Search Results (1,738)

Nowadays, numerical simulation methods are advanced and widely used in industry, enabling the modeling of complex systems from printed circuit boards (PCBs) to full power converters. Among many isolated topologies, the phase-shift full-bridge (PSFB) topology is a well-established solution for isolated DC–DC conversion in electric vehicles. Therefore, this paper proposes a broadband electromagnetic compatibility (EMC) modeling methodology for a custom-designed 1 kW gallium nitride (GaN)-based PSFB converter intended for an electric vehicle (EV) DC powertrain. Moreover, the approach combines full-wave electromagnetic simulation with circuit-level simulation, including parasitic effects from PCB layout, power harnesses, and discrete components. Thus, the virtual prototype is assessed within a complete virtual test bench compliant with the standard Comité International Spécial des Perturbations Radioélectriques (CISPR) 25 over the 150 kHz–108 MHz range to capture common-mode (CM) and differential-mode (DM) conducted electromagnetic interference (EMI). Results show that the converter achieves efficiencies of 97.26% in standalone mode and 97.03% when integrated into the full DC powertrain. However, the conducted EMI assessment reveals that both CM and DM emissions exceed CISPR 25 Class 2 limits across the entire spectrum, with excess levels reaching up to 72 dBµV. Therefore, power harnesses significantly increase EMI levels at low frequencies due to the distributed inductance and stray capacitance. Finally, this study demonstrates the value of virtual prototyping for simulation-based EMI prediction in early-stage power converter design. Full article

Photoplethysmography (PPG) is a widely used non-invasive optical technique for assessing cardiovascular dynamics and related hemodynamic processes. However, conventional noise-reduction methods can alter signal timing and distort waveform morphology, thereby affecting the identification of physiologically relevant events. Here, we propose a frequency-domain Gaussian filtering framework for selectively extracting harmonics from PPG signals. The method combines a Gaussian band-reject filter centered at 0 Hz to suppress the dominant DC component, reduce the non-pulsatile baseline, and attenuate low-frequency contributions associated with slow modulation processes. Symmetric Gaussian bandpass filters are then applied to isolate harmonic components, with the number of retained bands adapted to the requirements of a given application. As a proof of concept, the framework was applied to both a simulated PPG waveform and an experimental PPG recording. Because of the symmetric zero-phase properties of the filters, the temporal alignment of key PPG events, including the systolic peak, diastolic decay, and dicrotic notch, can be preserved while phase distortion is avoided. Reconstruction from filtered harmonics further suggests that low-order harmonics retain much of the observable waveform structure in the signals analyzed. Overall, this harmonic-based Gaussian filtering provides a promising framework for analysis of PPG signals and motivates further investigation of its potential for extracting physiologically related information from harmonic components, such as bedside monitoring. Full article

Applying functional hard protective coatings with friction-reducing and wear-resistant properties to optimize mechanical surfaces and interfaces can significantly enhance the reliability of operating components under extreme conditions and extend their service life. However, the difference of coating preparation technology often leads to great uncertainty in the improvement of the performance and lifetime of functional hard protective coatings. Hence, in this work, TiAlSiCN coatings were deposited at the substrate temperature of 300 °C by varying the C target power from 0 to 900 W using combined high-power impulse magnetron sputtering and pulsed DC magnetron sputtering. The TiAlSiCN coatings deposited at a C target power of 500 W containing the mixed phase of nc-TiAl(C)N, a-Si₃N₄ and a-C exhibit a simultaneous superhardness of 43.5 GPa and favorable toughness, benefiting from the fully dense microstructure and high surface integrity. The superhard TiAlSiCN coatings show excellent friction-reducing and wear-resistant properties with a low friction coefficient of about 0.1 and specific wear rate of 2.78 × 10⁻⁷ mm³·N⁻¹·m⁻¹ under dry reciprocating friction and wear tests. The improved friction and wear performance of TiAlSiCN coatings are mainly attributed to the increased cracking resistance and oxide-based films covering the superhard surface/interface. Full article

