脱硫石膏粒径分布与脱水性能实验研究

脱硫石膏粒径分布是影响脱硫石膏浆液脱水性能的重要因素之一,以干法、湿法筛分和研磨破碎获得不同粒径分布的脱硫石膏,在相同的过滤条件下,对不同粒径分布脱硫石膏浆液脱水性能进行了研究,实验结果表明,当脱硫石膏粒径d50大于50μm且（d90-d10）小于100μm,真空过滤最大真空度不低于0．098MPa,过滤时间不少于2．5min,滤饼厚度不超过20mm时,石膏滤饼含水率可以降低到12％以下（最低可达10％）;d50在17μm为脱硫石膏在相同的过滤条件下能够实现真空脱水干燥的转折点;d50和（d90-d10）共同影响石膏脱水性能,d50小于20μm时,仅表现为d50的影响。     

Projecting Cumulative Benefits of Multiple River Restoration Projects: An Example from the Sacramento-San Joaquin River System in California

Despite increasingly large investments, the potential ecological effects of river restoration programs are still small compared to the degree of human alterations to physical and ecological function. Thus, it is rarely possible to “restore” pre-disturbance conditions; rather restoration programs (even large, well-funded ones) will nearly always involve multiple small projects, each of which can make some modest change to selected ecosystem processes and habitats. At present, such projects are typically selected based on their attributes as individual projects (e.g., consistency with programmatic goals of the funders, scientific soundness, and acceptance by local communities), and ease of implementation. Projects are rarely prioritized (at least explicitly) based on how they will cumulatively affect ecosystem function over coming decades. Such projections require an understanding of the form of the restoration response curve, or at least that we assume some plausible relations and estimate cumulative effects based thereon. Drawing on our experience with the CALFED Bay-Delta Ecosystem Restoration Program in California, we consider potential cumulative system-wide benefits of a restoration activity extensively implemented in the region: isolating/filling abandoned floodplain gravel pits captured by rivers to reduce predation of outmigrating juvenile salmon by exotic warmwater species inhabiting the pits. We present a simple spreadsheet model to show how different assumptions about gravel pit bathymetry and predator behavior would affect the cumulative benefits of multiple pit-filling and isolation projects, and how these insights could help managers prioritize which pits to fill.     

Assessment of <Emphasis Type="Italic">Gmelina arborea</Emphasis> sawdust–cement-bonded rainwater storage tank

The performance of a mixture of a forest bye product and cement for the production of storage structure for harvested rainwater was assessed. Three mix ratios of Cement: Gmelina arborea sawdust 3.0:1.0 (specimen A), 2.5:1.0 (specimen B) and 2.0:1.0 (specimen C) were considered. Engineering properties and dimensional stability of the different mix-ratios were monitored from prototypes cylindrical pots and test billet specimens. Possible change in quality of stored rainwater, with time was monitored in all the three cases. Water quality parameters monitored include pH, hardness, total suspended solids, alkalinity, acidity and total dissolved CO₂. The tensile stress obtained were 110, 104, and 95 N/mm², while the compressive strength were 5,000, 3,000, and 2,000 kN for specimens A, B and C respectively. Accelerated aging test showed that sample A were more resistant to deformation, while specimen C were more susceptible to change in structure over time. Similarly, the values of tensile and compressive strength after accelerated aging test increased in the order of specimen A > B > C. Except in specimen C where significant differences in alkalinity and acidity were observed, there were no significant differences in quality of the water stored in the pots after 2 months of storage. The results indicate the suitability of the Gmelina arborea waste as an alternative in constructing water storage structures in rural communities.     

机柜振动、冲击响应特性的试验研究

机柜是设备的安装架,当其受到某一安装平台的振动与冲击作用后,随着安装位置的不同,机柜内安装的单元设备所经受的振动、冲击量值和谱型也有很大不同。因此对于单元设备的振动、冲击考核条件不应等同于整系统的要求,而应该根据其安装平台的响应制定。     

爆炸荷载作用下钢筋混凝土防爆墙动力响应研究

为了研究钢筋混凝土防爆墙的抗爆能力,采用有限元分析方法对不同纵向配筋率、不同高跨比、不同厚度的墙体在爆炸动态荷载作用下的动力响应进行研究,对各种不同设置的钢筋混凝土防爆墙的抗爆性能进行评估。结果表明:减小高跨比对提高钢筋混凝土防爆墙的抗爆能力最为重要,提高纵向配筋率,增加厚度都能增加防爆墙的抗爆能力。     

The sex in short supply for matings varies over small spatial scales in a katydid (Kawanaphilanartee, Orthoptera: Tettigoniidae)

