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Nanotechnology and Precision Engineering 2024年第3期7卷 71-78页

作者： Wei Zhao Zongwei Xu pengfei wang Hanyi Chen State Key Laboratory of Precision Measuring Technology and Instruments Tianjin UniversityTianjin 300072China Department of Modern Physics University of Science and Technology of ChinaHefei 230026China

Nitrogen vacancy(NV)color centers in diamond have useful applications in quantum sensing andﬂuorescent *** can be gen-erated experimentally by ion implantation,femtosecond lasers,and chemical vapor ***,there is a lack of studies of the yield of NV color centers at the atomic *** the molecular dynamics simulations described in this paper,NV color centers are pre-pared by ion implantation in diamond with pre-doped nitrogen and subsequent *** differences between the yields of NV color centers produced by implantation of carbon(C)and nitrogen(N)ions,respectively,are *** is found that C-ion implantation gives a greater yield of NV color centers and superior location *** effects of different pre-doping concentrations(400–1500 ppm)and implantation energies(1.0–3.0 keV)on the NV color center yield are analyzed,and it is shown that a pre-doping concentra-tion of 1000 ppm with 2 keV C-ion implantation can produce a 13%yield of NV color centers after 1600 K annealing for 7.4 ***,a brief comparison of the NV color center identiﬁcation methods is presented,and it is found that the error rate of an analysis utiliz-ing the identify diamond structure coordination analysis method is reduced by about 7%compared with conventional identiﬁcation+methods.

关键词： NV color center Ion implantation Molecular dynamics(MD)simulation Yield enhancement

A Parallel Actuated Pantograph Leg for High-speed Locomotion

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Journal of Bionic Engineering 2017年第2期14卷 202-217页

作者： Wei Guo Changrong Cai Mantian Li Fusheng Zha pengfei wang Kenan wang State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China

High-speed running is one of the most important topics in the field of legged robots which requires strict constraints on structural design and control. To solve the problems of high acceleration, high energy consumption, high pace frequency and ground impact during high-speed movement, this paper presents a parallel actuated pantograph leg with an approximately decoupled configuration. The articulated leg features in light weight, high load capacity, high mechanical efficiency and structural stability. The similarity features of force and position between the control point and the foot are analyzed. The key design parameters, K1 and K2, which concern the dynamic performances, are carefully optimized by comprehensive evaluation of the leg inertia and mass within the maximum foot trajectory, A control strategy that incorporates virtual Spring Loaded Inverted Pendulum （SLIP） model and active force is also proposed to test the design. The strategy can implement highly flexible impedance without mechanical springs, which substantially simplifies the design and satisfies the variable stiffness requirements during high-speed running. The rationality of the structure and the effectiveness of the control law are validated by simulation and experiments.

关键词： high-speed parallel actuated pantograph leg optimization virtual SLIP model active force

Motion Characteristics of the Appendages of Mole Crickets during Burrowing

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Journal of Bionic Engineering 2019年第2期16卷 319-327页

作者： Yan Zhang Jiafeng Cao Qi wang pengfei wang Yueying Zhu Junxia Zhang Tianjin Key Laboratory of Integrated Design and On-line Monitoring for Light Industry&Food Machinery and Equipment College of Mechanical EngineeringTianjin University of Science&TechnologyTianjin 300222China

Mole crickets,Gryllotalpa orientalis,have a pair of fully specialized forelegs for burrowing and employ an efficient underground excavating pattern,which provides excellent biological example for design of bionic underground excavation *** this study,the excavating pattern and kinematic features of mole crickets were obtained by using high-speed motion capture system and employing a transparent hydrogel as the analogue for *** two-dimensional motion characteristics of the forelegs of mole crickets during burrowing were captured and *** results show that the forelegs of the mole cricket employ a unique excavating pattern,which consists of foreword digging and horizontal *** label this pattern a digging-expanding *** excavating cycle includes the digging and expanding motion of the forelegs,rotation caused by the midlegs and hindlegs,and forward thrust by the *** excavating motion of the left and right forelegs is alternately carried *** study can inspire the design of bionic tunnelling mechanisms and underground excavation equipment.

