Search Results (7,797)

The transition process from synchronous condenser pump (SCP) mode to pumping mode determines the response rapidity of the startup procedure and operational stability of pump-turbines; however, the complex gas–liquid interaction and transient hydraulic characteristics during this process remain insufficiently understood. To address this, this study develops a numerical framework for the SCP-to-pumping transition process, incorporating the full-passage system, a multiscale mesh strategy for coupling mainstream and clearance flow regions, and a gas–liquid two-phase flow model based on the Volume of Fluid (VOF) method. The reliability of the numerical model is verified through comparison with model experiments, demonstrating good agreement between simulations and experimental data. Based on the validated model, the transient evolution of hydraulic forces, pressure pulsations, and internal flow structures is systematically analyzed. Axial force analysis reveals a significant internal equilibrium; the crown bears a maximum instantaneous fluctuation of approximately 2800 kN. Conversely, the radial force is primarily dominated by blade hydraulic thrust (1294 kN), showing distinct anisotropic behavior. The runner blade channels and the upper draft tube region are identified as critical areas with intense pressure fluctuations, with peak-to-peak pressure amplitudes reaching 45~48 m and 54 m head, respectively. Furthermore, reducing the duration of the exhaust process constitutes the main strategy for accelerating the transition and mitigating prolonged high-amplitude force and pressure fluctuations. The findings provide new insights into the transient hydraulic mechanisms of SCP-to-pumping transitions and offer guidance for optimizing transition control strategies in pumped-storage units. Full article

Ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) are physically complementary non-destructive evaluation methods for reinforced concrete, yet their integrated diagnostic use has been limited by the absence of controlled, ground-truth-validated calibration of the joint-signature space. This paper presents a laboratory calibration programme in which a single C30/37 reinforced concrete beam (3000 mm × 300 mm × 200 mm, three T12 bars at 35 mm cover, CEM I 42.5N, w/c = 0.50) was sequentially conditioned through four controlled deterioration states—intact reference (Model A), water-filled saw-cut crack (Model B), full saturation by seven-day top-surface ponding (Model C), and chloride-induced active corrosion (Model D). Seven RES2DINV inverted ERT sections at three electrode spacings (a = 7, 15, and 30 mm) and three 800 MHz GPR profiles were acquired across the four known ground-truth conditions. The intact-reference resistivity ρ₀ = 558 Ω·m (full-section median of the mlab dataset at a = 7 mm) and GPR-calibrated velocity v = 0.095 ± 0.008 m/ns (from hyperbola fitting at 35 mm rebar cover) establish the absolute baselines. The four conditions produce systematically distinct joint signatures: Model A exhibits uniform high resistivity with clean rebar hyperbolae and no anomalous reflections; Model B produces a localised ERT low-ρ anomaly (ρ_min = 1.46 Ω·m) co-located with a negative-polarity (R = −0.68) GPR crack-mouth reflection confirming water-fill; Model C produces pervasive low-ρ with a smooth depth gradient and 50–65% GPR amplitude attenuation (−6.0 to −9.1 dB); Model D produces the same bulk GPR signatures as Model C but with a critically different ERT spatial texture—a heterogeneous near-surface layer above a sharp boundary at z ≈ 40 mm with depth-preferential low-ρ concentrated at rebar level. This depth-preferential signature, quantified here by a reproducible Depth-Preferential Index (DPI), is the primary ERT-only diagnostic criterion distinguishing active corrosion from pervasive saturation. For the Model C versus Model D distinction, the GPR response is non-discriminating; this high-risk distinction is resolved exclusively by the ERT depth-preferential criterion. The calibration demonstrates that GPR and ERT are physically non-redundant in the strict sense: neither method alone can unambiguously discriminate all four states, but their combination yields correct classification within the controlled laboratory conditions and subject to the stated qualification conditions. The corrosion state was confirmed at the regime level (chloride above the depassivation threshold, under accelerated polarisation) but was not quantified electrochemically, so the depth-preferential signature is interpreted as an indirect spatial proxy for active corrosion rather than a measurement of corrosion rate. Seven failure modes are quantitatively characterised and embedded in the framework as a priori qualification conditions. The calibrated reference values (ρ₀, A₀, Stage 2 thresholds, depth-preferential criterion) are specific to the laboratory mix and curing history and require local Stage 1 recalibration for field application. Full article

