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Theoretical Analysis and Experimental Verification on Flow Field of Piezoelectric Pump with Unsymmetrical Slopes Element

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Chinese Journal of Mechanical Engineering 2009年第5期22卷 735-744页

作者： XIA Qixiao ZHANG Jianhui LEI Hong cheng wei College of Mechanical and Electronie Engineering Beijing Union University Beijing 100020 China Precision Driving Laboratory Nanjing University of Aeronautics andAstronautics Nanjing 210016 China

Regular valveless piezoelectric pumps have rectifying elements outside their chambers to produce net flow. These rectifying elements outside the chamber will increase the overall volume of the pump and prevent its minimization. Valveless piezoelectric pump with unsymmetrical slopes elements（USE）, proposed in this paper, differs from other valveless pumps in that it is easy to be minimized by developing the chamber bottom as such a rectifying element. In this research, the working principle of the proposed pump was analyzed first. Numerical models were thereby established and numerical simulation was conducted to the chamber flow field with the method of time-dependent velocity. The effects of the USEs on the flow field in the chamber were shown clearly in simulation. And the particular feature of flow field in the chamber was discovered. It behaves a complex flow field, in which strong turbulent occurs companying a lot of vortexes in different directions and different sizes. This feature is just opposite to what regular piezoelectric pumps expect： a moderate flow field. The turbulent flow could be used to have different liquids stirred and well mixed in the chamber to produce homogeneous solution, emulsion or turbid liquid. Meanwhile, numerical simulation also presents the effect of the angles difference of the two slopes upon the flow field, and upon the flow rate of the pump, which fits to the theoretical analysis. Experiments with the proposed pump were also conducted to verify the numerical results. In these experiments, six USEs with different slope angles were used for efficiency tests, which proved the validity and reliability of the numerical analysis. The data obtained from numerical analysis agree well with that from the experiments. The errors ranged from 4.4% to 14.8% with their weighted average error being 9.7%.

关键词： Piezoelectric Valveless Pump Flow field Unsymmetrical slopes element

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Modeling Method and Application of Rational Finite Element Based on Absolute Nodal Coordinate Formulation

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Acta Mechanica Solida Sinica 2018年第2期31卷 207-228页

作者： Chao Ma cheng wei Jing Sun Bin Liu Beijing Key Laboratory of Intelligent Space Robotic Systems Technology and Applications Beijing Institute of Spacecraft System Engineering Department of Aerospace Engineering Harbin Institute of Technology

In multibody system dynamics, the absolute nodal coordinate formulation （ANCF） uses power functions as interpolating polynomials to describe the displacement field. It can get accurate results for flexible bodies that undergo large deformation and large rotation. However, the power functions are irrational representation which cannot describe the complex shapes precisely, especially for circular and conic sections. Different from the ANCF representation, the rational absolute nodal coordinate formulation （RANCF） utilizes rational basis functions to describe geometric shapes, which allows the accurate representation of complicated displacement and deformation in dynamics modeling. In this paper, the relationships between the rational surface and volume and the RANCF finite element are provided, and the generalized transformation matrices are established correspondingly. Using these transformation matrices, a new four-node three-dimensional RANCF plate element and a new eight-node three-dimensional RANCF solid element are proposed based on the RANCF. Numerical examples are given to demonstrate the applicability of the proposed elements. It is shown that the proposed elements can depict the geometric characteristics and structure configurations precisely, and lead to better convergence in comparison with the ANCF finite elements for the dynamic analysis of flexible bodies.