关键词： bionics experimental biology mole cricket burrowing forelegs

Clean numerical simulation for some chaotic systems using the parallel multiple-precision Taylor scheme

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Chinese Science Bulletin 2014年第33期59卷 4465-4472页

作者： pengfei wang Yong Liu Jianping Li Center for Monsoon System Research Institute of Atmospheric Physics Chinese Academy of Sciences State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences

An improved parallel multiple-precision Taylor(PMT) scheme is developed to obtain clean numerical simulation(CNS) solutions of chaotic ordinary differential equations(ODEs). The new version program is about 500 times faster than the reported solvers developed in the MATHEMATICA, and also 2–3 times faster than the older version(PMT-1.0) of the scheme. This solver has the ability to yield longer solutions of Lorenz equations [up to5000 TU(time unit)]. The PMT-1.1 scheme is applied to a selection of chaotic systems including the Chen, Rossler,coupled Lorenz and Lu¨ systems. The Tc-M and Tc-K diagrams for these chaotic systems are presented and used to analyze the computation parameters for long-term solutions. The reliable computation times of these chaotic equations are obtained for single- and double-precision computation.

关键词：混沌系统精度计算数值模拟泰勒并行常微分方程 LTI系统数学发展

Performance study of feature descriptors for human detection on depth map

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International Journal of Modeling, Simulation, and Scientific Computing 2014年第3期5卷 17-32页

作者： pengfei wang Shiwei Ma Yujie Shen School of Mechatronic Engineering&Automation Shanghai Key Laboratory of Power Station Automation Technology Shanghai University No.149Yanchang Rd.200072 ShanghaiP.R.China

Depth map contains the space information of objects and is almost free from the influence of light,and it attracts many research interests in the field of machine vision used for human ***,hunting a suitable image feature for human detection on depth map is rather *** this paper,we evaluate the performance of the typical features on depth map.A depth map dataset containing various indoor scenes with human is constructed by using Microsoft’s Kinect camera as a quantitative benchmark for the study of methods of human detection on depth *** depth map is smoothed with pixel filtering and context filtering so as to reduce particulate ***,the performance of five image features and a new feature is studied and compared for human detection on the dataset through theoretic analysis and simulation *** show that the new feature outperforms other descriptors.

关键词： Human detection depth map feature descriptor

UOUU:User-Object Distance and User-User Distance Combined Method for Collaboration Task

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Computer Modeling in Engineering & Sciences 2023年第9期136卷 3213-3238页

作者： Xiangdong Li pengfei wang Hanfei Xia Yuting Niu College of Computer Science and Technology Zhejiang UniversityHangzhou310000China

Augmented reality superimposes digital information onto objects in the physical world and enables multi-user *** that previous proxemic interaction research has explored many applications of user-object distance and user-user distance in an augmented reality context,respectively,and combining both types of distance can improve the efficiency of users’perception and interaction with task objects and collaborators by providing userswith insight into spatial relations of user-task object and user-user,less is concerned about howthe two types of distances can be simultaneously adopted to assist collaboration tasks *** fulfill the gap,we present UOUU,the user-object distance and user-user distance combined method for dynamically assigning tasks across *** conducted empirical studies to investigate how the method affected user collaboration tasks in terms of collaboration occurrence and overall task *** results show that the method significantly improves the speed and accuracy of the collaboration tasks as well as the frequencies of collaboration *** study also confirms the method’s effects on stimulating collaboration activities,as the UOUU method has effectively reduced the participants’perceived workload and the overall moving distances during the *** for generalising the use of the method are discussed.

关键词： Augmented reality proximity interaction computer supported cooperative work user-object distance user-user distance

Organocatalytic atroposelective construction of axially chiral nonsymmetric biaryltriols and their applications in asymmetric synthesis and heavy metal ion detection

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Organic Chemistry Frontiers 2022年第4期9卷 923-928页

作者： Shiqi Jia Wenling Qin pengfei wang Hailong Yan Chongqing Key Laboratory of Natural Product Synthesis and Drug Research School of Pharmaceutical SciencesChongqing 401331P.R.China

An organocatalytic methodology toward the atroposelective construction of axially chiral nonsymmetric biaryltriols has been successfully developed.A quinine-derived thiourea-catalyzed intramolecular reaction using VQM(vinylidene ortho-quinone methides)intermediates enabled efficient access to a class of axially chiral nonsymmetric biaryltriols with up to 98%yield and 99%ee.

