检索结果-南通市图书馆

Earthquake Engineering and Engineering Vibration 2010年第2期9卷 247-258页

作者： He Xiaoyu and Li Hongnan 1.Zhejiang Provincial Planning,Design & Research Institute of communications,hangzhou 310006,china 2.State Key Laboratory of coastal and Offshore Engineering,Dalian University of technology,Dalian 116024,china Zhejiang Provincial Planning Design & Research Institute of Communications Hangzhou China State Key Laboratory of coastal and Offshore Engineering Dalian University of Technology Dalian China

The dynamic equations of motion of asymmetric offshore platforms under three different environmental conditions:seismic action,wave action and their combination are established in this paper. In establishing these motion equations,three typical eccentricity types including mass eccentricity,rigidity eccentricity and their combination were considered,as are eccentricities that occur un-idirectionally and bi-directionally. The effects of the eccentricity type,the dynamic characteristics and the environmental conditions on the torsional coupling response of platforms are investigated and compared. An effort has also been made to analyze the inffluence of accidental eccentricity on asymmetric platforms with different eccentricity in two horizontally orthogonal directions. The results are given in terms of non-dimensional parameters,accounting for the uncoupled torsional to lateral frequency ratio. Numerical results reveal that the eccentricity type has a great inffluence on the torsionally coupled response under different environmental conditions. Therefore,it is necessary to consider the combination of earthquake and wave action in the seismic response analysis of some offshore platforms.

关键词： offshore platform asymmetric structure accidental eccentricity torsion coupling earthquake load wave load

Fusion tracking in color and infrared images using joint sparse representation

在线全文

学校读者我要写书评

暂无评论

science china(Information sciences) 2012年第3期55卷 590-599页

作者： LIU HuaPing1,2,3 & SUN FuChun1,2,3 1Department of computer science and technology, Tsinghua University, Beijing 100084, china 2State Key Laboratory of Intelligent technology and Systems, Beijing 100084, china 3Tsinghua National Laboratory for Information science and technology, Beijing 100084, china Department of computer science and technology Tsinghua University Beijing China State Key Laboratory of Intelligent technology and Systems Beijing China Tsinghua National Laboratory for Information science and technology Beijing China

Currently sparse signal reconstruction gains considerable interest and is applied in many fields. In this paper, a similarity induced by joint sparse representation is designed to construct the likelihood function of particle filter tracker so that the color visual spectrum and thermal spectrum images can be fused for object tracking. The proposed fusion scheme performs joint sparse representation calculation on both modalities and the resultant tracking results are fused using min operation on the sparse representation coefficients. In addition, a co-learning approach is proposed to update the reference templates of both modality and enhance the tracking robustness. The proposed fusion scheme outperforms state-of-the-art approaches, and its effectiveness is verified using OTCBVS database.

关键词： joint sparse representation fusion tracking color image infrared image

Effect of Initial Microstructure on Warm Deformation Behavior of 45 Steel

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2012年第8期19卷 75-78页

作者： ZHAO Xin1, YANG Xiao-ling2, JING Tian-fu3 (1. The Sixth Department, Zhengzhou Institute of Aeronautics, Zhengzhou 450015, Henan, china 2. Zhengzhou Zhongxing Basic constructions Development co ltd, Zhengzhou 450015, Henan, china 3. State Key Laboratory of Metastable Materials science and technology, Qinhuangdao 066004, Hebei, china) The Sixth Department Zhengzhou Institute of Aeronautics Zhengzhou Henan China Zhengzhou Zhongxing Basic constructions Development co ltd Zhengzhou Henan China State Key Laboratory of Metastable Materials science and technology Qinhuangdao Hebei China

In order to investigate the effect of initial microstructure on warm deformation behavior, some specimens of 45 steel were annealed and some quenched. Then the specimens were isothermally compressed on a Gleeble 3500 machine. The deformation temperature range was 550 to 700 ℃ and the strain rate range was 0.001 to 0.1 s-1. An optical microscope (OM) and a transmission electron microscope (TEM) were used to study the microstructures. The results show that the microstructure of annealed specimens is ferrite and pearlite and that of quenched specimens is martensite. The flow stress of quenched specimens is higher than that of annealed ones at 550 ℃ when strain rates are greater than 0.001 s-1. However, at 600 to 700 ℃ and strain rate of 0.001 s-1, the whole flow curves of quenched specimens are below that of annealed ones. Under the rest conditions, the flow stress of quenched specimens is higher at the beginning of compression and then the opposite is true after the strain is greater than a critical value. The microstructure examination proves that the tempering and dynamic recrystallization easily occur in the specimens with martensite during warm compression, which results in the above phenomena.

