Search Results (1,823)

Surface permanent-magnet synchronous motors (SPMSMs) have been widely adopted for ship propulsion due to their high power density and efficiency. However, conventional three-phase open-slot SPMSMs struggle to balance high efficiency with reductions in cogging torque and torque ripple. This paper proposes a design of an SPMSM with a six-phase winding configuration and a chamfer-shaped permanent magnet to reduce cogging torque and torque ripple. Electromagnetic performance is evaluated through finite element analysis (FEA). A reference three-phase interior PMSM and three-phase SPMSMs with different magnet shapes are first compared to identify a suitable basic design. Based on the basic machine, three pole–slot combinations for the six-phase winding are analyzed, and the most efficient configuration is selected. A final model is designed to minimize cogging torque and torque ripple for the chamfer-shaped permanent magnet. Finally, the effectiveness of the final model is validated through FEA by comparing its performance with that of the reference model. Full article

This paper focuses on the vibration analysis of a prototype helicopter rotor test stand, with particular attention to the dynamic response of its electric propulsion system. The stand is driven by an induction motor and equipped with composite rotor blades of various geometries, including blades with shape memory alloy (SMA)-based torsion actuators for angle of attack (AoA) adjustment. These variable geometries significantly influence the system’s dynamic behavior, where resonance phenomena may pose risks to structural integrity. The objective was to investigate how selected operational parameters specifically motor speed and AoA affect the vibration response of the propulsion system. Structural vibrations were measured using a tri-axial piezoelectric accelerometer system integrated with calibrated signal conditioning and high-resolution data acquisition modules. This setup enabled precise, time-synchronized recording of dynamic responses along all three axes. Fast Fourier Transform (FFT) and Power Spectral Density (PSD) methods were applied to identify dominant frequency components, including those associated with rotor harmonics and SMA activation. The highest vibration amplitudes were observed at an AoA of 16°, but all results remained within the vibration limits defined by MIL-STD-810H for rotorcraft drive systems. The study confirms the importance of sensor-based diagnostics in evaluating electromechanical propulsion systems operating under dynamic loading conditions. Full article

The adoption of Interior Permanent Magnet Synchronous Motor (IPMSM) in Battery Electric Vehicle (BEV) and Plug-in Hybrid Electric Vehicle (PHEV) drives the need for innovative approaches to improve control performance and power conversion efficiency. This paper aims at evaluating advanced Model Predictive Control (MPC) strategies for IPMSM drives in a methodic comparison with the most widespread Field Oriented Control (FOC). Different extensions of direct Finite Control Set MPC (FCS-MPC) and indirect Continuous Control Set MPC (CCS-MPC) MPCs are considered and evaluated in terms of reference tracking performance, robustness, power efficiency, and complexity based on Matlab, Simulink™ simulations. Results confirm the inherent better control quality of MPCs over FOC in general and allow us to further identify some possible directions for improvement. Moreover, indirect MPCs perform better, but complexity may prevent them from supporting real-time implementation in some cases. On the other hand, direct MPCs are less complex and reduce inverter losses but at the cost of increased Total Harmonic Distortion (THD) and decreased robustness to parameters deviations. These results also highlight various trade-offs between different predictive control strategies and their feasibility for high-performance automotive applications. Full article

Countermovement jump (CMJ) is a key test for evaluating lower-limb neuromuscular function, and accurate measurement of countermovement depth (CMD) and countermovement velocity (CMV) is critical for determining optimal performance. However, the measurement validity and reliability of CMD and CMV—particularly when obtained from force plates (FP) and linear position transducers (LPT)—have remained uncertain. This study determined the validity and reliability of FP and LPT for measuring CMD and CMV. Twenty-eight male recreational athletes performed the CMJ test, and the variables were synchronously acquired by Motion Capture (MC), FP, and LPT. The test was divided into two sessions, with participants completing three maximal effort CMJs per session, and the second session occurred more than 48 h after the first. The reliability was evaluated using the intraclass correlation coefficient (ICC), and the validity was evaluated with linear Pearson’s correlation coefficient (r), one-way ANOVA with repeated measures, and Bland–Altman plots. The reliability results for FP and LPT indicated good to excellent (ICC = 0.809–0.900). Compared with MC, the FP showed a high to very high correlation (r = 0.894–0.937), and the LPT showed a high correlation (r = 0.721–0.726). When precise quantification of CMD/CMV is required, FP should be preferred. If only an LPT is available, it is best used for within-athlete longitudinal monitoring with a consistent setup, and cross-device comparisons should be avoided. Full article

