Journal of Military Science and Technology

Finite-time sliding mode control for model-free nonlinear systems with adaptive disturbance bound estimation

Nguyen Quang Binh — 2026-05-25

This paper proposes a finite-time sliding mode controller for model-free SISO nonlinear systems within the framework of model-free control. Unlike previous studies that primarily focused on asymptotic stability and required prior knowledge of the upper limit of the disturbance, the proposed method uses a power approach law to achieve finite-time convergence, while simultaneously constructing an attenuated online adaptive disturbance amplitude estimation mechanism. This eliminates the requirement for prior knowledge of the disturbance bound in controller design and avoids the phenomenon of unlimited gain. The stability of the closed-loop system is demonstrated through a non-smooth Lyapunov function, establishing practical finite-time stability conditions and ISS robustness against slowly varying disturbances. The effectiveness of the method is verified through simulations on a standard nonlinear system with strongly nonlinear dynamics and a reference signal with breakpoints. The results show that the proposed controller significantly improves convergence speed, reduces integration errors (ISE, ITAE), and limits control vibration compared to traditional MFC-iPID and SMC controllers.

An extended-range improvement solution for a homing flight vehicle

Dr Khoi Nguyen Van — 2026-05-25

This paper presents an extended-range improvement solution for a controlled gliding flight vehicle (GFV) equipped with a TV-homing seeker by increasing the lifting surface area within allowable limits while preserving static stability. This modification requires a redesign of the flight control system to accommodate the new aerodynamic configuration. Furthermore, during extended-range gliding flight, the vehicle experiences significant variations in velocity and altitude; therefore, the designed controller must ensure robustness over the entire flight envelope and under external disturbances. Six-degree-of-freedom (6DOF) simulation results demonstrate that the proposed improvement Solution and synthesized control system enable the GFV to increase its operational range from 9 km to 16 km while maintaining a terminal impact angle of no less than 45 degrees.

Explicit kinematic-based control allocation for a four-degree-of-freedom redundant radar antenna drive system in target tracking

Tran Thang Le — 2026-05-25

The control of a 4-degree-of-freedom (4-DOF) serial manipulator is a key research area in industrial robotics, particularly when the system exhibits actuation redundancy or demands high performance and precision. Handling actuation redundancy and control allocation plays a crucial role in ensuring operational flexibility, dynamic stability, while optimizing criteria such as energy consumption, torque, or obstacle avoidance. Modern research has developed diverse strategies, ranging from traditional optimization-based methods to intelligent techniques integrating deep learning and adaptive control. However, for systems applied in military fields such as radar gimbals, explicit techniques are often prioritized for their simplicity and high reliability. This paper presents an explicit control allocation method for a 4-DOF radar gimbal that effectively resolves practical application-oriented constraints. Accordingly, the naturally incorporated kinematic constraints lead to a control allocation process that aligns with the radar gimbal's operational conditions.

Development of a generation dispatch algorithm for power plants to achieve economic efficiency in power system operation

Lâm Văn Đức — 2026-05-25

In power system operation, economic generation dispatch aims to maintain the balance between power generation and load demand while minimizing electricity production cost. Conventional approaches are usually based on complex mathematical optimization methods, which require iterative calculations with high computational effort and are difficult to implement in real-time dispatch centers. This paper proposes a generation dispatch algorithm based on a linear relationship between generator outputs and total system demand. The proposed method significantly reduces computation time while maintaining adequate accuracy and economic efficiency, making it suitable for real-time and automated power system operation.

A variance-reduced simulation for benchmarking CFAR detectors in non-homogeneous environments

TS Hung Pham Van — 2026-05-25

This paper presents an accurate and stable simulation framework for evaluating the detection performance of constant false alarm rate (CFAR) detectors in the presence of clutter non-homogeneity and interference. The proposed framework incorporates theoretically consistent threshold calibration for CFAR detectors and introduces a variance-reduced estimator for false-alarm probability based on conditional expectation. This approach enables reliable estimation of extremely small false-alarm probabilities without excessive computational cost. Clutter edge scenarios are modeled using an edge-aware formulation that ensures physical consistency between the reference window and the cell under test. Extensive numerical results validate the proposed framework under homogeneous clutter and demonstrate its effectiveness in analyzing detector robustness in the presence of multiple interfering targets and clutter edges. The results provide clear insight into the relative strengths and limitations of different CFAR detectors and highlight the importance of accurate simulation techniques for meaningful performance comparison in realistic radar environments.

