Journal of University of Chinese Academy of Sciences

Digital twin outlook for all-vanadium redox flow batteries

WANG Erqiang, SANG Tengteng

2025, 42 (5): 577-588. DOI: 10.7523/j.ucas.2025.012

Redox flow batteries have gained wide attention at home and abroad as a long-duration energy storage technology with the advantages of high safety, long lifespan, mutual independence of capacity and power, and easy recycling. However, the current battery management technology faces significant challenges, and there is room for development. Digital twin (DT), as a technology that collectively senses, evaluates, predicts, and optimizes characteristics, is promising to contribute to redox flow batteries’ operation, maintenance, and management. This paper begins with a brief description of redox flow batteries, followed by a short explanation of the concept and application of DTs. DTs have already made some progress in the field of batteries, and can be applied to solve the problems of redox flow batteries in terms of thermal management and system optimization. Finally, the paper analyzes the combination of redox flow battery and DT architecture, which is expected to contribute to developing DT technology for redox flow batteries.

Some analytic results and applications in extremal Hermitian metrics

SANG Haoxin, WU Yingyi

2025, 42 (5): 589-599. DOI: 10.7523/j.ucas.2023.091

Abstract ( 208 ) PDF (0KB) ( 0 )

In this paper, we introduce and prove three analytic results related to uniform convergence, properties of Newtonian potential, and convergence of sequences in Sobolev space constrained by their Laplacian. Then, utilizing our analytic results, we develop a complete proof of a crucial estimate appearing in the results of Guofang Wang and Xiaohua Zhu, which states the classification of extremal Hermitian metrics with finite energy and area on compact Riemann surfaces and finite singularities satisfying small singular angles.

Direct experimental investigation of commutation relation

WANG Hui, WANG Shuang, QIAO Congfeng

2025, 42 (5): 600-605. DOI: 10.7523/j.ucas.2023.052

Abstract ( 123 ) PDF (0KB) ( 0 )

The canonical commutation relation is one of the hallmarks of quantum theory. One method of testing commutation relation is to perform sequential measurements according to its definition, but the verification of intrinsic association between incompatible observables has been rather limited. In this study, we construct the weak value of another incompatible observable based on the two-state vector formalism of weak measurement, where the eigenstate of one observable acts as pre-selective state. The weak value establishes a correlation between two noncommuting observables, and determines the expectation value of commutation relation together with the post-selection probability. The experiments realize the extraction of weak values using composite path interference with high-stability coherent light. Experimental results agree with the theory and accomplish a direct test of commutation relation for Pauli operators, which provides a new experimental basis for further understanding of the commutation relation and quantum uncertainty relations.

Assessment and pathway simulation of coordinated development of economy-resource-environment system in typical cities of the Yellow River Delta: the case of Binzhou City

SONG Jiawen, ZHANG Xiaoping, WU Aiping, LIAN Wenhua

2025, 42 (5): 606-618. DOI: 10.7523/j.ucas.2023.092

Abstract ( 325 ) PDF (0KB) ( 0 )

The coordinated development of regional economy-resource-environment system (ERE) is a crucial aspect of achieving the sustainable development goals. Taking Binzhou City in Shandong Province, a typical city in the Yellow River Delta, as an example, this paper constructs a coupling coordination degree model and examines the coupled and coordinated development of its ERE system from 2000 to 2020. Furthermore, a system dynamics (SD) model of Binzhou City’s ERE is constructed based on 71 indicators, through which causal feedback relationships and flows among subsystems are illustrated. Four scenarios are set for simulation as follows: current trend continuing mode, secondary industry leading mode, resource and environment prioritizing mode, and system coordinated mode. The results show that: 1) Over the past 20 years, the level of coupled and coordinated development in Binzhou City has been increasing year by year, and the type of coupled and coordinated development has gradually transitioned from an unbalanced state to a well-coordinated state, but there is still instability in the ERE; 2) Through SD parameter calculation and multi-scenario simulation analysis of Binzhou City’s ERE, it is pointed out that continuing the current development model cannot achieve high-quality sustainable development in Binzhou City. Therefore, a coordinated and stable development model, which takes economic, resource, and environmental benefits into account, is suggested as the relatively optimal solution for Binzhou City to achieve sustainable development in the long run.

