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1
Xue, Xin. "Health monitoring of drive connected three-phase induction motors from wired towards wireless sensor networks /." Diss., [Riverside, Calif.] : University of California, Riverside, 2009. http://proquest.umi.com/pqdweb?index=0&did=1899497101&SrchMode=2&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1269019645&clientId=48051.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--University of California, Riverside, 2009.Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 20, 2010). Includes bibliographical references. Also issued in print.
2
Zhu, Xi. "High frequency CMOS integrated filters for computer hard disk drive and wireless communication systems." Thesis, University of Hertfordshire, 2008. http://hdl.handle.net/2299/2069.
Повний текст джерелаАнотація:
Operational transconductance amplifier and capacitor (OTA-C) filters have outstood among different types of filter due to high frequency and low power capabilities in the main stream digital CMOS technology. They have been widely used in computer hard disk drive (HDD) and wireless communication transceivers. OTA-C filters based on cascade and passive ladder simulation are well-known. However, multiple loop feedback (MLF) OTA-C filters which have certain advantages still have the scope for further research. So far there have been no explicit formulas for current-mode leapfrog (LF) filter design and performance evaluation of current-mode MLF OTA-C filters are still lacking. From application viewpoints, read channels for computer hard disk drives require very high frequency continuous-time filters. This automatically disqualifies active- RC/MOSFET-C filters and OTA-C filters become the only solution. In wireless communications, active-RC/MOSFET-C filters have been proved useful for mobile systems whose baseband frequency falls below a few MHz. However, for wireless LANs with the frequency of several tens of MHz, OTA-C filters are a strong candidate. Whilst in HDD read channels, cascaded OTA-C architectures have been most utilized and in wireless receivers, OTA-C structures based on ladder simulation have been popular, MLF OTA-C filters have not been practically used in either of the applications. This thesis describes some novel designs and applications of multiple loop feedback OTA-C filters with extensive CMOS simulations. Analogue filters for computer hard disk drive systems are first reviewed; the state of the art and design considerations are provided. Three VHF linear phase lowpass OTA-C filters are then designed, which include a seventh-order and a fifth-order current-mode filter based on the follow-the-leader-feedback (FLF) structure and a seventh-order voltage-mode filter using the inverse FLF (IFLF) configuration. These filters all have very low power consumption. The synthesis and design of general current-mode LF OTA-C filters are conducted next. Iterative design formulas for both all-pole and finite-zero functions are derived and explicit formulas for up to sixth-orders are given. These formulas are very easy to use for designing any type of characteristics. Subsequently, linear phase lowpass OTA-C filter design for HDD read channels using LF structures are investigated in details. A current-mode filter and a voltage-mode filter using the fifth-order LF structure are presented. The two filters can operate up to 800MHz and have very small passband phase ripple. Analogue filters for wireless communication baseband applications are also reviewed thoroughly in this thesis, where the design of a fourth-order current-mode FLF Butterworth lowpass OTA-C filter for multi-standard receivers is presented. Then two fifth-order current-mode elliptic lowpass OTA-C filters based on respective LF and FLF structures for wireless communication baseband are designed. Fifth-order voltage-mode IFLF and LF elliptic lowpass filters are also presented. All these MLF baseband filters designed can operate up to 40MHz to cover all important wireless and mobile standards. Simulations show that the LF structures have better dynamic range and stopband attenuation performances than the FLF and IFLF configurations.
3
Huo, Xueliang. "Tongue drive: a wireless tongue-operated assistive technology for people with severe disabilities." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45887.
Повний текст джерелаАнотація:
The main objective of the presented research is to design, fabricate, fully characterize, and assess the usability and functionality of a novel wireless tongue-operated assistive technology, called Tongue Drive System (TDS), that allows individuals with severe physical disabilities (such as quadriplegics) to effectively access computers, drive powered wheelchairs, and control environments using their voluntary tongue motion. The system can wirelessly detect users' tongue movements using an array of magnetic sensors, and a magnetic tracer secured on the tongue, and translate them into a set of user-defined commands in real time, which can then be used to communicate with target devices in users' environment. The principal advantage of the TDS is that a combination of magnetic sensors and a small permanent magnet can capture a large number of tongue movements, each of which can represent one specific command. A set of dedicated tongue movements can be configured as specific commands for each individual user based on his/her preferences, lifestyle, and remaining abilities. As a result, this technology can benefit a wide range of potential users with different types of disabilities.
The work carried out in this dissertation is largely split into three portions: (1) Development, fabrication and characterization of external TDS (eTDS) prototypes to verify the concept of TDS that is detecting and extracting user's intention through their voluntary tongue motion, utilizing a combination of magnetic sensors and a small magnet, as well as the application of this idea in the context of assistive technology. This part of the work is presented in Chapters IV, V and VI. (2) Assessment of the TDS performance in medium term usage for both computer access and wheelchair control. The main purpose of this work was to gain valuable insight into the TDS learning process and its current limiting factors, which could lead the way in designing new generations of TDS with improved usability. This portion of the work is described in Chapter VII. (3) Development and performance assessment of a multimodal TDS (mTDS), that operates based on the information collected from two independent input channels: the tongue motion and speech. This multimodal system expands the access beyond one input channel and therefore improves the speed of access by increasing the information transfer bandwidth between users and computers. This part of the work is presented in Chapters VIII and IX.
This dissertation has contributed to the innovation and advancement of the start-of-the-art assistive technology research by exploring, realizing and validating the use of tongue motion as a voluntary motor output to substitute some of the lost arm and hand functions in people with severe disabilities for computer access, wheelchair navigation, and environmental control.
4
Famoriyo, Olusola. "THE EVALUATION OF TINYOS WITH WIRELESS SENSOR NODE OPERATING SYSTEMS." Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-886.
Повний текст джерелаАнотація:
Wireless Sensor nodes fall somewhere in between the single application devices that do
not need an operating system, and the more capable, general purpose devices with the
resources to run a traditional embedded operating system. Sensor node operating system
such as TinyOS, Contiki, MantisOS and SOS which is discussed in this paper exhibit
characteristics of both traditional embedded systems and general-purpose operating systems
providing a limited number of common services for application developers linking
software and hardware.
These common services typically include platform support, hardware management of sensors,
radios, and I/O buses and application construction etc. They also provide services
needed by applications which include task coordination, power management, adaptation
to resource constraints, and networking. The evaluation was concentrated on TinyOS
including an analysis on version 1.x and 2.x resource management and flexibility and its
operation with the other wireless sensor node operating systems.
