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2011 IEEE International Conference on Robotics and Automation(2011年IEEE世界机器人与自动化大会 ICRA 2011)

作者： Hao Li Yuru Zhang Jian S. Dai State Key Laboratory of Virtual Reality Technology and System Beihang University Beijing 100191 C Robotics Research Center Department of Mechanical Engineering Kings College London University of

Performance of a parallel manipulator heavily relies on its position/orientation resolution. Without a good resolution the manipulator is difficult to achieve a high stiffness. Therefore how to obtain the required resolution is a basic issue to design a parallel manipulator. This paper presents a method to solve the problem. Firstly, the mathematical definition of the position/orientation resolution is given. Then we discuss how to calculate them using Rayleigh quotient. And the design optimization problem is formulated. Fundamental concepts of the method are illustrated through a 3-RRR planar parallel manipulator. The design process to achieve an optimized task space of the required pose resolution is also demonstrated in the example.

关键词： Manipulators Haptic interfaces Joints Optimization Kinematics Jacobian matrices Conferences

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Guangxue Jingmi Gongcheng/Optics and Precision engineering 2015年第4期23卷 1138-1145页

作者： Zhao, Jun-Li Wu, Zhong-Ke Liu, Cui-Ting Duan, Fu-Qing Zhou, Ming-Quan Cao, Jia-Yi College of Software and Technology Qingdao University Qingdao266071 China Engineering Research Center of Virtual Reality and Applications of the Ministry of Education College of Information Science and Technology Beijing Normal University Beijing100875 China College of Traditional Chinese Medicine Tianjin University of Traditional Chinese Medicine Tianjin300193 China

This paper focuses on the 3D facial similarity comparison by using a computer automatically. A new 3D facial similarity comparison method based on a geodesics in a shape space was proposed. In this method, 3D facial surface was approximately represented by a set of geodesics and the corresponding geodesics between two facial models were compared by a elastic metric in the shape space, in which the similarity between two faces could be measured by the average geodesic distance of all corresponding geodesics. 3D facial similarity experiments were perfomed on 28 facial models of 14 persons in Gavadb database and the recognition rate is above 92.86%, which indicates that this method recognizes the facial models of the same person from different person's facial models. In addition, 3D facial similarity experiments on different person's facial models were implemented. The experimental results show that the similarity values computed by proposed method consist with that of people's subjective judgment. These results reflect that the proposed method can measure the similarity of 3D faces well. ©, 2015, Chinese Academy of Sciences. All right reserved.

关键词： Computer vision

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Additive Manufacturing of Large-scale Metal Mesh with Core-shell Composite Structure for Transparent Electromagnetic Shielding/glass Heater

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Chinese Journal of Mechanical engineering(Additive Manufacturing Frontiers) 2023年第3期2卷 29-38页

作者： Yuping Tai Junyi Zhou Xiaoyang Zhu Houchao Zhang Hongke Li Zhenghao Li Rui Wang Fan Zhang Guangming Zhang Chaohong Liu Hongbo Lan Shandong Engineering Research Center for Additive Manufacturing Qingdao University of TechnologyQingdao266520China Key Laboratory of Additive Manufacturing and Applications in Universities of Shandong Qingdao University of TechnologyQingdao266520China Qingdao Virtual Reality Research Institute Co. Ltd.Qingdao266100China

Transparent electromagnetic(EM)shielding glass with a metal mesh has significant potential for application in different fields of EM radiation and anti-EM interference light-transmitting observation *** particular,a transparent EM-shielding glass with a large-aspect-ratio metal mesh can effectively alleviate the contradictory problems of shielding effectiveness and light-transmission performance ***,the fabrication of high-aspect-ratio metal meshes on glass substrates has problems such as high cost,complex processes,low efficiency,small area,and easy damage issues,which limit their application in the field of high-performance,transparent EM-shielding ***,this paper proposes a composite additive manufacturing process based on electric-field-driven microjet 3D printing and *** fabricating metal meshes with an Ag-Cu core-shell structure on a glass substrate,EM-shielding glass with high shielding efficiency and light transmission can be manufactured without increasing the aspect ratio of the metal *** prepared Ag-Cu composite metal mesh has excellent optoelectronic properties(period 250𝜇m,line width 10𝜇m,90.1%transmission at 550 nm visible light,square resistance 0.21Ω/sq),efficient electrothermal effect(3 V DC voltage can reach 189°C steady-state temperature),stable EM-shielding effectiveness(average shielding effectiveness 23 dB at X-band),and acceptable mechanical and environmental stability(less than 3%change in square resistance after 150-times adhesion test and less than 6%and 0.6%change in resistance after 72 h in acid and alkali environments,respectively).This method provides a new solution for the mass production of high-performance large-area transparent electric heating/EM-shielding glass.

