高压交流输电线路故障检修技术研究

对高压交流输电线路故障检修技术进行研究,可以提高电力质量,减少因线路故障产生的一系列人财有损情况的发生。当前方法将短期的输电线路检修当作单重不确定性的优化问题,对其进行建模以及求解。而在现场运行过程中,架空线路可靠性指标不能准确表达线路故障发生的可能性,其理论基础相对薄弱,仅考虑了单重不确定性的问题,无法对高压交流输电线路进行高精度地检修。为此,提出一种基于层次分析的高压交流输电线路故障检修方法。该方法先将高压交流输电线路故障划分为：单相接地故障、高压交流输电线路短路故障、高压交流输电线路导线断路故障。然后利用多个电流测量点,通过FFT程序对电流故障分量相位进行求解,根据比较相邻测点相位差判别故障区域,最后利用图论实现高压交流输电线路故障检修时间控制函数,以及线路故障检修经济控制目标函数的制定,与分类和定位结果结合完成高压交流输电线路故障的检修。实验结果证明,所提方法可以有效地对高压交流输电线路故障进行检修,具有一定的利用价值。     

二维磁振子晶体中线缺陷模的性质及其应用

在超原胞近似下, 利用平面波展开法数值计算了含线缺陷结构的二维磁振子晶体带结构及缺陷模的磁化强度场分布. 研究结果表明, 线缺陷结构的引入会在禁带中产生一个小范围的通带, 即产生线缺陷模. 该模式的存在可使自旋波沿着线缺陷结构的方向传播, 利用此性质含线缺陷结构的二维磁振子晶体材料可作为自旋波导波器件的制作材料. 关键词： 磁振子晶体 线缺陷 波导     

An extended flow-based difference-of-Gaussians method of line drawing for polyhedral image

This paper presents a non-photorealistic rendering technique for stylizing a photograph in the line drawing style. The flow-based difference-of-Gaussians (FDoG) filter constructs lines of style and quality, which usually used to extract the line drawing for some images. In this paper, we inspired by the polyhedral image feature (the line of which are mostly straight line), proposed the method based on the standard FDoG to extract the line drawing of polyhedral image. First, we detect line by fast line segment detector with a false detection control (LSD); then construct a smooth and coherent edge tangent flow (ETF) of the polyhedral images. On the basis of the ETF, the anisotropic FDOG is used to render the lines. This scheme gives clear line features for polyhedral images without much noise, which is also simple and easy to implement, and is robust. The experimental results prove that our algorithm is more efficient than the traditional FDOG approaches in render line drawing for polyhedral image.     

Blumlein双极脉冲形成线

 为了提高超宽带系统的辐射因子,对超宽带脉冲整形技术进行了深入研究,介绍了采用Blumlein线产生双极脉冲的高功率双极脉冲产生技术。对采用Blumlein线产生双极脉冲的原理进行了讨论,通过数值模拟分析了影响双极脉冲形成的主要因素。设计了一套Blumlein高功率双极脉冲形成线,在800 kV脉冲源上开展了高压实验研究,分析了开关及形成线长度对形双极脉冲的影响。在输入单极脉冲电压为652.0 kV、脉宽为2.1 ns的情况下,Blumlein双极脉冲形成线可以产生负峰电压为571.9 kV、正峰电压为550.4 kV、半周期为740 ps的双极脉冲,峰-峰值电压是入射脉冲峰值电压的1.72倍,辐射因子为4.54 MV。     

介观耗散传输线的量子化

从耗散传输线的经典运动方程出发,将传输线中的单模信号进行量子化,研究了传输线在激发相干态下的量子效应.结果表明,传输线的量子涨落不仅与电路参数和电路的状态有关,还与传输线的位置有关. 关键词： 介观传输线 耗散 单模 激发相干态     

Studies on the spectral width,monochromatic degree and spectral resolving power of prism monochromator

The angular width and geometric line width in the spectral plane for the output incoherent imaging spectral line are discussed respectively on the basis of structure of prism monochromator, the relationship between the spectral width and line width of output incoherent imaging spectral line in the spectral plane is presented. The expression of monochromatic degree of output light in the exit slit plane is presented. The spectral resolving power of incoherent imaging spectral line and coherent imaging spectral line of the diffractive waves are discussed respectively, and the expressions of the spectral resolving power are presented respectively.     

