Journal of Military Science and Technology

Enhancing the accuracy of rainfall area classification in central Vietnam using machine learning methods

An Hung Nguyen — 2025-11-28

This study applies machine learning techniques, including Light Gradient Boosting Machine (LGBM), XGBoost (XGB), and Random Forest (RF), in conjunction with multi-source data comprising Himawari-8 satellite observations, ground-based rain gauge measurements, and auxiliary data such as ERA-5 reanalysis and the ASTER Digital Elevation Model (DEM), to enhance rainfall classification accuracy over Central Vietnam. Existing rainfall products in the region, including IMERG Final Run, IMERG Early, GSMaP_MVK_Gauge, PERSIANN_CCS, and FY-4A, are employed to evaluate the performance of the proposed classification approach. The results indicate that all proposed rainfall classification products exhibit high performance. Among them, the rainfall classification product based on LGBM achieved the highest performance across key evaluation metrics, including Probability of Detection (POD), Critical Success Index (CSI), Equitable Threat Score (ETS), and Heidke Skill Score (HSS). Compared to the investigated best-performing reference product, GSMaP_MVK_Gauge, the LGBM improves these metrics by 38.89%, 20.0%, 16.67%, and 13.04%, respectively. These findings highlight the potential of machine learning models, particularly LGBM, in enhancing the classification performance of meteorological models that utilize small but complex and high-dimensional datasets.

The quantum-resistant digital signature schemes based on new hard problems

Tuan Nguyen Kim — 2025-11-28

In this paper, we propose a family of quantum-resistant digital signature schemes built on novel hard problems defined over finite fields. These problems are, to the best of current knowledge, computationally intractable and therefore not susceptible to Shor’s quantum algorithm. Based on these problems, we present three concrete signature schemes with standard key-generation, signing, and verification procedures. We prove the correctness of each scheme and analyze its security against secret-key recovery and forgery attacks. Performance comparisons with representative post-quantum candidates illustrate that the proposed schemes achieve competitive key and signature sizes and efficient signing/verification times, making them attractive for practical deployment.

Direction estimation and tracking of rapidly moving RF emitters

Le Van Bao — 2025-11-28

Accurately localizing dynamic targets in complex and rapidly changing environments, such as unmanned aerial vehicles (UAVs), mobile platforms, or unstable moving objects-poses significant challenges in both civilian and military applications. This paper proposes an approach that integrates software-defined radio (SDR) technology with circularly polarized microstrip antennas to enhance localization performance under harsh conditions, including weak signals, multipath propagation, and disturbances caused by rapid motion. A simulation model is developed, and experimental analyses are conducted using an improved MUSIC algorithm for direction-of-arrival (DOA) estimation, combined with a second-order filtering technique. The results demonstrate a strong correlation between the simulated data and practical measurements, confirming the effectiveness of the proposed method.

Adaptive observer-based sliding mode control with time-varying learning using Riccati gain synthesis for robotic manipulators

Hoang Duc Long hoang — 2025-11-28

This paper presents an adaptive observer-based sliding mode control (AOSMC) framework integrated with time-varying learning rates and Riccati gain synthesis (RGS) for high-precision trajectory tracking of robotic manipulators under dynamic uncertainties and external disturbances. Conventional sliding mode control methods, while robust, often suffer from high chattering and require precise knowledge of system bounds. To address these limitations, the proposed AOSMC-RGS architecture combines a nonlinear disturbance observer with Riccati-based adaptive gain tuning, enabling real-time disturbance estimation and dynamic gain adjustment based on tracking errors. A rigorous Lyapunov stability analysis ensures boundedness and convergence of system states. Simulation studies on a 2-DOF robotic manipulator demonstrate significant improvements in tracking accuracy, disturbance rejection, and control smoothness compared to PID, SMC, ASMC, Fuzzy-ASMC, and RBF-ASMC controllers. The proposed approach achieves reduced overshoot, faster settling time, and lower control effort while maintaining robustness, making it a promising candidate for real-time robotic and mechatronic system applications.

Smooth robust adaptive sliding mode control of 2-DOF helicopter system

Dao Van Ba — 2025-11-28

This paper investigates the development of a tracking control system for a 2-degree-of-freedom (2-DOF) helicopter under parameter uncertainties and time-varying external disturbances. A nonlinear mathematical model of the 2-DOF helicopter system is first established. Subsequently, a conventional sliding mode controller (SMC) is designed, and its limitations in handling parameter uncertainties and external disturbances are analyzed. To address these limitations, the paper proposes a smooth, robust adaptive sliding mode controller for the 2-DOF helicopter system, ensuring convergence of closed-loop signals. The robust stability of the proposed controller is rigorously proven using Lyapunov stability theory. The system is simulated in MATLAB/Simulink with both the conventional and proposed controllers. Comparative simulation results demonstrate that the proposed adaptive robust controller outperforms the conventional sliding mode controller and fully meets the control requirements.

