Vojnotehnički glasnik / Military Technical Courier

Front impressum for the issue 1-2026

Vladan Anicijevic — 2026-03-18

Contents for the issue 1-2026

Vladan Anicijevic — 2026-03-18

Sustainable fibre-concrete reinforcement using manufacturing by-products

Ilyes IRKI — 2026-01-20

Introduction/purpose: Concrete is a material with very high compressive strength compared to very low tensile strength, which makes it brittle when subjected to tensile and bending stresses, with premature failure manifested by cracking. These stresses can be improved by reinforcing concrete with different types of fibres derived from industrial or other wastes.

Methods: In this context, this work aims to use industrial metal waste in concrete and compare it with metal fibre concrete to overcome this tensile strength deficiency. Two types of industrial fibres and two other types of waste were used, aluminium and steel waste (in the form of shavings) recovered from mechanical milling plants. The properties of the different fibre concretes in the fresh and hardened states are analysed and compared with natural non-fibre concrete.

Results: The experimental results suggest that incorporating such waste in concrete reduces the workability of concrete mixtures, improves the tensile strength of concrete, and reduces considerably its shrinkage without affecting its compressive strength.

Conclusion: Following a rigorous analysis of the obtained results, it was determined that the optimum percentage of recycled fibre in steel is 15%. The tensile strength at this level is comparable to that of industrial fibre-reinforced concrete. This finding is very relevant to the sustainable development strategy of the Algerian government, which promotes the improvement of characteristics and the conservation of natural resources.

Selection of 3D Printer for racing car spoilers using Entropy - CRADIS model

Rajeev Ranjan — 2026-01-20

Introduction/purpose: This study aims to identify the most suitable 3D printer for manufacturing racing car spoilers.

Methods: Sixteen different 3D printing machines are evaluated based on eight selection criteria. The criteria weights are determined using the Entropy method, while Compromise Ranking of Alternatives from Distance to Ideal Solution (CRADIS) method is applied to rank the machines and identify the best option for spoiler production. Sensitivity analysis is conducted using various methods to validate the results.

Results: Ultimaker 2 is identified as the most suitable 3D printer, followed by Delta Non-Turbo WASP 2040, while UP Plus 2 ranks as the least favorable.

Conclusion: By using the Entropy and CRADIS method, Ultimaker 2, is identified as the best-performing 3D printer, followed by Delta Non-Turbo WASP 2040, while UP Plus 2 received the lowest ranking. Various MCDM methods are applied for performance comparison and sensitivity analysis, with the Spearman Rank Correlation Coefficient applied to assess the correlation between different MCDM methods.

Comprehensive study of the effect of a structural parameter of hydraulic buffer on the firing stability of grenade launchers

Dung Nguyen Van — 2026-01-20

Introduction/purpose: The article's main goal is to present a novel method for evaluating the stability of automatic weapons mounted on tripods when firing in series.

Methods: The mathematical model is established based on the theory of many-body mechanics. The Lagrange II equation is used to establish the system of differential equations of motion of mechanical system. The mathematical model considers the influence of the ground elasticity and the impact of the gunner through elastic-damping connections. Dynamic simulations were performed on the AGS-17 grenade launcher. The calculated results were then compared with the experimental results to verify the proposed model.

Results: The comparison results show an unexpected confidence level between the theoretical model and experimental results. The errors in muzzle velocity and firing rate are 2.52% and 6.18%, respectively. Based on the theoretical basis of the mathematical model, the influence of some structural parameters of the hydraulic buffer on the firing stability of the automatic grenade launcher was investigated. The research results provide a reliable theoretical basis to improve, design, and manufacture hydraulic buffers for grenade launchers in particular and automatic guns in general.

Conclusion: The research results presented in this paper ensure high accuracy and reliability. This paper provides a reliable scientific document for the optimal design of the overall structure of the weapon system.

Laser obscuration and infrared emission characteristics of red phosphorus and mg-al based smoke composition

Dinh Thang Pham — 2026-01-20

Introduction/purpose: The capability for laser attenuation and infrared (IR) radiation emission is one of the most essential characteristics determining the camouflage effectiveness of multispectral smoke screens on the battlefield. In this study, the effects of red phosphorus and Mg-Al content, the initial mass of the smoke composition, and the relative humidity on the obscuration characteristics of smoke cloud, including the degree of laser attenuation, the mass extinction coefficient, the Yield factor, and the Figure of Merit, were examined. Additionally, the IR emission properties of smoke screens based on RP/Mg-Al were also evaluated.

Methods: Laser radiation attenuation was evaluated by comparing the initial laser power to the power measured after passing through the smoke screen. A 1.064 µm, 11.0 mW continuous-wave laser was transmitted through the test chamber and measured with a power meter. The infrared properties of the smoke clouds were analyzed using an SR-5000N spectral radiometer within the 2.5 – 14.0 µm range.

