N36特征化燃料辐照考验及性能评价

N36合金是我国自主研发的先进锆合金,将作为华龙一号反应堆燃料元件的包壳材料。为了研究N36合金包壳的堆内性能,验证其用于燃料元件包壳的可行性,以N36合金为包壳设计了N36合金特征化燃料组件,在秦山二期核电厂反应堆内进行了辐照考验,并在每循环末通过池边检查获取堆内性能数据,基于堆内数据对N36合金包壳的性能进行了分析和评价。本文研究提供了N36合金特征化燃料的辐照考验方案、N36合金特征化燃料的设计、堆内性能数据的获取方式以及N36合金与Zr-4合金堆内性能对比结果。      

Sustained hydrogen photoproduction by phosphorus-deprived Chlamydomonas reinhardtii cultures

This study demonstrates that, besides sulfur deprivation, sustained H₂ photoproduction in Chlamydomonas reinhardtii cultures can be generated by incubating algae under phosphorus-deprived (−P) conditions. However, phosphorus deficiency in algal cells could not be obtained by resuspension of algae in −P medium, evidently due to a significant reserve of phosphorus in cells. In this study, phosphorus deficiency was accomplished by inoculating the washed algae into the −P medium at low initial cell densities (below 2 mg Chl l⁻¹). After the initial growth period, where cells utilize intracellular phosphorus, algae established anaerobic environment followed by the period of H₂ photoproduction. The maximum H₂ output (∼70 ml l⁻¹) was obtained in cultures with the initial Chl content ∼1 mg l⁻¹. Cultures with Chl above 2 mg l⁻¹ did not produce H₂ gas. The physiological response of algal cultures to phosphorus deprivation demonstrated significant similarities with the response of algae to sulfur depletion.     

深圳市部分市售禽类制品二噁英污染水平研究

目的了解深圳市部分市售禽类制品(鸡肉、鸭肉、鸡蛋、鸭蛋)中17种二噁英污染情况。方法于2004年12月至2008年10月期间,随机采集深圳市市售的26份禽类样品,参照美国国家环保局EPA1613方法,采用索式抽提装置和FMS自动纯化系统分别对样品进行提取和净化,采用同位素稀释技术,用高分辨气相色谱/高分辨双聚焦磁式质谱联用(HRGC/HRMS)的超痕量有机分析技术平台,对样品中的二噁英进行定量分析检测。结果禽肉中PCDD/Fs含量(pgWHO-TEQ/g脂肪)范围是0.03～1.61,平均含量为0.50;禽蛋中PCDD/Fs含量范围是0.22～5.66,平均含量为1.43。其中有1份鸡肉和1份鸡蛋中二噁英含量超过欧盟执行标准,含量分别为1.61和5.66。结论本次调查的禽类制品中二噁英平均含量低于欧洲标准,但个别样品存在二噁英污染现象。     

钼精矿焙烧气体参数对环保和资源的影响

绝大部分钼精矿须经焙烧脱硫，该过程的严重污染和浪费缘于不合理的气体参数和稀释放应；调控此参数以抑制释释效应、制定新政策、结合硫酸生产实现钼精矿集约化焙烧，将有效促进污染防治和综合利用。     

GEO和IGSO卫星增强GPS性能的仿真分析

为了增强GPS在亚太地区的导航性能,提出了一种利用GEO和IGSO卫星增强GPS星座的方法。通过仿真分析,研究了该地区在星座增强前后的卫星可见性、PDOP值等方面的变化规律,通过对比导航系统在全球范围内的性能表现,证明这种增强系统在定位精度和可用性方面均有较大提高。     

Dilution of flammable vapor cloud formed by liquid hydrogen spill

The flammable vapor cloud formed by liquid hydrogen spill can severely threaten the safety of life and property, which is one of the primary concerns during handling liquid hydrogen. Mixture model and Realizable k-ε model are adopted in ANSYS Fluent to predict the two-phase flow of liquid hydrogen spill. Dilution of the hydrogen vapor cloud formed by liquid hydrogen spill is analyzed, including the turbulent disturbance during cloud dispersion, and the cloud dilution characteristics especially its behavior under different wind speeds. The results show that the turbulent disturbance in the upper part of flammable vapor cloud can be 7.21 times of that in the background atmosphere, due to the mixing of the vapor cloud with the incoming wind and the upper air. The dilution time, needed for the vapor cloud to be diluted below the lower flammable limit since the end of the spill, increases firstly and then turns to decrease with the increasing wind speed. The atmospheric turbulence, the turbulent disturbance induced by the upward movement of vapor cloud, and the cloud frontal area all affect the dilution behavior.     

