一步法设计单色仪凹面全息光栅

凹面全息光栅是光谱分析仪器的核心器件之一,其成像质量直接决定了光谱分析仪器的分辨本领。利用光程函数理论设计凹面全息光栅是一个繁琐的求解非线性方程组的过程,该过程分两步进行,每步需要求解四个非线性方程。分两步求解不但过程麻烦,还不可避免地引入了取舍误差,降低了最优参数的精度。为了解决该问题,本文提出了一种设计单色仪凹面全息光栅的新方法——一步法,该方法不但可以简化求解过程、降低最优参数的误差,还可以方便地控制整体像差的变化趋势。采用有较强全局搜索能力的遗传算法求解该方法中非线性方程的极值问题,并与传统的方法对比验证了该方法的可行性和正确性,结果表明,一步法不但在方法上比两步法简便,其设计结果还优于两步法。     

泡泡布点方法及其并行性

针对无网格和有限元方法中的布点需求,借鉴分子动力学方法和泡泡网格化方法的思想和处理技术,提出一种单纯的布点方法--泡泡布点方法.将区域内的点看作有相互作用力的泡泡,通过动态模拟得到高质量的点集,模拟中不需要网格连接.算例显示,生成的均匀点集和非均匀点集都具有很好的结构和渐进性,并对复杂区域具有很好的适应性.同时由于相互作用力的局部性,该布点方法类似于短程作用的分子动力学模拟,拥有潜在的并行性.通过初步的并行算例,验证了其并行化的可行性.     

基于椭圆形光强分布光栅投影的三维面形测量方法

基于椭圆形光强分布光栅投影测量物体三维面形的方法,将椭圆形光强分布光栅投影到被测物体表面,用摄像机获取变形条纹图,通过系统参量和条纹图携带的相位信息求解出物体的三维面形.推导出通过椭圆形光强分布光栅条纹求解相位的计算公式并对提出方法作了计算机仿真.实验结果表明该方法可以比较准确地测量物体的三维面形,在噪音较大的情况下测量结果仍具有较高准确度.     

利用3—5MeV γ射线测量核裂变数的可行性研究

提出了利用3—5MeV能区γ射线测量核裂变数的方法, 并且用浓缩铀样品堆照实验验证了该方法的可行性. 结果表明: 该方法可以应用于测量核裂变数, 依据通用方法的结果作为参考标准, 该方法测量不确定度小于16%.     

正则化参数求解方法研究

针对BP神经网络算法训练过程中出现的过拟合问题,提出了利用一阶原点矩,二阶原点矩,方差和极大似然估计概念的推广来计算L2正则化中正则化参数 值的方法。该方法通过对算法数据集[X,Y]中的X矩阵进行运算得到的四个 值,BP神经网络算法训练时通常采用的是贝叶斯正则化方法,贝叶斯正则化方法存在着对先验分布和数据分布依赖等问题,而利用上述概念的推广计算的参数代入L2正则化的方法简便没有应用条件限制。在BP神经网络手写数字识别的实验中,将该方法与贝叶斯正则化方法应用到实验中后的算法识别结果进行比较,正确率提高了1.14-1.50个百分点。因而计算得到的 值应用到L2正则化方法与贝叶斯正则化方法相比更能使得BP神经网络算法的泛化能力强,证明了该算法的有效性。     

基于椭圆形光强分布光栅投影的三维面形测量方法

基于椭圆形光强分布光栅投影测量物体三维面形的方法,将椭圆形光强分布光栅投影到被测物体表面,用摄像机获取变形条纹图,通过系统参量和条纹图携带的相位信息求解出物体的三维面形.推导出通过椭圆形光强分布光栅条纹求解相位的计算公式并对提出方法作了计算机仿真.实验结果表明该方法可以比较准确地测量物体的三维面形,在噪音较大的情况下测量结果仍具有较高准确度.     

