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

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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

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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

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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

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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

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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

Microstructures and mechanical properties of in-situ TiB2/Al−xSi−0.3Mg composites

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Transactions of Nonferrous Metals Society of China 2021年第2期31卷 331-344页

作者： yu-xuan liu Ri-chu WANG Chao-qun PENG Zhi-yong CAI Zhao-hui ZHOU Xiao-geng LI xuan-yang CAO School of Materials Science and Engineering Central South UniversityChangsha 410083China National Key Laboratory of Light High Strength Structural Materials Central South UniversityChangsha 410083China Changsha Advanced Materials Industrial Research Institute Changsha 410000China

In-situ 2 vol.%TiB2 particle reinforced Al−xSi−0.3Mg(x=7,9,12,15 wt.%)composites were prepared by the salt−metal reaction,and the microstructures and mechanical properties were *** results show that the TiB2 particles with a diameter of 20−80 nm and the eutectic Si with a length of 1−10μm are the main strengthening phases in the TiB2/Al−xSi−0.3Mg *** TiB2 particles promote grain refinement and modify the eutectic Si from needle-like to short-rod ***,the strengthening effect of TiB2 particles is weakened as the Si content exceeds the eutectic composition,which can be attributed to the formation of large and irregular primary *** axial tensile test results and fractography observations indicate that these composites show more brittle fracture characteristics than the corresponding alloy matrixes.

关键词： Al−Si alloy in-situ reaction aluminum matrix composite microstructure mechanical properties

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

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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

Dynamic interactive bitwise meta-holography with ultra-high computational and display frame rates

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Opto-Electronic Advances 2024年第1期7卷 36-46页

作者： yuncheng liu Ke Xu Xuhao Fan Xinger Wang xuan yu Wei Xiong Hui Gao Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074China Optics Valley Laboratory Wuhan 430074China

Interactive holography offers unmatched levels of immersion and user engagement in the field of future *** of the substantial progress has been made in dynamic meta-holography,the realization of real-time,highly smooth interactive holography remains a significant challenge due to the computational and display frame rate *** this study,we introduced a dynamic interactive bitwise meta-holography with ultra-high computational and display frame *** our knowledge,this is the first reported practical dynamic interactive metasurface holographic *** spa-tially divided the metasurface device into multiple distinct channels,each projecting a reconstructed *** switching states of these channels were mapped to bitwise operations on a set of bit values,which avoids complex holo-gram computations,enabling an ultra-high computational frame *** approach achieves a computational frame rate of 800 kHz and a display frame rate of 23 kHz on a low-power Raspberry Pi computational *** to this methodology,we demonstrated an interactive dynamic holographic Tetris game system that allows interactive gameplay,color display,and on-the-fly hologram *** technology presents an inspiration for advanced dynamic meta-holography,which is promising for a broad range of applications including advanced human-computer interaction,real-time 3D visualization,and next-generation virtual and augmented reality systems.

关键词： interactive display meta-holography bitwise operation ultra-high frame rate

Heterogeneous hybrid immunity against Omicron variant JN.1 at 11 months following breakthrough infection

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Signal Transduction and Targeted Therapy 2024年第8期9卷 3170-3172页

作者： xuan He Jingyou yu Jiajing Jiang Jinyuan liu Qi Qi Dan liu Weimin Li Department of Pulmonary and Critical Care Medicine Precision Medicine Key Laboratory of Sichuan ProvinceState Key Laboratory of Respiratory Health and MultimorbidityWest China HospitalSichuan UniversityChengduSichuanChina Guangzhou National Laboratory Bio-lslandGuangzhouGuangdongChina Sichuan Center for Disease Control and Prevention ChengduSichuanChina

Dear Editor,Due to the ongoing evolution of SARS-CoV-2 and waning immunity following COVID-19 vaccination,breakthrough infections have become common *** exposure to viral antigens during different COVID-19 waves and vaccination contribute to the unique"hybrid immunity"-immune protection conferred by the combined vaccination and natural infection in individuals.

关键词： immunity vaccination infection