This study assessed the cross-modal agreement between spin-exchange relaxation-free magnetoencephalography (SERF-MEG) and conventional visual evoked potentials (VEPs) in patients with optic nerve injury using comparable pattern-reversal visual stimulation paradigms. Forty-five patients with optic neuritis (ON), ischemic optic neuropathy (ION), and traumatic optic neuropathy (TON) were enrolled, and a paired-eye design was applied to assess interocular electrophysiological changes between the affected and fellow eyes. Both modalities indicated consistent impairment of visual pathway function, reflected by reduced response amplitudes and prolonged latencies. For latency measures, MEG-derived M100 showed moderate directional concordance and a significant correlation with VEP P100, whereas amplitude measures demonstrated similar directional changes but limited quantitative correlations across modalities. Compared with the MaxP2P method, the channel-averaged method displayed higher stability and cross-modal concordance. These findings show that SERF-MEG can capture clinically relevant visual pathway impairment and may complement conventional VEP by providing additional information on cortical response patterns. Overall, SERF-MEG shows potential as an objective functional biomarker for neuro-ophthalmic assessment of optic nerve injury. Full article

This paper presents a constrained robust procedure for synthesizing fixed positive input shapers for a trolley–pendulum crane that accounts for motor dynamics, actuator lag, and PD trajectory tracking. Rope length L and payload mass m are treated as uncertain parameters within a prescribed operating domain, while remaining constant during each maneuver. The method searches offline for a single impulse sequence that can be used across the entire (L,m) domain without online retuning. The impulse amplitudes and delays are obtained from a linearized closed-loop electromechanical model. Mean and worst-case peak payload sway are evaluated during synthesis, while residual RMS sway, terminal-position error, peak motor current, and peak actuator voltage are imposed as feasibility constraints. The resulting shapers are tested on a dense nonlinear validation grid and compared with nominal classical shapers, frequency-robust references, and pointwise-retuned benchmarks. The synthesized four-impulse robust shaper yields the lowest worst-case peak sway among the tested fixed shapers and satisfies all imposed feasibility limits over the validation domain. A frequency-robust reference retains a lower mean peak sway, a shorter shaping horizon, and lower drive demand. The proposed shaper is better suited to applications in which limiting the maximum payload excursion is the primary design objective. Full article

In arid and hyper-arid regions, the temporal dynamics of surface soil moisture (SSM) significantly affect surface erodibility, as well as aeolian sediment transport and deposition processes. Conventional measurement techniques fail to meet the requirements of fine spatiotemporal resolution monitoring, and terrestrial laser scanning (TLS) possesses unique advantages and great application potential for SSM detection. In this study, the accuracy and feasibility of TLS for retrieving SSM in sandy desert were evaluated. The experimental results reveal that sand particle size, measurement distance and SSM are three important factors affecting laser signal amplitude. The relationship between measurement distance and amplitude follows a three-stage variation pattern that can be well fitted by an exponential decay model. Amplitude fluctuates with sand particle size, and the fluctuations become more pronounced at longer measurement distances or higher SSM levels. A strong linear correlation exists between amplitude and SSM within the range of 2.5–20%. Accordingly, particle size-dependent calibration equations were established to estimate SSM from TLS observations. Field validation was further conducted to clarify the applicable scope and constraints of this method. This approach provides an innovative solution for the high-precision, rapid, non-contact and dynamic monitoring of SSM in arid sandy desert. Full article

