A long-baseline (LBL) underwater acoustic communication and localization system was developed for the Virginia Tech Underwater Glider (VTUG). Autonomous underwater vehicles, much like terrestrial and aerial robots require an effective positioning system, like GPS to perform a wide variety of guidance, navigation and control operations. Sea and freshwater attenuate electromagnetic waves (sea water is worse due to higher conductivity) within very few meters of striking the water surface. Since radio frequency communications are unavailable, many undersea systems use acoustic communications instead. Underwater acoustic communication is the technique of sending and receiving data below water. Underwater acoustic positioning is the technique of locating an underwater object. Among the various types of acoustic positioning systems, the LBL acoustic positioning method offers the highest accuracy for underwater vehicle navigation. A system consisting of three acoustic 'beacons which are placed on the surface of the water at known locations was developed. Using an acoustic modem to excite an acoustic transducer to send sound waves from an underwater glider, the range measurements to each of the beacons was calculated. These range measurements along with data from the attitude heading and reference system (AHRS) on board the glider were used to estimate the position of the underwater vehicle. Static and dynamic estimators were implemented. The system also allowed for underwater acoustic communication in the form of heartbeat messages from the glider, which were used to monitor the health of the vehicle. / Master of Science

Submitted by Hellen Luz (hellencrisluz@gmail.com) on 2017-10-04T17:32:51Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_PrototipoDesenvolvimentoAplicacao.pdf: 1668249 bytes, checksum: cd94542f915fbee0247c145c058c84ec (MD5) / Rejected by Edisangela Bastos (edisangela@ufpa.br), reason: on 2017-10-10T17:04:36Z (GMT) / Submitted by Hellen Luz (hellencrisluz@gmail.com) on 2017-10-11T16:43:33Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_PrototipoDesenvolvimentoAplicacao.pdf: 1668249 bytes, checksum: cd94542f915fbee0247c145c058c84ec (MD5) / Approved for entry into archive by Irvana Coutinho (irvana@ufpa.br) on 2017-10-16T13:25:44Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_PrototipoDesenvolvimentoAplicacao.pdf: 1668249 bytes, checksum: cd94542f915fbee0247c145c058c84ec (MD5) / Made available in DSpace on 2017-10-16T13:25:44Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_PrototipoDesenvolvimentoAplicacao.pdf: 1668249 bytes, checksum: cd94542f915fbee0247c145c058c84ec (MD5) Previous issue date: 2010-04-19 / FADESP - Fundação de Amparo e Desenvolvimento da Pesquisa / Este trabalho tem como objetivo o desenvolvimento de um prototipo para aplicação de estrategias de otimização em sistemas xDSL praticos. O prototipo descrito constitui-se de componentes de software e um setup experimental, capaz de gerar estímulos (trafego e ruídos) para uma rede DSL completa, a m de avaliar seu desempenho num ambiente controlado com equipamentos comerciais não modi cados. Os resultados obtidos com o prototipo, bem como suas aplicações no campo de otimização de sistemas DSL são apresentados. / This work describes the development of a prototype for the application of optimization strategies for practical xDSL systems. The prototype described here is made of software components and an experimental setup, capable of generating IP tra c and noise signals, in order to evaluate the performance of a complete DSL network in a controlled environment, with commercial unmodi ed hardware. The results obtained with the prototype as well as its applications for optimization of practical xDSL systems are presented.

