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1
Cohen, Nathan M. "DC Dielectrophoretic Assisted Anti-Fouling Filtration System." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/694.
Повний текст джерелаАнотація:
Filtration processes, whether on the microfluidic, clinical treatment systems, or industrial scale (e.g., point-of-care diagnostics, dialysis, and biopharmaceutical manufacturing, respectively), are often inseparable from membrane clogging (fouling). As a consequence, most, if not all, filtration systems require frequent maintenance to maintain functionality and efficiency. The thesis of this project hypothesizes that Dielectrophoresis can be combined with standard filtration to reduce filter fouling, extending membrane life, and enabling continuous operation. This project investigates a method to reduce fouling, add specificity and efficiency, and decrease the cost and challenge of filtration based biofluid separations.
To substantiate this thesis, we designed, fabricated, and tested a filtration system to filter micron diameter particles in suspension using Millipore™ membranes together with fabricated electrodes in a cross-flow filtration system. This prototype device elicits a repulsive dielectrophoretic (DEP) force via the application of a direct current (5-20 volts) sourced from a computer controlled voltage sequencer, designed to levitate and remove larger particles (> 6 µm) before particulate-membrane interaction. Analysis of the results shows a sufficient decrease in particles adhered to the filtration membrane, as compared to control, suggesting DC DEP may be a valid effector in this device. We are convinced that further research will augment the results validating the proof-of-concept thesis presented herein.
2
Chandrasekar, Soni. "Laser assisted fabrication of polymer based microfluidic devices." Thesis, Heriot-Watt University, 2015. http://hdl.handle.net/10399/3031.
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3
Venkatachalam, Vinothini. "Microwave assisted processing of Nanocrystalline Barium Titanate based capacitor devices." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8448.
Повний текст джерелаАнотація:
Interest towards fabrication of nanostructured electro ceramic devices has witnessed exponential growth in recent years, owing to the requirements of miniaturization, multifunctionality and improved reliability. The major hurdle in realising the full potential of nano ceramics is preventing the unwanted grain growth whilst achieving high densification during conventional high temperature processing. In this project, a detailed study was performed on the fabrication of nanostructured barium titanate based X7R multilayer ceramic capacitors (MLCCs) using microwave assisted heating. The main processing stages involved in MLCC manufacture were; (i) nano BT powder synthesis, (ii) making nano BT ink formulations suitable for screen printing, (iii) sintering of components using conventional, microwave, hybrid heating methods and (iv) performance evaluation of the end products.
4
Grue, Nathalie. "Illustration, explanation and navigation of physical devices and design processes." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/9228.
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5
Nassuphis, Nick I. "A laser-assisted microchemistry system for the fabrication of small electromechanical devices." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36928.
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6
Liang, Tao. "Design and modeling of grating-assisted devices for microwave and optical applications." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282414.
Повний текст джерелаАнотація:
Grating structures have found applications in microwave, millimeter wave, and optical devices and systems. While analytical methods can handle infinite, periodic gratings well, numerical methods usually are needed for general finite and/or aperiodic gratings. We have carried out numerical investigations of a number of grating structures with the finite-difference time-domain approach (FDTD). This approach is selected because of its ability to model complex structures and materials. Some of the many grating applications we investigated include gratings that can be used in waveguide environments as output couplers to transfer guided wave energy into radiation fields which propagate into predefined directions, as mode converters to convert energy between various modes in the same waveguide, or as directional couplers to transfer energy between different waveguides. Optical switching is also shown to be achievable and an efficient WDM demultiplexer is proposed and analyzed. The performance of grating assisted couplers in the presence of dispersive materials is also characterized. We have shown that the FDTD simulator is very effective in modeling complicated grating structures. Novel device features and operating behaviors have been revealed through its use. These results and observations provide insight and guidelines for the future design of various other grating assisted devices.
7
Patterson, Donald Jay. "Assisted cognition : compensatory activity assistance technology /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/6853.
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8
Lynch, Amy Katherine. "Robot assisted mobility for very young infants." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 156 p, 2009. http://proquest.umi.com/pqdweb?did=1824925431&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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9
Patten, Jared Russell. "A Flexible FPGA-Assisted Framework for Remote Attestation of Internet Connected Embedded Devices." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/6722.
Повний текст джерелаАнотація:
Embedded devices permeate our every day lives. They exist in our vehicles, traffic lights, medical equipment, and infrastructure controls. In many cases, improper functionality of these devices can present a physical danger to their users, data or financial loss, etc. Improper functionality can be a result of software or hardware bugs, but now more than ever, is often the result of malicious compromise and tampering, or as it is known colloquially "hacking". We are beginning to witness a proliferation of cyber-crime, and as more devices are built with internet connectivity (in the so called "Internet of Things"), security should be of the utmost concern. Embedded devices have begun to seamlessly merge with our daily existence. Therefore the need for security grows as it more directly affects the safety of our data, property, and even physical health. This thesis presents an FPGA-assisted framework for remote attestation, a security service that allows a remote device to prove to a verifying entity that it can be trusted. In other words, it presents a protocol by which a device (be it an insulin pump, vehicle, etc.) can prove to a user (or other entity) that it can be trusted - i.e. that it has not been "hacked". This is accomplished through executable code integrity verification and run-time monitoring. In essence, the protocol verifies that a device is running authorized and untampered software and makes it known to a verifier in a trusted fashion. We implement the protocol on a physical device to demonstrate its feasibility and to examine its performance impact.
10
Lee, Kwan-Ho. "Development of four novel UWB antennas assisted by FDTD method." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1103659688.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xvii, 165 p.; also includes graphics (some col.). Includes bibliographical references (p. 158-165).
11
Dolatmoradi, Ata. "Thermally-Assisted Acoustofluidic Separation for Bioanalytical Applications." FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3371.
Повний текст джерелаАнотація:
Changes in the biomechanical properties of cells accompanying the development of various pathological conditions have been increasingly reported as biomarkers for various diseases and as a predictor of disease progression stages. For instance, cancer cells have been found to be less stiff compared to their healthy counterparts due to the proteomic and lipidomic dysregulations conferred by the underlying pathology. The separation and selective recovery of cells or extracellular vesicles secreted from such cells that have undergone these changes have been suggested to be of diagnostic and prognostic value.
This dissertation first describes the implementation of a stiffness-based separation of phosphatidylcholine-based vesicles using a method first introduced based on the research in this work and was dubbed thermally-assisted acoustophoresis, or thermo-acoustophoresis. By tuning the temperature, we achieved the separation of vesicles of the same size, shape, and charge but with different stiffness values. It was observed that at a specific transition point, the acoustic contrast factor of vesicles changed sign from positive to negative. This change was mainly due to change in the compressibility of the vesicles, which is inversely proportional to stiffness. The acoustic contrast temperature (Tϕ), corresponding to the temperature at which the contrast factor switches sign, was determined to be unique to the composition of the vesicles. This unique temperature signature allowed us to develop this separation method of vesicles with distinct membrane stiffness with target outlet purities exceeding 95%.
We have further explored the functionality of this method by experimenting with cholesterol-containing vesicles. In cells, the cholesterol content plays a crucial role in determining stiffness. Changes in the cholesterol content in cellular membranes can be an indication of pathological disorders. We evaluated the Tϕ of vesicles at different cholesterol molar ratios (Xchol) and developed a multi-stage lab-on-a-chip method to accomplish for the first time the separation of a three-vesicle mixture. Using Xchol = 0.1, 0.2, and 0.3 vesicles, we obtained efficiencies exceeding 93%. The simplicity, rapidity, and label-free nature of this approach holds promise as a diagnostic and separation tool for cells affected by diseases that affect the stiffness and extracellular vesicles such as exosomes and microvesicles.
12
Ying, Julang. "Barometer-Assisted 3D Indoor WiFi Localization for Smart Devices-Map Selection and Performance Evaluation." Digital WPI, 2016. https://digitalcommons.wpi.edu/etd-theses/762.
Повний текст джерелаАнотація:
Recently, indoor localization becomes a hot topic no matter in industry or academic field. Smart phones are good candidates for localization since they are carrying various sensors such as GPS, Wi-Fi, accelerometer, barometer and etc, which can be used to estimate the current location. But there are still many challenges for 3D indoor geolocation using smart phones, among which the map selection and 3D performance evaluation problems are the most common and crucial. In the indoor environment, the popular outdoor Google maps cannot be utilized since we need maps showing the layout of every individual floor. Also, layout of different floors differ from one another. Therefore, algorithms are required to detect whether we are inside or outside a building and determine on which floor we are located so that an appropriate map can be selected accordingly. For Wi-Fi based indoor localization, the performance of location estimation is closely related to the algorithms and deployment that we are using. It is difficult to find out a general approach that can be used to evaluate any localization system. On one hand, since the RF signal will suffer extra loss when traveling through the ceilings between floors, its propagation property will be different from the empirical ones and consequently we should design a new propagation model for 3D scenarios. On the other hand, properties of sensors are unique so that corresponding models are required before we analyze the localization scheme. In-depth investigation on the possible hybrid are also needed in case more than one sensor is operated in the localization system. In this thesis, we firstly designed two algorithms to use GPS signal for detecting whether the smart device is operating inside or outside a building, which is called outdoor-indoor transition detection. We also design another algorithm to use barometer data for determining on which floor are we located, which is considered as a multi-floor transition detection. With three scenarios designed inside the Akwater Kent Laboratory building (AK building) at Worcester Polytechnic Institute (WPI), we collected raw data from an Android phone with a version of 4.3 and conducted experimental analysis based on that. An efficient way to quantitatively evaluate the 3D localization systems is using Cramer-Rao Lower Bound (CRLB), which is considered as the lower bound of the estimated error for any localization system. The characteristics of Wi-Fi and barometer signals are explored and proper models are introduced as a foundation. Then we extended the 2D CRLB into a 3D format so that it can fit the our 3D scenarios. A barometer-assisted CRLB is introduced as an improvement for the existing Wi-Fi Receive Signal Strength (RSS)-only scheme and both of the two schemes are compared with the contours in every scenario and the statistical analysis.
