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Random field representation of horizontal density distribution in partially oriented strandboard mat

WOOD AND FIBER SCIENCE 2001年第3期33卷 437-449页

作者： Lu, CJ Lam, F SydneyPLUS Int Lib Syst Richmond BC V6V 2J7 Canada Univ British Columbia Fac Forestry Dept Wood Sci Vancouver BC V6T 1Z4 Canada

A random field representation of the horizontal density distribution in partially oriented strandboard mats was investigated. The orientation of strands can be characterized by both the von Mises distribution and the uniform distribution within a range of angles. Theoretical models of the correlation coefficients of any two points simultaneously covered by one strand, characteristic area of the correlation, and the degree of orientation were developed. Results indicate that the concentration factor k = 700 is sufficiently large to represent a perfectly aligned strand arrangement in oriented strandboards based on the von Mises distribution. The correlation coefficients of two points in a mat have a lower bound (random case) and an upper bound (perfectly aligned) in both von Mises and uniform distributions. Based on the concept of characteristic area, where the minimum characteristic area is the area of the strand and the maximum characteristic area is approximate to the square of strand length, the degree of orientation in a panel can be represented as a function of characteristic area. This value is found to be very close to the percent alignment definition.

关键词： random field mathematical model horizontal density distribution auto-correlation function partially oriented strandboard von Mises distribution uniform distribution characteristic area degree of orientation

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Stability monitoring for BWR based on singular value decomposition method using artificial neural network

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JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY 2005年第12期42卷 1054-1066页

作者： Tsuji, M Michishita, H Shimazu, Y Hokkaido Univ Grad Sch Engn Dept Nucl Engn Kita Ku Sapporo Hokkaido 0608628 Japan Fujitsu Ltd Makuhari Syst Lab Mihama Ku Chiba 2618588 Japan

A new method for evaluating the decay ratios in a boiling water reactor (BWR) using the singular value decomposition (SVD) method had been proposed. In this method, a signal component closely related to the BWR stability can be extracted from independent components of the neutron noise signal decomposed by the SVD method. However, real-time stability monitoring by the SVD method requires an efficient procedure for screening such compoments. For efficient screening, an artificial neural network (ANN) with three layers was adopted. The trained ANN was actually applied to decomposed components of local power range monitor (LPRM) signals that were measured in stability experiments conducted in the Ringhals-1 BWR. In each LPRM signal, multiple candidates were screened from the decomposed components. However, decay ratios could be estimated by introducing appropriate criterions for selecting the most suitable component among the candidates. The estimated decay ratios are almost identical to those evaluated by visual screening in a previous study. The selected components commonly have the largest singular value, the largest decay ratio and the least squared fitting error among the candidates. By virtue of excellent screening performance of the trained ANN, the real-time stability monitoring by the SVD method can be applied in practice.

关键词： decay ratio BWR type reactors stability monitoring singular value decomposition auto-correlation function artificial neural network back-propagation method local power range monotor Ringhals-1

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Direct comparison of Fe-Cr unmixing characterization by atom probe tomography and small angle scattering

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MATERIALS CHARACTERIZATION 2016年 121卷 61-67页

作者： Couturier, Laurent De Geuser, Frederic Deschamps, Alexis Univ Grenoble Alpes SIMAP F-38000 Grenoble France CNRS SIMAP F-38000 Grenoble France Univ British Columbia Dept Mat Engn Vancouver BC V6T 1Z4 Canada

The fine microstructure obtained by unmixing of a solid solution either by classical precipitation or spinodal decomposition is often characterized either by small angle scattering or atom probe tomography. This article shows that a common data analysis framework can be used to analyze data obtained from these two techniques. An example of the application of this common analysis is given for characterization of the unmixing of the Fe-Cr matrix of a 15-5 PH stainless steel during long-term ageing at 350 degrees C and 400 degrees C. A direct comparison of the Cr composition fluctuations amplitudes and characteristic lengths obtained with both techniques is made showing a quantitative agreement for the fluctuation amplitudes. The origin of the discrepancy remaining for the characteristic lengths is discussed. (C) 2016 Elsevier Inc. All rights reserved.

