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Ferroelectric properties of Bi_(3.4)Ho_(0.6)Ti_3O_(1.) thin films prepared by sol-gel method

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Science china(Technological Sciences) 2008年第9期51卷 1439-1444页

作者： fu ChengJu1, HUANG Zhixiong1, LI Jie2 & GUO DongYun3 1 school of Materials Science and Technology, wuhan university of Technology, wuhan 430070, china 2 school of Mechanical Engineering, Chongqing university of Science and Technology, Chongqing 400050, china 3 Department of Physics, wuhan university, wuhan 430072, china school of Materials Science and Technology Wuhan University of Technology Wuhan China school of Mechanical Engineering Chongqing University of Science and Technology Chongqing China Department of Physics Wuhan University Wuhan China

We have prepared the Ho-substituted bismuth titanate (Bi3.4Ho0.6Ti3O1., BHT) thin films on Pt/Ti/SiO2/Si substrates using sol-gel method. The crystal structure and morphology of the films were characterized using X-ray diffraction and atomic force microscopy. The BHT film shows a single phase of Bi-layered Aurivillius structure and dense microstructure. The 2Pr and 2Ec of the 600-nm-thick BHT film were 38.4 μC/cm2 and 376.1.kV/cm, respectively at applied electric field 500 kV/cm. The dielectric constant and dielectric loss are about 31. and 0.01. at a frequency of 1.MHz, respectively. The Pr value decreased to 93% of its pre-fatigue values after 4.46×1.9 switching cycles at 1.MHz frenquency, and the BHT film shows good in-sulating behavior according to the test of leakage current.

关键词： Bi3.4Ho0.6Ti3O1. thin film sol-gel method ferroelectric property fatigue dielectric constant

Research on theory and key technology of trusted computing platform security testing and evaluation

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Science china(Information Sciences) 2010年第3期53卷 434-453页

作者： ZHANG HuanGuo1.2, YAN Fei1.2, fu JianMing1.2, {1. MingDi1.2, YANG Yang1.2, HE Fan1.2 & ZHAN Jing1.2 1.2} of Computer, wuhan university, wuhan 430072, china 2Key Laboratory of Aerospace Information Security and Trusted Computing, Ministry of Education, wuhan 430072, china school of Computer Wuhan University Wuhan China Key Laboratory of Aerospace Information Security and Trusted Computing Ministry of Education Wuhan China

Trusted computing has become a new trend in the area of international information security, and the products of trusted computing platform begin to be used in application. Users will not use the products of information security, unless it goes through the testing and evaluation. Here we concentrate on the testing and evaluation problem of trusted computing platform, begin with constructing proper formalization model of trusted computing platform for testing, and establish a mathematical chain of trust model based on SPA. Moreover, we give a verification method of composite characteristics and find the potential factors threatening the trusted system in the process of remote attestation through analysis. For trusted software stack, we study the problem of automatic generation of test case and propose an improved method of generating the random test case, to raise the quality of test case. Finally, we give a prototype system of trusted computing platform and the actual test data related. The result demonstrates that there exist some flaws in the architecture of the present TCG computing platform. At the same time, some flaws are found in the products of existing trusted computing platform, thus a basis is laid for the improvement and development of trusted platform technology and its products.

关键词： information security trusted computing trusted computing platform testing and evaluation

Microstructure and Fractural Morphology of Cobalt-based Alloy Laser Cladding

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Journal of wuhan university of Technology(Materials Science) 2003年第3期18卷 30-32页

作者：陈浩 school of Materials Science and Engineering Wuhan Univercity of Technology

The solidification features,micro segregation,and fracture characteristics of cobalt based alloy on the substrate of 20CrMo steel by laser cladding were studied by using electron *** results show that the fine columnar grains and cellular dendrite grains are obtained which are perpendicular to the coating/substrate interface;the primary arms are straight while the side branches are degenerated;the microstructure consists of primary face centered cubic (fcc) Co dendrites and a network of Cr enriched eutectic M23C6 (M=Cr,W,Fe) carbides;the micro segregation is severe for the rapid heating and cooling of laser cladding;the typical brittle intergranular fracture occurs in cobalt based laser cladding layer.

