浮动生物床/地下渗滤系统耦合优化

为了使浮动生物床/地下渗滤系统合理分配两段污染负荷,充分发挥两段的处理效果,以进出水的水质为约束条件,根据其费用组成建立费用函数.以某高校工程作为实例,解得结果为浮动生物床承担46%的污染负荷BOD,而不承担污染负荷TN,基建费用减少2.7%,年度运行费用减少12%.     

阳台无土栽培器及应用初报

阳台无土栽培器是由３个栽培槽插接于夹固在阳台栏墙平台上的构架组成。栽培槽内敷以基质，以毛细束汲取营养液，满足植物生长所需。三槽的排列可按需变换成内向或外向阶梯形，到位后锁紧固定。变换时各栽培槽能始终保持正常的水平状态。构架上还有可调节高度的扶持加罩装置。因此可使栽培植物充分受光、适当遮荫、避风雨寒冷，可充分地利用阳台的面积和空间，便于园艺爱好者栽种各类蔬菜、花卉。     

深液流悬杯式水培系统设计及结球生菜应用效果初报

通过对深液流循环系统的供系统及供氧方式加以改进，使原供液系统的注入式供液改进为小孔喷施式。循环营养液由一种增氧方式改为悬杯显根增氧，循环增氧和喷射增氧等３种方式，使得栽培蔬菜根际氧气条件大为改善，提高了根系的吸收机能和活力。     

哈尔滨热电总厂T.S.P.及SO_2的研究

本文研究热电总厂大气环境质量,为该厂园林绿化规划设计提供科学依据。通过对该厂大气四季监测的结果表明,该厂所属范围及厂外一定距离内普遍存在着T.S.P.(总悬浮微粒)的污染,污染程度不一,并且一年四季变化不大。大气中SO_2浓度几乎不超标,无SO_2污染(大气中SO_2浓度接近1mg/m~3时,敏感植物才会表现出SO_2伤害症状或生长受阻)。所以可选择某些植物作绿化、净化环境所用。     

悬栅消力池消能特性的试验研究

悬栅消力池是在新疆喀什河吉林台一级水电站引水隧洞水力学模型试验中提出的一种新型的消能工型式。通过试验研究，进一步分析悬栅消力池的消能特性，加栅前后消力池内水深及消力池下游明流洞内涌浪的变化。试验结果表明：同一工况下，悬栅的设置，破坏了水跃的结构，使水流内部结构经历剧烈的改变和再调整，消耗大量的机械能。消能率整体提高，最大提高幅度为15.10％，最高消能率达95．14％。加栅后消力池内水深及消力池下游明流洞内涌浪高度都有明显消减。     

珠江口伶仃洋水域悬浮物的分布特征

2003年5月(枯水期)和8月(丰水期)对珠江口水域悬浮物进行了调查,结果表明:调查期间珠江口水域悬浮物含量在0.5～27.6mg·L1之间,平均值为5.73mg·L1。其中,夏季悬浮物的平均含量为6.60mg·L1,春季平均含量为4.86mg·L1,夏季含量高于春季;悬浮物的含量分布呈西北部水域向东南部水域递减和近岸高于远岸的特点;悬浮物含量与水透明度、盐度、pH、DO含量呈负相关,与COD含量呈正相关;该水域悬浮物含量高于大亚湾大鹏澳水域。     

Non-linear finite element analysis based on the spatial catenary cables

According to the elastic catenary theory,this paper derives the spatial catenary cable element from the exact analytical expression,which is used for finite element analysis of the structure.It deduces the precise expression of two-node cable element tangent stiffness matrix and the tension of cable end.The equivalent node load of cable element is expressed by the total load algorithm,and the non-linear equation is solved by double Newdon-rapson method.The proposed non-linear semi-analytical finite element method based on spatial catenary cable element can take full account of the impact of non-linear geometry.The initial configuration and the internal forces on any directional spatial loads can be solved.The example shows that the calculation method is accurate and effective.     