Student disengagement remains a major barrier to effective learning in synchronous online classrooms, where lack of interaction, limited feedback, and screen fatigue often contribute to passive participation. Despite the growing use of generative AI, there is a notable lack of empirical research investigating the application of generative AI in addressing engagement challenges in synchronous online sessions. This study introduces VClass Engager, a novel experimental system that utilizes generative AI to foster student participation and deliver instant, personalized feedback during live virtual sessions. The system integrates several features, including instant analysis of student answers to chat questions, real-time AI-generated feedback, and a leaderboard that displays students’ cumulative scores to promote sustained engagement. To assess its effectiveness, the system was evaluated across multiple courses. Engagement was measured by tracking participation in three in-class formative questions, and response quality was analyzed using a cumulative link mixed model (CLMM). In addition, a post-session survey captured students’ perceptions regarding usability, motivational impact, and feedback quality. Results demonstrated statistically significant increases in student participation and response quality in sessions using VClass Engager compared to baseline sessions. Survey responses revealed high levels of satisfaction with the system’s ease of use and motivational aspects. By combining AI and gamification, this study provides early empirical evidence for a promising approach to enhancing engagement in synchronous online learning. Full article

This paper presents the experimental implementation and validation of the two-chamber method presented in Part I for the high-precision determination of the temperature coefficient of resistance (TCR) of current shunts. The two-chamber approach enables improved thermal isolation and independent temperature control of the reference and test shunts, which significantly reduces the measurement uncertainty. In this part, the complete experimental setup is described, including the thermoelectric temperature control, the current generation and the data acquisition system with synchronized high-resolution digital multimeters (DMMs). The experimental measurements were carried out for different resistance ratios ranging from 0.1 to 10. The results confirm the theoretical predictions and the uncertainty analysis from Part I. The influences of the stability of the current source, the temperature uniformity and the synchronization accuracy on the measurement results are evaluated. The two-chamber method shows high repeatability, ease of use and suitability for laboratory and interlaboratory tests, and thus represents a robust alternative to classical TCR determination methods. Full article

Magnetically controlled spinal growing rods, used for treating early-onset scoliosis (EOS), face a critical clinical limitation: insufficient distraction force. Compounding this issue is the inherent inability to directly monitor the mechanical output of such implants in vivo, which challenges their safety and efficacy. To overcome these limitations, optimizing the rotor’s maximum torque is essential. Furthermore, defining the “continuous rotation domain” establishes a vital safety boundary for stable operation, preventing loss of synchronization and loss of control, thus safeguarding the efficacy of future clinical control strategies. In this study, a transient finite element magnetic field simulation model of a circumferentially distributed permanent magnet–rotor system was established using ANSYS Maxwell (2024). The effects of the clamp angle between the driving magnets and the rotor, the number of pole pairs, the rotor’s outer diameter, and the rotational speed of the driving magnets on the rotor’s maximum torque were systematically analyzed, and the optimized continuous rotation domain of the rotor was determined. The results indicated that when the clamp angle was set at 120°, the number of pole pairs was one, the rotor outer diameter was 8 mm, the rotor achieved its maximum torque and exhibited the largest continuous rotation domain, while the rotational speed of the driving magnets had no effect on maximum torque. Following optimization, the maximum torque of the simulation increased by 201% compared with the pre-optimization condition, and the continuous rotation domain was significantly enlarged. To validate the simulation, a rotor torque measurement setup incorporating a torque sensor was constructed. Experimental results showed that the maximum torque improved from 30 N·mm before optimization to 90 N·mm after optimization, while the driving magnets maintained stable rotation throughout the process. Furthermore, a spinal growing rod test platform equipped with a pressure sensor was developed to evaluate actuator performance and measure the maximum distraction force. The optimized growing rod achieved a peak distraction force of 413 N, nearly double that of the commercial MAGEC system, which reached only 208 N. The simulation and experimental methodologies established in this study not only optimizes the device’s performance but also provides a viable pathway for in vivo performance prediction and monitoring, addressing a critical need in smart implantable technology. Full article

