Scipedia: Documents published in 2026

Investigation of Compensated Foundation SettlementMechanism Based on FEM-DEM Coupling Method

Jesús Sánchez Pinedo — Tue, 27 Jan 2026 10:15:23 +0100

The application of compensated foundations is common in engineering, but significant settlements often occur during the application process. A foundation pit model supported by a rigid retaining wall was established based on the Finite Element Method-Discrete Element Method (FEMDEM), and a cantilevered layer-by-layer excavation process was simulated. A rolling resistance linear model was used to simulate the sand, while a variable particle size method was adopted to establish the foundation model. It is shown that during the excavation process of the foundation pit, the stress of the sand at the pit bottom gradually decreases, and the displacement of the soil changes gradually fromsettlement to uplift as one moves frombehind the retaining wall to the bottomof the foundation pit. Moreover, theporosityof the sandat thepit bottomgradually increases.As a result, the strength of the uplifted sand at the pit bottomdecreases due to over-excavation during the foundation pit excavation stage. The uplifted sand is finally excavated during the site leveling stage, resulting in a further decrease in the strength of the sand at the pit bottom. Finally, an inverted arch bottom plate structure is proposed to mitigate the over-excavation settlement of the compensated foundation.

A New Scalable Hybrid Model Approach of High-Dimensional Time Series Forecasting Applications

Jesús Sánchez Pinedo — Tue, 27 Jan 2026 10:13:35 +0100

This study introduces a Lasso–Prophet hybrid framework developed to deal with the limitations and gap of Facebook’s Prophet model. The approach begins with Prophet’s decomposition of a time series into its fundamental components trend, seasonality, and holiday effects, and then applies Lasso regression to the residuals to capture additional structural patterns that fail to capture by the base model. This layered methodology boosts predictive accuracy by enabling the model to learn both systematic and irregular variations within temporal data by incorporating Lasso’s feature selection capability, the framework efficiently handles highdimensional datasets, retaining only the most informative predictors. The outcome is a hybrid model which achieves an optimal balance among interpretability, scalability, sparsity, and forecasting precision. Validation on simulated high-feature datasets and real-world electricity consumption data demonstrates that the Lasso–Prophet hybrid consistently outperforms the Prophet and other baseline models.OPEN ACCESS Received: 31/08/2025 Accepted: 17/11/2025 Published: 23/01/2026

Qualitative Analysis of Nonlinear Systems Involving Hadamard-Type Fractional Derivatives with Nonlocal Boundary Conditions and Stability Properties

Jesús Sánchez Pinedo — Tue, 27 Jan 2026 10:12:24 +0100

This paper establishes a comprehensive analysis of a coupled system of nonlinear Hadamard-type fractional differential equations subject to generalized nonlocal integral boundary conditions. The distinct logarithmic kernel of the Hadamard derivative makes this framework particularly suitable for modeling scale-invariant processes and ultraslow diffusion phenomena. The existence and uniqueness of solutions are rigorously investigated using fixed point theory: Banach’s contraction principle ensures uniqueness, while the Leray-Schauder nonlinear alternative guarantees existence under more general growth conditions. Furthermore, the system is proven to be Ulam-Hyers stable, ensuring that approximate solutions remain close to exact solutions, which is crucial for the robustness of the model in practical applications. The theoretical findings are effectively validated through two detailed numerical examples, demonstrating the applicability of the established results to different classes of nonlinearities.OPEN ACCESS Received: 22/08/2025 Accepted: 03/11/2025 Published: 23/01/2026

Solving the Sine-Gordon Equation: A Novel Numerical Approach Using Cubic B-Splines and the Method of Lines

Jesús Sánchez Pinedo — Tue, 27 Jan 2026 10:12:11 +0100

This 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: 23/01/2026

Combining Copula Theory and Machine Learning for Prediction of Ground Vibrations Induced by Tunnel Blasting

Jesús Sánchez Pinedo — Tue, 27 Jan 2026 10:10:47 +0100

To effectively predict and control the peak particle velocity (PPV) induced by tunnel blasting, this study investigates the Qinhuangdao Jiaoshan Tunnel as a case study. This study first proposes an Improved Particle Swarm Optimization (IPSO) algorithm through theoretical derivation. Building upon IPSO, a further enhanced algorithm, termed CIPSO, is developed by integrating a dependency model derived from Copula theory. The CIPSO algorithm is then employed to optimize a Support Vector Regression (SVR) model, establishing the final CIPSO-SVR prediction framework. Copula theory was employed to quantify the correlation between PPV and surface cumulative settlement (S). A regularization term incorporating Kullback-Leibler (KL) divergence was then embedded into the SVR objective function. The Hyperparameters of the CIPSO-SVR model were optimized using fixed-step rolling cross-validation. The model’s predictive performance was rigorously compared against CIPSO-optimized Convolutional Neural Network (CNN) and Long Short-Term Memory (LSTM) models, as well as against SVR, CNN, and LSTM models optimized by the Grey Wolf Optimizer (GWO) and Moth-Flame Optimization (MFO) algorithms. The results show that the CIPSO-SVR model achieves superior accuracy and robustness on the test set (R2= 0.9569) in predicting PPV compared to the alternative models. Crucially, the model effectively captures the inherent nonlinear relationships of complex engineering problems, even with small-sample data.OPEN ACCESS Received: 18/08/2025 Accepted: 17/10/2025 Published: 23/01/2026

Bearing Fault Diagnosis Based on AVMD and HPO-DBN

Jesús Sánchez Pinedo — Tue, 27 Jan 2026 10:09:22 +0100

To overcome difficulties such as non-stationary vibrations, highdimensional feature redundancy, and mode selection issues that may arise during signal decomposition in bearing fault diagnosis. We propose an adaptive method called Adaptive Variational Mode Decomposition (AVMD) for extracting time-frequency domain characteristics from the bearing vibration displacement signals to the maximum extent possible. Next, the ReliefF algorithm is employed to select desired features, and an autoencoder is used to reduce the selected features dimensionally. Furthermore, because the Hunter-Prey Optimisation (HPO) algorithm can balance multiple objectives during the search process by utilising the concepts of hunter and prey to generate a better solution set, incorporating this algorithm into the Deep Belief Network (DBN) establishes an HPO-DBN fault diagnosis model. Subsequently, we validate the proposed method using both public datasets and field compressor data. Moreover, we compare the results with those obtained from the Support Vector Machine (SVM). The findings indicate that this approach enhances the bearing fault identification rate, thus supporting predictive maintenance of bearings.OPEN ACCESS Received: 13/08/2025 Accepted: 16/10/2025 Published: 23/01/2026

Comparative Study of Fuzzy Logic, P&O, Incremental Conductance, and Artificial Neural Network MPPT Methods in Fluctuating Irradiance

Jesús Sánchez Pinedo — Tue, 27 Jan 2026 10:07:57 +0100

Photovoltaic (PV) energy is among the renewable and clean energies which are been widely used in recent years worldwide. To ensure optimal energy extraction under dynamic irradiance and temperature conditions, improving the efficiency of PV systems requires advanced Maximum Power Point Tracking (MPPT) techniques. To identify the most suitable technique that can be implemented practically, we conduct a comparative study in this paper between MPPT algorithms, namely Incremental Conductance (INC), Perturb and Observe (P&O), Fuzzy Logic (FL), and Artificial Neural Network (ANN). Using MATLAB/Simulink, our study was conducted under the same operating conditions, with a focus on efficiency, statistical analysis of robustness, and computational complexity. Our results show that the FL controller delivered the best overall performance, whose effectiveness depends on the accuracy of the rule base and scaling factors. It is characterized by a mean efficiency of 97.17%, a rapid response of 0.0585 s, minimal steady-state oscillations, and strong adaptability to environmental variations. The ANN-based approach achieves a mean efficiency of 94.91% and exhibits high performance at medium to high irradiance levels. However, its efficiency decreases significantly at low irradiance, resulting in reduced stability and increased deviation. INC and P&O achieve mean efficiencies of 95.20% and 95.15%, respectively. Moreover, due to their low computational cost, both techniques can be easily implemented. However, under rapidly changing conditions, they exhibit slower dynamics and more pronounced oscillations around the maximum power point, resulting in less stability.OPEN ACCESS Received: 01/08/2025 Accepted: 14/10/2025 Published: 23/01/2026

Reliability Modeling Using Weibull Distribution in Partially Accelerated Life Tests with Unified Hybrid Censoring: White Organic LEDs and Micro-Droplet Applications

Jesús Sánchez Pinedo — Tue, 27 Jan 2026 10:06:23 +0100

Accelerated life testing has become essential in modern reliability assessment, particularly for high-reliability products where traditional testing is often impractical due to time constraints. This study introduces a comprehensive framework for reliability analysis using Weibull-based partially accelerated life tests under a unified hybrid censoring scheme. Assuming lifetimes follow a Weibull distribution, we provide both classical and Bayesian estimation procedures to estimate core quantities, shape, scale, and the acceleration factor, alongside reliability metrics at normal operating conditions. The inferential framework encompasses point estimation along with uncertainty quantification, using both approximate confidence intervals and Bayesian credible intervals derived from Markov Chain Monte Carlo methods. A comprehensive Monte Carlo simulation study evaluates the performance of various methods in terms of mean squared error, interval coverage, and average interval width across a range of censoring patterns. The results provide actionable insights and practical recommendations for selecting appropriate methods and designing future studies under different censoring scenarios. The proposed methodology is further illustrated through two real-world case studies: the reliability of white organic light-emitting diodes and the lifetime of micro-droplets in ambient environments. These examples highlight the method’s flexibility and practical relevance in both engineering and biomedical reliability applications.OPEN ACCESS Received: 31/07/2025 Accepted: 10/09/2025 Published: 23/01/2026

Study on the Annular Fluid Level IdentificationAlgorithmfor Ultra-Deep Wells Based on AcousticVelocityCorrection

Jesús Sánchez Pinedo — Tue, 27 Jan 2026 10:05:34 +0100

The geological conditions and pressure system of ultra-deep oil and gas wells are complex, and formation leakage conditions are prone to occur. Accurately obtaining the annular liquid level depth during leakage is crucial for treatment decisions. In the high-temperature and high-pressure wellbore environment of ultra-deep wells, the sound velocity shows a nonuniform variation trend, which seriously affects the accuracy of annular liquid level identification. Therefore, it is of significance to carry out a study on the annular fluid level identification algorithm based on acoustic velocity correction. Based on establishing a calculation model for the annular temperature and pressure field, a sound velocity calculation model in the annular air section was constructed. By combining the actual sound velocity of the clear signal segment identified through the echo signal, the basic parameters in the sound velocity calculation model can be calibrated to obtain the calibrated wellbore sound velocity distribution. Finally, tests were conducted on simulated well sites and noisy production wells to verify the accuracy of the annular liquid level identification algorithm constructed in this study. The results showed that the identification algorithm had an error of less than 2%. All in all, this study can effectively meet the demand for dynamic annular liquid level data during the leakage conditions, which is of great significance for the treatment and decisionmaking in deep and ultra-deep wells.OPEN ACCESS Received: 30/07/2025 Accepted: 25/09/2025 Published: 23/01/2026

