GENERATION OF ASYMMETRIC F-v CHARACTERISTICS FOR SYMMETRIC MR DAMPERS

An asymmetric damping force generation algorithm is originally proposed to yield the asymmetric force-velocity characteristics for the symmetric magneto-rheological (MR) dampers. The command current is formulated in an asymmetric manner to excite the symmetric MR dampers by employing the "on-off" control law in response to the direction of velocity, and a smooth modulation function is developed without phase shift to suppress strong transients in the damping forces caused by the current-switching discontinuity. The effectiveness of the proposed algorithm is evaluated by analyzing the dynamic responses of a quarter-vehicle suspension system with a symmetric MR-damper by modulating the command current into the asymmetric manner. The simulation results show that the proposed algorithm could achieve a better compromise between the conflicting requirements of the asymmetric damping force ratio and the force-velocity curve smoothness, and the asymmetric damping MR-suspension design can ideally improve the road holding and ride performances of vehicle motion. The proposed algorithm can be generally incorporated with a controller synthesis to realize an intelligent vehicle suspension design with the symmetric MR dampers.     

SEMI-ACTIVE CONTROL OF VEHICLE SUSPENSION WITH MAGNETO- RHEOLOGICAL DAMPERS： PART Ⅰ ——CONTROLLER SYNTHESIS AND EVALUATION

A modified skyhook-based semi-active controller is proposed for implementing an asymmetric control suspension design with symmetric magneto-rheological （MR） dampers. The controller is formulated in current form, which is modulated by integrating a continuous modulation and an asymmetric damping force generation algorithms, so as to effectively minimize switching and hysteretic effects from the MR-damper. The proposed controller is implemented with a quarter-vehicle MR-suspension model, and its relative response characteristics are thus evaluated in terms of defined performance measures under varying amplitude harmonic, rounded pulse and random excitations. The sensitivity of the semi-active suspension performance to variations in controller parameters is thoroughly evaluated. The results illustrate that the proposed skyhook-based asymmetric semi-active MR-suspension controller has superior robustness on the system parameter variations, and can achieve desirable multi-objective suspension performance.     

SEMI-ACTIVE CONTROL OF VEHICLE SUSPENSION WITH MAGNETO- RHEOLOGICAL DAMPERS: PART Ⅰ-CONTROLLER SYNTHESIS AND EVALUATION

A modified skyhook-based semi-active controller is proposed for implementing an asymmetric control suspension design with symmetric magneto-rheological (MR) dampers. The controller is formulated in current form, which is modulated by integrating a continuous modulation and an asymmetric damping force generation algorithms, so as to effectively minimize switching and hysteretic effects from the MR-damper. The proposed controller is implemented with a quarter-vehicle MR-suspension model, and its relative response characteristics are thus evaluated in terms of defined performance measures under varying amplitude harmonic, rounded pulse and random excitations. The sensitivity of the semi-active suspension performance to variations in controller parameters is thoroughly evaluated. The results illustrate that the proposed skyhook-based asymmetric semi-active MR-suspension controller has superior robustness on the system parameter variations, and can achieve desirable multi-objective suspension performance.     

不对称信息下闭环供应链的合作机制分析

利用博弈论中的委托代理理论和显示原理,在回收固定投资的规模参数信息不对称下,研究了闭环供应链的合作机制,并与对称信息下的合作机制进行了比较,最后通过算例进行了分析。研究结果表明,在对称信息和不对称信息下,制造商都可以通过向零售商收取与制造成本相同的批发价和一定的特许经营费达到合作目的,但在对称信息下制造商索取全部合作后的超额利润,零售商只获得分散化决策下的利润,在不对称信息下,有信息优势的零售商可获得更多的利润。     

