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1.52 Tbit/s OCDM/WDM (4 OCDM x 19 WDM x 20 Gbit/s) transmission experiment

ELECTRONICS LETTERS 2001年第11期37卷 700-701页

作者： Sotobayashi, H Chujo, W Kitayama, K Independent Adm Inst Commun Res Lab Koganei Tokyo 1848795 Japan Osaka Univ Dept Elect & Informat Syst Suita Osaka 5650871 Japan

1.52Tbit/s OCDM/WDM (4 OCDM x 19 WDM x 20Gbit/s) transmission based on simultaneous multi-wavelength optical encoding of a single supercontinuum sourer is experimentally demonstrated with 0.4 bit/s/Hz spectrum efficie... 详细信息

关键词： 1.52 Tbit/s integrated optics error statistics optical transmitters Multiplexing and switching in optical communication Codes optical phase shifters high-speed optical techniques OCDM/WDM Integrated optics Optical communication equipment encoding optical fibre communication multi-wavelength optical encoding Optical coatings and filters optical code division multiplexing Fibre optics spectrum efficiency single supercontinuum source multiplexing transmission experiment wavelength division multiplexing probability and statistics optical fibre filters

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Statistical analysis of soliton robustness to polarisation-mode dispersion

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ELECTRONICS LETTERS 2000年第18期36卷 1575-1577页

作者： Xie, C Karlsson, M Andrekson, PA Sunnerud, H Chalmers Univ Technol Photon Lab Dept Microelect ED SE-41296 Gothenburg Sweden

The statistical characteristics of soliton robustness to polarisation-mode dispersion (PMD) in fibres are investigated numerically. It is found that the soliton robustness to PMD has a strong dependence on both chroma... 详细信息

关键词： Optical propagation, dispersion and attenuation in fibres optical fibre dispersion polarisation-mode dispersion Optical communication Other fibre optical properties Optical communication devices, equipment and systems optical communication optical fibre polarisation soliton robustness optical soliton energy probability theory, stochastic processes, and statistics chromatic dispersion statistical characteristics optical solitons Fibre optics Optical solitons optical fibre theory probability and statistics statistical analysis

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Improved stochastic gradient adaptive filter with gradient adaptive step size

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ELECTRONICS LETTERS 1998年第13期34卷 1300-1301页

作者： Woo, HC Taegu Univ Sch Comp & Commun Engn Jinryang Kyungsan Kyungp 712714 South Korea

The performance of a stochastic gradient adaptive filter can be significantly improved by introducing a forgetting factor. The complexity of the original algorithm can also be reduced by using only the signs of error ... 详细信息

关键词： original algorithm filtering theory gradient adaptive step size computation adaptive filters gradient adaptive step size input signals Signal processing and detection error signals probability and statistics signal processing Filters and other networks stochastic systems forgetting factor stochastic gradient adaptive filter

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Automated stochastic quality function deployment system for measuring the quality performance of design/build contractors

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AUTOMATION IN CONSTRUCTION 2009年第3期18卷 348-356页

作者： Lee, Dong-Eun Lim, Tae-Kyung Arditi, David IIT Dept Civil & Arch Engrg Chicago IL 60616 USA Kyungpook Natl Univ Sch Arch & Civil Engrg Taegu 702701 South Korea

This paper introduces an automated tool named Stochastic Quality Function Deployment (SQFD) system, which measures the quality performance of a Design/Build (D/B) contractor. SQFD integrates stochastic simulation modeling and analysis techniques into traditional QFD to deal efficiently with the uncertainties in the input data, to support the quality performance measurement that is involved in multi-attribute and multi-participant decision-making, and to predict the variability in the output. D/B construction owners who are in the process of selecting a D/B firm for a project would benefit from SQFD, because the system allows an owner to expeditiously assess the quality performance of potential D/B firms in their bidding list. An example in D/B contractor evaluation is presented to illustrate the functioning of the system. This quantitative method is a significant contribution to the field of quality performance measurement, because (1) SQFD is totally automated, (2) SQFD's reliability is higher than conventional QFD, and (3) SQFD efficiently deals with uncertainties in multi-attribute and multi-participant decision-making, and therefore generates more accurate results. The system helps to improve the D/B project bidding system. (C) 2008 Elsevier B.V. All rights reserved.

