974 resultados para Matrix transfer technique


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Investiga o processo de transição da Escola Normal para outro espaço físico sob a forma de Instituto de Educação e os desdobramentos dessa mudança na formação de professores no Espírito Santo, segundo as diretrizes instituídas pela Lei nº. 5.692/71, durante o Regime Ditatorial Brasileiro (1964-1985). O recorte temporal inicia-se em 1971, quando ocorreu a transição, e encerra-se no ano 2000, momento em que o Instituto passa a denominar-se Escola Estadual de 2º grau Professor Fernando Duarte Rabelo. Privilegia, como interlocutores teóricos, os historiadores Carlo Ginzburg (1986, 2006), Marc Bloch (2001) e Michel de Certeau (2004) e toma, como corpus documental, propostas curriculares do Estado, portarias, matérias de jornais, fotografias de eventos realizados pela instituição e entrevistas com sujeitos que atuaram naquele espaço como professoras, diretora e aluna. As fontes foram interrogadas a partir das seguintes questões: como se deu a transição da Escola Normal D. Pedro II para o Instituto de Educação de Vitória? Que motivos levaram a essa transição? Como se configurou a formação de professores no Instituto de Educação? Quais os desdobramentos das mudanças ocorridas, em se tratando da formação de professores capixabas? Pareceram intrigantes silêncios e lacunas observados em relação à transição da Escola Normal para o Instituto de Educação e aos motivos que desencadearam essa mudança. Das falas das professoras, depreende-se que decisões sobre a transferência do espaço físico e as modificações no currículo vieram prontas, de cima para baixo. O discurso da modernização alardeia a técnica e o tecnicismo e anuncia novidades. A Escola Normal e as suas tradições passam a habitar o passado como algo que se apaga em nome do avanço técnico. Ainda que sutilmente, o cheiro do cafezinho gratuito e do mingau fizessem espargir o aroma da saudade de um outro tempo em que o lanche dos professores da Escola Normal era um encontro “solene”. Conclui-se que a abrupta descontinuidade da Escola Normal, cujo prédio passou a abrigar a atual Escola Estadual Maria Ortiz, possivelmente não se esgota nas questões de ordem técnico-pedagógica que os documentos deixam explícitas. Entretanto, tendo em vista o cronograma limitado desta pesquisa e a lacuna das fontes, não foi possível explorar outras possibilidades de resposta.

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The radial undistortion model proposed by Fitzgibbon and the radial fundamental matrix were early steps to extend classical epipolar geometry to distorted cameras. Later minimal solvers have been proposed to find relative pose and radial distortion, given point correspondences between images. However, a big drawback of all these approaches is that they require the distortion center to be exactly known. In this paper we show how the distortion center can be absorbed into a new radial fundamental matrix. This new formulation is much more practical in reality as it allows also digital zoom, cropped images and camera-lens systems where the distortion center does not exactly coincide with the image center. In particular we start from the setting where only one of the two images contains radial distortion, analyze the structure of the particular radial fundamental matrix and show that the technique also generalizes to other linear multi-view relationships like trifocal tensor and homography. For the new radial fundamental matrix we propose different estimation algorithms from 9,10 and 11 points. We show how to extract the epipoles and prove the practical applicability on several epipolar geometry image pairs with strong distortion that - to the best of our knowledge - no other existing algorithm can handle properly.

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For modern consumer cameras often approximate calibration data is available, making applications such as 3D reconstruction or photo registration easier as compared to the pure uncalibrated setting. In this paper we address the setting with calibrateduncalibrated image pairs: for one image intrinsic parameters are assumed to be known, whereas the second view has unknown distortion and calibration parameters. This situation arises e.g. when one would like to register archive imagery to recently taken photos. A commonly adopted strategy for determining epipolar geometry is based on feature matching and minimal solvers inside a RANSAC framework. However, only very few existing solutions apply to the calibrated-uncalibrated setting. We propose a simple and numerically stable two-step scheme to first estimate radial distortion parameters and subsequently the focal length using novel solvers. We demonstrate the performance on synthetic and real datasets.