Results: The results indicate that increasing the content of red phosphorus, sample masses, and relative humidity enhances the laser obscuration characteristics. Notably, for a 1 m³ smoke chamber, the estimated optimal sample masses are 3.25 g and 2.30 g at 65% and 90% relative humidity, respectively. Furthermore, increasing Mg-Al content enhances IR emission in the β band (3-5 μm), while emission in the γ band (8-14 μm) decreased.

Conclusion: The laser obscuration characteristics of RP/Mg-Al-based smoke compositions can be effectively controlled by optimizing the RP/Mg-Al content and relative humidity levels. Moreover, the RP/Mg-Al-based compositions demonstrate strong IR radiation characteristics, which are also influenced by the content of RP and Mg-Al. Future research should focus on evaluating the obscuration characteristics of RP/Mg-Al-based compositions in the near- and far-IR regions.

Some considerations on thermodynamics of quantum mechanics on a circle and Kałuża–Klein models

Nicola Fabiano — 2026-01-20

Introduction/purpose: Quantum mechanics on a circle has been investigated and applied to a Kałuża–Klein model with a compactified dimension.

Methods: Methods of quantum mechanics and statistical mechanics were employed. Additionally, a Kałuża–Klein toy model with compactified dimension was considered.

Results: The resulting partition function can be evaluated in a closed form, giving a special function. It presents a phase transition depending on the geometry. When used in a Kałuża–Klein model, it showed a phase transition regulated by the radius of the circle, and the transition disappears when the radius is infinite, that is in the flat space.

Conclusion: Quantum mechanics on a circle exhibits many peculiar characteristics. Energy levels are discrete because of the geometry, in contrast to the configuration space of the real line. It presents a phase transition depending on the circle radius, also when embedded in a Kałuża–Klein model. This characteristic disappears when the radius becomes infinite, in the flat space.

Contribution to the damage analysis of pipeline cracking under high pressure

Fezazi Amina Ismahene — 2026-01-20

Introduction/purpose: This study aims to contribute to the prediction of pipeline damage caused by cracking in hydrocarbon-transport pipelines, subjected to high internal pressures, in response to the growing demand in industrialised countries.

Methods: To achieve this objective and analyse crack propagation in terms of Stress Intensity Factor (SIF) evaluation, the Finite Element Method (FEM) was employed. The study considers the effects of the transported medium's internal pressure on the one hand, and external stresses caused by natural phenomena such as earthquakes, landslides, and others, on the other. These external stresses are represented by tensile and compressive forces. Particular attention was given to the propagation of three types of cracks: circumferential, longitudinal, and mixed-mode cracks.

Results: The affected tubular structure zone is highly susceptible to mode I cracking. In contrast to the two initial types of cracking defects, an oriented crack at an angle of π/4 with respect to the pipeline's longitudinal axis develops nearly equally in modes I and II. Its growth kinetics are closely linked to its size, internal pressure, and the intensity of external forces.

Tensile forces promote the opening of circumferential cracks, the closure of longitudinal cracks, and mixed-mode (I and II) propagation of oriented cracks. Conversely, compressive forces favour the closure of circumferential and oriented cracks while encouraging the opening of longitudinal cracks.

Conclusion: The study reveals that, under identical loading conditions, longitudinally initiated cracks pose the greatest danger in terms of mode I crack growth. The risk of pipeline rupture is particularly high along the pipeline, and it increases significantly with higher internal pressure.

Application of the FMECA method for identifying failures in wind turbine systems

Branislava Radišić — 2026-01-20

This paper presents the potential causes of component failures in wind turbine systems that affect their reliable and efficient operation. Component failures in wind turbines can lead to complete system failure, resulting in downtime, reduced reliability, and increased costs. To fully utilize wind energy, minimizing the risk of component failures is essential. By applying the FMECA method (Failure Mode Effects and Criticality Analysis – FMECA), critical components of wind turbine systems have been identified, providing the opportunity to prioritize problem-solving. The results emphasize the importance of maintenance and design optimization to reduce the risk of failures and maximize the utilization of wind energy.

Introduction/purpose: The reliability of wind turbine systems plays a crucial role in ensuring a stable and efficient electricity supply from renewable sources. The failure of any component can lead to system downtime, reduced reliability, and increased operational costs. In this context, it is essential to identify and analyze potential failures in order to improve overall system reliability. The aim of this paper is to analyze the reliability of a wind turbine system using the FMECA method. The focus is on identifying the most critical components and understanding the causes and consequences of their failures, thereby contributing to the improvement of system design, maintenance, and operation.

Methods: This paper applies the FMECA (Failure Modes, Effects, and Criticality Analysis) method, which enables a detailed assessment of potential system failures, their causes and effects, and the identification of the most critical system points based on quantitative parameters. The methodology includes the following steps:

· Identification of key components of the wind turbine, including the rotor, gearbox, generator, control system, and other subsystems.

