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Kinematics Analysis of Motion Simulation Subsystem for Unmanned Vehicle

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Chinese Journal of Mechanical Engineering 2011年第6期24卷 923-934页

作者： TANG Guoming MEI Tao liu Wei li Bichun Institute of Intelligent Machines Chinese Academy of Sciences Hefei 230031 China Department of Precision Machinery ＆ Instrumentation University of Science and Technology of China Hefei 230026 China

Unmanned vehicle has attracted wide attention and interests throughout the world since it first deputed in the 1960s. However, the experimental methods for unmanned vehicle＇s intelligent behavior, such as semi-physical simulation and motion subsystem, have not been widely explored. First, the requirements of the motion subsystem in unmanned vehicle semi-physical facility are analyzed, and a six DOF parallel manipulator is selected to reproduce the pose of the vehicle. The link lengths of the motion subsystem are worked out under the given rotational angles of the vehicle. According to the geometric properties of tetrahedron, three joint positions of the top platform are determined, and the rest are obtained from the first three position vectors. Six constraint equations are set up based on the vertices on the top platform and the link lengths. In order to solve the six angle variables, a numerical algorithm built on the Newton-Raphson iterative method is presented, which is based on Taylor series expansion of six constraint equations. The pose of the top platform is ultimately calculated. The eigenvalues of the top platform are solved to obtain the natural frequencies of the motion subsystem. The coordinates of six joint centers on the top platform and six constraint equations can be realized by simple algebraic manipulation, which allows significant abbreviation in the formulation and provides a systematic way of obtaining the kinematic solution of the parallel manipulator. A numerical example is given and its efficacy is demonstrated by the inverse kinematics. The computation strategy based on tetrahedron method and Newton-Raphson iterative method provide a simple and cost-effective method for solving forward kinematics of six DOF parallel manipulators, and this method sheds light on other parallel manipulators.

关键词： unmanned vehicle motion simulation subsystem Tetrahedron method kinematics Newton-Raphson iterative method

Corrosion behavior of an Al-6Mg-Sc-Zr alloy

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Rare Metals 2005年第3期24卷 246-251页

作者： XU Guangxin TAO Binwu liu Jianhua li Songmei School of Materials Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China Shenyang Aircraft Design and Research Institute Shenyang 110035 China

The corrosion behavior of an Al-6Mg-Sc-Zr alloy was studied and compared with that of an Al-6Mg-Zr alloy. The addition of scandium into the Al-6Mg-Zr alloy reduced the susceptibility to exfoliation corrosion. By using the constant load tensile method in a 3.5 wt.% NaCl solution, the resistance to SCC of the Al-6Mg-Sc-Zr alloy was higher than that of the Al-6Mg-Zr alloy. When the specimens were not applied with an anodic current, the Al-6Mg-Sc-Zr alloy was resistance to SCC and no brittle cracking was found on the fracture surface. When an anodic current was applied, the Al-6Mg-Sc-Zr alloy specimens failed as a result of accelerated corrosion rather than SCC. It was believed that the addition of scandium re- sulted in （Al3Sc, Zr） particles that greatly refined grains and promoted the formation of homogeneous discontinuous distribution of β-phase in the alloy base, which much contributed to good corrosion resistance of the Al-6Mg-Sc-Zr alloy.

关键词： corrosion Al-Mg-Sc-Zr alloy SCC test exfoliation corrosion scandium

Application of a green coagulant with PACl in efficient purification of turbid water and its mechanism study

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Journal of Environmental Sciences 2019年第7期31卷 168-180页

作者： Yuxiang Xue Zhouzhou liu Aimin li Hu Yang State Key Laboratory of Pollution Control and Resource Reuse School of the Environment Nanjing University

