Table of Content

16 September 2025, Volume 31 Issue 4

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Materials Science

Reactive molecular dynamics of seed-based growth of carbon nanotubes

XI Sisi, LIU Fu, DONG Ziqiang, SUN Qiang, DENG Zhenyan, ZHAO Xinluo, LIU Yi

2025, 31(4):  571-590.  doi:10.12066/j.issn.1007-2861.2685

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The construction of future carbon-based electronic devices requires single-walled carbon nanotubes (SWCNTs) with specific diameters and electronic bandgaps. However, the selective synthesis of carbon nanotubes with controlled diameters and chirality remains a significant experimental challenge. Using carbon nanotubes as seed templates can promote the growth of SWCNTs with specific diameters and chirality, yet the microscopic growth mechanisms remain poorly understood. This study systematically investigated the microscopic processes of seed-based growth of SWCNTs through molecular dynamics simulations based on a newly developed next-generation all-carbon ReaxFF reactive force field. By designing open-ended short carbon nanotubes with varying diameters, chiral indices, and edge configurations, the study revealed the structural evolution and growth mechanisms at both ends of SWCNTs, along with their microscopic regulation principles. Moreover, the role of hydrogen during the growth process was explored, demonstrating its critical influence in key steps of SWCNT formation. These findings provide new insights into the role of hydrogen in the selective growth of SWCNTs. This work not only elucidates the mechanism of seed-based growth of SWCNTs but also offers theoretical guidance for the controlled experimental synthesis of SWCNTs with specific diameters and chirality, contributing to the design and application of carbon-based electronic device materials.

Focus on quantum materials: KTaO₃ two-dimensional interface superconductivity

YIN Xinmao, SUN Mengxia, NING Yuanjie, DAI Liang, LI Minjuan, CAI Chuanbing

2025, 31(4):  591-606.  doi:10.12066/j.issn.1007-2861.2582

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The discovery of two-dimensional electron gas (2DEG) and interfacial superconductivity within perovskite oxide heterostructures has made them one of the research hotspots. In recent years, there have been groundbreaking advancements in the study of oxide interfaces. In addition to the conventional LaAlO$_{3}$/SrTiO$_{3}$ (LAO/STO) interface, superconductivity has been observed at the KTaO$_{3}$ (KTO) interface in 2021, with a superconducting transition temperature ($T_{\rm c}$) approximately an order of magnitude higher than that of LAO/STO, reaching around 2 K, sparking widespread attention. Compared to the STO interface system, the KTO oxide interface exhibits characteristics such as high carrier mobility and strong spin-orbit coupling (SOC), providing a new avenue for understanding the mechanism of unconventional superconductivity and studying new physical properties, thus establishing KTO heterostructures as promising candidates for future electronic and spintronic applications. This paper aims to summarize the latest progress in KTO interfaces over the past five years, provide an in-depth overview of the novel physical phenomena of superconductivity at the interfaces of various oxides and KTO, and discuss unresolved issues in current researches, thereby guiding the direction of future investigations.

Preparation and performance of multi-level ZnO-PMIA nanofiber separator for lithium-ion batteries

WU Simin, HU Zuming, YU Junrong, WANG Yan, LI Na

2025, 31(4):  607-621.  doi:10.12066/j.issn.1007-2861.2672

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Electrostatic spinning technology was utilized to fabricate a poly (m-phenylene isophthalamide) (PMIA) nanofiber membrane and innovatively incorporated lithiophilic ZnO nanosheets onto the heat-resistant PMIA nanofiber membrane, successfully constructing a hierarchically structured nanofiber composite separator. The incorporated ZnO nanosheets facilitated the in-situ formation of the Li-Zn alloy layer, directionally promoted uniform lithium deposition, and suppressed the growth of lithium dendrites. With this design, the prepared lithium-ion batteries (LIBs) used ZnO-PMIA composite separators achieved an ionic conductivity of 0.750 mS/cm and a low interfacial impedance of 244 $\Omega$. Consequently, LIBs equipped with the ZnO-PMIA-0.1M composite separators exhibited exceptional cycling stability at 0.5 C, maintaining a high specific capacity of 128.5 mA$\cdot$h/g after 100 cycles.