13
Kumar, Ashutosh. "Computation Assisted Study of Silicon Carbide: A Potential Candidate Material for Radiation Detector Devices." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1376960400.
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14
Cheng, Kuan. "Magnet-assisted Layer-by-layer Assembly on Nanoparticles Based on 3D-printed Microfluidic Devices." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1554984796295339.
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15
Carter, Henry Lee. "Efficient techniques for secure multiparty computation on mobile devices." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54318.
Повний текст джерелаАнотація:
Smartphones are rapidly becoming a widespread computation platform, with many users relying on their mobile devices as their primary computing device. This popularity has brought about a plethora of mobile applications and services which are designed to efficiently make these limited devices a viable source of entertainment and productivity. This is commonly accomplished by moving the critical application computation to a Cloud or application server managed by the application developer. Unfortunately, the significant number of breaches experienced by mobile application infrastructure and the accompanying loss of private user data indicates the need for stronger security and privacy guarantees before this model of computation can become ubiquitous.
The cryptographic community has developed the field of secure multiparty computation (SMC) to allow applications to perform computation over encrypted data. Such a protocol would allow mobile users to keep their private information encrypted while still enjoying the convenience of their Cloud based applications. However, while SMC protocols have seen significant advances in efficiency on desktop and server class machines, they currently require more computation power and memory than is available on commodity smartphones. Furthermore, even as smartphone computational power increases, the mobile-specific limitations of network bandwidth and power usage will always stand as barriers to efficiently executing SMC protocols.
This dissertation develops techniques for outsourcing the costly operations in garbled circuit SMC protocols to an untrusted Cloud to allow resource-constrained devices to use this cryptographic primitive. By providing the mobile device with a third party Cloud provider, we show that it is possible for a mobile device to execute a garbled circuit with an application server at approximately the same efficiency as the same computation run between two server class machines. We first show two protocols for outsourcing the garbled circuit evaluation and generation. We develop a novel outsourced oblivious transfer (OOT) protocol to make this type of outsourcing possible. Second, we develop a black box technique for outsourcing any two-party SMC protocol, and show that the overhead incurred by outsourcing is minimal. Finally, we develop a protocol for outsourcing SMC that pro- vides both input privacy and circuit privacy, preventing the assisting Cloud from learning anything about the computation besides the fact that it took place. Through the protocols and the empirical evaluations in this dissertation, we show that executing SMC protocols on mobile devices can be done with comparable efficiency to the desktop platform, and provide techniques to allow for such computation using the latest developments in secure computation.
16
Atkins, D. W. "The CFD assisted design and experimental testing of a wing-sail with high lift devices." Thesis, University of Salford, 1996. http://usir.salford.ac.uk/14811/.
Повний текст джерелаАнотація:
A wingsail is a solid symmetrical aerofoil section which creates thrust in the same manner as a conventional sail. Wingsails may either be used as a sole power unit, e. g. for a yacht or catamaran, or as an auxiliary power unit on a larger craft, e. g. fishing vessels, cargo ships or passenger liners. To augment the thrust created by the wingsail, high lift devices are employed to increase both the maximum lift and the stall incidence of the aerofoil. A wingsail must be symmetrical and capable of creating an equal lift force with the flow approaching the leading edge from either side of the wing centreline, i. e. the wingsail surface must act as either the upper, or lower pressure surface. Initial experimental work proved that using a symmetrical slat as a leading edge high lift device both delayed the separation of flow over the wingsail upper surface and increased the effective camber of the aerofoil. To increase the thrust created still further, this leading edge high lift device was combined with a trailing edge high lift device, a symmetrical single slotted flap. Due to the large number of possible model configurations, a commercially available CFD package was introduced to assist with the design. A series of validation tests comparing the CFD with published and experimental results showed a qualitative agreement with these results. However, the CFD predictions were not sufficiently accurate to be used quantitatively. The computationally designed triple element model was tested experimentally. Lift, drag, pitching moment and pressure distribution measurements were taken from the model. The results of this testing showed that the triple element wingsail increased the plain wing Coax by 68% and the stall incidence by between 4* and 6'. The final triple element wingsail design also increased the thrust of a plain wingsail over the whole operating region. Thrust was increased by up to 83% at the wind angles where a wingsail is most efficient. The results also proved that a commercially available CFD package can be used as an effective and time saving tool for wingsail design.
17
Zaman, Ayesha. "Modeling and Experimental Characterization of Memristor Devices for Neuromorphic Computing." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton159636782366637.
Повний текст джерела
18
XI, XI. "RICERCA SU DEVICES ROBOTICI USER-FRIENDLY IN AAL." Doctoral thesis, Università degli studi di Genova, 2020. http://hdl.handle.net/11567/1008270.
Повний текст джерелаАнотація:
Il crescente interesse nei confronti del design come attivatore e facilitatore di processi apre la strada allo sviluppo di ricerche legate alla salute e alla qualità della vita, con particolare attenzione alle potenzialità offerte dalle nuove tecnologie (ICT), in un contesto sociale fortemente condizionato dall’evoluzione demografica, che vede nell’invecchiamento della popolazione una delle sfide cruciali per i decenni a venire.
Partendo dall’individuazione delle esigenze e dei bisogni dell’utenza debole, con particolare attenzione alla terza e quarta età, e grazie ad un approccio di tipo olistico ed innovativo, la ricerca si prefigge di approfondire il ruolo del design per la valorizzazione di prodotti e soluzioni applicabili a sistemi tecnologici di assistenza. La ricerca, inoltre, prende in considerazione differenti ambiti compresi nell’ambito disciplinare AAL (Ambient Assisted Living), quali telecomunicazioni, informatica, microsistemi, robotica e nuovi materiali.
In particolare, l’Interaction Design suggerisce agli utenti l’utilità di un prodotto e come esso possa aiutarli a raggiungere i propri obiettivi. In altre parole, l’Interfaccia interpreta la tecnologia e la funzione dei prodotti. Dal punto di vista della semiotica e semantica, l’Interaction Design si occupa della progettazione dello User Experience, ovvero l'esperienza personale degli utenti all'interno del loro ambiente sociale. Pertanto, per alcuni aspetti, l’Interaction Design incorpora caratteristiche storiche e geografiche che caratterizzano la domanda degli utenti.
Il progetto di ricerca sarà sviluppato a partire da uno studio che mira a rendere le nuove tecnologie facilmente accessibili a persone anziane, la cui condizione socio-culturale impedisce di fare pieno uso delle nuove tecnologie.
Attraverso lo studio di progettazioni in processo di sviluppo e una serie di sperimentazioni in diversi contesti, quali ospedaliero, domestico, urgente/specifico e generale, si intavolerà la discussione sulle strategie dello sviluppo progettuale. Quest’ultima riguarderà la verifica dell'usabilità e dell'accessibilità del prodotto e la valutazione dell'efficienza collaborativa dei dispositivi robotici indoor secondo l'approccio del concept AAL.The growing interest in design as an activator and a facilitator of processes opens the way to the development of research related to health and quality of life, with particular attention to the potential offered by new technologies (ICT), in a social context strongly conditioned by the demographic evolution, which sees an ageing population one of the crucial challenges for the decades to come. Starting from the identification of the needs and needs of the weak user, with particular attention to the third and fourth age, and thanks to a holistic and innovative approach, the research aims to deepen the role of design for the enhancement of products and solutions applicable to technological assistance systems. The research also takes into consideration different areas included in the AAL (Ambient Assisted Living) discipline, such as telecommunications, information technology, Microsystems, robotics and new materials. In particular, Interaction Design suggests to users the usefulness of a product and shows how it can help them achieve their goals. In other words, the Interface interprets the technology and function of the products. From the point of view of semiotics and semantics, Interaction Design deals with the design of the User Experience, that is, the personal experience of users within their social environment. Therefore, in some aspects, Interaction Design incorporates historical and geographical characteristics that characterise user demand. The research project will be developed starting from a study that aims to make new technologies easily accessible to older people, whose socio-cultural condition prevents them from making full use of new technologies. Through the study of designs in the development process and a series of experiments in different contexts, such as hospital, home, urgent / specific and general, the discussion on the strategies of project development will be initiated. The latter will concern the verification of the usability and accessibility of the product and the evaluation of the collaborative efficiency of the indoor robotic devices according to the approach of the AAL concept.
19
Ikkawi, Rabee Muhieddine. "Heat assisted magnetic recording for areal densities beyond 1 Tbit/in²." Diss., [Riverside, Calif.] : University of California, Riverside, 2008. http://proquest.umi.com/pqdweb?index=0&did=1663077891&SrchMode=2&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1268246782&clientId=48051.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--University of California, Riverside, 2008.Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 10, 2010). Includes bibliographical references (p. 126-135). Also issued in print.
20
Gasparrini, Samuele. "Activity monitoring and behaviour analysis using RGB-depth sensors and wearable devices for ambient assisted living applications." Doctoral thesis, Università Politecnica delle Marche, 2016. http://hdl.handle.net/11566/243152.
