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Dynamic Characteristic Analysis and Experiment for Integral Impeller Based on Cyclic Symmetry Analysis Method

Chinese Journal of Aeronautics 2012年第5期25卷 804-810页

作者： WU Qiong ZHANG Yidu ZHANG Hongwei State Key Laboratory of Virtual Reality Technology and Systems School of Mechanical Engineering and AutomationBeihang UniversityBeijing 100191China

A cyclic symmetry analysis method is proposed for analyzing the dynamic characteristic problems of thin walled integral im- peller. Reliability and feasibility of the present method are investigated by means of simulation and experiment. The fundamental cyclic symmetry equations and the solutions of these equations are derived for the cyclic symmetry structure. The computational efficiency analysis between whole and part is performed. Comparison of results obtained by the finite element analysis （FEA） and experiment shows that the local dynamic characteristic of integral impeller has consistency with the single cyclic symmetry blade. When the integral impeller is constrained and the thin walled blade becomes a concerned object in analysis, the dynamic characteristic of integral impeller can be replaced by the cyclic symmetry blade approximately. Hence, a cyclic symmetry analy- sis method is effectively used to improve efficiency and obtain more information of parameters for dynamic characteristic of integral impellers.

关键词： dynamic characteristic cyclic symmetry impellers simulation finite element analysis blade

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A real-time collision detection between virtual and real objects based on three-dimensional tracking of hand

A real-time collision detection between virtual and real obj...

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2010 International Conference on Audio, Language and Image Processing, ICALIP 2010

作者： Li, Yan Shen, Xukun State Key Laboratory of Virtual Reality Technology and System Beihang University China

ISBN: (纸本)9781424458653

In the working environment of argument reality, users interact with virtual objects by hands. Making real-time collision detection between virtual and real objects is very essential to enhance the immersion and authenticity of the environment. In this paper, the key points of hand are marked by color block. We use a pair of common web cameras to collect images and track the points. Then the stereo vision calibration algorithm is achieved .We get hand positioning by calculating the disparity of key points between two images and restoring the three-dimensional position. At the same time, the virtual object models are divided to a binary tree and pretreated by the OBB bounding box. At last, the accurate collision detection is achieved by calculating the relative position between real hand and virtual objects real-time. ©2010 IEEE.

关键词： Binary trees

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Mechanical and biological characteristics of 3D-printed auxetic structure in bone tissue engineering

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Journal of Biomechanics 2025年 184卷 112685-112685页

作者： Geng, Xuezheng Yao, Yan Huang, Huiwen Li, Qiao Wang, Lizhen Fan, Yubo Innovation Center for Medical Engineering & Engineering Medicine Hangzhou International Innovation Institute Beihang University Hangzhou311115 China Ministry of Education Beijing Advanced Innovation Center for Biomedical Engineering School of Biological and Medical Engineering Beihang University Beijing100191 China School of Engineering Medicine Beihang University Beijing100191 China State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing100191 China

The auxetic structures are highly effective in bone implants due to their unique deformation characteristics. However, ideal tissue engineering scaffolds must possess suitable mechanical properties and biocompatibility. The biological effects of auxetic structures require further study. In this study, three types of 3D re-entrant honeycomb structures with varying angles of 75°, 90°, and 105° were designed. These structures were fabricated by stereolithography 3D printing technology. Finite element simulations and compression tests were conducted to evaluate their mechanical properties. Scaffolds were inoculated with preosteoblast MC3T3-E1 cells, and cyclic loading was applied to investigate the influence of structural and mechanical stimulation on cell arrangement and proliferation. The results demonstrated that the 75° scaffold exhibited auxetic characteristics in all compression directions and possessed anti-fracture properties. The 75° scaffold also promoted cell proliferation by structural design. Cyclic compression facilitated the nuclear translocation of YAP, further enhancing cell growth. The combination of anti-fracture properties and the promotion of cell proliferation makes auxetic structures highly promising for extensive applications. © 2025

关键词： Cell proliferation

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Stable haptic interaction using a damping model to implement a realistic tooth-cutting simulation for dental training

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virtual reality 2008年第2期12卷 99-106页

作者： Liu, Guanyang Zhang, Yuru Wang, Dangxiao Townsend, William T. State Key Lab of Virtual Reality Technology and System Beihang University Beijing China Barrett Technology Inc.

