Journal of Military Science and Technology

Investigation of single mode high-power fiber laser used in industrial metal cutting machines

2024-12-27T04:48:06+00:00

High-power fiber lasers have demonstrated great potential in various industries such as industrial, medical, aerospace, defense, and many others. Utilizing single-mode fiber configuration offers advantages such as good beam quality, high power, stability, and efficiency. Therefore, high-power single-mode fiber lasers are applied in the manufacturing and processing of fine details. Ytterbium-doped active fibers are primarily used as the amplification medium, generating laser sources with powers exceeding 200W. The objective of this paper is to simulate the intensity distribution of single-mode fiber, analyze parameters affecting the output power of high-power fiber lasers, such as refractive index, core diameter, fiber length, pump scheme, and beam quality (M2). This aims to select optimal characteristics for single-mode fiber in specialized metal cutting laser machine applications.

Developing power control algorithms for dynamic multi-connection industrial wireless sensor networks

2024-12-27T04:51:11+00:00

In this paper, we propose a Dynamic Multi-Connection Industrial Wireless Sensor Network (DMC IWSN) model to improve data transmission efficiency in a factory workshop. We introduce a new power control algorithm called Window-Selection (WS), which adjusts sensor power based on predefined upper and lower limits. The algorithm reduces power when it exceeds the upper limit, increases power when it falls below the lower limit, and maintains power within these bounds. We compare the performance of the WS algorithm with the Max-Min (MM) algorithm, and a scenario no power control in terms of the weakest sensor capacity and total capacity in uplink transmission. Simulation results show that the WS algorithm achieves the highest capacities, while the MM algorithm moderately improves system performance in the DMC IWSN model.

Optimal slip estimator-based fixed-time control for anti-lock braking system in electric vehicles

2024-12-27T04:47:33+00:00

The Anti-lock Braking System (ABS) is a safety system that prevents the wheels from locking during emergency braking, ensuring the driver can maintain control of the vehicle and optimize braking distance. Therefore, research and experimentation on a robust nonlinear controller applicable to this system are highly important and necessary. This study proposes a Fixed-Time Control (FTC) strategy, aiming to converge the slip deviation within a predetermined time interval calculated in advance. The research also suggests an optimal slip estimator combined with the controller to enhance system robustness when the vehicle operates under different road conditions. Global Sliding Mode Control (GSMC) is introduced for comparison with the proposed controller. Simulation results using CarSim software combined with MATLAB/ Simulink have demonstrated the feasibility of the system.

A 8 GHz microwave substrate integrated waveguide power amplifier using complementary split ring resonators

2024-12-27T04:52:31+00:00

This paper introduces a design for a microwave substrate integrated waveguide (SIW) power amplifier (PA) for modern wireless communications. The amplifier design incorporates complementary split ring resonator (CSRR) structures integrated within the SIW to achieve low-loss characteristics and miniaturization through a below cut-off frequency operation approach. The designed PA operates at 8 GHz and exhibits good performance, which are measured output power P_out of 35.51 dBm, a maximum power added efficiency PAE of 47.2% and a power gain of 12.51 dB. The final circuit occupies just a compact size of 41 x 15.7 mm² benefiting from using the CSRR structure. The proposed PA employs a low-cost QFN packaged GaN HEMT device from Qorvo and it was designed and fabricated on a cost-effective RO4003C substrate. The simulated results agree well with the measured ones validating the accuracy of the design. With promising measured results, the proposed PA can be a potential candidate for using in the modern wireless communication systems.

A processing solution for target periodic tracking and selection in monoрulse radar

2024-12-27T04:48:39+00:00

The fire-control radar uses analog signals received in each transmitted cycle to separate the coordinate errors of the tracked target. The target selection and confirmation for tracking are carried out by the radar operator via disрlay screen. This paper proposes a method for processing target information displayed on the disрlay screen, ensuring two criteria: synchronization with high-speed tracking algorithms and the accurate provision of target data to support the target selection process on the screen.