New and more general traveling wave solutions for nonlinear Schrödinger equation

An extended Fan sub-equation method is used to seek some new and more general traveling wave solutions of nonlinear Schrödinger equation (NLSE). The important fact of this method is to take the full advantage of clear relationship among general elliptic equation involving five parameters and other existing sub-equations involving three parameters. It is preferable to use this method to solve NLSE because this method gives us all the solutions obtained previously by the application of at least four methods (the method of using Riccati equation, or auxiliary ordinary differential equation method, or first kind elliptic equation or the generalized Riccati equation as mapping equation) in a unified manner. So it is shown that this method is concise and its applications are promising.     

Control and synchronization of second Julia sets

A visualization of Julia sets of the complex Henon map system with two complex variables is introduced in this paper.With this method,the optimal control function method is introduced to this system and the control and synchronization of its Julia sets are achieved.Control and synchronization of generalized Julia sets are also achieved with this optimal control method.The simulations illustrate the efficacy of this method.     

Data point selection for weighted least square fitting of cavity decay time constant

For the accurate extraction of cavity decay time, a selection of data points is supplemented to the weighted least square method. We derive the expected precision, accuracy and computation cost of this improved method, and examine these performances by simulation. By comparing this method with the nonlinear least square fitting(NLSF) method and the linear regression of the sum(LRS) method in derivations and simulations, we find that this method can achieve the same or even better precision, comparable accuracy, and lower computation cost. We test this method by experimental decay signals. The results are in agreement with the ones obtained from the nonlinear least square fitting method.     

非平衡磁控溅射系统磁场的半解析法

应用电磁场分析中的一种新方法——半解析法，对一种典型的非平衡磁控溅射系统进行了磁场分析. 结果表明，应用半解析法计算,求解变量少、方法简单，而且计算精度高，该方法相对于等效源法有严密的理论依据，标量位函数的表达式为级数解析式，有利于场强的计算，更有利于优化设计.     

Ultrasonic attenuation estimation in-vivo using the difference ratio correction method.

In recent years, B scanners have been widely used clinically. Obviously, it is of particular importance to use the commercial B scanners to characterize tissue by estimating its ultrasonic attenuation in vivo. However, there are a lot of difficulties in doing so because the output of a B scanner is affected by many unknown factors. In this paper, a time domain method named the difference ratio correction (DRC) method is proposed to estimate the ultrasonic attenuation of tissue in vivo. In this method, three tissue-mimicking phantoms with known acoustical properties were employed to eliminate the instrumentation errors of the B scanner and the measuring system and to correct beam diffraction for correct attenuation estimation. Other advantages of this method are that it is very convenient to apply this method clinically and there is no need to change the inner construction of the B scanner because this method only utilizes the video output. Experimental and clinical results have proved the validity of this method.     

非平衡磁控溅射系统磁场的半解析法

应用电磁场分析中的一种新方法——半解析法,对一种典型的非平衡磁控溅射系统进行了磁场分析. 结果表明,应用半解析法计算,求解变量少、方法简单,而且计算精度高,该方法相对于等效源法有严密的理论依据,标量位函数的表达式为级数解析式,有利于场强的计算,更有利于优化设计. 关键词： 非平衡磁控溅射 半解析法 标量磁位 磁场强度     

利用泽尼克系数求取衍射光栅的分辨本领

光栅分辨本领检测设备的焦距通常达几米甚至十几米,采用直接测量法难度大、成本高,利用衍射波前间接求取光栅分辨本领是解决该问题的有效途径之一。在光栅光谱成像傅里叶变换理论基础上,建立了利用泽尼克多项式拟合系数求解衍射光栅分辨本领的归一化模型,揭示了光栅衍射波前与分辨本领的求取关系,提出了依据泽尼克多项式拟合系数求取衍射光栅分辨本领的新方法。根据该方法实测了一块衍射光栅的分辨本领,并与直接测量法进行对比测试。结果表明该方法误差小于4.42%,降低了分辨本领的测试难度,是衍射光栅分辨本领求取的有效手段,应用于ZYGO干涉仪等仪器中,通过简单的波前测试即可得到定量的衍射光栅分辨本领指标。     

