Virtual reality （VR） is a scientific method and technology created during the exploration of the nature by human beings to understand, simulate, and better adapt and use the nature. Based on the analysis on the whol...Virtual reality （VR） is a scientific method and technology created during the exploration of the nature by human beings to understand, simulate, and better adapt and use the nature. Based on the analysis on the whole process of VR, this paper presents different categories of VR problems and a type of theoretical expression, and abstracts three kinds of scientific and technical problems in VR field. On the basis of foresaid content, this paper also studies current major research objectives, research results and development trend of VR in the aspects of VR modeling method, VR representation technology, human-machine interaction and devices, VR development suites and supporting infrastructure, as well as VR applications. Finally, several theoretical and technical problems that need to be further studied and solved are addressed.展开更多
Traditional methods of discovering new materials,such as the empirical trial and error method and the density functional theory(DFT)-based method,are unable to keep pace with the development of materials science today...Traditional methods of discovering new materials,such as the empirical trial and error method and the density functional theory(DFT)-based method,are unable to keep pace with the development of materials science today due to their long development cycles,low efficiency,and high costs.Accordingly,due to its low computational cost and short development cycle,machine learning is coupled with powerful data processing and high prediction performance and is being widely used in material detection,material analysis,and material design.In this article,we discuss the basic operational procedures in analyzing material properties via machine learning,summarize recent applications of machine learning algorithms to several mature fields in materials science,and discuss the improvements that are required for wide-ranging application.展开更多
The compliance modeling and rigidity performance evaluation for the lower mobility parallel manipulators are still to be remained as two overwhelming challenges in the stage of conceptual design due to their geometric...The compliance modeling and rigidity performance evaluation for the lower mobility parallel manipulators are still to be remained as two overwhelming challenges in the stage of conceptual design due to their geometric complexities. By using the screw theory, this paper explores the compliance modeling and eigencompliance evaluation of a newly patented 1T2R spindle head whose topological architecture is a 3-RPS parallel mechanism. The kinematic definitions and inverse position analysis are briefly addressed in the first place to provide necessary information for compliance modeling. By considering the 3-RPS parallel kinematic machine（PKM） as a typical compliant parallel device, whose three limb assemblages have bending, extending and torsional deflections, an analytical compliance model for the spindle head is established with screw theory and the analytical stiffness matrix of the platform is formulated. Based on the eigenscrew decomposition, the eigencompliance and corresponding eigenscrews are analyzed and the platform＇s compliance properties are physically interpreted as the suspension of six screw springs. The distributions of stiffness constants of the six screw springs throughout the workspace are predicted in a quick manner with a piece-by-piece calculation algorithm. The numerical simulation reveals a strong dependency of platform＇s compliance on its configuration in that they are axially symmetric due to structural features. At the last stage, the effects of some design variables such as structural, configurational and dimensional parameters on system rigidity characteristics are investigated with the purpose of providing useful information for the structural design and performance improvement of the PKM. Compared with previous efforts in compliance analysis of PKMs, the present methodology is more intuitive and universal thus can be easily applied to evaluate the overall rigidity performance of other PKMs with high efficiency.展开更多
基金Supported by the National Basic Research Program of China (Grant No. 2009CB320805)the National Natural Science Foundation of China(Grant Nos. 60533070, 60503066)the National High-Tech Research & Development Program of China (Grant Nos. 2006AA01Z333,2006AA01Z311)
文摘Virtual reality （VR） is a scientific method and technology created during the exploration of the nature by human beings to understand, simulate, and better adapt and use the nature. Based on the analysis on the whole process of VR, this paper presents different categories of VR problems and a type of theoretical expression, and abstracts three kinds of scientific and technical problems in VR field. On the basis of foresaid content, this paper also studies current major research objectives, research results and development trend of VR in the aspects of VR modeling method, VR representation technology, human-machine interaction and devices, VR development suites and supporting infrastructure, as well as VR applications. Finally, several theoretical and technical problems that need to be further studied and solved are addressed.
基金funded by China Postdoctoral Science Foundation(no.2017M620694)National Postdoctoral Program for Innovative Talents(BX201700040)+3 种基金supported by the National Natural Science Foundation of China(grant nos.61622406 and 61571415)the National Key Research and Development Program of China(grant nos.2017YFA0207500 and 2016YFB0700700)the Strategic Priority Research Program of Chinese Academy of Sciences(grant no.XDB30000000)Beijing Academy of Quantum Information Sciences(grant no.Y18G04).
文摘Traditional methods of discovering new materials,such as the empirical trial and error method and the density functional theory(DFT)-based method,are unable to keep pace with the development of materials science today due to their long development cycles,low efficiency,and high costs.Accordingly,due to its low computational cost and short development cycle,machine learning is coupled with powerful data processing and high prediction performance and is being widely used in material detection,material analysis,and material design.In this article,we discuss the basic operational procedures in analyzing material properties via machine learning,summarize recent applications of machine learning algorithms to several mature fields in materials science,and discuss the improvements that are required for wide-ranging application.
基金Supported by National Natural Science Foundation of China(Grant No.51375013)Anhui Provincial Natural Science Foundation of China(Grant No.1208085ME64)Open Research Fund of Key Laboratory of High Performance Complex Manufacturing,Central South University(Grant No.Kfkt2013-12)
文摘The compliance modeling and rigidity performance evaluation for the lower mobility parallel manipulators are still to be remained as two overwhelming challenges in the stage of conceptual design due to their geometric complexities. By using the screw theory, this paper explores the compliance modeling and eigencompliance evaluation of a newly patented 1T2R spindle head whose topological architecture is a 3-RPS parallel mechanism. The kinematic definitions and inverse position analysis are briefly addressed in the first place to provide necessary information for compliance modeling. By considering the 3-RPS parallel kinematic machine（PKM） as a typical compliant parallel device, whose three limb assemblages have bending, extending and torsional deflections, an analytical compliance model for the spindle head is established with screw theory and the analytical stiffness matrix of the platform is formulated. Based on the eigenscrew decomposition, the eigencompliance and corresponding eigenscrews are analyzed and the platform＇s compliance properties are physically interpreted as the suspension of six screw springs. The distributions of stiffness constants of the six screw springs throughout the workspace are predicted in a quick manner with a piece-by-piece calculation algorithm. The numerical simulation reveals a strong dependency of platform＇s compliance on its configuration in that they are axially symmetric due to structural features. At the last stage, the effects of some design variables such as structural, configurational and dimensional parameters on system rigidity characteristics are investigated with the purpose of providing useful information for the structural design and performance improvement of the PKM. Compared with previous efforts in compliance analysis of PKMs, the present methodology is more intuitive and universal thus can be easily applied to evaluate the overall rigidity performance of other PKMs with high efficiency.
