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Abstract [Objective] The Northern Hengduan Mountains are rich in biodiversity. Over the last 10 years, there have been many reports of the biodiversity of the region. The team conducted a survey of plant diversity and vegetation structure in Northern Hengduan Mountains from June to August 2023. [Methods] Through field investigation and collection and photograph of plants, as well as preparing, classifying, and identifying specimens. [Results] Eight newly recorded species were reported from Chaya of Changdu in the Northern Hengduan Mountains in Xizang. They were Ephedra minuta Florin (Ephedraceae), Caragana korshinskii Kom. (Fabaceae), Rhododendron luhuoense H. P. Yang (Ericaceae), R. orthocladum var. longistylum Philipson et M. N. Philipson (Ericaceae), R. thymifolium Maxim. (Ericaceae), R. nivale Hook. f. subsp. australe Philipson et M. N. Philipson (Ericaceae), Artemisia capillaris Thunb. (Asteraceae), and Chenopodiastrum gracilispicum (H.W.Kung) Uotila (Amaranthaceae) [Conclusion] The discovery of the newly distributed plants is an important supplement for the flora of the Hengduan Mountains in Xizang. The voucher specimens are stored in the herbarium of Yibin University

In the process of upper coal mining, the floor condition may be incomplete because of the lower coal goaf, and the change of the floor condition has an obvious influence on the floor failure in the upper coal mining. Based on the micro-seismic monitoring data of 15249S working face in Jiulong Mine, the activity of floor events, the ratio of roof to floor, energy and other parameters are statistically analyzed. The results show that: when the lower coal is a gob, the activity of floor events is strong and the disturbance depth is large when the upper coal is mined. With the advance of mining location and the change of underlying coal seam conditions, the frequency ratio of floor and roof events changes greatly, and its change rule is consistent with the formation of water channel. The proportion of micro-seismic events increased by 16.49% and decreased by 10.92% when the bottom floor failure depth was 0-5 m and 5-20 m respectively. In the process of overlying coal stoping approaching the underlying stoping contact roadway, the development location of large energy events extends from shallow to deep. The floor safety evaluation system is constructed by using the parameters of floor warning layer event activity, floor and roof event ratio, distance from the stoping line of the underlying coal seam and vertical energy density. The danger zone before and after the stoping position of the underlying working face is a high risk factor, which can be combined with the changes of safety evaluation parameters for early warning and strengthening hydro-geological observation.

For the problem of air-to-air missile cooperative attack on high-speed maneuvering target, a multi-missile cooperative guidance law with consistent attack time is proposed. Firstly, the geometric model of engagement between each missile and target is established in the longitudinal plane, and the relationship between the radial and normal guidance laws of line of sight and the normal acceleration of velocity is analyzed. Then, the fixed time cooperative control law is designed, and based on the line of sight dynamic equation, the robust cooperative guidance law with attack-time constraint is established by using adaptive law and integral sliding mode algorithm to ensure that multiple missiles hit the maneuvering target at the same time. Through numerical simulation, the difference of cooperative time and miss distances are 0.001 s and 0.01 m respectively. The final results verify the effectiveness and rationality of the fixed-time cooperative guidance law.

[Objective] As a typical structure of carbonate rocks, the formation of stylolites is of great significance for the enrichment of organic matter and fluid migration within the carbonate rock itself. However, there is currently no in-depth research on the source of organic matter and the mechanism of fluid transport in stylolites. [Methods] This study collected carbonate core samples containing stylolites from the Dachigan structural belt in the eastern Sichuan Basin. The stylolites and matrix were respectively subjected to organic carbon and pyrolysis (Rock-Eval), common thin section observation, thin section observation under fluorescent light, whole rock X-ray diffraction, carbon and oxygen isotopes and scanning electron microscopy (SEM) and other testing items. [Results and Conclusions] The organic matter occurred in the stylolites is mainly in the form of three types including soluble organic matter, pyrobitumen, and bitumen, indicating that the organic matter in the stylolites is mainly the secondary migrated organic matter. Secondary dolomite and pyrite are well developed in the stylolites that the intercrystalline pore spaces and fractures are retained, thereby to provide good conditions for the accumulation and migration of oil and gas. The strong cementation on the contact between the stylolites and matrix and the formation of secondary minerals nearby may be the results of fractionation when the hydrocarbon fluid migrates from the matrix to stylolites. Through analysis, it is believed that the strong cementation at the contact interface between the suture and the matrix, as well as the formation of nearby secondary minerals, are the reasons for the fractionation effect of hydrocarbon fluids when migrating from the matrix to the suture. Through this study, it was found that during the development of sutures, the organic matter in the sutures will crack and form natural gas during the high evolution stage. When mixed with natural gas of other origins, it will affect the identification of natural gas sources ; When the suture line serves as a migration channel for crude oil, the fractionation effect on crude oil can also cause certain difficulties in identifying the source of crude oil. Therefore, appropriate biomarker comparison parameters should be selected to analyze the oil source relationship, and the spatial variation pattern of crude oil properties should also be considered. [ABSTRACT FROM AUTHOR]