中温热管换热器的优化过程与方法

利用"三次设计"优化方法对中温热管换热器冷热流体侧加热段长度、迎风面宽度、翅片高度、翅片厚度、翅片间距、管束横向管间距进行最优参数组合,找出中温热管换热器体积最小的最优解,最大限度降低换热器的体积,提高热管换热器的紧凑性。同时,对不同温度区域的热管进行了稳定性和可靠性研究。最后运用神经网络方法对优化结果进行模拟仿真,确定最佳方案。     

提高热轧卷板尺寸精度的研究

针对唐山不锈钢公司1580生产线中间坯开轧宽度、换规格宽度波动大,宽度超差降判突出的问题,进行了加热炉出钢工艺优化、轧机宽度控制模型及活套张力的优化、卷取带钢张力和张力系数优化研究。改进后,热轧卷板宽度公差+5~+15 mm的合格率达到98%以上,通条宽度差得到较大改善,去除带钢头尾20 m长度的卷板厚度通条差控制在±0.5 mm以内。     

首秦4300mm轧机厚度精度控制的研究

针对首秦公司4 300 mm轧机弹跳值不能满足轧机需求的实际情况,通过引入影响函数法优化弹跳值,并分析了轧件宽度、工作辊半径、支承辊半径、工作辊凸度、支承辊凸度对轧机弹跳的影响。通过拟合回归,优化后的模型计算误差在4%以内,大大提高了中厚板的厚度精度控制水平,满足了用户使用需求。     

基于Abaqus的加速度传感器频响参数分析

为了增大加速度传感器的测量频率范围,优化其动态特性,在传感器结构设计中应尽可能提高传感器的固有频率。针对一种四悬臂梁压电式加速度传感器,通过理论计算与有限元仿真对传感器结构进行模态分析,研究悬臂梁结构参数对传感器固有频率的影响,并根据分析结果提出结构优化方案。仿真结果表明,在仅改动悬臂梁的结构参数时,传感器的固有频率随着悬臂梁长度的增加而减小,随着悬臂梁宽度、厚度的增加而增大,且悬臂梁长度对固有频率的影响大于悬臂梁宽度和厚度。通过优化悬臂梁的长宽比、增加悬臂梁的局部厚度等方式,可以使传感器的固有频率得到显著提高。     

减振复合板阻尼测试样品模态分析及尺寸确定

针对减振复合板样品在阻尼测试中样品尺寸标准不一,样品尺寸在确定时缺乏理论依据,无法确定测试样品尺寸的问题,利用有限元方法对减振复合板进行模态分析,用悬臂梁法进行阻尼实测。有限元模拟结果表明,在一定的宽度和厚度下,随着试样长度的增加,其1阶到6阶共振频率均出现降低的规律;在一定的长度和厚度下,随着样品宽度的增加,前4阶共振频率有略微增加的趋势;在一定的长度和宽度下,随着样品厚度的增加,1阶到3阶的共振频率基本保持稳定。实测结果表明,选取自由端长度为216 mm、宽度为12.7 mm的样品,利用2阶和3阶共振频率下的损耗因子进行阻尼表征较为合理。     

磨具弯曲成形法加工抛物面时影响廓形精度的因素分析

在应用磨具弯曲成形法设计磨具的廓形曲线时,考虑到磨具厚度的影响,利用高等数学及力学的知识进行数学建模,推导出更加精确的宽度函数表达式。通过讨论表达式中相关参数变化表明,此方法更适合用来加工横截面宽度变化不明显的小曲率的工件。     