Повний текст джерелаАнотація:
Nei paesi sviluppati, la percentuale delle persone anziane è in costante crescita. Questa condizione è dovuta ai risultati raggiunti nel capo medico e nel miglioramento della qualità della vita. Con l'avanzare dell'età, le persone sono più soggette a malattie correlate con l'invecchiamento. Esse sono classificabili in tre gruppi: fisiche, sensoriali e mentali. Come diretta conseguenza dell'aumento della popolazione anziana ci sarà quindi una crescita dei costi nel sistema sanitario, che dovrà essere affrontata dalla UE nei prossimi anni.
Una possibile soluzione a questa sfida è l'utilizzo della tecnologia. Questo concetto è chiamato Ambient Assisted living (AAL) e copre diverse aree quali ad esempio il supporto alla mobilità, la cura delle persone, la privacy, la sicurezza e le interazioni sociali.
In questa tesi differenti sensori saranno utilizzati per mostrare, attraverso diverse applicazioni, le potenzialità della tecnologia nel contesto dell'AAL. In particolare verranno utilizzate le telecamere RGB-profondità e sensori indossabili.
La prima applicazione sfrutta una telecamera di profondità per monitorare la distanza sensore-persona al fine di individuare possibili cadute. Un'implementazione alternativa usa l'informazione di profondità sincronizzata con l'accelerazione fornita da un dispositivo indossabile per classificare le attività realizzate dalla persona in due gruppi: Activity Daily Living e cadute.
Al fine di valutare il fattore di rischio caduta negli anziani, la seconda applicazione usa la stessa configurazione descritta in precedenza per misurare i parametri cinematici del corpo durante un test clinico chiamato Timed Up and Go.
Infine, la terza applicazione monitora i movimenti della persona durante il pasto per valutare se il soggetto sta seguendo una dieta corretta. L'informazione di profondità viene sfruttata per riconoscere particolari azioni mentre quella RGB per classificare oggetti di interesse come bicchieri o piatti presenti sul tavolo.Nowadays, in the developed countries, the percentage of the elderly is growing. This situation is a consequence of improvements in people's quality life and developments in the medical field. Because of ageing, people have higher probability to be affected by age-related diseases classified in three main groups physical, perceptual and mental. Therefore, the direct consequence is a growing of healthcare system costs and a not negligible financial sustainability issue which the EU will have to face in the next years. One possible solution to tackle this challenge is exploiting the advantages provided by the technology. This paradigm is called Ambient Assisted Living (AAL) and concerns different areas, such as mobility support, health and care, privacy and security, social environment and communication. In this thesis, two different type of sensors will be used to show the potentialities of the technology in the AAL scenario. RGB-Depth cameras and wearable devices will be studied to design affordable solutions. The first one is a fall detection system that uses the distance information between the target and the camera to monitor people inside the covered area. The application will trigger an alarm when recognizes a fall. An alternative implementation of the same solution synchronizes the information provided by a depth camera and a wearable device to classify the activities performed by the user in two groups: Activity Daily Living and fall. In order to assess the fall risk in the elderly, the second proposed application uses the previous sensors configuration to measure kinematic parameters of the body during a specific assessment test called Timed Up and Go. Finally, the third application monitor's the user's movements during an intake activity. Especially, the drinking gesture can be recognized by the system using the depth information to track the hand movements whereas the RGB stream is exploited to classify important objects placed on a table.
21
Peiris, Nirmal. "Microwave-assisted processing of solid materials for sustainable energy related electronic and optoelectronic applications." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14941.
Повний текст джерелаАнотація:
Materials processing using microwave radiation is emerging as a novel and innovative technology that has proven useful in a number of applications. It has various advantages over conventional processing, such as; time and energy saving, very rapid heating rates, considerably reduced processing time and temperature, fine microstructures and improved mechanical properties, better product performance, etc. Microwave irradiation has shown great potential for the processing of different semiconductor materials and inorganic solids for various advanced electronic and optoelectronic devices such as solar cells, batteries, supercapacitors, fuel cells etc. This work intends to investigate the effect of microwave radiation on various semiconductor materials and inorganic solids, in particular the changes in their chemical, physical and photoelectrochemical properties after microwave treatment. Microwaves have been used as an alternative method to conventional thermal annealing for post annealing of widely used semiconductors (TiO2, ZnO nanorods), battery materials (lithium aluminium titanium phosphates), and synthesis of materials (ZnO, Ti0.97Pd0.03O1.97). It is found that, in contrast to conventional thermal annealing, microwave treatment of such materials improves the crystallinity without any structural changes by preserving their nanostructure due to the difference in the heating mechanism (volumetric heating). The results demonstrate that microwave processing is a promising alternative method to the traditional conventional sintering for materials processing for advanced electronic and optoelectronic devices. Also the microwave annealing method offers energy savings of up to ~75%, which would make it highly desirable for industrial scale up.
22
Akmaldinov, Kamil. "Ferromagnetic/antiferromagnetic exchange bias nanostructures for ultimate spintronic devices." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GRENY009/document.
Повний текст джерелаАнотація:
Les applications d’électronique de spin telles les mémoires à accès aléatoire (MRAM), les capteurs (e.g.les têtes de lecture des disques durs d’ordinateurs) et les éléments de logique magnétique utilisent les interactionsd’échange ferromagnétique/antiferromagnétique (F/AF) dans le but de définir une direction de référence pour lespin des électrons de conduction. Les MRAM à écriture assistée thermiquement (TA-MRAM) utilisent mêmedeux bicouches F/AF : une pour le stockage de l’information et l’autre comme référence. Ces dernièresapplications technologiques impliquent des étapes de nanofabrication des couches minces continues pour formerune matrice de cellules mémoires individuelles. La qualification industrielle du produit final impose de sérieusescontraintes sur la largeur des distributions des propriétés magnétiques - y compris d’échange F/AF - de cellulemémoire à cellule mémoire. Des phases verres de spin réparties de manière aléatoire sur la couche continue, àl’interface F/AF ou dans le coeur de l’AF pourraient contribuer de manière significative à ces distributionsd’échange F/AF dans les dispositifs, après nanofabrication ; comme supposé il y a de cela quelques années. Lebut de cette thèse est d’étudier factuellement le possible lien entre verre de spin répartis dans des couches mincesF/AF et dispersions de propriétés d’échange de cellule mémoire à cellule mémoire dans les dispositifs TAMRAMcorrespondants. Avant cela, l’origine de ces régions verre de spin a été étudiée et une attention plusparticulière a été portée au rôle joué par les diffusions de Mn. Ces dernières ont été directement observées,comprises et l’utilisation de barrières complexes pour les réduire et par là même pour diminuer la quantité dephases verre de spin a été mise en oeuvre avec succès. En guise d’alternative pour varier la quantité de verres despin, l’utilisation d’AFs composites a été également étudiée dans le cadre de cette thèse. Ce type d’AF permet dumême coup de varier la stabilité thermique des grains AF et de répondre à un autre problème identifié pour lesTA-MRAM qui consiste à trouver des matériaux AF avec des propriétés de rétention et d’écriture intermédiairespar rapport aux matériaux actuellement utilisés. Finalement, ces AFs composites ont été utilisés comme moyende varier la quantité de verres de spin dans des dispositifs TA-MRAM réels et de prouver le lien direct avec ladispersion de propriétés de cellule mémoire à cellule mémoireSpintronics applications such as magnetic random access memories (MRAM), sensors (e.g.. hard diskdrive read head) and logic devices use ferromagnetic/antiferromagnetic (F/AF) exchange bias (EB) interactionsto set the reference direction required for the spin of conduction electrons. Thermally-assisted (TA-) MRAMapplications even use two F/AF exchange biased bilayers: one for reference and one for storage. Suchtechnological applications involve patterning full sheet wafers into matrix of individual bit-cells. Industrialproducts qualification imposes stringent requirements on the distributions of the magnetic properties from cell tocell, including those related to EB. It was supposed few years ago that randomly spread spin-glass like phases atthe F/AF interface or within the bulk of the AF layer significantly contribute to the distributions of EB propertiesin devices after processing. This thesis aimed at factually studying the link between spin-glasses spread overF/AF thin films and bit-cell dispersions of EB in corresponding TA-MRAM. Prior to that the origin of the spinglasslike regions and more specifically the role of Mn-diffusion was consolidated. Mn-diffusion was directlyobserved, understood and the use of complex barriers to reduce such diffusion and consequently to minimize theamount of spin-glass was successfully studied. Mixing AFs as another way to tune the amount of spin-glass likephases was also evidenced in the framework of this thesis. All at once, this last solution also tuned the AF grainsthermal stability and this solved another issue related to TA-MRAM, i.e. finding AF-materials with intermediateretention and write properties compared to the AFs presently used. Finally, those mixed antiferromagnets werethe mean chosen to tune the amount of spin-glass like phases in real TA-MRAM devices and to factually provetheir link with bit-cell distributions of EB properties
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Roe, Austin R. "RESONANT ACOUSTIC WAVE ASSISTED SPIN-TRANSFER-TORQUE SWITCHING OF NANOMAGNETS." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/6029.
