Open Loop Saddle Point on Linear Quadratic Stochastic Differential Games

In this paper, we deal with one kind of two-player zero-sum linear quadratic stochastic differential game problem. We give the existence of an open loop saddle point if and only if the lower and upper values exist.

Open loop control of vortex-induced vibration of a circular cylinder

In this paper both numerical and experimental investigations have been carried out to suppress the vortex-induced vibration （VIV） of a circular cylinder in an electrically low-conducting fluid. The electromagnetic forces （Lorentz forces） in the azimuthal direction were generated through the mounted electrodes and magnets locally on the surface of the cylinder, which have been proved having an accelerating effect to the fluid on the surface of the cylinder. Results of computations are presented for synchronous vibration phenomenon of a cylinder at Re = 200, which are in good agreement with previous computational results. With the Lorentz forces loaded, the VIV of the cylinder has been suppressed successfully. Experimental results have also shown the same tendency and are in reasonable agreement with the numerical results.

Temperature Insensitive Open Loop Attenuation Control of a Liquid Crystal Based VOA

A patent pending open-loop liquid crystal based variable optical attenuator is introduced. The temperature dependent performance is compensated through electric monitoring and adjustment utilizing liquid crystal's opto-electronic properties.

Experiments on an Open-Loop Cycle Carbon Dioxide Refrigeration System

An open loop cycle carbon dioxide(CO2)refrigeration system is established,and the cooling performances of high-pressure CO2 under different storage conditions(25℃,30℃,and 35℃)are investigated.Moreover,the experimental mass flow rates of CO2 are compared with the theoretical values at different conditions and refrigeration capacities.The results indicate that the storage condition of CO2 has a significant impact on the refrigeration performance,and the mass flow rate of CO2 increases with the increasing storage temperature in a given refrigeration capacity.

Control-Relevant Identification Test Design for Open-Loop Experiment

An optimal experiment design (DED) with respect to the use of designing model-base controller was studied. The mean squared error at the setpoint is chosen as the performance criterion. Simple design formulas are derived based on the asymptotic theory. The signal is used for the open loop experiment. The design constraint is the power of the process signal or the process input signal. The results give guideline for identification application.

Dispersion compensation in an open-loop all-optical chaotic communication system

The optical chaotic communication system using open-loop fiber transmission is studied under strong injection conditions. The optical chaotic communication system with open-loop configuration is studied using fiber transmission under strong injection conditions. The performances of fiber links composed of two types of fiber segments in different dispersion compensation maps are compared by testing the quality of the recovered message with different bit rates and encrypted by chaotic modulation （CM） or chaotic shift keying （CSK）. The result indicates that the performance of the pre-compensation map is always worst. Two types of symmetrical maps are identical whatever the encryption method and bit-rate of message are. For the transmitting and the recovering of message of lower bit rate （1 Gb/s）, the post-compensation map is the best scheme. However, for the message of higher bit rate （2.5 Gb/s）, the parameters in communication system need to be modified properly in order to adapt to the high-speed application. Meanwhile, two types of symmetrical maps are the best scheme. In addition, the CM method is superior to the CSK method for high-speed applications. It is in accordance with the result in a back-to-back configuration system.

Instability of cylinder wake under open-loop active control

Instability of a wake controlled by a streamwise Lorentz force is investigated through a Floquet stability analysis. The streamwise Lorentz force, which is a two-dimensional control input created by an electromagnetic actuator located on the cylinder surface,adjusts the base flow to affect the three-dimensional wake instability and achieve wake stabilization and transition delay. The instability mode at a Reynolds number Re = 300 can be transformed from B to A with N = 1.0, where N is an interaction number representing the strength of the Lorentz force relative to the inertial force in the fluid. The wake flow is Floquet stable when N increases to 1.3. The spanwise perturbation wavelengths are 3.926 D and 0.822 D in the modes A and B, respectively, where D is the cylinder diameter. In addition, the oscillating amplitudes of drag and lift are reduced with the increase in the interaction number. Particle tracing is used to explore the essential physical mechanism for mode transformation. The path lines show that suppression of flow separation hinders the fluid deformation and rotation, leading to the decrease in elliptic and hyperbolic instability regions, which is the material cause of mode transformation.All of the results indicate that wake stabilization and transition delay can be achieved under open-loop active control via the streamwise Lorentz force.

Open-plus-closed-loop control for chaotic motion of 3D rigid pendulum

An open-plus-closed-loop （OPCL） control problem for the chaotic motion of a 3D rigid pendulum subjected to a constant gravitationM force is studied. The 3D rigid pendulum is assumed to be consist of a rigid body supported by a fixed and frictionless pivot with three rotational degrees. In order to avoid the singular phenomenon of Euler＇s angular velocity equation, the quaternion kinematic equation is used to describe the motion of the 3D rigid pendulum. An OPCL controller for chaotic motion of a 3D rigid pendulum at equilibrium position is designed. This OPCL controller contains two parts： the open-loop part to construct an ideal trajectory and the closed-loop part to stabilize the 3D rigid pendulum. Simulation results show that the controller is effective and efficient.

