A nomograph for the estimation of the field performance of active night viewing systems

A nomographic method for the estimation of the field performance of active night viewing systems is described. The nomograph is based on a set of relationships which relate the field performance with system parameters that can be measured in the laboratory. The usefulness of the method is illustrated with the help of a practical active night viewing system.     

A method for calculating the wedge spacing of a Fizeau wavelength meter

The wedge spacing of a Fizeau wavelength meter is an important parameter in the conversion of fringe patterns into wavelengths of interfering light. In this paper, computation formulae are derived for calculating the wedge spacing of a Fizeau wavelength meter. The calculated accuracy, which is of the order of 0.1 μm, is discussed. The main advantage of this method is that it calculates an accurate value of the wedge spacing using an estimated value of the spacing and two known wavelengths.     

General implementation of the ERETIC method for pulsed field gradient probe heads

A capacitive coupling between a secondary radiofrequency (rf) channel and the gradient coil of a standard commercially available high resolution NMR spectrometer and probe head is described and used to introduce a low level exponentially damped rf signal near the frequency of the primary rf channel to serve as an external concentration standard, in analogy to the so-called ERETIC™ method. The stability of this inexpensive and simple to implement method, here referred to as the Pulse Into the Gradient (PIG) approach, is superb over a 14-h period and both gradient tailored water suppression and one-dimensional imaging applications are provided. Since the low level signal is introduced via the pulsed field gradient coil, the coupling is identical to that for a free induction signal and thus the method proves to be immune (within 5%) to sample ionic strength effects up to the 2 M NaCl solutions explored here.     

简正模型势函数法计算C2v三原子分子力场

采用简亚模型势函数方法,在ａｂ ｉｎｉｔｉｏ水平上计算了Ｈ２Ｏ和Ｈ２Ｓ的分子内价值标和简正内坐标的谐性力学数矩阵对角工根据这两个坐丝毫宰的关系导出了谐性力常数矩阵的其它对角和非对角元。由于避免了三格点的ａｂ ｉｎｉｔｉｏｎ计算拟合,因此计算量较少。由此计算出的分子谐振动频率与实验 令人满意的。还在简正内坐标的简单价力场近似下,计算了力常数和谐振频率。     

A novel compensation method for the measurement of radius of curvature

A test method for spherical mirrors with super-long radius of curvature that only one compensator is employed to measure the radii of curvature of both concave and convex mirrors is presented. With this testing system, the surface figure and radius of curvature of spherical mirrors can be measured simultaneously. Using the ABCD matrix method, a precise formula for radius of curvature calculation is deduced. Experimental results show that the relative measurement error of this method is less than 4.2×10⁻⁴.     

旋转非导体带电球面磁场的全空间解析解新探

求旋转非导体带电球面的磁场是一个典型的静脉场边值问题，传统的解法之一是用磁标势概念，结合边界条件解拉普拉斯方程，其过程复杂，计算冗长，本文在介绍矢势Ａ、磁化强度Ｍ和电场强度Ｅ三者关系的基础上，用类比的方法，巧妙简捷地给出了问题的全空间解析解，并进行了有意义的讨论。     

Implementation of the direct demodulation method for natural gamma ray spectral logging

Spectrum analysis of natural gamma ray spectral logging （SGR） data is a critical part of surface informa- tion processing systems. Due to the low resolution, which is an inherent weakness of SGR, and the low signal-to-noise ratio problem of logging measurements, SGR is usually treated with a low confidence level. The Direct Demodulation （DD） method is an advanced technique to solve modulation equations interactively under physical constraints. It has higher sensitivity and spatial resolution than the traditional methods and can effectively suppress the logging noise. Based on standard count rate spectral data obtained from the China Offshore Oil Logging Company SGR Calibration Facility, this paper presents the application of the DD method to gamma-ray logging. The results are compared with four traditional algorithmic methods, showing that the DD method is a credible choice, with higher sensitivity and higher spatial resolution in gamma-ray log interpretation. The Point-Spread-Function of the Shengli Oil Logging Company＇s natural gamma ray spectroscopy instrument is obtained for the first time. The quantities of various radionuclides in their calibration pits are also obtained. The DD method was applied successfully to gamma-ray logging, offering a new option for SGR logging algorithm selection.     

Implementation of the direct demodulation method for natural gamma ray spectral logging

Spectrum analysis of natural gamma ray spectral logging (SGR) data is a critical part of surface information processing systems. Due to the low resolution, which is an inherent weakness of SGR, and the low signal-to-noise ratio problem of logging measurements, SGR is usually treated with a low confidence level. The Direct Demodulation (DD) method is an advanced technique to solve modulation equations interactively under physical constraints. It has higher sensitivity and spatial resolution than the traditional methods and can effectively suppress the logging noise. Based on standard count rate spectral data obtained from the China Offshore Oil Logging Company SGR Calibration Facility, this paper presents the application of the DD method to gamma-ray logging. The results are compared with four traditional algorithmic methods, showing that the DD method is a credible choice, with higher sensitivity and higher spatial resolution in gamma-ray log interpretation. The Point-Spread-Function of the Shengli Oil Logging Company's natural gamma ray spectroscopy instrument is obtained for the first time. The quantities of various radionuclides in their calibration pits are also obtained. The DD method was applied successfully to gamma-ray logging, offering a new option for SGR logging algorithm selection.     