Spatial distribution characteristics and tourism development potential evaluation of traditional villages in Shandong Province

ZHANG Shengrui, SONG Yongyong, ZHANG Tongyan

2025, 42 (5): 619-631. DOI: 10.7523/j.ucas.2024.001

Abstract ( 490 ) PDF (0KB) ( 0 )

This article takes 567 national level (168) and provincial level (511) traditional villages in Shandong Province as subjects of investigation. Firstly, a spatial econometric model is used to analyze the spatial distribution characteristics of traditional villages in Shandong Province. Secondly, the Delphi method and SPSS factor analysis method are used to screen and analyze the evaluation indicators. A total of 28 indicators including village cultural resources, village ecological and natural resources, institutional management, tourism infrastructure, and village economic vitality are obtained. Finally, the AHP entropy weight method is used to combine weights to score the selected indicators. A scoring table for tourism development potential of traditional villages in Shandong Province is constructed, and a multi-objective linear weighted function model is used for scoring. The results showed that: 1) The overall spatial distribution of traditional villages in Shandong Province is uneven, mostly distributed in mountainous areas or underdeveloped areas of cities with relatively uneven development and underdeveloped infrastructure; 2) Among various indicators, the cultural resources (0.331 2) and institutional management (0.144 0) of the village play an important role, followed by tourism infrastructure (0.143 7), village ecological and natural resources (0.143 4), and village economic vitality (0.097 7); 3) The evaluation results show that there are 135 key traditional villages (S≥7.9) in Shandong Province, accounting for only 23.81% of the total number of traditional villages in Shandong Province; there are 295 traditional villages (6.2<S<7.9), accounting for 52.03% of the total number of traditional villages in Shandong Province; there are 137 traditional villages with a focus on protection (S≤6.2), accounting for 24.16% of the total number of traditional villages in Shandong Province; 4) Based on the characteristics of various traditional villages, corresponding development strategies are proposed in this paper.

Differences in soil physicochemical properties between unirrigated paleo-cropping layers and natural sediment layers in Dongling Mountain, Beijing

LYU Xuanze, LI Yumei, WANG Luo

2025, 42 (5): 632-644. DOI: 10.7523/j.ucas.2024.014

Abstract ( 199 ) PDF (0KB) ( 0 )

The identification of paleo-cropping layers is an essential part of the study of the origins of agriculture and the exploration of ancient human land use. It is a challenge that archaeologists and palaeoenvironmentalists are facing together. The existing methods of identifying ancient cultivation layers are costly and limited, and there is an urgent need to develop new, simple, convenient, and reliable methods to identify ancient cultivation layers. Farming without irrigation, using plows to turn the land, once occurred in Beijing’s Dongling Mountain and continued for at least 300 years before retiring. There are also natural meadows and broadleaf forests in the area with no tillage history. In this study, four types of soil profiles, namely natural meadow, natural broadleaf forest, abandoned farming meadow, and abandoned farming broadleaf forest, were compared in terms of their soluble salt content, pH, magnetic susceptibility, and color characteristics in order to establish a method for identifying ancient cultivation layers. It was found that the soluble salt content in the abandoned farming soil profile was significantly lower than that in the natural profile, and the coefficient of variation was also significantly lower than that in the natural profile. The soluble salt content and its coefficient of variation can be used to identify ancient tillage layers without irrigation. Soil magnetic susceptibility and pH also have potential value in identifying ancient cultivation layers, and further in-depth studies are needed.

Multimodal medical image registration based on multi-layer feature fusion

CHANG Qing, LI Mengke, LU Chenhao, ZHANG Yang

2025, 42 (5): 645-654. DOI: 10.7523/j.ucas.2023.070

Abstract ( 281 ) PDF (0KB) ( 0 )

As the initial step of multimodal medical image registration, the accuracy and speed of registration will largely affect the effect of medical image fusion. Due to the large difference in grayscale and texture structure of multimodal medical images, it is difficult to extract correlating features, resulting in low registration accuracy. This paper proposes a multi-layer feature fusion registration network, parallel extraction of features of the fix image and moving image, and the multimodal feature is gradually fused by using the dual-input spatial attention module in the multi-layer structure, obtaining their correlation and mapping such correlation to image registration transformation. At the same time, the structural information loss term guidance network based on dense symmetric scale invariant feature transform is introduced for iterative optimization to achieve accurate unsupervised registration.