Research and evaluation of factors affecting propagation performance in high-frequency surface wave radar (HFSWR) systems

Dr Tho Luu Duc — 2026-05-25

High-frequency surface wave radar (HFSWR) systems operating in the HF band (3–30 MHz) enable the detection of targets beyond the horizon by exploiting the electromagnetic surface wave. However, the propagation characteristics of HF waves are strongly affected by environmental conditions such as ionospheric electron density, geomagnetic disturbances, temperature, humidity, atmospheric noise, and terrain and geographical features. This paper presents combined research and simulation results to evaluate the extent to which these factors influence HF wave propagation under surface wave radar operating conditions. The results show that variations in environmental conditions lead to fluctuations in propagation loss, which directly affect the detection probability and the effective operating range of the radar system. The paper presents calculation and simulation results at a frequency of 10 MHz. The research results can provide a scientific basis for proposing design, fabrication, and deployment solutions for surface wave radar systems that are suitable for the natural conditions in Vietnam.

Acceleration of signal processing in modern radar based on GPU platform

Van Anh Tran — 2026-05-25

Modern radar systems aiming for high resolution, wide bandwidth, and real-time processing of large data volumes pose significant computational challenges to traditional signal processing approaches. Implementations based on CPUs, FPGAs (Field-Programmable Gate Array), or dedicated DSPs (digital signal processors) often fail to provide sufficient throughput and computational resources for intensive tasks such as matched filtering, fast Fourier transforms (FFTs), Doppler processing, digital beamforming, and synthetic aperture radar (SAR) image formation. To address these limitations, this paper proposes the use of graphics processing units (GPUs) as an acceleration platform for radar signal processing algorithms by exploiting the massive parallelism inherent in GPU architectures. The paper further presents performance measurements and evaluations conducted on representative radar datasets using various signal processing algorithms. The results demonstrate that GPU-based implementations can achieve speedups ranging from tens to hundreds of times compared to MATLAB-based CPU implementations. These findings indicate that GPU-accelerated signal processing is a promising solution for meeting real-time processing requirements in modern radar systems. In addition, computational complexity analysis and numerical accuracy validation between CPU and GPU implementations are provided to ensure the correctness and scientific rigor of the reported performance improvements.

Effects of competing interactions on phase transition temperature in the Ising model

Oanh Nguyen — 2026-05-25

This paper focuses on studying the influence of competitive interaction on the phase diagram in a disordered Ising model using the effective field method. The competitive interaction factor is controlled by two parameters, the competition probability p and the fluctuation D. We obtain a phase diagram divided into three distinct regions according to critical temperatures. Specifically, in the range 1 < D < 1.005 and D > 1.4, the system exhibits a single phase transition from ferromagnetic to paramagnetic states. In the range 1.005 ≤ D ≤ 1.4, two critical points t_c1 and t_c2 are formed corresponding to the AF – FM – PM phase transition sequence. Simultaneously, we observe that the shift of the phase transition temperature depends on the two model parameters (p, D), similar to the effect of doping concentration on the phase transition temperature in the doped manganese perovskites.

Evaluation of the 182Ta radiative strength function via χ^2-weighted model averaging

Hoang Phuc Nguyen — 2026-05-25

Determining the radiative strength function (RSF) for ¹⁸²Ta is currently hindered by fragmented experimental coverage, leaving significant discrepancies between theoretical models, especially in the regions where experimental data are unavailable. This work addresses this gap by evaluating an ensemble of 78 E1 and M1 model combinations using a -weighted averaging method constrained by total experimental strength data from the Oslo method. Among the models tested, the Hartree-Fock-Bogoliubov plus quasiparticle random phase approximation with the D1M Gogny force framework exhibits the highest consistency with experimental observations. This is followed by the microscopic exact pairing plus phonon-damping model. In general, our results demonstrate that this data-driven weighting significantly reduces theoretical variance.

A reliable centralized real-time multi-protocol data collection module for mission-critical vessel systems

Cong Pham — 2026-05-25

Sensor networks deployed on modern vessels operate under heterogeneous communication protocols and stringent real-time constraints, necessitating a mission-critical, centralized solution for deterministic data acquisition and pre-processing. This paper presents the design and implementation of an FPGA-based sensor data collection and reconstruction module that supports the simultaneous integration of MIL-STD-1553B, ARINC-429, and RS-422/485 interfaces within a unified architecture. System reliability and fault tolerance are enhanced through support for error-correction coding and the use of high-bandwidth on-chip memory in place of conventional off-chip storage, ensuring deterministic performance for real-time operation. Following acquisition and normalization, sensor data are aggregated and transmitted to a central monitoring system via a high-speed Ethernet interface. Experimental validation demonstrates stable operation, improved data integrity, and compliance with real-time processing requirements in complex environments.

