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Teses / dissertações sobre o tema "Communications"

Autor: Grafiati
Publicado: 4 de junho de 2021
Última modificação: 30 de julho de 2024

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1

Kodikara, Patabandi C. K. "Multimedia communications over 3G wireless communication systems". Thesis, University of Surrey, 2004. http://epubs.surrey.ac.uk/844270/.

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This thesis addresses the transmission of video over third generation radio access networks. The first part of the thesis investigates the capabilities of Universal Terrestrial Radio Access Networks (UTRAN) in terms of the provision of multimedia communications. The error performance and traffic requirements of real-time video transmission over circuit switched and packet switched connections are examined. The effect of network parameter settings upon video performances is evaluated, and optimum radio bearer configurations for the transmission of video are derived. A method of estimating received video quality after transmission over error prone environments is developed. The quality estimation is based on a distortion model, which accurately models the overall distortion seen in decoder frame reconstruction. This includes quantisation distortion, concealment distortion, and error propagation. Based on the developed performance model, optimum MTU (Maximum Transfer Unit) size for efficient wireless video communications over a packet switched access network is derived. The second part of the thesis investigates quality enhancement techniques for multimedia traffic transmitted over wireless channels. Quality enhancement is achieved at three levels of the transmission process: link level, application level and system level. Link level quality enhancement techniques are designed to optimise the allocation of link level parameter values according to the media characteristics. A novel Unequal Error Protection scheme and a novel Unequal Power Allocation scheme are designed to exploit the inherent diversity in the subjective importance of different sections of compressed media. The algorithms are developed and analysed for transmission of video over 3G wireless systems. The effectiveness of these algorithms is demonstrated through the results of simulated transmission over a UMTS channel. Application level quality enhancement techniques are designed to explore the time-varying nature of the wireless channel. A number of link adaptation schemes are proposed for real time video communication and real-time video streaming over 3G wireless systems. These algorithms are designed to enhance the perceptual video quality, and the system utilisation. This is achieved by adapting the allocated radio network parameters and the source parameters, according to a feedback channel condition. Simulation results show a significant performance improvement compared to non-adaptive schemes. Finally, system level adaptation techniques are designed for efficient radio resource allocation in multi-user scenarios. Two adaptive resource allocation schemes are proposed and analysed for real-time video communications in a UMTS system. The proposed algorithms are shown to provide improved performances in terms of average received video quality and user satisfaction. Key words: Wireless Communication, Multimedia communication. Video Transmission.
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2

Bezuidenhout, Quintus. "Satellite communications strategy selection for optimal LEO satellite communication". Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71930.

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Thesis (MScEng)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: A low earth orbit satellite system can be useful in numerous communication applications where physical connections are not possible. Communication time available from any point on earth to the satellite is less than one hour per day. This one hour is fragmented into smaller time slots due to the satellite orbiting. This is not much time to transfer data and there is even less time available to transfer data when there are other external factors affecting the system. It is thus crucial to optimise the satellite communications link so that more data can be transferred per orbit. The goal of this thesis is to improve the performance of a low earth orbit satellite communication channel by varying certain parameters of the system, such as the protocol used, modulation scheme, packet size, transmission power etc. and then to observe how these parameters influence the system. The protocols that were chosen to be implemented are CSMA-CA, CSMA-CA with DSSS technology and Round-Robin Polling. A simulator for each protocol was designed with the Opnet platform, so that specific parameters could be changed and the results observed, in order to optimise the communications link between the satellite and ground stations. The results showed that there is no particular configuration of modulation scheme, packet size, transmission power etc. presenting the best overall solution for LEO satellite communications. It must be considered what the specific LEO satellite application would be used for and the characteristics required by that specific application. A suitable configuration must subsequently be chosen from the set of configurations available to satisfy most of the application requirements.
AFRIKAANSE OPSOMMING: ’n Satelliet met ’n lae wentelbaan kan gebruik word in verskeie kommunikasie toepassings waar fisiese verbindinge nie noodwendig moontlik is nie. Die kommunikasietyd van enige punt van aarde af na die satelliet, is minder as een uur per dag. Hierdie tyd word nog verder verklein omdat die satelliet besig is om, om die aarde te wentel. ’n Uur is glad nie baie tyd om data oor te dra nie en in realiteit is daar nog minder tyd beskikbaar as daar eksterne faktore op die sisteem inwerk. Dus is dit baie belangrik om die satelliet kommunikasiekanaal te optimiseer sodat soveel moontlik data as moontlik oorgedra kan word per omwenteling. Die doel van hierdie tesis is om die deurset van die kommunikasiekanaal van n lae wentelbaan satelliet te optimiseer, deur verskeie parameters te verander soos, protokol wat gebruik word, modulasie skema, pakkie grootte, transmissiekrag ens. en dan waar te neem hoe dit die sisteem beïnvloed. Die protokolle wat geïmplementeer is, is CSMA-CA, CSMA-CA met DSSS tegnologie en Round-Robin Polling. ’n Simulator vir elke protokol was ontwerp in die Opnet simulasie platform, sodat die spesifieke parameters verander kon word om die resultate te bestudeer met die doel om die kommunikasiekanaal tussen die satelliet en grond stasies optimaal te benut. Die resultate het bewys dat daar geen spesifieke konfigurasie van modulasie skema, pakkie grootte, transmissiekrag ens. is wat die algehele beste oplossing is nie. Die spesifieke applikasie waarvoor die lae wentelbaan satelliet gaan gebruik word moet geanaliseer word sowel as die spesifieke karakteristieke van daai applikasie. Daarvolgens moet n unieke konfigurasie opgestel word wat meeste van die applikasie se behoeftes bevredig.
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3