Improving the impact point accuracy of unpowered flight vehicles under uncertain wind conditions by using parameter-based adaptive control

Tuan Hung Pham — 2025-11-28

The paper focuses on the problem of pre-programmed trajectory tracking control under uncertain wind conditions for unpowered flight vehicles operating at transonic and subsonic speeds. In the vertical plane, the trajectory is assumed to be affected by the environment at low altitudes, where complex and unpredictable winds often occur, manifesting randomly as gusts, turbulence, or longitudinal winds. The influence of wind can cause significant deviations from the pre-programmed trajectory by hundreds of meters. To cope with these wind effects and improve the impact point deviation, an adaptive control combining Linear Quadratic Regulator (LQR) and Recursive Least Squares (RLS) based on model parameter estimation is implemented. Consequently, the adaptive LQR exhibits a flexible response and achieves high accuracy in tracking the pre-programmed trajectory. Compared with a non-adaptive one, adaptive LQR shortens the impact point deviation from tens of meters to meters.

Research on the design of a subsystem to connect and control multiple unmanned aerial vehicles simultaneously via the MAVLink protocol

Nguyễn Trung Thành Nguyễn Trung Thành — 2025-11-28

This paper introduces an innovative open-source software subsystem that extends QGroundControl to facilitate simultaneous connection and coordinated control of multiple unmanned aerial vehicles (UAVs) using the MAVLink protocol. Key enhancements include a comprehensive Vietnamese-language localization of the user interface, enhancing accessibility for non-English speakers, and a dedicated graphical swarm-management module for streamlined operations. The system ensures full compatibility with PX4 and ArduPilot flight stacks, offering scalable, map-based tools for multi-vehicle mission planning and execution. Furthermore, it supports seamless integration with ArduPilot SITL and Gazebo for robust pre-deployment simulation. Validation in a Software-in-the-Loop environment demonstrates reliable operation with three or more virtual UAVs, including group commands and synchronized mission execution without telemetry conflicts. The resulting cross-platform application (Windows and Linux) is released as open-source software, paving the way for broader adoption in Vietnam's growing UAV ecosystem.

Study on the synthesis of tetraglycidyl 4,4’-diamino-3,3’-chlorodiaminodiphenyl methane and application as an adhesive for flame-retardant cover and solid propellant rod

Dr Binh Le Duy — 2025-11-28

Tetraglicidyl 4,4'- diamino 3,3'- chlorodiaminodiphenyl methane was synthesized by a two-stage process. The first stage involved the addition polymerization reaction and the second stage involved the hydrochloride group reduction reaction. The synthesized product was measured, analyzed for technical parameters and compared with foreign samples using IR, ¹H NMR and ¹³C NMR spectra. The results showed that the physicochemical characteristics and spectral structure of the studied product were equivalent to foreign samples of the same type. The applicability was evaluated by manufacturing ОKZМS adhesive used as an adhesive for the flame-retardant cover and solid propellant rod for good adhesion quality, meeting the requirements.

Effect of CeO2 and CuO oxide nanoparticles on the nickel electroplating in sulfate solution

Dr Phuoc Mai Van — 2025-11-28

This study investigates the electrochemical behavior of nickel composite coatings containing CuO and CeO₂ nanoparticles using polarization and electrochemical impedance spectroscopy (EIS). The presence of CuO or CeO₂ oxide nanoparticles in the solution with the ranges between 2 and 12 g/L insignificant increased cathode polarization in the nickel sulfate plating solution. However, the EIS results showed that CuO particles had little effect on the solution resistance and plating process, while CeO₂ particles significantly increased the solution resistance, thus affecting the nickel plating rate. The solution's charge transfer resistance would rise due to the high concentration of added oxide particles, which will be detrimental to the electrode surface's deionization process, the plating solution's oxide particle content should not exceed 12 g/L.

Research on enhancing the corrosion resistance of epoxy-modified Fe3O4 coating on steel in a 3.5% NaCl environment Pham Hong Thach1, 2*, Phu Phuoc Huy2, Pham Trung Kien2, Tran Van

Hong Thach Pham — 2025-11-28

This study aims to improve the corrosion resistance of steel in a 3.5% NaCl environment by developing epoxy coatings containing surface-modified Fe₃O₄ nanoparticles. Fe₃O₄ was synthesized via co-precipitation, functionalized with 3-aminopropyltriethoxysilane (APTES) to improve dispersion, and combined with triethanolamine (TEA) as a surfactant to stabilize morphology. Five coating systems, pure epoxy, epoxy–Fe₃O₄, epoxy–Fe₃O₄/TEA, epoxy–APTES–Fe₃O₄, and epoxy–APTES–Fe₃O₄/TEA, were prepared. The nanoparticle structure and morphology were analyzed using XRD, FT-IR, SEM and EDX, while corrosion resistance was evaluated via potentiodynamic polarization (PDP) và electrochemical impedance spectroscopy (EIS). Results showed that APTES functionalization improved nanoparticle dispersion and interfacial bonding, while TEA reduced particle size and prevented agglomeration. The epoxy–APTES–Fe₃O₄/TEA system exhibited the best corrosion protection. These findings highlight the potential of modified epoxy nanocomposite coatings for marine steel protection.

