基于模糊综合评判方法的土壤重金属污染度研究

本文应用模糊综合评判方法对城区的土壤污染情况进行评估,根据土壤重金属污染等级标准,确定隶属度函数的类型,并把土壤污染分为低污染、中等污染和高污染三个级别。按照隶属度最大的原则,确定各功能区样本点的污染级别,进而对各功能区的污染情况进行分析。     

重金属污染评价及其污染源识别

重金属污染综合防治被纳入十二五规划.对土壤重金属污染物来源的评价和准确鉴别,是有效控制和治理污染源的前提.对采集的金属污染数据,采用主成分综合评价与内梅罗综合评价,结合克里金描述金属污染的空间分布.对数正态分布确定污染源个数,建立分段加权高斯扩散模型,遗传算法搜索污染源.     

北京市大气环境质量的模糊综合评价

为对北京市近几年的大气环境状况有一个全面客观的了解,选取SO_2,NO_2,PM_(10)三个污染因子作为评价参数,采用模糊综合评价法对其2006-2012年大气环境质量状况进行了定量分析和评价.研究表明:2006年到2012年北京市大气环境质量有了很大程度的改善,在常规检测污染物的治理方面有了较好的成效,但空气质量仍处于轻度污染的水平,PM_(10)为近年来主要污染物中权重最大的因子.根据研究的结果,最后提出了相应的政策建议,并解释研究结果与居民感受形成反差的原因.     

基于大数据的在线课程熵权Topsis评价模型研究

为推动供给侧课程评价改革、提高在线课程质量,构建了基于大数据的在线课程评价模型,从课程资源构建、学习过程和教学成效3个方面评估在线课程质量,丰富了在线课程评价的理论模型和指标体系.利用因子分析和熵权法计算评价指标的权重,并将加权重的TOPSIS多属性决策排序跟专家综合打分评价结果做相关性分析,两者呈显著的正相关关系.模...     

城市表层土壤重金属污染风险等级评价

利用MATLAB软件编写程序作图,直观得到重金属污染元素Hg,Cu,Zn,Cr,Pb,Cd,Ni,As在不同区域(生活区、工业区、山区、主干道路、公园绿地区)的空间分布,并且对同一区域各种重金属的含量浓度作图,直观得出了各个区的污染情况.为了从理论上进行说明,利用单因子指数法计算出土壤中各项污染因子的含量,然后用尼梅罗综合污染指数法对不同区域的污染程度进行定量分析,得出生活区、工业区、山区、主干道路、公园绿地区的综合污染指数依次为(3.1706,13.1887,1.2735,9.3696,2.7003),从而确定了某城区重金属的主要污染源.以此能够更为科学、综合的评价该区域内总体土壤质量状况.     

京津冀区域经济发展、社会稳定与雾霾防控协同发展分析

探究京津冀地区经济发展、社会稳定与雾霾防控评价指标的建立,采用指数功效函数、层次分析法对数据及指标进行处理,并构建评价模型对京津冀地区雾霾防控、经济发展与社会稳定进行综合评价,根据评价结果对雾霾防控指标进行约束性分析,分别得到雾霾防控指数与经济发展和社会稳定两个指数约束下的雾霾防控指数的散点图,最后根据散点图分析讨论了京津冀地区经济发展能力不均、社会稳定与雾霾防控相互制约.研究结论可以为京津冀区域各级政府雾霾治理与发展模式选择提供理论依据.     

基于信息熵的城市扬尘治理方案优选决策

城市扬尘的治理需要考虑到成本、效果以及对周围环境的影响等诸多因素,我国扬尘治理方案呈现明显的单一性和定性描述.因此,如何准确认识扬尘治理方案多属性决策对扬尘治理的实际工作具有重要意义.构建了城市扬尘治理方案优选评价指标体系,采用信息熵理论对方案优选的科学性和有效性进行实证研究.结果表明,抑尘周期和成本系数对扬尘治理方案优选具有较大的影响力,高压清洗方案可操作性高,适应性强,为最优方案;基于信息熵理论的扬尘治理方案优选决策计算简单,评价结果客观全面,可以很好的综合反映道路扬尘治理方案优选决策,可为城市扬尘治理提供科学依据.     

软件质量评估的Vague集方法应用研究

通过回顾软件质量评估领域的研究现状,分析了采用Vague集方法进行评价的可能性.提出在定性评价的基础上,借助定性指标向Vague值得转化,通过构建加权综合评价函数的方法实现了Vague集的软件质量评估.最后,通过案例计算,得到了公平公正的评价结果,并验证了计算结果的可靠性.     