UAV-assisted communication online control strategy based on MPC

WANG Yifei, HUANG Wei, XIANG Junyan, HE Xiaohe, LIANG Xuwen

2025, 42 (5): 655-665. DOI: 10.7523/j.ucas.2023.082

Abstract ( 235 ) PDF (0KB) ( 0 )

This paper addresses the research challenges in unmanned aerial vehicle communication networks, including significant interference among multiple users, high complexity of dynamic models, and the difficulty in designing real-time optimal control strategies. For the first time, the multi-antenna technology is introduced into the quadcopter unmanned aerial vehicle (UAV) communication network, proposing a complex communication network model under the 3D multi-user multiple-input single-output scenario. This model takes into account the small-scale variations of UAV attitudes and their impact on channel quality. Additionally, the space division multiple access technology is employed to effectively mitigate inter-user interference model predictive control. In this context, an online UAV attitude control and resource allocation strategy based on model predictive control(MPC) algorithm is designed. By iteratively solving the open-loop control problem with a rolling window of limited time duration, the average spectral efficiency of the UAV communication system is maximized. Simulation results demonstrate that the proposed coupled communication model significantly improves system gains, and the control strategy efficiently optimizes UAV flight trajectories and allocates communication resources in dynamic environments.

SAR decompressed image reconstruction algorithm based on generative adversarial network

ZHANG Bingyu, PAN Zhigang, YAO Kai, DONG Xubin

2025, 42 (5): 666-676. DOI: 10.7523/j.ucas.2023.033

Abstract ( 220 ) PDF (0KB) ( 0 )

The high multiple compression processing of SAR images will cause damage to the target and texture information in the image, which makes the problems of blur and indistinguishable targets often appear in the decompressed SAR image, and is difficult to effectively reflect the real features of ground objects. To solve the above problems, a new SAR image reconstruction algorithm is proposed based on the generative adversarial network. Based on the codec structure, the algorithm takes the parallel fusion of convolutional neural network and self-attention mechanism as the generator, and designs a simple and efficient architecture called ConTransformer, which can get richer global features and effectively improve the effect of small-target reconstruction. For the Discriminator, spectral normalization is introduced into the U-Net feature extractor to reduce the sensitivity of the model to input disturbance, so as to suppress artifacts. Synchronously, the pre-training mask mechanism is used to enhance the extraction of high-level semantic features and improve the authenticity of reconstructed images. Experimental results show that the reconstructed images obtained by this method have clearer visual effects and better key performance indicators than those obtained by Real-ESRGAN and other typical methods based on generative adversarial networks, among which the peak signal-to-noise ratio is improved by 0.57-1.54 dB.

An improved high efficiency low error substrate integrated waveguide wideband delay line

ZHANG Hongxi, WANG Pei

2025, 42 (5): 677-685. DOI: 10.7523/j.ucas.2023.034

Abstract ( 157 ) PDF (0KB) ( 0 )

In this paper, a wideband true time delay line for X-band is designed to overcome the beam dispersion problem in a high-resolution spaceborne synthetic aperture radar phased array antenna system. The delay line loads the electromagnetic bandgap structure on the upper surface of the substrate integrated waveguide. This is equivalent to including an additional inductance-capacitance for energy storage, which realizes the slow-wave effect. A microstrip line-SIW tapered transition structure is introduced to achieve a low loss and a large bandwidth. In the frequency band between 8-12 GHz, the measured results show that the delay multiplier of the delay line reaches 4 times, i.e., delay line’s delay time is 4 times larger than 50 Ω microstrip line with same length. Furthermore, the delay fluctuation, i.e., the difference between the maximum and minimum delay as a percentage of the standard delay is only 2.5%, the insertion loss is less than -2.5 dB, and the return loss is less than -15 dB. Compared with the existing delay lines, the proposed delay line has the advantages of high delay efficiency, low delay error, wide bandwidth and low loss, which has good practical value and application prospects.

