869 resultados para Wideband Receivers


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Vivemos uma era em que os distintos pontos geográficos do globo se tornaram mais próximos em virtude do estreitamento proporcionado pelo profundo avanço tecnológico dos meios de transporte, mas também pela evolução vertiginosa das novas tecnologias de comunicação que têm permitido fazer com que eventos ocorridos numa determinada região do planeta sejam vistos num outro ponto geográfico, com diferença de apenas algumas horas ou mesmo em tempo real. Graças a esse avanço tecnológico e ao consequente desenvolvimento do processo comercial de transmissão e receção de sinal de televisão por satélite e/ou por cabo, a par do veloz fluxo de informação, são também disponibilizados aos recetores conteúdos de entretenimento que refletem práticas culturais com características marcadamente identitárias, de outras sociedades. Considerando que determinadas condicionantes históricas e económicas do mundo não possibilitam um fluxo bidirecional dos referidos produtos televisivos e o facto de as empresas prestadoras destes serviços se dedicarem exclusivamente à venda de produtos, cujos conteúdos retratam práticas culturais de determinados países (em melhores condições de desenvolvimento económico e tecnológico) existe a possibilidade de se estar diante de um processo de difusão cultural e de aculturação de que são alvo os cidadãos dos países recetores dos referidos conteúdos. Este trabalho pretende efetuar uma análise do impacto das telenovelas brasileiras no comportamento dos luandenses, baseando-se numa pesquisa desenvolvida nos sete municípios da Província de Luanda. Os resultados da pesquisa revelam a presença de componentes culturais brasileiras em práticas sociais dos luandenses há várias gerações e mostram o papel transformador que as telenovelas brasileiras continuam a desempenhar nesta sociedade. A ausência nos canais de televisão locais de mensagens e imagens das representações endógenas favorece a apropriação de práticas culturais exógenas emitidas pelas produções brasileiras e a sua ressignificação no quotidiano local.

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O princípio do posicionamento por GNSS baseia-se, resumidamente, na resolução de um problema matemático que envolve a observação das distâncias do utilizador a um conjunto de satélites com coordenadas conhecidas. A posição resultante pode ser calculada em modo absoluto ou relativo. O posicionamento absoluto necessita apenas de um recetor para a determinação da posição. Por sua vez, o posicionamento relativo implica a utilização de estações de referência e envolve a utilização de mais recetores para além do pertencente ao próprio utilizador. Assim, os métodos mais utilizados na determinação da posição de uma plataforma móvel, com exatidão na ordem dos centímetros, baseiam-se neste último tipo de posicionamento. Contudo, têm a desvantagem de estarem dependentes de estações de referência, com um alcance limitado, e requerem observações simultâneas dos mesmos satélites por parte da estação e do recetor. Neste sentido foi desenvolvida uma nova metodologia de posicionamento GNSS em modo absoluto, através da modelação ou remoção dos erros associados a cada componente das equações de observação, da utilização de efemérides precisas e correções aos relógios dos satélites. Este método de posicionamento tem a designação Precise Point Positioning (PPP) e permite manter uma elevada exatidão, equivalente à dos sistemas de posicionamento relativo. Neste trabalho, após um estudo aprofundado do tema, foi desenvolvida uma aplicação PPP, de índole académica, com recurso à biblioteca de classes C++ do GPS Toolkit, que permite determinar a posição e velocidade do recetor em modo cinemático e em tempo real. Esta aplicação foi ensaiada utilizando dados de observação de uma estação estática (processados em modo cinemático) e de uma estação em movimento instalada no NRP Auriga. Os resultados obtidos permitiram uma exatidão para a posição na ordem decimétrica e para a velocidade na ordem do cm/s.

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vulnerabilidad a deslizamientos ubicado en el Cerro Tamuga del cantón Paute, provincia del Azuay, la metodología empleada consiste en utilizar la técnica DGPS (Differential Global Positioning System), la misma que incluye el uso simultaneo de dos o más receptores, el método de medida empleado para las observaciones DGPS es el estático rápido con un tiempo de medida de diez minutos para cada hito, los resultados fueron comparados con mediciones realizadas con estación total, para lo que se aplicó el método de medida y cálculo de triangulación; que consiste en observar desde dos bases diferentes al mismo hito para realizar la triangulación y procesamiento de los datos. Durante la etapa de muestreo se realizó 20 campañas de medición con técnicas DGPS, monitoreando un total de 14 hitos, con técnicas convencionales (Topográficas) se realizó 7 campañas y se monitoreó 14 hitos. De estos datos se obtiene la diferencia entre la última y la primera medición tanto para valores de X, Y y Z, y por tanto se obtiene la variación de precisión para los dos métodos de medición (DGPS y Estación Total). Con los resultados (∆X, ∆Y, ∆Z) se realiza el análisis de la direccionalidad de los vectores de desplazamiento mediante la diferencia entre el promedio de todas las mediciones con el primer punto medido. Los resultados DGPS presentan menor variabilidad de los datos, por lo que se sugiere emplear esta técnica en la medición de desplazamiento en extensiones grandes. Con relación al caso de estudio del Cerro Tamuga, se determinó que mediante las mediciones con DGPS, éste no presenta movimientos, pero se deben continuar las campañas de monitoreo para analizar la situación a largo plazo.

