Measurement of indoor air quality for ventilation with the existence of occupants in schools

This paper evaluates the performance of ventilation for the removal of indoor pollutants as a function of ventilation rate and the number of occupants in a test room and school classroom. An experimental apparatus consists of a test room, a tracer gas supply system, a gas detector, and a fan for ventilation air supply with a controller. The ventilation performance is evaluated in a step-down method based on ASTM Standard E741-83 using CO₂ gas as a tracer gas in the test room of 35 m³. For the ventilation air flow rate of 1.0 ACH, a recommended ventilation flow rate of Korea school standard for acceptable indoor air quality in the case of one person, CO₂ gas concentration decreases up to 55% within 50 minutes without occupancy and increases up to 75% in the case of one occupant. Also indoor air quality at the school classroom is investigated experimentally.     

International comparison of key volatile organic components in indoor air

An international comparison was coordinated by the National Physical Laboratory to assess the analytical capabilities of laboratories for measuring ten selected volatile organic compounds. These were chosen to represent a wide range of non-methane hydrocarbons, terpenes and oxygenated hydrocarbons, which pose a significant risk to public health from their presence in indoor environments from emissions by building and consumer materials. The components were loaded onto sorbent tubes and distributed to twenty-four participating laboratories for analysis. It was found that laboratories predominantly reported analytical results that were greater than the reference value, however the majority of results were closer to the reference value when compared to the previous comparison carried out in 2010.     

零件质量在机云检测无线终端设计

针对数字化闭环制造过程中的零件质量检测环节,设计了一种应用于零件质量在机检测系统的无线检测终端。首先介绍了零件质量在机云检测系统架构,接着给出了无线终端的功能需求,然后介绍了终端的硬件模块选型、系统设计,软件模块和流程设计以及WiFi网络上位机配置软件。终端硬件部分以嵌入式STM32芯片为核心,集成了RS485现场通讯、WiFi和GRPS无线网络通讯等模块,软件部分封装了质量数据采集、数据格式处理、无线网络通讯、现场设备控制、GPIO接口等模块。研究结果表明,系统作为连接现场设备和云端服务器的关键部件,可以用于生产过程的零件质量数据采集和远程设备监控,实现云计算模式下的零件质量控制。     

Feasibility of using thermal response methods for nonintrusive compressed air flow measurement

Robust, low-cost nonintrusive flow meters are of interest in many industries. In particular, a reliable nonintrusive flow measurement for the diagnosis of air leaks in compressed air systems is desirable. Measurement of the air flow due to leaks in the system ensures an accurate estimation of potential cost and energy savings. This study evaluates a novel method of using thermal responses to nonintrusively measure leakage rates in compressed air lines. The method uses heat and the resulting thermal response to calculate the flow rate inside the compressed air line. Compared to the current methods for flow measurement, this method can simplify flow measurement while decreasing the sensitivity to errors when measuring flow rates. In this study, the methodology of the proposed method is explained along with the potential advantages to the design. Two approaches are evaluated: a dynamic step response and sinusoidal frequency response. Simulated tests evaluate the feasibility of the proposed methods, followed by experiments that validate the simulation results. A clear correlation between the thermal step response and the flow rate indicate viability of the proposed method in simulation. Experimental results yielded similar results, confirming the validity of the proposed method. The results of a field test in an industrial environment demonstrate the capability of the approach to other flow rate measurement techniques.     

用预抽气真空腔法测量及补偿空气折射率的研究

空气折射率的补偿效果在高精度激光干涉测量中起着“瓶颈”作用。分析了空气折射率的补偿原理,回顾了几种空气折射率的测量方法及特点。在此基础上,深入研究了用预抽气真空腔测量与补偿空气折射率的测量原理、方法和装置。该方法保持了干涉法测量空气折射率能充分反映所有导致折射率变化的环境因素的特点,避免了测量过程中由于抽气过程给测量带来的干扰。通过空气折射率测量及补偿实验,证实了该方法的可行性,测量结果经补偿后可使精度提高一个数量级。