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MOTION OF TRACER PARTICLES IN A CENTRIFUGAL PUMP AND ITS TRACKING CHARACTERISTICS

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Journal of Hydrodynamics 2012年第5期24卷 785-793页

作者： LI Ya-lin yuan Shou-qi TANG Yue yuan jian-ping Research Center of Fluid Machinery Engineering and Technology Jiangsu University Zhenjiang 212013 China

The Basset-Boussinesq-Oseen （BBO） equation can be used for most flows to trace the motion of a particle, but in a centrifugal pump, among the forces that act on the particles, one should also include those due to the impeller rotation, as additional effects. This paper firstly reviews various approximations of the BBO equation for the motion of dispersion particles in a viscous fluid. Then based on the motion equation for particles in low Reynolds number centrifugal pumps, a formula for calculating the tracking characteristics of tracer particles is deduced through the Fourier integral transformation. After that the deviations of the particle motion from the fluid motion, as predicted by the various approximations, are discussed and compared. At last, with an emphasis on the Particle Image Velocimetry （PIV） results, the tracking characteristics of particles are estimated. Also, advantages and disadvantages of different tracer particles are discussed and suitable tracer particles for application in PIV studies for flow fields in centrifugal pumps are suggested.

关键词： tracer particles equations of motion tracking characteristics centrifugal pump Particle Image Velocimetry (PIV)

Trajectory optimisation in electrical discharge machining of three-dimensional curved and twisted channels

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Chinese Journal of Aeronautics 2022年第4期35卷 473-484页

作者： jianshe ZHAO Yicong QIU jian yuan Chao LIU College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Laboratory of Integrated Electrical Processing Nanjing HANGPU Machinery Technology Company LimitedNanjing 210000China Military Representative Bureau of the Air Force Equipment Department in Shanghai and Military Representative Office in Zhuzhou Region Zhuzhou 412002China AECC South Industry Company Limited Zhuzhou 412002China

Numerical control electrical discharge machining(NC EDM) is one of the most widely used machining technologies for manufacturing a closed blisk flow path, particularly for three-dimensional(3D) curved and twisted flow channels. In this process, tool electrode design and machining trajectory planning are the key factors affecting machining accessibility and efficiency. Herein, to reduce the difficulty in designing the electrode and its motion path in the closed curved and twisted channels, a heuristic search hybrid optimisation strategy based on channel grids is adopted to realise the initial electrode trajectory design search and optimised size reduction. By transferring the trajectory optimisation constraints from the complex free-form surface to numbered grids, the search is found to be more orderly and accurate. The two trajectory indicators, namely argument angle and minimum distance, are analysed separately for the optimised results of the adaptive learning particle swarm optimisation algorithm, demonstrating that they can meet the actual processing *** results of NC EDM indicate that the motion path generated by this design method can meet the machining requirements of 3D curved and twisted flow channels.

关键词： Blisk Electrical discharge machining(EDM) Electrode Objective functions Trajectory generation

LIDAR:learning from imperfect demonstrations with advantage rectification

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Frontiers of Computer Science 2022年第1期16卷 57-66页

作者： Xiaoqin ZHANG Huimin MA Xiong LUO jian yuan Department of EE Tsinghua UniversityBeijing100084China School of Computer and Communication Engineering University of Science and Technology BeijingBeijing100083China

