室内准稳态压力火灾烟气沉降模型的改进和实验验证

对室内火灾及烟气的研究给消防工程领域带来了诸多益处,如疏散时间预测、基于性能化的设计分析等。Zukoski (Fireand Materials,1978,2(2): 54-62)在室内火灾烟气运动的开创性研究给出了基于质量和能量平衡的理论方法,为后续研究奠定了基础。然而实验发现,由于忽略热损失偏差,模型对近壁面火源的火灾烟气沉降时间的预测缺乏准确度。本文通过空间重构的方法消除房间长宽比因素造成的热损失偏差,引入两个参数进行表征,以完善该模型。完善后的模型预测烟气沉降时间与实验吻合度非常好,验证了该方法的有效性。在计算分析基础上,将两个参数对模型的影响作了评估,发现其一对模型预测结果的影响远大于另一参数。火源大小确定后,烟气充满房间的时间范围可确定,火源功率越大,时间范围越小。     

Functional decomposition—A contribution to overcome the parameter space explosion during validation of highly automated driving

Abstract

Objective: Particular testing by functional decomposition of the automated driving function can potentially contribute to reducing the effort of validating highly automated driving functions. In this study, the required size of test suites for scenario-based testing and the potential to reduce it by functional decomposition are quantified for the first time.

Methods: The required size of test suites for scenario-based approval of a so-called Autobahn-Chauffeur (SAE Level 3) is analyzed for an exemplary set of scenarios. Based on studies of data from failure analyses in other domains, the possible range for the required test coverage is narrowed down and suitable discretization steps, as well as ranges for the influence parameters, are assumed. Based on those assumptions, the size of the test suites for testing the complete system is quantified. The effects that lead to a reduction in the parameter space for particular testing of the decomposed driving function are analyzed and the potential to reduce the validation effort is estimated by comparing the resulting test suite sizes for both methods.

Results: The combination of all effects leads to a reduction in the test suites’ size by a factor between 20 and 130, depending on the required test coverage. This means that the size of the required test suite can be reduced by 95–99% by particular testing compared to scenario-based testing of the complete system.

Conclusions: The reduction potential is a valuable contribution to overcome the parameter space explosion during the validation of highly automated driving. However, this study is based on assumptions and only a small set of exemplary scenarios. Thus, the findings have to be validated in further studies.     

Application of air pollution dispersion modeling for source-contribution assessment and model performance evaluation at integrated industrial estate-Pantnagar

Source-contribution assessment of ambient NO₂ concentration was performed at Pantnagar, India through simulation of two urban mathematical dispersive models namely Gaussian Finite Line Source Model (GFLSM) and Industrial Source Complex Model (ISCST-3) and model performances were evaluated. Principal approaches were development of comprehensive emission inventory, monitoring of traffic density and regional air quality and conclusively simulation of urban dispersive models. Initially, 18 industries were found responsible for emission of 39.11 kg/h of NO₂ through 43 elevated stacks. Further, vehicular emission potential in terms of NO₂ was computed as 7.1 kg/h. Air quality monitoring delineates an annual average NO₂ concentration of 32.6 μg/m³. Finally, GFLSM and ISCST-3 were simulated in conjunction with developed emission inventories and existing meteorological conditions. Models simulation indicated that contribution of NO₂ from industrial and vehicular source was in a range of 45-70% and 9-39%, respectively. Further, statistical analysis revealed satisfactory model performance with an aggregate accuracy of 61.9%.     

磁絮凝污水处理装置的设计及实验验证

为了优化设计装置内部的结构,分别使用Fe3O4磁块和NdFeB磁块制作了2台简易装置进行实验。在实验中由于装置的结构和磁系会影响絮凝的过程,因此将磁盘厚度减到了33 mm,提高了单位时间内流体通过磁盘的流量。在实用可行方面,设计了高效率的絮体助卸装置;2块外磁盘只受单边磁力作用因而对其结构做了加强设计;并且设计了独特的磁盘位置调整机构,以便在实验中调整磁盘间距;装置使用变频调速控制能够及时调整磁盘的转速,从而保证分离的效果。在实际实验中验证了该装置的处理效果,经过处理的水体能达到国家三类水质标准。     

