Search Results (1,690)

To address the current issues of single-objective control and the inability to achieve coordinated operation between the Modular Multilevel Converter (MMC) and the thyristor rectifier in parallel-type ice melting systems, this paper proposes a master-slave coordinated control method for such systems. The MMC operates in constant PQ mode, while the thyristor rectifier operates in constant-voltage mode. The thyristor rectifier provides voltage support to the MMC, and an adaptive U-I droop control is introduced in the control loop to cope with voltage drop. The MMC adjusts its active power output according to the operating condition of the thyristor rectifier, enabling coordinated ice melting operation, while simultaneously performing reactive power compensation and active filtering for the system. This paper elucidates the operating principle of the ice melting system, analyzes its harmonic characteristics, designs a control strategy, and constructs a PSCAD 5.0 simulation model to validate the proposed control strategy. The results demonstrate that the proposed strategy can coordinate the active power allocation between the MMC and the thyristor rectifier, laying the foundation for the safe and stable operation of the ice melting system while suppressing the harmonic currents and reactive power introduced into the power grid by the thyristor ice melting system. Full article

Since the 1960s, Bioethics, Law and Deontology have become increasingly integrated into healthcare education in response to the growing ethical, legal and professional complexity of clinical practice. This national cross-sectional comparative study aimed to investigate the presence and structural characteristics of Bioethics, Law and Deontology teaching in Greek undergraduate Medical, Dental and Nursing curricula. Online study guides and syllabi for the academic year 2024–2025 from all Greek public Medical (n = 7), Dental (n = 2) and Nursing (n = 9) Departments were systematically reviewed. Data regarding course presence, type, semester allocation, European Credit Transfer and Accumulation (ECTS) credits and teaching hours were extracted and analyzed using descriptive and comparative statistics. Courses related to Bioethics, Law and Deontology were identified in 17 of 18 Departments (94.4%). The mean teaching hours per Department were 37.4, with Nursing Departments demonstrating higher teaching loads. However, 50% of Departments reported fewer teaching hours than the minimum proposed by the UNESCO Bioethics Core Curriculum. Considerable heterogeneity was observed regarding course structure and curricular integration. These findings suggest the need for greater curricular harmonization and strengthened Bioethics, Law and Deontology education in Greek undergraduate healthcare training. Full article

This study analyses the effect of an agricultural biogas plant on power quality at the connection point of a dairy cattle farm. The main objective was to determine how power generation and fermenter mixer operation affect selected power quality parameters. Four characteristic operating states of the system were analysed, differing in terms of power generation and mixer operation. The measurement results showed that generator operation stabilised the voltage in the low-voltage network. When the generator was switched off, the voltage decreased from approximately 234 V to approximately 226 V, confirming the clear effect of local generation on the supply voltage level. At the same time, the analysis of total harmonic distortion (THD_U) showed that the greatest differences occurred when the generator was switched off, particularly between states with the fermenter mixers operating and inactive. In this case, the mean difference (Δmean) in phase L3 reached 0.31, indicating increased susceptibility of the system to non-linear loads in the absence of local generation. Mixer operation caused only a moderate voltage reduction and minor changes in power quality parameters. Its effect was therefore weaker than that of power generation. Statistical analysis, including the Games–Howell test, confirmed significant differences among most operating states, particularly between states with and without generation. Full article

Multi-antenna-based covert communication techniques exploit spatial degrees of freedom to improve transmission efficiency under covertness constraints, but this generally comes at the cost of increased hardware complexity and power consumption. To this end, time-modulated arrays (TMA) enable multi-user covert communication with a single radio-frequency (RF) chain, providing a promising solution for low-complexity and energy-efficient covert communication. However, the infinite-order harmonics generated by time modulation spread signal energy over the entire spectrum, allowing the warden to enhance detection capability via cross-band observations, which aggravates signal leakage toward unintended directions. This paper develops a binary hypothesis testing model from the perspective of the warden based on infinite-order harmonic characteristics, to characterize the statistical properties and power distribution of harmonic-induced leakage. Furthermore, since the Kullback–Leibler (KL) divergence is intractable under infinite-order harmonic conditions, a computable upper bound is derived to enable covert constraint analysis. Considering the strong coupling among system parameters, an optimization problem is formulated to maximize the minimum covert transmission rate, and a genetic algorithm (GA) is employed for the joint design of time modulation, power allocation, and spatial phase. Simulation results demonstrate that the proposed scheme effectively suppresses signal leakage and improves covert transmission performance. Full article