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A model to simulate the conductivity of carbon nanotube/polymer nanocomposites is presented. The proposed model is based on hopping between the fillers. A parameter related to the influence of the matrix in the overall composite conductivity is defined. It is demonstrated that increasing the aspect ratio of the fillers will increase the conductivity. Finally, it is demonstrated that the alignment of the filler rods parallel to the measurement direction results in higher conductivity values, in agreement with results from recent experimental work.

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The objective of the present study was the exogenous stimulation of ovarian activity and definition of embryo collection, and transfer protocols, in the domestic cat for potential application in non-domestic endangered species. Sixteen adult queens and two adult male reproducers kept in the experimental cat house at the Morphology sector at the Veterinary Department (DVT), UFV, were used in this study. All the queens received a single application of 150 IU Equine Chorionic Gonadotropin (eCG) in the post estrus to induce ovarian activity and 80 to 84 hours later, received a single application of 100 UI Human Chorionic Gonadotropin (hCG) to induce ovulation. After hCG application, only the donor queens were naturally mated. The receptor queens received extra stimulus for induction of ovulation through manipulation of an intravaginal swab. Five to six days after hCG application, the donor queens were subjected to a laparotomy for embryo collection that was performed by trans-horn uterine washing. On average, six embryos were surgically inovulated. They were classified as type I and III compact morula and blastocysts in four receptor queens. Three animals presented pregnancy confirmed by ultrasound at day 36 and two of these animals gave birth to litters of two and four offsprings, respectively, at 66 and 63 days after induction of ovulation. Except for one still birth, all the offspring developed normally.

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In this work, we consider the numerical solution of a large eigenvalue problem resulting from a finite rank discretization of an integral operator. We are interested in computing a few eigenpairs, with an iterative method, so a matrix representation that allows for fast matrix-vector products is required. Hierarchical matrices are appropriate for this setting, and also provide cheap LU decompositions required in the spectral transformation technique. We illustrate the use of freely available software tools to address the problem, in particular SLEPc for the eigensolvers and HLib for the construction of H-matrices. The numerical tests are performed using an astrophysics application. Results show the benefits of the data-sparse representation compared to standard storage schemes, in terms of computational cost as well as memory requirements.

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A hierarchical matrix is an efficient data-sparse representation of a matrix, especially useful for large dimensional problems. It consists of low-rank subblocks leading to low memory requirements as well as inexpensive computational costs. In this work, we discuss the use of the hierarchical matrix technique in the numerical solution of a large scale eigenvalue problem arising from a finite rank discretization of an integral operator. The operator is of convolution type, it is defined through the first exponential-integral function and, hence, it is weakly singular. We develop analytical expressions for the approximate degenerate kernels and deduce error upper bounds for these approximations. Some computational results illustrating the efficiency and robustness of the approach are presented.

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Background: Several studies link the seamless fit of implant-supported prosthesis with the accuracy of the dental impression technique obtained during acquisition. In addition, factors such as implant angulation and coping shape contribute to implant misfit. Purpose: The aim of this study was to identify the most accurate impression technique and factors affecting the impression accuracy. Material and Methods: A systematic review of peer-reviewed literature was conducted analyzing articles published between 2009 and 2013. The following search terms were used: implant impression, impression accuracy, and implant misfit.A total of 417 articles were identified; 32 were selected for review. Results: All 32 selected studies refer to in vitro studies. Fourteen articles compare open and closed impression technique, 8 advocate the open technique, and 6 report similar results. Other 14 articles evaluate splinted and non-splinted techniques; all advocating the splinted technique. Polyether material usage was reported in nine; six studies tested vinyl polysiloxane and one study used irreversible hydrocolloid. Eight studies evaluated different copings designs. Intraoral optical devices were compared in four studies. Conclusions: The most accurate results were achieved with two configurations: (1) the optical intraoral system with powder and (2) the open technique with splinted squared transfer copings, using polyether as impression material.