The applications of natural polymeric flocculants due to their green feature has been recently received much more attention. In this work, the combined usages of a cationic starch-based coagulant and polyaluminum chloride(PACl) were extensively evaluated for various addition sequences in the coagulation of both raw(surface water from the Jiuxiang River) and synthetic turbid water(two kaolin suspensions with different initial turbidities).Two typical cationic starch-based coagulants with different structures(St-G and St-E) were tried. In comparison to St-G, St-E and PACl used individually as well as St-G and St-E dosed after PACl, the combination of the starch-based coagulants fed before PACl showed higher turbidity removal efficiency, which featured not only less optimal doses of both inorganic and organic coagulants but also lower residual turbidity. On the basis of a detailed analysis of the particle size and its distribution in solution supernatants before and after coagulation by two starch-based coagulants and PACl, polymeric coagulants preferentially coagulate the small-sized colloids due to their distinct long-chain structures, but PACl preferentially coagulates the medium-sized ones. Thus, the medium-sized particles that were previously formed by the starch-based coagulants would be collectively and effectively removed by the subsequent addition of PACl. The addition sequence of the inorganic and organic coagulants in their combined usage is an important factor for improvement of the turbidity removal efficiency in practice.

关键词： Cationic starch-based green coagulants Polyaluminum chloride Combined coagulation Synergistic coagulation effects Synergistic mechanisms

Regulation of AMPK activation by extracellular matrix stiffness in pancreatic cancer

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Genes & Diseases 2024年第3期11卷 338-350页

作者： Xin Xu Yuan Fang Somaira Nowsheen ye-Xiong li Zhenkun Lou Min Deng State Key Laboratory of Molecular Oncology and Department of Radiation Oncology National Cancer Center/National Clinical Research Center for Cancer/Cancer HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100021China Department of General Surgery Shanghai General HospitalShanghai Jiaotong University School of MedicineShanghai 200080China Department of General Surgery Zhongshan HospitalFudan UniversityShanghai 200032China Department of Dermatology University of California San DiegoSan DiegoCA 92093USA Department of Oncology Mayo ClinicRochesterMN 55905USA

The adenosine monophosphate(AMP)-activated protein kinase(AMPK)sits at a cen-tral node in the regulation of energy metabolism and tumor *** is best known to sense high cellular ADP or AMP levels,which indicate the depletion of energy *** studies have shown that the low expression of phosphorylated AMPK is associated with a poor prognosis of pancreatic *** this study,we report that AMPK is also highly sensitive to extracellular matrix(ECM)*** found that AMPK is activated in cells when cultured under low ECM stiffness conditions and is functionally required for the metabolic switch induced by ECM *** regulation of AMPK requires the Hippo kinases but not LKB1/*** kinases directly phosphorylate AMPKa at Thr172 to activate AMPK at low ECM ***,we found AMPK activity is inhibited in patients with pancreatic ductal adenocarcinoma(PDAC)with high ECM stiffness and is associated with a poor survival *** activation of Hippo kinases by ROCK inhibitor Y-27632 in combination with the mitochondrial inhibitor metformin synergistically activates AMPK and dramatically inhibits PDAC ***,these findings establish a novel model for AMPK regulation by the mechanical properties of ECMs and provide a rationale for simultaneously targeting the ECM stiffness-Hippo kinases-AMPK signaling and low glucose-LKB1-AMPK signaling pathways as an effective therapeutic strategy against PDAC.

关键词： AMPKactivity Cellularmetabolic switch ECM stiffness Hippokinase signaling Pancreaticductal adenocarcinoma

Analysis of transmitter-side control methods in wireless EV charging systems

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Science China(Technological Sciences) 2018年第10期61卷 1492-1501页

作者： liu Fang CHEN KaiNan ZHAO ZhengMing li Kai Department of Electrical Engineering Tsinghua University

