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LIQUID-SOLID COUPLED SYSTEM OF MICROPUMP

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Acta Mechanica Solida Sinica 2006年第1期19卷 40-49页

作者： wu jiankang Lu Lijun Department of Mechanics Huazhong University of Science and Technology Wuhan 430074 China

This paper employs the integral-averaged method of thickness to approximate the periodical flows in a piezoelectric micropump, with a shallow water equation including nonlinearity and viscous damp presented to characterize the flows in micropump. The finite element method is used to obtain a matrix equation of fluid pressure. The fluid pressure equation is combined with the vibration equation of a silicon diaphragm to construct a liquid-solid coupled equation for reflecting the interaction between solid diaphragm and fluid motion in a micropump. Numerical results of a mode analysis of the coupled system indicate that the natural frequencies of the coupled system are much lower than those of the non-coupled system. The influence of additional mass and viscous damp of fluid on the natural frequencies of the coupled system is more significant as the pump thickness is small. It is found that the vibration shape functions of silicon diaphragm of the coupled system are almost the same as those of the non-coupled system. This paper also gives the first-order amplitude-frequency relationship of the silicon diaphragm, which is necessary for the flow-rate-frequency analysis of a micropump.

关键词： micropump liquid-solid coupled system shallow water equation finite element method

Iterative dipole moment method for calculating dielectrophoretic forces of particle-particle electric field interactions

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Applied Mathematics and Mechanics(English Edition) 2015年第11期36卷 1499-1512页

作者： Le LIU Chuanchuan XIE Bo CHEN jiankang wu School of Civil Engineering and Mechanics Huazhong University of Science and Technology Wenhua Institute

Dielectrophoresis （DEP） is one of the most popular techniques for bio-particle manipulation in microfluidic systems. Traditional calculation of dielectrophoretic forces of single particle based on the approximation of equivalent dipole moment （EDM） cannot be directly applied on the dense particle interactions in an electrical field. The Maxwell stress tensor （MST） method is strictly accurate in the theory for dielectrophoretic forces of particle interaction, but the cumbersome and complicated numerical computation greatly limits its practical applications. A novel iterative dipole moment （IDM） method is pre- sented in this work for calculating the dielectrophoretic forces of particle-particle inter- actions. The accuracy, convergence, and simplicity of the IDM are confirmed by a series of examples of two-particle interaction in a DC/AC electrical field. The results indicate that the IDM is able to calculate the DEP particle interaction forces in good agreement with the MST method. The IDM is a purely analytical operation and does not require complicated numerical computation for solving the differential equations of an electrical field while the particle is moving.

关键词： dielectrophoresis (DEP) equivalent dipole moment (EDM) particle inter-action Maxwell stress tensor (MST) iterative dipole moment (IDM)

Flow behavior in microchannel made of different materials with wall slip velocity and electro-viscous effects

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Acta Mechanica Sinica 2010年第1期26卷 73-80页

作者： Lei Wang jiankang wu Department of Mechanics Huazhong University of Science and Technology Wuhan National Laboratory of Optoelectronics 430074 Wuhan China

In a microfluidic system, flow slip velocity on a solid wall can be the same order of magnitude as the average velocity in a microchannel. The flow-electricity interaction in a complex microfluidic system subjected to joint action of wall slip and electro-viscous effect is an important topic. This paper presents an analytic solution of pressuredriven liquid flow velocity and flow-induced electric field in a two-dimensional microchannel made of different materials with wall slip and electro-viscous effects. The Poisson- Boltzmann equation and the Navier-Stokes equation are solved for the analytic solutions. The analytic solutions agree well with the numerical solutions. It was found that the wall slip amplifies the fow-induced electric field and enhances the electro-viscous effect on flow. Thus the electro-viscous effect can be significant in a relatively wide microchannel with relatively large kh, the ratio of channel width to thickness of electric double layer, in comparison with the channel without wall slip.

关键词： Microchannel Wall slip - Electro-viscous effects

A new method for particle manipulation by combination of dielectrophoresis and field-modulated electroosmotic vortex

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Applied Mathematics and Mechanics(English Edition) 2018年第3期39卷 409-422页

作者： Chuanchuan XIE Bo CHEN Bing YAN jiankang wu School of Civil Engineering and Mechanics Huazhong University of Science and Technology Department of Mechanical and Electrical Engineering Wenhua College

A field-modulated electroosmotic flow （FMEOF） in a microchannel can be obtained by applying modulating electric fields in a direction perpendicular to the channel wall. Micro-vortexes are generated around the electrodes along with an EOF due to the surface charge on the modulated wall. When polarizable particles are suspended near the electrodes, they experience dielectrophoretic forces due to a non-uniform electric field. In this paper, micro-vortexes and dielectrophoretic forces are combined to achieve separation and trap different sized particles in a continuous flow. Numerical results indicate that by adjusting the driving electric field parallel to the channel wall and the modulating electric field, the ratio of dielectrophoretic and hydrodynamic forces can be altered. One type of particles can be trapped by micro-vortexes （negative dielectrophoresis （DEP））, and the other particles are transported to the downstream so that the particles are separated. The influence of the electrode length and the channel height on the trapping rate is investigated.

