机械式离心调速器系统混沌的线性反馈反控制

建立了机械式离心调速器系统的动力学方程，求出了系统的平衡点。利用系统的相图分析了给定参数下自治系统及非自治系统的运动状态，用Poincare映射图分析了非自治系统混沌的形成过程。利用线性反馈反控制方法实现了自治系统及非自治系统混沌的反控制，将自治系统及非自治系统的周期运动利用适当的控制强度反控制到混沌运动轨道。     

一类单边刚性碰撞系统的分岔与混沌控制

研究了一类单自由度刚性碰撞系统的分岔和混沌运动。建立系统周期运动的Poincaré映射,通过数值仿真揭示了系统通过倍化分岔通向混沌的道路和系统的周期运动、混沌运动。最后运用外加恒定载荷控制方法对系统的混沌运动进行了有效的控制,使系统达到不同的周期轨道。     

含双侧约束碰撞振动系统的OGY混沌控制

以单自由度含双侧约束碰撞振动系统为研究对象,数值仿真了系统1-1-1周期运动经周期倍化分岔和Grazing分岔向混沌转迁的路径;给出了OGY控制方法的原理和步骤。利用混沌运动对参数微小扰动的敏感性和混沌轨道的遍历性质,选择嵌入混沌吸引子中的一个不稳定不动点作为控制目标,当系统状态访问目标不动点的微小邻域时,给系统参数施加微小扰动,把混沌控制到期望的目标轨道。仿真结果表明,在极短的时间内系统的混沌得到了抑制。     

机械式离心调速器系统混沌的非线性反馈反控制

根据拉格朗日方程建立了机械式离心调速器系统的动力学方程,求出了系统的平衡点,利用系统的相图分析了给定参数下自治系统及非自治系统的运动状态,用Poincaré映射图分析了非自治系统混沌的形成过程。利用非线性反馈反控制方法实现了自治系统及非自治系统混沌的反控制,将自治系统及非自治系统的周期运动利用适当的控制强度反控制到混沌运动轨道。     

碰撞振动系统中两种混沌门槛值的判据

以一类简单的碰撞振动系统为例，验证了两种混沌门槛值判据的等价性。即非扰动情形具有广义同宿轨道，扰动为鞍型周期运动的碰撞振动系统中，如果相对于该鞍型周期解的相对流形上仍存在同宿轨道，则它与Ｐｏｉｎｃａｒｅ截面上稳定流形和不稳定流形横截相交是等价的。因而它可作为Ｓｍａｌｅ马蹄意义下混沌门槛值的判据，但相对流形上的判据在碰撞振动系统中显得直观简洁。     

离心调速器系统的混沌及速度反馈控制

建立离心调速器反馈控制系统的动力学方程,利用系统的相图和Poincaré映射图分析系统的混沌形成过程.通过对离心调速器反馈控制系统增加一个速度反馈控制器,利用它控制系统从混沌运动转化为周期运动.数值仿真表明,该控制方法在离心调速器反馈控制系统的混沌控制中的有效性与可行性,可利用适当的控制强度镇定系统中不稳定的周期轨道.     

Bonhoeffer-van der Pol方程中双吸引子的混沌控制

基于延时反馈混沌控制方法和相空间压缩法,提出一种改进的延时反馈混沌控制方法。该方法不仅可用于单个吸引子混沌系统的控制,而且由于克服了Pyragas控制方法的不能简便地将混沌系统稳定到嵌入在不同混沌吸引子内周期轨道的不足,也可以用于多个混沌吸引子混沌系统的控制。以Bonhoeffer-van der Pol系统为例,数值验证此改进方法用于两个混沌吸引子系统控制的有效性,结果表明,在延时反馈控制中增加适当的相空间限制器,可以快捷地将系统稳定在期望的周期轨道上。     

基于神经网络模型预测控制的混沌运动的研究

为了实现混沌运动的控制,应用神经网络模型预测控制的策略.首先通过系统辨识建立要控制的混沌系统的神经网络模型,并设计出神经网络模型预测控制器,然后通过该控制器对混沌运动进行预测控制,使混沌吸引子中的不稳定周期轨道被镇定到不动点.最后借助MATLAB平台进行数字仿真,结果表明该控制方法对混沌控制是有效的.     

含时变啮合刚度的间隙非线性齿轮系统的混沌控制

基于含时变啮合刚度和间隙非线性单级齿轮系统的动力学模型,分析了系统响应的动态特性。针对系统在部分参数区域发生的混沌运动,运用OGY控制原理,以混沌吸引子内部不稳定周期轨道为目标,通过对系统的外激励参数实施连续的小扰动,使系统的轨道始终落在未加扰动的鞍点轨道的稳定流形上,从而实现了系统运动的稳定化。     

基于神经网络模型预测控制的混沌运动的研究

为了实现混沌运动的控制,应用神经网络模型预测控制的策略。首先通过系统辨识建立要控制的混沌系统的神经网络模型,并设计出神经网络模型预测控制器,然后通过该控制器对混沌运动进行预测控制,使混沌吸引子中的不稳定周期轨道被镇定到不动点。最后借助MATLAB平台进行数字仿真,结果表明该控制方法对混沌控制是有效的。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.