基于模糊数学的城市桥梁技术状况评价

准确的评价城市桥梁的技术状况是保证其运营安全与养护决策的前提.由于影响城市桥梁技术状况的因素复杂多样,综合考虑桥面系、上部结构、下部结构指标构建了城市桥梁技术状况综合评价体系.以保定城市桥梁的检测项目为依托,基于上述三个指标,提出了基于模糊数学的大陆性季风气候区城市桥梁技术状况评价方法.结果表明:(1)随着时间的推移,城市桥梁桥面系质量状况与上部、下部结构状况相比,衰退趋势明显,主要与影响其性能的气候及交通状况有关;(2)研究使用因子域、注释级别域、模糊关系矩阵、评价因子全矢量和模糊综合评价结果向量五步法,该方法可以有效的与规范中使用的评分指标相结合;(3)在规范中采用的多指标综合评估的基础上,通过模糊数学的迭代运算,突破了传统评估方法的主观随意性,改进了评判分析的不确定性,对城市桥梁技术状况进行了定量评估;(4)研究结果为城市桥梁技术状况的准确评价和分析提供了理论方法,也为城市桥梁养护及决策提供了技术支撑.     

水电工程应急能力模糊可变评估方法研究

针对水电工程应急能力评估的问题,综合运用可变模糊集理论,提出水电工程应急能力模糊可变评价方法.首先,通过分析水电工程应急能力构成要素,构建应急培训、应急预案与演练、危险源辨识与排查、应急保障体系、监测预警、现场处置等六类评价指标;其次,通过定义应急能力等级评价的模糊可变问题,分别计算样本指标对标准区间的级别相对隶属度和综合相对隶属度,构建应急能力模糊可变评价模型;然后,采用可变模糊迭代方法确定客观权向量,融合决策者的经验和主观偏好,调整评价权重.最后,以溪洛渡工程为例,表明方法综合使用主客观权重,提高了评价的可靠性与科学性.     

Linear birth and death models and associated Laguerre and Meixner polynomials

We study birth and death processes with linear rates λ_n = n + α + c + 1, μ_{n + 1} = n + c, n 0 and μ₀ is either zero or c. The spectral measures of both processes are found using generating functions and the integral transforms of Laplace and Stieltjes. The corresponding orthogonal polynomials generalize Laguerre polynomials and the choice μ₀ = c generates the associated Laguerre polynomials of Askey and Wimp. We investigate the orthogonal polynomials in both cases and give alternate proofs of some of the results of Askey and Wimp on the associated Laguerre polynomials. We also identify the spectra of the associated Charlier and Meixner polynomials as zeros of certain transcendental equations.     

Distributive and Multiplication Modules and Rings

We study rings in which every ideal is a finitely generated multiplication right ideal.     

Affine-inscribed and affine-circumscribed polygons and polytopes

Five theorems on polygons and polytopes inscribed in (or circumscribed about) a convex compact set in the plane or space are proved by topological methods. In particular, it is proved that for every interior point O of a convex compact set in ℝ³, there exists a two-dimensional section through O circumscribed about an affine image of a regular octagon. It is also proved that every compact convex set in ℝ³ (except the cases listed below) is circumscribed about an affine image of a cube-octahedron (the convex hull of the midpoints of the edges of a cube). Possible exceptions are provided by the bodies containing a parallelogram P and contained in a cylinder with directrix P. Bibliography: 29 titles. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 231, 1995, pp. 286–298. Translated by B. M. Bekker.     

Partitions and pairwise sums and products

A seven cell partition of N is constructed with the property that no infinite set has all of its pairwise sums and products in any one cell. A related Ramsey Theory question is shown to have different answers for two and three cell partitions.     

Ritz and harmonic Ritz values and the convergence of FOM and GMRES

The Ritz and harmonic Ritz values are approximate eigenvalues, which can be computed cheaply within the FOM and GMRES Krylov subspace iterative methods for solving non‐symmetric linear systems. They are also the zeros of the residual polynomials of FOM and GMRES, respectively. In this paper we show that the Walker–Zhou interpretation of GMRES enables us to formulate the relation between the harmonic Ritz values and GMRES in the same way as the relation between the Ritz values and FOM. We present an upper bound for the norm of the difference between the matrices from which the Ritz and harmonic Ritz values are computed. The differences between the Ritz and harmonic Ritz values enable us to describe the breakdown of FOM and stagnation of GMRES. Copyright © 1999 John Wiley & Sons, Ltd.     

Beliefs and beyond: affect and the teaching and learning of mathematics

The importance of beliefs for the teaching and learning of mathematics is widely recognized among mathematics educators. In this special issue, we explicitly address what we call “beliefs and beyond” to indicate the larger field surrounding beliefs in mathematics education. This is done to broaden the discussion to related concepts (which may not originate in mathematics education) and to consider the interconnectedness of concepts. In particular, we present some new developments at the conceptual level, address different approaches to investigate beliefs, highlight the role of student beliefs in problem-solving activities, and discuss teacher beliefs and their significance for professional development. One specific intention is to consider expertise from colleagues in the fields of educational research and psychology, side by side with perspectives provided by researchers from mathematics education.