11 resultados para Panoramic projections. Virtual Environments. Navigation in 3D environments. Virtual Reality

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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By using a correction factor of d electron effects on bond, PV theory is applied to the calculation of chemical bond;parameters of d transition-metal compounds. Racah parameters and Mossbauer isomer shifts are calculated, and the results are agreement with the experimental values.

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利用虚拟现实技术虚拟出月球机器人在月面上的作业环境和作业过程,是提高机器人作业的安全系数和工作效率的一条有效途径。在3D重建得到的虚拟月面环境中,如果采用通常的单纯基于运动学(或者动力学)模型的仿真方法,对机器人的作业和运动进行虚拟,那么机器人与地形交互的过程中容易产生接触偏差。而且,随着仿真时间的推进,这种接触偏差会逐渐积累并不断增大,进而严重影响仿真测试的精度和效果。为了消除月球机器人仿真中的轮地交互误差,在分析误差来源的基础上,提出了基于运动学优化的解决方法。最后利用实际的虚拟现实仿真系统,验证了所提出方法的有效性。

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提出了一种基于扩展集员估计(ESMF)的多机器人协作观测方法,该方法将多机器人之间的观测数据融合过程嵌入到估计过程当中,从而减少了数据处理的过程,增强了算法的快速性。同时,这种方法在实现协作观测时只需要协作机器人传送观测信息而不是整个的估计信息,因此可以减轻多机器人系统的通信负担。除此之外,该方法在融合多机器人的观测数据过程中避免了多余的近似过程,增加了观测的准确性。最后,给出了三维环境下的仿真结果,验证了方法的可行性。

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针对实时序列图像多目标识别问题提出了一种快速图像处理方法。该方法依据一定的先验知识和准则,对复杂背景图像进行窗口化,对每一个窗口独立进行自适应快速中值滤波,及基于局部图像灰度信息的自适应重新量化和最大熵分割处理,实现了对全景视场内预定目标的快速准确提取和识别。为动态环境中多目标条件下移动机器人的视觉定位、导航和目标跟踪所需图像处理技术提供了一种新的方法。

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This paper summarizes the recent development of dynamic fracture in China. The review covers analytical and numerical results on elastodynamic crack fields in 3D and layered media; experimental and theoretical research on dynamic mechanical properties of rocks and advanced materials; transient effects on ideally plastic crack-tip fields when the inertia forces are not negligible.

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The origin of beam disparity in emittance and betatron oscillation orbits, in and out of the polarization plane of the drive laser of laser-plasma accelerators, is explained in terms of betatron oscillations driven by the laser field. As trapped electrons accelerate, they move forward and interact with the laser pulse. For the bubble regime, a simple model is presented to describe this interaction in terms of a harmonic oscillator with a driving force from the laser and a restoring force from the plasma wake field. The resulting beam oscillations in the polarization plane, with period approximately the wavelength of the driving laser, increase emittance in that plane and cause microbunching of the beam. These effects are observed directly in 3D particle-in-cell simulations.

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We report a method for the selective introduction of fluorescent Ag nanoclusters in glass. Extinction and photoluminescence spectra show that a fraction of the Ag atoms are generated through femtosecond laser induced multiphoton reduction and then aggregate to form Ag nanoclusters after heat treatment. Red luminescence from the irradiated region is observed under blue or green laser excitation. The fluorescence can be attributed to interband transitions within Ag nanoclusters. This method provides a novel route to fabricate fluorescent nanomaterials in 3D transparent materials. (c) 2007 Elsevier B.V. All rights reserved.

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本文提出一种水下 ROV(Remotely Operated Vehicles)的模糊导航方法和基于该方法的控制器结构 .通常由于水下环境光照不足或是水质混浊 ,很难依赖摄像机准确地为 ROV导航 ,引导 ROV到达预定目标 ,尤其是工作空间存在障碍物时 ,ROV很可能发生碰撞 .文中提出的模糊控制方法 ,将 ROV在 3D空间运动的状态、局部环境信息以及导航规划数据表示为多重模糊条件 ,然后结合 ROV的导航特点 ,建立了一个三级模糊控制器 ,该控制器使用同一种控制模式完成 ROV有障碍和无障碍的导航任务 .仿真实验结果验证了所提出方法的有效性