Submitted by camilla martins (camillasmmartins@gmail.com) on 2016-12-13T14:28:34Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_MetologiaMedicaoParametros.pdf: 3812788 bytes, checksum: 973677041c916ac2888f276763fb9377 (MD5) / Rejected by Edisangela Bastos (edisangela@ufpa.br), reason: on 2016-12-15T12:16:59Z (GMT) / Submitted by camilla martins (camillasmmartins@gmail.com) on 2016-12-15T14:36:52Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_MetologiaMedicaoParametros.pdf: 3812788 bytes, checksum: 973677041c916ac2888f276763fb9377 (MD5) / Approved for entry into archive by Edisangela Bastos (edisangela@ufpa.br) on 2016-12-19T16:23:18Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_MetologiaMedicaoParametros.pdf: 3812788 bytes, checksum: 973677041c916ac2888f276763fb9377 (MD5) / Made available in DSpace on 2016-12-19T16:23:18Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_MetologiaMedicaoParametros.pdf: 3812788 bytes, checksum: 973677041c916ac2888f276763fb9377 (MD5) Previous issue date: 2007-05-25 / Este trabalho apresenta uma metodologia para a medição dos principais parâmetros relacionados à qualificação do enlace digital do assinante. Para essa metodologia, alguns procedimentos importantes são indicados, tais como: seleção adequada dos equipamentos/dispositivos para as medições, escolha adequada do processo de calibração para as medições e a realização de um tratamento estatístico dos parâmetros medidos: impedância de entrada, função de transferência e parâmetro de espalhamento. A validação da metodologia foi realizada através de alguns estudos de casos considerando duas situações: uma, quando todos os procedimentos de medições foram realizados de acordo com a metodologia e outra, quando as medições não seguiram os procedimentos propostos. Adicionalmente, para comprovar a aplicabilidade da metodologia, foram realizadas comparações entre os dados medidos e alguns modelos teóricos utilizados como referências. Em ambos os casos citados acima, a metodologia se mostrou bastante eficaz e apresentou medições coerentes, dentro de valores confiáveis. / The present work is related to SELT tests by proposing a methodology for measuring the main parameters related to the loop qualification. For the proposed methodology, some important procedures should be followed in order to provide trust measures such as: appropriate selection of the equipments/devices for the measurements, appropriate choice of the calibration process for the measurements and a statistical treatment of the measurements of the parameters which are Input Impedance, Transfer Function and Scattering Parameter. The present work defines such procedures. For validation of the methodology, some studies of cases were accomplished considering two situations: all of the procedures of measuring were made according to a proposed methodology and, the second case; the measurements made did not follow the proposed procedures. Additionally, in order to prove the applicability of the methodology a comparison evaluation was carried out between the measured data and some theoretical models used as references. In both cases (application of the proposed methodology and in the comparison evaluation) the results showed the applicability of methodology. The data were reliable and coherent with the expected values and theory.

Submitted by camilla martins (camillasmmartins@gmail.com) on 2017-03-03T15:47:53Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_TécnicasInteligenciaComputacional.pdf: 1260253 bytes, checksum: 3305f5c206ec272e9417eb11d1c42c5b (MD5) / Approved for entry into archive by Edisangela Bastos (edisangela@ufpa.br) on 2017-03-07T11:31:17Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_TécnicasInteligenciaComputacional.pdf: 1260253 bytes, checksum: 3305f5c206ec272e9417eb11d1c42c5b (MD5) / Made available in DSpace on 2017-03-07T11:31:17Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_TécnicasInteligenciaComputacional.pdf: 1260253 bytes, checksum: 3305f5c206ec272e9417eb11d1c42c5b (MD5) Previous issue date: 2015-05-29 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / A estabilidade das Linhas Digitais do Assinante (DSL) torna-se um grande desafio, quando os serviços conhecidos como Tripe-Play são fornecidos. Esses serviços devem ser confiáveis, ao mesmo tempo que requerem elevada taxa de transmissão e baixa latência, para uma melhor qualidade de experiência. Entretanto as ferramentas para a estabilização das redes DSL, como a adaptação automática da margem (AMA), o Interleaving, a proteção ao ruído impulsivo (INP) e o ruído virtual (VN), geralmente causam impacto ou na taxa de transmissão de dados, ou na latência da transmissão na tentativa de melhorar a estabilidade. O presente trabalho, por outro lado, tem como objetivo apresentar uma nova abordagem para estabilização das redes DSL. Essa abordagem e baseada na coordenação multiusuário do espectro que busca mitigar o efeito da interferência de crosstalk de maneira que o requisito de taxa de dados factível e a restrição de potência sejam alcançados com uma margem de ruído otimizada. Como, apenas os parâmetros da camada física são ajustados, a latência não e afetada pelo método. A questão é então colocada como um problema de otimização de margem e resolvido através de algoritmos evolucionários em conjunto com técnicas de minimização de potência. Experimentos mostram que o método proposto fornece melhoras significantes em termos de margem de ruído, quando comparado com os algoritmos anteriores, aumentando a estabilidade da rede sem penalizar a taxa de bits ou a latência. / The stability of digital subscriber lines (DSL) becomes a major challenge when tripleplay services are provisioned. These services must be reliable, while requiring relatively high transmission rates and low latency for an overall improved quality of experience. However, the stabilization tools available in DSL systems such as the automatic margin adaptation (AMA), interleaving, impulse noise protection (INP) and virtual noise (VN) usually trade o bit rate or latency in an attempt of improving the stability. The current work, on the other hand, presents a novel approach to the stabilization of the DSL lines. This approach is based on multiuser spectra coordination that seeks to mitigate crosstalk interference e ect such that feasible bit rate requirements and power restrictions are met with optimized noise margin. As only physical layer parameters are adjusted, latency is not a ected by the method. The problem is posed as a multiuser margin optimization problem and solved by evolutionary algorithms in conjunction with power minimization techniques. Simulations show that the proposed method provides signi cant improvements in terms of noise margin when compared to a previous algorithm, achieving higher protection for the network without penalizing bit rate or latency.

