Dissertations / Theses on the topic 'Communications engineering not elsewhere classified'
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1
Song, Dong Hyun. "Power struggles in Korean cyberspace and Korean cyber asylum seekers." Thesis, Goldsmiths College (University of London), 2012. http://research.gold.ac.uk/8052/.
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This thesis examines the potential power of internet users to use the internet in the conduct of their everyday lives by discussing the impact of state and non-state actors on cyberspace. The debate about ‘who controls the internet?’ has avoided the question of the power of internet users, which is needed to understand the character of cyberspace. Theoretical debates identify the overwhelmingly territorial nature of cyber governance through nationally developed and enforced legislation, which is in direct opposition to the power of transnational ICTs. This thesis contributes to this theoretical debate through the use of the concepts of alternative and radical media, which are usually categorised as anti-establishment resistance strategies. I use Michel de Certeau’s notion of the heterological practice of everyday life to develop a perspective on the power of the powerless on the internet. I also adopt Franklin’s theoretical stance on the relations between state, non-state, and social actors, which is influenced by de Certeau’s ideas about the plurality of space. In order to illustrate this argument, I discuss the Korean ‘cyber asylum seeker’ phenomenon, which arose when Korean internet users migrated from local web portals to global corporations, such as Google and YouTube, who had refused to comply with the restrictions that the Korean government policies imposed on the local internet. This development allowed Korea cyber asylum seekers to become power holders, thus expanding the reach of Korean cyberspace. The Korean cyber asylum phenomenon was a result of both the Korean government’s cyber intervention following the 2008 Candlelight protest and Korean web portals’ compliance. I therefore understand the Korean cyber asylum seeker phenomenon from the perspective of a tripartite inter-relationship between the Korean government, the web portals, and internet users. This tripartite approach sheds new light on current debates about the questions: ‘Who controls the internet’, ‘Why is it controlled?’ and ‘How is it controlled?’ by adding the question, ‘What other groups have had an impact on power formations in cyberspace?’ My field research points to the significance of internet user mobility for a more complete understanding of the effect of the Korean government and the web portals on the expansion of Korean cyberspace. The research project is based on an analysis of the Korean government’s internet policy, business reports of Korean web portals, and interviews with officials from government bodies, the Korean internet industry, activists, citizens and online community members, as well as online community observation.
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Mahmod, Jowan. "Reconfiguring diaspora : Kurds online." Thesis, Goldsmiths College (University of London), 2012. http://research.gold.ac.uk/8010/.
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This research examines diasporic transformations and the construction of belongings through new technologies of communication by looking at young Kurdish diasporas in Sweden and the UK. It argues that the diaspora concept needs to be reconceptualised in light of digital information and communication technologies and in relation to the imagined community. Empirical evidence from Kurdish diasporas has drawn attention to some missing gaps in the literature. The research asks what it means to be a Kurd in diaspora and what role new media and online communities have in the renegotiation and construction of belongings. By engaging with post-colonial and feminist studies, I unpick fixed categories of identity, belongings and home, and I argue for performativities of those belongings. Based on a year-long ethnographic online study supplemented by offline face-to-face interviews with young Kurds in these locations, and with additional reference to homeland- based Kurds, the research presents three main empirical chapters based on themes derived from the online community’s concerns, and focuses on Swedish, British, and Kurdish forums. The chapters discuss gender and religious tensions; cultural elements and historical suffering; and political engagements in homeland and settlement countries. A fourth chapter takes a step back from online and offline material and examines the comparative approach between the two diasporas, diasporic and homeland Kurds, in both offline and online environments. Against the background of such a close-up comparative study, this research argues for a reconsideration of diasporic formations that are currently fixed between homeland and settlement country, and it presents new perspectives on these that relates to new definitional positions in diasporic formations that have significant implications for the concept of the imagined community.
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Schlosberg, Justin. "Power in the dock : media and accountability in the digital age." Thesis, Goldsmiths College (University of London), 2012. http://research.gold.ac.uk/8029/.
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Contemporary democratic discourse places emphasis on accountability as the basis of power legitimacy and the scholarly literature across disciplines has reserved a special space for the media in that process, for better or for worse. But exactly who is held to account, when, how and by whom, remain troubling questions in the study of media, politics and power. Amidst displays of adversarial journalism without fear or favour, how far are powerful interests still able to control the agenda and manipulate outcomes? The research undertaken here set out to interrogate the notion of media spectacle in a different way from which it has been commonly applied in critical media theory. In particular, its intimate association with sensationalism and tabloidisation threatens to obscure the role of spectacle in what are considered the mainstays of ‘serious’ or responsible news. The Sun might still be the most popular newspaper in Britain, and online news the fastest growing platform, but it is the serious news outlets of traditional media – public service broadcasting, broadsheets, weeklies etc – which remain by far the most credible sources of news and information. And it is credibility which holds the key to ideological power. The research involved extensive analysis of archived television news programmes, supplemented by 50 interviews with a cross section of news producers and actors including journalists, news executives, politicians, campaigners, press officers, lawyers and civil servants. The core subject is terrestrial television news in the UK – a public service regulated platform with a longstanding reputation for high quality journalism. My overall concern is not so much with scandal involving official misconduct or misdemeanour, but rather controversies that point to systemic institutional corruption of the kind that transcends individuals and party politics. These controversies are no longer rare exceptions in the contemporary newscape and their existence raises profound questions about the scope of accountability through the media. There has, however, been surprisingly little critical assessment of such coverage. This provided the overarching motivation for the research; a core premise being that only by examining those instances where mechanisms of accountability appear most far reaching, can we gain a new understanding of ideological power in the age of transparency.
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Kolbl, Josef Karl. "Low-noise frequency synthesis and picosecond timing for satellite laser ranging systems." Thesis, University of Central Lancashire, 2001. http://clok.uclan.ac.uk/20201/.
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The main aims of the research are to develop various high-speed hardware circuits based on the latest electronic devices and integrated circuit technologies to provide time measurement with one picosecond accuracy, thereby enabling the development of a satellite laser ranging (SLR) system with submillimeter precision. Different types of oscillators and frequency multipliers have been developed (RF and microwave) in order to provide a synchronous and low phase noise clock signal to the SLR timing system, which is phase-locked to the Universal Time Clock (UTC). A technique to quantify phase noise in signal sources is presented and verified. The development of the ranging system encompasses the analog timing verniers, the digital timing system, acquisition and processing of the ranging data, and the controlling of the peripherals, like the laser. The mixed analog/digital timing system architecture provides a time interval determination of two events with picosecond accuracy. Optical calibration techniques and an electronic timing calibration technique were developed to provide calibration of the timing system down to one picosecond accuracy and femtoseconds of resolution, traceable to the International Standard (speed of light, metric standard). The work done has led to several electronic modules for measuring precisely laser runtimes to artificial satellites and to the Moon which are now in successful and permanent operation in five SLR stations around Tokyo, one SLR station in Australia, and one SLR station in Germany. Furthermore, the work has produced three papers and two patents and won the First Prize of Innovation Awards from Deggendorf Government. The research and development work pushed the picosecond timing technology to an extent where the SLR stations in Australia, Tokyo and Germany now have a significant improvement in their ranging data accuracy in comparison to their previous timing equipment, thereby achieving more precise environmental monitoring.
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Macwhannell, Robert. "An investigation of Organisational Carbon Accounting (OCA) practices in the defence sector to determine how these can best support low carbon technology innovation." Thesis, University of Central Lancashire, 2018. http://clok.uclan.ac.uk/23077/.
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‘Climate change’ and ‘defence’ are becoming closely associated topics, particularly in relation to the potential that the defence sector has to support the development of low carbon technologies. This exploratory research applies an inductive approach and a strongly archival strategy in order to investigate how Organisational Carbon Accounting (OCA) practices in the defence sector can best support low carbon technology innovation. It takes an interdisciplinary approach to the literature, drawing on the fields of Carbon Accounting, Defence Industrial Policy, and Innovation Studies. It finds that there some difficulties allocating emissions to organisations in existing OCAs, which are particularly marked in the defence sector due to close working relationships between organisations. These allocations can result in abstract OCAs that do not always reflect the underlying activities causing emissions to be produced. In contrast, ‘Project Level’ Carbon Accounts focused on large-scale collaborative programmes can better account for the emissions of the defence sector in an understandable way that engages new and relevant actors to defence-energy debates. These accounts are therefore more likely than existing OCA practices to support low carbon technology development across innovation networks. A positive selection environment for low carbon technologies can be promoted if these ‘Project-Level’ Carbon Accounts are presented within an appropriate strategic framework, and this research describes the relevance of the defence sector concepts of ‘resilience’ and ‘endurance’ and the related metric of the Fully Burdened Cost of Energy (FBCE). The findings emphasise the value of sector-level analyses of OCA practices, which are not represented in the literature at present. The sector-level perspective can help identify relevant methods from the wider Carbon Accounting field that can improve existing organisational approaches. More importantly, it can help researchers engage with the fundamental question of what Carbon Accounting is for, by analysing how the OCA practices within a specific sector support or inhibit its most effective contribution to climate change mitigation.
