Journal of Military Science and Technology

Research on the fabrication of composite materials based on unsaturated polyester resin matrix and modified rice husk reinforcement

2025-02-20T13:08:35+00:00

In this study, rice husks (RHs) were utilized as fillers to create a reinforcing phase during the fabrication of composites based on an unsaturated polyester (UPE) resin matrix. The aim was to maintain the mechanical properties of the materials at a certain level and partially replace the amount of thermosetting resin used, thereby reducing negative environmental impacts. Sodium hydroxide (NaOH) and 3-methacryloxypropyltrimethoxysilane (MPS) were employed in the modification process of the RHs. The structure and morphology of the modified RHs were investigated using Fourier-transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM). Additionally, the mechanical properties of composite samples were evaluated according to international standards, such as ISO 527:2012, ISO 178:2019, ISO 604:2002, and ASTM D256. The results showed that the RHs sequentially modified by a NaOH solution and a MPS-dissolved mixture significantly improved the mechanical properties of the respective composites, compared to the composites with untreated RHs and RHs chemically modified by one solution. Specifically, compared to the reference samples formed by raw RHs, the best composite among ones with two-stage-treated RHs demonstrated flexural strength with an increase of 34.1% (reaching 45.1 MPa), compressive strength with a climb of 51.6% (reaching 33.8 MPa), tensile strength rising by 44.6% (at 34.3 MPa), and impact strength of 6.3 kJ/m² (18.9% higher). These results indicate that modified RHs can meet the research objectives and pave the way for further studies on RH-based composites.

Decomposition of methyl orange by Heterogeneous Electro-Fenton technology using ferrimagnetic oxide on activated carbon support as the catalyst

2025-02-20T13:18:04+00:00

The treatment of methyl orange in this study was carried out by application of Electro-Fenton process using Fe₃O₄/AC catalyst and electrode cells in an area of 100 cm². The efficiency of removing methyl orange was 98.86% with optimal conditions including: pH of solution 3.0, potential difference between two electrodes 15 V, initial concentration of methyl orange 20 ppm, catalyst dosage 0.8 g/L. The synthesized material has the ability to be reused, achieving the treatment efficiency of 78.5% after 4 reuses. The experimental results showed the potential of application the heterogeneous Electro-Fenton process for treatment of persistent organic compounds.

Research on the steel corrosion inhibition of green tea leaf extract in a simulated sea water environment

2025-02-20T13:42:39+00:00

In this paper, the effect of polyphenol compounds extracted from green tea leaves to inhibit CT3 steel corrosion in a simulated sea water environment was studied. The corrosion inhibitor is evaluated through some specifications: electrochemical corrossion and salt spray corrosion test by the B117-16 standard. A scanning electron microscope (SEM) and the salt-sprayed steel plate surface observation were used to evaluate the level of corrosion. The CT3 steel soaked in polyphenol solutions with various concentrations and times showed different corrosion resistance in marine conditions. At the polyphenol concentration of 1.5 mg in 1 liter solution, the corrosion rate of CT3 steel is reduced from 0.057 mm/year compared to 0.113 mm/year in the 3.5% NaCl solution without polyphenol, and soaking CT3 steel for 45 minutes in polyphenol : water : ethanol solution (1 g : 90 ml : 910 ml) gives the best resistance to salt spray corrosion.

Green synthesis of nano CeO2 using cleistocalyx operculatus leaf extract

2024-12-13T07:35:29+00:00

This study explores the green synthesis of CeO₂ nanoparticles using an extract from Cleistocalyx operculatus leaves, a traditional medicinal plant known for its high antioxidant content. A detailed solvent optimization process identified ethanol-water (1:1) as the ideal medium for extracting the maximum amount of polyphenols and flavanols, essential for reducing and stabilizing nanoparticles. The morphology, structure, and physicochemical properties of the synthesized nanoparticles were analyzed using advanced techniques such as FE-SEM, EDX, XRD, FT-IR, UV-Vis, BET, and Zeta potential analysis. The CeO₂ nanoparticles exhibited a fluorite cubic crystal structure with a crystal size of 12.04 nm, as determined by XRD. The nanoparticles demonstrated a high surface area (49.71 m²/g), stable zeta potential (-42 mV), and optical and functional properties characteristic of CeO₂. These results underscore the potential of green synthesis as an eco-friendly, cost-effective alternative for nanoparticle production.

