A Simple Model to Determine In Situ Mixing Height Growth from Surface Measurements

A generic In Situ Mixing Height Growth (IMG) model, capable of predicting the real-time growth of the mixed layer and its diurnal evolution from routinely observed simple surface meteorological is developed. The algorithm for the determination of temporally growing daytime mixing height includes both convective and mechanical turbulence contributions. It accounts for neutral as well as height varying potential temperature gradients above the mixed layer. For thermally stable and mechanically dominated unstable night time Atmospheric Boundary Layer (ABL) the module uses similarity formulae based on the wind velocity [1]), the Monin—Obukhov length [2], and the Coriolis parameter. In the convective case simple slab model is integrated, based on initial lapse rate and the surface heat flux. The lapse rate is evaluated on the basis of vertical atmospheric stability, surface type and surface temperature. This differentiates the IMG model from other existing mixing height models that need initial measured lapse rate for calculation. IMG model is site specific as it calculates the radiative incoming heat flux depending on the solar declination estimates based on-site latitude and longitude. The IMG model is applied to calculate mixing height for India by using surface data (viz. wind speed, surface temperature, surface type) from 152 surface meteorological stations. Results have been evaluated with radiosonde mixing height data procured from 18 upper air stations. Sensitivity analysis of the model with respect to various parameters is performed. The model is formulated after reviewing presently available radiosonde mixing height data in India and can satisfactorily provide an alternative means of estimating mixing height for air pollution dispersion models.     

应用水色卫星遥感技术估算珠江口海域溶解有机碳浓度

溶解有机碳是水域环境评价的必测环境参数之一。根据水体光学理论，利用在珠江口水域实测的水体成分浓度数据集拟水体光谱，并建立溶解有机碳浓度的遥感反演模式。进而应用新一代海洋水色卫星传感器SeaWiFS资料估算珠江口及其邻近水域溶解有机碳浓度。     

Assessment of Calibration Parameters for an Aerial Gamma Spectrometry System using Monte-Carlo Technique

During a radiation emergency subsequent to a nuclear accident orweapon fallout, quick assessment of the ground contamination andthe resulting exposure is of prime importance in planning and execution of effective counter measures. For an online assessmentof ground contamination, it is essential to calibrate the detector system for several parameters viz. the source energy,source deployment matrix, the flight altitude and position abovethe contaminated surface. This article discusses the methodology to predict all the necessary parameters like photon fluence atvarious altitudes, the photo-peak counts in different energy windows, Air to Ground Correlation Factors (AGCF) and the doserate at any height due to air scattered gamma ray photons. Themethodology includes generation of theoretically simulated gammaspectra at a required detector position for a given source distribution on the ground using Monte-Carlo method provided by general purpose coupled neutron/photon transport code (MCNP CCC-200). Thus generated gamma spectra are analyzed to arrive at the required parameters mentioned above.     

Use of Water Clarity to Monitor the Effects of Climate Change and other Stressors on Oligotrophic Lakes

We present evidence from studies oflakes in Killarney Park, Ontario, Canada that waterclarity is a key variable for monitoring theeffects of climate change, high UV exposure andacidification. In small oligotrophic lakes, thesestressors affect water clarity primarily byaltering the concentration of DOC in lake water. Clear lakes (<2 mg L^-1 DOC) proved to be highlysensitive indicators of stressors, exhibiting largethermal and optical responses to small changes inDOC. Extremely clear (<0.5 mg L^-1 DOC) acidic lakesshowed the effects of climate change and solarbleaching in recent decades. These lakes becamemuch clearer even though they were slowlyrecovering from acidification.     

发光光谱分析在环境监测中的应用

现代科学技术发展的一个显著特点是多学科综合发展，物理光进学与化学分析相结合所产生的现代物理化学分析新技术──发光光谱分析在环境监测领域得到了广泛的应用。本文针对这一新技术的原理和特点作了简要介绍，并对近年来在环境监测中的应用作了较详细的介绍和评述。     

战斗机阻力伞载荷计算研究

目的通过对战斗机阻力伞载荷计算开展研究,为阻力伞安装支持结构的静强度和疲劳强度分析提供支持。方法分别运用工程计算方法、流固耦合数值模拟方法,并对比阻力伞火箭滑车试验实测数据,对阻力伞载荷计算开展研究。同时基于飞参数据,运用统计学方法对影响阻力伞载荷大小和方向的开伞速度、飞机俯仰角、侧风速度与方向等参数进行统计分析,为载荷谱编制提供数据基础。结果确定阻力伞载荷工程计算方法中动载系数k取为1.2,将一次放伞的载荷历程简化为以拉直力和张满力为峰值的两个载荷循环,且拉直力为张满力的50%。以某型飞机766架起落飞参数据为基础,运用皮尔逊Ⅲ型分布、指数分布对开伞速度、飞机俯仰角、侧风速度与方向等参数进行拟合,结合阻力伞载荷计算方法,得出阻力伞载荷大小和方向分布的统计规律。结论明确了阻力伞载荷计算方法及计算相关参数选取,同时提出一种符合战斗机实际使用环境的阻力伞载荷谱编制方法。     

