Search Results (29,962)

Thin-film thermocouples (TFTCs) offer conformal sensing junctions with minimal thermal mass, enabling rapid transient response and direct deposition on curved or moving components, which are difficult to achieve using conventional wire thermocouples in applications such as high-speed machining, electric powertrain thermal management, and fuel-cell monitoring. In practical deployment, the effective accuracy of a TFTC can also be affected by the measurement setup used for calibration and testing, particularly lead-wire material transitions, cold-junction compensation, and wiring-related thermoelectric offsets. This study presents a systematic static calibration and performance evaluation of NiCr-based TFTCs under standardised laboratory conditions, with repeated measurements across the 20–260 °C range using both copper leads and matched compensation wires. The thermoelectric output exhibits excellent linearity; temperature reconstruction against a traceable standard reference yields a maximum deviation of approximately 0.27 °C, with root-mean-square and relative errors within tight bounds. Short-term extended-range verification up to 1000 °C confirms detectable thermoelectric signal generation under the present test conditions. A calibration data packet framework containing the calibrated TFTC sample, wiring configuration, calibration coefficients, validity range, and a GUM-compliant uncertainty budget is proposed to support consistent interpretation of calibration results in future digital integration. The study therefore provides a structured calibration workflow and uncertainty-reporting basis for the tested flexible NiCr-based TFTC configurations, supporting further reliability assessment, material-level characterisation, and digital integration. Full article

To investigate the impact of underground multiple stress disturbances on the long-term stability of cemented tailings backfill (CTB), this study conducted experiments under different disturbance levels (20–80% of static strength) and frequencies (1–4 times). By comprehensively utilizing mechanical testing, wave velocity monitoring, digital image correlation (DIC), and scanning electron microscopy (SEM), the “heterogeneous” evolution mechanism of macro-micro damage was revealed. The results indicate that disturbance level and frequency exert distinctly different driving effects on the deterioration of CTB, rather than a simple linear superposition. Specifically, low-frequency disturbance produces a compaction strengthening effect, microscopically promoting the generation of Ca(OH)₂ and ettringite (increased Ca/Si ratio). In contrast, the combination of high disturbance and high frequency induces free water extrusion and inhibits hydration, leading to an advanced damage threshold based on energy evolution and the accelerated coalescence of microcracks, which favors the formation of C-S-H gel (decreased Ca/Si ratio). Within this heterogeneous mechanism, the disturbance level acts as the dominant controlling factor. This study clarifies the nonlinear mechanical and chemical evolution paths under composite disturbances, providing theoretical support for the dynamic stability control of backfill in deep multi-step mining. Full article

A novel sodium-oxide-fluxed slag is applied in the aluminothermic reduction of manganese ore. The slag’s high Al₂O₃ solubility facilitates the recycling of Al₂O₃ through hydrometallurgical processes, where NaAlO₂ serves as a water-leachable compound. Aluminothermic reduction is gaining renewed interest as an alternative processing route for the circular economy. In addition, CO₂ emissions in aluminium production via the electrochemical Hall–Héroult process can be reduced if the process electricity is sourced from non-fossil fuels. The unique Na₂O-fluxed MnO₂ ore formulation includes a small quantity of carbon reductant to ensure rapid pre-reduction to MnO. This approach negates the need for a pre-roasting step. Feed mixture variations with different collector metal additions (Si, Cr, Cu) were made to improve alloy–slag separation efficiency. The collector metals may influence the chemistry of the slag. This work compares the phase chemistry of slags formed during aluminothermic reduction to equilibrium phase chemistries calculated for the Na₂O-SiO₂-Al₂O₃-MnO-CaO system. The slag phase morphology consists of distinct alumina-rich strands (1.5% to 2.1%) embedded within a Na₂O-SiO₂-Al₂O₃-MnO-CaO glass matrix. The alumina-rich strands appear molten, indicating that the processing temperatures were higher than their liquidus temperatures (1537 °C to 1655 °C), as high as 1921 °C and 2053 °C. These findings contribute to sustainable practices in the circular economy through the production of low-carbon ferro-manganese complex alloys. Full article

