共查询到20条相似文献,搜索用时 15 毫秒
1.
Most of the existing modelling techniques for the speaker recognition task make an implicit assumption of sufficient data
for speaker modelling and hence may lead to poor modelling under limited data condition. The present work gives an experimental
evaluation of the modelling techniques like Crisp Vector Quantization (CVQ), Fuzzy Vector Quantization (FVQ), Self-Organizing
Map (SOM), Learning Vector Quantization (LVQ), and Gaussian Mixture Model (GMM) classifiers. An experimental evaluation of
the most widely used Gaussian Mixture Model-Universal Background Model (GMM-UBM) is also made. The experimental knowledge
is then used to select a subset of classifiers for obtaining the combined classifiers. It is proposed that the combined LVQ
and GMM-UBM classifier provides relatively better performance compared to all the individual as well as combined classifiers. 相似文献
2.
Isoconversion method for kinetic analysis of solid-state reactions from dynamic thermoanalytical data 总被引:3,自引:0,他引:3
The activation energy for a heterogeneous reaction involving a solid may be obtained from a plot of
0 ln(d/dt) d against
0(1/T) d, where represents the fractional conversion of the solid reactant, and T(t) is the (time-dependent) reactant temperature. This new approach to the analysis of dynamic thermoanalytical kinetic data has distinct advantages over existing methods, as it needs to make no assumption about the kinetic model, involves no approximation to the temperature integral, and is easy to implement on the computer. 相似文献
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Sabin Sulzer 《Materials Science & Technology》2013,29(18):2174-2201
Modelling of tertiary creep in single-crystal superalloys – operative over the majority of the temperature/stress regime of relevance – is assessed. Traditional, empirical approaches are useful for the prediction of component life; a modern trend is for more physically faithful models which account for microstructure and alloy composition. Calculations are made using different methods, to identify advantages/disadvantages, in an effort to approach best practice. The predictions are tested against experimental data. The creep resistance can be estimated to within approximately one-half of a Larson–Miller parameter, from an input of alloy composition, deformation conditions, and estimates of microstructural parameters, rate laws (and parameters therein), and physical constants. Different merit indices are considered to identify the most appropriate for compositional optimisation. 相似文献
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Peter J. Gawthrop Michael Pan Edmund J. Crampin 《Journal of the Royal Society Interface》2021,18(181)
Renewed interest in dynamic simulation models of biomolecular systems has arisen from advances in genome-wide measurement and applications of such models in biotechnology and synthetic biology. In particular, genome-scale models of cellular metabolism beyond the steady state are required in order to represent transient and dynamic regulatory properties of the system. Development of such whole-cell models requires new modelling approaches. Here, we propose the energy-based bond graph methodology, which integrates stoichiometric models with thermodynamic principles and kinetic modelling. We demonstrate how the bond graph approach intrinsically enforces thermodynamic constraints, provides a modular approach to modelling, and gives a basis for estimation of model parameters leading to dynamic models of biomolecular systems. The approach is illustrated using a well-established stoichiometric model of Escherichia coli and published experimental data. 相似文献
6.
《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2004,516(2-3):243-248
By applying the general dynamic aperture formulae for the multipoles in a storage ring developed by Gao (Nucl. Instr. and Meth. A 451 (2000) 545), in this paper, we give the analytical formulae for the dynamic apertures limited by the wigglers in storage rings and their validities have been confirmed by comparing with numerical simulation results. 相似文献
7.
Because of their complexity manufacturing systems are difficult to model. However, modelling is very often required in order to study the behaviour of the system. In this paper an approach is described, where an analogy is drawn between the behaviour of a manufacturing and a mechanical system. Manufacturing systems have to respond to a dynamic demand, namely, a demand that changes over time. Flexibility of a manufacturing system can be thought of as the ability and the rapidness with which the system responds to the dynamic demand. This resembles the behaviour of a mechanical system under the excitation of a force that changes over time. The paper attempts to establish a modelling method based on this analogy and uses this method in the study of a real industrial system. 相似文献
8.
