Journal of Military Science and Technology

Synthesis and structural determination of fluoran

Tue, 15 Apr 2025 00:00:00 +0000

Thermochromic materials have been widely applied in various civilian sectors, including textiles and healthcare, and hold significant potential for military applications. The prominent characteristic of these materials lies in their reversible color-changing ability in response to temperature variations. Among the compounds containing the xanthene moiety-a functional group commonly found in many dyes and pigments, fluoran stood out due to its high sensitivity in temperature-induced color transitions, particularly when combined with electron acceptors and suitable solvents. In this study, fluoran was synthesized via a two-step reaction involving phthalic anhydride, 3-diethylamino phenol, and p-bromophenol in toluene. The resulting product was a pink solid with a melting point in the range of 171 - 174 °C and a yield of 60,8%. The structure of the synthesized product was confirmed using advanced analytical techniques, including infrared spectroscopy (IR), one-dimensional nuclear magnetic resonance (1D NMR), and two-dimensional nuclear magnetic resonance (2D NMR).

Cobalt-doped biochar derived from coir fiber activation for peroxymonosulfate degradation of methylene blue

Le Minh Tri, Nguyen Thanh Tung, Ngo Van Thanh Huy, Tran Anh Khoa, Tran Anh Khoi — Tue, 15 Apr 2025 00:00:00 +0000

In this work, metal-impregnated biochar (Co-Biochar) was used to activate peroxymonosulfate (PMS) and degrade methylene blue (MB) in aqueous solutions. This procedure illustrates a possible method for transforming garbage into useful commodities. Coconut fiber was pyrolyzed in an inert environment to produce biochar, which was then modified with metal salts using the co-precipitation technique. The structural features of the resultant material were studied using sophisticated analytical methods such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and nitrogen adsorption-desorption isotherms. Following PMS activation, the catalyst degraded MB with remarkable efficiency. More than 90% of the MB was removed within 15 minutes using optimum conditions (0.05 g of catalyst, 100 mL of 50 mg/L MB solution, and 400 mg/L PMS). Additionally, the effects of various reaction parameters, such as catalyst dosage, PMS concentration, solution pH, and reaction temperature, were investigated. The findings suggest that Co-Biochar holds significant potential as a PMS activator for the treatment of MB in textile wastewater.

Investigation of methylene blue adsorption on activated carbon surfaces: A combined approach of experimental study and molecular simulation

Tue, 15 Apr 2025 00:00:00 +0000

Wastewater containing methylene blue, commonly found in dyeing and textile effluents, poses significant environmental risks if left untreated. It can severely pollute water bodies, disrupt ecosystems, and threaten human health due to its toxicity. This study examined the ability of activated carbon to adsorb methylene blue from water. The activated carbon was pre-treated with various KOH ratios, achieving a maximum adsorption capacity of 619.92 mg/g. The adsorption process was analyzed using kinetic and isothermal models. Results showed that the process was best described by the pseudo-second-order kinetic model and the Langmuir isotherm model, both demonstrating high R² values. Molecular simulation methods were applied to explore the adsorption mechanism in greater detail. The findings indicated a multilayer adsorption mechanism dominated by electrostatic interactions, which facilitate strong bonding between the activated carbon surface and methylene blue molecules. Overall, the study highlights the potential of activated carbon as an effective solution for removing methylene blue from polluted water sources.

Isolation and structural determination of compounds from Alstonia scholaris (L.) R. Br. (Apocynaceae), collected in Vietnam

Vu Minh Trang, Phan Minh Giang, To Phuong Linh — Tue, 15 Apr 2025 00:00:00 +0000

Alstonia scholaris (L.) R. Br. belongs to the genus Alstonia in the family Apocynaceae. For the first time, the current research phytochemically studied on A. scholaris, collected from Vietnam. By silica gel column chromatographic separation, a triterpenoid betulin (1) and a sterol β-sitosterol (3) were found in the ethyl acetate (EtOAc) extract of the leaves. Meanwhile, isolation of the methanol (MeOH) extract of the bark yielded a triterpenoid β-amyrin (2), a sterol β-sitosterol (3) and a free sugar compound sucrose (4). Oxidation of compound 1 with K₂Cr₂O₇ in an acidic medium resulted in betunic acid derivative (1a) with a yield of 43.8%. The structures of these compounds were determined by analysis of spectroscopic data.