关键词： Atom probe tomography Small angle scattering auto-correlation function Spinodal decomposition Stainless steel Ageing

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Investigating water and framework dynamics in pillared MOFs

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MOLECULAR SIMULATION 2015年第16-17期41卷 1379-1387页

作者： Burtch, Nicholas C. Dubbeldam, David Walton, Krista S. Georgia Inst Technol Sch Chem & Biomol Engn 311 Ferst Dr NW Atlanta GA 30332 USA Univ Amsterdam Vant Hoff Inst Mol Sci Sci Pk 904 NL-1098 XH Amsterdam Netherlands

In this work we highlight the use of molecular simulation to study the behaviour of water inside isostructural Zn-DMOF structures. Among the Zn-DMOF structures, the parent DMOF, and the DMOF-DM and DMOF-TF variants are known to be less stable than the DMOF-A and DMOF-TM structures in the presence of water. We apply tools such as radial distribution functions, rotational auto-correlation functions and the visualisation of adsorbate density distributions to investigate the differences in water behaviour within these structures. We also study properties that are inherent to the frameworks themselves such as thermal expansion and ligand flexibility. Our results indicate that water is only able to get 0.5 angstrom closer to the metal hydrolysis site in the water unstable structures than in the more water stable structures. The results can be somewhat sensitive to the details of the modelling of the electrostatic potential energy surface and, for dynamical properties, modelling of framework flexibility.

关键词： radial distribution function auto-correlation function adsorbate density distribution water stability metal organic frameworks

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Generalized Discrete Fourier Transform With Nonlinear Phase

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2010年第9期58卷 4547-4556页

作者： Akansu, Ali N. Agirman-Tosun, Handan New Jersey Inst Technol Dept Elect & Comp Engn Newark NJ 07102 USA

Constant modulus transforms like discrete Fourier transform (DFT), Walsh transform, and Gold codes have been successfully used over several decades in several engineering applications, including discrete multi-tone (DMT), orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA) communications systems. In this paper, we present a generalized framework for DFT called Generalized DFT (GDFT) with nonlinear phase by exploiting the phase space. We show that GDFT offers sizable correlation improvements over DFT, Walsh, Oppermann and Gold codes, leading to better performance in all multi-carrier communications scenarios investigated. We also highlight how known constant modulus orthogonal transforms are special solutions of the proposed GDFT framework. Moreover, we introduce practical design methods offering computationally efficient implementations of GDFT as enhancements to DFT. We conclude the paper with examples of communications applications where GDFT is shown to outperform DFT and other known constant modulus bases.

关键词： auto-correlation function CDMA cross-correlation function discrete Fourier transform DMT generalized discrete Fourier transform Gold codes OFDM Walsh codes

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A novel iris and chaos-based random number generator

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COMPUTERS & SECURITY 2013年 36卷 40-48页

作者： Zhu, Hegui Zhao, Cheng Zhang, Xiangde Yang, Lianping Jilin Univ Inst Math Changchun 130012 Peoples R China Northeastern Univ Coll Sci Shenyang 110819 Liaoning Peoples R China Indiana State Univ Dept Math & Comp Sci Terre Haute IN 47809 USA

A novel kind of iris and chaotic-based random number generator (ICRNG) is developed from the unique randomness and unpredictability of iris. This method combines biometric feature extraction and random number generation in a novel way. Firstly, we get the non-deterministic source-iris image by iris acquisition equipment, then, we use chaotic function to eliminate the similar pattern in iris from the same person and get the unpredictable random sequence. We use auto-correlation function method and correlation coefficients method to show that ICRNG is linearly independent, then, we use BDS statistical test method to verify ICRNG is nonlinearly independent. Finally, the randomness of ICRNG is verified by histogram analysis, information analysis, sensitivity analySis, FIPS 140-2 tests and NIST SP 800-22 tests. Hence, ICRNG possess satisfactory performance and can be implemented on common PC platform. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Iris Chaotic function auto-correlation function correlation coefficients BDS test FIPS 140-2 tests NIST SP 800-22 tests

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Changing the statistical properties of noisy laser radiation in a saturable absorber

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OPTICS COMMUNICATIONS 1999年第1-6期169卷 97-102页

作者： Kozich, VP Vodtchits, AI Ivanov, DA Orlovich, VA Natl Acad Sci Belarus BI Stepanov Inst Phys Minsk 220072 BELARUS

Changing the statistical properties of the noisy radiation of a multi-mode nanosecond YAG:Nd3+ laser by passing it through a saturable absorber (a methanol solution of polymethine dye 3274-u) is experimentally studied. A considerable increase in the contrast ratio of the second-order intensity auto-correlation function of the radiation is observed, indicating that the statistics of the noisy laser light become super-Gaussian after passing through the absorber. (C) 1999 Published by Elsevier Science B.V. All rights reserved.

