Search Results (141)

This paper presents a control delay compensation method for an LLCL-type active power filter (APF), aimed at improving performance in digital control systems. The proposed strategy is directly integrated into the inner-loop current controller, requiring no additional compensation modules, predictor structures, or capacitor current feedback, which simplifies the control structure and increases flexibility. The method uses real-time internal state responses of the controller to actively compensate for the phase lag caused by digital control delay, effectively maintaining current control accuracy and overall system dynamic stability. Simulation studies based on a 5.5 kW APF system are conducted to verify the effectiveness of the approach. The results show improved current tracking accuracy, stable dynamic behavior under various load conditions. The simulation-based results indicate the potential of the proposed method for improving control accuracy and stability in digitally controlled APF systems. Moreover, very few studies have addressed control delay compensation specifically for LLCL-based APF systems, making this work a valuable contribution to the field. Full article

A contactless passive magnetoelastic sensing setup, recently proposed for detecting pest/substance accumulation in confined spaces (labs, museum reserves), is optimized for enhanced low-frequency performance. The setup uses a short flexible polymer slab, clamped at one end. There, a short Metglas^® 2826MB magnetoelastic ribbon is fixed upon the slab’s surface. The opposite end receives excitation by a remotely controlled module of ultra-low amplitude vibration. When vibrating (with the slab), the ribbon generates magnetic flux, which depends on (and reflects) the slab’s dynamics. This changes when loads accumulate on its surface. The flux induces voltage in a contactless manner in a low-cost pick-up coil suspended above the ribbon. Voltage monitoring allows for evaluation of the vibrating slab’s real-time dynamics and, consequently, the detection of load-induced changes. This work innovates by introducing a low-cost passive circuit for real-time voltage processing, thus achieving an accurate representation of the low-frequency dynamics of the magnetic flux. Furthermore, it introduces an algorithm, which statistically detects load-induced changes using the voltage’s low-frequency power characteristics. Both additions enable load detection at relatively low frequencies, thus addressing a principal issue of passive contactless sensing setups. Extensive testing at different occasions demonstrates promising load detection performance under various conditions, especially given its cost-efficient hardware and operation. Full article

This paper presents a novel open-loop modulation and control strategy for bidirectional, multi-source/load parallel AC-link power converters. While these converters offer advantages such as high-frequency operation and flexible power conversion capabilities, their application to complex systems such as nanogrids presents significant control challenges. Traditional control methods often struggle to efficiently manage power flow and charging/discharging processes, especially when dealing with multiple sources and loads of varying characteristics. To address these issues, this paper proposes a new control strategy that enables intelligent source and load selection while maintaining fast charging and discharging times. Simulation results demonstrate the effectiveness of the proposed approach. This research contributes to advancing the state-of-the-art in power electronics by providing a foundation for improved control of complex power conversion systems for renewable energy applications. Full article

The growing complexity of distribution-level virtual power plants (VPPs) demands a rethinking of how flexible demand is modeled, aggregated, and dispatched under uncertainty. Traditional optimization frameworks often rely on deterministic or homogeneous assumptions about end-user behavior, thereby overestimating controllability and underestimating risk. In this paper, we propose a behavior-aware, two-stage stochastic dispatch framework for VPPs that explicitly models heterogeneous user participation via integrated behavioral economics and social interaction structures. At the behavioral layer, user responses to demand response (DR) incentives are captured using a Prospect Theory-based utility function, parameterized by loss aversion, nonlinear gain perception, and subjective probability weighting. In parallel, social influence dynamics are modeled using a peer interaction network that modulates individual participation probabilities through local contagion effects. These two mechanisms are combined to produce a high-dimensional, time-varying participation map across user classes, including residential, commercial, and industrial actors. This probabilistic behavioral landscape is embedded within a scenario-based two-stage stochastic optimization model. The first stage determines pre-committed dispatch quantities across flexible loads, electric vehicles, and distributed storage systems, while the second stage executes real-time recourse based on realized participation trajectories. The dispatch model includes physical constraints (e.g., energy balance, network limits), behavioral fatigue, and the intertemporal coupling of flexible resources. A scenario reduction technique and the Conditional Value-at-Risk (CVaR) metric are used to ensure computational tractability and robustness against extreme behavior deviations. Full article