关键词： laser cladding Cobalt based alloy solidification microstructure micro segregation fracture

Scaling up the DBSCAN Algorithm for Clustering Large Spatial Databases Based on Sampling Technique

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wuhan university Journal of Natural Sciences 2001年第Z1期6卷 467-473页

作者： Guan Ji hong 1. Zhou Shui geng 2, Bian fu ling 3, He Yan xiang 1.1. {1. of Computer, wuhan university, wuhan 430072, china 2.State Key Laboratory of Software Engineering, wuhan university, wuhan 430072, china 3.College of Remote Sensin school of Computer Wuhan University Wuhan China State Key Laboratory of Software Engineering Wuhan University Wuhan China College of Remote Sensing and Information Engineering Wuhan University Wuhan China

Clustering, in data mining, is a useful technique for discovering interesting data distributions and patterns in the underlying data, and has many application fields, such as statistical data analysis, pattern recognition, image processing, and etc. We combine sampling technique with DBSCAN algorithm to cluster large spatial databases, and two sampling based DBSCAN (SDBSCAN) algorithms are developed. One algorithm introduces sampling technique inside DBSCAN, and the other uses sampling procedure outside DBSCAN. Experimental results demonstrate that our algorithms are effective and efficient in clustering large scale spatial databases.

关键词： spatial databases data mining clustering sampling DBSCAN algorithm

On the new results of global attractive set and positive invariant set of the Lorenz chaotic system and the applications to chaos control and synchronization

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Science in china(Series F) 2005年第3期48卷 304-321页

作者： LIAO Xiaoxin 1, 2, 3 , fu Yuli 4 & XIE Shengli 4 1. Department of Control Science & Control Engineering, Huazhong university of Science & Technology, wuhan 430074, china 2. school of Automation, wuhan university of Science & Technology, wuhan 430070, china 3. school of Information, Central South university of Economy, Politics and law, wuhan 430064, china 4. school of Electronics & Information Engineering, South china university of Technology, Guangzhou 510640, china Correspondence should be addressed to Liao Xiaoxin (email: xiaoxin_liao@***) Department of Control Science & Control Engineering Huazhong University of Science & Technology Wuhan China school of Automation Wuhan University of Science & Technology Wuhan China school of Information Central South University of Economy Politics and Law Wuhan China school of Electronics & Information Engineering South China University of Technology Guangzhou China

Constructing a family of generalized Lyapunov functions, a new method is proposed to obtain new global attractive set and positive invariant set of the Lorenz chaotic system. The method we proposed greatly simplifies the complex proofs of the two famous estimations presented by the Russian scholar Leonov. Our uniform formula can derive a series of the new estimations. Employing the idea of intersection in set theory, we extract a new Leonov formula-like estimation from the family of the estimations. With our method and the new estimation, one can confirm that there are no equilibrium, periodic solutions, almost periodic motions, wandering motions or other chaotic attractors outside the global attractive set. The Lorenz butterfly-like singular attractors are located in the global attractive set only. This result is applied to the chaos control and chaos synchronization. Some feedback control {1.s are obtained to guarantee that all the trajectories of the Lorenz systems track a periodic solution, or globally stabilize an unstable (or locally stable but not globally asymptotically stable) equilibrium. further, some new global exponential chaos synchronization results are presented. Our new method and the new results are expected to be applied in real secure communication systems.

关键词： Lorenz chaotic system global attractive set positive invariant set globally exponential tracking globally exponential synchronization.

Advanced Design of Soft Robots with Artificial Intelligence

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Nano-Micro Letters 2024年第10期16卷 474-521页

作者： Ying Cao Bingang xu Bin Li Hong {1. Nanotechnology Center School of Fashion and TextilesThe Hong Kong Polytechnic UniversityHong Kong 999077People's Republic of China Department of Mathematics and Information Technology The Education University of Hong KongHong Kong 999077People's Republic of China Bioinspired Engineering and Biomechanics Center Xi'an Jiaotong UniversityXi'an 710049People's Republic of China

In recent years,breakthrough has been made in the field of artificial intelligence(AI),which has also revolutionized the industry of *** robots featured with high-level safety,less weight,lower power consumption have always been one of the research ***,multifunctional sensors for perception of soft robotics have been rapidly developed,while more algorithms and models of machine learning with high accuracy have been optimized and *** of soft robots with AI have also been advanced ranging from multimodal sensing,human-machine interaction to effective actuation in robotic ***-less,comprehensive reviews concerning the new developments and strategies for the ingenious design of the soft robotic systems equipped with AI are ***,the new development is systematically reviewed in the field of soft robots with ***,background and mechanisms of soft robotic systems are briefed,after which development focused on how to endow the soft robots with AI,including the aspects of feeling,thought and reaction,is ***,applications of soft robots with AI are systematically summarized and discussed together with advanced strategies proposed for performance *** thoughts for future intelligent soft robotics are pointed ***,some perspectives are put forward.