Murphy, Melvin Murphy. "Internal Strategies for Assessing Organizational Communication Channel Effectiveness". ScholarWorks, 2017. https://scholarworks.waldenu.edu/dissertations/3406.

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Evolving communication technology, the increased volume of information needed by businesses, and the intensified competitive environment have made internal company communication more critical to business success. The purpose of this multiple case study was to explore strategies used by managers and leaders of 3 law firms in the Commonwealth of Virginia for assessing the effectiveness of their organization's internal communication channels. The participating firms were recognized by their peers as being exceptionally well-managed. Data from interviews and company documents were analyzed through the conceptual lens of the channel expansion theory and the use of software coding to identify patterns and themes. Three important themes emerged: informal assessment strategies, indirect assessment strategies, and efficient versus timely assessments. The first theme suggested the effectiveness of an informal assessment strategy, depending on the size and complexity of the organization. The second theme reflected the effectiveness of an indirect assessment for organizations that lack the resources to support a more direct and specific assessment process. The third theme reflected the participants' perceptions of informal and indirect assessments may be more efficient, the feedback from the assessments are often less timely. Managers may consider these themes in formulating communication policies. The findings of this case study may have implications for positive social and economic change. Small professional service firms, such as legal firms, provide important services to individuals, families, and businesses in their community.
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4

Radford, Benjamin. "Misinformation in eating disorder communications| Implications for science communication policy". Thesis, State University of New York at Buffalo, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1546959.

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Though eating disorders are a serious public health threat, misinformation about these potentially deadly diseases is widespread. This study examines eating disorder information from a wide variety of sources including medical journals, news reports, and popular social activist authors. Examples of misinformation were identified, and three aspects of eating disorders (prevalence, mortality, and etiology) were chosen as key indicators of scientific illiteracy about those illnesses. A case study approach was then adopted to trace examples of misinformation to their original sources whenever possible. A dozen examples include best-selling books, national eating disorder information clearinghouses; the news media; documentary feature films; and a PBS television Nova documentary program. The results provide an overview of the ways in which valid information becomes flawed, including poor journalism, lack of fact-checking, plagiarism, and typographical errors. Less obvious—and perhaps even more important—much of the misinformation results from scientific research being co-opted to promote specific sociopolitical agendas. These results highlight a significant gap in science communication between researchers, the medical community, and the public regarding these diseases, and recommendations to address the problem are offered.

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5

Rajapakshalage, D. (Dhanushka). "Infrastructure based communication architecture to facilitate autonomous driving and communications". Master's thesis, University of Oulu, 2019. http://jultika.oulu.fi/Record/nbnfioulu-201909242926.

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Abstract. The traditional autonomous vehicle (AV) architecture places a heavy burden on graphics processing units of the vehicle due to heavy signal processing requirements. Ultimately this results in performance degradation in AVs. This is mainly due to advanced sensors, which enable the vision for AVs, like Light Detection and Ranging (LiDAR), radars and cameras. In most of the AV models accepted by many leading automobile companies, LiDAR plays a significant role. It generates a high definition (HD) point cloud of the surroundings to obtain a precise map. AV makes decisions based on that by processing Terabyte (Tb) scale data within the AV. Still, vehicle-mounted LiDARs are not capable of providing information beyond a human driver’s vision. To provide a solution for the above-mentioned drawbacks of the traditional AVs, we propose an infrastructure based communication architecture to facilitate autonomous driving and communications. A set of coordinated LiDAR modules with integrated transceivers, which are mounted at an elevation with a bird’s eye view, can provide a much larger field of vision (FoV). Decisions are taken from a centralized body. We prove the technical feasibility of the system from sensing and communication point of view. The proposed architecture can play a supportive role with traditional AV architectures and it can be applied to many cases such as to automate harbours and factory floors. In the second part of the thesis, we address a resource allocation problem with ultra-reliable and low latency communication (URLLC) for a factory floor. We have analytically proven the capability of the proposed system to establish a reliable (packet error probability less than 10^(-5)) and low latency (less than 1 ms transmission delay) links with sufficient throughput (kilobit scale) using a convex optimization problem. Latency, throughput and reliability variations are studied under the short packet transmission of the proposed system.
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6

Gregersen, Svein Erik Søndervik. "Underwater Communications : An OFDM-system for Underwater Communications". Thesis, Norwegian University of Science and Technology, Department of Electronics and Telecommunications, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-8735.