Microphysiological Systems (MPS) have emerged as a transformative platform in biomedical research, enabling the investigation of disease mechanisms, drug screening, and toxicity prediction by closely simulating human physiological functions. However, the rapid advancement of MPS technology has raised a series of complex ethical challenges. These include the sourcing and application of human-derived stem cells, the protection of donors’ personal and genetic data, the potential for brain organoids to develop consciousness-like characteristics, and the challenges to species boundaries posed by human–animal chimera research. Meanwhile, although regulatory authorities encourage innovation, specialized certification standards and ethical review guidelines for MPS are yet to be fully established. The lack of technical standardization and a coherent ethical governance framework remain a major bottleneck hindering the broader application and industrialization of MPS. This review systematically outlines the key ethical issues facing MPS, compares the evolution and differences in international ethical regulatory frameworks, and discusses strategies for addressing these challenges—including the establishment of dynamic ethical governance mechanisms, harmonization of international standards, and the promotion of benefit-sharing and public engagement. Finally, we highlight the need to develop a scientific, unified, and actionable ethical governance system that balances technological innovation with responsible translation, supporting the sustainable development of MPS technology. Full article

Identifying driving styles is essential for personalizing driving assistance systems and enhancing intelligent transportation services. However, existing approaches predominantly rely on experience-driven feature engineering and annotated data, limiting objectivity and hindering the exploitation of unlabeled naturalistic driving datasets. To address these limitations, this paper proposes an unsupervised framework for driving style identification from naturalistic driving data through context normalization. A Constrained Convolutional Autoencoder (CCAE) integrated with a global self-attention mechanism is developed to map unlabeled driving sequences onto a standardized dynamic reference defined by the Worldwide Harmonized Light Vehicles Test Cycle (WLTC). This process extracts Driving Adaptability Characteristics (DACs) as WLTC-anchored latent representations that characterize normalized driver-specific response patterns across heterogeneous naturalistic contexts. To ensure feature robustness, frequency-domain refinement is applied to eliminate high-frequency noise. The extracted DAC sequences are subsequently partitioned into distinct driving styles using a kernel-mapped clustering algorithm. To evaluate the external relevance and physical interpretability of the identified styles, actual vehicle accident records and raw CAN-bus feature backtracking are introduced as validation evidence. The results show that the identified driving styles exhibit different historical accident probabilities. The proposed CCAE model achieves clearer cluster-level differentiation than traditional feature engineering and unconstrained deep learning models, and the ablation analysis confirms the contribution of the WLTC-based constraint. These findings indicate that the context-normalization framework can extract interpretable and externally relevant driving style representations from unlabeled naturalistic data. Full article

Power quality disturbances (PQDs) in microgrids pose significant challenges to stable and reliable operation, particularly in tourism-oriented island systems with highly variable and uncertain load patterns. This paper proposes an interpretable PQD identification framework based on time–frequency feature extraction. The method utilizes a short-time Fourier transform to capture the nonstationary characteristics of voltage signals and constructs a compact feature set integrating time-domain, frequency-domain, and time–frequency information for disturbance classification. A supervised learning model is employed to map the extracted features to disturbance categories, while interpretability is achieved through feature contribution analysis, enabling explicit linkage between model decisions and the physical characteristics of PQDs. The proposed approach is validated using a combination of synthetic datasets, simulation data derived from MATLAB/Simulink R2024a microgrid models, and experimentally measured signals from a hardware-based platform. Case study results demonstrate that the proposed framework achieves a high overall classification accuracy of 99.50% across multiple disturbance types, including voltage sag, voltage swell, harmonic distortion, voltage flicker, transient disturbances, and hybrid disturbances. The interpretability analysis further confirms that the identified features are physically consistent with the underlying disturbance mechanisms. Overall, the proposed framework provides an accurate, robust, and interpretable solution for PQD identification, offering practical value for real-time monitoring and intelligent operation of renewable-rich microgrids. Full article

In this paper, we apply the double Fourier transform method to the two-dimensional Vlasov equations for a charged particle subjected to white noise, exponentially correlated Gaussian forces, trap forces and thermal and active noises in a magnetic field. By deriving the corresponding Fokker–Planck equation, analytical solutions for the joint probability density are obtained in different time domains. The mean squared displacement and velocity of a charged particle driven by white noise exhibits a super-diffusive behavior, scaling as ∼t² in the short-time regime, while it grows linearly with time (~t) in the long-time regime, in agreement with numerical simulations of the mean squared displacement. When thermal noise is included together with harmonic trap and viscous forces, the characteristic time scale increases as ~t^2h+1 in the corresponding time domains, whereas the mean squared velocity scales as ~t^2h+3. The moments of the joint probability density under thermal noise scale as ~t^2h+5. Furthermore, when the persistent Hurst exponent h→1/2, the entropy of the joint probability density associated with thermal noise coincides with that obtained for active noise in both the short-time (t ≪ τ) and long-time (t ≫ τ) limits. Full article