基于分布式超声无损检测方法的零件内部缺陷检测

超声检测广泛应用于工业检测,比如超声相控阵检测法和超声A扫应用于零件内部缺陷检测。然而,这些方法可以检测出缺陷位置却很难精确地检测缺陷尺寸,缺陷定量成了急需解决并且很有意义的问题。本文提出了一种分布式超声无损检测方法,将超声探头均匀布置在检测表面,每一个超声探头可以同时发射和接收超声信号,通过对接收到的信号进行处理来重构缺陷轮廓。基于分布式超声无损检测方法,重构零件的人造缺陷并建立相应的声学仿真模型。通过多项式拟合法和聚类法分别处理实验和仿真所获得的数据并重构缺陷轮廓。实验结果和仿真结果显示重构的椭圆形缺陷和正方形缺陷具有一定的精度。结果表明分布式超声无损检测方法有潜在的应用价值和理论意义。     

On the rate of convergence of the Legendre spectral collocation method for multi-dimensional nonlinear Volterra-Fredholm integral equations

While the approximate solutions of one-dimensional nonlinear Volterra-Fredholm integral equations with smooth kermels are now well understood,no systematic studies of the numerical solutions of their multi-dimensional counterparts exist.In this paper,we provide an efficient numerical approach for the multi-dimensional nonlinear Volterra-Fredholm integral equations based on the multi-variate Legendre-collocation approach.Spectral collocation methods for multi-dimensional nonlinear integral equations are known to cause major difficulties from a convergence analysis point of view.Consequently,rigorous error estimates are provided in the weighted Sobolev space showing the exponential decay of the numerical errors.The existence and uniqueness of the numerical solution are established.Numerical experiments are provided to support the theoretical convergence analysis.The results indicate that our spectral collocation method is more flexible with better accuracy than the existing ones.     

无限长均匀带电直线组电场分布的复势解法

给出无限长均匀带电直线的复势,接着讨论平行直线排列与平行环形排列两种情况下,无限长均匀带电直线组的复势与电场,并由此得出相应的电场线与等势线方程.     

求解线电荷与导体圆柱形成电场的新方法

用保角变换方法,将导体圆柱外区域映射为单位圆内区域,线电荷位置映射为单位圆圆心,从而直接写出导体圆柱外电势,并对结果进行详细讨论,还利用软件画出等势线簇图形.     

一种基于规则带特征的图案布匹检测新方法

为了对具有纹理图案的纺织品缺陷进行准确有效的检测,提出了一种新的基于规则带( regular band,RB)特征的纹理图案布匹瑕疵检测方法.首先利用规则带分析提取图像的各子带纹理特征;然后对各子带图像特征求梯度,并通过融合各子带梯度来获得纹理梯度,使其在纹理梯度中能有效地突出纹理区域的边界;最后在此基础上,结合分水岭...     

一种基于拉曼光谱的石油产品快速分类方法

提出了一种基于拉曼光谱的石油产品快速分类方法.首先,利用经过谱图预处理的石油产品训练样本拉曼谱图构建模型知识库,计算各类别的特征拉曼谱图和类内阈值;其次,将石油产品测试样本的拉曼谱图经过相同的预处理,再计算其与各类别特征拉曼谱图的线性相关系数,若最大相关系数大于或等于最大相关系数对应类别的类内阈值,则该样本属于此类别....     

A new method for compensation and rematch of cavity failure in the C-ADS linac

For proton linear accelerators used in applications such as accelerator-driven systems,due to the nature of the operation,it is essential for the beam failure rate to be several orders of magnitude lower than usual performance of similar accelerators.A fault-tolerant mechanism should be mandatorily imposed in order to maintain short recovery time,high uptime and extremely low frequency of beam loss.This paper proposes an innovative and challenging way for compensation and rematch of cavity failure using fast electronic devices and Field Programmable Gate Arrays(FPGAs)instead of embedded computers to complete the computation of beam dynamics.A method of building an equivalent model for the FPGA,with optimization using a genetic algorithm,is shown.Results based on the model and algorithm are compared with TRACEWIN simulation to show the precision and correctness of the mechanism.     

An effective potential method for the calculation of hydrogen molecule ion energy in a strong magnetic field

Using the adiabatic approximation and adiabatic variational approximation with an effective potential, the total energies and the equilibrium internuclear separations of H₂⁺ ion in states σ_g, π_u, δ_g, φ_u, γ_g, η_u in strong magnetic fields have been calculated. Our results reproduced those obtained by Vincke and Baye (Vincke M and Baye D 1985 J. Phys. B: At. Mol. Phys. 18 167), which are considered the most reliable. We found a basic function with better convergence than the Landau functions.     

An efficient approach for the implementation of the SNB based correlated-k method and its evaluation

The current implementation of the SNB based correlated-k method consumes a significant portion of the total cpu time on the on-line inversion of the cumulative distribution function. An approach was developed to pre-calculate the absorption coefficients of real gases from the inversion procedure. This approach results in significant improvement in the efficiency of the SNB based correlated-k method with slight loss in accuracy. This approach was evaluated against other implementation approaches of the SNB based correlated-k method in several non-isothermal and/or inhomogeneous problems.     

导体旋转椭球电学量的一种计算方法

用一种新方法，计算了孤立导体旋转椭球的面电荷密度、电容、电势和电场强度，并得出相应的解析表达式。