Multi-fold technology is widely applied in seismic exploration as a method of enhancing useful signals and suppressing noise interference to greatly increase the signal to noise ratio （S/N）. The authors introduce it...Multi-fold technology is widely applied in seismic exploration as a method of enhancing useful signals and suppressing noise interference to greatly increase the signal to noise ratio （S/N）. The authors introduce it to ground-penetrating radar （GPR） surveys and compare the experimental results to the conventional profiling method to demonstrate the feasibility and advantages of the technique for GPR exploration. Based on the experimental data, the authors summarize the GPR wave propagation rules and the parameters of multi- fold acquisition and processing. It is proven to be a useful attempt to enrich the GPR survey technology.展开更多
An invisibility cloak that can hide an arbitrary object external to the cloak itself has not been devised before.In this Letter,we introduce a novel way to design a remote cloaking device that makes any object located...An invisibility cloak that can hide an arbitrary object external to the cloak itself has not been devised before.In this Letter,we introduce a novel way to design a remote cloaking device that makes any object located at a certain distance invisible.This is accomplished using multi-folded transformation optics to remotely generate a hidden region around the object that no field can penetrate and that does not disturb the far-field scattering electromagnetic field.As a result,any object in the hidden region can stay in position or move freely within that region and remain invisible.Our idea is further extended in order to design a remote illusion optics that can transform any arbitrary object into another one.Unlike other cloaking methods,this method would require no knowledge of the details of the object itself.The proposed multi-folded transformation optics will be crucial in the design of remote devices in a variety of contexts.展开更多
针对复杂非结构化环境下移动机器人的折展能力与多模式适应性不足的问题,提出了一种由可变径平台和4-URU并联机构组成的可变径多模式移动并联机器人。首先,基于凸轮机构的特性设计了由多根径向伸缩杆组成的可变径平台,并分析了其结构与...针对复杂非结构化环境下移动机器人的折展能力与多模式适应性不足的问题,提出了一种由可变径平台和4-URU并联机构组成的可变径多模式移动并联机器人。首先,基于凸轮机构的特性设计了由多根径向伸缩杆组成的可变径平台,并分析了其结构与受力特性。然后,结合可变径平台的伸缩特性,以4-URU并联机构为主体构建了多模式移动并联机器人,并基于螺旋理论对4-URU并联机构的自由度进行了分析,得到了不同运动模式下的自由度及切换方法。在此基础上,采用ZMP(zero moment point,零力矩点)理论对机器人在各模式下的稳定性进行了评估。最后,通过ADAMS仿真和样机实验验证了机器人在窄缝穿越、单环滚动及双轮越障等模式下的越障性能与稳定性。结果表明,所设计的移动并联机器人兼具良好的折展能力与多模式适应性,可为复杂环境下多功能移动机器人的设计与应用提供新思路。展开更多
基金This work was sponsored by the National Natural Science Foundation of China （Grant No. 40476005, 40231013, 40233032,） and the Ministry of Science and Technology, China （Grant No. 2005DIBJ114）.
文摘Multi-fold technology is widely applied in seismic exploration as a method of enhancing useful signals and suppressing noise interference to greatly increase the signal to noise ratio （S/N）. The authors introduce it to ground-penetrating radar （GPR） surveys and compare the experimental results to the conventional profiling method to demonstrate the feasibility and advantages of the technique for GPR exploration. Based on the experimental data, the authors summarize the GPR wave propagation rules and the parameters of multi- fold acquisition and processing. It is proven to be a useful attempt to enrich the GPR survey technology.
基金sponsored by the National Natural Science Foundation of China under Grants No.61625502,No.61322501,No.61574127,No.61575174,No.61601408,No.61550110245 and No.61275183the Top-Notch Young Talents Program of China+3 种基金the Program for New Century Excellent Talents(NCET-12-0489)in Universitythe Fundamental Research Funds for the Central Universitiesthe Innovation Joint Research Center for Cyber-Physical-Society Systemthe support of the Postdoctoral Science Foundation of China under Grant No.2015M581930.
文摘An invisibility cloak that can hide an arbitrary object external to the cloak itself has not been devised before.In this Letter,we introduce a novel way to design a remote cloaking device that makes any object located at a certain distance invisible.This is accomplished using multi-folded transformation optics to remotely generate a hidden region around the object that no field can penetrate and that does not disturb the far-field scattering electromagnetic field.As a result,any object in the hidden region can stay in position or move freely within that region and remain invisible.Our idea is further extended in order to design a remote illusion optics that can transform any arbitrary object into another one.Unlike other cloaking methods,this method would require no knowledge of the details of the object itself.The proposed multi-folded transformation optics will be crucial in the design of remote devices in a variety of contexts.
文摘针对复杂非结构化环境下移动机器人的折展能力与多模式适应性不足的问题,提出了一种由可变径平台和4-URU并联机构组成的可变径多模式移动并联机器人。首先,基于凸轮机构的特性设计了由多根径向伸缩杆组成的可变径平台,并分析了其结构与受力特性。然后,结合可变径平台的伸缩特性,以4-URU并联机构为主体构建了多模式移动并联机器人,并基于螺旋理论对4-URU并联机构的自由度进行了分析,得到了不同运动模式下的自由度及切换方法。在此基础上,采用ZMP(zero moment point,零力矩点)理论对机器人在各模式下的稳定性进行了评估。最后,通过ADAMS仿真和样机实验验证了机器人在窄缝穿越、单环滚动及双轮越障等模式下的越障性能与稳定性。结果表明,所设计的移动并联机器人兼具良好的折展能力与多模式适应性,可为复杂环境下多功能移动机器人的设计与应用提供新思路。