The wireless electric vehicle(EV) charging system is highly safe and flexible. To reduce the weight and cost of EVs, the wireless charging system, which simplifies the structure inside an EV and utilizes the transmitter-side control method, has become popular. This study investigates the transmitter-side control methods in a wireless EV charging system. First, a universal wireless charging system is introduced, and the function of its transfer power is derived. It is observed that the transfer power can be controlled by regulating either the phase-shift angle or the DC-link voltage. Further, the influence of the control variables is studied using numerical analysis. Additionally, the corresponding control methods, namely the phase-shift angle and the DC-link voltage control, are compared by calculation and simulation. It is found that:(1) the system efficiency is low with the phase-shift control method because of the converter switching loss;(2) the dynamic response is slow with the DC-link voltage control method because of the large inertia of the inductor and capacitor;(3) both the control methods have limitations in their adjustable power range. Therefore, a combined control method is proposed, with the advantages of high system efficiency, fast dynamic response, and wide adjustable power range. Finally, experiments are performed to verify the validity of the theoretical analysis and the effectiveness of the proposed method. This study provides a detailed and comprehensive analysis of the transmitter-side control methods in the wireless charging system, considering the sensitivity of parameters, converter losses, system efficiency,and dynamic performance, with the dead-time effect taken into consideration. Moreover, the proposed control method can be used to realize the optimal combination of the phase-shift angle and the DC-link voltage with good dynamic performance, and it is useful for the optimal operation of the wireless charging system.

关键词： clean-energy vehicles EV charging system wireless power transfer (WPT) transmitter-side control phase-shift control DC-link voltage control combined control method

Nickel release rate of 18KW gold alloy for ornaments

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Rare Metals 2013年第1期32卷 33-39页

作者： Jun-Ping Yuan Wei li Wen-Ming liu Department of Materials Science and Engineering Jinan University Jewelry Institute of Guangzhou Panyu Polytechnic

Nickel is widely used as a bleaching element in white gold alloys, but it is a potential allergen. In this paper, a popular 18 KW gold alloy, often called ＂safe nickel,＂ was chosen as the experimental material; its nickel release rates under six different processing conditions were evaluated according to the EN1811 standard. The results reveal that both the surface processing method and heat treatment technology significantly affect the nickel release rate. A coarse surface releases more nickel ions than a smooth surface. The sample normalized at 700 ~C in the single region has a lower nickel release rate than the one treated at 550 ~C in the two-phase phase region, while high temperature normalizing at 800 ~C will accelerate it. All the measured nickel release rates of the experimental material under various processing conditions exceed the permitted threshold value in the Nickel Directive, which indicates that there exists the potential risk of nickel- induced allergy when it is used to make jewelries, espe- cially for piercing types.

关键词： 18 KW Gold alloy Jewelry Nickel releaserate Nickel Directive Processing conditions

Synergistic promotion of dielectric and thermomechanical properties of porous Si_(3)N_(4)ceramics by a dual-solvent template method

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Journal of Advanced Ceramics 2024年第10期13卷 1622-1634页

作者： Yuanyuan liu Zhilin Tian liya Zheng Bin li School of Materials Shenzhen Campus of Sun Yat-sen UniversityShenzhen 518107China

Porous Si_(3)N_(4)ceramics are promising high-temperature wave transparent materials for use as radomes or antenna windows in hypersonic ***,a trade-off between the dielectric and thermomechanical properties is still ***,tailoring the microstructure and properties of porous Si_(3)N_(4)is highly *** this work,porous Si_(3)N_(4)ceramics with uniform and fine structures were obtained via dual-solvent templating combined with the freeze-casting *** as-prepared porous Si_(3)N_(4)ceramic,with 56%porosity,possesses high mechanical properties,with flexural strength and compressive strength values of 95±14.8 and 132±4.5 MPa,*** uniform spherical pore structure improved the mechanical properties,and the rod-shaped Si_(3)N_(4)grains facilitated crack *** decreased pore size effectively blocks phonon transport,leading to a low thermal conductivity of only 4.2 W/(K·m).Moreover,the porous Si_(3)N_(4)ceramic maintains a small dielectric constant of 3.3,and the dielectric loss is stable between 1.0×10^(-3)-4.0×10^(-3),which guarantees its potential application in high-temperature wave-transparent *** results significantly advanced the development of high-performance wave-transparent materials used in hypersonic aircraft.

