TTI介质中的纯qP波衰减补偿最小二乘逆时偏移成像方法

为有效提高衰减各向异性介质中地震波成像剖面的质量,实现稳定的TTI介质中的衰减补偿成像,提出一种基于黏声TTI纯qP波方程的最小二乘逆时偏移方法。在最小二乘偏移框架的基础上,推导相应的Born正演方程、伴随算子和梯度敏感核。由于伴随算子是衰减的,可以避免衰减补偿引起的数值不稳定性。通过同时考虑各向异性和吸收衰减的影响,衰减补偿最小二乘逆时偏移可以提供高分辨率、更少假象和振幅均衡的偏移结果。最后,通过模型试验和实际数据的测试及分析,验证了新方法的可行性和适用性。结果表明,黏声TTI最小二乘逆时偏移成像在衰减区域可进行高质量成像,丰富成像剖面中的波数成分,拓宽成像剖面中的频带宽度,提高地下介质成像剖面的分辨率及成像精度。

Q波段宽带螺旋线行波管输能系统研究

针对Q波段宽带螺旋线行波管所需要的低损耗、低反射输能系统,采用后馈式单脊过渡波导和盒型窗方案,优化设计了过渡波导阻抗变换结构、内导体尺寸和螺旋线大螺距过渡结构,得到33~50 GHz频带内驻波系数小于2的输能系统,并成功应用在Q波段宽带多用途螺旋线行波管中。

Q value of anelastic S-wave attenuation in Yunnan region

The study of seismic attenuation property is a major subject in seismology. Seismic waves recorded by seismic stations （seismographs） contain source effect, seismic wave propagation effect, site response of seismic stations and instrumental response. The path effect of seismic wave propagation, site response of seismic stations and instrumental response must be taken out in the study of source property with seismic data. The path effect of seismic wave propagation （seismic attenuation） involves an important influential factor, the anelastic attenuation of medium, which is measured with quality factor Q, apart from geometric attenuation with the distance. As a basic physical parameter of the Earth medium, Q value is essential for quantitative study of earthquakes and source property （e.g. determination of source parameters）, which is widely used in earthquake source physics and engineering seismology.

Influence of Generalized （r, q） Distribution Function on Electrostatic Waves

Non-Maxwellian particle distribution functions possessing high energy tail and shoulder in the profile of distribution function considerably change the damping characteristics of the waves. In the present paper Landau damping of electron plasma （Langmuir） waves and ion-acoustic waves in a hot, isotropic, unmagnetized plasma is studied with the generalized （r, q） distribution function. The results show that for the Langmuir oscillations Landau damping becomes severe as the spectral index r or q reduces. However, for the ion-acoustic waves Landau damping is more sensitive to the ion temperature than the spectral indices.

Characterization for wave equations in viscoelastic media based on the constant Q property

The constant Q property in viscoelastic media assumes that the quality factor Q does not change with frequency(i.e.,the Q value is independent of the frequency).For seismic waves propagating in viscoelastic media,the wave equation is determined by the viscoelastic media model.Equivalence relations exist between various frequency domain mathematical models and physical rheological models for the constant Q property.Considering two elastic moduli and three attenuation variables,24 kinds of wave equations based on diff erent generalized rheological models are divided into six classes in this study,and the 12 kinds of specifi c representation for the wave equations in the time domain are derived.On the basis of the equivalence relations between the generalized rheological models,the diff erence and equivalence relation between diff erent wave equations are proven and clarifi ed.Results show that the high-order generalized rheological model can accurately characterize the attenuation characteristics of seismic waves and has advantages in characterizing the dispersion characteristics in viscoelastic media.Lastly,the seismic refl ection characteristics caused by the diff erence of Q value are verifi ed by the forward modeling of the constant Q wave equation in this study,thereby providing a theoretical basis for the analysis and inversion of the formation Q value from refl ection seismic data.