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In geophysics there are several steps in the study of the Earth, one of them is the processing of seismic records. These records are obtained through observations made on the earth surface and are useful for information about the structure and composition of the inaccessible parts in great depths. Most of the tools and techniques developed for such studies has been applied in academic projects. The big problem is that the seismic processing power unwanted, recorded by receivers that do not bring any kind of information related to the reflectors can mask the information and/or generate erroneous information from the subsurface. This energy is known as unwanted seismic noise. To reduce the noise and improve a signal indicating a reflection, without losing desirable signals is sometimes a problem of difficult solution. The project aims to get rid of the ground roll noise, which shows a pattern characterized by low frequency, low rate of decay, low velocity and high amplituds. The Karhunen-Loève Transform is a great tool for identification of patterns based on the eigenvalues and eigenvectors. Together with the Karhunen-Loève Transform we will be using the Singular Value Decomposition, since it is a great mathematical technique for manipulating data

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The actor is an actor during all the phases of creation and development of his character. (S) He goes beyond the moment of interpreting. In this sense, in her (his) daily life, the actor may use her (his) potential to extract from reality the necessary elements for the work of creation. This is a theoretical research which focus on the concept of presence in the actor s work, stretching the concept beyond the scene, encompassing different components such as the body, the word, the silence, the technique and the acting as the actor s stance in regards to his own reality. The objective of such stance is to integrate him (her) self in the environment, balancing his (hers) inner life with the outside life flow. To reach this objective, the research drew theoretical resources from the concept of presence in the actor s work according to BROOK, BARBA, GROTOWSKI and MNOUCHKINE and the studies on reception theory in ISER, 1996; GUMBRECHT, 2010. Thus, the dialogue between reader and actor high lights both as receivers in this work. A practical description of a street theater Kamchàtka show, featured by the Kamchàtka Company is used as an example of the research on the presence. The elements localized in this show are: play, listening, word, silence, meaning, relationship with here and now and the effects of the said presence

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This paper investigates the robust and accurate capture of human joint poses and bio-kinematic movements for exercise monitoring in real-time tele-rehabilitation applications. Recently developed model-based estimation ideas are used to improve the accuracy, robustness, and real-time characteristics considered vital for applications, where affordability and domestic use are the primary focus. We use the spatial diversity of the arbitrarily positioned Microsoft Kinect receivers to improve the reliability and promote the uptake of the concept. The skeleton-based information is fused to enhance accuracy and robustness, critical for biomedical applications. A specific version of a robust Kalman filter (KF) in a linear framework is employed to ensure superior estimator convergence and real-time use, compared to other commonly used filters. The algorithmic development was conducted in a generic form and computer simulations were conducted to verify our assertions. Hardware implementations were carried out to test the viability of the proposed state estimator in terms of the core requirements of reliability, accuracy, and real-time use. Performance of the overall system implemented in an information fusion context was evaluated against the commercially available and industry standard Vicon system for different exercise routines, producing comparable results with much less infrastructure and financial investment.

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Understanding the links between external variables such as habitat and interactions with conspecifics and animal space-use is fundamental to developing effective management measures. In the marine realm, automated acoustic tracking has become a widely used method for monitoring the movement of free-ranging animals, yet researchers generally lack robust methods for analysing the resulting spatial-usage data. In this study, acoustic tracking data from male and female broadnose sevengill sharks Notorynchus cepedianus, collected in a system of coastal embayments in southeast Tasmania were analyzed to examine sex-specific differences in the sharks' coastal space-use and test novel methods for the analysis of acoustic telemetry data. Sex-specific space-use of the broadnose sevengill shark from acoustic telemetry data was analysed in two ways: The recently proposed spatial network analysis of between-receiver movements was employed to identify sex-specific space-use patterns. To include the full breadth of temporal information held in the data, movements between receivers were furthermore considered as transitions between states of a Markov chain, with the resulting transition probability matrix allowing the ranking of the relative importance of different parts of the study area. Both spatial network and Markov chain analysis revealed sex-specific preferences of different sites within the study area. The identification of priority areas differed for the methods, due to the fact that in contrast to network analysis, our Markov chain approach preserves the chronological sequence of detections and accounts for both residency periods and movements. In addition to adding to our knowledge of the ecology of a globally distributed apex predator, this study presents a promising new step towards condensing the vast amounts of information collected with acoustic tracking technology into straightforward results which are directly applicable to the management and conservation of any species that meet the assumptions of our model.

