一种汽车磁流变半主动悬架的研制

为了改善车辆平顺性和行驶安全性,设计了一种基于单出杆式磁流变减振器的汽车半主动悬架。在分析传统的磁流变减振器力学模型的基础上,提出了一种改进的磁流变减振器多项式模型,试制了磁流变减振器样机,进行了磁流变减振器的力学特性试验,设计了半主动悬架天棚控制器、地棚控制器和LQG控制器,进行了不同控制策略的对比仿真分析,开发了磁流变半主动悬架试验测试系统,开展了该磁流变半主动悬架的LQG控制台架试验测试。结果表明,所研制的磁流变减振器耗能效果良好,能够最大限度地发挥振动衰减功能。与被动悬架相比,在4Hz和5Hz正弦激励下磁流变半主动悬架的簧载质量加速度分别降低15.80%和23.36%,在随机路面激励下簧载质量加速度降低19.46%。     

磁流变互联悬架的馈能特性及动力学性能分析

针对兼顾汽车行驶平顺性和馈能特性的需求,提出了一种新型磁流变互联悬架模型.先构建磁流变减振器力学与馈能的理论模型,并通过Simulink软件搭建磁流变减振器模型和磁流变互联悬架模型,分析影响馈能特性的主要参数;基于整车仿真模型,以30 km/h车速和一段C级路面为激励输入,对磁流变互联悬架与传统液压互联悬架进行对比仿真,分析互联悬架在实际路面激励下馈能特性和汽车行驶平顺性的变化规律.结果表明:磁流变互联悬架的减振效果更好;在满足车辆行驶平顺性需求的前提下,具有有效回收互联悬架振动能量和提高抗俯仰侧倾的能力.     

自适应磁流变悬架半主动控制研究

针对目前应用于汽车悬架系统的磁流变减振器工作时需要外部电源和控制设备的问题,设计了一种新型磁流变减振器,该减振器在无需外部电源和控制设备的条件下实现了对振动的自适应控制。研究了该减振器的结构特征和电能收集理论模型,并进行了模拟仿真。利用该减振器构建了无需外部电源和控制设备的汽车自适应磁流变悬架半主动控制系统,在1/4悬架实验台上进行了实验研究,实验结果表明,该控制系统是可行的,明显提高了汽车行驶的平顺性。     

车用新型旋转式磁流变减振器的设计与仿真

针对现有车用磁流变减振器(MRD)低频时阻尼力很小的问题,设计一种基于剪切模式的旋转式磁流变减振器,使减振器具有磁流变液用量小、低频时也具有大阻尼的性能,不仅能改善车辆的平顺性,也能提高车辆的操纵稳定性。进行了减振器的结构设计,利用ANSYS软件对磁场进行了有限元分析,以多学科优化软件ISIGHT为平台,以初步设计的减振器结构模型为对象,联合CATIA、MATLAB软件,对减振器的结构进行自动优化设计。采用SIMULINK软件对减振器外特性进行了仿真,结果表明,所设计的磁流变减振器在速度接近于零时就可达到很大的阻尼,可为车辆侧倾控制提供足够的阻尼力。     

基于磁流变减振器的汽车悬架振动控制

分析了磁流变减振器特性,为了抑制汽车磁流变悬架的振动,提出了一种含有控制级和协调级的分级模糊控制。在控制级,把天棚、地棚混合控制策略与模糊智能控制策略相结合,设计了1/4车辆垂直振动的半主动模糊智能控制器;在协调级,设计了整车控制的协调器,根据反馈变量对整车4个独立模糊智能控制器输出参数进行调整。把某微型汽车的4只被动减振器改装成磁流变减振器,搭建了磁流变悬架全车测控系统,运用设计的分级模糊控制器,进行了平顺性随机输入实车道路试验。试验结果表明对汽车磁流变悬架的垂直振动进行分级模糊控制是可行的,能有效提高汽车的乘坐舒适性和操纵稳定性。     

磁流变减振器对军用越野车平顺性及操稳性的影响

针对军用越野汽车在坏路面行驶中平顺性及操稳性提升的问题,首先建立了设计的一款单出杆双筒双线圈磁流变减振器的理论模型,经过理论仿真和台架试验研究了其示功特性和阻尼特性;设计了基于模糊算法的八板块控制算法,分别在B级路面、D级路面、波形路面上进行了平顺性试验,结果表明和被动减振器相比,驾驶员处振动强度下降达(14～20)%。在蛇形试验中,车身侧倾角、侧向加速度和横摆角速度下降幅值达(10～40)%。在制动试验中车身俯仰角下降幅值达(30～42)%。通过整车试验说明研制的单出杆双筒双线圈磁流变减振器以及控制策略对于提高军用越野汽车的平顺性和操稳性是可行的、有效的。     

磁流变减振器建模与试验

建立较为精确的磁流变减振器阻尼力模型是设计控制策略并获得良好控制效果的关键。基于流体动力学理论和磁流变液流变特性,对阻尼通道内磁流变液进行流体动力学分析,详细推导磁流变减振器阻尼力模型。结合阻尼通道处磁场有限元分析,完善阻尼力模型。最后试验测试自制磁流变减振器在不同励磁电流和不同活塞速度下的示功特性和速度特性,利用试验数据对模型进行系数辨识,建立磁流变减振器简化力学模型。研究结果表明,励磁电流小于0.8 A时,输出阻尼力试验值与计算值较吻合,当励磁电流增大,阻尼力试验值与计算值最大相差约100 N,计算值相对于试验值的误差在19%以内,该简化力学模型能描述磁流变减振器的基本力学特性,能为半主动悬架控制研究提供理论指导。     

磁流变液减振器的结构设计与性能研究

文中分析了3种工作模式的磁流变液减振器,分别是流体模式、剪切模式和挤压模型;设计了一种新型的基于混合模式的磁流变液减振器,并搭建了一套数据采集系统,包括数据采集卡、传动系统、Labview软件等,对磁流变液减振器的力学性进行了研究,测试结果表明,随着外加磁场强度的增加,磁流变液减振器的阻尼力增加较为明显。     

电机充当动力吸振器的轮边驱动系统研究

轮边电驱动系统具有传动高效、结构紧凑的优点,但也存在由于非簧载质量较大而影响平顺性、操稳性的问题。以一种将轮边电机充当动力吸振器的轮边减速式驱动系统为对象进行分析。该系统通过将电机转化为动力吸振器,既减小了簧下质量,又改善了电动汽车的平顺性及接地性。     

一种新型径向内通道式磁流变减振器的研究

针对改善磁流变减振器的磁场利用率及减振效果,提出了一种沿环形径向通道产生磁流变效应的MR减振器,并对其结构及磁路进行了完整的设计。此外,根据电磁学和磁流变流体动力学理论,利用相关工程仿真软件对减振器外特性进行了仿真分析,与相同活塞体积下传统的磁流变减振器相比,阻尼力明显提高,而且可调范围广,由此验证了该减振器设计的合理性。     

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.