Corrosion-fatigue evaluation in Q235A steel using nonlinear Rayleigh surface waves

This paper presents a non-destrcutive evaluation method for the evolution of corrosion fatigue of Q235A steel. Specimen surface degradation due to corrosion fatigue from the combined interaction of corrosion and cyclic loading leads to harmonic generation during Rayleigh wave propagation along the specimen surface,which allows for an early prediction of material fatigue life. The relative nonlinearity parameter β as an evaluation parameter,which is denoted as a ratio of fundamental and second-order harmonic amplitudes,is measured by using an experimental platform based on a pair of wedge transducers to launch and receive Rayleigh wave signal. Subjected to an immersion corrosion method with 10% NaCl solution and a 20 Hz cyclic loading,a corrosion-fatigue specimen was made,and its relative nonlinearity parameter was measured every 10 5 cycles until to 7 ×10^5 cycles. A measured curve of relative nonlinearity parameter versus fatigue load cycles,which is produced by surface degradation of specimen corrosion fatigue,showed an initial steady trend followed by a rapid increase. Experimental results demonstrate that corrosion fatigue results in the sudden destruction of a Q235A steel specimen and nonlinear Rayleigh surface waves measurement technique can be used to quantitatively characterize fatigue life of Q235A steel.

心电图碎裂QRS波联合病理性Q波对急性心肌梗死的诊断价值

目的分析心电图碎裂QRS波(fQRS)联合病理性Q波对急性心肌梗死(AMI)的诊断价值。方法将我院2020年1月至2021年12月收治的100例冠心病患者纳入本次研究,以心电图诊断结果差异将其分为AMI组(n=52)和非AMI组(n=48)。所有患者均接受心电图检查,根据心电图ST段是否抬高将52例AMI患者分为ST段抬高组与ST段未抬高组,比较两组的fQRS波、病理性Q波发生情况;以病理学检查结果为金标准,比较fQRS波、病理性Q波单独及联合检测对AMI的诊断效能,包括灵敏度、特异度、准确度、阳性预测值、阴性预测值;根据fQRS波是否出现将52例AMI患者分为fQRS波组与非fQRS波组,随访追踪两组患者1年内心血管不良事件发生率与再次住院率。结果ST段抬高组的fQRS波发生率低于ST段未抬高组,病理性Q波发生率高于ST段未抬高组(P<0.05)。fQRS波、病理性Q波联合诊断AMI的灵敏度、准确度、阴性预测值高于单独诊断(P<0.05)。fQRS波组的各项心血管不良事件发生率及再次住院率高于非fQRS波组(P<0.05)。结论心电图fQRS波联合病理性Q波能有效提高AMI诊断效能,特别是fQRS波能够评估患者预后,具有较高应用价值。

Analysis of the Q-T Dispersion and T Wave Alternans in Patients with Epilepsy

Objectives: There is a high rate of sudden death in epilepsy patients, part of which is sudden cardiac death. By investigating ECG T wave alternans and Q-T dispersion changes of epilepsy patients, we may predict the possibility of the occurrence of sudden death and provide basis for clinical prevention. Methods: Selecting 587 cases of epilepsy patients as the study group, 672 same period cases of healthy persons as the control group;Analyzing the effect of epilepsy on ECG T wave alternans and Q-T dispersion with the standard 12 lead ECG. Results: The study group had a significantly prolonged Q-T dispersion and an increased incidence of T wave alternans than that of the control group;Compared with other seizure types, tonic clonic seizure and absence seizure had a significantly prolonged Q-T dispersion and an increased occurrence rate of T wave alternans. Conclusions: Epilepsy patients ECG T wave alternans and Q-T dispersion has higher abnormal rate, and are prone to sudden cardiac death;Routine ECG(RECG) T wave alternans and Q-T dispersion changes can provide guidance for clinical prevention of sudden unexpected death in epilepsy (SUDEP).