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Thakore, Renuka. "A strategic engagement model for delivering energy efficiency initiatives in the English housing sector." Thesis, University of Central Lancashire, 2016. http://clok.uclan.ac.uk/18647/.
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Housing sectors have particular significance and impact on resource use, deployment and sustainability. Given this, they are inextricably enmeshed in a raft of conjoined issues, ranging from energy, production and consumption, through to effective governance structures and leveraged sustainable transformations. However, the real challenges facing the Housing sectors rest with the supportive societal structures which underpin the operationalisation of these issues. This includes such factors as consultation and engagement, and the identification of critical drivers and proven solutions – which are tangible barriers for sustainable transformations (particularly in the English housing system). This research presents a conceptual model – STRIDES (Strategic Tri-level Relational Interventions for Delivering Energy efficiency and Sustainability), which purposefully addresses the aforementioned barriers, and critically challenges thinking and engagement. STRIDES explicitly captures 5-INs, which embodies interrelated essential conditions needed for successful transformation. This conceptual model was developed using a mixed-method approach, engaging constructivism/interpretivism to guide the development and augmentation of this (to ensure maximum relevance and impact). The English housing system was used as the primary lens – which helped both shape and inform the research methodological approach. STRIDES was developed through: an online survey questionnaire (for systems-knowledge); Delphi questionnaires (for target-knowledge); and focus group discussions (for transformative-knowledge). The theoretical constructs and methods revealed exclusive hidden dialogue of composite correlated multi-perspective stakeholders, which highlighted tri-level influences on interdependent system-components for effective governance of sustainable transformations. Recognising and prioritising relationally responsive emerging strategies arising from STRIDES help stakeholders appreciate subtle nuances and forces across and beyond contexts. This helps positioning, especially to shape/tailor strategic interventions to deliver meaningful objectives of these sustainable transformations.
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Burchell, Kenzie. "Negotiating connection without convention : the management of presence, time and networked technology in everyday life." Thesis, Goldsmiths College (University of London), 2012. http://research.gold.ac.uk/7995/.
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This thesis explores the social processes through which technological change and technologies themselves are negotiated in everyday life. I look to interpersonal communication as a site of such negotiation and focus on the networked practices that extend from mobile telephones, personal computers, and online social platforms. The management of everyday life and interpersonal relationships are shaped by practices of communication management that work through the use of these technologies. I extend and inflect the phenomenological approach to co-presence in interpersonal communication, also reassessing notions of time, for the context of constant networked connection. Drawing from divergent theoretical approaches for understanding technology, an entry point for this thesis was formulated through social interaction. A grounded qualitative approach was used to engage with individuals’ experience of interpersonal communication across everyday domains and contexts of activity. A selection of 35 participants was asked to complete two in-depth interviews, thinking-aloud tasks, and a communication diary. The empirical findings are explored from three perspectives. First, individuals’ relationships to communication tools as objects in an everyday environment are understood for the perceived temporal pressures and a need for networked connection. Second, individuals’ management of those pressures is explored through their imposition of individually controlled barriers to interaction, through which domains of activity are managed by communication practices as relational domains, developing a form of networked awareness between individuals. Third, I examine the forms of negotiation taking place through the interdependency of individual practices, captured by notions of authenticity and perceptions of technologies, as well as a discourse about technology that is enacted through practice rather than communicated through content, what I call meta-communication. I conclude that the negotiated use and role of technologies in interpersonal relationships has implications for the negotiation of wider social changes to the role of technology and to everyday life itself.
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(8709819), Matthew Benjamin Booth. "Multiple Antenna Signal Processing Techniques for Millimeter Wave Communications." Thesis, 2020.
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Mobile devices operating at millimeter-wave (mmWave) frequencies are expected to comprise an integral part of fifth generation (5G) communication systems to meet increasing data rate demands. Massive multiple-input multiple-output (MIMO) and advanced signal processing techniques are required to overcome the harsh propagation environment in this spectrum. We focus on two aspects of MIMO communication systems.
First, the large number of antennas creates a challenge in aligning and tracking highly directional, narrow beams. Algorithms which rapidly adapt to the changing mobile environment are required. We propose a novel beam alignment and tracking algorithm for time-varying, sparse mmWave channels using multi-armed bandit beam selection. We show our algorithm has a more rapid initial beam alignment compared to other beam selection policies and, for dynamic channel support, long-term beamforming gain commensurate to omni-directional channel training. Simulation results are accomplished using idealized and realistic mmWave channel models.
Second, massive MIMO systems can generate potentially prohibitive amounts of data due to the large numbers of antennas. With modern parallel, low-rate analog-to-digital converters (ADCs), the bottleneck is often not in the quantization of the received signals but, rather, in the processing of the digitized bits. Therefore, we develop an adaptive algorithm for down-selecting the digital output data to meet some required output data rate threshold while simultaneously maximizing the information between the transmitted signal and the selected output.
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(9798128), David Gay. "Investigation of the applicability of power line communications for smart SWER." Thesis, 2013. https://figshare.com/articles/thesis/Investigation_of_the_applicability_of_power_line_communications_for_smart_SWER/13465160.
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"As demand for power increases in rural areas serviced by Single Wire Earth Return (SWER) networks, distribution issues are becoming increasingly evident. Voltage regulation and system capacity concerns are driving utilities toward using smarter compensation devices for network control in an attempt to provide longevity for aging SWER infrastructure. To date, despite increasing complexity in power delivery over SWER, no effective network monitoring solutions have been proposed.This paper examines the case for network monitoring and centralised management of smart compensation devices via PowerLine Communications (PLC). After establishing advantages in network monitoring, regulation and maintenance for SWER networks, narrowband and broadband PLC issues are reviewed. The channel capacity of typical SWER conductors is then evaluated and compared to data throughput requirements derived from existing infrastructure to validate the applicability of developing PLC over SWER infrastructureIn building a more efficient, smarter network, a degree of device autonomy will be eroded to facilitate a more holistically managed system. This can only be accomplished through communication between smart devices themselves and reporting to utilities, which in turn will require a communications medium. This thesis looks at the possibility of using the power distribution system as the communication medium."--Abstract.
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(8083247), Yong Hoon Kim. "INTEGRATED MODELING FRAMEWORK FOR DYNAMIC INFORMATION FLOW AND TRAFFIC FLOW UNDER VEHICLE-TO-VEHICLE COMMUNICATIONS: THEORETICAL ANALYSIS AND APPLICATION." Thesis, 2019.
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Advances in information and communication technologies enable new paradigms for connectivity involving vehicles, infrastructure, and the broader road transportation system environment. Vehicle-to-vehicle (V2V) communications under the aegis of the connected vehicle are being leveraged for novel applications related to traffic safety, management, and control, which lead to a V2V-based traffic system. Within the framework of a V2V-based traffic system, this study proposes an integrated modeling framework to model the dynamics of a V2V-based traffic system that entails spatiotemporal interdependencies among the traffic flow dynamics, V2V communication constraints, the dynamics of information flow propagation, and V2V-based application. The proposed framework systematically exploits their spatiotemporal interdependencies by theoretical and computational approaches.
First, a graph-based multi-layer framework is proposed to model the V2V-based advanced traveler information system (ATIS) as a complex system which is comprised of coupled network layers. This framework addresses the dynamics of each physical vehicular traffic flow, inter-vehicle communication, and information flow propagation components within a layer, while capturing their interactions among layers. This enables the capabilities to transparently understand the spatiotemporal evolution of information flow propagation through a graph structure. A novel contribution is the systematic modeling of an evolving information flow network that is characterized as the manifestation of spatiotemporal events in the other two networks to enhance the understanding of the information flow evolution by capturing the dynamics of the interactions involving the traffic flow and the inter-vehicle communication layers. The graph-based approach enables the computationally efficient tracking of information propagation using a simple graph-based search algorithm and the computationally efficient storage of information through a single graph database.
Second, this dissertation proposes analytical approaches that enable theoretical investigation into the qualitative properties of information flow propagation speed. The proposed analytical models, motivated from spatiotemporal epidemiology, introduce the concept of an information flow propagation wave (IFPW) to facilitate the analysis of the information propagation characteristics and impacts of traffic dynamics at a macroscopic level. The first model consists of a system of difference equations in the discrete-space and discrete-time domains where an information dissemination is described in the upper layer and a vehicular traffic flow is modeled in the lower layer. This study further proposes a continuous-space and continuous-time analytical model that can provide a closed-form solution for the IFPW speed to establish an analytical relationship between the IFPW speed and the underlying traffic flow dynamics. It can corporate the effects of congested traffic, such as the backward traffic propagation wave, on information flow propagation. Thereby, it illustrates the linkage between information flow propagation and the underlying traffic dynamics. Further, it captures V2V communication constraints in a realistic manner using a probabilistic communication kernel (which captures the probability).