Повний текст джерелаАнотація:
We studied the possibility of achieving an order of magnitude reduction in the energy dissipation needed to write bits in perpendicular magnetic tunnel junctions (p-MTJs) by simulating the magnetization dynamics under a combination of resonant surface acoustic waves (r-SAW) and spin-transfer-torque (STT). The magnetization dynamics were simulated using the Landau-Lifshitz-Gilbert equation under macrospin assumption with the inclusion of thermal noise. We studied such r-SAW assisted STT switching of nanomagnets for both in-plane elliptical and circular perpendicular magnetic anisotropy (PMA) nanomagnets and show that while thermal noise affects switching probability in in-plane nanomagnets, the PMA nanomagnets are relatively robust to the effect of thermal noise. In PMA nanomagnets, the resonant magnetization dynamics builds over few 10s of cycles of SAW application that drives the magnetization to precess in a cone with a deflection of ~45⁰ from the perpendicular direction. This reduces the STT current density required to switch the magnetization direction without increasing the STT application time or degrading the switching probability in the presence of room temperature thermal noise. This could lead to a pathway to achieve energy efficient switching of spin-transfer-torque random access memory (STT-RAM) based on p-MTJs whose lateral dimensions can be scaled aggressively despite using materials with low magnetostriction by employing resonant excitation to drive the magnetization away from the easy axis before applying spin torque to achieve a complete reversal.
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Mustaffa, Mohd N. "An alternative user interface for an expanded version of the Computer Aided Teaching System (CATSY)." Virtual Press, 1986. http://liblink.bsu.edu/uhtbin/catkey/459232.
Повний текст джерелаАнотація:
A new version of a Computer Aided Teaching System, CATSY-3, was created in order to allow greater flexibility and efficiency than older versions of CATSY. In the implementation of CATSY-3, the menu was transferred from the screen to the data tablet. In the process, the control structure of CATSY was rewritten to allow complete freedom of movement from one menu option to any another.A keyboard input feature (KEYIN) is also included in CATSY-3 in order to allow a more rapid mode of menu selection and to allow the option of precision coordinate input. Additional menu options are included in CATSY-3, namely, COPY, MOVE, REFRESH_OBJECT, interactive COLOR change, automatic set-up for input devices, among others.The history and description of various electronic chalkboard` implementations are also presented in this thesis.
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Pedraza, Vincent. "CATSY, computer aided teaching system : system overview, graphics and applications." Virtual Press, 1985. http://liblink.bsu.edu/uhtbin/catkey/416441.
Повний текст джерелаАнотація:
Computer Aided Teaching System (CATSY) is an interactive graphics system, utilizing current microcomputer technology, along with a graphics tablet and a large screen projection system to enhance lecture presentations. Included in this thesis are descriptions of the supporting graphics software (POLY-ReGIS) and the computer peripherals used in the development of CATSY.The development of interactive graphics is stressed in this thesis. Applications of these graphics to CATSY are presented and an introduction to the data structures used in this system is also given. This thesis is intended to support and complement the masters thesis presented by Mr. John Raab, which deals primarily with the system implementation, data structures and the text editor used in CATSY.
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ALIMELLI, ADRIANO. "Analytical system with familiar devices engineering." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2009. http://hdl.handle.net/2108/955.
Повний текст джерелаАнотація:
In the last few years there has been a huge demand to monitor different chemical environments, such as for example urban indoor and outdoor atmospheres, food aromas, etc. Chemical Optical sensors are among the most promising devices to be exploited for these kind of applications.
Nonetheless, the chemical practice of this approach is badly balanced by the transducer counterpart. Indeed, traditional optical instrumentations of high quality are usually bulky and expensive. On the other side in the last decade, in spite of the high cost of optical instruments, we assisted to a fast growth of performance in fields as consuming electronics, giving rise to a number of low-cost advanced optical equipments such as digital scanners, cameras, and screens whose characteristics largely fit the requirements necessary to capture change of optical properties of sensitive layers in many practical applications, that could be usefully exploited in routine analysis. In this thesis will be demonstrated that a combination of a computer monitor and an inexpensive webcam may be turned into a sort of spectrophotometer instrument. This last technique, known as Computer Screen Photo assisted Technique (CSPT) is based on the fact that a computer screen can be easily programmed to display millions of colour, combining wavelengths in the optical range. The CSPT is a sensing method that allows regular computer screens and web cameras to operate as generic sensing platforms of optical (bio)chemical assays. Due to the large diffusion of portable computers, PDAs, and cellular phones all endowed with colour screen, camera, and an even more extended computation capabilities, the application of the CSPT concept may be foreseen as to give rise to a sort of ubiquitous analytical capacity.
During a CSPT measurement the screen illuminates the array with an appropriate sequence of colours, while the webcamera captures the image of the array under analysis in synchronism with the illumination. The result of this data acquisition is a video stream, where regions of interest (ROIs) are selected and the intensity of the recorded pixels averaged into these regions chosen by us. The procedure is repeated along all N (length of the colour sequence) frames, generally corresponding to an illuminating sequence resembling the human perception of the visible spectrum. In this way a N elements vector is obtained for each ROI and camera channel. A fingerprint of the complete array is often constructed by concatenating red, green and blue channel vectors of each ROI and subsequently by collecting the different ROI vectors in a single (N*M*3) elements vector, where N is the length of the colour sequence, M is the number of the ROIs selected and 3 is the number of camera channel (Red, Green and Blue).
Then CSPT could in principle be used to detect general parameters related to the absorbance-emission spectra of every material under observation. In this Thesis, we show the possibility to use this very simple platform (CSPT), in two different configuration (Enose-mode and Spectroscopy mode), for very different kind of applications. In fact, in the first case, we present a chemical gas sensor array for detection of volatile molecules (NOx, CO, TEA, ETOH etc), and of fish freshness, where the optical features of layers of chemicals are transduced by CSPT-Enose mode; while in the second case we highlight the potentiality to use the CSPT such as a spectrophotometer, to directly optical characterize the compounds that we are observing (in this Thesis, Wine Optical Properties detection, and Bilirubin analysis will be showed).
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Battenberg, Janice K. "Selective attention : a comparison of two computer input devices utilizing a traditional keyboard vs. a touch sensitive screen." Virtual Press, 1988. http://liblink.bsu.edu/uhtbin/catkey/546125.
Повний текст джерелаАнотація:
The purpose of the study was to determine the efficacy of touch sensitive computer screens in focusing attention on a specific academic task. Forty nondelayed and forty delayed kindergarteners were compared as to their rates of task completion and performances on traditional computer keyboards versus touch sensitive screens. Two eight cell repeated measures experimental designs were used to compare the selective attention process of the nondelayed and delayed pupils. The two dependent variables manipulated in the study were two types of computer input device and the two developmental levels of the subjects. The dependent variable consisted of the number of previously unlearned French number words mastered through four performance measures involving speed, computer recall, noncomputer recall and noncomputer recognition.FINDINGSAs analyzed by a three factor MANOVA, a significant difference in the rate of task completion was shown in favor of the touch screens for all subjects in touching the sequential letters of the alphabet. Although there appeared to be no significant differences in noncomputer recall and recognition post tests, a four factor MANOVA verified significant differences in the subjects' computer recall post tests.CONCLUSIONSThe data supports the conclusion that the use of the touch sensitive screen facilitates the focus of attention (selective attention) on specific academic tasks and thus increases the rate of learning and degree of integration of new information. The degree of compatibility between the learner and the computer input device is greater with touch screens than with traditional keyboards for both nondelayed and delayed kindergarteners.The speed of completing the sequential touching of the alphabet letters was significantly faster for the touch screen than the traditional keyboard input. For mastery of information learned, the analyzed findings suggest a higher degree of recall for information learned through the touch screen intervention over the same instructional tasks with keyboard input.As the result of this key study, it is suggested future research investigations will expand the use of computers beyond educational drill, repetition, and games. Future investigations into the relationships between cognitive processing and the individualization of CAI could involve various age ranges, exceptionalities, and developmental comparisons.Department of Special Education
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Akers, John W. "A comparison of guided exploration and direct instruction computer tutors." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/30996.
Повний текст джерела
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Dai, Letian. "Silicon nanowire solar cells with μc-Si˸H absorbers for tandem radial junction devices". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS303.
