γ能谱仪在室内环境中的辐射测量技术研究

对于室内环境中的电离辐射剂量测量,常用碘化钠探测器进行总量测量,由于该探测器对不同能量的γ射线响应相差较大,而总量测量未进行能量剂量响应修正,因此测量结果误差较大,影响了室内环境辐射剂量检测的准确性。论文介绍了γ能谱仪测试室内环境中的辐射剂量研究结果。     

Virtual reality-based evaluation of indoor earthquake safety actions for occupants

Evaluations of indoor earthquake safety actions can provide effective guidance for occupants, and can be beneficial for reducing earthquake-induced casualties. Accordingly, in this study, a virtual reality (VR)-based evaluation method is proposed for indoor earthquake safety actions. Specifically, an indoor seismic damage scene is constructed based on the Federal Emergency Management Agency (FEMA) P-58 method and a physics engine, by which the damage and movements of indoor nonstructural components can be accurately calculated. Subsequently, a virtual body model is created, and a corresponding inverse kinematics (IK) algorithm is developed to accurately track the earthquake safety actions of occupants. Finally, a human safety model based on collision kinetic energy and fatal conditions is designed for quantitatively evaluating the effectiveness of earthquake safety actions. Taking an office room and living room as case studies, three earthquake safety actions (i.e., “drop, cover, and hold on,” “triangle of life,” and “run outside”) are evaluated using the proposed method. The results indicate that “drop, cover, and hold on” is the safest action in most earthquake scenarios. The outcomes of this study can be used to rate the effectiveness of various earthquake safety actions, and to support occupant safety decision-making.     

一种克服脉位脉宽信号码间干扰的均衡算法

使用脉位脉宽调制的室内红外无线通信系统,信号光经过红外信道会产生严重的码间干扰,因此需要在接收端使用均衡器进行处理。常用的迫零反馈均衡算法性能不够理想,针对脉位脉宽调制信号提出了一种MMSE分组判决反馈均衡算法。以最小均方误差原理为基础,同时简化了均衡器中判决器的结构,并使用信号抽取技术设计反馈系数,能够一次反馈多个符号以提高补偿效果。仿真实验表明,与经典的迫零均衡算法相比,算法在误比特率为时抗噪声性能提高了近3dB,并且能够适应更加复杂的信道条件,具有广阔的应用前景。     

The Indoor Environment in Dwellings: A Study of Air-exchange,Humidity and Pollutants in 115 Danish Residences

A total of 115 Danish dwellings were investigated during the winter season in order to evaluate the indoor environment. The sample was considered representative of Danish dwellings. Measurements of air-exchange rates in the bedrm showed a very low natural venthtion with a median air-exchange rate of 0.28 air changes per hour (ach) (interqmmle range (IQR): 0.12 –0.56).18% of the dwellings had a natural air-exchange below a detectable limit of 0.10 ach and 72% had air-exchanges rates below the requirements in Danish Building Codes of 0.50 ach. The investigations showed a statistically signifiant inverse correlation between air-exchange rates and absolute indoor humidity. Concentrations of formaldehyde and volatile organic compounds were measured in 36 dwellings. The median formaldehyde concentration was 0.037 mg/m³ which is well below the recommended indoor TLV The concentration of VOC in some cases reached a level that may be of importance for persons with sensitive airways. It is concluded that natural ventilation in a great number of Danish dwellings is too low fiom a health point of view and that the requirements in Danish Building codes are insufficient to ensure acceptable air-exchange rates.     

Indoor Exposures To Acidic Aerosols At Child And Elderly Care Facilities

A six-week study of indoor and outdoor air pollutants was conducted in central New Jersey during the summer months of 1989. Three institutional settings for elderly and child care were investigated for the potential of acidic aerosol exposures. The indoor penetration by fine aerosols was < 70% at all three institutions. For locations with closed ventilation, it was 15-25% lower than for the open-window setting. Relative to outdoor levels, indoor acidic sulfate aerosols were 30-57% neutralized. Indoor levels of ammonia were = 10 × higher than corresponding outdoor values, which were consistent with calculated emission rates from human occupants. From estimates of total daily exposure, 75% of the daily dose of aerosol acidity for the elderly was due to indoor exposures. Doses received by the elderly and children ranged from 290 to 1100 nmoles of acid (15 to 55 ug as H₂SO₄) in a 24—h period with “worst-case” dose received by children as high as 3400 nmoles of acid in the daytime. These doses were comparable to the levels observed in clinical and epdemiological studies where health effects result. The daily dose of acid delivered to children was calculated to be 2 to 4 × higher than the dose to the elderly population. The calculations for children indicate that more than 90% of their dose on a summer day may come from outdoor exposures. These data suggest that indoor settings are protective, but children may still be at risk from summertime acidic aerosol exposure, depending on their activities outdoors.     

Concentrations of Volatile Organic Compounds in Indoor Air – A Review

A review is presented of investigations of volatile organic compound (VOC) concentrations in indoor air of buildings of different classifications (dwellings, offices, schools, hospitals) and categories (established, new and complaint buildings). Measured concentrations obtained from the published literature and from research in progress overseas were pooled so that VOC concentration profiles could be derived for each building classification/category. Mean concentrations of individual compounds in established buildings were found to be generally below 50 μg/m³, with most below 5 μg/m³. Concentrations in new buildings were much greater, often by an order of magnitude or more, and appeared to arise from construction materials and building contents. The nature of these sources and approaches to reduce indoor air concentrations by limiting source VOC emissions is discussed. Total VOC (TVOC) concentrations were substantially higher than concentrations of any individual VOCs in all situations, reflecting the large number of compounds present, but interpretation of such measurements was limited by the lack of a common definition for TVOC relevant to occupant exposure.     

合路技术在GSM与WLAN系统中的应用

本文首先介绍了GSM室内分布系统与WLAN系统，具体地分析了合路技术的原理以及引入合路后的系统性能。合路技术的引入不但能改善系统的性能，而且还可以降低成本．在实际的工程中具有广阔的应用前景。     

气相色谱法测定室内空气中“三苯”的方法研究

针对室内空气中“三苯”特点,在居住区大气中“三苯”的测定方法——气相色谱法(GB 1737-89)的基础上,进一步优化该方法的采样时间、采样流量等条件,使优化后的测定方法更加适应室内空气监测需要的准确性、简便性、快速性的特点。     

γ谱仪活性炭法检测室内空气中氡浓度

GB50325—2001《民用建筑工程室内环境污染控制规范》中规定在工程验收时必须对氡浓度进行控制，本文采用低本底多道γ谱仪活性炭法建立室内空气中氡浓度的测试方法，从采集时间、平衡时间和检测时间这几个方面进一步细化规范，并确立此方法的最佳测量条件。     

室内~(222)Rn的水平与分布

本文根据1982年以来发表的资料,综述了不同国家和地区室内氡及其子体水平和分布的调查结果,估计了世界范围室内外氡浓度的平均水平,提出了制定室内氡限制标准的建议。