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In the fall 2006 NTNU (The Norwegian University and Science and Technology) initiated a strategic project in cooperations with SINTEF where the aim is to gain more knowledge about underwater acoustic communications. This study is a part of this project and focuses on a system for underwater communication. A orthogonal frequency division multiplexing (OFDM) system using differential quadrature phase shift keying (DQPSK) has been defined and implemented in MATLAB. The system has been characterized through thorough simulations and testing. Initial measurements has also been carried out in order to test the developed system on a real underwater acoustic channel and the results have been analysed.

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7

Wong, Chi Chong. "Personal communications". Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/70862.

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8

Lichtman, Marc Louis. "Antifragile Communications". Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/72267.

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Jamming is an ongoing threat that plagues wireless communications in contested areas. Unfortunately, jamming complexity and sophistication will continue to increase over time. The traditional approach to addressing the jamming threat is to harden radios, such that they sacrifice communications performance for more advanced jamming protection. To provide an escape from this trend, we investigate the previously unexplored area of jammer exploitation. This dissertation develops the concept of antifragile communications, defined as the capability for a communications system to improve in performance due to a system stressor or harsh condition. Antifragility refers to systems that increase in capability, resilience, or robustness as a result of disorder (e.g., chaos, uncertainty, stress). An antifragile system is fundamentally different from one that is resilient (i.e., able to recover from failure) and robust (i.e., able to resist failure). We apply the concept of antifragility to wireless communications through several novel strategies that all involve exploiting a communications jammer. These strategies can provide an increase in throughput, efficiency, connectivity, or covertness, as a result of the jamming attack itself. Through analysis and simulation, we show that an antifragile gain is possible under a wide array of electronic warfare scenarios. Throughout this dissertation we provide guidelines for realizing these antifragile waveforms. Other major contributions of this dissertation include the development of a communications jamming taxonomy, feasibility study of reactive jamming in a SATCOM-type scenario, and a reinforcement learning-based reactive jamming mitigation strategy, for times when an antifragile approach is not practical. Most of the jammer exploitation strategies described in this dissertation fall under the category of jammer piggybacking, meaning the communications system turns the jammer into an unwitting relay. We study this jammer piggybacking approach under a variety of reactive jamming behaviors, with emphasis on the sense-and-transmit type. One piggybacking approach involves transmitting using a specialized FSK waveform, tailored to exploit a jammer that channelizes a block of spectrum and selectively jams active subchannels. To aid in analysis, we introduce a generalized model for reactive jamming, applicable to both repeater-based and sensing-based jamming behaviors. Despite being limited to electronic warfare scenarios, we hope that this work can pave the way for further research into antifragile communications.
Ph. D.
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9

Дядечко, Алла Миколаївна, Алла Николаевна Дядечко, Alla Mykolaivna Diadechko e A. N. Zholudeva. "Marketing communications". Thesis, Видавництво СумДУ, 2010. http://essuir.sumdu.edu.ua/handle/123456789/18327.

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Marketing communications is defined by actions a firm takes to communicate with end-users, consumers and external parties. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/18327
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10

Vantine, Karin. "Communications sourcebook /". Online version of thesis, 1992. http://hdl.handle.net/1850/11867.

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11

Puglia, Vincent. "Unified communications : the search for ROI through tomorrow's business communication solutions /". Online version of thesis, 2010. http://hdl.handle.net/1850/11590.

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12

Steele, Robert Joshua. "Determining Communications Resource Feasibility in a Tactical Communications Network". Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/32418.

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In this paper, we present solutions concerning communications resource allocation for tactical communication networking. Given a mission definition (which defines communication needs among participants) and participant capabilities (such as processing power and bandwidth), algorithms are presented to determine if the mission as presented is feasible. The mathematical foundation of the problem is presented, and a â staticâ model to determine feasibility is shown. Further evolution of the algorithm into a â dynamicâ model and the reasons for the more demanding requirements are presented. Reasoning behind use of the Netflo algorithm in the dynamic model is also discussed. The inclusion of the algorithm in a stand-alone program is discussed, including overall program structure, graphical user interface components and alternative output (such as the generation of high level network policy). Finally, future work in this area is discussed.
Master of Science
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13

Germerie, Guizouarn Loïc. "Automates communicants et communications quasi-synchrones". Electronic Thesis or Diss., Université Côte d'Azur, 2023. http://www.theses.fr/2023COAZ4112.