Background: Total hip arthroplasty (THA) is an effective treatment for advanced hip osteoarthritis, yet the influence of the surgical approach on early biomechanical and neuromuscular recovery remains debated. The direct anterior approach (DAA) is considered muscle-sparing, whereas the lateral approach (LA) involves partial abductor detachment and may influence postoperative gait and muscle activation. As a first step, this pilot study was designed primarily to assess the feasibility of an integrated, multidomain assessment protocol to combine clinical and patient-reported outcomes, instrumented gait analysis, hip biomechanics, and surface electromyography (sEMG), and to delineate preliminary trajectories of recovery after DAA versus LA THA to inform a future, adequately powered trial. Methods: In this prospective, non-randomized pilot study, 12 patients undergoing primary unilateral THA were evaluated and allocated according to surgical approach (DAA, n = 6; LA, n = 6). Assessments were performed at three months (T3M) and six months (T6M) postoperatively. Outcomes included pain intensity, SF-12, the Hip disability and Osteoarthritis Outcome Score (HOOS), instrumented gait analysis, hip kinematics and kinetics, and sEMG activity of the gluteus medius, semitendinosus, and rectus femoris of the operated limb. Given the small sample, between-group differences, within-group changes, and change scores from T3M to T6M were analyzed using non-parametric tests, and all results were treated as exploratory and hypothesis-generating. Results: Recruitment, retention, and completion of the full multidomain protocol were feasible, with no missing primary outcomes. Preliminary findings suggested that at three months, the DAA group showed lower pain and higher PCS-12, HOOS Total and HOOS Function scores, together with faster gait speed, longer normalized stride length, and shorter cycle and stance times. At six months, spatiotemporal gait parameters no longer appeared to differ between groups, suggesting the convergence of global gait performance, whereas the DAA group tended to maintain higher HOOS Total and Function scores and lower pain. The LA group showed greater late-stance hip extension and higher semitendinosus and rectus femoris sEMG amplitudes at T6M. Change-score analysis suggested a possible catch-up phenomenon in the LA group for gait speed, stride length, stance time, cycle time, and hip flexion range of motion, whereas semitendinosus activation tended to decrease in the DAA group and increase in the LA group. Given the limited sample, these observations are preliminary and require confirmation. Conclusions: This pilot study supports the feasibility of an integrated protocol combining patient-reported measures, instrumented gait analysis, and sEMG to characterize early recovery after THA. Preliminary, hypothesis-generating data suggest that DAA may be associated with a more favorable early postoperative clinical and spatiotemporal gait profile, with global gait performance tending to converge between approaches by six months, while persistent differences in hip-specific patient-reported outcomes and sEMG activation patterns hint that a similar gait performance may be achieved through different neuromuscular strategies. These preliminary findings should be interpreted with caution and used primarily to inform the design of larger, adequately powered studies with longer follow-up. Full article

Terahertz time-domain spectroscopy (THz-TDS) is a widely used technique for characterizing a broad range of materials in the terahertz frequency region. Conventional THz-TDS requires both reference and sample signals to extract optical parameters such as refractive index and absorption coefficient. Determining optical anisotropy, specifically birefringence and linear dichroism, typically requires separate measurements of the optical parameters of the sample parallel and perpendicular to the terahertz electric field. This process increases measurement time and depends heavily on a stable reference scan. In this work, we present a simple and accurate method to directly obtain birefringence and linear dichroism without the need for a reference measurement. The proposed approach extracts anisotropic parameters solely from the sample signals by analyzing the differential phase delay and amplitude attenuation between orthogonally polarized terahertz electric field components. We validate this method experimentally using optically anisotropic materials such as TiO₂ and bamboo samples and confirm that the results agree closely with those from conventional reference-based THz-TDS. This technique offers a practical route to measure the optical anisotropy of materials, particularly in situations where acquiring a reference signal is challenging. Full article

