Search Results (211)

Accurate photovoltaic (PV) panel characterization is critical for optimizing renewable energy systems, but it is often hindered by the high cost of commercial tracers or the slow, error-prone nature of manual methods. This paper presents a low-cost, Arduino-based I–V curve tracer that overcomes these limitations through fully automated resistive load switching. By integrating a relay-controlled resistor bank managed by a single microcontroller, the system eliminates the need for manual intervention, enabling rapid and repeatable measurements in just 45 s. This rapid acquisition is a key advantage over manual systems, as it minimizes the impact of fluctuating environmental conditions and ensures the resulting I–V curve represents a stable operating point. Compared to commercial alternatives, our open-source solution offers significant benefits in cost, portability, and flexibility, making it ideal for field deployment. The system’s use of fixed, stable resistive loads for each measurement point also ensures high repeatability and straightforward comparison with theoretical models. Experimental validation demonstrated high agreement with a single-diode PV model, achieving a mean absolute percentage error (MAPE) of 4.40% against the manufacturer’s data. Furthermore, re-optimizing the model with field-acquired data reduces the MAPE from 18.23% to 7.06% under variable irradiance. This work provides an accessible, robust, and efficient tool for PV characterization, democratizing access for research, education, and field diagnostics. Full article

Blasting is one of the most widely used and cost-effective techniques for rock excavation and fragmentation in open-pit mining, particularly for large-scale operations. However, repeated or poorly controlled blasting can generate excessive ground vibrations that threaten slope stability by causing structural damage, fracturing of the rock mass, and potential failure. Evaluating the effects of blast-induced vibrations is essential to ensure safe and sustainable mining operations. This study investigates the impact of blasting-induced vibrations on slope stability at the Saindak Copper-Gold Open-Pit Mine in Pakistan. A comprehensive dataset was compiled, including field-monitored ground vibration measurements—specifically peak particle velocity (PPV) and key blast design parameters such as spacing (S), burden (B), stemming length (SL), maximum charge per delay (MCPD), and distance from the blast point (D). Geomechanical properties of slope-forming rock units were validated through laboratory testing. Slope stability was analyzed using pseudo-static limit equilibrium methods (LEMs) based on the Mohr–Coulomb failure criterion, employing four approaches: Fellenius, Janbu, Bishop, and Spencer. Pearson and Spearman correlation analyses quantified the influence of blasting parameters on slope behavior, and sensitivity analysis determined the cumulative distribution of slope failure and dynamic response under increasing seismic loads. FoS values were calculated for both east and west pit slopes under static and dynamic conditions. Among all methods, Spencer consistently yielded the highest FoS values. Under static conditions, FoS was 1.502 for the east slope and 1.254 for the west. Under dynamic loading, FoS declined to 1.308 and 1.102, reductions of 12.9% and 11.3%, respectively, as calculated using the Spencer method. The east slope exhibited greater stability due to its gentler angle. Correlation analysis revealed that burden had a significant negative impact (r = −0.81) on stability. Sensitivity analysis showed that stability deteriorates notably when PPV exceeds 10.9 mm/s. Although daily blasting did not critically compromise stability, the west slope showed greater vulnerability, underscoring the need for stricter control of blasting energy to mitigate vibration-induced instability and promote long-term operational sustainability. Full article

In this study, a new fibre combination for an interlayer hybrid fibre-reinforced polymer laminate was investigated to achieve pseudo-ductile behaviour in tensile tests. The chosen high-strain fibre for this purpose was S-Glass, and the low-strain fibre was flax. These materials were chosen because of their relatively low environmental impact compared to carbon/carbon and carbon/glass hybrids. An analytical model was used to find an ideal combination of the two materials. With that model, the expected stress–strain relation could also be predicted analytically. The modelling was based on preliminary tensile tests of the two basic components investigated in this research: unidirectional laminates reinforced with either flax fibres or S-Glass fibres. Hybrid specimens were then designed, produced in a heat-assisted pressing process, and subjected to tensile tests. The strain measurement was performed using distributed fibre optic sensing. Ultimately, it was possible to obtain repeatable pseudo-ductile stress–strain behaviour with the chosen hybrid when the specimens were subjected to quasi-static uniaxial tension in the direction of the fibres. The intended damage-mode, consisting of a controlled delamination at the flax-fibre/glass-fibre interface after the flax fibres failed, followed by a load transfer to the glass fibre layers, was successfully achieved. The pseudo-ductile strain averaged 0.52% with a standard deviation of 0.09%, and the average load reserve after delamination was 145.5 MPa with a standard deviation of 48.5 MPa. The integrated fibre optic sensors allowed us to monitor and verify the damage process with increasing strain and load. Finally, the analytical model was compared to the measurements and was partially modified by neglecting the Weibull strength distribution of the high-strain material. Full article

