On-line identification, flutter testing and adaptive notching of structural mode parameters for V-22 tiltrotor aircraft

New algorithms and results are presented for flutter testing and adaptive notching of structural modes in V-22 tiltrotor aircraft based on simulated and flight-test data from Bell Helicopter Textron, Inc. (BHTI). For flutter testing and the identification of structural mode frequencies, dampings and mode shapes, time domain state space techniques based on Deterministic Stochastic Realization Algorithms (DSRA) are used to accurately identify multiple modes simultaneously from sine sweep and other multifrequency data, resulting in great savings over the conventional Prony method. Two different techniques for adaptive notching are explored in order to design an Integrated Flight Structural Control (IFSC) system. The first technique is based on on-line identification of structural mode parameters using DSRA algorithm and tuning of a notch filter. The second technique is based on decoupling rigid-body and structural modes of the aircraft by means of a Kalman filter and using rigid-body estimates in the feedback control loop. The difference between the two approaches is that on-line identification and adaptive notching in the first approach are entirely based on the knowledge of structural modes, whereas the Kalman filter design in the second approach is based on the rigid-body dynamic model only. In the first IFSC design, on-line identification is necessary for flight envelope expansion and to adjust the notch filter frequencies and suppress aero-servoelastic instabilities due to changing flight conditions such as gross weight, sling loads, and air speed. It is shown that by tuning the notch filter frequency to the identified frequency, the phase lag is reduced and the corresponding structural mode is effectively suppressed and stability is maintained. In the second IFSC design using Kalman filter design, the structural modes are again effectively suppressed. Furthermore, the rigid-body estimates are found to be fairly insensitive to both natural frequency and damping factor variations and therefore stability is maintained. The Kalman filter design might be a better choice when the rigid-body dynamics are well known because no adaptation is necessary in this case.     

对提高我国造船企业国际竞争能力的建议

简要回顾了中国船舶工业18年来的发展和进步,分析了当前大中型造船厂的生产技术水平和管理现状,指出了存在的主要问题：这些正是造成我国船舶工业国际竞争能力下隆的主要原因。为了缩短同世界先进造船厂在技术水平、生产管理、成本和建造质量等方面的差距,提高造船企业在世界船舶市场中的竞争能力,提出了4点建议,供大中型造船厂领导层参考。     

计算机维修模拟训练系统的设计与实现

探索了一种在多媒体环境下进行计算机及外部设备维修教学、训练的新方法 ,介绍了计算机维修模拟训练系统的设计与实现 ,给出了主要的设计思想、总体结构及关键技术。     

信息系统生存模型的研究

本文根据信息论的定义,研究了信息系统生存与死亡的条件,结合信息系统安全工作的经验,首次提出了构筑信息系统生存模型的方法。该模型的提出与应用能使人们从大系统的角度审视信息主规划、设计、施工、测试昨运营,有助于信息系统的平安降生和茁壮成长。     

向家坝右岸电站技术供水系统运行方式研究

向家坝右岸电站前期出现过因机组停机调整技术供水系统运行方式而引起安全阀动作,导致渗漏集水井水位越限。为此,通过对安全阀动作原因的分析,引申出安全阀动作对技术供水系统运行方式的影响,并比较各种运行方式的优缺点;从而提出合理的技术供水系统运行方式。     

Sliding mode control for multi-agent systems under a time-varying topology

This paper addresses the tracking problem of a class of multi-agent systems under uncertain communication environments which has been modelled by a finite number of constant Laplacian matrices together with their corresponding scheduling functions. Sliding mode control method is applied to solve this nonlinear tracking problem under a time-varying topology. The controller of each tracking agent has been designed by using only its own and neighbours’ information. Sufficient conditions for the existence of a sliding mode control tracking strategy have been provided by the solvability of linear matrix inequalities. At the end of this work, numerical simulations are employed to demonstrate the effectiveness of the proposed sliding mode control tracking strategy.     

Robust control of robotic manipulators based on integral sliding mode

For rigid body robot manipulators, the computed torque approach provides asymptotic stability for tracking control tasks. However, the state dependent matrices needed to complete the computed torque algorithm are normally unknown and possibly too complex for a real-time implementation. This paper proposes a simple controller with computed-torque-like structure enhanced by integral sliding mode, having pole-placement capability. For the reduction of the chattering effect generated by the sliding mode part, the integral sliding mode is posed as a perturbation estimator with quasi-continuous control action provided by an additional low-pass filter. The time-constant of the latter tunes the controller functionality between the perturbation compensation and a pure integral sliding mode control, as well as between chattering reduction and system robustness. A comparative simulation study between conventional sliding mode control, integral sliding mode control, and integral sliding mode in form of a perturbation estimator for a two-link robot arm validates the proposed design.     

国产600MW超临界直流机组凝泵变频自动控制策略

为提高凝泵变频改造后凝结水系统自动投入效果,降低厂用电,提高机组效率,对凝结水系统运行方式进行深度分析的基础上,实现了凝结水系统的一键自启功能,并提出压力／水位协调控制与稳流调节的引入,较大程度地提高了凝结水自动控制系统的鲁棒性。     

改进的Allman无零能模式平面三角形单元

基于原始的带有旋转自由度的Allman单元,从转动分量定义出发,对原始的Allman单元泛函位能Ⅱp进行了一些修正,推导得到了一个新的单元.该单元成功地消除了Allman单元的主要缺陷--多余零能模式,同时保持了该单元的优点:列式简洁、精度高,给出的算例证实了改进单元的良好特性.     

论开发750 kV超高压真空断路器的必要性

简述了真空断路器的发展概况，对真空断路器与SF6断路器进行了对比分析。同时对真空断路器向750kV超高压等级发展的途径进行论述。