Obesity prevalence has increased globally, and metabolic bariatric surgery (MBS) is the most effective treatment for severe obesity. However, the impact of postoperative dietary counselling (DC) on clinical outcomes including weight is unclear. This review aims to assess the nature and impact of postoperative DC delivered by dietitians on clinical outcomes in adults undergoing post-MBS, focusing on weight change as the primary outcome, and body composition, nutritional status, biochemical parameters, and complications as secondary outcomes. Five databases (Medline, Embase, Web of Science, CINAHL, and Cochrane Library) were searched for observational studies and randomised controlled trials (RCTs) assessing DC related to weight change. Thirteen studies met the inclusion criteria (five RCTs and eight observational studies), involving 4173 individuals. Eight studies reported no significant difference in weight outcomes between the groups receiving DC and comparison groups. However, secondary outcomes such as nutritional status, complications, and levels of transferrin saturation, vitamin B12, and vitamin D showed improvements with more frequent DC. The components of DC delivered by dietitians varied, including advice on micronutrient supplements, protein intake, physical activity, transition diets, healthy eating, and mindful eating. Evidence supporting the efficacy of postoperative DC in promoting weight loss is limited by short-term assessment and inconsistencies in reporting weight outcomes, highlighting the need for long-term RCTs to ascertain its effectiveness. Full article

Zinc oxide (ZnO) varistors are a core component of surge arresters; their failure can directly affect the secure and reliable operation of power equipment. Therefore, this paper conducts an impulse degradation test on ZnO varistors, combining electrical and microstructural tests to systematically explore the intrinsic correlation mechanism between the electrical properties and microstructural characteristics. Test results show that this type of ZnO varistor is susceptible to side-glaze surface flashover under an impulse current with a waveform of 8/20 μs and an amplitude of 27 kA, and the discharge branches exhibit an extension from the negative electrode towards the positive electrode. Moreover, surface flashover causes the formation of local conductive channels in the side glaze layer, resulting in a significant drop in the direct-current (DC) reference voltage U_1mA. However, the residual voltage U_10kA increases slightly with an increase in the number of impulse groups, with a change in amplitude of less than 1.5%. Additionally, the microstructural testing reveals that the impulse currents cause the bismuth (Bi) element in ZnO grains to precipitate and form more Bi-rich phases at the grain boundaries. This results in an increase in the thickness of the grain boundary layer, which is negatively correlated with the U_1mA. Meanwhile, the grain morphology and size distribution of brand-new samples, samples with different degrees of degradation, and samples with side-glaze surface flashover damage are not significantly different. This is consistent with the fact that the change range of the residual voltage U_10kA during impulse degradation is very small. This test phenomenon indicates that the failure of this type of ZnO varistor to withstand an impulse current with a waveform of 8/20 μs and an amplitude of 27 kA is mainly due to changes in the volt-ampere properties of the small-current regions caused by ion migration within the grain boundary layer. This research provides an experimental basis and theoretical support for improving the impulse withstand capacity of ZnO varistors in their design. Full article

This paper reports the development of a Class-A amplifier that operates at 50 MHz and 400 °C. The amplifier utilizes a commercially available 4H-SiC static induction transistor (SIT) as the active device and incorporates input/output-matching networks to optimize amplifier operation and DC bias networks, which comprise thin-film spiral inductors, metal–insulator–metal (MIM) capacitors, and thick-film chip resistors. All passive components were tested at frequency and temperature prior to amplifier development and are reported. A small-signal SiC SIT model that was developed in Keysight’s Advanced Design System (ADS 2023) software suite was used to design and optimize the amplifier’s performance. The SiC SIT amplifier’s S-parameters were recorded for frequencies between 20 and 100 MHz over a temperature range of 25 °C to 400 °C, exhibiting a gain (S₂₁) of approximately 15.8 and 5.80 dB at 25 °C and 400 °C, respectively. The input and output reflection coefficients at 50 MHz and 400 °C were −18.5 and −15.2 dB, respectively. The noise figure and phase noise were measured at temperatures between 25 °C and 400 °C. At 50 MHz, the noise figure increased by only 21% over the temperature range, while the 1 kHz offset of the phase noise remained below −110 dBc/Hz. The stability factor, K, calculated using both measured and simulated data, demonstrates unconditional stability over the frequency range at 400 °C. Lastly, the 1 dB compression point was measured at 50 MHz and 400 °C with an approximated output of 9.5 dB. Simulated and measured results are presented and show the model is within 10% error at 400 °C. Full article

