基于H方程的超导磁悬浮系统悬浮特性分析

高精度的重力测量在地震监测、资源勘探、惯性导航等领域均有着十分重要的意义,将超导磁悬浮系统应用于重力测量可以极大提高重力测量的精度,减少漂移率。当前对超导重力仪内磁悬浮系统的仿真主要采用A方程静磁场法,仿真得到的数据与实验结果相差较大,为了提高仿真精度和效率,采用H方程在COMSOL中建立了新的仿真模型,仿真得到的数据与实验结果偏差较小,验证了该方法可以提高超导磁悬浮系统的仿真精度和效率。仿真得到了超导重力仪内磁悬浮系统的磁场分布,屏蔽电流分布,受力,穿透深度等特征,分析了超导球在磁场中受到的悬浮力与悬浮高度、悬浮线圈电流大小、通入速率的关系,计算得到了超导磁悬浮系统的磁力梯度。     

激光聚变靶丸磁悬浮系统设计

为实现均匀辐照,ICF靶的无接触支撑是关键,ICF磁靶悬浮是实现无接触支撑的理想途径之一。对ICF靶的磁悬浮系统进行了初步设计,利用超前相位补偿器作为内回路改善系统的稳定性。仿真试验时,系统在初始阶段（0～10 ms）小球出现轻微振荡,之后逐渐趋于稳定,最终到达设定的目标位。悬浮系统控制曲线平滑,调节时间短,这说明ICF靶磁悬浮是可行的。     

激光聚变靶丸磁悬浮系统设计

 为实现均匀辐照,ICF靶的无接触支撑是关键,ICF磁靶悬浮是实现无接触支撑的理想途径之一。对ICF靶的磁悬浮系统进行了初步设计,利用超前相位补偿器作为内回路改善系统的稳定性。仿真试验时,系统在初始阶段（0～10 ms）小球出现轻微振荡,之后逐渐趋于稳定,最终到达设定的目标位。悬浮系统控制曲线平滑,调节时间短,这说明ICF靶磁悬浮是可行的。     

Human simulated intelligent control of vehicle suspension system with MR dampers

This paper presents vibration control responses of a controllable magnetorheological (MR) suspension system of a passenger car. The MR damper is designed and manufactured on the basis of the mixed-mode operation, and its time response is experimentally evaluated to integrate with the suspension model. After formulating the dynamic model of a half-car MR suspension system, a human simulated intelligent control (HSIC) scheme is developed to attenuate unwanted vibrations such as pitch angle acceleration. After verifying the effectiveness of the HSIC via computer simulation, the road test of the passenger car installed with four MR dampers is undertaken. The power spectrum densities of dynamic motions such as body acceleration and pitch angle acceleration are measured and analyzed. In addition, the control results obtained from the proposed HSIC are compared with those obtained from a conventional linear quadratic Gaussian (LQG) control method.     

Nonlinear resonance in an acoustic system with a coagulating gas suspension

The occurrence of resonance in an acoustic system as a result of a change of the dispersion of a gas suspension filling a resonator with fixed external excitation parameters was studied. The dynamics of the medium is described by a system of equations of motion of a multi-velocity multi temperature continuum taking into account pulse and energy exchange between the carrier phase and the disperse fractions. Coagulation of different particle fractions is simulated by Smolukhovskii’s Lagrangian model, which takes into account pair collisions. Resonance occurs as a result of the resonance frequency of the system approaching a fixed external excitation frequency as a result of a change in the dispersion of the gas suspension during coagulation initiated by the addition of a small amount of the large particle fraction to the finely dispersed gas suspension. As a result of calculations, an estimate for the time of the change in dispersion of the system and the generation of resonance oscillations were obtained.     

