An energy-saving nonlinear position control strategy for electro-hydraulic servo systems

The electro-hydraulic servo system (EHSS) demonstrates numerous advantages in size and performance compared to other actuation methods. Oftentimes, its utilization in industrial and machinery settings is limited by its inferior efficiency. In this paper, a nonlinear backstepping control algorithm with an energy-saving approach is proposed for position control in the EHSS. To achieve improved efficiency, two control valves including a proportional directional valve (PDV) and a proportional relief valve (PRV) are used to achieve the control objectives. To design the control algorithm, the state space model equations of the system are transformed to their normal form and the control law through the PDV is designed using a backstepping approach for position tracking. Then, another nonlinear set of laws is derived to achieve energy-saving through the PRV input. This control design method, based on the normal form representation, imposes internal dynamics on the closed-loop system. The stability of the internal dynamics is analyzed in special cases of operation. Experimental results verify that both tracking and energy-saving objectives are satisfied for the closed-loop system.     

3G用户细分研究

对3G用户的细分方法及3G目标市场的定位进行了初步的研究，提出了3G用户细分的体系框架和3G目标市场定位的考虑要素及初步的定位建议。     

Precision measurement of energy and position resolutions of the BTeV electromagnetic calorimeter prototype

The energy dependence of the energy and position resolutions of the electromagnetic calorimeter prototype made of lead tungstate crystals produced in Bogoroditsk (Russia) and Shanghai (China) is presented. These measurements were carried out at the Protvino accelerator using a 1–45 GeV electron beam. The crystals were coupled to photomultiplier tubes. The dependence of energy and position resolutions on different factors as well as the measured electromagnetic shower lateral profile are presented.     

地面油管漏失定量测试方法探讨

对油管漏失进行定量测试的方法确定具体漏失位置。方法运用双频道回声探仪探测动液面的原理和工作方法，根据油管漏失形成的死油坏在测试曲线上出现特殊波位置判断油管漏失位置。结果：经过７０多井次的现场试验，该方法具有较高的准确性和可靠性。结论：利用特殊波可以有效监测油管漏失，并具有推广使用价值。     

位置灵敏塑料探测器阵列

本文描述了一个有效探测面积为100×70cm~2的位置灵敏塑料闪烁探测器阵列,它由两条100×5×1cm和6条100×10×1cm的Pilot U型塑料闪烁体组成。用~(252)Cfα放射源测得10cm宽的闪烁体的时间分辨、位置分辨和能量分辨分别为740ps,5.7cm和60％;5cm宽的闪烁体分别为610ps,4.7cm和40％。     

Position synchronization of multiple motion axes with adaptive coupling control

A new control approach to position synchronization of multiple motion axes is developed, by incorporating cross-coupling technology into adaptive control architecture. The control strategy is to stabilize position tracking of each axis while synchronizing its motion with other axes’ motions so that differential position errors amongst axes converge to zero. The proposed adaptive controller and parameter estimator employ coupling control by feeding back position errors and differential position errors, and have been realized to guarantee asymptotic convergence to zero of both position and synchronization errors. Simulations conducted on a multi-axis motion control system demonstrate the effectiveness of the method.     

Operating experience from the ehecatl wind turbines

This paper presents a summary of the mechanical features and the medium term operating experience from three small horizontal axis wind energy conversion systems covering a range of 500 to 5000 Watt, intented for rural and isolated communities. These turbines have a new regulator which reduces gyroscopic loads, is easy to adjust and could be manufactured stronger and in smaller sizes than the conventional tail vanes. It is concluded that is feasible to build cheaps and reliable wind turbine generators with an acceptable efficiency employing common-use elements, but is needed a careful and optimized design.     

开关DC—DC变换器并联运行问题的研究

开关直流电源并联运行在许多场合应用。每一路电源输出阻抗的不一致性使每一路输出电流难以均衡，影响了系统的可靠性。本文提出了一种双回路ＤＣ—ＤＣ变换器的控制方案。由于采用电压环（外环）和电流环（内环）两环结构的双回路控制模式，变换器输出电流得到了有效控制，便于多个ＤＣ—ＤＣ变换器输出直接并联，从而实现了模块化，具有一定的实用性     

交变光源型位敏器件应用技术

在利用直流光源型半导体位敏器件（ＰＳＤ）进行测量时，常因环境光强的改变而引起误差。本文介绍的交变调制光源及其相应的ＰＳＤ光电信号处理电路，可大大地降低和消除杂散光对测量的影响。     

基于二阶矩阵微分方程的机械振动系统线性二次型调节器设计

本文讨论机械振动系统线性二次型状态调节器（LQR）问题，直接针对系统二阶运动微分方程，性能指标为一个依赖于二阶导数的泛函。由欧拉-拉格朗日方程得出一个系统矩阵增广的二阶线性微分方程，指出该方程稳定的特征对就是最优控制振动系统闭环特征对，并给出求解最优控制状态反馈矩阵的方法，另外，由本文方法还可得出基于速度和加速度反馈的最优控制反馈矩阵。这里不涉及求解代数矩阵Riccati方程。