Experimental and numerical analysis of flow instabilities in rectangular shallow basins

Free surface flows in several shallow rectangular basins have been analyzed experimentally, numerically and theoretically. Different geometries, characterized by different widths and lengths, are considered as well as different hydraulic conditions. First, the results of a series of experimental tests are briefly depicted. They reveal that, under clearly identified hydraulic and geometrical conditions, the flow pattern is found to become non-symmetric, in spite of the symmetrical inflow conditions, outflow conditions and geometry of the basin. This non-symmetric motion results from the growth of small disturbances actually present in the experimental initial and boundary conditions. Second, numerical simulations are conducted based on a depth-averaged approach and a finite volume scheme. The simulation results reproduce the global pattern of the flow observed experimentally and succeed in predicting the stability or instability of a symmetric flow pattern for all tested configurations. Finally, an analytical study provides mathematical insights into the conditions under which the symmetric flow pattern becomes unstable and clarifies the governing physical processes.     

Roadside dusts and soils contamination in Cincinnati,Ohio, USA

Roadside dusts and soils were collected from various nonindustrial districts in Cincinnati, Ohio, USA, and analyzed for lead and copper contents. Results showed that the recent lead phase-down action has reduced the level of lead, but the concentrations of both metals are still higher than the background levels for normal soil. Elevated concentrations of copper in heavily traveled highways were noted, suggesting that much of the copper pollutants is probably of automotive origin. The concentration of lead was found to vary with housing age, and higher levels of contamination in the older neighborhoods were observed. This result is probably ascribable to the accumulation of residues from leaded gasoline and lead-based paint in the past and the use of coal fire for space heating in older houses.     

Effect of acidic deposition on productivity of forest ecosystem and estimation of its economic losses in southern suburbs of Chongqing

In accordance with principle sand methods of ecology, this paper studied the effects of acidic deposition on productivity and volume increment of masson pine and Cinnamomum campora forest which are widely distributed in southern suburbs of Chongqing. Based on the field data and measurements, a multivariable stepwise regression model was established to analyze the effects of multiple environmental factors on the productivity of the forest ecosystems. This model was used to assess the volume and economic losses of these two forest ecosystems caused by acidic deposition. The results showed that, among the environmental factors, pH value of precipitation, soil depth, soil organic contents and slope are the dominant ones influencing the growth of masson pine forest. It is also shown that the acidic deposition has no clear relation to the growth of C.Campora forest, so development of such broad-leaved forest is suitable in the area.     

石化企业生产操作室隔音降噪措施及控制效果的应用研究

通过对石化企业主要噪声源分布，构成情况和生产操作室隔音降噪措施及控制效果的比较，分析，提出了生产操作室噪声控制和治理的原则，方法和方向。     

森林与雾露水关系研究进展

论文从雾露水的形成机制、森林对雾露水的截留量、雾露水对森林分布的影响及雾露水的生态效应方面,阐述了国外在该领域的研究动态和取得的成果,以期推动我国在该领域的研究工作。国外的大量研究表明,雾露水对于植物的生长、分布具有重要的生态意义,是森林生态系统水分平衡、养分循环不可忽视的输入项,其生态效应是多方面的。因而,进一步深入研究雾露水与森林的关系是必要的。     

大鸨生长期能量代谢和蛋白质沉积量的初步研究

对不同日龄笼养大鸨 (Otistarda)的能量代谢和蛋白质沉积量进行研究 .结果表明 ,5 0日龄、70日龄、30 0日龄和 4 0 0日龄雄性大鸨的能量日摄入量分别为 14 98.9kJ、2 376 .2kJ、2 397.4kJ和 2 4 6 5 .9kJ;能量代谢率分别为 82 .3%、81.8%、81.8%和 83.1% ;蛋白质的日沉积量分别为 5 .8g、13.4g、15 .8g和 13.5g .表 3参 9     

用马尔柯夫模型预测马尾松低效林改造恢复过程

运用马尔柯夫模型对四川盆地马尾松低效林改造恢复过程中林分各层次盖度、多样性指数和灌木层物种组成的变化趋势进行了预测．结果表明：马尔柯夫模型可适用于退化森林生态系统人工恢复重建过程的研究；四川盆地马尾松低效林可以自然恢复，但采用封育补植措施则能加快恢复进程．对马尔柯夫模型及预测结果进行了讨论．     

电除尘技术研究现状及趋势

详细介绍了电除尘技术研究现状、现存问题及其发展趋势.论述了烟尘荷电凝聚机制及其输运特性等,以便解决除尘电场中的电离占空比、输运项甚低等问题;又着重研究了烟尘的荷电、凝聚的物理过程,将有助于解决电除尘器存在的捕集微细烟尘效率低的问题.     

硬硅钙石二次粒子对含铅废水处理效果的影响研究

对硬硅钙石间歇培养颗粒污泥处理含铅废水进行了实验研究,通过单因素分析说明Pb2 、二次粒子投加量及颗粒污泥量三者间相互作用的最佳运行参数,结果表明,营养液为100 mL的条件下,污泥量为120 mL、铅浓度为60 mg/L、硬硅钙石投加量为4 g的条件下可保持颗粒污泥的活性,铅的去除率较高,为连续运行的反应器(容积负荷为18 g COD/L·d)提供了工艺条件.