连续流动法测定卷烟主流烟气中氰化氢的影响因素及方法改进

为了使连续流动法更准确地测定卷烟主流烟气中的氰化氢(HCN),考察了甲醛、乙醛、丙酮、丙烯醛对连续流动法测定体系的影响,并考察了不同浓度的甲醛对测定体系的影响,以及稀释与不稀释卷烟烟气气相捕集液及粒相萃取液中HCN的稳定性.结果表明:①甲醛对连续流动法测定体系影响最大,乙醛、丙酮及丙烯醛影响较小,可以忽略;②当甲醛含量在5.80 μg/mL时,HCN测定值降低7.38％,当甲醛含量在11.49 μg/mL时,HCN测定值降低13.51％;③甲醛对样品的稳定性影响最大,乙醛、丙酮及丙烯醛影响较小,可以忽略;④不稀释卷烟主流烟气气相捕集液及粒相萃取液中的HCN稳定性差,稀释卷烟烟气气相捕集液及粒相萃取液的稳定性明显改善;⑤方法的回收率在100％ ～ 104％之间,相对标准偏差1.11％.该法与离子色谱法的HCN检测值的相对偏差＜5％.     

Simulations of Dye Releases off the Coast of New Jersey: Development and Validation of an Ocean Outfall Mixing Model

A kinematic mixing model has been developed to predict far field effluent distributions for ocean discharges. The model allows for complex outfall configurations and time varying discharge rates to be simulated. The model can use field observations or the output from a proven near field mixing model as input to this far field mixing model. The model uses observed or simulated horizontal currents at one location to advect the effluent plume and a scale-dependent “diffusion velocity” submodel to account for horizontal diffusive processes. To collect data to calibrate and verify the model, long-term continuous dye release experiments were conducted at two New Jersey ocean outfalls. Based upon the results of the dye release experiments, appropriate values for the diffusion velocity were determined for each outfall. Simulations using these diffusion velocities provided reasonable predictions of plume width and of average dye concentration at each transect for each outfall. This work demonstrates that an Eulerian velocity observed at one location in the coastal ocean off New Jersey may be used to predict Lagrangian transport over a distance of several kilometers.     

Growth and metabolic behaviour of Lactococcus lactis subsp. lactis IPLA 947 in anaerobic lactose-limited chemostat cultures

Lactococcus lactis subsp. lactis IPLA 947 is a starter strain isolated from a Spanish farmhouse acid-coagulated cheese. To use this strain as starter culture in Afuegal Pitu cheese manufacture, anaerobic lactose-limited chemostat cultures were used to optimise the active biomass production in a simple medium (BRFS). Growth, lactose consumption and metabolite production were measured at different pH values (5.5, 6.0 and 6.5) and dilution rates (0.06 to 0.96 h^–1). The influence of both variables on the quoted parameters was described by means of mathematical models. These provided a satisfactory representation of the experimental data. The bacterial response surface showed a significant increase in the biomass when the pH increased and the dilution rate decreased. As dilution rate increased, biomass yield increased but only at the lowest pH. The lactose consumption and the ratio of metabolic end products were also influenced by both variables. As dilution rate decreased, the residual lactose decreased and increased amounts of metabolites other than lactate (acetate, formate, ethanol) were produced. The minimum lactose consumption was obtained at pH 5.5 and 0.96 h^–1 dilution rate. A significant rise of acetate and formate levels occurred as pH increased. A maximum lactate level, along with an acetate, formate and ethanol production close to the minimum, was predicted by mathematical modelling at 0.5173 h^–1 dilution rate and pH 6.054.

Marine Wastewater Discharges from Multiport Diffusers. III: Stratified Stationary Water

Experiments on the near-field mixing of wastewater discharged from multiport diffusers into a stationary density-stratified environment are reported for conditions typical of ocean sewage outfalls. Dilutions were measured with a microconductivity probe in which the test tank was stratified with a nonconducting solution; geometrical characteristics such as rise height and layer thickness were measured by planar laser-induced fluorescence in which the test tank was stratified with refractive-index matched fluids. The port spacing was varied over a wide range encompassing rapidly merging to nonmerging plumes. The end of the near-field occurs at a distance of order one plume rise height from the diffuser. At this point the turbulence and mixing induced by the discharge is effectively damped by the ambient stratification, and little near-field mixing occurs beyond it. The results were analyzed in terms of line and point-source parameters to deduce the ranges of port spacings for which line and point plume solutions apply. Equations to predict the near-field characteristics are presented.