Steel lazy wave risers (SLWRs) are critical in offshore hydrocarbon transport for linking subsea wells to floating production facilities in deep-water environments. The incorporation of buoyancy modules reduces curvature-induced stress concentrations in the touchdown zone (TDZ); however, extended operational exposure under cyclic environmental and operational loads results in repeated seabed contact. This repeated interaction modifies the seabed soil over time, gradually forming a trench and altering the riser configuration, which significantly impacts stress patterns and contributes to fatigue degradation. Accurately reconstructing the riser’s evolving profile in the TDZ is essential for reliable fatigue life estimation and structural integrity evaluation. This study proposes a simulation-based framework for the autonomous tracking of SLWRs using a fin-actuated autonomous underwater vehicle (AUV) equipped with a monocular camera and multibeam echosounder. By fusing visual and acoustic data, the system continuously estimates the AUV’s relative position concerning the riser. A dedicated image processing pipeline, comprising bilateral filtering, edge detection, Hough transform, and K-means clustering, facilitates the extraction of the riser’s centerline and measures its displacement from nearby objects and seabed variations. The framework was developed and validated in the underwater unmanned vehicle (UUV) Simulator, a high-fidelity underwater robotics and pipeline inspection environment. Simulated scenarios included the riser’s dynamic lateral and vertical oscillations, in which the system demonstrated robust performance in capturing complex three-dimensional trajectories. The resulting riser profiles can be integrated into numerical models incorporating riser–soil interaction and non-linear hysteretic behavior, ultimately enhancing fatigue prediction accuracy and informing long-term infrastructure maintenance strategies. Full article

This study investigates the potential of low-density polymeric materials to enhance the deformation energy absorption of drone fuselage components manufactured using fused filament fabrication (FFF). Two materials—PLA (polylactic acid) and LW-PLA (lightweight polylactic acid)—were selected based on their accessibility, printability, and prior mechanical characterizations. While PLA is widely used in additive manufacturing, its brittleness limits its suitability for components subjected to accidental or impact loads. In contrast, LW-PLA exhibits greater ductility and energy absorption, making it a promising alternative where weight reduction is critical and structural redundancy is available. To evaluate the structural efficiency, a simplified analysis scenario was developed using a theoretical 300 J collision energy, not as a design condition, but as a comparative benchmark for assessing the performance of various metastructural configurations. The experimental results demonstrate that a stiffening core of the LW-PLA metastructure can reduce the component weight by over 60% while maintaining or improving the deformation energy absorption. Modified prototypes with hybrid internal structures demonstrated stable performances under repeated loading; however, the tests also revealed a buckling-like failure of the internal core in specific configurations, highlighting the need for core stabilization within metastructures to ensure reliable energy dissipation. Full article

A narrow coal pillar in double-roadway excavation can solve the problem of working face connection and improve the resource recovery rate, but narrow coal pillars are affected by the full mining stress. Taking the 2109 double-roadway excavation of Qingwa Coal Mine as the engineering background, the roof mechanical structure model of a narrow coal pillar in a double-roadway excavation layout was established, and the bearing characteristics of different coal pillar widths under the influence of full dynamic pressure were studied. The narrow coal pillar retention width was obtained and tested through field industrial experiments. The main research results were as follows: (1) The relationship between the coal pillar bearing load and the immediate roof length was deduced, and the bearing stress of the coal pillar was divided into the steep decline stage, the transition stage, and the stabilization stage. The coal pillar within the width of the stabilization stage has a certain strength surplus capacity. (2) Under the influence of full dynamic pressure, the 5~7 m coal pillar yielded to failure, and the coal pillar of 8 m and above had a certain residual bearing capacity, compared with the first mining. After the second mining, the elastic zone in the coal pillar of each width was significantly reduced; there was no elastic grid in the coal pillar of 5 m and 6 m in width, and the grid area and proportion of the elastic zone of the coal pillars with widths of 7 m and above were very low. The optimal retention width of the narrow coal pillar was determined to be 8 m. (3) Under the influence of repeated mining, the impact of first mining on the roadway displacement of the roof and floor plate was greater, followed by the solid coal side, which had less impact on the coal pillar side. The secondary mining had a greater impact on the floor, followed by the coal pillar side and the solid coal side, which had little impact on the roadway roof. This paper also provides a significant reference for the retention of narrow coal pillars in double-roadway excavation. Full article

