基于车桥耦合振动分析的桥梁损伤诊断方法评述

车辆通过桥梁时,桥梁和车辆的动力响应都包含桥梁结构模态或者几何参数信息,对它们进行分析能识别桥梁的模态参数和损伤。结合国内外最新研究成果,综述基于车桥耦合振动分析的桥梁结构损伤识别技术,并与传统识别方法进行比较。指出其优缺点;详细介绍基于灵敏度分析和模型修正的方法、基于结构刚度搜索的方法、利用车辆响应傅立叶变换识别桥梁频率的方法、利用车激桥梁响应的小波变换识别桥梁模态参数的方法以及综合利用车辆和桥梁响应识别桥梁损伤的方法等5种参数识别与损伤诊断方法的基本原理,并总结上述方法的实施步骤和应用时应该注意的问题;指出了该领域的关键问题和进一步的研究方向。     

稀土氧化物催化还原烟气中的SO2

在实验室研究结果的基础上，建立了小型实际燃煤烟气脱硫试验装置，采用实际燃煤烟气进行了稀土氧化物催化还原烟气脱硫的试验，考察了空速、反应温度对脱硫率的影响。试验结果表明，在反应温度520～550℃、空速2800h。的条件下，脱硫率为99％，NOx的去除率为95％，SO2最高排放质量浓度为100mg／m^3，NOx最高排放质量浓度为50mg／m^3，符合GB13223-2003《火电厂大气污染物排放标准》2时段标准，与实验室的实验结果基本吻合。     

安全管理评价的基本思想及方法探讨

由于事故的主要原因是管理缺陷,所以通过对企业的安全管理工作进行分析与评价能有效预防事故发生,减少事故损失,大大提高企业的安全管理水平.从评价的基本原理出发,提出安全管理评价,分析了安全管理评价的目的、要求和作用,阐述了安全管理评价的基本思想,并对目前适用于安全管理评价的方法进行了分析与比较.     

某公路边坡锚杆支护系统的安全评价

对某公路节理岩质边坡的安全稳定性进行分析,并提出支护措施。通过FLAC3D建立计算模型,采用强度折减法计算安全系数,得到边坡在未支护情况下的安全系数为0.67,处于不稳定状态。采用全长注浆锚杆进行支护。建立正交试验,以安全系数和工程造价为目标,以锚杆的长度和倾角为因素,得到6 m,2 m,20°的参数优化方案。计算表明,边坡支护后安全系数为1.29,处于稳定状态。同时,得到边坡在开挖扰动和锚杆支护情况下,各个部位的静态位移和动态位移响应,表明:锚杆支护有效地限制了位移的发展,有利于边坡稳定。     

GIS在广西香蕉低温冻害分析中的应用

根据香蕉生长状况、受害程度与低温冻害强度的关系,确定香蕉冻害的等级指标;利用广西90个气象台站30年的气候资料和台站地理信息,建立冻害指标的空间分析模型,采用GIS技术推算出1km×1km分辨率的冻害指标空间分布;并根据香蕉冻害分级指标,通过GIS的空间分析能力,分析了广西香蕉低温冻害的空间分布特征。     

宁波市公民防灾应急状况调查研究

为了解公民关于应急知识的掌握情况,也为制定应急宣传教育方法和重点教育内容提供依据,采用自编问卷对1 318名公民进行了调查。结果显示,宁波市公民防灾应急意识状况总体良好,但存在显著的性别差异、城乡差异、文化程度差异、年龄差异和职业状态差异。     

Concentration-time exposure index for modeling soil fumigation under various management scenarios

Best management decisions in soil fumigation require informed management selections of soil type, field geometry, application dosage, and depth to maximize fumigant distribution for efficacy and minimize off-site transport for environmental safety. An efficacy- or exposure-based concentration-time exposure index (CTEI) was used to serve as a continuous quantitative efficacy assessment for soil fumigation by subsurface drip irrigation using numerical model simulations. The CTEI was defined as the ratio between the soil volume where concentration-time (CT) exceeded a threshold value for a particular pest-fumigant combination and the total soil volume required for fumigation treatment. Applications of CTEI as a simple efficacy index were demonstrated by simulating combinations of three soil types (loam, sandy loam, sand); three field configurations consisting of 102- and 203-cm-wide bed systems and a flat surface system; three application depths (15, 30, 45 cm); and two application rates (82 and 327 kg ha(-1)) for 1,3-dichloropropene against citrus nematode (Tylenchulus semipenetrans) using a threshold air-phase CT value of 12 microg h cm(-3) obtained from a separate field study. For soil fumigation by subsurface drip irrigation, the order of importance in optimizing CTEI was soil type, depth of application and depth of treatment, dosage, and field configuration. Model simulation using CTEI as a numeric efficacy index can be an effective alternative to assist in the planning of field trials for making final management decisions concerning soil fumigation or other pesticide applications.     