Refinement effect of Ti/B on Al dendrites in Zn-6Al-3Mg alloy

DAI Jingge, LIU Yao, WU Guangxin

2025, 31(4):  622-631.  doi:10.12066/j.issn.1007-2861.2684

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To further improve the surface quality and enhance the corrosion resistance of Zn-6Al-3Mg (ZAM) alloy, the refinement effects of Ti or Ti/B additions on Al dendrites in ZAM alloy were investigated. The results showed that the Al dendrites in ZAM alloy exhibited a standard secondary dendritic morphology. However, after adding Ti or Ti/B, the Al phase consisted of secondary dendrites, primary dendrites, and axial crystal morphologies. Both Ti and Ti/B additions effectively refined the Al dendrites, with ZAM-Ti/B alloy demonstrating superior refinement compared to ZAM-Ti alloy. Transmission electron microscope (TEM) results revealed that Ti and B additions induced the formation of new precipitated phases, namely TiAl$_3$ and TiB$_2$ in ZAM alloy. TiAl$_3$ appeared at the center of Al dendrites, while TiB$_2$ was typically surrounded by MgZn$_2$ phases. These precipitated phases effectively refined the Al dendrites in ZAM alloy.

Effect of PMO on solidification structure and segregation of Cr8Mo2SiV steel

XU Fan, CHEN Xiangru, ZHAI Qijie

2025, 31(4):  632-645.  doi:10.12066/j.issn.1007-2861.2683

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This study aims to address the issues of coarse solidification microstructure and central segregation in Cr8Mo2SiV steel ingots by employing pulsed magneto-oscillation (PMO) technology to regulate the solidification process. Through microstructure characterization and elemental analysis, the effects of PMO peak currents (0, 1 000 $K_{\rm P}$, 1 500 $K_{\rm P}$, and 2 000$K_{\rm P}$ A) on the solidification structure and segregation behavior of Cr8Mo2SiV steel were systematically investigated. The results demonstrate that PMO treatment significantly refines the solidification structure. Under the 1 500$K_{\rm P}$ A parameter, the proportion of columnar crystal zones decreases from 30.8% in untreated samples to 8.07%, while that of the equiaxed crystal zone increases to 86.31%. Additionally, elemental segregation is markedly improved. The area of central segregation regions is reduced, and the enrichment of Cr, Mo, and other elements in interdendritic regions is diminished. The PMO mechanism promotes nucleation and internally generates electromagnetic forces that detach grains from the mold wall, thereby refining the grain structure. Furthermore, it induces a double recirculation flow within the melt, enhancing solute uniformity. This technology provides an effective solution for improving the solidification quality of Cr8Mo2SiV steel ingots.

Light quantum mechanism of PCR efficiency oscillation concerning gold nanoparticle concentration

FANG Huanhuan, CHEN Yongcong

2025, 31(4):  646-656.  doi:10.12066/j.issn.1007-2861.2590

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The widespread application of nanomaterials in polymerase chain reaction (PCR) technology has opened new avenues for improving detection methods in the biomedical field. Recent experiments have revealed that the oscillatory behavior between PCR efficiency and the concentration of gold nanoparticles in the pM range is, potentially linked to the long-range Coulomb interactions among charged colloidal particles and the quantum size effect of nanoparticles electronic states. Through Monte Carlo simulation, this paper discovered that the radial distribution function of gold nanoparticles in solution gradually exhibited peak characteristics with increasing charge, triggering coherent photon behavior in Rayleigh scattering within the solution, and thereby influencing the efficiency of reusing released photons in the PCR reaction. The study demonstrates that the oscillation period aligns with the wavelength of downstream reaction photons, while their energy matches the width of energy levels near the Fermi level of gold nanoparticles. The latter can absorb and store electron states internally, promoting upstream PCR reactions through subsequent re-release, and compensating for energy deficiencies through the Boltzmann distribution of electrons. This work is poised to advance the application of PCR-specific precise detection methods in the field of quantum biotechnology.