Removal of methyl orange from aqueous solution by heterogeneous Electro-Fenton process using MnFe2O4/C catalyst

Pham Hong Tuan — 2025-11-28

In this study, the heterogeneous Electro-Fenton process using a manganese ferrite catalyst on activated carbon derived from sugarcane bagasse (MnFe₂O₄/C) was investigated for the removal of methyl orange (MO) dye from aqueous solution. MnFe₂O₄/C was synthesized by an impregnation-coprecipitation method and characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), X-ray diffraction (XRD). Electro-Fenton model using graphite electrodes. The experiment was carried out to examine the efficiency of MO removal under neutral pH conditions. The effect of various operational parameters, such as applied current, catalyst loading, initial methyl orange concentration, was investigated.

Research on the fabrication of camouflage coating based on Cr2O3 material

Dinh The Dung — 2025-11-28

This study reports on the fabrication and performance evaluation of camouflage coatings based on Cr₂O₃ nanoparticles and polyurethane resin. Cr₂O₃ nanoparticles were synthesized via a combustion method using Cr(NO₃)₃·9H₂O as the precursor and glycine as a fuel at a glycine/NO₃ ratio of 9:1. The obtained Cr₂O₃ nanoparticles, with sizes ranging from 40 to 60 nm, were uniformly dispersed within the polyurethane (PU) matrix coated onto the polyester fabric surface. Thermal imaging analysis using a FLIR BHM-Series Bi-Ocular Thermal Imaging Camera confirmed that the coatings provided enhanced and prolonged camouflage effectiveness.

Optimization of overhead crane main girder considering deflection constraint using differential evolution

Nguyen Minh Kha — 2025-11-28

Overhead cranes are one of the commonly used lifting and transporting equipment for hoisting, lowering, and moving goods within factories and warehouses. The main girder plays the most important role, directly bearing the loads during lifting operations and resisting various forces during crane operation. In this paper, the authors present an optimal design method for the main girder using the Differential Evolution method, taking into account the deflection constraint of the girder in two cases: hollow rectangular box section and I-shaped section. The research results of this paper provide an important scientific and practical basis for selecting reasonable structural parameters of the crane main girder, while also contributing to improving the efficiency of design, fabrication, and operation of the equipment. In addition, the results of this paper serve as a reference for comparing and evaluating the optimization of the two types of cross-sections, providing a basis for selecting the girder’s cross-sectional shape according to bending strength and deflection criteria.

Investigating the effect of the gap between the throttling ring and the control rod in the hydraulic braking mechanism on the stability of the cannon during firing

Lai Thanh Tuan — 2025-11-28

In this paper, a mathematical model is developed to describe the dynamics of the recoiling part of the cannon during both the recoil and counter-recoil (push-up) phases. Based on the analysis of the forces acting on the cannon during these phases, expressions are derived to evaluate the stability conditions - specifically, preventing the cannon from overturning upward during recoil and downward during counter-recoil. The influence of the gap between the throttling ring and the control rod of the recoil braking mechanism on the stability of the 85mm D44 cannon is investigated. The results show that a change in the gap to 1 mm does not cause instability (either upward or downward overturning) but does significantly affect the recoil velocity, recoil distance, and final impact speed during the counter-recoil process. These changes can potentially reduce the durability of the components or even cause structural failure of the cannon mechanisms. Therefore, it is essential to consider the tolerances of these parts during technical inspections, maintenance, and repair. This research can contribute to improving the reliability and maintenance effectiveness of field artillery systems under actual combat conditions.

Design and optimization of axial length in a -1× magnification image-inverting optical system

Lai Thanh Tuan — 2025-11-28

This paper focuses on optimizing the axial size of a -1x magnification image-inverting optical system. The objective is to shorten the distance between the object plane and the image plane. This is achieved by shifting the rear principal plane forward and moving the front principal plane backward. An inverting lens system with a focal length of 40.48 mm has been designed, achieving an object-to-image plane distance of 59.5 mm. The configuration consists of four singlet lenses, utilizing spherical surfaces in the design. The optical system achieves high image quality across the entire field of view, with MTF values exceeding 0.1 at a spatial frequency of 56 lp/mm.

Effect of laser peak power on LIDAR's ability to detect UAVs under changing atmospheric conditions

Thế Vĩnh Ngô — 2025-11-28

This study presents a comprehensive Link Budget analysis for optimizing laser peak power in a UAV detection LIDAR (light detection and ranging) system operating under variable atmospheric conditions. The analytical model combines Beer-Lambert atmospheric transmission law, Lambertian target scattering, and APD characteristics to establish relationships between power and range across four atmospheric scenarios (α ranging from 0.1 to 0.6 km^-1). Validated through Monte Carlo simulations, our analysis demonstrates that maintaining P_d= 0.9 for 0.3×0.3 m UAV targets at 1000 m requires adaptive power control from 3.75 kW to 10.18 kW. This research provides quantitative parameters for designing intelligent LIDAR systems with adaptive power modulation capability responsive to atmospheric conditions. Consequently, the system reduces power consumption by 40-60% compared to legacy systems that must continuously operate at maximum peak power regardless of clear or foggy atmospheric states.