爆炸冲击波作用下圆形通风设施的动态破坏特性

为了研究瓦斯爆炸对通风设施造成的严重破坏及其导致的通风系统紊乱与灾情迅速扩展问题,基于LS-DYNA有限元软件,模拟研究巷道中瓦斯爆炸冲击波作用下圆形通风设施的动态破坏特性,分析应力、应变、速度、位移的动态特征及其破坏过程,并对圆形通风设施动态破坏机理进行初步探索。研究结果表明:爆炸冲击波作用下,圆形通风设施正、反面出现压应力与拉应力分布圆环,且压应力与拉应力峰值处于在外部受约束边界径向圆环附近区域与圆心位置,应变、速度和位移最大值均分布在次区域;爆炸冲击波作用下,通风设施表面形成多圈的正向和反向的应变相互交替,呈现W型的褶皱变形;爆炸冲击波作用下,环向裂纹集中在受约束的边界区域附近,发生脆性破坏,其他区域会出现较多的径向裂纹,可发生韧性破坏,整个断裂过程是脆性与韧性断裂的混合型断裂。     

某处理厂CASS池改造工艺选择及运行效果

随着污水处理厂排到受纳水体标准的不断提高及区域污染物排放限值的要求,已建的污水处理厂需要提标改造提高排放标准。本文所提工程对现有的CASS池进行改造,通过投加悬浮填料形成CASS+MBBR工艺,其中TN污染物的去除率可提高到8%~15%间,其它污染物也能达到预期的设计标准。     

序批式生物膜反应器挂膜启动实现短程硝化

常温条件下(20～25℃),以模拟的人工配水为研究对象,采用序批式生物膜反应器(SBBR),在初期挂膜的基础上,笔者运用两种不同的挂膜方式即重新加入新泥和不加新泥而加大进水COD浓度来实现生物膜的快速启动。实验表明,2种挂膜启动通过14 d的培养与富集,NH4+-N与COD的处理效果都能分别达到85%和75%以上。将剩余污泥排尽后,采用第1种挂膜方式的反应器通过连续间歇曝气,达到了比较好的短程硝化效果。调整溶解氧,并且通过先下降后上升曝气量的方式,能进一步提高亚氮的出水。最终在DO为3.6 mg/L时,亚氮的积累率能达到平均74%左右,达到了比较好的亚硝化效果。而第2种挂膜方式培养的生物膜则以好氧反硝化菌为主,去除的氨氮由同化作用和培养的好氧反硝化菌去除,以后者为主。通过比较可以看出,为了实现短程硝化,第1种挂膜方式比第2种更具有优越性,有利于硝化菌种的生长和亚氮的积累,而第2种方式则有利于培养好氧反硝化菌。     

大学生就业难的原因分析及指导对策

本文对大学生就业存在的自身问题、高校办学专业设置和培养模式问题、用人单位的误区问题以及现今的社会问题等进行了理性分析,并提出了加强对大学生的就业指导,引导大学生树立科学理性的就业观,广泛疏通就业途径和集聚多方力量鼓励大学生自主创业的对策。     

基于指标体系的地下水环境承载力评价

在分析可持续发展指标体系及模型研究的基础上，对地下水环境承载力问题进行了探讨，并提出了相应的指标与模型，通过实全对两个模型进行了进一步阐释。结果表明，模糊优选模型较系统学模型更能反映问题的实质，结果亦更具说服力。     

城市室内环境多环芳烃污染与源的相关性

本实验选择了天津市４类典型室内环境和２处室外对照点，共１９个采样点。现场采样测定了１０种ＰＡＨｓ组成含量。结果显示，室内燃煤和室内吸烟是室内环境中多环芳烃排放的主要污染源。同作为对照的室外大气中多环芳烃组成和含量进行了对比，研究了室内环境不同污染源排放多环芳烃组成和含量的特征性。提出了室内燃煤污染同燃煤型室外大气源排放多环芳烃具有相似组成含量特征，而室内烟草烟雾污染源的多环芳烃组成含量特征则与室外     