Anti-friction bearings are fundamental components in rotating machinery. Any bearing fault appearing during operation could lead to catastrophic damages and failures without proper maintenance. Numerous methods have been developed for bearing fault detection to reduce maintenance costs and avoid unscheduled downtime. However, once a bearing fault is detected, assessing defect severity may be of more critical concern to industries, as it determines the urgency of interventions such as replacement scheduling and maintenance strategies. This paper presents an efficient estimation method for bearing fault severity using vibration-based input parameters and machine learning. Based on modal characteristics, key input parameters, the vibration amplitudes at the bearing fault frequencies and their harmonics, are extracted from acceleration envelope spectra for their close correlations with physical defect conditions. The nonlinearity between these spectral parameters and bearing fault severity is revealed with experimental observations and is represented using artificial neural networks. The model is validated on experimental vibration data measured from a bearing rig, covering various defect scenarios of different sizes and shapes. The classification criteria of bearing fault severity levels, ranging from healthy to severe, are formulated based on physical defect sizes with maintenance recommendations. Robust and accurate fault severity estimation is achieved across three bearing datasets collected under different operating conditions. The proposed method addresses both fault detection and degradation assessment for anti-friction bearings using simple vibration-based parameters based on rotor and bearing dynamics, providing a practical framework for predictive maintenance in industrial applications. Full article

Affected by moisture cohesion, wet rice seeds exhibit poor flowability and frequent arching blockage during silo discharging, which seriously restricts stable grain storage and conveying. To address this issue and reveal its intrinsic flow mechanism, this study establishes a discrete element method (DEM) model for wet rice seed-silo systems adopting the Hertz-Mindlin with Johnson-Kendall-Roberts (JKR) contact model, which incorporates surface energy to reflect moisture-induced cohesive effects. The model is verified via physical silo discharge tests, with consistent flow patterns, wall pressure error below 3.7% and discharge time error of 2.14%. EDEM parametric simulations are conducted to analyze velocity fluctuation at different silo heights. Coordination number and normalized contact force distribution are adopted to assess micro-contact force distribution in discharge areas, and a force chain extraction algorithm is used to explore variations in force chain length and orientation. Results demonstrate that during discharge, average particle velocity drops from silo bottom to top with growing fluctuation amplitude, presenting obvious stratified flow and intense upper-layer velocity pulsation. Weak contacts dominate wet rice seed groups and conform to exponential decay distribution. The force chain network undergoes three evolution phases: formation, force arch generation and collapse. Quantitative analysis reveals long force chain proportion falls steadily from 81.40% to 3.68% throughout discharge. Short force chains rise to 60.54% in the arch-forming stage and reach 96.32% after arch collapse. Horizontal force chains account for a maximum of 71.09% during arch formation, while vertical ones decline from 99.52% initially to 61.57% post collapse. This research offers mechanical references and quantitative parameters for the design and operation of silos for wet granular farm grains like rice seeds, and is particularly relevant to post-harvest engineering, grain storage safety, and agricultural machinery design. Full article

This study aimed to evaluate the efficacy of crude polysaccharide extraction from Thai-cultivated oats (Avena sativa L.) utilizing hot water extraction (HW) and ultrasound-assisted water extraction (UW) methods. Optimal conditions were determined by a response surface methodology (RSM). The influence of solid-to-liquid ratio, temperature or %amplitude, and extraction time on %yield and beta glucan content was investigated. Under optimal conditions, UW produced a superior %yield (82.72 ± 2.19%) and beta glucan content (1.75 ± 0.87 g/100 g extract) compared to HW (41.32 ± 0.98% and 1.25 ± 0.27 g/100 g extract). This finding may occur from acoustic cavitation, which effectively dismantles the cellular wall structure, supported by FTIR analysis finding more distinct β-glycosidic linkage peaks. SEM analyses indicated a greater surface area dispersion and porosity in UW extract relative to HW extract. Analysis of monosaccharide composition supported the properties of both crude extracts, demonstrating glucose as the predominant component. However, the functional and bioactive characterization demonstrated a distinct trade-off between the two extraction methods. HW extract demonstrated superior swelling capacity (6.2 vs. 2.7 g/g at pH 6.5), enhanced antioxidant activity compared to both ABTS (0.67 ± 0.04 vs. 0.58 ± 0.06 μmol TE/g), DPPH (0.53 ± 0.06 vs. 0.35 ± 0.06 μmol TE/g), and FRAP (0.05 ± 0.02 vs. 0.03 ± 0.01 μmol TE/g), total phenolic content (98.33 ± 7.68 vs. 87.79 ± 3.07 mg GAE/g). The crude extracts from the two methods had selective enzyme inhibitory activity, exhibiting considerable inhibition of α-glucosidase and markedly reduced inhibition of α-amylase. UW demonstrated slightly superior inhibitory activity compared to HW for both enzymes. The findings indicate that the determination of crude polysaccharides should principally take into account the purpose of the final product. UW is preferable for optimizing %yield and beta glucan content. Nevertheless, if the emphasis is on functional attributes like water absorption and antioxidant efficacy, HW has advantages that merit a consideration. This research provides a framework for identifying optimal extraction methods aimed at extracting crude polysaccharides from Thai-cultivated oats for use as a functional ingredient in health food products. Full article

