Search Results (270)

Background and Clinical Significance: Chronic non-bacterial osteomyelitis (CNO) is a rare autoinflammatory bone disorder that primarily affects children and adolescents, with females more frequently impacted. The condition remains poorly understood, though cytokine dysregulation and inflammasome activation are believed to contribute to its pathogenesis. Clinically, CNO is often difficult to distinguish from infectious osteomyelitis, as presenting symptoms such as bone pain, swelling, and functional limitation are nonspecific, while cultures are frequently negative. As a diagnosis of exclusion, delays in recognition can lead to prolonged or unnecessary antibiotic exposure and uncertainty in management. Case Presentation: A 14-year-old male with a history of left second toe osteomyelitis initially diagnosed in 2021. Despite negative cultures and limited histopathologic findings, he received multiple antibiotic courses with little improvement, and the digit remained chronically swollen. Three years later, a repeat evaluation revealed osseous resorption of the middle and distal phalanges, and a biopsy confirmed acute and mild chronic fibrosing osteomyelitis, consistent with CNO. Given the risk of progression and possible amputation, surgical reconstruction was pursued. The patient underwent autologous calcaneal bone grafting with digital fusion using a K-wire. At three months and one year postoperatively, radiographs demonstrated solid fusion of the digit with maintained activity and resolution of pain. Conclusions: This case emphasizes the diagnostic complexity of CNO and the importance of considering it in children with culture-negative or recurrent osteomyelitis. It further illustrates how timely surgical intervention can preserve function and quality of life while avoiding unnecessary amputation. Full article

The dynamic behavior of relaxed steel wire ropes under slowly varying pulse loads is dominated by the geometric wave impedance effect caused by the helical geometric topology. This study proposes a numerical analysis framework based on high-fidelity parametric solid modeling and implicit dynamics to investigate a Seale-type 6×19S-WSC steel wire rope. Under baseline conditions without pretension and friction, the helical structure forces significant modal conversion and geometric scattering of the axially incident waves, producing an energy attenuation effect akin to “geometric filtering”. Parametric analysis varying the core wire diameter reveals that the helical structure causes the axial wave speed to decrease by orders of magnitude compared to the material’s inherent wave speed. Furthermore, changes in core wire size induce a non-monotonic variation in the dynamic response, revealing a competitive mechanism between overall stiffness increase and a “dynamic decoupling” effect caused by interlayer gaps. This study confirms the dominant role of geometric wave impedance in the dynamic performance of relaxed steel wire ropes. Full article

Additive manufacturing (AM) of aluminium by solid-state routes offers a promising pathway to overcome the limitations of fusion-based processes, such as porosity and hot cracking. This study investigates the potential of wire-based friction stir additive manufacturing (W-FSAM) as an innovative solid-state process. A test specimen made of EN AW-1050 was fabricated and characterised using mechanical testing as well as optical and electron microscopy. Microstructural characterisation revealed a fully consolidated, pore-free build with fine equiaxed grains and partial dynamic recrystallisation (DRX). The average grain size decreased from 13.4 µm near the substrate to 9.7 µm at the top, reflecting the variation in cumulative thermal exposure along the build height. A homogeneous hardness distribution (21.2 HV) and smooth interlayer interfaces were observed. Tensile tests in the travel direction yielded an ultimate tensile strength of approximately 85 MPa and an elongation exceeding 60%, while high-cycle fatigue tests demonstrated a fatigue strength of about 30 MPa at $2\times {10}^6$ cycles ($R=0.1$) with ductile fracture features. The results confirm that W-FSAM enables the production of fine-grained, defect-free CP-Al structures whose mechanical properties, in terms of strength and ductility, exceed those of the reference material. Thus, W-FSAM represents a promising solid-state additive manufacturing route for the production of high-performance CP-Al components. Full article

The adjustable-ring-mode (ARM) scanning laser was used to perform butt welding on 0.5 mm thick TA1 titanium alloy and 304 stainless steel (SS304) thin sheets, with 1.2 mm diameter AZ61S magnesium alloy welding wire as the filling material. Microhardness test results show that the hardness distribution presented a trend of being higher in the base metals on both sides and lower in the middle filling area, with no hardening observed in the weld zone. For all specimens subjected to horizontal and axial weld bending tests, the bending angle reached 108° without any cracks occurring. When the ring power was in the range of 800–1000 W, or the scanning frequency was between 100 and 200 Hz, all the average tensile strengths of the welded joints were more than 80% of that of the AZ61S filling material (approximately 240 MPa); the maximum average tensile strength stood at 281.2 MPa, which is equivalent to 93.7% of the AZ61S. As the ring power or scanning frequency increased further, the tensile strengths of the joints showed a decreasing trend. The remelting effect of the trailing edge of the ARM laser under high energy conditions, or the scouring of the turbulent molten flow induced by the scanning beam, damages the weak links at the newly formed solid–liquid interface and increases the Fe concentration in the molten pool. This leads to a thicker FeAl interface layer during growth, thereby resulting in a decline in the mechanical properties of the welded joints. Full article

