977 resultados para Direct digital synthesizer


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A direct twos-complement parallel array multiplication algorithm is introduced and modified for digital optical numerical computation. The modified version overcomes the problems encountered in the conventional optical twos-complement algorithm. In the array, all the summands are generated in parallel, and the relevant summands having the same weights are added simultaneously without carries, resulting in the product expressed in a mixed twos-complement system. In a two-stage array, complex multiplication is possible with using four real subarrays. Furthermore, with a three-stage array architecture, complex matrix operation is straightforwardly accomplished. In the experiment, parallel two-stage array complex multiplication with liquid-crystal panels is demonstrated.

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A closed-loop control technique based on monitoring phase current risetime for switched reluctance (SR) motors without direct rotor-position sensors has been studied and implemented successfully. In this technique the variation in incremental phase inductance in a SR motor is used to detect rotor position. A control circuit for current-waveform-based rotor position detection has been implemented using hard-wire digital circuits. Torque-speed and system-efficiency characteristics resulting from the application of the method to a 4-kW, four-phase SR motor with an IGBT drive are presented.

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A modular image capture system with close integration to CCD cameras has been developed. The aim is to produce a system capable of integrating CCD sensor, image capture and image processing into a single compact unit. This close integration provides a direct mapping between CCD pixels and digital image pixels. The system has been interfaced to a digital signal processor board for the development and control of image processing tasks. These have included characterization and enhancement of noisy images from an intensified camera and measurement to subpixel resolutions. A highly compact form of the image capture system is in an advanced stage of development. This consists of a single FPGA device and a single VRAM providing a two chip image capturing system capable of being integrated into a CCD camera. A miniature compact PC has been developed using a novel modular interconnection technique, providing a processing unit in a three dimensional format highly suited to integration into a CCD camera unit. Work is under way to interface the compact capture system to the PC using this interconnection technique, combining CCD sensor, image capture and image processing into a single compact unit. ©2005 Copyright SPIE - The International Society for Optical Engineering.

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This paper proposes a fast-settling frequency-presetting PLL frequency synthesizer. A mixed-signal VCO and a digital processor are developed to accurately preset the frequency of VCO and greatly reduce the settling time. An auxiliary tuning loop is introduced in order to reduce reference spur caused by leakage current. The digital processor can automatically compensate presetting frequency variation with process and temperature, and control the operation of the auxiliary tuning loop. A 1.2 GHz integer-N synthesizer with 1 MHz reference input Was implemented in a 0.18μm process. The measured results demonstrate that the typical settling time of the synthesizer is less than 3μs,and the phase noise is -108 dBc/Hz@1MHz.The reference spur is -52 dBc.

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With the growing demand for high-speed and high-quality short-range communication, multi-band orthogonal frequency division multiplexing ultra-wide band (MB-OFDM UWB) systems have recently garnered considerable interest in industry and in academia. To achieve a low-cost solution, highly integrated transceivers with small die area and minimum power consumption are required. The key building block of the transceiver is the frequency synthesizer. A frequency synthesizer comprised of two PLLs and one multiplexer is presented in this thesis. Ring oscillators are adopted for PLL implementation in order to drastically reduce the die area of the frequency synthesizer. The poor spectral purity appearing in the frequency synthesizers involving mixers is greatly improved in this design. Based on the specifications derived from application standards, a design methodology is presented to obtain the parameters of building blocks. As well, the simulation results are provided to verify the performance of proposed design.

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A new method for modeling-frequency-dependent boundaries in finite-difference time-domain (FDTD) and Kirchhoff variable digital waveguide mesh (K-DWM) room acoustics simulations is presented. The proposed approach allows the direct incorporation of a digital impedance filter (DIF) in the Multidimensional (2D or 3D) FDTD boundary model of a locally reacting surface. An explicit boundary update equation is obtained by carefully constructing a Suitable recursive formulation. The method is analyzed in terms of pressure wave reflectance for different wall impedance filters and angles of incidence. Results obtained from numerical experiments confirm the high accuracy of the proposed digital impedance filter boundary model, the reflectance of which matches locally reacting surface (LRS) theory closely. Furthermore a numerical boundary analysis (NBA) formula is provided as a technique for an analytic evaluation of the numerical reflectance of the proposed digital impedance filter boundary formulation.