Alongside the general growth in gaming and esports, competitive simulated (sim) racing has specifically surged in popularity in recent years, leading to an increased demand for understanding performance. In recent work, braking-related metrics were identified among the key indicators of successful sim racing performance. While load cell sensors currently serve as the industry standard for brake hardware, sensors like the Hall sensor may provide another viable option. No study to date has compared the performance of these braking sensors. The aim of this study was to investigate whether sim racing performance differed when racing using a load cell or Hall brake sensor. Twenty (N = 20) experienced sim racers raced with both the load cell and Hall brake sensors (with load cell behaviour mimicked on the Hall sensor) in a repeated measures design. Paired samples t-tests, Wilcoxon-signed rank tests, and chi-square goodness-of-fit tests were used to test for differences in lap time, driving behaviour metrics, and subjective responses between the two sensors. Results showed that participants achieved faster lap times using the load cell brake sensor (average lap time (p = 0.071); fastest lap time (p = 0.052)) and displayed braking behaviour more aligned with that of a “faster racer”. The differences observed may be potentially attributed to differences in in-game response curves between two brake sensors, which specifically may impact both the initial, and trail braking, phases. Full article

The accurate modeling of dynamic soil–structure interaction processes under impact loading is critical for advancing the design of soil-embedded barrier systems. Full-scale crash testing remains the benchmark for evaluating barrier performance; however, such tests are costly, logistically demanding, and subject to variability that limits repeatability. Recent advancements in computational methods, particularly the development of large-deformation numerical schemes, such as the multi-material arbitrary Lagrangian–Eulerian (MM-ALE) and smoothed particle hydrodynamics (SPH) approaches, offer viable alternatives for simulating soil behavior under impact loading. These methods have enabled a more realistic representation of granular soil dynamics, particularly that of the Manual for Assessing Safety Hardware (MASH) strong soil, a well-graded gravelly soil commonly used in crash testing of soil-embedded barriers and safety features. This soil exhibits complex mechanical responses governed by inter-particle friction, dilatancy, confining pressure, and moisture content. Nonetheless, the predictive fidelity of these simulations is governed by the selection and implementation of soil constitutive models, which must capture the nonlinear, dilatant, and pressure-sensitive behavior of granular materials under high strain rate loading. This review critically examines the theoretical foundations and practical applications of a range of soil constitutive models embedded in the LS-DYNA hydrocode, including elastic, elastoplastic, elasto-viscoplastic, and multi-yield surface formulations. Emphasis is placed on the unique behaviors of MASH strong soil, such as confining-pressure dependence, limited elastic range, and strong dilatancy, which must be accurately represented to model the soil’s transition between solid-like and fluid-like states during impact loading. This paper addresses existing gaps in the literature by offering a structured basis for selecting and evaluating constitutive models in simulations of high-energy vehicular impact events involving soil–structure systems. This framework supports researchers working to improve the numerical analysis of impact-induced responses in soil-embedded structural systems. Full article

The structural reliability of bottom-fixed offshore wind turbines is generally influenced by the dispersion of and variability in soil properties, which affect their ultimate capacity, serviceability, and both the short- and long-term fatigue. During an earthquake, the soil–pile system is subjected to intense cyclic loads that can lead to stiffness and strength degradation, typically captured through cyclic soil models. Calibration of soil parameter variability is fundamental for reliable structural assessments of wind turbine integrity. In this study, a method to generate randomness of the parameters affecting cyclic soil degradation models is proposed. Fatigue parameters are quantified through random cyclic undrained triaxial tests conducted using the Discrete Element Method. Deterministic simulations are first performed based on experimental results from the Liquefaction Experiments and Analysis Project for validation. Subsequently, variability in the initial particle size distribution functions is introduced to generate random soil samples, and triaxial simulations are repeated to quantify the dispersion of soil fatigue parameters. The proposed procedure is then applied through Monte Carlo simulations on the IEA 15-MW reference wind turbine, which is subjected to both short- and long-duration earthquakes. The results demonstrate the significant impact of soil degradation on the bending moment envelope, as well as the effect of soil uncertainty on tower fatigue, assessed using the damage equivalent load approach. Full article