Third, within the integrated modeling framework, this dissertation captures the impact of information flow propagation on traffic safety and control applications. The proposed multi-anticipative forward collision warning system predicts the driver’s maneuver intention using a coupled hidden Markov model, which is one of statistical machine learning techniques. It significantly reduces the false alarm rates by addressing the uncertainty associate improves the performance of the future motion prediction, while currently available sensor-based kinematic models for addressing the uncertainty associated with the future motion prediction. A network-level simulation framework is developed to investigate a V2V-based ATIS in a large-scale network by capturing its inter-dependencies and feedback loop. This modeling framework provides the understanding of the relationship between the travelers’ routing decisions and information flow propagation.
This thesis provides a holistic understanding of information flow propagation characteristics in space and time by characterizing interactions among information flow propagation, and underlying traffic flow, and V2V communications characteristics. The proposed models and the closed-form solution of IFPW speed can help in designing effective V2V-based traffic systems, without relying on computationally expensive numerical methods. An innovative aspect of this approach represents a building block to develop both descriptive capabilities and prescriptive strategies related to propagating the flow of useful information efficiently and synergistically generating routing mechanisms that enhance the traffic network performance. Given the lack of appropriate methodologies to characterize the information flow propagation, this thesis expects to make a novel and significant contribution to understanding the characteristics of V2V-based traffic systems and their analysis.
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(10716282), Xiaozhe Fan. "EXPLOITING LUMINESCENCE EMISSIONS OF SOLAR CELLS FOR INTERNET-OF-THINGS (IOT) APPLICATIONS." Thesis, 2021.
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The Internet-of-Things (IoT) devices have experienced an explosive growth during the last decades. The number of IoT devices is predicted to reach 36.4 billion by 2025, resulting in an urgent demand for high-density and high-capacity network connectivity. Recently, self-powered optical wireless devices have attracted more attention from both academia and industry. Although radio frequency (RF) technologies are readily available for various wireless applications, the RF
communication bands are becoming saturated due to the scarcity of the RF spectrum. Optical wireless communication (OWC) provides an attractive solution to overcome the shortage of RF bands. OWC is also attractive for low-power or even self-powered applications since optical energy is the most abundant in both indoor and outdoor scenarios.
This dissertation explores a new optical communication technique called optical frequency identification (OFID). This technique employs solar cells as an optical antenna, capable of harvesting energy and transmitting/receiving optical information. Transmission of information with a solar cell is achieved by modulating the cell's luminescent emissions. Two OFID system prototypes were designed,
fabricated, evaluated, and discussed.
A series of experiments have been carried out to exploit the feasibility of using a solar cell's luminescence emissions for optical communication and evaluate proposed two OFID system prototypes. This dissertation validated that luminescent emissions from a GaAs solar cell can be modulated for optical communications. Then, two photoluminescence (PL) modulators were proposed and compared in terms of their energy harvesting and communication performances. The first OFID system prototype, based on a dual-aperture reader and a microcontroller-based tag was validated and experimented for a remote temperature sensing application. The second prototype, based on a single-aperture OFID reader and an FPGA-based OFID module, was analyzed with an emphasis on the communication date rate, communication range, tag's cold-startup period and power consumption.
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(10716051), Tomohiro Arakawa. "Wireless Powered Communication over Inductively Coupled Circuits." Thesis, 2021.
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Wireless powered communication (WPC) is an emerging paradigm where wireless devices are powered over the air while exchanging information with them. This technology is attractive for various wireless applications, including classical radio-frequency identification (RFID) systems, implantable sensors, environmental sensing as found in agriculture and forestry, and simultaneous charging and telemetry communications for electric vehicles. While recent studies have shown that inductive coupling provides a more energy-efficient and robust channel for short and middle-range wireless transmission, most of the previous analyses on WPC have been limited to far-field transmission models. To this end, this work provides a comprehensive framework to design and analyze WPC over inductively coupled circuits. We consider three problems, namely, wireless power transfer (WPT), simultaneous wireless information and power transfer (SWIPT), and wireless powered communication network (WPCN) using multiple coupled coils. Each configuration is modeled by an abstract circuit model in which various effects, including mutual coupling and parasitic elements, are captured by a small number of measurable parameters. This technique allows us to not only eliminate the need for solving the circuit but also apply well-known signal processing techniques such as beamforming and channel estimation to inductively coupled models. For each of the three models, we derive the properties of the optimal source signal. In addition, we propose methods to design the load impedance of WPCN by taking into account the nonlinear effects due to impedance mismatches in the circuits.
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(9791285), Ronald Day. "Preventing design error in control room systems: A human factors approach." Thesis, 2013. https://figshare.com/articles/thesis/Preventing_design_error_in_control_room_systems_A_human_factors_approach/13433213.
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This study investigates the design processes used by IT designers, engineering firms, and business process developers; particularly those associated with high risk activities such as railway network control. Designers and end-users of technologies. devices. and business systems were surveyed and interviewed, and accident databases from around the world examined. The results from these three activities were analysed using a mixed methods approach. SPSS, N Vivo and Excel Analytical Tools were used to analyse the data.
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(10514360), Uttara Vinay Tipnis. "Data Science Approaches on Brain Connectivity: Communication Dynamics and Fingerprint Gradients." Thesis, 2021.
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The innovations in Magnetic Resonance Imaging (MRI) in the recent decades have given rise to large open-source datasets. MRI affords researchers the ability to look at both structure and function of the human brain. This dissertation will make use of one of these large open-source datasets, the Human Connectome Project (HCP), to study the structural and functional connectivity in the brain.
Communication processes within the human brain at different cognitive states are neither well understood nor completely characterized. We assess communication processes in the human connectome using ant colony-inspired cooperative learning algorithm, starting from a source with no a priori information about the network topology, and cooperatively searching for the target through a pheromone-inspired model. This framework relies on two parameters, namely pheromone and edge perception, to define the cognizance and subsequent behaviour of the ants on the network and the communication processes happening between source and target. Simulations with different configurations allow the identification of path-ensembles that are involved in the communication between node pairs. In order to assess the different communication regimes displayed on the simulations and their associations with functional connectivity, we introduce two network measurements, effective path-length and arrival rate. These measurements are tested as individual and combined descriptors of functional connectivity during different tasks. Finally, different communication regimes are found in different specialized functional networks. This framework may be used as a test-bed for different communication regimes on top of an underlying topology.
The assessment of brain fingerprints has emerged in the recent years as an important tool to study individual differences. Studies so far have mainly focused on connectivity fingerprints between different brain scans of the same individual. We extend the concept of brain connectivity fingerprints beyond test/retest and assess fingerprint gradients in young adults by developing an extension of the differential identifiability framework. To do so, we look at the similarity between not only the multiple scans of an individual (subject fingerprint), but also between the scans of monozygotic and dizygotic twins (twin fingerprint). We have carried out this analysis on the 8 fMRI conditions present in the Human Connectome Project -- Young Adult dataset, which we processed into functional connectomes (FCs) and time series parcellated according to the Schaefer Atlas scheme, which has multiple levels of resolution. Our differential identifiability results show that the fingerprint gradients based on genetic and environmental similarities are indeed present when comparing FCs for all parcellations and fMRI conditions. Importantly, only when assessing optimally reconstructed FCs, we fully uncover fingerprints present in higher resolution atlases. We also study the effect of scanning length on subject fingerprint of resting-state FCs to analyze the effect of scanning length and parcellation. In the pursuit of open science, we have also made available the processed and parcellated FCs and time series for all conditions for ~1200 subjects part of the HCP-YA dataset to the scientific community.
Lastly, we have estimated the effect of genetics and environment on the original and optimally reconstructed FC with an ACE model.
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(8082827), Kuang-Chung Wang. "METHOD DEVELOPMENT IN THE NEGF FRAMEWORK: MAXIMALLY LOCALIZED WANNIER FUNCTION AND BÜTTIKER PROBE FOR MULTI-PARTICLE INTERACTION." Thesis, 2019.
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The work involves two new method implementation and application in the Quantum transport community for nano-scale electronic devices.
First method: Ab-initio Tight-Binding(TB)
As the surfacing of novel 2D materials, layers can be stacked freely on top of each other bound by Van der Waals force with atomic precision. New devices created with unique characteristics will need the theoretical guidance. The empirical tight-binding method is known to have difficulty accurately representing Hamiltonian of the 2D materials. Maximally localized Wannier function(MLWF) constructed directly from ab-initio calculation is an efficient and accurate method for basis construction. Together with NEGF, device calculation can be conducted. The implementation of MLWF in NEMO5 and the application on 2D MOS structure to demystify interlayer coupling are addressed.
Second method: Büttiker-probe Recombination/Generation(RG) method:
The non-equilibrium Green function (NEGF) method is capable of nanodevice performance predictions including coherent and incoherent effects. To treat incoherent scattering, carrier generation and recombination is computationally very expensive. In this work, the numerically efficient Büttiker-probe model is expanded to cover recombination and generation effects in addition to various incoherent scattering processes. The capability of the new method to predict nanodevices is exemplified with quantum well III-N light-emitting diodes and photo-detector. Comparison is made with the state of art drift-diffusion method. Agreements are found to justify the method and disagreements are identified attributing to quantum effects.
