Pub Date : 2026-02-01DOI: 10.1016/j.dt.2025.09.009
Hongyu Han, Zhaohui Dang
This paper proposes a threat assessment framework for non-cooperative satellites by analyzing their motion characteristics, developing a quantitative evaluation methodology, and demonstrating its effectiveness via representative scenarios with neural network acceleration. The framework first establishes a threat evaluation model that integrates three core parameters: capability, opportunity, and hidden values. Subsequently, this research systematically investigates the critical role of transfer windows in threat quantification and introduces a transfer window-based threat assessment approach. The proposed methodology is validated through multiple representative scenarios, with simulation results demonstrating superior performance compared to conventional methods relying solely on optimal transfer windows or minimum distance metrics, enabling more nuanced threat ranking in scenarios where traditional techniques prove inadequate. To address computational demands, a neural network-based approximation system is implemented to achieve a 25,200 × speedup (0.005 s vs. baseline 126 s per 1000-sample batch) through parallel processing, maintaining 99.3% accuracy. Finally, the study explores the framework's extensibility to diverse NCS objectives. It identifies discrepancies between intention inference models and threat evaluation paradigms, providing methodological insights for next-generation space domain awareness systems.
{"title":"Threat assessment of non-cooperative satellites in interception scenarios: A transfer window perspective","authors":"Hongyu Han, Zhaohui Dang","doi":"10.1016/j.dt.2025.09.009","DOIUrl":"10.1016/j.dt.2025.09.009","url":null,"abstract":"<div><div>This paper proposes a threat assessment framework for non-cooperative satellites by analyzing their motion characteristics, developing a quantitative evaluation methodology, and demonstrating its effectiveness via representative scenarios with neural network acceleration. The framework first establishes a threat evaluation model that integrates three core parameters: capability, opportunity, and hidden values. Subsequently, this research systematically investigates the critical role of transfer windows in threat quantification and introduces a transfer window-based threat assessment approach. The proposed methodology is validated through multiple representative scenarios, with simulation results demonstrating superior performance compared to conventional methods relying solely on optimal transfer windows or minimum distance metrics, enabling more nuanced threat ranking in scenarios where traditional techniques prove inadequate. To address computational demands, a neural network-based approximation system is implemented to achieve a 25,200 × speedup (0.005 s vs. baseline 126 s per 1000-sample batch) through parallel processing, maintaining 99.3% accuracy. Finally, the study explores the framework's extensibility to diverse NCS objectives. It identifies discrepancies between intention inference models and threat evaluation paradigms, providing methodological insights for next-generation space domain awareness systems.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"56 ","pages":"Pages 172-183"},"PeriodicalIF":5.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.dt.2025.09.019
Qiangqiang Xiao, Zhengxiang Huang, Xudong Zu, Xin Jia, Bin Ma
<div><div>The penetration of shaped charge jets into targets at high velocities is significantly influenced by the compressibility effect, while at low velocities, the strength effect becomes predominant. In the latter regime, material strength dictates the resistance to plastic deformation and flow, a contrast to the shockwave-dominated interactions where compressibility is key. This paper presents a self-consistent compressible penetration theory that considers both the axial penetration and radial crater growth of shaped charge jets into targets. An integrated approach where the axial and radial dynamics are coupled has been proposed, influencing each other through shared physical principles rather than being treated as separate, empirically linked phenomena. The presented theory is rooted in the compressible Bernoulli equation and the linear Rankine–Hugoniot relation. These foundational equations are employed to accurately model the high-pressure shock state and subsequent material flow at the jet-target interface, providing a robust physical basis for the penetration model. Notably, it considers the target material's compressibility, which elevates the pressure at the jet-target interface beyond that observed with incompressible materials. This pressure increase is directly proportional to the target's degree of compressibility. As such, this model of compressible penetration reorients the analytical approach: rather than merely estimating penetration resistance, it determines this value from the target material's specific compressibility and yield strength. This shift from empirical correlations to a physics-based derivation of penetration resistance enhances the model's predictive power, particularly for novel target materials or engagement conditions outside established experimental datasets. This investigation establishes a quantitative link between the material's yield strength and its penetration resistance. The accuracy of this penetration resistance value is paramount, as it significantly influences the predicted crater diameter; indeed, the crater diameter's sensitivity to this resistance underscores the necessity for its precise determination. Ultimately, by integrating the yield strength of the target material, this framework enables the prediction of both the penetration depth and the resultant crater diameter from a shaped charge jet. The theory's validation involved two experimental sets: the first focused on shaped charge jet penetration into 45# steel at varied stand-offs, while the second utilized targets of high-to ultrahigh-strength steel-fiber reactive powder concrete (RPC) with differing strength characteristics. These experimental campaigns were specifically chosen to test the theory against both ductile metallic alloys, where plastic flow is significant, and advanced quasi-brittle cementitious composites, presenting a broad spectrum of material responses and penetration challenges. Resulting hole profiles derived from