Large-scale spectrum monitoring infrastructures generate high-dimensional spectral time series, providing a critical data foundation for proactive spectrum management, anomaly detection, radio environment awareness, and interference-aware decision-making. In complex electromagnetic environments, real-world deployments are highly nonstationary and frequently affected by unexpected interference, which substantially degrades the predictability of spectrum dynamics and the reliability of downstream spectrum sensing and management systems. Consequently, classical linear forecasting methods and generic deep sequence models often generalize poorly from clean training conditions to interference-corrupted scenarios, as jamming patterns distort the latent representations used for future-spectrum forecasting. This study focuses on multivariate spectrum forecasting, where the objective is to predict multi-step future amplitude or power distributions across all frequency bins from a historical observation window. To address this limitation, we propose DS-SpecIT, a Decomposed Spectral Inverted Transformer for interference-aware spectrum forecasting. Unlike generic long-term forecasting models that mainly minimize average prediction errors, DS-SpecIT is specifically designed to handle structured electromagnetic interference. Its novelty lies in the integration of spectral tokenization, inverted attention over frequency tokens, an interference-aware dual-scale objective, and orthogonality-based latent feature separation. These components enable the model to jointly preserve global spectral trends and reduce local errors inside interference-affected time–frequency regions. Using publicly available spectrum measurements, we establish evaluation protocols under both clean and synthetic-jamming settings. Experiments show that DS-SpecIT maintains competitive clean setting accuracy while achieving stronger global and local robustness under structured interference. Full article

Permanent magnet synchronous motors (PMSMs) are widely used in various fields due to their advantages. However, mechanical position sensor failures will cause various serious safety issues. High-frequency square-wave injection (HF-SWI) enables sensorless control of PMSMs at low speeds; yet, the fixed-frequency nature of conventional methods results in narrow current power spectral density (PSD), causing harsh noise and limiting the widespread application of sensorless control, especially in household appliances. To address this, this paper proposes a pseudo-random coding (PRC) injection strategy. First, a 2³ PRC-injection method (2³ PRC-IN) is introduced, which disrupts the signal periodicity by varying the injection frequency and amplitude, thereby significantly expanding the current PSD. To further suppress residual peaks in the 2³ PRC-IN, an improved 2^(3&1) PRC-IN method is developed. By optimizing the code transition logic, this approach can completely eliminate the sharp noise. Experiments on a 5.5 kW PMSM platform validate that the proposed methods effectively broaden the current PSD and reduce the noise without compromising position observation accuracy. Full article

