Research on a Rigid Rotor—Sliding Bearing System with a Squeeze Film Damper

In this paper,a dynamic model on a rigid rotor-sliding bearing system with a SFD is established.The stability and bifurcation behaviors of the system are studied,on The basis of the differential equations of fluid momentum and mass continuity,the distribution pressure function is derived by taking oil film inertia force into consideration.Damping force, clearance excitation force,interference force of different frequencies and static load are also considered in the model,Finally,the governing equations of the stability and bifurcation behaviors of the system are solved by Floquet theory,Simulation of dynamic model shows that the rigid rotor-sliding bearing system can maintain stability and exhibit a Hopt bifurcation phenomenon in a certain range.     

Analysis on Dynamic Performance for Active Magnetic Bearing—Rotor System

In the application of active magnetic bearings(AMB),one of the key problems to be solved is the safety and stabiltiy in the sense of rotor dynamics,The project related to the present paper deals with the method for analyzing bearing rotor systems with high rotation speed and specially supported by active magnetic bearings,and studies its rotor dynamics performance,including calculation of the natural frequencies with their distribution characteristics,and the critical speeds of the system.one of the targets of this project is to formulate a theory and method valid for the analysis of the dynamic performance of the active magntic bearing-rotor systemby combining the traditional theory and method of rotor dynamics with the analytical theory and design method based on modern control theory of the AMB system.     

Theoretical Investigation on a Novel Hydrodynamic Journal Bearing

To improve the static and dynamic performance of hydrodynamic journal beatings, a novel bearing is developed, which is a cone-shaped hydrodynamic bearing with spiral oil wedges. The major structural feature of this bearing is the three spiral circular recesses on the beating‘s surface, leading to improved characteristics. This paper aims to develop a model for design and calculation of the geometric parameters and the oil film thickness, and to provide a theoretical analysis to the static characteristics using a f‘mite element method. Some new features are introduced.     

Experiment and Simulations on Lubrication Performance of EMP Journal Bearing

In recent years, much attention has been devoted to the design and operation of bearings made of elastic metal plastic (EMP). The surface of the bearing bush is covered by a layer of polymer PTFE(polytetrafluoroethylene). The physical performances of the polymer are quite different from that of metal. It can reduce friction because of its lower surface energy, and it is more difficult for the fluid to be adhered. Consequently, the slip will exist at the oil-bush interface. The journal bearings made of this material are researched in this article. Through test, the existence of slip is proven and the equation of the slip velocity for the EMP journal bearing is established when shear stress up to a certain value. Thus, the classical Reynolds equation is modified. The lubrication mechanism is analyzed by some simulation results.     

Interaction Efects on the Density of States in a Disordered Metalic Film

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Study on Mandatory Access Control in a Secure Database Management System

This paper propses a security policy model for mandatory access control in class B1 database management system whose level of labeling if tuple.the relation-hierarchical data model is extended to multilevel relation-hierarchical data model.Based on the multievel relation-hierarchical data model,the concept of upper-lower layer relational integrity is presented after we analyze and eliminate the covert channels caused by the database untegrity,Two SQL statements are extended to process polyinstantiation in the multilevel secure environment.The system is based on the multievel relation-hierarchical data model and is capable of integratively storing and manipulating multilevel complicated objects(e.g.,multilevel spatial data) and multievel conventional data(e.g.,integer,real number and character string).     

Implementation of a Novel Algorithm on Acoustic Doppler Current Profiler Signal Processing System＊

Acoustic Doppler current profiler （ADCP） uses acoustic energy directed along narrow beams for current measurement. In conventional method, the quantity of sampling affects the precision of fast Fourier transform （FFT） algorithm, and the algorithm needs a large amount of data to process. A novel frequency estimator.enhanced least mean square （ELMS） algorithm for a single complex sinusoid in complex white Gaussian noise, is proposed in ADCP system. As sampling frequency equals 120 krad/s and the sampling number equals 240. the minimum resolving is 0. 5 krad/s. All variances keep 11.11%. ELMS algorithm needs less data than FFT. And the robust algorithm can estimate the spectrum true value to 99.9% when the signal to noise ratio （SNR） is equal to 0 dB. Experiments prove that the estimation values will diverge much from the ideal when SNR is less than -6 dB.     

A Method of Calculating the 3D coordinates on a Micro Object in a Virtual Micro—Operation System

A simple method for calculating the 3D coordinates of points on a moro object in a multi-camera system is proposed.It simplifies the algorithms used in traditional computer vision system by eliminating the calculation of the CCD( charge coupled device) camera parameters and the relative position between cameras,and using solid geometry in the calculation procedres instead of the calculation of the complex matrixes,The algorithm was used in the research of generating a virtual magnified 3D image of a micro object to be operated in a micro operation system,and the satisfactory results were obtained.The application in a virtual tele-operation system for a dexterous mechanical gripper is under test.     