Synthesis of MIL-101(Cr) metal-organic framework material and research photocatalytic capability of material for nitrate removal in water

2024-12-14T08:12:57+00:00

This paper presents the research results on some characteristics of the metal-organic framework material MIL-101(Cr) and its ability to remove nitrate from aqueous environments based on photocatalytic reactions. This material was synthesized using the hydrothermal method in the laboratory. Techniques such as FE-SEM, XRD, FT-IR, and BET were employed, demonstrating that the porous structure of the material is highly developed, with a specific surface area of up to 3017 m²/g and characteristic octahedral crystal size ranging from approximately 100 to 300 nm. Experimental results show that under UV light conditions at a wavelength of 365 nm and a power of 250 W, the MOF MIL-101(Cr) can catalyze nitrate removal under UV light, achieving a maximum removal efficiency of up to 99% after 180 minutes of reaction. The nitrate removal efficiency of MIL-101 is significantly improved, and reaches nearly 100% within a reaction time of 40 minutes when formic acid (HCOOH 46 mM) is used as a hole scavenger.

Geometries and thermodynamic stability of [Mo3Se132-]@TM (TM = Sc-Ni) clusters: A theoretical investigation

2024-12-18T03:56:31+00:00

We study the geometric structure and thermodynamic stability of Mo₃Se₁₃^2-@TM atomic clusters (TM = Sc, Ti, V, Cr, Mn, Fe, Co and Ni) using the B3LYP/LanL2DZ level within the density functional theory. The presence of transition metal in the Mo₃Se₁₃^2- clusters enhances the mobility of (Se-Se) terminals. Transition metal atoms preferentially attach to the sites, which forms the maximum number of bonds with Se atoms. Dissociation energy and entropy gradient analysis points out the Mo₃Se₁₃^2-@TM clusters favor to dissociate along two channels to create either Se-TM atoms or molecules. The [Mo₃Se₁₃]^2-@Ti, [Mo₃Se₁₃]^2-@Cr và [Mo₃Se₁₃]_2-@Ni can be predicted to be clusters with great catalytic potential due to high stability and minimum energy of 1.91, 1.57 and 1.78 eV, respectively.

Optical characterization of 2D heterostructure MoS2/WS2 using spectroscopic ellipsometry

2024-12-23T01:59:07+00:00

TMDC materials like MoS₂ and WS₂ are well known for their unique monolayer properties, ideal for optoelectronic applications. Stacking these monolayers enhances the properties beneficial for light detection and harvesting devices. This study investigates the dielectric function and critical point (CP) energies of heterostructure MoS₂/WS₂ using spectroscopic ellipsometry (SE) within the spectral range of 1.5 to 6.0 eV at different angles. The SE method, employing the Tauc-Lorentz model for detailed analysis, confirms the formation of high-quality TMDC heterostructure and provides precise values for intrinsic properties. These results are crucial for optimizing TMDC-based optoelectronic devices for military and commercial applications.

A method of calculating spectral characteristics applied to optimize the thermal imaging systems design

2024-12-10T00:44:41+00:00

In the design of thermal imaging systems, the selection of wavelengths and their relative weights plays a critical role in design optimization, directly influencing the system’s final performance. The spectral characteristics of a thermal imaging system, which encompass the distribution of wavelengths within the primary optical beam, must be thoroughly analyzed prior to initiating the optical design process. These characteristics are shaped by key factors, including the target’s emission spectrum, the medium’s and optical component’s transmission properties, and the detector sensitivity. This paper presents a detailed investigation and quantitative analysis of the spectral characteristics of a thermal imaging system under real-world environmental conditions, emphasizing their implications for system design. The findings provide valuable insights into how these spectral parameters influence design outcomes, contributing to enhanced research, optimized system development, and improved performance in practical applications.

A study on developing a computational model for determining operating parameters of a dual-flow solid rocket engine

2024-12-24T09:50:20+00:00

The aerodynamic launch principle operates with a complex mechanism, combining both artillery-like principles and solid-fuel engine concepts. Calculating and determining the working parameters of the launch motor is a crucial step in designing launch systems, especially when researching, developing, and manufacturing new systems. This is a mandatory requirement to ensure the functionality and reliability of the equipment. This paper focuses on developing a physical model to calculate the operating parameters of a dual-flow solid rocket engine over time, based on a set of hypothetical system parameters. The computational model presented in this paper, along with the resulting calculations, supports the investigation and design of systems while serving as a theoretical foundation for further, more comprehensive research. It also provides a basis for applications in research projects, improvements, upgrades, and the design and manufacturing of similar launch devices.