AI-Driven Modeling of Window Opening Behavior in Kindergarten Classrooms: A Case Study during the Transitional Season in the Cold Region of China

Scipedia content — Mon, 26 Jan 2026 12:19:35 +0100

With increasing awareness of energy conservation and environmental protection, optimizing indoor air quality and energy consumption through rational control of window opening behavior (WOB) has become a crucial issue in building design and environmental management. However, existing research primarily focuses on buildings for adults, with relatively few studies on buildings for children, particularly those used by children aged 3–6. Moreover, previous studies often overlook the impact of functional differences between buildings on occupant behavior patterns. This study focuses on a kindergarten and proposes an event-based method for analyzing and modeling WOB. The results show that events such as arrival, class, and departure are associated with higher frequencies of window opening (exceeding 50%), whereas events such as dietary activity, indoor/outdoor activity, sleep, and tidying exhibit lower probabilities. WOB is more sensitive to indoor air quality during events with higher student activity (e.g., class, dietary activity, and indoor activity), resulting in more frequent ventilation. In terms of modeling, the Random Forest (RF) algorithm achieved higher prediction accuracy than Logistic Regression (LR) and Support Vector Machine (SVM). To reduce the complexity associated with multi-model integration, a stacking model was introduced, further enhancing predictive performance. Finally, the generalizability of the proposed method was validated using office building data from the ASHRAE occupant behavior database, achieving a maximum accuracy improvement of 3.87%. This study presents a novel approach for modeling WOB in functional buildings such as kindergartens and provides theoretical support for energy efficiency optimization and indoor air quality management.

Functional H∞ Filtering for Descriptor Systems with Monotone Nonlinearities

Jesús Sánchez Pinedo — Mon, 26 Jan 2026 10:33:19 +0100

This paper proposes a new framework for the design of functional H∞ filters tailored for nonlinear descriptor systems affected by disturbances. Earliermethods have some significant drawbacks: they rely on the restrictive assumption of system regularity, employ implicit descriptor-form filters that complicate implementation, and emphasize full-order filtering, which is often unnecessary and computationally expensive. To overcome these drawbacks, the proposed filter is developed in an explicit state-space form that allows simple implementation with arbitrary initial conditions. Moreover, its order is minimized by matching it to the dimension of the functional vector, which reduces computational complexity compared to conventional filters. A new set of sufficient conditions is presented for the existence of a functionalH∞ filter, expressed through a rank condition and a linear matrix inequality (LMI) formulation. These conditions guarantee the stability of the estimation error dynamics while ensuring that the L2 gain from disturbances to errors remains below a specified bound. A numerical example based on a simple constrained mechanical system is presented to illustrate the effectiveness of the proposed method.

Bayesian and Non-Bayesian Inference for Discrete Model Based on Censored Samples with Optimal Test Plan

Jesús Sánchez Pinedo — Mon, 26 Jan 2026 10:32:33 +0100

In reliability and lifetime studies, it is often impractical to observe the failure times of all units in a sample, particularly when the process is timeconsuming or expensive. Type II censoring addresses this by terminating the experiment after a predetermined number of failures from a total sample of size. The Discrete Alpha Power Extended Inverted Weibull distribution is particularly suitable for modeling such censored discrete lifetime data. Its flexible shape parameters allow it to capture a wide range of failure behaviors, including over-dispersion, which is common in censored datasets. In this context, the likelihood function and estimation procedures (maximum likelihood and Bayesian) explicitly account for the censoring, ensuring unbiased parameter estimates and reliable predictive inferences. Consequently, the Discrete Alpha Power Extended Inverted Weibull distribution provides a practical and statistically robust framework for analyzing discrete lifetimes under type II censoring.OPEN ACCESS Received: 28/07/2025 Accepted: 19/09/2025 Published: 23/01/2026

Drill Bit Optimization Method Using Grey Clustering and Grey Correlation Analysis

Jesús Sánchez Pinedo — Mon, 26 Jan 2026 10:31:54 +0100

The conventional approach to drill bit selection primarily relies on the performance records of bits used in adjacent wells, where the bestperforming bit in each formation is selected for the corresponding zone to be drilled. However, this method does not take into account the lithology and rock mechanical properties of all relevant wells, nor can it evaluate the adaptability of a particular bit type to different intervals. As a result, it fails to fully ensure an optimal match between the bit and the formation, thus exhibiting significant limitations. To address these issues, this paper proposes a bit optimization method based on grey clustering and grey correlation analysis. This method comprehensively considers the influence of rock mechanics parameters on formation drillability and quantitatively evaluates the similarity in drilling resistance between the target formation and previously drilled intervals using grey clustering. This approach breaks away from the traditional constraint of limited bit options for a specific formation grade. Instead, it screens all previously used bit types to construct a candidate bit library for the target zone. Subsequently, the grey correlation method is applied to assess the candidate bits using multiple indicators that reflect bit performance. This enables the optimization of bit types for various target zones. Field applications demonstrate that the new bit selection method effectively improves upon the conventional practices by enhancing the flexibility and scientific basis of bit selection, and has yielded favorable results in actual drilling operations.OPEN ACCESS Received: 28/07/2025 Accepted: 16/10/2025 Published: 23/01/2026

Design and Implementation of a Vulkan-Based Rasterization System in the PC Environment

Jesús Sánchez Pinedo — Mon, 26 Jan 2026 10:28:40 +0100

Graphics application programming interfaces (APIs) for threedimensional (3D) rendering have been employed in computer graphics. Traditional 3D graphics APIs, such as Open Graphics Library (OpenGL), have structured the entire pipeline for the programmer’s convenience and are relatively easy to use. With the advancement of graphics hardware technology, new graphics APIs, including Vulkan, have been introduced to control specific function units of the graphics card and reveal the graphics processing power. Vulkan has many advantages, such as graphics processing power and parallel processing support. However, it also has the disadvantage of increasing the implementation costs because it requires detailed controls. This paper aims to implement a rasterization pipeline that applies a local illumination model with Vulkan. The implemented system can be used for standardized 3D graphics tasks as is and can also be used as a starting point for varying the pipeline configurations. This work designs and implements a Vulkan-based local rasterization pipeline. With this implemented platform, practical 3D rendering scenes are executed to be compared and analyzed with the rendering results from traditional OpenGL. The experimental results demonstrate the correctness and efficiency of the implementation. The implementation will be used as a testbed for various rendering experiments in the future.OPEN ACCESS Received: 27/07/2025 Accepted: 11/10/2025 Published: 23/01/2026

Advanced Reliability Analysis with Applications of Hjorth Constant-Stress Normal-Operating Setting Using Newly Progressive Censored Data

Jesús Sánchez Pinedo — Mon, 26 Jan 2026 10:28:28 +0100

Modern high-reliability products fail rarely, so researchers rely on accelerated life testing to obtain failure information within practical time limits. This study presents a useful framework integrating constant-stress accelerated life tests with an improved adaptive progressive Type-II censoring plan to estimate the reliability function under normal operating conditions of the Hjorth model. The Hjorth model is chosen because its hazard rate can be constant, increasing, decreasing, or bathtub-shaped, which reduces errors due to incorrect hazard assumptions. Stress affects lifetime through a log-linear relationship applied to the scale and the shape parameter. We derive the full likelihood for the proposed censoring plan across several stress levels, obtain maximum likelihood estimates with confidence intervals based on the observed information matrix, and develop a Bayesian analysis with informative prior distributions and sampling by Markov chain Monte Carlo technique. We then estimate reliability at normal operating conditions together with its interval estimates by both approaches. Extensive Monte Carlo simulations demonstrate the superior accuracy of the Bayesian estimators, especially when the number of observed failures is small or censoring is heavy, while maintaining interval coverage close to the nominal level. The practical utility of the proposed methodology is demonstrated through its application to real-world accelerated lifetime data sets. Applications to real-world data sets show that the proposed model fits the data well and yields reliable estimates of reliability at normal operating conditions.OPEN ACCESS Received: 26/07/2025 Accepted: 28/10/2025 Published: 23/01/2026

Research on Correction Method for Pipe-Soil p-y Curves in Submarine Silty Clay-Sand Gas Hydrate Formations

Jesús Sánchez Pinedo — Mon, 26 Jan 2026 10:27:23 +0100

The 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.

Bifurcation Analysis and Dynamical Investigation of Nonlinear DiffusionReaction Equations with Nonlinear Convective Flux Term: Stability and Applications

Jesús Sánchez Pinedo — Mon, 26 Jan 2026 10:24:40 +0100

The aim of this work is to examine the rich dynamics of quadratic and quartic nonlinear diffusion-reaction (DR) equations with a nonlinear convective flux term. These equations are crucial for simulating a variety of biological and physical processes, such as the dynamics of species populations. The main goal is to use the modified extended simple equation method (mESEM), a generalization of the standard simple equation method that hasn’t been used in this situation before, to extend the analytical treatment of such equations. We obtain a variety of new exact solutions using this method, such as breathers, kink and anti-kink waves, multi-peak solitons, bright-dark solitons, periodic waves, and waveforms represented by hyperbolic, trigonometric, and rational functions. Analyzing the stability and physical relevance of these solutions is another major goal of this work. Modulational instability analysis verifies the robustness of the obtained waveforms, while bifurcation analysis reveals qualitative changes in system behavior under parameter variations. The various wave structures and their dynamical characteristics are further highlighted with graphic illustrations. In general, the study highlights the potential of mESEM to reveal rich wave phenomena with applications spanning fluid dynamics, plasma physics, chemical reaction processes, population biology, neuroscience, and optical fiber communication, in addition to showcasing its effectiveness and versatility in solving nonlinear DR equations.OPEN ACCESS Received: 15/07/2025 Accepted: 18/09/2025 Published: 23/01/2026

Thermomechanical Uncertainty Analysis of Steel PartitionWalls Using Direct FE2 and Polynomial Chaos Expansion

