Changes in the Seam-Filtration Mode with Stress Redistribution in Country Rock

A mathematical model for the mechanism of increasing oil output of productive seams is developed. The model involves a deliberate conversion of segments of the fault zone of the country rock to a supercritical state, which leads to a local redistribution of stresses in the block massif of rocks and an increase in contour and seam pressures. Based on solving the problem of restricted filtration, it is shown that the use of the proposed mechanism can ensure a relative increase in well production of 5–8%.     

Numerical blow‐up for the porous medium equation with a source

We study numerical approximations of positive solutions of the porous medium equation with a nonlinear source, where m > 1, p > 0 and L > 0 are parameters. We describe in terms of p, m, and L when solutions of a semidiscretization in space exist globally in time and when they blow up in a finite time. We also find the blow‐up rates and the blow‐up sets, proving that there is no regional blow‐up for the numerical scheme. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2004     

Simple method for the assay of linezolid in Brain Heart Infusion broth by high-performance liquid chromatography

A simple HPLC method was developed and validated for quantification of linezolid in Brain Heart Infusion (BHI) broth. Eperezolid was employed as internal standard and the sample pre-treatment procedure was simple. Calibration standards ranged from 0.05 to 16 mg/L. Accuracy was within 7.8% and reproducibility (RSD) was less than 8.3%. Recovery was approximately 100% at all concentrations examined. Linezolid was stable in the autosampler insert for at least 24 h at ambient temperature and in BHI for 72 h at 37 degrees C. This assay is rapid and ideal for analysis of a large number of samples.     

声波导中的局部正交变换

In this paper, a local orthogonal transformation is created to transform the Helmholtz waveguide with curved interface to the one with a flat interface within the two-layer medium, and the Helmholtz equation uxx uzz k^2(x,z)u=0 is transformed to Vxx αVzz βVz γV=0. Numerical results demonstrate that the transformation is more feasible. This transformation is particularly useful for the research on wave propagation in acoustic waveguide.     

低压微位移驱动电路及控制方法

讨论了低压微位移驱动电路及控制方法在光电轮廓仪上的运用。采用低压驱动电路驱动压电陶瓷相移器对参考光束进行相移，从而使仪器质量减轻、体积缩小、成本降低。在运用该电路时，为了解决压电陶瓷低电压区非线性误差大的问题，用PC计算机控制压电陶瓷上所加电压的电压值，由摄像头摄取图像并计算出干涉条纹的间隔，然后由PC计算机修改压电陶瓷上所加的电压值，直至干涉条纹相位差达到要求值。该方法的优点是：可消除压电陶瓷低压区的非线性误差，使得开环电路得到闭环的效果；可降低机械零部件的装配难度。     

Kerr介质中双原子-压缩真空场系统的腔场谱

研究了含Kerr介质腔中耦合双原子间与双模均处于压缩真空态的光场拉曼相互作用过程的腔场谱.通过求解本征方程导出了双模光场处于任意强度时腔场谱的计算公式,给出了数值计算结果.发现在两模初始场均为弱场时,Kerr介质和原子间的耦合作用对谱结构的影响较小;当双模初始场均为强场时,两模主峰的右侧出现了半梳状边峰,随Kerr效应的增强,峰间距逐渐加宽,并向高频方向扩展,在Kerr效应较强时,两模边峰的峰高出现高低相间的现象.     

Piezoelectric resonators with mechanical damping and resistance in current conduction

A novel design method for high Q piezoelectric resonators was presented and proposed using the 3-D equations of linear piezoelectricity with quasi-electrostatic approximation which include losses attributed to mechanical damping in solid and resistance in current conduction. There is currently no finite element sofware for estimating the Q of a resonator without apriori assumptions of the resonator impedance or damping. There is a necessity for better and more realistic modeling of resonators and filters due to miniaturization and the rapid advances in frequency ranges in telecommunication. We presented new three-dimensional finite element models of quartz and barium titanate resonators with mechanical damping and resistance in current conduction. Lee, Liu and Ballato’s 3-D equations of linear piezoelectricity with quasi-electrostatic approximation which include losses attributed to mechanical damping in solid and resistance in current conduction were formulated in a weak form and implemented in COMSOL. The resulting finite element model could predict the Q and other electrical parameters for any piezoelectric resonator without apriori assumptions of damping or resistance. Forced and free vibration analyses were performed and the results for the Q and other electrical parameters were obtained. Comparisons of the Q and other electrical parameters obtained from the free vibration analysis with their corresponding values from the forced vibration analysis were found to be in excellent agreement. Hence, the frequency spectra obtained from the free vibration analysis could be used for designing high Q resonators. Results for quartz thickness shear AT-cut and SC-cut resonators and thickness stretch poled barium titanate resonators were presented. An unexpected benefit of the model was the prediction of resonator Q with energy losses via the mounting supports.     

环形光束的非线性传输及聚焦特性研究

针对用于产生光镊的环形光束,利用分步傅里叶-贝塞尔变换算法,对二维环形超高斯光束的非线性传输及聚焦过程进行了数值模拟,给出了环形光束聚焦场附近的光强分布,并分析了非线性调制对聚焦性质(包括焦面中心光强、焦面光强的横向分布、轴上光强和光束质量)的影响.研究表明,从聚焦角度来看,非线性调制中的位相调制比振幅调制对环形光束聚焦性质的影响程度要大;从非线性传输角度来看,随着非线性介质长度的增加,位相调制和振幅调制对环形光束聚焦性质各有不同程度的加剧,其中非线性作用对振幅调制的影响要比位相调制明显.     

周期性边界条件下多孔介质方腔内自然对流换热数值研究

对充满多孔介质的倾斜方腔,在其上下壁面绝热、右侧壁面维持恒温To及左侧壁面温度基于To随时间按正弦规律变化的情况下,采用Brinkman扩展达西模型和SIMPLER算法对方腔内的自然对流与换热进行了非稳态数值模拟,方腔倾角α的范围为0°～90°,Pr数为1,Ra数为106.计算研究不同的振荡频率和方腔倾角对方腔内对流换热的影响.数值模拟结果表明:振荡频率f为60π,方腔倾角为43°时,方腔内的换热最强.