运用正交试验法改革工艺提高钢球精度

我厂产品铬钢球过去精度只能达到G100,而市场需求G20以上钢球,产品不能适销对路,经济效益较低.针对这个问题,我们开展QC活动,分析钢球生产的工艺流程,确定了影响钢球精度的主要因素,运用正交试验法对主要影响因素做了试验,确定了最佳工艺参数,使钢球精度大幅度提高,取得了显著的经济效益. 主要影响因素分析 铬钢球生产工艺流程为:冷镦→光球→热处理→硬磨→研磨.在QC活动中,经过集思广益,确认决定钢球几何精度主要是在末道工序研磨阶段,并且初步认为工艺参数是影响精度的主要因素,它包含有主机转速、压力、磨削量和Cr_2O_3使用时机四个…     

求解概率的常用方法解析

数学课程标准把概率作为新增加的学习内容以后,近几年的中考试题中出现了大量与概率有关的题目,这类问题紧密联系生产生活实际,生动有趣,但题型千变万化,解题思路灵活多样.解答有关概率的问题     

课改后统计与概率内容考查研究

1 引言 统计与概率在工农业生产和社会生活中有着广泛的应用.在生产、生活和科学技术飞速发展的当今社会,它的应用已渗透到整个社会的方方面面,从而使统计与概率的基础知识成为一个普通公民的必备常识.由于统计与概率的学习对于培养和提高学生的数学思维能力方面发挥着特有的作用,因此国外许多国家很早就将其列为中、小学数学教学的内容和目标的一部分.如美国在1989年出版《中小学数学课程与评估标准》中规定了统计与概率,并且强调统计和概率的思想方法[1];前苏联在1990年颁布的教学大纲中就包涵概率与统计理论的教学内容,包括概率的加法与乘法,条件概率,独立事件,伯努利公式,随机变量,数学期望等内容知识.     

纤维增强复合材料靶板抗钢球贯穿的工程分析方法研究

介绍了钢球贯穿纤维增强复合材料靶板的一维工程近似分析方法.钢球被假定为刚体,复合材料靶被近似为横观各向同性弹埋性材料.通过将球腔膨胀模型和柱腔贯穿相结合的方法,提出了一种改进的复合材料靶抗贯穿的工程近似分析方法.利用该方法,对三维芳纶纤维编织(3DKw)复合材料靶板开展了抗钢球贯穿的工程近似分析,计算结果与实验结果一致性较好;并进一步讨论了计算中材料主要参数对靶板抗贯穿规律的影响.     

由条件概率看概念教学在学生素养培养中的重要作用北大核心

1新增条件概率的背景分析 条件概率是概率论中一个非常重要的的概念,概率研究和生产实践中很多问题都涉及条件概率．在普通高中数学“课标教材”中（人教社新课标教材A版·普通高中课程标准实验教科书,下同）,条件概率属新增内容,从知识形成的顺序结构和逻辑层面上分析,它上联古典概型、几何概型,涉及事件、事件空间、事件条件、事件的关系,下联积事件概率、独立重复试验、二项分布,起着承上启下的作用,是与概率概念的综合运用．     

基于改进混合遗传算法安排生产调度

研究了某工厂生产调度问题,建立了数学模型.针对这一实际问题,通过引入小生境技术、最优保存策略、近优淘汰策略、自适应调整交叉概率和变异概率,设计了用于求解多个最优顺序的混合遗传算法,用所设计的混合遗传算法对该模型进行了计算,获得了许多最优顺序,这就使得生产调度安排灵活机动,便于智能调度,同时生产量比原来大幅度提高.这表明使用混合遗传算法安排生产调度是非常有效的.     

串并联电路的可靠性问题

随着科学技术的发展,串、并联电路在日常生活及生产中时常可见.下面我们用概率知识来研究串、并电路工作的可靠性问题. 一、简单串、并联电路正常工作的概率     

刀具问题的仿真及灵敏度分析

本文通过计算机模拟仿真 ,搜索到了 CMCM-99A题中换刀间隔与检查间隔的近似最优解及单位正品最小费用 ,并对 p1(好刀生产正品的概率 ) ,p2 (坏刀生产正品的概率 ) ,k,f,d进行了灵敏度分析 ,得出 u(换刀间隔 )是最重要的优化参数的结论     

从后验概率的应用看Bayes概率的意义

某厂有一条自动化生产线，根据以前的经验知它正常运转的概率是９５％。正常运转时生产９０％的合格品，不正常运转时可生产４０％的合格品。某日进行抽样检查，先抽取了一件产品，检验后发现它是合格品；又抽取了一件产品，检验后发现它是废品。根据两次抽样结果推测一下，生产线属于正常运转的概率有多大。这个问题中生产线正常运转的先验概率是９５％，现在产生了新的信息，即两次抽样中一次是合格品，一次是废品，在获取的这种新信息下，再推算生产线正常运转的概率即是后验概率，后验概率可用Ｂａｙｅｓ公式来计算。用Ａ表示生产线正常…     

也谈一道被误解的概率题

<正> 本刊八七年第二期上《一道被误解的概率题》一文指出了题目为:“某工厂生产过程中出现次品的概率为0.05.每100个产品为一批,检查产品质量时,在每批中任取一半来检查,如果发现次品不多于一个,则这批产品可以认为是合格的.求一批产品被认为是合格的概率.”在一些教材及习题解答中被误解了.我     

目标定位最优布站的研究

将目标检测问题转化为椭球体的截面对圆的覆盖问题,并给出了“逐层收缩”方案,给出了一个可计算的较优的结果;通过对逐层收缩方案的调整,获得了最优解:18个球(9个红球和9个蓝球).本文将目标定位问题转化为圆的三重覆盖问题,建立“球均定位能力”模型证明了一个红(蓝)球周围有4个蓝(红)球这种模式具有最大的球均定位能力,在此基础上给出红、蓝球的一个布局.36个球(18个红球和18个蓝球).     

