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.     

南京站斜拉索锚固节点模型试验

较详细地介绍了南京站主站房斜拉索锚固节点的试验过程 ,包括有限元计算、试验装置设计、试验结果分析等。本次试验工作分为两部分 ,即设计索力试验和 2倍的设计索力试验。通过对试验过程和试验结果的分析 ,研究了这种斜拉索锚固节点的受力特性和可行性 ,为类似节点的设计与试验提供参考和依据。     

确定建筑材料有害物散发量的三种传质模型

室内空气污染源散发量的确定是建立室内空气质量(IAQ)模型的重要步骤之一。目前研究建筑装饰材料和建筑涂料散发污染物的模型主要有经验模型和理论模型两类。经验模型简洁，但应用受到测试条件的限制，不具有普适性。基于传质理论而提出的理论模型目前研究较多，本文对研究建筑材料散发有害物的三个传质模型进行了评述。VB模型是一个简单的溶剂基室内涂料散发的总挥发性有机物(TVOC)的传质模型，低估了污染物的长期散发量。对流传质模型是基于界面平衡所导出的稳态模型，适用于固体和液体等材料的散发过程。Yang等提出的四层传质模型通常需与数值求解结合，计算较麻烦，但能较好地确定建筑材料散发挥发性有机物的散发量。     

大型同步电机启动的节能改造方案

对同步电机启动、加速、励磁模式切换等工作过程中变频器的应用进行了论述，介绍了电网改造的经济方案，提出了变频器在使用时的注意事项，达到既要节能又要省费用的电网改造效果。