关键词： Quality function deployment (QFD) Simulation Design/build (D/B) probability and statistics Quality performance measurement

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Adaptive density estimation using an orthogonal series for global illumination

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COMPUTERS & GRAPHICS-UK 2005年第5期29卷 738-755页

作者： Wong, KW Wang, WP City Univ Hong Kong Sch Creat Media Hong Kong Hong Kong Peoples R China Univ Hong Kong Dept Comp Sci Hong Kong Hong Kong Peoples R China

In Monte-Carlo photon-tracing methods energy-carrying particles are traced in an environment to generate hit points on object surfaces for simulating global illumination. The surface illumination can be reconstructed from particle hit points by solving a density estimation problem using an orthogonal series. The appropriate number of terms of an orthogonal series used for approximating surface illumination depends on the numbers of hit points (i.e. the number of samples) as well as illumination discontinuity (i.e. shadow boundaries) on a surface. Existing photon-tracing methods based on orthogonal series density estimation use a pre-specified or fixed number in of terms of an orthogonal series;this results in undesirable visual artifacts, i.e. either near-constant shading across a surface which conceals the true illumination variation when m is very small or excessive illumination oscillation when m is very large. On the other hand, interactive user specification of the number of terms for different surface patches is inefficient and inaccurate, and thus is not a practical solution. In this paper an algorithm is presented for automatically determining on the fly the optimal number of terms to be used in an orthogonal series in order to reconstruct surface illumination from surface hit points. When the optimal number of terms required is too high due to illumination discontinuity of a surface, a heuristic scheme is used to subdivide the surface along the discontinuity boundary into some smaller patches, called sub-patches, so as to allow a smaller number of terms in the orthogonal series to optimally represent illumination on these sub-patches. Experimental results are presented to show that the new method improves upon other existing orthogonal series-based density estimation methods used for global illumination in both running time and memory requirements. (c) 2005 Elsevier Ltd. All rights reserved.

关键词： photon-tracing Monte Carlo simulation probability and statistics density estimation

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Statistical continuum theory for large plastic deformation of polycrystalline materials

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JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS 2001年第3期49卷 589-607页

作者： Garmestani, H Lin, S Adams, BL Ahzi, S FSU Coll Engn FAMU Dept Mech Engn MARTECH Tallahassee FL 32310 USA Brigham Young Univ Provo UT 84602 USA Univ Strasbourg Strasbourg France

This paper focuses on the application of statistical continuum mechanics to the prediction of mechanical response of polycrystalline materials and microstructure evolution under large plastic deformations. A statistical continuum mechanics formulation is developed by applying a Green's function solution to the equations of stress equilibrium in an infinite domain. The distribution and morphology of grains (crystals) in polycrystalline materials is represented by a set of correlation functions that are described by the corresponding probability functions. The elastic deformation is neglected and a viscoplastic power law is employed for crystallographic slip in single crystals. In this formulation, two- and three-point probability functions are used. A secant modulus-based formulation is used. The statistical analysis is applied to simulate homogeneous deformation processes under uniaxial tension, uniaxial compression and plane strain compression of an FCC polycrystal. The results are compared to the well-known Taylor upper bound model and discussed in comparison to experimental observations. (C) 2001 Elsevier Science Ltd. All rights reserved.

关键词： microstructures polycrystalline probability and statistics

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probability distribution of multi-hop-distance in one-dimensional sensor networks

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COMPUTER NETWORKS 2007年第13期51卷 3727-3749页

作者： Vural, Serdar Ekici, Eylem Ohio State Univ Dept Elect & Comp Engn Columbus OH 43210 USA

In spatially random sensor networks, estimating the Euclidean distance covered by a packet in a given number of hops carries a high importance for various functions such as localization and distance estimations. The inaccuracies in such estimations motivate this study on the distribution of the Euclidean distance covered by a packet in spatially random sensor networks in a given number of hops. Although a closed-form expression of distance distribution cannot be obtained, highly accurate approximations are derived for this distribution in one-dimensional spatially random sensor networks. Using statistical measures and numerical examples, it is also shown that the presented distribution approximation yields very high accuracy even for small number of hops. Furthermore, the distribution of hop distance that covers a given Euclidean distance is also approximated. Published by Elsevier B.V.