It is difficult to implement a stable and realistic haptic simulation for cutting rigid objects that is based on a damping model because of an inevitable conflict between stability and high output force. This paper presents passivity techniques to show that an excessive damping coefficient causes the output stiffness to exceed the maximum output stiffness of the haptic device, leading to instability. By analysing the damping model of a haptic dental-training simulator, we construct a relationship among the damping coefficient, position resolution, sampling frequency, human operation, and the maximum achievable device stiffness that will still maintain device stability. A method is also provided to restrict the output stiffness of the haptic device to ensure stability while enabling the realistic haptic simulation of cutting rigid objects (teeth) that is based in a damping model. Our analysis and conclusions are verified by a damping model that is constructed for a dental-training haptic display. Three types of haptic devices are used in our analysis and experiments. © Springer-Verlag London Limited 2008.

关键词： Haptic interfaces

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A method of stereo vision matching based on OpenCV

A method of stereo vision matching based on OpenCV

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2010 International Conference on Audio, Language and Image Processing, ICALIP 2010

作者： Zou, Ling Li, Yan State Key Laboratory of Virtual Reality Technology and System Beihang University China

ISBN: (纸本)9781424458653

Stereo vision is an important branch of the research area in computer vision. Among the techniques of stereo vision, binocular stereo vision which is based on processing two images remains a research hotspot. Binocular stereo vision directly simulates the manner of human eyes observing one scene from two different viewpoints. By using the principle of triangulation, the disparities of a number of 3D points mapped to pixels in two images are computed. Then the visual information of depth is also recovered. The object surface shape can be acquired using these disparities. In this paper, a pair of common web cameras is used to collect images. Based on OpenCV, the calibration algorithm of stereo vision is achieved. Stereo rectify and stereo matching algorithm are also rapidly and efficiently implemented. Finally, the depth information of object is obtained. ©2010 IEEE.

关键词： Stereo vision

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Web-based mixed reality video fusion with remote rendering

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virtual reality & Intelligent Hardware 2023年第2期5卷 188-199页

作者： Qiang ZHOU Zhong ZHOU State Key Laboratory of Virtual Reality Technology and Systems Beihang UniversityBeijing 100191China

Background Mixed reality(MR)video fusion systems merge video imagery with 3D scenes to make the scene more realistic and help users understand the video content and temporal–spatial correlation between them,reducing the user′s cognitive *** video fusion are used in various applications;however,video fusion systems require powerful client machines because video streaming delivery,stitching,and rendering are computationally ***,huge bandwidth usage is another critical factor that affects the scalability of video-fusion *** Our framework proposes a fusion method for dynamically projecting video images into 3D models as *** Several experiments on different metrics demonstrate the effectiveness of the proposed *** The framework proposed in this study can overcome client limitations by utilizing remote ***,the framework we built is based on ***,the user can test the MR video fusion system with a laptop or tablet without installing any additional plug-ins or application programs.

关键词： Mixed reality Video fusion WebRTC Remote rendering

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Avian contrast sensitivity inspired contour detector for unmanned aerial vehicle landing

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Science China(Technological Sciences) 2017年第12期60卷 1958-1965页

作者： DENG YiMin DUAN HaiBin State Key Laboratory of Virtual Reality Technology and Systems School of Automation Science and Electrical Engineering Beihang University Beijing 100191 China

Runway detection is a demanding task for autonomous landing of unmanned aerial vehicles. Inspired by the attenuation effect and surround suppression mechanism, a novel biologically computational method based on the avian contrast sensitivity is proposed for runway contour detection. For the noisy stimuli, deniosed responses of the biologically inspired Gabor energy operator are generalized followed by the denoising layer and the multiresolution fusion layer. Moreover, two factors such as contour effect and texture suppression are considered in the contrast sensitivity based surround inhibition. Different from traditional detectors, which do not distinguish between contours and texture edges, the proposed method can respond strongly to contours and suppress the texture information. Applying the contrast sensitivity inspired detector to noisy runway scenes yields effective contours, while the non-meaningful texture elements are removed dramatically at the same time. Besides the superior performance over traditional detectors, the proposed method is capable to provide insight into the attenuation effect of the avian contrast sensitivity function and has potential applications in computer vision and pattern recognition.