Foreign direct investment (FDI) in food retailing has generated a considerable amount of attention in both the media and the business world throughout the 199Os, with a strong focus on Asian and Central and Eastern European countries. Among these countries, China is a key player and a nation that no international retailers can afford to ignore due to its population size of 1.2 billion and its rapid economic development. Food retailers from different parts of the world have been keen to use their modern retail concepts and technology to seek expansion opportunities in China. Consequently, two important questions emerge: What does the process of FDI in food retailing entail? Is the retail and distribution market in China easily entered? Regarding the first question, substantial research effort has been vested in this topic. However, a conceptual framework that incorporates the whole scope and complexity of the process is still lacking. For the second question, a prudent scrutiny reveals that foreign food retailers are confronted with a lot of complications due to the legacy of the previous command economy and the unique Chinese social and business structure. The thesis develops an analytical model in which critical variables, and their logical relationships, are used to analyse and explain the process of FDI of food retailers in the contemporary era, using China as the domain for the empirical work. Methodologically, the study adopts a qualitative approach using case studies with thirteen foreign food retailers in China. The research focuses on three main areas: long-term strategic objectives behind retail international expansion, market entry issues, and retail operational issues. Firstly, the long-term strategic objectives that underlie retailers’ undertaking of foreign direct investment are investigated. Evidence shows that the prevailing concept of reactive retail internationalisation and the tenet of psychic distance do not fully reflect the reality of retail internationalisation. Secondly, three issues related to market entry are explored. The first issue is the legal and regulatory infrastructures that foreign retailers face when entering China. The second issue is the selection of Chinese partners, managing partner relationships and the share of managerial control. The third issue is the technical and political procedures of site selection and store development. The empirical work reveals that the lack of a systematic and well-developed legal system complicates the process of foreign direct investment and having a Chinese partner who possesses the appropriate guanxi network alleviates the problem. Furthermore, the exercise of dominant control over operational and managerial issues is practised by the foreign retailers in their joint ventures. Significant conflicts between partners appear not to exist under such an arrangement. On the other hand, political procedures of site selection and store development are found to be onerous. In terms of technical procedures, respondents reported that the methods that are being used in developed countries are not entirely applicable in China. The third area on which the research focuses is operational issues that foreign food retailers confront in the host countries. These include supply chain management; adjustment and adaptation; and development of human resources. Findings suggest that there are two types of retail know-how: core and peripheral. No changes to core elements should be made in the overseas operation so that the uniqueness of the individual retailer is preserved. Adjustments, however, have to be made to peripheral elements in order to match particularities of local consumer demand. A learningoriented culture within a retail organisation is found to be an important underlying element that contributes significantly towards successful retail internationalisation. Taking a holistic perspective, the foreign direct investment behaviour in the retailing sector and the manufacturing sector, from which the prevailing foreign direct investment theories were developed, appear to be very different. The foreign direct investment behaviour of retailers seems to be better explained and understood within a framework that emphasises market power seeking, stresses the dynamics of different elements that constitute retail know-how, and underscores the notion of knowledge accumulation and utilisation.