关键词： sensor networks localization probability and statistics

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The effects of crack face interaction on nonlinear wave propagation in microcracked media

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JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS 1998年第4期46卷 591-619页

作者： Woolfries, S Univ Cambridge Dept Appl Math & Theoret Phys Cambridge CB3 9EW England

An elastic matrix containing aligned, randomly positioned, penny-shaped cracks is considered. Admission that the cracks open under tension and close under compression introduces a nonlinearity in the form of an inequality into the boundary conditions. The stress in the matrix is found in terms of the dynamic Green's function and a field of internal variables representing crack openness. The boundary conditions on the crack allow an exact variational principle to be written down. Proof is given that subsequent statistical averaging and search for a solution within a particular space of trial functions is equivalent to making a quasi-crystalline approximation on the original equation for the stress. The stress then depends on two-point statistics. A system of integro-differential inequalities on a set of averaged variables is written down. This system models the effective behaviour of the composite. The integral terms contain information about history of loading and effects of crack interaction. In the case of an isotropic matrix with mean wave parallel to the crack normal, the equations decouple and the frictional behaviour of the cracks is irrelevant. Simplifying approximations to the integral terms allow easy numerical solutions to initial-and boundary-value problems on the averaged variables when the statistics have a particular form. This work is intended as an extension to that of Smyshlyaev and Willis (1996) to include the effects of crack interaction through two-point statistics. (C) 1998 Elsevier Science Ltd. All rights reserved.

关键词： crack mechanics variational calculus probability and statistics shock waves dynamics

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Homogenization of geomaterials containing voids by random fields and finite elements

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INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES 2012年第14期49卷 2006-2014页

作者： Griffiths, D. V. Paiboon, Jumpol Huang, Jinsong Fenton, Gordon A. Colorado Sch Mines Dept Civil & Environm Engn Golden CO 80401 USA Univ Newcastle Australian Res Council Ctr Excellence Geotech Sci & Engn Callaghan NSW 2308 Australia Dalhousie Univ Dept Engn Math Halifax NS B3J 2X4 Canada Delft Univ Technol Fac Civil Engn & Geosci NL-2600 GA Delft Netherlands

The paper describes the use of random fields and finite elements to assess the influence of porosity and void size on the effective elastic stiffness of geomaterials. A finite element model is developed involving "tied freedoms" that allows analysis of an ideal block of materials leading to direct evaluation of the effective Young's modulus and Poisson's ratio. The influence of block size and representative volume elements (RVE) are discussed. The use of random fields and Monte-Carlo simulations deliver a mean and standard deviation of the elastic parameters that lead naturally to a probabilistic interpretation. The methodology is extended to a foundation problem involving a footing on an elastic foundation containing voids. The approach enables estimates to be made of the probability of excessive settlement. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： Homogenization Random finite element method (RFEM) Representative volume element (RVE) Effective elastic properties Foundation analysis Elastic settlement probability and statistics

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Elastic properties of a tungsten-silver composite by reconstruction and computation

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JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS 1999年第10期47卷 2029-2055页

作者： Roberts, AP Garboczi, EJ Natl Inst Stand & Technol Bldg Mat Div Gaithersburg MD 20899 USA Univ Oxford Dept Mat Oxford OX1 3PH England Univ Queensland Ctr Microscopy & Microanal Brisbane Qld 4072 Australia

A three-dimensional model of a tungsten-silver composite is statistically constructed from an experimental two-dimensional image. The effective Young's modulus (E) of the model is computed in the temperature range 25-1060 degrees C using a finite element method. The results are in good agreement with experimental data. The reconstructed and overlapping sphere models are examples of bi-continuous (non-particulate) media. The computed moduli of the models are not generally in good agreement with the predictions of the self-consistent method. It has also been possible to evaluate the three-point variational bounds on the Young's moduli of the models using the results of Beran, Molyneux, Milton and Phan-Thien. The measured data were close to the upper bound if the properties of the two phases were similar (1/6 < E-1/E-2 < 6). (C) 1999 Elsevier Science Ltd. All rights reserved.

关键词： microstructures inhomogeneous material finite elements probability and statistics

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