{"title":"The effects of compressibility and target strength on shaped charge jet penetration","authors":"Qiangqiang Xiao, Zhengxiang Huang, Xudong Zu, Xin Jia, Bin Ma","doi":"10.1016/j.dt.2025.09.019","DOIUrl":"10.1016/j.dt.2025.09.019","url":null,"abstract":"<div><div>The penetration of shaped charge jets into targets at high velocities is significantly influenced by the compressibility effect, while at low velocities, the strength effect becomes predominant. In the latter regime, material strength dictates the resistance to plastic deformation and flow, a contrast to the shockwave-dominated interactions where compressibility is key. This paper presents a self-consistent compressible penetration theory that considers both the axial penetration and radial crater growth of shaped charge jets into targets. An integrated approach where the axial and radial dynamics are coupled has been proposed, influencing each other through shared physical principles rather than being treated as separate, empirically linked phenomena. The presented theory is rooted in the compressible Bernoulli equation and the linear Rankine–Hugoniot relation. These foundational equations are employed to accurately model the high-pressure shock state and subsequent material flow at the jet-target interface, providing a robust physical basis for the penetration model. Notably, it considers the target material's compressibility, which elevates the pressure at the jet-target interface beyond that observed with incompressible materials. This pressure increase is directly proportional to the target's degree of compressibility. As such, this model of compressible penetration reorients the analytical approach: rather than merely estimating penetration resistance, it determines this value from the target material's specific compressibility and yield strength. This shift from empirical correlations to a physics-based derivation of penetration resistance enhances the model's predictive power, particularly for novel target materials or engagement conditions outside established experimental datasets. This investigation establishes a quantitative link between the material's yield strength and its penetration resistance. The accuracy of this penetration resistance value is paramount, as it significantly influences the predicted crater diameter; indeed, the crater diameter's sensitivity to this resistance underscores the necessity for its precise determination. Ultimately, by integrating the yield strength of the target material, this framework enables the prediction of both the penetration depth and the resultant crater diameter from a shaped charge jet. The theory's validation involved two experimental sets: the first focused on shaped charge jet penetration into 45# steel at varied stand-offs, while the second utilized targets of high-to ultrahigh-strength steel-fiber reactive powder concrete (RPC) with differing strength characteristics. These experimental campaigns were specifically chosen to test the theory against both ductile metallic alloys, where plastic flow is significant, and advanced quasi-brittle cementitious composites, presenting a broad spectrum of material responses and penetration challenges. Resulting hole profiles derived from ","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"56 ","pages":"Pages 244-253"},"PeriodicalIF":5.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.dt.2025.09.021
Yiming Zhang , Hanqing Xia , Kangyu Ji , Ningfei Wang , Ke Li , Sen Chen , Yi Wu
An in-depth understanding of the behaviours of solid propellants under low-velocity impact loads is crucial for enhancing their safety in applications such as aerospace propulsion. This study investigated the dynamic responses of single ammonium perchlorate (AP)/octogen (HMX) particles embedded in a hydroxyl-terminated polybutadiene (HTPB) binder under dynamic compression loading via real-time synchrotron-based X-ray phase contrast imaging and a modified split Hopkinson pressure bar (SHPB) system. The compression of the viscoelastic binder and subsequent dynamic fracturing of the AP/HMX particles were captured. During compression, transverse cracks developed within the AP particles, and their propagation led to particle fracturing, resulting in ductile fracturing. Unlike AP, HMX generated numerous short cracks within the internal and edge regions simultaneously, leading to fragmentation and brittle fracturing. Moreover, particle damage reduced the modulus of the sample, shifting its dynamic stress response from nonlinear elasticity to strain softening and further strain hardening as the binder exhibited plastic deformation. A compression simulation incorporating a real particle microscopic structure was established to study the mechanical response of the interface and particles. The simulation results agreed with the experimental observations. These results indicate that the shear stress at the HTPB-AP interface is greater than that at the HTPB-HMX interface, which is a factor influencing the differences in the mesoscale damage mechanisms of the particles.