Jesús Sánchez Pinedo — Mon, 26 Jan 2026 10:23:25 +0100

Steel partition walls are essential components in modern civil engineering, providing both structural support and spatial separation. These walls are frequently exposed to combined thermal and mechanical loads, particularly in specialized environments such as high-temperature workshops or fire scenarios, where their thermo-mechanical coupling behavior is critical to building safety and functionality. This study integrates the direct finite element squared (Direct FE2) method with generalized polynomial chaos expansion (PCE) to quantify the uncertainties in key material propertiesnamely, the elastic modulus and the coefficient of thermal expansionand to evaluate their effects on the thermo-mechanical performance of steel partition walls. The proposed approach enables efficient simulation of material uncertainties and their influence on structural behavior under coupled thermal-mechanical conditions. Case studies demonstrate both the accuracy and computational efficiency of the method, while sensitivity analysis highlights the most influential uncertainty factors. The integration of Direct FE2and PCE thus offers a robust framework for assessing the reliability of steel partition walls under uncertain conditions, providing valuable insights for design optimization and enhancing the safety and efficiency of building structures in practical applications.OPEN ACCESS Received: 05/07/2025 Accepted: 17/09/2025 Published: 23/01/2026

Modeling Engineering Reliability Data Using the Modified Generalized Exponential Distribution

Jesús Sánchez Pinedo — Mon, 26 Jan 2026 10:22:34 +0100

This study introduces the modified generalized exponential (MGEx) distribution, a flexible probabilistic model designed to capture complex failure behaviors commonly encountered in engineering systems. The MGEx distribution accommodates various hazard rate shapes, including unimodal, increasing, and decreasing forms, making it suitable for modeling reliability and lifetime data. We derive the mathematical properties of the model and focus on computational techniques for parameter estimation using multiple frequentist approaches. To evaluate the numerical performance of these methods, we conduct extensive Monte Carlo simulations, comparing their accuracy and robustness through partial and overall ranking metrics. The practical utility of the MGEx model is demonstrated by applying it to two real-world engineering datasets. The results highlight the model’s potential in enhancing simulation accuracy and supporting data-driven decision-making in reliability analysis, system design, and failure prediction tasks.OPEN ACCESS Received: 05/07/2025 Accepted: 27/10/2025 Published: 23/01/2026

Evaluation and Optimization of High Collapse Resistance Casing Strings for Salt Cavern Gas Storage in Salt Formations

Jesús Sánchez Pinedo — Fri, 23 Jan 2026 11:26:24 +0100

Salt cavern gas storage imposes stringent requirements on casing performance due to salt rock creep and high in-situ stress, necessitating a balance between mechanical strength and economic viability. This study evaluates the collapse resistance of BG110V and BG140V casings under 50°C–85°C through full-scale experiments (ASTM E2948) and elastoplastic finite element simulations. Results show that BG140V achieves a collapse strength of 75.94 MPa at 85°C, surpassing BG110V (52.96 MPa) at the same temperature by 43.4%, attributed to its thick-walled design (17.50 mm vs. BG110V’s 15.88 mm) and material enhancements. Simulations reveal lower prediction errors for BG140V (5.9% in full collapse) compared to BG110V (20.6%). A multi-criteria model integrating collapse strength (0.5), temperature sensitivity (0.3), and life-cycle cost (LCC, 0.2) with Monte Carlo analysis demonstrates BG140V’s LCC advantage in deep reservoirs (creep rate > 1.2× 10−7s−1, 12% maintenance cost reduction), while BG110V suits shallow scenarios (18% lower procurement cost). Dynamic selection strategies with real-time monitoring, low-friction thread optimization, crystal plasticity simulations, and smart maintenance systems are proposed. This study provides a quantitative framework for balancing safety and economy, advancing the standardization of non-API casings.OPEN ACCESS Received: 30/06/2025 Accepted: 19/08/2025 Published: 23/01/2026

Analysis of Airflow Velocity on Microdroplets Using Weibull StressStress Reliability Index under Unified Type-I Progressive Hybrid Data

Jesús Sánchez Pinedo — Fri, 23 Jan 2026 11:21:33 +0100

This work presents a novel and comprehensive inferential framework for analyzing the stress-strength reliability parameter,R= P(Y < X), where X and Y denote independent stress and strength variables, respectively, both modeled as Weibull-distributed with a shared shape parameter but distinct scale parameters. A key innovation of this study lies in its integration of the unified Type-I progressively hybrid censoring scheme, which simultaneously accommodates time constraints and partial failure information, conditions often encountered in real-world reliability testing. To estimate R, we propose and evaluate four distinct inferential strategies: two frequentist (maximum likelihood estimation and maximum spacings estimation) and two Bayesian, each tailored to either the likelihood or spacings-based posterior formulation. The Bayesian methods employ Monte Carlo sampling to compute both Bayes point estimates and credible intervals under informative priors, offering robustness in small-sample or heavily censored contexts. An extensive simulation study is conducted to systematically compare the estimators in terms of bias, efficiency, and interval coverage. To validate the practical applicability of our framework, we further analyze two real-world microdroplet datasets, revealing critical insights into stress-tolerance behavior under experimental constraints. This study not only advances methodological tools for reliability inference under hybrid censoring but also establishes a blueprint for combining classical and Bayesian paradigms in stress-strength modeling.OPEN ACCESS Received: 01/07/2025 Accepted: 02/09/2025 Published: 23/01/2026

Classical and Bayesian Stress-Strength Reliability Estimation for Weibull Data under Unified Hybrid Censoring Scheme with LED Application

Jesús Sánchez Pinedo — Fri, 23 Jan 2026 11:18:41 +0100

The stress-strength reliability parameter is a key metric used in various fields, including engineering, medicine, and business. In engineering, it quantifies the probability that a system’s strength X exceeds the applied stress Y . In this study, we examine for the first time four estimation approaches for evaluating the stress-strength reliability parameter R= P(Y < X ), where X and Y are independent Weibull random variables with different scale parameters but a common shape parameter. The analysis is conducted under a unified hybrid censoring scheme. From the classical perspective, we employ the maximum likelihood and maximum product of spacings methods to obtain both point and interval estimates. From the Bayesian perspective, two forms of the posterior distribution, based on the likelihood and spacings functions, are derived and analyzed using Markov Chain Monte Carlo sampling techniques. The Bayes estimates of R are obtained under the symmetric squared error loss, and the corresponding Bayesian credible intervals are also computed. To compare the four point estimators and the four interval estimators, an extensive simulation study is performed using various experimental scenarios. Finally, comprehensive analyses for organic white light-emitting diode datasets mixed with three colors, namely red, green, and blue, are provided.OPEN ACCESS Received: 29/06/2025 Accepted: 16/09/2025 Published: 23/01/2026

Numerical Investigation on Condensation of Non-Condensable Gas in Large Deformation Enhanced Tube

Jesús Sánchez Pinedo — Fri, 23 Jan 2026 11:17:28 +0100

In order to improve the condensation heat transfer performance of tubelines in cooling systems, a new type of large deformation heat transfer tube was proposed. Based on the theory of diffusion, the distributions of temperature, velocity, heat transfer coefficient, and species are presented to compare with smooth tubes. In addition, the effects of relevant parameters on thermo-hydraulic performance are discussed. The numerical results show that the distributions of temperature and velocity show a periodic distribution. The unique structure of the large deformation heat transfer tube disturbs the fluid flow near the wall. The boundary layer of air concentration is destroyed, resulting in heat transfer enhancement. Within the scope of this paper, the heat transfer coefficient and friction factor of the large deformation heat transfer tube are increased by 1.01–3.47 times and 1.05–7.13 times compared with the smooth tube. The heat transfer performance increases with the rising dimple depth and declining noncondensable gas content and dimple pitch.OPEN ACCESS Received: 25/06/2025 Accepted: 29/07/2025 Published: 23/01/2026

Reconfigurable Solar-Powered Multiple Input Multiple Output Terahertz Antenna System

Jesús Sánchez Pinedo — Fri, 23 Jan 2026 10:41:33 +0100

The 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: 23/01/2026

Multi-Objective Optimization and Performance Evaluation of Manifold-Based Cooling Systems for Battery Thermal Management Using RSM and NSGA-II

Jesús Sánchez Pinedo — Fri, 23 Jan 2026 10:37:24 +0100

Efficient thermal management is critical to the safety, performance, and longevity of lithium-ion battery (LIB) energy storage systems. In this study, a novel manifold cold plate featuring an overflow channel with a triangular ridge at the bottom is proposed for a liquid-cooled Battery Thermal Management System (BTMS). A comprehensive multi-objective optimization framework is developed by integrating Response Surface Methodology (RSM), the Non-dominated Sorting Genetic Algorithm II (NSGA-II), and the Linear Programming Technique forMultidimensional Analysis of Preference (LINMAP) decision-making method to minimize the maximum temperature difference (Tcell) and pressure drop (P) across the cooling plate.Thedesign variables include the manifold channel width ratio (λ), the height ratio (φ), the inlet velocity (u), and the triangular ridge angle (θ). Second-order polynomial regression models are constructed and validated using Analysis ofVariance (ANOVA), yielding high coefficients of determination (R2 = 0.9926 forTcell and 0.9600 forP), confirming strong predictive accuracy. Sensitivity analysis reveals that the inlet velocity and channel angle are the primary factors influencing system performance. The LINMAP-based decision-making approach identifies an optimal configuration with λ = 1.031, φ = 1.47, u = 1.671 m/s, and θ = 29.8°, achieving a Tcell of 12.61°C and a P of 6742.99 Pa, with validation errors below 3%. Transient simulations at 0.5 and 1C discharge rates show that the LINMAP-optimized design reduces the maximumcell temperature by 13.12°C and 11.77°C, respectively, compared to the natural convection baseline, and by 1.42°C and 0.76°C compared to the prototype design, while maintaining comparable hydraulic resistance. This work offers valuable guidance for designing and optimizing liquid-cooled battery

Analysis of Burr-XII Lifespan Using Adaptive Progressive Type-II Hybrid Binomial Censoring with Physical Modeling of Polyester and Carbon Fibers

Jesús Sánchez Pinedo — Fri, 23 Jan 2026 10:35:28 +0100

This study introduces advanced statistical methods, allowing for more efficient and accurate reliability testing of fibers such as polyester and carbon. Polyester ficbers are suitable for textiles and industrial use due to their wrinkle resistance and affordability, while carbon fibers offer superior strength, thermal stability, and corrosion resistance. To guarantee greater efficiency of inference methodologies and reduce overall testing time, the adaptive Type-II progressive hybrid censoring via binomial removals has gained popularity in reliability analysis and life-testing problems. The proposed scheme allows survival units to be removed at random stages according to a binomial law, thereby reducing experimental time while preserving statistical efficiency. When lifetimes are gathered using the suggested censoring technique, point and interval estimates of the unknown parameters of the Burr-XII model are obtained using both classical and Bayesian approaches. We obtain various Bayesian estimates using the squared loss function. Some numerical methods are employed to obtain the suggested estimators due to their complexity. The various Bayes estimates and related credible intervals are created using Markov chain Monte Carlo techniques. To assess estimator performance, extensive simulation studies are conducted, comparing bias, mean squared error, coverage probabilities, and interval lengths under varying censoring and removal settings. The simulation results confirm that the Bayesian framework, particularly with informative priors, provides more accurate and stable estimates than asymptotic likelihood-based methods. We examine two physics data sets representing polyester and carbon fibers to demonstrate the relevance of the suggested approaches in a real-world setting. These applications highlight the practical value of the proposed approach for material design, maintenance planning, and broader reliability engineering problems.OPEN ACCESS Received: 13/06/2025 Accepted: 12/09/2025 Published: 23/01/2026

