The Kinematic Flow Structure for the Gvirtzman–Gorelick In Situ VOC Remediation System

Potential theory and Stokes' stream function techniques are used to investigate the flow structure around the recirculation system developed by Gvirtzman and Gorelick (1992, 1993), which consists of an extraction well and a gallery (trench) for the recharge of treated water to the aquifer. Analytical formulas are derived for the drawdown, velocity, and stream function for a model in which the extraction well is modeled as a uniformly distributed line sink and the gallery is modeled as a uniformly distributed ring source. Travel times are reported for water particles traveling along the streamlines containing 50 and 90% of the flow for various degrees of well penetration and various radii of the ring source. The travel times along the streamline resulting in the shortest travel time (not necessarily the shortest path) are also reported for various degrees of well penetration and various radii of the ring source. The method completely eliminates the use of numerical finite-difference or finite-element methods and can be used for optimization of technological parameters of this remediation system.     

ASE/GC-MS法同时测定海洋沉积物中65种多氯联苯、多环芳烃与有机氯农药

建立了加速溶剂萃取/气相色谱-质谱法(ASE/GC-MS)同时测定海洋沉积物中28种多氯联苯(PCBs)、16种多环芳烃(PAHs)和21种有机氯农药(OCPs)的分析方法.结果表明,ASE的最佳萃取温度为100 ℃,最佳静态时间为5 min.GC-MS同时分析65种化合物时,PAHs的线性范围为0.05 ～5.00 ...     

粘滑混合边界条件下平面边界前的Stokes流动

对具有粘滑混合边界条件的平面边界,建立一个Stokes流动的一般性定理,利用双调和函数A与调和函数B,表示了3维Stokes流动的速度场和压力场.关于无滑动平面边界前Stokes流动的早期定理,成为该一般性定理的一个特例.进一步地,从一般性定理导出了一个推论,根据该Stokes流函数,给出了粘滑边界条件时刚性平面轴对称Stokes流动问题的解,得到了流体作用在边界上的牵引力和扭矩公式.给出了一个说明性的例子.     

Navier-Stokes方程流函数形式两重网格算法的误差分析

对定常Navier-Stokes方程流函数形式两重网格有限元算法进行了误差分析。此方法包括在粗网格上求解一个非线性问题，在细网格上求解一个线性问题，然后再在粗网格上求解一个线性校正问题。分析了包括校正项和不包括校正项两种方法的误差，得出对于任意固定的Beynolds数，能达到最优逼近阶。     

具有特定非零Walsh谱值个数的布尔函数的研究及构造

布尔函数与其变元的相关性与流密码的相关攻击有紧密联系，Walsh变换则是研究布尔函数相关特性的主要工具，本文研究了非零Walsh谱值个数k=9，10的布尔函数，证明了k=9的函数的不存在性，并构造了所有k=10的函数。     

A high‐order accurate method for two‐dimensional incompressible viscous flows

A high‐order accurate solution method for complex geometries is developed for two‐dimensional flows using the stream function–vorticity formulation. High‐order accurate spectrally optimized compact schemes along with appropriate boundary schemes are used for spatial discretization while a two‐level backward Euler implicit scheme is used for the time integration. The linear system of equations for stream function and vorticity are solved by an inner iteration while contravariant velocities constitute outer iterations. The effect of curvilinear grids on the solution accuracy is studied. The method is used to compute Cartesian and inclined driven cavity, flow in a triangular cavity and viscous flow in constricted channel. Benchmark‐like accuracy is obtained in all the problems with fewer grid points compared to reported studies. Copyright © 2006 John Wiley & Sons, Ltd.     

Variations in Grain Size Analysis with a Time‐of‐Transition Laser Sizer (Galai CIS‐50) using a Gravitational Flow System

This study deals with grain size analysis with a Laser Sizer Galai CIS‐50. This device utilizes the time‐of‐transition method and is equipped with a module for measurements in the range 0.5 to 150 μm along with a gravitational flow system. Experiments were conducted using natural marine sediments. The aim was to determine possible explanations for discrepancies in the measured results that occurred between different operators of the Galai CIS‐50. These discrepancies may be due to differences in the technique of inserting a sub‐sample into the measurement system. Furthermore, the influence of the sample concentration and the flow velocity in the device's liquid flow cell is considered, since these factors can act as potential sources of inaccuracies and errors in the experimental setup. Strong variations in the results occurred, which were mainly due to problems in the detection of particles >20 μm. In the range>20 μm gaps appeared in the registration of the size distribution. An improvement in reproducibility was achieved by using a pipette instead of a beaker for the insertion step. Nevertheless, the standard deviation for mean grain sizes of natural marine sediments obtained with the Galai CIS‐50 is still about 20%.     

An Approximate Distribution for the Maximum Order Complexity

In this paper we give an approximate probability distribution for the maximum order complexity of a random binary sequence. This enables the development of statistical tests based on maximum order complexity for the testing of a binary sequence generator. These tests are analogous to those based on linear complexity.