The two menthod are individually developed and utilized together to study BP/MoS2 interface. In this vertical 2D device, anti-ambipolar(AAP) IV curve has been identified experimentally with different explanation in the current literature. An atomistic simulation is performed with basis generated from density functional theory. Recombination process is included and is able to explain the experiment findings and to provide insights into 2D interface devices.
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(6417014), Hung-Yi Lo. "Non-Gaussian Interference in High Frequency, Underwater Acoustic, and Molecular Communication." Thesis, 2019.
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The implications of non-Gaussian interference for various communication systemsare explored. The focus is on the Kappa distribution, Generalized Gaussian distribu-tions, and the distribution of the interference in molecular communication systems.A review of how dynamic systems that are not in equilibrium are modeled by theKappa distribution and how this distribution models interference in HF communica-tions systems at sunrise is provided. The channel model, bit error rate for single andmultiple antennas, channel capacity, and polar code performance are shown.Next, a review of the Generalized Gaussian distribution that has been found tomodel the interference resulting from surface activities is provided. This modeling isextended to find the secrecy capacity so that information cannot be obtained by theeavesdropper.
Finally, future nanomachnines are examined. The vulnerability to a receptorantagonist of a ligand-based molecule receiver is explored. These effects are consideredto be interference as in other wireless systems and the damage to signal reception isquantified.
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(10195706), Shreeya Sriram. "Electro - Quasistatic Body Communication for Biopotential Applications." Thesis, 2021.
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The current state of the art in biopotential recordings rely on radiative electromagnetic (EM) fields. In such transmissions, only a small fraction of this energy is received since the EM fields are widely radiated resulting in lossy inefficient systems. Using the body as a communication medium (similar to a ’wire’) allows for the containment of the energy within the body, yielding order(s) of magnitude lower energy than radiative EM communication. The first part of this work introduces Animal Body Communication for untethered rodent biopotential recording and for the first time this work develops the theory and models for animal body communication circuitry and channel loss. In vivo experimental analysis proves that ABC successfully transmits acquired electrocardiogram (EKG) signals through the body with correlation greater than 99% when compared to traditional wireless communication modalities, with a 50x reduction in power consumption. The second part of this work focusses on the analysis and design of an Electro-Quasistatic Human Body Communication (EQS-HBC) system for simultaneous sensing and transmission of biopotential signals. In this work, detailed analysis on the system level interaction between the sensing and transmitting circuitry is studied and a design to enable simultaneous sensing and transmission is proposed. Experimental analysis was performed to understand the interaction between the Right Leg-Drive circuitry and the HBC transmission along with the effect of the ADC quantization on signal quality. Finally, experimental trials proves that EKG signals can be transmitted through the body with greater than 96% correlation when compared to Bluetooth systems at extremely low powers.
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(8788169), Julia Bryan. "Effects of Movement on Biometric Facial Recognition in Body-Worn Cameras." Thesis, 2020.
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This study examined how three different manipulations of a single policing stance affected the quality scores and matching performance in a biometric facial recognition system; it was conducted in three phases. In the first phase, the researcher collected qualitative survey data from active, sworn law enforcement officers in 15 states. In the second phase, the researcher collected quantitative data using a single facial recognition subject and a static body-worn camera mounted to an adjustable tripod. In the third phase, the researcher collected quantitative data from body-worn camera-equipped law enforcement officers who filmed a stationary target as they executed a series of specified movements from the interview stance. The second phase tested two different body-worn cameras: one that is popular among law enforcement agencies in the United States, the Axon Body 2; and one that is inexpensive and available to the general public via a popular internet commerce website. The third phase tested only the Axon Body 2. Results of the study showed that matching results are poor in a biometric system where the test body-worn camera was the sensor, with error rates as high as 100% when the body-worn camera wearer was in motion. The general conclusion of this study is that a body-worn camera is not a suitable sensor for a biometric facial recognition system at this time, though advances in camera technology and biometric systems may close the gap in the future.
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(6622304), Juan S. Martinez. "Tactile Speech Communication: Design and Evaluation of Haptic Codes for Phonemes with Game-based Learning." Thesis, 2019.
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This thesis research was motivated by the need for increasing speech transmission rates through a phonemic-based tactile speech communication device named TAPS (TActile Phonemic Sleeve). The device consists of a 4-by-6 tactor array worn on
the forearm that delivers vibrotactile patterns corresponding to English phonemes. Three studies that proceeded this thesis evaluated a coding strategy that mapped 39 English phonemes into vibrotactile patterns. This thesis corresponds to a continuation of the project with improvements summarized in two parts. First, a design and implementation of a training framework based on theories of second language acquisition and game-based learning is developed. A role playing game named Haptos was designed to implement this framework. A pilot study using the first version of the game showed that two participants were able to master a list of 52 words within 45 minutes of game play. Second, an improved set of haptic codes was designed. The design was based on the statistics of spoken English and included an additional set of codes that abbreviate the most frequently co-occurring phonemes in duration. The new set included 39 English phonemes and 10 additional abbreviated symbols. The new codes represent a 24 to 46% increase in word presentation rates. A second version of the Haptos game was implemented to test the new 49 codes in a learning curriculum distributed over multiple days. Eight participants learned the new codes within 6 hours of training and obtained an average score of 84.44% in symbol identification tests with error rates per haptic symbol below 18%. The results demonstrate the feasibility of employing the new codes for future work where the ability to receive longer sequences of phonemes corresponding to phrases and sentences will be trained
and tested.
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(11186010), Jing Guo. "Making Wireless Communication More Efficient." Thesis, 2021.
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Given the increasing importance of mobile data access, extending broadband wireless access have become a global grand challenge. Wireless sensor networks (WSNs) and millimeter wave (mmWave) systems have been introduced to resolve these issues which motivate us to have further investigation. In this paper, the first two work assuming a quantized-and-forward WSN. We first develop a rate adaptive integer forcing source coding (RAIF) scheme to enhance the system throughput by assigning optimal quantization rate to each sensor optimally. Then, we are interested in developing an supervised online technique for solving classification problems. In order to enhance the classification performance, we developed this technique by jointly training the decision function that determines/estimates class label, quantizers across all sensors, and reliability of sensors such that M' most reliable sensors are enabled. Finally, we develop an idea to provide a folded low-resolution ADC array architecture that can utilize any of the widely published centralized folded ADC (FADC) implementation by placing the centralized FADC branches at different antenna elements in a millimeter wave (mmWave) system. With adding a simple analog shift and modulo operations prior to the sign quantizer, we show that the multiple low-resolution ADCs across the array elements can be properly designed such that they can be combined into an effective high-resolution ADC with excellent performance characteristics.
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(5930402), Justin C. Wirth. "Engineering Sensitivity: An Optical Optimization of Ring Resonator Arrays for Label-Free Whole Bacterial Sensing." Thesis, 2019.
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(5929799), Poolad Imany. "Quantum Frequency Combs and their Applications in Quantum Information Processing." Thesis, 2019.
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We experimentally demonstrate time-frequency entangled photons with comb-like spectra via both bulk optical crystals and on-chip microring resonators and explore their characterization in both time and frequency domain using quantum state manipulation techniques. Our characterization of these quantum frequency combs involves the use of unbalanced Mach-Zehnder interferometers and electro-optic modulators for manipulation in time- and frequency-domain, respectively. By creating indistinguishable superposition states using these techniques, we are able to interfere states from various time- and frequency-bins, consequently proving time- and frequency-bin en-tanglement. Furthermore, our time-domain manipulations reveal pair-wise continuous time-energy entanglement that spans multiple frequency bins, while our utilization of electro-optic modulators to verify high-dimensional frequency-bin entanglement constitutes the proof of this phenomenon for a spontaneous four-wave mixing pro-cess. By doing so, we show the potential of these quantum frequency combs for high-dimensional quantum computing with frequency-encoded quantum states, as well as fully secure quantum communications via quantum key distribution by per-forming a nonlocal dispersion cancellation experiment. To show the potential of our entangled photons source for encoding quantum information in the frequency domain, we carry out a frequency-domain Hong-Ou-Mandel interference experiment by implementing a frequency beam splitter. Lastly, we use the high-dimensionality of our time-frequency entangled source in both time and frequency domain to implement deterministic high-dimensional controlled quantum gates, with the quantum information encoded in both the time and frequency degrees of freedom of a single photon. This novel demonstration of deterministic high-dimensional quantum gates paves the way for scalable optical quantum computation, as quantum circuits can be implemented with fewer resources and high success probability using this scheme.
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(10214267), Chih-Hua Chang. "Optimal Network Coding Under Some Less-Restrictive Network Models." Thesis, 2021.
