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The complexity of the war and the density of high and new technologies have led to an increasing demand for the maintenance and support of space equipment in actual combat. The traditional maintenance support capability system is difficult to meet the dynamic and complex maintenance support needs. By analyzing the factors and relationships generated by the actual combat maintenance and support capability of aerospace equipment, the idea of constructing a capability system based on the decomposition of maintenance support activities is proposed, and the improved gray correlation analysis method is used to optimize, and the optimized maintenance support capability system is obtained. The research can provide a reference for the generation of actual combat maintenance support capability of aerospace equipment.

Renowned for their outstanding structural and electronic properties, two-dimensional (2D) polar materials are highly regarded as promising candidates for advanced optoelectronics and catalysis applications. Herein, based on the design principle of valence charge balance and layer stacking, we successfully designed 22 stable 2D polar monolayers with intrinsic built-in electric fields. The predicted monolayer, i.e., 2D MAN3, originates from the MA2N4 (M= V, Nb, Ta; A = Si, Ge) and has been widely studied in recent years. All of these monolayers exhibit semiconductor properties, with half displaying a direct band feature. Additionally, 2D MAN3 monolayer shows remarkable hole mobility (∼104 cm2 V–1 s–1) and optical absorption. Furthermore, the band edges of these monolayers not only facilitate the establishment of diverse interface contacts but also meet the requirements for photovoltaic water splitting. Our work not only significantly expands the MAN3 family but also provides valuable insights for its future research on optoelectronic applications. [ABSTRACT FROM AUTHOR]

Groundwater quality assessment is an essential study which plays important roles in the rational development and utilization of groundwater. Groundwater quality greatly influences the health of local people. However, most traditional water quality comprehensive assessment methods which have complicated formulas are difficult to apply in water quality assessment. In this paper, a novel method for groundwater quality assessment called set pair analysis was introduced and entropy weight was assigned to each index to improve the assessment model. The calculation steps are depicted in the paper and take groundwater quality assessment in Dongsheng City as a case study. The assessment results indicated that groundwater qualities in the study area were relatively good, Set Pair Analysis method, which was an optimal method for groundwater quality assessment and worth promoting, was easy to use and calculation processes which use almost all the relative information were simple, results were reasonable, reliable and intuitive.

The aim of this work is to assess the groundwater quality in Pengyang County based on an improved water quality index. An information entropy method was introduced to assign weight to each parameter. For calculating WQI and assess the groundwater quality, total 74 groundwater samples were collected and all these samples subjected to comprehensive physicochemical analysis. Each of the groundwater samples was analyzed for 26 parameters and for computing WQI 14 parameters were chosen including chloride, sulphate, pH, chemical oxygen demand (COD), total dissolved solid (TDS), total hardness (TH), nitrate, ammonia nitrogen, fluoride, total iron (Tfe), arsenic, iodine, aluminum, nitrite, metasilicic acid and free carbon dioxide. At last a zoning map of different water quality was drawn. Information entropy weight makes WQI perfect and makes the assessment results more reasonable. The WQI for 74 samples ranges from 12.40 to 205.24 and over 90% of the samples are below 100. The excellent quality water area covers nearly 90% of the whole region. The high value of WQI has been found to be closely related with the high values of TDS, fluoride, sulphate, nitrite and TH. In the medium quality water area and poor quality water area, groundwater needs some degree of pretreated before consumption. From the groundwater conservation view of point, the groundwater still need protection and long term monitoring in case of future rapid industrial development. At the same time, preventive actions on the agricultural non point pollution sources in the plain area are also need to be in consideration.

In order to satisfy the requirerment of image location accuracy for space TDICCD remote sensing camera at scroll imaging, a method of improving image location for scroll imaging is proposed. First, based on the principle of TDICCD remote sensing camera, the line period in normal imaging mode and scroll imaging mode is calculated respectively. Then, the reason is analyzed that image location error would be too large in scroll imaging mode after working a period of time, and the method of calculating the image location error is introduced by record three kinds of data: ringing edge time of line cycle signal, ringing edge time of line synchronous signal and the time difference between the above two signals. Finally, image location error is calculated. Experimental results indicate that the image location error is less than ground sample distance in an imaging process. It can satisfy the system requirement on image location accuracy. [ABSTRACT FROM AUTHOR]

The extreme changes in autumn rain have significant impacts on the ecological environment of Weihe River basin. Based on 117 autumn rain samples and corresponding meteorological data from 2015 to 2021 at Yangling located in the middle of Weihe River basin, we investigated the stable hydrogen and oxygen isotope composition and water vapor sources of precipitation. The results showed that, (1) extreme changes in autumn rainfall in the study area occurred frequently in recent years, which could be divided into extreme-high autumn precipitation year (HAP, 2021), general autumn precipitation year (GAP, 2015-2017, 2019-2020) and extreme-low autumn precipitation year (LAP, 2018) based on the autumn rain index (ARI); (2) the stable isotopes of different types of precipitation differed significantly, with a pattern of LAP>GAP>HAP for both δ 2 H and δ 18 O values. the variations of d-excess values and the slopes and intercepts of the meteoric water lines of autumn rain showed opposite trends. The main factor controlling autumn rain anomaly was not the local meteorological parameters, but the El Nino-Southern Oscillation and the Indian Ocean dipole events, which could explain 99% and 93% of the autumn rain isotopic variations, respectively. These coupling phenomena affected water vapor transport intensity of the marine air mass to the northwest inland, which determined autumn rainfall amount and the stable hydrogen-oxygen isotope composition. Our results would be helpful for improving the understanding of autumn rain anomalies in West China, and provide basic data and theoretical support for regional hydrological model building, would thereby better serve water resources management and disaster prevention and reduction.