Study on the development of 3D printing materials based on blend of polyamide 6 and polyamide 11

Tue, 15 Apr 2025 00:00:00 +0000

3D printed CF/PA6+PA11 filaments are created from a blend of BASF's polyamide 6 (PA6), Arkema's polyamide 11 (PA11), and carbon fibers from Toray (Japan). This study focuses on evaluating the blend ratios of PA6, PA11, and the composite ratios of the blend with carbon fibers in the production of 3D printed filaments. Key technical parameters such as tensile strength, flexural strength, and impact strength were measured to assess mechanical performance under filament fabrication conditions. The study determined that a blend ratio of 70:30 for PA6:PA11 provides the best compatibility. Based on the PA6 and PA11 blend, the 3D printed CF/PA6-PA11 filament achieved suitable mechanical properties with component ratios of PA6, PA11, short carbon fibers (≤ 0.3 mm), and long carbon fibers (0.3 mm – 1 mm) at 49%, 21%, 20%, and 10%, respectively.

Synthesis of an optimal backstepping controller with an adaptive extended observer for missile control systems

Dinh Hong Toan, Le Ngoc Giang, Truong Dang Khoa, Nguyen Cong Dinh — Tue, 15 Apr 2025 00:00:00 +0000

The paper proposes an optimal Backstepping linear quadratic regulator (BLQR) and an Adaptive extended disturbance observer (AEDO) to enhance control performance and disturbance estimation in nonlinear, uncertain systems. The BLQR controller is employed to handle nonlinearities and uncertainties while optimizing control quality, whereas the AEDO effectively estimates and compensates for disturbances in missile control systems. The authors demonstrate system stability based on Lyapunov stability theory and conduct simulations in MatLab/Simulink. The simulation results validate the effectiveness of the proposed approach.

Workflow for completing natural-language request with metric-semantic representation of environment

Nguyen Van Hung, Truong Xuan Tung, Le Viet Hong, Le Khanh Thanh — Tue, 15 Apr 2025 00:00:00 +0000

In mobile robotics and autonomous systems, a natural-language request can be completed by converting it into high-level and low-level tasks. To accomplish such a request, both these types of tasks must be implemented, along with an efficient method to bridge them. However, this problem is still open. This work presents a two-phase workflow (figure 1), including Comprehension and Implementation, based on a metric-semantic map to address this problem. In the Comprehension phase, also known as automated planning, the natural language request is converted into actionable plans using semantic information from the map. These plans are then passed to the Implementation phase, where tasks like navigation or manipulation are executed utilizing geometric information from the map. Moreover, we also conduct an experiment to illustrate how a natural-language request is implemented on a specific metric-semantic presentation of the environment, namely a 3D Scene Graph, with the following complete sequence: from creating the 3D Scene graph until getting the feasible output path. In addition, this work highlights limitations that need to be addressed in the future to enhance the proposed workflow.

Synthesis of adaptive control algorithms based on output feedback with an implicit reference model for application on aerial vehicles

Nguyen Viet Phuong, Nguyen Duy Khanh — Tue, 15 Apr 2025 00:00:00 +0000

This paper addresses adaptive control for an aircraft's longitudinal motion under parameter uncertainty. A mathematical model is developed, and simulations validate the proposed approach. A linear modal controller is designed for nominal parameters, while an adaptive controller with an implicit reference model ensures stability under uncertainties. MATLAB/Simulink simulations on the UAV-70V model show that the linear modal controller performs well with known parameters but becomes unstable with variations. In contrast, the adaptive controller maintains robust stability, rapid response, and precise trajectory tracking. These findings confirm its effectiveness in uncertain environments.

Synthesis of control command for single-channel flying equipment by pulse width - amplitude modulation method

Pham Van May, Do Anh Cuong, Tran Duc Thuan, Chu Hoa Lu, Lam Van Duc — Tue, 15 Apr 2025 00:00:00 +0000

The article examines the method of synthesizing control commands of single-channel flying equipment (TBBMK) with infrared homing heads currently in use; These methods require the rudder angle to be able to change from the maximum negative value to the maximum positive value continuously or in steps. Through analyzing the mathematical model describing the flight dynamics of TBBMK based on the assumption of actual flight conditions, the authors propose to control TBBMK according to the pulse width - amplitude modulation (PWAM) method.

Optimal sizing of battery energy storage systems considering degradation and replacement in microgrids

Tue, 15 Apr 2025 00:00:00 +0000

In recent years, the integration of Battery Energy Storage Systems (BESS) has played a crucial role in ensuring the reliability and efficiency of microgrids. This paper presents an optimal sizing model for BESS, considering operational degradation and replacement over the system's lifecycle. The proposed model integrates technical, economic, and environmental aspects in the operation of microgrids, while also accounting for the degradation rate of batteries. A Mixed-Integer Nonlinear Programming (MINLP) approach is used to minimize the total system cost, including investment, operation, and replacement costs, while satisfying constraints related to load demand, renewable energy integration, and system reliability. Simulation results demonstrate that the proposed optimal model is highly effective in determining both the capacity and installation cost of the energy storage system. Additionally, the model can support the development of efficient operation scheduling and management strategies for BESS.