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Network Coding is a critical technique when designing next-generation network systems, since the use of network coding can significantly improve the throughput and performance (delay/reliability) of the system. In the traditional design paradigm without network coding, different information flows are transported in a similar way like commodity flows such that the flows are kept separated while being forwarded in the network. However, network coding allows nodes in the network to not only forward the packet but also process the incoming information messages with the goal of either improving the throughput, reducing delay, or increasing the reliability. Specifically, network coding is a critical tool when designing absolute Shannon-capacity-achieving schemes for various broadcasting and multi-casting applications. In this thesis, we study the optimal network schemes for some applications with less restrictive network models. A common component of the models/approaches is how to use network coding to take advantage of a broadcast communication channel.In the first part of the thesis, we consider the system of one server transmitting K information flows, one for each of K users (destinations), through a broadcast packet erasure channels with ACK/NACK. The capacity region of 1-to-K broadcast packet erasure channels with ACK/NACK is known for some scenarios, e.g., K<=3, etc. However, existing achievability schemes with network coding either require knowing the target rate in advance, and/or have a complicated description of the achievable rate region that is difficult to prove whether it matches the capacity or not. In this part, we propose a new network coding protocol with the following features: (i) Its achievable rate region is identical to the capacity region for all the scenarios in which the capacity is known; (ii) Its achievable rate region is much more tractable and has been used to derive new capacity rate vectors; (iii) It employs sequential encoding that naturally handles dynamic packet arrivals; (iv) It automatically adapts to unknown packet arrival rates; (v) It is based on GF(q) with q>=K. Numerically, for K=4, it admits an average control overhead 1.1% (assuming each packet has 1000 bytes), average encoding memory usage 48.5 packets, and average per-packet delay 513.6 time slots, when operating at 95% of the capacity.
In the second part, we focus on the coded caching system of one server and K users, each user k has cache memory size Mk and demand a file among the N files currently stored at server. The coded caching system consists of two phases: Phase 1, the placement phase: Each user accesses the N files and fills its cache memory during off-peak hours; and Phase 2, the delivery phase: During the peak hours, each user submits his/her own file request and the server broadcasts a set of packet simultaneously to K users with the goal of successfully delivering the desired packets to each user. Due to the high complexity of coded caching problem with heterogeneous file size and heterogeneous cache memory size for arbitrary N and K, prior works focus on solving the optimal worst-case rate with homogeneous file size and mostly focus on designing order-optimal coded caching schemes with user-homogeneous file popularity that attain the lower bound within a constant factor. In this part, we derive the average rate capacity for microscopic 2-user/2-file (N=K=2) coded caching problem with heterogeneous files size, cache memory size, and user-dependent heterogeneous file popularity. The study will shed some further insights on the complexity and optimal scheme design of general coded caching problem with full heterogeneity.
In the third part, we further study the coded caching system of one server, K= 2 users, and N>=2 files and focus on the user-dependent file popularity of the two users. In order to approach the exactly optimal uniform average rate of the system, we simplify the file demand popularity to binary outputs, i.e., each user either has no interest (with probability 0) or positive uniform interest (with a constant probability) to each of the N file. Under this model, the file popularity of each user is characterized by his/her file demand set of positive interest in the N files. Specifically, we analyze the case of two user (K=2). We show the exact capacity results of one overlapped file of the two file demand sets for arbitrary N and two overlapped files of the two file demand sets for N = 3. To investigate the performance of large overlapped files we also present the average rate capacity under the constraint of selfish and uncoded prefetching with explicit prefetching schemes that achieve those capacities. All the results allow for arbitrary (and not necessarily identical) users' cache capacities and number of files in each file demand set.
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(11184744), Vinayak Suresh. "BINARY FEEDBACK IN COMMUNICATION SYSTEMS: BEAM ALIGNMENT, ADVERSARIES AND ENCODING." Thesis, 2021.
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The availability of feedback from the receiver to the transmitter in a communication system can play a significant role. In this dissertation, our focus is specifically on binary or one-bit feedback. First, we study the problem of successive beam alignment for millimeter-wave channels where the receiver sends back only one-bit of information per beam sounding. The sparse nature of the channel allows us to interpret channel sounding as a form of questioning. By posing the alignment problem as a questioning strategy, we describe adaptive (closed-loop) and non-adaptive (open-loop) channel sounding techniques which are robust to erroneous feedback signals caused by noisy quantization. In the second part, we tightly characterize the capacity for two binary stochastic-adversarial mixed noise channels. Specifically, the transmitter (Alice) intends to convey a message to the receiver (Bob) over a binary symmetric channel (BSC) or a binary erasure channel (BEC) in the presence of an adversary (Calvin) who injects additional noise at the channel's input subject to a budget constraint. Calvin is online or causal in that at any point during the transmission, he can infer the bits being sent by Alice and those being received by Bob via a feedback link. Finally in the third part, we study the applicability of binary feedback for encoding and propose the framework of linearly adapting block feedback codes. We also prove a new result for Reed-Muller (RM) codes to demonstrate how an uncoded system can mimic a RM code under this framework, against remarkably large feedback delays.
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(11251179), Abdullah Al Noman. "Fabrication and Characterization of Silicon Photonic Devices." Thesis, 2021.
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Silicon photonics has become one of the leading candidates for the next generation optical communication platform. In addition to being an inexpensive material and compatible with Complementary metal–oxide–semiconductor (CMOS) manufacturing, silicon exhibits low absorption at optical telecommunication bands. However, high propagation loss and poor light confinement in narrow Si waveguides have limited high-density optical integration.In this work, we show the fabrication and characterization of a novel type of devices named E-skid devices that can reduce the skin depth and suppress the large spatial content of evanescent light. These devices use artificial anisotropic dielectric metamaterial to suppress the evanescent waves. Beside E-skid devices, we also discuss the fabrication and experimental characterization of mode filters using Silicon on Insulator that can block the fundamental TE0 and allow the higher order modes to pass through using Multi Mode Interference.
In this work, the mode is filtered using radiation, not by reflection.
Beside Silicon, Silicon Nitride has also gained much interest because of its low loss, smaller nonlinear absorption and higher Kerr effect. Silicon Nitride waveguides have widely
been used for lots of applications specially the optical frequency comb generation. One special case of coherent optical frequency comb is Soliton in which case the non-linearity and dispersion cancel each other’s effect and keep the pulse without distortion. In this work, we described the Silicon Nitride fabrication process and did a comparative analysis with other research groups who fabricates similar devices. We tried to improve our process by inserting a few additional steps in our fabrication process. We also investigated our process step by step and found out reasons for our low quality factor and low yield. We found a few factors that might be responsible for the low quality factor and addressed them. We fabricated real devices using our modified process and saw improvement in quality factors, yield and thermal performance of the devices.
Finally, we describe an edge polishing method for Silicon Nitride microring resonator devices, which we developed from scratch and we can polish edges down to sub-micron level. Thus, the edges become optically flat and it allowed us to do heterogeneous integration with an Indium Phosphide chip. This paves away for some exciting opportunities like on-chip frequency comb generation.
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Mastilovich, Nikola. "Automatisation of programming of a PLC code : a thesis presented in partial fulfilment of the requirements of the degree of Masters of Engineering in Mechatronics." 2010. http://hdl.handle.net/10179/1681.
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Appendix D, CD content can be found with print thesis held at Turitea library, Palmerston North. Content: Empty APCG program Empty RSLogix5000 l5k file Empty RSLogix5000 ACD file Real Life project - APCG program (only partial) Real Life project - RSLogix5000 l5k file (only partial) Real Life project - RSLogix5000 ACD file (only partial)A competitive edge is one of the requirements of a successful business. Tools, which increase an engineer s productivity and minimize cost, can be considered as a competitive edge. The objective of this thesis was to design, create, and implement Automatic PLC Code Generator (APCG) software. A secondary objective was to demonstrate that the use of the APCG software will lead to improved project efficiency and enhanced profit margin. To create the APCG software, the MS Excel and Visual Basic for Applications (VBA) programs were used as the platform. MS Excel sheets were used as a user interface, while VBA creates the PLC code from the information entered by the engineer. The PLC code, created by the APCG software, follows the PLC structure of the Realcold Milmech Pty. Ltd, as well as the research Automatic generation of PLC code beyond the nominal sequence written by Guttel et al [1]. The APCG software was used to design and create a PLC code for one of the projects undertaken by Realcold Milmech Pty. Ltd. By using APCG software, time to design, create, and test the PLC code was improved when compared to the budgeted time. In addition, the project's profit margin was increased. Based on the results of this thesis it is expected that the APCG software will be useful for programmers that tend to handle a variety of projects on a regular basis, where programming in a modular way is not appropriate.
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Nguyen, Dang Khoa. "Adaptive transmission for block-fading channels." 2010. http://arrow.unisa.edu.au:8081/1959.8/96822.