Image enhancement is of pivotal importance in the detection of defects in wood veneers. However, acquired images frequently exhibit signs of blurring, uneven illumination, and insufficient contrast, which can lead to a reduction in the accuracy of defect recognition. In this study, an algorithm based on Grünwald–Letnikov (G–L) fractional-order differentiation is proposed for the enhancement of wood veneer defect images. Initially, the gain characteristics of differential amplitude-frequency responses on high- and low-frequency image components are analyzed, and the feasibility of the method is demonstrated by linking these characteristics with the frequency-domain distributions of live knot, dead knot, and crack defects. Secondly, an eight-direction mask operator is constructed based on the G–L definition, and a DC component preservation factor is introduced to eliminate the luminance drift caused by mask truncation. The application of the mask is performed independently on the R, G, and B channels, and a dynamic blending mechanism is designed to achieve a balance between texture enhancement and structural fidelity. Finally, a set of six evaluation metrics (AG, E, PSNR, RMSE, SSIM, and VIF) is employed to assess the quality of enhanced images. The proposed algorithm is then compared with five existing algorithms (SSR, MSR, MSRCR, CLAHE, and AGC) under both noise-free and additive white Gaussian noise conditions. The findings indicate that the G–L fractional-order differentiation algorithm facilitates a more balanced representation of image features, thereby enhancing contrast, brightness, and textural contours. This approach results in more authentic color reproduction and superior visual quality. Full article

This paper presents a hybrid methodology for the creation of educational mobile robots, combining the efforts of developers in design, construction, and instrumentation with the use of “Vibe Coding” as an alternative programming approach. To achieve this objective, the methodology integrates electronics and algorithmic thinking to enable adaptive behavior across three operating modes for robotics competitions. The mobile robot features a compact and modular architecture (430 g, 22 cm length × 14 cm width) with support components manufactured using 3D printing. Instrumentation included an Arduino Uno^® development board, a Syb-170^® proto shield, a buzzer, an HC-SR04^® ultrasonic sensor, an SG90 RC^® servomotor, a SSD1315 display, three TCRT5000^® reflective optical sensors, two DC motors with integrated 48:1 gearboxes, an L298N motor driver, and two 18650^® rechargeable lithium-ion batteries. Programming and algorithmic implementation were carried out using Vibe Coding, leveraging its intuitive environment to accelerate the development of three independent operating modes: (1) line follower on a racetrack, (2) obstacle avoidance with various objects, and (3) Bluetooth control via the free MIT Application Inventor. The mobile robot successfully demonstrated all three tasks, validating its suitability for educational and competitive purposes. Furthermore, its architecture supports AI-assisted decision-making through Vibe Coding, enabling dynamic responses to environmental disturbances. The multimodal configuration enhances navigation by correcting trajectory deviations, thereby improving robustness, adaptability, and overall functionality. Full article

The UHV dry-type bushing plays a critical role in power transmission by enabling electrical connection, electrical insulation, and mechanical support, making it a core component for ensuring the safe and stable operation of UHV direct current (DC) transmission projects. Epoxy resin, serving as the fundamental insulating material for the bushing core, undergoes significant residual strain during high-temperature curing due to chemical shrinkage and thermal strain, which directly affects the molding quality and service reliability of the component. This paper investigates the curing process of a large-thickness epoxy material, which is on the same scale as a UHV bushing. An in situ monitoring system combining fiber Bragg grating (FBG) sensors and thermocouples, together with COMSOL Multiphysics simulations, is employed to systematically study the evolution of the temperature field and residual strain throughout the entire curing process, considering the demolding effect. The results show that during the curing stage, the internal temperature distribution is non-uniform, with a maximum temperature difference of 65 °C between the center and the edge. The residual strain is dominated by chemical shrinkage (accounting for 73.25%) and exhibits a pronounced radial gradient. Mold constraint and demolding cause abrupt changes in the strain. The developed thermo-chemo-mechanical coupled model shows good agreement between simulations and experimental measurements. Thermal cycling relaxes the residual stress, achieving a reduction of 3.89–5.77%. This study provides support for process optimization and defect prevention in large-scale epoxy insulation components. Full article