This paper is concerned with scheduling in flexible manufacturing systems (FMSs) using a fuzzy logic (FL) approach. Four fuzzy input variables: machine allocated processing time, machine priority, due date priority and setup time priority are defined. The job priority is the output fuzzy variable, showing the priority status of a job to be selected for next operation on a machine. The model will first select the machines and then assign operations based on a multi-criteria scheduling scheme. The performance of the approach is compared against established methods reported in the literature. The performance measures considered average machine utilisation, meeting due dates, setup times, work in process and mean flow times. The test results demonstrate the superiority of the fuzzy logic approach in most performance measures. 相似文献
9.
Summary. The aim of this contribution is to propose and apply a new approach to the formulation of mathematical models for the analysis of dynamic behavior of dense periodic lattice structures (space or plane trusses) of an arbitrary form. The modelling approach is carried out on two levels. First, we formulate a discrete model, represented by the system of finite difference equations with respect to the spatial coordinates. The obtained equations describe both low- and high-frequency wave propagation problems. Second, two continuum models are derived directly from the finite difference equations and represented respectively by the second- and the fourth-order PDEs with constant coefficients. These models have a physical sense provided that the considerations are restricted to the long wave propagation phenomena. The proposed approach is applied to the vibration analysis for a certain plane lattice structure. Special attention is given to the determination of the range of applicability of the continuum models. 相似文献
10.
Quentin L. Burrell 《Scientometrics》2005,64(3):247-270
Summary Although its use in informetrics dates back at least to 1987, data analysed in a recent paper by Shan et al. (2004) has rekindled interest in the generalized Waring distribution (GWD). The purpose of this note is to show that for many purposes, the distribution is best motivated via a familiar informetric scenario of a population of “sources” producing “items” over time leading to a stochastic process from which the univariate, bivariate and multivariate forms of the GWD are natural consequences. Earlier work and possible future applications are highlighted. Many of the results are due to Irwin and Xekalaki while much of the material on the Waring process has been previously available in an unpublished research report by the author (Burrell, 1991). 相似文献
11.
The paper discusses the application of three well known diffusion models and their modified versions to the growth of publication
data in four selected fields of S&T. It is observed that all the three models in their modified versions generally improve
their performance in terms of parameter values, fit statistics, and graphical fit to the data. The most appropriate model
is generally seen to be the modified exponential-logistic model. 相似文献
12.
Figaro S Avril JP Brouers F Ouensanga A Gaspard S 《Journal of hazardous materials》2009,161(2-3):649-656
Adsorption kinetic of molasses wastewaters after anaerobic digestion (MSWD) and melanoidin respectively on activated carbon was studied at different pH. The kinetic parameters could be determined using classical kinetic equations and a recently published fractal kinetic equation. A linear form of this equation can also be used to fit adsorption data. Even with lower correlation coefficients the fractal kinetic equation gives lower normalized standard deviation values than the pseudo-second order model generally used to fit adsorption kinetic data, indicating that the fractal kinetic model is much more accurate for describing the kinetic adsorption data than the pseudo-second order kinetic model. 相似文献
13.
Under dynamic adiabatic conditions, the plastic work is known to dissipate into heat and induce thermal softening. From both theoretical and numerical viewpoints, the proportion of effectively dissipated plastic work is commonly evaluated using the so-called Taylor–Quinney coefficient usually assumed to be a constant empirical value. On the other hand, experimental investigations have shown its dependence on strain, strain rate and temperature. 相似文献
14.
Alexandre Dolgui Semyon Potryasaev Boris Sokolov Marina Ivanova Frank Werner 《国际生产研究杂志》2020,58(7):2184-2199
Recently, the applications of Blockchain technology have begun to revolutionise different aspects of supply chain (SC) management. Among others, Blockchain is a platform to execute the smart contracts in the SC as transactions. We develop and test a new model for smart contract design in the SC with multiple logistics service providers and show that this problem can be presented as a multi-processor flexible flow shop scheduling. A distinctive feature of our approach is that the execution of physical operations is modelled inside the start and completion of cyber information services. We name this modelling concept ‘virtual operation’. The constructed model and the developed experimental environment constitute an event-driven dynamic approach to task and service composition when designing the smart contract. Our approach is also of value when considering the contract execution stage. The use of state control variables in our model allows for operations status updates in the Blockchain that in turn, feeds automated information feedbacks, disruption detection and control of contract execution. The latter launches the re-scheduling procedure, comprehensively combining planning and adaptation decisions within a unified methodological framework of dynamic control theory. The modelling complex developed can be used to design and control smart contracts in the SC. 相似文献
15.
