检索结果-南通市图书馆

Configuration Design of an Under-Actuated Robotic Hand Based on Maximum Grasping Space

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2018年第2期31卷 45-53页

作者： Shang-Ling Qiao Rong-Qiang liu Hong-Wei Guo yu-xuan liu Zong-Quan Deng State Key Laboratory of Robotics and System Harbin Institute of Technology College of International Cooperative Education Harbin Engineering University

Capture is a key component for on?orbit service and space debris clean. The current research of capture on?orbit focuses on using special capture devices or full?actuated space arms to capture cooperative targets. However, the structures of current capture devices are complex, and both space debris and abandoned spacecraft are non?cooperative targets. To capture non?cooperative targets in space, a lightweight, less driven under?actuated robotic hand is proposed in this paper, which composed by tendon?pulley transmission and double?stage mechanisms, and always driven by only one motor in process of closing finger. Because of the expandability, general grasping model is constructed. The equivalent joint driving forces and general grasping force are analyzed based on the model and the principle of virtual work. Which reveal the relationship among tendon driving force, joint driving forces and grasping force. In order to configure the number of knuckles of finger, a new analysis method which takes the maximum grasping space into account, is proposed. Supposing the maximum grasped object is an envelope circle with diameter of 2.5m. In the condition, a finger grasping maximum envelope circle with different knuckles is modeled. And the finger lengths with corresponding knuckles are calculated out. The finger length which consists of three knuckles is the shortest among under?actuated fingers consists of not more than five knuckles. Finally, the principle prototype and prototype robotic hand which consists of two dingers are designed and assembled. Experiments indicate that the under?actuated robotic hand can satisfy the grasp requirements.

关键词： Under?actuated robotic hand Tendon?pulley transmission Grasping space Configuration design

Advances in low-field nuclear magnetic resonance(NMR) technologies applied for characterization of pore space inside rocks:a critical review

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2020年第5期17卷 1281-1297页

作者： Jian-Chun Guo Hang-yu Zhou Jie Zeng Kun-Jie Wang Jie Lai yu-xuan liu State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu 610500China Department of Chemical Engineering School of EngineeringThe University of Western Australia35 Stirling HighwayPerthWA 6009Australia Downhole Operation Branch Southwest Petroleum Engineering Co.LtdSinopecDeyang 618014China

NMR serves as an important technique for probing rock pore space,such as pore structure characterization,fluid identification,and petrophysical property testing,due to the reusability of cores,convenience in sample processing,and time efficiency in laboratory *** practice,NMR signal collection is normally achieved through polarized nuclei relaxation which releases crucial relaxation messages for result *** impetus of this work is to help engineers and researchers with petroleum background obtain new insights into NMR principals and extend existing methodologies for characterization of unconventional *** article first gives a brief description of the development history of relaxation theories and models for porous ***,the widely used NMR techniques for characterizing petrophysical properties and pore structures are ***,limitations and deficiencies of them are ***,future work on improving these insufficiencies and approaches of enhancement applicability for NMR technologies are discussed.

关键词： Low-field NMR Critical review Relaxation theory Unconventional formation

Preparation and compression behavior of Fe-Ni-P/porous-Fe/Fe-Ni-P composites

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2022年第8期29卷 1334-1341页

作者： yu-xuan liu Shuai-jiang Yan Cheng-song Zhang Da-zhi Chen Qin Xu Guo-dong Cui Key Lab of Advanced Technology of Materials of Education Ministry School of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031SichuanChina Yibin Institute of Southwest Jiaotong University Yibin 644000SichuanChina

Porous-Fe-N alloys designed for light weight or energy absorption are inevitably facing the compromise of deteriorated mechanical properties. To optimize their mechanical properties, here a novel Fe-Ni-P/porous-Fe/Fe-Ni-P composite with sandwich structure was fabricated by spark plasma sintering and further strengthened via cryogenic treatment. Based on the principle of solid phase sintering and transient liquid phase sintering, porous core and dense outer layers formed simultaneously after co-sintering. The as-fabricated samples show excellent compressive strength of 1708 MPa, and after cryogenic treatment, due to the sufficient martensitic transformation, Fe-Ni-P outer layers show substantially increased hardness from 246.7 to 386.6 HV_(0.1)while the porous-Fe core remains unchanged. And the compressive strength maintains 1424 MPa despise the aggravated incongruity of deformation. The ratio of constituent microhardness R has been proposed to represent the hardness matching, and with decreasing R, the incongruity of deformation is intensified, and the nominal compressive strength is reduced.