Solution for suppressing viscoelastic creep in cylindrical dielectric elastomer actuator

2024-10-25T06:37:26+00:00

The cylindrical dielectric elastomer actuator (CDEA) is known as a self-prestretching structure of dielectric elastomer actuators (DEAs). However, their inherent viscoelastic nonlinearity leads to nonlinear viscoelastic creep and hysteresis, which makes the modeling and control of CDEAs challenging and can affect their motion accuracy in practical applications. In this paper, the generalized KV-GM rheological model is employed to characterize the actuator's viscoelastic creep behavior, and an adjusted voltage signal is derived from maintaining a constant output stretch by making the input voltage time-dependent. Experimental results with the preprogrammed voltage demonstrate that the creep rate of the CDEA decreases from 27% to less than 9%. The proposed solution effectively minimizes energy dissipation caused by nonlinear viscoelastic properties, playing a significant role in promoting the practical application of CDEA.

Internal ballistics model of recoilless weapons with moving high-pressure chambered

2025-02-03T09:47:41+00:00

This paper presents an internal ballistics model for recoilless weapons with a high-pressure chamber, in which the chamber moves relative to the grenade. The model can also be applied to other scenarios, including a stationary high-pressure chamber, flowing out from high and low-pressure chambers, or a high-pressure chamber moving together with the grenade. The problem is solved using the numerical integration method in the MATLAB software. The maximum difference between the results of the mathematical model and experimental data was found to be 8.48% for both the case of a moving high-pressure chamber and a stationary chamber.

Simulation of 6DOF motion control loop of three-channel flight device

2024-12-17T03:33:26+00:00

The article presents a method for constructing a control system and simulating the closed-loop control of a 6-degree-of-freedom (6DOF) motion for a three-channel flight device (TLCT-3), modeled after the Javelin. Based on publicly available data on the tactical and technical features of the TLCT-3, the authors analyzed and calculated the geometric, inertial, and aerodynamic characteristics to provide input data for the controlled object in the simulation program. At the same time, the research team developed models for the command generation block, autopilot block, and controlled object block to design the simulation program. The simulation results, based on two scenarios of top attack and direct attack modes, confirm the accuracy of the models and their alignment with the tactical and technical features of the TLCT-3.

Developing a new step reduction algorithm to improve the efficiency of large-scale electrical and electronic circuit simulation: Mixed Balanced Short Cutting and Riccati-Lyapunov Mixed Balanced Short Cutting

2024-11-27T01:26:47+00:00

This paper studies model reduction methods (MOR) in simulation of large-scale electrical and electronic systems, in order to reduce computational costs and optimize performance while maintaining important physical properties. In particular, two new reduction algorithms, Mixed Balanced Truncation (MBT) and Mixed Riccati-Lyapunov Balanced Truncation (MRLBT), were developed to improve efficiency compared to Balanced Truncation (BT) and Positive True Balance Truncation (PRBT) methods. Both the MBT and MRLBT algorithms preserve the stability and passivity of the original system. The paper describes in detail the steps to implement the algorithms, compares their efficiency on the RLC power network, through simulations that conduct error analysis and simulate responses on the time and frequency domains. The results show that MBT achieves a balance between accuracy and computational cost, the deceleration error is between BT and PRBT, while MRLBT has the best performance and meets the deceleration requirements among the four algorithms considered.

A method of profile control applied in laser technology

2025-02-20T14:48:35+00:00

The proposed model allows the generation of any two-dimensional profile, which can be applied, for example, in laser welding and cutting techniques. In the paper, a system model for generating two-dimensional profiles using two galvanometer mirrors placed on two perpendicular axes is studied and designed. The forward and inverse kinematic equations establishing the relationship between the mirror motion and the laser profile are proposed and thoroughly solved by the author, and the author also presents the control problem to generate the desired profile. Simulations on Matlab are performed for circular and figure-8 profiles. The simulation results obtained profiles similar to the desired profile, both in shape and scanning frequency.