AI-Driven Multi-Dimensional Computing Power Scheduling: Adaptive Resource Coordination via Task Demand Prediction in Heterogeneous Clusters

Jesús Sánchez Pinedo — Fri, 23 Jan 2026 10:34:03 +0100

This paper introduces an AI-driven computing power scheduling framework that innovatively integrates multidimensional resource optimization with machine-learning-based task-demand prediction to significantly enhance computational efficiency and resource utilization. Unlike prior works that primarily focus on Graphics Processing Unit (GPU) allocation, our method pioneers a holistic resource-coordination mechanism that dynamically balances GPU, memory, Central Processing Unit (CPU), and other critical resources according to their joint impact on task performance and cluster efficiency. A core innovation is our data-driven resource predictor, which autonomously analyzes historical task patterns and forecasts future demand, enabling the scheduler to adaptively scale resources so that user over-provisioning is reduced and under-allocation bottlenecks are avoided. Experimental validation demonstrates that this closed-loop prediction–scheduling paradigm achieves breakthroughs in both scale and efficiency: a 25.7% increase in concurrent task deployment, a 15.6% increase in task completion rate, and substantial relative utilization improvements of 7.5% for GPU and 8.0% for memory, outperforming conventional single-resource optimization approaches. These advancements establish a new direction for intelligent resource management in large-scale heterogeneous computing environments.OPEN ACCESS Received: 15/05/2025 Accepted: 11/10/2025 Published: 23/01/2026

Statistical Inference of Step Stress Partially Accelerated Life-Testing for Insulating Fluid between Electrodes under Censored Data and Different Loss Functions

Jesús Sánchez Pinedo — Fri, 23 Jan 2026 10:33:24 +0100

Long testing times are usually required for the life testing of very reliable products or materials. The testing process can be hastened by using accelerated life tests. The lifespan of the items that accelerated life tests inspect is reduced since they test products in more severe circumstances than those found in regular use scenarios. Data that was censored and disclosed the precise timings of failure may point to accelerated life tests where all units assigned to test are unknown, or where all units assigned to test have not failed for a few reasons, including challenges with technology, tools, costs, and schedules. The step-stress partially accelerated life test was examined in this work using the type-I progressive hybrid censoring scheme and the type-II progressive censoring scheme. The influence of the stress shift is explained using the tempered random variable model, where the failure times of the items are assumed to follow the alpha power Lomax distribution. The unknown parameters are estimated using the maximum likelihood estimation and Bayesian methods. The asymptotic theory of maximum likelihood estimation is also employed in the construction of the approximate confidence intervals. While the point estimates under two censoring schemes are compared in terms of absolute biases and root mean squared errors, approximate confidence intervals and coverage probabilities are compared in terms of their lengths and coverage probabilities. Additionally, three possible optimal test strategies are investigated using different optimal criteria. The performance of the estimators was evaluated and contrasted with two censoring techniques with various sample sizes using a simulation study. Finally, a numerical example for insulating fluid between electrodes data is presented to illustrate how the methods will work in real-world scenarios.OPEN ACCESS Received: 11/06/2025 Accepted: 29/07/2025 Published: 23/01/2026

Numerical Simulation Analysis of Influence of Wind and Temperature on Deformation of Constructed Zhaidi River High Bridge Pier

Jesús Sánchez Pinedo — Fri, 23 Jan 2026 10:32:35 +0100

Bridges are key projects of high-grade Expressways in mountainous areas. The verticality of bridge piers with a height of more than 100 m is crucial to ensure the safety and stability of bridge projects. When a pier construction is completed but the upper beam structure has not yet been connected (socalled after construction or constructed), the verticality of the pier is most likely to vary due to some factors. Based on the Zhaidi River Bridge project of Yunnan Zhenhe Expressway, considering the natural environment of the bridge site, three wind force intensity levels (Beaufort Scale 8, 10, and 12) and two climate conditions (high temperature and high radiation in summer, and low temperature and low radiation in winter) were identified; and the wind-induced deformation, temperature-induced deformation, and wind-temperature coupled deformation of the constructed main pier of the Zhaidi River Bridge with a height of 112.60 m were simulated with ANSYS Workbench numerical simulation platform. The simulation results show that: the influence of wind on pier deformation is much greater than that of ambient temperature variation; the influence of solar radiation on temperature-induced deformation of the bridge pier is much greater than that of air temperature variation; the temperature-induced deformation of the pier body under low temperature and low radiation condition in winter is greater than that under high temperature and high radiation condition in summer; the directional effect of the superposition of wind-induced deformation and temperature-induced deformation is more significant under low temperature and low radiation condition in winter.OPEN ACCESS Received: 11/04/2025 Accepted: 16/10/2025 Published: 23/01/2026

Evolution Families and Time-Varying Processes in Modular Function Spaces

Nisar Ahmad — Fri, 23 Jan 2026 09:06:44 +0100

This paper develops a modular framework for the study of time--dependent linear evolution processes via evolution families. We consider non--autonomous abstract Cauchy problems generated by families of operators depending on time and introduce a notion of $\varrho$--strong continuity compatible with the modular topology. Under suitable uniform $\varrho$--boundedness assumptions, we establish the existence of evolution families and derive modular growth estimates formulated in terms of the associated modular growth function. To address regularity issues, a Steklov--type averaging technique is employed, allowing differentiability and domain inclusion to be treated in the modular sense. Several examples, including time--varying multiplication processes in integral and Orlicz--type modular spaces, are presented to illustrate the scope and effectiveness of the proposed approach.

A Quantitative Assessment of Supplier Service Quality Using AHP and SERVQUAL in

Mohammed Al Awadh — Mon, 19 Jan 2026 20:40:23 +0100

The selection and assessment of suppliers are essential for improving supply chain efficiency and fostering competitiveness. This study investigates the application of the Analytical Hierarchy Process (AHP) as a proficient method for assessing supplier service quality. AHP, a multi-criteria decision-making tool, provides a systematic and structured framework for evaluating the critical factors influencing supplier performance. The study employed the AHP model to evaluate supplier service quality in small and medium-sized enterprises (SMEs) to achieve this objective. The SERVQUAL framework consists of five dimensions—reliability, responsiveness, assurance, tangibles, and empathy accompanied by 20 sub-criteria, developed using the AHP technique. The analysis focused on evaluating the service quality of three distinct vendors, meticulously assessing their overall performance. The findings suggested that providers should emphasize reliability, responsiveness, certainty, and tangibles, while placing relatively less significance on empathy. Among the sub-criteria, delivering accurate services on the first attempt emerged as a significant issue for vendors. The AHP analysis indicates that Supplier A attained the highest performance ranking, followed by Supplier C and Supplier B. This study's findings offer actionable insights for decision-makers to effectively manage and enhance the aviation sector. By focusing on delivering exceptional services, suppliers can significantly improve customer satisfaction, aligning with the fundamental goal of supplier service excellence.

Effects of Trichosanthes Root Extract on Regeneration Rate, Behavior, and Locomotor Activity in Dugesia tigrina

Alexander Lee — Tue, 13 Jan 2026 14:47:14 +0100

This study investigated the effects of Trichosanthes root extract on the regeneration rate of Dugesia tigrina, a freshwater planarian. Planarians were chosen for their regenerative ability and stem cell systems. Traditionally used in Chinese medicine for its anti-inflammatory and antioxidant properties, Trichosanthes root was tested for its unexplored regenerative potential. The goal was to evaluate a cost-effective, biologically based method for enhancing tissue regeneration with potential applications in regenerative medicine and wound healing. Planarians were continuously exposed to varying concentrations of the extract, with locomotor activity recorded before and after treatments. Specimens were then transversely amputated into head and tail fragments, which were observed independently. Regenerative outcomes, including body length, eyespot formation, and indicators of nervous system recovery, were measured at regular intervals. Results demonstrated that in trial 1, group D slightly decreased in head length regeneration compared to our control group A. Although group A had the smallest amount of head regeneration over the course of 11 days, there was no significant difference found between the groups in trial 1. Similarly, group C had the least regenerative ability overall over 11 days, but there was still no statistical difference found between the groups. Ultimately, Trichosanthes root was not significantly effective in the regeneration, locomotor activity, and behavior of Dugesia Tirgrina. These findings suggest that even as planarians remain valuable assets in testing biological compounds, Tricosanthes root may not have benefited tissue regeneration as hypothesized.

The Effects of GlyNAC on the Regeneration Rate and Movement of Dugesia tigrina

Alexander Lee — Fri, 02 Jan 2026 16:52:23 +0100

This study aims to investigate the effects of GlyNAC on planaria tissue regeneration and behavioral changes. There has been a focus on anti-aging in the older population due to the adverse effects that come with it such as muscle fatigue, a decrease in tissue regeneration, etc. As a result, there was an increase in research on finding an effective supplement to combat health issues and aging. GlyNAC, a combination of Glycine and N-acetylcysteine, has been shown to reverse and improve health by increasing glutathione levels. Glutathione is an antioxidant with multiple health benefits such as protecting against oxidative stress, a main factor in causing cell death. This experiment was conducted using planarians because they have a similar central nervous system, tissue regeneration, and glutathione production to humans. There were 1 control group and 3 experimental groups. The control group was fed regular ground beef while the experimental group was fed ground beef with GlyNAC. For tissue regeneration, each group would be measured and observed before and after the ground beef or GlyNAC-mixed ground beef. The planarians’ motility was recorded for 20 minutes with grid paper underneath their petri dishes. The results indicate that GlyNAC treated groups had increased regeneration and movement. With this support, our hypothesis of GlyNAC increases the regeneration and movement in planarians. Future Research can be done by having bigger experimental groups for more accurate data. Introduction GlyNAC There has been an interest in anti-aging in the modern day due to one’s fear of aging and the many symptoms that come with it, such as muscle fatigue, inflammation, a decrease in tissue

Drift Boss: Drive really far

Drift boss — Thu, 01 Jan 2026 08:53:22 +0100

Get ready to slide into the driver's seat of Drift Boss, a deceptively simple yet addictive driving game where timing is everything. Forget complex controls; this game is all about the one-button mechanic. Your mission is to navigate endless, winding tracks floating high in the sky, drifting around sharp corners with perfect precision. It sounds easy, but the procedurally generated paths demand intense focus and quick reflexes. As you collect coins and unlock unique vehicles—from taxis to fire trucks—you’ll find yourself hooked, constantly chasing that next high score. Can you stay on track, or will you plummet into the abyss?