关键词： Metallic composite Sandwich structure Spark plasma sintering Mechanical property

Effect of Ni-P content on microstructure and mechanical properties of Fe-Ni-P alloy

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2022年第11期29卷 1846-1852页

作者： Chi liu yu-xuan liu Ji-ping Lu Yan-huan Wang Lin-wang Chen Cheng-song Zhang Da-zhi Chen Guo-dong Cui Key Laboratory of Advanced Technology of Materials of Education Ministry School of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031SichuanChina Yibin Institute of Southwest Jiaotong University Yibin 644000SichuanChina

A series of Fe-Ni-P alloys with different Ni-P contents were prepared by micro-press sintering,and the influence of the contents on the final microstructure and mechanical properties was *** Fe-34(Ni,P)contains the highest Ni-P content(34.18 wt.%)and its relative density reaches 98.75%,which is attributed to the introduction of an appropriate amount of liquid phase during the sintering *** main phase of the sample is transformed from a to c phase under the gradual increment of Ni-P ***,a large number of phosphides that have strong inhibition on the migration and expansion of grain boundaries are precipitated on the matrix,and synergistic effect with low-temperature sintering results in partial grain *** samples with high Ni-P content have a high volume of c phase,which makes the sample show the optimal plasticity under the maximum compressive *** the fracture mode has also changed from brittle fracture to a mixed mode of brittle and ductile *** decrease in the proportion of a phase has a weakening effect on the strength,but the refinement of the grain and the increase in the phosphide are the factors that increase the strength,so that the degree of manifestation varies in different Ni-P levels.

关键词： Fe-Ni-P alloy Liquid phase sintering Mechanical behavior Microstructure

Subtle Alignment of Organic Semiconductors at the Donor/Acceptor Heterojunction Facilitates the Photoelectric Conversion Process

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2022年第8期40卷 951-959,I0010页

作者： yu-xuan liu Liang Wang Ke Zhou Hong-Bo Wu Xiao-Bo Zhou Zai-Fei Ma Sheng-Wei Guo Wei Ma State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an710049China School of Materials Science&Engineering North Minzu UniversityYinchuan750021China Center for Advanced Low-dimension Materials State Key Laboratory for Modification of Chemical Fibers and Polymer MaterialsCollege of Materials Science and EngineeringDonghua UniversityShanghai201620China

The aligned molecular packing structure is vital to the anisotropic charge transport in conjugated polymer and small molecule thin ***,how this molecular packing motif influences the photoelectric conversion process at the donor/acceptor heterojunction is still ***,we employed a PM6/Y6 bilayer model to investigate the long-range alignment of molecular packing induced photoelectric conversion *** PM6 and Y6 layers were properly controlled to exhibit the uniaxially oriented molecular packing compared to their as-cast counterparts,as revealed by the polarized absorption spectra and transmission electron *** analyzing the photovoltaic performance of bilayer devices,the smaller energy loss,lower energetic disorder,and longer charge carrier lifetime can be observed in the bilayer devices with aligned Y6 molecules,which contribute to a higher power conversion efficiency(PCE)than the as-cast *** the molecular packing structure of PM6 layer exhibited negligible influence on the device performance,probably resulting from the intrinsic semicrystalline nature of PM6 *** results indicate that the alignment of small molecular acceptor at the donor/acceptor interfaces should be a powerful strategy to facilitate the photoelectric conversion process,which will definitely pave the way to highly efficient bulk heterojunction photovoltaic device.

关键词： Molecular packing Photoelectric conversion process Planar heterojunction Organic solar cells

An efficient Bi/NH_4I-mediated addition reaction for the highly diastereoselective synthesis of homoallylic alcohols in aqueous media

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2020年第2期31卷 391-395页

作者： Zhen Wu Xue-Xin Feng Qing-Dong Wang xuan-yu liu Weidong Rao Jin-Ming Yang Zhi-Liang Shen School of Chemistry and Molecular Engineering Nanjing Tech UniversityNanjing 211816China School of Pharmacy Yancheng Teachers UniversityYancheng 224007China Jiangsu Key Laboratory of Biomass-based Green Fuels and Chemicals College of Chemical EngineeringNanjing Forestry UniversityNanjing 210037China

An efficient water-based bismuth-mediated addition reaction of carbonyl compound with cyclic allylic halide was *** reactions proceeded smoothly in aqueous DMF in the presence of ammonium iodide to afford the corresponding syn-homoallylic alcohols in moderate to good yields with excellent diastereoselectivities(>99:1 syn:anti).Reversal of product diastereoselectivity was observed when heteroaryl aldehyde possessing an adjacent chelating nitrogen atom was employed as substrate.