Dense direct-current (DC) bias routing and numerous radio-frequency (RF) choke inductors pose major challenges to the practical implementation of phase-shifter-free beam steering using PIN-controlled phase switching. To address this issue, a compact vertical DC biasing network is proposed, in which most DC bias lines are routed beneath the ground plane. The DC signals are fed to the PIN diodes through vertical bias lines passing through metallized vias in the dielectric substrate. This arrangement reduces routing congestion and simplifies array-level bias integration. The number of required RF choke inductors is decreased from 112 to 22 per dual-polarized element while preserving the required beam-steering functionality. For experimental validation, a 1 × 3 prototype operating at 3.5 GHz is fabricated and measured. The measured beam directions of −14°, 0°, and +14° agree well with simulations, confirming that the proposed bias network provides the phase control required for beam steering. The proposed network, therefore, offers a compact, low-complexity, and practical solution for scalable phase-shifter-free beam-steering systems. Full article

Edible flowers are important components of traditional food systems and biocultural practices in southern China, yet their ethnobotanical significance remains poorly documented. This study investigated the diversity, traditional uses, and cultural importance of edible flowers in Baise City through semi-structured interviews, market surveys, and field observations with local informants. Quantitative ethnobotanical indices, including the Cultural Food Significance Index (CFSI), Fidelity Level (FL), and Informant Consensus Factor (ICF), were applied to evaluate cultural and medicinal importance. A total of 96 edible flower taxa belonging to 77 genera and 44 families were documented. Most species were native to China, herbaceous in growth form, and collected from wild habitats. Inflorescences were the most commonly utilized floral organs. Edible flowers were used as vegetables, herbal teas, medicinal edible plants, natural food colorants, condiments, desserts, and snack foods. Species such as Emilia sonchifolia (L.) DC., Plantago asiatica L., and Solanum americanum Mill. showed high cultural significance. A total of 64 taxa were recognized as medicinal edible plants, and high ICF values indicated strong agreement among informants regarding ethnomedicinal uses. These findings demonstrate the important roles of edible flowers in local food systems, traditional healthcare, and biocultural heritage, emphasizing their relevance for biodiversity conservation and sustainable food practices. Full article

Background: Cancer stem cells (CSCs) contribute to hepatocellular carcinoma (HCC) progression and therapeutic resistance. Natural products with antioxidant and bioactive properties may offer novel strategies to suppress CSC-driven tumorigenesis. Methods: We investigated the effects of unfermented and fermented Alnus japonica bark extracts on CSC-like rG2-DC-1C cells. Cell proliferation, invasion, and xenograft tumor formation were assessed, and autophagy/apoptosis markers were analyzed. Results: Bark extracts reduced OCT4 expression, suppressed CSC proliferation and invasion, and inhibited xenograft tumor formation. Mechanistically, extracts activated BAK-dependent autophagy, evidenced by LC3B accumulation and p62 modulation, whereas diarylheptanoids Hirsutenone (Hir) and Oregonin (Ore) primarily induced apoptosis via Caspase-3 cleavage. Blocking autophagy with chloroquine or BAK knockdown reversed the anti-invasive effects of bark extracts, confirming BAK’s role in CSC suppression. Component analysis suggests quercetin contributes to autophagy induction, though synergistic effects of other constituents remain possible. Conclusions: Together, these findings indicate that Alnus japonica bark extracts suppress CSC-driven liver tumorigenesis through autophagy, while Hir and Ore act via apoptosis, highlighting complementary mechanisms that broaden the therapeutic potential of this traditional medicinal plant and support further preclinical validation. Full article