The effect of Pomegranate juice on C. elegans under Thermal Stress

Armaanjit Singh — Thu, 01 Jan 2026 04:02:33 +0100

This experiment analyzed the effects of pomegranate juice on C. elegans under thermal stress. C. elegans, a nematode with similar genes to humans, is an effective model for studying human diseases. Thermal stress occurs when an organism is exposed to high temperatures, which results in the release of heat shock proteins. Heat shock proteins act as molecular chaperones that help restore protein homeostasis following heat stress. Despite their presence, thermal stress can still weaken antioxidant defense in organisms. However, pomegranate juice is rich in antioxidants and polyphenols, which can help strengthen antioxidant defense. In this study, pomegranate extract was dissolved in water and mixed with agar powder. Using this pomegranate mixed agar, E. coli was cultured for 24 hours. The results showed that the 5 mg/ml concentration increased survival rates of C. elegans. However, the 10 and 20 mg/ml concentrations lowered survival rates, which can be attributed to dose-dependent toxicity. Interestingly, the higher concentrations of pomegranate extract significantly increased C. elegans reproductive rates. This research expands on previous studies that examined the effect of pomegranate juice on C. elegans and distinctly focuses on its role under thermal stress. This distinction helps gain a deeper insight into pomegranate juice's effect on oxidative stress.

GANADOGO: APLICACIÓN MÓVIL PARA EL CONTROL Y GESTIÓN DE GANADO MEDIANTE GPS Y GEOREFERENCIACIÓN

Helmer Ahumada Hernandez — Thu, 28 Aug 2025 18:36:44 +0200

GanadoGo es una innovadora aplicación móvil diseñada para optimizar la gestión ganadera en el municipio de Sampués, Colombia. Mediante la integración de geolocalización GPS y dispositivos micro:bit, la aplicación permite el seguimiento y monitoreo del ganado en tiempo real, mejorando el control y minimizando las pérdidas. La implementación de GanadoGo representa un avance significativo en la eficiencia productiva, el bienestar social y la sostenibilidad ambiental. Este proyecto apoya el desarrollo rural y económico de la región, en consonancia con los planes de desarrollo nacionales y sectoriales, a la vez que mejora la seguridad alimentaria, promueve la inclusión social y fomenta el uso responsable de los recursos naturales.

The Effects of Pomegranate Juice on C. elegans under Thermal Stress

Armaanjit Singh — Mon, 21 Jul 2025 20:30:43 +0200

This experiment analyzed the effects of pomegranate juice on C. elegans under thermal stress. C. elegans, a nematode with similar genes to humans, is an effective model for studying human diseases. Thermal stress occurs when an organism is exposed to high temperatures, which results in the release of heat shock proteins. Heat shock proteins act as molecular chaperones that help restore protein homeostasis following heat stress. Despite their presence, thermal stress can still weaken antioxidant defense in organisms. However, pomegranate juice is rich in antioxidants and polyphenols, which can help strengthen antioxidant defense. In this study, pomegranate extract was dissolved in water and mixed with agar powder. Using this pomegranate mixed agar, E. coli was cultured for 24 hours. The results showed that the 5 mg/ml concentration increased survival rates of C. elegans. However, the 10 and 20 mg/ml concentrations lowered survival rates, which can be attributed to dose-dependent toxicity. Interestingly, the higher concentrations of pomegranate extract significantly increased C. elegans reproductive rates. This research expands on previous studies that examined the effect of pomegranate juice on C. elegans and distinctly focuses on its role under thermal stress. This distinction helps gain a deeper insight into pomegranate juice's effect on oxidative stress.

Compensation of thermal and mechanical effects of a Lamb-Wave based SHM system in a composite aerostructure.

Jesús Sesé — Sun, 06 Jul 2025 23:08:53 +0200

Structural Health Monitoring has become one of the next challenges in the aeronautical industry in order to know the real-time status of structures and optimize their maintenance. The use of Lamb Waves for damage detection is proven; however, its effectiveness is affected by the boundary conditions in which the structure is located. To counteract this effect, it is essential to model its behavior in different environmental and operating conditions to ensure the correct detection of variations in the structure during its service life. This work presents the characterization of the Lamb wave behavior for a composite UAV supporting surface. By applying different load and temperature conditions to the structure, different conditions of the structure during flight will be simulated. The results obtained for the newly fabricated structure will be compared with the results obtained for the same structure damaged by impact. And finally, the main effects produced on the signal (arrival time, amplitude...) will be analyzed; and how they can simulate the presence of a damage that has not occurred (false positive) or camouflage the presence of existing damage (false negative).

Fracture characterization of hybrid composite laminates in modes I and II

Juan de Gracia Igelmo — Wed, 02 Jul 2025 09:27:53 +0200

In this work, the Mode I and Mode II interlaminar fracture toughness of a hybrid laminate composite consisting of carbon fiber-reinforced layers and glass fiber-reinforced layers was characterized. Unidirectional laminates were used for the tests, and the stacking sequence was chosen with the aim of achieving pure fracture modes in the tests. Mechanical characterization was carried out using three-point bending tests with different spans, taking into account the effects of indentation, shear, and support rotation. Mode I and Mode II interlaminar fracture tests were performed using the ADCB (Asymmetric Double Cantilever Beam) and AENF (Asymmetric End Notched Flexure) tests, respectively, also considering the effects of shear, local deformation, and rotations due to bending. The data were obtained using a recently published analytical model that allows the resistance curve to be found for each load-displacement data obtained from the testing machine.

Matrix cracking effect in thermoset and thermoplastic CFRP: development of an analysis tool for the design of hydrogen tanks

Mayerlin Salgado — Thu, 12 Jun 2025 14:32:44 +0200

Liquid hydrogen (LH₂) is a promising alternative to reduce carbon dioxide (CO₂) emissions in the aeronautical industry. However, current tanks do not meet their rigorous design and safety requirements. Carbon Fibre Reinforced Polymers (CFRP) offer advantages over classic metallic materials, such as higher stiffness and toughness at low temperatures, as well as lower density. Nevertheless, matrix cracking in composites can cause leaks through the tank walls, compromising their tightness, even with a low crack density. Therefore, a deeper understanding of this phenomenon could prevent permeability loss and ensure the operational safety of the tank. Currently, thermoplastic composites are gaining distinction over thermosets in the aeronautical industry due to their better range of properties and the possibility of out-of-autoclave manufacturing. In this context, CF/PEEK composite has shown greater resistance to damage propagation compared to epoxy-based materials, positioning it as a promising candidate for LH₂ storage tanks. This research evaluates the initiation and propagation of transverse cracks in the matrix in specimens with 0º and 90º layer orientations of thermoplastic (CF/PEEK) and thermoset (M21E/IMA-12K) matrices under static loads and at room temperature. Two different stacking sequences, [0/90/0₂/90₂]s and [90/0/90₂/0₂]s, have been analysed. X-ray tomography images were captured at different deformation states. From these images, crack density was calculated using a digital processing method developed by the authors, which quantifies the number of cracks in each layer across the entire width of the specimen. This method allows for a three-dimensional (3D) visualization of the inspected area, facilitating the tracking of possible paths that could compromise the tightness of the tanks. These results contribute to the design of safer and more efficient tanks for liquid hydrogen storage in aeronautical applications.

Flame retardant polyurethane nanofibers based on the Diels-Alder reaction

Arantxa Eceiza — Tue, 10 Jun 2025 18:03:24 +0200

In this study, a halogen-free flame retardant containing maleimide groups was synthesized and incorporated into a polyurethane solution containing pendant furan groups (PUF), with the aim of producing nanofibres via electrospinning. The furan groups of the polyurethane and the maleimide groups of the flame retardant readily react with each other via the Diels–Alder (DA) reaction. The resulting nanofibre membranes were characterized before and after crosslinking through DA reaction. Microscopy images of the membranes showed morphologically homogeneous and defect-free nanometric fibers. The crosslinked membranes exhibited higher solvent resistance and superior mechanical properties compared to the uncrosslinked ones. Thermal analysis showed that the flame retardant promotes the formation of a protective carbonaceous layer that gives the membranes fire-resistant properties.

Development of thermoplastic composites with energy storage capacity for aeronautical applications

Fernando Ramos Saz — Fri, 16 May 2025 20:23:22 +0200

The RE-CELL project proposes a comprehensive approach to developing multifunctional structural composites capable of energy storage for non-critical aeronautical applications. The project is rooted in the recycling and valorization of carbon fiber waste through solvolysis, promoting environmental sustainability and circular economy principles. Recovered fibers are functionalized with conductive materials such as carbonaceous particles and MXenes, enabling them to serve as both structural reinforcement and electrodes. Solid electrolytes are produced by incorporating thermally stable ionic liquids and BaTiO₃ as a dielectric enhancer into a polycarbonate matrix via extrusion. The resulting films function simultaneously as electrolytes and separators. Finally, the structural cells are assembled by compression molding and subjected to mechanical (tensile, flexural, delamination) and electrochemical (electrochemical impedance spectroscopy, cyclic voltammetry) characterization. The project aims to scale up the most promising multifunctional laminates and validate their performance through a demonstrator based on the geometry of an actual aircraft fuselage component.

Mechanical performance of continuous fiber-reinforced thermoplastic composites for structural applications

Jaime Lozano — Fri, 16 May 2025 07:47:23 +0200

Continuous fiber-reinforced thermoplastic composites are emerging as an efficient structural alternative to traditional thermoset materials, thanks to their recyclability, good impact resistance, and suitability for continuous processing. In this work, a manufacturing system was developed based on the thermoplastic pultrusion of unidirectional polypropylene (PP) and carbon fiber (CF) tapes, followed by hot compression molding. This approach enables the production of structural profiles with high fiber alignment and good consolidation. Experimental characterization included tensile, flexural, and impact tests to assess the structural applicability of the manufactured profiles. The results demonstrate a balanced combination of stiffness, mechanical strength, and impact performance, confirming the potential of this system for functional applications in sectors such as mobility or infrastructure, where lightweight, efficient processing, and sustainability are key requirements.