Urea is one of the most widely used sources of non-protein nitrogen (NPN) in ruminant diets due to its low cost and high availability. However, its rapid solubilization in the rumen can result in abrupt ammonia release, leading to toxicity risks and low nitrogen utilization efficiency. In this context, slow-release technologies, particularly microencapsulation, have been developed to synchronize NPN release with fermentable carbohydrate availability, thereby enhancing microbial protein synthesis, improving animal performance, and reducing environmental impacts. This review compiles recent advances in urea microencapsulation, emphasizing different wall materials such as waxes, lipids, polysaccharides, and fatty acids, as well as drying techniques and formulation strategies. Slow-release urea (SRU) addition in small ruminants’ diet may increase nutrient intake and digestibility, improve N balance, and reduce urinary excretion losses. Regarding performance, positive responses are observed when nitrogen release is properly synchronized with energy availability, although the results may vary depending on the encapsulant type, forage-to-concentrate ratio, and ruminal passage rate. Additionally, effects on meat quality and environmental parameters indicate that this technology holds not only zootechnical but also socio-environmental potential. It is concluded that urea microencapsulation can represent a promising alternative to optimize NPN use efficiency in ruminant production systems, though greater methodological standardization, long-term evaluations, and comparative economic analyses are required to encourage its broader adoption. Full article

The Clinical Descriptions and Diagnostic Guidelines (CDDG) for Mental, Behavioral, and Neurodevelopmental Disorders (MBND) in the International Classification of Diseases 11th Revision (ICD-11) are a substantial improvement over their equivalent in the ICD-10. This study evaluates the usefulness of the synchronous and asynchronous modalities of an online training course on the ICD-11-CDDG-MBND to increase readiness to implement it in routine clinical practice among Spanish-speaking clinicians. A convenience sample of psychiatrists, psychologists, and general practitioners completed online evaluations of one of the two course modalities. Acquired knowledge was evaluated through a multiple-choice questionnaire. Readiness to implement the ICD-11-CDDG-MBND was evaluated before and after the course, using an instrument based on the transtheoretical model of stages of change: precontemplation, contemplation, preparation and action. A total of 310 clinicians completed either the asynchronous (n = 176) or synchronous course (n = 134). Prior to the course, most participants were at the precontemplation stage. By the end of the course, participants reported a moderate level of knowledge. The percentage of clinicians at the preparation and action stages was higher than before the courses, with no differences being observed between course modalities. Online training was associated with increased knowledge and motivation to implement the ICD-11-CDDG-MBND. Full article

