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Energy-based multi-view piecewise planar stereo

Science China(Information Sciences) 2017年第3期60卷 32-49页

作者： Wei WANG Lihua hu Zhanyi hu School of Network Engineering Zhoukou Normal University National Laboratory of Pattern Recognition Institute of Automation Chinese Academy of Sciences School of Computer Science and Technology Taiyuan University of Science and Technology

The piecewise planar model(PPM) is an effective means of approximating a complex scene by using planar patches to give a complete interpretation of the spatial points reconstructed from projected 2D *** traditional piecewise planar stereo methods suffer from either a very restricted number of directions for plane detection or heavy reliance on the segmentation accuracy of superpixels. To address these issues, we propose a new multi-view piecewise planar stereo method in this paper. Our method formulates the problem of complete scene reconstruction as a multi-level energy minimization problem. To detect planes along principal directions,a novel energy formulation with pair-wise potentials is used to assign an optimal plane for each superpixel in an iterative manner, where reliable scene priors and geometric constraints are incorporated to enhance the modeling efficacy and inference efficiency. To detect non-principal-direction planes, we adopt a multi-direction plane sweeping with a restricted search space method to generate reliable candidate planes. To handle the multi-surface straddling problem of a single superpixel, a superpixel sub-segmenting scheme is proposed and a robust PnPotts model-like higher-order potential is introduced to refine the resulting depth map. Our method is a natural integration of pixel- and superpixel-level multi-view stereos under a unified energy minimization framework. Experimental results for standard data sets and our own data sets show that our proposed method can satisfactorily handle many challenging factors(e.g., slanted surfaces and poorly textured regions) and can obtain accurate piecewise planar depth maps.

关键词： piecewise planar model depth map plane fitting energy optimization multi-view stereo

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自适应变分模态分解算法在高温高压水空化特性分析中的应用

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西安交通大学学报 2025年第1期59卷 56-67页

作者：许博胡鸿飞王海军西安交通大学能源与动力工程学院西安710049

针对高温高压流动工况下,空化状态判断困难、传统分析方法难以有效提取压力脉动信号中的有效信息的问题,以孔板为对象,开展了高温高压水的空化实验,并提出了一种基于遗传算法的自适应变分模态分解(AVMD)算法。该算法通过结合中心频率法... 详细信息

针对高温高压流动工况下,空化状态判断困难、传统分析方法难以有效提取压力脉动信号中的有效信息的问题,以孔板为对象,开展了高温高压水的空化实验,并提出了一种基于遗传算法的自适应变分模态分解(AVMD)算法。该算法通过结合中心频率法、遗传算法、功率谱熵和相对能量等技术,自适应地确定变分模态分解算法中的超参数并有效去除信号中的噪声成分,提高了空化特征的提取精度。结果表明:AVMD算法能够精确捕捉到高温高压水流经孔板时空化现象的发生和发展,识别空化起始点、转捩点以及空化强度的变化;当高温高压水流经孔板后,压力脉动的无量纲频率在0.04~0.35、压力脉动的无量纲幅值在0.014~0.067时,空化现象开始出现;随着空化强度增加,管内压力脉动幅值和频率整体呈增大趋势;空化起始转捩点及空化严重转捩点与入口压力和工质入口过冷度密切相关。AVMD算法能够有效提高空化特性分析的精度,尤其是在复杂流动条件下的空化预测,为压水堆核电站冷却剂系统和高压蒸汽系统的稳定运行提供理论依据和参考。

关键词：高温高压水空化特性自适应变分模态分解孔板

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Role of boron in TiAl alloy development: a review

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Rare Metals 2016年第1期35卷 1-14页

作者： Dawei hu Interdisciplinary Research Centre in Materials University of Birmingham

Boron was found to be a unique grain refiner in cast TiAl alloys in the beginning of 1990 s and has become an element in most of the TiAl alloys developed to *** the past 25 or so years,efforts to understand the role of boron in solidification,solid-phase transformation,thermal and thermomechanical processing and mechanical properties of TiAl alloys and the relevant mechanisms never *** a result,abundant knowledge on boron in TiAl alloys has been accumulated but scattered in various research papers and conference *** review summarises the progress in understanding boron and its impacts on the TiAl alloy systems.