基于拖曳倾斜线列阵的海底反射损失提取方法

在浅海环境中,海底声学参数对水下声场的精确预报十分重要.现有的海底声学参数反演方法大多数是采用固定垂直阵进行的,其缺点是不能实施大面积、高分辨的走航式反演.在已提出的垂直阵海底反射损失反演方法的基础上,研究了基于三种线列阵阵形的海底反射损失提取方法及其特点,提出了基于拖曳倾斜线列阵与三个声源组合的走航式海底参数快速获取方法,并对该方法进行了误差分析.研究结果表明：覆盖同样的掠射角范围,垂直线列阵需与多个距离的声源组合,拖曳水平线列阵只需一个声源组合但需要采用较大的物理孔径,拖曳倾斜线列阵综合了垂直阵和水平 关键词： 水下声场预报 海底声学参数 海底反射损失 拖曳倾斜线列阵     

YBa2Cu3O7-δ外延薄膜的不可逆线与磁通玻璃线

在0—10T磁场范围内,系统地测量了YBa₂Cu₃O_7-δ外延薄膜处于磁场平行和垂直膜面两种情况下的R-T曲线和I-V曲线, 并对该样品的不可逆线和磁通玻璃线作了直接的比较.结果表明, 由不同约化电阻率判据给出的不可逆线和磁通玻璃线遵守相同的H∝(T(0)-T(H))ⁿ 关系.对于不可逆线, n=3/2,对于磁通玻璃线,n=4/3.不可逆线的位置不仅与判据有关而且与测量电流密度也有关,磁通玻璃线位于不可逆线的下方.探讨 关键词：     

利用Doppler-warping变换的水下对空运动声源的线谱探测EI北大核心CSCD

提出了一种利用Doppler-warping变换的水下对空运动声源的线谱探测方法。该方法首先利用Doppler-warping变换线性化目标线谱的多普勒相位,再提取线性化后的目标线谱点,结合波束形成算法实现对目标的探测。仿真和海试数据处理结果表明,与直接提取目标线谱实现探测的方法相比,所提出方法有以下几个优势:(1)将目标线谱多普勒相位线性化,线谱跟踪更为稳定连续;(2)将目标线谱频带展宽的能量重新集中到原频率附近,在低信噪比环境下能更好地提取目标线谱;(3)将干扰线谱瞬时频率非线性化,能更好地实现干扰线谱的分离。海试数据处理结果表明,实现了对远至16.8 km处空中运动目标的水下有效探测,探测能力与抗干扰能力明显增强。     

Scaling properties of phase-change line memory

Phase-change line memory cells with different line widths are fabricated using focused-ion-beam deposited C-Pt as a hard mask. The electrical performance of these memory devices was characterized. The current-voltage (I-V ) and resistance-voltage (R-V ) characteristics demonstrate that the power consumption decreases with the width of the phase-change line. A three-dimensional simulation is carried out to further study the scaling properties of the phase-change line memory. The results show that the resistive amorphous (RESET) power consumption is proportional to the cross-sectional area of the phase-change line, but increases as the line length decreases.     

Reducing the line curvature error of mechanically ruled gratings by interferometric control

Line curvature error greatly influences the quality of the diffraction wave fronts of machine-ruling gratings. To reduce the line curvature error, we propose a correction method that uses interferometric control. This method uses diffraction wave fronts of symmetrical orders to compute the mean line curvature error of the ruled grating, taking the mean line curvature error as the system line curvature error. To minimize the line curvature error of the grating, a dual-frequency laser interferometer is used as a real-time position feedback for the grating ruling stage, along with using a piezoelectric actuator to adjust the stage positioning to compensate the line curvature error. Our experiments show that the proposed method effectively reduced the peak-to-valley value of the line curvature error, improving the quality of the grating diffraction wave front.     

Line defects of a two-component vector order parameter

The line density of line defects in terms of a two-component vector order parameter are obtained from the definition of topological charges of line defects. The spatial structure and bifurcation of line defects in three-dimensional space are also studied from the topological properties of the two-component vector order parameter. The branch conditions for generating, annihilating, colliding, splitting, and merging of line defects are obtained according to the properties of the two-component vector order parameter itself. It is found that the velocities of line defects are infinite when they are being annihilated or generated, which is obtained only from the topological properties of the two-component vector order parameter.     

On the Quillen determinant

We explain the bundle structures of the Determinant line bundle and the Quillen determinant line bundle considered on the connected component of the space of Fredholm operators including the identity operator in an intrinsic way. Then we show that these two are isomorphic and that they are non-trivial line bundles and trivial on some subspaces. Also we remark a relation of the Quillen determinant line bundle and the Maslov line bundle.     

