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Approximately two-thirds of Earth's outermost shell is composed of oceanic plates that form at spreading ridges and recycle back to Earth's interior in subduction zones. A series of physical and chemical changes occur in the subducting lithospheric slab as the temperature and pressure increase with depth. In particular, olivine, the most abundant mineral in the upper mantle, progressively transforms to its high-pressure polymorphs near the mantle transition zone, which is bounded by the 410 km and 660 km discontinuities. However, whether olivine still exists in the core of slabs once they penetrate the 660 km discontinuity remains debated. Based on SKS and SKKS shear-wave differential splitting times, we report new evidence that reveals the presence of metastable olivine in the uppermost lower mantle within the ancient Farallon plate beneath the eastern United States. Such differential splitting times were attributed to anisotropy in the D” layer. Spatial coherency analysis and consistency between the area with differential splitting times and that with higher than normal seismic velocities favor an uppermost lower mantle origin of the differential times. We estimate that the low-density olivine layer in the subducted Farallon slab may compensate the high density of the rest of the slab associated with the low temperature, leading to neutral buoyancy and preventing further sinking of the slab into the deeper part of the lower mantle., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

On March 31, 2020, an M_w 6.5 earthquake struck near Stanley, Idaho. More than 35% nondouble-couple component in long-period point-source solutions indicate a more complex source than slip on a planar fault. Using an integrative analysis of seismological and geodetic data, we find that the Stanley earthquake ruptured a pair of opposing-dip faults offset by a 10-km-wide step, including an unmapped northern subfault with predominantly strike-slip faulting and a southern subfault subparallel to the Sawtooth fault with predominantly normal faulting. This converging fault geometry allowed the rupture to traverse a surficial 10-km-wide step, which is greater than the limiting dimension (3–4 km) that commonly ceases earthquake ruptures. This study reveals that a composite rupture process with strike-slip and normal faulting is typical for earthquakes located near the northern boundary of the Centennial Tectonic Belt (CTB), which is distinct from the predominantly normal faulting in the central CTB.

In order to solve the problem of encrypted traffic identification, the identification method based on dynamic time warping (DTW) and k-nearest neighbor (KNN) for the encrypted network behaviors was proposed. The method took the encrypted Twitter traffic as an example of research, and a large number of encrypted Twitter network behaviors were deeply analyzed, and then the features representing the encrypted network behaviors were extracted, and the specific encrypted network behavior module database based on DTW and KNN were established, and the DTW between the collection data set and the module database were calculated, and then were normalized, and then the encrypted network behaviors were classified by comparing with the preset empirical threshold, and the distance information were also considered by DTW algorithm, at the same time, the influence of TCP retransmission and duplicate ACK packets can be effectively eliminated by the dynamic time warping algorithm. In order to overcome the noise interference of the similar data traffic except the distance information, the similar filtered data packets were classified as the true behavior or the false behavior by KNN algorithm, and then the encrypted network behaviors were identified automatically and in real time, compared with the only correlation coefficient method or only DTW method, the online correct recognition rate by DTW and KNN has been greatly increased and reached to about 93%, and the missed detection rate is almost same with the traditional methods, the experiments and actual project applications showed that the proposed method was effective.

This paper reports the preparation and the study of mechanical, electrical and tribological properties of Ag-based electrical contact composites containing silver coated transition metal selenide. It is found that the hardness and strength of Ag-based electrical contact composites containing the transition metal selenide are improved, and the resistivity and the contact resistance are reduced. It is also found that Ag and Cr have good interfacial bonding strength by X-ray diffract meter. Through scanning electron microscope, we can find that the silver coated transition metal selenide is evenly distributed in Ag matrix and it has good interface bonding with Ag. Furthermore, the tribological test results show that the tribological properties of Ag coated the transition metal selenide is slightly affected, but it still shows excellent lubricity.

15co(x)li/ac catalysts promoted by different trace amounts of li doping were prepared by incipient-wetness impregnation. the catalysts were investigated by means of co hydrogenation and characterized by x-ray diffraction (xrd), temperature-programmed reduction (h-2-tpr), and temperature-programmed surface reaction (tpsr) techniques. the results show that co conversion, selectivity towards c5+ hydrocarbons, selectivity towards mixed linear alpha-alcohols and the distribution of higher alcohols (c6+oh) in the alcohol products were improved by adding trace amounts of li to the 15co/ac catalysts. xrd, h-2-tpr, and tpsr results indicate that the existence of trace amounts of li promotes weak interaction between li and co species, disperses the co species of the catalysts, decreases the size of metallic co particles, and promotes the formation of co2c species.

The effect of Li promoter on the catalytic performance of the activated carbon(AC) supported cobalt catalysts(Co/AC) for CO hydrogenation was investigated by means of CO hydrogenation,X-ray diffraction(XRD),temperature-programmed reduction(H2-TPR),and temperature-programmed desorption of adsorbed CO(CO-TPD).The results showed that the addition of Li significantly suppressed the formation of gaseous hydrocarbons and remarkably improved the selectivities for higher hydrocarbons(C5+) and mixed linear α-alcohols(C1-C18) of CO hydrogenation over the Co/AC catalyst.However,the activity of CO hydrogenation decreased gradually with the increase of Li loading in the Co-based catalyst.H2-TPR and CO-TPD results illuminated that the existence of Li decreased the reducibility of Co2+ and the ability of CO dissociation,which was the rate-determining step.XRD results indicated that the existence of Li promoter enhanced the formation of Co2C species.

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