An Improved 3D SPIHT Coding for Hyperspectral Imagery Data Compression

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解线性代数方程组的TCG迭代法

ICCG方法是解线性代数方程组较为理想的方法,但它仅适用于具有正定对称的系数阵。本文介绍的TCG方法便足改造过的ICCG方法,它适用于一般非奇异的非正定对称阵。TCG方法比常用的JLUCG方法,对于非定常问题,可提高效率18%,特别是取用SIP不完全L、U分解作预条件时,可提高效率40%,是计算非正定对称阵较为理想的迭代法之一。本文推导出在消去法不完全L,U分解下的TCG方法,并用数值结果论证出它比ILUCG方法加速收敛的所在。     

一种应用相息图对灰度图像信息进行隐藏的方法

一幅灰度图像的相息图被隐藏于一幅宿主图像中,该相息图是采用基于相息图迭代的双随机相位加密技术得到的.由于采用仅含有位相信息的相息图作为待加密灰度图像信息的载体,因而与隐藏图像同时具有振幅和相位信息的情况相比较,需要隐藏的信息量大大降低,从而可在对宿主图像影响较小的情况下,提高提取信息的质量;并可有效地提高信息提取时的光学效率,并且对二元图像信息的隐藏也同样适用.水印图像的剪切对隐藏信息提取质量的影响也被分析,模拟实验结果证明了所采用方法的有效性. 关键词： 灰度图像 相息图 信息隐藏     

An Improved 3D SPIHT Coding for Hyperspectral Imagery Data Compression

In this paper, an improved 3D SPIHT compression coding method, naming 3D BCSPIHT, based on wavelet zero tree compression coding (EZW), is used to exploit redundancy in 3D hyperspectral imagery data. The experimental results show that this method can obtain the compression ratio 200 for 224 spectral band data without any K-L transformation (KLT) to remove the spectral correlation, and the total compression performance of this method is better than the method of KLT and other two dimensional transformation (such as 2D DCT and 2DWT) to remove the spectral correlation and spatial redundancy. To compare with the total compression ratio of KLT+JPEG method and KLT+BBZTC method, this method reaches 200 folds at the average PSNR of 32.531 dB. This method enhances 2～5 dB in PSNR at same compression ratio to KLT+BBZTC method, and the average compression rate improves above 15 fold.     

基于小波的不均匀光照的校正

给出了一种减小图像中的不均匀光照的方法。利用基于小波的非线性回归来估计降质图像的光照分布,再通过从原图中减去光照分布图达到减小不均匀光照的目的。对此方法和常用的双立方插值法的计算量进行了分析比较,证明此方法计算量小。最后取三幅图像进行了实验验证。     

Charged black rings from inverse scattering

The inverse scattering method of Belinsky and Zakharov is a powerful method to construct solutions of vacuum Einstein equations. In particular, in five dimensions this method has been successfully applied to construct a large variety of black hole solutions. Recent applications of this method to Einstein–Maxwell-dilaton (EMd) theory, for the special case of Kaluza–Klein dilaton coupling, has led to the construction of the most general black ring in this theory. In this contribution, we review the inverse scattering method and its application to the EMd theory. We illustrate the efficiency of these methods with a detailed construction of an electrically charged black ring.     

超导螺线管的冷铁轭优化

介绍了超导螺线管的冷铁轭优化设计方法, 即采用均匀设计结合有限元软件Opera作为试验手段进行研究。 对该方法进行了举例说明, 并得到物理量与参数之间的关系式, 并验证了关系式的精度, 以此证明此优化方法的可行性。 A method of studying the effect about cold yoke on the superconducting solenoid is introduced in this paper. In this method the uniform design table was used to arrange experiments. And then these experiments were executed by OPERA software package. Finally, the results were analyzed by the Stepwise Regression Analysis. An example according to the method is described and the reliability of this method is also proved.