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Stability and guaranteed cost control for uncertain time-delay Lur'e systems

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Journal of Systems Engineering and Electronics 2008年第3期19卷 546-554页

作者： zhang dongmei Yu Li zhang Wen'an Coll. of Science Zhejiang Uinv. of Technology Hangzhou 310032 P. R. China Dept. of Automation Zhejiang Uinv. of Technology Hangzhou 310032 P. R. China

The problem of delay-dependent stability and guaranteed cost control （GCC） for a class of uncertain time-delay Lur＇e systems are studied. By using an improved integral inequality,a less conservative delay-dependent stability criterion is formulated as the feasibility problem of the linear matrix inequality （LMI）. The criterion is proved theoretically to be less conservative than some existing results for linear time-delay systems. Because of the fact that the matrices in the LMI-based stability criteria usually have different dimensions, different structures, and different variables, the conservatism analysis of the criteria is difficult. This study brings about a new insight into the comparison of conservatism among different stability criteria, which are expressed in certain LMI forms. The existence of the guaranteed cost controller is given in terms of matrix inequalities. The condition can be solved by using an iterative procedure and does not need any parameter tuning. A numerical example is given to illustrate the effectiveness of the proposed method.

关键词： guaranteed cost control absolute stability LMI delay-dependent.

MICROMECHANICAL MODELLING OF PHASE TRANSFORMATION BEHAVIOUR OF A TRANSITIONAL SOIL

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Acta Mechanica Solida Sinica 2014年第3期27卷 259-275页

作者： Chuang Yu Zhenyu Yin dongmei zhang College of Architecture and Civil Engineering Wenzhou University LUNAM University Ecole Centrale de Nantes UMR CNRS GeM Nantes France Department of Geotechnical Engineering College of Civil Engineering Tongji University

Experiments show that silts and silty soils exhibit contraction followed by dilation during shearing and the slope of failure line decreases at large strains, termed as phase transformation behaviour. This paper is to develop a new micromechanical stress-strain model that accounts for the phase transformation behaviour by explicitly employing the phase transformation line and its related friction angles. The overall strain includes plastic sliding and plastic compression among grains. The internal-friction angle at the phase transformation state and the void state variable are employed to describe the phase transformation behaviour. The model is examined by simulating undrained and drained triaxial compression tests performed on Pitea silts. The local stress-strain behaviour for contact planes is also investigated.

关键词： micromechanics silts constitutive models elastoplasticity anisotropy simulation

Optimization and Parameters Estimation in Ultrasonic Echo Problems Using Modified Artificial Bee Colony Algorithm

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Journal of Bionic Engineering 2015年第1期12卷 160-169页

作者： Jinghua Zhou Xiaofeng zhang Guangbin zhang dongmei Chen Ultrasonic Key Laboratory of Shaanxi Province College of Physics and Information Technology Shaanxi Normal University Xi'an Shaanxi 710119 China

The patterns of ultrasonic backscattered echoes represent valuable information pertaining to the geometric shape, size, and orientation of the reflectors as well as the microstructure of the propagation path. Accurate estimation of the ultrasonic echo pattern is essential in determining the object or propagation path properties. This paper proposes a parameter estimation method for ultrasonic echoes based on Artificial Bee Colony （ABC） algorithm which is one of the most recent swarm intelligence based algorithms. A modified ABC （MABC） algorithm is given by adding an adjusting factor to the neighborhood search formula of traditional ABC algorithm in order to enhance its performance. The algorithm could overcome the impact of different search range on estimation accuracy to solve the multi-dimensional parameter optimization problems. The performance of the MABC algorithm is demonstrated by numerical simulation and ultrasonic detection experiments. Results show that MABC not only can accurately estimate various parameters of the ultrasonic echoes, but also can achieve the optimal solution in the global scope. The proposed algorithm also has the advantages of fast convergence speed, short running time and real-time parameters esti- mation.