{"title":"Real-time visualization and numerical investigation of the dynamic compression response behaviours of single AP/HMX particles embedded in an HTPB binder","authors":"Yiming Zhang , Hanqing Xia , Kangyu Ji , Ningfei Wang , Ke Li , Sen Chen , Yi Wu","doi":"10.1016/j.dt.2025.09.021","DOIUrl":"10.1016/j.dt.2025.09.021","url":null,"abstract":"<div><div>An in-depth understanding of the behaviours of solid propellants under low-velocity impact loads is crucial for enhancing their safety in applications such as aerospace propulsion. This study investigated the dynamic responses of single ammonium perchlorate (AP)/octogen (HMX) particles embedded in a hydroxyl-terminated polybutadiene (HTPB) binder under dynamic compression loading via real-time synchrotron-based X-ray phase contrast imaging and a modified split Hopkinson pressure bar (SHPB) system. The compression of the viscoelastic binder and subsequent dynamic fracturing of the AP/HMX particles were captured. During compression, transverse cracks developed within the AP particles, and their propagation led to particle fracturing, resulting in ductile fracturing. Unlike AP, HMX generated numerous short cracks within the internal and edge regions simultaneously, leading to fragmentation and brittle fracturing. Moreover, particle damage reduced the modulus of the sample, shifting its dynamic stress response from nonlinear elasticity to strain softening and further strain hardening as the binder exhibited plastic deformation. A compression simulation incorporating a real particle microscopic structure was established to study the mechanical response of the interface and particles. The simulation results agreed with the experimental observations. These results indicate that the shear stress at the HTPB-AP interface is greater than that at the HTPB-HMX interface, which is a factor influencing the differences in the mesoscale damage mechanisms of the particles.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"56 ","pages":"Pages 254-269"},"PeriodicalIF":5.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.dt.2025.09.014
Shijie Deng, Yingxin Kou, You Li, An Xu, Bincheng Wen, Juntao Zhang, Ling Ma
This study addresses the maneuver evasion problem for medium-to-long-range air-to-air missiles by proposing a KAN--PPO-based evasion algorithm. The algorithm introduces Kolmogorov-Arnold Networks (KAN) to mitigate the catastrophic forgetting issue of Multilayer Perceptrons (MLP) in continual learning, while incorporating -return to resolve sparse reward challenges in evasion scenarios. First, we model the evasion problem with -return and present the KAN--PPO algorithm. Subsequently, we establish game environments based on the segmented ballistic characteristics of medium and long range missiles. During training, a joint reward function is designed by combining the miss distance and positional advantages to train the agent. Experiments evaluate four dimensions: (1) Performance comparison between KAN and MLP in value function approximation; (2) Catastrophic forgetting mitigation of KAN--PPO in dual-task scenarios; (3) Continual learning capabilities across multiple evasion scenarios; (4) Quantitative analysis of agent strategy evolution and positional advantages. Empirical results demonstrate that KAN improves value function approximation accuracy by an order of magnitude compared with traditional MLP architectures. In continual learning tasks, the KAN--PPO scheme exhibits significant knowledge retention, achieving performance improvements of 32.7% and 8.6% over MLP baselines in Task1→2 and Task2→3 transitions, respectively. Furthermore, the learned maneuver strategies outperform High-G Barrel Rolls(HGB) and S-maneuver tactics in securing positional advantages while accomplishing evasion.