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Study of 3D visualization technology of engineering geology and its application to engineering is a cross subject which includes geosciences, computer, software and information technology. Being an important part of the secondary theme of National Basic Research Program of China (973 Program) whose name is Study of Multi-Scale Structure and Occurrence Environment of Complicated Geological Engineering Mass(No.2002CB412701), the dissertation involves the studies of key problems of 3D geological modeling, integrated applications of multi-format geological data, effective modeling methods of complex approximately layered geological mass as well as applications of 3D virtual reality information management technology.The main research findings are listed below:Integrated application method of multi-format geological data is proposed,which has solved the integrated application of drill holes, engineering geology plandrawings, sectional drawings and cutting drawings as well as exploratory trenchsketch. Its application can provide as more as possible fundamental data for 3Dgeological modeling.A 3D surface construction method combined Laplace interpolation points withoriginal points is proposed, so the deformation of 3D model and the crossing error ofupper and lower surface of model resulted from lack of data when constructing alaminated stratum can be eliminated.3D modeling method of approximately layered geological mass is proposed,which has solved the problems of general modeling method based on the sections or points and faces when constructing terrain and concordant strata.The 3D geological model of VII dam site of Xiangjiaba hydropower stationhas been constructed. The applications of 3D geological model to the auto-plotting ofsectional drawing and the converting of numerical analysis model are also discussed.3D virtual reality information integrated platform is developed, whose mostimportant character is that it is a software platform having the functions of 3D virtualreality flying and multi-format data management simultaneously. Therefore, theplatform can load different 3D model so as to satisfy the different engineeringdemands.The relics of Aigong Cave of Longyou Stone Caves are recovered. Thereinforcement plans of 1# and 2# cave in phoenix hill also be expressed. The intuitiveexpression provided decision makers and designers a very good environment.The basic framework and specific functions of 3D geological informationsystem are proposed.The main research findings in the dissertation have been successfully applied to some important engineering such as Xiangjiaba hydropower station, a military airport and Longyou Stone Caves etc.

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Interface has been becoming a more significant element today which influences the development of shopping on-line greatly. But in practice the attention arisen from society and study made are quite inadequate. Under this circumstance, I focus my study on the purpose of improving understanding of the engineering psychological factors, which definitely will play a crucial role in shopping on-line representation in future, and of the relations between them through the following experimental research. I hope it can give a basic reference to the practical application of shopping on-line representation pattern and continuous study. In current thesis, an analysis was made on the basis of engineering psychology principles from three aspects, i.e. person (users), task and information environment. It was considered that system overview and information behavior model would have great impact on the activities of users on the web and that representation pattern of information system would affect the forming of system overview and behavior pattern and then further after the performances of users in information system. Based on above-mentioned statement, a three-dimensional conceptual model was presented which demonstrates the relations between the crucial factors, which are media representation pattern, system hierarchy and objects in information unit. Thereafter, eight study hypothesis, which are about engineering psychological factors of virtual reality (VR) representation in shopping on-line system, was taken out and four experiments were followed up to testify the hypothesis. -In experiment one, a research was made to study how the three kinds of single media representation pattern influence the forming of system overview and information behavior from the point view of task performance, operating error, overall satisfactory and mental workload etc. -In experiment two, a study of how the combined media representation pattern of system hierarchy influences users' behavior was carried out. -In experiment three, a study of the hierarchy structure feature of VR representation pattern and the tendency of its width and depth to the effects of system behavior was made. -In experiment four, a study of the location relations between different parties in VR scene (information unit) was made. The result is as follows: -During structure dimensional state: Width-increasing caused more damage to the speed of users than depth-increasing in VR representation pattern. Although the performance of subjects was quite slow in wider environment, yet the percentage rate of causing errors was in lowest level. -During hierarchy representation pattern: 1. Between the representation patterns of the three media, no significant differences was found in terms of the speed of fulfilling the task, error rate, satisfactory, mental workload etc. But the pattern with figure- aided gained the worst results on all of these aspects. 2. During primary stage of the task and the first level of the hierarchy, the speed of subjects' performance in VR pattern was slower than that in text pattern. While with developing of the task and going deeper level of the hierarchy, the speed of users' performance in VR representation pattern reached to the highest level. 3. Effects in VR representation pattern was better than that in text pattern in higher level of the system. The representation pattern in highest level has greatest impact on the performance of the system behavior, whereas results of the only VR representation in the middle part of hierarchy would be worst. 4. Activity error in single media representation pattern was more than that in combined media representation pattern. 5. Individual differences among subjects had effects on the representation pattern of the system. During VR environment, behavior tendency of party A had a significant negative correlation to the quantities of errors. -In VR-scene representation: Physical-distance and flash influenced the subjects' task performance greatly, while psychological-distance has no outstanding impact. Subjects' accurate rate of performing increased if objects with same relation were in the same structure position, in the state of close psychological-distance or if the object target flashed (not reliable). Although the article limits the topic only on the present-existing questions and analysis of shopping-on-line, as a matter of fact, it can also apply for other relevant purposes on the web. While the study of this article only gives its emphasis on the researching-task with definite goal, making no consideration of other task conditions and their relations with other navigation tools. So I hope it lay a good start to make continuous research in this areas.