关键词： contrast sensitivity function surround suppression contour perception unmanned aerial vehicle landing

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Multiplane-based Cross-view Interaction Mechanism for Robust Light Field Angular Super-Resolution

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IEEE Transactions on Visualization and Computer Graphics 2025年 PP卷 PP页

作者： Chen, Rongshan Sheng, Hao Yang, Da Cong, Ruixuan Cui, Zhenglong Wang, Sizhe Ke, Wei Beihang University Data Science and Intelligent Computing Laboratory Hangzhou International Innovation Institute Zhejiang Hangzhou311115 China Beihang University State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beijing100191 China Macao Polytechnic University Faculty of Applied Sciences 999078 China Macao Polytechnic University School of Applied Sciences 999078 China

Dense sampling of the light field (LF) is essential for various applications, such as virtual reality. However, the collection process is prohibitively expensive due to technological limitations in imaging. Synthesizing novel views from sparse LF data, known as LF Angular Super-Resolution (LFASR), offers an effective solution to this problem. Accurate cross-view interaction is crucial for this task, given the complementary information between LF views. Previous methods, however, suffer from limited reconstruction quality due to inefficient view interaction. To address this, we propose a Multiplane-based Cross-view Interaction Mechanism (MCIM) for robust LFASR. Extensive comparisons with state-of-the-art methods demonstrate that our method achieves superior performance, both visually and quantitatively. Specifically, Drawing inspiration from MultiPlane Images (MPI) in scene modeling, our mechanism incorporates a novel Multiplane Feature Fusion (MPFF) strategy. This strategy facilitates fast and accurate cross-view interaction, enhancing the network's robustness to scene geometry and suitability for different-baseline LF scenes. Furthermore, to address information redundancy in multiplanes, we leverage the transparency property of MPI and devise a plane selection strategy. Finally, we propose CSTNet, a Cross-Shaped Transformer-based network for LFASR, which employs a cross-shaped self-attention mechanism to enable low-cost training and inference. Experimental results on various angular super-resolution tasks validate that our network achieves state-of-the-art performance on both synthetic and real-world LF scenes. © 1995-2012 IEEE.

关键词： virtual reality

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Stable Flocking of Multiple Agents Based on Molecular Potential Field and Distributed Receding Horizon Control

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Chinese Physics Letters 2011年第4期28卷 47-50页

作者： ZHANG Yun-Peng DUAN Hai-Bin ZHANG Xiang-Yin State Key Laboratory of Virtual Reality Technology and Systems Beihang UniversityBeijing 100191 Science and Technology on Aircraft Control Laboratory Beihang UniversityBeijing 100191

A novel distributed control scheme to generate stable flocking motion for a group of agents is *** this control scheme,a molecular potential field model is applied as the potential field function because of its smoothness and unique *** approach of distributed receding horizon control is adopted to drive each agent to find its optimal control input to lower its potential at every *** results show that this proposed control scheme can ensure that all agents eventually converge to a stable flocking formation with a common velocity and the collisions can also be avoided at the same time.

关键词： Agents agent scheme

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A object surface reflectance data modeling method for isotropic opaque materials

A object surface reflectance data modeling method for isotro...

引用

International Congress on Image and Signal Processing

作者： Zou, Ling Qi, Yue State Key Laboratory of Virtual Reality Technology and System Beihang University Beijing China

ISBN: (纸本)9781424465149

In computer graphics research, the acquisition and modeling of 3D information of real object and the property of surface reflectance is the base of realistic rendering. This paper proposes a robust data acquisition method for surface reflectance and 3D geometric information data. Based on the accurate data acquisition and processing of the initial data, this paper implements a novel method to render realistic surface. We use the acquisition of real reflectance data to generate the BRDF sampling values of real object surface. In order to attain parametric BRDF expression, and complete the surface reflectance modeling, we use sampling values to fit Ward model. Finally, surface realistic rendering is achieved and the experiments verify the effectiveness and verisimilitude of this method. ©2010 IEEE.

关键词： Reflection

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