{"title":"Avoidance method for medium-to-long-range air-to-air missile based on the kan-λ-ppo algorithm","authors":"Shijie Deng, Yingxin Kou, You Li, An Xu, Bincheng Wen, Juntao Zhang, Ling Ma","doi":"10.1016/j.dt.2025.09.014","DOIUrl":"10.1016/j.dt.2025.09.014","url":null,"abstract":"<div><div>This study addresses the maneuver evasion problem for medium-to-long-range air-to-air missiles by proposing a KAN-<span><math><mrow><mi>λ</mi></mrow></math></span>-PPO-based evasion algorithm. The algorithm introduces Kolmogorov-Arnold Networks (KAN) to mitigate the catastrophic forgetting issue of Multilayer Perceptrons (MLP) in continual learning, while incorporating <span><math><mrow><mi>λ</mi></mrow></math></span>-return to resolve sparse reward challenges in evasion scenarios. First, we model the evasion problem with <span><math><mrow><mi>λ</mi></mrow></math></span>-return and present the KAN-<span><math><mrow><mi>λ</mi></mrow></math></span>-PPO algorithm. Subsequently, we establish game environments based on the segmented ballistic characteristics of medium and long range missiles. During training, a joint reward function is designed by combining the miss distance and positional advantages to train the agent. Experiments evaluate four dimensions: (1) Performance comparison between KAN and MLP in value function approximation; (2) Catastrophic forgetting mitigation of KAN-<span><math><mrow><mi>λ</mi></mrow></math></span>-PPO in dual-task scenarios; (3) Continual learning capabilities across multiple evasion scenarios; (4) Quantitative analysis of agent strategy evolution and positional advantages. Empirical results demonstrate that KAN improves value function approximation accuracy by an order of magnitude compared with traditional MLP architectures. In continual learning tasks, the KAN-<span><math><mrow><mi>λ</mi></mrow></math></span>-PPO scheme exhibits significant knowledge retention, achieving performance improvements of 32.7% and 8.6% over MLP baselines in Task1→2 and Task2→3 transitions, respectively. Furthermore, the learned maneuver strategies outperform High-G Barrel Rolls(HGB) and S-maneuver tactics in securing positional advantages while accomplishing evasion.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"56 ","pages":"Pages 352-366"},"PeriodicalIF":5.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.dt.2025.09.020
Hao Wang, Xiangyu Li, Yong Peng, Zhandong Tian, Fangyun Lu
Reinforced concrete (RC) columns are often subjected to off-central explosion due to the uncertainty of blast locations. However, few studies have focused on the dynamic response of RC columns under off-central explosions. A field blast experiment was conducted under close-in explosion with varying detonation offset distances (0 m, 0.5 m, and 1 m), the overpressure load and dynamic responses of the full-scale RC columns were measured. Compared with the centrally detonated condition, a relative offset distance of 1.67 decreases the maximum and residual deflections of the RC column by 16.8% and 21.4%, respectively, while increasing the maximum and residual support rotations by 24.7% and 17.8%. Based on the experimental results, a theoretical model was proposed that considers the detonation location and charge mass, boundary conditions, axial compression ratio and material properties. The theoretical model exhibited good agreement with the experimental results, with prediction errors below 10% for both maximum and residual deflection. The effects of parameters were analyzed, and it indicated that an increase in offset distance results in decreased maximum and residual deflections but an increased support angle, thereby exacerbating damage. Higher axial load ratio, span-depth ratio, and longitudinal reinforcement ratio reduce both deflections and support angle. Additionally, a rapid method to predict the maximum and residual deflection of RC columns under off-central blast loading was also proposed based on the Generalized Regression Neural Network (GRNN). Eleven features which related to the RC column properties and the blast characteristics were used in the training process of GRNN, and accurate predictions were achieved with prediction errors within 20%. This study fills the gap in predicting the dynamic response of RC columns under off-central explosion, providing valuable references for blast-resistant design.