粗轧狗骨失宽的控制

轧件宽度控制作为粗轧过程控制的一个重要组成部分，其控制精度已成为衡量带钢生产质量的重要指标之一。对于厚宽比较大的轧件，经立辊轧制后轧件的宽度被压缩，断面形成狗骨形，从而造成头尾失宽，导致生产造成额外的切损。本文主要研究了狗骨的形成机理，分析了影响宽度断面形成的主要因素为立辊侧压量、立辊直径、轧件宽度和厚度等，且立辊侧压量、直径越大，狗骨高度和失宽量越大；轧件来料尺寸越大，狗骨高度和失宽量越大。并以柳钢热轧厂2032生产线为例，通过调整各道次立辊侧压量，在不起拱的前提下减小首道次增大末道次侧压量，提高头部宽度均匀性；根据实时曲线调整头尾短行程的设置幅度，减小头尾失宽程度；更改立辊辊形减小狗骨高度等方式，优化了狗骨失宽现象。     

热轧板坯加热温度场数值模拟及应用

 建立了三段步进梁式加热炉板坯加热过程数学模型,用全隐式有限差分法对数学模型进行离散化,开发了板坯温度场计算模型。采用该模型重点研究了板坯宽度对板坯中心温度变化过程的影响规律。研究结果表明,对于厚度为200 mm的板坯,当板坯宽度大于600 mm时,板坯中心温度变化过程与板坯宽度无关。以此为根据,优化了板坯加热工艺,达到了提高生产效率并节能减排的目的。     

UOE焊管线铣边机钝边铣削超差原因理论分析

以某UOE焊管线铣边机设备为研究对象,着力分析夹钳小车可能引起钢板出现铣削钝边超差现象的原因。根据被铣削钢板与铣削单元之间的位置关系及刀具几何形状建立钢板在其宽度方向的偏移量与钝边高度变化量之间的函数关系式,并由此关系式计算不同厚度钢板在不引起钢板铣削质量超差的情况下在其宽度方向允许产生的最大偏移量;计算铣削不同形状钢板时,钢板可能受到的最大合外力,并在此基础上,从两个角度对可能引起钢板出现铣削质量超差现象的原因进行详细分析,明确其是否可能引起质量超差现象,为后续此类问题的快速解决和薄弱环节改善提供理论依据。     

热轧板坯加热工艺优化

建立了三段步进梁式加热炉板坯加热过程数学模型,用全隐式有限差分法对数学模型进行离散化,开发了板坯温度场计算模型.采用该模型重点研究了板坯宽度对板坯中心温度变化过程的影响规律.研究结果表明,对于厚度为200 mm的板坯,当板坯宽度大于600 mm时,板坯中心温度变化过程与板坯宽度无关.以此为根据,优化了板坯加热工艺,达到了提高生产效率并节能减排的目的.     

Integration of stimulus dimensions in perception and memory: Composition rules and psychophysical relations.

Used the method of magnitude estimation in 5 experiments with 46 undergraduates to assess how height and width are integrated in perceptual and in memorial judgments of area. Separate groups of Ss estimated the areas of perceived or remembered rectangles produced by a symmetrical 4?×?4 factorial design of height and width. Additional independent groups of observers made area judgments, based on special mixes of perceptual and memorial information referring to the height and width components of the to-be-judged rectangles. Both perceptual and memory data obeyed the bilinear interaction prediction of the normative multiplicative model. The relation between perceived and actual area and the relation between remembered and actual area could both be described by a compressive power function, with the exponent being reliably smaller for remembered than for perceived area. Findings imply a principle of integration rule invariance across perceptual and memorial estimates of a given set of stimuli, in conjunction with characteristically different valuation operations. (81 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Area judgment from width and height information: the case of the rectangle

We assessed the effect on performance of shifting from a perceptual area judgment situation, in which the physical quantity to be judged (the area) is present in the stimulus, to a situation in which it is not present in the stimulus. Adults, 9-year-olds, and 5-year-olds were shown combinations of horizontal and vertical lines of various sizes, presented on the same wall or on different walls, and asked to estimate the corresponding area. The following main results were obtained (a) When width and height information items were completely separated, 5- and 9-year-old children gave the same weight to both dimensions in their estimations; (b) when width and height information items were on two different walls, adults gave a greater weight to the larger dimension; (c) when width and height were joined, 9-year-old children gave a greater weight to the larger dimension but when they were separated, they did not.     