Speciation of heavy metals in marine sediments from the East China Sea by ICP-MS with sequential extraction

Twelve elements (V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Sn, Cd and Pb) in 24 sediment samples at eight sites (S1-S8) from the East China Sea were analyzed with the BCR sequential extraction (SE) protocol to obtain the metal distribution patterns in this region. The results showed that the heavy metal pollutions in S4 and S8 were more severe than in other sampling sites, especially Cd and Pb pollution. In the top sediments at S4 and S8, both the total contents and the most dangerous non-residual fractions of Cd and Pb were extremely high. More than 90% of the total concentrations of V, Cr, Mo and Sn existed in the residual fraction. Fe, Co, Ni, Cu and Zn mainly (more than 60%) occurred in the residual fraction. While Mn, Pb and Cd dominantly presented in the non-residual fractions in the top sediments. The metal distribution patterns with depth and the correlations between total organic carbon (TOC) and the total Fe-Mn content were also investigated. The results showed that, for most of the elements except Fe, the concentration of elements in fraction A in the top sediments was higher than that in other depth. The similar rule was also found in fraction B but not in fraction C. Besides, the distributions of V, Cd in fraction B and Pb, Cd, Cu in fraction C might be affected by TOC.     

A Comparison Between Corrosion Rates and Runoff Rates from New and Aged Copper and Zinc as Roofing Material

Recently there has been anincreased environmental concern in severalcountries in Europe, in particular in Sweden andin the Netherlands regarding the amount of copperand zinc that is released from building materialsinto society. Due to lack of runoff data, thelegislators have so far used corrosion ratesmeasured during the last 20 years to calculatequantities of metal released from buildingsassuming that the quantity of metal corrosionequals the quantity of metal runoff. Withdecreasing levels of environmental pollutantsduring the last decade in Europe, it is importantto determine more recent and hence morerepresentative corrosion and runoff rates to beused in the calculations. For this reason a field exposure program was implemented during 48 weeks in an urbanatmosphere in Sweden determining corrosion andrunoff rates for copper and zinc of differentage. New copper exposed for 48 weeks in the urbanatmosphere shows a corrosion rate of 6.7gm^-2y^-1 and an almost constant runoff rate of1.3 gm^-2y^-1 during the period. Therunoff rate is significantly lower than thecorrosion rate and represents only a fraction(20%) of the total amount of corroded metalduring this period. Zinc shows a graduallydecreasing corrosion rate with time being 5.0gm^-2y^-1 after 48 weeks of exposure. Therunoff rate is relatively stable with an averagerate of 3.1 gm^-2y^-1 during the sameperiod. This value represents 60% of the totalamount of corroded zinc. The effect of panel age has been investigatedin parallel field and laboratory studies. Theresults show that naturally aged copper exhibitssomewhat higher average runoff rates (2 gm^-2y^-1) than new copper, probably due to acombined effect of storage and weatherconditions. No significant difference in runoffrate can be found between new and naturally agedzinc. The field and laboratory investigationsshow that precipitation rate and amount influence the magnitude of the runoff rate forboth copper and zinc.     

基于GIS的北京市机动车污染数据库的开发和应用

利用 GIS技术建立机动车污染数据库 ,能动态、直观地反映机动车污染的时空分布规律 ,为机动车污染控制研究提供强有力的工具 .本研究以 ArcView为主要的 GIS开发工具 ,通过属性数据和空间数据的链接 ,实现了北京市机动车污染数据库的地图化表现、动态查询、基本空间分析等功能 ,从而为机动车污染数据库提供了技术支持 .利用该系统 ,可以对北京市机动车污染物的排放、浓度和分担率的空间分布规律进行 GIS实例分析 .