Background: Multifocal (MF) and multicentric (MC) breast cancers, defined by the presence of multiple synchronous tumor foci within the same breast, present important diagnostic, therapeutic, and prognostic challenges. Historically considered a contraindication for breast-conserving therapy (BCT), advances in imaging, surgical techniques, and adjuvant therapy have reshaped management strategies. Methods: A narrative literature review was conducted through PubMed, Web of Science, and Scopus, prioritizing ISI-indexed articles published within the last 10–15 years. More than 55 relevant studies, including systematic reviews, meta-analyses, and large cohorts, were analyzed to evaluate epidemiology, pathological features, imaging modalities, treatment outcomes, and prognosis of MF/MC breast cancers. Results: The reported incidence of MF/MC breast cancers ranges from 10% to 24%, increasing when MRI or whole-organ pathology is applied. MRI can detect otherwise occult additional foci in up to 30% of patients, improving staging accuracy but raising concerns of overdiagnosis. MF/MC presentation is strongly associated with lobular histology, younger age at diagnosis, and higher rates of axillary involvement—nodal positivity is observed in up to 45% of MF/MC cases versus 28% in unifocal tumors. Pathological analyses demonstrate frequent clonal origin of MF lesions, whereas MC lesions may represent independent primaries, occasionally with receptor heterogeneity that alters systemic therapy selection. From a prognostic perspective, older series suggested shorter breast cancer-specific survival (e.g., median 154 vs. 204 months for MF/MC vs. unifocal disease), and higher local recurrence with BCT. However, contemporary analyses, including a 2022 meta-analysis of 15,703 patients, demonstrated no significant difference in overall or disease-free survival once adjusted for tumor size and nodal status. Local recurrence remains slightly higher with BCT in MF/MC (5.6% vs. 4.2%), but outcomes are equivalent to mastectomy when radiotherapy is appropriately delivered. Five-year survival in early-stage MF/MC exceeds 90% with guideline-concordant multimodal therapy. Conclusions: MF/MC breast cancers represent a biologically heterogeneous entity. Optimal outcomes rely on precise imaging, complete excision, tailored systemic therapy, and multidisciplinary management, with increasing acceptance of breast conservation in selected patients. Full article

This paper proposes a solution to enhance the torque production capability of Permanent Magnet Synchronous Machine (PMSM), utilizing not only the unused space resulting from the stator end windings on the rotor side, but also the otherwise unused space around the winding on the yoke side. By implementing an additional axial rotor equipped with Permanent Magnets (PMs) in both rotor and yoke sides, the proposed design technique increases the PMSM torque output, taking advantage of the useless space on the yoke side. In the proposed configuration, one magnetic flux path circulates between the PMs on the rotor (rotor side) and the stator, while an additional flux path circulates between the PMs positioned on both sides of the stator end windings. These two flux paths contribute to generating a stronger and more effective magnetic field within the machine than conventional structure, resulting in increased torque density. A magnetic equivalent circuit (MEC) model of the proposed design is developed, and its accuracy is validated through Finite Element (FE) analysis. For a fair evaluation, the proposed structure is compared with a conventional configuration using the same volume of PM material. Furthermore, optimization of the proposed design is carried out to maximize Torque/PM. Full article

The Hamiltonian Monte Carlo (HMC) method is effective for Bayesian inference but suffers from synchronization overhead in distributed settings. We propose two variants: a distributed HMC (DHMC) baseline with synchronized, globally exact gradient evaluations and a communication-avoiding leapfrog HMC (CALF-HMC) method that interleaves local surrogate micro-steps with a single–global Metropolis–Hastings correction per trajectory. Implemented on Apache Spark/PySpark and evaluated on a large synthetic logistic regression ($N={10}^7$, $d=100$, workers $J\in \{4,8,16,32\}$), DHMC attained an average acceptance of $0.986$, mean ESS of 1200, and wall-clock of $64.1$ s per evaluation run, yielding $\approx 18.7$ ESS/s; CALF-HMC achieved an acceptance of $0.942$, mean ESS of $5.1$, and $14.8$ s, i.e., ≈0.34 ESS/s under the tested surrogate configuration. While DHMC delivered higher ESS/s due to robust mixing under conservative integration, CALF-HMC reduced the per-trajectory runtime and exhibited more favorable scaling as inter-worker latency increased. The study contributes (i) a systems-oriented communication cost model for distributed HMC, (ii) an exact, communication-avoiding leapfrog variant, and (iii) practical guidance for ESS/s-optimized tuning on clusters. Full article

