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Experimental Evaluation of the Damping Factor in Laminated Composite Materials
No full textThe use of natural fibers in composite materials is gaining significant interest in the current context of emission reduction. In this regard, along with the fact that it is an eco-responsible material, it becomes a very attractive option, although its clear inferiority in mechanical properties such as stiffness and strength compared to glass fiber, and certainly carbon fiber, raises doubts about its use in structural applications. However, flax fiber's ability to absorb and damp vibrations is much greater than that of the aforementioned high-performance structural fibers. The experimental determination of the damping coefficient emerges as a key aspect that may allow for the consideration of natural fibers in structural applications requiring damping. Existing standards are very generic and do not account for some important details in the execution of the test. The present work presents the experimental method used for determining the damping coefficient of laminated composite materials using accelerometers and a vibration exciter (shaker), including consideration of the analysis of the effect of certain parameters such as the positioning of accelerometers, excitation methods, and data reduction methods
Solving the Sine-Gordon Equation: A Novel Numerical Approach Using Cubic B-Splines and the Method of Lines
No full textThis work explores a numerical approach to solving the sine-Gordon equation using the method of lines combined with cubic B-spline interpolation. The sine-Gordon equation, a nonlinear partial differential equation, arises in various fields of physics and engineering, describing phenomena such as solitons in non-linear optics and magnetic flux lines in superconductors. In our approach the method of lines is used to discretize the spatial derivatives, thereby converting the partial differential equation into a system of ordinary differential equations. These ordinary differential equations are then solved numerically using standard techniques, specifically the Runge-Kutta method of order 4. Cubic B-spline interpolation is employed to approximate the spatial derivative, ensuring efficient and precise computation of the solution. A comprehensive stability analysis reveals that our scheme requires the time step conditiont1.53 h for numerical stability. Theoretical convergence analysis demonstrates that the method achieves O(h2)spatial convergence and O( t4)temporal convergence, resulting in an overall error bound of O(h2+ t4 ). These theoretical predictions are strongly supported by numerical experiments, where empirical convergence rates closely match the theoretical values. To validate the numerical scheme, the results are compared with existing solutions. Our findings demonstrate the accuracy and computational efficiency of the proposed method, highlighting its potential as a valuable tool for studying the dynamics and behavior of systems governed by the sine-Gordon equation.OPEN ACCESS Received: 29/08/2025 Accepted: 05/11/2025 Published: 23/01/202
Research on Correction Method for Pipe-Soil p-y Curves in Submarine Silty Clay-Sand Gas Hydrate Formations
No full textThe development of marine natural gas hydrates faces complex geomechanical challenges. Argillaceous silty hydrate reservoirs, due to their weak cementation and low permeability, have significantly different mechanical properties from those of general reservoirs. Based on the self-developed triaxial seepage experimental platform for hydrates, this paper systematically carried out triaxial compression experiments of argillaceous silt hydrate sediments, focusing on simulating the insitu temperature and pressure conditions of the formation, analyzing the influences of saturation, temperature and confining pressure on mechanical properties, and comparing them with the experimental results of sandy hydrate sediments. The experimental results show that due to the weak cementation effect of kaolin and methane hydrate, the failure mode of argillaceous silt hydrate is manifested as compression and dispersion, while sandy hydrate presents the traditional core compression failure characteristics. The peak strength of the stress-strain curve of argillaceous silt hydrate is lower than that of sandy hydrate, and the strain softening characteristic is more significant. The experimental results were calculated through MATLAB programming, and it was obtained that the cohesion and internal friction Angle of the argillaceous silt hydrate increased with saturation higher than those of the sandy hydrate. The pipe-soil coupling numerical simulation based on ABAQUS reveals that the initial stiffness and plastic deformation response of the p-y curve in the argillaceous silty hydrate formation are essentially different from those in the traditional API sandy soil model. By comparing the numerical simulation results of sandy properties and argillaceous silty hydrate, a two-parameter correction model for argillaceous silty strata was proposed. The cementation factor related to mass abundance and the displacement correction term were introduced. The error analysis indicated that the correction method was significantly superior to the API specification. Studies show that the mechanical properties of hydrates need to be evaluated independently, and the correction method provides a theoretical basis for the safety design of deep water well engineering