关键词： artificial bee colony algorithm swarm intelligence global optimization ultrasonic echoes ultrasonic testing

Algorithms for the Prize-Collecting k-Steiner Tree Problem

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Tsinghua Science and Technology 2022年第5期27卷 785-792页

作者： Lu Han Changjun Wang Dachuan Xu dongmei zhang School of Science Beijing University of Posts and TelecommunicationsBeijing 100876China Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China Beijing Institute for Scientific and Engineering Computing Beijing University of TechnologyBeijing 100124China School of Computer Science and Technology Shandong Jianzhu UniversityJinan 250101China

In this paper,we study the prize-collecting k-Steiner tree(PCkST) *** are given a graph G=(V,E) and an integer *** graph is connected and undirected.A vertex r ∈ V called root and a subset R?V called terminals are also given.A feasible solution for the PCkST is a tree F rooted at r and connecting at least k vertices in *** a vertex from the tree incurs a penalty cost,and including an edge in the tree incurs an edge *** wish to find a feasible solution with minimum total *** total cost of a tree F is the sum of the edge costs of the edges in F and the penalty costs of the vertices not in *** present a simple approximation algorithm with the ratio of 5.9672 for the *** algorithm uses the approximation algorithms for the prize-collecting Steiner tree(PCST) problem and the k-Steiner tree(kST) problem as *** we propose a primal-dual based approximation algorithm and improve the approximation ratio to 5.

关键词： prize-collecting Steiner tree approximation algorithm

Regularized two-stage submodular maximization under streaming

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Science China(Information Sciences) 2022年第4期65卷 102-111页

作者： Ruiqi YANG Dachuan XU Longkun GUO dongmei zhang Beijing Institute for Scientific and Engineering Computing Beijing University of Technology School of Mathematical Sciences University of Chinese Academy Sciences School of Computer Science and Technology Qilu University of Technology School of Computer Science and Technology Shandong Jianzhu University

In the problem of maximizing regularized two-stage submodular functions in streams, we assemble a family ■ of m functions each of which is submodular and is visited in a streaming style that an element is visited for only once. The aim is to choose a subset S of size at most ■ from the element stream ■, so as to maximize the average maximum value of these functions restricted on S with a regularized modular term. The problem can be formally cast as ■, where c:■ is a non-negative modular function and ■ is a non-negative monotone non-decreasing submodular function. The well-studied regularized problem of ■ is exactly a special case of the above regularized two-stage submodular maximization by setting m=1 and ■=k. Although f(·)-c(·) is submodular, it is potentially negative and non-monotone and admits no constant multiplicative factor approximation. Therefore, we adopt a slightly weaker notion of approximation which constructs S such that f(S)-c(S)≥ρ·f(O)-c(O) holds against optimum solution O for some ρ∈(0, 1). Eventually, we devise a streaming algorithm by employing the distorted threshold technique, achieving a weaker approximation ratio with ρ=0.2996 for the discussed regularized two-stage model.

关键词： submodular maximization streaming model two-stage threshold technique approximation algorithms

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Effect of water level fluctuations on temporal-spatial patterns of foraging activities by the wintering Hooded Crane(Grus monacha)

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Chinese Birds 2015年第3期6卷 169-177页

作者： dongmei zhang Lizhi Zhou Yunwei Song School of Resources and Environmental Engineering Anhui University Institute of Biodiversity and Wetland Ecology Anhui University Anhui Biodiversity Information Center Shengjin Lake National Nature Reserve of Anhui Province

Background:The Yangtze River floodplain provides important wintering habitats for Hooded Cranes(Grus monacha) in *** in the water level change foraging habitat and food availability,affecting their temporal-spatial patterns of foraging *** is of considerable importance to investigate the effect of these fluctuations on food availability for wintering Hooded Cranes and their foraging response to these *** their behavior patterns is beneficial in protecting the wintering crane population and restoring their wintering ***:A field survey of the winter behavior of cranes was carried out at Shengjin Lake from November in 2013 to April in *** variables,as well as the spatial distribution and behavior patterns of wintering cranes at their foraging sites during five stages of water level fluctuation were *** on this data we analyzed the relationship of foraging behavior relative to water level fluctuations and habitat ***:The foraging habitats used by Hooded Cranes varied at the different water level *** the water level decreased,the use of meadows and mudflats *** the water dropped to its lowest level,the use by the Hooded Crane in the mudflats reached a *** were statistically significant differences in time budget in the three types of habitats over the five stages of the water *** the mudflats,the foraging behavior and maintenance behavior varied significantly with the water level,while the alert behavior showed little *** of a generalized linear model showed that the five water level stages and three habitat types had a significant effect on foraging behavior,while the combined effect of these two variables was significant on the foraging time budget and the length of foraging activity of the Hooded ***:With the decrease in the water level,the use of mudflats by Hooded Cranes increased *** availability in differ

