黄土力学数据挖掘系统研究

岩土工程智能化系统研究是岩土工程领域前缘问题。本文基于信息技术中最先进的数据挖掘技术,研制了黄土力学数据挖掘系统,包括有预处理模块、挖掘操作模块、知识库管理模块,自重湿陷与湿陷性判定决策树模型、判定规则和评价模型的精度以及其他应用软件接口等。可实现数据的归约、聚类分析、分类、预测等。通过工程实例分析,证明了该系统的有效性和实用性。采用59项工程的2766组黄土试验数据对决策树的每条规则进行测试,结果表明自重湿陷性判定规则的准确率为87.3%,湿陷性判定规则的准确率为92.5%。利用挖掘所得到的判定规则和决策树模型,可减少试验工作、降低成本;提出的模型还可用于确定湿陷底界与自重湿陷的底界,从而为地基处理深度的确定提供依据。     

路基土回弹模量应力依赖性分析及预估模型

通过室内重复加载三轴试验研究4种常用路基土的回弹特性,分析回弹模量对体应力、侧向应力、偏应力的依赖关系。试验结果表明,回弹模量值是两个应力变量的函数,且当其中一个变量保持不变时,回弹模量值随另一变量呈非线性变化,函数关系应为幂函数形式。在此分析基础上,参考Uzan模型表达式,以偏应力和体应力为变量回归得出相应的路基土回弹模量预估模型,拟合结果良好。模型的建立,有利于更好地理解路基土的回弹特性,并为路基模量设计值的取用与路面结构力学响应计算提供可靠的技术依据。     

低强度自密实混凝土在竖向薄型构件中的应用分析

目前国内外低强度自密实混凝土尚处于试验研究阶段,应用研究较少.通过试验室模型试验,提出了低强度自密实混凝土的施工配合比,并应用于工程中的竖向薄型构件,取得了较好的效果.     

肋片管式换热器表面结霜问题的研究

针对平肋肋片管式换热器的结霜过程，建立了数学模型，考虑了霜层密度变化和霜层阻力引起空气流量减小等因素。对结霜量随时间的变化和霜层密度的变化进行了数值分析和实验研究，模型计算结果和实验结果吻合得较好。     

灯光元素的数字化描述

基于对灯光元素的分析，引入灯光的特征参数以表征城市灯光景观的效果。并定义了包括光色参数、光形参数、多媒质参数、增强参数和环境参数的特征参数向量和关联矩阵模型，从而建立起进行灯光环境规划的现代数学分析的基础，为系统工程学分析方法应用于城市规划提供了一个平台。     

李坝金矿地质-地球物理找矿模型及远景评价

通过对李坝金矿控矿因素和岩、矿石地球物理参数的研究以及对地球物理异常的分析和推断，建立起矿田地质－地球物理找矿模型，并应用于找矿预测，已获得很好的找矿效果。     

堤防工程生态固坡浅析

阐述了堤防工程中生态固坡技术的一般性原理，着重分析了生态固坡的岩土力学效应。参照树根桩计算的力学模式，把根系考虑为摩擦桩，根据加固后边坡中的力学平衡条件建议了深粗根加固坡体计算的本构模型。介绍了几种生态固坡新技术。     

Housing location choices of the poor: does access to jobs matter?

Abstract

This research investigates whether access to jobs affects poor households’ residential location choices using data from individual households in the Chicago Metropolitan Area. Our results, based on discrete choice models, show that the effects of job accessibility on household location choices are contingent upon households’ automobile ownership and employment status. Places with higher job accessibility by public transit mode are more likely to attract poor households that do not own cars but have at least one employed worker or one labour force participant, while job accessibility by automobile travel mode has no positive effect on the location choices of poor households who own automobiles. The results stress the importance of job accessibility for those poor households with limited transportation mobility but strong needs for access to jobs.     

Assessment of contaminant diffusivities in building materials from porosimetry tests

Recent studies have shown that surface and gaseous contaminant interactions may play an important role in indoor air quality. Modeling is an important tool to improve our knowledge about the phenomena involved and define appropriate ventilation strategies. However, data for sorption isotherms and diffusion in building materials remain woefully lacking. This paper deals with the latter point. It aims at investigating a methodology based on an analysis of the material porosity first and then the application of Carniglia's mathematical model to determine the effective diffusivity of gaseous species in building materials. This methodology, whose main principles are presented in the first part of the paper, was applied to seven commonly found materials. Mercury intrusion porosimetry (MIP) tests, and the calculations using Carniglia's model, reveal typical total porosities and tortuosity factors for these materials. The analysis of pore size distributions (PSDs) also draws one's attention to the possible differences in the pore structures that may exist between two samples of the same type of material and the differences in the effective diffusivities of contaminants that may result from them. The computed effective diffusivities were subsequently compared to data from experiments carried out in the frame of the EC project MATHIS. An agreement was obtained, thus validating Carniglia's methodology - a methodology that offers many practical advantages compared to diffusion-cell methods.     

重物高空坠落撞击多层钢筋混凝土楼板的仿真计算分析

本文针对重物高空坠落高速撞击钢筋混凝土楼（屋）盖时的结构损伤分析，根据弹塑性靶板理论以及动能守恒定理提出了一种计算板及周边梁中内力的简化手算算法。计算结果和现场实测资料吻合，说明该算法可以用于实际工程。