Steel wire rods are essential for manufacturing high-strength steel tire cords. Yet, the presence of residual copper (Cu) in recycled steel can cause grain-boundary sensitization, embrittlement, and deterioration of the mechanical performance of the final product. This study introduces a desensitization heat treatment step designed to redistribute Cu away from austenite grain boundaries after sensitization occurs. The treatment consists of a 10 min dwell at 1000 °C in a 5%H₂-Ar reducing atmosphere followed by quench. The temperature and hold time were selected based on diffusion calculations to promote solid-state back diffusion of Cu without altering grain morphology. Experimental validation showed that the dwell step reduced the length of Cu-rich sensitized zones of steel wire rod samples containing 0.21 wt.% Cu by approximately 89% and restored the mechanical properties to nearly 95–98% relative to low-Cu baseline steel (0.01 wt.% Cu). Compared with sensitized and as-obtained samples, these results highlight the effectiveness of the proposed method in improving both the microstructure and tensile performance of recycled steel wire rods, enabling their potential application in tire manufacturing. Full article

A thin-walled product made of AZ31 magnesium alloy was successfully fabricated using wire-feed electron-beam additive manufacturing. The microstructure of the initial wire, used as a precursor, comprises a α-Mg(Al, Zn) solid solution and a minor amount of the Al₈Mn₅ intermetallic phase. The microstructure of the as-printed AZ31 alloy exhibits a three-phase structure: α-Mg(Al, Zn), Al₈Mn₅, and β-Mg₁₇Al₁₂. It was proposed that the secondary β-phase was formed via a primary solidification process upon the cooling of the welded layers. The texture effect was evident in the <01$\overline{1}$2> direction, corresponding to the printing direction, while other crystallographic orientations demonstrated near-equal pole densities as the XRD lines. The yield strength for the as-printed alloy was found to be 86 MPa; the tensile strength reached 240 MPa; and the relative elongation was 21.5%. For the first time, the corrosion resistance of an EBAM-fabricated AZ31 alloy was studied. It was revealed that the corrosion current density in the referenced as-cast and as-printed alloys was below 2·10⁻⁴ A/cm². Full article

The failure behavior of steel wire ropes under heavy load conditions is a complex system involving the interaction of mechanical damage, lubrication status, and detection technology. Despite numerous studies, the existing literature seriously lacks a systematic framework to correlate the structural integrity and deformation behavior of gel-like grease and its central role in suppressing the critical failure modes (wear, fatigue, corrosion) of steel wire ropes. This review aims to fill this critical knowledge gap. By critically synthesizing existing studies, this paper explains for the first time how the microstructural evolution and rheological behavior of gel-like grease can ultimately determine the macroscopic failure process and life of steel wire ropes by influencing the interfacial tribological processes. We further demonstrate, based on the understanding of the above mechanism, how to optimize the detection strategy and design high-performance gel-like greases for specific working conditions. Ultimately, this work not only provides a unified perspective for understanding the system reliability of steel wire ropes but also lays a solid theoretical foundation for the future development of intelligent mechanism-based lubrication and predictive maintenance technologies. Full article

Aluminum powder is the most commonly used metal fuel in the industry of explosives and propellants. The research progress in preparation technology, reactivity and application of nano-aluminum in explosives and propellants is systematically reviewed in this paper. The preparation technology of nano-aluminum powder includes mechanical pulverization technology (such as the ball milling method and ultrasonic ablation method, etc.), evaporation condensation technology (such as the laser induction composite heating method, high-frequency induction method, arc method, pulsed laser ablation method, resistance heating condensation method, gas-phase pyrolysis method, wire explosion pulverization method, etc.), chemical reduction technology (such as the solid-phase reduction method, solution reduction method, etc.) and the ionic liquid electrodeposition method, each of which has its own advantages. Some new preparation methods have emerged, providing important reference value for the large-scale production of high-purity, high-quality nano-aluminum powder. The reactivity differences between nano-aluminum powder and micro-aluminum powder are compared in the thesis. It is clear that the reactivity of nano-aluminum powder is much higher than that of micro-aluminum powder in terms of ignition performance, combustion performance and reaction completeness, and it has a stronger influence on the detonation performance of mixed explosives and the combustion performance of propellants. Nano-aluminum powder is highly prone to oxidation, which seriously affects its application efficiency. In addition, when aluminum powder oxidizes or burns, a surface oxide layer will be formed, which hinders the continued reaction of internal aluminum powder. In addition, nano-aluminum powder may deteriorate the preparation process of explosives or propellants. To improve these shortcomings, appropriate coating or modification treatment is required. The application of nano-aluminum powder in mixed explosives can improve many properties of mixed explosives, such as detonation velocity, detonation heat, peak value of shock wave overpressure, etc. Applying nano-aluminum powder to propellants can significantly increase the burning rate and improve the properties of combustion products. It is pointed out that the high reactivity of nano-aluminum powder makes the preparation and storage of high-purity nano-aluminum powder extremely difficult. It is recommended to increase research on the preparation and storage technology of high-purity nano-aluminum powder. Full article