5
Devarakond, Shyam Kumar. "Signature driven low cost test, diagnosis and tuning of wireless systems." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47594.
Повний текст джерелаАнотація:
With increased and varied performance demands, it is essential that complex multi-standard radio/systems coexist on a same chip. To have cost and performance benefits, these analog/RF systems are implemented in scaled nanometer nodes. At these nodes, the high level of variability in process variations is making the task of manufacturing high fidelity systems a challenge leading to yield and reliability issues. Hence, in the post-manufacturing phase, test and diagnosis steps are critical to identify the cause and effect of the process variations. Further, intelligent post-manufacturing tuning techniques are required to correct the effect of process variations on analog/RF systems. In this work, a die-level concurrent test and diagnosis approach using optimized measurements obtained in high volume manufacturing environment is proposed for analog/RF circuits. Such a simultaneous test and diagnosis methodology enables monitoring parametric process shifts and providing rapid feedback to the fab to minimize or prevent yield loss. In the case of devices that are continuously operating in the field, an efficient on-line diagnosis approach has been developed to perform reliability related prognosis. For advanced RF technologies such as MIMO-OFDM systems, a rapid system-level testing scheme is presented that performs concurrent testing of the multiple RF chains. Depending on the availability of the computational resources and system tuning knobs, different low-cost methodologies for post-manufacture tuning or self-healing of RF SISO/MIMO systems are developed. These include faster digital monitoring and tuning techniques, on-chip tuning techniques using digital logic that enables die-level self-tuning, and DSP-based power conscious iterative techniques for SISO/MIMO RF systems. An adaptive power-performance tuning technique is developed for those devices that have a post-manufacture power consumption value that is more than the acceptable limit. These intelligent post-manufacturing techniques result in reduced manufacturing cost, improved yield, and reliability of analog/RF systems.
6
Salman, A. "Reducing complexity in developing wireless sensor network systems using model-driven development." Thesis, University of Salford, 2017. http://usir.salford.ac.uk/44127/.
Повний текст джерелаАнотація:
Wireless Sensor Network (WSN) is a collection of small and low-powered gadgets called sensor nodes (motes), which are capable of sensing the environment, collecting and processing the sensed data, and communicating with each other to accomplish a specific task. Moreover, all sensed and processed data are finally handed over to a central gathering point called a base station (sink), where all collected data are stored and can be reviewed by the user. Most of the current methods concerning WSN development are application or platform-dependent; hence it is not a trivial task to reuse developed applications in another environment. Therefore, WSN application development is a challenging and complex task because of the low-level technical details and programming complexity. Furthermore, most WSN development projects are managed by software engineers, not application field experts or WSN end users. Consequently, WSN solutions are considered expensive, due to the amount of effort that has to be put into these projects. This research project aims to reduce the complexity in developing WSN applications, by abstracting the low-level technical and programming details for average developers and domain experts. In this research, we argue that reducing complexity can be achieved by defining a new Domain-Specific Language (DSL) as a new application development and programming abstraction, which supports multi-levels modelling (i.e. network, group, and node-level). The outcome of this work is the definition of a new language called SenNet, which is an open source DSL programming abstraction that enables application developers to concentrate on the high-level application logic rather than the low-level complex details. SenNet was developed using the principles of Model-Driven Development (MDD) and macro-programming. Developers can use SenNet as a high-level programming abstraction to auto-generate a ready-to-deploy single node nesC code for all sensor nodes that comprise the SenNet application. SenNet gives developers the flexibility they need by offering them a broad range of predefined monitoring tasks and activities, enabling developers to develop different application types such as Sense-Forward (SF), and Event-Triggered (ET); besides providing a set of node-level and in-network data processing tasks. The current SenNet version is configured to generate nesC code, yet SenNet can be set up to produce and generate any programming language such as Java, or C++, by reconfiguring the code generator to produce the new language format, without changing the language design and produced semantics. Various tests and user study have been used to evaluate SenNet’s usability and functional suitability. Evaluation results found that SenNet could save 88.45% of the LOC required to be programmed by a developer, and 87.14% of the required vocabularies. Furthermore, results showed that SenNet could save 92.86% and 96.47% of the program length and volume respectively. Most of the user study participants (96%) found SenNet to be usable and helps to achieve the required WSN application with reduced development effort. Moreover, 82% of the participants believe that SenNet is functionally suitable for WSN application development. Two real-world business case studies developed were used to assess SenNet’s appropriateness to develop WSN real applications, and how it can be used to develop applications related to data processing tasks. Based on the final evaluation results, it can be concluded that our research has been successful in introducing SenNet as a new abstraction to reduce complexity in the WSN application development process.
7
Khan, Zeashan Hameed. "Wireless network architecture for long range teleoperation of an autonomous System." Grenoble INPG, 2010. http://www.theses.fr/2010INPG0134.
