The Annals of “Dunarea de Jos” University of Galati. Fascicle IX, Metallurgy and Materials Science

Deep Learning-Based Camouflage Detection for Anti-Personnel Mine Identification in Natural Environments

Florin-Bogdan MARIN — 2026-06-15

The detection of anti-personnel mines in natural environments remains a critical humanitarian and technological challenge due to the high visual similarity between explosive devices and their surrounding backgrounds. This study presents a deep learning-based camouflage detection framework for the identification and segmentation of PFM-1 anti-personnel mine surrogates embedded in visually homogeneous outdoor scenes. The proposed approach employs a Deep Camouflage Detection Network (DCDN) designed to extract multi-scale contextual features and enhance boundary sensitivity under low-contrast conditions. A dedicated dataset was constructed using 3D-printed PFM-1 surrogates positioned in vegetated environments under varying illumination conditions, viewing angles, occlusion levels, and object scales. The network architecture integrates a pretrained convolutional backbone, multi-scale feature aggregation modules, and a composite loss function (consisting of Binary Cross-Entropy and Dice loss) to address class imbalance and weak edge contrast.
Experimental evaluation on an independent test set demonstrates robust segmentation performance, achieving a mean Intersection over Union (IoU) of 91.8% and a Dice coefficient of 95.7%. Precision and recall values of 96.3% and 94.9%, respectively, confirm a balanced detection capability with limited false positives. Stratified analysis indicates stable performance under illumination variability and partial occlusion, while ablation studies highlight the importance of multi-scale aggregation and region-aware loss optimization. The results confirm that deep camouflage-aware segmentation architectures provide reliable detection of low-contrast objects in complex natural environments.

Fracture Behavior of Dissimilar Resistance Spot Welded Overlap Joint

Abdelkader BENYOUCEF — 2026-06-15

The resistance spot welding process is also used for the welding of dissimilar materials. A dissimilar join is formed by two sheets: a 1.0 mm thick sheet of lowalloy carbon steel and a 1.5 mm thick sheet of aluminium alloy 6061 T6. In this study, the effects of welding current and nugget diameter are investigated. Welding times and welding force are kept constant. Tensile shear tests were applied in order to determine the strength parameters of the dissimilar joint. The experimental results show that an increase in the welding current increases the tensile shear stress and the weld nugget diameter. This study used a fracture mechanics-based approach, to investigate the influence of resistance spot welding parameters on the critical stress intensity factor. The results show that the critical stress intensity factor is maximal for a welding current equal to 16 kA. Also, the maximum tensile shear strength is achieved at an 8 mm nugget diameter, which is influenced by an increase in the welding current.

Simulation of the Mechanical Stress Behavior in the Case of the Damascus Steel After Heat Treatments for Improvement

Carmen-Penelopi PAPADATU — 2026-06-15

The paper aims to study the behavior of Damascus steel at a maximum admissible load with a force of 250 N. Previous studies considered lower loading force values that did not produce cracks in the material. The processing of the samples and laboratory tests were carried out on specimens of Damascus steel obtained in the laboratory. The applied treatments were hardening and tempering to improve the material’s properties. The processing of the results and the simulations were carried out using Autodesk Inventor Professional 2023.

Assessment of Pollutant Load and Potential Impact of the Snowpack in Brăila Municipality

Nicoleta CIOBOTARU — 2026-06-15

Urban snowpack represents a highly effective matrix for monitoring atmospheric deposition, as it has the capacity to accumulate pollutants originating from anthropogenic activities during the cold season. The present study aims to assess the contamination levels of snow collected from different functional areas of the Brăila municipality, as well as to estimate the potential impact of pollutants on soil and surface waters during the melting period. Snow samples were collected from areas characterized by intense road traffic, residential zones, industrial sectors, and green spaces, in order to highlight the spatial variability of contaminants. Laboratory analyses included the determination of physicochemical parameters (pH, total dissolved solids, and electrical conductivity), major ionic species (Cl⁻, SO₄²⁻, NO₃⁻, NH₄⁺, Ca²⁺, Mg²⁺), and selected heavy metals (Pb, Cd, Fe), which are relevant indicators for identifying sources of urban pollution. The assessment of pollution levels was carried out using specific indices, such as the contamination factor and the pollution load index. The obtained results highlight the influence of anthropogenic activities on the chemical composition of urban snow and emphasize its role as a vector for pollutant transfer to soils and drainage systems during snowmelt. Ultimately, this study contributes to a better understanding of seasonal urban pollution processes and provides a scientific basis for the development of sustainable environmental management measures.

