超分辨率图像重构技术在航天器相对位置测量中的应用

以两颗航天器间相对位置参数测量为研究对象,确定了基于单目计算机视觉及目标特征的测量方案,提出了基于超分辩率图像重构技术的航天器间相对位置的高精度测量方法。分析讨论了图像传感器的观察模型、图像传感器及光学测量系统的点扩散函数、配准方法、重构原理及方法。利用地面试验验证了该方法的正确性。试验结果表明:该方法与基于单帧图像及目标特征的方法、基于插值的方法相比较,在测量精度及稳定性等方面都有了较大的提高;与基于单帧图像及目标特征的方法相结合,不仅可以保证在不同作用距离上相对位置的高精度测量,而且具有较高的测量稳定性和可靠性。     

Method for the determination of dopant concentrations of luminescent ions

We report on a new method for determining dopant ion concentrations in laser materials. This method is based on optical absorption spectroscopy. In contrast to other methods used to measure the dopant concentration that are based on absorption measurements, this method does not require the knowledge of the absorption cross sections. An advantage of this method compared to the micro probe analysis is that only concentrations of dopant ions of a certain valency, which are luminescent, are detected. The method is sensitive especially for small doping concentrations of ions with high absorption cross sections. Another application of this method is the determination of the ratio between luminescent dopant ions to the total number of dopant ions in the case that not all dopant ions are on crystal sites that allow for optical transitions.     

光纤水听器相位生成载波解调非线性因素的抑制方法

为了消除非线性因素对相位生成载波解调结果的干扰,降低相位生成载波解调过程中低通滤波器的频响特性对相位生成载波解调结果的影响,该文提出了一种基于扩展卡尔曼滤波椭圆参数估计的相位生成载波微分交叉相乘解调方法。该方法在综合考虑各种非线性因素对相位生成载波微分交叉相乘解调结果的影响的基础上,对传统的相位生成载波微分交叉相乘解调过程进行了改进。经过计算机仿真和实验验证,该文所提出的扩展卡尔曼滤波微分交叉相乘方法能够有效地抑制非线性因素对相位生成载波解调结果的干扰,相比传统的相位生成载波微分交叉相乘方法,其信噪比提高了35.0 d B,总谐波失真降低了30.7 dB,信噪谐波比提高了31.0 dB,且扩展卡尔曼滤波微分交叉相乘方法受解调过程中低通滤波器频响特性的影响较小。     

A stiffness equation transfer method for natural frequencies of structures

A stiffness equation transfer method is proposed for obtaining vibration frequencies of structures. This method is an extension of the finite element-transfer matrix (FE-TM) method. In the present method, the transfer of state vectors from left to right in the ordinary FE-TM method is changed into the transfer of stiffness equations of every section from left to right. This method reduces the propagation of round-off errors produced in the ordinary transfer matrix method. Furthermore, the drawback that the number of degrees of freedom on the left boundary must be the same as that on the right boundary in the ordinary FE-TM method, is now avoided. Besides, this method finds out the values of the frequency by Newton-Raphson iteration method, so no plotting of the value of the determinant versus assumed frequency is necessary. An IFETM—W program based on this method for use on an IBM PC586 microcomputer is developed. Finally, numerical examples are presented to demonstrate the accuracy as well as the potential of the proposed method for free vibration analysis of structures.     

胶带粘面手印显现的实验

为提高胶带粘面上汗潜手印的显出率。通过实验,对胶粘面上汗潜手印剥离和显出做了多种方法的研究,显现包括碳素墨水法、龙胆紫溶液法、"502"熏显后加染法、小颗粒悬浮液法,比较研究每种方法的显现效果及适用情况。胶粘面上手印的最佳显现方法是碳素墨水法。     

