低强度超声波强化污水生物处理中超声辐照污泥比例的优化选择

通过超声波的SBR反应器与对照反应器处理人工配制生活污水的对比试验,研究了利用低强度超声波强化污水生物处理的另一个重要工艺参数———超声处理污泥比例(即超声处理污泥量占反应器内总污泥量的百分比).设置超声波反应器采用频率35kHz、声强0.3W/cm²超声波每隔8h取反应器中一定比例的活性污泥辐照10min后再返回反应器.结果表明,超声处理污泥比例为10%时,其COD和NH₃-N去除率可分别提高5%和0.5%左右,以好氧呼吸速率(Oxygen Uptake Rate,OUR)表示的污泥活性可提高12%以上.通过对污泥增长率的研究表明,当超声污泥比例为10%,超声波反应器内污泥的增长率比对照反应器降低了11%左右,减轻了后续污泥处理工序的负荷.随着超声处理污泥比例的增加,污泥体积指数SVI持续增大,但是超声污泥比例不超过10%对污泥沉降性能影响不大.因此,在超声强化污水生物处理工艺中,可采用强度0.3W/cm²超声波每隔8h取反应器中的10%的活性污泥辐照10min后再返回反应器,来提高反应器的生物处理效率.     

Economic Analysis of CO2 Emission Trends in China

Climate change is one of hot spots all around the world. China, the second biggest CO₂ emitter, is facing increasingly severe pressure to reduce CO₂ emission. The article first describes Kaya Identity and its policy implications. Second, it uses the modified Kaya Identity and makes decomposition without residues on CO₂ emission during the period 1971-2005. Taking into account the changes of macroeconomic background, it conducts a detailed analysis in terms of CO₂ emission trend from 4^th Five Year Plan through 10^th Five Year Plan. The decomposition results indicate that economic development and increase in population are major driving forces, and that improvement in energy efficiency contributes to the reduction of CO₂ emission, and that decarbonization in primary energy structure is also an important strategic choice. Finally, the article stresses that in CO₂ order to realize the binding target of 20% reduction in GDP energy intensity during the 11^th Five Year Plan, China should speed up the readjustment of the industrial structure and energetically develop the energy-efficient technologies and clean fuel technology, which will effectively promote the country to reduce CO₂ emission and contribute to the mitigation of climate change.     

石油野外作业工人体力劳动强度分级调查

据ＧＢ３８６９—８３标准对江汉油田测量、地震、钻井、井下四类野外作业３４名工人、２４个工种进行了体力劳动强度分级调查，其结果：测量作业为Ⅰ～Ⅱ级；钻井作业Ⅱ级占５／８，Ⅲ级占１／４；井下作业Ⅲ级占２／３；地震作业Ⅲ、Ⅳ级各占４／９、２／９。说明前两类基本属中等强度劳动，后两类大部分属重强度劳动。     

RUNOFF AND SEDIMENT YIELD UNDER GRAZING IN FOOTHILLS FESCUE GRASSLANDS OF ALBERTA1

ABSTRACT: Grazing can have a profound impact on infiltration and thus runoff and erosion. The objectives of this study were to quantify the effects of select grazing systems on rainfall and snowmelt induced runoff and sediment yield from sloped areas of the foothills fescue grasslands of Alberta, Canada. The effects of two grazing intensities (heavy and very heavy) for two durations (short duration and continuous throughout the growing season) were compared to an ungrazed control between June 1988 and April 1991. Runoff was measured using 1-rn² runoff frames and collection bucket systems. Sediment yields were then determined on samples from the collected runoff. Snowmelt was the dominant source of runoff. Snowmelt runoff was higher from the heavily grazed areas than from the very heavily grazed areas, due to the higher standing vegetation which accumulated snow in the former areas. Sediment yields as a result of snowmelt were generally low in all areas. Only a few summer storms caused runoff. Runoff volumes and sediment yields from summer rainstorms were low, due to low rainfall and to generally dry antecedent soil moisture conditions. The greatest risk of summer runoff, and thus sediment yield, appears to occur in August.     

