Search Results (2,041)

This study presents a calibration-oriented multi-phase micromechanical homogenization framework for estimating the elastic modulus of sustainable concrete containing fly ash and recycled gypsum. In the absence of direct experimental measurements, a computational framework was developed to simulate the interactions among coarse aggregate, mortar, and the interfacial transition zone (ITZ). A two-phase homogenization model was first calibrated against the ACI 318-19 elastic modulus relationship through a sensitivity analysis, achieving relative errors below 3% with respect to the ACI-based empirical reference. Subsequently, a three-phase model incorporating a $30\mathsf{\mu }\mathrm{m}$ ITZ was developed to explicitly account for the influence of the interfacial transition zone on the effective elastic modulus within the adopted modelling assumptions. While the inclusion of the ITZ slightly increased the prediction error for the control mix, it consistently improved agreement with the ACI-based reference for all fly ash–gypsum blends. In addition, comparison with experimentally reported elastic modulus values for similar SCM-modified concretes demonstrated that the predicted values were physically reasonable and generally consistent with published data. Overall, the proposed framework reproduced stiffness trends predicted by the ACI empirical relationship and provides a physically informed computational baseline for future experimental validation and parametric investigations of sustainable concrete systems. Full article

In this study, laser powder bed fusion (PBF-LB) 022Cr17Ni12Mo2 steel plates with dimensions of 50 mm × 50 mm × 2 mm were fabricated using a laser power of 206 W, a scanning speed of 900 mm/s, a hatch spacing of 90 μm, a layer thickness of 30 μm, and an interlayer scanning rotation of 67°. The specimens were then subjected to solution treatment at 900–1100 °C for 30 min and at 950 °C for 30–120 min. Unlike previous ultrasonic studies on additively manufactured metals, which mainly focused on defect detection, elastic-constant characterization, or residual stress evaluation, this work investigates whether solution-treatment-induced changes in grain size and dislocation density can be quantitatively reflected by laser-ultrasonic attenuation and further correlated with yield strength. Laser ultrasonic nondestructive testing using a 1064 nm pulsed laser with a pulse width of 8 ns and a pulse energy of 500 mJ was combined with metallographic observation, EBSD characterization, XRD analysis, tensile testing, and microhardness measurement. The results show that the solution-treated samples retained a single-phase γ-austenitic structure, while microstructural recovery, weakening of PBF-LB-induced cellular substructures, and partial annihilation of cell-wall dislocations led to a reduction in KAM-derived dislocation density from 2.04 × 10¹⁴ m⁻² to 1.45 × 10¹⁴ m⁻² and a decrease in yield strength from 466.9 MPa to 407.4 MPa. Within the present dataset, the EBSD-equivalent grain size showed an apparent positive correlation with ultrasonic attenuation, while the KAM-derived dislocation density showed an empirical negative correlation with ultrasonic attenuation. However, ultrasonic attenuation should be interpreted as a combined microstructure-sensitive response rather than as a response controlled only by EBSD-equivalent grain size or dislocation density. Based on the empirical correlations among ultrasonic attenuation, EBSD-equivalent grain size, KAM-derived dislocation density, and yield strength, a preliminary attenuation-based calibration model was established for the present solution-treated samples. The model should be regarded as an in-sample empirical calibration within the present experimental range rather than a general Hall–Petch-based predictive model. The model showed good in-sample fitting performance, with (R²) values higher than 0.85 and a maximum in-sample fitting error of 3.85%. However, because the model was established and assessed using the same eight solution-treatment conditions, it should be regarded as a preliminary calibration model within the present experimental range rather than a general predictive model. This study demonstrates the potential of laser ultrasonic attenuation for non-contact evaluation of microstructural and mechanical-property variations in solution-treated PBF-LB 022Cr17Ni12Mo2 steel. Full article

Background: Handgrip strength has been proposed as an objective marker of post-COVID functional impairment, but its contribution relative to fatigue and sleep quality has not been formally evaluated in Latin American populations. Methods: We conducted an exploratory cross-sectional analysis of 130 adults with post-COVID condition in Palmira, Colombia. The outcome was any functional limitation on the Post-COVID Functional Status (PCFS) scale (grades 1–4 versus grade 0). Eight predictors were pre-specified on clinical grounds before examining outcome associations, and ridge-penalized logistic regression was pre-specified as the primary model. Sample size adequacy followed the criteria of Riley et al. Internal validation used bootstrap optimism correction (B = 1000), re-running the complete pipeline within each replicate. We assessed calibration, decision curves, prediction stability, SHapley Additive exPlanations (SHAP) with bootstrap rank intervals, and subgroup performance. Reporting followed TRIPOD + AI; risk of bias was self-assessed with PROBAST + AI. Results: Functional limitation affected 91/130 participants (70.0%). The minimum sample required for eight parameters was 566; the cohort met 23.0% of this requirement, so the analysis is exploratory. The optimism-corrected area under the curve was 0.748 (95% confidence interval (CI) 0.669–0.830), with calibration slope 1.15 (0.71–1.69). Fatigue ranked first in SHAP importance (54.0% of resamples), whereas grip strength ranked fifth (median rank 6). Net benefit exceeded both default strategies between thresholds 0.38 and 0.88. Thirty percent of participants changed classification in over 20% of resamples. Conclusions: Fatigue, sleep quality and acute-phase severity, rather than grip strength, emerged as the most influential correlates. These hypothesis-generating findings require confirmation in adequately powered cohorts. Full article