Study on the influence of air in the recoil mechanism on artillery performance during firing

Lai Thanh Tuan — 2026-05-25

This paper investigates the influence of air and structural parameters of the hydraulic recoil mechanisms on the firing process and stability of artillery systems. A mathematical model is developed to describe the internal firing process of the artillery and the dynamics of the recoil components during both the recoil and counter-recoil phases. The paper also calculates the influence of air in the recoil mechanism on recoil resistance force, recoil velocity, recoil displacement, and force distribution characteristics by incorporating the compressibility of the fluid-air mixture through the effective bulk elastic modulus. The paper also investigates the influence of the initial working chamber volume of the recoil brake mechanism on the movement of the recoil components. Simulation results with the artillery D-44 85 mm show that neglecting the influence of air leads to a higher and earlier peak recoil resistance force, a shorter and less stable force stabilization zone, and therefore can cause adverse force impulses acting on the artillery structure. The research results provide a valuable theoretical basis for evaluating the working efficiency of the recoil braking mechanism, as well as contributing to improving the reliability, durability, and technical maintenance efficiency of ground artillery systems.

Synthesis, structural characterization, and application prospects of SiO2/CaCl2 composite materials for atmospheric water harvesting

Dao Nam — 2026-05-25

In this study, SiO₂/CaCl₂ composite materials were synthesized via a sol–gel method for atmospheric water harvesting applications. The effects of the SiO₂/CaCl₂ mass ratio and gel aging time on structural characteristics and adsorption performance were systematically investigated. The optimal synthesis conditions were identified at a SiO₂/CaCl₂ mass ratio of 1:1 with a gel aging time of 48 h. Structural properties of the synthesized composites were characterized using SEM–EDX, X-ray diffraction (XRD), and N₂ adsorption–desorption (BET) analysis. The results revealed a biphasic structure consisting of crystalline CaCl₂ dispersed within an amorphous SiO₂ matrix, with a specific surface area of 19.1 m² g⁻¹ and mesoporous characteristics. At room temperature (25–27 °C), the composite exhibited water adsorption capacities of 0.31 g g⁻¹ at 70% relative humidity (RH) and 0.39 g g⁻¹ at 90% RH, reaching equilibrium after approximately 60 h. Although a decrease in adsorption capacity was observed after thermal regeneration, the material retained considerable water uptake, demonstrating its potential for low-cost, decentralized atmospheric water-harvesting systems.

Valorization of industrial waste red mud into geopolymer adsorbent for fluoride removal from aqueous solution

Dr Dung Cong Tien — 2026-05-25

Red mud, a waste by-product of the Tan Rai alumina plant, was utilized as a precursor for geopolymer synthesis and evaluated for fluoride removal from water. Geopolymers were prepared by alkali activation with NaOH (1%, 5%, and 10%) and subsequently calcined at 200–800 °C. Structural and surface characterizations were performed using XRD and FT-IR. Among the tested conditions, the sample activated with 1% NaOH and calcined at 200 °C exhibited the best performance, achieving a maximum fluoride adsorption capacity of 48.31 mg/g with an equilibrium time of 4 hours, and was effective at pH ≤ 8.4. Adsorption data were best fitted to the Freundlich isotherm model compared with Langmuir and Dubinin–Radushkevich models, indicating multilayer adsorption on a heterogeneous surface. These findings highlight the potential of red mud-based geopolymer as a cost-effective adsorbent for efficient fluoride removal from contaminated water.

Toxicity-guided screening and identification of glycosides in extracts of dry leafless branches of Nerium oleander L. collected in Vietnam

Dr Hoang Le Huy — 2026-05-25

This study conducted toxicity-guided screening based on the Allium cepa L. root model in combination with chemical analysis. Accordingly, the crude ethanol extract (CEE) from dry leafless branches of oleander (Nerium oleander L.) collected in Vietnam was evaluated using three bioassay methods (A, B, and AB), all of which yielded Toxicity Unit (TU) values indicating low toxicity with a predominant effect on root growth inhibition. Among them, method AB produced the most stable response (EC₅₀ ≈ 433 µg/mL; TU = 0.231) and was therefore selected for subsequent toxicity screening of the derived fractions. Liquid–liquid partitioning of the CEE yielded HF, CF, and EAF fractions, of which the EAF exhibited the highest toxicity (TU = 0.50). The EAF fraction was further subjected to column chromatography, qualitative color reactions, and TLC–MS/MS analysis, leading to the identification of oleandrin and adynerin as the two major cardiac glycosides, with adynerin being predominant, consistent with the toxicity screening results. The integration of rapid root-based toxicity screening and TLC–MS/MS analysis demonstrates a promising approach for toxicity-guided identification of bioactive compounds from Nerium oleander L. extracts, providing a scientific basis for ecological toxin studies as well as plant waste management of this toxic species.