关键词： Bismuth Ammonium iodide Water Homoallylic alcohol Diastereoselectivity

Device-Free Through-the-Wall Activity Recognition Using Bi-Directional Long Short-Term Memory and WiFi Channel State Information

在线全文

学校读者我要写书评

暂无评论

Journal of Electronic Science and Technology 2021年第4期19卷 357-368页

作者： Zi-yuan Gong Xiang Lu yu-xuan liu Huan-Huan Hou Rui Zhou with the School of Information and Software Engineering University of Electronic Science and Technology of ChinaChengdu 610054

Activity recognition plays a key role in health management and *** approaches are based on vision or wearables,which only work under the line of sight(LOS)or require the targets to carry dedicated *** human bodies and their movements have influences on WiFi propagation,this paper proposes the recognition of human activities by analyzing the channel state information(CSI)from the WiFi physical *** method requires only the commodity:WiFi transmitters and receivers that can operate through a wall,under LOS and non-line of sight(NLOS),while the targets are not required to carry dedicated *** collecting CSI,the discrete wavelet transform is applied to reduce the noise,followed by outlier detection based on the local outlier factor to extract the activity *** recognition is fulfilled by using the bi-directional long short-term memory that takes the sequential features into *** in through-the-wall environments achieve recognition accuracy>95%for six common activities,such as standing up,squatting down,walking,running,jumping,and falling,outperforming existing work in this field.

关键词： Activity recognition bi-directional long short-term memory(Bi-LSTM) channel state information(CSI) device-free through-the-wall.

Spin glassy behavior and large exchange bias effect in cubic perovskite Ba0.8Sr0.2FeO3-δ

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2019年第6期28卷 433-437页

作者： yu-xuan liu Zhe-Hong liu Xu-Bin Ye Xu-Dong Shen Xiao Wang Bo-Wen Zhou Guang-Hui Zhou You-Wen Long Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications of Hunan Province Hunan Normal UniversityChangsha 410081China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physics University of Chinese Academy of SciencesBeijing 100049China Songshan Lake Materials Laboratory Dongguan 523808China

A single-phase iron oxideBa0.8Sr0.2FeO3-δwith a simple cubic perovskite structure in Pm-3 m symmetry is successfully synthesized by a solid-state reaction method in O2 flow. The oxygen content is determined to be about 2.81, indicating the formation of mixed Fe3+and Fe4+charge states with a disorder fashion. As a result, the compound shows small-polaron conductivity behavior, as well as spin glassy features arising from the competition between the ferromagnetic interaction and the antiferromagnetic interaction. Moreover, the competing interactions also give rise to a remarkable exchange bias effect in Ba0.8 Sr0.2 FeO2.81, providing an opportunity to use it in spin devices.

关键词： high-pressure synthesis exchange bias effect spin glass

Analysis of the geomorphology surrounding the Chang'e-3 landing site

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2014年第12期14卷 1514-1529页

作者： Chun-Lai Li Ling-Li Mu Xiao-Duan Zou Jian-Jun liu Xin Ren Xing-Guo Zeng Yi-Man Yang Zhou-Bin Zhang yu-xuan liu Wei Zuo Han Li Key Laboratory of Lunar and Deep Space Exploration National Astronomical ObservatoriesChinese Academy of Sciences

Chang＇e-3 （CE-3） landed on the Mare Imbrium basin in the east part of Sinus Iridum （19.51°W, 44.12°N）, which was China＇s first soft landing on the Moon and it started collecting data on the lunar surface environment. To better understand the environment of this region, this paper utilizes the available high-resolution topography data, image data and geological data to carry out a detailed analysis and research on the area surrounding the landing site （Sinus Iridum and 45 km×70 km of the landing area） as well as on the topography, landform, geology and lunar dust of the area surrounding the landing site. A general topographic analysis of the surrounding area is based on a digital elevation model and digital elevation model data acquired by Chang＇e-2 that have high resolution; the geology analysis is based on lunar geological data published by USGS; the study on topographic factors and distribution of craters and rocks in the surrounding area covering 4km^4km or even smaller is based on images from the CE-3 landing camera and images from the topographic camera; an analysis is done of the effect of the CE-3 engine plume on the lunar surface by comparing images before and after the landing using data from the landing camera. A comprehensive analysis of the results shows that the landing site and its surrounding area are identified as typical lunar mare with flat topography. They are suitable for maneuvers by the rover, and are rich in geological phenomena and scientific targets, making it an ideal site for exploration.

关键词： atlases -- methods: data analysis -- techniques: image processing --techniques: photometric