Optimization of global path planning for asymmetric mobile robots

2024-12-27T04:50:38+00:00

This research focuses on optimizing global path planning for asymmetric mobile robots (AMRs), which are characterized by an asymmetric structure and mobility capabilities commonly encountered in practical applications. The objective is to propose a method for optimizing global trajectory planning, enabling efficient movement of asymmetric AMRs in complex environments, reducing task execution time, and optimizing operational performance. The study employs the SPBL algorithm to search for an optimal path in an environment based on an initial trajectory. The path following process utilizing the Dynamic Window Approach (DWA) is optimized by adjusting cost parameters for basic maneuvers such as straight-line motion, rotations, sliding, and reversing. These parameters are designed to prioritize smooth trajectories while avoiding complex and inefficient maneuvers. The results of the research demonstrate that the proposed method minimizes trajectory complexity, leading to reduced task execution time and improved operational performance of asymmetric AMRs. The findings have potential applications in robotic transport systems in the industrial sector.

Calculation and simulation of low Earth satellite orbit using least-squares method and on-board GPS data: case study of VNREDSat-1 satellite

2024-12-27T04:49:30+00:00

The article focuses on describing the results of precise calculation and simulation of low Earth observation satellite orbits using Least-Squares Method and GPS data collected on-board satellite. The calculation and simulation tool is implemented on Matlab and tested for real data of the VNREDSat-1 satellite. The purpose of this tool is to improve the accuracy of calculating low Earth observation satellite orbits compared to the method of using Two-line Element Set (TLE) files according to the standards of NORAD (North American Aerospace Defense Command). The results achieved will contribute significantly to the process of mastering the technology of ground control stations for Earth observation satellites, especifically the Flight Dynamics Terminal which is responsible for precise orbit determination and maneuver and supporting mission planning.

Deep learning models approach for maritime radar target data classification

2024-12-27T04:51:43+00:00

In maritime ra đa systems, reflection signals play a crucial role in target identification. The application of machine learning techniques, such as recurrent neural networks (RNNs) and convolutional neural networks (CNNs), has gained the attention of researchers in the field of ra đa data analysis. Both theoretical and experimental results demonstrate that these techniques can enhance ra đa target classification performance by utilizing a diverse amount of target data. However, the limited availability of real ra đa data has constrained the development of ra đa data analysis techniques. In this paper, we focus on analyzing and evaluating the performance of classification models, including SCNet, TARAN, TACNN, and RFRAN. We conduct experiments and fine-tune several parameters to improve classification performance. Experiments were carried out on Doppler ra đa and maritime ra đa datasets. The results show that SCNet and RFRAN can be optimized to effectively assist in maritime radar target recognition.

A method for constructing dynamic S-boxes based on fractional transformation

2024-12-27T04:50:22+00:00

This article describes the method for constructing a dynamic S-box based on fractional transformation on a finite field. The article shows the conditions of S-box, such as S-box is bijective. After that, the article describes S-box properties: nonlinearity, linear approximation probability, differential approximation probability, and algebraic degree. The paper proves that some important cryptographic properties of S-box based on fractional transformation are independent of coefficients a,b,c, d. Based on this, we propose an encryption algorithm with a dynamic S-box.

Recent advances in the development of carbon-based catalyst materials for fuel cells

2024-12-09T03:18:31+00:00

In recent years, the development of catalytic materials to enhance the efficiency of hydrogen energy conversion in fuel cells has become a primary focus in global scientific research. Platinum (Pt) and its alloys are widely used in fuel cells due to their superior catalytic properties; however, their high cost and scarcity limit broader application. Replacing Pt with carbon-based materials in fuel cell catalysts offers a promising pathway to reduce costs and enhance sustainability. Consequently, recent studies have shifted toward exploring non-precious metal catalysts based on carbon materials, which are of significant interest for their diverse applications and potential as viable alternatives to reduce amounts of Pt catalysts. This report presents and examines recent advancements in Pt-carbon hybrid catalysts for fuel cell applications, highlighting their synthesis, structural characteristics, and performance in hydrogen energy conversion.

