Phase estimation in bispectral domain based on conformal mapping and applications in seismic wavelet estimation

地震小浪评价是地震数据处理和解释的重要部分，谁的正确直接与 deconvolution 和倒置的结果有关。小浪评价基于高顺序的系列是一个重要新方法。然而，高顺序的系列经常有阶段包装纸问题，它导致小浪阶段光谱偏差并且从而影响混合阶段小浪评价。解决这个问题，我们建议一个新阶段光谱方法基于在 bispectral 领域的保角的印射。方法避免由缩小 Fourier 阶段光谱的范围消除在原来的阶段包影响的 bispectral 阶段包问题的阶段光谱评价。方法基于保角的印射组成最少平方的小浪阶段光谱评价它与最少平方的小浪振幅光谱评价被用于混合阶段小浪评价。理论模型和实际地震数据验证这个方法的有效性。我们也扩大到 trispectral 小浪阶段光谱评价的在 bispectral 小浪阶段光谱评价的保角的印射的想法。

Study of Dielectric and Mechanical Spectra on Point Defects and Phase Transition in Ferroelectric Ceramics

Ferroelectric materials have enormous potential applications in advanced techniques. However, there are still many problems in its practical application. Dielectric and mechanical (internal friction) measurements are very sensitive to phase transitions, relaxation process of point defects, domain walls and their mobility, which have severe effect on ferroelectric properties. These make them become very good means to investigate substantial information on structural features and to explore the fundamental principles in ferroelectric materials and their applications. In this paper, the dielectric and internal friction measurement were used to investigate the behaviors for point defects and phase transition in ferroelectric ceramics such as Bi_ 4-x La_ x Ti_ 3 O_ 12 , Bi_ 4 Ti_ 3-y Nb_ y O_ 12 , SrBi_ 2 Ti_ 2 O_ 9 , PbZr_ x Ti_ 1-x O_ 3 ,_ PMN-PT. They were used to clarify the mechanism for some ferroelectric behaviors.

基于极值外推的特种车辆疲劳耐久性多轴载荷谱编制

非道路特种车辆服役载荷谱是整车结构耐久性的关键,为此提出基于极值外推的特种车辆疲劳耐久性多轴服役载荷编制方法。考虑到多轴载荷谱外推时的载荷通道之间具有相位关系,开展以临界平面损伤参量为基础的多轴载荷等效合成研究;构建极值超出量服从广义Pareto分布的多轴外推模型。利用等效合成载荷谱进行载荷外推,将基于等效合成系数获取的外推量分配到每个载荷通道上,实现考虑相位关系的多轴载荷外推。以典型工况下特种车辆的轮端六向力信号为研究对象进行多轴外推,并对比外推前后的载荷谱与采集载荷谱通道之间的相位关系、穿级计数、雨流计数和功率谱密度。研究结果表明:基于极值外推的特种车辆整车疲劳耐久性多轴载荷编制,可以实现在相同典型工况下多轴载荷谱的有效预测。

基于云雷达资料的那曲对流云粒子相态识别研究

本文利用第三次青藏高原大气科学试验的Ka波段云雷达资料,结合微波辐射计和探空资料,提出了以模糊逻辑算法为框架的相态识别方法,并利用那曲两个典型对流云个例对方法效果进行了分析。通过与前人方法的对比和对不同相态粒子回波强度谱的统计,进一步验证了本文方法的可靠性。结果表明:利用雷达功率谱资料反演下落末速度并代替径向速度作为相态识别的参量之一,可提升对流云内粒子相态分类结果的合理性。零度层亮带和抬升凝结高度参量的使用,能够进一步优化相态识别的初步结果。固态云粒子的下落末速度远低于相同反射率因子的降水粒子,多模态/多谱峰的谱形态特征能够帮助识别混合相态粒子。

高压下硝酸肼结构演化的中远红外光谱和第一性原理计算研究

对于含能材料,6 THz(200 cm^(-1))以内的晶格振动模式对外部压力变化引起的结构变化非常敏感,因此,中远红外振动光谱可作为研究含能材料高压相变的有力手段。利用基于空气等离子体产生的中远红外超宽带光谱技术,结合金刚石对顶砧,获得了含能材料硝酸肼的高压振动光谱。同时,采用第一性原理方法,计算了硝酸肼的晶体结构和红外光谱,在此基础上对分子间的相互作用进行了分析。综合实验和计算结果,揭示了压力作用下分子间氢键和范德瓦尔斯相互作用对材料中分子结构和堆垛变化的影响,获得了硝酸肼的相变过程。