Повний текст джерелаАнотація:
La téléopération en réseau est une thématique émergente, où un humain (le maître) communique avec un esclave commandé à distance à travers un réseau de communication, pour l'échange des données de commande et de mesure. Pour la téléopération longue distance, ces informations traversent divers réseaux hétérogènes ou hybrides interconnectés ensemble. Nous traitons également le cas où un segment sera sans fil, ce qui permet d'envisager que l'esclave soit mobile (véhicule télé-opéré par exemple). Une étude indépendante des aspects commande et des aspects réseau entraîne l'atteinte d'objectifs locaux, qui peuvent le cas échéant être ensuite fortement dégradés après l'intégration des deux aspects. L'utilisation de réseaux partagés, comme internet, en lieu et place d'une liaison dédiée (point à point, liaison virtuelle) est également un défi, en particulier dans le cas de la longue distance. Les mécanismes de qualité de service (QdS) d'un réseau, en particulier du réseau hétérogène, doivent pouvoir être traités par les autres réseaux ; ces points sont assez souvent traités avec un point de vue d'applications multimedia, plus rarement avec le point de vue de la téléopération critique. L'approche de téléopération en réseau peut profiter de ces mécanismes de qualité de service en utilisant des priorités ou des réservations de bandes passantes en fonction des critères de commande et de transparence. Cela peut entraîner une adaptation des ressources réseau en fonction des besoins des objectifs de téléopération afin de transporter l'information en satisfaisant les besoins bout en bout de l'application, cette notion devant être précisée. Lorsqu'on considère la QdS avec un point de vue réseau, elle consiste principalement à la gestion de flux de communication, en prenant en compte des paramètres de besoin et d'ordonnancement. Si l'on prend en compte le point de vue de la téléopération, la QdS entraîne des conséquences sur la qualité de commande (QdC) ce qui inclut la stabilité, la transparence et la téléprésence. De plus, l'interface humaine peut également avoir des besoins spécifiques en termes de téléprésence, ce qui peut entraîner des conséquences sur la répartition de la charge du réseau. Afin d'intégrer les deux approches de QdS et de QdC pour apporter une meilleure réponse au problème posé, nous proposons une approche de coconception avec d'une part une adaptation de la QdS aux besoins de la Qdc (qualité de la transparence) et d'autre part une adaptation de la Qdc (par exemple dégradation de la qualité du flux vidéo) à la disponibilité du réseau. Nous avons considéré deux cas de figures. Dans un premier temps, sans tenir compte des mécanismes de QdS du réseau (approche dite du meilleur effort ou best effort) et par l'adaptation au mieux de l'application, pour répondre aux besoins de la téléopération. La seconde approche considère un réseau orienté QdS entre le maître et l'esclave, où différentes priorités peuvent être attribuées aux flux nécessaires à la téléopération, en fonction des contextes. L'approche proposée est finalement mise en oeuvre sur NeCS-Car, la voiture téléopérée disponible au LaboratoireNetworked teleoperation (NT) is an emerging area of technology, where human assisted Master and remote Slave devices communicate over a communication network for the exchange of command and sensor feedback information. For long range mobile teleoperation, this information travels over different types of heterogeneous/hybrid networks interconnected together with a compulsory network segment over wireless to permit increased mobility. The independent design of control and network promotes the isolated objectives and the performance is degraded after an integration. It is also challenging if internet is used for teleoperation, instead of point to point communication. The mechanisms of QoS in one network protocol of the heterogeneous network needs mapping on any other network which is usually carried out with a multimedia point of view and not for the critical teleoperation data. The approach for networked teleoperation can be given a new dimension by adding quality of service (QoS) to different flows on need based priority and as a function of control and transparence criteria. This means to alter the network resources for teleoperation objective in order to transport the information to satisfy the end-to-end application needs. The network QoS perspective is important to consider in the co-design approach for teleoperation. However, the true meaning of end to end QoS must be defined for teleoperation. If we consider the QoS from the network point of view, it refers to the management of various flows or users as per their need and precedence. Whereas, from the teleoperation perspective, QoS is related to the quality of control (QoC) which includes stability, transparence and telepresence. Moreover, the human interface may have different requirements as per telepresence feeling which will result in varying network load. To control network QoS, we need to measure or estimate it. Therefore, classification of QoS is performed with a fuzzy inference system which is able to distinguish between varying levels of QoS. In addition, it is also a challenging task for online decision for reconfiguration of network and control performance. We have used supervised methods for classification and prediction of QoS to be used in the proposed approach. Thus, data communication networks treat control information as best effort most of the time. Conclusion the communication used in teleoperation uses a dedicated network/communication. In short, a co-design approach is formulated to treat the network QoS as a function of teleoperation objectives which are related to the quality of transparence and control. Alternatively, the video flow is managed in order to effectively reduce the necessary throughput for instants when the network quality is not sufficient. We have considered two cases. First, without taking into account any network QoS mechanism (best effort flows only) and adapting application needs as per the teleoperation objectives. The second one considers a QoS oriented network in between the master and slave, where different priorities can be assigned to the teleoperation flows as per need. In the end, the proposed methodology is implemented on the NeCS-Car benchmark
8
Meshkova, Elena [Verfasser]. "Design and self-management of wireless networked systems with model-driven optimization / Elena Meshkova." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2015. http://d-nb.info/1076067425/34.
Повний текст джерела
9
Nadas, João Pedro Battistella. "Energy eficiente synchronization for alarm driven wireless sensor networks." Universidade Tecnológica Federal do Paraná, 2016. http://repositorio.utfpr.edu.br/jspui/handle/1/2309.
Повний текст джерелаАнотація:
Muitas aplicações de redes de sensores sem fio exigem que nós, além de monitorar certo fenômeno, devem ser capazes de detectar e comunicar eventos assíncronos (e.g. alarmes), o que implica que eles deverão ouvir o meio em modo ocioso, o que é inerentemente um desperdício de energia. Nesse cenário, sincronização de relógio é crucial para operar com eficiência em ciclos de trabalho e minimizar o consumo de energia. Nesta dissertação, avaliamos o impacto do \textit{trade-off} entre a energia gasta com sincronizações mais frequentes e, em troca reduzir a janela de escuta ociosa necessária para que a confiabilidade desejada da comunicação seja atingida. A frequência ideal de sincronizações é obtida analiticamente e corroborada por resultados numéricos, mostrando que é possível gastar uma pequena fração da energia total com uma rede com sincronização mais precisa quando comparada com a manutenção da precisão do relógio mínima exigida pelo fenômeno que está sendo monitorado, aumentando significativamente a vida útil da rede. Além disso, uma solução fechada para o limite superior a este número ideal é derivada através da aproximação de que a energia gasta para transmitir ser muito menos significativa quando comparada à gasta para receber. Usando este resultado, pudemos prever através de simulações que este número ideal será aumentado pela energia de escuta, o número de vezes que um nó precisa ouvir o meio à espera de alarmes, ao nível de confiança em que o sistema foi concebido para trabalhar, ao intervalo de sincronização e à variância da frequência de oscilação relativa entre os nós. Por outro lado, este número será menor quando o custo energético de sincronização for maior (i.e. Quando a energia de comunicação aumentar).Many applications of wireless sensor networks require that nodes, besides monitoring a given phenomenon, must be able to detect and communicate asynchronous events (e.g. alarms), implying that they have to often listen to the medium in idle mode, which is inherently energy wasteful. In such a scenario time synchronization is crucial to efficiently operate in duty-cycles and minimize energy consumption. In this work we assess the impact of the trade-off between spending energy with more frequent synchronizations and in return saving it by reducing the idle listening window necessary for the desired reliability of the communication. The optimal frequency of time synchronizations is obtained analytically and corroborated by numerical results, showing that several times less overall energy may be spent with a finer synchronization when compared with maintaining the minimum clock precision required by the phenomenon being monitored, greatly extending the life-span of the network.Furthermore, a closed form upper bound to this optimal number is derived by approximating transmit power being of much more significance when compared to receive power. Using this result, we predict and then simulate that this optimal number will be increased by the listening power, the number of times which a node has to listen to the medium idly, the level of confidence at which the system is designed to work, the synchronization interval and the variance of the relative oscillation frequency between synchronizing nodes. On the other hand, this number will be smaller when the energy cost of synchronization is higher (e.g. when active communication energy increases).