Firms increasingly coordinate lot-sizing, distribution center (DC) location, and joint replenishment over time to reduce costs. This paper studies this integrated problem under the (R, S) policy with demand, which stochasticity varies from period to period. We build a model where only the timing of replenishment is the core decision; all else follows from it. To solve efficiently, we design a hybrid differential evolution algorithm with a random neighborhood search. Experiments show our algorithm outperforms eight benchmark methods in solution quality and speed. A sensitivity analysis reveals how key parameters affect the total cost, replenishment frequency, and the number of DCs. Higher ordering costs reduce replenishment frequency, and larger DC setup costs lead to fewer DCs. However, fewer DCs do not always lower the total cost—when dealers are geographically dispersed, more DCs can reduce the overall total system cost. These insights help managers balance the cost components in a supply chain network design. Full article

Lectin receptor-like kinases (LecRLKs) are a large subfamily of receptor-like kinases (RLKs), and their N-terminal lectin domain is predicted to reversibly bind to carbohydrates. Within this family, G-type LecRLKs represent a distinct subclass defined by an extracellular S-locus glycoprotein (SLG) domain, which was originally identified for its role in governing self-incompatibility in Brassica species. Emerging evidence suggests that G-type LecRLKs are involved in plant immunity; however, only a small fraction have been functionally characterized, leaving the roles of most family members largely unknown. In this study, we identified RK3 (Receptor Kinase 3) as the most strongly induced gene within the G-type LecRLK clade VI upon infection with Pseudomonas syringae pv. tomato DC3000 (Pst DC3000). Through both gain- and loss-of-function analyses, we demonstrated that RK3 positively regulates flg22-induced immune signaling events, including oxidative burst and mitogen-activated protein kinase (MAPK) activation, as well as downstream responses such as defense gene expression and ethylene production. Remarkably, the immune-enhancing activity of RK3 does not require its kinase domain. Critically, both full-length RK3 and a kinase-deleted variant (RK3-ΔK) constitutively interact with FLS2 (Flagellin-Sensing 2) and BAK1 (BRASSINOSTEROID INSENSITIVE 1-associated receptor kinase 1). This provides direct evidence that RK3 functions primarily as a co-regulatory component within the PRR complex, independent of its kinase activity. Moreover, ectopic expression of RK3 in tomato enhanced resistance to Pst DC3000, highlighting its potential utility in engineering disease resistance in crops. Thus, RK3 reveals a non-canonical, kinase-independent mechanism by which a G-type LecRLK potentiates plant immunity, expanding our understanding of RLK signaling complexity. Full article

This paper proposes a new single-stage bipolar Boost DC/DC converter topology, hereafter referred to as the Full-bridge Boost converter. The proposed architecture enables the generation of a bipolar output voltage with a magnitude equal to or greater than the input voltage, reducing the passive component count. Specifically, a single inductor and a single capacitor are employed, in conjunction with a full-bridge structure and auxiliary switches, to achieve both voltage boosting and polarity inversion within a unified conversion stage. A comprehensive switching configuration is presented, and a mathematical model based on the system switching dynamics is derived. Furthermore, the steady-state behavior is analyzed, yielding an explicit expression for the voltage gain as a function of the control input. In addition, ripple analysis and continuous conduction mode (CCM) boundary conditions are derived to establish design constraints for the converter operation. The characteristic waveforms under both CCM and discontinuous conduction mode (DCM) operation are also analyzed. The validity of the proposed topology and its mathematical representation is verified through MATLAB/Simulink simulations. The detailed switching-level converter is implemented using the Simscape Electrical environment, and the numerical results of the averaged model are compared against the circuit-level simulation through waveform analysis and root mean square error (RMSE) indices to assess modeling accuracy. Finally, implementation feasibility considerations, including semiconductor stress, dead-time requirements, conduction and switching losses, and efficiency analysis, are discussed. Full article