传输线特性阻抗的一个新计算方法

本文提出对于传输线的特性阻抗的一个新计算方法,即利用变分法的一个定理求出特性阻抗的准确值的上限及下限,但在计算过程中不是应用变分法的常用方法来进行处理,而是利用函数变换法来进行处理。这种方法可以估计特性阻抗的准确值的上限及下限,如果上下限值差别不大,则其平均值即可取作此特性阻抗的近似值,并且准确度很高。文中对于具有圆柱形内导体的矩形线、对称全矩形线、槽形线及平板线的特性阴抗分别进行计算,并举例求出数值与已发表的文献进行比较,最后对多心电续的特性阻抗也进行近似计算。 关键词：     

Electronic transport of bilayer graphene with asymmetry line defects

In this paper,we study the quantum properties of a bilayer graphene with(asymmetry) line defects.The localized states are found around the line defects.Thus,the line defects on one certain layer of the bilayer graphene can lead to an electric transport channel.By adding a bias potential along the direction of the line defects,we calculate the electric conductivity of bilayer graphene with line defects using the Landauer-Biittiker theory,and show that the channel affects the electric conductivity remarkably by comparing the results with those in a perfect bilayer graphene.This one-dimensional line electric channel has the potential to be applied in nanotechnology engineering.     

一种有损非均匀传输线时域分析方法

提出利用等效电路法解决电磁脉冲注入下有损非均匀传输线及其网络端接非线性负载的时域响应问题。采用分段逼近级联方法建立了有损非均匀传输线的等效电路模型。利用设计的快沿电磁脉冲源对有损非均匀微带线端接电阻、瞬态抑制二极管的响应进行了试验和仿真对比分析,验证了该等效电路模型的正确性和解决非线性负载响应问题上的有效性。通过与FDTD法对更复杂的有损非均匀传输线、不等长有损非均匀传输线、有损非均匀传输线网络的仿真结果和计算机运行时间进行对比分析,进一步验证了该等效电路法的正确性以及在解决有损非均匀传输线问题上的普遍适用性和高效性。     

Poisson线瞄准技术初步研究

Poisson斑的中心可以在很长的距离内保持与轴心共线因而能实现高精度的对心瞄准,这一技术被称为Poisson线技术.利用数值模拟和实验验证对Poisson线瞄准技术进行了初步研究.通过数值模拟发现,Poisson线上的光强随着离圆屏距离的增加而增大;Poisson斑直径随着圆屏直径增加而减小、随着距离增加而增加;其方向平行于入射激光束并过圆屏中心（待瞄准点）.Poisson线对圆屏的倾斜非常不敏感,但是对中心的偏移非常敏感.模拟中发现Poisson线对10 μm的中心偏移敏感,初步实验验证Poisson线可实现50 μm的对心误差调节. 关键词： 中子成像 Poisson线 Fresnel衍射     

Line positions and intensities of acetylene in the 2.2-μm region

More than 440 line positions and intensities of 8 bands of acetylene are measured in the 2.2-μm spectral region. A multispectrum fitting procedure has been applied to retrieve line parameters. The average absolute accuracy of the line parameters obtained in this work is estimated to be ±0.0005 cm⁻¹ for the line positions, and ±5% for the line intensities. Vibrational transition dipole moment and Herman-Wallis coefficients are determined for two of the studied bands. An unusual rotational dependence of the vibrational-rotational transition dipole moment of remaining bands has been found. All measured line intensities are treated simultaneously within the framework of the effective operators approach. The sets of effective dipole moment parameters obtained reproduce the observed line intensities within the experimental uncertainty.     

基于数字图像的高精度面内转角测量方法

针对科研与工程中转角测量优于5″的高精度要求,提出了一种用直线做特征标志的基于图像的测量方法。用高分辨率相机采集被测物上长直线标志,通过高精度检测图像上直线的倾斜角度来计算转角。分析了基于图像高精度角度测量中出现的多种原来无需考虑的影响精度的因素。给出了角秒级角度测量时直线的拟合检测算法以及直线标志的成像宽度、长度、与采样方向的角度等参量的选择应满足的条件。仿真和实验结果表明直线宽度5~9 pixel,直线方向避开与采样方向成0°和45°角时角度检测精度达到最优,当直线长度不小于1000 pixel时测量精度优于5″。     

An efficient analytical approach for calculating line mixing in atmospheric remote sensing applications

Collisional coupling between energy states in a molecule undergoing an optical transition can alter the line shape associated with the transition, an effect known as line mixing. Accounting for this effect in the analysis of remote sensing measurements of Earth's atmosphere by the Atmospheric Chemistry Experiment (ACE) yields reduced residuals, which leads to improved performance in the volume mixing ratio retrievals for some molecules. Analytical expressions are presented for the imaginary components of the polynomial ratios from the Humlicek algorithm, which provides approximate solutions to the complex probability function. These imaginary components are employed in the calculation of line mixing using the Rosenkranz first order approximation. Examples of line mixing in ACE measurements are presented, including a set of CH₄ lines that exhibit both line mixing and speed dependence. An efficient, analytical approach is proposed for calculating line shapes with a combination of line mixing and speed dependence. FORTRAN routines for calculating line mixing effects are provided as a supplement to the paper.