Повний текст джерелаАнотація:
Dans cette thèse, nous avons fabriqué des cellules solaires à jonction radiale en nanofils de silicium avec du silicium microcristallin hydrogéné (µc-Si:H) comme absorbeur, par dépôt chimique en phase vapeur assisté par plasma à basse température (PECVD). Pour contrôler la densité de nanofils sur les substrats, nous avons utilisé des nanoparticules (NP) de dioxyde d'étain (SnO₂) d'un diamètre moyen de 55 nm, disponibles dans le commerce, comme précurseur du catalyseur Sn pour la croissance des nanofils de silicium. La distribution des nanoparticules de SnO₂ sur le substrat a été contrôlée par centrifugation et dilution du colloïde de SnO₂, en combinaison avec la fonctionnalisation du substrat. Par la suite, le SnO₂ est réduit en Sn métallique après le traitement par plasma de H₂, suivi de la croissance, par la technique vapeur-liquide-solide (VLS) assistée par plasma, de nanofils de Si sur lesquels sont déposées les couches P, I et N constituant les cellules solaires à jonction radiale. Nous avons atteint un taux de croissance élevé des nanofils de Si, jusqu'à 70%, avec une très large gamme de densité, de 10⁶ à 10⁹ /cm². Comme approche supplémentaire de contrôle de la densité des nanofils, nous avons utilisé du Sn évaporé comme précurseur du catalyseur Sn. Nous avons étudié l'effet de l'épaisseur de Sn évaporé, l'effet de la durée du traitement au plasma de H₂ et l'effet du débit de gaz H₂ dans le dans le mélange de précurseurs, sur la densité des nanofils. L'ellipsométrie spectroscopique in-situ (SE) a été utilisée pour contrôler la croissance des nanofils et le dépôt des couches de µc-Si:H sur les SiNWs. En combinant les résultats de in-situ SE et de microscopie électronique à balayage, une relation entre l'intensité du signal de SE pendant la croissance et la longueur et la densité des nanofils a été démontrée, ce qui permet d'estimer ces paramètres en cours de croissance. Nous avons réalisé une étude systématique des matériaux (couches intrinsèques et dopées de type n ou p de µc-Si:H, couches dopées d'oxyde de silicium microcristallin hydrogéné, µcSiOx:H) et des cellules solaires obtenues dans deux réacteurs à plasma appelés "PLASFIL" et "ARCAM". Les épaisseurs de revêtement sur substrat lisse et sur les nanofils ont été déterminées et nous avons obtenu une relation linéaire entre les deux, ce qui permet de concevoir un revêtement conforme sur les nanofils pour chaque couche avec une épaisseur optimale. Les paramètres des nanofils et des matériaux, affectant la performance des cellules solaires à jonction radiale, ont été systématiquement étudiés, les principaux étant la longueur et la densité des nanofils, l'épaisseur de la couche intrinsèque de µc-Si:H, l'utilisation de µc-SiOx:H et le réflecteur arrière en Ag. Enfin, avec les cellules solaires à jonction radiale en nanofils de silicium optimisées utilisant le µc-Si:H comme absorbeur, nous avons atteint un rendement de conversion de l'énergie de 4,13 % avec Voc = 0,41 V, Jsc = 14,4 mA/cm² et FF = 69,7%. Cette performance est supérieure de plus de 40 % à l'efficacité record de 2,9 % publiée précédemmentIn this thesis, we have fabricated silicon nanowire (SiNW) radial junction solar cells with hydrogenated microcrystalline silicon (μc-Si:H) as the absorber via low-temperature plasma-enhanced chemical vapor deposition (PECVD). To control the density of NW on the substrates, we have used commercially available tin dioxide (SnO₂) nanoparticles (NPs) with an average diameter of 55 nm as the precursor of Sn catalyst for the growth of SiNWs. The distribution of SnO₂ NPs on the substrate has been controlled by centrifugation and the dilution of the SnO₂ colloid, combined with the functionalization of the substrate. Subsequently, SnO₂ is reduced to metallic Sn after the H₂ plasma treatment, followed by the plasma-assisted vapor-liquid-solid (VLS) growth of SiNWs upon which the P, I and N layers constituting the radial junction solar cells are deposited. We have achieved a high yield growth of SiNWs up to 70% with a very wide range of NW density, from 10⁶ to 10⁹ /cm². As an additional approach of controlling the density of SiNWs we have used evaporated Sn as the precursor of Sn catalyst. We have studied the effect of the thickness of evaporated Sn, the effect of duration of H₂ plasma treatment and the effect of H₂ gas flow rate in the plasma, on the density of SiNWs.In-situ spectroscopic ellipsometry (SE) was used for monitoring the growth of SiNWs and the deposition of the layers of μc-Si:H on SiNWs. Combining in-situ SE and SEM results, a relationship between the intensity of SE signal and the length and the density of SiNWs during the growth was demonstrated, which allows to estimate the density and the length of SiNWs during the growth. We have carried out a systematic study of materials (intrinsic, p-type,n-type µc-Si:H and µcSiOx:H doped layers) and solar cells obtained in two plasma reactors named “PLASFIL” and “ARCAM”. The thicknesses of coating on the flat substrate and on the SiNWs have been determined with a linear relation which helps to design a conformal coating on SiNWs for each layer with an optimal thickness. The parameters of the SiNWs and the materials, affecting the performance of radial junction solar cells, have been systematically studied, the main ones being the length and the density of SiNWs, the thickness of intrinsic layer of μc-Si:H on SiNWs, the use of the hydrogenated microcrystalline silicon oxide (μc-SiOx:H) and the back reflector Ag. Finally, with the optimized silicon nanowire radial junction solar cells using the μc-Si:H as the absorber we have achieved an energy conversion efficiency of 4.13 % with Voc = 0.41 V, Jsc = 14.4 mA/cm² and FF = 69.7%. This performance is more than 40 % better than the previous published record efficiency of 2.9 %
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De, Kock Hugo Werner. "Dynamic control of the permanent magnet assisted reluctance synchronous machine with constant current angle." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/2062.
Повний текст джерелаАнотація:
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006.This thesis is about the dynamic control of a permanent magnet assisted reluctance synchronous machine (PMA RSM). The PMA RSM in this thesis is a 110 kW traction machine and is ideal for the use in electrical rail vehicles. An application of the dynamic control of the PMA RSM in electrical rail vehicles is to reduce wheel slip. The mathematical model of the PMA RSM is derived and explained in physical terms. Two methods of current control for the PMA RSM are investigated, namely constant field current control (CFCC) and constant current angle control (CCAC). It is shown that CCAC is more appropriate for the PMA RSM. A current controller for the PMA RSM that guarantees stability is derived and given as an analytic formula. This current controller can be used for any method of current control, i.e. CFCC or CCAC. An accurate simulation model for the PMA RSM is obtained using results from finite element analysis (FEA). The accurate model is used in a simulation to verify CCAC. A normal proportional integral speed controller for the PMA RSM is designed and the design is also verified by simulation. Practical implementation of the current and speed controllers is considered along with a general description of the entire drive system. The operation of the resolver (for position measurement) is given in detail. Important safety measures and the design of the electronic circuitry to give protection are shown. Practical results concerning current and speed control are then shown. To improve the dynamic performance of the PMA RSM, a load torque observer with compensation current feedback is investigated. Two observer structures are considered, namely the reduced state observer and the full state observer. The derivation of the full state observer and the detail designs of the observer elements are given. The accurate simulation model of the PMA RSM is used to verify the operation of the observer structures and to evaluate the dynamic performance. Both observer structures are implemented practically and practical results are shown. One method of position sensorless control, namely the high frequency voltage injection method, is discussed in terms of the PMA RSM. This work is additional to the thesis but it is shown, because it raises some interesting questions regarding the dynamic control of the PMA RSM.
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Oudenhoven, Rik. "Preparing for a sustainable future, with assisted rehabilitation. : How assistive devices can improve the treatment and rehabilitation process of ACL injuries." Thesis, Umeå universitet, Designhögskolan vid Umeå universitet, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-152337.
Повний текст джерелаАнотація:
Abstract The majority of sports injuries involve the lower body, particularly the knees. Roughly 2,5 million people suffer a knee injury each year. Through sudden harsh movements the knee can get damaged. Often, these injuries never truly heal. Once the knee is weakened the risk of injury increases and in many cases the function of the knee will never fully return. The goal of this project was to empower patients who suffer from damage to the Anterior Cruciate Ligament (ACL) to recover faster by providing a personalized and humanized rehabilitation plan. Inspiration and Method Interviews, shadowing sessions and workshops were done with patients, athletes, surgeons and therapists to truly gain an in depth understanding of the rehabilitation process and how to prevent the injury from happening. This showed that there is a clear problem with the rehabilitation between the therapist and the patients. The outcome of the treatment is too much determined by the capabilities of the therapist, who often do not have enough expertise or get too little information to generate a personalized treatment for each individual. Another big problem is the fact that patients lose their motivation since they feel that they are not improving, and alone in the overall process. It became clear that patients need to be empowered and to let them know that the outcome of the rehabilitation is completely in their hands. Result The result of this collaboration is Ara, the smart rehabilitation bracelet. Ara continuously monitors the injured knee to provide an increased amount of insights, which enables practitioners to take humanized, and data driven decisions to personalize the rehabilitation plan for each individual. It empowers patients to take an active part in their own rehabilitation by providing live and precise feedback on their activities throughout the day.
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Helsel, Sandra Kay. "A set of criteria derived from curriculum theory to assist in the planning, use and evaluation of educational interactive videodisc." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184372.
Повний текст джерелаАнотація:
It was the purpose of this study to develop a set of criteria derived from curriculum theory to assist in the planning, use and evaluation of educational interactive videodisc. That set of criteria, referred to herein as the EIVD Curricular Base, consists of six sets of guidelines corresponding to Eisner's (1985) curriculum typologies: Development of Cognitive Processes, Curriculum as Technology, Curriculum for Personal Relevance, Curriculum for Social Adaptation, Curriculum for Social Reconstruction, and Academic Rationalism. The set of criteria was developed through the examination of three primary research questions: (1) What ways have those elements Beauchamp (1981) deemed necessary for any curriculum theory (definitions, values, design, engineering, and regeneration) been operationalized in Eisner's six curriculum typologies; (2) To what extent do interactive design characteristics identified by DeBloois (1979) apply to curriculum theory; (3) How can the ability of videodisc to simulate reality be integrated into the set of criteria? Further, the proposed set of criteria was critiqued against sample educational videodiscs to establish its veracity. The results of this study indicate that the Cognitive Processes curricular typology utilizes the potential of educational interactive videodisc to a greater extent than any other curricular typology in the EIVD Curricular Base. Therefore, it is recommended that an in-depth exploration of the Cognitive Process set of criteria be initiated. Ideally, the exploration would result in the research, design, production, use and evaluation of an actual videodisc program. Several, more general, recommendations regarding education's use of videodisc technology and courseware complete this study.
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Zhen, Yongjian. "Improving students' math problem-solving skills in a computer-assisted learning environment." CSUSB ScholarWorks, 1999. https://scholarworks.lib.csusb.edu/etd-project/1797.
Повний текст джерела
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Hungr, Nikolai Anthony. "Haptic emulation of hard surfaces with applications to orthopaedic surgery." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/639.