Background/Objectives: Effective drug delivery systems require precise formulation and understanding of excipient impact on active pharmaceutical ingredient (API) stability and efficacy, as uncontrolled interactions can compromise outcomes. This study developed and validated a semi-solid extrusion (SSE) 3D printing method for polyvinyl alcohol (PVA)-based hydrogel disks with metronidazole (MET). These disks served as a standardized platform to assess excipient influence on MET’s antimicrobial activity, focusing on plasticizers (polyethylene glycol 400, glycerol, propylene glycol, and diethylene glycol monoethyl ether)—excipients that modify hydrogel properties for their application in printing dressing matrices—with the platform’s capabilities demonstrated using in vitro antimicrobial susceptibility testing against Bacteroides fragilis. Methods: Hydrogel inks based on PVA with added plasticizers and MET were prepared. These inks were used to 3D-print standardized disks. The MET content in the disks was precisely determined. The antimicrobial activity of all formulation variants was evaluated using the disk diffusion method against B. fragilis. Results: The incorporated plasticizers did not negatively affect the antimicrobial efficacy of MET against B. fragilis. All printed hydrogel matrices exhibited clear antimicrobial activity. The 3D-printed disks showed high repeatability and precision regarding MET content. Conclusions: SSE 3D printing is viable for manufacturing precise, reproducible MET-loaded PVA hydrogel disks. It provides a standardized platform to evaluate diverse excipient impacts, like plasticizers, on API antimicrobial performance. The tested plasticizers were compatible with MET. This platform aids rational formulation design and screening for optimal excipients in designed formulations and for various pharmaceutical applications. Full article

The optimal selection of conductors (OCS) in radial distribution networks is a critical aspect of system planning, directly impacting both investment costs and energy losses. This paper proposed a mixed-integer convex (MI-Convex) optimization framework to solve the OCS problem under balanced operating conditions, integrating the costs of conductor investment and energy losses into a single convex objective. This formulation leveraged second-order conic constraints and was solved using a combination of branch-and-bound and interior-point methods. Numerical validations on standard 27-, 33-, and 85-bus test systems confirmed the effectiveness of the proposal. In the 27-bus grid, the MI-Convex approach achieved a total cost of $550,680.25, outperforming or matching the best results reported by state-of-the-art metaheuristic algorithms, including the vortex search algorithm (VSA), Newton’s metaheuristic algorithm (NMA), the generalized normal distribution optimizer (GNDO), and the tabu search algorithm (TSA). The MI-Convex method demonstrated consistent and repeatable results, in contrast to the variability observed in heuristic techniques. Further analyses considering three-period and daily load profiles led to cost reductions of up to 27.6%, and incorporating distributed renewable generation into the 85-bus system achieved a total cost of $705,197.06—approximately 22.97% lower than under peak-load planning. Moreover, the methodology proved computationally efficient, requiring only 1.84 s for the 27-bus and 12.27 s for the peak scenario of the 85-bus. These results demonstrate the superiority of the MI-Convex approach in achieving globally optimal, reproducible, and computationally tractable solutions for cost-effective conductor selection. Full article

Unlike conventional asphalt pavements, steel bridge deck pavement (SBDP) is directly constructed on orthotropic steel deck plates characterized by relatively low flexural stiffness, rendering it more susceptible to rutting deformation under elevated temperatures and repeated loading. To investigate the mesoscopic mechanism underlying rutting formation in SBDP, a three-dimensional (3D) discrete–continuous coupled model of a steel–asphalt composite structural specimen (SACSS) was developed and employed to conduct virtual rutting simulations, which were subsequently validated against laboratory test results. The impact of surface cracking on rutting progression was then explored. In addition, the spatial motion and contact interactions of particles during the rutting process were monitored and analyzed. The influence of steel plate stiffness on the rutting resistance of SBDP was also evaluated. The numerical analyses yielded the following key findings: (1) Under three steel–asphalt interface bonding (SAIB) failure conditions (0%, 17%, and 100%), the virtual simulation results exhibited strong agreement with experimental trends in rutting depth over time, thereby confirming the validity and reliability of the coupled modeling approach. (2) At 30 °C, the presence of surface cracks is found to increase the rutting depth by 35.77%, whereas this effect is mitigated at 45 °C. (3) The meso-mechanical mechanisms governing rutting deformation in SBDP are further elucidated under different temperature conditions. (4) Moreover, at elevated temperatures, the use of a steel plate with an elastic modulus of 206 MPa effectively inhibit rutting development. This study offers mesoscopic-level insights into the effects of temperature, SAIB conditions, steel plate stiffness, and surface cracking on the macroscopic rutting behavior of SBDP, thereby providing a theoretical foundation for the design and optimization of long-lasting SBDPs. Full article

