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Fused-ring electron acceptors in China

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Science China Chemistry 2020年第9期63卷 1179-1181页

作者： Boyu Jia Xiaowei zhan Department of Materials Science and Engineering College of EngineeringKey Laboratory of Polymer Chemistry and Physics of Ministry of EducationPeking UniversityBeijing 100871China

In recent years,organic photovoltaics(OPVs)as one of nextgeneration solar energy technologies have attracted intense interest since they are featured with low cost,light weight,flexibility and semi-transparency[1].At the early stage in the OPV field,fullerenes and their derivatives dominated electron acceptor materials due to their high electron affinity,high electron mobility and isotropic electron transporting ability,and fullerene-based devices yielded power conversion efficiencies(PCEs)up to^12%[2].

关键词： transparency intense acceptor

Kinematics-based four-state trajectory tracking control of a spherical mobile robot driven by a 2-DOF pendulum

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Chinese Journal of Aeronautics 2019年第6期32卷 1530-1540页

作者： Wei LI Qiang zhan Robotics Institute Beihang UniversityBeijing 100083China Ecole Centrale de Pékin Beihang UniversityBeijing 100083China

Spherical mobile robot has compact structure, remarkable stability, and flexible motion,which make it have many advantages over traditional mobile robots when applied in those unmanned environments, such as outer planets. However, spherical mobile robot is a special highly under-actuated nonholonomic system, which cannot be transformed to the classic chained form. At present, there has not been a kinematics-based trajectory tracking controller which could track both the position states and the attitude states of a spherical mobile robot. In this paper, the four-state(two position states and two attitude states) trajectory tracking control of a type of spherical mobile robot driven by a 2-DOF pendulum was studied. A controller based on the shunting model of neurodynamics and the kinematic model was deduced, and its stability was demonstrated with Lyapunov’s direct method. The control priorities of the four states were allocated according to the magnification of each state tracking error in order to firstly ensure the correct tracking of the position states. The outputs(motor speeds) of the controller were regulated according to the maximum speeds and the maximum accelerations of the actuation motors in order to solve the speed jump problem caused by initial state errors, and continuous and bounded outputs were obtained. The effectiveness including the anti-interference ability of the proposed trajectory tracking controller was verified through MATLAB simulations.

关键词： Kinematics Lyapunov methods Neurodynamics Nonholonomic systems Spherical mobile robot Trajectory tracking

Interactions of penny-shaped cracks in three-dimensional solids

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Acta Mechanica Sinica 2006年第4期22卷 341-353页

作者： Shige zhan Tzuchiang Wang Department of Mathematical and Physical Sciences NSFC Beijing 100085 China LNM Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

The interaction of arbitrarily distributed penny-shaped cracks in three-dimensional solids is analyzed in this paper. Using oblate spheroidal coordinates and displacement functions, an analytic method is devel- oped in which the opening and the sliding displacements on each crack surface are taken as the basic unknown functions. The basic unknown functions can be expanded in series of Legendre polynomials with unknown coefficients. Based on superposition technique, a set of governing equations for the unknown coefficients are formulated from the traction free conditions on each crack surface. The boundary collocation procedure and the average method for crack-surface tractions are used for solving the governing equations. The solution can be obtained for quite closely located cracks. Numerical examples are given for several crack problems. By comparing the present results with other existing results, one can conclude that the present method provides a direct and efficient approach to deal with three-dimensional solids containing multiple cracks.

关键词： Three-dimensional problem Penny-shaped cracks Interaction

Topology optimization of a 6-DOF spatial compliant mechanism based on Stewart propotype platform

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Acta Mechanica Sinica 2019年第5期35卷 1044-1059页

作者： Dachang Zhu Wanghu zhan School of Mechanical and Electrical Engineering Guangzhou UniversityGuangzhou 510006China

To improve the global stiffness and conveniently build a model of a compliant mechanism with spatial multiple degrees of freedom(DOF),the topology optimization method,combined with the isomorphic mapping matrix,is proposed in this paper for structure synthesis of a 6-DOF spatial compliant *** using the differential approximation method,the Jacobian matrix of the Stewart prototype platform is calculated as the isomorphic mapping matrix,and its eigenvalues and eigenvectors are *** the isomorphic mapping matrix with the solid isotropic material with the penalization topology optimization method,the topological model of the 6-DOF spatial compliant mechanism is constructed,and a topological structure of the 6-DOF spatial compliant mechanism is derived which has the same differential kinematic characteristics as the Gough-Stewart prototype *** actuators are mounted inside the topological structure during the three-dimensional printing manufacturing process,and its driver directions are in accordance with the driver configuration directions of the Gough-Stewart prototype *** effectiveness of the proposed method for topological structure synthesis of the 6-DOF spatial compliant mechanism is demonstrated through several numerical examples and experimental studies.

关键词： 6-DOF spatial compliant mechanism Stewart prototype platform Isomorphic mapping Jacobian matrix Topology optimization

A Microstructural Damage Model toward Simulating the Mullins Effect in Double-Network Hydrogels

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Acta Mechanica Solida Sinica 2022年第4期35卷 682-693页

作者： Lin zhan Rui Xiao State Key Laboratory of Fluid Power and Mechatronic System Key Laboratory of Soft Machines and Smart Devices of Zhejiang ProvinceDepartment of Engineering MechanicsZhejiang UniversityHangzhou310027China

The damage models based on the eight-chain model and the affine full-chain network model are not adequate to describe the damage behaviors in double-network(DN)*** overcome this limitation,we propose a combined chain stretch model with new damage flow *** is demonstrated that the new proposed micro-chain stretch is a reduced form of the complete representation for the transversely isotropic tensor *** a result,the damage models based on the eight-chain model and the affine model are incorporated as special *** effects of chain affineness and network entangling are simultaneously involved in the new model,while only one of these two effects can be characterized in either the eight-chain model or the affine *** is further shown that the new model can effectively capture the Mullins features of the DN hydrogels and achieve better agreement with the experimental data than the affine model and the eight-chain model.