Investigating the dynamic model of the flying object on the elastic background

2024-12-27T04:47:49+00:00

In the article, the dynamic model of the launcher on elastic ground is established using the Lagrange II equation. Using this model for the configuration of the airborne device launcher, the oscillation laws of the movements of the launch platform are determined. This allows for the assessment of the launcher’s oscillation on elastic ground during firing, serving as a basis for the design calculations of several structural components of the launcher, optimizing the firing for a class of launchers with the same structural principles and launching mechanisms.

Application of SMC-PID algorithm for anti-roll control for human-carrying robot

2024-12-27T04:52:16+00:00

The paper presents the application of the PID sliding control algorithm in anti-roll control for robots transporting people up and down stairs. Robots transporting people moving on complex terrain need to be analyzed and controlled to prevent rolling during the movement to ensure the robot's operation is effective and brings safety to the user. When the robot moves, the anti-roll control process is performed by controlling the position of the human transport mechanism with a linear actuator, which is an electric cylinder. The sliding control algorithm with the PID sliding surface is applied to control the response of the linear electric cylinder according to the change in the slope of the stairs to ensure the robot's anti-roll process by shifting the user's center of gravity. The simulation results of the application of the sliding mode controller to anti-roll control for robots are performed on Matlab Simulink software. The position of the anti-roll mechanism changes linearly according to the slope of the stairs, thereby showing the effectiveness of the controller for the anti-roll control process for robots. Simulation shows the effectiveness of the proposed algorithm, which helps the design and manufacturing process of human-carrying robots become more efficient.

Research on simulation of a bullet skimming the ground by the finite element method

2024-12-27T04:52:00+00:00

It is greatly complicated to research the process of bullets penetrating into the ground due to the diversity and heterogeneity of ground physical characteristics. The empirical formulas have been developed for scenarios involving deep penetration of bullets into the ground so far; however, equivalent calculations for bullets skimming the ground scenarios remain absent. This paper has established a finite element method (FEM) simulation model for deep penetration and validated it against empirical data. Leveraging this validated model, simulations have been extended to examine the bullets skimming the ground behavior of bullets. The results have delineated the impact angles at which bullets skimming the ground occur for soil with average compaction density. This methodology can be adapted to various soil types to construct a comprehensive set of parameters for bullets skimming the ground angles, thereby optimizing artillery performance.

Ambient air quality in Hanoi Capital: The current status and potential health risk of exposure

2024-12-27T04:51:27+00:00

Ambient air pollution in Hanoi is the most popular concern of not only the capital’s citizens but also soldiers which are garrisoned there. In this study, PM10, PM2.5, total particulate matter, O₃, SO₂, CO, NO₂ and NH₃ in ambient air at eight manual stations were determined four times in 2024. Moreover, analysis results of samples at both dry and wet deposition stations were calculated. That all data were combined with others from various sources to assess the status of ambient air in Hanoi and recognize the potential of citizens and local soldiers’ health impacts. The results showed that Hanoi’s ambient air quality was influenced by PM10, PM2.5 as well as total particulate matter. Even though, during the monitoring time of this study, some published data from various sources indicated that the quality of ambient air in Hanoi was not good, all air quality indicators in this research met the limit values in Vietnam national technical standard for ambient air quality QCVN 05:2023/BTNMT. The consequences of long-term exposure to particle pollution air can increase the risk of some diseases relating to respiratory, cardiovascular, and blood pressure, and particulate matter can also carry other toxins into the human body.