{"title":"Dynamic response of RC columns under off-central explosions: Experimental, theoretical studies and neural network prediction","authors":"Hao Wang, Xiangyu Li, Yong Peng, Zhandong Tian, Fangyun Lu","doi":"10.1016/j.dt.2025.09.020","DOIUrl":"10.1016/j.dt.2025.09.020","url":null,"abstract":"<div><div>Reinforced concrete (RC) columns are often subjected to off-central explosion due to the uncertainty of blast locations. However, few studies have focused on the dynamic response of RC columns under off-central explosions. A field blast experiment was conducted under close-in explosion with varying detonation offset distances (0 m, 0.5 m, and 1 m), the overpressure load and dynamic responses of the full-scale RC columns were measured. Compared with the centrally detonated condition, a relative offset distance of 1.67 decreases the maximum and residual deflections of the RC column by 16.8% and 21.4%, respectively, while increasing the maximum and residual support rotations by 24.7% and 17.8%. Based on the experimental results, a theoretical model was proposed that considers the detonation location and charge mass, boundary conditions, axial compression ratio and material properties. The theoretical model exhibited good agreement with the experimental results, with prediction errors below 10% for both maximum and residual deflection. The effects of parameters were analyzed, and it indicated that an increase in offset distance results in decreased maximum and residual deflections but an increased support angle, thereby exacerbating damage. Higher axial load ratio, span-depth ratio, and longitudinal reinforcement ratio reduce both deflections and support angle. Additionally, a rapid method to predict the maximum and residual deflection of RC columns under off-central blast loading was also proposed based on the Generalized Regression Neural Network (GRNN). Eleven features which related to the RC column properties and the blast characteristics were used in the training process of GRNN, and accurate predictions were achieved with prediction errors within 20%. This study fills the gap in predicting the dynamic response of RC columns under off-central explosion, providing valuable references for blast-resistant design.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"56 ","pages":"Pages 314-336"},"PeriodicalIF":5.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01DOI: 10.1016/j.dt.2025.08.006
Liu Yang , Liu Yuezhou , Gao Fulei , Liu Yingzhe , Wang Yinglei
Boron has attracted increasing attention in the field of high-energy explosives and propellants due to its high volume calorific value and mass calorific value. However, the complicated combustion process and low combustion efficiency hinder its wide application. To tackle this challenge, bioinspired polydopamine (PDA) interface reinforced boron-Viton composites, with high structure stability and excellent energy releasing efficiency, are designed and prepared, combining the interface regulation of PDA biomimetic materials and combustion promotion of fluoropolymers. Firstly, the stronger adsorption energy of PDA with boron compared to Viton is demonstrated by molecular dynamics simulations. Next, B@PDA@Viton is prepared by the combination of in-situ dopamine polymerization and solvent/non-solvent method, and the double-layer core-shell structure is confirmed by XPS, FTIR, and TEM characterizations. TG-DSC analysis shows that B@PDA@Viton possesses superior thermal properties, with a 55.48% increase in oxidation heat compared to raw B. Furthermore, ignition and combustion performance tests indicate that B@PDA@Viton reduces ignition delay by 57.56% and increases heat of combustion by 68.63% relative to raw B. These findings elucidate the ignition and combustion mechanisms of B@PDA@Viton. This work not only developed high-performance boron-based composite fuels but also provided insights into the development of boron-based fuels.
{"title":"Bioinspired polydopamine interface reinforced boron-Viton composites with high structure stability and energy releasing efficiency","authors":"Liu Yang , Liu Yuezhou , Gao Fulei , Liu Yingzhe , Wang Yinglei","doi":"10.1016/j.dt.2025.08.006","DOIUrl":"10.1016/j.dt.2025.08.006","url":null,"abstract":"<div><div>Boron has attracted increasing attention in the field of high-energy explosives and propellants due to its high volume calorific value and mass calorific value. However, the complicated combustion process and low combustion efficiency hinder its wide application. To tackle this challenge, bioinspired polydopamine (PDA) interface reinforced boron-Viton composites, with high structure stability and excellent energy releasing efficiency, are designed and prepared, combining the interface regulation of PDA biomimetic materials and combustion promotion of fluoropolymers. Firstly, the stronger adsorption energy of PDA with boron compared to Viton is demonstrated by molecular dynamics simulations. Next, B@PDA@Viton is prepared by the combination of in-situ dopamine polymerization and solvent/non-solvent method, and the double-layer core-shell structure is confirmed by XPS, FTIR, and TEM characterizations. TG-DSC analysis shows that B@PDA@Viton possesses superior thermal properties, with a 55.48% increase in oxidation heat compared to raw B. Furthermore, ignition and combustion performance tests indicate that B@PDA@Viton reduces ignition delay by 57.56% and increases heat of combustion by 68.63% relative to raw B. These findings elucidate the ignition and combustion mechanisms of B@PDA@Viton. This work not only developed high-performance boron-based composite fuels but also provided insights into the development of boron-based fuels.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"55 ","pages":"Pages 330-339"},"PeriodicalIF":5.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145981803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Conventional ignition methods are proving to be ineffective for low-sensitivity energetic materials, highlighting the need to investigate alternative ignition systems, such as laser-based techniques. Over the past decade, lasers have emerged as a promising solution, providing focused energy beams for controllable, efficient, and reliable ignition in the field of energetic materials. This study presents a comparative analysis of two state-of-the-art ignition approaches: direct laser ignition and laser-driven flyer ignition. Experiments were performed using a Neodymium-doped Yttrium Aluminum Garnet (Nd: YAG) laser at different energy beam levels to systematically evaluate ignition onset. In the direct laser ignition test setup, the laser beam was applied directly to the energetic tested material, while laser-driven flyer ignition utilized 40 and 100 μm aluminum foils, propelled at velocities ranging from 300 to 1250 m/s. Comparative analysis with the Lawrence and Trott model substantiated the velocity data and provided insight into the ignition mechanisms. Experimental results indicate that the ignition time for the laser-driven flyer method was significantly shorter, with the pyrotechnic composition achieving complete combustion faster compared to direct laser ignition. Moreover, precise ignition thresholds were determined for both methods, providing critical parameters for optimizing ignition systems in energetic materials. This work elucidates the advantages and limitations of each technique while advancing next-generation ignition technology, enhancing the reliability and safety of propulsion systems.