基于拓扑网络的轧机扭振分析计算

为能进行轧机主传动系统复杂分支结构的扭振分析和计算,研究了一种基于拓扑网络的扭振分析模型,模型中同时考察了内外阻尼的影响。求解模型的单支和多分支情况的动态响应。对比传统方法,文中的计算算例和仿真模拟都取得了很好的一致性。同时该法的表达便于作为控制系统的输入,为大型复杂机械主传动系统的实时主动控制和故障诊断监测开辟了一种容易实现的工程途径,也为工程中分析解决复杂多分支传动扭振及其类似问题提供了新方法。     

Isogeometric topology optimization based on energy penalization for symmetric structure

We present an energy penalization method for isogeometric topology optimization using moving morphable components (ITO–MMC), propose an ITO–MMC with an additional bilateral or periodic symmetric constraint for symmetric structures, and then extend the proposed energy penalization method to an ITO–MMC with a symmetric constraint. The energy penalization method can solve the problems of numerical instability and convergence for the ITO–MMC and the ITO–MMC subjected to the structural symmetric constraint with asymmetric loads. Topology optimization problems of asymmetric, bilateral symmetric, and periodic symmetric structures are discussed to validate the effectiveness of the proposed energy penalization approach. Compared with the conventional ITO–MMC, the energy penalization method for the ITO–MMC can improve the convergence rate from 18.6% to 44.5% for the optimization of the asymmetric structure. For the ITO–MMC under a bilateral symmetric constraint, the proposed method can reduce the objective value by 5.6% and obtain a final optimized topology that has a clear boundary with decreased iterations. For the ITO–MMC under a periodic symmetric constraint, the proposed energy penalization method can dramatically reduce the number of iterations and obtain a speedup of more than 2.     

SMA压电复合减震装置电力学性能及其本构模型

针对形状记忆合金(shape memory alloy,简称SMA)阻尼器控制力不可调和压电摩擦阻尼器启动难的问题,提出了一种SMA单元和压电摩擦单元依次工作的复合减震装置,进行了相应的电力学性能试验,分析了位移幅值、激励频率和输入电压对复合减震装置力学性能的影响。在试验结果的基础上,建立了以速率符号、电压和位移为神经元输入的优化反向传播(back propagation,简称BP)神经网络预测模型。结果表明,该复合减震装置的滞回曲线饱满且基本对称,工作性能稳定,随着电压的增大,滞回环的面积逐渐增大,耗能能力不断增强。在位移幅值为12mm、电压为120V下,单圈耗能量提高了138.23%,等效阻尼比提高了94.23%。两种智能材料经过合理组合而成的SMA压电复合减震装置耗能好、适应性强,可以更好地用于工程结构的减震控制。BP网络预测模型能够较好地跟踪SMA类复合减震装置的输出,而优化后的BP网络更加稳定,能够快速得到误差更小的网络模型,该神经网络算法为SMA类复合减震装置本构模型的建立和应用提供了新途径。     

ADAPTIVE CONTROLLER AND ITS APPLICATION IN FORCE SYSTEM OF ASYMMETRIC CYLINDER CONTROLLED BY SYMMETRIC VALVE

Partial pressure, system vibration and asymmetric system dynamic performance exit in asymmetric cylinder controller by symmetric valve hydraulic system. To solve this problem in the force control system, model reference adaptive controller is designed using equilibrium point stability theory and output error equation polynomial. The reference model is selected in such a way that it meets the system dynamic performance. Hardware configuration of asymmetric cylinder controlled by asymmetric valve hydraulic system is replaced by intelligent control algorithm, thus the cost is lowered and easy to application. Simulation results demonstrate that the proposed adaptive control sheme has good adaptive ability and well solves asymmetric dynamic performance problem. The designed adaptive controller is fairly robust to load disturbance and system parameter variation.     