The slow evolution and inconspicuous nature of buffer-layer ablation in high-voltage cables pose a significant challenge for early fault diagnosis. To tackle this issue, we propose a hybrid diagnostic approach that integrates frequency-domain impedance measurement with a convolutional neural network (CNN). A cable simulation model is first established using transmission-line theory and a distributed-parameter framework. We examine the impedance and phase responses at the cable’s sending end, revealing a consistent decreasing trend with rising frequency alongside periodic resonant peaks. The simulator generates a diverse set of spectral signatures corresponding to various cable health states. The CNN then extracts discriminative features from these waveforms, and a probabilistic clustering preprocessing step further refines the input data. Experimental results on a test set of 78 samples—comprising 52 experimentally measured normal spectra and 26 experimentally calibrated simulated spectra for mild and severe ablation—demonstrate a classification accuracy of 0.95, confirming that the proposed methodology enables reliable, non-intrusive detection of buffer-layer ablation without cable disassembly. Full article

Surface recession can underestimate laser-induced damage in 2.5D C/SiC composites because thermochemical degradation extends beneath the visible pit. Infrared thermography and micro-CT data from six laser conditions (400–1600 W·cm⁻², 3–12 s), together with SEM/EDS observations, were reanalysed using a layered phase-selective model tracking C, SiC and SiO₂ evolution. For the four conditions with resolvable damage, the internal degradation front lay 0.84–1.07 mm below the recession surface. At 800 W·cm⁻², the 0.02 mm difference between the 6 and 12 s front depths was below the 25 μm voxel size and within specimen uncertainty. The calibrated model matched rear-centre peak temperatures with a mean absolute percentage error of 4.37%, although larger transient discrepancies remained. Temperatures sampled at the measured front coordinates ranged from 2890 to 3080 K. Relative to 800 W·cm⁻² for 12 s, the 1600 W·cm⁻², 6 s condition caused greater near-surface SiC consumption and solid-mass loss, while the maximum retained SiO₂ density decreased from approximately 360 to 180 kg·m⁻³. These results distinguish geometric recession from internal degradation and support experimental-front mapping and mechanistic interpretation. The mapped states are condition-specific and do not constitute an independently predicted front criterion. Full article

Conventional pinhole point-diffraction interferometers (PPDIs) owe their popularity to a simple configuration, but that same configuration limits both the usable measurement aperture and the load the phase shifter can carry. Here, we propose a heterodyne phase-shifting point-diffraction interferometer (HPDI) based on dual-cascaded acousto-optic modulators (AOMs), which removes both limitations while keeping the configuration compact. The dual-cascaded AOM module integrates the functions of frequency shifting, beam splitting, and contrast modulation. By modulating its input RF power, the interference contrast can be flexibly adjusted. Simulation and experimental results verify the feasibility of the proposed HPDI, which achieves a measurement repeatability of 0.045 nm (RMS, with piston, tilt, and defocus removed) and agrees with an absolute shift-rotation calibration to within 3.3 nm (RMS). Full article

Dissimilar resistance spot welding of Al-Si-coated B1500HS hot-stamped steel to HC340/590DP dual-phase steel suffers from a narrow process window and HAZ temper softening. A sequential orthogonal-central composite design strategy screened factors and constructed local second-order models for nugget diameter and tensile-shear force. Because the complete tensile-shear CCD dataset is unavailable for independent verification, the tensile-shear model is used strictly as an auxiliary local calibration and is not assigned the same validation level as the nugget-diameter model. Within-batch ANOVA showed that electrode force dominated diameter variation and first-pulse current dominated force variation. A model-assisted variance-aware compromise (7.8/8.5 kA, 2.9 kN, 13/17 cycles) was point-wise validated at 6.5065 ± 0.1366 mm and 15.053 ± 0.1899 kN (n = 20, CV 2.10%/1.26%). The measured performance-optimal orthogonal condition remained Run 11; thus, the compromise is interpreted as a stability-oriented choice rather than a global optimum. A joint-specific HAZ screening envelope (width < 0.7 mm; hardness loss < 50%) is proposed as a descriptive screening criterion only; because HAZ width and microhardness were not measured for the n = 20 validation condition, the envelope was not validated on that condition and remains conditional on the single-factor HAZ data. The framework integrates process optimization with transparent statistical qualification and reports its model calibration limits. Full article