关键词： Titanium aluminide TiAl Ti3Al Boron Grain refinement

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Simulating coupled dynamics of a rigid-flexible multibody system and compressible fluid

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Science China(Physics,Mechanics & Astronomy) 2018年第4期61卷 54-68页

作者： Wei hu Qiang Tian HaiYan hu Ministry of Education Key Laboratory of Dynamics and Control of Flight Vehicle School of Aerospace Engineering Beijing Institute of Technology

As a subsequent work of previous studies of authors, a new parallel computation approach is proposed to simulate the coupled dynamics of a rigid-flexible multibody system and compressible fluid. In this approach, the smoothed particle hydrodynamics(SPH) method is used to model the compressible fluid, the natural coordinate formulation(NCF) and absolute nodal coordinate formulation(ANCF) are used to model the rigid and flexible bodies, respectively. In order to model the compressible fluid properly and efficiently via SPH method, three measures are taken as follows. The first is to use the Riemann solver to cope with the fluid compressibility, the second is to define virtual particles of SPH to model the dynamic interaction between the fluid and the multibody system, and the third is to impose the boundary conditions of periodical inflow and outflow to reduce the number of SPH particles involved in the computation process. Afterwards, a parallel computation strategy is proposed based on the graphics processing unit(GPU) to detect the neighboring SPH particles and to solve the dynamic equations of SPH particles in order to improve the computation efficiency. Meanwhile, the generalized-alpha algorithm is used to solve the dynamic equations of the multibody system. Finally, four case studies are given to validate the proposed parallel computation approach.

关键词： smoothed particle hydrodynamics(SPH) compressible flow Riemann solver absolute nodal coordinate formulation(ANCF) graphics processing unit(GPU)

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Properties of SV-Style Homomorphic Encryption and Their Application

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Chinese Journal of Electronics 2017年第5期26卷 926-932页

作者： CHEN hu hu Yupu LIAN Zhizhu State Key Laboratory of Integrated Service Networks Xidian University Jiangsu Key Laboratory of Education Big Data Science and Engineering Jiangsu Normal University

Several special properties of Smart and Vercauteren’s encryption scheme are put *** are all based on the special parameter,which is a recommended modulus *** properties not only show that the secret key is deduced from an N-dimensional vector into its any entry,but also produce the triplet(grade-i reduced plaintext space,grade-i reduced ciphertext space,grade-i reduced secret key) for each i,where grade-i reduced secret key can decrypt grade-i reduced ciphertexts and can be efficiently computed from grade-i delegated *** the same time,sequentially grade-(i + 1)delegated key can be efficiently computed from grade-i delegated *** work also discusses a sequential computation in opposite direction,i.e.,computing grade-i delegated key from grade-(i + 1) delegated *** the sequential computation in the opposite direction is difficult except at most the first steps of such sequential *** on the properties given,we then propose a simple hierarchical encryption scheme with relatively small key and ciphertext sizes.

关键词： Lattice-based cryptosystem Fully homomorphic encryption Hierarchical encryption

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Steady-state responses of a belt-drive dynamical system under dual excitations

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Acta Mechanica Sinica 2016年第1期32卷 156-169页

作者： hu Ding Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai 200072China

The stable steady-state periodic responses of a belt-drive system with a one-way clutch are studied. For the first time, the dynamical system is investigated under dual excitations. The system is simultaneously excited by the firing pulsations of the engine and the harmonic motion of the foundation. Nonlinear discrete-continuous equations are derived for coupling the transverse vibration of the belt spans and the rotations of the driving and driven pulleys and the accessory pulley. The nonlinear dynamics is studied under equal and multiple relations between the frequency of the fir- ing pulsations and the frequency of the foundation motion. Furthermore, translating belt spans are modeled as axially moving strings. A set of nonlinear piecewise ordinary differ- ential equations is achieved by using the Galerkin truncation. Under various relations between the excitation frequencies, the time histories of the dynamical system are numerically simulated based on the time discretization method. Further- more, the stable steady-state periodic response curves are calculated based on the frequency sweep. Moreover, the convergence of the Galerkin truncation is examined. Numer- ical results demonstrate that the one-way clutch reduces the resonance amplitude of the rotations of the driven pul- ley and the accessory pulley. On the other hand, numerical examples prove that the resonance areas of the belt spans are decreased by eliminating the torque-transmitting in the opposite direction. With the increasing amplitude of the foun- dation excitation, the damping effect of the one-way clutch will be reduced. Furthermore, as the amplitude of the firing pulsations of the engine increases, the jumping phenomena in steady-state response curves of the belt-drive system with or without a one-way clutch both occur.

