人口迁移模型的改进及系统动力学仿真预测

求出了Keyfitz模型和Rogers模型的理论解,并以Rogers模型为例,对人口迁移模型进行了改进,使之适用范围更广.在人口迁移模型的基础上,建立了系统动力学模型,并对江西省的人口迁移问题进行了仿真预测,模拟出了江西省农村人口、城镇人口及城市化率的变化趋势.     

北京市水资源利用建模分析研究

以北京市为例,分别应用无偏灰色GM(1,1)模型和非线性模型对北京市2001年-2010年的用水量进行了建模,利用最优化方法,计算了上述两种模型的最优组合模型,通过三种模型分别计算了北京市2001年-2010年的水资源利用量,并与北京市2001年-2010年的实际用水量进行了对比,采用精度检验方法,分别对无偏灰色模型,非线性模型和组合模型进行了精度检验,计算结果表明,加权组合模型是三种模型中精度最高的模型,通过组合模型计算得出的用水量值与实际水资源利用量相比误差最小,由此得出,可以利用组合模型对北京市未来的水资源利用量进行预测,预测结果可为其他相关研究提供参考.     

灰色绝对关联度的改进模型

基于刘思峰教授提出的灰色绝对关联度模型,提出了一点改进,给出了新的灰色绝对关联度模型,并讨论了新模型的性质及其算法.一方面保持了原绝对关联度模型的优点,另一方面改正了原模型在某些方面的不足.     

门限自回归滑动平均模型——TARMA

一、引言 近年来,时间序列的理论及应用得到了很大的发展,各种模型也应运而生。人们在实际应用中越来越感到现有的线性模型,如AR,ARMA模型等,难以很好地刻划复杂的物理现象。因此,对非线性模型的讨论越来越活跃,已经提出了一些非线性模型。但这些模型一般都较复杂,局限性强,建立模型很麻烦,难以推广。1977年,汤家豪提出的门限自回归模型,简称“TAR”(Threshold Autoregression),较好地克服了这些缺点。它的计算复杂性与一般的AR模型相当,且能刻划线性模型难以刻划的物理现象。本文就是基于这一思想,进一步发展了这一模型,提出了一种新的非线性模型——门限自回归滑动平均模型(TARMA)。     

构成型顾客满意模型的偏最小二乘路径建模及其应用

本文研究了偏最小二乘路径建模在顾客满意模型中的应用,特别是引入了构成型关系的模型。本文首先比较了构成型模型和反映型模型的区别,并详尽阐述了构成型模型的偏最小二乘建模原理,接着构建了电信企业顾客满意度指数模型,并考虑了如何在指数模型中引入构成型外部关系.利用该电信企业的数据,比较分析了构成型模型(顾客期望和质量感知潜变量调整为构成型关系)和反映型模型(所有潜变量均为反映型关系)的实证结果,研究表明在为企业提供改善顾客满意水平的信息上两种模型具有较好的相似性,但是构成型模型能够提供更加稳定的结果,从而验证了顾客满意模型中引入构成型模型的可行性.     

成比例附加故障混合模型

Frailty模型和可加故障模型在研究各种风险因素与疾病发生原因的关系中提供了两种重要的方法.在不知哪个模型更适合数据时,涵盖这两个模型的成比例附加故障模型提供了一个备选模型.Frailty基本上是观察不到的,需要考虑对应的混合模型.本文研究了成比例附加故障混合模型的年龄性质、相依性质.并对该模型中的那些随机变量进行了随机比较.     

经济增长的随机AK模型

本文以经济增长AK模型(模型Ⅰ)作为基本模型,将人口数量作为不确定性的来源,建立了经济增长的随机AK模型(模型Ⅱ).分析了模型Ⅱ解的存在唯一性和M arkov性,探讨了模型Ⅱ的零均衡解的稳定性及资本-劳动比率的动态性质.     

房地产行业的数学建模分析

分别建立了需求模型,供给模型,房地产与其他产业的关系模型,房价模型及房地产发展趋势的预测模型,并对影响模型的相应因素做了简要的分析.     

基于可信性理论的投资组合优化问题研究

建立了基于可信性理论的投资组合模型,包括风险最小的单目标均值-方差模型和收益最大的单目标均值-方差模型,运用拉格朗日乘数法对两个模型进行了求解,给出了2个模型解析解的表达式,并通过数值算例验证了模型的可行性.对两个模型的结果进行对比,发现风险最小化和收益最大化的单目标均值—方差模型得到的结果基本吻合.     