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Background: Digital pathology provides a digital environment for the management and interpretation of pathological images and associated data. It is becoming increasing popular to use modern computer based tools and applications in pathological education, tissue based research and clinical diagnosis. Uptake of this new technology is stymied by its single user orientation and its prerequisite and cumbersome combination of mouse and keyboard for navigation and annotation.

Methodology: In this study we developed SurfaceSlide, a dedicated viewing platform which enables the navigation and annotation of gigapixel digitised pathological images using fingertip touch. SurfaceSlide was developed using the Microsoft Surface, a 30 inch multitouch tabletop computing platform. SurfaceSlide users can perform direct panning and zooming operations on digitised slide images. These images are downloaded onto the Microsoft Surface platform from a remote server on-demand. Users can also draw annotations and key in texts using an on-screen virtual keyboard. We also developed a smart caching protocol which caches the surrounding regions of a field of view in multi-resolutions thus providing a smooth and vivid user experience and reducing the delay for image downloading from the internet. We compared the usability of SurfaceSlide against Aperio ImageScope and PathXL online viewer.

Conclusion: SurfaceSlide is intuitive, fast and easy to use. SurfaceSlide represents the most direct, effective and intimate human–digital slide interaction experience. It is expected that SurfaceSlide will significantly enhance digital pathology tools and applications in education and clinical practice.

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The aim of this study was to explore the impact of interaction (through gathering local field data and engaging in remote reciprocal presentations) on aspects of multicultural awareness. Sixty-six 11-12-year-old Scottish primary school pupils collected data in the field from their local community through questionnaires, interviews, direct observation, digital images and video. From this they distilled a multimedia presentation, delivered by videoconference to a partner school in the USA, who reciprocated. There was some evidence of pre-post project gains in the complexity of the children's perceptions of their community environment, the ethnicity of their community, their own ethnicity, and news images. The children's use of language to define ethnicity also became more complex and their attitudes toward ethnic minorities became more inclusive. The implications for practice, policy and future research were explored. © 2004 Elsevier Ltd. All rights reserved.

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BACKGROUND: Lacrimo-auriculo-dento-digital (LADD) syndrome (OMIM #149730) is an autosomal-dominant congenital disorder that can be caused by heterozygous mutations in the tyrosine kinase domains of the genes encoding fibroblast growth factor receptors 2 (FGFR2) and 3 (FGFR3), and has been found in association with a mutation in the FGF10 gene, which encodes an Fgfr ligand. Clinical signs vary, but the condition is characterised by involvement of the lacrimal and salivary systems, cup-shaped ears, hearing loss and dental abnormalities. Additional features may include involvement of the hands and feet with other body systems particularly the kidneys.

CASE REPORT: Previous literature on the subject has been reviewed and this case is the first presentation of LADD syndrome in the Republic of Ireland, as a sporadic case in a 12-year-old girl who exhibited a range of dental and digital anomalies.

TREATMENT: Her general medical practitioner managed her medical care whilst her oral care necessitated a multidisciplinary approach involving restorative and orthodontic elements.

FOLLOW-UP: The initial restorative phase of treatment has successfully improved the appearance of the patient's anterior teeth using direct resin composite build-ups.

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A novel digital image correlation (DIC) technique has been developed to track changes in textile yarn orientations during shear characterisation experiments, requiring only low-cost digital imaging equipment. Fabric shear angles and effective yarn strains are calculated and visualised using this new DIC technique for bias extension testing of an aerospace grade, carbon-fibre reinforcement material with a plain weave architecture. The DIC results are validated by direct measurement, and the use of a wide bias extension sample is evaluated against a more commonly used narrow sample. Wide samples exhibit a shear angle range 25% greater than narrow samples and peak loads which are 10 times higher. This is primarily due to excessive yarn slippage in the narrow samples; hence, the wide sample configuration is recommended for characterisation of shear properties which are required for accurate modelling of textile draping.