气固两相湍流非定常压力脉动特性数值模拟研究

与发动机振荡燃烧相关的气固两相流中的压力脉动现象长期以来备受关注。为了解发动机气固两相流动中的非定常压力脉动特性,以典型的后台阶气固两相流动为研究对象,使用发展的自适应湍流模拟(Self-adaptive turbulence eddy simulation,SATES)和离散相模型(Discrete phase model,DPM)相结合的方法,对两相流场进行了三维非定常高精度数值计算。以实验数据作为参考验证了计算方法的精度和可靠性。通过将两相流场的压力脉动信号与纯气相流场进行对比,发现加入颗粒后流场压力脉动主导频率略有变化,无量纲压力脉动幅值明显减小;进一步研究了固体颗粒直径和质量分数对脉动特性的影响规律,发现随着颗粒直径变大,流场振幅先减小后增大。颗粒直径为10μm时,振幅最小;随着质量分数的增大,流场振幅呈现出下降趋势。研究表明气固两相流中颗粒的参数变化对振荡主频影响较小,对脉动振幅影响显著。

外加静电场对O_(2)分子高次谐波的调制机制(特邀)

采用了Lewenstein强场近似方法,计算了外加静电场对O_(2)分子在线偏振激光场中高次谐波产生的影响。结果表明:1)当静电场方向平行激光偏振方向时,谐波谱出现双平台结构,截止频率增大,偶次和奇次谐波幅度相当;2)当静电场方向垂直时,谐波谱呈现单平台结构,偶次谐波比奇次谐波的幅度小两个量级左右;3)外加静电场对双心干涉极小值的位置基本没有影响。利用Lewenstein理论,可以将分子谐波谱视为分子两端电离通道产生谐波的叠加,对外加静电场控制高次谐波提供了参考。

FORMATION OF MANGANESE SILICIDE THIN FILMS BY SOLID PHASE REACTION

Manganese silicide MnSi_(2-x) thin films have been prepared on n-type siliconsubstrates through solid phase reaction. The heterostructures were analyzed by X-ray diffraction,Rutherford backscattering spectroscopy, Fourier transform infrared transmittance spectroscopy andthe four-point probe technique. The results show that two manganese silicides have been formedsequentially via the reaction of thin layer Mn with Si substrate at different irradiation annealingstages, i.e., MnSi at 450 deg C and MnSi_(1.73) at 550 deg C. MnSi_(1.73) phase exhibits preferredgrowth after irradiation with infrared. In situ four-point probe measurements of sheet resistanceduring infrared irradiation annealing show that nucleation of MnSi and phase transformation of MnSito MaSi_(1.73) occur at 410 deg C and 530 deg C, respectively; the MnSi phase shows metallicbehavior, while MnSi_(1.73) exhibits semiconducting behavior. Characteristic phonon bands ofMnSi_(2-x) silicides, which can be used for phase identification along with conventional XRDtechniques, have been observed by FTIR spectroscopy.

HIGHER ORDER SPECTRAL ANALYSIS IN FAULT DIAGNOSIS OF ROTORS

The nonlinear properties of rotating machinery vibration signals are presented. The relationship between faults and quadratic phase coupling is discussed. The mechanism that gives rise to quadratic phase coupling is analyzed, and the coupling models are summarized. As a result, higher order spectra analysis is introduced into fault diagnosis of rotors. A brief review of the properties of higher order spectra is presented. Furthermore, the bicoherence spectrum is employed to extract the features that signify the machinery condition. Experiments show that bicoherence spectrum patterns of different faults are quite different, so it is proposed to identify the faults in rotors.

