一种基于VG模型的非饱和土渗流参数反演方法

针对非饱和土渗流分析中土水特征曲线和渗透性函数难以获取的问题,本文提出一种基于van Genuchten（VG）模型的非饱和土渗流参数反演方法,非饱和渗流控制方程采用Richards方程,通过计算数值模拟值与实测各观测点不同时刻孔隙水压力或重量（体积）含水量之误差平方和,寻求最优VG模型参数组合使得误差平方和最小.编制了二维非饱和渗流参数反演程序（BAKSEEP）,并通过算例展示了该程序良好的适用性和稳定性.     

考虑约束条件的油藏生产优化

油藏生产优化是把对油藏生产体系的控制描述成一个最优化问题,通过求解最优化问题得到油藏生产的最优控制。首先利用数值方法得到目标函数的近似梯度,然后利用投影梯度方法将近似梯度投影到可行方向上,在可行方向上进行线性搜索,得到满足约束条件的最优解。通过计算案例,对两种近似梯度方法的优化效果与利用有限差分法得到的梯度的优化效果进行对比。优化得到的调控方案可以满足约束要求,并且能够有效改善注水开发效果,大幅度增加油田的经济效益。     

直升机桨叶图像中圆形标记点圆心检测及修正方法

视觉测量直升机高速旋转桨叶形变常采用基于圆形标记点的测量方法,但该方法中圆形标记点具有低曝光、小目标和投影不对称等特点,极易产生标记点漏检和圆心坐标误差的问题。为减小漏检、修正圆心坐标误差,提出了一种直升机桨叶图像中圆形标记点圆心检测及修正方法。首先,提取图像中局部极值中心的像素坐标,并依据阵列排布结构滤除干扰,获得所有圆形标记点极值中心的像素坐标;其次,以各极值中心的像素坐标为圆心,与相邻极值的最小距离为直径,建立圆形ROI （region of interest）区域,在ROI区域内并行分水岭变换和最小二乘法圆拟合得到圆心;再次,采用透视变换建立该图像与垂直相机光轴的同相位桨叶图像（正面图像）的投影映射关系,再采用LM （levenberg-marquardt）优化求解投影映射矩阵;最后,将该图像转换为正面图像进行圆心检测,再将该圆心坐标逆变换得到精确圆心坐标。实验结果表明,本文检测方法准确率和精度分别达98.89%和0.191 mm,已应用于直升机高速旋转桨叶运动轨迹和形变的高精度视觉测量。     

D~4线中心投影的计算公式及D~4空间的平移变换和旋转变换

本文推导出D~4线中心投影的计算公式,并且提出D~4空间的平移变换矩阵和绕各坐标面旋转的变换矩阵。为用计算机绘制D~4线中心投影图提供了必要的数学模型。     

Low side lobe pattern synthesis using projection method with genetic algorithm for truncated cone conformal phased arrays

A hybrid method for synthesizing antenna＇s three dimensional （3D） pattern is proposed to obtain the low sidelobe feature of truncated cone conformal phased arrays. In this method, the elements of truncated cone conformal phased arrays are projected to the tangent plane in one generatrix of the truncated cone. Then two dimensional （2D） Chebyshev amplitude distribution optimization is respectively used in two mutual vertical directions of the tangent plane. According to the location of the elements, the excitation current amplitude distribution of each element on the conformal structure is derived reversely, then the excitation current amplitude is further optimized by using the genetic algorithm （GA）. A truncated cone problem with 8x8 elements on it, and a 3D pattern desired side lobe level （SLL） up to 35 dB, is studied. By using the hybrid method, the optimal goal is accomplished with acceptable CPU time, which indicates that this hybrid method for the low sidelobe synthesis is feasible.     

基于ICSA-MWF的多级投影干扰抑制方法

为降低子空间投影方法的计算量,提出基于迭代相关相减结构多级维纳滤波器(iterative correlation subtraction algorithm-multistage Wiener filter,ICSA-MWF)的无源雷达多级投影干扰抑制方法。该方法根据回波通道内多径干扰的特点,首先提出一种新的初始化方法将ICSA-MWF应用于距离-多普勒频移域内,依据其前向投影特性即可利用多级小维数投影取代子空间投影方法,接着又提出一种简便的滤波器级数选取方法,然后利用迭代算法实现后向误差综合,最终输出误差即为多径干扰抑制后的信号。该方法干扰抑制性能好、数值稳健且计算量低于子空间投影方法。仿真结果表明该方法的有效性。     

基于非线性时间序列的胎儿心电信号提取算法

研究了基于非线性时间序列的状态空间投影算法提取胎儿心电信号.母亲、胎儿心电信号以及噪声在状态空间中的吸引子表现形式不同,通过选择不同的邻域半径,将混合信号在某一局部范围内投影,就可以分离出所要监测的胎儿心电信号.对模拟的和实际测量的孕妇腹部混合信号仿真,都得到了较好的效果.相对于其它胎儿心电信号提取算法,该方法只需要一路导联信号就可以分离出胎儿心电信号,方便了医生对胎儿的监测.该算法对其它微弱特征信号提取具有借鉴作用.     

Study on Main Component Projection Evaluation of Regional Science and Technology Development

With the further aggravation of international competition, the science ＆： technology development has already become the most important factor that it influences a country＇s competitiveness. This paper structures the evaluation index system of regional science and technology development. It also utilizes AHP and main component projection to analyze the current science and technology development situations of eight areas in our country and receive the final result.     

Wavelet-Based Mixed-Resolution Coding Approach Incorporating with SPT for the Stereo Image

ELECTRONICS TECHNOLOGY1. INTroDUCTIONThe human brain can process subtle differences between the images that are presented to the left and right eyesto perceive a three-dimensional (3-D) outside world. This ability is called stereo vision. A stereoscopic systemmay be used to stimulate the stereo vision ability edificially. A stereo pair, a pair of images of the same sceneacquired from two different perspectives, is presented to the observers so that the right image is seen by theri…     

一种具有动态最优学习率的BP算法

提出具有动态最优学习率的BP算法,动态最优学习率是通过迭代的方式得到的,这种算法具有运算简单,收敛速度快,精度高特点。仿真结果说明此算法是有效的。