关键词： Mullins effect Double-network hydrogel Full-network model Microstructural model

Harnessing GABAergic Transmission for Slow Oscillations

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Neuroscience Bulletin 2016年第5期32卷 501-502页

作者： Yang zhan Brain Cognition and Brain Disease Institute Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences

Oscillatory neuronal activity is the fundamental signature of neural *** the EEG literature,the oscillations are described as belonging to different frequency bands that are commonly used in clinical monitoring.

关键词： signature neuronal bands excitatory hippocampal theta oscillation synaptic blocked hippocampus

Basic properties of sintering dust from iron and steel plant and potassium recovery

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Journal of Environmental Sciences 2013年第6期25卷 1226-1234页

作者： Guang zhan zhancheng Guo State Key Laboratory of Advanced Metallurgy University of Science and Technology

With the production of crude steel, China produces several million tons of sintering dusts which contain a great deal of valuable metals such as, K, Na, Zn, Pb. If discharged directly without adequate treatment, these elements can lead to adverse effects on the environment. Therefore, it is very necessary to determine how to separate these elements from the dust before discharge, Several physical and chemical detection methods were used to study the basic properties of sintering dust. At the same time, preliminary experiments on the recovery of the potassium resources from the sintering dust were carried out. The mean particle size of the electrostatic precipitator （ESP） dust determined by a laser granulometer was 41.468 ~tm. Multi-point BET and single-point BET analysis showed that the surface area of the ESP dust was 2.697 mZ/g. XRD measurements detected the following phases in the ESP dust： Fe203, Fe304, KC1 and NaC1, and Fe203, Fe304 and SiO2 in the water-washed dust. SEM-EDS results proved that in the ESP dust, K mostly existed in the form of KC1 particles without being coated. Leaching experiments showed that the KCI in the ESP dust could be separated and recovered by water leaching and fractional crystallization. Through the recovery experiments, the yield of K-Na vaporized crystalline salt was 18.56%, in which the mass fractions of KCl, NaCl, CaSO4 and K2SO4 were about 61.03%, 13.58%, 14.03% and 9.97%, respectively. This process is technically viable and considerable in economic benefit. There was almost no secondary pollution produced in the whole recovery process.

关键词： sintering dust physicochemical analysis recovery experiment potassium resource

Numerical analysis of time-varying wear with elastic deformation in line contact

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Friction 2019年第2期7卷 143-152页

作者： Wanglong zhan Ping HUANG School of Mechanical and Automotive Engineering South China University of Technology

Wear is an important factor for failures of mechanical components. Current research on wear is mainly focused on experiments while the numerical simulation of wear is hardly used owing to the complexities of the wear process. Explaining the effect of friction on the wear process is important, as it will lead to a deeper understanding of the evolution of wear. This study proposed a numerical method to expound the wear process in the contact between an elastic cylinder and a half-space simulating the ring-block tester. There are two difficulties during the calculation; one is that the contact shapes vary with time, causing the pressure distribution to change simultaneously and the other is the integral equation for calculating the contact pressure under different worn shapes. In the present study, the wear rate was computed using Archard's law and the wear process was calculated step by step until the specified total sliding distance was achieved. During each step of the calculation, the contact topography was updated. The simulation intuitively reproduced the contact state of change from line to surface contact throughout the wear process. Reasonable agreements on the changes of the wear scar, achieved from experiments and numerical simulations, were obtained.

关键词： time varying wear singular integral equation elastic deformation wear scars contact pressure

Diversity of free-living nitrogen-fixing microorganisms in wastelands of copper mine tailings during the process of natural ecological restoration

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Journal of Environmental Sciences 2011年第3期23卷 476-487页

作者： Jing zhan Qingye Sun School of Life Science Anhui University Hefei 230039 China

Biological nitrogen fixing is an important source of nitrogen input in the natural ecological restoration of mine wastelands. The diversity of nifH genes in railings samples under different plant communities in Yangshanchong and Tongguanshan wastelands in Tongling, was analyzed using polymerase chain reaction-denaturing gradient gel electrophoresis （PCR-DGGE） approach. The nitrogen-fixing microorganism community in the upper layer of tailings of Tongguanshan wasteland discarded in 1980 showed higher Shannon-Wiener diversity index than that in Yangshanchong wasteland discarded in 1991. The diversity of nifH genes in Yangshanchong wasteland of copper mine tailings did not display a consistent successional tendency with development of plant communities during the process of natural ecological restoration. Phylogenetic analysis of 25 sequences of nifH gene fragments retrieved from the DGGE gels indicated that there were mainly two taxa of free-living nitrogen-fixing microorganisms, Proteobacteria and Cyanobacteria living in the wastelands investigated, most of which were unique and uncultured. Canonical correspondence analysis （CCA） based on the relationship between band patterns of DGGE profile and physico-chemical properties of railings samples showed that the diversity of nifH genes in different tailing samples was mainly affected by loss of ignition, water content, pH and available Zn contents of wastelands. The dominant plant species and development period of plant communities by ameliorating pH, reducing the toxicity of heavy metals, increasing organic matter and water content affected the diversity and structure of the free-living nitrogenfixing microorganisms in wastelands of copper mine tailings.

关键词： nifH nitrogen fixation PCR-DGGE natural ecological restoration copper mine tailings