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Multipath propagation and mobility in wireless communication systems give rise to variations in the amplitude and phase of the transmitted signal, commonly referred to as fading. Many wireless applications are affected by slowly varying fading, where the channel is non-ergodic, leading to non-reliable transmission during bad channel realizations. These communication scenarios are well modeled by the block-fading channel, where the reliability is quantatively characterized by the outage probability. This thesis focuses on the analysis and design of adaptive transmission schemes to improve the outage performance of both single- and multiple-antenna transmission over the block-fading channel, especially for the cases where discrete input constellations are used. Firstly, a new lower bound on the outage probability of non-adaptive transmission is proposed, providing an efficient tool for evaluating the performance of non-adaptive transmission. The lower bound, together with its asymptotic analysis, is essential for efficiently designing the adaptive transmission schemes considered in the thesis. Secondly, new power allocation rules are derived to minimize the outage probability of fixed-rate transmission over block-fading channels. Asymptotic outage analysis for the resulting schemes is performed, revealing important system design criteria. Furthermore, the thesis proposes novel suboptimal power allocation rules, which enjoy low-complexity while suffering minimal losses as compared to the optimal solution. Thus, these schemes facilitate power adaptation in low-cost devices. Thirdly, the thesis considers incremental-redundancy automatic-repeat-request (INR-ARQ) strategies, which perform adaptive transmission based on receiver feedback. In particular, the thesis concentrates on multi-bit feedback, which has been shown to yield significant gains in performance compared to conventional single-bit ARQ schemes. The thesis proposes a new information-theoretic framework for multi-bit feedback INR-ARQ, whereby the receiver feeds back a quantized version of the accumulated mutual information. Within this framework, the thesis presents an asymptotic analysis which yields the large gains in outage performance offered by multi-bit feedback. Furthermore, the thesis proposes practical design rules, which further illustrates the benefits of multi-bit feedback in INR-ARQ systems. In short, the thesis studies the outage performance of transmission over block-fading channels. Outage analysis is performed for non-adaptive and adaptive transmission. Improvements for the existing adaptive schemes are also proposed, leading to either lower complexity requirements or better outage performance. Still, further research is needed to bring the benefits offered by adaptive transmission into practical systems.Thesis (PhD)--University of South Australia, 2010
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(10723737), Navin Bhartoor Lingaraju. "Spectral Multiplexing and Information Processing for Quantum Networks." Thesis, 2021.
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Modern fiber-optic networks leverage massive parallelization of communications channels in the spectral domain, as well as low-noise recovery of optical signals, to achieve high rates of information transfer. However, quantum information imposes additional constraints on optical transport networks – the no-cloning theorem forbids use of signal regeneration and many network protocols are premised on operations like Bell state measurements that prize spectral indistinguishability. Consequently, a key challenge for quantum networks is identifying a path to high-rate and high-fidelity quantum state transport.To bridge this gap between the capabilities of classical and quantum networks, we developed techniques that harness spectral multiplexing of quantum channels, as well as that support frequency encoding. In relation to the former, we demonstrated reconfigurable connectivity over arbitrary subgraphs in a multi-user quantum network. In particular, through flexible provisioning of the pair source bandwidth, we adjusted the rate at which entanglement was distributed over any user-to-user link. To facilitate networking protocols compatible with both spectral multiplexing and frequency encoding, we synthesized a Bell state analyzer based on mixing outcomes that populate different spectral modes, in contrast to conventional approaches that are based on mixing outcomes that populate different spatial paths. This advance breaks the tradeoff between the fidelity of remote entanglement and the spectral distinguishability of photons participating in a joint measurement.
Finally, we take steps toward field deployment by developing photonic integrated circuits to migrate the aforementioned functionality to a chip-scale platform while also achieving the low loss transmission and high-fidelity operation needed for practical quantum networks.
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(8815964), Minsuk Koo. "Energy Efficient Neuromorphic Computing: Circuits, Interconnects and Architecture." Thesis, 2020.
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Neuromorphic computing has gained tremendous interest because of its ability to overcome the limitations of traditional signal processing algorithms in data intensive applications such as image recognition, video analytics, or language translation. The new computing paradigm is built with the goal of achieving high energy efficiency, comparable to biological systems.
To achieve such energy efficiency, there is a need to explore new neuro-mimetic devices, circuits, and architecture, along with new learning algorithms. To that effect, we propose two main approaches:
First, we explore an energy-efficient hardware implementation of a bio-plausible Spiking Neural Network (SNN). The key highlights of our proposed system for SNNs are 1) addressing connectivity issues arising from Network On Chip (NOC)-based SNNs, and 2) proposing stochastic CMOS binary SNNs using biased random number generator (BRNG). On-chip Power Line Communication (PLC) is proposed to address the connectivity issues in NOC-based SNNs. PLC can use the on-chip power lines augmented with low-overhead receiver and transmitter to communicate data between neurons that are spatially far apart. We also propose a CMOS 'stochastic-bit' with on-chip stochastic Spike Timing Dependent Plasticity (sSTDP) based learning for memory-compressed binary SNNs. A chip was fabricated in 90 nm CMOS process to demonstrate memory-efficient reconfigurable on-chip learning using sSTDP training.
Second, we explored coupled oscillatory systems for distance computation and convolution operation. Recent research on nano-oscillators has shown the possibility of using coupled oscillator networks as a core computing primitive for analog/non-Boolean computations. Spin-torque oscillator (STO) can be an attractive candidate for such oscillators because it is CMOS compatible, highly integratable, scalable, and frequency/phase tunable. Based on these promising features, we propose a new coupled-oscillator based architecture for hybrid spintronic/CMOS hardware that computes multi-dimensional norm. The hybrid system composed of an array of four injection-locked STOs and a CMOS detector is experimentally demonstrated. Energy and scaling analysis shows that the proposed STO-based coupled oscillatory system has higher energy efficiency compared to the CMOS-based system, and an order of magnitude faster computation speed in distance computation for high dimensional input vectors.
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(9828620), Md Mustafizur Rahman. "Design and development of digital smart meter network for distribution system." Thesis, 2011. https://figshare.com/articles/thesis/Design_and_development_of_digital_smart_meter_network_for_distribution_system/13465598.
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"The main objective of this study is to design and develop smart meter network to investigate the requirements of an efficient and reliable smart meter network. Research on smart meter network is limited and there is an increased demand for further research in this area since distribution network needs to uptake of green-house friendly technology and provide consumers better access to manage and control their power consumption. Furthermore, an effective integration of renewable energy sources with the distribution network will require smart meter network"--Abstract.
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(9530630), Akshay Jajoo. "EXPLOITING THE SPATIAL DIMENSION OF BIG DATA JOBS FOR EFFICIENT CLUSTER JOB SCHEDULING." Thesis, 2020.
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With the growing business impact of distributed big data analytics jobs, it has become crucial to optimize their execution and resource consumption. In most cases, such jobs consist of multiple sub-entities called tasks and are executed online in a large shared distributed computing system. The ability to accurately estimate runtime properties and coordinate execution of sub-entities of a job allows a scheduler to efficiently schedule jobs for optimal scheduling. This thesis presents the first study that highlights spatial dimension, an inherent property of distributed jobs, and underscores its importance in efficient cluster job scheduling. We develop two new classes of spatial dimension based algorithms toaddress the two primary challenges of cluster scheduling. First, we propose, validate, and design two complete systems that employ learning algorithms exploiting spatial dimension. We demonstrate high similarity in runtime properties between sub-entities of the same job by detailed trace analysis on four different industrial cluster traces. We identify design challenges and propose principles for a sampling based learning system for two examples, first for a coflow scheduler, and second for a cluster job scheduler.
We also propose, design, and demonstrate the effectiveness of new multi-task scheduling algorithms based on effective synchronization across the spatial dimension. We underline and validate by experimental analysis the importance of synchronization between sub-entities (flows, tasks) of a distributed entity (coflow, data analytics jobs) for its efficient execution. We also highlight that by not considering sibling sub-entities when scheduling something it may also lead to sub-optimal overall cluster performance. We propose, design, and implement a full coflow scheduler based on these assertions.
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(13978926), Kirsten M. Vanstone. "The evolution of planetarium shows: A case study in oral science presentations for the public." Thesis, 2005. https://figshare.com/articles/thesis/The_evolution_of_planetarium_shows_A_case_study_in_oral_science_presentations_for_the_public/21357885.
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Science presentations for the public in the form of planetarium shows were investigated to track their evolution in terms of length and language, visuals and visual change, the application of learning theory, and tone. Scripts were entered into a word processor and subjected to a readability analysis. Counts of visual change in the shows were tracked and analysed. Concepts presented in the shows were analysed in terms of learning theory. From this information and other aspects of the scripts, the tone of the shows was described. Results indicate that shows have evolved to become more scientifically based, using more complex language and realistic visuals. Visuals are shown to carry more of the burden of communication in modern shows. Modern shows are also more participatory and inclusive, using some, but not all aspects of modern learning theory. This evolution is shown to better appeal to the profile of a typical visitor to a modern science venue.
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(10701084), James Lawrence Stewart. "Designing Optical Metastructures for IR Sensing, Discernment and Signature Reduction." Thesis, 2021.