串级二极管悬浮电极支撑控制系统的研制

串级二极管悬浮电极支撑控制系统主要包括支撑结构、驱动电路和同步控制三部分。支撑结构采用基于电磁铁工作原理的支撑针,对悬浮电极进行三点定位;驱动控制采用高压脉冲电容放电驱动螺线电磁铁,使电磁铁支撑针在5 ms内移动30 mm,悬浮电极在撤去支撑的5 ms内自由落体125 m;同步控制采用螺线电磁铁线圈信号作为同步控制初始信号,对该信号延时5 ms,触发闪光二号的前级触发源,启动闪光二号主机工作,实现螺线电磁铁与闪光二号主机的同步。使用该套支撑控制系统用于串级二极管前期研究,初步实现了两级间隙串联工作。     

固液悬浮体系下超声波浓度测量技术进展

在工业生产和科学实验中,固液悬浮体系是一种非常重要的流体类型,其浓度与均匀性变化直接决定了最终制品的物理化学性能及服役稳定性,对其进行实时、原位、高精度测量具有重要意义。因为超声波技术其具有非接触、精度高、响应速度快等优点,所以本文重点介绍了基于该技术实现固液悬浮体系浓度测量的方法,回顾了其国内外发展状况,特别是对该技术在浆液混合过程监控方向的应用做出了介绍和总结。最后,对该领域的发展趋势进行了展望     

Hysteresis-induced bifurcation and chaos in a magneto-rheological suspension system under external excitation

The magneto-rheological damper(MRD) is a promising device used in vehicle semi-active suspension systems, for its continuous adjustable damping output. However, the innate nonlinear hysteresis characteristic of MRD may cause the nonlinear behaviors. In this work, a two-degree-of-freedom(2-DOF) MR suspension system was established first, by employing the modified Bouc–Wen force–velocity(F –v) hysteretic model. The nonlinear dynamic response of the system was investigated under the external excitation of single-frequency harmonic and bandwidth-limited stochastic road surface.The largest Lyapunov exponent(LLE) was used to detect the chaotic area of the frequency and amplitude of harmonic excitation, and the bifurcation diagrams, time histories, phase portraits, and power spectrum density(PSD) diagrams were used to reveal the dynamic evolution process in detail. Moreover, the LLE and Kolmogorov entropy(K entropy) were used to identify whether the system response was random or chaotic under stochastic road surface. The results demonstrated that the complex dynamical behaviors occur under different external excitation conditions. The oscillating mechanism of alternating periodic oscillations, quasi-periodic oscillations, and chaotic oscillations was observed in detail. The chaotic regions revealed that chaotic motions may appear in conditions of mid-low frequency and large amplitude, as well as small amplitude and all frequency. The obtained parameter regions where the chaotic motions may appear are useful for design of structural parameters of the vibration isolation, and the optimization of control strategy for MR suspension system.     

应用于重力测量的超导磁悬浮系统电磁特性分析

高精度重力测量是资源勘测、地球科学研究等领域研究的基础。与常规的机械式重力仪相比,超导重力仪具有极低的噪声和漂移率,并且测量精度高、工作寿命长、工作稳定性好,超导磁悬浮系统是它的核心部件。论文研究了超导重力仪磁悬浮系统结构,并对其原理及可行性进行了阐述。利用Ansoft及Opera软件对系统进行建模仿真分析,完成结构位置的优化选择。分析了系统正常运行时悬浮力、磁力梯度、电流值、间隙磁场分布等参量特征,并研究了超导球质量变化对系统测量灵敏度的间接影响。仿真结果表明,对于15g超导球磁悬浮系统,重力分辨率可以达到1nGal,且间隙磁场最大值小于超导材料临界磁场值。     

Profiles of the turbulent-exchange coefficient and suspension concentration in a system of stratified currents

The theoretical distribution of the turbulent-diffusion coefficient for a system of stratified currents is presented taking the specific features of exchange in boundary layers and in zones with a zero vertical-velocity gradient into account. The suspension-diffusion equation is solved using the obtained turbulent-viscosity distribution. The theoretical solution is tested against field measurements of the suspension-concentration distribution over the entire depth of a water body in four systems of currents.     