关键词： Transparent electromagnetic interference (EMI)shielding Composite metal mesh Shielding efficiency Optical transmittance Additive manufacturing

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Influence of meniscal attachments placement on articular stress deterioration

Influence of meniscal attachments placement on articular str...

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World Congress on Medical Physics and Biomedical engineering

作者： Yao, J. Niu, W.X. Cheung, J.T. Zhang, M. Fan, Y.B. Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education School of Biological Science and Medical Engineering Beihang University No.37 Xueyuan Road 100191 Beijing China Li Ning Sports Science Research Center Beijing China Department of Health Technology and Informatics Hong Kong Polytechnic University Kowloon Hong Kong State Key Laboratory of Virtual Reality Technology and Systems Beihang University 100191 Beijing China

ISBN: (纸本)9783642293047

Meniscal attachments provide constraint for meniscus and contribute to knee stability. However, the influence of attachments placement on articular mechanical environment remains unclear. The present study aims to characterize the stress deterioration caused by abnormal attachment locations. Different placement of medial meniscal attachments were analyzed with a three-dimensional (3D) finite element (FE) model of knee joint. The articular stress distribution under compressive loadings indicates that abnormal placement of medial meniscal attachments could cause stress deterioration in meniscus and tibia plateau, which may increase the risk of OA. The influence of PMMA relocation was more severe than that of AMMA. The anterior displacement of both AMMA and PMMA could decrease the tibial contact area and therefore weaken the meniscal function of loading transmission. The present study provides an insight into the biomechanical character of meniscal attachments and may help improving the meniscal transplantation in the future. © 2013 Springer-Verlag.

关键词： Deterioration

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Left ventricle segmentation with mixture of Gaussian active contours

Left ventricle segmentation with mixture of Gaussian active ...

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IEEE International Symposium on Biomedical Imaging

作者： Xiaoxu Wang Qingmao Hu Pheng Ann Heng Human Computer Interaction Centre Shenzhen Institute of Advanced Technology Shenzhen Guangdong China Virtual Reality Visualization and Imaging Research Centre Department of Computer Science and Engineering Chinese University of Hong Kong Sha Tin New Territories Hong Kong China

Cine MRI is an imaging technique for visualizing the left ventricle wall motion in a heart beating cycle. The paper proposed a method to semi-automatically segment the left ventricle (LV) boundaries from a stack of cine MRI and build a LV mesh. The different intensities in the MRI are modeled with the mixture of Gaussian method. The thresholds between them are semi-automatically determined by K-means initialization and the expectation maximization (EM) method. The spatial constrain is added into the model with active contour models, which fit explicit contours on the boundary of the area of interest. We propose a marching cube alike initialization method of the active contour models. A 3D mesh is built from a stack of contours and smoothed afterwards. Stroke volume, myocardium mass and ejection function can be estimated from the LV boundary mesh and the endocardium mesh.

关键词： Magnetic resonance imaging Active contours Image segmentation Cavity resonators Image reconstruction Myocardium

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Comparative visualization of vector field ensembles based on longest common subsequence

Comparative visualization of vector field ensembles based on...

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Pacific (formerly Asia-Pacific APVIS) visualization Symposium

作者： Richen Liu Hanqi Guo Jiang Zhang Xiaoru Yuan Key Laboratory of Machine Perception (Ministry of Education) Peking University Mathematics and Computer Science Division Argonne National Laboratory Beijing Engineering Technology Research Center of Virtual Simulation and Visualization Peking University

We propose a longest common subsequence (LCSS)-based approach to compute the distance among vector field ensembles. By measuring how many common blocks the ensemble pathlines pass through, the LCSS distance defines the similarity among vector field ensembles by counting the number of shared domain data blocks. Compared with traditional methods (e.g., pointwise Euclidean distance or dynamic time warping distance), the proposed approach is robust to outliers, missing data, and the sampling rate of the pathline timesteps. Taking advantage of smaller and reusable intermediate output, visualization based on the proposed LCSS approach reveals temporal trends in the data at low storage cost and avoids tracing pathlines repeatedly. We evaluate our method on both synthetic data and simulation data, demonstrating the robustness of the proposed approach.

关键词： Data models Data visualization Time series analysis Uncertainty Computational modeling Shape Measurement

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virtual Worlds as a Tool for Enterprise Services

Virtual Worlds as a Tool for Enterprise Services

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Consumer Communications and Networking Conference, CCNC IEEE

作者： Sameer Vijaykar Muthukkumar S. Kadavasal Krishna K. Dhara Xiaotao Wu Venkatesh Krishnaswamy Department of Computer Science and Engineering Indian Institute of Technology Mumbai India Virtual Reality Applications Center Iowa State University Ames IA USA Avaya Laboratories Research Lincroft NJ USA

Online virtual worlds offer exciting new opportunities for enterprises or businesses. To exploit these opportunities enterprises need to find a way to integrate virtual world services with their real-world services, and to exploit virtual worlds rich collaboration environment to offer new or enhanced services. However, there are many challenges to realizing these goals, such as resolving virtual and real identifications, controlling communication sessions between real and virtual world entities, and managing resources in both worlds. In this paper, we study these issues and propose a framework for integrating virtual worlds into enterprise service work flow. We implemented a customer service in a VW contact center that is integrated with corresponding enterprise services. We also present a novel mechanism in virtual worlds that allow users to bring their own resources, along with the contact center resources, and share the resources with other customers or agents to resolve customer issues. Further, we present experiences from our prototype.

