函数型数据视角下的空气质量政策效应评估——以兰州市机动车单双号限行效应测算为例

以机动车单双号限行政策为切入点,尝试对环境政策微观效应量化作出讨论。通过B-样条逼近数据离散值,形成空气质量日变动曲线作为模型分析的"数据",并以此为基础,构建一种政策效应逐点测算的函数型虚拟变量回归模型。以2013年冬季以来兰州市机动车单双号限行前、中、后三个时期二氧化氮(NO2)小时数据为例,测算机动车单双号限行政策逐点微观效果。研究表明,在样本期内,限行政策在统计意义下显著有效,且效应在一天内表现出与人类作息规律一致的"U"型轨迹。     

我国低空空域改革和通用航空事业发展有关问题的思考

我国通用航空的需求与日俱增,国家和公众对低空空域的需求与可供使用的低空空域资源不足的矛盾日益突出,低空空域改革已势在必行。低空空域改革应在确保国家空防安全的前提下,更好地开发利用空域这一重要的资源。改革一是调整各类空域范围,划设低空空域;二是改进航空服务保障体系;三是加强法规、人才建设,三个方面同时入手推动低空空域逐步开放,为通用航空事业发展扫清障碍。     

浅谈航空承运人航运延误之法律责任

航空延误现象日渐增多 ,而中国现行的《民用航空法》有关航空承运人航运延误的法律责任的规定明显滞后。为此 ,本文在解剖国际公约有关承运人航运延误造成旅客损失的法律责任的归责原则的基础上 ,对我国法律有关承运人航空延误的法律责任归责原则进行了对比分析 ,并提出相关建议     

板带式速冻机空载状况下速度场的数值模拟

通过对速冻机作适当的几何简化,建立了相应的数学物理模型.使用PHOENICS软件对速冻机内的流场进行了数值模拟,分析了板带运动、空气进口速度、流动通道高度及空气入射角等对内部流场的影响.研究结果表明,空气进口速度和通道高度的选取应综合考虑空气流速大小、流速均匀性和流动阻力损失等3方面因素;最佳空气入射角应为0°.     

Economic Costs of Misinforming About Risk: The EDB Scare and the Media

This study reports results of an analysis of consumer responses to news reports of grain-product contamination by the pesticide ethylene dibromide (EDB). The results demonstrate that it is possible to quantify market disruption related to the dissemination of risk information. Implications include the need for increased awareness among risk managers that public perceptions, regardless of their objective accuracy, can induce real economic costs. Such costs should be considered in designing regulatory and information policies.     

玻璃管空气预热器的优化设计

本文研究玻璃管空气预热器的优化问题,提出了管式空气预热器优化设计的通用计算机软件,并进行了实例计算。同时还对卧式空气预热器的经济流速和最佳风烟速比进行了讨论。     

民航管制员素质的模糊综合评估研究

针对民航管制员的工作性质和素质要求,从生理特征、管制技能或培训、心理特征三个方面,提出了管制员素质评价指标体系。基于模糊集合论,采用综合评判法建立了管制员素质综合评估模型,并给出了应用实例,旨在尽量避免人为主观评价因素的干扰,相对准确地反映管制员的综合素质水平,促进空中交通管理机构对管制员的选拔、培训和量化测评,为空中交通安全预警和预控管理提供对策依据。     

Estimated Soil Ingestion Rates for Use in Risk Assessment

Assessing the risks to human health posed by contaminants present in soil requires an estimate of likely soil ingestion rates. In the past, direct measurements of soil ingestion were not available and risk assessors were forced to estimate soil ingestion rates based on observations of mouthing behavior and measurements of soil on hands. Recently, empirical data on soil ingestion rates have become available from two sources (Binder et al., 1986 and van Wijnen et al., 1986). Although preliminary, these data can be used to derive better estimates of soil ingestion rates for use in risk assessments. Estimates of average soil ingestion rates derived in this paper range from 25 to 100 mg/day, depending on the age of the individual at risk. Maximum soil ingestion rates that are unlikely to underestimate exposure range from 100 to 500 mg. A value of 5,000 mg/day is considered a reasonable estimate of a maximum single-day exposure for a child with habitual pica.     

乙醇—水体系的表面张力和最大气泡法的实验研究

本文以最大气泡法测定了不同温度和浓度下乙酸－水体系的表面张力，并求出相应的吸附量，建立了一套适用范围广、相关系数达99．5％以上的经验公式。对最大气泡法测定表面张力也总结出一些有价值的规律。     

Estimation of Vulnerable Zones Due to Accidental Release of Toxic Materials Resulting in Dense Gas Clouds

Heavy gas dispersion models have been developed at IIT (hereinafter referred as IIT heavy gas models I and II) with a view to estimate vulnerable zones due to accidental (both instantaneous and continuous, respectively) release of dense toxic material in the atmosphere. The results obtained from IIT heavy gas models have been compared with those obtained from the DEGADIS model [Dense Gas Dispersion Model, developed by Havens and Spicer (1985) for the U.S. Coast Guard] as well as with the observed data collected during the Burro Series, Maplin Sands, and Thorney Island field trials. Both of these models include relevant features of dense gas dispersion, viz., gravity slumping, air entrainment, cloud heating, and transition to the passive phase, etc. The DEGADIS model has been considered for comparing the performance of IIT heavy gas models in this study because it incorporates most of the physical processes of dense gas dispersion in an elaborate manner, and has also been satisfactorily tested against field observations. The predictions from IIT heavy gas models indicate a fairly similar trend to the observed values from Thorney Island, Burro Series, and Maplin experiments with a tendency toward overprediction. There is a good agreement between the prediction of IIT Heavy Gas models I and II with those from DEGADIS, except for the simulations of IIT heavy gas model-I pertaining to very large release quantities under highly stable atmospheric conditions. In summary, the performance of IIT heavy gas models have been found to be reasonably good both with respect to the limited field data available and various simulations (selected on the basis of relevant storages in the industries and prevalent meteorological conditions performed with DEGADIS). However, there is a scope of improvement in the IIT heavy gas models (viz., better formulation for entrainment, modification of coefficients, transition criteria, etc.). Further, isotons (nomograms) have been prepared by using IIT heavy gas models for chlorine, which provide safe distance for various storage amounts for 24 meteorological scenarios prevalent in the entire year. These nomograms are prepared such that a nonspecialist can use them easily for control and management in case of an emergency requiring the evacuation of people in the affected region. These results can also be useful for siting and limiting the storage quantities.