Quantum Science

Mechanism and prospects of room-temperature magnetoresistance effect in (Fe_1-xNi_x)_5+δGeTe₂ single crystals

LONG Xiumin, PAN Haojie, CAO Guixin

2025, 31(4):  657-665.  doi:10.12066/j.issn.1007-2861.2680

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According to reports, Ni-doped Fe$_{5}$GeTe$_{2}$ single crystals have a Curie temperature ($T_{\rm C}$) of up to 478 K. Given the great potential of room-temperature van der Waals (vdW) ferromagnetic materials in spintronics, a series of (Fe$_{1-x}$Ni$_{x})_{5+\delta }$GeTe$_{2}$ single crystals were formed via the chemical vapor transport (CVT) method, so as to investigate the effect of Ni doping on the room-temperature magnetoresistance (MR) effect of Fe$_5$GeTe$_2$ single crystals. Moreover, their magnetic properties and room-temperature MR changes with Ni doping were measured using a physical property measurement system (PPMS) and a magnetic property measurement system (MPMS). The results show that the room-temperature MR evolves from linear negative magnetoresistance (NMR) to two nonlinear NMR types and then to linear positive magnetoresistance (PMR) with increasing Ni content. The microscopic mechanisms of different MR effects and their prospects in spintronic devices were analyzed.

Robustness of non-adiabatic geometric single qubit gate with compensation pulse

LAI Ying, HUANG Jiedong, QIAN Yang, YAN Ying, LU Jie

2025, 31(4):  666-677.  doi:10.12066/j.issn.1007-2861.2640

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Single qubit gates are the core components for realizing quantum computing, and their high fidelity and robustness are indispensable key characteristics. Designing quantum gates using the global properties of geometric phases is an important approach, as this method can effectively resist certain local perturbations, thereby improving the fault tolerance of gate operations. In some experimental schemes, a compensation pulse is often applied after quantum gate operations to enhance fidelity. Within the framework of non-adiabatic geometric quantum computing and based on the general theory of time-dependent perturbation, this paper examined the impact of system errors on fidelity and derived the corresponding analytical results. Moreover, the paper validated these analytical results through numerical simulations, demonstrating their influence on the robustness of quantum gates. This provides a potential direction for designing more optimal pulses. The results show that the fidelity error of the NOT gate and S gate can be reduced by about 50% with the help of a compensation pulse.

Information Engineering

Traffic accident prediction based on multi-head attention spatio-temporal graph convolutional network

JIANG Tianhao, WANG Rui

2025, 31(4):  678-690.  doi:10.12066/j.issn.1007-2861.2676

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This paper proposed a novel spatio-temporal graph convolutional network (STGCN) enhanced with a multi-head attention (MHA) mechanism and adaptive adjacency matrices. The MHA mechanism dynamically weighted spatio-temporal features and external environmental factors, while the adaptive adjacency matrices adjusted the connection weights of road networks to improve the model's ability to capture spatial dependencies. Experimental results demonstrated that the model outperformed state-of-the-art (SOTA) models on the London road network dataset, achieving significant improvements across multiple evaluation metrics.

Real-time reflective vest detection in operational environments based on YOLO

ZHU Shuo, WANG Yongfang, LI Zixuan, CHEN Wei

2025, 31(4):  691-703.  doi:10.12066/j.issn.1007-2861.2686

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Based on the YOLOv7 model, the YOLOv7-globel attention mechanism (YOLO-GAM) model was proposed to enhance the model's focus on critical regions. Additionally, a multi-scale training scheme was introduced to improve the model's ability to detect small targets, and a two-stage enhanced detection algorithm was designed, which effectively mitigated the degradation of detection performance caused by occlusion, overlapping, and small targets. With an input image resolution of $640\times 640$, the scheme's detection speed could meet the real-time requirements of the actual production environment and outperform the related algorithms in terms of performance.

