The Indoor Air Quality Programme of the WHO Regional Office for Europe

The indoor air quality (IAQ) programme of the World Health Organization Regional office for Europe was initiated in the mid-seventies when it was realized that over 70% of the general population spends its time indoors in homes, office buildings, schools, hospitals, transportation means, etc. The first meting of experts on health aspects related to IAQ was convened in 1979, being probably the first international meeting on IAQ with participation from eastern and western Europe as well as from North America. Seven meetings followed between 1982 and 1990, at which the “sick building” syndrome, IAQ research, formaldehyde and radon, organic pollutants, biological contaminants, combustion products, and mineral fibres were discussed. A ninth meeting on sources, control and mitigation is planned for 1991.     

The Possible Role of Indoor Radon Reduction Systems in Back-Drafting Residential Combustion Appliances

Abstract A computational sensitivity analysis was conducted to identify the conditions under which residential active soil depressurization (ASD) systems for indoor radon reduction might most likely exacerbate or create back-drafting of natural-draft combustion appliances. Parameters varied included: house size; normalized leakage area; exhaust rate of exhaust appliances other than the ASD system; and the amount of house air exhausted by the ASD system. Even with a reasonably conservative set of assumptions, it is predicted that ASD systems should not exacerbate or create back- drafting in most of the U.S. housing stock. Only at normalized leakage areas lower than 3 to 4 cm² (@ 4 Pa) per m² of floor area should ASD contribute to back-drafting, even in small houses at high ASD exhaust rates (compared to a mean of over 10 cm²/m² determined from data on over 12,000 U.S. houses). But on the other hand, even with a more forgiving set of assumptions, it is predicted that ASD systems could contribute to back-drafting in some fraction of the housing stock – houses tighter than about 1 to 2 cm²/m²– even in large houses at minimal ASD exhaust rates. It is not possible to use parameters such as house size or ASD system flow rate to estimate reliably the risk that an ASD system might contribute to back-drafting in a given house. Spillage/back-draft testing would be needed for essentially all installations.     

中国第一个氡及氡子体刻度和试验装置

我国第一个氡及氡子体刻度和试验装置(简称氡室)已于1988年建立。本文介绍了该氡室的构成,测控能力及其技术服务项目。现已应用于氡及氡子体测量仪的刻度、比对和性能测试,在应用中进一步完善了测控能力。     

测氡在煤矿采空区的应用

通过对采空区氡异常的分析，说明了地面测氡方法的可行性，并以锁簧镇中学办公楼的采空区探测为例，进一步说明测氡在煤矿采空区的应用。     

基于ERS2S测氡仪的氡析出率准确测量研究

氡析出率的测定是废石堆、尾矿堆监测治理中的重要指标,德国ERS2S氡钍射气析出率测量仪提供了线性拟合和指数拟合两种数据处理方式,在实际工作中往往出现难以确定选择使用何种数据处理方式能得到较为准确的氡析出率。针对该问题本文从线性拟合和指数拟合两种计算方法的理论模型入手,分析两种拟合方法的适用范围。研究表明线性拟合适合短时间测量,随着测量时间的增加,线性拟合计算的氡析出率误差将会不断增大。指数拟合需要测量数据较多,短时间测量时容易产生较大误差,长时间测量拟合度较好。研究成果有利于使用ERS2S测氡仪准确测量氡析出率,同时也为氡析出率的新测量方法的研究提供了理论、实践基础。     

ATE射频测试板低成本解决方案

近年来国内无线通讯市场发展迅猛,射频芯片的出货量也快速增长,射频芯片不同于其他SoC芯片,往往是市场周期短,更新速度快,这给芯片的量产测试带来挑战,ATE射频测试板作为测试的重要组件,成为制约测试开发和成本的最关键因素,ADVANTEST推出的低成本射频测试板兼顾了开发效率和测试成本的平衡性,给射频芯片的量产测试带来了...     

矢量Radon变换波场分离方法研究现状与展望

保持地震波场矢量特征的波场分离是多分量地震数据处理的核心问题之一。为提高多分量波场分离精度,基于传统Radon变换的优势,探讨了矢量Radon变换保持波场特征的可行性。首先,在分析传统Radon变换基础上,阐述了基于组稀疏的矢量Radon变换实现保持矢量波场振幅特性的纵、横波分离方法,并将其应用于模型数据的纵、横波分离;其次,介绍了复矢量Radon变换压制多分量地震数据面波干扰的处理方法,并展望了复矢量Radon变换在多分量地震数据处理中纵、横波分离和快、慢横波分离的应用前景。模型数据应用结果表明,基于组稀疏的矢量Radon变换波场分离方法能够保持多分量地震数据的矢量特性,并能获得好于非矢量Radon变换的纵、横波分离结果。     

λ-f域三维抛物Radon变换多次波压制方法

通常情况下,应用Radon变换压制多次波,一般是对正变换的模型空间进行处理,再反变换回时空域,而Radon域能量团的收敛性直接影响多次波去除效果,且求解过程中需反复进行矩阵的逆运算,计算成本偏高。为此,基于二维抛物Radon变换,借鉴Abbad等的方法,首次提出λ-f(λ为曲率q与频率f的乘积)域三维抛物Radon变换多次波压制方法,将常规三维抛物Radon变换的f-q_x-q_y(q_x、q_y分别为横、纵向离散曲率)域转换到一个全新的λ_x-λ_y-f(λ_x=q_xf、λ_y=q_yf)域,继承了二维λ-f域Radon变换思路。通过引入新的变量λ_x和λ_y,消除常规Radon算子对频率的依赖,减少了矩阵运算次数,显著提高了计算效率;根据一次波和多次波能量在λ-f域空间分布特征,设计三维椎体滤波器,更有效地分离一次波和多次波,降低空间截断效应引起的误差。理论模型及实际数据测试表明：1所提方法降低了空间截断效应的影响,消除了变换算子对频率的依赖,有效减少了矩阵求逆运算次数,较常规三维Radon变换方法的计算效率提高了约8倍以上;2所提方法仍然存在Radon类方法的弊端,即当一次波和多次波速度差异较小时,在近炮检距位置无法得到较理想的多次波压制效果。     

基于Radon-WVD变换的编队目标架次识别

针对常规低分辨雷达,研究了编队目标回波的多普勒频率变化特征,提出了采用Radon-WVD法,在时频域对编队目标的整体特性(调频率)进行快速准确的估计。该方法的估计结果不但不受WVD交叉项的影响,而且由于Radon变换的积累特性使得Radon-WVD变换法相对WVD有更好的抗噪声性能。仿真实验验证了该方法的有效性,成功地实现了多架编队飞机架次识别。