Development of dry fiber based on thermoplastic binders for aeronautical applications

GUILLERMO ULLDEMOLINS DE OLIVES — Thu, 15 May 2025 12:13:34 +0200

As part of the regional NEOCOMP project, funded by IVACE in the Valencian Community, AIMPLAS presents a comprehensive approach to the development of advanced composite materials by producing dry fiber through its own pilot line. This work focuses on the development of thermoplastic binders, dry fiber production, pre-consolidation and resin infusion, as well as the study of mechanical properties. The main objective is the development of thermoplastic binders and the subsequent production of dry fiber. The binders will be formulated using compounding technologies with co-rotating twin-screw extruders to ensure proper dispersion and distribution of the additives. The dry fiber will be produced using a pilot plant system designed and developed by AIMPLAS, equipped with the necessary technology for binder adhesion onto continuous reinforcement. Finally, the materials will be validated for processing with AFP (Automated Fiber Placement) equipment to achieve pre-consolidated panels. After pre-consolidation, resin infusion will be carried out to obtain high-performance structural materials. The binder materials will be characterized through powder granulometry analysis, while the dry fiber will be studied using scanning electron microscopy (SEM) to evaluate binder-to-fiber distribution and adhesion. The project concludes with a thorough tensile analysis of the infused panels, following standards for mechanical performance evaluation. The results obtained not only highlight the potential of the developed materials but also demonstrate the feasibility of this approach for the industrial production of high-performance composite materials for key sectors such as aerospace.

Lightweight, very high-speed bogie frame. CFRP in high-responsibility railway components

Diego Escobar Redondo — Fri, 25 Apr 2025 16:50:14 +0200

In recent years, the railway sector has been demanding lighter, high-responsibility components made from composites due to the incorporation of new technologies to improve passenger comfort and experience, as well as to address new environmental challenges (reducing emissions, energy consumption, increasing capacity, etc.). With this objective, Talgo introduces a high-performance composite bogie frame (CFRP) for very high-speed trains, traditionally made of metal (steel), which allows for weight reductions of over 30%. Additionally, this new bogie leverages the fatigue properties of these materials to incorporate the first stage of suspension into the frame itself. The reduction of bogie elements, as well as infusion manufacturing, improves competitiveness throughout the lifecycle compared to a traditional bogie, complying with the EN-45545-2 HL2 standards for fire, smoke, and toxicity. The project for this lightweight frame will be completed with manufacturing and bench testing in accordance with EN 13749 standards, as well as ballistic impact tests with ballast stones.

Nanocomposites based on PVDF-HFP and piezoelectric nanoparticles fabricated by solvent-casting and electrospinning techniques for sensing applications

Esther Arribas Yuste — Mon, 14 Apr 2025 23:24:13 +0200

This work deals with the development of flexible piezoelectric nanocomposites based on PVDF-HFP copolymer reinforced with ZnO nanoparticles (NPs) for biomedical sensing applications. Two fabrication techniques are analyzed: solvent casting and electrospinning. The films obtained by the solvent casting technique, characterized by FTIR-ATR and Atomic Force Microscopy (AFM) in PFM mode, show a significant increase of the piezoelectric coefficient (d₃₃) for ZnO NPs concentrations equal or higher than 12% by weight, with respect to the unreinforced polymeric matrix. FTIR analysis estimated an electroactive phase content close to 60% in the reinforced samples. On the other hand, the preliminary study of optimization of electrospinning parameters, evaluated by Scanning Electron Microscopy (SEM), demonstrates the feasibility of forming mats with high fiber content and homogeneous nanofiber diameters between 110-140 nm, whose morphology depends on parameters such as the speed of the collector. These preliminary results are promising for obtaining flexible piezoelectric fabrics by both fabrication routes.

Characterization of 3D-printed cordierite-rGO nanocomposites for aerospace applications

Maria Garcia-Martinez — Mon, 14 Apr 2025 23:00:45 +0200

One of the most critical challenges in the aerospace industry is the mismatch in the coefficient of thermal expansion (CTE) between optical components in satellites and their metallic supports, which limits system reliability and performance. Ceramic materials, due to their superior thermal properties, offer a potential solution; however, their adoption has been limited by the complexity of their geometries and conventional manufacturing constraints. Additive manufacturing has opened new opportunities for the development of advanced ceramics, including ceramic matrix composites (CMCs). Within the framework of the AERORECORD-3D project, funded by the Spanish Ministry of Science and Innovation, ceramic cordierite-based supports reinforced with reduced graphene oxide (rGO) have been developed for aerospace applications. In this study, cordierite nanocomposites with varying rGO contents were successfully fabricated via 3D printing. Their thermal, electrical, and mechanical properties were evaluated to assess their performance, exploring their potential as advanced materials for demanding space applications. This work represents a significant step toward the implementation of 3D-printed ceramic nanocomposites by combining innovative materials with advanced additive manufacturing technologies.

Caracterización de las propiedades mecánicas de estructuras kirigami impresas en 3D y sus conexiones fabricadas con materiales compuestos

Montserrat Dolz — Mon, 14 Apr 2025 22:00:24 +0200

El avance de la tecnología de impresión 3D ha permitido la creación de estructuras complejas con formas únicas, como los diseños basados en kirigami, inspirados en el arte de cortar papel para formar estructuras tridimensionales. Estas estructuras ofrecen beneficios significativos, como una construcción ligera, despliegue rápido y la capacidad de soportar cargas mecánicas y absorber energía de deformación. Sin embargo, existe una investigación limitada sobre el comportamiento de estas estructuras y sus conexiones críticas cuando se fabrican con materiales compuestos mediante técnicas de impresión 3D.

Este estudio examina las propiedades mecánicas de estructuras kirigami impresas en 3D y sus conexiones, centrándose en mejorar el comportamiento de unión y optimizar el uso del material. Se emplea el marco Space Mapping para abordar la anisotropía inherente de los compuestos impresos en 3D, transformando el comportamiento direccional complejo del material en un dominio isotrópico equivalente. Este enfoque permite aplicar modelos no lineales isotrópicos ya consolidados, mejorando la precisión de la simulación y reduciendo el coste computacional.

Se utilizan simulaciones por elementos finitos para modelar el comportamiento de las estructuras kirigami, prestando especial atención a las propiedades del material, la adhesión entre capas, la dirección de impresión y la orientación de las fibras en el material compuesto. Se llevan a cabo ensayos mecánicos para validar las simulaciones, centrándose en la rigidez y resistencia de los pliegues y uniones bajo diferentes condiciones de carga. Mediante la mejora de los mecanismos de plegado y la optimización de la distribución del material en las zonas críticas, esta investigación busca demostrar cómo se comparan las estructuras kirigami frente a los diseños sólidos tradicionales en aplicaciones que requieren tanto resistencia como adaptabilidad.

Estos resultados son especialmente relevantes para sectores donde se necesitan diseños ligeros y flexibles, como la aeronáutica, la automoción, el transporte marítimo y la ingeniería civil. Combinando análisis numérico con validación experimental, el estudio ofrece aportaciones valiosas para la optimización de los puntos de plegado y conexión en estructuras kirigami impresas en 3D, con vistas a su aplicación en la ingeniería avanzada.

Experimental characterisation of the translaminar fracture toughness of an additive manufacturing c-CFRP composite

Alex Fernández — Mon, 14 Apr 2025 13:32:24 +0200

Fibre breakeage in composite materials is usually a determining damage mechanism for its structural integrity due to the high energy associated, in comparison with matrix cracking. For this reason, the assessment of the translaminar fracture toughness is relevant for accurate numerical predictions of composite structures. However, there are scarce investigations related to this topic for additive manufactured composites reinforced with continuous fibres. In this investigation, the translaminar fracture toughness of 3D-printed continuous fibre reinforced polymer (c-CFRP) composites was characterised using double-tapered compact tension (2TCT) specimens. The 2TCT geometric dimensions were obtained through a parametric study to prevent undesired failure modes. The results show a translaminar fracture toughness of 17.4 N/mm for the tested 0/90 laminates. The fracture toughness corresponding to the tensile failure of the 0° ply was derived using a rule-of-mixtures approach. Post-mortem micrographic and X-ray analysis indicated the presence of fibre pull-outs in the crack surface and confirmed the absence of any additional damage, validating the use of 2TCT geometry for the determination of the translaminar fracture toughness in additively manufactured c-CFRP composites.

Development and integration of printed strain gauge-based sensors for structural health monitoring in composite material repairs of wind turbine blades

EDURNE TELLECHEA — Mon, 14 Apr 2025 11:00:23 +0200

Structural health monitoring is essential to ensure safety and extend the service life of critical components in renewable energy systems, such as repaired wind turbine blades. This study presents the development of strain gauges printed using advanced functional printing techniques, optimized for integration into composite materials and tailored to the mechanical characteristics of repaired areas to assess the effectiveness and durability of structural repairs. The integration of these sensors would enable real-time monitoring of key parameters, such as microstrains, during the operation of the blade after repair. The experimental work included the printing of strain gauges, evaluation of different substrates, and cyclic loading tests under controlled conditions to assess the accuracy and sensitivity of the printed gauges. Additionally, composite material coupons were characterized under tensile and compressive loads to analyse the impact of gauge integration on the mechanical properties of the composite. Preliminary results demonstrate the feasibility of this approach, although full validation is required, including aging studies, testing in real operational environments, and exposure to extreme temperature variations prior to industrial implementation.

Mechanical behavior analysis at low temperature of flax/epoxy laminates

Gabriel Enrique Sánchez Escudero — Sun, 13 Apr 2025 11:49:34 +0200

The growing environmental consciousness of recent years has driven the composite materials industry to increasingly adopt natural fibers as a sustainable alternative to synthetic ones, aiming to reduce the ecological footprint of manufacturing processes. Replacing conventional synthetic fibers with natural counterparts, such as flax, offers a significant decrease in energy consumption during laminate production, enhancing overall process sustainability. This study explores the mechanical performance of a flax fiber-reinforced epoxy laminate with a twill weave configuration. The material was tested under tensile and in-plane shear loading at both room temperature and subzero conditions (–40 °C and –70 °C). The laminate demonstrated a nonlinear stress–strain response, characterized by three distinct regions, suggesting that a trilinear model may be appropriate for its numerical simulation. The influence of temperature on the mechanical behavior was assessed in both the longitudinal and transverse tensile directions, as well as in shear. Results reveal that lower temperatures lead to increased stiffness and strength, although differences between –40 °C and –70 °C were not substantial.