Domain generalization for road scene object detection under complex weather conditions

WANG Yunting, ZHANG Jinyi

2025, 31(4):  704-718.  doi:10.12066/j.issn.1007-2861.2573

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Road scene object detection is an important part of the intelligent transport field, which is directly related to the implementation of many intelligent transport applicative technologies. However, the existing domain generalization techniques for road scene object detection generally have the problems of insufficient domain-invariant feature extraction, low detection accuracy, and weak generalization ability. To address this problem, this paper proposed a domain generalization method for road scene object detection under complex weather conditions. The paper designed a road scene domain-invariant feature generation model, extracted the intra-domain invariant features and inter-domain invariant features of the source domain images, respectively, and generated more diverse road scene domain-invariant features under complex weather conditions to improve the generalization ability of the object detection model. On this basis, a domain generalization model of road scene object detection was designed, and the self-distillation mechanism was introduced to make the features extracted by the object detection model have rich domain-invariant features to further enhance its generalization ability, so as to improve the detection accuracy of the object detection model. The experimental results show that the performance of the object detection domain generalization model in this paper is significantly improved compared with the comparison models. The model can significantly improve the generalization ability and detection accuracy of the object detection model. Among them, the F1-score is increased by 0.042-0.051 compared with the baseline object detection model, and the mean average precision (mAP) is increased by 3.0%-5.9%, which proves the effectiveness and superiority of the object detection domain generalization method proposed in this paper.

Few-shot encrypted traffic classification model incorporating MAML and contrastive learning

JIN Yanliang, FANG Jie, GAO Yuan

2025, 31(4):  719-734.  doi:10.12066/j.issn.1007-2861.2594

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In order to address the current challenge of limited labeled encrypted traffic and rapidly adapt to the classification tasks of emerging traffic, this paper proposed a few-shot encrypted traffic classification model incorporating model-agnostic meta-learning (MAML) and contrastive learning. Specifically, it improved the inner-loop optimization of the MAML by incorporating supervised contrastive loss, thereby enabling the embedding representations generated by the feature encoding network during the conversation flow to be more distinguishable in the label space. Consequently, general meta-knowledge across multiple tasks was obtained. Leveraging this meta-knowledge, the adaptation phase for new tasks requires only a small amount of labeled data, enabling rapid learning and satisfactory performance on the target task. Results on the public dataset ISCXVPN-NonVPN2016 and a private dataset show that the proposed method exceeds the existing few-shot classification methods. In the 2way-10shot task, the proposed method achieves 97.46% accuracy and 97.12% F1-score on the public dataset, as well as 95.19% accuracy and 94.96% F1-score on the private dataset, respectively. In addition, the proposed model can alleviate the problems of inter-class similarity and intra-class difference that MAML is difficult to deal with. Compared to MAML, its accuracy and F1-score improve by 3.62% and 3.70% on the 5way-10shot task in the public dataset, respectively.

Accelerated design of polynomial multiplication for fully homomorphic encryption

TIAN Huihui, YAN Limin

2025, 31(4):  735-745.  doi:10.12066/j.issn.1007-2861.2634

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Aiming at the problem of long computation time of polynomial multiplication in fully homomorphic encryption (FHE), a hardware multiplication structure is designed to accelerate it. First, the design of the configurable hardware modular addition unit is completed by combining the two hardware modular addition structures. Then Barrett reduction method is improved through the utilization of a special modulus method, which serves to accelerate the modular reduction computation time. The optimized reduction method is then used to improve the optimized constant-geometry number-theoretic transform (CG-NTT) algorithm. At last, complete the design of the multiplication module on a field-programmable gate array (FPGA) platform. The experimental results show that by using the hardware multiplication structure, the polynomial multiplication computation time can be reduced by 96.26% and the resource consumption of look-up-table (LUT) can be reduced by 50.71% to 93.97%.

Event-triggered control of networked control systems based on fixed-time observers

YAO Xinpeng, LI Jian, MENG Xianglong, XIE Dongdong, KAN Xin, MENG Qiang

2025, 31(4):  746-756.  doi:10.12066/j.issn.1007-2861.2643

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This paper proposes a dynamic event-triggered fixed-time backstepping control method based on a fixed-time disturbance observer for networked strict-feedback systems with uncertainty. Firstly, a fixed-time disturbance observer is proposed to estimate the uncertainty in the system. Then a dynamic event-triggered mechanism is designed to reduce the communication resource waste of the system. Furthermore, by compensating for the impact of uncertainty and considering the impact of event-triggering mechanisms on the system, a practical fixed-time stable controller without singularity problems is designed under the backstepping framework. Finally, the effectiveness of the proposed control method was verified through numerical simulation.