Open-loop frequency response for a chaotic masking system

In this paper, a new numerical simulation approach is proposed for the study of open-loop frequency response of a chaotic masking system. Using Chua＇s circuit and the Lorenz system as illustrative examples, we have shown that one can employ chaos synchronization to separate the feedback network from a chaotic masking system, and then use numerical simulation to obtain the open-loop synchronization response, the phase response, and the amplitude response of a chaotic masking system. Based on the analysis of the frequency response, we have also proved that changing the amplitude of the exciting （input） signal within normal working domain does not influence the frequency response of the chaotic masking system. The new numerical simulation method developed in this paper can be extended to consider the open-loop frequency response of other systems described by differential or difference equations.

PERFORMANCE OF A NEW DECODING METHOD USED IN OPEN-LOOP ALL-OPTICAL CHAOTIC COMMUNICATION SYSTEM

A new decoding method with decoder is used in open-loop all-optical chaotic communication system under strong injection condition.The performance of the new decoding method is numerically investigated by comparing it with the common decoding method without decoder.For new decoding method,two cases are analyzed,including whether or not the output of the decoder is adjusted by its input to receiver.The results indicate the decoding quality can be improved by adjusting for the new decoding method.Meanwhile,the injection strength of decoder can be restricted in a certain range.The adjusted new decoding method with decoder can achieve better decoding quality than decoding method without decoder when the bit rate of message is under 5 Gb/s.However,a stronger injection for receiver is needed.Moreover,the new decoding method can broaden the range of injection strength acceptable for good decoding quality.Different message encryption techniques are tested,and the result is similar to that of the common decoding method,indicative of the fact that the message encoded by using Chaotic Modulation(CM) can be best recovered by the new decoding method owning to the essence of this encryption technique.

Analytical solution for a class of linear quadratic open-loop Nash game with multiple players

In this paper, the Nash equilibria for differential games with multiple players is studied. A method for solving the Riccati-type matrix differential equations for open-loop Nash strategy in linear quadratic game with multiple players is presented and analytical solution is given for a type of differential games in which the system matrixcan be diagonalizable. As the special cases, the Nash equilibria for some type of differential games with particular structure is studied also, and some results in previous literatures are extended. Finally, a numerical example is given to illustrate the effectiveness of the solution procedure.

开环同步型单相并网逆变器小干扰建模与弱电网下稳定性分析

单相并网逆变器中,多采用锁相环(phase-lockedloop,PLL)型闭环同步方法,但PLL引入的低频段负阻特性不利于系统稳定性,在电网阻抗较大时并网逆变器易发生严重失稳。对此,国内外广泛开展了PLL优化或替代技术的研究。其中,开环同步(open-loop synchronization,OLS)方法的无反馈结构使得其自身是完全稳定的,近年来得到了较多关注。然而,OLS结构中非线性特性明显,如何获得准确的小干扰线性化模型仍非常困难,OLS型单相并网逆变器在弱电网下的稳定性仍不清晰。鉴于此,重点研究开环同步型单相并网逆变器小干扰建模与稳定性。借鉴谐波线性化思想,提出OLS的线性化建模方法,建立开环同步型单相并网逆变器的输出阻抗模型。在此基础上,讨论OLS型单相并网逆变器的鲁棒性。较大电网阻抗下,采用OLS的开环同步型单相并网逆变器系统仍有良好的稳定性。通过仿真和对比实验验证上述模型的准确性以及弱电网下OLS的适应性。

兆瓦级高效紧凑型核动力系统运行特性研究

为研究兆瓦级高效紧凑型核动力系统的运行特性,使用自主开发的热管堆瞬态分析程序TAPIRS(Transient Analysis code for heat Pipe and AMTEC power conversion space Reactor power System)和超临界二氧化碳布雷顿循环的瞬态分析程序SCTRAN/CO_(2)(Super Critical reactors Transient Analysis code/Carbon Dioxide)的耦合程序对其反应性、负荷、冷却水温度和流量等扰动进行了开环动态响应分析,并据此进行了控制系统设计。在此基础上,对线性变负荷、阶梯式变负荷以及甩负荷这三种变负荷运行工况进行了计算分析。结果表明:该核动力系统的转速对扰动的变化较为敏感,需要加以控制;低负荷下旁通会使压缩机流量上升,需对压缩机流量加以控制;系统在控制方案下能以6%FP(Full Power)·min^(−1)的速度实现0%~100%的负荷变动,且可以在任意负荷水平下运行;甩负荷下系统的波动时间变长,但是仍可达到新的稳态进行工作,且各参数处于安全范围内。本研究可为新型核动力系统的概念设计提供参考。