Pair phase transition and its evolution on even ^(64～68)Ge isotopes

By using a microscopic sdIBM-2+2q.p. approach which is the phenomenological core plus two-quasi-particle model and the experimental single-particle energies, the levels of the ground-band, β-band, γ-band, and partial two-quasi-particle states on 64~68 Ge isotopes are successfully reproduced. Based on the phenomenological model and microscopic approach, it has been deduced that no s-boson in the nucleus is breaking up and aligning; and that when one d-boson does, the minimum aligned energy can be calculated. This paper explicitly indicates that, with the increase of neutron number, an evolution process of PPT objectes, i.e. from the two-quasi-proton states (on64Ge nucleus) to the two-quasi-neutron states (on 68Ge nucleus) may take place in even Ge isotopes.

Residual Phase Noise and Time Jitters of Single-Chip Digital Frequency Dividers

In this paper, we demonstrate the residual phase noise of a few microwave frequency dividers which usually limit the performance of frequency synthesizers. In order to compare these dividers under different operation frequencies, we calculate additional time jitters of these dividers by using the measured phase noise. The time jitters are various from -0.1 fs to 43 fs in a bandwidth from 1 Hz to 100 Hz in dependent of models and operation frequencies. The HMC series frequency dividers exhibit outstanding performance for high operation frequencies, and the time jitters can be sub-fs. The time jitters of SP8401, MC10EP139, and MC100LVEL34 are comparable or even below that of HMC series for low operation frequencies.

Amplitude and phase controlled absorption and dispersion of coherently driven five-level atom in double-band photonic crystal

The absorption–dispersion properties of a microwave-driven five-level atom embedded in an isotropic photonic bandgap(PBG) have been studied. Due to the singular density of modes(DOM) in the isotropic PBG and the dynamically coherence induced by the coupling fields, modified reservoir-induced transparency and quantum interference-induced transparency emerge simultaneously. Their interaction leads to ultra-narrow spectral structure. As a result of closed-loop configuration, these features can be manipulated by the amplitudes and relative phase of the coherently driven fields. The position and width of PBG also have an influence on the spectra. The theoretical studies can provide us with more efficient methods to control the atomic absorption–dispersion properties, which have applications in optical switching and slow light.

A RAMAN-SPECTROSCOPIC STUDY OF PHASE STRUCTURE OF DRAWN POLYETHYLENE

A drawn high density polyethylene（HDPE）has been measured by Raman spectroscopy and differential scanning calorimetry （DSC）. The crystalline structure of drawn HDPE is analysed by the Raman internal modes in terms of mass fractions of the crystalline orthorhombic phase, the liquid- like amorphous phase and the disordered anisotropic phase. The mass fractions depend on draw temperature T;and draw ratio R;. The fraction of disordered anisotropic amorphous phase changes very little with, the T;and increases with increasing R;. Sum of the mass fractions of crystalline orthorhombic phase and the disordered anisotropic phase increases linearly as the same slope as the crystallinity W;determined from DSC measurements with increasing T;or R;and it is higher than the W;for all the samples. The results show that the mass fraction of disordered anisotropic phase is partially devoted by the taut tie molecules （TTM s） in the amorphous state. The dependence of the disordered anisotropic phase on T;and R;supports the mechanism of plastic deformation of fibre structure.

双色中红外激光场延迟及相位调控产生水窗区间光子

理论研究了双色中红外激光场时间延迟及相位对高次谐波光谱的影响.结果表明:当激光延迟为-1.0 fs,激光相位为0.2π和0时,谐波截止能量可以得到有效延伸,并且获得一个超宽水窗区间谐波连续平台区.此外,谐波光谱的延伸与控制场波长关系不大,即,在上述激光延迟和相位下,控制场波长在2300 nm到2700 nm区间时都可获得水窗区谐波光谱.最后,叠加光谱连续区的谐波可获得35 as的水窗区孤立阿秒脉冲.

非线性系统中双频光栅相位测量

为了在非线性测量系统中获得更好的相位测量结果,提出了一种在几乎消除非线性影响后使用双频光栅投影的相位测量方法。首先,讨论了相位测量系统的非线性效应,分析了频域中存在高阶频谱成份的基本原因,给出了减小非线性效应并分离基频信息的基本方法。然后,在减小系统非线性效应影响的基础上,分析了使用双频光栅投影测量被测物体条纹图像的相位基本原理。为验证所提出的相位测量方法的有效性,进行了计算机仿真和实际实验,获得了良好结果。在仿真实验中,该方法的误差值为有非线性影响方法的27.97%,为几乎没有非线性影响方法的52.51%;在实际实验中,该方法的相位恢复效果最好。表明采用本文方法所测量的相位效果好,误差较小。