关键词： chiral symmetric axial

Dust removal efficiency of high pressure atomization in underground coal mine

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International Journal of Mining Science and Technology 2018年第4期28卷 677-682页

作者： pengfei wang Xuanhao Tan Weimin Cheng Gang Guo Ronghua Liu School of Mining and Safety Engineering Shandong University of Science & Technology School of Resource Environment & Safety Engineering Hunan University of Science & Technology

To master theoretical calculation for dust removal efficiency of high pressure atomization in an underground coal mine, the corresponding atomization characteristics and dust removal efficiency were both comprehensively studied in theory by virtue of related theories of hydromechanics and *** to actual measurements of flow coefficients and atomization angles of X-type swirl nozzle,computational formula was derived for atomized particle sizes of such a nozzle in conjunction with relevant empirical equation. Moreover, a mathematical model for applying high pressure atomization to dust removal in underground coal mine was also established to deduce theoretical computation formula of fractional efficiency. Then, Matlab was adopted to portray the relation curve between fractional efficiency and influence factors. In addition, a theoretical formula was also set up for removal efficiency of respirable dust and total coal dust based on dust size and frequency distribution equations. In the end,impacts of dust characteristic parameters on various dust removal efficiencies were analyzed.

关键词： Underground coal mine High pressure atomization Atomization characteristics Dust removal efficiency

Can Monetary Policy Undo Asset-freezing Sanctions?

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China & World Economy 2023年第6期31卷 33-55页

作者： Hengxu Song pengfei wang School of Economics Jinan UniversityChina HSBC Business School Peking UniversityChina

This article investigates the macroeconomic consequences of foreign asset-freezing sanctions,a tool utilized by several Western nations amid recent geopolitical ***,it examines the repercussions of such sanctions on open economies,finding that they may experience a sharp recession and currency *** quantify the impact,we develop a new Keynesian dynamic stochastic general equilibrium model with financial frictions and an asset-freezing channel for an open *** also calibrate our model to capture the unique structures of the Russian *** quantitative analysis of the model demonstrates that an abrupt asset-freezing sanction would lead to large output losses and high inflation *** counterfactual examination reveals that higher elasticity of import substitution and lower elasticity of export substitution could alleviate the impact of foreign sanctions,whereas more aggressive monetary policy may have positive but limited stabilization ***,the monetary authority must navigate a trade-off between stabilizing output and managing inflation resulting from the cash-in-advance channel.

关键词： monetary policy new Keynesian reserves freezing sanctions

Steady-state coupled analysis of flowfields and thermochemical erosion of C/C nozzles in hybrid rocket motors

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Science China(Technological Sciences) 2015年第3期58卷 574-586页

作者： ZHAO Sheng TIAN Hui wang pengfei YU NanJia CAI GuoBiao School of Astronautics Beihang University

A hybrid rocket can be used in various applications and is an attractive propulsion system. However, serious erosion of nozzles is common in motor firing operations, which could restrict the application of hybrid rocket motors. Usually, the serious erosion is attributed to the high concentration of oxidizing species in hybrid motors, while the details of flowfields in the motors are not paid special attention to. In this paper, first the thermochemical erosion of C/C nozzle is simulated coupled with the flowfields in a 98% H2O2/hydroxyl-terminated polybutadiene（HTPB） hybrid rocket motor. The simulation is made on a typical axisymmetric motor, including a pre-combustion chamber, an aft-combustion chamber and nozzle structures. Thermochemica reactions of H2 O, CO2, OH, O and O2 with C are taken into account. Second, the change of flowfields due to fuel regression during motor firing operations is considered. Nozzle erosion in different flowfields is evaluated. Third, the results of nozzle erosion in the coupled simulation are compared with those under uniform and chemical equilibrium flow and motor firing test results. The results of simulation and firing tests indicate that the thermochemical erosion of nozzles in hybrid motors should be calculated coupled with flowfields in the motor. In uniform and chemical equilibrium flowfields, the erosion rate is overestimated. The diffusion flame in hybrid motors protects the nozzle surface from the injected oxidizer and high temperature products in flowfields, leading to a relatively fuel-rich environment above the nozzle. The influence of OH and the geometry of motor should also be considered in the evaluation of nozzle erosion in hybrid motors.

关键词： hybrid rocket motor C/C nozzle thermochemical erosion