风电机组传动链动力响应特性与支撑系统影响

本文以某项风电机组为基本研究对象,对传动链刚柔耦合的多体动力学仿真模型进行研究分析。研究结果表明,支撑系统对振动能量通常分布在发电机壳体齿轮、箱体的模态影响程度特别大,科学合理的支撑系统高度设计有利于降低传动链共振风险出现概率,而且谐振引起的零部件振动速度偏差程度非常大,增大齿轮箱弹性支撑高度,降低发电机的弹性支撑高度,能够降低传动链振动水平。

牵引式弹力特性转换桥的特征与分类

通过对牵引式弹力特征转换桥典型机构传动特征的分析，提出了分类方案，以机械配重为例说明应用方式，对相关的产品设计有指导意义。

园林球形灌木修剪机的设计研制

园林球形灌木修剪机主要对灌木进行球面修剪,园林球形灌木修剪机的传动机构,即空间双联偏心轮右侧的齿轮及偏心轮与左侧的齿轮及偏心轮大小相等、形状一样、偏心相反。空间双联偏心轮转动时,上连杆、下连杆随之做空间摆动,从而使工作部件上圆弧弯刀、下圆弧弯刀上下往复作圆弧运动。园林工人只要手持园林球形灌木修剪机,围着灌木走一圈,即可将灌木上半部修剪成半球形,或将灌木的下半部修剪成半球形。

Kinetic characteristics of coal gas desorption based on the pulsating injection

In order to understand the kinetic characteristics of coal gas desorption based on the pulsating injection （PI）, the research experimentally studied the kinetic process of methane desorption in terms of the PI and hydrostatic injection （HI）. The results show that the kinetic curves of methane desorption based on PI and HI are consistent with each other, and the diffusion model can best describe the characteristics of meth- ane desorption. Initial velocity, diffusion capacity and ultimate desorption amount of methane desorption after P! are greater than those after HI, and the ultimate desorption amount increases by 16.7-39.7%. Methane decay rate over the time is less than that of the HI. The PI influences the diffusion model param- eters, and it makes the mass transfer Biot number B＇_i decrease and the mass transfer Fourier series F＇_0 increase. As a result, PI makes the methane diffusion resistance in the coal smaller, methane diffusion rate greater, mass transfer velocity faster and the disturbance range of methane concentration wider than HI. Therefore, the effect of methane desorption based on PI is better than that of HI.

Dynamic Characteristics of Growing Modes of Raman Instability from Intense Laser Beam Propagating Through Plasma

An essential dispersion relation,which can describe the dynamic properties of stimulated Raman scattering instability as a laser beam propagates through plasmas,is derived analytically.The development of growth mode,angle distribution,and temperature dependence of the instabilities are presented by solving this dispersion relation numerically.A significant dynamic characteristic has been revealed that the temperature increasing of the electron would result in redshift of scattered spectrum at high laser intensities.Furthermore,a novel modulational instability with double-peak temporal structure appears in a limited density region because of the coupling of scattered upshift and downshift waves.

A bearing fault diagnosis method based on sparse decomposition theory

The bearing fault information is often interfered or lost in the background noise after the vibration signal being transferred complicatedly, which will make it very difficult to extract fault features from the vibration signals. To avoid the problem in choosing and extracting the fault features in bearing fault diagnosing, a novelty fault diagnosis method based on sparse decomposition theory is proposed. Certain over-complete dictionaries are obtained by training, on which the bearing vibration signals corresponded to different states can be decomposed sparsely. The fault detection and state identification can be achieved based on the fact that the sparse representation errors of the signal on different dictionaries are different. The effects of the representation error threshold and the number of dictionary atoms used in signal decomposition to the fault diagnosis are analyzed. The effectiveness of the proposed method is validated with experimental bearing vibration signals.

Gustiness and coherent structure under weak wind period in atmospheric boundary layer

Statistical analysis of turbulent and gusty characteristics in the atmospheric boundary layer under weak wind period has been carried out.The data used in the analysis were from the multilevel ultrasonic anemometer-thermometers at 47 m,120 m,and 280 m levels on Beijing 325 m meteorological tower.The time series of 3D atmospheric velocity were analyzed by using conventional Fourier spectral analysis and decompose into three parts:basic mean flow(period > 10 min),gusty disturbances(1 min < period < 10 min)and turbulence fluctuations(period < 1 min).The results show that under weak mean wind condition:1)the gusty disturbances are the most strong fluctuations,contribute about 60% kinetic energy of eddy kinetic energy and 80% downward flux of momentum,although both the eddy kinetic energy and momentum transport are small in comparison with those in strong mean wind condition;2)the gusty wind disturbances are anisotropic;3)the gusty wind disturbances have obviously coherent structure,and their horizontal and vertical component are negatively correlated and make downward transport of momentum more effectively;4)the friction velocities related to turbulence and gusty wind are approximately constant with height in the surface layer.

Controllable Optical Solitons in Optical Fiber System with Distributed Coefficients

We present how to control the dynamics of optical solitons in optical fibers under nonlinearity and dispersion management, together with the fiber loss or gain. We obtain a family of exact solutions for the nonlinear Schrfidinger equation, which describes the propagation of optical pulses in optical fibers, and investigate the dynamical features of solitons by analyzing the exact analytical solutions in different physical situations. The results show that under the appropriate condition, not only the group velocity dispersion and the nonlinearity, but also the loss/gain can be used to manipulate the light pulse.

Hydrodynamic and Heat Transfer Characteristics of Magnetofluidized Beds

To investigate the flow and heat-transfer behaviors of magnetofluidized beds, an experimental facilitywas designed. A constant uniform magnetic field is produced by a Helmholtz electromagnet. The nature of fiuidization and heat-transfer characteristics of a horizontal electrically heated tube immersed in the bed were measured. The bed material is iron shots. Depending upon the intensity of magnetic field (weak, moderate and strong), the bed pressure drop and heat transfer coefficient are classified into three ranges of magnetic fields. The range of variation of maximum magnetic-field intensity is from 0 to about 20690 A/m.