This study presents a material-level characterization of recycled aluminum briquettes produced by cold pressing Al–Si–Mg machining chips and investigates their behavior during subsequent remelting. The study evaluates density, porosity, chemical composition, and metallurgical yield before and after remelting, with the aim of assessing material-related prerequisites for potential metallurgical reuse applications. The cold-pressed briquette (Sample A) exhibited a bulk density of 2.29 g·cm⁻³ and an estimated porosity of 14.6%, attributed mainly to intergranular voids and residual surface contaminants. After melting and resolidification (Sample B), the density increased to 2.388 g·cm⁻³, while the estimated porosity decreased to 10.9%. Handheld ED-XRF analysis indicated no substantial compositional variation within the instrumental uncertainty range after remelting. SEM–EDS observations revealed Al-rich surface regions containing minor oxygen contributions associated with naturally formed surface oxides, while no pronounced intermetallic features were observed at the analyzed surface locations. The remelting process achieved a metallurgical yield of 94.2% with low dross generation. The results indicate that appropriately preprocessed and compacted aluminum machining chips can form mechanically stable briquettes with favorable remelting characteristics and potential applicability in secondary metallurgical processing. However, the present study does not evaluate deoxidation efficiency under molten steel conditions, which remains a subject for future investigation. Full article

Carbon nanotube (CNT)-reinforced composites are promising advanced materials due to their exceptional mechanical properties. This paper presents a comprehensive investigation of the mechanical behavior of CNT/epoxy composites through theoretical modeling and experimental validation. An equivalent cylindrical fiber model was developed to transform CNTs into effective reinforcement phases, enabling the application of classical composite mechanics. Three reinforcement configurations were analyzed: two unidirectional short fiber models (aligned and staggered) and a three-dimensional four-directional braided long-fiber model. The effects of geometric parameters, including the diameter-to-thickness ratio (D/t) and fiber aspect ratio, on the effective elastic moduli were systematically evaluated. Static and dynamic compression experiments were conducted using an MTS 810 testing system and a Split Hopkinson Pressure Bar (SHPB) to examine the influence of loading rate, vacuum treatment, and reinforcement type (CNT, SiC, and hybrid SiC/CNT) on composite strength. The results indicated that 3 wt% CNT reinforcement increases the Young’s modulus by 30% under static loading and enhanced the dynamic compressive strength under impact loading. The vacuum degassing process significantly affected composite quality, with insufficient vacuum leading to strength degradation due to void formation. Theoretical predictions using Mori–Tanaka and dilute methods showed good agreement with experimental results at low reinforcement volume fractions. Scanning electron microscopy revealed uniform CNT dispersion and provided insights into failure mechanisms, including CNT pull-out and breakage. This work contributes to the understanding of structure–property relationships in CNT-reinforced polymer composites and provides guidelines for achieving their optimal design. Full article

Surge reliability is a crucial aspect of silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET) reliability. This study investigates the degradation behavior and mechanisms of switching characteristics in 1.2 kV planar-gate SiC MOSFETs under repetitive surge current. A surge current test platform is established to conduct surge tests on the device, while monitoring the evolution of its switching characteristics. The results indicate that after 4000 surge current cycles, the device’s turn-on delay time (t_d(on)), rise time (t_r), and turn-on loss (E_ON) show no significant changes. In contrast, the turn-off delay time (t_d(off)), fall time (t_f), and turn-off loss (E_OFF) increase by 9%, 7.5%, and 8.3%, respectively. Switching characteristics variations are closely linked to the reduction in threshold voltage (V_TH) and the increase in gate-source capacitance (C_GS) and gate-drain capacitance (C_GD). The degradation of these parameters stems from the accumulation of positive trapped charge in the gate oxide layer above the channel and junction field-effect transistor (JFET) region. The increase in charges results from the combined effects of negative gate bias and cyclic high temperature induced by repetitive surge current. This study provides a theoretical basis for the comprehensive understanding of the impact of surge current on SiC MOSFET performance. Full article