10
Crk, Igor. "Context-Aware Resource Management." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/195573.
Повний текст джерелаАнотація:
The demand for performance and resources that is placed on the system is dictated by the application alone in non-interactive environments, and by a combination of application and user interactions in interactive environments. Understanding user interaction can provide valuable information about which resources will be needed ahead of time. This leads to performance optimizations such as better resource allocations for applications that can utilize a given resource more productively, and transitioning devices to a more appropriate energy performance state before the demand arrives. The challenge is to provide a performance/energy schedule that best matches the task at hand, since keeping the device in one performance level is not energy efficient due to the continually changing demand placed on the device. This dissertation addresses the challenge of designing energy efficient systems by examining the role of user interaction in energy consumption and in providing an energy-performance schedule that adequately accommodates user demand. It is shown that system performance can be tailored to a user's pattern of interaction and it's energy-performance schedule optimized.First, a detailed design of context capture systems in Linux's X-Window System is presented with an evaluation of the associated storage and computation overheads. Due to the overall low complexity of the application window representations, the overheads of computing interaction identifiers and storing a secondary representation of the application interface within the context capture system are likewise low. Additionally, a Microsoft Windows-based context capture system leveraging the Active Accessibility framework is discussed and applied to improving the navigation of cascading pull-down menus.Secondly, this dissertation addresses the application of interaction capture in energy and delay management of Wireless Network Interface Controllers/Cards (WNICs) and hard drives. The Interaction Aware Prediction (IAP) system for WNICs is evaluated showing that the available power modes can be effectively managed to provide energy efficiency while maintaining performance. Similarly, the Interaction Aware Spin-up Prediction (IASP) uses interaction awareness to reduce or eliminate the interactive delays associated with aggressive hard disk energy management.
11
Sanli, Ozgur. "Rule-based In-network Processing For Event-driven Applications In Wireless Sensor Networks." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613389/index.pdf.
Повний текст джерелаАнотація:
Wireless sensor networks are application-specific networks that necessitate the development of specific network and information processing architectures that can meet the requirements of the applications involved. The most important challenge related to wireless sensor networks is the limited energy and computational resources of the battery powered sensor nodes. Although the central processing of information produces the most accurate results, it is not an energy-efficient method because it requires a continuous flow of raw sensor readings over the network. As communication operations are the most expensive in terms of energy usage,
the distributed processing of information is indispensable for viable deployments of applications in wireless sensor networks. This method not only helps in reducing the total amount of packets transmitted and the total energy consumed by sensor nodes, but also produces scalable and fault-tolerant networks. Another important challenge associated with wireless sensor networks is that the possibility of sensory data being imperfect and imprecise is high. The requirement of precision necessitates employing expensive mechanisms such as redundancy or use of sophisticated equipments. Therefore, approximate computing may need to be used instead of precise computing to conserve energy. This thesis presents two schemes that
distribute information processing for event-driven reactive applications, which are interested in higher-level information not in the raw sensory data of individual nodes, to appropriate
nodes in sensor networks. Furthermore, based on these schemes, a fuzzy rule-based system is proposed that handles imprecision, inherently present in sensory data.
12
Camacho, Pedro Alexandre Armas. "Front-end design for visible light communications systems." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/23477.
Повний текст джерелаАнотація:
Mestrado em Engenharia Eletrónica e TelecomunicaçõesCommunications are vital in the world today. Everything is connected and this means that communication technologies are constantly being pushed to their limits. Any kind of development and improvement that can be done to increase networks capabilities, will find use in some specific application, or even in more common technologies if such is justified. One such case is VLC, it can be used to improve other communication methods capabilities, or as standalone solution, providing advantage in certain scenarios where regular wirelesscommunicationsmethodswouldnotperformaswell,orwouldnotsuit theapplication. VLCalsooffersthegreatadvantageofutilisinganewmedium of transmission for telecomunication systems, which is the visible light spectrum, and is not yet overused and overregulated as other typical mediums. This work was done in partnership with the integrated circuit systems groupd ofInstitutodeTelecomunicaçõesAveiroandaimstostudyanddevelopoptical front end systems for VLC to be used in future projects by this group.
As Telecomunicações são fundamentais nos nossos dias em que tudo está interligado, levando as tecnologias de telecomunicações constantemente ao seu limite. Todo o tipo de melhoria que possa ser feito para melhorar o desempenho de uma rede, encontrará aplicação em alguma área, mais específica, ou caso se justifique, até mesmo em tecnologias de telecomunicação mais comuns. Um exemplo é o VLC (Visible Light Communication), que pode ser utilizado para melhorar as capacidades de outros tipos de redes de telecomunicações, ou em alternativa a outros tipos de redes, oferecendo vantagens em certos cenários onde métodos tradicionais de telecomunicações sem fios não teriam tão bom desempenho, ou não serviriam a aplicação desejada. O VLC também tem como grande vantagem a hipótese de utilização de um novo meio de transmissão para sistemas de telecomunicações, que é o espectro da luz vísivel, que não se encontra ainda sobrelotado e tem regulamentos mais relaxados que outros meios de comunicação tradicionais. Este trabalho foi feito em colaboração com o grupo de sistemas e circuitos integrados do Instituto de Telecomunicações Aveiro, e visa o estudo de desenvolvimento de ‘frontends’óticosparaVLC,parautilizaçãofuturaemprojetosporpartedeste grupo.
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Birrell, Stewart A., Daniel Wilson, Chek Pin Yang, Gunwant Dhadyalla, and Paul Jennings. "How driver behaviour and parking alignment affects inductive charging systems for electric vehicles." Elsevier, 2015. https://publish.fid-move.qucosa.de/id/qucosa%3A72829.
Повний текст джерелаАнотація:
Inductive charging, a form of wireless charging, uses an electromagnetic field to transfer energy between two objects. This emerging technology offers an alternative solution to users having to physically plug in their electric vehicle (EV) to charge. Whilst manufacturers claim inductive charging technology is market ready, the efficiency of transfer of electrical energy is highly reliant on the accurate alignment of the coils involved. Therefore understanding the issue of parking misalignment and driver behaviour is an important human factors question, and the focus of this paper. Two studies were conducted, one a retrospective analysis of 100 pre-parked vehicles, the second a dynamic study where 10 participants parked an EV aiming to align with a charging pad with no bay markings as guidance. Results from both studies suggest that drivers are more accurate at parking laterally than in the longitudinal direction, with a mean lateral distance from the centre of the bay being 12.12 and 9.57 cm (retrospective and dynamic studies respectively) compared to longitudinally 23.73 and 73.48 cm. With current inductive charging systems having typical tolerances of approximately ±10 cm from their centre point, this study has shown that only 5% of vehicles in both studies would be aligned sufficiently accurately to allow efficient transfer of electrical energy through induction.
