中厚板轧制辊缝值的设定方法

本文介绍中厚板轧机的计算机控制方法，尤其是中厚板高精度轧制辊缝值的设定方法，通过实时厚度最佳分配、轧制过程自适应和轧机弹跳方程得出辊缝设定值，从而达到命中目标厚度和板形平直的目的。     

基于弹跳方程的GM-AGC的局限性

通过理论分析,证明在基于弹跳方程的GM-AGC系统中,如果轧机刚度计算值和实际刚度存在偏差,则实际厚差不仅不能被完全消除,而且在某些条件下,看似负反馈的厚度控制过程甚至会因辊缝调节方向错误而造成实际厚度的正反馈现象,从而导致基于弹跳方程的GM-AGC控制效果的恶化。     

动态修正轧机弹跳值提高热轧带钢头尾厚度精度

为了得到高精度的辊缝设定值,分析了某钢铁公司热连轧厂轧机弹性方程,找出更接近实际的轧机弹性曲线,以便在假定带钢塑性系数为常数的条件下,在线动态给出带钢穿带过程中轧机弹跳值修正量。结果表明：一段轧机弹跳回归模型精度比二段轧机弹跳回归模型高一个数量级。通过动态修正轧机弹跳方程,消除了辊缝设定模型中的刚度补偿系数误差,可以提高热轧带钢头尾部厚度精度。     

轧件宽度对热轧带钢轧机弹跳的影响

 轧机的弹跳方程是AGC控制系统不可缺少的模型,但轧制过程中轧机的实际弹跳与轧件的宽度有关,当轧件宽度显著偏离全辊面宽度时,轧机的弹跳也会严重偏离预压靠方法得到的结果。采用影响函数法分析了轧件宽度对轧机弹跳的影响,计算结果表明随着轧件宽度的减小,轧机弹跳宽度补偿量增加;随着轧制力的增加,轧机弹跳宽度补偿量增加。根据影响函数法计算结果,建立便于工程应用的轧机弹跳宽度补偿回归模型。     

钢板轧机小预压靠力的弹跳方程

本文根据武钢2800钢板轧机上的实测数据,用一元线性回归的方法,建立了在小预压靠力下的轧机弹跳方程,并据此推理,建立了在任意小预压靠力下的弹跳方程。由此可算出轧件厚度,从而可取代射线测厚仪。     

BP神经网络和弹跳方程在铝热连轧厚度预报中的综合应用

采用BP神经网络方法建立了铝热连轧精轧机组出口厚度预测模型，采用试错法解决了中间隐层最佳隐层单元数的问题，采用回归法确定了轧机的相关弹性系数，建立了轧机的弹跳方程数学模型。通过比较有、无传统弹跳方程数学模型输入的神经网络厚度预测模型，确定了弹跳方程对神经网络在热连轧厚度预报应用中的重要性，提出了BP神经网络与数学模型相结合的综合网络方法。相比全部使用整体神经网络，中间隐层最佳隐层单元数减小，网络结构得以简化，网络负担减小，网络的泛化能力也得到加强，同时也进一步提高了预报精度。预测结果与实测数据对比表明，相对误差在1％以内，实现了高精度预报，为铝热连轧出口厚度预报提供了一条准确高效的新途径。     

邯钢2800mm中厚板轧机优化规程研究

优化轧制规程计算及实现的基本数学模型，由优选轧制压力公式，变形抗力，温降模型参数和精确弹跳方程构成。通过计算机模拟实验比较主要压力公式的Ｑｐ值，优选出该轧机的实用压力公式，变形抗力和温降模型参数非线性估计方法，提高了压力预报精度；反映板宽因素的非线性弹跳方程，是提高辊缝设定精度的关键。通过实测轧机横向刚度的轧制方案，优化轧制规程和不同终轧道次轧制压力规程的设定计算，并在轧机上实验，证明所研制的方法     

测厚计厚控方法实用中的几个问题探讨

通过测厚计厚控方法实用中问题的分析研究 ,得出测厚计型变刚度计算公式 :MC=M× KBKB-M。厚控系统的厚度设定值计算公式 :h′=h-(P-P0 ) /MC,新的厚度预报公式 (即实用弹跳方程 ) :h=Φ+(P-P0 ) /KB+(P-P0 ) /MC+A。新厚度预报公式将反映控制系统特性和轧机设备特性的双参数引入在一个方程中 ,将现用弹跳方程 A参数里的轧制力函数项分离出来 ,从而显著地提高了弹跳方程的精确度。     

轧机低速轧钢时一种新的厚度控制方法

在低速轧钢时,由于测厚仪测量值的长时间滞后,传统的后馈控制效果不好.而采用传统的"弹跳方程"进行厚度控制,虽然其无滞后,快速性好,但绝对精度差,也不能满足要求.为此开发出一种新的"弹跳方程"厚度控制方法,它兼有"弹跳方程"控制固有的快速性,又具有后馈控制的精确性,在工程应用中达到了满意的效果.此方法也可推广到冷连轧机组上,在穿带或分卷低速轧钢时进行厚度AGC控制.     