This study investigated the effect of MoS₂/graphite lubricant composition on the high-temperature compaction behavior, local mechanical uniformity, and microstructural characteristics of Fe–5.0 wt.%Si SMCs. Nine lubricant compositions were prepared by varying MoS₂ and graphite contents, and their friction behavior, Vickers hardness, and compaction behavior were evaluated experimentally and by FEA. One-way ANOVA confirmed that lubricant composition significantly affected the Vickers hardness response (F = 4.245, p = 0.000273). The measured friction coefficients were applied as interface friction conditions in FEA, and the relative density, effective strain, and absolute hydrostatic stress distributions were compared. Among the investigated compositions, C3, containing 1.0 wt.% MoS₂ and 0.3 wt.% graphite, showed the lowest friction coefficient and Vickers hardness standard deviation. In FEA, C3 also showed balanced relative density, effective strain, and hydrostatic stress distributions. XRD confirmed the α-Fe-based bcc Fe–Si matrix, while SEM-EDS indicated locally distributed lubricant-derived residual regions. Therefore, C3 was selected as the most balanced lubricant composition within the investigated range. Future studies will evaluate electromagnetic properties, including core loss and magnetic permeability. Full article

Silicone rubber is an important external insulating material for composite bushings, composite insulators, and other power equipment. During long-term service, it is inevitably exposed to coupled environmental and electrical stresses, such as elevated temperature, moisture ingress, strong electric fields, and partial discharge, which may lead to hydrophobicity loss, surface chalking, crack propagation, and particle shedding. To reveal the microscopic degradation mechanism of silicone rubber under complex operating conditions, a molecular model of methyl vinyl silicone rubber was constructed using Materials Studio. A stable silicone rubber molecular structure was obtained through crosslinking, geometry optimization, and ensemble relaxation. Subsequently, a reactive molecular dynamics simulation system under coupled temperature–humidity–electric field conditions was established using LAMMPS and the ReaxFF reactive force field. Different temperature gradients, electric field intensities, and aging–recovery stages were designed to investigate the degradation behavior of silicone rubber. The evolution of the maximum carbon content, maximum silicon content, carbon-containing decomposition products, and typical small-molecule products, including H₂, H₂O, CH₄, C₂H₂, C₂H₄, and C₂H₆, was statistically analyzed. In addition, atomic trajectory tracking was performed to clarify the processes of methyl group detachment, Si-O bond cleavage, water molecule participation, and molecular chain reconstruction. The results show that high temperature mainly promotes methyl group detachment from side chains and fracture of the siloxane main chain, while a strong electric field accelerates the decomposition process and induces the transformation of long siloxane chains into shorter chains. Water molecules can react with broken siloxane chains to form hydroxyl-containing structures, making the structural degradation partially irreversible. The degradation process of silicone rubber under coupled temperature–humidity–electric field stress can be summarized as side-chain detachment, main-chain scission, water-assisted reactions, free-radical recombination, and local molecular aggregation. This study provides a molecular-level theoretical basis for aging mechanism analysis, condition assessment, and lifetime prediction of composite external insulating materials. Full article

To tackle the environmental challenges associated with industrial oily wastewater discharges and recurrent marine oil spill incidents, developing high-efficiency oil–water separation technologies represents a pressing environmental challenge. This research presents a novel design approach comprising the deposition of a stable SiO₂ anchoring layer followed by the fabrication of a PDA/CS crosslinked coating, thereby achieving successful construction of a superhydrophilic/underwater superoleophobic (SH/UWSO) coating on stainless steel meshes (SSM). In the first step, SiO₂ microspheres were deposited via vapor deposition to create a micro-rough surface architecture. Subsequently, a dopamine/chitosan (DA/CS) reaction solution was introduced to form a Polydopamine/chitosan (PDA/CS) coating, yielding a SiO₂@PDA/CS-SSM separation membrane. The resulting membrane exhibited separation efficiencies surpassing 99% for various oil–water mixtures, achieving a flux of 1.24 × 10⁵ L·m⁻²·h⁻¹ in petroleum ether systems. Notably, the membrane maintained high efficiency and structural stability even after 25 separation cycles, immersion in strong acid and base solutions for 72 h, and 100 abrasion tests. The rational design of the anchoring and crosslinking layers endows SiO₂@PDA/CS-SSM with high efficiency and stability, making it an effective oil–water separation material. Full article