关键词： Water level fluctuations Foraging activity Temporal-spatial pattern Hooded Crane Grus monacha

Unified modeling of the monotonic and cyclic behaviors of sand and clay

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Acta Mechanica Solida Sinica 2015年第2期28卷 111-132页

作者： Yinfu Jin Zhenyu Yin dongmei zhang Hongwei Huang Department of Geotechnical Engineering Tongji University Department of Civil Engineering Shanghai Jiao Tong University LUNAM University Ecole Centrale de Nantes

In this study, we aim to investigate a unified modeling method for the monotonic and cyclic behaviors of sand and clay. A simple double-yield-surface model, with plastic hardening modulus and dilatancy relation being dependent on density state unlike in existing approaches, is developed by considering the location of the critical state line. The model is used to simulate the drained and undrained tests of various sands and clays under monotonic and cyclic loadings. Prediction results are compared with experimental results, which show that the proposed approach is capable of modeling the monotonic and cyclic behaviors of sand and clay.

关键词： sand clay constitutive relations plasticity critical state cyclic loading

MnO_(2)-coated nanodiamond-driven photodynamic therapy for enhanced antitumor effect by addressing hypoxia and glutathione depletion

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Particuology 2024年第9期92卷 305-315页

作者： Jicheng Cui dongmei zhang Hui Qiao Zeyu Yan Wenxia zhang Yingqi Li Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education Institute of Molecular ScienceShanxi UniversityTaiyuan030006China Taiyuan Central Hospital Taiyuan030009China School of Chemistry and Chemical Engineering Shanxi UniversityTaiyuan030006China

The generation of reactive oxygen species(ROS)at the tumor site to induce destruction is emerging as a novel strategy for cancer treatment,which involves photodynamic therapy(PDT).Nevertheless,tumors typically create a hypoxic environment and are equipped with an endogenous antioxidant defense system that could potentially impede the efficiency of the therapeutic *** overcome these drawbacks,herein,a tumor microenvironment-responsive the ND-PAA-CD-Ce6@MnO_(2)(NPCC@M)delivery system was fabricated by disulfide bond coupling chlorin e6(Ce6)to nanodiamond(ND)and further wrapped by MnO_(2)nanosheets to facilitate *** use of disulfide bond not only stabilizes Ce6 in the blood circulation to prevent premature leakage,but also destroys the antioxidant barrier of overexpressed glutathione(GSH)in tumor ***,the outer MnO_(2)was rapidly degraded by the endogenous hydrogen peroxide(H_(2)O_(2))in the acidic pH and GSH within the tumor cells,which leads to an abundance of O_(2)and while increases the level of 1O_(2)under laser *** results eventually broke the redox homeostasis and attenuate hypoxia,thereby inducing apoptosis and necrosis of tumor *** in vitro and in vivo biological effect has revealed a good biosafety profile and a high tumor suppression *** a novel ND-based system with tumor microenvironment-modulating capability to elevate oxygen content and promote GSH consumption in tumor cells opens new opportunities for enhanced ROS treatment paradigms.

关键词： Nanodiamond Photodynamic Chlorin e6 MnO_(2) Tumor suppression

Auto machine learning-based modelling and prediction of excavationinduced tunnel displacement

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第4期14卷 1100-1114页

作者： dongmei zhang Yiming Shen Zhongkai Huang Xiaochuang Xie Key Laboratory of Geotechnical and Underground Engineering Ministry of EducationTongji UniversityShanghai200092China Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai200092China

The influence of a deep excavation on existing shield tunnels nearby is a vital issue in tunnelling ***,there lacks robust methods to predict excavation-induced tunnel *** this study,an auto machine learning(AutoML)-based approach is proposed to precisely solve the *** input parameters are considered in the database covering two physical aspects,namely soil property,and spatial characteristics of the deep *** 10-fold cross-validation method is employed to overcome the scarcity of data,and promote model’s *** genetic algorithm(GA)-ML models are established as well for *** results indicated that the proposed AutoML model is a comprehensive model that integrates efficiency and *** analysis reveals that the ratio of the average shear strength to the vertical effective stress E_(ur)/σ′_(v),the excavation depth H,and the excavation width B are the most influential variables for the ***,the AutoML model is further validated by practical *** prediction results are in a good agreement with monitoring data,signifying that our model can be applied in real projects.

关键词： Soilestructure interaction Auto machine learning(AutoML) Displacement prediction Robust model Geotechnical engineering