查询词典 spectral analysis

Spectral element methods for partial differencial equation is introduced in this study from viewpoint of the collocation approximation of Chebyshev polynomial. Wave Equation and its space discretization are deduced. Two time integral methods, central difference method and implicit Newmark method, are introduced, and their stability and applicability are also discussed in some details. The significance of absorbing boundary conditions in spectral element methods for Aeroacoustics is explained, and Clayton-Engquist-Majda absorbing boundary conditions is emphasized and introduced, then the discrete scheme of this boundary conditions is deduced and applied to spectral element methods for wave equation.

本文从Chebyshev多项式逼近理论出发，详细介绍了谱元方法求解偏微分方程的过程；推导了流体中的声波动方程并在空间上对其进行了谱元离散；详细讨论了两种时间积分方法──中心差分法和Newmark方法，分析了它们的稳定性条件，并从理论上对比了两种方法的优缺点和适用范围；将吸收边界条件推广应用于谱元方法求解气动声学问题中，重点介绍了Clayton-Engquist-Majda吸收边界条件的原理和公式，推导了该吸收边界条件的变分形式，并将其引入波动方程的离散形式中。

The present paper focuses on the effect of spectral range on the detected characteristic absorption structure of O3, and the variation of differential cross section of O3 with the change in spectral range and the source of interference in different spectral range.

文章主要研究了在不同光谱波段O3特征吸收结构和差分光学厚度的不同，在不同光谱波段O3浓度反演的干扰来源以及影响程度，确定了实际检测时大气消光对不同波段光强的影响，最后通过对多种污染物标准气体进行了同时监测，计算出标准气体在不同光谱分辨率不同O3浓度时的测量误差，确定了对O3的最适用光谱波段范围。

Spectral determination has proved an automatic, quick and nondestructive method for assessment ofnutrition, and the spectral discriminability of the treatments demonstrated the feasibility to evaluate rice N status in field by canopy spectral determination and the potential for detecting rice N status in a wide area by using multispectral remote sensing.

由于从高光谱窄波段的角度与氮素营养之间建立的关系在不同环境条件、不同作物品种之间具有不稳定性，因此本研究在水稻氮素营养光谱诊断方法的研究上避开了单纯使用高光谱连续波段或者窄波段的方法，从以下方面进行研究：。

In Chapter 2, we introduce a new scalar function of the vector optimization problem by virtue of the spectral function in Euclidean Jordan algebra. Correspondingly, we define the spectral scalar optimization problem and spectral scalar solution.

第二章借助欧几里德若当代数中谱函数的概念，引入了欧几里德若当代数向量优化新的标量函数——谱标量函数，并进一步定义了相应的谱标量优化问题及其谱标量解。

Based on the speciality of the spectral function, we provide the sufficient conditions such that the spectral function are K—increasing (strictly K—increasing) in Euclidean Jordan algebra, and establish the relationship between the spectral scalar solution set and the K— efficient solution set of the Euclidean Jordan algebra vector optimization problem.

基于谱函数的特殊性，刻画了谱标量函数满足K-增性的充分条件，继而建立了谱标量解集与欧几里德若当代数向量优化问题K-弱有效解集和K-有效解集的包含关系。

In this technique, K-L transformation was used to remove spectral statistic correlation on the spectral direction. Then SNMAW prediction tree technique was used to remove spatial correlation and spectral structure correlation. With the limit of a certain max error, this technique can get a higher compression ratio. 6. We proposed a lossy compression technique based on wavelet transformation with sharing significance map.

该方法在谱维方向进行K-L变换，有效地去除谱间统计冗余，而变换后的图象仍存在空间相关性和谱间结构相关性，再利用改进的预测树方法方法进行无损压缩，在最大误差很小的限制下，得到较高的压缩效率。

The number of the spectral switches decreases with decreasing obscuration ratio,and the relative spectral shifts at the spectral switches increases with decreasing carrier frequency and pulse width.