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De todas as áreas que sofrerão alterações com o surgimento das Redes Sociais, as Relações Públicas encontram-se na fila da frente desde o seu começo, uma vez que os social media implicam um público e o estabelecimento de um relacionamento com este. Mesmo as dinâmicas presentes nas RP antes da era 2.0, como é o exemplo das relações com os media, interacção com stakeholders ou a gestão de crises, não só estão presentes nas Redes Sociais como são acentuadas e amplificadas por estas. Neste mundo digital, as marcas de moda ligadas ao prêt-à-porter expandem a sua comunicação a outro nível, adaptando-se às novas tecnologias e tirando o máximo partido do potencial que estas têm para lhes oferecer. Apostam em redes sociais como o Facebook e os Blogs da área da moda & beleza de modo a envolver e cativar o seu público-alvo e stakeholders de uma forma muito mais directa, onde estes têm agora uma voz activa e um papel determinante no sucesso da marca. Idealizadas para gerar notoriedade e aumentar a reputação das marcas, como se demonstra ao longo do presente Relatório de Estágio, as Redes Sociais são agora o melhor amigo das marcas e das Relações Públicas.

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I (Prática pedagógica)- Esta secção do Relatório de Estágio pretende apresentar elementos referentes ao Estágio do Ensino Especializado da Música no ensino do saxofone, efectuado na Escola de Música Luís António Maldonado Rodrigues, no ano lectivo 2012/2013. Neste estágio foram envolvidos e analisados três alunos, em níveis distintos de desenvolvimento, mas com orientações semelhantes no que respeita à organização do trabalho. Para cada aluno foram realizados trinta planos de aula, uma planificação anual e três gravações vídeo/áudio em contexto de sala de aula, permitindo uma análise e reflexão mais profunda do trabalho docente. A secção é composta pela caracterização da escola onde se realizou o estágio, através da sua contextualização/funcionamento, dos seus espaços e equipamentos, recursos humanos existentes e organização pedagógica. Posteriormente é efectuada a caracterização dos três alunos envolvidos no estágio, baseada na experiência docente e nos conhecimentos fornecidos pelas Unidades Curriculares do Mestrado em Ensino da Música. Seguidamente descrevem-se as práticas lectivas desenvolvidas ao longo do ano lectivo por parte do docente, incorporando linhas orientadoras da docência aplicadas na prática pedagógica. É feita uma análise crítica da actividade docente no âmbito do estágio do Ensino Especializado da Música, e, por último, uma conclusão desta primeira secção. .

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The nature tourism experienced a great expansion of its market with the appearance of different lifestyles. In this Work Project a study regarding the website direct sales of Rota Vicentina was developed. Its website shows the idea of being solely an information structure and not a purchase one, leading to a current absence of online sales. Hence, it is suggested the modification of its business model, using different instruments and channels. Some digital marketing recommendations were developed in order to boost website sales, such as a platform for online reviews, remarketing campaigns and social media activity.

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This paper proposes a high-level reinforcement learning (RL) control system for solving the action selection problem of an autonomous robot. Although the dominant approach, when using RL, has been to apply value function based algorithms, the system here detailed is characterized by the use of direct policy search methods. Rather than approximating a value function, these methodologies approximate a policy using an independent function approximator with its own parameters, trying to maximize the future expected reward. The policy based algorithm presented in this paper is used for learning the internal state/action mapping of a behavior. In this preliminary work, we demonstrate its feasibility with simulated experiments using the underwater robot GARBI in a target reaching task

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A series of InxAl1-xAs samples (0.51≪x≪0.55)coherently grown on InP was studied in order to measure the band-gap energy of the lattice matched composition. As the substrate is opaque to the relevant photon energies, a method is developed to calculate the optical absorption coefficient from the photoluminescence excitation spectra. The effect of strain on the band-gap energy has been taken into account. For x=0.532, at 14 K we have obtained Eg0=1549±6 meV