The Danish Twin Apartment Study – Part II: Mathematical modeling of the relative strength of sources of indoor air pollution

Abstract This study deals with the modeling of air pollution in apartments from laboratory measurements of source strengths, using formaldehyde and Total Volatile Organic Compounds (TVOCs) as model pollutants. The sources in two test apartments were grouped into two: building-related sources and occupant-related sources. The measured source strengths and ventilation rates were used for the prediction of concentrations expected in the apartments. These predictions were compared to measurements in the apartment over 12 months. The conclusions were that the model predictions based on emission rates measured in the laboratory can be used to predict the long-term concentration of the two model pollutants in the apartments. Considering the measured differences in ventilation between the apartments, an occupant emission rate of between 0.2 and 0.3 mg/h/kg body weight could be estimated. Based on previous suggested limits of acceptable exposures of humans to VOCs, an acceptable average emission rate of VOCs from building materials in general was estimated to be about 30 (μ/m²/h. The modeling showed that during the first 200 days, building materials dominated the emissions. After this, sources relating to the occupants dominated. On average about half of the VOC pollution originated from the building materials.     

A simplified cascade current‐source inverter interconnected to a single‐phase three‐wire distribution system and its application to electric energy storage systems with batteries

A novel current source inverter system interconnected to the single‐phase grid is proposed. It has the same construction as the conventional three‐phase current source inverter that is interconnected to the single‐phase three‐wire distribution system. Though the proposed circuit has no output transformer, it can be equivalently performed as the single‐phase double cascade inverter by diverting the pole transformer in the utility system. By controlling the appropriate scheme, the output currents can be obtained as the five‐level waveforms and their distortions can be decreased sufficiently. It is applied to the interactive electric energy storage system with batteries and the basic discharging characteristics are discussed experimentally. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 50–61, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10380     

担载型含稀土三组份体系在二氧化碳甲烷化反应中的催化性能

用浸渍法制备了一系列氧化锆担载的含稀土Ⅷ族金属催化剂，对其在二氧化碳甲烷化过程中的催化活性作了研究，并用漫反射紫外可见光谱，ＦＴＩＲ等手段对催化剂作了表征。结果表明，含稀土新型催化剂具有催化活性高，目标产物选择性好等优点；稀土主要以氧化物形式存在于催化剂表面，参与对氢及表面含碳物种的吸附及活化；含稀土三组份催化剂的活性与所添加稀土三价离子的４ｆ电子数有关。     

一个高电阻值测量电路

介绍一种新的高阻测试方法，可满足对高达１×１０＾１６Ω的测试要求。测试结果显示，对于１×１０＾１３Ω重复误差优于±２％。高阻测试电路通过接口与６８０９微机配套使用，操作简便，读数直观，便于长时间重复测量。     

对梁,底组合步进式加热炉半热滑轨的改进实践

介绍了间断式半热滑轨的研制和应用过程，以及经过节能技术改造，用新型半热滑轨代替老式滑轨的使用。实践表明，不但解决了以往的水梁漏水的问题，而且使线Ｃ级品率提高了３．３９％，每年可增产３５００ｔ线材，吨钢热涌单耗降低０．１４ＧＪ，年创经济效益２３９万元。     

未知钍—铀比的误差分析

研究了在任意Th、U含量和Th-U比覆盖整个范围(即0≤Th/U≤∝)时总α计数率对年剂量的转换因子及其误差。结果表明,当不测定Th-U比而只测量总α计数率时,最终引起的年龄误差对0≤Th/U≤∝来说为±5.1％-±8.3％,对1.1≤Th/U≤9.5来说只有±2.5％％-±4.1％。     

Effects of computers on Japanese schools

In this paper I consider how the computer can or should be accepted in Japanese schools. The concept of teaching in Japan stresses learning from a long-term perspective. Whereas in the instructional technology, on which the CAI or the Tutoring System depends, step-by-step attainments in relatively short time are emphasized. The former is reluctant in using the computer, but both share the Platonic perspective which are goal-oriented. However, The Socratic teacher, who intends to activate students' innate disposition to be better, would find another way of teaching and use of the computer.     

铸造用CO2硬化冷芯盒材料及工艺的发展

铸造用CO2硬化粘结剂系统具有气硬冷芯盒的优点,同时又具有环保方面的优势。主要介绍了水玻璃-CO2法、聚丙烯酸钠-CO2法、酚醛树脂-CO2法三种工艺。这些工艺方法近年来国内外研究较多,并且取得了很大进展。