光谱开关的数目随遮拦比的减小而减小，而发生光谱开关处的相对光谱移动随载波频率和脉冲宽度的减小而增加。

Angular spectral is spectral value map formed by estimating semblable coefficients of fast and slow shear wave or the variation of amplitude ratio of fast and slow shear wave with times and angles at a specified space point based on semblable theory of fast and slow shear wave, the angle value of this space point at a given time can be got by picking the maximum of angular spectral; the study reveals that fast and slow shear wave with different polarization direction should be separated using different rotation formula, eight formulas of separating fast and slow shear wave using clockwise rotation and counterclockwise rotation have been derived, and gained energy assignment rule and phase coincidence rule, in real data estimation, the rotation formula used for separating fast and slow shear wave can be uniquely determined on the two discriminating rules. On the basis of semblable theory of fast and slow shear wave, the delay time corresponding to the maximum of semblable coefficients at a specified point in a given time window is the delay time of fast and slow shear wave, delay time section of fast and slow shear wave can be got by moving space point and smoothing time window. The vertical variation values of delay time of fast and slow shear wave reflect the effect degree of vertical fractured reservoir on fast and slow shear wave which is defined as anisotropic coefficient, and section map of anisotropic coefficient can be obtained.

角度谱就是利用快慢横波的相似性原理，在某一空间点求出快慢横波的相似系数或快慢横波的振幅比值随着时间和角度的变化而形成的谱值图，拾取其极大值就得到该空间点某一时间的角度值；在研究中发现分离不同偏振方向的快慢横波应该采用不同的旋转公式，推导出了利用顺时针旋转和逆时针旋转分离快慢横波的八个公式，并给出了能量分配准则和相位一致性准则两个判别准则，在实际计算中利用这两个判别准则能唯一地确定分离快慢横波的旋转公式；根据快慢横波的相似性原理，在某一给定点和给定时窗内最大相似系数对应的延迟时间就是快慢横波的延迟时间，随着空间点的移动和时窗的滑动就可以得到快慢横波延迟时间的剖面图；快慢横波延迟时间与慢横波传播时间的比值定义为裂缝密度，并求出了裂缝密度剖面图；快慢横波延迟时间纵向上的变化值的大小反映了纵向上裂隙层对快慢横波影响的大小，定义为各向异性系数，并求出了各向异性系数的剖面图。

By fusing the IKONOS multi-band and pan image using several image fusion algorithms(IHS transform, PC transform, Gram-Schmidt transform and smoothing filter-based intensity modulation) and assessing the fusion image, indicates that qualitative comparison is too subjective, although many methods are provided for assessment when using quantitative methods, more bands and more methods should be used for their limitations, spectral curve comparison was the best method for appraising the result, spectral angle and geometry distance was introduced to appraise the spectral curve.

以IKONOS影像为数据源，对IHS、PC，Gram-Schmidt和基于亮度调节的平滑滤波四种融合算法进行融合处理，对其结果进行了评价。结果表明，定性比较主观性较强，定量比较方法虽多，但大都有一定的局限性，不同谱段的计算结果总有些差异。因此，定量评价时应该多选一些波段与评价方法才能获得比较客观的评价结果。光谱曲线的比较不失为一种比较好的方法，在对光谱曲线进行比较时本文引入了光谱角度和几何距离两种方法进行定量的比较。

The results show the high accuracy quality of spectral element method and the stability of Newmark time integral method. Then some computational parameter is changed in example one such as the subdivision style of computational domain, time step length and such on. Some important conclusions and strategies for spectral element method with Newmark integral method for computational aeroacoustics can be given. The feasibility of spectral element method for computational aeroacoustics is verified.

计算结果表明谱元方法的高精度及Newmark时间积分方法的稳定性，并改变算例的计算参数，例如计算区域剖分方式、时间推进步长等进行了计算，得出了一些重要结论，为使用谱元方法结合Newmark积分求解气动声学问题积累了重要的经验，最终证明了谱元方法求解计算气动声学问题的可行性。

The receding calculations and experiment analyses in this subject are built on the blood cast of pig tongue.

本研究课题的前期工作是采用猪舌血管铸型模拟人舌而进行的数值计算与实验分析。

"Each human infection constitutes an opportunity for genetic modification of the virus through reassortment, mutation, or both...."

&每一次人类的感染都暗藏着一次基因修改的机会，无论是通过病毒的整合、突变或者兼而有之。。。。&