Failure Case Study Series Part Two: Failure Analysis of Roller Guides in a Wire Rod Rolling Mill

Liviu GURĂU — 2026-06-15

The paper aims to present the root cause of failure of roller guides from the wire rod and coil rolling mill during normal operation. A comprehensive failure investigation was conducted following standard metallurgical procedures, including visual inspection, hardness testing, chemical analysis, optical microscopy, stereomicroscopy, scanning electron microscopy (SEM–EDS) characterization, and inclusion rating according to ASTM E45. The investigation concludes that the primary root cause of failure was the use of D3 tool steel, which is unsuitable for components subjected to severe thermal cycling, resulting in progressive thermal fatigue damage and eventual catastrophic fracture. Moreover, the election of D2 or other Mo-V alloyed hot‑work tool steels, combined with appropriate surface hardening, is recommended to enhance service life under rolling mill operating conditions.

Failure Case Study Series Part Three: Investigation of Wear and Failure Mechanisms in Heavy-Duty Gear Coupling

Liviu GURĂU — 2026-06-15

This paper investigates the failure mechanisms of the gear teeth in a heavyduty coupling, emphasizing the combined effects of mechanical loading, metallurgical microstructure, and tribological wear mechanisms.
Detailed characterization using optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and both chemical and mechanical testing identified pronounced wear and progressive degradation of the coupling sleeve, largely driven by operational misalignments and external contamination, such as mill cobbles. The analysis underscores the critical importance of precise material compatibility, a controlled hardness differential, and manufacturing accuracy in mitigating localized stress concentrations and wear. The findings highlight that abnormal wear progression results from a complex interaction among load redistribution owing to misalignment, tribological deterioration, manufacturing tolerances, and dynamic rotor–coupling interactions. Recommendations focus on optimizing design parameters, manufacturing processes, and operational routines to enhance the reliability, durability, and safety of high-torque coupling systems in harsh industrial environments.

Failure Case Study Series Part Four: Investigation of the Failure Mechanism of the Connecting Rod in an Industrial Oxygen Compressor

Liviu GURĂU — 2026-06-15

This investigation addresses the catastrophic fracture of a connecting rod in an oxygen compressor unit during steady‑state operation. Owing to its function in transmitting cyclic compressive and tensile loads between the crankshaft and the piston, the connecting rod it’s a critical structural element.
The assessment employed a systematic multi‑technique protocol. Macroscopic fractography was used to document crack morphology, fracture‑surface topography, and subsidiary failure‑related surface markers. Representative specimens were preserved for laboratory evaluation. Material conformance was verified through chemical composition analysis and hardness measurements benchmarked against applicable standards. The internal structure, including phase distribution, cleanliness, inclusion content, and thermal‑processing quality, was examined using optical metallography (OM). High‑resolution scanning electron microscopy (SEM) combined with energy‑dispersive spectroscopy (EDS) enabled the identification of crack‑initiation sites, fracture mechanisms, and local compositional anomalies.

Functionalized Plasmonic Nanoparticles: Synthesis, Surface Engineering and Emerging Biomedical Applications

Mariana BUȘILĂ — 2026-06-15

Functionalized plasmonic nanoparticles have attracted significant attention in biomedical research due to their unique optical properties, high surface reactivity, and versatile surface chemistry. In this study, gold nanoparticles (AuNPs) were synthesized via the Turkevich citrate reduction method and subsequently functionalized using (3-glycidyloxypropyl) trimethoxysilane (GPTMS) to enhance their stability and surface reactivity. The synthesized and functionalized nanoparticles were comprehensively characterized using multiple analytical techniques. Morphological features and particle size distribution were investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), while elemental composition was confirmed by energy-dispersive X-ray spectroscopy (EDS). The crystalline structure was analysed using X-ray diffraction (XRD), and the average crystallite size was estimated using the Scherrer equation. Fourier-transform infrared spectroscopy (FTIR) was employed to identify surface functional groups and confirm successful GPTMS functionalization. Additionally, UV–Vis spectrophotometry was used to evaluate the optical properties of the nanoparticles and to assess their localized surface plasmon resonance (LSPR) behavior. The results demonstrate that the functionalized AuNPs exhibit stable colloidal properties, controlled morphology, and modified optical responses due to surface engineering. The presence of additional absorption features in the UV region highlights the influence of GPTMS on the interfacial environment of the nanoparticles. The obtained results underscore the potential of GPTMSfunctionalized gold nanoparticles for applications in nanomedicine, including biosensing, drug delivery, and optical bioimaging.