Evaluation of the MIKE SHE Model for Application in the Loess Plateau,China1

Abstract: Quantifying the hydrologic responses to land use/land cover change and climate variability is essential for integrated sustainable watershed management in water limited regions such as the Loess Plateau in Northwestern China where an adaptive watershed management approach is being implemented. Traditional empirical modeling approach to quantifying the accumulated hydrologic effects of watershed management is limited due to its complex nature of soil and water conservation practices (e.g., biological, structural, and agricultural measures) in the region. Therefore, the objective of this study was to evaluate the ability of the distributed hydrologic model, MIKE SHE to simulate basin runoff. Streamflow data measured from an overland flow‐dominant watershed (12 km²) in northwestern China were used for model evaluation. Model calibration and validation suggested that the model could capture the dominant runoff process of the small watershed. We found that the physically based model required calibration at appropriate scales and estimated model parameters were influenced by both temporal and spatial scales of input data. We concluded that the model was useful for understanding the rainfall‐runoff mechanisms. However, more measured data with higher temporal resolution are needed to further test the model for regional applications.     

Dispersion in Urban Environments; Comparison of Field Measurements with Wind Tunnel Results

A wind tunnel study was performed to determine the dispersion characteristics of vehicle exhaust gases within the urban canopy layer. The results were compared with those from a field monitoring station located in a street canyon with heavy traffic load. The agreement found was fair. In the second part of the paper it is shown how wind tunnel data can be utilized to supplement and thereby enhance the value of field data for model validation purposes. Uncertainty ranges were quantified which are inherent to mean concentration values measured in urban streets.     

生物滤池工艺的数值模拟与运行优化

以筼筜污水处理厂生物滤池工艺(DNBF+BAF)为研究对象,应用Bio Win软件,构建该工艺的Bio Win模型,基于2013年9月和10月的实际运行数据,结合两种灵敏度分析方法,对Bio Win模型进行校正.结果表明,校正模型可对DNBF+BAF工艺进行有效模拟,且对该工艺的Bio Win模拟结果影响最为显著的3类参数为:与生物膜有关的参数、与异养菌(OHOs)有关的参数和曝气参数.然后应用校正模型模拟该工艺在不同工况条件下的运行结果,对其进行工艺优化.结果表明:1一级B排放标准的最佳运行条件为:回流比=50%,取消甲醇投加,此时进水C/N=4.43;2一级A排放标准的最佳运行条件为:回流比=50%,投加甲醇后的进水COD=155 mg·L-1,此时进水C/N=5.10.     

卫星遥感监测海南地区对流层CO2浓度时空变化特征

为了探索海南地区对流层CO₂浓度[以φ(CO₂)计]时空变化特征,采用2002年9月—2012年2月AIRS反演的对流层中层CO₂产品,利用北半球全球本底站瓦里关站和飞机观测φ(CO₂)对该产品进行验证,结合统计分析方法对海南地区φ(CO₂)的月、季、年平均值的时空变化特征进行了研究.结果表明:AIRS反演φ(CO₂)与地基和不同纬度带海洋上空飞机观测数据对比均具有很好的一致性,并且与飞机观测验证偏差更小,二者相关系数均在0.9以上,总体月均值偏差小于2×10-6;全国φ(CO₂)呈现北高南低的分布规律,并且存在较为明显的分界线,形成4个高值中心(塔克拉玛干沙漠、塔里木盆地、内蒙古西部和东北平原)和2个低值中心(青藏高原西南部和云南地区),海南地区平均φ(CO₂)为382.67×10-6,略高于云南低值中心的381.45×10-6;全国φ(CO₂)呈现明显逐年增加趋势,其年均增长速率为2.16×10-6,而海南地区亦呈现显著增加趋势,年均增长速率为2.11×10-6,低于全国水平;φ(CO₂)呈季节性波动特性,全国φ(CO₂)最高值出现在春季,而海南地区为夏季,最低值均出现在秋季;海南地区西部海域、陆地和东部海域上空φ(CO₂)年增长速率分别为2.09×10-6、2.14×10-6和2.11×10-6,表明海南陆地上空增速略大于海洋地区,西部和东部海域上空增长速率基本保持一致.