关键词： virtual reality Data processing Sensor systems Data mining Laboratories Sensor systems and applications Hardware virtual environment Noise measurement Time measurement

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Efficient unsteady flow visualization with high-order access dependencies

Efficient unsteady flow visualization with high-order access...

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Pacific (formerly Asia-Pacific APVIS) visualization Symposium

作者： Jiang Zhang Hanqi Guo Xiaoru Yuan Key Laboratory of Machine Perception (Ministry of Education) Peking University Mathematics and Computer Science Division Argonne National Laboratory Beijing Engineering Technology Research Center of Virtual Simulation and Visualization Peking University

ISBN: (纸本)9781509014521

We present a novel high-order access dependencies-based model for efficient pathline computation in unsteady flow visualization. By taking longer access sequences into account to model more sophisticated data access patterns in particle tracing, our method greatly improves the accuracy and reliability in data access prediction. In our work, high-order access dependencies are calculated by tracing uniformly seeded pathlines in both forward and backward directions in a preprocessing stage. The effectiveness of our approach is demonstrated through a parallel particle tracing framework with high-order data prefetching. Results show that our method achieves higher data locality and hence improves the efficiency of pathline computation.

关键词： Data visualization Prefetching Markov processes Data models Computational modeling Mathematical model Reliability

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Real time motion tracking system for interactive entertainment applications

Real time motion tracking system for interactive entertainme...

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Proceedings AESF/EPA Conference for Environmental Excellence

作者： Kim, Namgyu Chung, Jaeyong Kim, Gerard Jounghyung Park, Chan-Mo Virtual Reality Laboratory Dept. of Comp. Sci. and Engineering Pohang Univ. of Sci. and Technology San 31 Hyoja-dong Nam-gu Pohang Kyung-buk 790-784 Korea Republic of VR Research Center Electronics and Telecom. Res. Inst. 161 Gajeong-Dong Yuseong-Gu Deaejeon 305-350 Korea Republic of

ISBN: (纸本)7506255715

"Looking human through a camera" is a potentially powerful technique to facilitate human-computer interaction. Many 2D/3D visual human tracking techniques have been introduced in area of computer vision, and applied to smart surveillance, motion analysis, interactive computer graphics and virtual reality applications. For applications emphasizing real time interactivity, the visual tracking techniques need to be fast, robust, and preferably run on an inexpensive hardware system. In this paper, we present a relatively inexpensive (e.g. run on a high-end PC) but reasonably robust real time motion-tracking system based on a simple 2D color object segmentation and recognition algorithm. Users grasp color objects for achieving more exact tracking performance on their hands and make predefined motion gestures continuously. Through object segmentation processing based on color information, 2D positions of the objects are computed. And then, a motion gesture corresponding on these 2D position trajectories is found by a simple correlation-based matching algorithm. Also, we demonstrate this system by applying it to a popular interactive entertainment (e.g. TETRIS).

关键词： Computer simulation

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FluidPlaying: Efficient Adaptive Simulation for Highly Dynamic Fluid

FluidPlaying: Efficient Adaptive Simulation for Highly Dynam...

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virtual reality and 3D User Interfaces Abstracts and Workshops (VRW), IEEE Conference on

作者： Sinuo Liu Xiaojuan Ban Sheng Li Haokai Zeng Xiaokun Wang Yanrui Xu Fei Zhu Guoping Wang Graphics & Interaction Lab National Biomedical Imaging Center School of Computer Science Peking University School of Intelligence Science and Technology University of Science and Technology Beijing Beijing Engineering Technology Research Center of Virtual Simulation and Visualization Peking University Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai)

We present FliudPlaying, a novel dynamic level-based spatially adaptive simulation method that can handle highly dynamic fluid efficiently. To capture the subtle detail of the fluid surface, the high-resolution simulation is performed not only at the free surface but also at those regions with high vorticity levels and velocity difference levels. To minimize the density error, an online optimization scheme is used when increasing the resolution by particle splitting. We also proposed a neighbor-based splash enhancement to compensate for the loss of dynamic details. Compared with the high-resolution simulation baseline, our method can achieve over 3× speedups while consuming only less than 10% computational resources. Furthermore, our method can make up for the loss of high-frequency details caused by the spatial adaptation, and provide more realistic dynamics in particle-based fluid simulation.

关键词： Solid modeling Adaptation models Three-dimensional displays Fluid dynamics Computational modeling Conferences virtual reality

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