关键词： Si_(3)N_(4) porous ceramics freeze-casting wave-transparent material dual solvent

A triple-RBD-based mucosal vaccine provides broad protectionagainst SARS-CoV-2 variants of concern

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Cellular & Molecular Immunology 2022年第11期19卷 1279-1289页

作者： Jingyi Yang Mei-Qin liu lin liu Xian li Mengxin Xu Haofeng lin Shuning liu Yunqi Hu Bei li Bowen liu Min li Ying Sun Yao-Qing Chen Zheng-li Shi Huimin Yan Vaccine and Immunology Research Center Translational Medical Research InstituteShanghai Public Health Clinical CenterFudan University201508 ShanghaiChina Wuhan Institute of Virology Chinese Academy of Sciences430071 WuhanChina University of Chinese Academy of Sciences 100049 BeijingChina School of Public Health(Shenzhen) Shenzhen Campus of Sun Yat-sen UniversityShenzhen 518107 GuangdongChina Aerosol Bio-Tech(Suzhou)Co. LTDSuzhou 215123 JiangsuChina Key Laboratory of Tropical Disease Control(Sun Yat-sen University) Ministry of EducationGuangzhouChina

The rapid mutation and spread of SARS-CoV-2 variants urge the development of effective mucosal vaccines to provide broadspectrum protection against the initial infection and thereby curb the transmission ***,we designed a chimeric tripleRBD immunogen,3Ro-NC,harboring one Delta RBD and two Omicron RBDs within a novel protein scaffold.3Ro-NC elicits potent and broad RBD-specific neutralizing immunity against SARS-CoV-2 variants of ***,intranasal immunization with 3RoNC plus the mucosal adjuvant KFD(3Ro-NC+KFDi.n)elicits coordinated mucosal IgA and higher neutralizing antibody specificity(closer antigenic distance)against the Omicron *** Omicron-challenged human ACE2 transgenic mice,3Ro-NC+KFDi.n immunization significantly reduces the tissue pathology in the lung and lowers the viral RNA copy numbers in both the lung(85.7-fold)and the nasal turbinate(13.6-fold).Nasal virologic control is highly correlated with RBD-specific secretory IgA *** data show that 3Ro-NC plus KFD is a promising mucosal vaccine candidate for protection against SARS-CoV-2 Omicron infection,pathology and transmission potential.

关键词： SARS-CoV-2 Mucosal vaccine Intranasal immunization Triple-RBD Flagellin adjuvant Variant of concern

Solid-Phase Decarburization of High-Carbon Ferromanganese Powders by Microwave Heating

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Journal of Iron and Steel Research International 2013年第8期20卷 34-40页

作者： GUO li-na CHEN Jin SHI Wen-li ZHAO Jing liu Ke liu Jin-ying College of Materials Science and Engineering Taiyuan University of Technology lian-zhi Technology Corporation of Xiangtan City No.12 Research Institute China Electronics Technology Group Corporation

The solid-phase decarburization of high-carbon ferromanganese powders （HCFPs） was investigated using calcium carbonate as the decarburizer by microwave heating and conventional heating methods to explore the differ-ences of microwave heating and conventional heating. Experimental results show that HCFPs containing ***-bonate were heated up to 900, 1000, 1 100, and 1200 ℃ and held for 60 rain for decarburization by microwave heat-ing at decarburization ratios of 76.69%, 82.90%, 84.11%, and 85. 75%, respectively. These ratios are higher than the decarburization ratios used for conventional heating under the same experimental conditipns. The microwave heat- ing can significantly improve decarburization ratio. This indicates the microwave heating field features a non-thermal effect, which in turn, visibly enhances the carbon diffusion ability of HCFPs. It also improves the kinetic conditions of solid-phase decarburization.

关键词： high-carbon ferromanganese powder solid-phase decarburization microwave heating conventional heating