油田回注水中硫酸盐还原原核生物的快速检测和群落结构分析

利用荧光原位杂交(Fluorescence in situ hybridization,FISH)技术,采用荧光标记的rRNA探针及其组合对胜利油田胜利采油厂回注水中硫酸盐还原原核生物(Sulfate reducing prokaryotes,SRPs,包括硫酸盐还原细菌和硫酸盐还原古菌)进行检测,分析了该回注水中SRPs群落结构.结果表明:SRPs在胜利油田回注水中具有极高的种群多样性,广泛分布于4个细菌门和1个古菌门;总数可达2.86×104个/mL,占回注水中总微生物细胞的20%左右;其中优势菌属为脱硫弧菌属(Desulfovibrio)和脱硫肠状菌属(Desulfotomaculum),分别占回注水微生物总细胞数的8.71%(±4.45%),和12.15%(±3.90%).Desulfobacterales和Syntrophobacterales这2个目中的SRPs,Thermodesulfobacteriales以及Thermodesulfovibro属的SRPs分别占样品微生物总量的7.59%(±2.92%),3.57%(±1.39%)和2.32%(±0.80%).除此之外,也检测到了占微生物总量4.29%(±1.75%)的Archaeoglobus属的SRPs,证明了古菌类SRPs是回注水中一个不容忽视的硫酸盐还原微生物种群.FISH法能够快速、准确地检测回注水中SRPs数量,解析SRPs群落结构.     

甲烷煤尘耦合爆炸传播特性及伤害研究

为探究煤尘质量浓度对甲烷煤尘耦合爆炸传播特性及伤害距离的影响,自制长15 m的爆炸管道系统,用体积分数为7％甲烷分别与质量浓度为0、50、100和200 g/m3的煤尘进行耦合爆炸试验,并根据质量、动量和能量守恒理论推导出最大压力计算公式.结果 表明:不同质量浓度煤尘与甲烷耦合爆炸时,最大压力均随与爆源距离的增加呈现出...     

三江源地区1961~2005年气温极端事件变化

利用三江源地区11个气象台站1961~2005年逐日最高气温和最低气温资料，分析了三江源地区极端高温和极端低温的变化趋势。研究表明：近45年来，白天和夜间温度极端偏高的日数明显增多，分别以26 d/10 a和44 d/10 a速度在增加;白天和夜间温度极端偏低的日数显著减缓，分别以41 d/10 a和85 d/10 a的速度显著减少;年极端低温和极端高温分别以042℃/10 a和029℃/10 a的速度增加;白天和夜间温度极端偏高的日数增加主要发生在冬季和夏季，而白天和夜间温度极端偏低的日数减少主要发生在春季和秋季，夜间温度极端偏低的日数减少趋势最为明显;长江源地区极端气温变化对区域增温的响应更为敏感。     

NON-ZERO LOWER LIMIT IN LOW FLOW FREQUENCY ANALYSIS?1

ABSTRACT: The implications of fitting distributions with non-zero lower limits to low flow data are examined. The 3-parameter Weibull distribution is fitted to annual minimum flow series from 60 long term stations in Canada. The relations between the estimated lower limit and three sampling variables (skewness, smallest, and largest observations) were investigated. The lower limit strongly depends on the sample skewness; it varies directly with the sample skewness, which in turn is highly influenced by the largest observation. For a given skewness, the value of the estimated lower limit is determined by the value of the smallest observation. Therefore, the lower limit cannot be accurately determined, and the resulting low flow estimates will be either too small or too high.     

ANALYSIS OF WASTE LOAD ALLOCATION PROCEDURES1

A study was made to analyze and modify procedures used for stream assimilation capacity and point source wasteload allocation calculations. This paper describes the sources and types of information collected and the analysis of alternative computation methods developed during the study. The calculation of stream assimilation capacity or Total Maximum Daily Load (TMDL), will depend upon assumed stream flows, quality standards, reaction rates, and modeling procedures. The “critical conditions” selected for TMDL calculations usually are low flows and warm temperatures. The complexity of water quality models used for TMDL and allocation calculations can range from simple, complete mixing to calibrated and verified mathematical models. A list of 20 wasteload allocation (WLA) methods was developed. Five of these WLA's were applied to an example stream to permit comparisons based on cost, equity, efficient use of stream assimilation capacity, and sensitivity to fundamental stream quality data. Based on insensitivity to data errors and current use by several states, the WLA method of “equal percent treatment” was preferable in the example stream.     

