Journal of University of Chinese Academy of Sciences

Potoushan Kaolin Deposit in the middle of the Greater Khingan Range: identification of lithocaps and its significance

SONG Guoxue, QIN Zhangwei, ZHANG Daiyue, ZHENG Fangshun, XIONG Yuxin

2025, 42 (3): 289-303. DOI: 10.7523/j.ucas.2024.065

The area of volcanic and plutonic rocks in the Greater Khingan Range accounts for about 75%, characterized by the development of copper, molybdenum, tin, lead zinc, gold and silver, and rare metal minerals related to magmatic and hydrothermal activities. The middle section of the Greater Khingan Range, where the Potoushan Kaolin Deposit is located, mainly develops a compound mineralization system consisting of porphyry type mineralization, epithermal type mineralization, cryptoexplosive breccia type mineralization, and skarn type mineralization, but its overall exploration level is relatively low. Samples from the mining pit and shallow drill cores of the Potoushan kaolin mine have been identified minerals such as kaolinite, dikaite, alunite, pyrophyllite, microveined quartz, chalcedony quartz, sericite, chlorite, boehmite, gypsum, barite, pyrite, sphalerite, tellurite, pyrargyrite, cinnabar, limonite, etc., with the characteristic of developing low-temperature advanced argillation such as kaolinization, dickitization, alunitization, clayification, and silicification (chalcedony quartz), belonging to the top lithocap of deep porphyry-epithermal system. Based on the identified typical altered minerals, trace metal minerals, and four types of hydrothermal breccia within the mining area, it is speculated that there may be a potential ore bearing magma-hydrothermal system in the deep of Potoushan lithocaps. For the Greater Khingan Range, the extensive magmatic activity from the Paleozoic to Mesozoic and the moist and thick forest cover provided sufficient conditions for the development and preservation of lithocaps. It is suggested that future geological research and exploration work should pay more attention to lithocap for discovering more lithocaps, identifying their altered minerals, and researching their genetic mechanisms, to provide theoretical supports for further exploration of potential ore bearing magma-hydrothermal systems in the region.

Aerodynamic characteristics of deforming bat-like wing in forward flight

ZHU Bowen, YU Yongliang

2025, 42 (3): 304-314. DOI: 10.7523/j.ucas.2023.051

Abstract ( 224 ) PDF (0KB) ( 0 )

A simplified geometric model of a bat wing was utilized to study its morphology and deformation, along with its aerodynamic characteristics, using computational fluid dynamics methods. A model was established with a parallelogram-shaped inner wing and a combined triangular outer wing. The wing deformations were categorized into four types:area variation, outer wing bending, chordwise cambering, and wing twisting. Two flight modes, slow and fast, were defined based on experimental data. The results demonstrate that the aerodynamic forces acting on the bat wing model in both slow and fast flight modes are similar in spatial-temporal distribution, with both lift and thrust generated during the downstroke phase. The forces during the upstroke phase are comparatively smaller. Thrust is generated entirely by the outer wing, whereas lift is generated by both the outer and the inner wings. Furthermore, it was found that slow flight achieves velocity adaptation primarily through angle-of-attack adjustments, supplemented by minor flapping frequency modulation. In contrast, fast flight relies predominantly on frequency adjustments, with fine-tuning of the angle of attack to maintain force equilibrium across different speeds. The analysis of the aerodynamic forces acting on the deforming bat wing contributes to a more profound comprehension of the mysteries of bat flight.

J/ψ+1jet inclusive production process at the LHC

SUN Liping

2025, 42 (3): 315-321. DOI: 10.7523/j.ucas.2024.048

Abstract ( 83 ) PDF (0KB) ( 0 )

For J/ψ+1jet inclusive production at the large hadron collider, within the non-relativistic quantum chromodynamics framework, in this work a full next-to-leading order calculation with the anti-kt algorithm for the jet is presented. The J/ψ is considered to be not contained in the jet. The predictions are made for the total cross section, J/ψ transverse momentum distribution, jet transverse momentum distribution and the J/ψ jet rapidity difference distribution for this process. It is found that the process is detectable in the experiment, and the color-octet long distance matrix elements(LDMEs) fitted in the J/ψ inclusive production by different groups are not consistent in the J/ψ+1jet inclusive production process, which makes a reexamination for the fit of the J/ψ LDMEs necessary.