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Murphy, Robert T. "Developing, Demonstrating, and Validating a Vehicle Test Bed to Extend the Capabilities of a Chassis Dynamometer Test System." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1226630699.
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Christmann, Dennis [Verfasser], and Reinhard [Akademischer Betreuer] Gotzhein. "Distributed Real-time Systems - Deterministic Protocols for Wireless Networks and Model-Driven Development with SDL / Dennis Christmann. Betreuer: Reinhard Gotzhein." Kaiserslautern : Technische Universität Kaiserslautern, 2015. http://d-nb.info/1073868486/34.
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Zhang, Hongwei. "Dependable messaging in wireless sensor networks." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1155607973.
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Sheerer, Corey D. "A Hand-Held Device for Controlling a Mounted, Motor-Driven Colonoscope." Ohio University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1418983633.
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Lavassani, Mehrzad. "Reliable Information Exchange in IIoT : Investigation into the Role of Data and Data-Driven Modelling." Licentiate thesis, Mittuniversitetet, Avdelningen för informationssystem och -teknologi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-34886.
Повний текст джерелаАнотація:
The concept of Industrial Internet of Things (IIoT) is the tangible building block for the realisation of the fourth industrial revolution. It should improve productivity, efficiency and reliability of industrial automation systems, leading to revenue growth in industrial scenarios. IIoT needs to encompass various disciplines and technologies to constitute an operable and harmonious system. One essential requirement for a system to exhibit such behaviour is reliable exchange of information. In industrial automation, the information life-cycle starts at the field level, with data collected by sensors, and ends at the enterprise level, where that data is processed into knowledge for business decision making. In IIoT, the process of knowledge discovery is expected to start in the lower layers of the automation hierarchy, and to cover the data exchange between the connected smart objects to perform collaborative tasks. This thesis aims to assist the comprehension of the processes for information exchange in IIoT-enabled industrial automation- in particular, how reliable exchange of information can be performed by communication systems at field level given an underlying wireless sensor technology, and how data analytics can complement the processes of various levels of the automation hierarchy. Furthermore, this work explores how an IIoT monitoring system can be designed and developed. The communication reliability is addressed by proposing a redundancy-based medium access control protocol for mission-critical applications, and analysing its performance regarding real-time and deterministic delivery. The importance of the data and the benefits of data analytics for various levels of the automation hierarchy are examined by suggesting data-driven methods for visualisation, centralised system modelling and distributed data streams modelling. The design and development of an IIoT monitoring system are addressed by proposing a novel three-layer framework that incorporates wireless sensor, fog, and cloud technologies. Moreover, an IIoT testbed system is developed to realise the proposed framework. The outcome of this study suggests that redundancy-based mechanisms improve communication reliability. However, they can also introduce drawbacks, such as poor link utilisation and limited scalability, in the context of IIoT. Data-driven methods result in enhanced readability of visualisation, and reduced necessity of the ground truth in system modelling. The results illustrate that distributed modelling can lower the negative effect of the redundancy-based mechanisms on link utilisation, by reducing the up-link traffic. Mathematical analysis reveals that introducing fog layer in the IIoT framework removes the single point of failure and enhances scalability, while meeting the latency requirements of the monitoring application. Finally, the experiment results show that the IIoT testbed works adequately and can serve for the future development and deployment of IIoT applications.SMART (Smarta system och tjänster för ett effektivt och innovativt samhälle)
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Natarajan, Vishwanath. "Self-healing RF SoCs: low cost built-in test and control driven simultaneous tuning of multiple performance metrics." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37165.
Повний текст джерелаАнотація:
The advent of deep submicron technology coupled with ever increasing demands from the customer for more functionality on a compact silicon real estate has led to a proliferation of highly complex integrated RF system-on-chip (SoC) and system-on-insulator (SoI) solutions. The use of scaled CMOS technologies for high frequency wireless applications is posing daunting technological challenges both in design and manufacturing test.
To ensure market success, manufacturers need to ensure the quality of these advanced RF devices by subjecting them to a conventional set of production test routines that are both time consuming and expensive. Typically the devices are tested for parametric specifications such as gain, linearity metrics, quadrature mismatches, phase noise, noise figure (NF) and end-to-end system level specifications such as EVM (error vector magnitude), BER (bit-error-rate) etc. Due to the reduced visibility imposed by high levels of integration, testing for parametric specifications are becoming more and more complex.
To offset the yield loss resulting from process variability effects and reliability issues in RF circuits, the use of self-healing/self-tuning mechanisms will be imperative. Such self-healing is typically implemented as a test/self-test and self-tune procedure and is applied post-manufacture. To enable this, simple test routines that can accurately diagnose complex performance parameters of the RF circuits need to be developed first. After diagnosing the performance of a complex RF system appropriate compensation techniques need to be developed to increase or restore the system performance. Moreover, the test, diagnosis and compensation approach should be low-cost with minimal hardware and software overhead to ensure that the final product is economically viable for the manufacturer.
The main components of the thesis are as follows:
1) Low-cost specification testing of advanced radio frequency front-ends:
Methodologies are developed to address the issue of test cost and test time associated with conventional production testing of advanced RF front-ends. The developed methodologies are amenable for performing self healing of RF SoCs. Test generation algorithms are developed to perform alternate test stimulus generation that includes the artifacts of test signal path such as response capture accuracy, load-board DfT etc. A novel cross loop-back methodology is developed to perform low cost system level specification testing of multi-band RF transceivers. A novel low-cost EVM testing approach is developed for production testing of wireless 802.11 OFDM front-ends. A signal transformation based model extraction technique is developed to compute multiple RF system level specifications of wireless front-ends from a single data capture. The developed techniques are low-cost and facilitate a reduction in the overall contribution of test cost towards the manufacturing cost of advanced wireless products.
2)Analog tuning methodologies for compensating wireless RF front ends:
Methodologies for performing low-cost self tuning of multiple impairments of wireless RF devices are developed. This research considers for the first time, multiple analog tuning parameters of a complete RF transceiver system (transmitter and receiver) for tuning purposes. The developed techniques are demonstrated on hardware components and behavioral models to improve the overall yield of integrated RF SoCs.