PREDICTING INSTANTANEOUS PEAK DEMAND IN RURAL DOMESTIC WATER SUPPLY SYSTEMS1

ABSTRACT: Many rural areas of the United States still have no public domestic water systems. Typical land use patterns in these areas may require 1/2 mile or more of pipe per farm connection. Public systems serving these areas are economically feasible only if realistic short-term peak demand standards are available for their design. The lack of reliable data upon which to establish such criteria has resulted in a large variation in criteria among state and federal agencies involved in financing and in approving construction of these systems. During the summer of 1975 three distribution laterals of a rural system in Utah were master metered and instantaneous peak flows were recorded for 4 months. The metered lines served 4, 12, and 22 farm houses each. The frequency distribution of peak flows has been analyzed and compared with that developed during similar research in Mississippi and with the existing design standards of the Farmers Home Administration and the State of Utah.     

GIS在巨灾保险风险管理中的应用研究

近年来 ,巨灾的不断发生 ,使得许多保险和再保险公司遭受巨大赔偿 ,乃至可能造成破产。究其原因 ,除了人们对巨灾自身难以抗拒这一客观原因外 ,保险企业对巨灾保险的风险管理方法、技术和手段的不适也是一个很重要的因素。为此 ,笔者分析了利用GIS辅助巨灾保险风险管理的优越性 ,并就GIS在巨灾保险的信息管理、风险累积预测和风险管理专家系统中所起的作用和发挥的功能分别进行了探讨。利用GIS辅助巨灾保险风险管理 ,不仅可以了解巨灾的发生和变化规律 ,进行危险性区域和费率区域的划分 ,而且可以优化保险和再保险方案 ,并通过专家系统设计出符合实用灾情的风险管理及保险管理的对策 ,对保险公司的巨灾保险风险管理起到了重要的指导作用。     

碳二馏分加氢反应装置火灾爆炸危险性评价

运用美国道化学公司的火灾爆炸危险指数评价方法 (第七版 ) ,对碳二馏分加氢反应装置的火灾爆炸危险性进行了定量计算和评价 ,其结果表明 ,该装置的火灾爆炸危险等级为“非常大”。为了降低该装置的危险程度 ,笔者提出了采取有效的安全补偿措施 ,以降低单元的危险程度的新思路。通过分析表明 ,针对部分补偿系数对装置进行安全改进 ,能有效地降低其危险性等级 ,同时可以为避免重大危险源火灾爆炸事故 ,提供切实可行的手段和途径。     

ESTIMATING THE MEAN AND VARIANCE OF CENSORED PHOSPHORUS CONCENTRATIONS IN FLORIDA RAINFALL1

ABSTRACT: The total phosphorous (TP) concentrations in the South Florida rainfall have been recorded in weekly intervals with a detection limit (D_L) of 3.5 μg/L. As a large amount of the data is reported as below the D_L, appropriate statistical methods are needed for data analysis. Thus, an attempt was made to identify an appropriate method to estimate the mean and variance of the data. In particular, a method to separate the statistics for the below D_L portion from the estimated population statistics is proposed. The estimated statistics of the censored data are compared with the statistics of the uncensored data available from the recent years’ laboratory records. It was found that the one-step restricted maximum likelihood method is the most accurate for the wet TP data, and that the proposed method to combine the estimated statistics for TP < D_L portion and the sample statistics for TP ≥ D_L portion improves estimates compared to the conventional maximum likelihood estimates.     

A HYBRID OPTIMIZATION APPROACH TO THE ESTIMATION OF DISTRIBUTED PARAMETERS IN TWO-DIMENSIONAL CONFINED AQUIFERS1

ABSTRACT: In using non-linear optimization techniques for estimation of parameters in a distributed ground water model, the initial values of the parameters and prior information about them play important roles. In this paper, the genetic algorithm (GA) is combined with the truncated-Newton search technique to estimate groundwater parameters for a confined steady-state ground water model. Use of prior information about the parameters is shown to be important in estimating correct or near-correct values of parameters on a regional scale. The amount of prior information needed for an accurate solution is estimated by evaluation of the sensitivity of the performance function to the parameters. For the example presented here, it is experimentally demonstrated that only one piece of prior information of the least sensitive parameter is sufficient to arrive at the global or near-global optimum solution. For hydraulic head data with measurement errors, the error in the estimation of parameters increases as the standard deviation of the errors increases. Results from our experiments show that, in general, the accuracy of the estimated parameters depends on the level of noise in the hydraulic head data and the initial values used in the truncated-Newton search technique.