一种天线阵列定位法及其仿真研究

为了克服CDMA移动台(MS)定位估计中面临的远近效应问题,该文提出了一种在服务基站(BS)附近布置一种天线阵列,采用TSOA/AOA混合定位技术对MS进行定位估计的方法,分析了采用不同定位法的GDOP分布, 并给出了相应的TSOA/AOA混合定位算法。不同条件下的仿真结果表明,只要AOA测量值达到一定精度,采用这种方法就能对MS进行准确定位。     

FINITE DIFFERENCE METHOD-BASED SIMULATION OF TEMPERATURE FIELDS FOR APPLICATION TO ORTHOGONAL CUTTING WITH COATED TOOLS

A finite difference method was proposed to model the effect of a variety of tool coatings on the magnitude and distribution of temperatures through the tool-chip contact region and the coating/substrate boundaries. For each workpiece-tool pair tested the intensity of uniformly distributed heat flux and relevant analytically obtained values of the heat partition coefficient were assumed to change with variations of cutting speed and the corresponding friction. In this case the simulation of an orthogonal machining of AISI 1045 steel was performed using special computing algorithm with elementary balances of induced energies (MBE). It is concluded that the temperature contours obtained reflect favorable the specific contact conditions existing at the tool-chip interface and substantial differences can arise from coating effects.     

基于小波分解与运动补偿的弹迹检测方法

基于小波分解与运动补偿的弹迹检测方法,采用多层离散小波分解图像,以低频图像块匹配估计背景运动矢量.再利用差分算法检测射弹,计算出形心坐标并绘出射弹运动轨迹.其实现步骤包括:图像预处理-靶标定位跟踪、原始图像小波多层分解、低频图像块匹配、背景图像运动补偿及射弹检测与空间坐标推断.并以实验验证.     

油藏数值模拟求解中的IMPIMS方法

在油藏数值模拟中对数值模型进行求解,目前基本有两类方法：一类是顺序求解法,如IMPES方法和IMPIMS方法;一类是联立求解法,如半隐式法和全隐式法。IMPIMS方法是一种顺序求解方法,是IMPES和半隐式方法的混合变种。它既具有半隐式求解饱和度的特点,又保留了IMPES方法省内存,省计算工作量的优势。     

抛物型方程的一个六阶精度的差分格式及格式稳定性的—种新的证明方法

用待定系数法构违了六阶差分格式,比已有文献的四阶差分格式提高了精度。格式稳定性的证明方法也是新的。     

微分算子

微分算子是数学学科的一个比较大的分支,本文主要介绍了微分算子理论的内容、意义、发展沿革及研究方法,总结了近几年来的部分研究成果,并提出了今后的研究方向。     

Flash cosintering of a lanthanum strontium cobalt ferrite nanofibre/Gd-doped ceria bilayer structure

For solid oxide fuel cells, an important structural requirement is that the electrolyte layer needs to be dense and the electrode layer porous, which is difficult to obtain by conventional cosintering. In this work, flash cosintering of a double layer structure consisting of a Gd-doped ceria substrate with a lanthanum strontium cobalt ferrite nanofibre coating is investigated. Experimental and finite element modelling results reveal that when the LSCF layer is connected to the electrode, the heat is concentrated in the LSCF layer, which leads to a huge temperature gradient and introduces severe cracking. When the LSCF layer is electrically isolated from the electrode, the heat is concentrated in the GDC layer, and the temperature gradient is dramatically reduced. In this situation, the density of GDC can reach 92.86% while a high porosity of 52.26% is maintained in the LSCF layer, which is higher than that of the conventional cosintered sample.     

关于热传导方程的一个三层七点格式

对于热传导方程,构造出其三层七点隐格式,同时给出稳定条件。     

Difference points in reactive and extractive cascades, V: Determining reaction distribution from separatrix manifolds

The effect of reaction distribution policy on a reactive column profiles is analyzed. We find that the extent reaction on a single reactive stage can greatly influence the feasibility and termination of subsequent non-reactive stages. We develop a method to quantitatively predict when perturbing the amount of reaction on a single stage will subsequently force the column profile to become infeasible or otherwise fail to meet global design targets. To predict such behavior we rely on the map of stable invariant manifolds over the saddle branch of an isoreflux pinch point curve. We show how this method can be used to select reactive stages and distribute reaction over a column section profile to meet certain design criteria. We also show how this method can be used to find limits on overall extent reaction within a column or extent reaction on a single stage.     

注塑冷却的数值模拟

以注塑制品的温度变化为对象,考虑了注塑制品出模后的冷却过程。系统地对注塑模具的冷却过程以及制品在注塑模具内和出模后的冷却过程进行集成分析。建立了冷却过程的数学模型,并采用边界元法和有限差分法求解成型过程中模具的温度分布和制品在模具内和出模后的温度分布。