Slotless permanent magnet synchronous motors (PMSMs) have recently attracted significant attention for robotic and high-speed machine applications because they eliminate cogging torque and reduce iron loss through the absence of stator teeth. However, removing the stator teeth increases the effective airgap, resulting in extremely low synchronous inductance and introducing electrical challenges such as reduced control stability and increased current harmonics during pulse-width modulation (PWM) operation in inverter drive systems. In this paper, the current harmonic characteristics of a slotless PMSM are investigated with respect to switching frequency. Based on the mathematical model, the effects of switching frequency on a slotless PMSM drive system employing a MOSFET inverter are analyzed. In addition, an experimental setup, including a 700 W slotless PMSM and a MOSFET inverter, is implemented to evaluate the current harmonic characteristics under different switching frequencies of 25 kHz, 50 kHz, and 99 kHz. The total harmonic distortion of current at 99 kHz is reduced by approximately 6.73%p and 3.57%p compared with operation at 25 kHz and 50 kHz, respectively. The experimental results demonstrate the influence of PWM operation on the current characteristics of the slotless PMSM and verify the importance of high switching frequency operation for improving current performance. Full article

The five-phase fault-tolerant consequent-pole permanent-magnet Vernier machine (FTCP-PMVM) has attracted extensive research attention owing to its excellent permanent-magnet utilization while maintaining competitive electromagnetic performance. However, the double-salient structure poses considerable challenges for analysis. The torque generation and power factor characteristics of the FTCP-PMVM are analyzed from a magnetic field modulation perspective in this work. Initially, based on the air gap field modulation effect, the modulation processes of both the permanent-magnet field and the armature field are analyzed. Subsequently, the torque generation mechanism is explained through harmonic matching resulting from the field modulation process, the results demonstrate that the 23rd air gap harmonic dominates the generation of average electromagnetic torque and accounts for the majority of output torque. Furthermore, the power factor is examined in depth by analyzing the reactive power contributed by the machine inductive components (e.g., self-inductance, mutual inductance and leakage inductance) and the active power generated by the permanent-magnet portion, all from the standpoint of field modulation. Finally, a prototype is fabricated to test the machine’s torque, power factor and efficiency. Experimental data confirms the reliability of the theoretical analysis. Full article

Accredited sensory certification is increasingly central to the credibility of EU Geographical Indications (GIs), particularly for wine, where typicity and regional identity complicate harmonization. In the absence of shared descriptors, reference standards, and decision rules, sensory control may produce inconsistent conformity outcomes across certification bodies. This study examines the main drivers and limitations of sensory harmonization in GI wine certification, with particular focus on Portugal’s mandatory batch-level sensory approval system. Using a structured narrative review and comparative analysis, it integrates sensory science literature with the EU regulatory framework requiring verifiable organoleptic characteristics in product specifications. National approaches from Portugal, Croatia, France, Germany, Greece, Italy, Romania and Spain are compared, alongside the harmonized IOC Panel Test model for virgin olive oil. Accreditation is analyzed through International Organization for Standardization standards ISO/IEC 17025 and ISO/IEC 17065, as well as EA guidance. Results show increasing convergence toward formal sensory certification but persistent divergence in how typicity is operationalized and translated into conformity decisions. The study proposes a conceptual framework in which harmonization focuses on evidential conditions rather than uniform sensory identities. Full article