基于FLAC~(3D)下向进路采场参数优化

为获得最优采场参数,应用数值模拟软件FLAC~(3D)对不同进路采场结构参数进行计算,分析不同参数的进路在开挖过程中位移和应力变化特征,获得不同方案进路开采位移和应力随进路宽度和高度的变化曲线,选出最优的进路参数。结果表明:进路宽度的变化对采场顶板的稳定性较进路高度明显,进路宽度达到4.0 m时采场顶板的最大拉应力超出了其自身极限抗拉强度,最大位移量达43 mm,顶板在开挖后自身稳定性较差。综合考虑三山岛金矿新立矿区生产能力和安全性,建议矿山选择进路宽度为3.5 m,高度为3.0 m。     

基于改流体放矿技术的放矿口尺寸试验研究

针对无底柱分段崩落法开采中厚倾斜矿体普遍存在矿石损失贫化较高的问题,提出了改流体放矿技术.其基本原理是在回采进路矿岩接触处设立改流隔离板,以改变矿岩的流动路径并改善放矿条件.通过采用改流体放矿技术,开展了12组改流体放矿物理模拟试验,分析了改流体放矿技术中不同放矿口尺寸对矿石损失贫化的影响.试验结果表明:采用改流体放矿...     

Optimal Design of a Settling Basin for a Small-Scale Drainage Area

This paper develops a nonlinear programming model to optimally design a settling basin for a small-scale drainage area with a minimum total cost. It is assumed that the shape of the settling basin is rectangular parallelepiped, and it is connected to an open channel at both ends. Therefore, the decision variables include the scales of the settling basin (i.e., length, width, and height) and the scales of the channel (i.e., width and height). The design trap efficiency requirement, which must be greater than or equal to the required one of the considered watershed, makes up the main constraint. Other constraints consist of the upper and lower bounds of the decision variables, the equations for computing the trap efficiency, and the average flow velocity in the settling basin. The objective function is to minimize the total annual cost, which is the sum of the land, capital, and maintenance-operation cost. The developed model is solved by using a genetic algorithm. This model is applied to a subwatershed of the Wu-She Reservoir watershed in central Taiwan. The obtained results effectively demonstrate the applicability and practicability of the model.     

Origin软件在等离子体发射光谱分析中谱线拟合的应用

以微合金标准样品为例,采用激光诱导击穿光谱(LIBS)分析技术采集全谱数据,应用Origin 9.0软件对其在等离子体发射光谱分析中的谱线背景扣除、谱线轮廓拟合及多重叠峰拟合等数据处理方面的应用进行了详细的介绍。对Al 396.152 nm谱线进行Lorentz拟合,由Lorentz拟合曲线可以得到峰面积、半高峰宽及峰高等重要的信息,依据谱线的半高峰宽结合简化后Stark场致展宽公式对等离子体中电子数密度重要参数进行估算,由计算可知电子数密度为2.74×10¹⁶ cm^-3。此外,对402.8～403.8 nm之间未分开的锰元素三重峰应用多峰拟合功能对多重叠峰进行谱线间的干扰校正,同时给出拟合函数参数信息,依据其峰高或峰面积可进行定量分析。     

The randomization procedure in the study of categorization of multidimensional stimuli by pigeons

Pigeons categorized rectangles varying in both height and width in an adaptation of a method used by Ashby and colleagues for the cognitive and neuropsychological analysis of human decision bounds for ill-defined categories. Optimal decision bounds were defined in a stimulus space in which the point (x,y) corresponded to a rectangle with width x and height y. Four tasks defined the following 4 optimal bounds: x = y, x = c, x = y + d, and (x-a)2 + (y-b)2 = r2, where a, b, c, d, and r were constants given by a task. Estimated decision bounds for individual pigeons conformed approximately to the optimal decision bound in each of the 4 tasks. The new method suggests a way to (a) integrate the disparate literature on ill-defined visual concepts and on optimal performances in nonhuman animals; (b) compare how humans and nonhuman animals categorize ambiguous, multidimensional configural stimuli; (c) model how nonhuman animals categorize naturalistic stimuli; and (d) infer that pigeons' categorizations of naturalistic stimuli may be remarkably close to optimal.     