Perovskite solar cells (PSCs) rarely report, on a single-device platform, concurrent gains in optoelectronic efficiency and buried-interface mechanical robustness—two prerequisites for flexible and roll-to-roll (R2R) integration. We engineered a nanoplate-structured fluorine-doped tin oxide (NP-FTO) front electrode that couples light management with three-dimensional interfacial anchoring, and we quantified both photovoltaic (PV) and nanomechanical metrics on the same device stack. Relative to planar FTO, the NP-FTO PSCs achieved PCE of up to 25.65%, with simultaneous improvements in Voc (to 1.196 V), Jsc (up to 26.35 mA cm⁻²), and FF (to 82.65%). Nanoindentation revealed a ~28% increase in reduced modulus and >70% higher hardness, accompanied by a ~32% reduction in maximum indentation depth, indicating enhanced load-bearing capacity consistent with the observed FF gains. The low-temperature, solution-compatible NP-FTO interface is amenable to R2R manufacturing and flexible substrates, offering a unified route to bridge high PCE with reinforced interfacial mechanics toward integration-ready perovskite modules. Full article

This research presents the design and implementation of a cascade Proportional–Integral (PI) controller tailored for a Variable Air Volume (VAV) system that was specially created and executed particularly for hospital operating rooms. The main goal of this work is to make sure that the temperature and positive pressure stay within the limits set by ASHRAE Standard 170-2017. This is necessary for patient safety, surgical accuracy, and system reliability. The proposed cascade design uses dual-loop PI controllers: one loop controls the temperature based on user-defined setpoints by local control touch screen, and the other loop accurately modulates the differential pressure to keep the pressure of the environment sterile (positive pressure). The system works perfectly with Building Automation System (BAS) parts from Automated Logic Corporation (ALC) brand, like Direct Digital Controllers (DDC) and Web-CTRL software with Variable Frequency Drives (VFDs), advanced sensors, and actuators that give real-time feedback, precise control, and energy efficiency. The system’s exceptional responsiveness, extraordinary stability, and resilient flexibility were proven through empirical validation at the Korean Iraqi Critical Care Hospital in Baghdad under a variety of operating circumstances. Even during rapid load changes and door openings, the control system successfully maintained the temperature between 18 and 22 °C and the differential pressure between 3 and 15 Pascals. Four performance scenarios, such as normal (pressure and temperature), high-temperature, high-pressure, and low-pressure cases, were tested. The results showed that the cascade PI control strategy is a reliable solution for critical care settings because it achieves precise environmental control, improves energy efficiency, and ensures compliance with strict healthcare facility standards. Full article

The increasing deployment of photovoltaic-storage systems in distribution-level microgrids introduces a critical control conflict: traditional maximum power point tracking algorithms aim to maximize energy harvest, while grid-forming inverter control demands real-time power flexibility to deliver frequency and inertia support. This paper presents a novel two-layer co-optimization framework that resolves this tension by integrating adaptive traditional maximum power point tracking modulation and virtual synchronous control into a unified, grid-aware inverter strategy. The proposed approach consists of a distributionally robust predictive scheduling layer, formulated using Wasserstein ambiguity sets, and a real-time control layer that dynamically reallocates photovoltaic output and synthetic inertia response based on local frequency conditions. Unlike existing methods that treat traditional maximum power point tracking and grid-forming control in isolation, our architecture redefines traditional maximum power point tracking as a tunable component of system-level stability control, enabling intentional photovoltaic curtailment to create headroom for disturbance mitigation. The mathematical model includes multi-timescale inverter dynamics, frequency-coupled battery dispatch, state-of-charge-constrained response planning, and robust power flow feasibility. The framework is validated on a modified IEEE 33-bus low-voltage feeder with high photovoltaic penetration and battery energy storage system-equipped inverters operating under realistic solar and load variability. Results demonstrate that the proposed method reduces the frequency of lowest frequency point violations by over 30%, maintains battery state-of-charge within safe margins across all nodes, and achieves higher energy utilization than fixed-frequency-power adjustment or decoupled Model Predictive Control schemes. Additional analysis quantifies the trade-off between photovoltaic curtailment and rate of change of frequency resilience, revealing that modest dynamic curtailment yields disproportionately large stability benefits. This study provides a scalable and implementable paradigm for inverter-dominated grids, where resilience, efficiency, and uncertainty-aware decision making must be co-optimized in real time. Full article