Повний текст джерелаАнотація:
A generally accepted goal in orthopaedic surgery today is to maximize conservation of tissue and reduce tissue damage. Bone-conserving implants have bone-mating surfaces that reproduce the natural curvature of bone structures, requiring less bone removal. No small, reliable, inexpensive and universal bone sculpting technique currently exists, however, that can both create and accurately align such complex surfaces. The goal of this thesis was to develop a haptic hard surface emulation mechanism that could be applied to curvilinear bone sculpting using a surgical robot. A novel dynamic physical constraint concept was developed that is able to emulate realistic hard constraints, smooth surface following, and realistic surface rigidity, while allowing complete freedom of motion away from the constraints. The concept was verified through the construction of a two-link manipulator prototype. Tests were run on nine users that involved each user tracing out five different virtual surfaces on a drawing surface using the prototype. The primary purposes of prototype testing were to obtain subjective data on how effectively the dynamic physical constraint concept simulates simple surfaces, to assess how it reacts to typical user interactions and to identify any unexpected behaviour. Users were 100% satisfied with the prototype’s ability to emulate realistic and stiff hard surfaces and with its ease of manipulation. The amount of incursion into each of the virtual surfaces by all the users was measured to assess the precision of the system with the goal of deciding whether this new haptic concept should be further developed specifically for precision applications such as surgery. For curvilinear surfaces, 90% of the cumulative distribution of the measured data was less than 2mm, while for linear surfaces it was less than 6mm. Four behavioural effects were noticed: lateral deflection, reverse ‘stickiness’, hysteresis and instability in certain areas. These effects were studied in detail to determine how to either eliminate them or to minimize them through system design optimization. A computer simulation was also used to model the behaviour of the prototype and to gain further understanding of these effects. These analyses showed that the concept can be successfully used in curvilinear bone sculpting.
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Austin, Dianne Lenore. "Using a teacher created website to provide 24/7 access to student assignments: An abstract." CSUSB ScholarWorks, 2005. https://scholarworks.lib.csusb.edu/etd-project/2792.
Повний текст джерелаАнотація:
The purpose of this project was to create a website that would assist students in the process of submitting the correct assignments with a minimal amount of frustration for all parties concerned: teachers, administrators, parents, and students.
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Galantier, João. "Avaliação do emprego clínico do dispositivo de assistência ventricular InCor como ponte para o transplante cardíaco." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/5/5156/tde-11122007-145953/.
Повний текст джерелаАнотація:
Apesar dos crescentes avanços no controle e tratamento da insuficiência cardíaca, sejam eles na área clinica ou cirúrgica, o tratamento definitivo permanece sendo o transplante cardíaco. No entanto, o transplante cardíaco tem enfrentado o grave problema da escassez de doadores. Atualmente, estima-se que entre 20% e 40% dos pacientes selecionados falecem na fila de espera em todo o mundo sendo que a maioria, por falência circulatória progressiva. Para esses pacientes, a utilização de dispositivos de assistência circulatória mecânica é, muitas vezes, a única possibilidade de sobrevivência durante a espera do doador. No Brasil, a experiência com o emprego de métodos de assistência circulatória mecânica no tratamento do choque cardiogênico é pequena. Paralelamente, a expectativa de vida dos pacientes nesta situação, em particular os de etiologia chagásica, é muito limitada, e nenhum programa regular foi ainda introduzido com a finalidade de utilizar estes dispositivos no tratamento do choque cardiogênico refratário, especialmente como ponte para o transplante cardíaco. Objetivos: O objetivo deste estudo é determinar a viabilidade e segurança do implante do DAV-InCor como ponte para o transplante cardíaco, avaliando o seu desempenho hemodinâmico, a evolução clínica e as alterações da resposta inflamatória dos pacientes submetidos a este procedimento. Métodos: Este estudo foi realizado em pacientes que estavam na fila de espera para o transplante cardíaco, no período de outubro de 2003 a abril de 2006, e se apresentavam em quadro clínico de choque cardiogênico refratário. Durante os primeiros dias, foram analisadas as medidas de pressão capilar pulmonar (PCP), pressão de artéria pulmonar (PAP), pressão venosa central (PVC), débito cardíaco e índice cardíaco (IC). O cálculo do fluxo indexado era obtido pela divisão entre o fluxo do dispositivo pela superfície corpórea. Durante o seguimento pós-operatório imediato, a saturação venosa central de oxigênio (SVO2), os níveis de lactato sérico, uréia, creatinina, bilirrubinas e desidrogenase lática foram dosados diariamente. Os níveis séricos do peptídeo natriurético central (BNP), das interleucinas (IL6 e IL8), do fator de necrose tumoral alfa (TNF alfa) e da proteína C reativa (PCR) foram dosados nos três primeiros dias de seguimento e posteriormente a cada semana. Resultados: No período do estudo, 29 pacientes foram indicados em caráter de prioridade para o transplante cardíaco. Destes pacientes, 11 evoluíram em choque cardiogênico refratário à terapêutica farmacológica e ao implante de balão intra-aórtico. O implante do DAV-Incor foi realizado em sete destes pacientes. O diagnóstico etiológico foi cardiopatia chagásica em cinco (71%) e cardiomiopatia dilatada idiopática em dois (29%) dos sete pacientes estudados. Cinco pacientes eram do sexo masculino. A idade variou entre 34 e 54 anos (média de 39,5 anos). A assistência circulatória mecânica ao ventrículo esquerdo foi mantida nos 7 pacientes por períodos que variaram de 14 a 42 dias, com média de 26,2 dias. Neste período, o desempenho hemodinâmico foi adequado, sendo observada a normalização do índice cardíaco, das pressões em território pulmonar, da SVO2 e do lactato sérico. A avaliação da resposta inflamatória sistêmica demonstrou a elevação do TNF e das interleucinas, principalmente nos pacientes que evoluíram com alterações infecciosas. O transplante cardíaco foi realizado em 2 pacientes e os outros 5 faleceram em uso do DAV Incor por infecção sistêmica ou falência de múltiplos órgãos. Não ocorreram complicações relacionadas ao DAV em 6 pacientes nos primeiros 30 dias de seguimento. Um paciente apresentou episódio de acidente vascular cerebral extenso aos 26 dias de pós-operatório. Conclusões: Os resultados deste estudo demonstram que, apesar do alto índice de complicações apresentado pelos pacientes, a assistência circulatória mecânica ao ventrículo esquerdo pode ser realizada como ponte para transplante cardíaco em nosso meio.Cardiac transplantation faces a serious problem of lack of donation. Between 20 and 40% of the listed patients died while waiting for heart transplantation, most of them because of progressive heart failure. For these patients, the use of mechanical circulatory assist devices is the only choice of surviving during that time. In Brazil, the experience with mechanical circulatory support is limited and there is no regular program of the use of these devices as bridge to heart transplantation. Objectives: To evaluate the hemodynamic performance and the systemic inflammatory response during the clinical application of the ventricular assist device type InCor (DAV-InCor) as bridge to heart transplantation. Methods: Between October 2003 and April 2006, 11 patients on the waiting list for heart transplantation have hemodynamic deterioration to refractory cardiogenic shock. Hemodinamic profile (cardiac index, capilar pressure, pulmonary artery pressure and central venous pressure) was analised during early post-operative days. Serum levels of central venous saturation, lactate, urea, creatinin, bilirrubin and lacti desidrogenase were measured every day Blood drawn from patients for 3 days and once a week was assayed for levels of BNP, interleukin 6, interleukin 8, and tumor necrosis factor-alfa. Results: During the study, 11 patients listed for cardiac transplantation as urgent status have deteriorated to refractory cardiogenic shock. Seven of these patients were submitted to DAV-InCor implantation for left ventricular assistance. The etiologic diagnosis was Chagas\' disease in 5 patients (71%) and idiopathic dilated cardiomyopathy in 2 (29%). There were 5 male and 2 female. The age ranged from 34 and 54 years (mean 39,5). Duration of left ventricular assistance ranged from 14 to 42 days (mean 26.2 days). During this period, the hemodynamic performance of the DAV-InCor was adequate to support a normal hemodynamic condition. There was normalization of cardiac index, central venous oxygen saturation and serum lactate. The systemic inflammatory response showed elevated TNF-alfa, Interleukin-6 and interleukin-8 concentrations. Two patients were submitted to heart transplantation, while the other 5 patients died under assistance due to infection and multiple organ failure. There were no complications related to the device in 6 patients. One patient had a stroke by the 26st day Conclusions: Mechanical circulatory support can be performed as bridge to heart transplantation with the DAV-InCor, in spite of the high incidence of complications.
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Barutcu, Burcu. "The Design And Production Of Interference Edge Filters With Plasma Ion Assisted Deposition Technique For A Space Camera." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614574/index.pdf.
Повний текст джерелаАнотація:
Interference filters are multilayer thin film devices. They use interference effects between
the incident and reflected radiation waves at each layer interface to select wavelengths. The
production of interference filters depend on the precise deposition of thin material layers on
substrates which have suitable optical properties. In this thesis, the main target is to design
and produce two optical filters (short-pass filter and long-pass filter) for the CCDs that will
be used in the electronics of a space camera. By means of these filters, it is possible to take
image in different bands (RGB and NIR) by identical two CCDs. The filters will be fabricated
by plasma ion-assisted deposition technique.
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Parrish, Janet Yvonne. "Using the computer to motivate at-risk students as writers." CSUSB ScholarWorks, 1997. https://scholarworks.lib.csusb.edu/etd-project/1437.