The shape of things to come: Miss America versus the golden rectangle.

With today's emphasis on Metrecal, dietary cola, and artificial sweeteners, one can only conclude that America is slenderness conscious. The low silhouettes of modern houses and factories, the soaring skyscrapers puncturing the horizon, reinforce the notion that sheer bulk is considered ugly nowadays. Our original aim in this study was to try to relate preferences for rectangle shapes to pleasing height/width architectural proportions. The golden rectangle has exercised a mystical mathematical appeal; the longer side is to the shorter as the shorter is to the difference between the sides. Cards were prepared showing a black rectangle, with the long side oriented vertically, on a white background. Two such packs were used, one having rectangles of equal width, the other rectangles of equal area. The 12 selected length/width ratios were identical for each pack ranging from 1/1 to 2.85/1, and the ratios included the golden rectangle. Subjects were given a pack of cards stacked in a random order and asked to spread them out, and then to choose the most pleasing shape. The main conclusion is that preferred height/width ratios for buildings are exceedingly variable. Second, there is a definite preference in favor of the tall and slender, much more so than for rectangles. In general it may be said that heights of Miss America pageant winners have been rather variable, waistlines have tended to become slimmer over the past 46 years, leading to an increasing height/waistline ratio. It is obvious that the height/waistline ratio cannot be a linear function of time; women were not wider than they were tall several hundred years ago. Yet one can look forward to slimmer waisted and perhaps slightly taller Miss America winners in the years to come. We therefore wish to affirm the notion that modern Americans are slenderness conscious. It can be stated that the golden rectangle is not now, and perhaps never was, a sure preference standard. But with each passing year it seems, to us at least, that the newest Miss America proves to be more shapely than ever. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

带钢卷取过程起筋控制的建模与仿真

 为了研究带钢局部高点卷取过程起筋的控制方法,基于应力函数假设和S Timoshenko最小功原理获得了起筋带钢的应力场分布,并采用伽辽金虚位移原理建立了可用于在线计算的起筋临界卷取张力设定模型和起筋弹性极限模型。并对应力场分布和临界卷取张力各影响因素进行仿真研究,仿真结果表明：局部高点在径向累积叠加所引起的带钢张力不均匀分布和轴向压应力是导致带钢起筋的主要原因;临界卷取张力随带钢厚度、局部高点高度和卷取半径增大而减小,带钢宽度对钢卷的起筋临界卷取张力影响非常小。通过与实际生产控制方法和ANSYS有限元分析结果对比,验证了本模型的计算精度和可行性。     

Earth Dam with Toe Drain on an Impervious Base

The required height of a toe drain for a homogeneous earth dam on an impervious base has been determined considering reservoir water level, capillary rise for the embankment soil, free board, top width of the earth dam, embankment slopes, and tail-water position, such that the surface of seepage does not develop on the downstream sloping face of the earth dam and capillary saturation above phreatic line is contained well within the downstream sloping face. Using Kozeny’s analytic function, exact solution to the unconfined flow through an earth dam having parabolic equipotential boundaries on either side has been obtained. For straight toe drain face, and for various positions of tailwater, approximate toe drain heights and heights of surface of seepage have been determined using the Kozeny’s function and the method of fragments. It has been found that for an earth dam with 1/2 upstream slope, ?1/3 downstream slope, no tailwater, and 2?m capillary rise, capillary saturation is contained within the earth dam and the phreatic line is prevented from emerging on the downstream sloping face by providing a toe drain of height equal to 1/3 of the height of water level in the reservoir.