Notes on the variability of reflected inner core phases

Recent events beneath Central America have produced excellent sets of inner core reflection （PKiKP phase） at high frequency recorded by USArray ranging from 18° to 30°. However, the amplitude of this phase displays considerable scatter with a factor of six or more. Such scatter has been attributed to upper-mantle scattering and the Inner Core Boundary （ICB） in combination. Here, we show that neighboring events share upper-mantle scatterers beneath the receivers, and their ratio allows a clearer image of deep earth structure. Alter confirming some of the measured variation is indeed due to deep structure, we stacked nearby traces to reduce fine scale variations which are mostly due to shallow structure. Then, the remaining relatively large scale variation pattern of PKiKP phase is caused by the inner core boundary, as demonstrated by numerical experiments. After migration of data to the 1CB, we observe a consistent image. We find such a pattern can be explained by a patch of mushy material of a few kilometers high where the material changes gradually from that of the outer core to that of the inner core.

A Study on Reflection Phase Time of Particles Passing through a Potential Well

To understand the physical meaning of phase time further more, we discuss the reflection phase time of quantum-particles passing though a potential well It is shown that the reflection phase time is equal to the transmission phase time in value and negative under certain conditions for a square potential well by analyzing While quantum-particles passing through the potential well, we think that this course can be described only with the velocity of energy of quantum mechanics whether or not they are reflected or transmitted eventually

Complex spherical-wave elastic inversion using amplitude and phase reflection information

Unlike the real-valued plane wave reflection coefficient(PRC)at the pre-critical incident angles,the frequency-and depth-dependent spherical-wave reflection coefficient(SRC)is more accurate and always a complex value,which contains more reflection amplitude and phase information.In near field,the imaginary part of complex SRC(phase)cannot be ignored,but it is rarely considered in seismic inversion.To promote the practical application of spherical-wave seismic inversion,a novel spherical-wave inversion strategy is implemented.The complex-valued spherical-wave synthetic seismograms can be obtained by using a simple harmonic superposition model.It is assumed that geophone can only record the real part of complex-valued seismogram.The imaginary part can be further obtained by the Hilbert transform operator.We also propose the concept of complex spherical-wave elastic impedance(EI)and the complex spherical-wave EI equation.Finally,a novel complex spherical-wave EI inversion approach is proposed,which can fully use the reflection information of amplitude,phase,and frequency.With the inverted complex spherical-wave EI,the velocities and density can be further extracted.Synthetic data and field data examples show that the elastic parameters can be reasonably estimated,which illustrate the potential of our spherical-wave inversion approach in practical applications.

High Gain of UWB Planar Antenna Utilising FSS Reflector for UWB Applications

In this paper,a high gain and directional coplanarwaveguide(CPW)-fed ultra-wideband(UWB)planar antenna with a new frequency selective surface(FSS)unit cells design is proposed for UWB applications.The proposed UWB antenna was designed based on the Mercedes artistic-shaped planar(MAP)antenna.The antenna consisted of a circular ring embedded with three straight legs for antenna impedance bandwidth improvement.The modelled FSS used the integration of a two parallel conductive metallic patch with a circular loop structure.The FSS provided a UWB stopband filter response covering a bandwidth of 10.5 GHz,for frequencies from 2.2 to 12.7 GHz.The proposed FSS had a compact physical dimension of 5 mm×5 mm×1.6 mm,with a printed array of 19×19 FSS unit cells.The FSS unit cells were printed on only one side of the dielectric FR4 substrate and placed as a sandwich between the antenna and the reflector ground plane.An equivalent circuit configuration(ECC)was used to verify the FSS unit cell structure’s performance.The simulated results indicated that the UWB MAP antenna and FSS reflector provided a fractional bandwidth of 136%and a high gain of 11.5 dB at 8.5 GHz with an acceptable radiation efficiency of 89%.Furthermore,the gain was improved across the operating band and kept between 8.3 and 11.5 dB.The proposed antenna was in good agreement between theoretical and experimental results and offered a wide enough bandwidth for UWB and vehicle applications.

Study of Temperature Enhancement of the Photorefractive Effect in Ce：Fe：LiNbO_3 Crystal

in the range of 20 to 120 ℃, the two-beam coupling exponential gain coefficient and the four-wave mixing phase conjugation reflectivity have been investigated. It is shown that the values such as the gain, the phase conjugation reflectivity and the response speed increase as the temperature increases. At about 55, 71 and 110℃, extraordinary enhancement of the gain and the phase conjugation reflectivity were observed.The mechanism is analyzed by the phase change in the crystal at these temperatures.