关键词： electroosmotic dielectrophoretic micro-vortex particle separation

Combining field-modulating electroosmotic vortex and insulating post to manipulate particles based on dielectrophoresis

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Applied Mathematics and Mechanics(English Edition) 2021年第3期42卷 371-386页

作者： Bing YAN Bo CHEN Fanyun LIU jiankang wu Yongliang XIONG School of Civil Engineering and Mechanics Huazhong University of Science and TechnologyWuhan 430074China

The dielectrophoretic technology has been one of the most frequently applied microfluidic technologies to manipulate *** way of a combination of controlled electroosmotic micro-vortices and dielectrophoresis to manipulate particles of different sizes was proposed in our previous ***,the thickness of the modulating electrode is *** practice,when the thickness of the modulating electrode increases,the channel flux increases,while the ability of the vortex to capture the particles *** this study,a new method combining the field-modulating electroosmotic vortex and the insulating post is proposed to improve the manipulating capability of the field-modulated electroosmotic vortex to *** results indicate that there are three great advantages as the insulating post is placed on the channel wall on the same side of the modulating ***,the capturing ability of the vortex to particles is greater due to the reduction of channel flux and the squeezing ***,the range of regulating channel flux to achieve the optimal separation is ***,the separation efficiency improves since the perfect separation can be achieved at a higher flow ***,the effects of the location and the size of the insulating post on particle separation are analyzed in *** present work could provide the reference for the application of the DEP technology.

关键词： electroosmotic vortex dielectrophoresis(DEP) insulating post particle separation

Wearable sensors for 3D upper limb motion modeling and ubiquitous estimation

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控制理论与应用（英文版） 2011年第1期9卷 10-17页

作者： Zhang, Zhiqiang Wong, Wai Choong wu, jiankang Sensor Network and Application Research Center Graduate University of Chinese Academy of Sciences Beijing 100049 China China-Singapore Institute of Digital Media Singapore 119613 Singapore Department of Electrical and Computer Engineering National University of Singapore Singapore 117576 Singapore

Human motion capture technologies are widely used in interactive game and learning, animation, film special effects, health care, and navigation. Because of the agility, upper limb motion estimation is the most difficult problem in human motion capture. Traditional methods always assume that the movements of upper arm and forearm are independent and then estimate their movements separately; therefore, the estimated motion are always with serious distortion. In this paper, we propose a novel ubiquitous upper limb motion estimation method using wearable microsensors, which concentrates on modeling the relationship of the movements between upper arm and forearm. Exploration of the skeleton structure as a link structure with 5 degrees of freedom is firstly proposed to model human upper limb motion. After that, parameters are defined according to Denavit-Hartenberg convention, forward kinematic equations of upper limb are derived, and an unscented Kalman filter is invoked to estimate the defined parameters. The experimental results have shown the feasibility and effectiveness of the proposed upper limb motion capture and analysis algorithm.

关键词： Ubiquitous motion modeling and estimation Forward kinematic equation Wearable microsensors

Body sensor networks for ubiquitous healthcare

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控制理论与应用（英文版） 2011年第1期9卷 3-9页

作者： Wang, Shaofeng Ji, Lianying Li, Aiguang wu, jiankang Sensor Networks and Applications Research Center Graduate University and Institute of Automation Chinese Academy of Sciences Beijing 100190 China

Body sensor networks provide a platform for ubiquitous healthcare, driving the diagnosis in hospital static environment to the daily life dynamic context. We realized the importance of sensing of activities, which is not only a dimension of human health but also important context information for diagnosis based on the physiologic data. This paper presents our ubiquitous healthcare system, uCare. It consists of uCare devices and a server system. Currently, the uCare system is designed for cardiovascular disease (CVD) examination and management. The uCare device has been tested in a trial in Beijing Hospital. The uCare system will be further tested in elderly care at home and exercise management in training to measure heart dynamics during training.

关键词： Body sensor networks Healthcare applications Sensor fusion Ubiquitous healthcare

Pulses in ground motions identified through surface partial matching and their impact on seismic rocking consequence

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 35-50页

作者： Tang Yuchuan Wang jiankang wu Gang School of Civil Engineering Southeast UniversityKey Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of EducationNanjing 211102China National and Local Joint Engineering Research Center for Intelligent Construction and Maintenance Nanjing 211102China

In seismology and earthquake engineering,it is fundamental to identify and characterize the pulse-like features in pulse-type ground *** capture the pulses that dominate structural responses,this study establishes congruence and shift relationships between response spectrum surfaces.A similarity search between spectrum surfaces,supplemented with a similarity search in time series,has been applied to characterize the pulse-like features in pulse-type ground *** identified pulses are tested in predicting the rocking consequences of slender rectangular blocks under the original ground ***,the prediction is promising for the majority of the ground motions where the dominant pulse is correctly identified.

关键词： velocity pulse ground motion surface similarity rocking overturning

A NEW DATA ASSOCIATION ALGORITHM USING PROBABILITY HYPOTHESIS DENSITY FILTER

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Journal of Electronics(China) 2010年第2期27卷 218-223页

作者： Huang Zhipei Sun Shuyan wu jiankang School of Information Science and Engineering Graduate University of Chinese Academy of Sciences Beijing 100190 China Institute of Electronics Chinese Academy of Sciences Beijing 100190 China

Probability Hypothesis Density (PHD) filtering approach has shown its advantages in tracking time varying number of targets even when there are noise,clutter and misdetection. For linear Gaussian Mixture (GM) system,PHD filter has a closed form recursion (GMPHD). But PHD filter cannot estimate the trajectories of multi-target because it only provides identity-free estimate of target states. Existing data association methods still remain a big challenge mostly because they are com-putationally expensive. In this paper,we proposed a new data association algorithm using GMPHD filter,which significantly alleviated the heavy computing load and performed multi-target trajectory tracking effectively in the meantime.

关键词： Multi-target trajectory tracking Probability Hypothesis Density (PHD) Gaussian mixture ((]M) model Multiple hypotheses detection Peak-to-track association