To promote the high-value recycling of machining return materials from powder metallurgy (P/M) FGH95 superalloy production, a vacuum induction melting refining process was developed to achieve gas impurity purification and compositional control. Cylindrical solid returns obtained from wire-cut electrical discharge machining were used as feedstock, and the effects of refining temperature (1550–1650 °C) and holding time (10–30 min) on impurity removal and element stability were systematically investigated. For each condition, three repeated melts were performed, and the average gas contents (mean ± SD) were evaluated by inert-gas fusion analysis. Results show that at 1650 °C, O decreased from 8 ppm to 6 ppm, N decreased from 6 ppm to 3 ppm, while H remained below the detection limit (<1 ppm). Prolonged refining caused slight compositional deviations, with Cr exhibiting measurable volatilization, whereas Al and Ti showed minor increases (<0.06 wt.%). A kinetic model describing O removal was established, yielding an apparent activation energy of 128 kJ·mol⁻¹, confirming diffusion-controlled deoxidation behavior. The optimal refining condition—1650 °C for 10 min—achieved efficient removal of O and H while maintaining alloy compositional stability. This study provides both a practical refining route and a kinetic basis for the purification and reuse of machining returns in nickel-based P/M superalloys, contributing to cost reduction and sustainable manufacturing. Full article

This study focuses on the design and implementation of an Adaptive High-Order sliding mode control for by-wire ground vehicle systems. The controller integrates advanced technologies such as Active Front Steering (AFS) and Rear Torque Vectoring (RTV), aimed at enhancing vehicle dynamics. However, lateral velocity remains one of the most challenging variables to measure, even in modern vehicles. To address this limitation, a High-Order Sliding Mode (HOSM)-based observer with adaptive gains is proposed. The HOSM observer provides critical information for the operation of the dynamic controller, ensuring the tracking of desired references. Compared with traditional observers, the proposed adaptive HOSM observer achieves finite-time convergence of state estimation errors and exhibits enhanced robustness against external disturbances, as confirmed through simulation results. The adaptive gains dynamically adjust the system parameters, enhancing its precision and flexibility under changing environmental conditions. This dynamic approach ensures efficient and reliable performance, enabling the system to respond effectively to complex scenarios. The stability of the dynamic HOSM controller with adaptive gain is analyzed through a Lyapunov-based approach, providing solid theoretical guarantees. Its performance is evaluated using detailed simulations conducted in CarSim 2017 software. The simulation results demonstrate that the proposed controller is highly effective in ensuring accurate trajectory tracking. Full article

Electric arc spraying is a promising technique for enhancing the wear resistance of components operating under abrasive and mechanical loads, particularly in agricultural soil-processing machinery. This study aims to comparatively analyze the properties of coatings formed using electric arc metallization with cored and solid wires of 30KhGSA and 51KhFA steel grades. Experimental investigations were carried out to evaluate the influence of wire type on the microstructure, microhardness, adhesion strength, and wear resistance of the sprayed coatings. Metallographic analysis and microhardness measurements revealed that coatings produced with cored wire exhibited a finer lamellar structure and higher hardness values compared to those formed with solid wire. Wear tests demonstrated improved resistance under abrasive conditions for cored wire coatings, indicating better performance under operational loads. The optimized spraying parameters were determined to ensure uniform and adherent coatings. The results suggest that using cored wire in electric arc spraying offers significant advantages in forming high-quality protective layers. These findings support the potential application of the developed coatings in extending the service life of soil-engaging machine parts under intensive field conditions. Full article