· Definition of possible failure modes for each component, with corresponding mechanisms that may lead to failure (e.g., wear, overheating, mechanical damage, etc.).

· Evaluation of the consequences of failures, both on the specific component and on the overall operation of the wind turbine.

· Quantitative risk assessment through the assignment of values for:

o the probability of potential failure occurrence (R₁),

o the severity of the potential failure (R₂), and

o the probability of detecting the failure and preventing its manifestation (R₃).

· Calculation of the criticality level (R) using the expression:

· Ranking of components based on R values to identify those that pose the greatest threat to system reliability and require prioritized monitoring or optimization.

Results: The results of the FMECA analysis indicate that the most critical components of the wind turbine system are:

1. Gearbox – the highest criticality level (R value), as gearbox failure can lead to complete system shutdown and costly repairs.

2. Generator – high severity of failure and moderate likelihood of failure detection.

3. Wind turbine control system – although failures are less frequent, the consequences can be severe due to the loss of control over the turbine.

Based on the analysis, components have been classified according to maintenance and monitoring priorities to enable timely detection of potential failures and prevent major breakdowns.

Conclusion: The FMECA method has proven to be an effective tool for identifying and ranking potentially critical components of wind turbine systems. The results indicate that the gearbox, generator, and control system are the most sensitive points in the system. Their preventive maintenance, along with the implementation of condition monitoring systems and design improvements, can significantly enhance reliability and reduce operational costs. This analysis can serve as a foundation for improving maintenance strategies and increasing the operational efficiency of wind farms.

Organic geochemical assessment of black shales: case study of Oued Soura, Tamtret region, Algeria

Abdelghani Kadou — 2026-01-20

Introduction/purpose: Black shales are increasingly recognized as signif- icant unconventional hydrocarbon sources due to their organic richness and potential for oil and gas generation. However, their complex geo- chemical nature, especially in underexplored regions such as Tamtert in southwestern Algeria, poses challenges to accurate evaluation. This study aims to assess the hydrocarbon potential of black shales from the Djebel-Zereg area using advanced organic geochemical methods.

Methods: Five black shale samples were collected from Djebel-Zereg, Tamtert region. Total Organic Carbon (TOC) content was determined, and Rock-Eval 6 pyrolysis and elemental analysis were conducted. Pa- rameters measured included TOC, S1, S2, Tmax, Hydrogen Index (HI), Oxygen Index (OI), and vitrinite reflectance (Ro), providing data on or- ganic matter type, thermal maturity, and hydrocarbon generative capac- ity.

Results: TOC values ranged from 0.51 to 2 wt.% with an average of 1.33 wt.%, indicating acceptable to very good source rock quality. S2 values ranged from 0.45 to 4 mg HC/g rock, and the average Production Index (PI) was 2.23. HI values (51–233 mg HC/g TOC), along with OI and Tmax, indicated the presence of type II and III kerogen, suggesting potential for both oil and gas generation. Tmax values (435–465°C, av- erage 447°C) and vitrinite reflectance (0.68%–1.19%) confirmed thermal maturity. A positive correlation between TOC and S1 values supported the presence of indigenous hydrocarbons.

Conclusion: The integrated geochemical approach confirms that the Djebel-Zereg black shales are thermally mature, organic-rich rocks with promising oil shale potential. These findings support further explo- ration and development of unconventional hydrocarbon resources in the Tamtert region.

A finite element-based optimization of composite wrap repair for welded pipelines with Surface Cracks: influence of geometry, adhesive properties, and internal pressure on mode I fracture behavior

Hachemi Nedir — 2026-01-20

Introduction/purpose: The structural integrity of pressurized pipelines is often threatened by surface cracks, especially in welded regions. This study evaluates the effectiveness of composite wrap reinforcement in repairing longitudinal semi-elliptical cracks in welded steel pipelines subjected to internal pressure. Although environmental effects such as temperature, moisture, and chemical exposure were not modeled, they are acknowledged as key factors influencing the long-term durability of composite repairs.

Methods: A three-dimensional finite element model was developed for a welded pipeline (outer diameter = 1016 mm, thickness = 12.8 mm) containing an external semi-elliptical crack (2c = 10.24 mm, a = 2.56 mm). The Virtual Crack Closure Technique (VCCT) was applied to compute Mode I Stress Intensity Factors (SIFs) under internal pressures of 2–12 MPa. A parametric study assessed the influence of patch length (100–400 mm), thickness (6–12 mm), and circumferential coverage angle (30°–360°), as well as adhesive shear modulus, thickness, and debonding effects.