Thermal modeling and analysis of novel twin-chamber community solar cooker as a replacement of biomass-based cooking

A novel design of twin-chamber community solar (TCCS) cooker is presented as a replacement of biomass-based cooking. The novelty of separating a single rectangular cooking chamber into separate twin chambers (of 1-m² aperture area each) improves the cooking performance as opening of one chamber for unloading of food cooked in lesser time (rice) does not disturb the stagnation temperature of the other chamber (pulses and meat) needing more time to cook besides resulting in reduction in side heat loss coefficient due to common wall. Aperture area and cooking volume of TCCS cooker are 9.54 and 35.33 times more as compared to single-chamber domestic solar (SCDS) cooker which makes it a community-scale large-capacity solar cooker. The developed solar radiation capture model and overall heat loss coefficient (U_l) computed for TCCS cooker have been used in a thermal model developed between various interactive components. First (F₁) and second figures of merit (F₂) values are 0.13 and 0.42, respectively, for TCCS cooker at par with ‘A’ grade category SCDS cooker. Techno-economic analysis shows that the net present value of TCCS cooker is Rs. 83,253 with break-even point occurring after cooking 43,461 meals with payback period of only 25, 50, and 72 months if used as a replacement for LPG, cow dung cakes, and wood-based cooking, respectively. Environmental impact analysis shows that the use of the proposed cooker can mitigate 2, 5.9, and 4.1 tonnes of CO₂ emissions every year by not burning LPG, cow dung cakes, and wood respectively.     

丁苯橡胶生产废水的生物降解特性

为研究丁苯橡胶生产废水的好氧生物降解特性,对某石化企业丁苯橡胶生产装置的生产废水进行好氧处理,并采用液液萃取-气相色谱/质谱、三维荧光光谱、紫外吸收光谱等手段对水质指标进行表征. 结果表明:经好氧生物降解后,丁苯橡胶废水中ρ(COD_Cr)和ρ(DOC)分别降至155和76 mg/L,COD_Cr和DOC去除率分别为76.07%和70.08%;废水中二苄胺、苯乙烯和十二烷基二甲基叔胺等9种主要特征有机物19 d内可被完全降解. 丁苯橡胶生产废水在λ_Ex/λ_Em(激发波长/发射波长)为225 nm/340 nm、215 nm/290 nm,275 nm/340 nm处有3个荧光峰,分别由二苄胺、十二烷基二甲基叔胺、苯乙烯、甲苯和苯甲醛等胺类、苯乙烯和芳香族化合物等有机物产生,好氧生物降解能去除废水中的绝大部分荧光物质,荧光峰强度的总去除率达到93.87%;废水中二苄胺、十二烷基二甲基叔胺、4-甲基环己酮、苯甲醛,苯乙烯、甲苯等有机物使丁苯橡胶生产废水分别在波长190~230、230~250、250~400 nm处有紫外吸收,好氧生物降解对UV₂₅₄的去除率达到52%. 研究显示,丁苯橡胶废水经单独好氧生物处理不能达到GB 31572—2015《合成树脂工业污染物排放标准》的要求,需结合其他方式进行联合处理.      

公交车噪声排放实验测量及频谱特性分析

设计了一种测量公交车噪声源排放的实验方案,采用实验方法对公交车的噪声源排放进行了测量。对测量数据进行统计分析,建立了考虑加、减速影响的公交车噪声源排放模型。然后通过计算得到不同行驶状态下公交车噪声的A计权等效频率,并进行了对比分析。最后分析了不同行驶状态下公交车噪声的频率分布的差异,得到了公交车噪声频率分布的若干规律。     

基于EEMs和PARAFAC分析典型碳材料吸附水中DOM特征研究

水中溶解性有机物(DOM)对全球污染物迁移和水处理工艺效能具有重要影响。采用3种典型碳材料,包括碳纳米管(CNTs)、颗粒活性炭(GAC)、粉末活性炭(PAC)分别吸附微污染源水中的DOM。基于荧光发射-激发光谱(EEMs)和平行因子(PARAFAC)分析,解析DOM中的有效荧光组分,评估3种材料对不同组分吸附去除的效果和吸附特征。研究表明:PARAFAC分析方法提取4种荧光组分C1和C2(腐殖酸类)、C3和C4(类蛋白类)。以TOC为基础的吸附等温线模型表明,PAC的KF值大于GAC和CNTs,PAC有丰富的中孔和较大的比表面积,吸附容量比GAC和CNTs更大。C3和C4 2个荧光组分在吸附过程中更容易被吸附,PAC对两者吸附容量最大。研究结果揭示了不同碳吸附材料对水中不同类型有机物的吸附特征,可为吸附工艺应用提供技术参考。