数模—动模混合仿真系统的接口建模与稳定性分析

为满足现代电力系统实时仿真的发展需求,数模-动模混合仿真系统结合实时数字仿真和物理动态模拟仿真的优点,成为现代电力系统研究的重要仿真方法。接口系统是混合仿真系统设计中的核心与难点。为了深入分析混合仿真系统的稳定性,对接口系统各个组成环节进行建模得到系统开环传递函数,分别根据劳斯判据和奈奎斯特判据研究开环传递函数中不同参数对系统稳定性的影响。理论推导表明接口系统中滤波器截止频率、接口延时和阻抗模拟比对系统的稳定性影响较大,并通过所搭建的混合仿真系统进行实验,实验结果表明不同参数对系统的稳定性影响与理论推导一致。

航天器气动角运动学及开环性能分析

对于航天器在大气中飞行的控制设计问题,由于气动角与气动力和气动力矩直接相关,因此一般采用气动角反馈.在研究稳定性等闭环性能时,需要用到气动角运动学方程.但是难以找到气动角运动学的推导方法,因此在应用时对于不同坐标系的定义缺乏灵活性.气动角运动学形式复杂,其推导具有难度.提出推导的方法,给出了气动角运动学方程,并对其开环性能进行了分析,为控制设计提供了基础.所提出的气动角运动学的推导方法,气动角运动学方程,以及开环性能分析的方法和结果,可以应用于带有大气的目标星体的气动进入的控制设计和分析中,从而为其提供了理论支撑.

基于厚壁圆筒理论的袖阀管注浆开环压力计算方法及影响因素分析

目的袖阀管注浆技术已广泛应用于地层加固、路基病害治理、地铁站渗漏水处治等众多工程领域,然而袖阀管注浆的关键技术—开环压力的确定问题目前尚未有效解决。为解决此问题,方法基于厚壁圆筒理论模型,提出任意倾斜状态下袖阀管出浆口地层应力计算方法,结合第四强度准则,建立考虑多因素综合影响的袖阀管注浆开环压力理论计算公式,并进行开环压力影响因素分析。结果结果表明,袖阀管注浆开环压力随套壳料抗压强度、套壳料与土体泊松比比值、注浆深度、地层最小与最大水平主应力比值的增大而增大,随着套壳料内外半径比、套壳料与土体弹性模量比的增大而减小。套壳料抗压强度、套壳料内外半径比、注浆深度和注浆钻孔方向对开环压力的影响较显著。注浆钻孔方向对开环压力影响较大,α一定时,开环压力随β增大而减小;β一定时,开环压力随α增大而增大。将本文建立的袖阀管注浆开环压力计算公式应用于新建大冶北至阳新铁路DK107+105框架顶进涵工程,并与现有开环压力计算方法进行对比,利用本文方法计算得到的开环压力值更接近现场实测范围,并优于现有计算方法。结论研究结果可为袖阀管注浆理论发展和现场应用提供支持。

基于硬件在环仿真的DFIG并网系统开环模式谐振风险及验证

开环模式谐振理论是阐释风电并网引起的电力系统振荡机理的研究成果,其中基于平均模型的离线时域仿真结果可信度存疑。为提升开环模式谐振的工程指导可靠度,首先基于硬件在环仿真,组建了用于验证开环模式谐振的半实物实验平台;其次建立双馈风电场并网系统的小信号模型,提出开环模式分析通用方法评估系统振荡风险;最后以两个算例进行了开环模式谐振现象的分析与实验。得到结论:硬件在环仿真的结果符合开环模式分析的结果,在开环模式谐振条件下,系统稳定性下降。留数法可以较为准确地预测系统闭环模式,系统参数的合理整定可以减小开环模式谐振带来的影响。

有源电力滤波器补偿的PI解耦控制技术研究

电网中电压和电流波形的失真会产生谐波,导致电网功率因数降低,并影响电力系统的稳定性和可靠性。为了确保电力系统的正常工作,研究了基于有源电力滤波器补偿的比例积分(PI)解耦控制技术。设计了基于二极管钳位式的有源电力滤波器模型。结合基尔霍博电压法,降低控制谐波和解除部分变量耦合。针对设备非线性产生的谐波,分析有源电力滤波器的可逆性,获得输入雅可比矩阵,以实现滤波器旋转坐标的线性化。利用变换矩阵转换转动角速向量,输入谐波的幅度,输出电流取样延迟,完成无差PI解耦控制。试验结果表明,所提技术能够有效解耦滤波器的谐波电流成分,从而补偿电网中的失真电流。该技术可以减少谐波对电力系统的整体影响,保证设备的正常运行。

基于数字检测的磁通门电流传感器

传统的自激式磁通门电流传感器通常基于平均电流法测量电流,结构复杂且测量带宽和响应时间均受滤波器截止频率的限制。文中基于占空比采样的数字检测法设计了一款面向复杂漏电流测量的传感器,使用单片机直接测量激磁信号占空比,并通过数字算法完成信号的解调与处理。文中的传感器采用开环设计,节省了滤波电路与AD转换器,降低了成本。实验表明:该传感器的带宽和响应时间性能均优于基于平均电流法的传感器。