SIZING SMALL STORMWATER PUMP STATIONS1

ABSTRACT: Design of a stormwater pump station is a complicated procedure because of the large number of parameters that are involved. Even the most basic pump station serving a small catchment requires a computationally intensive iterative evaluation. However, the design problem consists primarily of finding the combination of temporary storage and pump capacity that accommodates runoff of the selected recurrence interval for the least cost. A procedure is developed for rapidly obtaining the needed relation between storage volume and discharge for small pump stations where a constant outflow can be assumed and the inflow hydro-graph can be represented using the modified rational method with rainfall given by a widely-used intensity-duration equation. Accepting the limitations of the modified rational method and the simplifications applied to pump station operation, the procedure provides an uncomplicated way of rapidly finding the stormwater runoff volume that needs to be temporarily stored for given values of pump discharge and activation water level (or, equivalently, activation storage volume). Ultimate determination of temporary runoff storage will depend on an economic analysis of the trade-off between storage volume and pump capacity.     

REGIONAL RAINFALL INTENSITY-DURATION-FREQUENCY CURVES FOR PENNSYLVANIA1

ABSTRACT: A statistical analysis of all available continuous hourly and 15-minute duration rainfall records for Pennsylvania was performed to develop an updated procedure to estimate design storms. As a resuit of this study, Pennsylvania was divided into five homogeneous rainfall regions and a set of rainfall intensity-duration curves developed for each region, for return periods of 1 to 100 years and durations ranging from 5 minutes to 24 hours. The PDT-IDF curves were judged to be a better representation of Pennsylvania rainfall than the nationwide TP-40 maps, particularly for storm events of 10-years and lower return periods. The average time distribution of 24-hour storms in Pennsylvania was found to be well represented by the SCS Type II distribution. The Corps of Engineers SPS 24-hour distribution was found to differ appreciably from both the SCS Type H and the Pennsylvania 24-hour storm distribution. For storm durations between 15 and 90 minutes the standard Yarnell intensity-duration curves closely resemble Pennsylvania storm distributions.     

内蒙古草原四种主要禾本科牧草若干生理特性的研究

禾本科牧草是内蒙古草原植物群落中最重要的优势植物。其中，无芒雀麦（Ｂｒｏｍｕｓｉｎｅｒｍｉｓ）、冰草（Ａｇｒｏｐｙｒｏｎｃｒｉｓｔａｔａｕｍ）、老芒麦（Ｅｌｙｍｕｓｓｉｂｉｒｉｃｕｓ）和麦草（Ｅｌｙｍｕｓｔａｎｇｕｔｏｔｕｍ）是大部分草原的建群种。本文运用室外试验田材料采集和室内实验测定相结合的手段分别为这４种禾木科牧草的蒸腾强度、光合作用、叶绿素含量等生理特性进行研究，结果表明，禾本科牧草一日内蒸腾强度最高值出现于１２：００－１４：３０，到下午４：００有一小回升；光合强度以开始繁殖期为最强。四种牧草中生产潜力最高的是老芒麦。在内蒙古草原上，水分是非常重要的要素，测定表明，空气相对湿度与老芒麦的叶子含水量呈正相关，相关系数达０．９９３。     

单一重现期非线性暴雨强度模型参数的确定--新型混合加速遗传算法的构建与应用

对浮点编码遗传算法进行了改进,并嵌入Powell方向加速局部搜索算法与加速循环操作,从而构建了新型混合加速遗传算法.确定单一重现期的非线性暴雨强度模型参数的应用实例表明,该方法兼顾了改进浮点编码遗传算法和Powell算法的优点,是一种既可以较大概率、快速地搜索全局近似最优解,又能进行局部细微搜索的出色的非线性优化方法.该法在其它工程问题的非线性模型参数的确定中也具有广阔的应用前景.     

地下储罐爆炸事故源强估算

从能量释放的角度出发，以爆炸理论为基础，利用爆破技术中已得出的结论，着重研究地下储罐爆炸事故源强的估算方法。确定各种伤害效应的安全距离，为预防事故和安全评价提供理论依据。