Unbalanced input voltage can significantly affect the electrical behavior of transformer rectifier units (TRUs), especially when a diode open-circuit (OC) fault breaks the original diode conduction symmetry. However, the effect of unbalanced input voltage on the diode OC fault has not been sufficiently clarified from the perspective of a conduction mechanism. This paper analyzes the effect of unbalanced input voltage on diode OC faults in TRUs by establishing a conduction-oriented mechanism. Unbalanced input voltage is divided into two forms, namely, unequal magnitude and phase-shift deviation. The effects on diode conduction boundaries, conduction angles, and conduction intervals are first derived theoretically. Then, using a 12-pulse TRU with $D_{11}$ and $D_{21}$ OC faults as representative cases, current and voltage responses are investigated in both time and frequency domains. The experimental results show that the two forms change diode conduction intervals in different ways. In particular, an unequal magnitude changes the relative driving voltage dominance near the conduction boundaries, resulting in the stretching or compression of diode conduction intervals; phase-shift deviation shifts the angular positions of the driving voltages and modifies the commutation timing. Two forms further aggravate waveform asymmetry and enhance low-order and non-characteristic harmonics under diode OC fault conditions. This effect analysis provides a more comprehensive basis for understanding diode OC fault responses in 12-pulse TRUs and supports the development of more robust diode OC fault diagnosis methods under non-ideal input voltage conditions. Full article

Rapid geographical origin discrimination of Tremella fuciformis is important for quality control and authenticity assessment; however, conventional analytical methods are often time-consuming and require complex sample preparation. In this study, a rapid discrimination approach was established by integrating electronic nose (E-nose) response fingerprints with machine learning. To capture temporal variation in the E-nose signals, fingerprint features were extracted from three response windows: the selected overall response window (0–69 s), the early response window (0–29 s), and the relatively stable response window (56–65 s). Random forest, partial least squares discriminant analysis (PLS-DA), Gaussian naive Bayes, nearest centroid, and decision tree were then constructed and evaluated. Classification performance varied among the temporal-window feature sets. Based on 100 repeated stratified random splits, PLS-DA model using the 56–65 s feature window achieved the best overall classification performance, with accuracy, balanced accuracy, F1-score (the harmonic mean of precision and recall), and ROC-AUC (the area under the receiver operating characteristic curve) values of 0.9933 ± 0.0255, 0.9928 ± 0.0256, 0.9919 ± 0.0293, 0.9991 ± 0.0085, respectively. These findings indicate that E-nose fingerprinting combined with PLS-DA may provide a rapid and effective method for geographical origin discrimination of T. fuciformis. Full article

The study investigates the nonlinear dynamics of a harmonically excited Duffing oscillator coupled with an unforced two-degrees-of-freedom nonlinear energy sink. The external excitation is applied only to the primary oscillator; meanwhile, the NES response is induced through nonlinear internal coupling. The governing nonlinear ordinary differential equations are analyzed using the proposed non-perturbation approach, which does not rely on small-parameter assumptions or Taylor-series expansions. The formulation is used to obtain amplitude-dependent equivalent linear representations and analytical approximations of the coupled system. The analytical results are compared with direct numerical simulations, showing overall agreement with the full nonlinear model. The stability of the steady-state solutions is examined under variations of the main system parameters. The results indicate that the nonlinear coupling and stiffness parameters significantly affect the response amplitudes, stability characteristics, and overall dynamical behavior. Additional analyses using bifurcation diagrams, Lyapunov exponents, Poincaré maps, and basins of attraction reveal transitions between periodic, quasi-periodic, and chaotic regimes, as well as the presence of multi-stability and sensitivity to initial conditions. The proposed framework provides a useful analytical tool in studying the dynamics and stability of nonlinear oscillatory systems over a wide range of operating conditions. Full article

The series-connected chain MMC with DC-blocking capacitor (C-SCMMC) is an emerging topology for HVDC tapping applications with high voltage and relatively low power capacity. However, the DC-blocking capacitor can be bulky and costly, which deteriorates its economy and flexibility. This paper investigates the feasibility of DC-blocking capacitor reduction, with special emphasis on the characteristics, control, and parameter design. The principle of C-SCMMC considering the DC-blocking capacitor dynamics is firstly modeled and analyzed, and the ripples and harmonics, as well as their influences on the external performance of the converter, are analyzed; then, improved control strategies, namely, the grid-tied harmonics suppression and current control, are proposed considering the enlarged DC-blocking capacitor voltage ripple; after that, the influence of reduced DC-blocking capacitor on the operation range and parameter design are analyzed, and the economic advantage is demonstrated via parameter design and comparison based on a typical bench mark. Analysis shows that the DC-blocking capacitor voltage ripple is coupled with other parameters, such as the arm output voltage and SM capacitance, and the advised range is from 0.1 to 0.3 p.u. at unity power factor to reduce the overall cost. In a typical design, the C-SCMMC can reduce the number of SMs by 2/3 and the capacitor energy storage capacity by 15% compared to the conventional MMC. Finally, simulation results obtained in MATLAB/Simulink 2024b are provided to verify the feasibility of the proposed converter and the correctness of the parameter design. Full article