This paper investigates the impact of permanent magnet (PM) displacement and flux barrier extension on cogging torque in flux-intensifying permanent magnet-assisted synchronous reluctance machines (FI-PMa-SynRMs) with surface-inset PMs. Unlike prior work centred on average torque, torque ripple, or inductance, we focus on cogging torque, a key driver of noise and vibration. Four rotor configurations are evaluated via finite element analysis of ∼20,000 designs per configuration generated during NSGA-II multi-objective optimisation. To avoid bias from near-duplicate designs, we introduce Euclidean distance-based medoid filtering, which enforces a minimum separation of models within each configuration. The cross-configuration similarity is measured by Euclidean distance over common design variables. Results show that PM displacement alone does not substantially reduce cogging torque, while flux barrier extension alone yields reductions of up to ∼25%. Combining PM displacement with flux barrier extension achieves up to a ∼30% reduction in cogging torque, often maintaining average torque and lowering torque ripple. This study provides a comparative framework for mitigating cogging torque in FI-PMa-SynRMs and clarifies the trade-offs revealed by similarity-based analyses. Full article

Background: Stereotactic body radiotherapy (SBRT) is an established curative modality for patients with early-stage non-small cell lung cancer (NSCLC) who are not candidates for surgery. In circumstances where neither surgical resection nor tissue sampling can be performed, SBRT may still be administered empirically, with accumulating evidence indicating excellent efficacy and safety. Objective: This single-institution retrospective study aimed to evaluate the clinical outcomes of SBRT for presumed malignant lung lesions, focusing on local control, survival, and treatment-related toxicity, and to compare these findings with published results in histologically confirmed NSCLC. Methods: Between 2018 and 2024, 80 cases with 85 pulmonary lesions received SBRT at the Department of Oncoradiology, University of Debrecen. All patients underwent comprehensive staging with chest CT and PET-CT, and treatment decisions were made by a multidisciplinary tumor board. Eligibility required the absence of other primary malignancies within 5 years. Treatment planning was based on 4D-CT imaging with internal target volume delineation across multiple respiratory phases. SBRT was delivered on linear accelerators in 4–8 fractions, to a total dose of 48–60 Gy, using volumetric-modulated arc therapy and daily image guidance with 4D cone-beam CT. Results: Most patients presented with solitary lesions, while several had synchronous or metachronous multiple lesions (maximum 3 lesions). The median age was 70.1 years, with 60% ECOG performance status 1. Median follow-up was 21 months. One- and two-year local control rates were 89.8% and 94.3%, respectively, with a 51.4% complete response rate at two years. Mean overall survival was 49.6 months. No grade ≥ 3 toxicities were observed. Conclusions: Empirical SBRT is a safe, well-tolerated, and highly effective treatment option in elderly, inoperable patients with presumed malignant lung lesions. Its favorable efficacy supports its broader use as a curative alternative when histological confirmation is not feasible. Full article

Background/Objectives—Traditional forensic investigations often analyze digital, physical, and criminological evidence separately, leading to fragmented timelines and reduced accuracy in reconstructing complex events. To address these gaps, this study proposes the Digital Stratigraphy Framework (DSF), inspired by archaeological stratigraphy, to integrate heterogeneous evidence into structured, temporally ordered layers. DSF aims to reduce asynchronous inconsistencies, minimize false associations, and enhance interpretability across digital, behavioral, geospatial, and excavation evidence. Methods—DSF employs Hierarchical Pattern Mining (HPM) to detect recurring behavioral patterns and Forensic Sequence Alignment (FSA) to synchronize evidence layers temporally and contextually. The framework was tested on the CSI-DS2025 dataset containing 25,000 multimodal, stratified records, including digital logs, geospatial data, criminological reports, and excavation notes. Evaluation used 10-fold cross-validation, Bayesian hyperparameter tuning, and structured train-validation-test splits. Metrics included accuracy, precision, recall, F1-score, and Stratigraphic Reconstruction Consistency (SRC), alongside ablation and runtime assessments. Results—DSF achieved 92.6% accuracy, 93.1% precision, 90.5% recall, 91.3% F1-score, and an SRC of 0.89, outperforming baseline models. False associations were reduced by 18%, confirming effective cross-layer alignment and computational efficiency. Conclusions—By applying stratigraphic principles to forensic analytics, DSF enables accurate, interpretable, and legally robust evidence reconstruction. The framework establishes a scalable foundation for real-time investigative applications and multi-modal evidence integration, offering significant improvements over traditional fragmented approaches. Full article