Aleixandre-Benavent Rafael Sapena Antonia Ferrer Ferrer Silvia Coronado Peset Fernanda García Alicia García 《Scientometrics》2019,118(2):439-451
Scientometrics - Sharing research data is an increasingly necessary requirement for the advancement of science. The goal of this paper is twofold. First, to analyze the policies on openness in... 相似文献
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Desmet G Clicq D Nguyen DT Guillarme D Rudaz S Veuthey JL Vervoort N Torok G Cabooter D Gzil P 《Analytical chemistry》2006,78(7):2150-2162
It is demonstrated that the kinetic plot representation of experimental plate height data can also account for practical constraints on the column length, the peak width, the viscous heating, and the mobile-phase velocity without needing any iterative solution routine. This implies that the best possible kinetic performance to be expected from a given tested support under any possible set of practical optimization constraints can always be found using a directly responding calculation spreadsheet template. To show how the resulting constrained kinetic plots can be used as a powerful design and selection tool, the method has been applied to a series of plate height measurements performed on a number of different commercial columns for the same component (butyl-parabene) and mobile-phase composition. The method, for example, allows one to account for the fact that the advantageous solutions displayed by the silica monolith and 5 microm particle columns in the large plate number range of the free kinetic plot are no longer accessible if applying a maximal column length constraint of Lmax = 30 cm. In the plate number range that remains accessible, the investigated sub-2 mum particle columns in any case perform (at least for the presently considered parabene separation) better than the 3.5 mum particle columns or silica monolith, especially if considering the use of system pressures exceeding 400 bar. The constrained kinetic plot method can also be used to select the best-suited column length from an available product gamma to perform a separation with a preset number of plates. One of the optimization results that is obtained in this case is that sometimes a significant gain in analysis time can be obtained by selecting a longer column, yielding the desired plate number at a larger velocity than that for a shorter column. 相似文献
19.
The Office for Analysis and Evaluation of Operational Data (AEOD) was established after the accident at Three Mile Island to improve the ways the US Nuclear Regulatory Commission (NRC) and the nuclear community use operating experience in identifying and resolving potential safety problems. One of the major missions of AEOD is to collect, screen, analyze and feed back operating experience to appropriate NRC offices, the nuclear community and the public. An important task within this mission is to assess the safety significance of numerous operating events and, for those determined to be significant, develop recommendations to eliminate the root causes of the event in order to prevent its recurrence. AEOD has developed and implemented a systematic framework for assessing the safety significance of operating events. 相似文献
20.
Extrinsic cohesive modelling of dynamic fracture and microbranching instability in brittle materials
Zhengyu Zhang Glaucio H. Paulino Waldemar Celes 《International journal for numerical methods in engineering》2007,72(8):893-923
Dynamic crack microbranching processes in brittle materials are investigated by means of a computational fracture mechanics approach using the finite element method with special interface elements and a topological data structure representation. Experiments indicate presence of a limiting crack speed for dynamic crack in brittle materials as well as increasing fracture resistance with crack speed. These phenomena are numerically investigated by means of a cohesive zone model (CZM) to characterize the fracture process. A critical evaluation of intrinsic versus extrinsic CZMs is briefly presented, which highlights the necessity of adopting an extrinsic approach in the current analysis. A novel topology‐based data structure is employed to enable fast and robust manipulation of evolving mesh information when extrinsic cohesive elements are inserted adaptively. Compared to intrinsic CZMs, which include an initial hardening segment in the traction–separation curve, extrinsic CZMs involve additional issues both in implementing the procedure and in interpreting simulation results. These include time discontinuity in stress history, fracture pattern dependence on time step control, and numerical energy balance. These issues are investigated in detail through a ‘quasi‐steady‐state’ crack propagation problem in polymethylmethacrylate. The simulation results compare reasonably well with experimental observations both globally and locally, and demonstrate certain advantageous features of the extrinsic CZM with respect to the intrinsic CZM. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献