Analysis of Delamination Behavior in Mode I under Thermal Environment Exposure in Adhesive Joints of Carbon-Epoxy Composite Materials

Paula Vigón — Fri, 11 Apr 2025 19:25:45 +0200

This study analyzes the delamination behavior in mode I, under static and fatigue loading, in adhesive joints on a composite material with an epoxy matrix and unidirectional carbon fiber reinforcement (CFRP). The samples were exposed in a climate chamber at 60°C and 70% relative humidity for different periods (no exposure, 1, 2, and 4 weeks). Subsequently, standardized DCB tests were performed to evaluate the effect of environmental aging on interlaminar fracture toughness and adhesive strength. After an initial static characterization, reference parameters for fatigue tests were defined, obtaining initiation (ΔG–N) and crack growth (G–da/dN) curves. The initiation data were analyzed using a Weibull probabilistic model. The results show a change in the epoxy adhesive behavior with exposure time, evidenced by a reduction in the fatigue limit and an increase in crack propagation rates.

Experimental Evaluation of the Damping Factor in Laminated Composite Materials

Daniel Trias — Fri, 11 Apr 2025 18:56:56 +0200

The 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.

Manufacturing of new composites with a polypropylene matrix and latxa sheep wool reinforcement

Ander Larruscain — Fri, 11 Apr 2025 18:29:23 +0200

The development of new sustainable materials is key to meeting growing demand without compromising the planet’s future. To achieve this, it is essential to reduce environmental impact through strategies like those of the circular economy. One example is the use of Latxa sheep wool, a breed associated with Idiazabal cheese in the Basque Country. This wool has interesting physical, chemical, and mechanical properties, but currently lacks industrial applications. Therefore, it could be used as reinforcement in composite manufacturing, also supporting the local economy. In this study, polypropylene (PP) was used as the matrix—one of the most widely used thermoplastic polymers due to its versatility, good barrier properties, and chemical resistance. However, PP has few functional groups, which limits interaction with other materials. This may lead to poor adhesion at the fiber-matrix interface, affecting the cohesion and properties of the composite. To address this, composites of PP with Latxa wool fiber (PPWF) were prepared, analyzing the effect of modifying the PP with maleic anhydride (MAPP) to enhance compatibility between the matrix and the protein-based fiber. MAPP was added in a proportion of 10% relative to the wool fiber. The results show that adding 20% wool to the modified matrix significantly improves both the strength and modulus of the PP.

Effect of Environmental Degradation on the Fatigue Resistance of Mode II Adhesive Joints in Carbon/Epoxy Composite Materials

Paula Vigón — Fri, 11 Apr 2025 17:06:23 +0200

This study analyzes delamination in CFRP adhesive joints under mode II loading in both static and dynamic regimes. The ENF test was used to evaluate the effect of exposure to salt spray and a climatic chamber over various periods—one, two, four, and twelve weeks—as well as for unaged specimens. Based on the experimental data, fatigue initiation curves (ΔG-N) and fatigue crack growth curves (G-da/dN) were constructed to analyze both degradation processes. In the fatigue initiation phase, the data were analyzed using a probabilistic model based on a Weibull distribution. The most relevant findings of this study are as follows: regarding the fatigue limits obtained for the adhesive joint under mode II fracture, a decrease in load-bearing capacity was observed due to degradation processes—around 20% under static loading conditions for salt spray exposure, and 25% for hygrothermal degradation. As for the fatigue crack growth phase, the crack propagation rates were found to depend on the specific environmental degradation process to which the tested specimens were subjected.

Optimization of a car hood using natural fiber composite and 3D-printed PLA foam

Aritz Esnaola — Fri, 11 Apr 2025 15:23:13 +0200

Thanks to the wide range of available cores and skins, the design and manufacture of sandwich structures allows for many variations, but conventional manufacturing processes limit design freedom when it comes to geometries. In recent years, interest in sustainable materials, such as plant-based resins and natural fibres, has grown. Furthermore, recent advances in 3D printing have opened up new design possibilities, including the use of biodegradable foams and functionally graded structures. This study presents the development of a 1:6 scale car bonnet, where the skin is made of bio-epoxy resin reinforced with flax fibre and the core is a PLA foam produced via additive manufacturing. Two variants were considered: in the first, the core was distributed homogeneously across the entire bonnet surface, and in the second, it was distributed in areas selected through topological optimisation simulations. As both bonnets have the same mass, the density of the homogeneous bonnet had to be lower. This was achieved by programming different 3D printing parameters. Quasi-static load test results show that the bonnet with the optimised distribution is 25% stiffer. The study's main conclusion is that manufacturing cores using 3D-printed foamed PLA enables a wide range of densities and design possibilities that are not feasible with conventional materials and manufacturing processes.

Ballast Impact Damage Characterization. Determination of Acceptance/Rejection Criteria for Railway Components Made of CFRP.

Francisco José García Piñeiro — Fri, 11 Apr 2025 08:27:24 +0200

In recent years, the railway sector has been developing high-responsibility lighter components (such as the running gear frame), made from composites (mainly CFRP) to meet the new challenges of the sector. However, these components may be more sensitive to damage from impacts compared to conventional metallic ones. In high-speed train operations, elements located on the lower parts of the train are exposed to impacts with ballast stones that are lifted as the train passes (v > 200 km/h), leading to damage (sometimes internal and not visible) that can limit the use of these materials. During the development of CFRP components by Talgo, the damage caused by these types of low-velocity impacts has been analyzed and evaluated. These impacts can cause damage that requires more or less complex technologies (such as ultrasound) for evaluation, which are difficult to implement in maintenance operations. From the studies conducted on CFRP materials (compliant with the EN-45545 standard for fire, smoke, and toxicity), it has been found that acceptable approaches can be used, with easily implementable measures in routine inspections, to estimate the damage caused by ballast stone impacts. In these analyses, it was observed that: a) It is possible to estimate the impact energy level through the depth of the surface damage, b) it is possible to estimate the size of the internal damaged area based on the energy level, and c) it is possible to determine the residual strength based on the size of the internal damaged area. These results allow us to establish both acceptance requirements and criteria for the repair and rejection of materials

Functionally Graded Foamed PLA Cores for Optimized Vibratory Behavior in Sandwich Panels

Jon Rodriguez — Thu, 10 Apr 2025 11:40:34 +0200

Fused filament fabrication of foamed PLA enables lightweight structural parts with adjustable density and stiffness. This material expands during printing, making it ideal for functionally graded materials. It can serve as a sandwich core, enhancing lightweight properties. These panels can be a promising type of panel, as their behavior, such as vibracoustic, can be customized. However, their effectiveness in vibration attenuation remains unexplored. This study designs, manufactures, and tests 3D-printed foamed PLA sandwich panels with variable stiffness and density to improve vibroacoustic performance. The material’s Poisson’s ratio and elasticity modulus were characterized as a function of density, controlled by hot-end temperature and extrusion flow rate. A finite element model with spatially variable mechanical properties was developed for optimization. A genetic algorithm determined the optimal core properties to maximize the first two natural frequencies of a plate with one fixed edge and three free edges. The best designs were fabricated and tested, showing significant increment in the first two natural frequencies. This work advances the design and manufacturing of 3D-printed foamed PLA sandwich panels and contributes to high-performance, functionally graded components for enhanced vibroacoustic behavior.

Thermal and flame retardant properties of recyclable disulfide based epoxy vitrimers

Alaitz Rekondo — Thu, 10 Apr 2025 09:20:33 +0200

The development of flame-retardant epoxy vitrimers which are suitable for use as a composite matrix material is essential for the transition to a sustainable circular economy. In this work the thermal and flame-retardant properties as well as the rheological characteristics of epoxy vitrimers based on 4-Aminophenyldisulfide (4-AFD) hardener and with different reactive and additive Phosphorus based flame retardants (FR) with different oxidation states were studied. The use of 4-AFD as curing agent imparts vitrimeric properties to the material and allows repairing, reprocessing and recycling. A series of epoxy vitrimers (EV) were prepared aiming to improve the flame-retardant properties while maintaining dynamism and reprocessability. The neat EV (T_g ∼125 °C) showed a limited oxygen index (LOI) of 20.9 ± 0.4 %O₂ and no classification and heavy dripping in the UL-94 vertical burning test. With 1.5 wt% of Phosphorous (P) in the EV, LOI values up to 38.5 ± 0.4 %O₂ and V-0 classification with excellent self-extinguishing behavior was achieved. Especially gas phase active FRs with lower oxidation states showed better flame-retardant properties in the LOI and UL-94 vertical burning tests with identical phosphorus content. In cone calorimeter test the EVs with 1.5 wt% P reduced the peak heat release rate (PHRR) up to 43 %. The addition of reactive phosphorous-based FRs did not influence the dynamism and recyclability of the material in dynamic mechanical analysis. After mechanical recycling >73 % of the mechanical strength was recovered and the flame retardant EVs do reach as well a V-0 classification in the UL-94 vertical burning test.

Polymerization kinetics of a recyclable thermoplastic as a matrix for structural composites

Jordi Farjas — Tue, 08 Apr 2025 18:57:23 +0200

In this contribution we have performed the kinetic analysis of the curing process and of its thermal decomposition. Due to the presence of a peroxide initiator, polymerization is a complex process involving an induction period for a fast cross-linking reaction. From the kinetic analysis, we have been able to characterize the induction time and the degradation kinetics. Finally, from the analysis of the volatiles we have determine that the main volatile generated during decomposition is the monomer.

Ionic conductive bio-based composite aerogels

Miguel Sanchez-Soto — Sun, 06 Apr 2025 00:50:23 +0200

In the realm of energy transition, significant advancements are essential on the improvement of energy storage performance as well as in sustainability and safety. Aerogels are lightweight materials that can be endowed with mechanical strength, thermal insulation capability, and fire resistance. These characteristics make them promising for electrochemical devices such as composite polymer electrolytes (CPE). Silica-based aerogels have been used as scaffolds for solid polymer electrolytes (SPE). In these applications, the aerogel not only provides structural support but also creates additional conduction channels that improve ionic conductivity (IC). In this work, we present a bio-based aerogel composed of gelatin, montmorillonite clay, and tannic acid, synthesized using water as a solvent. By employing an ice templating strategy, we achieved a 1D pore orientation, which provides more direct conduction pathways. This aerogel exhibits an axially oriented honeycomb porous structure with high porosity (92.9 ± 0.1%) and low density (0.130 ± 0.002 g/cm³). It is also categorized as a self-extinguishing material. This aerogel was infiltrated with a SPE consisting of Polyethylene glycol (PEG) and Lithium bis (trifluoromethanesulfonyl) imide (LiTFSI). With partial pore coverage, we achieved IC at room temperature on the order of 2 × 10^-7 S/cm. This led to promising results, resulting in a porous (76%) ionic conductive aerogel that opens new perspectives. It enables the creation of a low-density solid electrolyte, which can increase the specific capacity of the final device. Alternatively, it can serve as an active, fire resistant, scaffold for a liquid or gel electrolyte, enhancing and maximizing IC.

