阻尼型高斯-牛顿法及其在高频电磁波测井反演中的应用

提出一种改进的阻尼型高斯牛顿优化算法,通过引入阻尼矩阵,对反演参数依其相对修改量不同而给以不同的阻尼作用,并将它用于高频电磁波测井资料的反演中.     

激光二极管相对于铯饱和吸收D2线的无调制扰动三次谐波锁频

将频率调制加在声光调制器上 ,用三次谐波探测法获得了铯原子D2 线的三阶微分饱和光谱。采用这种激光器无调制扰动方案结合三次谐波锁频技术 ,实现了 85 2nm的分布布拉格反射器半导体激光器相对于 6S1/2 F =4- 6P3 /2 F′ =5超精细跃线的频率锁定。由锁定后的频率误差信号估算 ,10s内激光频率起伏小于± 35 0kHz ,相对频率稳定度约 1× 10 -9。这种无调制扰动方案可以消除一般的饱和吸收稳频方法中由于直接对激光器进行频率调制而带来的额外频率噪声 ;三次谐波锁频技术的应用 ,还可有效地降低铯原子饱和吸收谱中剩余多普勒背景的影响     

Harmonics-to-Noise Ratio: An Index of Vocal Aging

Distinguishing between vocal changes that occur with normal aging and those that are associated with disease is an important goal of research in voice. Several acoustic measures have been used in an attempt to illuminate the integrity of the vocal mechanism, including harmonics-to-noise ratio (HNR), jitter, and fundamental frequency (F₀). HNR is a measure that quantifies the amount of additive noise in the voice signal; jitter reflects the periodicity of vocal fold vibration. In this study, measures of HNR, jitter and F₀ were used to compare vocal function in three groups of normally speaking women: young adults, middle-aged adults, and elderly adults. Significant differences in HNR emerged between the elderly women and the other two groups. F₀ differences were also apparent between the elderly group and the two younger groups; there were no significant differences in jitter between the three groups. HNR was found to be a more sensitive index of vocal function than jitter. The significant lowering of HNR evident in the elderly speakers may be attributable in part to medications taken by the majority of these elderly subjects.     

Study on Planar Whispering Gallery Dielectric Resonators. I. General Properties

Several basic properties of homogeneous planar Whispering Gallery dielectric resonators are investigated through a general approach. In particular the values for the minimum and maximum allowed radius, defined by irradiation and dielectric losses, respectively, are obtained in terms of the complex dielectric constant of the involved media. The same approach is employed in the analysis of the limit allowed frequencies of a fixed family of mode, leading to the definition of the ideal frequency band. The role of the transverse mode is then discussed, and the effective frequency band is introduced and determined both in simple disc and circular ring resonators. The extension of the effective band is limited at least by a factor 3, in terms of decades, in comparison to the extension of the ideal one; this limitation, due to the presence of transverse modes, can be overcome using suitable designed nonhomogeneous resonators, as discussed in a following companion paper.     

Dynamic response of permalloy/Cu/Co magnetoresistive sandwiches

The dynamic response of trilayer magnetoresistive permalloy/Cu/Co films was studied by high-frequency permeability spectra measurements. The resonance frequency is shown to depend on the interlayer copper thickness. This dependence is related to exchange coupling between permalloy and cobalt and the interaction field is estimated using the Landau–Lifschitz–Gilbert model.     

Probing buried interfaces with non-linear optical spectroscopy

The importance of buried interfaces in our everyday lives and in current scientific research is highlighted, along with experimental difficulty associated with studying such systems. We present an overview of the application of second harmonic generation and sum-frequency spectroscopy to the study of buried interfaces. Several examples from the current literature are presented, ranging from chemical and biological, to electrical and magnetic interfaces. The importance of this work in the context of ongoing research in these areas is discussed. Finally, we provide a snapshot of the state of the art in non-linear optical spectroscopy by mentioning several new directions that are likely to have a large impact on future research into the physics and chemistry of buried interfaces.     

Nd:Ca4ReO(BO3)3(Re=Gd,Y)晶体最佳激光、最佳倍频及最佳自倍频方向的确定

介绍了Nd:Ca4ReO(BO3)3(Re=Gd,Y)晶体最佳激光方向、最佳倍频方向的确定.综合考虑激光受激发射截面、抽运光吸收系数、有效非线性系数的各向异性,分析了自倍频性质的空间分布,并就此确定出最佳自倍频方向 关键词： Nd:Ca4ReO(BO3)3(Re=Gd Y)晶体 激光发射 倍频 自倍频     

小型录音室的建筑声学设计的讨论

本主要从小型语言录音室建筑结构出发，分析材料与声学规律的关系，从而建议设计实施经济合理、符合声学条件的小型录音室。     

工作点测量系统在合肥光源的应用研究

 介绍了利用合肥光源(HLS)的工作点测量系统进行一些束流参数的测量及其应用研究，这些参数包括工作点、β函数；自然色品以及中心频率。同时还进行了清洗电极对工作点的影响的测量。给出了一些测量结果，测量结果与理论计算值相当吻合。     

Thickness and stacking geometry effects on high frequency overtone and combination Raman modes of graphene

We investigate two high frequency Raman overtone and combination modes of graphene named 2D' and 2D + G bands, and located at ~3240 and ~ 4260 cm^–1, respectively. The graphene thickness and stacking geometry effects for these two modes are systematically studied. The features of the 2D' band, which arises from intravalley double resonance, are not sensitive to the variation of thickness with single Lorentzian peak and fixed linewidth. We explain it theoretically by calculating the phonon dispersion mode in k‐space and find that the flat band region of longitudinal optical phonon near Γ point is the mechanism leading to the 2D' band nonsplit. With the thickness increasing, the band position exhibits blueshift and the linewidth increases for the 2D + G band. With changing thickness and stacking geometry of graphene, the intensities of these two high‐frequency bands show obvious different evolution compared with that of G band. Copyright © 2012 John Wiley & Sons, Ltd.