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Les systèmes distribués sont le plus souvent basés sur l'échange asynchrone de messages entre des agents. La programmation par échanges de messages est largement utilisée en calcul haute performance, en programmation événementielle, dans les architectures orientées service, etc. Malheureusement du fait de la variété des modèles de communication, des ambiguïtés dans les spécifications, de la portabilité limitée du code, ou encore de la difficulté à exécuter des tests, il est très difficile de vérifier les systèmes communicants. Le model-checking de systèmes communicants vise à analyser des modèles formels de systèmes distribués et à détecter automatiquement des erreurs comme des pertes de messages ou des inter-blocages. Ces problèmes sont indécidables pour des systèmes à partir de deux machines, et plusieurs hypothèses restrictives ont été étudiées pour rendre les problèmes décidables. Nous définissons dans cette thèse une nouvelle classe de systèmes : les systèmes réalisables avec des communications synchrones (RSC pour faire court). Les comportements de ces systèmes approximent des comportement synchrones, où les messages sont envoyés et reçus simultanément. Nous nous basons sur cette définition pour étudier la généralisation d'une autre classe de systèmes : les systèmes half- duplex. Un système à deux machines est half-duplex si lorsqu'une machine envoie des messages, l'autre ne peut pas lui en envoyer. Nous étudions également un autre formalisme, permettant de raisonner sur les systèmes de manière globale : les chorégraphies. Ce formalisme décrit les exécutions de manière synchrone, et un des problèmes qui y est associé est de vérifier si la combinaison des comportements de chaque acteur qui y est décrit est conforme à la description globale. Nous proposons d'utiliser les propriétés des systèmes RSC pour traiter ce problème
Most of the distributed systems we use nowadays are based on the message-passing paradigm where systems are structured into parties that interact only by sending and receiving messages asynchronously. Message-passing programming is largely employed in high performance computing (MPI, OpenMP, etc), event-driven applications built on top of actor-based languages (Scala, Erlang, etc), service-oriented architectures, peer-to-peer applications, etc. Unfortunately, because of the variety of communication models (peer to peer, mailbox, etc), of the ambiguities of the specifications of the communication primitives, of a limited portability of the code, and of the difficulty of running representative tests, etc, it is error prone and therefore often reserved to experts. Model-checking of communicating automata aims at analysing formal models of distributed systems and discovering bugs like message loss or deadlocks. Due to the asynchronous nature of the communications, this problem is undecidable in general, even with two machines only, and several restrictions have been considered to restore decidability. We define a new one in this thesis: systems that are realisable with synchronous communications (RSC for short), that is the systems whose behaviours are equivalent to synchronous ones. We propose the class of RSC systems as a generalisation of half-duplex systems, which are system of two machines, where a machines does not send any message if it still has some pending messages to be received in its queue. We study another formalism as well: choreographies, which provide a way to reason globally on a system. Choreographies describe synchronous executions, and one of the problems associated with it is checking whether the combination of all participants of the described communication will behave accordingly to the global description. We propose to rely on the properties of RSC systems to study this problem
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Oswald, Jennalande. "Transparency and City Government Communications". BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/2005.

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This study expresses the need for a communications model created specifically for government communications that is centered on the concept of transparency. However, it also recognizes the previous research done pertaining to government communications and public relations. Importantly, the study recognizes the lack of trust in American government at city, state and federal levels and the need to improve trust, which is very closely related to transparency. The study focuses primarily on a model created in 2007 called the three-dimensional model for government communications. The model has four parts: the base of the model is the need to value transparency; the other three parts are communication practices, provision of resources, and organizational support. This study seeks to test and quantify the three-dimensional model through the creation of a survey based on the four parts of the three-dimensional model. The study seeks to determine if by following the guidelines established in the three-dimensional model a city will be more transparent. The findings come from the point of view of city communicators. Over two hundred city communicators from the largest cities in America participated in the study. The findings show that following the tenets of the three-dimensional model does in fact lead to greater transparency. Although the study only surveyed government communicators at the city level, the findings are important to government communicators at all levels of government. The study illustrates the importance of creating a communications plan that is based on transparency and the three-dimensional model. It also illustrates that the frustrations found at the federal level are similar to those faced at the city level. The study also sheds light on the need for future research pertaining to government communications.
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15

Kolhatkar, Madhuri. "Web-mediated communication at workplace : a case study at US WEST Communications". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0001/MQ43614.pdf.

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16

Wang, Shendi. "Efficient transmission design for machine type communications in future wireless communication systems". Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/23647.

