RIVER DYE GAGING1

Procedures have been developed (a) to inject a tracer at a constant rate below the water surface at selected points across a stream and (b) to deal with suspended sediment. Mixing remained far from complete in relatively long channels, owing to channel and flow divergence with uncertainty where to sample downstream and which marginal sample values to include for flow calculation. These problems are encountered when mixing is largely dependent on transverse diffusion. Accurate and replicable results were obtained where dye was injected upstream and detected downstream from riffles that induced thorough turbulent mixing. Dye gaging should be practical in gorges or wherever flow is turbulent across the whole width of a channel.     

USE OF STATE ESTIMATION TECHNIQUES IN WATER RESOURCE SYSTEM MODELING1

ABSTRACT. A relatively straightforward illustration of the potential uses of State Estimation techniques in water resources modeling is given. Background theory for Linear and Extended Kalman Filters is given; application of the filter techniques to modeling BOD and oxygen deficit in a stream illustrates the importance of model conceptualization, model completeness, uncertainty in model dynamics and incorporation of measurements and measurement errors. Potential applications of state estimation techniques to measurement system design; model building, assessment and calibration; and data extension are explored.     

SEDIMENT DEPOSITION ESTIMATION FROM CESIUM-137 MEASUREMENTS1

ABSTRACT The movement of fallout ¹³⁷Cs carried by soil particles was studied as an indicator of erosion and sedimentation in the Allerton watersheds and 4-H Memorial Lake located near Monticello, Illinois. Sediment deposition was greater in the waterway draining from watershed IB than in the waterway from watershed IA. At the average rate of 2.3 cm/yr of sediment deposition in the lake (from 1954 to 1979), there will be a loss of over 2 meters of water depth in the next century. However, there appears to be a decreasing rate of sediment deposition in the 4-H Memorial Lake as a result of improved conservation practices on the watersheds and the increased effectiveness of vegetated waterways and buffers for retaining sediment.     

Objective and subjective measurements of slipperiness in fast-food restaurants in the USA and their comparison with the previous results obtained in Taiwan

Floor slipperiness is a critical issue in slip and fall incidents which are a major source of occupational injuries. The objectives of the current study were to investigate if the protocols used in a field study conducted in Taiwan could be used in similar environments in the USA and whether consistent results could be obtained. Protocols used in the field study to investigate floor slipperiness in western-style fast-food restaurants in Taiwan included both objective and subjective measurements. Using the same methods as in Taiwan, friction was measured on tiles in six major working areas of 10 fast-food kitchens in the USA as an objective measurement of slipperiness, while the subjective measurement was employees’ ratings of floor slipperiness over the same areas. The Pearson’s and Spearman’s correlation coefficients in the USA between the averaged friction coefficients and subjective ratings for all 60 evaluated areas across 10 restaurants were 0.33 (p = 0.01) and 0.36 (p = 0.005), respectively, which were lower than the correlations of 0.49 and 0.45, respectively, obtained in Taiwan. Cultural differences, the amount of water on the floors in the sink areas and the existence of a slip resistant shoe program in one country might be contributors to the lower correlation coefficients in the USA. However, the current study confirmed the results obtained in Taiwan that average friction coefficient and perception values are in fair agreement, suggesting that both might be reasonably good indicators of slipperiness.     

EVALUATING DIRECT BENEFIT ESTIMATION PROCEDURES FOR IRRIGATION PROJECTS: A SIMPLIFIED APPROACH1

ABSTRACT: An integral part of evaluating the net benefits generated by an existing or proposed irrigation project is the assessment of the associated impacts in commodity markets. Traditionally, these impacts have been measured by either assuming no change in commodity prices and calculating net returns to project farmers, or by allowing commodity prices to fall in accordance with a given elasticity of demand and subtracting commodity production costs from the associated area under the commodity demand curve. In either case, it is implicitly assumed that supply is perfectly inelastic. This article establishes that traditional approaches to measuring direct benefits are biased. Formulae are presented for calculating the maximum absolute and relative error which may result from using these techniques as a function of project size. Direct benefit estimates are then evaluated for three irrigation projects in Nebraska, illustrating how these results can be used to improve project evaluation procedures.     

