Review of scientific technology-based solutions for vehicular pollution control

Clean Technologies and Environmental Policy - Numerous management strategies are implemented for the improvement in urban air quality worldwide, including control at tailpipe emissions. Control at...     

Optimization of a liquid desiccant based dedicated outdoor air-chilled ceiling system serving multi-zone spaces

A liquid desiccant based dedicated outdoor air-chilled ceiling (DOAS-CC) system is proposed to serve a multi-zone space. The outdoor airflow rate and the supply air humidity ratio are two crucial variables in such a system, which significantly influence indoor thermal comfort, indoor air quality and energy consumption. Two strategies are presented to optimize these two variables in the study. They are the demand-controlled ventilation (DCV) strategy and the supply air humidity ratio set-point reset strategy. To evaluate the performances of these two strategies, a basic control strategy, i.e., the strategy adopting constant ventilation flow rate and constant supply air humidity ratio, is selected as the benchmark. Performances of the two strategies in terms of indoor air temperature, relative humidity and CO₂ concentration as well as energy consumption are analyzed using simulation tests. The results show that the supply air humidity ratio set-point reset strategy is effective for the indoor air humidity control. It can save about 19.4% of total energy consumption during the whole year. The DCV-based ventilation strategy can further reduce about 10.0% of energy consumption.     

响应面法优化VC二步混合菌新菌系发酵培养基

为提高VC二步发酵法中糖酸转化过程的产酸量,本实验室从新鲜牛奶中筛选出一株高效促产酸菌生长和产酸的伴生菌——枯草芽孢杆菌A9。在单因素试验基础上,采用响应面法对发酵培养基成分进行优化。结果表明,L-山梨糖、玉米浆、尿素的影响比较显著,最佳培养基条件为L-山梨糖90g/L、尿素12.2g/L、玉米浆14.2g/L、CaCO34.1g/L、MgSO40.2g/L,可获得2-酮基-L-古龙酸产量为69.74g/L,与理论值70.33g/L的相对误差为-0.59g/L。曲面回归方程与实验结果拟合性较好,此模型合理可靠,可用于实际预测。优化后的培养基比原培养基平均提高2-KGA产量17.4%。     

Characteristics of wire-electro discharge machined Ti6Al4V surface

Titanium and titanium alloys (e.g., Ti6Al4V) are increasingly used in aerospace and automotive industries, and also used as medical implant material in wide variety of applications. Wire-electro discharge machining (WEDM) is an important non-traditional machining process, widely used for machining a variety of difficult-to-machine materials including titanium alloys with intricate shapes. The process is essentially a thermal process and the nature of surface produced is studied in this paper. It is observed that more uniform surface characteristics are obtained with coated wire electrode. Among the parameters such as time between two pulses, pulse duration, injection pressure, wire speed and wire tension that have more influence on the surface characteristics, the time between two pulses is the most sensitive parameter.     

Numerical simulation of passive and active solar strategies in buildings with complex topology

In this paper a numerical software, that simulates the building thermal behaviour with complex topology in transient conditions, was developed and used in the study of kindergarten thermal response and the occupants’ thermal comfort and air quality in Mediterranean conditions. In this numerical model a new building three-dimensional grid generation philosophy, closer to the reality, that considers the building and the surrounding buildings used in the long and short-wave calculus, the external and internal shading devices, the energy and mass balance integral equations philosophy generated by the building geometry, the equation system resolution done by the Runge-Kutta-Felberg with error control and the human thermal comfort level evaluated through human thermo-physiology, are developed. In the simulation, with a real occupation cycle, the compartments, the building opaque bodies, the building transparent bodies, and the external shading devices were considered. In passive strategies the kindergarten is equipped with multiple inclined aluminium shading devices placed above the transparent windows level and in front to the transparent door facing south, removable inclined tissue shading devices placed in front to the transparent windows facing east, and horizontal fabrics shading devices placed above the transparent panel levels facing south, south-west and west. In this study, made with natural and forced ventilation, the summer and winter conditions were used. In summer conditions, the forced ventilation active strategies in all spaces with cold air from the external environment during the night, and in occupied spaces with stored cold air from the underground space were used. In winter conditions forced ventilation from an internal greenhouse, to heat the internal occupied cold spaces, was used.     