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Sadri, Seyed Mohammad Reza, of Western Sydney Nepean University, and Faculty of Engineering. "Variable reluctance motor and drive systems." THESIS_FENG_XXX_Sadri_S.xml, 1995. http://handle.uws.edu.au:8081/1959.7/427.
Повний текст джерелаАнотація:
This thesis investigates the development of a machine which is termed as singly salient reluctance (SSR) motor and its drive system. The stator of SSR motor is identical to that of a conventional induction motor or any other ac machine. Its rotor has salient poles with internal flux barriers or flux guides. This research covers the detailed designs of the SSR motors and their magnetic circuit analysis using finite element method (FEM). The parameters which are important for designing the SSR motor are investigated. This investigation resulted in designs which have low manufacturing cost as well as high torque per ampere, efficiency and power factors. This thesis also researches the different drive system for the SSR motor. The SSR motor is tested as a variable speed drive with closed loop control and supplied with dc source. Therefore for this purpose a controller system is designed and built. In addition, the SSR motor supplied by ac source using open loop control is also tested for synchronous operation. Some of the proposed designs are built and their performance compared with their predicted analysis. The SSR motors showed a competitive performance compared with equivalent induction motor in both efficiency and power factor. However the validity of the theoretical designs is assessed by comparing them with experimental results. Quite good agreement between experimental and theoretical evaluations has been achieved. In addition, suggested further improvements for SSR motors and drive systems are discussed.Doctor of Philosophy (PhD)
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Sadri, Seyed Mohammad Reza. "Variable reluctance motor and drive systems /." View thesis, 1995. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030716.150935/index.html.
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Bharadwaj, Aravind S. "Vector controlled induction motor drive systems." Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06062008-172143/.
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La, Palombara Cristina <1983>. "Cooperative Wireless Systems." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5363/.
Повний текст джерелаАнотація:
This Ph.D. dissertation reports on the work performed at the Wireless Communication Laboratory - University of Bologna and National Research Council - as well as, for six months, at the Fraunhofer Institute for Integrated Circuit (IIS) in Nürnberg. The work of this thesis is in the area of wireless communications, especially with regards to cooperative communications aspects in narrow-band and ultra-wideband systems, cooperative links characterization, network geometry, power allocation techniques,and synchronization between nodes. The underpinning of this work is devoted to developing a general framework for design and analysis of wireless cooperative communication systems, which depends on propagation environment, transmission technique, diversity method, power allocation for various scenarios and relay positions. The optimal power allocation for minimizing the bit error probability at the destination is derived. In addition, a syncronization algorithm for master-slave communications is proposed with the aim of jointly compensate the clock drift and offset of wireless nodes composing the network.
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Klomp, Matthijs. "Passenger car all-wheel drive systems analysis." Thesis, University West, Department of Technology, Mathematics and Computer Science, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-742.
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Taghirad, Hamid D. "Robust torque control of harmonic drive systems." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35427.
Повний текст джерелаАнотація:
A harmonic drive is a compact, light-weight and high-ratio torque transmission device which has almost zero backlash. Its unique performance features has captured the attention of designers in many industrial applications, especially in robotics. Despite widespread industrial application of harmonic drives, the torque control of this system has not been fully addressed. In this thesis the robust torque control of harmonic drive system is examined in detail.In order to measure the transmitted torque of a harmonic drive and for the purpose of a torque feedback scheme, an intelligent built-in torque sensing technique is developed in this thesis. Specifically, strain-gauges are mounted directly on the flexspline and therefore no extra flexible element is introduced into the system. To have maximum sensing accuracy, four Rosette strain gauges are employed using an accurate positioning method. Kalman filter estimation is employed to cancel the torque ripples, oscillations observed on the measured torque and caused mainly by gear teeth meshing. A simple forth order harmonic oscillator proved sufficient to model these torque ripples. Moreover, the error model is extended to incorporate any misalignment torque. By on-line implementation of the Kalman filter, it is shown that this method affords a fast and accurate way to filter torque ripples and misalignment torque from torque measurements.
Based on experimental and theoretical studies, a systematic way to capture and rationalize the dynamic behavior of the harmonic drive systems is developed next in this thesis. Simple and accurate models for compliance, hysteresis, and friction are proposed, and the model parameters are estimated using least-squares approximation for linear and nonlinear regression models. A statistical measure of variation is defined, by which the reliability of the estimated parameter for different operating condition, as well as the accuracy and integrity of the proposed model is quantified. By these means, it is shown that a linear stiffness model best captures the behavior of the system when combined with a good model for hysteresis. Moreover, the frictional losses of harmonic drive are modelled at both low and high velocities. The model performance is assessed by comparing simulations with the experimental results on two different harmonic drives.
Finally, robust Hinfinity -based torque controllers are designed and implemented for harmonic drive systems under constrained- and free-motion applications. A nominal model for the system is obtained in each case from ensembles of experimental frequency response estimates of the system, while the deviation of the system from the model is encapsulated by a multiplicative uncertainty. Robust Hinfinity -based torque controllers are designed using this information, and the controllers are implemented on two different setups using the Kalman filtered torque as an integral part of the torque-feedback loop. Exceptional performance results are obtained from the tune and frequency response of the closed-loop system, especially for the constrained-motion system. The further improve the performance of the free-motion system, a model-based friction-compensation algorithm is implemented in addition to the robust torque control. It is shown that the friction-compensation shrinks the model uncertainty at low frequencies. Hence, the performance of the closed-loop system is for tracking signals with low-frequency content.
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Dokht, Taghirad Hamid. "Robust torque control of harmonic drive systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0018/NQ44660.pdf.
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Costa, Fl?via Cabral da. "Uma nova proposta de antenas Quasi-Yagi banda larga para comunica??o sem fio." Universidade Federal do Rio Grande do Norte, 2009. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15276.
