离散辅助闭环在轧辊偏心补偿中应用的仿真研究

在板带轧机液压板厚自动控制系统中,扰动补偿控制是控制系统中的一个重要组成部分。扰动控制基本是开环控制,补偿效果难以准确保证。轧辊偏心补偿通常是在计算得到轧辊偏心量后,通过扰动控制进行补偿。轧辊偏心是一个周期量,如果投入的计算补偿量幅值或相位偏差较大,将会补偿一个错误量,有可能恶化产品厚差精度。该文根据闭环控制基本原理,在进行轧辊偏心补偿时,构建出一个辅助的闭环系统,根据计算或检测得到的相位,通过从离散存取矩阵中读取对应的偏心补偿量进行补偿,并根据控制期望值、实际输出值及原偏心补偿量对厚度的补偿影响量计算出补偿偏差,经辅助闭环控制器计算出修正偏心补偿量,代替原离散存取矩阵中对应相位处的偏心补偿量,实现对偏心补偿量的滚动优化,从而改善补偿效果,进而提高补偿精度。通过不同工况下的仿真运行曲线显示了离散辅助闭环控制在轧辊偏心补偿应用中的可行性,为轧辊偏心补偿提供了一种有效的新途径。     

基于微分进化的MFFT轧辊偏心诊断技术

针对FFT对轧辊偏心信号分析的局限性,提出了基于微分进化的MFFT方法。论述了方法的基本思想、实现过程及其关键步骤。通过仿真实验表明,基于微分进化的MFFT方法可以较好地分析当采样持续时间不是信号周期整数倍时的轧辊偏心信号。以某五机架冷连轧机为研究对象,应用基于微分进化的MFFT方法实现对轧辊偏心的诊断,结果表明:在该五机架连轧机中,第1架轧机的轧辊偏心因素、末架轧机的轧辊偏心因素及热轧前钢坯上的水印因素,是造成末架轧机轧制力波动的主要原因。该诊断方法可以为轧辊偏心的定性分析与在线控制及补偿提供可靠的依据。     

带钢冷轧过程辊系径向变形的数据挖掘与预报

在带钢冷轧过程中,辊系径向变形会影响带钢的厚度精度,并且难以在线检测.依据自动厚度控制(Autogaugecontrol,AGC)系统固有的测试系统,充分利用采集到的出口厚度、压下位移、轧制力、轧制速度等数据,根据厚差公式进行数据挖掘,对辊系的变形进行挖掘计算.为了解决由于测厚仪安装距离造成的厚差信号滞后问题,在挖掘计算前依据轧制速度进行数据重新匹配和整理,在挖掘计算后采用指数平滑法对计算结果进行平滑,并按照趋势外推法进行当前辊系径向变形值的预报.采用平滑系数自适应算法进一步提高预报精度.将辊系径向变形值的挖掘和预报方法在某四辊轧机轧制数据上进行应用,取得比较清晰的变形规律和完整变形过程.为进一步研究轧辊辊系径向变形规律和补差方法,进而提高厚度控制精度奠定了基础.     

基于柔性转子动力学建模的热轧板带凸度在线预测模型

现代加工技术的发展对金属板带产品的质量标准要求越来越高,因此在板带轧制过程中对板形进行控制具有重要意义。板带凸度是描述轧制过程板形的重要参数。提出一种基于柔性转子动力学建模的低阶板带凸度在线预测模型,结合动力学机理建模和数据挖掘技术,计算速度快,既能弥补解析模型精度不足的缺点,也能解决智能方法不能适应轧制条件变化的问题。结合铝板带四连轧机组在线实测数据进行模型建立以后,实现对轧制过程板带凸度的预测并得到验证,测试结果表明,模型的预测精度较高,较低的模型阶数适合于轧制过程板带凸度的在线控制器设计。     