Orthogonal frequency-division multiplexing (OFDM) has been adopted by many broadband wireless communication systems for the simplicity of the receiver technique to support high data rates and user mobility. However, studies also show that the advantage of OFDM over the single-carrier modulation schemes could be substantially compromised by timing or frequency estimation errors at the receiver. In this thesis we investigate the synchronization problem for practical OFDM systems using a system model generalized from the IEEE 802.11 and IEEE 802.16 standards. For preamble based synchronization schemes, which are most common in the downlink of wireless communication systems, we propose a novel timing acquisition algorithm which minimizes false alarm probability and indirectly improves correct detection probability. We then introduce a universal fractional carrier frequency offset (CFO) estimator that outperforms conventional methods at low signal to noise ratio with lower complexity. More accurate timing and frequency estimates can be obtained by our proposed frequency-domain algorithms incorporating channel knowledge. We derive four joint frequency, timing, and channel estimators with different approximations, and then propose a hybrid integer CFO estimation scheme to provide flexible performance and complexity tradeoffs. When the exact channel delay profile is unknown at the receiver, we present a successive timing estimation algorithm to solve the timing ambiguity. Both analytical and simulation results are presented to confirm the performance of the proposed methods in various realistic channel conditions. The ranging based synchronization scheme is most commonly used in the uplink of wireless communication systems. Here we propose a successive multiuser detection algorithm to mitigate multiple access interference and achieve better performance than that of conventional single-user based methods. A reduced-complexity version of the successive algorithm feasible for hardware real-time implementation is also presented in the thesis. To better understand the performance of a ranging detector from a system point of view, we develop a technique that can directly translate a detector�s missed detection probability into the maximum number of users that the method can support in one cell with a given number of ranging opportunities. The analytical results match the simulations reasonably well and show that the proposed successive algorithms allow a base station to serve more than double the number of users supported by the conventional methods. Finally, we investigate inter-carrier interference which is caused by the timevarying communication channels. We derive the bounds on the power of residual inter-carrier interference that cannot be mitigated by a frequency-domain equalizer with a given number of taps. We also propose a Turbo equalization scheme using the novel grouped Particle filter, which approaches the performance of the Maximum A Posterior algorithm with much lower complexity.

Our thesis is about development of equipment, which combine two technology. First technology is wattmeter which is used to energy measurement and second is Power line communication. Wattmeter needs two variables for measurement, voltage and current. Voltage measurement is less difficult than measurement of current. Voltage can be reduce and measured by A/D converter. Current has to be transform to voltage and than can be measured same way. To do that we use current transformer. Than we design program for the microcontroller, involvement and PCB. Wattmeter is connect to PLC modem which has been chosen. Fusing this two technology we create wattmeter network. Next step was program which is used to network control and data collecting. This data are used to create charts in web application.

This semestral thesis focuses on the circuit design of the repeater for PLC communication in order to achieve greater distance in communication. It can also serve as a bridge for a separate modem device power grid. In this work we discuss the involvement of individual assembly parts repeater and proposed method of connection.