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Xiang, Wanlin. "Design of a new grab bar for older adults." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/48942.
Повний текст джерелаАнотація:
Toilet grab bars were intended to facilitate independent and safe toilet transfer for people with different abilities. However, standard grab bars require too much effort from older adults who typically transfer to the toilet in a standing position rather than a sitting position. Among existing grab bars, grab bars on both sides of the toilet worked best for older adults because they allowed older adults to use both arms to get on and off the toilet. However, based on our observation, these grab bars were not effective to assist older adults to get in and out of the wheelchair. Additionally, these grab bars are too far apart that older adults have to use their shoulders rather than arms, which arise problems because shoulder are typically weaker than arms. This study intends to solve this problem by developing a new grab bar which would be safer, easier and more comfortable to use. Based on the literature review, analysis of existing grab bars and observation, a new concept of grab bars was generated and a functional prototype was constructed for user testing. The prototype was proved to be safe, easy and comfortable to use in the entire transfer process and it reduced the use of wheelchairs as well.
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Mamugudubi, Khathutshelo Stephen. "Learning and the use of smart phone devices : an experimental case study in a Gauteng secondary school." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86559.
Повний текст джерелаАнотація:
Thesis (MPhil)--Stellenbosch University, 2014.ENGLISH ABSTRACT: The purpose of this project was to investigate the prospects to advance and fast-track formal learning with the aid of smart phone technology, as learning should be reinforced through varied, pliable assets for engagement. The project’s introduction clarifies more on this. Chapter two focuses on literature review. Previous studies which are related to the topic were consulted to acquaint the researcher with thoughts and sentiments relating to the use of smart mobile devices in advancing learning. Chapter three covers comprehension centred learning. It pays special attention to the theories of Barret and Bloom which are used as the framework for the experiment reported on in the next chapters. Chapter four provides methodological background to the experiment. It describes the case study, curriculum correlation with smart phone functions, the organisation and analysis of the data, ethical issues in qualitative interviewing, and limitations of the empirical study. Chapter five focuses on the experiment that was carried out to investigate the usefulness of smartphones to support and enhance formal comprehension strategies. Sub-types from Barrett’s five learning types and Bloom’s cognitive dimensions of learning provide the interpretive framework. Chapter six discusses the findings of the experiment based on written and oral responses by participants after conclusion of the experiment, as well as teacher observations. Finally, Chapter seven presents the conclusion and implications.
AFRIKAANSE OPSOMMING: Die doel van hierdie projek was om die moontlikhede te ondersoek om formele leer aan te help en te bespoedig deur gebruikmaking van “smart phones.” Die aanname was dat dit ‘n groter verskeidenheid en buisaamheid van leerervarings behels. Die inleidende hoofstuk brei hierop uit. Hoofstuk 2 dek relevant literatuur oor studies met betrekking tot die gebruik van “smart” mobiele apparate Hoofstuk 3 handel oor begripsgesentreerde leer. Dit gee besondere aandag aan die teorieë van Barret en Bloom wat die raamwerk daarstel vir die ekspriment wat in die volgende hoofstukke beskryf word. Hoofstuk 4 bied die metodologiese agtergrond vir die eksperiment. Dit beskryf die gevallestudie, kurrikulum korrelasie met “smart phone” funksies, die organisasie en analise van die data, etiese aspekte van onderhoudvoering, en die beperkinge van die empiriese studie. Hoofstuk 5 fokus op die eksperiment wat uitgevoer is om die bruikbaarheid van “smartphones” te ondersoek met betrekking tot steun en bevordering van formele begripsgesentreerde leer. Sub-tipes van Barret se vyf leertipes, en Bloom se kognitiewe dimensies van leer bied die interpretatiewe raamwek. Hoofstuk 6 bespreek die resultate van die eksperiment na aanleiding van geskrewe en mondelinge terugvoer deur die deelnemers na afloop van die eksperiment, asook observasie deur die onderwyser. Hoofstuk 7 bespreek enkele implikasies en gevolgtrekkings van die studie.
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Baeza, Mario Enrique. "The influence of behavior modeling and experience on the acquisition of computer skills." CSUSB ScholarWorks, 1990. https://scholarworks.lib.csusb.edu/etd-project/588.
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Decroo, Kenneth Louis. "Creating a student accessible online syllabus." CSUSB ScholarWorks, 2001. https://scholarworks.lib.csusb.edu/etd-project/1737.
Повний текст джерелаАнотація:
This project addresses how to create an online syllabus that is accessible to students and parents, that empowers students to take responsibility for their own learning while enhancing school/home communication, and serves as a graphic representation of what students have accomplished. Web quests are used as the principle means of instructional delivery to engage middle school students in problem-based projects that address real life situations using rigorous and relevant curricula. Elements of an online syllabus and the content of the course it supports are examined. The role, an online syllabus plays in fulfilling the goals of techno-constructivism, the move from a top down, broadcast model toa decentralized, constructivism model of instructional delivery is addressed.
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Morales, Marcelo Mecchi. "Modelagem matemática da fluidodinâmica não-newtoniana e bifásica simplificada da hemólise induzida mecanicamente em sistemas de bombeamento centrífugo de sangue." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/98/98131/tde-09012018-075451/.
Повний текст джерелаАнотація:
A hemólise induzida mecanicamente em sistemas de bombeamento centrífugo é um processo complexo para o qual ainda se almeja um modelo matemático que possa auxiliar eficazmente o desenvolvimento e otimização destes dispositivos médicos. Este trabalho propõe um equacionamento matemático do escoamento do fluido sanguíneo no interior de bombas centrífugas, levando-se em consideração as variações do campo de tensões através de uma abordagem reológica não-newtoniana. A destruição da fase globular é modelada matematicamente por uma distribuição estatística. Tal modelo bifásico simplificado é utilizado em simulações numéricas de experimentos virtuais propostos e padronizados pela comunidade científica internacional especializada. A validação do modelo é realizada através de comparação com resultados referenciais. Os resultados obtidos demonstram um nova possibilidade de solução numérico-computacional para o problema da hemólise por trauma mecânico.Mechanically induced hemolysis in centrifugal pumping systems is a complex process for which a mathematical model is still desired. It can effectively aid the development and optimization of these medical devices. This work proposes a mathematical modeling for the blood flow into centrifugal pumps, taking into account the variations of the stress field through a non-Newtonian rheological approach. The destruction of the globular phase is mathematically modeled by a statistical distribution. Such a simplified two-phase model is used in numerical simulations of virtual experiments proposed and standardized by the international scientific community. The validation of the model is performed through comparison with reference results. The results obtained show a new mathematical solution for the problem of hemolysis induced by mechanical trauma.
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Motala, Tasneem. "Towards a better understanding of how to implement technology projects at rural primary schools : a case study." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97351.
Повний текст джерелаАнотація:
Thesis (MBA)--Stellenbosch University, 2015.ENGLISH ABSTRACT: In South Africa, an increased effort is being made to integrate the use of technology into the public education system, as technology has proved to be beneficial to both teachers and learners. Technologies introduced in schools are not always adopted equally by all educators. There are differences in both the rate at which the technology is adopted, as well as differences in the extent to which each teacher is willing to integrate the technology into the classroom. iSchoolAfrica has extensive experience in the successful roll out and implementation of technology at schools. The objective of the research was to study iSchoolAfrica’s implementation approach, with a focus on educator engagement, to enable the generation of a set of guidelines that can be used by service providers who implement similar projects in the future. A secondary objective was to understand the reasons for resistance towards technology. Primary data was obtained via interviews with iSchoolAfrica employees. In order to include the views of a set of end-users and possibly the primary stakeholders in such projects, this study offers input from teachers at a school where iSchoolAfrica implemented a technology program. The attributes of a school have a significant impact on the success or failure of a technology project. Implementers must have a deep understanding of the management of the school and the challenges that the school faces before they undertake any technology projects. Resistance from teachers towards a technology change initiative arises for a variety of intrinsic and extrinsic reasons. The main reason why teachers tend to be unwilling to adopt new technology is their lack of self-confidence in terms of their competency in using the technology. Teachers are also overwhelmed by their existing workload and may resist a technology change that they feel adds to their workload. There is also a high probability of resistance from teachers who integrate technology into lessons under duress, after exposure to inadequate training programs. Appropriate training is the primary measure used to counter potential resistance. This training should not only focus on device usage, but rather on pedagogical practices so that teachers understand how to integrate the technology into existing lessons. The role of a facilitator is also important. Although facilitators lead the training effort, they also assume a supportive role and guide the teachers through their adjustment to technology. Although resistance towards change is expected, an implementer can take proactive measures to minimise this resistance and thereby increase the probability of success of the project.
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Hamdani, Hamid. "Métamodèles pour l’étude fiabiliste des systèmes mécatroniques Métamodélisation pour une conception robuste des systèmes mécatroniques Reliability analysis of tape based chip-scale packages based metamodel Optimization of solder joints in embedded mechatronic systemsvia Kriging-assisted CMA-ES algorithm Metamodel assisted evolution strategies for global optimization of solder joints reliability in embedded mechatronic devices." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMIR12.