Повний текст джерелаАнотація:
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Previous issue date: 2009-11-17ln this work, planar quasi- Y agi antennas are investigated based on the concept of the classic Y agi_Uda antennas. These antennas represent improvements on the topologies of the antennas existing printed because they present characteristics of broad bandwidth, excellent radiation diagrams and simple construction. New configurations are adapted for the driver of the antennas, introducing patches elements into the driver. These new configurations are named Patches Elements Anteonas (PEA). This adaptation is obtained from simulations that are executed usiog the software C8T Microwave 8tudio 5. After doing the optimizations, procedures for construction and measurement ofthe prototypes are executed in order to improve the performance of the antennas in such way that they could be used in wireless communication applications, such as Bluetooth, WLAN' s and Wi-Fi. Next, the quasi- Y agi antennas are studied in order to implement them in arrangements. The arrangements construction is based 00 the best driver configuration of the antenna developed in this work. First, a linear arrangement composed by two elements of quasi?Yagi antennas is constructed in such way that the radiation characteristics and the mutual coupling effects could be analyzed. After that, a 90? angle arrangement composed by two elements is studied to observe the effect of circular polarization. Experiments are executed in order to evaluate the arrangements performance. The experimental results show that the analysis made in this work is efficient and accurate. The numerical values obtained for the analyzed parameters of each structure developed are compared with the experimental values. 80, it is possible to observe a good concordance between them. Finally, some future works proposals are presented
Neste trabalho, antenas planares quasi-Yagi s?o estudadas com base no conceito das antenas Yagi-Uda cl?ssicas. Estas antenas representam melhorias sobre as topologias das antenas impressas existentes por apresentarem caracter?sticas de banda larga, excelentes diagramas de irradia??o e constru??o simples. Novas configura??es s?o adaptadas para o driver das antenas, introduzindo elementos patches sobre o driver. Essas novas configura??es s?o chamadas de Antenas de Elementos Patches (AEP). Esta adapta??o ? obtida realizando simula??es de otimiza??o com o aux?lio do software CST Microwave Studio 5. Ap?s as otimiza??es, procedimentos para constru??o e medi??o dos prot?tipos s?o realizados com o objetivo de melhorar o desempenho das antenas para aplica??es de comunica??es sem fio, tais como Bluetooth, WLAN's e Wi-Fi. Posteriormente, as antenas quasi- Yagi s?o estudadas com o intuito de implement?-Ias em arranjos. A constru??o dos arranjos baseia-se na melhor configura??o do driver da antena desenvolvida por este trabalho. Primeiramente, um arranjo linear com dois elementos de antenas quasi-Yagi ? constru?do de tal forma que as caracter?sticas de irradia??o e o efeito do acoplamento m?tuo pudessem ser analisados. Em seguida, um arranjo composto por dois elementos dispostos sob um ?ngulo de 900 ? estudado para se observar o efeito da polariza??o circular. Experimentos s?o executados para avaliar o desempenho dos arranjos. Os resultados dos experimentos demonstram que a an?lise efetuada neste trabalho ? eficiente e precisa. Os valores num?ricos obtidos para os par?metros analisados em cada estrutura desenvolvida s?o comparados com os valores experimentais. Com isso, ? poss?vel observar uma boa concord?ncia entre eles. Por fim, algumas propostas para a realiza??o de trabalhos futuros s?o apresentadas
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Andersson, Pär, and Farkhan Jamalzadeh. "Wireless networked control systems." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-199310.
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Hanzo, L. "Adaptive wireless multimedia systems." Thesis, University of Southampton, 2004. https://eprints.soton.ac.uk/260332/.
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Jiang, Junyi. "Optical wireless communication systems." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/387239/.
Повний текст джерелаАнотація:
In recent years, Optical Wireless (OW) communication techniques have attracted substantial attention as a benefit of their abundant spectral resources in the optical domain, which is a potential solution for satisfying the ever-increasing demand for increased wireless capacity in the conventional Radio Frequency (RF) band. Motivated by the emerging techniques and applications of OW communication, the Institute of Electrical and Electronics Engineers (IEEE) had released the IEEE standard 802.15.7 for short-range optical wireless communications, which categorised the Physical layer (PHY) of the OW communication into three candidate-solutions according to their advantages in different applications and environments: 1) Physical-layer I (PHY I): Free Space Optical (FSO)communication employs high-intensity Light Emitting Diodes (LEDs) or Laser Diodes (LDs) as its transmitter. 2) Physical-layer II (PHY II) uses cost-effective, low-power directional white LEDs for the dual function of illumination and communication. 3) Physical III (PHY-III) relies on the so-called Colour-Shift Keying (CSK) modulation scheme for supporting high-rate communication. Our investigations can be classified into three major categories, namely Optical Orthogonal Frequency Division Multiplexing (OFDM) based Multiple-Input Multiple-Output (MIMO) techniques for FSO communications in the context of PHY I, video streaming in PHY-II and the analysis and design of CSK for PHY-III. To be more explicit, in Chapter 2 we first construct a novel ACO-OFDM based MIMO system and investigate its performance under various FSO turbulence channel conditions. However, MIMO systems require multiple optical chains, hence their power consumption and hardware costs become substantial. Hence, we introduced the concept of Aperture Selection (ApS) to mitigate these problems with the aid of a simple yet efficient ApS algorithm for assisting our ACO-OFDM based MIMO system. Since the channel conditions of indoor Visible Light Communication (VLC) environments are more benign than the FSO-channels of Chapter 2, directional white LEDs are used to create an “attocell” in Chapter 3. More specifically, we investigate video streaming in a multi-Mobile Terminals (MTs) indoor VLC system relying on Unity Frequency Reuse (UFR) as well as on Higher Frequency Reuse Factor based Transmission (HFRFT) and on Vectored Transmission (VT) schemes. We minimise the distortion of video streaming, while satisfying the rate constraints as well as optical constraints of all the MTs. In Chapter 4 we analyse the performance of CSK relying both on joint Maximum Likelihood (ML) Hard-Detection (HD), as well as on the the Maximum A posteriori (MAP) criterion-based Soft-Detection (SD) of CSK. Finally, we conceive both two- stage and three-stage concatenated iterative receivers capable of achieving a substantial iteration gain, leading to a vanishingly low BER.
31
Zhang, Lixin. "Dynamic analysis of viscoelastic serpentine belt drive systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0021/NQ45747.pdf.
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Samaranayake, Lilantha. "Distributed control of electric drive systems via Ethernet /." Stockholm : Electrical Machines and Power Electronics, School of Electrical Engineering, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-594.
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Liang, Darwin Tat Wai. "Simulation and analysis of induction motor drive systems." Thesis, Heriot-Watt University, 1993. http://hdl.handle.net/10399/1427.
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Saad, S. "Efficiency of mining electrical variable speed drive systems." Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381103.
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Akin, Bilal. "Low-cost motor drive embedded fault diagnosis systems." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1488.
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Huang, Tony Chun-Hung. "High performance electric drive systems using fuzzy control /." Thesis, Connect to this title online; UW restricted, 1995. http://hdl.handle.net/1773/5970.
