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Because of its strong penetrating capability, the natural seismic receiving function has become the most widely used method for detecting crust-mantle structure. As the understanding of the structure and dynamic processes in the crust and upper mantle has advanced, the broadband seismic array with relatively large station spacing has become incompetent to the high-resolution imaging. The Dense Nodal Seismic Array (DNA), composed of hundreds of short-period portable digital high-frequency seismometers, offers a solution with station spacing as small as a few hundred meters, allowing for the collection of substantial observational data in a short time (1-2 months). Its advantages mainly include three aspects: (1) Good cross-ray-path coverage in the crust, conducive to improving imaging resolution; (2) Densely distributed ray-paths, facilitating noise suppression through coherent stacking of receiver functions, allowing for high-frequency receiver function imaging of crustal structures; (3) High efficiency due to the short observation time. Therefore, short-period dense array has become one of seismic observation approach commonly adopted in deep crustal structure research for only a few years. This paper mainly introduces the origin of short-period dense array in deep crustal structure exploration, and demonstrates its exploration effect and application in different tectonic domains through several typical exploration examples.

Abstract With the rapid increase of wind power penetration, the frequency indicators of power system, encompassing frequency deviation and rate of change of frequency (RoCoF), are prone to exceed the pertinent relay thresholds, thus leading to serious power outages. Wind farms can participate in primary frequency regulation (PFR) to alleviate the above problem. However, wind farms reserve capacity (WFRC) presented by overspeed control and pitch angle control is the important factor for frequency safety especially when large disturbance occurs, and it varies obviously in different conditions. Thus, WFRC should be utilized optimally to avoid insufficient or excessive response of wind farms in PFR. To overcome the challenge, this paper proposes frequency‐trajectory‐oriented control (FTOC) for wind farms based on a two‐fold optimization framework, seeking to obtain the best frequency control performances in PFR through realizing the optimal compromise between frequency results and the consumption of WFRC. First, when the frequency indicators deviate significantly from the normal values, the optimal frequency trajectory is planned periodically according to the local standards and operation conditions, thereby minimizing the total consumption of WFRC on the premise of frequency safety. Second, based on model predictive control and a real‐time power system parameters estimator, the total reference power of wind farms, which helps the frequency track the latest planned trajectory, is optimally distributed among wind generators according to their reserve capacity. In this case, through the optimal frequency trajectory planning and tracking, the new method in this paper not only effectively prevents the frequency results from exceeding the local standards under diverse conditions, but also finds the optimal balance among frequency indicators safety, frequency trajectory smoothness, and the reserve capacity consumption of wind power generators. Finally, the simulation results prove the effectiveness and advancement of FTOC.

The relationship of the crustal contact between the Indian and Eurasian plates is a key issue in understanding crustal thickening and the subduction of the Indian lithosphere beneath the Qinghai-Tibetan Plateau. Across the middle of the Yarlung-Zangbo Suture (YZS), we deployed an ∼450-km-long SN-trending wide-angle reflection/refraction profile to observe the P-wave velocity (vP) structure beneath the northern Himalaya and the southern plateau. Our results show that, 1. the high vP (∼7.1 ​km/s) indicates that the Indian lower crust extends no more than 50 ​km north of the YZS. 2. The lower crust beneath the southern part of the plateau features an extremely low vP (

The article reports on science research based on geology which informs about the seismological evidence for the earliest global subduction network with earliest evidence for subduction, which have been localized, does not signify when plate tectonics global phenomenon. Topics include investigated Paleoproterozoic time, for which seismic evidence is available from multiple continents; and high-density seismic array in North China to image the crustal structure that exhibits a dipping Moho.