Objectives: This cross-sectional study examined associations between field bioelectrical impedance analysis (BIA)-estimated body composition, handgrip strength, event-defined centre-of-pressure (CoP) variables, and short-range police precision-shooting accuracy. Methods: Fifty-seven Police Officer Training Course cadets completed body-composition assessment, handgrip testing, and five-shot Glock 19 pistol tasks at 5 and 7 m. CoP variables were extracted during an event-defined aiming phase and a fixed 1 s post-discharge phase. Results: Shooting accuracy was higher at 5 m than at 7 m (p < 0.001). Higher BIA-estimated fat mass percentage was associated with lower shooting accuracy at both distances (p < 0.050), whereas handgrip strength was not associated with accuracy. Compared with the aiming phase, the post-discharge phase was characterized by greater CoP velocity-related measures and lower CoP amplitude and displacement (p < 0.010); these phase comparisons should be interpreted with caution because of differences in phase duration. Associations between CoP variables and shooting accuracy were generally weak. Sex-adjusted exploratory fixed-entry regression models showed modest explanatory capacity after internal validation (5 m: adjusted R² = 0.281, LOOCV_R² = 0.240; 7 m: adjusted R² = 0.193, LOOCV_R² = 0.131). BIA-estimated fat mass percentage and AP peak velocity during aiming were retained across distances, but these model-based findings should be interpreted as exploratory candidate associations rather than stable predictors. Conclusions: These findings suggest that field BIA-estimated body composition and task-specific postural regulation may be related to police precision-shooting accuracy but should be interpreted as correlates rather than determinants of performance. Full article

The problem of fault diagnosis in electrical motors has an important impact on the supervision of dynamic systems, and model-based methods are efficient tools for this purpose. In this regard, this work presents a novel method for detecting inter-turn short circuits (ITSCs) in the stator windings of permanent magnet synchronous motors (PMSMs). The approach is based on algebraic identification to process the motor voltage signals, estimating the offsets, amplitudes, and phases of the fundamental and third-harmonic components. Fault detection is performed in two steps: first, a voltage imbalance index is evaluated to determine the presence of abnormal operating conditions. Subsequently, characteristic patterns in the estimated parameters are analyzed to identify both the fault type and the affected phase(s). The experimental results show that single-phase ITSC faults produce a reduction in the offset of the faulted phase together with an increase in its third-harmonic amplitude, whereas phase-to-phase ITSC faults lead to an increase in the offsets of the affected phases and nearly identical third-harmonic amplitudes between them. In both cases, only minor variations are observed in the estimated phase angles. The effectiveness of the proposed methodology is supported through theoretical analysis and validated experimentally using voltage measurements acquired from a PMSM test bench. The results demonstrate that the proposed technique can accurately identify fault conditions through voltage imbalance and harmonic-pattern analysis, providing a practical and computationally efficient methodology for PMSM stator winding fault diagnosis. Full article

In this study, a high-order Galerkin–Numerov approach is presented to solve the transient vibration problem of anisotropic Kirchhoff plates supported by a uniform Vlasov foundation. A discretization of the governing fourth-order plate equation is derived based on a mixed boundary value problem and a hybrid Hermite–sine Galerkin formulation, which maintains the C1-continuity properties of classical plate theory. The resulting reduced-order modal system is integrated in time with the Numerov scheme, which is fourth-order accurate, and has a small numerical dispersion and good phase-preserving properties for oscillatory dynamics. The proposed methodology is evaluated using stability and convergence tests and parametric investigations. The fourth-order temporal convergence and rapid spectral-like spatial convergence of the numerical results are validated, and the long-time accuracy and robustness of the formulation is confirmed by the negligible phase error and bounded energy drift. The results from the parametric study indicate that the thickness of the plates and the stiffness of the Winkler foundation are the two most important mechanisms for vibration suppression, while the orthotropic coupling and the Vlasov shear interaction have substantial effects on the modal redistribution and transient deformation properties. The proposed method is compared with the conventional lower-order integration schemes, and it is observed that the method gives better phase fidelity and computational efficiency, and it is possible to predict the vibration amplitude and vibration timing accurately. In addition to the numerical benefits, the framework also provided physical insights on the coupled effect of anisotropy, foundation interaction and boundary restraint. The suggested model is directly applicable for composite floor systems, aerospace panels, foundation supported slabs, biomechanical plate analogs, etc., and smart vibration control platforms. This work thus lays the groundwork for future studies of nonlinear behavior, adaptive foundations and digital twin simulation of structural systems and presents a strong and scalable computational tool for the study of plate–foundation dynamics. Full article