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With a wide range of potential applications, the machine type communication (MTC) is gaining a tremendous interest among mobile network operators, system designers, MTC specialist companies, and research institutes. The idea of having electronic devices and systems automatically connected to each other without human intervention is one of the most significant objectives for future wireless communications. Low data rate transmission and the requirement for low energy consumption are two typical characteristics for MTC applications. In terms of supporting low cots MTC devices, industrial standards will be more efficient if designers can re-use many features of existing radio access technologies. This will yield a cost effective solution to support MTC in future communication systems. This thesis investigates efficient MTC waveform and receiver designs for superior signal transmission quality with low operational costs. In terms of the downlink receiver design, this thesis proposes a novel virtual carrier (VC) receiver system for MTC receivers, which aims to reduce the maximum bandwidth to improve the data processing efficiency and cost-efficiency by using analogue filters to extract only sub-carriers of interest. For the VC receiver systems, we thus reduce the sampling rate in order to reduce the number of subsequent processing operations, which significantly reduces the analogue-to-digital converter (ADC) cost and power consumption while providing high signal to interference noise ratio (SINR) and low bit to error rate (BER) to support low data rate MTC devices. Our theoretical equations account for the interference effect of aliasing on the sub-carrier location, and this helps the system designer to evaluate what kind of filters and receiver sampling rate can be used to balance the energy cost and detection performance. In terms of the uplink waveform design, considering the enhanced number of MTC devices in the future communication systems, i.e. the fifth generation (5G) communications, the same tight synchronisation as used in today appears not to be cost-effective or even possible. Synchronisation signals, which aim to provide a perfect time or frequency synchronisation in the current fourth generation (4G) communication systems (known as the long-term evolution, LTE), is much more costly for low data rate MTC transmissions. The system bandwidth will be significantly reduced if a base station tries to synchronise all received signals among hundreds or thousands MTC devices in one transmission time period. In terms of relaxing the synchronisation requirements, this thesis compares and analyses the side-lobe reduction performance for several candidate multi-carrier waveforms to avoid these problems. We also propose the infinite impulse response universal filtered multi-carrier (UFMC) system and the overlap and add UFMC system, which significantly reduce the processing complexity compared with the state of the art UFMC techniques. This thesis derives closed-form expressions for the interference caused by time offsets between adjacent unsynchronised MTC users. Our analytical equations can be used in both simple and complex time-offset transmission scenarios, and enable the system designer to evaluate the SINR, the theoretical Shannon capacity and the BER performance.
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Byrne, Daniel Scott II. "A Technical Communication Internship With An eCRM Software Company: Synchrony Communications, INC". Miami University / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=miami1007737580.

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18

Holton, Carolyn F. "The impact of computer mediated communication systems monitoring on organizational communications content". [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002440.

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19

Sen, Cem. "Digital communications jamming". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2000. http://handle.dtic.mil/100.2/ADA383913.

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Thesis (M.S. in Systems Engineering) Naval Postgraduate School, Sept. 2000.
Thesis advisor(s): Smith, Rasler W.; Lebaric, Jovan. Includes bibliographical references (p. 137-139). Also available online.
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20

Wang, Tiejun. "Mobile OFDM communications". Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3211276.

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Thesis (Ph. D.)--University of California, San Diego, 2006.
Title from first page of PDF file (viewed June 7, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 104-111).
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21

Michaels, Alan Jason. "Digital chaotic communications". Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/34849.

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This dissertation provides the conceptual development, modeling and simulation, physical implementation, and measured hardware results for a practicable digital coherent chaotic communication system. Such systems are highly desirable for robust communications due to the maximal entropy signal characteristics that satisfy Shannon's ideal noise-like waveform and provide optimal data transmission across a flat communications channel. At the core of the coherent chaotic communications system is a fully digital chaotic circuit, providing an efficiently controllable mechanism that overcomes the traditional bottleneck of chaotic circuit state synchronization. The analytical, simulation, and hardware results yield a generalization of direct sequence spread spectrum waveforms, that can be further extended to create a new class of maximal entropy waveforms suitable for optimized channel performance, maximal entropy transmission of chaotically spread amplitude modulated data constellations, and permission-based multiple access systems.
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22

Danezis, George. "Better anonymous communications". Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616002.

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Asbery, Christopher W. "SMART GRID COMMUNICATIONS". UKnowledge, 2012. http://uknowledge.uky.edu/ece_etds/10.

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Smart grid technologies are starting to be the future of electric power systems. These systems are giving the utilities detailed information about their systems in real time. One of the most challenging things of implementing smart grid applications is employing the communications into the systems. Understanding the available communications can help ease the transition to these smart grid applications. Many of the utility personnel are spending too much time trying to figure out which communication is better for their application or applications. So this thesis presents the different communication types available with discussing the different attributes in which these communication types are going to offer to the utility. Then these communication types are looked such that utilities can quickly understand how to approach the difficult task of obtaining the information from the different smart grid applications by the use of different communication options.
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Giroudeau, Rodolphe. "ordonnancement et communications". Habilitation à diriger des recherches, Université Montpellier II - Sciences et Techniques du Languedoc, 2012. http://tel.archives-ouvertes.fr/tel-00797855.

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Simensen, Thor A. "Link-11 communications". Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23945.

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Davies, Jonathan James. "Underwater acoustic communications". Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289679.

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Biddiscombe, Martin David. "Free market communications". Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325627.

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Морозова, Ірина Анатоліївна, Ирина Анатольевна Морозова, Iryna Anatoliivna Morozova e M. I. Bilan. "Information communications technology". Thesis, Вид-во СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/22209.

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Bojko, C. "Ecology communications, inc". Thesis, Вид-во СумДУ, 2005. http://essuir.sumdu.edu.ua/handle/123456789/13369.

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30

Sheriff, Ray E., A. Donner e A. Vanelli-Coralli. "Satellite Communications [Editorial]". Master's thesis, Hindawi Publishing Corporation, 2007. http://hdl.handle.net/10454/3488.