Background: Wettability of dental implant surfaces is a key factor in the osteointegration process. This study aimed to evaluate the effect of a new hydrophilic surface on implant stability in posterior maxilla rehabilitations. Materials and Methods: A 6-month, single-center, parallel-group clinical trial following STROBE guidelines was reported. Implant Stability Quotient (ISQ) changes were compared between implants with a moderately rough surface (MultiNeO CS, Alpha-Bio Tec, Israel, Control Group–CG) and those with the same surface and, in addition, nano-scale roughness and hydrophilic properties (MultiNeO NH CS, Alpha-Bio Tec, Israel, Test Group–TG) placed using a crestal sinus lift technique. ISQ values at bucco-lingual (ISQBL) and mesio-distal (ISQMD) sides were measured at insertion (t0), 4 months (t4), and 6 months (t6). Repeated measures ANOVA (RMA) was performed for statistical evaluation. Results: The study included 35 participants (18 TG, 17 CG). Mean ISQBL0 was 69.45 (SD = 12.62), increasing to 71.72 (SD = 6.74) at t4 and 75.21 (SD = 4) at t6. ISQMD0 mean was 67.54 (SD = 12.54), rising to 72.32 (SD = 6.90) at t4 and 75.67 (SD = 4.60) at t6. No statistically significant differences were found between groups, though TG showed a significant increase in ISQBL at t6 vs. t4 and ISQMD at t6 vs. t0. One-way ANOVA revealed no significant variations between mean ISQ differences over time. Conclusion: Both groups exhibited an increasing ISQ trend, but no significant differences were observed between t4–t0 and t6–t4 periods. Further research is required to assess the impact of hydrophilia on early loading, osteointegration, and long-term outcomes. Full article

In integrated turbine wheel designs, small deviations, known as mistuning, often occur in the modal properties of individual blades due to manufacturing tolerances and material inhomogeneity. During operation, this mistuning can cause some rotor blades to be subjected to significantly higher loads than predicted for an ideal rotor. The degree of rotor mistuning can only be determined using methods of experimental modal analysis. However, the manual use of the modal hammer cannot ensure precise repeatability of the force impulse’s location and timing, leading to inaccuracies. This article introduces a mechanism that replaces manual modal hammer operations, guaranteeing consistent impact location and timing while eliminating double strikes. The device was verified on bladed discs of various sizes, and its usability is demonstrated in this article on a turbine wheel of a marine engine turbocharger. The developed mechanism automates modal hammer strikes, ensuring precisely repeatable force courses and positioning for each impact. This automation reduces the measurement time and significantly improves the accuracy. The results of this research showed that even with careful manual operation of the modal hammer by an experienced operator, statistically significant differences arise in the repeated measurements of a bladed disc mistuning, whereas with the use of the presented measuring device, the results of the repeated measurements are practically identical. Full article

In renewable energy generation, uncertainties mainly refer to power output fluctuations caused by the intermittency, variability, and forecasting errors of wind and photovoltaic power. These uncertainties have adverse effects on the secure operation of the power systems. Probabilistic load supply capability (LSC) serves as an effective perspective for evaluating power system security under uncertainties. Therefore, this paper studies the influence of renewable energy generation on probabilistic LSC to quantify the impact of these uncertainties on the secure operation of the power systems. Global sensitivity analysis (GSA) is introduced for the first time into probabilistic LSC evaluation. It can quantify the impact of renewable energy generation on the system’s LSC and rank the importance of renewable energy power stations based on GSA indices. GSA necessitates multiple rounds of probabilistic LSC evaluation, which is computationally intensive. To address it, this paper introduces a novel probabilistic repeated power flow (PRPF) algorithm, which employs a basis-adaptive sparse polynomial chaos expansion (BASPCE) model as a surrogate model for the original repeated power flow model, thereby accelerating the probabilistic LSC evaluation. Finally, the effectiveness of the proposed methods is verified through case studies on the IEEE 39-bus system. This study provides a practical approach for analyzing the impact of renewable generation uncertainties on power system security, contributing to more informed planning and operational decisions. Full article