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Free vibration of pre-tensioned nanobeams based on nonlocal stress theory

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第1期11卷 34-42页

作者： c. w. LIM cheng LI Ji-lin YU Department of Building and construction City University of Hong Kong Kowloon Hong Kong SAR China Department of Modern Mechanics University of Science and Technology of China Hefei 230026 China

The transverse free vibration of nanobeams subjected to an initial axial tension based on nonlocal stress theory is presented. It considers the effects of nonlocal stress field on the natural frequencies and vibration modes. The effects of a small scale parameter at molecular level unavailable in classical macro-beams are investigated for three different types of boundary conditions:simple supports,clamped supports and elastically-constrained supports. Analytical solutions for transverse deforma-tion and vibration modes are derived. Through numerical examples,effects of the dimensionless nanoscale parameter and pre-tension on natural frequencies are presented and discussed.

关键词： Nanobeam Natural frequency Nonlocal stress Pre-tensioned Vibration mode

3D thermoelasticity solutions for functionally graded thick plates

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第3期10卷 327-336页

作者： Ji YING chao-feng LU c. w. LIM Department of Mechanical Engineering Zhejiang University Hangzhou 310027 China Department of civil Engineering Zhejiang University Hangzhou 310058 China Department of Building and construction City University of Hong Kong Hong Kong China

Thermal-mechanical behavior of functionally graded thick plates, with one pair of opposite edges simply supported, is investigated based on 3D thermoelasticity. As for the arbitrary boundary conditions, a semi-analytical solution is presented via a hybrid approach combining the state space method and the technique of differential quadrature. The temperature field in the plate is determined according to the steady-state 3D thermal conduction. The Mori-Tanaka method with a power-law volume fraction profile is used to predict the effective material properties including the bulk and shear moduli, while the effective coefficient of thermal expansion and the thermal conductivity are estimated using other micromechanics-based models. To facilitate the im-plementation of state space analysis through the thickness direction, the approximate laminate model is employed to reduce the inhomogeneous plate into a homogeneous laminate that delivers a state equation with constant coefficients. The present solutions are validated by comparisons with the exact ones for both thin and thick plates. Effects of gradient indices, volume fraction of ceramics, and boundary conditions on the thermomechanical behavior of functionally graded plates are discussed.

关键词： Functionally graded plates Semi-analytical solutions 3D thermoelasticity Mori-Tanaka method

Rapid Identification of Rice Samples Using an Electronic Nose

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Journal of Bionic Engineering 2009年第3期6卷 290-297页

作者： John westbrook w.c.Hoffmann R.E.Lacey USDA-ARS College Station Department of Biological and Agricultural Engineering Texas A&M UniversityCollege Station

Four rice samples of long grain type were tested using an electronic nose (cyranose-320).Samples of 5 g of each variety of rice were placed individually in vials and were analyzed with the electronic nose unit consisting of 32 polymer *** cyranose-320 was able to differentiate between varieties of *** chemical composition of the rice odors for differentiating rice samples needs to be *** optimum parameter settings should be considered during the cyranose-320 training process especially for multiple samples,which are helpful for obtaining an accurate training model to improve identification ***,it is necessary to investigate the E-nose sensor selection for obtaining better classification accuracy.A re- duced number of sensors could potentially shorten the data processing time,and could be used to establish an application pro- cedure and reduce the cost for a specific electronic *** research is needed for developing analytical procedures that adapt the cyranose-320 as a tool for testing rice quality.

关键词： rice grain identification electronic nose data analysis pattern recognition

Minimal observability of Boolean networks

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Science china(Information Sciences) 2022年第5期65卷 157-168页

作者： Yang LIU Jie ZHONG Daniel w.c.HO weihua GUI college of Mathematics and computer Science Zhejiang Normal University Department of Mathematics City University of Hong Kong School of Information Science and Engineering Central South University

In this study, the minimum observability of Boolean networks(BNs) is investigated by using the semi-tensor product(STP) of matrices. First, a new system based on the considered BN is obtained to analyze states pair dynamic trajectories, from which a necessary and sufficient condition for the observability of BNs is determined. Second, adding a new observer improves the observability without affecting the observable states. Thus, an algorithm is presented to design an observer for an unobservable BN. In addition, a necessary condition is obtained to determine the minimum number of nodes required to be directly measurable. Further,an algorithm to address the minimal observability is presented. Finally, examples are provided to demonstrate the effectiveness of the obtained results.