Soil quality assessment, which considers numerous physical, chemical, and biological indicators, has long been a challenge for monitoring soil functions and ensuring sustainable resource use in agriculture. In this study, different indicator selection and weighting methods were compared to derive a reliable Soil Quality Index (SQI) in semi-arid agroecosystems. A total of 117 topsoil samples were taken from the Ap horizon within a 14,200 ha area of the Honam sub-catchment, southwestern Iran. Twenty-one soil indicators were measured and analyzed to assess the overall SQI. Soil indicator selection was performed using Principal Component Analysis (PCA), considering standard and norm value strategies, as well as component rotation. Four weighting approaches, including PCA, Coefficient of Variation (CV), correlation score (r), and Expert Opinion (EO), were applied to the Minimum Dataset (MDS) and Total Dataset (TDS) to compute the Integrated Quality Index (IQI), Nemoro (NQI), simple additive (IQIa), and Fuzzy Fertility Index (FFI). The performance of the SQI models was evaluated using the Sensitivity Index (SI) and their relationships with crop yield. The results showed that the combination of the norm value approach without component rotation was more effective in selecting the influential indicators for SQI determination. The Soil Stability Index (SSI), which integrates soil organic carbon and textural properties, was the key indicator with the highest contribution, ranging between 6.3% and 37.5% in most of the models. Among the evaluated approaches, the IQI-CV-MDS showed the highest sensitivity (SI = 6.8) and the strongest correlation (r = 0.53) with rainfed barley yield. The majority of the samples exhibited moderate SQI values, indicating a general risk of soil quality decline in the study area. The findings of this study highlight that appropriate indicator selection and weighting strategies are essential for improving the reliability of SQI assessments in semi-arid environments with diverse mountainous topography. Full article

We report, for the first time, a continuous-wave (CW) switchable multi-wavelength Nd:Lu₂SiO₅ (Nd:LSO) laser using two wedge birefringent filters (WBFs) operating on the ⁴F_3/2 → ⁴I_13/2 transition. The threshold equivalence condition was calculated via the two intracavity WBFs to achieve the simultaneous multiple-wavelength operation. Three dual-wavelength pairs (1332/1344 nm, 1344/1359 nm, and 1359/1363 nm), two triple-wavelength combinations (1332/1344/1359 nm and 1344/1359/1363 nm), and a four-wavelength set (1332/1344/1359/1363 nm) were further experimentally demonstrated. These wavelength combinations are mutually switchable via tuning of the WBF. Under an incident pump power of 20 W at 808 nm, the total output powers for the dual-wavelength pairs (1332/1344 nm, 1344/1359 nm, and 1359/1363 nm) were measured to be 1.55 W, 2.17 W, and 3.40 W, respectively. The triple-wavelength outputs at 1332/1344/1359 nm and 1344/1359/1363 nm delivered 1.57 W and 1.91 W, respectively. The four-wavelength emission at 1332/1344/1359/1363 nm reached 913 mW. Full article

Technological advances in hardware and software have enabled the development of novel in situ plankton imaging systems to investigate the spatial and temporal distribution of plankton communities. State-of-the-art machine learning approaches have been applied for automated image classification, effectively handling the complex and highly variable morphology of plankton while maintaining high accuracy. Despite these advances, few instruments can acquire zooplankton images autonomously in a continuous underway mode, which is essential for large-scale oceanographic surveys conducted aboard research vessels or ships of opportunity. Here, we present SiMFlux, an underway shadowgraphic imaging system developed at the University of São Paulo, and report results from the Orient Expedition. Observations were conducted aboard an 80-foot sailing vessel navigating across the Indian and Atlantic Oceans. A total of 193 videos were analyzed from daily route segments, yielding over 1.2 million regions of interest (ROIs) containing organisms and detrital particles. Particles were automatically classified and subsequently validated by plankton experts. Full article