Oil compatibility and characteristics of insulating paper materials for new energy vehicle drive motors

LIU Rui, ZHANG Shengde, WANG Zhenxing

2025, 42 (3): 322-327. DOI: 10.7523/j.ucas.2024.022

Abstract ( 230 ) PDF (0KB) ( 0 )

According to the T/CEEIA 415 standard, taking the drive motor slot insulating material as the research object, three kinds of interstitial aramid insulating papers with 0.25 mm thickness are selected for the oil compatibility test, and based on the changes of the physical, chemical, electrical, and mechanical properties of the insulating paper surfaces in different cycles, the degree of damage and the degradation factors of the materials are elaborated in detail. The results indicate that in the oil compatibility test, the porous structure and surface capillarity enhance the densification of the paper-based structure in the short term, which is beneficial to the electrical performance. However, with the increase of the test time, the diffusion of moisture in the automatic transmission fluid in the oil-paper insulating system is intensified, which triggers the formation of insulating defects and results in the attenuation of the mechanical strength. When screening insulation materials, changes in mechanical properties are more intuitive and accurate. In addition, due to the destruction of the hydrogen bond stabilizing configuration, the amide bond and the C＝O bond strength are changed, and the dielectric properties of the lower density paper deteriorate significantly.

Effects of agricultural activities on soil inorganic nitrogen along an altitudinal gradient in Motuo, Southeastern Xizang, China

LEI Haojing, XU Ri, QU Songbo, SHAMA Ribu, LI Fengzi, ZHANG Lin, LIANG Eryuan

2025, 42 (3): 328-338. DOI: 10.7523/j.ucas.2023.043

Abstract ( 107 ) PDF (0KB) ( 0 )

Soil inorganic nitrogen (SIN, NH⁺₄-N, and NO^-₃-N) is a vital indicator of soil N supply. Studying the current status of farmlands’ soil inorganic nitrogen (SIN) on the Qinghai-Xizang Plateau is important to achieve the sustainability of plateau agriculture development. Ten pairs of farmland and forest soils were collected along the sampling gradient from 800 to 2 000 m (a.s.l.) in Motuo of southeastern Xizang, to investigate the effects of agricultural activities on SIN and clarify the environmental drivers of SIN. The results have shown that human activities significantly changed the concentration and spatial distribution pattern of SIN in farmlands. The topsoil (0-10 cm) was vulnerable to human activities. NH⁺₄-N concentration of topsoil decreased significantly and NO^-₃-N concentration increased significantly after reclamation. The SIN of the forests did not differ significantly among layers, but large differences were seen in the farmlands’ SIN among layers. SIN in forest ecosystems was influenced by altitude, soil temperature, soil moisture, and pH value, while agricultural ecosystems were not sensitive to environmental factors. The change amount of SIN after reclamation was mainly determined by soil temperature and soil pH value. In conclusion, reasonable agricultural management is necessary to achieve sustainable development of regional agriculture.

An empirical study on the relationship between regional innovation capacity and economic development level in China

CAO Sha, YAN Mengxue, REN Mei, ZHANG Yu

2025, 42 (3): 339-349. DOI: 10.7523/j.ucas.2023.078

Abstract ( 369 ) PDF (0KB) ( 0 )