Additive manufacturing of metal components is predominantly based on fusion-welding processes involving melting and solidification. However, processing high-strength aluminium alloys presents challenges, including reduced mechanical properties and increased susceptibility to hot cracking. To address these issues, alternative solid-state processing methods for aluminium are being explored worldwide. One such method is wire-based friction-stir additive manufacturing, which builds on the principles of friction-stir welding. This study focused on assessing a range of pin tool designs to promote improved mixing between the filler material and substrate. The best results were achieved using a two-stirring-probe configuration, which was then employed to fabricate a multilayer wall made of EN AW-6063 aluminium alloy. The resulting structure showed significant grain refinement, with the deposited layers having an average grain size approximately four times smaller than that of the substrate, indicating dynamic recrystallisation. Tensile testing of the intermediate layer revealed a strength of 147 MPa and 10% elongation, corresponding to 77% of the filler wire strength. These findings highlight the potential of the W-FSAM process for producing near-net-shape, high-quality lightweight metal components with refined microstructures and reliable mechanical performance. Full article

The development of dynamic missions of small satellites requires the development of efficient, compact, and reliable propulsion systems (PSs). This paper investigates a propellant storage and supply system (PSSS), utilizing alternative solid-state propellants in the form of wire. To establish the background to the suggested solutions implemented in the proposed system, two types of comparative analysis were performed. The first one compared different types of propellant management system designs while the second juxtaposes a variety of propellants. It is shown that the solid-state systems for small satellite operations are advantageous, while the selection of propellants should be focused on safe operations and operational requirements. The principle of operation and structural design of the proposed wire-based solid-state propellant management system are discussed, including the assessment of its engineering realization. The strategies to mitigate the potential problems with the system’s operations such as propellant unwanted deposition and corrosive effects are suggested. An example of using the proposed system is provided, which considers a deep space dynamic mission case. The proposed PSSS architecture is dedicated to increasing the energy efficiency, resilience to environmental factors, and suitability for small satellite platforms, including that of the CubeSat format. Full article

Silicon carbide (SiC) ceramics have gained significant attention in advanced engineering applications because of their superior mechanical properties, resistance to wear and corrosion, and thermal stability. However, the precision machining of these materials is extremely challenging because of their intrinsic hardness and brittleness. Wire Electrical Discharge Machining (WEDM) has become increasingly popular as a viable technique for processing SiC ceramics because of its ability to produce intricate geometries and high-quality surface finishes. In this review paper, a comprehensive overview of WEDM technology applied to SiC ceramics is presented, emphasizing the influence of process parameters, wire materials, and dielectric fluids on cutting efficiency and quality. This research explores recent experimental findings related to Wire Electrical Discharge Machining (WEDM) and highlights the challenges in reducing material damage. It also presents strategies to improve machining performance. Additionally, potential future directions are discussed, providing a roadmap for further research and the application of WEDM in processing silicon carbide (SiC) and its variants, including solid silicon carbide (SSiC) and silicon-infiltrated silicon carbide (SiSiC). Full article

Several decades after the development of FEM in computer-based form, which is a milestone in the evaluation of mechanical systems, the method has been adopted to analyze the biomechanical response of human skeletal structures. This innovative technique has generated new questions, but also new results, and, at the same time, competitive environments with explosive development, in the recent period. This research is focused on analyzing, using FEM, the extreme thermal variations produced at the level of two oro-facial systems (one control and one subjected to orthodontic therapy using a fixed metallic orthodontic appliance). The objective of the study was to determine the temperature evolution in different dental structures subjected to extreme temperatures given by variations between very cold and very hot foods. Each system was exposed to a succession of extreme thermal regimes (70…−18…70… °C and −18…70…−18… °C). In order to conduct this research, we used the case of a 14-year-old female patient. Following an orthodontic evaluation, we discovered that the patient had dento-alveolar disharmony with crowding. The straight-wire method of applying a fixed metallic orthodontic appliance was chosen. As complementary examinations, the patient was subjected to a bimaxillary CBCT. Using a series of programs (InVesalius, Geomagic, SolidWorks, and AnsysWorkbench), a three-dimensional model was obtained. This model contained jaws and teeth. Also, brackets, tubes, and orthodontic wires can be incorporated into the model. Following the simulations carried out in this study, it was found that thermal variations from the dental pulp are more severe for the oro-facial system with a fixed metallic orthodontic appliance (regardless of the type of thermal stimulus used). Thus, even today, with all the facilities available in the dental materials industry, metallic orthodontic devices present significant thermal conductivity, generating harmful effects on the dental structures. The reading of the results was performed on the virtual model, more precisely, on the internal dental structures (enamel, dentin, and pulp). A statistical study was not performed because it was considered that, in other patients, the results would be similar. Full article