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Yes
We are delighted to bring to you this special issue on satellite communications, which we have prepared as part of the spreading of excellence remit of the satellite communications network of excellence (SatNEx). The SatNEx project, which began in 2004, is funded for five years under the European Union¿s Sixth Framework Programme (FP6) Information Society Technologies (IST) Thematic Area. Led by the German Aerospace Center, SatNEx brings together a network of 24 partners, distributed throughout Europe, with membership drawn from ten countries. The philosophy underlying the SatNEx approach revolves around the selection of focused actions under Joint Programmes of Activities, which are carried out collectively by the partners and include research, integration, and dissemination activities. Training represents an important part of the SatNEx remit and is supported through a number of initiatives including the hosting of internship projects and an annual summer school. The call for papers resulted in a high number of submissions, from which we have been able to select 12 excellent papers dealing with the different aspects of satellite communications and navigation.
European Union
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31

Zou, Ding, e Ivan B. Djordjevic. "FPGA-Based Rate-Compatible LDPC Codes for the Next Generation of Optical Transmission Systems". IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2016. http://hdl.handle.net/10150/621685.

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In this paper, we propose a rate-compatible forward error-correcting (FEC) scheme based on low-density-parity check (LDPC) codes together with its software reconfigurable unified field-programmable gate array (FPGA) architecture. By FPGA emulation, we demonstrate that the proposed class of rate-compatible LDPC codes based on puncturing and generalized LDPC coding with an overhead from 25% to 46% provides a coding gain ranging from 12.67 to 13.8 dB at a post-FEC bit-error rate (BER) of 10(-15). As a result, the proposed rate-compatible codes represent one of the strong FEC candidates of soft-decision FEC for both short-haul and long-haul optical transmission systems.
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32

Poirrier, Julien. "Electronic Mitigation of Polarization Mode Dispersion". Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/34469.

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Polarization Mode Dispersion induces polarization dependent propagation. Consequently it generates a multiple imaging of the light pulse carrying the information. Its first order appears as a dual path fading channel of Maxwellian statistics. It results in harmful impairments that prevent the upgrade and installation of high bit-rate systems. The random process PMD exhibits a strong frequency dependence, so that its amelioration requires channel by channel, non-linear, adaptive mitigation. Electronic mitigation appears as a very attractive solution to overcome the limit set by the PMD. Consequently, we considered the implementation of these solutions at the receiver in the electrical domain. We verified that these linear and non-linear equalization techniques can greatly reduce the power penalty due to PMD. Equalization's performance depends highly on the type of systems considered. For the two main types of systems: thermal noise limited systems and systems exhibiting ASE (systems using optical amplifiers), we demonstrated and quantified the induced improvement (measured as power penalty reduction). The most sophisticated technique that we considered (NLC+FDE) handles any kind of first order PMD within a 4 dB margin in the thermal noise limit. This extended to a 11 dB margin in the presence of ASE. This comes from the limitation set by the signal dependence of the noise. In fact, these DSP techniques do a better job at reducing very high penalty. Consequently, for a power and ISI limited link, it may be required to associate to electronic solutions optical compensation in order to reach acceptable performance. On the other hand, for links having large power margin or exhibiting reasonable PMD, electronic techniques appear as an easy, inexpensive and convenient solution. We derived in this work the bounds to NLC performance in the presence of ASE. Therefore, we extended the usual results of the thermal noise limit to the particular case of signal dependent noise. We also made clear that optical systems, because of their noise specificities can not be studied or designed as others links. Notions such as eye opening, SNR and ISI need to be carefully defined and adapted to this case. We have provided in this work PMD dependent power penalty map for known systems. Given the link's statistics and characteristics, one can determine, following our structure, which mitigation techniques allow upgrade.
Master of Science
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33

Cournoyer, Ronald C. "Personal communications services : improving theater deployable communications for the 21st century". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA283465.

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Thesis (M.S. in Systems Technology (Command, Control, and Communications)) Naval Postgraduate School, June 1994.
Thesis advisor(s): Carl R. Jones, Dan C. Boger. "June 1994." Includes bibliographical references. Also available online.
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34

Gow, Gordon Albert. "New approaches to disaster communications, towards a global communications lifeline infrastructure". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq24588.pdf.

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MacCallum, Irene F. "Effective communications, a study of manager/employee communications in an organization". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ49206.pdf.

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36

Link, Jeffrey P. "Design of a serial communication protocol and bus interface chip for tactile communications". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA362194.

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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, March 1999.
Thesis advisor(s): Douglas J. Fouts. "March 1999". Includes bibliographical references (p. 285). Also available online.
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37

Monaghan, Joseph Francis. "Evaluation of digital communications using the Marine Corps Communications Architecture Analysis Model". Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23661.