关键词： laser radiation statistics auto-correlation function saturable absorber

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Construction of Binary Array Set with Zero correlation Zone Based on Interleaving Technique

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2011年第2期E94A卷 766-772页

作者： Tu, Yifeng Fan, Pingzhi Hao, Li Li, Xiyang SW Jiaotong Univ Keylab Informat Coding & Transmiss Inst Mobile Commun Chengdu 610031 Sichuan Peoples R China

Sequences with good correlation properties are of substantial interest in many applications. By interleaving a perfect array with shift sequences, a new method of constructing binary array set with zero correlation zone (ZCZ) is presented. The interleaving operation can be performed not only row-by-row but also column-by-column on the perfect array. The resultant ZCZ binary array set is optimal or almost optimal with respect to the theoretical bound. The new method provides a flexible choice for the rectangular ZCZ and the set size.

关键词： auto-correlation function cross-correlation fucntion perfect array zero correlation zone

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A selective bitplane image encryption scheme using chaotic maps

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MULTIMEDIA TOOLS AND APPLICATIONS 2019年第8期78卷 10373-10400页

作者： Som, Sukalyan Mitra, Abhijit Palit, Sarbani Chaudhuri, B. B. Barrackpore Rastraguru Surendranath Coll Dept Comp Sci Kolkata W Bengal India Gargi Mem Inst Technol Kolkata 144 India Indian Stat Inst Comp Vis & Pattern Recognit Unit Kolkata W Bengal India

Partial encryption is one of the viable solutions for low power, high speed, real time secure multimedia communication. In this paper, a chaotic tent map based selective bitplane encryption technique is proposed for both gray scale and color images. After decomposing the original image into eight bitplanes, each bitplane is classified into either significant or non-significant category by defining a flexible threshold value of 0.3, deduced experimentally. Following this segregation, only the significant bitplanes are encrypted with the key stream sequences generated by a chaos-based pseudo-random binary number generator. The cipher image is then transmitted through public channel. The proposed scheme has three important contributions v.i.z. a) determination of significant bitplanes, b) encryption of only the significant bitplanes leading to reduction in computational complexity and c) elimination of the need for separate channel for transmitting the information about the significant bitplanes. It is shown that the proposed partial encryption scheme saves around 35% computation on the image database used here. Different types of attacks against this scheme are also analysed to show the robustness of this approach.

关键词： Partial image encryption auto-correlation function Bitplane Tent map Uniformity test correlation coefficient Key sensitivity Differential attack Cropping attack Replacement attack

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The input vector space optimization for LSTM deep learning model in real-time prediction of ship motions

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OCEAN ENGINEERING 2020年 213卷 107681-107681页

作者： Liu, Yucheng Duan, Wenyang Huang, Limin Duan, Shiliang Ma, Xuewen Harbin Engn Univ Coll Shipbldg Engn Harbin 150001 Peoples R China

Vessel motions due to the ocean waves contribute to maritime operational safety and efficiency. Real-time prediction of deterministic ship motions in the coming future seconds is essential in decision-making when performing motions sensitive activities. The Long-Short Term Memory (LSTM) deep learning model provides a potential way for nonlinear ship motions prediction due to its capability in nonlinearity processing. Determination of a reasonable dimension of the input vector is critical in training the LSTM model. Conventionally, the optimal dimension for the input vector is selected by traversing an empirical preset range. Hence, it suffers both high computational cost and poor adaptation in determining the optimal input vector dimension. In the present work, an input vector space optimization method is proposed based on the dependence hidden in ship motion records of a sequence. Taking different correlation expressions into consideration, both the Impulse Response function (IRF) based and auto-correlation function (ACF) based techniques are investigated for input vector space optimization. Numerical simulations are carried out for vilification and comparison purpose. The ACF technique is better in representing the auto-correlation hidden in the stochastic ship motions. And the ACF-based LSTM model performs better in both training efficiency and prediction accuracy.

关键词： Ship motions real-time prediction LSTM deep learning model Input vector space optimization Impulse response function auto-correlation function

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