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[en] Automatic detection of P wave very important to speed up the data analysis rather than manual. One of the methods used for P wave detection is Short Term Average/Long Term Average (STA/LTA). The P wave is detected automatically by STA/LTA when the STA/LTA ratio exceed from the given threshold value. This algorithm has been displayed in the form of Graphical User Interface (GUI) for make it easy to use. We have experimented the GUI to an earthquake on December 24, 2014 that recorded by ACEHSEIS network. We use four vertical components from different seismic stations and one of it has a noisy waveform. The P-wave was obtained when the STA/LTA ratio exceeded the threshold value at 0.35. We also determine the P wave with the manual detection and Pphase Picker as the comparison to our GUI of STA/LTA. The result shows that, our GUI of STA/LTA method can be used determine P wave arrivals although the waveform is noisy but the program cannot be used to determine the relatively minor phase of P wave arrivals. While the results of Pphase Picker is opposite of STA/LTA. (paper)
[en] Different from the usual tetraquark assignment to charged Z(3885) and Z(4025) charmoniumlike structures, in this letter we propose a universal non-resonant explanation to decode these Z’s, which is based on a special dynamical behavior of ee→Dπ. Our study shows that Z(3885) and Z(4025) are only the reflection from the P-wave charmed meson D(2420) involved in ee→Dπ. Obviously, the present work provides a unique perspective, which can be examined by future experiments like BESIII and BelleII.
[en] The pure P-wave equation for modelling and migration in tilted transversely isotropic (TTI) media has attracted more and more attention in imaging seismic data with anisotropy. The desirable feature is that it is absolutely free of shear-wave artefacts and the consequent alleviation of numerical instabilities generally suffered by some systems of coupled equations. However, due to several forward–backward Fourier transforms in wavefield updating at each time step, the computational cost is significant, and thereby hampers its prevalence. We propose to use a hybrid pseudospectral (PS) and finite-difference (FD) scheme to solve the pure P-wave equation. In the hybrid solution, most of the cost-consuming wavenumber terms in the equation are replaced by inexpensive FD operators, which in turn accelerates the computation and reduces the computational cost. To demonstrate the benefit in cost saving of the new scheme, 2D and 3D reverse-time migration (RTM) examples using the hybrid solution to the pure P-wave equation are carried out, and respective runtimes are listed and compared. Numerical results show that the hybrid strategy demands less computation time and is faster than using the PS method alone. Furthermore, this new TTI RTM algorithm with the hybrid method is computationally less expensive than that with the FD solution to conventional TTI coupled equations. (paper)
[en] The purpose of this work was to study the seismic attributes of the Podvodnikov Basin basement. It was found that these attributes, first of all, P-wave velocities of 5.9–6.2 km/s, the ratio VP/VS = 1.71, and the diffraction nature of the reflections from the basement indicate that the basin has a continental origin and that its tectonic development began at the pre-oceanic stage of evolution of the Arctic.
[en] We describe the progress made and some of the difficulties encountered in measuring the solar rotation rate with p-modes of degree 100 <∼ l <∼ 400, using a set of high-resolution solar images taken at Big Bear Solar Observatory. The main conclusion drawn from an analysis of one day of data is that the equatorial angular velocity is essentially equal to the observed surface rate over the radius range 0.87 ≤ r/R ≤ 0.99 to within a few percent. Because of likely systematic errors at the 1% level these data do not allow us to distinguish between a surface rotation rate equal to that measured using magnetic tracers and that based on the Doppler shift of photospheric spectral lines
[en] We consider 16 earthquakes with Mw = 4.2–5.2 that occurred in the south-eastern part of the Laptev Sea shelf, Lena River Delta, and North Verkhoyanye (Russia) in 1990–2014. Focal mechanisms, scalar seismic moments, moment magnitudes, and hypocentral depths of the seismic events have been calculated from the data on amplitude spectra of surface waves and P wave first-motion polarities. The obtained results sufficiently implement the existing dataset on reliable earthquake source parameters for the study region and prove the change of the stress-strain state of the crust from extension on the Laptev Sea shelf to compression on the continent providing finer spatial details of the deformation field in the transition zones such as Buor-Khaya Bay and the Lena River Delta.
[en] A vertical short period seismological array was operated for six months in earstern Senegal. Large P wave travel-time anomalies are in fairly good relation with the gravity and geological features. Two-dimensional inversion of the data shows the existence of a major vertical discontinuity extending from the surface to 150-200 km depth. The other heterogeneities are mainly located in the crust and related to specific segments of the regional geology: craton, Mauritanides and Senegalo-Mauritanian basin. The main discontinuity dipping to the east is interpreted as the trace of an old subduction slab. We propose the following geodynamical process to explain the formation of the Mauritanides orogenic belt: continental collision after opening of a back-arc marginal basin in late Precambrian and its closure until Devonian
[en] In this paper, we present a new analysis on the P-wave charmonium annihilation into two photons up to next-to-next-to-leading order (NNLO) QCD corrections by using the principle of maximum conformality (PMC). The conventional perturbative QCD prediction shows strong scale dependence and deviates largely from the BESIII measurements. After applying the PMC, we obtain a more precise scale-invariant pQCD prediction, which also agrees with the BESIII measurements within errors, i.e. R = ()/ () = 0.246 ± 0.013, where the error is for (M) = ± 0.016. By further considering the color-octet contributions, even the central value can be in agreement with the data. This shows the importance of a correct scale-setting approach. We also give a prediction for the ratio involving → γγ, which could be tested in future Belle II experiment.