木材气体渗透系数测量的分析

本文从测量理论和测量过程两方面分析木材气体渗透系数测量,分析结果表明:测量中存在理想气体近似和节流效应产生的误差,在实际测量条件下这两项相对误差的极限值都在0.4%左右,纵向渗透通常为0.1%左右,理想气体和节流效应的实际影响可忽略。其次,实际测量过程中存在气体压强测量、流量率测量以及试件尺寸三个方面的误差,后两项可占总误差值的85%,而试件尺寸造成的误差占总误差的一半以上,三者总和为3%左右。

用体积置换法测量木材渗透系数的计算与修正

从体积置换法测量木材气体渗透系数的基本原理出发，针对水柱上升和水柱下降两种体积置换法的测量装置，分析了体积置换法测量过程中气体渗透压强的变化，以及非稳态条件对体积置换法测量结果的影响．并详细推导了测量中的有关计算式和对非稳态测量补偿的修正因子．此外，运用动力学分析方法，论证了气体渗透压强在测量中的线性变化．其中关于测量的计算及其修正的关键设定的合理性，进一步从理论上阐明了体积置换法测量木材气体渗透系数的精确性．

青铜灌区古灌渠河床渗透系数空间变异性研究

渗透系数影响地表水与地下水之间的水量交换,其大小具有空间效应。通过竖管法(单管法)、多孔介质垂向渗透系数测量仪法(双管法)测定了银川平原青铜峡市灌区汉延、惠农两条古灌渠18个试验点位的渗透系数,每个试验点进行了3组试验,共得到54组试验数据,另采取了16组原状土样进行颗粒分析。通过对试验数据的统计分析得出,研究区2条灌渠的渗透系数在0.1~1.1 m·d-1之间变化,渗透系数值总体服从正态分布,总体变异系数大小为0.441,属于中等程度变异;汉延渠河床渗透系数平均值比惠农渠稍大,但变异程度较惠农渠略小。且从上游至下游,河床渗透系数值总体变化呈下降趋势;颗粒直径是造成本研究区河段渗透系数变异的一个主要因素,但河床渗透系数的大小不仅仅受颗粒直径的影响,河床生物扰动、水化学特征变化等也可能会造成河床渗透系数发生明显变化。

Self-contained in situ sediment acoustic measurement system based on hydraulic driving penetration

A novel self-contained in situ sediment acoustic measurement system based on hydraulic driving penetration is proposed to solve the problem of large disturbances to sediments of the in situ equipments already in existence. By using a hydraulic driving device, the system drives four acoustic probes into sediments at an even speed, and this decreases disturbances to sediments introduced by the penetration of acoustic probes. By means of the special design of the central control unit, the system can work full-automatically and the data are stored self-containedly, and this avoids the requirement of real-time remote controlling from the ship. Its operating water depth, measuring depth and measuring frequency is 500m, 1.0m and 30kHz respectively. A set of in situ sound speeds and attenuation coefficients of sediments are obtained at 40 stations using the system. The results confirm that the data obtained by the in situ sediment acoustic system are accurate and credible.