Nonconstructible Simplicial Balls and a Way of Testing Constructibility

Constructibility of simplicial complexes is a notion weaker than shellability. It is known that shellable pseudomanifolds are homeomorphic to balls or spheres but simplicial complexes homeomorphic to balls or spheres need not be shellable in general. Constructible pseudomanifolds are also homeomorphic to balls or spheres, but the existence of nonconstructible balls was not known. In this paper we study the constructibility of some nonshellable balls and show that some of them are not constructible, either. Moreover, we give a necessary and sufficient condition for the constructibility of three-dimensional simplicial balls, whose vertices are all on the boundary. Received September 29, 1997, and in revised form August 3, 1998 and August 11, 1998.     

A Survey of the Coupon Collector’s Problem with Random Sample Sizes

This paper surveys the coupon collector’s waiting time problem with random sample sizes and equally likely balls. Consider an urn containing m red balls. For each draw, a random number of balls are removed from the urn. The group of removed balls is painted white and returned to the urn. Several approaches to addressing this problem are discussed, including a Markov chain approach to compute the distribution and expected value of the number of draws required for the urn to contain j white balls given that it currently contains i white balls. As a special case, E[N], the expected number of draws until all the balls are white given that all are currently red is also obtained.      

一类抽球模型中两两(或相互)独立的条件及其模型构建

以一类抽球模型中由两两独立不能推出相互独立为基础,导出只由单色球和全色球构成的抽球模型中,抽到的球上的颜色两两独立的充要条件;然后得到并为必然事件的n个随机事件相互独立一个必要条件,并构建抽球模型中抽到的球上的颜色相互独立的球色彩结构.     

The onset of dominance in balls‐in‐bins processes with feedback

Consider a balls‐in‐bins process in which each new ball goes into a given bin with probability proportional to f(n), where n is the number of balls currently in the bin and f is a fixed positive function. It is known that these so‐called balls‐in‐bins processes with feedback have a monopolistic regime: if f(x) = x^p for p > 1, then there is a finite time after which one of the bins will receive all incoming balls. Our goal in this article is to quantify the onset of monopoly. We show that the initial number of balls is large and bin 1 starts with a fraction α > 1/2 of the balls, then with very high probability its share of the total number of balls never decreases significantly below α. Thus a bin that obtains more than half of the balls at a “large time” will most likely preserve its position of leadership. However, the probability that the winning bin has a non‐negligible advantage after n balls are in the system is ～const. × n^1‐p, and the number of balls in the losing bin has a power‐law tail. Similar results also hold for more general functions f. © 2009 Wiley Periodicals, Inc. Random Struct. Alg., 2009     

A time-dependent version of Pólya's urn

A process is defined that consists of drawing balls from an urn and replacing them along with extra balls. The process generalizes the well-knownPólya urn process. It is shown that the proportion of red balls in the urn converges to a random limit that may have a nonzero probability of being 0 or 1, but is nonatomic elsewhere.     

发现空间目标并定位的模型

针对在一个圆柱体内用最少的红球、蓝球发现黄球的问题,采用多个椭圆覆盖圆柱顶面的方法,设计出利用18个球覆盖的方案,叙述了该方案的设计思路,并严格证明出方案的可行性.针对用最少的红球、蓝球发现并定位黄球的问题,设计出36个球的方案,严格证明出方案的可行性.     

On the problem of characterizing the diversity vectors of balls

Under study are the diversity vectors of balls (the ith entry of the vector is equal to the number of different balls of radius i) for ordinary connected graphs. The problem is solved of characterizing the diversity vectors of balls in graphs of small diameter.     

发现并定位黄球

本文讨论了如何设置红球和蓝球的数量和位置,发现圆柱区域内的黄球并进行定位的问题.我们考虑了一对红球蓝球发现黄球并定位的问题,在此基础上进行扩展,基本解决了黄球的发现并定位的问题.在静止黄球发现问题中,采用了正三角形扩展和正六边形扩展两种方法.在静止黄球的定位问题中,我们结合正三角形和正六边形运用了旋转法和添点法进行扩展.在运动黄球的定位问题中,讨论了体积概率模型和时间概率模型,给出了两种模型的概率求解公式.在系统协同定位模型中,我们给出了发现定位分步模型和周期系统跟踪模型,其中后者在仿真中实现了大于80%的定位性能,该系统可以简单扩展为多目标快速定位问题.此外,文章讨论了精确测量和颜色切换模型,快速定位问题,多目标定位等问题.     

On the graphs with given diameter,number of vertices,and local diversity of balls

In connection with the problem of characterizing the diversity vectors of balls in ordinary connected graphs, we study the n-vertex graphs with diameter d and local t-diversity of balls; i.e., the graphs that have n different balls of radius i for all i ≤ t. For these graphs, a lower bound is available for the number of vertices defined by d and t. In this work, we explicitly up to an isomorphism describe all graphs with diameter d and the local t-diversity of balls (full diversity of balls) that have the smallest order. Moreover, the diversity vector of balls is calculated for each of these graphs.