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Opto-acoustic imaging is a growing field of research in recent years, providing functional imaging of physiological biomarkers, such as the oxygenation of haemoglobin. Piezo electric transducers are the industry standard detector for ultrasonics, but their limited bandwidth, susceptibility to electromagnetic interference and their inversely proportional sensitivity to size all affect the detector performance. Sensors based on polymer optical fibres (POF) are immune to electromagnetic interference, have lower acoustic impedance and a reduced Young's Modulus compared to silica fibres. Furthermore, POF enables the possibility of a wideband sensor and a size appropriate to endoscopy. Micro-structured POF (mPOF) used in an interferometric detector has been shown to be an order of magnitude more sensitive than silica fibre at 1 MHz and 3 times more sensitive at 10 MHz. We present the first opto-acoustic measurements obtained using a 4.7mm PMMA mPOF Bragg grating with a fibre diameter of 130 μm and present the lateral directivity pattern of a PMMA mPOF FBG ultrasound sensor over a frequency range of 1-50 MHz. We discuss the impact of the pattern with respect to the targeted application and draw conclusions on how to mitigate the problems encountered.

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Non-orthogonal multiple access (NOMA) is emerging as a promising multiple access technology for the fifth generation cellular networks to address the fast growing mobile data traffic. It applies superposition coding in transmitters, allowing simultaneous allocation of the same frequency resource to multiple intra-cell users. Successive interference cancellation is used at the receivers to cancel intra-cell interference. User pairing and power allocation (UPPA) is a key design aspect of NOMA. Existing UPPA algorithms are mainly based on exhaustive search method with extensive computation complexity, which can severely affect the NOMA performance. A fast proportional fairness (PF) scheduling based UPPA algorithm is proposed to address the problem. The novel idea is to form user pairs around the users with the highest PF metrics with pre-configured fixed power allocation. Systemlevel simulation results show that the proposed algorithm is significantly faster (seven times faster for the scenario with 20 users) with a negligible throughput loss than the existing exhaustive search algorithm.

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Recent marine long-offset transient electromagnetic (LOTEM) measurements yielded the offshore delineation of a fresh groundwater body beneath the seafloor in the region of Bat Yam, Israel. The LOTEM application was effective in detecting this freshwater body underneath the Mediterranean Sea and allowed an estimation of its seaward extent. However, the measured data set was insufficient to understand the hydrogeological configuration and mechanism controlling the occurrence of this fresh groundwater discovery. Especially the lateral geometry of the freshwater boundary, important for the hydrogeological modelling, could not be resolved. Without such an understanding, a rational management of this unexploited groundwater reservoir is not possible. Two new high-resolution marine time-domain electromagnetic methods are theoretically developed to derive the hydrogeological structure of the western aquifer boundary. The first is called Circular Electric Dipole (CED). It is the land-based analogous of the Vertical Electric Dipole (VED), which is commonly applied to detect resistive structures in the subsurface. Although the CED shows exceptional detectability characteristics in the step-off signal towards the sub-seafloor freshwater body, an actual application was not carried out in the extent of this study. It was found that the method suffers from an insufficient signal strength to adequately delineate the resistive aquifer under realistic noise conditions. Moreover, modelling studies demonstrated that severe signal distortions are caused by the slightest geometrical inaccuracies. As a result, a successful application of CED in Israel proved to be rather doubtful. A second method called Differential Electric Dipole (DED) is developed as an alternative to the intended CED method. Compared to the conventional marine time-domain electromagnetic system that commonly applies a horizontal electric dipole transmitter, the DED is composed of two horizontal electric dipoles in an in-line configuration that share a common central electrode. Theoretically, DED has similar detectability/resolution characteristics compared to the conventional LOTEM system. However, the superior lateral resolution towards multi-dimensional resistivity structures make an application desirable. Furthermore, the method is less susceptible towards geometrical errors making an application in Israel feasible. In the extent of this thesis, the novel marine DED method is substantiated using several one-dimensional (1D) and multi-dimensional (2D/3D) modelling studies. The main emphasis lies on the application in Israel. Preliminary resistivity models are derived from the previous marine LOTEM measurement and tested for a DED application. The DED method is effective in locating the two-dimensional resistivity structure at the western aquifer boundary. Moreover, a prediction regarding the hydrogeological boundary conditions are feasible, provided a brackish water zone exists at the head of the interface. A seafloor-based DED transmitter/receiver system is designed and built at the Institute of Geophysics and Meteorology at the University of Cologne. The first DED measurements were carried out in Israel in April 2016. The acquired data set is the first of its kind. The measured data is processed and subsequently interpreted using 1D inversion. The intended aim of interpreting both step-on and step-off signals failed, due to the insufficient data quality of the latter. Yet, the 1D inversion models of the DED step-on signals clearly detect the freshwater body for receivers located close to the Israeli coast. Additionally, a lateral resistivity contrast is observable in the 1D inversion models that allow to constrain the seaward extent of this freshwater body. A large-scale 2D modelling study followed the 1D interpretation. In total, 425 600 forward calculations are conducted to find a sub-seafloor resistivity distribution that adequately explains the measured data. The results indicate that the western aquifer boundary is located at 3600 m - 3700 m before the coast. Moreover, a brackish water zone of 3 Omega*m to 5 Omega*m with a lateral extent of less than 300 m is likely located at the head of the freshwater aquifer. Based on these results, it is predicted that the sub-seafloor freshwater body is indeed open to the sea and may be vulnerable to seawater intrusion.

