查询词典 spectral density

It is concluded by the comparison of the Power Spectrum Density Function estimated from design spectra that the spectral energies do not distribute uniformly within the frequency of engineering interest in Chinese codes. The remarkable spectral energies concentrate in the range of low and high frequency.

由各规范设计谱估计的功率谱密度函数的比较说明，我国某些抗震设计规范设计谱给出的设计地震动在工程感兴趣的频率范围内可能存在能量分布不均的问题，低频分量和高频分量与中等频率段相比相对显著。

In addition,the electron density of plasmas were calculated from measured stark broadening of emission spectral line respectively, the effects of the additional voltage on the electron density and the spatial evolution property of the electron density were finally discussed according to the experimental results.

此外，由发射光谱线的Stark展宽计算了等离子体电子密度，并由实验结果讨论电子密度随外加电压的演化特性和空间演化特性。

The influences of the shock thickness and Alfven waves on the particle acceleration by diffusive shock waves are numerically studied through solving one-dimensional diffusive equation including the second-order Fermi effect. It is shown that the spectral index of the energetic particles strongly depends on the shock thickness. For example, the spectral index increases from 2.1 to 3.7 in the low energy range of 3-10 MeV and from 2.5 to 5.0 in the high energy range of 20-60 MeV as the thickness increases. The spectral index decreases from 4.3 to 3.1 as the particle injection energy increases. The spectral index decreases from 4.0 to 1.8 at the quasi-steady stage with the enhancement of the compression ratio from 2 to 4. The results indicate that under the influence of Alfven waves, the energetic particle spectrum at lower energy becomes flat and the spectral index decreases from 2.5 to 0.6 in the low energy range of 3-10 MeV and from 11.6 to 5.0 in the high energy range of 20-60 MeV. At the same time, the rollover energy reaches 19.6 MeV. The spectral index decreases from 5.8 to 2.9 as the energy density of Alfven waves increase. All these results are basically consistent with the theoretical models, as well as the observations of typical energetic particle events.

通过数值求解包含二阶费米加速的一维扩散方程，探讨在准平行激波条件下激波厚度和级联阿尔芬波对粒子加速的影响，研究粒子分布函数的演化与激波厚度和阿尔芬波强度的内禀关系，计算结果表明：(1)考虑激波厚度时，谱指数明显依赖于激波厚度，随着厚度从0.32增大到2.56，低能端(3-10MeV)谱指数逐渐从2.1增加到3.7，高能端(20-60MeV)谱指数从2.4增大到5.0，能谱逐渐变软；当初始注入粒子动量增大1.3倍，质子能谱指数从4.3减小到3.1，且与零厚度激波加速的谱指数差值缩小；厚度不变时，随着压缩比从2增加到4，准稳态分布时低能端(3-10MeV)粒子能谱指数逐渐从4.0减小到1.8谱变硬；(2)在级联阿尔芬波的影响下，随着时间的增大，粒子在低能处(3-10MeV)的谱指数从2.5减小到0.6高能端(20-60MeV)谱指数从11.6减小到5.0，能谱变硬，拐点能量值从7.5MeV增大到为19.6MeV；随着波的能量密度增大，谱指数从5.8减小到2.9，这表明阿尔芬波强度越大，加速效率越高，通过与激波厚度解析结果和高能粒子事件的观测能谱比较发现两者是一致的，说明数值模拟结果是可靠的。

According to spectral characteristics of the HCVAW arc in a body, energy factor which value equals to the ratio of two spectral lines' intensity, was defined.When τ's value was less than 0.1, the HCVAW arc was exhibitive of diffusedshape with lower energy density instinct; and when τ's value was higher than 0.5,the arc was a fine-constricted arc with higher energy density.

从积聚态电弧的谱线空间分布来看，阳极材料为水冷铜板时，自空心阴极端面到阳极工件，氩原子谱线相对辐射强度具有比氩一次离子谱线相对辐射强度更快的减弱趋势，最大辐射强度均出现在距空心阴极端面2mm左右的位置。

Further, with the help of Riccati equations, an infinite number of conservation laws for the solton hierarchy are deduced. For the sake of simplicity, taking the general TD hierarchy as an illustrative example, we prove that its 2×2 Lenard pair of operators forms a Hamiltonian pair. Thus the isospectral evolution TD hierarchy is the general Hamiltonian system and possesses the Bi-Hamiltonian structures and Multi-Hamiltonian structures. By using the method of derivation of functional under some constraint condition, a complete one-to-one correspondence between the Hamiltonian functions of the hierarchy and its conservation density functions can be built. These results can also be applied to the isospectral evolution soliton hierarchy of this paper. Finally, there's a gauge transformation between the spectral problem of this paper and the AKNS system. Moreover, the potentials in these spectral problems satisfy the general Miura transformation, the corresponding relationship between the two soliton hierarchies is also given.

进一步本文还通过特征函数的组合关系所满足的Riccati方程，得到了该等谱方程族的无穷多个守恒律；为简便起见，本文以广义TD族为例，由它的2×2 Lenard算子对的性质证明了此算子对为Hamilton算子对，这说明广义TD族是广义Hamilton系统且具有Bi-Hamilton结构和Multi-Hamilton结构；进而利用它的依赖于谱参数的一般守恒密度的积分在约束条件下求泛函导数的方法，得到了广义TD族的Hamilton函数与守恒密度之间的对应关系，这些性质对于由本文提出的2×2谱问题所导出的等谱孤子族仍成立；另外此谱问题与AKNS系统存在着规范变换，位势之间有广义Miura变换，而孤子方程之间也满足一定的等价关系。

It has been found that the spectral energy density and radiation pressure of a Kerr nonlinear blackbody are larger than those of a normal blackbody, and there is a regular variety of the spectral energy density and radiation pressure in a Kerr nonlinear blackbody with the change of temperature and frequency.

通过和普通黑体比较发现，克尔非线性黑体的光谱能量密度和辐射压强都要比普通黑体大，非线性黑体中的热辐射光谱能量密度和辐射压强随着温度和频率的改变有着规律的变化。

Fα power spectral density of the cardiac QRS complex is not associated with a fractal Purkinje system. Biophys J.

His-Purkinje系统的分形特征的形态学基础与心电信号表观之间有何关系的问题尚待进一步研究。

We analyse statistics properties of ground clutters and study AR model of correlated clutters power spectral density.

分析了地杂波统计特性，研究了相关雷达杂波功率谱特性的AR模型及其模拟方法。

Random noise for a fiber optic gyro mainly consists of wh ite noise and1/f γ fractal noise, which characterized by longˉterm correlation, selfˉsimilarity and1/f γ spectral density with 1/fγpower law.

光纤陀螺随机噪声中包含了白噪声和具有长程相关性、自相似性及 1/f γ类型谱密度特点的一种非平稳随机噪声———1/f γ类分形噪声。

In order to obtain infrared spectral radiance distribution of some infrared sources, such as spectral radiant flux density, spectral radiant intensity, spectral radiance and spectral irradiance, the instrument response function under different conditions must be known.

在应用红外发射光谱来获得某些红外源的绝对光谱能量数据，如辐射源光谱辐射通量密度、辐射源光谱辐射强度、辐射源光谱辐射亮度及光谱辐射照度等时，需要得知不同条件下的仪器响应函数。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。