关键词： Nonlinear vibration One-way clutch Dynamical system Steady-state responses Galerkinmethod

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Statistic Measurement and Empirical Research on Sustainable Development of China Internet

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Journal of Systems Science & Complexity 2016年第2期29卷 336-349页

作者： hu Yonghong School of Statistics and Mathematics Central University of Finance and Economics

In this paper,the concepts of green development and coordinated development of the Internet are proposed,and the connotation of sustainable development of the Internet is defined *** on these,by using the comprehensive evaluation method,the Internet sustainable development index(ISDI) system is created and designed,the sustainable development level of the Internet in China is evaluated and measured systematically,and corresponding policy suggestions are given.

关键词： Index Internet sustainable development.

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EMPIRICAL LIKELIHOOD INFERENCE FOR LOGISTIC EQUATION WITH RANDOM PERTURBATION

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Journal of Systems Science & Complexity 2014年第2期27卷 350-359页

作者： hu Xuemei School of Mathematics and Statistics ChongQing Technology and Business University Academy of Mathematics and Systems Science Chinese Academy of Sciences

Empirical likelihood(EL) combined with estimating equations(EE) provides a modern semi-parametric alternative to classical estimation techniques such as maximum likelihood estimation(MLE). This paper not only uses closed form of conditional expectation and conditional variance of Logistic equation with random perturbation to perform maximum empirical likelihood estimation(MELE) for the model parameters, but also proposes an empirical likelihood ratio statistic(ELRS) for hypotheses concerning the interesting parameter. Monte Carlo simulation results show that MELE and ELRS provide competitive performance to parametric alternatives.

关键词： Empirical likelihood ratio statistic estimating equations logistic equation with randomperturbation maximum empirical likelihood estimations maximum likelihood estimation.

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High Accuracy Gene Signature for Chemosensitivity Prediction in Breast Cancer

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Tsinghua Science and Technology 2015年第5期20卷 530-536页

作者： Wei hu Department of Computer Science Houghton College

Neoadjuvant chemotherapy for breast cancer patients with large tumor size is a necessary *** this treatment patients who achieve a pathologic Complete Response（p CR） usually have a favorable prognosis than those without. Therefore, p CR is now considered as the best prognosticator for patients with neoadjuvant chemotherapy. However, not all patients can benefit from this treatment. As a result, we need to find a way to predict what kind of patients can induce p CR. Various gene signatures of chemosensitivity in breast cancer have been identified, from which such predictors can be built. Nevertheless, many of them have their prediction accuracy around 80%. As such, identifying gene signatures that could be employed to build high accuracy predictors is a prerequisite for their clinical tests and applications. Furthermore, to elucidate the importance of each individual gene in a signature is another pressing need before such signature could be tested in clinical settings. In this study, Genetic Algorithm（GA） and Sparse Logistic Regression（SLR） along with t-test were employed to identify one signature. It had 28 probe sets selected by GA from the top 65 probe sets that were highly overexpressed between p CR and Residual Disease（RD） and was used to build an SLR predictor of p CR（SLR-28）. This predictor tested on a training set（n = 81） and validation set（n = 52） had very precise predictions measured by accuracy,specificity, sensitivity, positive predictive value, and negative predictive value with their corresponding P value all zero. Furthermore, this predictor discovered 12 important genes in the 28 probe set signature. Our findings also demonstrated that the most discriminative genes measured by SLR as a group selected by GA were not necessarily those with the smallest P values by t-test as individual genes, highlighting the ability of GA to capture the interacting genes in p CR prediction as multivariate techniques. Our gene signature produced superior per

关键词： genetic algorithm gene signature breast cancer sparse logistic regression predictor chemosensitivity

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ESTIMATION IN A SEMI-VARYING COEFFICIENT MODEL FOR PANEL DATA WITH FIXED EFFECTS

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Journal of Systems Science & Complexity 2014年第3期27卷 594-604页

作者： hu Xuemei School of Mathematics and Statistics Chongqing Technology and Business University Academy of Mathematics and Systems Science Chinese Academy of Sciences

This paper considers a semi-varying coefficient model for panel data with fixed effects,proposes the profile-likelihood-based estimators for the parametric and nonparametric components,and establishes convergence rates and asymptotic normality properties for both *** results show that the proposed estimators behave well in finite sample cases.

关键词： Fixed effect profile likelihood semi-varying coefficient model for panel data.

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