Reconfigurable Solar-Powered Multiple Input Multiple Output Terahertz Antenna System
No full textThe rapid evolution of terahertz (THz) technology has opened new frontiers in high-speed wireless communication, imaging, and sensing. However, the practical deployment of THz systems, particularly in remote or space-constrained environments, is often limited by power constraints and rigid antenna structures. A reconfigurable THz antenna system that is powered by solar energy is suggested. By leveraging real-time energy harvesting, the antenna system maintains operation without external power sources, making it ideal for deployment in remote IoT nodes, CubeSats, or energy-constrained sensor networks. Material used in antenna design is lead glass while gold is used as a radiator, the MIMO antenna loaded with graphene with chemical potential of graphene= 0 works from 2.4–2.5 THz, 3.87–3.98 THz, and 5.17–5.3 THz. The MIMO antenna with graphene chemical potential= 1 eV works from 2.54–2.63 THz, 3.96–4.1 THz, and 5.27–5.45 THz. The MIMO antenna with graphene chemical potential= 2 eV works from 2.6–2.68 THz, 4–4.2 THz, and 5.3–5.55 THz. Gain of antenna at 2.45, 3.95, and 5.3 THz maximum gain obtained at these frequencies is 6, 5 and 7 dBi, respectively. By integrating real-time solar energy harvesting with a tunable THz antenna structure, the design enables self-sustained, high-efficiency operation for remote IoT nodes, CubeSats, and energy-constrained sensor networks, merging green energy and next-generation THz communication in a compact platform. Advantages of the proposed design are self-powered operation, reconfigurable multi-band tuning, high gain, and suitability for diverse THz applications.OPEN ACCESS Received: 23/06/2025 Accepted: 17/09/2025 Published: 23/01/202
From Computed Tomography to Finite Element Analysis: Mapping Porosity in Metal Additive Manufacturing
No full textA Thermal-History-Informed Inherent Strain Framework for Efficient Distortion Prediction in PBF-LB
No full textAdvanced Computational Study of Nonlinear Time-Fractional Newell-Whitehead-Segel Equation with Caputo-Fabrizio Derivative Using B-Spline Techniques
No full textThis study presents numerical solutions for the time-fractional NewellWhitehead-Segel (NWS) equation with a Caputo-Fabrizio derivative. Spatial derivatives are discretized using three B-splines-cubic, cubic trigonometric and extended cubic B-splines-while temporal discretization is handled by a finite difference scheme. The proposed schemes are rigorously analyzed for stability and convergence. Their performance is evaluated in terms of accuracy and computational efficiency. Numerical experiments confirm the effectiveness of these techniques in capturing the dynamics of the fractional NWS equation. Each B-spline variant demonstrates unique strengths, highlighting the flexibility of B-spline approaches for solving fractional differential equations with nonlocal, memory-dependent operators. These results affirm the reliability and robustness of B-spline-based methods for such problems, paving the way for future advancements in this area.OPEN ACCESS Received: 23/08/2025 Accepted: 08/12/202
A Hybrid Approach for Vulkan-Based Ray Tracing Implementations
No full textThree-dimensional (3D) graphics output started with traditional local shading models processed in real time. Ray-tracing techniques are actively introduced for high-quality output. These traditional local shading pipelines and ray tracing pipelines are typically provided independently. Recently, hybrid rendering methods were introduced to integrate the results of these pipelines for better real-time graphics results. However, technical problems arise with heterogeneous application programming interfaces (APIs). Vulkan was recently introduced as a new low-level graphics API in practical 3D graphics implementations. With its new ray tracing extensions, Vulkan has become one of the 3D graphics environments that simultaneously supports traditional local shading and modern ray tracing pipelines. Stand-alone ray tracing and hybrid rendering techniques are implemented to determine a practical implementation of the ray tracing technique in this latest Vulkan environment. This work reveals the completeness of both implementations and compares the graphics performance with experimental computer animation sequences and different camera configurations. The hybrid rendering techniques perform better with previous graphics processing unit models, and the core ray tracing implementation achieves faster processing speeds of 39% to 64% compared to the stand-alone ray tracing method, at least in the Vulkan environment with the latest NVIDIA graphics card. In contrast, the preprocessing of the geometry pass takes noticeable time, which reduces our overall performance improvements. The experimental results can be applied as guidelines for implementing practical real-time 3D graphics applications and as a new benchmark model for ray tracing implementations.OPEN ACCESS Received: 23/08/2025 Accepted: 28/11/2025 Published: 03/02/202