多图模型的联合估计的群桥方法

高斯图模型研究独立随机变量之间的关系.主要针对该模型,提出了一种分层惩罚连接单个图模型估计的多图模型.研究了新模型的高维统计性质,给出模型的参数估计,并得到了相合性及稀疏性两大理论.     

Universal algebras

A survey of the development of the theory of universal algebras in the years 1976–1988. Such basic directions of development of this theory as classes of universal algebras (varieties, quasivarieties, etc.), Mal'tsev conditions, congruences, sheaves, homomorphisms, subalgebras, products of algebras, clones of operations, completeness, systems of equations in algeberas, and connections with computer mathematics show up in it. Considerable attention is given to concrete classes of algebras (p-algebras, BCK-algebras, unary algebras, etc.).Translated from Itogi Nauki i Tekhniki, Seriya Algebra, Topologiya, Geometriya, Vol. 27, pp. 45–124, 1989.     

基于DEA-博弈论模型的铁路电子车票实名制查验评价分析

将基于数据包络分析(DEA)模型和纳什讨价还价博弈论结合, 作为一种合作博弈方法, 对铁路电子车票实名制的查验进行了综合评价, 为准确评估铁路电子车票实名制查验的效率, 加强铁路客运服务水平提供决策判断。本文以20个不同等级的铁路车站为研究对象, 分人工和机器两大类, 选取身份证购票比例、通勤员工购票比例、临时身份证购票比例, 以及人工查验旅客数/小时/通道、机器查验的通过人数/闸机/小时、闸机人脸自动识别比例和延误比例等7个指标作为投入指标, 选取人、证、票三证合一的实名制查验比例作为产出指标, 基于数据包络分析(DEA)和纳什讨价还价博弈论结合的合作博弈模型, 从人工查验和机器查验两个角度对铁路电子车票实名制查验进行统一综合评价。案例结果表明, 铁路电子车票实名制查验效率呈现出人工查验和机器查验效率不均衡的态势; 车站人脸识别闸机的数量投入与所需闸机数量的不匹配是造成实名制查验效率下降的主要原因。根据评价结果, 从人工和机器查验两个角度提出了可行建议, 促进了铁路电子车票实名制查验效率的进一步提升。     

统计在生命科学中的实践与认识(Ⅵ) 临床试验(上)

本文回顾了临床试验发展的简史、随机临床试验的主要特征、临床试验实践中所面临的问题和困难，介绍了有关临床试验研究和应用的近展     

In Defense of Logical Universalism: Taking Issue with Jean van Heijenoort

Van Heijenoort??s main contribution to history and philosophy of modern logic was his distinction between two basic views of logic, first, the absolutist, or universalist, view of the founding fathers, Frege, Peano, and Russell, which dominated the first, classical period of history of modern logic, and, second, the relativist, or model-theoretic, view, inherited from Boole, Schr?der, and L?wenheim, which has dominated the second, contemporary period of that history. In my paper, I present the man Jean van Heijenoort (Sect. 1); then I describe his way of arguing for the second view (Sect. 2); and finally I come down in favor of the first view (Sect. 3). There, I specify the version of universalism for which I am prepared to argue (Sect. 3, introduction). Choosing ZFC to play the part of universal, logical (in a nowadays forgotten sense) system, I show, through an example, how the usual model theory can be naturally given its proper place, from the universalist point of view, in the logical framework of ZFC; I outline another, not rival but complementary, semantics for admissible extensions of ZFC in the very same logical framework; I propose a way to get universalism out of the predicaments in which universalists themselves believed it to be (Sect. 3.1). Thus, if universalists of the classical period did not, in fact, construct these semantics, it was not that their universalism forbade them, in principle, to do so. The historical defeat of universalism was not technical in character. Neither was it philosophical. Indeed, it was hardly more than the victory of technicism over the very possibility of a philosophical dispute (Sect. 3.2).     