关键词： Multibody system dynamics Absolute nodal coordinate formulation Flexible deformation Spline representation Rational finite element

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Analysis on Flow Field of the Valveless Piezoelectric Pump with Two Inlets and One Outlet and a Rotating Unsymmetrical Slopes Element

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Chinese Journal of Mechanical Engineering 2012年第3期25卷 474-483页

作者： XIA Qixiao ZHANG Jianhui LEI Hong cheng wei College of Mechanical and Electronic Engineering Beijing Union UniversityBeijing 100020China Precision Driving Laboratory Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Typically,liquid pump and liquids mixer are two separate *** invention of piezoelectric pump makes it possible to integrate the two ***,the existing piezoelectric mixing-pumps are larger because the need the space outside the chamber,and another shortcome of them is that they cannot adjust the mixing ratio of two *** this paper,a new piezoelectric pump being capable of integrating mixer and pump is presented,based on the theory of the piezoelectric pump with the unsymmetrical slopes element（USE）.Besides the features of two inlets and one outlet,the piezoelectric pump has a rotatable unsymmetrical slopes element（RUSE）.When the pump works,two fluids flow into the inlet channels *** the RUSE controls the ratio of the two flows by adjusting the flow resistances of the two inlet *** fluids form a net flow due to the USE principle,while they are mixed into a homogeneous solution due to strong turbulence flow field and complex vortices generated by RUSE in the *** then the solution flows through the ***,the theoretical analysis on this pump is ***,the flow field in the chamber is calculated and *** then,the relationship between the flows of the two channels and the rotating angle of the RUSE is set up and ***,experiment with the proposed pump is carried out to verify the numerical results.A RUSE with 20° slope angle is used in the *** sets of data are tested with the RUSE at the rotating angles of 0°,6°,11°,and 16°,respectively,corresponding to the numerical *** experimental results show that the empirical data and the theoretical data share the same *** maximum error between the theoretical flow and the experimental flow is 11.14%,and the maximum error between the theoretical flow ratio of the two inlets and the experimental one is 2.5%.The experiment verified the theoretical *** proposed research provides a new idea for integration o

关键词： piezoelectric pump valveless rotatable unsymmetrical slopes element

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Relationship between Dislocation Density in P91 Steel and Its Nonlinear Ultrasonic Parameter

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Journal of Iron and Steel Research International 2015年第11期22卷 1024-1030页

作者： Ye-qing CAI Jin-zhong SUN cheng-jie LIU Shi-wei MA Xi-cheng wei School of Materials Science and Engineering Shanghai University School of Mechatronics Engineering and Automation Shanghai University

P91 steel is an important bearing material used in nuclear power plants. The study of its mechanical degradation behavior is important for ensuring safe operation. The relationship between the dislocation density of P91 steel under different strains and the corresponding nonlinear ultrasonic parameter β was studied. The dislocation density of strained samples was estimated by X-ray diffraction. Nonlinear ultrasonic testing was conducted to evaluate β, showing that this value increased with increasing dislocation density induced by different tensile elongations. It was shown that the ultrasonic secondharmonic generation technique can effectively evaluate the degradation behavior of metallic materials, and the prediction of the residual life of bearing parts in service can be made based on β and the dislocation density.

关键词： dislocation density P91 steel nonlinear ultrasonic second order harmonic

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Superoscillation:from physics to optical applications

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Light(Science & Applications) 2019年第1期8卷 688-710页

作者： Gang Chen Zhong-Quan Wen cheng-wei Qiu College of Optoelectronic Engineering Chongqing University174 Shazheng StreetChongqing 400044China Department of Electrical and Computer Engineering National University of Singapore4 Engineering Drive 3Singapore 117583Singapore

The resolution of conventional optical elements and systems has long been perceived to satisfy the classic Rayleigh *** efforts have been made to develop different types of superresolution techniques to achieve optical resolution down to several nanometres,such as by using evanescent waves,fluorescence labelling,and *** imaging techniques,which are noncontact,far field and label free,are highly desirable but challenging to *** concept of superoscillation offers an alternative route to optical superresolution and enables the engineering of focal spots and point-spread functions of arbitrarily small size without theoretical *** paper reviews recent developments in optical superoscillation technologies,design approaches,methods of characterizing superoscillatory optical fields,and applications in noncontact,far-field and label-free superresolution *** work may promote the wider adoption and application of optical superresolution across different wave types and application domains.