关键词： warm deformation flow stress steel microstructure

Fractal Structure of the core Loss Spectrum of co-based Amorphous Soft Magnetic Alloy with constant Permeability

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 1999年第1期13卷 54-56页

作者： Yiping Chen (Applied science School, University of science and technology Beijing, Beijing 100083, china) Applied science School University of Science and Technology Beijing Beijing 100083 China

In order to check the traditional core loss formula, the core loss spectrum P(f) of co-based amorphous soft magnetic alloy with constant permeability has been studied. It is found that within a high frequency range from 10 kHz to 200 kHz and at Bm = 0. 1 T,the P(f) has the fractal structure P (f) = Po, and with the increasing of induced anisotropy energy Ku, the fractal dimension Dfrises, thus the total power loss at high frequency increases and the frequency characteristic of P(f) becomes worse.

关键词： amorphous soft magnetic alloy constant permeability core loss fractal

Scenario simulation and forecast of land use/cover in northern china

在线全文

学校读者我要写书评

暂无评论

Chinese science Bulletin 2008年第9期53卷 1401-1412页

作者： LI YueChen 1,2,3 & HE ChunYang 3 1 college of Geographical science, Chongqing Normal University, Chongqing 400047, china 2 college of Resources and Environmental science, Chongqing University, Chongqing 400044, china 3 college of Resources science & technology, Beijing Normal University, Beijing 100875, china college of Geographical science Chongqing Normal University Chongqing China college of Resources and Environmental science Chongqing University Chongqing China college of Resources science & technology Beijing Normal University Beijing China

Modeling land use/cover scenario changes and its potential impacts on structure and functions of ecosystem in typical regions are helpful to understanding the interactive mechanism between land use/cover system and ecosystem. Based on the analysis of the existing land use/cover simulation and forecast models, a land use/cover scenario dynamics model by the integration of System Dynamics (SD) model, Back Propagation Neural Network (BPNN) and Cellular Automata (CA) model is developed with land use/cover scenario changes in northern china in the next 30 years and simulated in this paper. The model is to simulate the land use/cover scenario demands by using a SD model at first, and then allocating the land use scenario patterns at the local scale with the considerations of land use/cover suitability, inheritance ability and neighborhood effect by using BPNN-CA model to satisfy the balance between land use/cover scenario demands and supplies. It integrates the advantages of SD, BPNN and CA. Macro-driving factors and the micro-spatial pattern are also fully taken into account. The BPNN simplifies the identification of the factors’ weights used in CA model and improves the reliability of the simulation results. The simulation accuracy of the model developed in this paper was found to be about 74%. It suggests that the model has the ability to reflect the complexity of land use/cover system at different scales to some extent and it is a useful tool for assessing the potential impacts of land use system on ecosystem. The simulated results also indicate that the urban land, water area and forest will increase significantly, and farmland and unable land will decrease gradually. Obvious land use/cover changes will take place in the farming-pastoral zone and the southeast area of northern china.

关键词：土地利用中国北方细胞自动机系统动力学

An efficient and DoS-resistant user authentication scheme for two-tiered wireless sensor networks

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-science C(computers and Electronics) 2011年第7期12卷 550-560页

作者： Rong FAN ,Dao-jing HE ,Xue-zeng PAN,Ling-di PING (School of computer science and technology,Zhejiang University,hangzhou 310027,china) School of computer science and technology Zhejiang University Hangzhou China

Wireless sensor networks (WSNs) are vulnerable to security attacks due to their deployment and resource *** that most large-scale WSNs follow a two-tiered architecture,we propose an efficient and denial-of-service (DoS)-resistant user authentication scheme for two-tiered *** proposed approach reduces the computational load,since it performs only simple operations,such as exclusive-OR and a one-way hash *** feature is more suitable for the resource-limited sensor nodes and mobile *** it is unnecessary for master nodes to forward login request messages to the base station,or maintain a long user *** addition,pseudonym identity is introduced to preserve user *** clever design,our proposed scheme can prevent smart card ***,security and performance analysis demonstrates the effectiveness and robustness of the proposed scheme.