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Older people have been identified as being at risk of social exclusion. However, despite the fact that care is commonly required in later life and the majority of that care provided by informal carers, a connection between social exclusion and informal care-receipt has rarely been considered. The aim of this study was to examine how informal care-receipt is related to social exclusion. A face-to-face questionnaire survey on social exclusion and informal care-receipt was carried out among older people (n=1255) living in Barnsley, United Kingdom. Multivariable analyses examined the association between social exclusion and categories of informal care-receipt: care receiver; assurance receiver; non-receiver with no need; non-receiver with need. Compared to being a non-receiver with no need participants were more likely to be a care receiver or assurance receiver if they had higher levels of social exclusion. The highest level of social exclusion, however, was found in non-receivers with need. Despite a lack of informal care and support, formal practical support and personal care was also low in this latter group. Findings are discussed in relation to the conceptualisation of care-receipt and how contact with medical services could be an opportunity for identification and appropriate referral of non-receivers with need.

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Extensive livestock production is supported by natural and biodiverse pastures, characterized by marked seasonal variation of biomass, plant species and growth stage. The use of the food resources and the occupation of grazing space can be very heterogeneous in such conditions due to ruminants grazing behaviour. Successful grazing and pasture management requires an understanding of the adjustment mechanisms behind the grazing behaviour that enables adaptation to grazing conditions. Use of GNSS technology allows a quick and effective grazing data collection which is, however expensive, limiting its application to research purposes. This paper reviews the principles for the application of GNSS technology and evaluates the use of inexpensive commercial GNSS receivers (commercial of the shelf - COTS: CatTrackTM”). Six receivers were used for six data collection period over two months of continuous grazing on a natural pasture. The measured static and dynamic accuracy of the receivers is 14m and 40m, respectively. The precision was 3m and the reliability 80%. The tested equipment allows the differentiation between animal activities (grazing, resting and transit). It also determines sheep locations, allowing the characterization of patterns, pathways and preferred areas. It is concluded that the COTS equipment has a high quality / price ratio, so it can become an important support decision tool essential to a more precise pasture management.

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Mark-recapture tagging and acoustic telemetry were used to study the movements of Diplodus sargus within the Pessegueiro Island no-take Marine Protected Area (MPA), (Portugal) and assess its size adequacy for this species' protection against fishing activities. Therefore, 894 Diplodus sargus were captured and marked with conventional plastic t-bar tags. At the same time, 19 D. sargus were tagged with acoustic transmitters and monitored by 20 automatic acoustic receivers inside the no-take MPA for 60 days. Recapture rate of conventionally tagged specimens was 3.47%, most occurring during subsequent marking campaigns. One individual however was recaptured by recreational fishermen near Faro (ca. 250 km from the tagging location) 6 months after release. Furthermore, three specimens were recaptured in October 2013 near releasing site, one year after being tagged. Regarding acoustic telemetry, 18 specimens were detected by the receivers during most of the study period. To analyse no-take MPA use, the study site was divided into five areas reflecting habitat characteristics, three of which were frequently used by the tagged fish: Exterior, Interior Protected and Interior Exposed areas. Information on no-take protected area use was also analysed according to diel and tidal patterns. Preferred passageways and permanence areas were identified and high site fidelity was confirmed. The interaction between tide and time of day influenced space use patterns, with higher and more variable movements during daytime and neap tides. This no-take MPA proved to be an important refuge and feeding area for this species, encompassing most of the home ranges of tagged specimens. Therefore, it is likely that this no-take MPA is of adequate size to protect D. sargus against fishing activities, thus contributing to its sustainable management in the region.