广州地区光化辐射通量与辐照度的特征

应用NCAR TUV辐射模式与地表实际观测分析了理论上广州地区地表可获得的最强光化辐射通量、辐照度及其波谱变化特征与月、日变化特征,计算与观测的差异用于评估气溶胶对紫外辐射通量的作用.结果表明,光化辐射通量与辐照度均具有正弦曲线的日变化特征,但光化辐射通量的正弦波形较辐照度的更为宽广,其辐射强度随太阳天顶角的增加下降幅度也更为缓慢;光化辐射中的总能量可见光谱区约占86%,紫外谱区仅占约14%;理论计算与实际观测表明,不同监测波段范围的紫外辐射表,虽然其标识均为监测UVA或UVB的辐射,但差异明显;广州地区的气溶胶污染显著影响紫外辐射通量.由于紫外辐射通量是影响对流层臭氧生产力的关键因子,有必要更加深入地认识广州地区气溶胶与紫外辐射通量的相互作用.     

Comparison of sensitivity analysis techniques: A case study with the rice model WARM

The considerable complexity often included in biophysical models leads to the need of specifying a large number of parameters and inputs, which are available with various levels of uncertainty. Also, models may behave counter-intuitively, particularly when there are nonlinearities in multiple input-output relationships. Quantitative knowledge of the sensitivity of models to changes in their parameters is hence a prerequisite for operational use of models. This can be achieved using sensitivity analysis (SA) via methods which differ for specific characteristics, including computational resources required to perform the analysis. Running SA on biophysical models across several contexts requires flexible and computationally efficient SA approaches, which must be able to account also for possible interactions among parameters. A number of SA experiments were performed on a crop model for the simulation of rice growth (Water Accounting Rice Model, WARM) in Northern Italy. SAs were carried out using the Morris method, three regression-based methods (Latin hypercube sampling, random and Quasi-Random, LpTau), and two methods based on variance decomposition: Extended Fourier Amplitude Sensitivity Test (E-FAST) and Sobol’, with the latter adopted as benchmark. Aboveground biomass at physiological maturity was selected as reference output to facilitate the comparison of alternative SA methods. Rankings of crop parameters (from the most to the least relevant) were generated according to sensitivity experiments using different SA methods and alternate parameterizations for each method, and calculating the top-down coefficient of concordance (TDCC) as measure of agreement between rankings. With few exceptions, significant TDCC values were obtained both for different parameterizations within each method and for the comparison of each method to the Sobol’ one. The substantial stability observed in the rankings seem to indicate that, for a crop model of average complexity such as WARM, resource intensive SA methods could not be needed to identify most relevant parameters. In fact, the simplest among the SA methods used (i.e., Morris method) produced results comparable to those obtained by methods more computationally expensive.     

Comparative Assessment of Power Absorption in Heads of Adults and Children Exposed to the Radiation of Cellular Phones at 1800 MHz

Summary The aim of this work is to examine the differences in power absorption in the brain of adults and children exposed to the radiation of mobile phone terminals at 1710 MHz. To this end, simulations using the Finite-Difference Time-Domain (FDTD) method have been carried out to study the interaction between heterogeneous anatomically correct models of the human head and a linear or helical monopole mounted on the top of a metal box representing a realistic mobile communication terminal. The study includes computations of specific absorption rates (SARs) inside the human head and the total power absorbed by the head. Emphasis is placed on the comparative assessment of power absorption characteristics in heads of adults and children as well as on the effect of various parameters such as the age-related changes in dielectric properties and the usage distance between the user's head and the mobile terminal.     

226Ra in Tap and Mineral Water and Related Health Risk in the Republic of Croatia

The presence of 226Ra in drinking water may sometimes make important contribution to natural background radiation exposures. The paper describes the study of 226Ra content in drinking water of Croatia: tap water from the public supply system of several major towns and bottled mineral water from two selected mineral water springs. 226Ra was determined by alpha-spectrometric measurement after radiochemical separation. The radiation doses originating from drinking tap water and bottled mineral water were estimated. The annual dose from consumption of bottled mineral water was compared to that received from ingestion of public system tap water. The study showed that 226Ra content for investigated categories of waters is below the levels at which any unacceptable dose due to ingestion would arise.     