关键词： User authentication User anonymity Smart card Two-tiered Wireless sensor network (WSN)

A new heuristic algorithm for the circular packing problem with equilibrium constraints

在线全文

学校读者我要写书评

暂无评论

science china(Information sciences) 2011年第8期54卷 1572-1584页

作者： LIU JingFa 1,2,LI Gang 3 & GENG HuanTong 1 1 School of computer and Software,Nanjing University of Information science & technology,Nanjing 210044,china 2 Network Information Center,Nanjing University of Information science & technology, Nanjing 210044,china 3 School of Mathematics and Physics,Nanjing University of Information science & technology,Nanjing 210044,china School of computer and Software Nanjing University of Information Science & Technology Nanjing China Network Information Center Nanjing University of Information Science & Technology Nanjing China School of Mathematics and Physics Nanjing University of Information Science & Technology Nanjing China

The circular packing problem with equilibrium constraints is an optimization problem about simplified satellite module layout design.A heuristic algorithm based on tabu search is put forward for solving this *** algorithm begins from a random initial configuration and applies the gradient method with an adaptive step length to search for the minimum energy *** jump out of the local minima and avoid the search doing repeated work,the algorithm adopts the strategy of tabu *** the process of tabu search,we improve the traditional neighboring solutions,tabu objects and the acceptance criteria of the current solution *** test two sets of benchmarks consisting of 11 representative instances from the current *** numerical results show that the proposed algorithm breaks the records in seven out of 11 instances,and obtains the optimal solutions for the other four instances.

关键词： equilibrium constraints packing problem heuristic algorithm tabu search layout optimization

Hybrid of comprehensive learning particle swarm optimization and SQP algorithm for large scale economic load dispatch optimization of power system

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Information sciences) 2010年第8期53卷 1566-1573页

作者： WANG Yu , LI Bin & YUAN Bo Department of Electronic science and technology, School of Information science and technology, University of science and technology of china, Hefei 230027, china Department of Electronic science and technology School of Information Science and Technology University of Science and Technology of China Hefei China

Economic load dispatch (ELD) is an important optimization task in power systems. In the previous works, various researchers attempted to address this problem by both mathmatical and heuristic optimization algorithms. However, there are still two practically important issues that have not attracted sufficient attention: 1) the stability of these algorithms cannot be effectively ensured; 2) the performance of these algorithms on large scale ELD optimization tasks remains to be unsatisfactory. CLPSO is an effective global optimization algorithm. To strengthen the convergence ability of CLPSO, the sequential quadratic programming (SQP) is introduced into it. This results in a new algorithm hybrid of comprehensive learning particle swarm optimization and sequential quadratic programming (SQP-CLPSO). To assess the performance of SQP-CLPSO, it is compared with several state-of-the-art evolutionary algorithms (EAs) on the classical ELD optimization problems. Experimental results show that SQP-CLPSO has very good abilities of convergence, diversity maintainence and scalability, which make it suitable for complex ELD problems.

关键词： particle swarm optimization comprehensive learning particle swarm optimization sequential quadratic programming local search power systems economic load dispatch

Dynamics and control designs for internal thermally coupled distillation columns with different purities,Part 1:Open loop dynamic behaviors

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2006年第5期16卷 346-351页

作者： ZHU Yu, LIU Xinggao and CHU Jian National Laboratory of Industrial control technology, Department of control science and Engineering, Zhejiang University, hangzhou 310027, china National Laboratory of Industrial control technology Department of Control Science and Engineering Zhejiang University Hangzhou 310027 China

The open loop dynamic behaviors of internal thermally coupled distillation column with four different purities (low-, moderate-, high- and very high-purity) are studied. These dynamic behaviors are characterized by strong asymmetric non-linearity, high sensitivity to operation conditions change and distinct inverse response. With the increase of purity, these dynamic behaviors are intensified and become more complex, which easily lead to the mismatch between linear model and plant and also change the relationship between manipulated and controlled variables.

关键词： thermal coupling inverse response non-linearity high purity asymmetric behavior.

Three Main Points in Promoting the Integral Level of Chinese Information science and technology——An Example of Stress Researches on Prosodic Words in Mandarin

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Three Main Points in Promoting the Integral Level of Chinese...