炼油厂污泥脱水系统技术改进

阐述炼油厂污水处理场污泥的组成、性质及污泥脱水的实际情况，在原工艺处理流程的基础上采取增加污泥储存罐、污泥调理系统、污泥输送系统等设施，并进行一系列的技术改造，使得污泥脱水系统能够正常平稳运行，减少污泥对环境的污染．取得了一定的经济效益和社会效益。     

The production of sexual and asexual larvae within single broods of the scleractinian coral, Pocillopora damicornis

The genotypic compositions of two populations of the brooding coral, Pocillopora damicornis, were studied by exhaustive sampling of adult colonies on a fine scale in southern Taiwan. In addition, 100 larvae were randomly selected among more than 1,000 brooded larvae collected from a single broodparent within each population. Using 7 polymorphic microsatellite markers, both populations were found to be highly clonal, and 7 clonal lineages were characterized. One clonal lineage (C1) dominated both study areas and comprises 54.9% of all colonies sampled, while any of the other 6 clonal lineages represented no more than 5%. Among the 100 larvae randomly selected for genotyping from each broodparent, the extent of clonal reproduction was high, and only 29 and 6 larvae, respectively, were found to be genotypically different from their broodparent. Among the 35 genotypically distinct larvae, 33 were thought to be derived from sexual reproduction, and 2 were assumed to be clonal propagules that had undergone somatic mutations. Two genotypically identical larvae were also found in one of the 2 sexually derived larva arrays, indicating the possible existence of polyembryony. The high proportions of clonality in both adult colonies and brooded larvae suggest that asexually produced larvae might significantly contribute to the recruitment of local populations. The dense clonal population of P. damicornis in the study area favors the quick recolonization view of clonal propagules after disturbances.     

Plutonium in groundwater at the 100K-Area of the U.S. DOE Hanford Site

We examined the concentration, size distribution, redox state and isotopic composition of plutonium (Pu) in groundwater at the 100K-Area at the U.S. Department of Energy's (DOE) Hanford Site. Total concentrations of Pu isotopes were extremely low (10(-4) to 10(-6) pCi/kg, approximately 10(4) to 10(6) atoms/kg) but measurable for the first time in the 100K-Area wells using mass spectrometric analyses that are much more sensitive than alpha spectroscopy methods used previously. Size fractionation data from two wells suggest that 7-29% of the Pu is associated with colloids, operationally defined here as particles between 1 kDa-0.2 microm in size. These colloids were collected using a 1 kDa cross-flow ultrafiltration (CFF) system developed specifically for groundwater actinide studies to include careful controls both in the field and during processing to ensure in situ geochemical conditions are maintained and size separations can be well characterized. Pu in this colloidal fraction was exclusively in the more reduced Pu(III/IV) form, consistent with the higher affinity of Pu in the lower oxidation states for particle surfaces. While the overall concentrations of Pu were low, the Pu isotopic composition suggests at least two local sources of groundwater Pu, namely, local Hanford reactor operations at the 100K-Area and spent nuclear fuel from the N-reactor, which was stored in concrete pools at this site. Differences between this site and the Savannah River Site (SRS) are noted, since groundwater Pu at the F-Area seepage basin at SRS has been found using these same methods, to be characterized by lower colloidal abundances and higher oxidation states. This difference is not directly attributable to groundwater redox potential or geochemical conditions, but rather the physical-chemical difference in Pu sources, which at SRS appear to be dominated downstream from the seepage basins by decay of 244Cm, resulting in more oxidized forms of 240Pu. There is no clear evidence for colloid facilitated transport of Pu in groundwater at the Hanford Site, since downstream wells have both an order of magnitude lower concentrations of Pu and a lower fractional colloidal distribution.     

氯代芳香化合物的微生物降解研究

生物技术对消除有毒化学品已显示出广阔的应用前景，深入研究有毒化学品微生物降解的生物化学和遗传学，可按照预期目的构建具有更大降解能力的遗传工程菌株，以促使污染物的无害化资源化。本文对纯菌株降解氯代芳香化合物的降解途径、降解性质粒和遗传工程菌株的构建等诸方面进行了综述。