沼液中悬浮物对乙醇发酵的影响及其絮凝处理的研究

乙醇-沼气双发酵耦联工艺的应用有望实现乙醇工业工艺废水"零排放"的目标.本研究对该耦联工艺的回用配料水——中温沼液中的悬浮物对乙醇发酵的影响进行了考察,并对其去除方法进行了确定.结果表明,沼液中悬浮物的存在会促进酵母细胞的繁殖,提高发酵速率,但副产物甘油及小分子有机酸的量大幅上升,而主产物乙醇的生成量减少,悬浮物对乙醇合成的临界抑制浓度为0.35 g·L-1(干重).采用不同的絮凝剂及絮凝方式对沼液中的悬浮物进行去除,发现絮凝剂聚合氯化铝(PAC,300 mg·L-1)与阳离子聚丙烯酰胺(CPAM,2 mg·L-1)协同处理时效果最佳,对沼液浊度、色度的去除率分别为92.4%、23.7%,所得上清液的悬浮物粒径小于2μm,PAC、CPAM的残留量分别为0.82、0.03mg·L-1.絮凝处理后消除了悬浮物对乙醇合成的抑制作用,且絮凝处理后沼液回用的发酵性能略优于离心所得沼液回用的发酵水平,达到了预期的目的.     

微生物学检验中菌落总数测量结果不确定度的评定研究

文章主要分析了微生物学检验中菌落总数测量不确定度的数学模型、测量不确定度的来源分析、测量不确定度的计算以及相应的表示方法.微生物学检验中菌落总数的测定,其特点是同一样品测定结果相差极大,由随机效应带来的测量重复性所导致的不确定度占了主要部分.通常的做法是对同一样品作多次测量,取对数后进行计算.     

30CrMnSiA合金钢3种涂层体系耐蚀性研究

目的研究西沙海洋环境下30CrMnSiA合金钢三种(C1,C2,C3)涂层体系的耐腐蚀性能。方法在西沙海域环境开展30CrMnSiA合金钢三种涂层的自然暴晒实验,暴晒实验时间为3年,分别通过测试光泽度、色差、电化学阻抗值等手段检测腐蚀状况来研究腐蚀特点。结果三种涂层的光泽度和色差随着时间的增长逐渐减少,暴晒后三种涂层的光泽度和色差相差不大,但三种涂层检测的电化学阻抗值相差很大,且C1涂层阻抗值明显大于C2和C3涂层。结论 C1涂层体系相较于C2和C3两种涂层体系有更高的耐腐蚀性能。     

平面问题中主应变测量不确定度评定

目的实现平面场中主应变的测量不确定度评定。方法首先建立主应变的是非线性传播测量模型,然后应用基于二阶TAYLOR级数展开理论的不确定度传播方法(LPU方法),开展平面问题中主应变的测量不确定度评定。针对二种常用的应变花,建立以主应变为输出量、以应变花之三个方向测量应变为输入量的测量模型,并将二阶LPU方法应用于该模型。设计数值计算算例,以说明主应变不确定度的评定过程和方法,并与一阶LPU结果进行了比较。结果当应变花三个方向的应变测量结果相近时,文中方法与一阶LPU方法获得的主应变的不确定度评定结果存在明显的差异,主应变不确定度评定结果在数值上都大于应变花测量的不确定度。当应变花三个方向的应变测量结果相差较大时,文中方法和一阶LPU方法获得的主应变测量不确定度评定结果相差不大。结论特定情况下,主应变的测量不确定度值远大于应变花测量的不确定度,且与一阶LPU方法的评定结果有显著差异,二者可相差一倍。     

气象因素对长三角背景地区甲烷浓度的影响分析

通过分析2009年1月～2011年12月临安区域大气本底站在线观测获得的CH4浓度,研究地面风向、地面风速、地面气温、日照等气象因素对长三角背景地区CH4浓度的影响.结果表明,临安站CH4浓度的日变化分布表现为单峰型形态,下午低、凌晨高,浓度日变幅在19.0×10-9～74.7×10-9(摩尔分数)之间;季节变化特征表现为春季低、秋季高,月均浓度分布在1 955.7×10-9～2 036.2×10-9之间.NE～SSE风向上CH4浓度较高,SW～NNW风向上CH4浓度较低;地面风速越大,CH4浓度越低;地面气温升高,CH4浓度出现先升后降的分布;随着日照时数的增加,CH4浓度亦表现为先升后降的分布特征.