Submitted by Samira Prince (prince@ufpa.br) on 2012-10-11T15:11:23Z No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_ImplementacaoSoftwareCodificacao.pdf: 2858087 bytes, checksum: 6c4682b32c60fc6ba383677c0c0dcb02 (MD5) / Approved for entry into archive by Ana Rosa Silva(arosa@ufpa.br) on 2012-10-11T16:38:32Z (GMT) No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_ImplementacaoSoftwareCodificacao.pdf: 2858087 bytes, checksum: 6c4682b32c60fc6ba383677c0c0dcb02 (MD5) / Made available in DSpace on 2012-10-11T16:38:32Z (GMT). No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_ImplementacaoSoftwareCodificacao.pdf: 2858087 bytes, checksum: 6c4682b32c60fc6ba383677c0c0dcb02 (MD5) Previous issue date: 2011 / Este trabalho apresenta a implementação em software da codificação de canal utilizada no padrão ADSL. A teoria da codificação de canal e descrita, bem como a codificação de canal implementada no Software Modem ADSL utilizando o ambiente de desenvolvimento Ptolemy II. A implementação de um modelo de ruído impulsivo também é apresentada. Para garantir que a implementação obedeça o padrão do ADSL, testes utilizando o analisador de sistemas DSL TraceSpan são descritos. O trabalho apresenta ainda um exemplo de aplicação do Software Modem ADSL, caracterizado por um estudo de caso sobre os efeitos do ruído impulsivo na transmissão de vídeo, analisando o impacto de alguns parâmetros da codificação de canal na correção dos erros. / This work describes the implementation in software of the channel coding used in the ADSL standard. The theory of channel coding is described, as well as the channel coding implemented in the Software Modem ADSL using the development environment Ptolemy II. The implementation of a impulsive noise model is also presented. To ensure that the implementation meets the ADSL standard, tests using the DSL systems analyzer TraceSpan are described. This work also presents an application example of the Software Modem ADSL, characterized by a study case on the e ects of impulsive noise in the video transmission, analyzing the impact of some parameters of channel coding in the correction of errors.

Submitted by Irvana Coutinho (irvana@ufpa.br) on 2011-03-25T21:55:49Z No. of bitstreams: 1 CARDOSO, Diego Lisboa PPGEngenharia Elétrica tese.pdf: 1990062 bytes, checksum: 80be122205e774a6962464432b1dc73d (MD5) / Made available in DSpace on 2011-03-25T21:55:49Z (GMT). No. of bitstreams: 1 CARDOSO, Diego Lisboa PPGEngenharia Elétrica tese.pdf: 1990062 bytes, checksum: 80be122205e774a6962464432b1dc73d (MD5) Previous issue date: 2010-03-26 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / A tecnologia DSL- Digital Subscriber Line permitem um acesso universal de banda larga, com redução de custo e tempo de implantação necessários, quando comparadas a outras redes de acesso. DSL pode ser considerada uma rede de banda larga de grande capilaridade, uma vez que utiliza uma combinação de infra-estrutura de telefonia existente e a tecnologia de transmissão. Não obstante, a rede DSL precisa ser amplamente compreendida, de maneira que suas principais vantagens não sejam suplantadas pela ineficiência geral do sistema. Esta tese apresenta uma abordagem baseada em estratégias que possibilitem o planejamento de redes de comunicação que a priori não foram implementadas para suportar fluxos Triple Play (pré-requisito obrigatório diante do perfil atual de usuários da Internet). Será mostrado que, a partir do uso de medidas reais e análises probabilísticas, é possível elaborar o planejamento de redes de comunicação, considerando os parâmetros físicos e lógicos, tais como: o caminho de transmissão, a influência do ruído na comunicação, os protocolos utilizados e tráfego de Triple Play (voz, vídeo e dados). / Recently, the Next Generation Network (NGN) have emerged as a viable alternative to merge the data, voice and video transmission over a single network, while maintaining reasonable standards for quality of service. However, despite the improvements brought by the NGN philosophy, many developing countries lack the infrastructure necessary to implement such technology. In this context, technologies such as DSL (Digital Subscriber Line) allows universal access to broadband, with reduced cost and time, when compared to others access networks. In many third world countries, DSL can be considered a broadband network of high capillarity, since it uses a combination of the existing telephony infrastructure and transmission technologies However, the DSL network needs to be widely understood, so that its main advantages are not outweighed by the inefficiency of the system. Therefore, the implementation of a planning policy to aid in this process, taking into account the current needs of applications (voice, video and data) is of major importance. This thesis presents an approach based on strategies to facilitate the planning of communication networks which, a priori, were not implemented to support triple play streams (a prerequisite, nowadays, for the current profile of Internet users). It will be shown that, from the use of actual measurements and probabilistic analysis, it is possible to enable the planning of communication networks, considering physical and software parameters, such as the transmission path, the influence of noise in the communication, the protocols used, and traffic of Triple Play (voice, video and data) applications.