Ethnic minority embroidery from Guizhou is an important part of Chinese culture, reflecting the history, beliefs, and artistic traditions of the region’s diverse ethnic groups. However, challenges in automatic recognition arise due to data scarcity, complex textures, and the flexibility of handmade designs. This study constructs the Guizhou Province Intangible Cultural Heritage Embroidery dataset and proposes an improved MobileViT-DDC model to address the issues of complex textures and data scarcity. The model integrates Dilatefomer, Deformable Dilatefomer (DefDilatefomer), and Context Broadcasting Module (CBM) to capture local details and global information in embroidery patterns. Experimental results show that the MobileViT-DDC model achieves an accuracy of 98.40% on the Guizhou embroidery dataset (a 2.17% improvement over the original baseline model) with a 14% reduction in computational load; on the Pakistani National Dress Dataset, it reaches an accuracy of 79.07%, representing a 2.63% increase compared to the original baseline model of the same scale. This study is the first to apply a CNN-ViT hybrid model to ethnic embroidery recognition, providing a new solution for the digital preservation of cultural heritage. The model’s cross-cultural adaptability was further validated through its application to the Pakistani National Dress dataset. Full article

Among other uses, DC-DC converters are employed in the auxiliary power modules (APMs) of electric vehicles (EVs), connecting the high-voltage traction battery to the low-voltage auxiliary system (AS). Traditionally, the APM is an isolated two-port, two-level (2L) DC-DC converter, and the auxiliary loads are fed at a fixed voltage level, e.g., 12 V in passenger cars. Dual-active-bridge (DAB) converters are commonly used for this application, as they provide galvanic isolation, high power density and efficiency, and bidirectional power flow capability. However, the auxiliary loads do not present a uniform optimum supply voltage, hindering overall efficiency. Thus, a more flexible approach, providing multiple supply voltages, would be more suitable for this application. Multiport DC-DC converters capable of feeding auxiliary loads at different voltage levels are a promising alternative. Multilevel neutral-point-clamped (NPC) DAB converters offer several advantages compared to conventional two-level (2L) ones, such as greater efficiency, reduced voltage stress, and enhanced scalability. The series connection of the NPC DC-link capacitors enables a multiport configuration without additional conversion stages. Moreover, the modular nature of the ML NPC DAB converter enables scalability while using semiconductors with the same voltage rating and without requiring additional passive components, thereby enhancing the converter’s power density and efficiency. This paper proposes a modulation strategy and decoupled closed-loop control strategy for the generalized multiport 2L-NL NPC DAB converter interfacing the EV traction battery with the AS, and its performance is validated through hardware-in-the-loop testing and simulations. The proposed modulation strategy minimizes conduction losses in the converter, and the control strategy effectively regulates the LV battery modules’ states of charge (SoC) by varying the required SoC and the power sunk by the LV loads, with the system stabilizing in less than 0.5 s in both scenarios. Full article

This research investigates the interaction between a flexible thin-walled hemisphere and the surrounding wake at $R{e}_D=2\times {10}^5$ acting as a simplified model of a flexible surface protuberance immersed within a turbulent boundary layer (BL). A flexible model and a rigid model, both 100 mm in diameter, are experimentally tested to observe and contrast the flow variation between a rigid structure and a freely deforming structure. Two experiments were conducted. To capture fluid flow behaviour, stereo particle image velocimetry (SPIV) was used. To capture structural deformation of the model, digital image correlation (DIC) was utilised. Experimental testing was conducted non-simultaneously. From the experimental testing, it was observed that the flexible model experienced a leading edge (LE) deformation at $29°$ of the altitude angle ($\theta$), showing an average deformation of $2.11$ mm. All regions of the structure experienced non-zero distortion due to the incoming wind load. This was similar to behaviour observed in previous literature. This caused a modulation in the wake region, giving a parabolic wake velocity contour to form about $\theta \approx 20°$. A velocity inflection point is observed for the flexible model at an average of $\theta =23.39°$ within the wake. This inflection region extends surrounding the area of maximum structural deflection up to $\theta \approx 40°$. This indicates that the deflection across the LE centreline has a direct interaction with location and size of the near wake. Turbulent kinetic energy (TKE) in the wake was observed to drop with the introduction of the flexible model, with a lower dissipation rate observable. This is indicative of energy transfer from the flow to the structure, allowing deformation. The maximum region of TKE coincides with the recirculation vortex core region, which was shown to move from $z/D=$ 0.19 to $z/D=$ 0.35 for the rigid and flexible models, respectively. The results indicate that, with the Reynolds number tested, the rigid behaviour is in line with previous literature trends. The flexibility of the model, therefore, highly influences the wake region, with general shape deformation causing a decrease in near wake TKE and change in wake shape and recirculation core location. Full article