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Approved for public release; distribution is unlimited
The United States Marine Corps (USMC) is currently evolving to digital communications. This change has created a need for an analysis tool capable of analyzing digital architectures. Traditional communications are being supplemented, and in some cases, replaced by automated systems like the Marine Tactical Command and Control System (MTACCS) Older equipment, the PRC-77 and AN/VRC-12 family of radios, is being replaced by lighter, more efficient equipment like SINCGARS and the Digital Communications Terminal (DCT). Protocols like the Marine Tactical System (MTS) Broadcast Protocol are being implemented to orchestrate this new way of communicating. To assist in the transition, this thesis modified the Marine Corps Communications Architecture Analysis Model (MCCAAM) so it could measure the impact of changing from voice to digital communications. The Fidelity Enhancement Process (FEP) , a comprehensive methodology for model upgrades, was used to systematically modify the model. The model's usefulness is demonstrated in an analysis example by comparing three separate partially digital communications architectures.
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38

Taylor, Christine. "Project Manager Strategies for Strengthening Communications Within Project Teams". ScholarWorks, 2018. https://scholarworks.waldenu.edu/dissertations/6135.

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Communication inefficiencies are among the reasons for poor or substandard performances in project teams. The purpose of this multiple case study was to explore the strategies used by project managers in the health care industry to strengthen communication within project teams. The conceptual framework for the study was McQuail's mass communication theory and Craig's communication theory. Participants of the study were 4 project managers from 2 leading medical supply companies located in the mid-Atlantic region of the United States. Data were collected using semistructured interviews and a review of company documents. The summarized interview responses were validated by participants through the use of member checking. The 3 key themes that emerged from thematic data analysis highlighted strategies that project managers used to strengthen communications with project teams: communication planning, management, and ethics. Project managers can use the study's findings to increase team members' motivation, improve project results, and bolster organizational profitability, which may positively contribute to the growth, development, and betterment of the communities served by their companies.
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39

Neo, Soo Sim Daniel. "Free space optics communication for mobile military platforms". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Dec%5FNeo.pdf.

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40

Borgmann, Moritz. "Noncoherent MIMO wideband communications /". Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17352.

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41

Larsson, Johannes. "Streamline Communications in Radiology". Thesis, Linköping University, Department of Computer and Information Science, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17421.

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The background to the study was Unified Communications (UC), defined as Communications integrated to optimize business processes. A case study design is used to develop a LoFi-prototype. The prototype investigateswhat components an integrated communication solution should provide,for the people in radiology. The design was inspired by consumer products likeSkype. In these consumer products were functionality and look studied. The reason for integrate it into Sectra MEI, was that Sectra believed the system’s features could be even more useful, when used together with a communication solution. The prototype is tested on users (usability tested). To bundle the growing pile of requirements in the design process was a requirement specification produced.

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42

Purushothama, Rashmi. "MULTIPATH COMMUNICATIONS USING NAMES". Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-90235.

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Increased host mobility, and multi-homing make IP address management very complex in applications. Due to host mobility, the IP address of a host may change dynamically, and also frequently. Multi-homing leads to multiple IP addresses for a single host. Name-based socket is a solution to address the complex IP address management. It relieves the applications from the overhead, and moves it to the operating system. It uses a constant name, instead of an IP address to establish a connection, thus allowing for the IP address changes during the course of the connection. The current implementation of name-based sockets is on Transmission Control Protocol (TCP). TCP restricts the connection to a single path, even when multiple capable paths are available. Multi-path communication provides higher reliability, and increase throughput. Today, multi-path connections are quite feasible, since many hosts are generally multi-homed. Multipath TCP (MPTCP) is designed to overcome the restrictions in TCP. It renders the ability to simultaneously use multiple paths between the peers. Thus, it offers higher reliability, and better throughput. One of the aims of this Master’s thesis is coalescing MPTCP and name-based socket to provide a mechanism which handles IP address management issues as well as provides high resilience, and throughput. Another important area of research is to discover ways of providing good user experience with IPv6 addresses. Given that IPv6 deployments are still in its infancy, there are high chances that IPv6 is broken. Hence, it is very important to protect the users from these IPv6 outages and thereby motivate the major websites and service providers to use IPv6. This will in turn help in the global deployment of IPv6. Happy eyeballs is a smart approach to determine the best suitable path from a dual-stack client to a dual-stack server. In order to save the users from IPv6 outages, this thesis work also focuses on implementing happy eyeballs on name-based sockets.
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43

Eichhorn, Alexander Kühnhauser Winfried. "Content-aware multimedia communications /". Oslo : Unipub AS, 2008. http://www.gbv.de/dms/ilmenau/toc/570639581.PDF.

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44

Jiang, Xiaofeng. "Multipoint digital video communications". Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239548.

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45

Goudevenos, Apostolos. "Through water electromagnetic communications". Thesis, University of Liverpool, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494085.

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Underwater communications at high frequencies have a wide variety of applications including diving, military equipment, oil and gas exploration in offshore fields as well as oceanographic mapping. Wireless communications are much more practical than hardwire communications due to the nature of the ocean environment. Currently the most commonly applied method for underwater communications is acoustic communications but have some serious disadvantages. These include low data rate, shadowing and reflections. Optical fibre communications have been offered as a viable alternative but their use is limited to small distances.
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46

Xie, Xiaoling. "Communications in construction design". Thesis, Loughborough University, 2002. https://dspace.lboro.ac.uk/2134/7571.

