Siyuan Zhao

Giant rock avalanche is extremely rare worldwide, while giant rock avalanche developed in suture zone has presented unique development characteristics. The suture zone is a product of plate moving and strong tectonic activity, where the appearance of a giant avalanche not only plays a barometer role for the regional disaster development environment but an indicator role for the complicated geological environment. In 2019-2021, the author has found a giant paleo-rock avalanche (name Basu avalanche) in the Bangonghu-Nujiang suture zone of the Tibetan Plateau. Some infrequent characteristics such as huge volume, development in nappe structure, and hyper-mobility (debris impact height > 600m) appeared for this giant rock avalanche. In this paper, based on the detailed investigation, 36Cl dating, and reconstructing the pre-avalanche terrain methods, the development, failure, and hyper-mobility of this giant rock avalanche have been analyzed. The result shows that: (1) The volume of the Basu avalanche is about 3.5×109m3, the residue is about 1.4×109m3 now. The avalanche occurred at 205.70±7.71ka B.P.(ka: millennium), subsequent the accumulation body occurred two times secondary landslides (name Duolasi landslide) at 17.57±0.72ka B.P. and 7.01±0.32ka B.P., respectively; (2) The nappe structure, formed from the uplift and orogeny process of the suture zone, controls the development and volume size of the Basu avalanche, while the strong earthquake is the biggest likely to trigger the avalanche finally failure because of the dense active faults distribution; (3) Because of the rich Ultrabasic clasts derived from the F2 fault and fine particles produced by cataclastic rock mass, the Basu avalanche formed the slide belt that thickness from centimeters to meters during the motion. The lubrication effect of the slide belt has dominated the avalanche debris's high-speed motion and hyper-mobility, the mechanism is that: due to the huge avalanche volume and induced the high pressure and closed slide belt environment, the slide belt fine-grain formed the lubrication layer with certain water involved, and the friction force sharply decreased; (4) Because of the Basu rock avalanche and the debris flow successive blocked the Leng River, the Leng River valley has experienced diversions process and the river valley from the ’S’ shape to approximate straight-line shape.

Mare Fecunditatis is a ~310,000 km² flat basalt plain located in the low-latitude area of the Moon. Plenty of volcanic features (multiple episodes of mare basalts, sinuous rilles, lava tubes, pyroclastic deposits, domes, irregular mare patches (IMP), ring-moat dome structures (RMDS), floor-fractured craters), tectonic features (grabens and wrinkle ridges), impact-related features, and other features (swirls, pit craters) are identified in Mare Fecunditatis. An in-situ mission to Mare Fecunditatis is scientifically significant to better understand the lunar thermal histories and other questions. All previous in-situ and human missions (Apollo, Luna, Chang’E) were limited to small areas, and no traverse longer than 40 km has been made yet. With the development of technology, long-distance movement will be possible in the future on the lunar surface, providing opportunities to explore multiple sites at one mission with complete documentation of the regional geology. Eight high-value targets (pit crater, IMPs, RMDSs, young basalts, high-Al basalts, pyroclastic deposits, swirls, and fresh craters) were found in Mare Fecunditatis, and a ~1400 km-traverse in 5 years is proposed to explore them to solve the most fundamental lunar questions.

Load mismatch becomes an urgent issue to be resolved in the design of RF PA circuit with the fast development of wireless communication technology. In this paper, we proposed a real-time waveform load pull technique for RF PA ruggedness test, which can be used for both fundamental and harmonic load mismatch and deliver accurate output waveforms. This technique has many advantages versus traditional passive load pull based techniques. Through rigorous experimental verification, it is proved that this technique is capable of providing comprehensive and meaningful information for the RF circuit Electro-Magnetic safety analysis and design.

The Rümker region (41–45°N, 49–69°W) is located in northern Oceanus Procellarum of the Moon. Mons Rümker is the most distinctive geological feature in the area. The region is characterized by prolonged lunar volcanism (Late Imbrian Period to Eratosthenian Period), forming multiple geologic units in the area, including very low‐Ti to low‐Ti mare basalts, high‐Ti mare basalts, and volcanic complexes. Each geologic unit has distinct element composition and mineral assemblages. The Rümker region, overlying the Procellarum KREEP Terrain, was selected as the landing region for China's Chang'E‐5 lunar sample return mission. Prelanding analyses of the geologic context and scientific potential are reported in this contribution. We conducted detailed geological mapping using image, spectral, and altimetry data. Fourteen geological units were defined, a geologic map was constructed, and the geologic history was outlined. The western mare units (Im1, Im2, and Im3) are Imbrian‐aged (~3.4–3.5 Ga) representing the major stage of lunar mare eruptive volcanism. The eastern young mare units (Em3 and Em4; <2 Ga) are among the youngest mare basalts on the Moon. They have never been explored in situ or studied in the laboratory. We suggest that samples returned from the eastern mare unit (Em4) could answer many fundamental questions and that this unit should be listed as the top priority landing site for Chang'E‐5 sample return mission.