Parallel encoding and decoding algorithms with optimized hardware architecture for polar codes to reduce complexity and processing time

Dang Trung Hieu, Tran Van Nghia, Nguyen Thi Thuy — Tue, 15 Apr 2025 00:00:00 +0000

This paper presents the development of a simplified equivalent algorithm for fully parallel encoding and decoding of polar codes, which reduces computational complexity and minimizes processing latency compared to existing parallel encoding and decoding methods. The algorithm is implemented in the System Generator/Vitis Model Composer with parameterization capabilities, enabling easy maintenance and adaptation of FPGA designs for future standards. The design accuracy is validated through MATLAB simulations of the standard 3GPP code, and RTL synthesis using Vivado significantly improves latency and throughput.

Research on technical solutions for digital signal processing to enhance the reception quality of air defense radar systems

Bui Chi Thanh, Vu Chi Thanh, Le Van Viet, Tran Duc Thien — Tue, 15 Apr 2025 00:00:00 +0000

The paper presents the signal processing algorithm, hardware design solution, and software development of the digital signal processing module for linear frequency modulated signals to improve the signal-to-noise ratio and reduce computational overload in the system. The proposed signal processing algorithm performs direct analog-to-digital conversion of two quadrature channels, downsampling filtering, optimization filtering, and signal correlation compression filtering. The selected functional components feature several advantages such as high gain, high speed, and ready availability in the market. The hardware design and software development were carried out following a survey–simulation–prototype process, ensuring high logical coherence and systematic integration. The final product has been successfully validated on both test benches and radar systems.

RegC2P: A registration-enhanced GAN for 3D CT-to-PET translation

Nguyen Thanh Trung, Le Ke Hung — Tue, 15 Apr 2025 00:00:00 +0000

The fusion of Positron Emission Tomography (PET) and Computed Tomography (CT) has significantly advanced cancer imaging by combining metabolic and anatomical information, enhancing diagnosis, staging, and treatment monitoring. However, the widespread use of PET/CT systems is limited by the scarcity of PET scanners and the reliance on radioactive tracers. To address this, 3D image-to-image translation has emerged as a promising solution for generating synthetic PET images from CT scans. Existing generative methods based on Generative Adversarial Networks (GANs) face challenges such as instability and stochastic outputs that lack precision for reliable 3D CT-to-PET translation. We propose RegC2P, a novel approach that integrates a registration module into a GAN-based framework to generate accurately aligned 3D PET images from CT scans. RegC2P transforms the problem into a slice-by-slice 2D image-to-image translation task, where individual 2D CT slices are translated into PET slices and then stacked into a 3D PET volume. Misaligned 2D PET slices are treated as noisy labels, and the generator is trained with an additional registration network to adaptively correct the misalignment, optimizing both the translation and registration tasks simultaneously. To ensure smoothness and consistency across generated PET slices throughout the entire volume, we introduce a 3D U-Net refinement network. Extensive experiments on large datasets demonstrate that RegC2P outperforms state-of-the-art methods, achieving a 10.16% reduction in MAE, a 0.96% improvement in SSIM, and a 3.6% increase in PSNR, setting a new benchmark for the quality of synthesized 3D PET images.

Explosion sound classification using machine learning method based on audio features

Nguyen Van Tuan, Nguyen Dang Tuan — Tue, 15 Apr 2025 00:00:00 +0000

This study focuses on the classification of gunshot sounds using multiple audio features and machine learning methods. The gunshot sound samples are converted into spectrograms and processed using Support Vector Machine (SVM) for classification. The model was trained on a dataset of 851 audio files from 8 different gun types. Using a combination of audio features along with data preprocessing techniques, our SVM model achieved 95.32% accuracy in classifying different types of gunshots. The model also demonstrated good performance with real-world data, though with lower confidence levels due to environmental noise. This study provides an effective method for gunshot classification in defense security surveillance systems and sound forensics applications.

Study on the effect of pressure on the thrust force of a solid propellant engine operating in a water environment

Tue, 15 Apr 2025 00:00:00 +0000

The paper presents the results of research on the impact of ambient pressure on the thrust of solid rocket engines when operating underwater at different depths. The study establishes a system of equations for rocket propulsion, considering the variations in ambient pressure while functioning in an aquatic environment. It develops algorithms and constructs a computational program for rocket propulsion in solid rocket engines operating underwater. The paper further explores how water pressure affects the engine's pressure and thrust.

The trajectory simulation of an anti-submarine missile motion

Nguyen Hanh Hoan, Nguyen Van Hoa, Dang Van Hung, Le Tuan Anh — Tue, 15 Apr 2025 00:00:00 +0000

This paper analyses an anti-submarine missile's aerial motion, water entry motion and under- water motion. It establishes equations of motion for each phase and presents the ballistic characteristics of each section. According to the model, a trajectory is simulated. The method and the result provide an efficacious guarantee for the operational employment of an anti-submarine missile. It thus provides a basis for the design and calculation of an anti-submarine missile.

