A range of silicon-based optical thin films have been deposited in a matrix distributed electron cyclotron resonance (MDECR) reactor. Process parameters were optimized in order to obtain optical quality thin films at ...
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A range of silicon-based optical thin films have been deposited in a matrix distributed electron cyclotron resonance (MDECR) reactor. Process parameters were optimized in order to obtain optical quality thin films at low substrate temperatures and high deposition rates without post-deposition treatment. Stoichiometric silica films have been deposited at the rates up to 70 nm/min at temperatures lower than 150degreesC. Oxynitride films with a controllable refractive index ranging from 1.46 to 1.86 have been obtained from SiH4/O-2/N-2 mixtures. Real time process control by multichannel ellipsometry has been implemented and successfully applied for the deposition of silica, silicon oxynitrides and amorphous silicon. Better than 0.3% in thickness accuracy was achieved in high rate deposition of silica layers of various predefined thickness. Refractive indices were determined in real-time with an absolute precision of 0.005 - 0.02. The control algorithm was used for fabrication of multilayer optical filters. The results show that the MDECR concept coupled with real-time process control by ellipsometry can be technology of choice for the deposition of interference coatings.
A structured multisignature scheme is an order-sensitive multisignature scheme that allows participating signers to sign messages in compliance with a specified signing order. It has been shown that the Burmester et a...
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A structured multisignature scheme is an order-sensitive multisignature scheme that allows participating signers to sign messages in compliance with a specified signing order. It has been shown that the Burmester et al. order-sensitive multisignature scheme cannot prevent all signers producing a valid multisignature without following the specified signing order. The paper proposes two structured multisignature algorithms, one based on the RSA scheme and the other on an ElGamal-type scheme. Incorporation of both order-free and order-sensitive multisignature algorithms together is shown to construct a generalised multisignature algorithm.
Researchers have reported varied, even disparate, findings about the productivity of paired versus independent programmers. The authors conclude that the role-based coordination protocol associated with agile software...
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Researchers have reported varied, even disparate, findings about the productivity of paired versus independent programmers. The authors conclude that the role-based coordination protocol associated with agile software methodologies overcomes a significant productivity loss that is otherwise associated with concurrent software development pairs.
A new approach for ROM implementation of finite state machines (FSMs) is proposed, based on the selection of a subset of inputs in each state using multiplexers. This technique has been applied to different FSM standa...
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A new approach for ROM implementation of finite state machines (FSMs) is proposed, based on the selection of a subset of inputs in each state using multiplexers. This technique has been applied to different FSM standard benchmarks and very good results have been obtained.
A class of serial concatenated ordinary (non-punctured) convolutional (SCOC) codes is introduced. Simulation results over additive white Guassian noise channels show that the SCOC codes have comparable performance as ...
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A class of serial concatenated ordinary (non-punctured) convolutional (SCOC) codes is introduced. Simulation results over additive white Guassian noise channels show that the SCOC codes have comparable performance as 3GPP turbo codes and LDPC codes, while with overall decoding complexity smaller than that of LDPC codes and 3GPP turbo codes.
This article reviews and introduces an enhanced distributed admission control algorithm for enhanced distributed channel access in the emerging IEEE 802.11e wireless local area networks. The algorithm is evaluated for...
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This article reviews and introduces an enhanced distributed admission control algorithm for enhanced distributed channel access in the emerging IEEE 802.11e wireless local area networks. The algorithm is evaluated for video streams in terms of throughput, delay, transmission limit convergence, and effects of the damping factor.
This special issue of Recherche Operationnelle is devoted to recent researchwhich significantly enhances our ability to model, either mathematically or algo-rithmically,increasingly complex service systems. All the pa...
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This special issue of Recherche Operationnelle is devoted to recent researchwhich significantly enhances our ability to model, either mathematically or algo-rithmically,increasingly complex service systems. All the papers in this issue are methodological in nature,even though the first paper addresses a very practical approach. This collection of papers beginswith a survey by Dr Khaled Hussain and Mr Varol Kaptan of recent advances which allow modelling andsimulation to be conducted in a very realistic visual setting. We all know how frustrating it can beto deal with the need to determine whether the objects we model are represented in a realisticmanner, and whether the simulation conditions are indeed realistic. The approach described in thisfirst paper is based on the premise that the system being simulated has a realistic visualcounterpart, e.g. some natural scenery (as in a military tactical simulation), a room (as whenpeople''s behaviour may be simulated), some roads or an airport (as when a transportation system hasto be simulated), a hospital operating room (as when a surgical procedure needs to be simulated),and so on. In all of these cases, the real world being simulated can be based on an actual videosequence of the real world setting. It can be even more realistic and the simulation can beconducted within a video viewing of the real world itself. This paper shows how this can actually bedone and describes a system that has been designed and developed at the University of CentralFlorida and at Imperial College to achieve this. In such a simulator, the simulated conditions arethe real world itself, while the behaviour of synthetic objects or synthetic changes to real objectsis what is being simulated. The value of such simulations can be tremendous, and can allow testingof complex behaviours in a fully realistic setting with the possibility of the human viewer actuallyobserving different operating conditions. In addition to the visual aspects, the authors a
A modified linearly constrained constant modulus algorithm for blind adaptive multiuser detection in DS/CDMA systems is presented. By selecting a suitable linearly constrained cost function, the performance of the pro...
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A modified linearly constrained constant modulus algorithm for blind adaptive multiuser detection in DS/CDMA systems is presented. By selecting a suitable linearly constrained cost function, the performance of the proposed algorithm is improved in terms of the capability of suppressing multiple access interference. Simulation results indicate that the proposed algorithm provides a faster convergence and steady-state performance.
In this letter, we show a direct relation between spectral embedding methods and kernel principal components analysis and how both are special cases of a more general learning problem: learning the principal eigenfunc...
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In this letter, we show a direct relation between spectral embedding methods and kernel principal components analysis and how both are special cases of a more general learning problem: learning the principal eigenfunctions of an operator defined from a kernel and the unknown data-generating density. Whereas spectral embedding methods provided only coordinates for the training points, the analysis justifies a simple extension to out-of-sample examples (the Nystrom formula) for multidimensional scaling (MDS), spectral clustering, Laplacian eigenmaps, locally linear embedding (LLE), and Isomap. The analysis provides, for all such spectral embedding methods, the definition of a loss function, whose empirical average is minimized by the traditional algorithms. The asymptotic expected value of that loss defines a generalization performance and clarifies what these algorithms are trying to learn. Experiments with LLE, Isomap, spectral clustering, and MDS show that this out-of-sample embedding formula generalizes well, with a level of error comparable to the effect of small perturbations of the training set on the embedding.
Rate models are often used to study the behavior of large networks of spiking neurons. Here we propose a procedure to derive rate models that take into account the fluctuations of the input current and firing-rate ada...
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Rate models are often used to study the behavior of large networks of spiking neurons. Here we propose a procedure to derive rate models that take into account the fluctuations of the input current and firing-rate adaptation, two ubiquitous features in the central nervous system that have been previously overlooked in constructing rate models. The procedure is general and applies to any model of firing unit. As examples, we apply it to the leaky integrate-and-fire (IF) neuron, the leaky IF neuron with reversal potentials, and to the quadratic IF neuron. Two mechanisms of adaptation are considered, one due to an afterhyperpolarization current and the other to an adapting threshold for spike emission. The parameters of these simple models can be tuned to match experimental data obtained from neocortical pyramidal neurons. Finally, we show how the stationary model can be used to predict the time-varying activity of a large population of adapting neurons.
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