非ST段抬高型心肌梗死患者经皮冠状动脉介入治疗后病理性Q波持续状态与预后的关系

目的探讨非ST段抬高型心肌梗死(NSTEMI)患者经皮冠状动脉介入(PCI)治疗后病理性Q波持续状态与预后的关系。方法回顾性分析2020年8月至2022年8月首都医科大学附属北京同仁医院收治的147例NSTEMI患者的临床资料,根据PCI治疗后1年是否发生主要不良心血管事件(MACE),将患者分为MACE组(52例)和非MACE组(95例)。比较2组患者临床资料,采用多因素Logistic回归方法分析NSTEMI患者PCI治疗后预后的影响因素。采用交互作用检验分析评估患者治疗后病理性Q波持续状态对预后的预测价值。结果2组患者全球急性冠状动脉事件注册(GRACE)评分、中性粒细胞与淋巴细胞比值(NLR)、高密度脂蛋白胆固醇(HDL-C)、肌酸激酶同工酶(CK-MB)、心肌肌钙蛋白I(cTnI)、左心室射血分数(LVEF)、病理性Q波状态比较差异均有统计学意义(均P<0.05)。多因素Logistic回归分析结果显示,GRACE评分、LVEF、NLR、HDL-C、CK-MB、cTnI、病理性Q波状态均为NSTEMI患者PCI治疗后预后的影响因素(比值比=3.017、3.868、2.562、2.161、4.093、5.604、7.556,均P<0.05)。病理性Q波持续状态对NSTEMI患者PCI治疗后预后具有一定预测价值(风险比=5.791,95%置信区间:2.207~9.894,P<0.001)。结论NSTEMI患者PCI治疗后病理性Q波持续状态是患者预后的重要影响因素,对患者预后具有一定预测价值。

Tomography for Q of the Eastern Section of the Tianshan Area from High-frequency Attenuation of S-wave

Based on the waveform data of 5,076 local earthquakes recorded at 25 stations in Xinjiang during the period from 2009 to 2014 and the observation reports provided by the Xinjiang Digital Seismic Network,a data set of 19,140 attenuation factors t*is obtained by fitting the high-frequency attenuation of S-wave spectra with a genetic algorithm. The spatial distribution of Q_S is determined by inverting the t*data with seismic tomography. The results show that the average Q0 in eastern Tianshan is 520,and there is a significant correlation between the Q_S value distribution or attenuation characteristics it disclosed and the surface structure of the study area. The Q_S value is lower in the intersection area of the mountain basin which is located on the north and south sides of the Tianshan Mountains,and the high Q_S distribution is more concentrated inside the Tianshan orogenic belt. The M≥6. 0 earthquakes have been basically located in the Low-Q_S region since 1900. 24 high heat flow points in eastern Tianshan are located at the north and south of Tianshan Mountains where low Q_S exists,indicating a negative correlation. In addition,there is a positive correlation between the velocity structure and the attenuation structure in the study area,which reflects the consistency of the 2-D attenuation structure with the velocity structure and the two-dimensional density structure.

高Q值横向激发体声波谐振器的设计与制备

随着5G移动通信时代的发展,射频前端(RF front-ends)的滤波和信号处理迫切需要高频大带宽的声学谐振器。横向激发体声波谐振器(XBAR)具有超高的工作频率和超大的机电耦合系数(k^(2)),但其品质因数(Q)值不高,阻碍了其在射频前端中的应用。该文提出了一种基于ZY切铌酸锂(LiNbO 3)的XBAR谐振器,通过有限元(FEM)仿真对谐振器进行了优化设计,并在微机电系统(MEMS)工艺下对谐振器进行加工。该文所制备的横向激发体声波谐振器A 1模式的谐振频率为4.72 GHz,k 2=26.9%,Q_(3) dB为384,温度频率漂移系数为-60.5×10^(-6)/℃。A_(3)模式的谐振频率为13.5 GHz,k^(2)=4.4%。

心电图碎裂QRS波联合病理性Q波在急性心肌梗死诊断中的效能

目的:观察心电图碎裂QRS波联合病理性Q波在急性心肌梗死(AMI)诊断中的效能。方法:选取2020年1月至2022年12月该院收治的200例冠心病患者进行横断面研究,均行心电图和冠状动脉造影检查,以冠状动脉造影检查结果为金标准。按照是否为AMI将其分为AMI组(n=100)和非AMI组(n=100),比较两组心电图检查碎裂QRS波、病理性Q波、碎裂QRS波+病理性Q波检出率,分析心电图检查碎裂QRS波、病理性Q波单项及联合检查诊断AMI的效能,并比较不同类型AMI碎裂QRS波检出率。结果:AMI组碎裂QRS波、病理性Q波、碎裂QRS波+病理性Q波检出率均高于非AMI组,差异有统计学意义(P<0.05);碎裂QRS波、病理性Q波联合诊断AMI的灵敏度高于二者单项诊断,差异有统计学意义(P<0.05);ST段抬高型AMI碎裂QRS波检出率高于非ST段抬高型,差异有统计学意义(P<0.05)。结论:心电图碎裂QRS波联合病理性Q波诊断AMI的效能高于二者单项诊断。