Study on three-stage T6I6 aging technology to improve the mechanical properties of B95 aluminum alloy

Nguyen Dinh Chien, Nguyen Van Duong, Nguyen Tai Truong, Luc Van Thuong — Tue, 15 Apr 2025 00:00:00 +0000

In this article, a study on the three-stage T6I6 aging technology is conducted to improve the mechanical properties of B95 aluminum alloy. After annealing and quenching, B95 aluminum alloy samples were aged in three stages (T6I6) according to four different regimes. Additionally, the authors investigated the traditional T6 artificial aging technology as a basis for comparison with the three-stage T6I6 aging treatments. Based on the results from hardness measurements, tensile testing, optical microscopy, FE-SEM, and electrical conductivity measurements, it was found that the three-stage T6I6 aging treatments achieved a higher density of intermetallic phase precipitates and improved mechanical properties (hardness, tensile strength, and yield strength) compared to the T6 aging technology. The optimal T6I6 aging process is determined as follows: first stage at 130 ºC for 1 hour, second stage at 95 ºC for 10 hours, and third stage at 130 ºC for 20 hours, resulting in a hardness of 185 HV, tensile strength approximately 9.1% higher, yield strength approximately 23.5% higher, and elongation approximately 1.83 times greater than those of the quenching and artificial aging process per ГОСТ 21488-97 standards.

Performance analysis of semi-active suspension in an electric vehicle with acceleration-driven damping

Bui Van Cuong, Le Van Quynh, Nguyen Tien Dung, Hoang Anh Tan — Tue, 15 Apr 2025 00:00:00 +0000

In order to enhance ride comfort performance of an electric vehicle (EV) semi-active suspension system (SASs), a 5-degree-of-freedom dynamic model of an EV is proposed to analyze their effectiveness on ride comfort. A SASs with Acceleration-Driven Damping (ADD) is proposed for enhance ride comfort performance of EV SASs. The Firefly Algorithm (FA) is used to optimize the ride performance of the SASs. The root mean square (RMS) values of vertical driver’s seat acceleration (a_ws), vertical body vehicle acceleration (a_wb), and pitching body vehicle acceleration (a_wphi) are selected based on the ISO 2631:1997(E) standard. The achieved results indicate that the a_ws, a_wb and a_wphi values with the proposed SASs respectively reduce by 12.07%, 6.85%, and 21.47% compared to the original passive suspension systems (PSSs) when vehicle moves on ISO road class B at a speed of 20 m/s and full load. In addition, the ride effectiveness is verified under various vehicle velocities.

Experimental research and evaluation of thermal camouflage effectiveness of advanced materials for mobile vehicles

Tran Tien Bao, Tong Minh Hoa — Tue, 15 Apr 2025 00:00:00 +0000

Mobile vehicles, with high heat-generating engines and metallic outer shells known for their significant heat absorption and emission, are easily detected and identified by thermal imaging reconnaissance systems. To mitigate thermal contrast, a practical solution is to apply coatings capable of reducing thermal emissions from mobile vehicles. However, no domestic studies have yet evaluated the effectiveness of thermal camouflage coatings for such vehicles. This paper focuses on analyzing the composition of advanced coating materials, conducting experimental trials, and assessing their thermal camouflage effectiveness for mobile vehicles in Vietnam. The findings of this study serve as a foundation for developing new materials and effectively applying thermal camouflage to mobile vehicles in the country.

Fabrication of photothermal carbon nanodot materials coated with luffa evaporation structure for solar energy water evaporation

Le Minh Tri, Nguyen Trong Cuong, Pham Hong Thach — Tue, 15 Apr 2025 00:00:00 +0000

Solar water evaporation is considered one of the most sustainable and environmentally friendly technologies. To achieve good evaporation performance, a combination of materials with good photothermal conversion efficiency and good evaporation structure is required. In this study, we used carbon nanodots as a photothermal material made that synthesis by hydrothermal of urea and citric acid. At the same time, luffa possessing advantages such as good water transport and easy attachment of carbon nanodots was chosen as the evaporation structure. The results showed that carbon nanodots material had an average size of less than 5 nm and a good absorption range in the wavelength of 200-800 nm. The absorption range of the material has expanded to the near-infrared region (NIR region), increasing the ability to absorb sunlight and convert it into heat energy, subsequently, improving the evaporation efficiency. The carbon nanodots/ luffa composite structure showed a high evaporation rate of 1.25 kg.m^-2h ^-1 under 1 sun irradiation (1 kW.m^-2).