The study uses factor analysis, coupled coordination degree model, the Theil index, vector autoregression model, and other methods, and combines geographic spatial expressions to make a specific analysis of the coordinated benefits of China’s regional innovation capacity and economic development level as well as the dynamic evolution process of the two from 2002 to 2020. The results found that: 1) From 2002 to 2020, China’s regional innovation capacity and economic development level showed a synchronous growth trend, and the coupling coordination changed from weak to strong, roughly going through a temporal evolution process of “lagging coordination (2002-2006) → coordinated transition (2008-2010) → coordinated development (2012-2020) ”, showing the stage characteristics of tending to high-quality coordination transition. 2) Spatially, the degree of coupling coordination decreases from the coast to the interior, showing obvious characteristics of a step-like distribution. The Theil index fluctuates between 0.033 6 and 0.071 2, with small regional spatial differences and a decreasing trend. The disparity between groups is more significant than the disparity within groups. The intra-group gap and the contribution rate of the eastern and western regions are significantly higher than those of the central and northeastern regions, and both have a stronger influence on the overall geographical differences across the country. 3) There is a long-term stable equilibrium relationship between regional innovation capacity and economic development level, and regional innovation capacity is not the Granger cause of economic development level, but regional innovation capacity has a more significant contribution to China’s economic development level, and its contribution rate to economic development level is over 50%.

A method to extract forest cover information by fusing Transformer and UNet

LIAO Lingcen, LIU Wei, LIU Shibin

2025, 42 (3): 350-360. DOI: 10.7523/j.ucas.2023.049

Abstract ( 229 ) PDF (0KB) ( 0 )

Forest cover information extraction is one of the essential tasks in forest remote sensing applications, which is of great significance for forest resource management, ecological environment protection, and climate change research. Traditional convolutional neural network-based methods can effectively extract local features, but struggle to capture long-range dependencies and global context information. To address this issue, we propose a method for forest cover information extraction that fuses Transformer and UNet, referred to as DiUNet. This approach embeds Transformer modules into the UNet network to enhance its perception of long-range dependencies and global context information. Meanwhile, considering the fragmentation, irregularity, and inconsistent scale of forest cover information, our method enhances the model’s ability to capture spatial information by using relative position encoding to increase the positional information, enabling the model to capture features at different levels and scales. We constructed a forest cover information dataset based on Landsat 8 and CDL data layers and conducted in-depth experimental analyses on this dataset. In the comparative experiments, DiUNet achieved the best results in accuracy, recall, F₁ score, intersection-over-union, and frequency-weighted intersection-over-union indices, which were 91.22%, 92.66%, 91.94%, 85.08%, and 81.65%, respectively. The model also performed well in generalization experiments. The experimental results show that the DiUNet method outperforms existing methods in forest cover information extraction and has high robustness and generalization capabilities.

A Scanning strategy optimizing method for spaceborne squint sliding spotlight SAR based on particle swarm optimization

GONG Liwei, LI Fei, HAN Xiaodong, WANG Wei

2025, 42 (3): 361-370. DOI: 10.7523/j.ucas.2023.056

Abstract ( 92 ) PDF (0KB) ( 0 )

In view of the significant spatial variance in the azimuth resolution of traditional spaceborne sliding spotlight SAR, this paper proposes a scanning strategy optimizing method for spaceborne squint sliding spotlight SAR based on particle swarm optimization. The proposed method can basically eliminate the spatial variance of azimuth resolution in SAR images and improve the accuracy of localization and identification when SAR images are used for target identification. Considering that traditional particle swarm optimization is prone to fall into local optimum when optimizing the scanning strategy, this paper proposes an improved particle swarm optimization in which a parameterized model of the sliding factor, whose parameters are solved using particle swarm optimization, is established and a neighborhood search algorithm is integrated so that the ability of the algorithm to reach the optimum is enhanced. Simulation results validate the effectiveness of the proposed method.