心电图碎裂QRS波联合病理性Q波检查对急性心肌梗死患者的诊断价值观察

观察心电图碎裂QRS波联合病理性Q波检查对急性心肌梗死患者的诊断价值。选取2020年1月—2023年1月甘肃医学院附属医院收治的233例冠心病患者为研究对象,均实施心电图检查。以病理诊断结果作为金标准,分析心电图碎裂QRS波联合病理性Q波检查对急性心肌梗死患者的诊断价值以及患者发生心脏事件的具体情况。结果显示,联合心电图碎裂QRS波、病理性Q波诊断急性心肌梗死患者的灵敏度为75.83%、准确度为68.67%,高于两者单一检查(P<0.05)。随访1年的统计结果显示,120例急性心肌梗死患者的心脏事件发生率为25.00%。有心电图碎裂QRS波的急性心肌梗死患者心脏事件发生率高于无心电图碎裂QRS波的急性心肌梗死患者(P<0.05);有病理性Q波的急性心肌梗死患者心脏事件发生率高于无病理性Q波的急性心肌梗死患者(P<0.05)。研究发现,心电图碎裂QRS波、病理性Q波检查对急性心肌梗死患者具有一定的诊断价值,两者联合应用能提升诊断灵敏度、准确度。

近地表Q值求取及振幅补偿

利用面波衰减的Q模型 ,反演出近地表的Q值 .据此 ,给出消除振幅受近地表影响的振幅静校正 ,利用时间剩余静校正方法解决了振幅问题 .

岫岩陨石坑三维Q值层析成像

到2009年为止，世界上已发现176个陨石撞击坑．从20世纪80年代起，中国学者从地质、地球化学和地质钻探角度推断并证实辽宁省岫岩县的一个环形构造为陨石撞击而成，但该坑的深部构造及整体特征仍有待地球物理方法来确认．本文从地震勘探角度利用三维Q值层析成像方法首次对岫岩坑的地震波衰减结构进行了研究，以便对该撞击构造有个整体认识．Q值结构对了解地壳的非弹性性质、地壳介质非均匀性有着重要意义．利用基于吸收特征时间t^＊的三维Q值层析成像方法，计算了岫岩坑地震折射方阵的观测数据的振幅谱，并通过拟合振幅谱得到了反映地震波衰减的t^＊,利用t^＊通过三维Q值层析成像方法获得了该坑的三维Q值结构．结果表明：该陨石坑内从地表到深度100m的Q值层对应坑内上部107m厚的湖泊相沉积物，深度100t300m的Q值层对应坑内下部厚度为188m的角砾岩堆积透镜体．深度300700m的Q值层对应角砾岩堆积透镜体下面的下元古界变质岩系程度较低的撞击破碎层．大约250m深处的波阻抗界面与地质钻孔的260m深处的陨石冲击分界面相对应．