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Construction design has become an increasingly complex synthesis activity for which effective solutions depend upon co-operative participation by a number of people. Thus communication, including the integration of specialised knowledge and negotiation of differences between team members, is a vital process for collaborative design. A questionnaire survey was initially conducted to investigate communication issues and problems, which had been highlighted from a review of the literature, in current construction design. The results confirmed that communication among the different construction team members is often difficult although of paramount important to design outcomes. Based on these results, case studies have been carried out to gain further insights into communication issues and problems, and explore why and how they are caused. Through the application of multiple approaches, a model has been developed, which suggests strategies that may help participants communicate more effectively and ultimately improve the quality of construction design outcomes.
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47

Fay, Leon. "Equalizers for communications satellites". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45992.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.
Includes bibliographical references (p. 57).
This thesis investigates equalization for advanced protected satellite communications systems in development at MIT Lincoln Laboratory. Equalizers facilitate high data rate communication by correcting dispersion in the transmitter and receiver signal chains. An automated calibration procedure for finding optimal equalizers was developed. Repeated testing addressed questions about noise amplification, filter complexity requirements, and narrow band performance degradation. After examining various architectures, it was determined that the FIR filter was the best equalizer structure given the nature of the channel. The basic calibration procedure was also extended for use at high RF frequencies by using a spectrum analyzer as a tuned receiver.
by Leon Fay.
M.Eng.
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48

Olayiwola, Rahman Olalekan. "Political communications in Nigeria". Thesis, London School of Economics and Political Science (University of London), 1991. http://etheses.lse.ac.uk/1089/.

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This study of the Nigerian Political Communications examines the patterns of mass media ownership and their impact on the coverage of selected national issues - the census controversy, ethnic problems and the general elections of 1979 and 1983. The contents of 21 newspapers of variegated ownership pattern involving governments, partisan and private interests are analysed and "live" illustrations of stories are given. This is to demonstrate empirically the thesis argument that the criterion of ownership is the key factor which determines how the Nigerian mass media are used for moulding the citizens' perception of political reality. The thesis seeks to answer questions such as: (a) what role have the Nigerian mass media played in promoting and/or compounding the problems of national integration in the Nigerian society since independence. (b) what role should the Nigerian mass media play to promote national integration and political stability. (c) what changes are necessary and desirable with the present situation to allow the mass media perform such integrative and stabilizing functions. Located within a comparative political communication approach to the study of mass media and politics in developing countries, this thesis seeks to contribute to knowledge in the areas of the theory, methodology and practice of political communications in Africa - with Nigeria as a case study. The question of media ownership has remained central to the Nigerian political communications with the attendant intrigues, ethnic violence, character assassination, political vilification, personal vendetta, coups and counter coups, general violent political disagreement and perennial problems of political instability culminating in fragmentation and disintegration that threaten the continued existence of Nigeria. The thesis also highlights a host of other factors which work in collaboration with media ownership to influence the Nigerian political communications - ethnicity, economic position, religion, legal limitations, circulation, transportation, audience reach, freedom of the press or lack of it, linguistic barriers and literacy. The thesis argues, in conclusion, that as Nigeria approaches a third attempt at democratic rule in socio-economic conditions which are less propitious than on past occasions, there is a need for the Nigerian mass media to operate in a way which contributes to national integration. It questions the existing pattern which is elitist and urban in orientation, ignores the rural majority and divides the Nigerian people rather than unites them. To achieve integration through political communications, the thesis suggests the need to restructure the media ownership pattern and to establish a Nigerian Media Advisory Council with some regulatory powers and authority to impose punitive sanctions on media practitioners and institutions for any professional misconduct.
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49

Jones, David Blodgett. "Directiveness in promotional communications". Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/77808.

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The style of a communication may influence a receiver's responses as well as the message's factual, informational content. The degree to which a promotional communication attempts to control a receiver's responses can be defined as a relational and therefore a stylistic variable. This dissertation operationalizes a stylistic variable, directiveness, as the degree to which a persuasive communication instructs the receiver how to respond in terms of action, attitudes and beliefs. Directive messages attempt to limit the receiver's responses while less directive or suggestive messages encourage the reader to make up his or her own mind. Using Attribution Theory and the Cognitive Processing Model as theoretical bases, experimental hypotheses were tested involving the impact of directive versus suggestive messages on receiver responses to one-sided and two-sided communications and high and low involvement topics. Directiveness was found to have significant impact on receiver responses depending on the receiver's level of involvement. The main implication of this research is that how a persuasive communication is worded may influence a receiver's responses to what informational content is presented.
Ph. D.
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50

Milosavljevic, Ivana. "Power Electronics System Communications". Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/31218.

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This work investigates communication issues in high-frequency power converters. A novel control communication network (Power Electronics System Network or PES Net) is proposed for modular, medium and high-power, converters. The network protocol, hardware and software are designed and implemented. The PES Net runs at 125 Mb/s over plastic optical fiber allowing converter switching frequencies in excess of 100 kHz. Communication control is implemented in a field programmable gate array device. A novel synchronization method applicable to ring networks is proposed. The effect of the communication delay on the power converter operation is studied.
Master of Science
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