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A dynamic signal is introduced and adaptive nonlinear damping terms are used to restrain the effects of unmodeled dynamics, nonlinear uncertainties and unknown bounded disturbances.


Nonlinear optimal predictive controller for static var compensator to improve power system damping and to maintain voltage


The main objectives of this paper are to simultaneously improve power system damping and to maintain voltage at the static var compensator (SVC) location bus simultaneously.


The ideas of adaptive nonlinear damping and changing supply functions were used to counteract the effects of parameter and nonlinear uncertainties, unmodeled dynamics and unknown bounded disturbances.


The results, based on the dynamic properties calculation of a typical mechanical spiral seal, such as stiffness coefficients and damping coefficients, exert the influence of the mechanical seal on the rotorbearing system of the highspeed machinery.

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 This paper is mainly devoted to: (1) the description of the special features of the equations of pressure, equations of flow and resistance and the calculations of the performances of the journal bearings under turbulent conditions; (2) the comparison between the performances of the elliptic bearings under turbulent conditions and those under laminar conditions. The comparison shows that with the same eccentricity the load capacities for the turbulent operation are larger, the stiffness and damping of... This paper is mainly devoted to: (1) the description of the special features of the equations of pressure, equations of flow and resistance and the calculations of the performances of the journal bearings under turbulent conditions; (2) the comparison between the performances of the elliptic bearings under turbulent conditions and those under laminar conditions. The comparison shows that with the same eccentricity the load capacities for the turbulent operation are larger, the stiffness and damping of the oil film are greater and stability conditions are basically the same. With the same coefficients of load capacities, the oil flow for the turbulent operation will be a little greater or smaller, the power losses and temperature rises will be about thrice larger and the regions of stability will be slightly narrower. Thus the data for laminar operation may be used to estimate the stability performances for turbulent operation in case of lack of the turbulent data; (3) a comparison among several theories of the turbulent lubrication developed abroad more recently by Constantinescu, Ng and Pan, Aoki and Harada and Hirs. These theories have been examined and analysed. The result shows that the theory put forward by Aoki and Harada is the best of all. On the other hand the Hirs Theory is obviously unreasonable when it is used with large eccentricities; (4) suggestions and recommendations made to the manufacturer concerned: recommending the length diameter ratio should be chosen as 0.75, the elliptic ratios should be chosen between 0.5 and 2/3 and some kinds of grooves for oil outflow should be made in the region of the oil film rupture to reduce power losses; (5) a preliminary disoussion on the rational criteria for determining the flow regime in the oil film of an elliptio bearing. The materials in the paper may prove helpful in designing, calculating and experimenting with bearings for turbulent operation.  本文主要介绍:(1)紊流工况下椭圆轴承的方程(雷诺、流量和阻力方程),计算框图以及计算中的几点考虑:紊流系数的选取;油膜破裂区阻力的考虑;紊流系数中的局部雷诺数R_h值;紊流流道中出现层流段的考虑等。(2)紊流工况和层流工况轴承性能差异分析。(3)紊流工况椭圆轴承的性能曲线和分析。(4)对某机组用椭圆轴承结构、参数的建议。  Previously in the analysis of helicopter "Ground Resoance" in the design stage, a dynamic model with one degree of freedom which has different parameters in two separate frequency regions was generally adopted to describe the lateral dynamic Characteristics of the hub center of the body of a singlerotor helicopter with hinged blades. But the tests of two singlerotor helicopters showed that the dynamic Characteristics of such a model were inconsistent with the results of the the test in high frequency region.In... Previously in the analysis of helicopter "Ground Resoance" in the design stage, a dynamic model with one degree of freedom which has different parameters in two separate frequency regions was generally adopted to describe the lateral dynamic Characteristics of the hub center of the body of a singlerotor helicopter with hinged blades. But the tests of two singlerotor helicopters showed that the dynamic Characteristics of such a model were inconsistent with the results of the the test in high frequency region.In this paper, a model with two degrees of freedom whose coupled damping is neglected is adopted, and the calculated results show that its dynamic characteristics basically accord with the results of the test. With dimensionless frequency and Nyquist stability criteron, a "Ground Resonance" criterion is obtained, upon which to analyse the influense of the model parameters on the "Ground Resonance" .The results mentioned above can also be used as a guide to control modal parameters for avoiding "Ground Resonance" in the design stage.  以往在设计阶段,对铰接式单旋翼直升机作“地面共振”分析时,机体桨毂中心横向动力学特性一般分频段采用单自由度动力学模型。但是两架单旋翼直升机的试验表明,这种模型在高频段和试验结果不符。本文则采用不计模态间耦合阻尼的二自由度模型,其动力学特性与试验结果基本符合。 频率无因次化后利用Nyquist稳定准则给出了铰接式单旋翼直升机“地面共振”的判别公式。据此分析了模态参数对“地面共振”的影响。 以上结果可供设计阶段控制模态参数、排除“地面共振”参考。  The purpose of this paper is first to discuss how relative damping coefficient of the system is selected with minimum R. M. S acceleration of equipment response for the "white noise" or "pseudowhite noise" random excitation. The calculation method of natural frequency of the system is then discussed with minimum R. M. S acceleration of equipment response for allowable maximum displacement. Finally, It's introduced simply to acquire the datas under sine vibration for dispose of the design on random condition... The purpose of this paper is first to discuss how relative damping coefficient of the system is selected with minimum R. M. S acceleration of equipment response for the "white noise" or "pseudowhite noise" random excitation. The calculation method of natural frequency of the system is then discussed with minimum R. M. S acceleration of equipment response for allowable maximum displacement. Finally, It's introduced simply to acquire the datas under sine vibration for dispose of the design on random condition and to illustrate this process.  本文首先讨论了在“白色”或“近似白色”随机激励下,使设备响应均方根加速度最小时,系统的相对阻尼系数应如何选取。然后讨论了在设备最大允许位移情况下,使设备响应均方根加速度最小时,系统的固有频率的计算方法。最后简单介绍了用正弦振动条件下获得的数据,来处理随机条件下的设计。并举例说明了这个过程。   << 更多相关文摘 
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