Classical approaches often treat interaction as engineered product terms or as emergent patterns in flexible models, offering little control over how synergy or antagonism arises. We take a quantum-inspired view: following the Born rule (probability as squared amplitude), coherent aggregation sums complex amplitudes before squaring, creating an interference cross-term, whereas an incoherent proxy sums squared magnitudes and removes it. Representing input contributions as complex amplitudes, the relative phase between amplitudes modulates the sign and magnitude of this cross-term, providing a mechanism-level account of synergy versus antagonism. In a minimal amplitude-linear model over a $2\times 2$ design—the simplest setting for feature interaction—this cross-term equals the standard interaction contrast ${\Delta }_{\mathrm{INT}}$, which can be interpreted as the potential-outcome interaction measure under randomized assignment. We instantiate this idea in a lightweight Interference Kernel Classifier (IKC) and introduce two diagnostics: Coherent Gain (log-likelihood gain of coherent aggregation over the incoherent proxy) and Interference Information (the induced Kullback–Leibler gap). A controlled phase sweep recovers this identity. On a high-interaction synthetic task (XOR), IKC attains predictive performance closely matching that of the evaluated classical baselines under paired, budget-matched comparisons; on real tabular data, its competitiveness is dataset-dependent, trailing the best evaluated baseline on Adult while outperforming it on Bank Marketing. In coherent–incoherent ablations with learned parameters held fixed, removing the coherent cross-terms degrades negative log-likelihood, Brier score, and expected calibration error on both datasets, with positive Coherent Gain. This quantum-inspired approach offers an interpretable mechanism for modeling and diagnosing feature interactions in probabilistic classification. Full article

Limited snapshots and element-wise gain–phase mismatch jointly impair covariance estimation and array manifold accuracy in uniform planar arrays. This paper proposes a deep robust adaptive beamforming framework that combines statistical base-weight generation, element-wise array manifold calibration, and regularized response projection. The base-weight network extracts finite-snapshot covariance information, whereas the calibration network estimates a physically bounded element-wise complex-gain vector from covariance features and nominal direction context. Phase-aligned auxiliary supervision makes the calibration loss invariant to the unidentifiable common phase and is required only during training. The calibrated steering vectors define a closed-form minimum-distance projection that preserves the normalized base weight’s desired direction response while suppressing the calibrated interference responses. Across three training seeds, the method achieves 23.43 ± 0.06 dB output SINR and a −52.48 ± 0.09 dB average null level, improving the former by 5.64 dB and deepening the latter by 5.11 dB relative to the best-performing baseline under the main test distribution. Experiments on mismatch severity, input SNR, snapshot number, direction-of-arrival errors, controlled ablations, and computational cost characterize the performance and limitations of the method under the stated synthetic-array model. Full article

The rapid advancement of unmanned aerial vehicle (UAV) technology has introduced increasingly severe airspace security challenges. As a critical component of counter-UAV systems, the direction-finding (DF) accuracy of airborne warning systems directly affects threat assessment and response efficiency. This paper addresses the problem of limited DF accuracy in airborne environments by proposing a direction-finding method that integrates attitude self-calibration with real-time signal-to-noise ratio (SNR) estimation. Based on the monopulse amplitude–phase comparison angle-measurement principle, the proposed method dynamically corrects the angle-discrimination curve using real-time SNR information and adaptively calibrates azimuth information by incorporating UAV attitude data. Simulation and experimental results demonstrate that the proposed method significantly reduces angle-measurement errors under low-SNR conditions, and attitude calibration further improves DF accuracy across the full angular range. Field experiments indicate that, after attitude calibration, the angle-measurement error is less than $2^{\circ }$ in over $77\%$ of the test points. Full article

Gold in the coarse-grained alluvial sediments of the Irgaity placer deposit (Kazakhstan) occurs predominantly as finely dispersed particles associated with mineral matrices, which limits the efficiency of conventional recovery methods. The proposed processing flowsheet demonstrated that thermal pre-treatment is an effective approach for enhancing ultrafine gold recovery, achieving an overall recovery of 86% from the treated concentrate. The Tescan TIMA “Bright Phase Search” workflow, optimized for gold detection by applying a minimum BSE brightness threshold of 75% and an Au phase filter calibrated using a gold standard, successfully identified gold-bearing grains within the analyzed mounts. Further mineralogical investigations revealed that gold particles ≤10 μm occur as native gold and Au-Ag-As-bearing phases, with silver content reaching up to 14 wt.% in some coarser grains. The significant association of silver with gold-bearing particles indicates the potential for incorporating silver recovery into the processing flowsheet, thereby improving the overall economic value of the deposit. Despite the low average gold grade (0.3–0.4 g/t), the large dimensions of the Irgaity placer deposit (approximately 12 km long, 1.5 km wide, and 60–70 m thick) suggest the presence of a substantial large-volume mineral resource. The combination of extensive mineralized sediments and high recovery achieved through thermal activation supports the potential economic viability of the deposit and warrants further evaluation of its development potential. Full article