{"title":"Advancing ignition techniques for energetic materials: A comparative study of direct laser ignition and laser-driven flyer methods","authors":"Răzvan-Marian Mircioagă , Baptiste Reynier , Tudor Prisecaru , Adrian-Nicolae Rotariu , Florin-Marian Dîrloman , Liviu-Cristian Matache , Laviniu Haller","doi":"10.1016/j.dt.2025.09.005","DOIUrl":"10.1016/j.dt.2025.09.005","url":null,"abstract":"<div><div>Conventional ignition methods are proving to be ineffective for low-sensitivity energetic materials, highlighting the need to investigate alternative ignition systems, such as laser-based techniques. Over the past decade, lasers have emerged as a promising solution, providing focused energy beams for controllable, efficient, and reliable ignition in the field of energetic materials. This study presents a comparative analysis of two state-of-the-art ignition approaches: direct laser ignition and laser-driven flyer ignition. Experiments were performed using a Neodymium-doped Yttrium Aluminum Garnet (Nd: YAG) laser at different energy beam levels to systematically evaluate ignition onset. In the direct laser ignition test setup, the laser beam was applied directly to the energetic tested material, while laser-driven flyer ignition utilized 40 and 100 μm aluminum foils, propelled at velocities ranging from 300 to 1250 m/s. Comparative analysis with the Lawrence and Trott model substantiated the velocity data and provided insight into the ignition mechanisms. Experimental results indicate that the ignition time for the laser-driven flyer method was significantly shorter, with the pyrotechnic composition achieving complete combustion faster compared to direct laser ignition. Moreover, precise ignition thresholds were determined for both methods, providing critical parameters for optimizing ignition systems in energetic materials. This work elucidates the advantages and limitations of each technique while advancing next-generation ignition technology, enhancing the reliability and safety of propulsion systems.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"55 ","pages":"Pages 180-192"},"PeriodicalIF":5.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145981813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01DOI: 10.1016/j.dt.2025.07.022
Zehua Liu , Yifan Yan , Haoying Pang , Xinhui Liu , Jixi Lu , Xusheng Lei , Zhuo Wang , Wei Quan
Atomic spin gyroscopes are promising candidates for next-generation inertial navigation due to extremely high theoretical precision, relatively small size among atomic gyroscopes, and promising potential for miniaturization. In particular, the spin-exchange relaxation-free (SERF) atomic gyroscope relies on optical pumping to polarize atoms, enabling rotation sensing through the Faraday optical rotation angle (FORA). However, fluctuations in atomic density introduce systematic errors in FORA measurements, limiting long-term stability. We present a data-driven decoupling method that isolates atomic density fluctuations from the FORA signal by modeling spatially resolved light absorption in the vapor cell. The model accounts for the spatial distribution of spin polarization in the pump-light interaction volume, density-dependent relaxation rates, wall-induced relaxation, and polarization diffusion, and is implemented within a finite-element framework. Compared to the conventional Lambert-Beer law, which assumes one-dimensional homogeneity, our approach captures the full three-dimensional density and polarization distribution, significantly improving the accuracy of light absorption modeling. The resulting absorption-density maps are used to train a feedforward neural network, yielding a high-precision estimator for atomic density fluctuations. This estimator enables the construction of a decoupling equation that separates the density contribution from the FORA signal. Experimental validation shows that this method improves the bias instability at σ (100 s) of the gyroscope was improved by 73.1% compared to traditional platinum-resistance-based stabilization. The proposed framework is general and can be extended to other optical pumping-based sensors, such as optically pumped magnetometers.
