Determination and discussion hydraulic retention time in membrane bioreactor system

Based on the microorganism kinetic model, the formula for computing hydraulic retention time in a membrane bioreactor system (MBR) is derived. With considering HRT as an evaluation index a combinational approach was used to discuss factors which have an effect on MBR. As a result, the influencing factors were listed in order from strength to weakness as: maximum specific removal rate K, saturation constant Ks, maintenance coefficient m, maximum specific growth rate ,ua and observed yield coefficient Yobs. Moreover, the formula was simplified, whose parameters were experimentally determined in petrochemical wastewater treatment. The simplified formula is θ= 1.1( 1/β -1)(Kｓ S)/KXo , for oetroehemical wastewater treatment K and Ko eaualed 0.185 and 154.2, resoectively.     

A THEORETICAL TRAVEL TIME BASED ON WATERSHED HYPSOMETRY1

ABSTRACT: The time to hydrograph peak of a watershed basin has been found to correlate with various statistical attributes (e.g., skewness and kurtosis) of its hypsometric curve (treated as probability distribution). This paper presents a theoretical travel time that is conceptually analogous to the time to hydrograph peak and can be calculated directly from the hypsometric curve of a watershed basin based on gravity and acceleration. The theoretical travel times for 23 selected watersheds in the United States are found to correlate significantly with their corresponding hypsometric attributes. In addition, the theoretical travel times are consistent with the times of concentration estimated from the Federal Aviation Administration method. Thus, this paper offers a simple theoretical explanation to the empirically identified linkage between time to hydrograph peak and hypsometric attributes. This theoretical travel time can provide an alternative way of characterizing the effects of basin morphometry on hydrologic response.     

Demonstration of Line Transect Methodologies to Estimate Urban Gray Squirrel Density

Sciurus carolinensis ) have been labor intensive and costly, I demonstrate the use of line transect surveys to estimate gray squirrel density and determine the costs of conducting surveys to achieve precise estimates. Density estimates are based on four transects that were surveyed five times from 30 June to 9 July 1994. Using the program DISTANCE, I estimated there were 4.7 (95% CI = 1.86–11.92) gray squirrels/ha on the Clemson University campus. Eleven additional surveys would have decreased the percent coefficient of variation from 30% to 20% and would have cost approximately $114. Estimating urban gray squirrel density using line transect surveys is cost effective and can provide unbiased estimates of density, provided that none of the assumptions of distance sampling theory are violated.     

PREDICTIVE MODEL FOR NITRATE LOAD IN THE BULL RUN WATERSHED,OREGON1

ABSTRACT: Predictive models for nitrate in four streams in the Bull Run Watershed in the Cascade Mountains of Oregon were developed from a record of 17 years of nitrate samples. The models are time series regression models written in terms of Log(nitrate load). The independent variables are logarithm of 14-day mean daily stream discharge, current day's precipitation, logarithm of the previous day's precipitation, total precipitation for the previous seven days, a hydrograph position variable that indicates rising or falling limb, and average maximum air temperature for the preceding 14 days. The models describe annual cycle and seasonable trends and variations in nitrate load, but are unable to describe large day to day variations like those associated with hydrograph peaks.     

显微构造分析法和包裹体方法在断层研究中的应用

在工程建设中，工地及邻近地区的断层活动性是工程设计的一项重要依据。在总结以往研究的基础上，介绍了显微构造分析法和包裹体方法在断层活动性评价中的国内外最新研究成果。事实表明，这两种方法在工程地质领域具有良好的应用前景。     

孟连,丽江地震前云南天文台时纬残差异常

本文分析了云南天文台光电等高仪自有观测以来的时纬残差异常与云南及其周邻地区大地震的对应关系；并报导了孟连、丽江地震前云南天文台的时纬残差均有明显异常。这再次证明时纬残差的明显异常可为台站周围的强震预测提供可靠信息     

环境保护要依靠公众参与——关于环境保护主要依靠力量的市民调查

环境问题和环境保护已日益深入到社会政治、经济、文化、生活各个领域。在呼吁公众参与的条件下，依靠谁去搞好环境保护？公众是如何看待自己在环境保护中的作用的呢？对这些问题的回答将有助于了解公众关于环境保护的心态，有助于环境保护公众参与政策更具有针对性的实施。本文就这一话题进行了城市居民的抽样调查。调查表明，公众普遍认为，政府和公众参与是搞好环保的主要依靠力量；而公众对环境宣传教育和污染企业的治理以及技术进步的期望较低。本文进一步分析了不同年龄、文化程度、职业和人均月收入带来的影响，以期把握不同层次公众的心态。在此基础上本文就环境宣传教育如何促进公众参与提出了一些思考。     

THE ARMA MODELS APPLIED TO THE FLOW OF KARSTIC SPRINGS1

ABSTRACT: Autoregressive moving average (ABMA) models have been applied to study the flow series of the karstic springs of La Villa, Fuente Mayor (Spain), and Aliou (France). The theoretical meaning of the parameters involved in the model upon applying it to a simplified scheme of the emptying of a karstic aquifer is first analyzed. The types of transformations necessary to apply these models to the flow series that lack normality and have strong periodic components are also indicated, as are the advantages of this type of model and the physical significance of the parameters obtained, with respect to the standpoint of hydraulics, ranging from rather homogeneous aquifers (La Villa) to extremely karstic (Aliou), including aquifers with intermediate characteristics (Fuente Mayor).     

时域反射仪结合土钻法测定土壤容重

土壤水分是土地持续利用、水资源规划与管理、环境化学、节水农业技术研究的基础。介绍了时域反射仪（TDR）及其测定土壤水分的方法及应用，并利用时域反射仪结合土钻法测定土壤容重，与经典的环刀法测定土壤容重进行了比较，结果表明：两种测定结果存在一定的差异，TDR结合土钻法测定土壤容重能连续测定而且稳定性好。     

变光焊接眼护具响应时间定义分析

通过对不同标准的变光焊接眼护具响应时间定义分析，提出各标准定义及计算值的区别，以利于帮助消费者进行产品选择和企业对产品设计的改进。