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Increasing flexibility of light manipulation is vital for various domains including both biomedical and military applications, where a lack of photon control could become critical. The efforts conducted and projected within this proposal are focused on three major areas: semi-continuous planar thin film photomodification for infrared (IR) filtering, nanosphere core-shell structures for obscurance, and all-dielectric sub-wavelength focal lenses for advanced IR sensing.Through a collaborative effort with the Army Research Office, we advanced the tunability of planar plasmonic filters with cutoff wavelengths in the 10–16μm range with photomodification using a 10.6μm CO2laser. Surface-enhanced molecular absorption in concert with three-dimensional (3D) Au nano-structures with inherent broad absorption in the IR band was a novel approach utilized to create such planar filters.Expanding on these, efforts and the results of the 2-dimensional (2D) semicontinuous Au plasmonic planar filtering, we further advanced our research with 3D Au nano-coreshell structures to enable levitated long-wavelength pass filter obscurants. We exploited the radiative effects of Au nano-structures that mimic conventional apertures or antennas, though these structures are on the nanometer scale and demonstrated the filtering characteristics through flow cell.In parallel with our plasmonic filtering we designed, manufactured and tested low loss dielectric microlenses for IR radiation based on a dielectric metasurface layer by patterning a SI substrate and etching to sub-micron depths. For a proof-of-concept lens demonstration,we chose a fine patterned array of nano-pillars with variable diameters.Merging our plasmonic filtering and dielectric microlens efforts, we created a holographic lenslet by designing and simulating a low loss focusing metasurface lens with engineered nano-scaled features to converge off-axis IR radiation. An array of nano-pillars with varied diameter and fixed height and periodicity was chosen for ease of fabrication with single layer etching
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Ashraf, Manzur. "Channel based medium access control for ad hoc wireless networks." 2009. http://arrow.unisa.edu.au:8081/1959.8/92176.
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Opportunistic communication techniques have shown to provide significant performance improvements in centralised random access wireless networks. The key mechanism of opportunistic communication is to send back-to-back data packets whenever the channel quality is deemed "good". Recently there have been attempts to introduce opportunistic communication techniques in distributed wireless networks such as wireless ad hoc networks. In line of this research, we propose a new paradigm of medium access control, called Channel MAC based on the channel randomness and opportunistic communication principles. Scheduling in Channel MAC depends on the instance at which the channel quality improves beyond a threshold, while neighbouring nodes are deemed to be silent. Once a node starts transmitting, it will keep transmitting until the channel becomes "bad". We derive an analytical throughput equation of the proposed MAC in a multiple access environment and validate it by simulations. It is observed that Channel MAC outperforms IEEE 802.11 for all probabilities of good channel condition and all numbers of nodes. For higher number of nodes, Channel MAC achieves higher throughput at lower probabilities of good channel condition increasing the operating range. Furthermore, the total throughput of the network grows with increasing number of nodes considering negligible propagation delay in the network. A scalable channel prediction scheme is required to implement the practical Channel MAC protocol in practice. We propose a mean-value based channel prediction scheme, which provides prediction with enough accuracy to be used in the Channel MAC protocol. NS2 simulation result shows that the Channel MAC protocol outperforms the IEEE 802.11 in throughput due to its channel diversity mechanism in spite of the prediction errors and packet collisions. Next, we extend the Channel MAC protocol to support multi-rate communications. At present, two prominent multi-rate mechanisms, Opportunistic Auto Rate (OAR) and Receiver Based Auto Rate (RBAR) are unable to adapt to short term changes in channel conditions during transmission as well as to use optimum power and throughput during packet transmissions. On the other hand, using channel predictions, each source-destinations pair in Channel MAC can fully utilise the non-fade durations. We combine the scheduling of Channel MAC and the rate adaptive transmission based on the channel state information to design the 'Rate Adaptive Channel MAC' protocol. However, to implement the Rate adaptive Channel MAC, we need to use a channel prediction scheme to identify transmission opportunities as well as auto rate adaptation mechanism to select rates and number of packets to transmit during those times. For channel prediction, we apply the scheme proposed for the practical implementation of Channel MAC. We propose a "safety margin" based technique to provide auto rate adaptation. Simulation results show that a significant performance improvement can be achieved by Rate adaptive Channel MAC as compared to existing rate adaptive protocols such as OAR.
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(7046372), Shovan Maity. "Electro-Quasistatic Human Body Communication: From Bio-Physical Modeling to Broadband Circuits and HCI Applications." Thesis, 2019.
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Decades of scaling in semiconductor technology has resulted in a drastic reduction in the cost and size of unit computing. This has enabled computing capabilities in small form factor wearable and implantable devices. These devices communicate with each other to form a network around the body, commonly known as the Wireless Body Area Network (WBAN). Radio wave transmission over air is the commonly used method of communication among these devices. However, the human body can be used as the communication medium by utilizing its electrical conductivity property. This has given rise to Human Body Communication (HBC), which provides higher energy efficiency and enhanced security compared to over the air radio wave communication enabling applications like remote health monitoring, secure authentication. In this thesis we characterize the human body channel characteristics at low frequencies, utilize the insight obtained from the channel characterization to build high energy-efficiency, interference-robust circuits and demonstrate the security and selectivity aspect of HBC through a Common Off the Shelf (COTS) component-based system. First, we characterize the response of the human body channel in the 10KHz1MHz frequency range with wearable transmitter/ receiver to study the feasibility of using it as a broadband communication channel. Voltage mode measurements with capacitive termination show almost at-band response in this frequency range, establishing the body as a broadband channel. The body channel response is also measured across different interaction scenario between two wearable devices and a wearable and a computer. A bio-physical model of the HBC channel is developed to explain the measurement results and the wide discrepancies found in previous studies.We analyze the safety aspect of different type of HBC by carrying out theoretical circuit and FEM based simulations. A study is carried out among multiple subjects to assess the effect of HBC on the vital parameters of a subject. A statistical analysis of the results shows no signicant change in the vital parameters before and during HBC transmission, validating the theoretical simulations showing >!000x safety margin compared to the established ICNIRP guidelines. Next, an HBC transceiver is built utilizing the wire-like, broadband human body channel to enable high energy efficiency. The transceiver also provides robustness to ambient interference picked up by the human body through integration followed by periodic sampling. The transceiver achieves 6.3pJ/bit energy effciency while operating at a maximum data rate of 30Mbps, while providing -30dB interference tolerant operation. Finally, a COTS based HBC prototype is developed, which utilizes low frequency operation to enable selective and physically secure communication strictly during touch for Human Computer Interaction (HCI) between two wearable devices for the rst time. A thorough study of the effect of different parameters such as environment, posture, subject variation, on the channel loss has also been characterized to build a robust HBC system working across different use cases. Applications such as secure authentication (e.g. opening a door, pairing a smart device) and information exchange (e.g. payment, image, medical data, personal profile transfer) through touch is demonstrated to show the impact of HBC in enabling new human-machine interaction modalities.
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(5930396), Jack D. Williams. "Magnetically-Coupled Circuits Systems for Wireless Excitation of Passive Stimulators for Stimulation Therapies and Application as a Treatment for Glaucoma." Thesis, 2019.
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The practice of delivering an electrical current waveform to an excitable tissue such as a structure in the brain, nerve fiber, or muscle to relieve the symptoms of disease constitutes an electrical stimulation therapy. Electrical stimulation therapies supported by implantable devices provide effective treatment options for people suffering from treatment-resistant chronic diseases that often fail to respond to medication and other traditional therapies [1, 2]. However, implantable electrical stimulators traditionally approved by the Food and Drug Administration (FDA) use implanted batteries that require surgical replacement over years of operation and limit therapies to applications with minimal constraints on implant mass, volume, and rigidity [3, 4]. Previous works have proposed to eliminate batteries in implantable stimulators by using magnetically-coupled coils to deliver energy through radio-frequency (RF) fields, exciting alternating currents on implantable devices to be converted into stimulus pulses by rectifiers [5, 6]. Implantable stimulators without batteries may be excited by an alternative theory of operation without the use of RF fields that eliminates the need for a rectifier and permits stimulators with minimal complexity.
This work proposes an original use of magnetically-coupled circuits theory for the wireless excitation of electrical stimulation current waveforms on passive stimulators that eliminates the need for an implanted battery. The principle of the technique is to drive stimulation current waveforms on passive stimulators with electromotive forces excited by applied time-varying magnetic fields via the phenomena described by Faraday’s law of induction [7-9]. The proposed systems require a wearable driving component and a passive driven component that may either be worn or implanted. The wearable driving component must include a battery, pulse-generating circuitry, and a primary coil, whereas the driven component is a passive device requiring only a secondary coil with electrodes to contact tissue. The pulse-generating circuitry of the driving component may be implemented readily such that the design of the coils defines the challenge in the implementation of the proposed systems. The design of the coils for the proposed systems presents the potential for a nontrivial optimization problem with conflicting objectives; possible objectives for the design of the coils include maximizing the attainable peak amplitudes of the stimulation currents, obtaining various characteristics of a desired stimulation current waveform, and minimizing the variation of the stimulation currents with varying displacements between the coils. The problem posed by the design of the coils for the proposed systems is addressed by direction obtained from theoretical analyses and experiments performed in this work that supplement direction from the literature [5, 10-12]. The potential utility of the proposed theory of operation is demonstrated by enabling the first chronic electrical stimulation therapy for glaucoma, the leading cause of irreversible blindness worldwide. The system designed for the glaucoma stimulation therapy and the methods used to quantify its electrical performance are presented along with data from experimental therapeutic trials with human participants.