蒙特卡洛法计算空间辐射制冷器耦合因子的研究

为了研究蒙特卡洛法计算空间辐射制冷器耦合因子 ,文中通过计算平面 W型空间辐射制冷器二级冷块耦合因子 ,介绍了计算流程 ,并以积分分布概率为基础研究了相关核心算法。计算结果表明 ,采用以积分分布概率为基础的核心算法 ,蒙特卡洛法替代传统耦合因子计算方法 ,具有计算结果精度高的优点 ,达到了实用要求     

内外流一体化飞行器动导数数值预测

研究内外流一体化飞行器通流模型和带整流罩模型，考核强迫振荡法和自激振荡法在内外流一体化飞行器上的适用性，详细分析时间步长、振荡频率等参数对动导数的影响.研究发现，强迫振荡法在内外流一体化飞行器动导数预测中具有较好的适用性，但与常规的纯外流飞行器相比，时间步长的选取、计算时间及振荡频率等参数的选择都有较大不同.对常规的纯外流飞行器，自由振荡法的预测结果与强迫振荡法符合较好，但对内外流一体化飞行器外形，两者相差50%以上，差异的来源及产生的机理尚需开展深入的研究.     

On the synchronization of a class of chaotic systems based on backstepping method

This Letter focuses on the synchronization problem of a class of chaotic systems. A synchronization method is presented based on Lyapunov method and backstepping method. Finally some typical numerical examples are given to show the effectiveness of the theoretical results.     

气轨导轨阻尼常数测量的研究

对用平均值代替瞬时值就可以用动力学的方法测定气垫导轨上的阻尼常数进行了理论分析，并指出该方法所得到的测量表达式与运动学测量方法表达式是等价的。     

Fresnel diffraction method with object wave rotation for numerical reconstruction of digital hologram on tilted plane

We present a new method for numerically reconstructing holography image on tilted planes within the Fresnel domain. The method is based on the Fresnel diffraction algorithm and object wave rotation transform. By suitable rotation the object wave on recording plane and once fast Fourier transformation this method can be implemented. The proposed method can render the real image of the hologram not only on parallel plane but also on the tilted. Experimental results are presented to demonstrate the method for a single axis rotation.     

非制冷热像观瞄系统动态目标的智能检测

为了适应实时性的要求,在目标检测及定位时对处理方法的简洁性提出了很高的要求。基于热像观瞄系统,根据观瞄的目的,介绍了一种具有一定大小的目标检测方法。根据差分图像像素特性,提出了自适应选取阈值的新方法,对目标像素的亮度和分布密度进行精确定位。这种方法充分考虑了像素的自身属性信息,便于硬件的实时处理。该方法可以达到较高的检测率。     

Correlation method of measuring the frequency shifts of the sound field maxima caused by perturbations of the oceanic medium

The correlation method of measuring the frequency shifts of the sound field maxima caused by the nonstationary oceanic medium is considered. The method is based on tracing the frequency shift of the maximum that is observed in the cross-correlation function of signal spectra received at different instants of time. The relation between the correlation method and the method based on measuring the frequency shifts of the maxima observed in the interference pattern of the source is analyzed. The sensitivity of the correlation method is estimated.     

Analysis of distribution of partially polarized light

A new method for characterization of the distribution of the partially polarized light is described. Analysis of distribution is based on three dimensional radial distribution function. The radial distribution function is useful method of determining type of the distribution of partially polarized light. For uniformity analysis of the distribution method which is based on calculation of the correlation coefficient is presented.     

基于改进格林元的压裂水平井动态分析方法

以建立高效的动态分析方法为出发点,以边单元作为求解点,改进传统的格林元方法,减少未知数和求解矩阵维度;并提出基于改进格林元的加密网格加密方法,保证考虑复杂裂缝网络的压裂水平井动态模拟的早期精度.退化模型与半解析解、数值模拟结果进行对比,验证本文基于加密网格的改进格林元方法的准确性和动态分析的高效性.最后进行动态响应的敏感性分析,结果表明：①格林元方法是一种高精度的动态模拟方法,将求解节点设置在网格的边上可以提高压裂水平井动态模拟的速度;②改进格林元方法的加密基于叠加原理,不需要通过插值近似,其求解精度高.在相同加密网格条件下,基于本文改进格林元方法的加密效果比有限差分加密效果更佳;③复杂裂缝导流能力、改造区渗透率提高倍数、改造区大小等参数对压裂水平井动态特征影响较大,在动态分析和参数反演时,应着重考虑这些因素的影响.     