In katydids such as Kawanaphilanartee, a female bias in the operational sex ratio (OSR) results in female competition for mates and male choice of mates. Previous work showed that the excess of sexually active females occurs when food availability is low, in part because less food increases the propensity of females to mate as they forage for the large edible spermatophores produced by males. In this study with K.nartee, a pollen-feeding species, we estimate natural variation in numbers of sexually active males and females by assessing male calling activity and the propensity of females to respond to experimental calling males. We found an excess of sexually active males at a site with many flowers and an excess of sexually active females at a site with few flowers about 900 m away. Between-site differences in gut masses of calling males were consistent with the hypothesis that pollen availability controls OSR. Finally, at a third site where flowers were at first scarce, we found that the initial excess in sexually active females changed to an excess of sexually active males after a clump of grass-trees flowered. The mean gut mass of all sampled males from this site increased after flowering. The large variation in OSR that we document for K. nartee highlights the importance of identifying the appropriate spatial and temporal scales over which OSRs are measured in studies of factors controlling sexual selection. Received: 13 May 1997 / Accepted after revision: 27 October 1997     

内乡-镇平4.7级地震及震后应急

内乡 -镇平 4 7级地震 ,是河南省解放以来唯一一次造成人员伤亡的地震事件。本文对这次地震的震害及烈度进行了考察评定 ,总结了有关部门的震后应急措施 ,讨论了从这次地震中应吸取的经验教训。     

太湖蓝藻水华时空分布与预警监测响应的分析

选择2007和2008年200幅EOS/MODIS太湖蓝藻监测遥感影像,统计分析了梅梁湾、竺山湾宜兴段、贡湖湾、东太湖胥口湾和湖州方向湖体蓝藻水华爆发的空间和时间分布规律。并在得出全太湖蓝藻水华空间和时间分布规律的基础上,从环境监测部门蓝藻预警监测工作的实际出发,将蓝藻水华预警监测的响应划分为常规监测和应急监测,提出了具体的监测要求,为环太湖地区的相关部门更好地开展蓝藻预警监测工作提供了科学依据。     

侧流FNA抑制的CANON颗粒-絮体复合系统参数优化

为探究侧流游离亚硝酸(FNA)处理抑制亚硝酸盐氧化菌(NOB)策略相关工艺参数的最佳组合,在颗粒-絮体复合系统的全程自养脱氮(CANON)工艺中,采用批次试验探讨污泥沉降时间、FNA处理浓度及处理时间对相关功能菌活性的影响,针对性抑制NOB活性,降低FNA对功能菌活性影响.结果显示,沉降时间影响处理污泥中功能菌群活性,随着沉降时间的延长,排出污泥中厌氧氨氧化菌(AnAOB)活性逐渐减弱.沉降1min后进行排泥排出了大部分NOB并且反应器内保留了尽可能多的AnAOB,此时排出的污泥中AnAOB、氨氧化菌(AOB)和NOB的相对活性分别为15.79%、54.55%和68.63%.综合FNA对NOB和AOB活性的影响,采用0.6mg/L的FNA抑制12h后AOB活性为38.71%,而NOB活性仅为12.5%.响应曲面分析结果显示,FNA处理时间、处理浓度是影响NOB、AOB活性的关键因素.     

Prevalence of the Crayfish Plague Pathogen Aphanomyces astaci in Invasive American Crayfishes in the Czech Republic

Abstract:  In Central Europe invasive North American crayfishes are carriers of the oomycete Aphanomyces astaci, which causes crayfish plague. This lethal disease currently represents one of the major threats to native European crayfishes. We used molecular methods—species-specific amplification and sequencing of the pathogen DNA—to investigate the prevalence of individuals latently infected with A. astaci in 28 populations of two invasive American crayfish species (6 of the signal crayfish [ Pacifastacus leniusculus ] and 22 of the spiny-cheek crayfish [ Orconectes limosus ]) in the Czech Republic. The pathogen occurred in 17 investigated populations. We recorded a high variation in positive reactions, ranging from 0% to 100%, in populations of O. limosus . In P. leniusculus, however, only one individual out of 124 tested positive for the pathogen. There was a clear relationship between the water body type and pathogen prevalence in O. limosus . Infection ratios in isolated standing waters were usually low, whereas in running waters, pathogen prevalence often exceeded 50%. Other evaluated characteristics of potential plague pathogen carriers (size, sex, and the presence of melanized spots in the cuticle) seemed to be unrelated to infection. Our data suggest that in contrast to other European countries, O. limosus seems to be the primary reservoir of crayfish plague in the Czech Republic. Although all populations of alien American crayfishes may be potential sources of infections and should be managed as such, knowledge on the prevalence of the plague pathogen at various localities may allow managers to focus conservation efforts on the most directly endangered populations of native crayfishes.