Long-term performance of injection-molded isotactic polypropylene containing weld lines in unfilled and glass fiber-reinforced grades

Aitor Arriaga — Wed, 02 Apr 2025 10:06:44 +0200

The study of weld lines in polymers is far from settled, especially in predicting how materials perform over long periods under stress. While previous research has explored the behavior of isotactic polypropylene (iPP) in both its unfilled and glass fiber-reinforced forms, the focus has been largely on short-term behavior. However, this study shifts the lens to long-term performance under complex conditions, specifically looking at creep and fatigue. We take a novel approach by considering iPP with 30% glass fiber reinforcement, using tensile samples that induce weld line formation. Creep behavior is measured across a broad range of strain rates and temperatures, aiming to understand the underlying mechanisms that govern material failure. These short-term tests are then linked to more comprehensive long-term evaluations, including cyclic loading and creep-to-rupture tests. Crack growth is assessed using CT specimens, enabling us to capture failure modes that are otherwise difficult to quantify. The study goes further by proposing a new way to model deformation. Instead of relying on traditional methods, we turn to the Eyring equation for a more accurate prediction of failure times under cyclic stress, especially as materials transition to brittle fracture at higher temperatures. These predictions match experimental results, demonstrating the potential of linear elastic fracture mechanics (LEFM) in assessing long-term material performance. Ultimately, this research challenges conventional models and provides a pathway for more accurate long-term predictions, a crucial step for industries relying on polymer materials in demanding environments.

Buckling analysis of laminates subjected to biaxial loads using cruciform specimens

Maria del Carmen Serna Moreno — Fri, 28 Mar 2025 21:00:33 +0100

This study presents the compression-compression test with cruciform specimens (test CC) as a viable methodology to assess the geometric instability of a ∓45° symmetric laminate. The central region of the specimen, subjected to biaxial loading, exhibits a geometry similar to that of a square plate fixed along its entire perimeter. The bifurcation of the strains recorded at the top and bottom surfaces of the laminate is considered to be the threshold between the in-plane biaxial response and the response dominated by bending and torsional moments. The nonlinearities observed in the evolution of the stress-strain relationship in the region subjected to biaxial loading are confirmed to be independent of the response of the specimen arms. The bending-torsion coupling effects at the beginning of the bifurcation are observed experimentally in the deflection surface recorded by Digital Image Correlation. The results obtained suggest that the test CC is potentially suitable for the observation and measurement of buckling modes under various boundary conditions. However, more work is needed to reduce the quantitative dispersion. Specifically, the research should focus on minimizing geometric imperfections and load misalignments.

Combined Treatment of Korean Red Ginseng (Panax ginseng) and DHA Outperforms Either Treatment Alone Against Amyloid-Beta Neurotoxicity in a Caenorhabditis elegans Model of Alzheimer’s Disease

Nathalie Zhang — Thu, 20 Feb 2025 06:30:04 +0100

his study investigated the combined efficacy of docosahexaenoic acid (DHA) and Panax ginseng extract for treating Alzheimer's disease (AD). Single-target therapies aimed at clearing amyloid-beta (Aβ) have been largely unsuccessful, shifting attention toward multi-target approaches; among the most promising are DHA and Panax ginseng. Although DHA shows strong efficacy in AD prevention, once neurodegeneration has taken hold, blood-brain barrier (BBB) damage impairs its transport into the brain. Ginseng may counteract this by strengthening the BBB through the Wnt/β-catenin (BAR-1 ortholog in Caenorhabditis elegans) pathway and preventing DHA oxidation via its antioxidant properties, thereby enhancing delivery where it exerts neuroprotective effects. Based on these complementary mechanisms, the present study evaluated whether combined treatment confers benefits beyond either treatment alone using CL2355 (transgenic AD model) and N2 (wild-type) Caenorhabditis elegans. Five experimental groups were compared: two untreated controls (wild-type; AD model) and three AD model groups receiving DHA (5 mM), ginsenoside (10 μg/mL), or both. Treatment effects were assessed through paralysis (mobility), chemotaxis (neurological function), and population growth (reproduction) assays. The combined treatment reduced paralysis by 40% relative to untreated AD worms and 10% beyond either treatment alone, while significantly improving chemotactic function (p<0.01). These results suggest combined treatment holds potential as a multi-target therapeutic strategy, possibly by enhancing DHA absorption by the neurological system and/or targeting AD pathology through compounding mechanisms, though this study cannot distinguish between the two. These promising findings warrant further research using higher-order AD models or assays measuring nervous system DHA absorption.

Effects of nitrogen form on growth rate of the free-floating macrophyte Phyllanthus fluitans: Implications for nitrogen phytoremediation and invasive plant management

Nathalie Zhang — Tue, 11 Feb 2025 02:43:10 +0100

Phytoremediation is a promising method for mitigating nitrogen pollution due to its low cost and generation of biomass that can be repurposed. However, given the risk of plant invasion and the low tolerance to extreme conditions of plants currently used for phytoremediation, broad implementation requires the discovery of new species. This study assessed the phytoremediation suitability and invasive potential of Phyllanthus fluitans, a promising free-floating macrophyte for which no peer-reviewed physiological data exist. P. fluitans is morphologically similar to Lemna minor, the most widely used phytoremediation species, but has the added benefit of larger fronds that reduce wind-driven displacement risk. Plants were placed in 0.002M solutions of ammonium-to-nitrate ratios ranging from 0:1 to 1:0 across two independent trials. Plants receiving solely nitrate exhibited drastically higher fresh weight (p<0.05), dry weight, leaf count (p<0.05), root length, and survival rate compared to all other groups. Ammonium dose-dependently increased mortality, causing toxicity symptoms like chlorosis, necrosis, and stunted growth, resulting in complete die-off in the sole ammonium group. Additionally, the reduction of a mineral supplement between trials revealed P. fluitans to be highly sensitive to elevated water hardness. Collectively, nitrate preference and poor resilience render P. fluitans a poor phytoremediation candidate. However, under optimal conditions, the species can more than double its biomass in 24 days. This indicates that the invasive potential of P. fluitans varies drastically depending on environmental conditions, a finding that environmentalists can use to make condition-specific risk assessments and manage invasions accordingly.

The Effects of Energy Efficient Behavior Reminders on Electricity Conservation in a New York Public High School

Amanda Chen — Mon, 10 Jun 2024 21:03:03 +0200

Excessive electricity consumption negatively affects the economic growth of developing countries, and is a major cause of carbon emissions throughout the globe. This experiment investigated how the use of energy efficient behavior reminder affects electricity conservation in a New York City Public High School. In this experiment, during the first 10 days of the experiment, custodians were not reminded to turn off lights. From Day 11-20, reminders were sent to custodians every Monday and Fridays to turn off the light. During Day 21-30, reminders were sent everyday to remind custodians to turn off the lights. The results showed daily reminders had a significant decrease in electricity consumption compared to when no reminders were sent, but there was no significant difference between the percentage of lights being on, making it difficult to confirm if the custodians followed the reminders. The reminder of turning off lights was not a major source of electricity consumption and other factors might have consumed a larger portion of electricity.. More schools should be studied in order to validate the results. Future studies/research can test the effects of energy saving behavior reminders on electricity conservation from turning off electronic devices, such as smart boards or computers, at the end of the day.

REPAIRING OF STEEL STRUCTURES BY COMPOSITE PATCHES ACTING AS A CRACK ARRESTORS

Lourdes Blanco Salgado — Sun, 01 May 2022 19:58:52 +0200

Today’s merchant and passenger vessels are complex structures that operate in harsh environments with respect to static and cyclic loads and corrosion. Depleting funds for fleet renewal and increasing through-life cost of maintenance and repair are the principal factors that lead to the need to implement new solutions that are easy to apply and low cost. All this added to the growing need for lightening in the transport sector turn the FRP materials into the main candidates as drivers for this change.

This present study within RAMSSES is focused on the compare a damage steel structures to repair composite patches. A representative structural detail of a cruise vessel was selected and designed as a demo case. The best patch solution was selected by FEM calculations, which have been fed from the mechanical test results of the composite material combinations, steel, surface treatments and adhesion joint of the one-shot dissimilar joints without adhesive.

Fatigue tests have been carried out and monitoring by strain gauges and FBGs positioning and distribution in the high stress areas along the demonstrator. Fatigue tests have been carried out in the six demos to compare crack evolution in cracked Patched and Un-Patched demonstrators.

As conclusion after the fatigue tests, composite patch works as crack arrested. Therefore, this behaviour represents an improvement of the 2.6 times of the fatigue life comparing UnPatched and Patched damaged steel.

Performance-Based Optimization of Reinforced Ductile Concrete Frames with Asymmetric Reinforcement in Columns, using the ISR analogy

Luis Fernando Verduzco Martínez — Sun, 05 Sep 2021 20:43:03 +0200

The present work exposes the design of optimization procedures both with the “Particle Swarm Optimization” (PSO) algorithm and the “Genetic Algorithm” (GA) for the design of reinforced concrete frames, making comparisons in cost, weight of the structure and predicted damage. The optimization procedures are built up using the “Idealized Smeared Reinforcement” (ISR) analogy for each element of the structural model frames considered for this work. Two different numerical structural plane-frame models were created for the application and comparison of the performance of the optimization design procedures hereby proposed. The optimization procedures were mono-objective with a cost-objective function, taking on account steel reinforcement and concrete for the cost computation. Two different design approaches were carried on for this work, one proposing asymmetrical reinforcement for columns and the other with symmetrical reinforcement. In order to compute the damage indices considered for this study a non-linear Pushover structural analysis is performed. Results show that asymmetrical reinforcement in columns may reduce concrete volumes, although such reduction in material might not be quite proportional with construction cost, given that asymmetric reinforcement in columns is more expensive than symmetrical, per unit-cost. The bigger the structure, the more likely is to obtain lighter structures by using asymmetrical reinforcement. Regarding damage of the structure, results show that when using asymmetrical reinforcement in columns, it is more likely to obtain smaller values for the expected damage with no great difference on the estimated collapse Safety Factors for the seismic loads. In general, the proposed methodology hereby proposed enhances quite good optima results, requiring only a few adjustments of clash-free and slap reinforcement after the optimization procedure terminates. When designing reinforced concrete frames with asymmetric reinforcement in columns, an increase in construction costs of as much as $25\%$ as that obtained for symmetric reinforcement could be enhanced. In general, with the proposed methodology to optimally design reinforced concrete frames, savings of as much as $20\%$ in construction costs from an initial structural proposal can be reached.