蚕桑生产回归模型及其应用

本文利用现代回归分析的理论和方法，建立了农业县植桑养蚕系统的决策数学模型，并在此基础上分析了发展农村植桑养蚕的规律，提出了科学的决策建议。     

随机序列的适时预报方法——新息预报方法

<正> 人们在进行科学研究和科学实验的过程中,常常得到一系列的量测数据,由于这些数据带有一定的随机性,并往往依时间次序排列,因此常称之为随机时间序列,或简称为随机序列.如何充分利用随机序列的信息,分析研究客观事物本身的内在规律,并进一步预测未来,这往往是非常重要的.因此,首先需要从这串数据出发,建立合理的数学模型.关于这一方面,BOX给出了用ARMA(p,q)模型来描述平稳时间序列的方法和具体的     

国民经济的最优增长模型

本文利用 Cobb-Douglas生产函数建立了一类描述国民经济收入和积累率关系的数学模型 ,并利用该模型求出了国家预定经济增长目标下的计划投资量以及保持国民经济快速增长的合理的投资量和消费目标 .     

逐步回归方法在建立造纸蒸煮过程预测模型中的应用

(一) 蒸煮过程是造纸厂的一个重要组成部分,蒸煮的主要目的是除去纤维原料中的木素使其解离成浆。 对确定的蒸煮过程,浆的硬度是一个非常重要的质量指标,如硬度不当,除可显著地降低产品质量外,还会造成纤维原料、化学药品及能源消耗的增加。由于受多种因素的影响,加之尚无可用的硬度在线检测器,常常无法达到预定硬度。目前硬度的控制发展为计量设备加预测数学模型的方法。预测数学模型将硬度同过程中可在线测量联系到一起,从而实现硬度的间接在线检测,在一定程度上控制硬度。 应用预测数学模型的蒸煮过程控制可显著地提高浆硬度的一致性,由…     

对我公司工业总产值的预测

前言 利用经济数学模型分析国民经济现实的经济活动,并对经济发展趋势进行预测,是实行国民经济现代化管理的重要方法和手段.一个企业的工业总产值增长速度也与其他事物一样,有其一定规律。只有掌握这一规律,才能为决策机关编制生产计划、科学组织生产提供重要的科学依据。 本文根据我公司历年各季的工业总产值这一经济指标,运用数理统计方法对公司未来工业总产值进行了科学预测,取得了较理想的初步结果。 工业总产值这一经济指标,除受时间因素的影响有其长期趋势外,同时还受一年季节更替和其他随机变动的影响。因此,要预测一个企业未来的工…     

一类利用历史生产数据的计量抽样方案——Ⅰ 单侧情形

一、数学模型的建立 许多产品质量的指标是用测得的量来表示的,比如长度、重量、耐压力等。在生产过程中,反映产品质量的这个数量指标,对各件产品往往是不全相同的,而是遵从某种规律的分布。 我们抄录了北京维尼纶厂1966年12月的纤度抽样的数据记录,每天20个数据,(为简单起见,将实际数据减去1.40,再乘以100来进行分析)。用数理统计方法对数据进行分析,可以得到下面几个结论。 (一)每天记录的数据是遵从正态分布的。     

上证指数的预测分析

本文根据上海股市2005年6月到2009年8月的上证指数数据,通过建立数学模型的方法,对上海股票市场的走势情况作出了综合评价,建立短期内预测股市发展趋势模型对上证指数进行预测,并通过历史实际数据对模型进行了验证。     

银行对公存款模型探索

对公款是银行各项存款的重要组成部分，是银行信贷资金的主要来源之一，探索对公存款的活动规律已引起金融部门的高度重视．本文从某市近五年的实际数据出发，通过多元线性回归的方法，建立了对公存款活动规律的数学模型，并对模型进行了各种检验，结果表明模型合格可用，利用它对未来五年的活动规律进行了预测、取得了令人满意的结果．     

基于DGM的模糊多目标区间预测

无论对预测过程还是决策过程,区间预测相对于点估计预测往往拥有更重要的信息量。本文基于模糊多目标规划模型和离散灰色模型理论(DGM),给出了基于DGM的模糊多目标区间预测模型。同时,为了有利于比较区间预测的优劣,又提出了评价区间预测优劣的两个指标:区间中心的均值相对百分比误差和区间边界的均值相对百分比误差。最后,将LCD TV销售量作为本模型的实验数据,给出了区间预测的结果,并将我们的结果与其他两个模型的预测结果进行了比较分析。     

基于灰色马尔可夫模型的物流配送需求量预测研究

研究可以较准确地预测物流配送需求量的数学模型,以服务于政府及企业的物流规划及其决策.将灰色理论和离散状态的马尔可夫链相结合,用灰色马尔可夫链对物流配送需求量进行实证研究.针对灰色数据系列首先用GM模型进行趋势预测,然后利用马尔可夫状态转移概率矩阵预报方法对其预测值进行二次拟合,预测精度明显高于GM模型预测.     