关键词： Boolean networks minimal observability semi-tensor product

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Decision support model for effects estimation and proportionality assessment for targeting in cyber operations

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Defence Technology（防务技术） 2021年第2期17卷 352-374页

作者： c.Maathuis w.Pieters J.van den Berg Delft University of Technology Jaffalaan 52628 BXDelftNetherlands TNO Military Operations Oude Waaldorperweg 632597 AKDen HaagNetherlands Netherlands Defense Academy De la Reyweg 1204818 BBBredaNetherlands Open University of the Netherlands Valkenburgerweg 1776419 ATHeerlenNetherlands

cyber operations are relatively a new phenomenon of the last two *** that period,they have increased in number,complexity,and agility,while their design and development have been processes well kept under *** a consequence,limited data(sets)regarding these incidents are *** various academic and practitioner public communities addressed some of the key points and dilemmas that surround cyber operations(such as attack,target identification and selection,and collateral damage),still methodologies and models are needed in order to plan,execute,and assess them in a responsibly and legally compliant *** on these facts,it is the aim of this article to propose a model that i))estimates and classifies the effects of cyber operations,and ii)assesses proportionality in order to support targeting decisions in cyber *** order to do that,a multi-layered fuzzy model was designed and implemented by analysing real and virtual realistic cyber operations combined with interviews and focus groups with technical e military *** proposed model was evaluated on two cyber operations use cases in a focus group with four technical e military *** the design and the results of the evaluation are revealed in this article.

关键词： cyber operations cyber warfare cyber weapons Artificial intelligence Fuzzy logic Targeting

Solid state crack repair by friction stir processing in 304L stainless steel

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Journal of Materials Science & Technology 2018年第1期34卷 140-147页

作者： c.Gunter M.P.Miles F.c.Liu T.w Nelson Manufacturing Engineering Technology Brigham Young University Department of Mechanical Engineering Brigham Young University

Friction stir processing （FSP） was investigated as a method of repairing cracks in 12 mm thick 304L stainless steel plate. Healing feasibility was demonstrated by processing a tapered crack using a PcBN/w- Re tool with a 25 mm diameter shoulder and a pin length of 6.4 mm. The experiment showed that it was possible to heal a crack that begins narrow and then progressively grows up to a width of 2 mm. Bead on plate experiments were used to find the best parameters for creating a consolidated stir zone with the least amount of hardness difference compared to the base metal. Grain refinement in some specimens resulted in much higher stir zone hardness, compared to base metal, A plot of grain size versus microhardness showed a very strong inverse correlation between grain size and hardness, as expected from the Hall- Perch relationship. corrosion testing was carried out in order to evaluate the effect of FSP on potential sensitization of the stir zone. After 1000 h of intermittent immersion in 3.5% saline solution at room temperature it was found that no corrosion products formed on the base material controls or on any of the friction stir processed specimens.

关键词： Stainless steel crack healing Friction stir processing corrosion resistance

Stable Quantum Filters with Scattering Phenomena

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International Journal of Automation and computing 2008年第2期5卷 132-137页

作者： w.U.Ahamed c.Kambhampati Department of computer Science University of Hull

Quantum neural network filters for signal processing have received a lot of interest in the recent past. The implementations of these filters had a number of design parameters that led to numerical inefficiencies. At the same time the solution procedures employed were explicit in that the evolution of the time-varying functions had to be controlled. This often led to numerical instabilities. This paper outlines a procedure for improving the stability, numerical efficiency, and the accuracy of quantum neural network filters. Two examples are used to illustrate the principles employed.

关键词： Filter estimation quantum neural network probability density function nonlinear wave equation

Diagonalizations of Vector and Tensor Addition Theorems

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communications in computational Physics 2008年第9期4卷 797-819页

作者： B.He w.c.chew Department of Electrical and computer Engineering University of IllinoisUrbanaChampaignUrbanaIL 61801-2918USA. Faculty of Engineering The University of Hong KongHong Kong

Based on the generalizations of the Funk-Hecke formula and the Rayleigh plan-wave expansion formula,an alternative and succinct derivation of the addition theorem for general tensor field is *** new derivation facilitates the diagonalization of the tensor addition *** order to complete this derivation,we have carried out the evaluation of the generalization of the Gaunt coefficient for tensor *** vector fields(special case of tensor fields)are very useful in practice,we discuss vector multipole fields and vector addition theorem in *** work is important in multiple scattering and fast algorithms in wave physics.

关键词： Addition theorem vector field tensor field fast algorithm.

Extraction of catechins and caffeine from different tealeaves and comparison with micellar electrokinetic chromatography

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chinese Science Bulletin 2003年第22期48卷 2438-2443页

作者： SONGGuanqun LINJinming QuFeng c.w.Huie ResearchcenterforEco-EnvironmentalSciences ChineseAcademyofSciencesBeijing100085China Departmentofchemistry HongKongBaptistUniversityKowloonTongHongKongChina

This work describes the simultaneous deter- mination of catechins and caffeine in green, black tealeaves and canned tea-drink using micellar electrokinetic chromatography. The catechins analyzed include (+)-catechin, (-)- epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate and (-)-epigallocatechin gallate. Using UV absorption method at 280 nm, the limits of detections of catechins and caffeine are 10-6 mol/L, which is suitable for the real sample determination. Using this analytical method, the extraction of these compounds from the tealeaves with hot water is compared under different temperatures. The effects of temperature on the amount of catechins and caffeine extracted are evident, showing that (-)-epigallocatechin gallate is the most easiest to be extracted at 100℃. The stability of catechins and caffeine in stocking solution of tea-drink at 4℃ is also compared on five consecutive days. The contents of catechins and caffeine in green and black teas are discussed and the difference of the content between different tealeaves can provide a reference for the assessment of tea quality.

关键词：咖啡因儿茶酚萃取法茶叶胶束电动套色版