Multitemporal polarimetric SAR crop classification method based on tensor representation

XU Lu, ZHANG Hong, WANG Chao, WU Fan, ZHANG Bo, TANG Yixian

2025, 42 (5): 686-699. DOI: 10.7523/j.ucas.2024.003

Abstract ( 324 ) PDF (0KB) ( 0 )

Multitemporal polarimetric synthetic aperture radar (SAR) provides abundant polarimetric scattering information, which is of great value to the long-term monitoring of various crop lands. To make full use of the time correlation and polarimetric information of multitemporal polarimetric SAR, this paper proposed a multitemporal polarimetric SAR crop classification method, which is based on the complete polarimetric covariance matrix. The method can maintain the complex matrix structure of covariance matrix and realize the independent representation of time dimension in tensor space, so that it can be applied to both full- and compact-polarimetric SAR. The method adopted the object-level classification strategy. Firstly, the superpixel segmentation of multitemporal SAR data was achieved by the simple linear iterative clustering (SLIC) method. Then, the covariance matrices of multitemporal SAR were expressed as tensors, and the multilinear principal component analysis (MPCA) method was used to reduce the feature dimension. Finally, the crop classification is achieved by decision tree. In this research, four multitemporal RADARSAT-2 Fine Quad SAR images covered Wuqing District，Tianjin, were used for the crop classification experiments. Compared with methods proposed in other references, the method proposed in this paper achieved the highest overall classification accuracy. Besides, the proposed method was applied to the π/4 mode and the CTLR mode compact-polarimetric SAR to discuss the capability of different kinds of polarimetric SAR in crop classification. Compared with the full-polarimetric SAR, the compact-polarimetric SAR could achieve comparable classification accuracies, but the full-polarimetric SAR performed better at the classes with small sample size, such as rice and lotus.

Individual tree segmentation of desert Haloxylon ammodendron forests based on UAV LiDAR

XIONG Shimei, XU Wenqiang, BAO Anming, WANG Zhengyu, TAO Zefu

2025, 42 (5): 700-710. DOI: 10.7523/j.ucas.2024.006

Abstract ( 295 ) PDF (0KB) ( 0 )

The potential of light detection and ranging (LiDAR) technology in the application of individual tree segmentation and parameter estimation in desert Haloxylon ammodendron forests has not been explored. This study uses UAV LiDAR data to extract canopy height models (CHM) at spatial resolutions of 0.1, 0.25, 0.5, and 1 m on different interpolation methods, and applies the CHM seed point segmentation algorithm to segment individual trees in three types of Haloxylon ammodendron plots with different growth conditions. This study evaluates the impact of spatial resolution and growth conditions on segmentation accuracy, and verifies the extraction accuracy of tree height and crown width with field measurement data. The results show that the inverse distance weighting interpolation has a higher segmentation accuracy in this study. Spatial resolution is a key factor affecting the results of individual tree segmentation, with the best segmentation results obtained at a resolution of 0.25 m.Class III plots had the highest segmentation accuracy, which was 27% higher than that of Class II plots and 44% higher than that of Class I sample plots. The overlapping crowns of Haloxylon ammodendron in plot I make it difficult to distinguish the crown boundaries, while the independent crowns in plot III make it easier to achieve accurate segmentation. The R² of the tree height fitting model for all three types of plots is around 0.80, with RMSE less than 0.31 m. The R² of the canopy extraction fit for the Class I and II plots is around 0.70, with a slightly higher RMSE error, and the branches in a half dead state of Haloxylon ammodendron in plot III affect the extraction accuracy of crown width. This study demonstrates that LiDAR data has great potential for individual tree segmentation in desert Haloxylon ammodendron forests, which can provide data support for desert forests carbon sink estimation in Xinjiang.

Cultivation and utilization of Chinese jujube in Turpan during the Jin to Tang dynasties based on unearthed plant remains and documents

CHEN Tao, YU Haiqin, JIANG Hong

2025, 42 (5): 711-719. DOI: 10.7523/j.ucas.2023.084

Abstract ( 232 ) PDF (0KB) ( 0 )

Astana Cemetery is located in Turpan Basin, Xinjiang. Due to the local extremely arid climate, large numbers of plant remains and documents were well preserved in Astana Cemetery, providing valuable materials for exploring the agricultural production and plant utilization of Turpan people during the Jin to Tang dynasties. Archaeobotanical method was applied on the Chinese jujube (Ziziphus jujuba Mill.) remains unearthed from the Astana Cemetery. Combined with relevant documents, the cultivation and utilization of Chinese jujube during the Jin to Tang dynasties were discussed. It showed that Chinese jujube was a common and important characteristic cash crop in ancient Turpan. The indigenous people used Chinese jujube in various ways, including eating in fresh and further processing it into dried jujube, jujube cake or dry powder of jujube. In addition, the medicinal value of Chinese jujube and the excellent characteristics of jujube wood were also recognized and utilized by ancient Turpan people.

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