BLEVE火球热辐射及其影响评价模型介绍

高压液化易燃、易爆化学品储罐易发生BLEVE,引起热辐射,会造成周围人员伤亡和设备损坏.介绍了BLEVE火球热辐射及其影响模型,通过该模型可以计算BLEVE火球的尺寸、持续时间、升空高度、热辐射通量及预测暴露在BLEVE火球热辐射通量下人的致死概率.     

火球热辐射后果计算动态模型的应用

为了精确地评估火球的热辐射后果,需要深入研究火球热负荷对影响区域暴露人员所造成的伤害.详细介绍了具有时间属性的火球热辐射动态模型,以实例描绘了火球直径、高度以及目标接受到的热通量等火球参数的动态变化规律.结果表明:具有时间属性的火球热辐射动态模型计算出的热辐射值小于静态模型计算的值,动态模型有可能更准确地描述火球参数的实际动态变化,进而合理地确定火球热辐射的人员伤亡区域,并为过热可燃液体容器的安全设计及风险分析提供一种新的后果评估技术及方法.     

手机基站电磁辐射问题释疑

本文就社会普遍关心的手机基站电磁辐射对人体健康的影响问题,从基站电磁辐射属性,强度,对人体健康的影响等,作了较为详细的论述。     

环境辐射有关问题的讨论

本文论述了与环境辐射有关的问题。根据其剂量当量和危险水平,讨论了公众剂量限值的实践性     

UV-B辐射增强与1,2,4-三氯苯污染复合胁迫对青菜生长的影响

采用盆栽实验,分析了单一UV-B辐射增强或1,2,4-三氯苯(TCB)污染土壤与两种胁迫复合作用对青菜生长发育、气孔阻力及叶片结构的影响.结果表明,单一1,2,4-TCB污染对青菜生长发育的抑制作用大于两种胁迫复合作用.UV-B辐射增强和1,2,4-TCB污染均显著增加青菜叶片正面和反面气孔阻力.UV-B辐射增强使青菜叶片产生白化现象.1,2,4-TCB污染使叶片颜色变淡,并使青菜叶片表面出现黑斑症状,且UV-B辐射增强使黑斑症状加剧.总之,单一增强UV-B辐射或1,2,4-TCB污染及其复合作用对青菜各生长发育指标的影响结果不同.     

Radiation induced decomposition of a refractory cefathiamidine intermediate

Diisopropylthiourea（DPT）, an intermediate of a widely used cephalosporin, has been found to be one of the most refractory components in cephalosporin synthesis wastewater.This compound cannot be completely removed by conventional biological processes due to its antimicrobial property. Ionizing radiation has been applied in the decomposition of refractory pollutants in recent years and has proved effective. Therefore, the decomposition of DPT by γ-irradiation was studied. The compound was irradiated at the dose of 150–2000 Gy before a change of concentration and UV absorption of the solutions was detected.Furthermore, the decomposition kinetics and radiation yield（G-value） of DPT was investigated. The results of radiation experiments on DPT-containing aqueous showed that the DPT can be effectively degraded by γ-radiation. DPT concentration decreased with increasing absorbed doses. G-values of radiolytic decomposition for DPT（20 mg/L） were 1.04 and 0.47 for absorbed doses of 150 and 2000 Gy, respectively. The initial concentration and p H of the solutions affected the degradation. As the concentration of substrate increased,the decomposition was reduced. The decrease of removal rate and radiation efficacy under alkaline condition suggested that lower p H values benefit the γ-induced degradation. UV absorption from 190 to 250 nm decreased after radiation while that from 250 to 300 nm increased, indicating the formation of by-products.