{"title":"Atomic density disturbance rejection in atomic gyroscopes via faraday polarimetric decoupling","authors":"Zehua Liu , Yifan Yan , Haoying Pang , Xinhui Liu , Jixi Lu , Xusheng Lei , Zhuo Wang , Wei Quan","doi":"10.1016/j.dt.2025.07.022","DOIUrl":"10.1016/j.dt.2025.07.022","url":null,"abstract":"<div><div>Atomic spin gyroscopes are promising candidates for next-generation inertial navigation due to extremely high theoretical precision, relatively small size among atomic gyroscopes, and promising potential for miniaturization. In particular, the spin-exchange relaxation-free (SERF) atomic gyroscope relies on optical pumping to polarize atoms, enabling rotation sensing through the Faraday optical rotation angle (FORA). However, fluctuations in atomic density introduce systematic errors in FORA measurements, limiting long-term stability. We present a data-driven decoupling method that isolates atomic density fluctuations from the FORA signal by modeling spatially resolved light absorption in the vapor cell. The model accounts for the spatial distribution of spin polarization in the pump-light interaction volume, density-dependent relaxation rates, wall-induced relaxation, and polarization diffusion, and is implemented within a finite-element framework. Compared to the conventional Lambert-Beer law, which assumes one-dimensional homogeneity, our approach captures the full three-dimensional density and polarization distribution, significantly improving the accuracy of light absorption modeling. The resulting absorption-density maps are used to train a feedforward neural network, yielding a high-precision estimator for atomic density fluctuations. This estimator enables the construction of a decoupling equation that separates the density contribution from the FORA signal. Experimental validation shows that this method improves the bias instability at <em>σ</em> (100 s) of the gyroscope was improved by 73.1% compared to traditional platinum-resistance-based stabilization. The proposed framework is general and can be extended to other optical pumping-based sensors, such as optically pumped magnetometers.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"55 ","pages":"Pages 1-10"},"PeriodicalIF":5.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145981911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01DOI: 10.1016/j.dt.2025.08.003
Tien Van Truong , Quoc-Viet Nguyen , Loan Thi Kim Au , Hung-Truyen Luong
Wing design is a critical factor in the aerodynamic performance of flapping-wing (FW) robots. Inspired by the natural wing structures of insects, bats, and birds, we explored how bio-mimetic wing vein morphologies, combined with a bio-inspired double wing clap-and-fling mechanism, affect thrust generation. This study focused on increasing vertical force and payload capacity. Through systematic experimentation with various vein configurations and structural designs, we developed innovative wings optimized for thrust production. Comprehensive tests were conducted to measure aerodynamic forces, power consumption, and wing kinematics across a range of flapping frequencies. Additionally, wings with different aspect ratios, a key factor in wing design, were fabricated and extensively evaluated. The study also examined the role of bio-inspired vein layouts on wing flexibility, a critical component in improving flight efficiency. Our findings demonstrate that the newly developed wing design led to a 20% increase in thrust, achieving up to 30 g-force (gf). This research sheds light on the clap-and-fling effect and establishes a promising framework for bio-inspired wing design, offering significant improvements in both performance and payload capacity for FW robots.