关键词： Soft robotic systems Artificial intelligence Design tactics Review and perspective

Differential Hydrological Grey Model (DHGM) with self-memory function and its application to flood forecasting

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Science china(Technological Sciences) 2009年第4期52卷 1039-1049页

作者： CHEN XiangDong1. XIA Jun1.2 & xu Qian3 1.Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 1.01.1.{1. 2 State Key Laboratory of Water Resources and Hydropower Engineering Science, wuhan university, wuhan 430072,{1. 3 school of Hydrology and Water Resources, Hohai university, Nanjing 21.098,{1. Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Wuhan China school of Hydrology and Water Resources Hohai University Nanjing China

This paper addresses a problem of flood forecasting with the self-memory function. Considering flood forecasting’s uncertainty and updating demand, a hybrid hydrological model, namely Differential Hy- drological Grey Model with self-memory function (DHGM-SM), is developed. The model has two fold features. One is to establish a self-memorization equation linked with DHGM, that could extract useful information from past data series and realize updating of hydrological dynamic process. The other is that this model has higher efficiency relative to original hydrological model without self-memory func- tion. This approach was applied to river flow forecasting of two representative basins in Tunxi of South china and Daqinggou of North china. It is shown that this hybrid method has satisfactory forecasting accuracy by examination of both calibration and validation.

关键词： differential grey model the self-memorization principle real-time forecasting faded-memory recursive least square method

Building Distributed Web GIS: A Mobile Agent Based Approach

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wuhan university Journal of Natural Sciences 2001年第Z1期6卷 474-481页

作者： jhguan@*** Guan Ji hong 1., Zhou Shui geng 2 , Bian fu ling 3, Meng Ling kui 3 1. {1. of Computer, wuhan university, wuhan 430072, china 2. State Key Laboratory of Software Engineering, wuhan university, wuhan 430072, Chin school of Computer Wuhan University Wuhan China State Key Laboratory of Software Engineering Wuhan University Wuhan China College of Remote Sensing and Information Engineering Wuhan University Wuhan China

The diversity of GISs and the wide spread availability of WWW have led to an increasing amount of research on integrating a variety of heterogeneous and autonomous GISs in a cooperative environment to construct a new generation of GIS characterizing in open architecture, distributed computation, interoperability, and extensibility. Our on going research project MADGIS (Mobile Agent based Distributed Geographic Information System) is reported, in which we propose the architecture of MADGIS to meet the requirements of integrating distributed GIS applications under Internet environment. We first describe the architecture of MADGIS, and detailed discussions focusing on the structure of client site, server site and mobile agent in MADGIS. Then we explore key techniques for MADGIS implementation.

关键词： distributed GIS mobile agent architecture mobility interoperability

Experimental study and correlation development for the two-phase frictional pressure drop of flow boiling in copper foam fin microchannels

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Science china(Technological Sciences) 2024年第9期67卷 2758-2776页

作者： fu Kai {1. XiangHua LIANG XinGang school of Aerospace Engineering Tsinghua UniversityBeijing 100084China

Flow boiling in microchannels with porous walls has received extensive attention in recent years. Compared with the emphasis on heat transfer, there is a lack of research on the effect of the porous wall structures on the pressure drop characteristics. In this study, systematic experiments are performed to measure the pressure drop of water-vapor two-phase flow in five microchannels with copper foam fins, which consist of nine or six channels and fins of copper foam. The porosities of the foam fins range from0.78 to 0.82 and ratios of fin width to channel width range from 0.5 to 2. The channels are approximately 0.5 or 1.mm in width and 1.mm in height. Both adiabatic and flow boiling experiments are conducted with water at mass fluxes ranging from 66 to 407 kg/(m^(2)s). In the adiabatic experiments, the average quality in channels is between 0.01. and 0.846. In the flow boiling experiments, the outlet quality of channels is between 0.040 and 0.863. Slug flow, churn flow, annular flow, and wispy-annular flow are observed in adiabatic experiments. A two-phase frictional pressure drop correlation based on the Lockhart-Martinelli model is developed for copper foam fin microchannels by introducing the effects of the mass flux, porosity, ratio of fin width to channel width, and heating condition step by step. The mean absolute percentage errors of the new correlation are 7.53% for 325data points under adiabatic conditions and 5.51. for 268 data points under flow boiling conditions, respectively. This work provides insight into the correlations of frictional pressure drop in microchannels with porous walls.

关键词： two-phase flow boiling pressure drop correlation microchannel copper foam porous wall