Application of the Non—Stationary Oil Film Force Database

The technique of non-stationary oll film force database for hydrodynamic bearing is introduced and its potential applications in nonlinear rotor-dynamics are demonstrated.Through simulations of the locus of the shaft center aided by the database technique,nonlinear stability analysis can be performed and the natural frequency can be obtained as well.The easiness of “assembling” the individual bush forces from the database to form the bearing force.makes it very convenient to evaluate the stability of various types of journal bearings,Examples are demonstrated to show how the database technique makes it possible to get technically abundant simulation results at the expense of very short calculation time.     

不同轴承联合作用下转子系统的不平衡响应

基于线性振动理论分析并计算了滚动轴承和滑动轴承联合作用下转子系统理想对中和不对中时的不平衡响应。结果表明,不平衡响应主要发生在临界转速附近,此时不对中量对系统的不平衡响应的影响非常显著,而在工作转速处,不对中量对系统不平衡响应的影响变小。     

非解析径向轴承支承转子系统非线性动力特性分析

Nomenclaturex,y,x ·, y·-displacement and velocity of rotor-x,-y,x-·,-y·-displacement and velocity of rotor , di mension less¨x,¨y-acceleration of rotor¨-x,¨-y-acceleration of rotor ,di mensionlessω-rotating speed of rotor-ω-rotating speed of rotor ,di mensionlessx,y,z-Cartesian coordinates-x,-y,-z-Cartesian coordinates ,di mensionless2m-mass of rotorg-acceleration of gravityG-weight of rotor ,di mensionlesse=e2x e2y-mass eccentricity of rotorex,ey-mass eccentricity of rotor in thexan…     

A study on dynamic response of slopes under wave action using simulation tests

1. Introduction At present, the construction of large-scale reservoirworks has given rise to many large-scale reservoirareas, the stabilization of slopes in these reservoirdistricts will be influenced by water waves. Thecirculating hydraulic loading caused by the waveproduces a great force on the slope, and especiallyforms a vibration wave force on the boundary of water surface and the slope earth, and even breaks the water-soil interface, leading to the excess pore pressurechanging along diff…     

齿轮传动系统动力学的研究方向

介绍了齿轮传动系统的振动和噪音问题，并阐述了目前齿轮系统动力学研究的发展方向。     

Dynamic response of functional virtual prototyping of motorcycle under combined excitations

This paper developed 3D product models of motorcycle and engine by UGNX as well as virtual prototyping by ADAMS program with road roughness generated by MATLAB. Under the straight-line running condition, the dynamic responses of motorcycle multibody system to both road and engine excitations were compared with those to only road excitation in terms of vertical acceleration response, amplitude frequency response and power spectral density. The comparisons of simulation data showed that the response due to flat road excitation was around 20 Hz, while that to the combined excitations was in a wide frequency band, of which the major components focused on 10 Hz, 15 Hz, 35 Hz ,70 Hz, 100 Hz and even higher frequencies, reflecting the characteristics of engine excitation based on its unbalanced inertia force and torque. It is concluded that the high fidelity virtual prototyping can simulate the dynamics of motorcycle product well in investigating the vibration and ride comfort performance.     

基于Hamilton原理的双跨转子系统建模和转子动态特性分析

研究目的：研究双盘双跨转子/轴承/汽封系统在非线性油膜力和非线性汽封力共同作用下的动力学特性,分析了转子转速、密封力、油膜力和联轴器刚度等因素对转子稳定性的影响。创新要点：采用Hamilton原理和有限元方法建立双盘双跨转子/轴承/汽封系统模型,使得双跨多节点的转子系统数值求解更加容易。研究分析转子转速、非线性密封力、非线性油膜力和联轴器刚度等因素对转子稳定性的影响,为大型转子系统的设计提供理论基础。研究方法：采用Hamilton原理和有限元方法建立双盘双跨转子/轴承/汽封系统模型（图1和2）。应用四阶Runge-Kutta法进行数值求解,并采用轴承处、圆盘处的分岔图、时程图、庞加莱映射图、频率图和相轨迹图等来分析转子系统的动态特性。重要结论：1.通过数值计算分析,转子的转速、非线性汽封力、非线性油膜力和联轴器的刚度对双跨转子的稳定性有重要的影响作用。2.随着转速的上升,双跨转子系统从最初的稳定运动,到三倍周期运动,到准周期运动和多倍周期运动交替出现,运动特性相比单跨转子系统要更为复杂。