凸透镜焦距测量方法的探索简

凸透镜焦距的测量方法和不确定度评价已经有很多研究,本文着重研究测量方法,提出了应用实物成虚像、虚物成实像方法来测量凸透镜的焦距,并与实物成实像方法进行比较和分析。本文的实验研究拓展了透镜焦距测量的方法,同时更加深入研究了透镜成像的规律,开拓了实验思路。     

横向各向同性地层快速各向异性反演方法

斯通利波的频散特性常用于反演横向各向同性地层的各向异性。该文重点对斯通利波频散曲线随井孔和地层弹性模量相关参数的变化规律进行了探讨,提出了频散曲线的快速插值计算方法,经过误差分析验证了插值频散计算的可行性。据此提出了通过对参数大间隔取值建立理论频散数值表,插值计算不同各向异性参数的频散曲线,对比波形频散快速反演横向各向同性地层各向异性的方法。基于实轴积分法计算的横向各向同性地层井孔声场分别进行了插值频散快速反演和传统方法反演,对比结果证实了该文提出的快速反演方法的准确高效性,并且对数据加噪后验证了快速反演方法的抗噪性。     

Computation of localized modes in a defect-containing photonic crystal by the method of periodic continuation of solution

The applicability of the method of periodic continuation of solution for computing the spatial distribution of an electromagnetic field in a photonic crystal with a defect is analyzed. The accuracy of the method is estimated. The crystal eigenmodes are classified, and the method is shown to be applicable only for states localized on the defect. The results of numerical calculations based on expansion of electromagnetic field in plane waves are presented, and the details of the expansion method are described.     

Resolution-enhanced Fourier transform method for the estimation of multiple phases in interferometry

A phase shifting method based on high-resolution frequency estimation and Fourier transform technique is introduced. This method, also referred to as the eigenvector method, draws on the complementary strengths of both these methods. The salient feature of the method lies in its ability to handle nonsinusoidal wave-forms, multiple piezoelectric transducers, and arbitrary phase steps in an optical configuration. The method does not need the addition of carrier fringes to separate the spectral contents in the intensity fringes. The proposed concept thus overcomes the limitations of methods based on Fourier transform techniques. The robustness of the proposed method is studied in the presence of noise.     

Use of phase transparency to reconstruct the phase structure of a field

A method for reconstructing an optical field is developed. It is based on special shaping of the structure of the information on the amplitude and phase pattern of the recording field. The amplitude information is recorded by a standard method, such as photography. The phase information is recorded after visualization on a phase-sensitive material. The field structure is reconstructed by passing a quasimonochromatic space-coherent plane wave through the obtained transparencies. The method was implemented experimentally for phase-modulated fields with the phase information visualized by the Zernike method.Translated from FIAN Preprint No. 227, Lebedev Physics Institute, Moscow, 1988.     

Reconstruction of the Point-Spread Function of the Human Eye Using a New Phase-Retrieval Algorithm

The double-pass method is thought to obtain the point spread function (PSF) in human eyes based on two techniques: the symmetric double-pass method using the same pupil size and the asymmetric double-pass method using a different pupil size. The symmetric double-pass method provides autocorrelation of the retinal PSF and, thus, the modulation transfer function. The asymmetric double-pass method provides low-frequency partial-phase information and the partial phase-retrieval algorithm is applied to obtain the complete-phase information, and to estimate the PSF. The partial phase-retrieval algorithm is based on the iteration method proposed by Fineup and Kowalczyk and requires a lengthy computation. In this study, we propose a new high-speed phase-retrieval algorithm based on the property that the real and imaginary parts of optical transfer functions (OTFs) continuously change in value.