宽厚板轧制过程有限元模拟分析

以大型ANSYS软件中的LS-DYNA模块为平台,对鞍钢5500mm轧机轧辊和板带进行建模。通过设置板带的咬入速度、轧辊的角速度、压下量等初始条件,动态模拟四组不同板宽的单道次轧制过程和施加三组不同压下量的单道次轧制过程,进而分析宽厚板轧制过程中的应力、应变以及板带轧后凸度的变化情况。最后,把模拟结果与现场板带轧制实际数据进行比较,验证分析结果的准确性。分析结果对提高宽厚板产品的质量和精度都具有重要的理论意义和应用价值。     

小模数齿轮极坐标快速测量技术研究

为了解决小模数齿轮齿距、齿厚、齿轮偏心等参数的测量,利用非接触式距离传感器及直驱旋转平台构建了一个极坐标式测量系统。通过旋转平台的光栅信号控制距离传感器的触发,实现了被测小模数齿轮横截面数据的等角度采样。开发软件对获取到的数据进行处理,获得了齿距、齿厚、齿轮偏心等误差。试验表明,该系统可实现小模数齿轮上述参数的快速测量。     

四辊轧机有载辊缝解析模型研究

针对轧制过程中轧辊的弹性变形和轧辊与轧件间的相互作用，通过对四辊轧机辊系变形和受力状况的分析，从理论上详细推导了直观的有载辊缝形状函数，明确了有载辊缝形状函数与相关因素的对应关系。同时，为了验证辊缝解析模型的准确性，采用该模型对某铝热连轧机的精轧末机架的出口板凸度进行了理论计算，并与在线测得数据进行比较，结果表明：该模型计算精度高，相对误差较小(低于15％)。该模型不但为板形的控制以及轧制板凸度的建模提供了理论基础，还为预报板形、研究板带截面上任一点的板凸度提供了方便。     

反演算法测量冷轧接触应力的影响因素与精度分析

在现代高速轧制过程中,准确获得轧辊和轧板接触应力至关重要,基于反演算法测量轧制界面接触应力的方法是一种测量接触应力的前沿技术。通过有限元数值仿真模拟二辊冷轧铝板过程,解析了采样半径和采样频率对平面应变条件下的反演算法精度的影响。根据仿真结果,提取轧辊内部不同半径位置一周应力分量作为反演算法输入量反演出轧制界面接触应力,计算出反演接触应力和仿真接触应力相对误差,讨论了反演算法输入量的采样半径和采样频率对反演算法精度的影响规律。结果表明,采样半径越靠近轧辊表面、采样频率越大,接触应力的反演精度越高,但是达到一定范围内反演算法的改善效果已经不明显,为下一步基于该反演算法的新型接触应力传感器的设计与安装提供了理论依据。     

基于虚拟仪器的冷轧带钢板纵向厚度监测策略研究

为了改善本钢冷轧厂1676mm酸洗一冷连轧联合机组的板带质量,提出了采用虚拟仪器技术构成监测系统的方法。在详细分析影响板带材纵向厚度和板凸度的各种因素基础上,采用基于LabVIEW的虚拟仪器构建方法开发了板带厚度和板凸度的监测软件系统,能够对冷轧厂现场的实际工况与设计系统实际测试结果进行对比分析。在轧制过程中,系统可以准确实时的完成对所需信号的监测,并进行实时显示等相关处理工作,实现了对监测数据的协同处理。     

热轧铝板带分段冷却闭环控制策略

针对目前热轧铝板带凸度控制存在的问题,建立以轧辊温度在线测量为基础的分段冷却闭环模糊控制系统。以简单的测量设备和控制方法,代替昂贵复杂的板带凸度控制机构。用实际轧制数据训练自适应PSO-BP神经网络,并用训练完成的神经网络依据目标板带凸度得出轧辊温度预设定模型;依据操作人员的经验以及理论分析结果,设计分段冷却模糊控制规则,形成分段冷却闭环控制系统,达到控制板带凸度的目的。经在某厂二辊可逆热轧上的应用,结果表明:轧辊温度偏差量可控制在±4℃内;铝板带纵向各处的凸度95%以上可控制在目标凸度(20~40μm)范围内。该方法充分发挥了分段冷却系统对板带凸度的控制能力。     

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...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

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。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

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.