News information mining and price prediction of individual stock based on DTW-SACP-LSTM model

WANG Ziping, JIN Baisuo

2025, 42 (3): 371-381. DOI: 10.7523/j.ucas.2023.069

Abstract ( 171 ) PDF (0KB) ( 0 )

Aiming at the rapid changes and complex relations in the stock market, this paper proposes a stock price prediction method based on individual stock news. First, through dynamic time warping algorithm，the benchmark sequence with the highest similarity to the target individual stock sequence is found, and then we can extract the length and time of news impact through smooth-and-abrupt change point model, which is converted into time series data. We introduce the relationship between stocks into time series forecasting through statistical models, examine the relationship between news influence and historical stock price data, and combine news influence with individual stock data for price forecasting by using long-and-short-term memory network. The results show that the stock sector’s influence of news in the technology sector is the most obvious. Compared to existing stock prediction methods, the prediction performance of the fusion model has been improved, and the prediction accuracy has decreased slightly over time. The fusion model can more accurately describe the changes in stock prices, achieving an average return of 14.50% under the conditions of simulating investment strategies.

Beam hopping scheduling strategy of LEO communication satellite based on improved genetic algorithm

ZHANG Panpan, CHANG Jiachao, ZOU Cheng, LI Guotong

2025, 42 (3): 382-391. DOI: 10.7523/j.ucas.2023.054

Abstract ( 290 ) PDF (0KB) ( 0 )

Low earth orbit (LEO) communication satellites can break through terrain constraints and work with 6G to build an integrated space-ground information network. In terms of the beam scheduling problem of satellites for fixed terminals on the ground, a beam scheduling strategy that can achieve dual optimization of interference and delay is proposed, considering that the uneven distribution of global user demands exists. The model with the optimization goal of minimizing the queuing delay and co-channel interference is constructed, combining with constraints such as transmit power as well as carrier-to-noise ratio. By means of step-by-step optimization, a beam-hopping scheme including demand clustering, time slot allocation and beam position matching is designed. When it comes to the interference optimization problem in the beam position matching process, a genetic algorithm-based chromosome crossover mechanism of “beam position self-crossover within a cluster” is proposed. The simulation results show that the improved genetic algorithm can reduce the co-channel interference by 32% to 58% compared with the other algorithms. Besides, the proposed strategy can schedule the beam within the resource allocation period while achieving dual optimization of delay and interference.

Compression-sensing-based algorithm for the azimuth interrupted data reconstruction of spaceborne IFMCW SAR

ZHONG Shengyiliu, QIAO Ming, LIU Yunlong, ZHANG Tong

2025, 42 (3): 392-402. DOI: 10.7523/j.ucas.2023.038

Abstract ( 125 ) PDF (0KB) ( 0 )

The interrupted frequency modulated continuous wave (IFMCW) SAR is an economical and practical solution for the development of light-duty and miniature spaceborne synthetic aperture radar (SAR) systems due to its light weight, small size, low power consumption, and low data rate. However, data interruptions occur in the received azimuthal signals due to the alternation between the “transmit” and “receive” modes of IFMCW SAR, which lead to pseudo-peaks on both sides of the target in the imaging result. In this paper, a compression sensing-based azimuthal interrupted data reconstruction method for IFMCW SAR is proposed, employing stage-wise orthogonal matching pursuit (StOMP) and sparsity adaptive matching pursuit (SAMP) to azimuthal data reconstruction for the first time. The proposed method solves the problem of the existing algorithm, which requires sparsity as a priori knowledge. In addition, the method optimizes the SAMP structure, which improves the applicability of the algorithm on IFMCW SAR’s data reconstruction. The effectiveness of the proposed algorithms is verified by processing both simulated point target and ground truth echo data with unknown sparsity. Furthermore, the processing speed and reconstruction effect are compared with the original algorithm, revealing the good performance of the improved SAMP algorithm in sparse scenarios and the advantage of StOMP in complex scenarios.