A hybrid control approach for pole assignment to second-order asymmetric systems

Structural modification in the form of adding mass and stiffness (and sometime damping) as a means of passive control to assign desirable poles and zeros for symmetric systems has been extensively studied. Pole and zero assignment by means of active control has also attracted much research. Assignment of poles to stabilise second-order damped asymmetric dynamic systems using structural modifications and state-feedback control, respectively, was carried out recently. It was found that the former is often incapable of assigning complex poles with negative real parts for asymmetric systems while the latter is nearly always capable of doing that. However, the gains required to assign poles with negative real parts using active control can be high.This paper presents a two-stage passive (structural modification) and active (state-feedback) combined control approach to assign complex poles with negative real parts to damped asymmetric dynamic systems to suppress flutter instability. This hybrid approach is motivated by possible restriction to gains of actuators and cost of sole active control. Simulated numerical examples show its effectiveness over the individual control strategies of passive control and active control.     

网络数据DES加密算法研究与实现

介绍了几种常见的网络数据加密方法,分析了对称加密与不对称加密的优缺点,结合实际详细阐述了DES对称加密算法运算与密钥计算,并在VC++6.0中实现了该算法,论证了该算法加密的快速性与可行性。     

基于进化神经网络的电火花铣削加工电极损耗预测

针对电火花铣削加工的时变非线性特性,提出基于神经网络的电火花铣削加工电极损耗预测模型,利用该网络预测加工速度和工具的相对损耗,从而可在加工中实时计算出工具实际损耗量,为实现电极损耗的在线动态补偿打下基础。针对神经网络传统训练算法-BP算法的不足,提出了一种自适应调节变异率和变异量的进化算法来优化网络权值和网络结构,提高了网络的逼近精度和进化速度。     

Multi-formation control of nonlinear leader-following multi-agent systems

This paper deals with the multi-formation control problem for nonlinear leader-following multi-agent systems. Both the fixed topology case and the switching topology case are considered. The neighbor-based multi-formation control protocols are proposed under the assumption that for one subgroup, the total information received from other subgroups is zero. Then, based on the Lyapunov stability theory combined with the algebraic graph theory, sufficient conditions are established to ensure that the leader-following multi-agent systems with nonlinear dynamics can reach and maintain the desired multi-formation control. Finally, simulation examples are provided to illustrate the effectiveness of the theoretical results.     

质量控制图在线智能诊断分析系统

在计算机集成制造系统环境下，为了有效实现工序质量控制，提出了质量控制图的在线智能诊断分析系统框架，它由控制图模式识别、参数估计、专家诊断分析系统和加工参数调整系统四个模块组成。在该系统中，采用了一种适用于模式识别与分类的新型神经网络模型——局部有监督特征映射网络，将其应用于该系统的控制图模式识别和参数估计中。仿真实验和应用实例表明，识别和分类结果与实际相符，并可以保证实时性。     

双输入双输出时滞系统的解耦控制方法

文章针对带有时滞环节的双输入双输出非最小相位系统提出了一种基于遗传算法的模糊解耦控制方法。该方法将遗传算法引入模糊解耦控制机制并对其进行优化,克服了传统解耦方法中由于时滞问题所带来的误差,并将其运用于空气压缩机模型,通过MATLAB仿真分析证实了这种基于遗传算法的模糊解耦方法能有效的控制开环不稳定非最小相位系统。并对其进行有效解耦。     

约束阻尼变密度材料属性合理近似插值模型全域灵敏度减振优化

针对圆柱壳约束阻尼拓扑减振优化问题,基于变密度材料属性合理近似插值模型,构建以模态损耗因子最小为优化目标的拓扑减振模型,引入振型控制因子MAC评价振型的阶跃状态,寻优迭代轻量化约束设计域内的减振优化解。推导目标灵敏度的插值模型,演算全域优化求解算法,建立∞-范数的全域灵敏度拓扑变量优化准则,避免非凸优化函数的部分目标灵敏度参与优化迭代的局部优化解和跳跃。编程实现了壳构件约束阻尼结构的减振优化分析。结果表明：全域优化算法寻优域广,迭代历程稳定时间短、敷设部分阻尼材料易获得有效的减振效果。     

