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991.
Christensen M.G. van de Par S. 《IEEE transactions on audio, speech, and language processing》2006,14(4):1340-1351
In this paper, methods for improved parametric coding of transients are presented. We propose a signal model for coding of transients consisting of a sum of sinusoids each being amplitude-modulated by a different gamma envelope. These envelopes are characterized by an onset time, an attack and a decay parameter. An efficient method for estimating these parameters is presented. Further, methods are proposed that combine this transient model with a constant-amplitude sinusoidal model in order to achieve efficient coding of both stationary and transient signal parts. By rate-distortion optimization using a perceptual distortion measure, we combine variable rate bit allocation and segmentation in an optimal way. Formal, as well as informal, listening tests show that significant improvements can be achieved with the proposed model as compared to a state-of-the-art sinusoidal coder by the combination of optimal segmentation and amplitude modulated sinusoidal audio coding. 相似文献
992.
As organizations flesh out their enterprise software security framework (ESSF), they quickly spot an overwhelming gap between their current state of practice and their eventual goals for building secure applications. To address this gap, the application security group must bring ESSF plans to other parts of the organization: corporate, engineering, business, training, and IT groups, to name a few. Such socialization helps organizational participants understand their role in framework adoption and roll out, and it should cover what tools people will need, how they'll interact with each other, and what levels of effort they can expect to put forth 相似文献
993.
994.
Hilderick A. van der Meiden Author Vitae Willem F. Bronsvoort Author Vitae 《Computer aided design》2006,38(4):275-283
Geometric constraints are at the heart of parametric and feature-based CAD systems. Changing values of geometric constraint parameters is one of the most common operations in such systems. However, because allowable parameter values are not known to the user beforehand, this is often a trial-and-error process. We present an approach for automatically determining the allowable range for parameters of geometric constraints. Considered are systems of distance and angle constraints on points in 3D that can be decomposed into triangular and tetrahedral subproblems, by which most practical situations in parametric and feature-based CAD systems can be represented. Our method uses the decomposition to find critical parameter values for which subproblems degenerate. By solving one problem instance for each interval between two subsequent critical values, the exact parameter range is determined for which a solution exists. 相似文献
995.
Either from a control theoretic viewpoint or from an analysis viewpoint it is necessary to convert smooth systems to discrete systems, which can then be implemented on computers for numerical simulations. Discrete models can be obtained either by discretizing a smooth model, or by directly modeling at the discrete level itself. One of the goals of this paper is to model port-Hamiltonian systems at the discrete level. We also show that the dynamics of the discrete models we obtain exactly correspond to the dynamics obtained via a usual discretization procedure. In this sense we offer an alternative to the usual procedure of modeling (at the smooth level) and discretization. 相似文献
996.
Edzer Huitema Gerwin Gelinck Bas van der Putten Eugenio Cantatore Karel Kuijk Kees Hart Dago De Leeuw 《Journal of the Society for Information Display》2002,10(3):195-202
A 2‐in. active‐matrix display was demonstrated, containing 4096 solution‐processed polymer‐based transistors. By using the polymer‐dispersed liquid‐crystal display (LCD) effect, this results in a reflective, low‐power display with paper‐like contrast. The influence of the transistor parameters on the display performance is analyzed by use of a model for charging and discharging of the pixel capacitors. Good agreement was obtained between the model and the experimental data. Scaling behavior allows estimation of the performance required for transistors in a quarter‐VGA display. These requirements are met by solution‐processed pentacene transistors. 相似文献
997.
van Schoor G. van Wyk J.D. Shaw I.S. 《Industry Applications, IEEE Transactions on》2002,38(2):467-475
A hybrid power compensator (HPC) consisting of a static VAr compensator and a dynamic compensator needs to be optimally controlled during the compensation of nonlinear loads. The HPC must be controlled to meet minimum requirements in terms of power factor and harmonic distortion, while at the same time minimizing its total cost. The use of an artificial neural network (ANN) to control the HPC amid a very dynamic environment to achieve the above is investigated. A state-space model of the power distribution network together with the HPC forms the basis of evaluation of the mentioned controller. The model was calibrated against actual in-network measurements. The results obtained reveals that the application of an ANN in controlling an HPC is feasible given that the ANN parameters are chosen appropriately 相似文献
998.
John van den Hoven 《Information Systems Management》2002,19(3):89-92
Today's rapidly changing, global, competitive business environment requires that an enterprise optimize its operations and leverage its data, information, and knowledge resources better than ever before. the result is an ever-increasing demand for data, information, and knowledge about the enterprise, its operations, and about its customers, suppliers, and business partners. the database management system is the key component of the information systems infrastructure of the modern enterprise that is focused on meeting this demand. the database management system is an organized store of the enterprise' data that provides ever-increasing capabilities for adding value to data by turning data into information; by turning this information into knowledge; and by sharing data, information, and knowledge securely throughout the enterprise. 相似文献
999.
M.G.J. van den Brand P. Klint J.J. Vinju 《Electronic Notes in Theoretical Computer Science》2002,70(6):100-117
Term rewriting is an appealing technique for performing program analysis and program transformation. Tree (term) traversal is frequently used but is not supported by standard term rewriting. In this paper, many-sorted first-order term rewriting is extended with automatic tree traversal by adding two primitive tree traversal strategies and complementing them with three types of traversals. These so-called traversal functions can be either top-down or bottom-up. They can be sort preserving, mapping to a single sort, or a combination of these two. Traversal functions have a simple design, their application is type-safe in a first-order many-sorted setting and can be implemented efficiently. We describe the operational semantics of traversal functions and discuss applications. 相似文献
1000.
The unique combination of high-pressure and pulse radiolysis kinetic techniques enables detailed mechanistic insight for a large variety of chemical processes to be gained. Typical examples for transition metal reactions are presented. These include ligand substitution, electron transfer, reactions of complexes with uncommon oxidation states, and reactions with radicals, including the formation and decomposition reactions of complexes with metal-carbon sigma bonds. The volumes of activation and volume profiles obtained form the basis of a critical analysis of different plausible reaction mechanisms. 相似文献