A study on the key characteristics of the explosive mixture ocfol-5.5

2024-12-27T04:50:54+00:00

HMX is currently one of the most powerful explosives. However, HMX has the drawbacks of being sensitive to impact and friction, having poor compressibility, and being difficult to directly load into various types of weapons. Ocfol-5.5 is a phlegmatized version of HMX, primarily composed of HMX (94-96%) and phlegmatizing agents (4-6%). This paper presents the results achieved in the research and development of Ocfol-5.5, the selection of phlegmatizing agents, and the orientation of the manufacturing technology. Optimal manufacturing parameters were selected in a laboratory setting. HMX was phlegmatized using a mixture of stearic acid (38%), ceresin (60%), and Sudan yellow pigment (2%). The phlegmatizing process was carried out by dispersing a water-phlegmatizing agent emulsion into a water-HMX suspension under stirring at 300 rpm and at a temperature of (85 ± 1) °C, gradually cooling at a rate of 1 °C per minute. The paper also identifies factors affecting the explosive and combustion properties of the product. The analysis results indicate that the technical specifications of the Ocfol-5.5 produced by the research group are comparable to those published abroad.

Fabrication of expanded vermiculite using the mixed methods of microwave and H2O2 agents for arsenic adsorption in water

2024-12-27T04:48:22+00:00

Among the technologies that have been studied to remove anions caused by Arsenic pollution, adsorption has received considerable attention. Vermiculite (VER) is a clay mineral that is abundant, low cost, environmentally friendly and is considered a potential adsorbent material for removing Arsenic from aqueous environments. In this work, expanded VER was studied for the adsorption of Arsenic(V) in water. The effects of concentration and time on adsorption efficiency were investigated in detail and fully. The maximum adsorption capacity of expanded VER for As(V) was 17.123 mg.g-1, and the saturation adsorption time was about 120 minutes. The kinetic model results showed that the adsorption processes followed second-order kinetics.

Synthesis of Cu-GPNs/Polyvinyl chloride (Cu-GPNs/PVC) nanocomposite for application as an electromagnetic wave reflecting material

2024-12-27T04:49:14+00:00

This article presents a method for synthesizing Cu-GPNs/PVC nanocomposite materials. Cu is synthesized from CuCl₂ salt using ascorbic acid as a reducing agent. Graphene nano sheet (GPNs) was synthesized using the oxidation method of graphite, then reducing it at high temperatures. The characteristics of Cu nanoparticles, graphene were determined using Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX), and X-ray diffaction (XRD). With a mass ratio of 5% nano Cu and 10% graphene, the Cu-GNPs/PVC nanocomposite film with a thickness of 0.6 mm can reflect from 86.89% to 90.78% at a frequency of 8-12 GHz.

Research on using naturally extracted capsaicin to develop irritant smoke agents as alternatives to military-grade CS gas

2024-12-27T04:48:56+00:00

Development of the LĐO-24 training tear gas smoke grenade, which uses capsaicin extracted from chili peppers as a substitute for the military-grade toxic agent CS. The LĐO-24 is safer for humans and the environment compared to conventional tear gas grenades. It can be used in combat readiness training and gas mask testing. Experiments on the mixing ratio of smoke-producing and irritant components, similar to those in the LĐC-16 grenade, indicate that the LĐO-24 training grenade possesses similar features to the LĐC-16. It generates an airborne smoke layer that irritates the eyes and respiratory system, with an optimal capsaicin concentration of 10% in the smoke mixture, achieving a capsaicin concentration of 0,0036 mg/m³ in the smoke layer. This irritant concentration effectively causes eye and respiratory irritation while remaining safe for personnel during training. The capsaicin's persistence in the air decreases over time, with tear gas effects lasting between 120 and 180 seconds.

Artificial Intelligence development, opportunities and challenges

2024-12-27T04:50:06+00:00

The article presents the development process, opportunities and challenges of artificial intelligence (AI), a field with many practical applications: Medicine, Management Economics, Education, Military, etc. The scope of artificial intelligence includes algorithms, heuristics, genetic algorithms, expert systems, artificial neural networks, fuzzy logic, etc. The article also analyzes the creation of intelligent machines that can think and make decisions independently and the arbitrary and dangerous use of this technology that can lead to disaster (as in the case of nuclear energy). However, concerns about the reduced importance of humans are unfounded because humans not only create intelligent machines but also create machines with their own consciousness and personality.