基于广义S变换的地震资料振幅谱补偿和相位谱校正方法研究（英文）

由于地下介质对地震波振幅的影响和地震波频散因素,地震波振幅和相位随时间、空间及频率的变化而发生改变,本文提出一种基于广义S变换的振幅谱补偿和相位谱校正新方法。该方法在S域中分为振幅谱补偿和相位谱校正两个步骤进行处理:振幅谱补偿是在地震记录可靠频带范围内恢复反射系数的振幅谱,其具体实现是在S域中利用谱模拟技术来拟合时变子波振幅谱,从而补偿由地层吸收所引起的振幅衰减;相位谱校正是消除子波剩余相位的影响,其具体实现是在S域中利用相位扫描来拾取随时间、空间和频率而变化的相位校正量,并由Parsimony准则来进行最佳相位判别。本文方法不需要直接求取Q值,能够适用于变Q值情况。理论模型和实际资料处理表明,该方法不仅能恢复地层反射系数的振幅谱,还可以有效消除子波剩余相位的影响,使子波接近或达到零相位,从而提高地震资料分辨率。

基于小波分解的热波相位特征提取及喷涂层厚度评价

针对热障涂层制备过程中的厚度评估问题,通过数值模拟手段研究了光脉冲激励下制备在镍基高温合金上不同厚度的Ni Cr Al Y涂层表面热波瞬态响应规律;在此基础上分析了表面热波相位特征随涂层厚度的变化规律,结果表明特定频率范围的热波相位特征与涂层厚度具有近似线性对应关系,但不同涂层厚度之间的相位差绝对值较小,不利于厚度定量评价;为提高不同厚度涂层之间的热波相位差,提出采用小波分解第二层细节系数对涂层表面热波进行重构,重构热波相位差比原始热波提高了约500倍,有利于提高涂层厚度评价的准确率;最后采用试验手段验证了模拟结果的准确性。

多元醇及其二元混合物固固相变的IR研究

FT infrared spectrometer was used to obtain a series of infrared spectra at various temperatures of pentaerythritol(PE)、pentaglycerine(PG)、neopentylglycol(NPG) and their binary mixtures.The shifts of -OH absorption peak reveal the solid solid phase transition mechanisms and the connection of wave number shifts with temperature and enthalpies of phase transition.The solid solid phase transitions of the three polyols and their binary mixtures are known to transform from a low symmetric layered crystal structure to a highly symmetric face centered cubic structure.Experimental results support a mechanism which involves reversible breaking of nearest neighbor hydrogen resonance bonds in the molecular crystals at the transformation temperature.Infrared spectra show reversible increase in the wave number of the absorption peak of -OH groups with reversible breaking of the hydrogen bonds.This is in agreement with the experimental results of X ray diffraction and thermal analysis.

金红石高温高压相变的Raman光谱特征

以Ar作压力介质,在准静水压力条件下,利用激光加热DAC技术和显微Raman光谱原位测试技术,在0~35 GPa压力范围开展金红石的高温高压相变研究。在室温条件下,金红石结构TiO2于13.4 GPa开始转变成斜锆石相,于21 GPa时转变完全,并直到35 GPa时斜锆石相稳定存在。在压力分别为29.4和35.0 GPa时,用YAG激光器发出的波长为1.064μm的红外激光束扫描加热样品,TiO2斜锆石高压相转变成另一Pbca结构高压相。卸压时,Pbca相于26.3 GPa时转变成斜锆石相。斜锆石相转变成Pbca相需要加热才能发生,而卸压时却在较小的压力区间即迅速转变完全,两相转变压力边界在28 GPa左右。进一步卸压,斜锆石相直到11 GPa仍稳定,在7.6 GPa时斜锆石相与-αPbO2相两相共存,5 GPa时完全转变成-αPbO2相,并直到常压该相以亚稳定态存在。

硫氰化铵固-固相变贮热及变温红外研究

用 Ｄ Ｓ Ｃ 法研究无机塑晶材料硫氰化铵从室温到２２０℃之间的热物理性质，探讨其贮热可跑性，并利用变温红外光谱仪分析硫氰化铵固固相变的机理。