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Optimal financiai strategies are criticai for long term survival in competitive international markets. Financial strategies pertaining to transfer pricing have become increasingly important as income tax authorities seek additional revenues through increased monitoring of company practices. In this first of two articles, optimal tax strategies are presented after reviewing the transfer pricing concept and the rationale underlying governments' increased focus on transfer pricing. In the second forthcoming article, we analyze the effect of government restrictions on optimal pricing strategies.

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Transfer pricing is a pervasive issue that presents significant tax savings potential concerning international enterprises. The authors discuss company incentives to manage transfer prices in an article appearing in the preceding issue of this journal. In response to these incentives, governments have increasingly enacted and enforced domestic restrictions on transfer prices. In this article, contemporary norms restricting transfer pricing are analyzed. The OEGO and US pricing standards are assessed and Brazil's recent application of these standards is considered. Transfer pricing methods are described and evidence of their use is presented. We conclude by describing an intercompany transfer pricing policy intended to facilitate internaI financiaI management and minimize externaI tax threats.

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Multi-national enterprises often attempt to replicate successful management practices in "foreign" environments. However, such practices may be ethnocentric because they fit the assumptions, behaviors, expectations, and values of the home cultural environment. Unless the underlying assumptions are shared, transfer to a differing environment may fail. Even if the focus is shifted from cultural differences to implementation, implementation approaches may also be criticized as ethnocentric for the same reasons. In this article, a non-ethnocentric model is expanded and used to test the portability of one management practice, performance appraisal, from the USA to Brazil. This "Test of Portability" may help managers understand which management practices are portable, and, perhaps even more valuable, provide a rationale for adaptation or rejection.

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This paper presents the Direct Power Control of Three-Phase Matrix Converters (DPC-MC) operating as Unified Power Flow Controllers (UPFC). Since matrix converters allow direct AC/AC power conversion without intermediate energy storage link, the resulting UPFC has reduced volume and cost, together with higher reliability. Theoretical principles of DPC-MC method are established based on an UPFC model, together with a new direct power control approach based on sliding mode control techniques. As a result, active and reactive power can be directly controlled by selection of an appropriate switching state of matrix converter. This new direct power control approach associated to matrix converters technology guarantees decoupled active and reactive power control, zero error tracking, fast response times and timely control actions. Simulation results show good performance of the proposed system.

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This paper presents a predictive optimal matrix converter controller for a flywheel energy storage system used as Dynamic Voltage Restorer (DVR). The flywheel energy storage device is based on a steel seamless tube mounted as a vertical axis flywheel to store kinetic energy. The motor/generator is a Permanent Magnet Synchronous Machine driven by the AC-AC Matrix Converter. The matrix control method uses a discrete-time model of the converter system to predict the expected values of the input and output currents for all the 27 possible vectors generated by the matrix converter. An optimal controller minimizes control errors using a weighted cost functional. The flywheel and control process was tested as a DVR to mitigate voltage sags and swells. Simulation results show that the DVR is able to compensate the critical load voltage without delays, voltage undershoots or overshoots, overcoming the input/output coupling of matrix converters.

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The modelling of the experimental data of the extraction of the volatile oil from six aromatic plants (coriander, fennel, savoury, winter savoury, cotton lavender and thyme) was performed using five mathematical models, based on differential mass balances. In all cases the extraction was internal diffusion controlled and the internal mass transfer coefficienty (k(s)) have been found to change with pressure, temperature and particle size. For fennel, savoury and cotton lavender, the external mass transfer and the equilibrium phase also influenced the second extraction period, since k(s) changed with the tested flow rates. In general, the axial dispersion coefficient could be neglected for the conditions studied, since Peclet numbers were high. On the other hand, the solute-matrix interaction had to be considered in order to ensure a satisfactory description of the experimental data.