Fine-paste earthenware held symbolic significance in Hindu and Buddhist rituals and domestic use in Southeast Asia. Despite the influx of Chinese glazed ceramics from the ninth century onward, these locally produced vessels continued to circulate widely until the fourteenth century along maritime trade routes extending from northern Sumatra and Java to the southern Philippines and the Thai–Malay Peninsula. Integrated petrographic, Field Emission Scanning Electron Microscopy (FESEM), and Energy Dispersive X-ray Spectroscopy (EDS) analyses were employed to compare fine-paste earthenware from the Kok Moh production center in Songkhla Province, Thailand, and the Kota Cina consumption site in northern Sumatra, Indonesia. Petrographic observations indicate broadly similar mineralogical compositions in samples from both sites, consistent with the use of kaolin-rich clay materials. FESEM reveals that Kok Moh samples exhibit relatively dense and homogeneous microstructures with more continuous matrices, whereas Kota Cina specimens display coarser textures, more distinct mineral inclusions, and less consolidated matrices. EDS elemental mapping further demonstrates a more uniform distribution of major elements in the Kok Moh samples. Although both groups share broadly similar silica–alumina compositions, the observed microstructural differences suggest variations in clay preparation and firing practices rather than major differences in raw material selection. Comparison with published data from Nakhon Si Thammarat supports an association with kaolin-rich clay resources in southern Thailand. In contrast, the examined ceramics differ from fine-paste wares reported from northeastern Thailand, Myanmar, and India. These findings suggest that maritime Southeast Asian fine-paste ware developed as a localized technological tradition shaped by regional resources, production practices, and maritime exchange networks. Full article

Luminescent gadolinium oxide nanoparticles doped with europium were synthesized through a precipitation reaction using gadolinium and europium nitrates as precursors. The europium-doped gadolinium oxide nanoparticles were incorporated first into a gel matrix of silicon dioxide and second by mixing with polymethyl methacrylate. Both processes are synthesized by the simultaneous hydrolysis of tetraethyl orthosilicate and polymerization of 3-(Trimethoxysilyl) propyl methacrylate. The solid samples obtained are round in shape with a size of about 2.5 cm, which makes the material easy to handle to test different applications. The inclusion of Gd₂O₃:Eu³⁺ nanoparticles increases the level of absorbance in the ultraviolet region, which allows for the improved emission of the material at a wavelength of around 610 nm. Furthermore, it enables easy doping of the material and the fabrication of thin films and monoliths with potential optical applications. Full article

Wireless power transfer (WPT) systems for electric vehicles (EVs) are increasingly being studied in the MHz range to increase power density and reduce the size of passive components. However, operation at higher frequencies significantly changes electromagnetic interference (EMI) behaavior. Fast switching in SiC- and GaN-based inverters, high-Q resonant operation, and frequency-dependent parasitic capacitances create conductive, capacitive, and magnetic interference mechanisms that are less significant in conventional kHz-range systems. Although many existing studies focus on power-transfer efficiency and converter optimization, EMI mechanisms in MHz-range EV WPT systems remain insufficiently systematized from a system-level electromagnetic perspective. This paper presents a state-of-the-art review of EMI generation mechanisms and system-level effects in high-frequency WPT systems for electric vehicles. The review considers the main interference sources and coupling paths, including switching-induced common-mode currents, resonant amplification of current and voltage stress, capacitive coupling between the coupler and nearby conductive structures, and magnetic-field redistribution caused by coil misalignment. Special attention is given to the transition from lumped-element assumptions to more distributed electromagnetic behavior at higher frequencies. The review also discusses the possible impact of these mechanisms on vehicle electronic subsystems and highlights the need for frequency-aware electromagnetic design, integrated modeling, and more rigorous EMC assessment for reliable MHz-range wireless EV charging systems. Full article