Results: Increasing patch length, thickness, and coverage angle reduced SIFs, improving crack-tip stress attenuation. A higher adhesive shear modulus enhanced interfacial load transfer, while excessive adhesive thickness impaired efficiency. Localized adhesive debonding significantly increased SIFs under pressure, highlighting the sensitivity of repair performance to bonding quality.

Conclusions: This study provides design insights for optimizing composite reinforcement in welded pipeline repairs. Although a rectangular patch was analyzed, future work should investigate alternative geometries to mitigate edge stress concentrations and incorporate fatigue and environmental effects to better predict long-term service performance.

A new iteration scheme for approximating fixed points of some generalized nonexpansive mappings

Penumarthy Parvateesam Murthy — 2026-01-20

Introduction/purpose: A new three-step iteration process, which converges faster than the Mann iteration and the S-iteration, is introduced, as well as some convergence results for approximation of fixed points of the Suzuki generalized nonexpansive mappings and nearly asymptotically nonexpansive mappings have been established.

Methods: The authors provide a specific three-step iterative method {xn} in a Banach space, defined as a sequence of convex combinations of the current iterate and its images under the mapping T, with control sequences {αn}, {βn}, {γn} ⊆ (0, 1). The results are proved in the setting of uniformly convex Banach spaces, where T is assumed to be either a Suzuki generalized nonexpansive mapping or a nearly asymptotically nonexpansive mapping. The authors obtain both weak and strong convergence theorems by using demiclosedness principles, Suzuki generalized nonexpansive mapping properties, and suitable lemmas on the behavior of the iterates. To compare the rates of convergence, they perform numerical experiments (usually implemented in MATLAB) where the proposed three-step iteration is run in parallel with the Thakur and S-iterations. The iterates are graphed to display the error convergence per iteration.

Results: The new iteration scheme converges faster than the S-iteration scheme if the mapping is a contraction. The new iteration scheme converges to a fixed point of a Suzuki generalized nonexpansive mapping under suitable conditions. The new iteration scheme converges to a fixed point of a nearly asymptotically nonexpansive mapping under suitable conditions.

Conclusions: The three-step iteration algorithm is proved, both theoretically and numerically, to converge faster than the Mann iteration and the S iteration (and sometimes faster than several other existing methods) for the considered types of mappings. The authors prove weak and strong convergence theorems for fixed points of the Suzuki generalized nonexpansive mappings and nearly asymptotically nonexpansive mappings in uniformly convex Banach spaces, thus generalizing, extending, and unifying several existing fixed-point approximation results in the literature.

Cryptography using Laplace transform for the Serbian language

Tatjana Mirković — 2026-01-22

Introduction/purpose: In this paper authors develop a new mathematical method for cryptography. The procedure was performed for messages written in the Serbian language, which consists of 30 phonemes.

Methods: The standard expansion of the inverse trigonometric function in a Taylor series was used. The Laplace transform was applied to encrypt the plaintext, while the corresponding inverse Laplace transform was used for decryption.

Results: A new cryptographic algorithm has been written to encrypt and decrypt a text message written in Serbian letters.

Conclusion: In the paper the authors presented a new algorithm in which the Laplace transform was used for the encryption and description of a message. The message is written in Serbian in Cyrillic letters.

Battlesight zero in context of counter UAV engagement

Ivan Pemčák — 2026-01-22

Introduction/purpose: This paper explores the optimal zeroing distance for an assault rifle on the modern battlefield. Traditionally, armies have used sight settings that align the projectile’s trajectory with the line of sight at distances of 25 m and 300 m. This configuration is well suited for assault rifles chambered in 7 mm to 8 mm calibers when fired from the prone position at an approaching figure target. However, with the increasing use of smaller-caliber ammunition (5 mm to 6 mm) and evolving battlefield threats, including drones, it is necessary to reassess this traditional approach. This study investigates the optimal first zeroing distance when engaging both drone-type targets and standard NATO Type E figure targets. All tests and configurations were conducted using the BREN 2 assault rifle used by the Czech Army.

Methods: This study uses probability-of-hit simulation methods. The parameters of the BREN 2 weapon under investigation were experimentally verified.

Results: The probability of hitting a point target depends significantly on the setting of the sight zeroing distance. The greater the deviation of the projectile trajectory from the line of sight, the lower the probability of hitting the target without distance adjustment.

Conclusion: The findings suggest that for engaging small, irregular targets such as UAVs, zeroing distances between 50 m and 100 m are more effective, without compromising combat effectiveness against standard figure targets.

Call for papers and instructions for authors for the issue 1-2026

Vladan Anicijevic — 2026-03-18

The list of the reviewers of the Military Technical Courier in 20245

Vladan Anicijevic — 2026-03-18

Publication ethics statement for the year 2026

Vladan Anicijevic — 2026-03-18

Back impressum for the issue 1-2026

Vladan Anicijevic — 2026-03-18