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(5930270), Mehdi Shishehbor. "Numerical Investigation on the Mechanical Properties of Neat Cellulose Nanocrystal." Thesis, 2020.
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Nature has evolved efficient strategies to make materials with hierarchical internal structure that often exhibit exceptional mechanical properties. One such example is found in cellulose, which has achieved a high order of functionality and mechanical properties through a hierarchical structure with an exceptional control from the atomic level all the way to the macroscopic level. Cellulose is present in a wide variety of living species (trees, plants, algae, bacteria, tunicates), and provides the base reinforcement structure used by organisms for high mechanical strength, high strength-to-weight ratio, and high toughness. Additionally, being the most abundant organic substance on earth, cellulose has been used by our society as an engineering material for thousands of years, and are prolific within our society, as demonstrated by the enormity of the world-wide industries in cellulose derivatives, paper/packaging, textiles, and forest products.
More recently, a new class of cellulose base particles are being extracted from plants/trees, cellulose nanocrystals (CNCs), which are spindle-shaped nano-sized particles (3 ̶ 20 nm in width and 50 ̶ 500 nm in length) that are distinct from the more traditional cellulose materials currently used (e.g. molecular cellulose and wood pulp). They offer a new combination of particle morphology, properties and chemical functionalities that enable CNCs for use in applications that were once thought impossible for cellulosic materials.
CNCs have shown utility in many engineering applications, for example, biomedical, nanocomposites, barrier/separation membranes and cementitious materials. To gain greater insight as to how best use CNCs in various engineering application areas, a comprehensive understanding of the mechanics of CNCs is needed. The characterization of the mechanical properties of nanomaterials via experimental testing has always been challenging due to their small size, resulting in large uncertainties related to testing near sensitivity limits of a given technique, the same is true when characterizing CNCs. For CNCs, to help offset limitations in experimental testing, numerical modeling has been useful in predicting the mechanical properties of CNCs. We present a continuum-based structural model to study the mechanical behavior of cellulose nanocrystals (CNCs), and analyze the effect of bonded and non-bonded interactions on the mechanical properties under various loading conditions. In particular, this model assumes the uncoupling between the bonded and nonbonded interactions and their behavior is obtained from atomistic simulations.
For large deformations and when there is interaction and dynamics of many particles involved, continuum models could become as expensive as MD simulations. In addition, it has been shown that traditional material models in the continuum mechanics context, cannot model all the mechanical properties of CNC, especially for large deformation. To overcome these setbacks and to be able to model real size of CNC, 50-1000 nm, and/or to increase the number of particles involved in the simulation, a so called ‘‘coarse-grained’’ (CG) model for mechanical and interfacial properties of CNC is proposed. The proposed CG model is based on both mechanical properties and crystal-crystal interactions. Parametrization of the model is carried out in comparison with all-atom (AA) molecular dynamics and experimental results of some specific mechanical and interfacial tests.
Subsequently, verification is done with other tests. Finally, we analyze the effect of interface properties on the mechanical performance of CNC-based materials including, bending of a CNC bundle, tensile load and fracture in bioinspired structure of CNCs such as staggered brick-and-mortar and Bouligand structures of interest.
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(13753927), S. Vijay Sundhar. "Endurance limit determination in porous materials." Thesis, 1992. https://figshare.com/articles/thesis/Endurance_limit_determination_in_porous_materials/21047392.
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The theory describing the fatigue mechanism in elasto-plastic material containing pores or inclusions has been developed. An attempt at quantitative determination of the effect of endurance limit reduction by analysis of sizes of plastic zones formed near the inclusions, and their cracking has been -done. The geometrical configuration, consisting of round, horizontal, vertical and angular elliptical inclusions from which a nucleating crack emerged, was considered, and the stress intensity factory of such configurations was analysed. Based on threshold value of 6K below which crack propagation ceases, the critical value of loading stress was determined. Finite element technique was used to obtain theoretical results. A source code developed by Owen and Hinton for solving elastoplastic applications using finite element concept was used for solving the problem. Experimental analysis was done using photoelasticity method. Theoretical results were compared with results from experiments, showing quite good agreement.
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(7013471), NIRANJAN RAVI. "Integration of UAVS with Real Time Operating Systems and Establishing a Secure Data Transmission." Thesis, 2019.
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In today’s world, the applications of Unmanned Aerial Vehicle (UAV) systems
are leaping by extending their scope from military applications on to commercial and
medical sectors as well. Owing to this commercialization, the need to append external
hardware with UAV systems becomes inevitable. This external hardware could aid in
enabling wireless data transfer between the UAV system and remote Wireless Sensor
Networks (WSN) using low powered architecture like Thread, BLE (Bluetooth Low
Energy). The data is being transmitted from the flight controller to the ground
control station using a MAVlink (Micro Air Vehicle Link) protocol. But this radio
transmission method is not secure, which may lead to data leakage problems. The
ideal aim of this research is to address the issues of integrating different hardware with
the flight controller of the UAV system using a light-weight protocol called UAVCAN
(Unmanned Aerial Vehicle Controller Area Network). This would result in reduced
wiring and would harness the problem of integrating multiple systems to UAV. At
the same time, data security is addressed by deploying an encryption chip into the
UAV system to encrypt the data transfer using ECC (Elliptic curve cryptography)
and transmitting it to cloud platforms instead of radio transmission.
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(11186220), Julianna Gesun. "Beyond Surviving: Developing and Testing a Model of Thriving for Engineering Students." Thesis, 2021.
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The goal of my dissertation is to take a step toward shifting the narrative in engineering from “surviving” to “thriving” so that more engineering students can reach their full potential in college and beyond. Many engineering students experience barriers such as the hardships of engineering culture, which are exacerbated for women and underrepresented racial/ethnic minorities(such as Black, Latinx, and Indigenous students). These barriers are well documented in research and well discussed in interventions to support engineering student success, under the assumption that helping students cope with these cultural and systemic barriers will, by itself, lead to their success. My research on engineering thriving challenges this assumption by asserting that the skills engineering students need to succeed academically, socially, and personally differ from the skills they need to “survive” cultural and systemic barriers.This dissertation employs an exploratory multiphase research design, with three studies, to develop a model of thriving for undergraduate engineering students. The first study consists of a scoping literature review of 68 papers to define and characterize engineering thriving as the process in which engineering students develop and refine competencies that allow them to function optimally in engineering programs. From this definition, the second study employs a Delphi process with 47 experts to develop a model of engineering thriving that includes 1) internal thriving competencies; 2) external thriving outcomes; 3) engineering culture, systemic factors, resources, context and situation; and 4) how these three broader categories function together. The third study tests some of these relationships proposed in the model of engineering thriving using structural equation modeling(SEM) on a large dataset of responses by over 2,000 undergraduate U.S. engineering students to a survey that measured various constructs associated with thriving. Findings from the SEM analysis suggest that gratitude was one of the most important competencies for engineering student thriving, and that a holistic model approach accounted for 79% of the variance in engineering students’ belongingness and 25% of the variance in perceptions of faculty caring(two external thriving outcomes).
Understanding and supporting more engineering thriving has positive implications for students, recruitment and outreach, and engineering programs. Thriving is multidimensional and, thus, supporting engineering students to achieve traditional success metrics (such as academic performance and graduation) goes hand in hand with supporting their personal and social development and wellbeing. Recruitment and outreach of K-12 students can benefit from viewing engineering as an attractive and inspirational career, combating negative stereotypes that currently deter students from pursuing engineering. Engineering programs can benefit from developing a reputation and culture of thriving. However, cultural change requires the collective investment from all members of the engineering community.
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(10716507), Alexis Margaret Corda. "Advancements of a Silicon-on-Insulator Thermoelectric Sensor for Biomedical Applications." Thesis, 2021.
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Heat can be used as a reliable biomarker of cell metabolism. Assessing changes in metabolic activity is useful to study normal bioactivity or factors which may stimulate or inhibit cell proliferation. Methods which measure the heat of cell metabolism over time must be sensitive to the small changes. Thermoelectric sensors, which work by the Seebeck effect, are one method which has shown adequate sensitivity. This type of sensor directly converts heat energy into electrical energy without the use of a power source. Current research into sensors for cell metabolism may list lengthy, complex, and expensive procedures or include materials with rare or toxic elements. This work establishes a design approach of a silicon-based thermoelectric sensor for cell metabolism measurement which incorporates abundant and non-toxic materials and a simple procedure based on standard MEMS fabrication methods. The foundation for the sensor design is discussed. Fabrication was done using optical lithography, reactive ion etching, and electron beam evaporation which are standard and well known in industry. Sensor quality was characterized successfully based on the defined design parameters. Preliminary data has been recorded on the Coli cell metabolism. Finally, recommendations to improve heat insulation, include sensor calibration, and optimize manufacturing parameters are given for future work on this design to advance sensitivity and commercial potential.