In actor-critic reinforcement learning(RL)algorithms,function estimation errors are known to cause ineffective random exploration at the beginning of training,and lead to overestimated value estimates and suboptimal *** this paper,we address the problem by executing advantage rectification with imperfect demonstrations,thus reducing the function estimation *** with expert demonstrations has been widely adopted to accelerate the learning process of deep reinforcement learning when simulations are expensive to ***,existing methods,such as behavior cloning,often assume the demonstrations contain other information or labels with regard to performances,such as optimal assumption,which is usually incorrect and useless in the real *** this paper,we explicitly handle imperfect demonstrations within the actor-critic RL frameworks,and propose a new method called learning from imperfect demonstrations with advantage rectification(LIDAR).LIDAR utilizes a rectified loss function to merely learn from selective demonstrations,which is derived from a minimal assumption that the demonstrating policies have better performances than our current *** learns from contradictions caused by estimation errors,and in turn reduces estimation *** apply LIDAR to three popular actor-critic algorithms,DDPG,TD3 and SAC,and experiments show that our method can observably reduce the function estimation errors,effectively leverage demonstrations far from the optimal,and outperform state-of-the-art baselines consistently in all the scenarios.

关键词： learning from demonstrations actor-critic reinforcement learning advantage rectification

Scaling law of hydrogen evolution reaction for InSe monolayer with 3d transition metals doping and strain engineering

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Journal of Energy Chemistry 2020年第2期29卷 107-114页

作者： Chao Wang Yanyu Liu jian yuan Ping Wu Wei Zhou Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology Faculty of ScienceDepartment of Applied PhysicsInstitute of Advanced Materials PhysicsTianjin UniversityTianjin 300072China School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China

Recently, two dimensional In Se attracts great attentions as potential hydrogen production ***, comprehensive investigations on the hydrogen evolution reaction activity of In Se monolayer with3 d transition metal doping and biaxial strain were performed based on the density functional *** metal dopants significantly increase the bonding strength between H and Se, and then adjust the hydrogen adsorption free energy to 0.02 e V by Zn doping. The enhanced hydrogen evolution reaction activity results from less electron occupying H 1 s-Se 4 pzanti-bonding states, which is well correlated with the pzband center level. Importantly, the universal scalling law was proposed to descript the evolution of hydrogen adsorption free energy including both doping and strain effects. Moreover, with appropriate band alignment, optical absorption, and carriers separation ability, Zn doped In Se monolayer is considered as a promising candidate of visible-light photocatalyst for hydrogen production.

关键词： InSe monolayer Visible light photocatalyst Strain engineering 3d transition metals doping Hydrogen evolution reaction

Molecular Cloning and Expression Analysis of an Actin Gene from Chinese Licorice(Glycyrrhiza uralensis Fisch)

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Chemical Research in Chinese Universities 2009年第3期25卷 357-361页

作者： WANG Fang DONG Le yuan jian-jun Department of Biology School of Chemical and Biology Science Quanzhou Normal University Quanzhou 362000 P R. China

A PCR-based homologous cloning strategy was used to identify an actin gene from the roots of Chinese licorice（Glycyrrhiza uralensis Fisch）. Results of sequence analysis indicate that a 1137 bp cDNA with an open reading frame encoding 377 amino acids, actin ortholog, GuActin, was successfully cloned and characterized（GenBank accession No. EU190972）. Thus far, GuActin is the first actin of Chinese licorice that has been identified at a molecular level. Analysis by Northern blot shows that GuActin was expressed strongly in the roots, particularly in radicles than in stems and leaves. These results suggest that GuActin may be a member of the vegetative subfamily of the actin family.

关键词： Actin Gene cloning Chinese licorice(Glycyrrhiza uralensis Fisch) Gene expression

Non-detection of pulsed radio emission from magnetar Swift J1834.9-0846: constraint on the fundamental plane of magnetar radio emission

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Research in Astronomy and Astrophysics 2013年第7期13卷 835-840页

作者： Hao Tong jian-Ping yuan Zhi-Yong Liu Xinjiang Astronomical Observatory Chinese Academy of Sciences

The magnetar Swift J1834.9-0846 is observed using the Nanshan 25 m radio telescope. No pulsed radio emission is detected. The upper limit on the pulsed radio emission from this source is 0.5 mJy. According to the ＂fundamental plane＂ for radio magnetars, this source should have radio emission. Therefore, our results put constraints on the existence of a fundamental plane of magnetar radio emission. We argue that a magnetar＇s ability to emit radio emission may have little to do with the spin down luminosity and is related to the magnetar＇s X-ray luminosity. The only necessary condition is a relatively low X-ray luminosity.