A design of Archimedean spiral antennas applied in passive radar

2024-12-17T07:37:28+00:00

Currently, spiral antennas are widely studied and applied for both military and civilian purposes. However, ensuring that the antenna system operates effectively across a wide frequency range while still meeting gain and directionality requirements is a complex problem. In this article, the authors present the results of research and design of spiral antennas operating in the 2 to 4 GHz frequency range (S band). The analysis of operating principles, calculations, and simulations using CST 2019 software demonstrates that the antenna system operates over a broad frequency range, meeting the requirements of passive radar stations.

Reinforcement learning based - sliding mode control for trajectory tracking of quadrotor unmanned aerial vehicles under disturbances

2025-02-21T03:57:08+00:00

In this article, a reinforcement learning (RL)-based sliding mode control (SMC) is proposed for trajectory tracking of a quadrotor unmanned aerial vehicle (QUAV) under external disturbances. First, an actor-critic RL framework sliding mode control is provided to tackle the optimal control problem without external disturbances. Secondly, the simulation in an environment with disturbances is carried out to show the robustness of the proposed controller. Theoretical analysis shows that the position and attitude tracking errors converge to a preset region, and the weight estimation errors of the actor-critic networks are uniformly ultimately bounded (UUB). Finally, a comparison of the numerical simulations between the proposed controller and traditional sliding mode controller and the Backstepping (BSP) technique is provided to indicate the advantages and improved performance of the RL-based SMC.

A method for determining look-angle stability parameters for VSAT control systems installed on ships with a non-orthogonal axis system

2024-11-27T01:22:03+00:00

The VSAT communication depends on many factors, such as signal strength, receiver sensitivity, and environmental interference factors. To ensure optimal signal quality, the VSAT antenna must remain properly aligned and polarized toward the satellite. For the VSAT system installed on the shipboard, the disturbances from waves, wind, and current significantly disrupt the antenna's ability to maintain a stable orientation toward the satellite target. To enhance structural efficiency, motion precision, and stiffness, some shipboard VSAT systems, such as the ORSAT AL7103 and AL7107, incorporate designs with motion axes that are not perpendicular. The article introduces a method for calculating look angle stability parameters for this type of VSAT system, including azimuth and elevation angles, rotation control angles, and the ship's attitude angles. Some experiment and simulation results support the theoretical analysis of the proposed method.

Improved performance of sonobuoys based on open source RISC-V SoC microprocessor technology

2024-12-23T02:10:18+00:00

This paper presents a SoC design solution using Rocket core supporting open source RV32GC RISC-V instruction set, verifying the design on pre-silicon platforms which are Vivado FPGAs. The SoC system includes Rocket RISC-V core integrating peripheral blocks UART, SPI, RAM, ROM, GPIO, TILELINK BUS and a SonarDetect block (custom hardware developed by the user). This solution is applied to replace the central processor of the PTA-18 sonobuoy [1],develop and upgrade the target identification feature compared to the old design. SonarDetect is a new user design block (Custom Hardware) that detects the signals of local sonar targets, compares with the given database to identify the target. The design is tested and implemented on the Arty-A7 100T FPGA development kit and aims at the next goals of smartening and chip-izing the buoy control circuit.

Research and implementation of the Kalman filter in 3D radar target tracking

2024-11-26T04:15:50+00:00

Tracking a moving target in three-dimensional (3D) space using radar requires the processing system to consistently and accurately update the target's position with minimal delay. The Kalman filter, a powerful tool for target tracking, is utilized to estimate the target's state from noisy measurement data. This paper presents the results of evaluating the effectiveness of the Kalman filter in estimating the altitude and tracking 3D radar targets instead of 2D in existing research. The tests are performed on highly mobile moving target models (UAVs, fighter aircraft, etc.). The evaluation criteria include the accuracy of position and velocity estimation, as well as the computational efficiency of the 3D Kalman filter. Finally, a solution for applying the filter to level 2 processing computers in 3D radar systems is proposed.

Developing a digital signature scheme avoids attacks based on the order of the generator element

2024-12-23T02:08:01+00:00

In this paper, we propose a new digital signature scheme based on composite discrete logarithms, which is a variant of the DSA signature scheme. Our new proposed scheme is more secure than the DSA signature scheme. Furthermore, the speed of computing of our scheme is faster than to some similar schemes. For this season, it can be applied in practice.