轧辊凸度变化对中厚板辊缝设定的影响

 根据影响函数法计算轧辊凸度对辊缝设定的影响，当保持工作辊和支承辊凸度不变，则轧制力与辊系弹性变形呈线性关系，工作辊和支承辊凸度的变化对直线的斜率几乎没有影响。并基于不同条件的计算结果，回归出轧辊凸度变化对辊缝设定影响的计算模型。最后对传统轧机弹跳模型进行改造，提出新的轧机弹跳模型。实际应用表明该修正模型能够有效提高轧件厚度预测精度。     

350mm×470mm矩形坯连铸生产轴承钢的凝固末端

确定轴承钢在连铸坯凝固末端的位置,对于轴承钢轻压下工艺的合理制定、改善铸坯的中心疏松及中心偏析等缺陷具有至关重要的意义。首先,采用二维非稳态传热方程,结合本钢350mm×470mm矩形坯铸机自身特点,建立了矩形坯凝固模型。其次,通过射钉试验,取片做硫印,来标定生产状态下不同位置的坯壳厚度。最后,对铸坯的表面温度进行了实际测定。研究结果表明,射钉硫印测量的坯壳厚度、实测的铸坯表面温度都与凝固模型的计算结果相近,实际生产过程中,完全可以采用该模型来理论计算铸坯凝固末端,为轻压下工艺提供理论依据。     

Crop Coefficients for Microsprinkler-Irrigated, Clean-Cultivated, Mature Citrus in an Arid Climate

Crop evapotranspiration (ETc) was measured over a clean-cultivated, mature navel orange orchard with microsprinkler irrigation located near Lindsay, California. Hourly mean latent heat flux density was determined as the residual of the energy balance equation with measured net radiation, soil heat flux density and sensible heat flux density estimated using the surface renewal method. The ETc was compared with ETo calculated using hourly weather data and the ASCE-EWRI Penman-Monteith equation. Following pruning and topping of the trees in the spring of 2001, the Kco values slowly increased as the canopy developed in the following season. An average Kco = 0.82 was observed. In the following year, the mean summertime value increased to about Kco = 0.95, and in 2003 and 2004, the summertime value averaged near Kco = 1.00, which is somewhat higher than observed for drip irrigated trees in southwestern Arizona and considerably higher than reported in the widely used Food and Agricultural Organization of the United Nations publications that were based on infrequent surface irrigation.     

GM-AGC的伪正反馈现象研究

从数学分析和物理本质两方面解释了GM-AGC系统中的伪正反馈现象，证明了这种现象的出现，是作为厚度测量机构的弹跳方程的误差和GM-AGC的负反馈机制在某种条件下共同作用的结果，给出了避免其出现的方法。     

Three-layer copper-iron-copper strips of metal powder

Summary The experimental study of the effect of the dimensions of the feed mechanism and the properties of powder upon the relative thickness of copper and iron layers in pore-free strip was carried out. An equation is suggested for the calculation of the relative thickness of copper layers in pore-free strips prior to rolling; this equation takes into account the setting of the feed apparatus and the properties (volume weight) of powders. The calculated data is in good agreement with experimental results. The agreement of the three-layer metal-powder strip with the standard specifications is not worse than that of the strip made of laminated ingots.     

Regulation of gamma-aminobutyric acid (GABA) transporters by extracellular GABA

Hydrophobic interactions between a bilayer and its embedded membrane proteins couple protein conformational changes to changes in the packing of the surrounding lipids. The energetic cost of a protein conformational change therefore includes a contribution from the associated bilayer deformation energy (DeltaGdef0), which provides a mechanism for how membrane protein function depends on the bilayer material properties. Theoretical studies based on an elastic liquid-crystal model of the bilayer deformation show that DeltaGdef0 should be quantifiable by a phenomenological linear spring model, in which the bilayer mechanical characteristics are lumped into a single spring constant. The spring constant scales with the protein radius, meaning that one can use suitable reporter proteins for in situ measurements of the spring constant and thereby evaluate quantitatively the DeltaGdef0 associated with protein conformational changes. Gramicidin channels can be used as such reporter proteins because the channels form by the transmembrane assembly of two nonconducting monomers. The monomerleft arrow over right arrow dimer reaction thus constitutes a well characterized conformational transition, and it should be possible to determine the phenomenological spring constant describing the channel-induced bilayer deformation by examining how DeltaGdef0 varies as a function of a mismatch between the hydrophobic channel length and the unperturbed bilayer thickness. We show this is possible by analyzing experimental studies on the relation between bilayer thickness and gramicidin channel duration. The spring constant in nominally hydrocarbon-free bilayers agrees well with estimates based on a continuum analysis of inclusion-induced bilayer deformations using independently measured material constants.     

大型筒节轧制力预报模型

 根据筒节和轧辊的几何关系,得到了筒节上下表面接触弧长的几何方程;根据现场数据和有限元方法,得到了筒节上下表面接触弧长的变形方程;结合几何方程和变形方程,并基于赫希柯克公式计算了考虑弹性压扁的筒节接触弧长。由于筒节外端对轧制力的影响远远大于接触摩擦的影响,结合接触弧长模型和材料变形抗力模型,基于现场数据和优化算法,优化得到了外端应力状态影响系数,从而建立了大型筒节轧制力预报模型。结果表明：上下辊的接触弧长不等,上辊接触弧长稍大于下辊接触弧长,上辊压下量大于下辊压下量,上辊和下辊的接触弧长之比约为1.3左右;将模型应用到筒节轧制中,计算轧制力与实测轧制力平均误差为9.2%,模型计算精度较高,能够满足工业应用要求。