双洞盾构施工对邻近桩基础的影响研究

隧道开挖不可避免的会影响围岩的变形,从而对周围的既有基础及结构物产生复杂的影响,且多为不利影响。本文针对某市地铁区间盾构的设计及施工方案,运用有限元计算方法,分析了双洞盾构施工情况下,隧道开挖对邻近桩基础的影响规律,得到了桩基位移及内力变化的最不利时刻,进而寻找到在桩基最不利的位移及内力的变化特征,能够为类似的工程设计及施工提供参考。     

城市综合能源网统一前推回代能流计算方法

综合能源系统能流计算复杂且解耦后算法不统一,计及电力系统在综合能源系统中的核心地位,考虑将配电网常采用的前推回代法应用于城市综合能源网能流计算中并提出一种城市综合能源网统一前推回代能流计算方法。通过详细分析风电、光伏等新能源接入对实际配电网的影响以及热网的运行方式,对传统前推回代法进行改进,提高算法对实际电网和热网的适用性;对于天然气网络,采用解环的思想推导并得出线性化补偿气流法,实现对适用于天然气网络的前推回代法的改进。最后,采用算例验证所提算法的正确性并对综合能源系统静动态特性及风电消纳能力进行分析,算例结果表明该算法不仅实现了能流计算方法的统一,还具有编程简单、对初值要求不高等优点。     

机械润滑油第三次更新换代

分析了信息时代机械及相关行业的生产技术和生产设备对高档润滑油的需求;论述了Ⅲ类润滑油的优越性能,提出了解决润滑油光敏性的渠道;分析了国内外Ⅲ类润滑油的发展状况;提出了第三次润滑油更新换代即:“高性能化、低粘化、个性化”的可能和需要。     

Traceability Issue in PM2.5 and PM10 Measurements

Nowadays particle size and mass concentration measurements are the important parameter of the ambient air quality standards of several countries. The regulatory limits of mass concentration of particulate matter (PM) for the size classes of PM_2.5 and PM₁₀, i.e., particle sizes of less than or equal to 2.5 and 10 μm in aerodynamic diameter, respectively in air are defined on yearly and hourly time-weighted-average basis. However, these limits are different in different regulations of the countries. Both of the parameters relate with the human health, climate and other issues, therefore accurate and precise measurement of these parameters are very important. Despite this, so far not much work has progressed in national metrology institutes (NMIs) worldwide on calibration and traceability issue of PM measurements. In this paper in context of PM measurement traceability, we present systematically the (1) air quality regulation in different countries, (2) reference methods for size and mass measurements, (3) variation/error and limitations of PM measurements based on the current results in this study and previously published results, (4) current status of PM size and mass calibration facility, (5) expected uncertainty in PM measurements, (6) add-on uncertainty in other parameters of national ambient air quality standards due to PM measurements, (7) where does traceability of PM issue stand against other parameters of air quality standards and its impact on health and climate, (8) NMIs working on this issue, (9) status at Bureau International des Poids et Mesures (BIPM), France and (10) conclusion. The aim of this paper is to better understand the importance of international system of units (SI) traceability issue in PM measurements, so wherever and whenever it is measured, should be acceptable everywhere, and data should be comparable for improving air quality and thus the quality of life. Funding agencies should be aware of this issue, and accept the results from the principle investigators and team only when their results have the traceability link to SI. NMIs should make program to involve industries in gas and aerosol metrology work to fulfill the requirement of calibration and standards. The regulatory authorities/ministry should work together with NMIs to improve the data quality of ambient measurements. This will greatly help to better make the policies and decisions on the related impacts. These were also the ultimate goals of “one-day pre-AdMet workshop” organized at National Physical Laboratory, New Delhi, India on February 20th, 2013.     

盾构掘进过程中围岩变形规律的研究

无论采用什么样的施工工艺开挖隧道,都不可避免隧道开挖过程中围岩的应力释放。通常,土体颗粒在新的应力平衡条件下发生位移,引起围岩变形,变形较大时更可能诱发隧道失稳坍塌,最终破坏。为此,对隧道在开挖过程中围岩的变形规律的研究一直从未间断。并结合工程实例,建立三维有限元分析模型,通过对比理论计算和实测数据相结合的方法,对盾构法施工隧道掘进过程中围岩的变形进行了深入的研究,总结了盾构施工过程中围岩变形规律,能够为类似工程设计及施工提供参考意义。