关键词： optical oscillation resolution

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Preparation and properties of silane coupling agent modified steel slag as functional filler for anti-corrosion coating

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Journal of Iron and Steel Research International 2023年第4期30卷 708-716页

作者： wei-cheng Zheng wei-cheng Xu Hao Zhang Hao-xuan Zheng Lin Wang Zheng-ming cheng Yan-fei Ye Jun Lin Hong-ming Long School of Metallurgical Engineering Anhui University of TechnologyMa’anshan 243032AnhuiChina Key Laboratory of Metallurgical Emission Reduction and Resources Recycling(Anhui University of Technology) Ministry of EducationMa’anshan 243002AnhuiChina School of Civil Engineering and Architecture Anhui University of TechnologyMa’anshan 243032AnhuiChina Department of Chemical and Biochemical Engineering Western UniversityLondonON N6A 3K7Canada Shanghai Baosteel New Building Materials Technology Co. Ltd.Shanghai 201900China Shougang Jingtang United Iron&Steel Co. Ltd.Tangshan 063200HebeiChina Zhanjiang Baosteel New Building Materials Technology Co. Ltd.Zhenjiang 524047GuangdongChina Guilin Hongcheng Mining Equipment Manufacture Co. Ltd.Guilin 541000GuangxiChina

The chemical composition and high wear resistance of steel slag(SS)make it a potential alternative to traditional inorganic fillers.3-Aminopropyltriethoxysilane(KH550)modified steel slag(MSS)was successfully prepared,and its application in epoxy(EP)anti-corrosion coating was *** to the grafting of silane coupling agent functional groups onto the surface of SS,MSS exhibited improved solubility in xylene organic solvent and reduced *** the MSS content was 15 wt.%,the contact angle of the MSS/EP composite coating was 101°,and the abrasion was only 0.07 g,compared with 56.2°and 0.13 g,respectively,for the pure EP *** corrosion resistance of coatings was investigated by performing the electrochemical test(impedance)after immersion in a 3.5 wt.%NaCl *** electrochemical test results showed that the impedance modulus of the 15 wt.%MSS/EP composite coating at low frequency(Z_(f)=0.01 Hz)was approximately 1.08×10^(7)Ωcm^(2),which was two orders of magnitude higher than that of the pure EP coating.

关键词： Steel slag Silane coupling agent Modification Epoxy coating Inorganic filler

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Precision micro-milling process:state of the art

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Advances in Manufacturing 2021年第2期9卷 173-205页

作者： Lorcan O’Toole cheng-wei Kang Feng-Zhou Fang Center of Micro/Nano Manufacturing Technology(MNMT-Dublin) University College DublinDublin 4Ireland State Key Laboratory of Precision Measuring Technology and Instruments Center of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin 300072People’s Republic of China

Micro-milling is a precision manufacturing process with broad applications across the biomedical,electronics,aerospace,and aeronautical industries owing to its versatility,capability,economy,and efficiency in a wide range of *** particular,the micro-milling process is highly suitable for very precise and accurate machining of mold prototypes with high aspect ratios in the microdomain,as well as for rapid micro-texturing and micro-patterning,which will have great importance in the near future in bio-implant *** is particularly true for machining of typical difficult-to-machine materials commonly found in both the mold and orthopedic implant ***,inherent physical process constraints of machining arise as macromilling is scaled down to the *** leads to some physical phenomena during micromilling such as chip formation,size effect,and process *** dynamic physical process phenomena are introduced and discussed in *** is important to remember that these phenomena have multifactor effects during micro-milling,which must be taken into consideration to maximize the performance of the *** most recent research on the micro-milling process inputs is discussed in detail from a process output perspective to determine how the process as a whole can be ***,newly developed processes that combine conventional micro-milling with other technologies,which have great prospects in reducing the issues related to the physical process phenomena,are also ***,the major applications of this versatile precision machining process are discussed with important insights into how the application range may be further broadened.