不同缓冲带植物在滨岸缓冲带中的作用

对高羊茅、紫穗槐、柽柳3种植被不同配置方式缓冲带对径流水中固体颗粒悬浮物(SS)的净化效果进行了研究。结果表明,草本缓冲带对SS的净化效果明显,可净化约83.81%的SS;3块样地沿程截流污染物效果为:草本带>灌木带≈小乔木带。通过对土壤抗侵蚀能力的评估可知,草本可提高5～20 cm土层的抗侵蚀能力,灌木可提高15～30 cm土层的抗侵蚀能力,乔木可提高25～40 cm土层的抗侵蚀能力。     

基于RUSLE的松花江流域不同侵蚀类型区泥沙输移比估算

为摸清东北黑土区土壤侵蚀与泥沙输移特征,以松花江流域为研究对象,选取不同侵蚀类型区8个水文站控制区,利用RUSLE模型,结合水文站实测输沙数据,分析了不同侵蚀类型区泥沙输移比的时空变化特征。结果表明:（1）松花江流域各侵蚀类型区均以微度侵蚀和轻度侵蚀为主,而草地、旱地和裸地侵蚀模数均呈现依次增大趋势,且大于该区容许土壤流失量,特别是松岭站、碾子山站、大石寨站和大山咀子站水文站控制区裸地土壤侵蚀模数均大于20 000 t/（km²·a）,达到剧烈侵蚀程度。不同侵蚀类型区之间侵蚀模数表现为丘陵沟壑区Ⅰ > 丘陵沟壑区Ⅱ > 天然林区 > 漫川漫岗区。（2）松花江流域不同侵蚀类型区泥沙输移比总体上表现为漫川漫岗区 > 丘陵沟壑区Ⅱ > 丘陵沟壑区Ⅰ > 天然林区。（3）同一侵蚀类型区不同年际间泥沙输移比波动起伏,而从20世纪60年代到80年代,人类活动影响较小的天然林区和丘陵沟壑区Ⅱ不同时期平均泥沙输移比相差不大,人类活动剧烈的漫川漫岗区和丘陵沟壑区Ⅰ平均泥沙输移比则表现为波动式递增。研究结果对于了解东北黑土区土壤侵蚀和泥沙输移规律,明确该区域土壤侵蚀机理和治理目标具有指导意义。     

Effect of different biofloc levels on microbial activity,water quality and performance of Litopenaeus vannamei in a tank system operated with no water exchange

In zero-exchange superintensive culture systems, flocculated particles (bioflocs) accumulate in the water column. Consequently, some control over the concentration of these particles must be performed. The objective of this study is to evaluate the effects of three concentrations of bioflocs on microbial activity, selected water quality indicators and performance of Litopenaeus vannamei in a tank system operated with no water exchange. A 44-day study was conducted with juvenile (6.8 g) shrimp stocked in twelve 850 L tanks at a stocking density of 459 shrimp m⁻³. Biofloc levels were expressed as three presets of total suspended solids (TSS) concentrations, as follows: 200 mg L⁻¹ (T200), 400–600 mg L⁻¹ (T400–600), and 800–1000 mg L⁻¹ (T800–1000). TSS levels were controlled by attaching a 40 L settling tank to each culture tank. Reduction of TSS to concentrations close to 200 mg L⁻¹ decreased the time of bacterial cell residence and significantly reduced the nitrification rates in the water (P < 0.05). The tanks in the T200 treatment had a greater variability of ammonia and nitrite (P < 0.05), which led to the need to increase the C:N ratio of the organic substrate to control ammonia through its assimilation into heterotrophic bacterial biomass. But the higher production of heterotrophic bacteria in T200 (P < 0.05) increased the dissolved oxygen demand. Nitrification rates were higher (P < 0.05) in tanks with TSS concentrations above 400 mg L⁻¹, and ammonia and nitrite were significantly lower than in the T200 tanks. We suggest that ammonia and nitrite in the T400–600 and T800–1000 tanks were controlled primarily by nitrifying bacteria, which provided higher stability of these parameters and of dissolved oxygen. Regarding shrimp performance, the reduction of TSS to levels close to 200 mg L⁻¹ was associated with better nutritional quality of bioflocs. Nevertheless, differences in biofloc levels and nutritional quality were not sufficient to affect the weight gain by shrimp. The rate of shrimp survival and the final shrimp biomass were lower (P < 0.05) when the TSS concentrations were higher than 800 mg L⁻¹. Analysis of the shrimps’ gills showed a higher degree of occlusion in the T800–1000 treatment (P < 0.05), which suggests that the shrimp have an intolerance to environments with a solids concentration above 800 mg L⁻¹. Our results show that intermediate levels of bioflocs (TSS between 400 and 600 mg L⁻¹) appear to be more suitable to superintensive culture of L. vannamei since they create factors propitious for maintaining the system’s productivity and stability