Investigation of pinned evaporation droplets under different wind velocity

LI Zilong, QIN Jun, TAO Yuequn, HE Naifeng, LIU Qiusheng, ZHU Zhiqiang

2025, 42 (3): 403-411. DOI: 10.7523/j.ucas.2023.053

Abstract ( 147 ) PDF (0KB) ( 0 )

A closed loop wind tunnel that allows for high-quality optical observation was designed. Droplets were subjected to shear flow in the wind tunnel and the CCD cameras mounted horizontally and vertically were used to acquire the shape information to experimentally investigate the droplet evaporation. It is found that the droplet will experience three stages under the shear flow and airflow could enhance the evaporation rate significantly. For the droplet of 10 μL, the evaporation rate is 168% higher in 2 m/s wind speed than that without wind. However, increasing the wind speed can not improve the evaporation rate when the wind speed is high. The effect of airflow on the shape of droplet is mainly dependent on the Weber number and the dimensionless number k', which characterizes the ratio of wind force and adhesion force. The effect of shear flow on mass transfer at the gas-liquid interface was investigated, and the relationship between the dimensionless Reynolds number and the Sherwood numbers was determined. It was determined that the theoretical relationship between wind speed and evaporation rate is consistent with experimental data.

Design and experimental research of micro-newton thruster

WANG Hao, MU Jianchao, CONG Linxiao, LI Yingmin, LIU Jie, QIAO Congfeng

2025, 42 (3): 412-420. DOI: 10.7523/j.ucas.2023.058

Abstract ( 328 ) PDF (0KB) ( 0 )

The space exploration missions for precise attitude control and orbit adjustment require spacecraft propulsion systems with micro-thrust, high precision, and wide-range continuous adjustment. The cusp-type Hall thruster has the characteristics of simple structure, large thrust range, low power consumption and long working life. This paper proposes a micro-newton cusp Hall thruster with narrower channel and stronger magnetic field. Under micro-flow rate conditions, the narrower channel increases the density of the propellant in the discharge chamber, and the stronger magnetic field improves the confinement efficiency of electrons. This promotes the collision ionization process between electrons and propellant atoms, and the stable thrust of the thruster output is realized. The experimental results show that the flow range(propellant is Xe) is 0.5-1.0 sccm, the voltage range is 0-300 V, the thrust range reaches 5.4-518.9 μN. The response time is better than 150 ms, and the thrust noise reaches 0.1 μN/Hz^1/2at 0.05-1 Hz. When the flow rate of propellant Xe is 0.5 sccm and the voltage is 500 V, the thrust output reaches 50 μN and the specific impulse reaches 104 s. By optimizing the magnetic field design, the performance of this type of micro-newton cusp Hall thruster can be further improved, which can meet the requirements of space exploration missions.

Core-mantle coupled numerical modeling of Mercury’s thermal evolution

ZHAN Wenzhen, YU Hongzheng, WANG Shimin

2025, 42 (3): 421-432. DOI: 10.7523/j.ucas.2023.062

Abstract ( 104 ) PDF (0KB) ( 0 )

Thermal evolution is at the origin of all dynamics inside a planet. In terms of approximations including parameterizing the stagnant-lid convection heat transfer in Mercury’s mantle and representing the temperature distribution in Mercury’s liquid core by an adiabat, a one-dimensional finite difference model with core-mantle coupling is established in this study to investigate Mercury’s thermal evolution since its core began to solidify. Based on observational data and previous research, this article focuses on analyzing the influence of the solidification mode of Mercury’s core and the radioactive heat generation in Mercury’s mantle on the internal temperature and heat flow evolution of Mercury, laying a foundation for studying the origin of Mercury’s magnetic field. The numerical modeling results indicate that the thermal evolution of outward solidification of Mercury’s core cannot explain the observed magnetic field of Mercury. Based on a previous estimate of the thickness of a stable conductive layer in the upper region of Mercury’s core, the thermal evolution model with inward core solidification predicts that the current solid outer core of Mercury has an age older than 2.8 Ga, while the heat flow through the current liquid inner core of Mercury is between 0.8 and 0.4 TW. The low intensity of the observed Mercury’s magnetic field is a combined result of the low heat flow through the liquid inner core and the magnetic shielding effect of the solid outer core.

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