关键词： Precision machining Micro-milling Size effect Deflection Runout Tool wear

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An influence function method based subsidence prediction program for longwall mining operations in inclined coal seams

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Mining Science and Technology 2009年第5期19卷 592-598页

作者： LUO Yi cheng Jian-wei Department of Mining Engineering West Virginia University Morgantown WV USA

The distribution of the final surface subsidence basin induced by longwall operations in inclined coal seam could be significantly different from that in flat coal seam and demands special prediction methods. Though many empirical prediction methods have been developed, these methods are inflexible for varying geological and mining conditions. An influence function method has been developed to take the advantage of its fundamentally sound nature and flexibility. In developing this method, significant modifications have been made to the original Knothe function to produce an asymmetrical influence function. The empirical equations for final subsidence parameters derived from US subsidence data and Chinese empirical values have been incorpo- rated into the mathematical models to improve the prediction accuracy. A corresponding computer program is developed. A number of subsidence cases for longwall mining operations in coal seams with varying inclination angles have been used to demonstrate the applicability of the developed subsidence prediction model.

关键词： subsidence prediction influence function method inclined coal seam longwall mining

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A Kernel-Free Boundary Integral Method for Variable Coefficients Elliptic PDEs

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Communications in Computational Physics 2014年第4期15卷 1108-1140页

作者： Wenjun Ying wei-cheng Wang Department of Mathematics MOE-LSC and Institute of Natural SciencesShanghai Jiao Tong UniversityMinhangShanghai 200240P.R.China Department of Mathematics National Tsing Hua Universityand National Center for Theoretical SciencesHsinChu300Taiwan

This work proposes a generalized boundary integral method for variable coefficients elliptic partial differential equations(PDEs),including both boundary value and interface *** method is kernel-free in the sense that there is no need to know analytical expressions for kernels of the boundary and volume integrals in the solution of boundary integral *** of a boundary or volume integral is replaced with interpolation of a Cartesian grid based solution,which satisfies an equivalent discrete interface problem,while the interface problem is solved by a fast solver in the Cartesian *** computational work involved with the generalized boundary integral method is essentially linearly proportional to the number of grid nodes in the *** paper gives implementation details for a secondorder version of the kernel-free boundary integral method in two space dimensions and presents numerical experiments to demonstrate the efficiency and accuracy of the method for both boundary value and interface *** interface problems demonstrated include those with piecewise constant and large-ratio coefficients and the heterogeneous interface problem,where the elliptic PDEs on two sides of the interface are of different types.

关键词： Elliptic partial differential equation variable coefficients kernel-free boundary integral method finite difference method geometric multigrid iteration

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Application type identification of Internet flows based on medium mathematics

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The Journal of China Universities of Posts and Telecommunications 2010年第6期17卷 72-79,88页

作者： cheng wei-qing GONG Jian DING wei SUN Zhi-xin Computer College Nanjing University of Posts and Telecommunications Nanjing 210003 China School of Computer Science and Technology Southeast University Nanjing 210096 China State Key Laboratory of Software Development Environment Beijing 100191 China

Internet application identification is needed by network management in many aspects,such as quality of service （QoS） management,intrusion detection,traffic engineering,accounting,and so on. This article makes an in-depth study of precise identification of Internet applications by using flow characteristics instead of well-known port or application signature match. A novel approach that identifies the application type of an Internet protocol （IP） flow by finding what flow the flow looks the most like based on medium mathematics system （MMS） is proposed. The approach differs from previous ones mainly in two aspects：it has inherent scalability due to its use of the measure of n-dimensional medium truth degree; not only features of a flow,but also the association between the flow and the other flows of the same host as well as the relation among all flows of a host are employed to recognize a flow＇s application type. For the present,some popular applications are concentrated on,and up to six application types can be identified with better accuracy. The results of experiments conducted on Internet show that the proposed methodology is effective and deserves attention.

关键词： application type identification flow characteristics measure of medium truth degree MMS

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