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Trigkidis, Georgios. "Electro-thermal modelling of electrical power drive systems." Thesis, University of Derby, 2008. http://hdl.handle.net/10545/528567.
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Lukama, L. "Diversity systems for future wideband wireless communication systems." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249495.
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Schmitt, Michael Philipp. "ARQ systems for wireless communications." Phd thesis, [S.l. : s.n.], 2002. http://elib.tu-darmstadt.de/diss/000269.
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Parand, Farivar. "Cellular optical wireless communications systems." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270654.
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Chan, Hsun-Hung. "Indoor infrared wireless PPM systems." Thesis, Northumbria University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246144.
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Aggarwal, Pankaj. "Mobile authentication in wireless systems." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010839.
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Toni, Laura <1982>. "Adaptive wireless multimedia communication systems." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/2117/.
Повний текст джерелаАнотація:
In recent years, due to the rapid convergence of multimedia services, Internet and wireless communications, there has been a growing trend of heterogeneity (in terms of channel bandwidths, mobility levels of terminals, end-user quality-of-service (QoS) requirements) for emerging integrated wired/wireless networks. Moreover, in nowadays systems, a multitude of users coexists within the same network, each of them with his own QoS requirement and bandwidth availability. In this framework, embedded source coding allowing partial decoding at various resolution is an appealing technique for multimedia transmissions. This dissertation includes my PhD research, mainly devoted to the study of embedded multimedia bitstreams in heterogenous networks, developed at the University of Bologna, advised by Prof. O. Andrisano and Prof. A. Conti, and at the University of California, San Diego (UCSD), where I spent
eighteen months as a visiting scholar, advised by Prof. L. B. Milstein and Prof. P. C. Cosman. In order to improve the multimedia transmission quality over wireless channels, joint source and channel coding optimization is investigated in a 2D time-frequency resource block for an
OFDM system. We show that knowing the order of diversity in time and/or frequency domain can assist image (video) coding in selecting optimal channel code rates (source and channel code rates). Then, adaptive modulation techniques, aimed at maximizing the spectral efficiency, are investigated as another possible solution for improving multimedia transmissions. For both slow and fast adaptive modulations, the effects of imperfect channel estimation errors are evaluated, showing that the fast technique, optimal in ideal systems, might be outperformed by the slow adaptive modulation, when a real test case is considered. Finally, the effects of co-channel interference and approximated bit error probability (BEP) are evaluated in adaptive modulation techniques, providing new decision regions concepts, and showing how the widely used BEP
approximations lead to a substantial loss in the overall performance.
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Alhartomi, Mohammed. "Collaborative optical wireless communication systems." Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/13153/.
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Gollakota, Shyamnath (Shyamnath Venkata Satyasrisai). "Embracing interference in wireless systems." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/79213.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2013."February 2013." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 169-183).
The wireless medium is a shared resource. If nearby devices transmit at the same time, their signals interfere, resulting in a collision. In traditional networks, collisions cause the loss of the transmitted information. For this reason, wireless networks have been designed with the assumption that interference is intrinsically harmful and must be avoided. This dissertation takes an alternate approach: Instead of viewing interference as an inherently counterproductive phenomenon that should to be avoided, we design practical systems that transform interference into a harmless, and even a beneficial phenomenon. To achieve this goal, we consider how wireless signals interact when they interfere, and use this understanding in our system designs. Specifically, when interference occurs, the signals get mixed on the wireless medium. By understanding the parameters of this mixing, we can invert the mixing and decode the interfered packets; thus, making interference harmless. Furthermore, we can control this mixing process to create strategic interference that allow decodability at a particular receiver of interest, but prevent decodability at unintended receivers and adversaries. Hence, we can transform interference into a beneficial phenomenon that provides security. Building on this approach, we make four main contributions: We present the first WiFi receiver that can successfully reconstruct the transmitted information in the presence of packet collisions. Next, we introduce a WiFi receiver design that can decode in the presence of high-power cross-technology interference from devices like baby monitors, cordless phones, microwave ovens, or even unknown technologies. We then show how we can harness interference to improve security. In particular, we develop the first system that secures an insecure medical implant without any modification to the implant itself. Finally, we present a solution that establishes secure connections between any two WiFi devices, without having users enter passwords or use pre-shared secret keys.
by Shyamnath Gollakota.
Ph.D.
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Chen, Changmin. "Motion control and synchronisation of multi-axis drive systems." Thesis, Loughborough University, 1994. https://dspace.lboro.ac.uk/2134/7360.
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Bedingfield, Ralph Andrew. "Development of CAE system for switched motor drive systems." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10312009-020029/.
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Skawinski, Grzegorz. "Fuel pump motor-drive systems for more electric aircraft." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527520.
Повний текст джерелаАнотація:
The fuel systems fitted to the current generation of civil transport aircraft are rather complicated, due to the presence of multiple tanks, pumps, valves and complex pipeline systems. During fuel transfer between the tanks, when controlling the aircraft centre of gravity or engine feed and refuel operations, a number of pumps and valves are involved resulting in complex pressure and flow interactions. In order to minimise the pressure surges during sudden system changes and flow overshoot during fuel transfer and refuelling, different motor drive system control strategies have been investigated. It is proposed that the current control method of electrically driven centrifugal-type pumps could be replaced by improved open and closed loop strategies where the flow overshoot can be minimised and pressure surges reduced. Steady-state and dynamic models of an AC induction motor drive and typical aircraft fuel system pipework components have been developed. The validation of these models has been performed using experimental data obtained from a fuel test rig constructed at the University of Bath using water as the working fluid. The simulation results have been shown to agree well with those from experimentation. In addition, the induction motor has been modelled based on its physical properties using the Finite Element Method software MEGA. The investigated fuel system has been described in linear terms and its behaviour has been identified. It is shown that the system dynamic behaviour can be controlled/improved using well established closed loop proportional-integral control. An open loop technique of simultaneous pump and valve control has been proposed and validated using experimental results, resulting in a reduction of both the transient pressure surges and flow overshoot during sudden valve closures, showing significant performance improvements. Improved closed loop control strategies for the pump drive system have also been developed in simulation. These are based on adaptive proportional-integral-derivative and fuzzy logic control strategies.
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Leedy, Aleck Wayne Nelms R. M. "Analysis of DC power systems containing induction motor-drive loads." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Spring/doctoral/LEEDY_ALECK_32.pdf.
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Ferreira, Rodreguez John D. "Modelling and development of drive control schemes for convoy systems." Thesis, University of Manchester, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.553759.
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