{"title":"The effects of bio-inspired wing vein morphology on thrust generation in double-clap flapping-wing robots","authors":"Tien Van Truong , Quoc-Viet Nguyen , Loan Thi Kim Au , Hung-Truyen Luong","doi":"10.1016/j.dt.2025.08.003","DOIUrl":"10.1016/j.dt.2025.08.003","url":null,"abstract":"<div><div>Wing design is a critical factor in the aerodynamic performance of flapping-wing (FW) robots. Inspired by the natural wing structures of insects, bats, and birds, we explored how bio-mimetic wing vein morphologies, combined with a bio-inspired double wing clap-and-fling mechanism, affect thrust generation. This study focused on increasing vertical force and payload capacity. Through systematic experimentation with various vein configurations and structural designs, we developed innovative wings optimized for thrust production. Comprehensive tests were conducted to measure aerodynamic forces, power consumption, and wing kinematics across a range of flapping frequencies. Additionally, wings with different aspect ratios, a key factor in wing design, were fabricated and extensively evaluated. The study also examined the role of bio-inspired vein layouts on wing flexibility, a critical component in improving flight efficiency. Our findings demonstrate that the newly developed wing design led to a 20% increase in thrust, achieving up to 30 g-force (gf). This research sheds light on the clap-and-fling effect and establishes a promising framework for bio-inspired wing design, offering significant improvements in both performance and payload capacity for FW robots.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"55 ","pages":"Pages 257-276"},"PeriodicalIF":5.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145981804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Al/NH4CoF3-Φ (Φ = 0.5, 1.0, 1.5, 2.0, and 3.0) binary composites and Al-NH4CoF3@P(VDF-HFP) ternary composites are fabricated via ultrasonication-assisted blending and electrostatic spraying. The effect of equivalence ratio (Φ) on the reaction properties is systematically investigated in the binary Al/NH4CoF3 system. For ternary systems, electrostatic spraying allows both components to be efficiently encapsulated by P(VDF-HFP) and to achieve structural stabilization and enhanced reactivity through synergistic interfacial interactions. Morphological analysis using SEM/TEM revealed that P(VDF-HFP) formed a protective layer on Al and NH4CoF3 particles, improving dispersion, hydrophobicity (water contact angle increased by 80.5% compared to physically mixed composites), and corrosion resistance. Thermal decomposition of NH4CoF3 occurred at 265 °C, releasing NH3 and HF, which triggered exothermic reactions with Al. The ternary composites exhibited a narrowed main reaction temperature range and concentrated heat release, attributed to improved interfacial contact and polymer decomposition. Combustion tests demonstrated that Al-NH4CoF3@P(VDF-HFP) achieved self-sustaining combustion. In addition, a simple validation was done by replacing the Al component in the aluminium-containing propellant, demonstrating its potential application in the propellant field. This work establishes a novel strategy for designing stable, high-energy composites with potential applications in advanced propulsion systems.
{"title":"Interfacial engineering of Al-NH4CoF3@P(VDF-HFP) core-shell energetic composites via electrostatic spraying: Enhanced stability and combustion performance","authors":"Xiandie Zhang, Zhijie Fan, Heng Xu, Jinbin Zou, Chongqing Deng, Xiang Zhou, Xiaode Guo","doi":"10.1016/j.dt.2025.06.020","DOIUrl":"10.1016/j.dt.2025.06.020","url":null,"abstract":"<div><div>Al/NH<sub>4</sub>CoF<sub>3</sub>-<em>Φ</em> (<em>Φ</em> = 0.5, 1.0, 1.5, 2.0, and 3.0) binary composites and Al-NH<sub>4</sub>CoF<sub>3</sub>@P(VDF-HFP) ternary composites are fabricated via ultrasonication-assisted blending and electrostatic spraying. The effect of equivalence ratio (<em>Φ</em>) on the reaction properties is systematically investigated in the binary Al/NH<sub>4</sub>CoF<sub>3</sub> system. For ternary systems, electrostatic spraying allows both components to be efficiently encapsulated by P(VDF-HFP) and to achieve structural stabilization and enhanced reactivity through synergistic interfacial interactions. Morphological analysis using SEM/TEM revealed that P(VDF-HFP) formed a protective layer on Al and NH<sub>4</sub>CoF<sub>3</sub> particles, improving dispersion, hydrophobicity (water contact angle increased by 80.5% compared to physically mixed composites), and corrosion resistance. Thermal decomposition of NH<sub>4</sub>CoF<sub>3</sub> occurred at 265 °C, releasing NH<sub>3</sub> and HF, which triggered exothermic reactions with Al. The ternary composites exhibited a narrowed main reaction temperature range and concentrated heat release, attributed to improved interfacial contact and polymer decomposition. Combustion tests demonstrated that Al-NH<sub>4</sub>CoF<sub>3</sub>@P(VDF-HFP) achieved self-sustaining combustion. In addition, a simple validation was done by replacing the Al component in the aluminium-containing propellant, demonstrating its potential application in the propellant field. This work establishes a novel strategy for designing stable, high-energy composites with potential applications in advanced propulsion systems.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"55 ","pages":"Pages 210-223"},"PeriodicalIF":5.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145981807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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