关键词： pulsars: individual (Swift J1834.9-0846) - stars: magnetars - stars:neutron

Convergence Results of Landweber Iterations for Linear Systems

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Acta Mathematicae Applicatae Sinica 2014年第1期30卷 111-118页

作者： Gang-rong QU Ming jianG yuan-jian YANG School of Science Beijing Jiaotong University Beijing Center for Mathematics and Information Interdisciplinary Sciences LMAM School of Mathematical SciencesPeking University

The Landweber scheme is a method for algebraic image reconstructions. The convergence behavior of the Landweber scheme is of both theoretical and practical importance. Using the diagonalization of matrix, we derive a neat iterative representation formula for the Landweber schemes and consequently establish the convergence conditions of Landweber iteration. This work refines our previous convergence results on the Landweber scheme.

关键词： algebraic image reconstruction Landweber scheme weighted least-squares convergence conditions

Bore-center annular shaped charges with different liner materials penetrating into steel targets

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Defence Technology（防务技术） 2019年第5期15卷 796-801页

作者： Wen-long Xu Cheng Wang jian-ming yuan Tao Deng State Key Lab of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China Temasek Laboratories Nanyang Technological University50 Nanyang Drive637553Singapore

The bore-center annular shaped charge(BCASC)is a new type of shaped charge which can generate a larger-diameter hole in steel targets than classical shaped *** this paper,the influence of three liner materials,***,nickel and copper,on BCASC formation and penetrating into steel targets was investigated by experiment and numerical *** simulation results were well consistent with the experimental *** study showed that,at 0.50D standoff distance,the axial velocity of the molybdenum projectile was lower than that of the nickel and copper *** nickel and copper projectiles had almost the same head *** absolute values of the radial velocity of the molybdenum projectile head was lower than that of the nickel and copper ***,at 0.75D standoff distance,the absolute values of the radial velocity of the molybdenum projectile head became much greater than that of the nickel and copper projectile *** projectile formed by BCASC with the molybdenum liner had the highest penetration depth of 61.5 mm,which was 10.0%and 21.3%higher than that generated by the copper and nickel projectiles.

关键词： Annular shaped charge Liner material Formation Numerical simulation

Optical properties of Al_(x)Ga_(1-x)As/GaAs Woods-Saxon quantum well in the presence of hydrostatic pressure and applied electric field

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Communications in Theoretical Physics 2022年第6期74卷 143-151页

作者： Zhi-Hai Zhang Yi-Sheng Shi jian-Hui yuan School of Physics and Electronics Yancheng Teachers UniversityYancheng 224002China Intelligent photoelectric device and measurement engineering research center Yancheng Teachers UniversityYancheng 224002China The Laboratory of Biomedical Photonics and Engineering Guangxi Medical UniversityNanning 530021China

The third harmonic generation(THG),linear and nonlinear optical absorption coefficients(OACs),and refractive index changes(RICs)are investigated in a Woods-Saxon quantum well(QW)modulated by the hydrostatic pressure and applied electric *** effect of non-uniform aluminum doping(position-dependent effective mass(PDEM))on the mass of the system is discussed,and further to explore the influence of PDEM on the nonlinear THG,OACs,and RICs of the Woods-Saxon *** nonlinear optical properties above are obtained using the compact-density matrix *** electron states in a Woods-Saxon QW under the constant effective mass(CEM)and PDEM are calculated by solving the Schr?dinger equation via the finite difference *** contributions from competing effects of the hydrostatic pressure and applied electric field to the nonlinear optical properties with CEM and PDEM are reported,as well as the comparison with each *** observations reveal that the regulation of external fields and the influence of PDEM play an important role in the photoelectric properties of QW.

关键词： optical properties position dependent effective mass hydrostatic pressure electric field