基于新分簇路由算法的温室监控网络节能研究

针对设施农业发展需求,根据温室结构特性,从能量高效与节点可信度方面出发,提出了一种新的3层无线传感器网络分簇路由算法。该算法分别在簇头节点的选择、簇区的形成和簇间路由通信方式上进行了改进,在簇的形成过程中同时考虑了节点的能量与位置信息,提出了新的簇头选择权值参数,并在选出的第1层簇头节点的基础上,进行阈值划分,均衡了网络的能耗与通信负载。仿真与实际应用结果表明,该算法在节点的能量消耗、网络通信流量等方面优于传统分簇路由协议,应用于温室监控项目中时,新的组网协议体积小,节省能量,均衡了各监控传感器节点的能耗负担,获得较好的拓扑结构,延长了1.5倍网络生命周期。     

IDENTIFICATION OF NON-PROPORTIONAL MODAL DAMPING MATRIX AND REAL NORMAL MODES

Equations of motion for non-proportionally damped structures cannot be decoupled by using the real normal modes. For such structures, the complex normal modes are in common use for this purpose, but for the validation of finite element mass and stiffness matrices where physical damping matrices are not available, the related experimental real normal modes must be known. In previous publications, an identification theory using the real normal modes and the non-diagonal modal damping matrix for the non-proportionally damped system and some applications with the computer code ISSPA were presented. However, the theory cannot assure the symmetry of the identified modal damping matrix, which must be theoretically symmetric. In this paper, a method for identifying the symmetric non-proportional modal damping matrix using undamped modal parameters obtained from ISSPA is presented and the validity of the method is demon-strated through both numerical and experimental examples.     

非对称轴向柱塞泵斜盘力矩特性研究

高压化轴向柱塞泵的配流盘多以非对称、具有较大死区的结构来取代对称式结构以提高增压能力。针对某航天舵机用柱塞泵对柱塞腔压力周期变化规律进行研究，进而对非对称式配流结构斜盘力矩进行了理论分析并建立了其数学模型。最后基于AMESim平台搭建了传统对称式和非对称式斜盘力矩仿真模型并在典型工况下进行了对比分析。与对称式斜盘力矩特性不同，液压力矩在非对称式斜盘力矩中不可忽略，其大小主要受系统压力的影响而与斜盘倾角无关。     

一种减小微机械加速度计振动偏移的方案

为降低敏感元件对称性较差的微机械加速度计的振动偏移,对加速度计振动偏移产生的原因和抑制方案进行研究.首先,分析了系统学模型,并得出对于不对称的敏感元件采用对称的电容检测电路时,检测电路输出和敏感元件动极板位移关系函数中存在明显偶次项系数,进而造成振动零偏;其次,讨论了力矩器的非线性,通过理论分析得出,外加静电力等效对称方案无法抑制力矩器环节的振动偏移,提出了敏感元件等效对称补偿方案以及静电力发生器等效对称化方案,通过理论分析得出该方案大大降低了敏感元件不对称带来的振动偏移;最后,对静电力对称方案和等效对称补偿方案进行了对比试验.试验结果表明,对于对称性较差的敏感元件,等效对称补偿方案在保证线性度的同时,大大减小了振动时输出均值的偏移.     

基于NARMAX模型的阀控非对称缸神经网络预测控制

针对非对称缸位置跟踪控制精度较差,提出了一种基于非线性自回归平均滑动离散模型(NARMAX)和量子粒子群算法的神经网络预测控制策略(QPSO-NNMPC)。利用NARMAX模型表示阀控非对称缸的动态模型,使用粒子群算法优化BP神经网络(PSO-BP)对阀控非对称缸系统在线预测,使用量子粒子群算法(QPSO)对目标函数非线性优化。仿真结果表明,在不同频率期望信号与变干扰力情况下,该控制策略具有良好的跟踪效果和鲁棒性。