schools.
This thesis aims to address three core research questions across its constituent publications: (i) "What is the prevalence of anxiety and depression among Chinese adolescents in urban school settings, and how are these mental health disorders associated with academic performance?", (ii) "How do perceived educational expectations from parents, teachers, and adolescents themselves align with or diverge from actual academic performance?", and (iii) "What is the impact of expectation-performance alignment or misalignment on adolescents' psychological well-being, particularly regarding anxiety and depression?" Additionally, the thesis offers recommendations for policy practice based on these findings, with a specific focus on the development of school-based mental health programs.
The research comprises three empirical studies and a policy paper. Study 1 explores the prevalence and co-morbidity of CMDs and their associations with academic performance, employing cross-sectional data from 1,698 junior middle school students in Suzhou and Qingdao. Study 2 employs a longitudinal design to examine risk factors for CMDs, with an emphasis on how misalignments in educational expectations among parents, teachers, and students affect mental health. Study 3 employs a longitudinal design to investigate the long-term effects of CMDs and educational expectations on academic outcomes. The policy paper synthesizes these findings to offer actionable recommendations for enhancing mental health support within schools.
Key findings indicate notably elevated rates of CMDs, with nearly half of the sample experiencing symptoms of depression and anxiety at clinically significant levels, and nearly 40% showing co-morbid conditions. CMDs were strongly associated with poorer academic performance, exhibiting a dose-response relationship between symptom severity and achievement. Furthermore, misalignment between educational expectations and actual performance emerged as a significant predictor of psychological distress, underscoring the need for interventions that foster realistic and supportive expectations.
This thesis emphasizes the critical importance of culturally tailored mental health interventions and education system reforms in China. Recommendations include implementing school-based mental health programs, aligning educational expectations with students' abilities, and promoting collaboration among parents, educators, and policymakers. By addressing the complex interplay of mental health, educational demands, and cultural factors, this research provides valuable insights and evidence-based strategies for fostering balanced development in high-pressure academic settings
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