An active lateral suspension to a track/vehicle system using stochastic optimal control

An active suspension design to improve lateral ride quality and stability in a track/vehicle system subject to lateral track irregularity is presented. The measurement of the state variables is performed in a noisy environment, and unknown state variables of the system are estimated from the measurement data by using a Kalman filter. It is assumed that the lateral track irregularity and measurement noise are Gaussian random processes, respectively. The optimal control for the active suspension is determined by minimizing the quadratic performance index composed of the state variables and control efforts, and then the active suspension structure has a cascade feedback loop composed of the Kalman filter and the optimal controller. The numerical results indicate that the proposed active suspension provides much improved lateral ride quality and stability.     

制作磁悬浮天平的设想

设想用磁场力悬浮天平刀口,以减小刀口摩擦力;用光放大和光电电位器检测平衡位置,用灵敏电流计的电流大小和指针偏转方向稳定天平平衡状况,上述设想可提高天平的灵敏度。     

声悬浮现象的研究

分析了声波在垂直谐振腔内使物体悬浮于空中的条件与位置,给出了运用声悬浮现象测量声速的方法并实测了声速.     

Magnetorheological suspension electromagnetic brake

The magnetorheological suspension (MRS) brake is of the monoblock type. The main part of the electromagnetic brake is an electromagnet, between whose poles two MRS disks are placed. For distances between disks of 0.65×10⁻³ m±10%, revolutions of the electric motor, coupled to the electromagnetic brake, ranging between 200 and 1600 rev/min and braking powers of up to 85 W, there are no differences in revolutions between the disks of the electromagnetic brake. For fixed revolutions of the electric motor, the revolution of the parallel disk can be modified continuously by means of the intensity of the magnetic field. In all cases, the quantity of MRS is of 0.35×10⁻³ kg.     

Simple cost-efficient magnetic suspension

The problem of reducing electric losses in a magnetic suspension is considered. Specifically, the feasibility of decreasing electric losses in dynamics in addition to the well-known method of loss reduction in statics by means of permanent magnets is discussed. It is demonstrated by an example of a simple magnetic suspension with permanent magnets that, when the suspension is brought to equilibrium, the functional in the dependence of the electromagnet coil current squared reaches a minimum; i.e., electrical losses are minimized in dynamics.     

On the vibration transmission of a rolling tire on a suspension system due to periodic tread excitation

Several methods of modeling the vibration excitation of an automotive tire by its tread pattern were developed, ranging from a very simplified approach with an equivalent single point, single line scanning procedure to multi-point, multi-line scanning. This results in a periodic model, since even for a so called random tread pattern there is a periodicity corresponding to one tire revolution. Various tread profiles are explored and response spectra for forces and displacement at the suspension point are obtained and discussed. Receptances formulated in terms of the free tire shell modes are utilized. To contrast the force input type models of the tread excitation with the displacement type input of long road waves, the latter is also discussed briefly.     

Dynamic stabilization of a bistable suspension system attached to a flexible host structure for operational safety enhancement

In engineering applications, a suspension system may be attached to a flexible host structure, e.g. spacecraft truss, to provide vibration isolation for sensitive instrumentation, where the suspension and host structure dynamics are strongly coupled. For linear suspensions, a resonance normally occurs adjacent to the roll-off frequency band, which significantly and detrimentally amplifies vibration transmission. To avoid the adverse resonance for operational safety enhancement, this research proposes a nonlinear bistable suspension and evaluates its performance when attached to a flexible host structure. Dynamic models of the bistable and comparable linear suspensions attached to the host structure are formulated, and steady-state responses are predicted using analytical and numerical methods. Results show that the bistable suspension can eliminate the harmful resonance via a dynamic stabilization phenomenon, and simultaneously retains the favorable isolation performance in the roll-off bandwidth as compared to the linear suspension. Series of experimental investigations support the analytical and numerical findings and help define design guidelines for operational safety improvement.