Wireless sensing networks increasingly extend into obstacle-prone deployments, where physical blockage degrades reliability and open propagation exposes transmission activity. Intelligent reflecting surfaces (IRSs) establish programmable paths around obstacles while passive elements remain constrained by severe cascaded attenuation. To address the tradeoff between reliability and covertness, we propose an unmanned aerial vehicle (UAV) -assisted active-IRS architecture under probabilistic line-of-sight and non-line-of-sight propagation conditions that accounts for direct leakage from the transmitter to the warden together with residual jammer cancellation and always-on IRS circuit noise under a finite output power budget. Furthermore, bidirectional Kullback–Leibler analysis identifies the reverse divergence as the tighter restriction and converts the covertness requirement into conservative gain bounds under warden location uncertainty and relative phase uncertainty conditions between the direct and aggregate reflected fields. Subsequently, closed-form phase control for calibrated equal-gain elements and gain monotonicity reduce the joint design to an exhaustive search over the prescribed placement grid. The numerical results demonstrate a SINR advantage over passive reflection and single-element relaying across the evaluated settings. The finite-array and hardware analyses show that gain back-off enforces a prescribed covert-outage limit while direct leakage and residual self-interference remain explicitly controlled. Overall, the framework provides a transparent basis for reliable covert sensing through UAV-assisted active reflection. Full article

The degradation formed during the gas-phase reaction of amyl acetate, CH₃COO(CH₂)₄CH₃, initiated by chlorine atoms (^●Cl), was investigated under atmospheric conditions using gas chromatography–mass spectrometry. The main products identified were acetic acid, formaldehyde, acetaldehyde, butyraldehyde, and propionaldehyde. Calibration curves were established for each identified product at different concentrations to enable their quantification by gas chromatography coupled with flame ionization detection. Product yields were subsequently determined from the calibration data, allowing a quantitative evaluation of the formation of the major oxidation products. The results obtained contribute to a better understanding of the atmospheric degradation pathways of amyl acetate and related ester compounds, providing useful information for assessing the atmospheric processing of ester-containing emissions, including those associated with biofuel applications. Full article

This paper presents the development of a multi-domain simulation for the Porsche Taycan’s all-wheel-drive (AWD) electric propulsion system to investigate the impact of the rear drive unit’s two-speed transmission on performance and drive quality during maximum acceleration. This study was undertaken independent of the vehicle and propulsion system OEM. A lumped-parameter model of the front and rear electric drive units (EDU) and the high-voltage battery was developed and calibrated against the published data for key benchmarks, including 0–100 kph acceleration times and peak longitudinal acceleration. The mechanical shifting mechanism was reverse-engineered to simulate high-performance shift trajectories. To manage the transition, a clutch control scheme integrates a reduced-order clutch-to-clutch model featuring a feedforward (FF) torque estimator and a closed-loop feedback (FB) controller to achieve target input shaft speeds and shift durations. The study concludes with a comprehensive analysis of the propulsion system’s behavior at a battery state of charge of 96% and 25% and three electric motor speeds at which the upshift is commanded. The simulation results demonstrate that executing an early upshift at 10,700 rpm with 96% of SOC yields a 0.100-s inertia phase shift time, restricts the clutch thermal dissipation to 21 kJ, and achieves an 8-s velocity of 203.4 kph, outperforming the upshift at 15,300 rpm (0.210 s, 34 kJ, and 202.8 kph). Furthermore, the transient regenerative braking on the rear axle during the inertia phase reduces the peak current draw from 675 A to 87 A, recovering the DC bus voltage to enable cross-axle torque boosting on the front axle. Full article

Manufacturing errors introduce phase deviations in Mach–Zehnder interferometers (MZIs) that degrade the fidelity of optical processors. To address this issue, we employ a Broyden–Fletcher–Goldfarb–Shanno (BFGS) quasi-Newton method for phase calibration of a $4\times 4$ reconfigurable MZI optical processor based on the Reck architecture. By optimizing the mapping from the target matrix to the optical network, the method determines the optimized phase parameters of 12 phase shifters. Thermo-optic simulations are further used to establish the relationship between the applied bias voltage and the induced phase shift, providing a link between the optimized phase parameters and the electrical driving conditions. Compared with Particle Swarm Optimization (PSO), Genetic Algorithms (GA), and Gradient Descent with Momentum (GDM), the BFGS method provides faster convergence and high calibration fidelity. These results demonstrate an efficient approach for phase calibration of programmable MZI optical processors. Full article