区域资源禀赋、成本约束与农业生产效率测度

农业是我国基础产业,是保障粮食安全和经济发展的根本。根据经济发展战略要求和区域资源禀赋,合理发展区域农业,提升农业对区域资源使用效率和区域资源产业配置效益,形成区域农业高效发展和资源最优配置,是区域经济发展战略的重要内容。在柯布道格拉斯生产函数的基础上,利用随机前沿技术效率测度、产业投入产出分析、偏离-份额分析,构建农业产业生产效率的测度模型,探索地区农业产出的技术效率、资源利用效率和使用效率,为农业生产和区域资源配置提供参考。结果表明,大部分区域农业产出与资源禀赋未形成最佳匹配,应在大力提高农业对区域内资本资源、政府服务资源和劳动力资源使用效率的同时,鼓励过剩的资源在产业间和区域间进行适度转移,从低使用效益产业转移到高使用效益产业,从低产出弹性区域转移到高产出弹性效益区域。     

Quality rating of a metal matrix-diamondcomposite from its thermal conductivity and electric resistance

The efficiency of hot-pressed diamond-containing composite materials (DCM) for various tool applications is greatly affected by microdefects, namely, the residual porosity of the metal matrix, damaged diamond grains, and imperfect diamond-matrix interfaces. An instrumental evaluation of these microdefects, predetermining the quality of a tool equipped with DCM, is rather difficult due to the small size, the nonstandard shape, and the strong heterogeneity of specimens. Proposed here is an alternative, nondestructive technique of DCM quality rating, which includes the measurement of electric resistance and thermal conductivity of diamond-containing composites and processing the obtained data by the methods of composite mechanics. It exploits the fact that diamond, being a dielectric, possesses an extremely high thermal conductivity, which allows estimating the residual porosity of a sintered metal matrix from the ratio of specific electric resistances, one being measured and another predicted by a theory. These data, in turn, are utilized to predict the thermal conductivity ofDCMwith an imperfect matrix. Matching with experiments, after solving the inverse problem gives the thermal resistance of diamond-matrix interface, which, within the frame work of the given model, simulates the damage of both the diamond grains and their bonds with the matrix. Thus, the numerical rating of quality is given in terms of two dimensionless parameters. The first one, 0 < K < 1, reflects the quality of the sintered metal matrix, whereas the second one, 0 < R <1, is an aggregate measure of the integrity of diamond grains and the perfection degree of composite interfaces. The quite satisfactory agreement observed between the theory and experiment confirms the efficiency of the technique and the reliability of the data obtained. Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 3, pp. 361–374, May–June, 2006.     

城市老旧居住小区交通环境评价指标与评价方法

定量的评判城市老旧居住小区整体交通环境质量并进而科学有效的提出老旧小区交通环境更新与改善措施,对城市老旧居住小区交通环境进行了调查,明确了老旧居住小区存在的突出交通问题,并提出了城市老旧居住小区交通环境评价的指标体系,包括行人跨路出行指数、无人行道路段长度占比、停车泊位供需比、路内非法停车占比、平均停车步行距离、泊位数量户数比、人均步行空间、无障碍通道、盲道设置比例、非机动车泊位供需比、地面停放车辆数小区面积比、外部穿行交通周转量小区面积比等。并给出了具体指标的计算方法与获得办法。以长沙市四个典型老旧居住小区为例,对评价方法进行了论证,并得到城市老旧居住小区存在的一般问题,包括人车混杂、人车交织现象严重,停车泊位短缺、车辆乱停乱放,交通设施、特别是弱势群体交通设施缺乏。给出的评价指标、评价方法与结论可为城市老旧小区改造更新,特别是其中很重要的交通环境更新提供决策依据。     

一個多元函數的內插公式

本文介绍一个新型多元函数结构.它在一定条件下: 1)可根据一定的已知数值决定函数的其他近似值, 2)可作为构成经验公式的骨架.     

On free products in varieties of associative algebras

Varieties of associative algebras over a field of characteristic zero are considered. Belov recently proved that, in any variety of this kind, the Hilbert series of a relatively free algebra of finite rank is rational. At the same time, for three important varieties, namely, those of algebras with zero multiplication, of commutative algebras, and of all associative algebras, a stronger assertion holds: for these varieties, formulas that rationally express the Hilbert series of the free product algebra via the Hilbert series of the factors are well known. In the paper, a system of counterexamples is presented which shows that there is no formula of this kind in any other variety, even in the case of two factors one of which is a free algebra. However, if we restrict ourselves to the class of graded PI-algebras generated by their components of degree one, then there exist infinitely many varieties for each of which a similar formula is valid. Translated fromMatematicheskie Zametki, Vol. 65, No. 5, pp. 693–702, May, 1999.