小波分析印花税调整对股市成交量的影响

在2008年中国股票市场的下跌趋势中,政府为提振股票市场,在2008年4月24日和2008年9月19日分别将印花税由3%下调至1%和单边开征印花税,引起当时市场的强烈反应。文章给出小波检验方法,考察印花税对大盘指数的走势的作用。从结果来看,短期内(小于4天)对股市成交量有很大促进作用,而长期(大于16天)作用有限。     

Action of an elliptic stamp moving at a constant speed on an elastic half-space : PMM vol. 42, no. 6, 1978, pp 1074–1079

The action of a rigid stamp moving at a constant speed, on the boundary of an elastic half-space, is investigated. It is assumed that the frictional forces between the stamp and the surface of the half-space are absent. The integral equation obtained in [1] yields formulas for the pressure, for the case when the area of contact between the stamp and the half-space has an elliptic form.     

神经网络汛期降水短期气候预测模型

用1960-2005年每年5-9月安徽宣城7县(市)平均降水量作为预报对象,在对应降水前期逐月74项大气环流特征量资料、500hPa月平均高度场和月平均海温场资料中选取因子.采用主分量分析方法构造网络学习矩阵,降低矩阵维数,提高网络预测模型泛化性能.建立的神经网络汛期降水短期气候预测模型对历年样本拟合精度高,试报效果较好,可在气候预测业务中使用.     

Three-dimensional contact problem for a prestressed elastic body : PMM vol. 42, no. 6, 1978, pp 1080–1084

A half-space of an incompressible neo — Hookean [1,2] material subjected to a homogeneous bi-axial tension or compression along its boundary, is considered. A small deformation caused by the action of a smooth rigid stamp on the boundary of the half-space is superimposed on the initial finite deformation. An integral equation is obtained for the contact pressure. A solution of this equation is obtained for an inclined elliptic stamp with a flat base, and for an elliptic stamp with a curved base, for the cases when the extension coefficients in two directions are either identical, or differ little from each other. The influence of the inital loading on the distribution of the contact pressure, the displacement of the stamp and the form of the contact zone, is analysed.     

Three-dimensional contact problem of the motion of a stamp with friction

There is considered the three-dimensional contact problem of elasticity theory with friction forces collinear to the motion direction. Such a case holds during stamp motion along the boundary of an elastic half-space with anisotropic friction /1/. In the case of an arbitrary friction surface, the mentioned force distribution is satisfied approximately during stamp motion.     

Contact problems of the theory of elasticity with friction and adhesion

An exact closed solution of the plane contact problem for a semi-infinite stamp is constructed for the case when the free boundary of the half-plane is under a load (problem 1), or for an analytic solution, to any prescribed accuracy, of the problem of a finite stamp impressed into an elastic half-plane under the action of a central vertical forceP (problem 2), or under the action of the above force P, a horizontal force T and a pair of forces with moment M (problem 3). In all three cases the region of contact consists of a zone of adhesion and fraction, and the stamp has a plane profile.     

A dynamic contact problem for an elastic half-plane in the case of high frequency oscillations

Harmonic high frequency oscillations of a rigid stamp coupled without friction tc an elastic half-plane are considered. The main difficulty in constructing the high-frequency asymptotic forms is that of carrying out the effective factorization of the kernel of the basic integral equation. A function is proposed, which takes into account all properties of the kernel, enables it to be uniformly approximated and is easily factorized. Such a solution of the problem of approximate factorization makes it possible to write, in a simple explicit form, the principal term of the asymptotic expression of the solution. The nature of the distribution of contact stresses under the stamp is studied, as well as the compliance of the foundation and phase shift between the applied force and the displacement of the stamp.     

Pressure of a plane stamp of nearly circular cross section on an elastic half-space : PMM vol. 40, n 6, 1976, pp. 1143–1145

An approximate method of solving the contact problem of impressing a plane stamp of nearly circular cross section into an elastic half-space is suggested. The friction of the contact surface is neglected. A numerical algorithm for the method is produced. An elliptical and rectangular stamps are considered as examples.There is no general method of solving the problems for stamps of nearly circular cross section. Apart from the classical problem of a plane elliptical stamp, the literature gives solutions for the problems of polygonal stamps, with each problem however requiring a different approach. An approximate solution for the problem of impressing a stamp of nearly circular cross section into an elastic half-space is given in [1]. The method makes it possible to use the same approach to solve the contact problem for an arbitrary region of contact, and to construct an universal numerical algorithm. The program can be adapted to each particular case by making the corresponding changes in the procedure of computing the Fourier coefficients of the equation of the boundary of the area of contact. Below a numerical algorithm for the approximate method in question is given. A more effective formulation of the solution is given for the case of the elliptical stamp.     

基于支持向量机的大豆产量预测研究

应用支持向量机(SVM)的算法进行中国大豆产量的预测研究,用1991-2008年中国大豆数据组成样本集,建立影响因素与大豆产量之间的SVM模型.利用SVM对输入和输出数据进行训练学习,逼近历史数据所隐含的函数关系,完成对新数据序列的映射关系,从而完成对未来年份大豆的预测,并与其它几种方法的预测效果进行比较.结果表明,SVM预测模型预测大豆产量的精度优于其它预测方法.     

Plane contact problem of the indentation of a stamp into an elastic wedge

We consider the contact interaction of a stamp with rectilinear base and an elastic wedge. One of the wedge faces is fixed, and the stamp edge touches the wedge vertex. Using the Wiener–Hopf method, we have obtained an exact solution of this problem. We have also determined the stress distributions in the contact region and on the wedge fixed face as well as the displacements of its free boundary.