Повний текст джерелаАнотація:
Les défaillances des systèmes mécatroniques sont souvent causées par la rupture par fatigue des joints de brasure de ses composants électroniques. Avec la miniaturisation croissante des boîtiers électroniques, la sollicitation des joints de brasure, qui assurent la liaison entre les sorties du composant et la carte, peut devenir problématique. En effet, les joints de brasures peuvent accepter des taux de déformation importants, mais une accumulation des sollicitations répétées provoquent leur vieillissement prématuré pouvant conduire à la rupture de joints brasés (phénomène de fatigue thermomécanique). Ainsi, les études basées sur la simulation par les méthodes des éléments finis sont menées pour étudier numériquement la durée de vie des boîtiers montés sur circuit imprimé (fiabilité de deuxième niveau). Le coût de calcul élevé de la résolution de ce type de problèmes peut rendre la procédure d’optimisation et d’évaluation de la fiabilité irréalisable en raison de la grande consommation de temps de calcul de la simulation multiphysique par la méthode des éléments finis. Cette thèse propose d’une part, une adaptation de la méthode CMA-ES Assisté par le métamodèle de krigeage pour l’optimisation globale d’un problème. La mise en œuvre de cet algorithme proposé a été réalisée dans l’optimisation globale des joints de brasure d’un boîtier de type PQFP. Les résultats des études numériques montrent que l’algorithme KA-CMA-ES proposé est plus efficace et plus performant que l’algorithme CMA-ES standard. D’autre part, une méthodologie générale pour l’analyse de la fiabilité en fatigue est proposée dans ce manuscrit. Elle s’appuie sur la modélisation des incertitudes (chargement, propriétés du matériau, géométrie) et vise à quantifier le niveau de fiabilité du système étudié pour un scénario de défaillance en fatigue. Une méthode basée sur les techniques de métamodélisation est précisément proposée pour remédier à la complexité des systèmes mécatroniques dans la résolution du problème de fiabilité. Le métamodèle est utilisé pour imiter le comportement du modèle mécanique tout en satisfaisant en même temps l’efficacité et la précision de ce dernier. La mise en œuvre de cette méthodologie est appliquée pour l’analyse de fiabilité d’un boîtier de type T-CSPMechatronic system failures are often caused by fatigue failure of the solder joints of its electronic devices. With the increasing miniaturization of electronic devices, the stress on solder joints, which provide the connection between the component outputs and the PCB, has become a major challenge. Indeed, solder joints can accept high deformation rates, but an accumulation of repeated stresses causes their premature ageing which can lead to the rupture of solder joints (thermomechanical fatigue phenomenon). Thus, the studies based on finite element simulation methods are performed to numerically investigate the lifetime of PCB-mounted devices (secondlevel reliability). The high computational costs required to solve such problems may make the optimization and reliability assessment procedure impracticable due to the high computation time of multi-physics finite element simulation. This thesis proposes on the one side, an adaptation of the CMA-ES method Assisted by the kriging metamodel for the global optimization of a given problem. The implementation of this proposed algorithm was performed in the global optimization of the solder joints in a PQFP package. The results of the numerical studies show that the proposed KA-CMA-ES algorithm is more efficient and more efficient than the standard CMA-ES algorithm. On the other side, a general methodology for reliability analysis in fatigue is proposed in this manuscript. It is based on the uncertainty modeling (loading, material properties, geometry) and aims to quantify the reliability level of the system studied for a fatigue failure scenario. A method based on metamodelling techniques is precisely proposed to address the complexity of mechatronic systems in solving the reliability problem. The metamodel is used to emulate the mechanical model behaviour while satisfying both the its efficiency and accuracy. The implementation of the proposed methodology is applied for the reliability analysis of a T-CSP package
46
Chan, Sau-chuen Jenny, and 陳秀川. "Wireless technology use in schools to support student learning." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B27741655.
Повний текст джерела
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Lemoncello, Richard R. "A within-subjects experimental evaluation of the Television Assisted Prompting (TAP) system to maximize completion of home-delivered swallow strengthening exercises among individuals with co-occurring acquired swallowing and cognitive impairments." Thesis, Connect to title online (Scholars' Bank) Connect to title online (ProQuest), 2008. http://hdl.handle.net/1794/8948.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--University of Oregon, 2008.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 150-162). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.
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Uyoata, Uyoata Etuk. "Relay assisted device-to-device communication with channel uncertainty." Doctoral thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/31309.
Повний текст джерелаАнотація:
The gains of direct communication between user equipment in a network may not be fully realised due to the separation between the user equipment and due to the fading that the channel between these user equipment experiences. In order to fully realise the gains that direct (device-to-device) communication promises, idle user equipment can be exploited to serve as relays to enforce device-to-device communication. The availability of potential relay user equipment creates a problem: a way to select the relay user equipment. Moreover, unlike infrastructure relays, user equipment are carried around by people and these users are self-interested. Thus the problem of relay selection goes beyond choosing which device to assist in relayed communication but catering for user self-interest. Another problem in wireless communication is the unavailability of perfect channel state information. This reality creates uncertainty in the channel and so in designing selection algorithms, channel uncertainty awareness needs to be a consideration. Therefore the work in this thesis considers the design of relay user equipment selection algorithms that are not only device centric but that are relay user equipment centric. Furthermore, the designed algorithms are channel uncertainty aware. Firstly, a stable matching based relay user equipment selection algorithm is put forward for underlay device-to-device communication. A channel uncertainty aware approach is proposed to cater to imperfect channel state information at the devices. The algorithm is combined with a rate based mode selection algorithm. Next, to cater to the queue state at the relay user equipment, a cross-layer selection algorithm is proposed for a twoway decode and forward relay set up. The algorithm proposed employs deterministic uncertainty constraint in the interference channel, solving the selection algorithm in a heuristic fashion. Then a cluster head selection algorithm is proposed for device-to-device group communication constrained by channel uncertainty in the interference channel. The formulated rate maximization problem is solved for deterministic and probabilistic constraint scenarios, and the problem extended to a multiple-input single-out scenario for which robust beamforming was designed. Finally, relay utility and social distance based selection algorithms are proposed for full duplex decode and forward device-to-device communication set up. A worst-case approach is proposed for a full channel uncertainty scenario. The results from computer simulations indicate that the proposed algorithms offer spectral efficiency, fairness and energy efficiency gains. The results also showed clearly the deterioration in the performance of networks when perfect channel state information is assumed.
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Whiteford, Justin James. "LaunchPad: Using students-owned computers in the classroom." CSUSB ScholarWorks, 2002. https://scholarworks.lib.csusb.edu/etd-project/2206.
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Kai, Yuan. "Resource management for cellular-assisted device-to-device (D2D) communications." Thesis, University of Kent, 2018. https://kar.kent.ac.uk/66874/.
Повний текст джерелаАнотація:
Device-to-Device (D2D) communication has become a promising candidate for future wireless communication systems to improve the system spectral efficiency, while reducing the latency and energy consumption of individual communication. With the assistance of cellular network, D2D communications can greatly reduce the transmit distance by utilizing the spatial dispersive nature of ever increasing user devices. Further, substantial spectrum reuse gain can be achieved due to the short transmit distance of D2D communication. It, however, significantly complicates the resource management and performance analysis of D2D communication underlaid cellular networks. Despite an increasing amount of academic attention and industrial interests, how to evaluate the system performance advantages of D2D communications with resource management remains largely unknown. On account of the proximity requirement of D2D communication, the resource management of D2D communication generally consists of admission access control and resource allocation. Resource allocation of cellular assisted D2D communications is very challenging when frequency reuse is considered among multiple D2D pairs within a cell, as intense inter D2D interference is difficult to tackle and generally causes extremely large amount of signaling overheads for channel state information (CSI) acquisition. Hence, the first part of this thesis is devoted to the resource allocation of cellular assisted D2D communication and the performance analysis. A novel resource allocation scheme for cellular assisted D2D communication is developed with low signaling overhead, while maintaining high spectral efficiency. By utilizing the spatial dispersive nature of D2D pairs, a geography-based sub-cell division strategy is proposed to group the D2D pairs into multiple disjoint clusters, and sub-cell resource allocation is performed independently for the D2D pairs within each sub-cell without the need of any prior knowledge of inter D2D interference. Under the proposed resource allocation scheme, tractable approximation for the inter D2D interference modeling is obtained and a computationally efficient expression for the average ergodic sum capacity of the cell is derived. The expression further allows us to obtain the optimal number of sub-cells that maximizes the average ergodic sum capacity of the cell. It is shown that with small CSI feedback, the system capacity/spectral efficiency can be improved significantly by adopting the proposed resource allocation scheme, especially in dense D2D deployment scenario. The investigation of use cases for cellular assisted D2D communication is another important topic which has direct effect on the performance evaluation of D2D communication. Thanks to the spatial dispersive nature of devices, D2D communication can be utilized to harvest the vast amount of the idle computation power and storage space distributed at the devices, which yields sufficient capacities for performing computation-intensive and latency-critical tasks. Therefore, the second part of this thesis focuses on the D2D communication assisted Mobile Edge Computing (MEC) network. The admission access control of D2D communication is determined by both disciplines of mobile computing and wireless communications. Specifically, the energy minimization problem in D2D assisted MEC networks is addressed with the latency constraint of each individual task and the computing resource constraint of each computing entity. The energy minimization problem is formed as a two-stage optimization problem. At the first stage, an initial feasibility problem is formed to maximize the number of executed tasks, and the global energy minimization problem is tackled in the second stage while maintaining the maximum number of executed tasks. Both of the optimization problems in two stages are NP-hard, therefore a low-complexity algorithm is developed for the initial feasibility problem with a supplementary algorithm further proposed for energy minimization. Simulation results demonstrate the near-optimal performance of the proposed algorithms and the fact that the number of executed tasks is greatly increased and the energy consumption per executed task is significantly reduced with the assistance of D2D communication in MEC networks, especially in dense user scenario.