川滇地区横波Q值动态变化

Q值的动态变化能够反映地壳应力、裂隙、地下流体等的变化趋势,为进一步理解地震的孕育发生提供证据.文中尝试将选自中国地震年报、四川省地震台网观测报告及云南省地震台网观测报告的数据分成6个时间段,分别对每个时间段的数据进行成像,来获得Q值的动态变化图像.首先选择一个具有超过14000条射线数据的时间段,通过原始数据加噪音的方法和Bootstrap方法对ML振幅成像的结果进行误差和可信度分析,然后在误差可接受的基础上,再对每个时间段的数据进行成像.研究结果发现:(1)原始数据的观测误差和忽略震源辐射花样对成像结果的影响比较小,40%的噪音所造成的结果误差最大不超过6%.(2)用Bootstrap方法获得的结果最大误差不超过平均Q值的8%,说明振幅层析成像方法在川滇地区的应用因采用大量数据所获得的结果是稳定可靠的,误差是比较小的.(3)分辨率测试发现,川滇地区在射线超过50条的区域,分辨率能够达到20′.(4)分别对每个时间段进行成像,从而获得Q值变化的动态图像.每个时段的区域平均Q值与中强地震的个数有明显的正相关关系,即地震个数越多,则区域平均Q值越大,这可能是区域整体应力变化的结果.通过分析地震的分布和Q值动态变化的关系还发现,大多数中强地震不是分布在Q值变化最大的区域,而是分布在Q增加和降低最大区域之间的过渡区域,这可能是由于差应力变化在过渡区最大,更容易触发地震造成的.

叠前PS波Q值提取与稳定高效的反Q滤波算法

多波多分量地震勘探是进行岩性油气藏和隐蔽油气藏勘探的一种非常有潜力的方法。但由于实际地层是黏弹介质,造成地震波能量衰减和波形畸变,导致地震资料信噪比和分辨率难以满足油气勘探的精度要求。为更好地利用纵横波信息,需要对PP波和PS波进行振幅和相位补偿。通过解析法推导出一种从叠前转换波共炮点道集中提取横波Q值的方法,将叠后稳定高效的反Q滤波算法推广到叠前纵波和转换波的反Q滤波中,改进了沿着纵波和转换波的传播路径进行补偿的叠前反Q滤波算法,并进一步将常Q层内的纵波和转换波反Q滤波振幅补偿算子解耦为时间项和频率项的乘积,在保证补偿效果稳定的前提下,计算效率得到显著提高。

华北地区Lg尾波衰减研究——Lg尾波Q的测量

利用 1989～ 1998年间发生在中国华北地区ML≥ 3.0级的地震事件 ,华北遥测台网以及数字化台网记录到的信噪比较高的Lg尾波时间序列 ,经过滤波、消除背景噪声等预处理 ,采用单台记录叠加频谱比法 ,得到传播路径上Lg尾波Q0 (Q =Q0 fη ,Q0 是 1Hz的Q值 ,η是Q值与频率相关系数 ) ,进而获得该地区Q0 和 η的空间分布 .测量结果表明 ,华北地区地壳Lg尾波Q0 值分布存在显著的横向不均匀性 ,这种不均匀性与该地区地壳的速度分布基本一致 ,表现为与该地区地表地质特征明显的一致性 ,即传播路径位于太行山隆起和燕山隆起区为高Q0 值分布 ;传播路径位于冀中坳陷和黄骅坳陷等平原区表现为低Q0 值 ;传播路径位于隆起区和坳陷区二者之间 ,其Q0 值也介于二者之间 ,说明华北地区的地壳结构没有很大的阶跃式变化而使波导遭到破坏 ,Lg尾波Q0 值基本上反映了地壳内介质滞弹性的固有衰减 .

华北地区Lg尾波衰减研究——Lg尾波Q_0地震成像

利用单台记录叠加频谱比法测量出的华北地区 5 6 0余条单台传播路径上平均Lg尾波Q0 值数据 (Q0 是1Hz的Q值 ) ,采用随机褶积模型和奇异值分解法 ,重建该地区地壳中Q0 的横向变化 .结果表明 ,华北地区地壳中Lg尾波Q0 值分布具有显著的横向不均匀性 ,这种不均匀性与地质构造明显相关 ,块隆区具有较高的Q0 值 ,例如 ,燕山造山带、太行山块隆、鲁西隆起 ;华北平原区表现为低Q0 值分布 ,例如冀中坳陷、黄骅坳陷、济阳坳陷 ,二者界限分明 .结合研究区内的大地热值分布研究表明 ,低Q0 值区大都处于高热流区 ,这可能是地壳内热物质的活动有关 .虽然华北地区Lg尾波Q0 值高、低分区明显 ,但是 ,从总体上应该属于低Q0 值异常区 ,也就是说 ,该区的地壳是高地震波衰减区 ,这可能是该地区受太平洋板块和欧亚板块的相互作用而使地壳减薄 。