Currently, soft robots face challenges such as low motion efficiency, susceptibility to damage in traditional silicone materials, and difficulty in achieving reproducible manufacturing. To address these issues, we integrate flexible film materials with modular design principles and apply them to soft robotics. Based on the concept of modularity, this study simplifies and decomposes the robot’s motion into three fundamental modules: a thin-film elongation actuator module, a thin-film deflection actuator module, and a connection module. Inspired by the Miura-fold origami technique and traditional lantern contraction, the elongation actuator is designed to produce axial extension of varying lengths under different air pressures. The deflection actuator is modeled after the head expansion mechanism of the pelican eel, enabling deflection movement. The connection module integrates the elongation and deflection modules into a unified structure. The research results show that the elongation actuator achieves an extension length of 118 mm under 50 kPa and can pull a 500 g load during horizontal contraction. The two-layer deflection actuator achieves a deflection angle of 56° at 40 kPa, while the three-layer version reaches 98°. For further demonstration, we subsequently conducted peristaltic soft robot experiments and obstacle avoidance experiments. This study holds significant potential for the development of next-generation multifunctional soft robots. Full article

The first ray plays a fundamental role in foot biomechanics, particularly in stabilizing the medial longitudinal arch and enabling efficient weight transfer during the mid-stance and propulsion phases of gait. When dorsiflexed—a condition known as metatarsus primus elevatus—especially in its flexible form, this structure disrupts load distribution, impairs propulsion, and contributes to various clinical symptoms. Despite its clinical importance, the biomechanical impact of orthotic elements placed beneath the first ray remains underexplored. This study aimed to quantify the variations in medio-lateral (Fx), antero-posterior (Fy), and vertical (Fz) force vectors generated during gait in response to different orthotic elements positioned under the first ray. A quasi-experimental, post-test design was conducted involving 22 participants (10 men and 12 women) diagnosed with flexible metatarsus primus elevatus. Each participant was evaluated using custom-made insoles incorporating various orthotic elements, while gait data were collected using a dynamometric platform during the mid-stance and propulsion phases. Significant gait-phase-dependent force alterations were observed. A cut-out (E) reduced medio-lateral forces during propulsion (p < 0.05), while a kinetic wedge (F) was correlated with late-stance stability (r = −0.526). The foot posture index (FPI)/body mass index (BMI) mediated the vertical forces. The effect sizes reached 0.45–0.42 for antero-posterior force modulation. Phase-targeted orthoses (a cut-out for propulsion, a kinetic wedge for late stance) and patient factors (FPI/BMI) appear to promote biomechanical efficacy in metatarsus primus elevatus, enabling personalized therapeutic strategies. Full article

This paper presents a novel design for a bionic knee exoskeleton equipped with a variable stiffness actuator based on rope-driven artificial muscles. To meet the varying stiffness requirements of the knee joint across different gait modes, the actuator dynamically switches between multiple rope bundle configurations, thereby enabling effective stiffness modulation. A mathematical model of the knee exoskeleton is developed, and the mechanical properties of the selected flexible aramid fiber ropes under tensile loading are analyzed through both theoretical and experimental approaches. Furthermore, a control framework for the exoskeleton system is proposed. Wearable experiments are conducted to evaluate the effectiveness of the variable stiffness actuation in improving compliance and comfort across various gait patterns. Electromyography (EMG) results further demonstrate that the exoskeleton provides a compensatory effect on the rectus femoris muscle. Full article

In this study, zinc–tin oxide (ZTO) thin films were prepared via radio-frequency magnetron sputtering to examine the influence of annealing temperature on the performance of thin-film transistors (TFTs) and their resistive-load inverters. The findings reveal that annealing modulates the concentration and spatial distribution of oxygen vacancies (V_O), which directly affect carrier density and interface trap density, ultimately determining the electrical behavior of inverters. At the optimal annealing temperature of 600 °C, the V_O concentration was effectively moderated, resulting in a TFT with a mobility of 12.39 cm² V⁻¹ s⁻¹, a threshold voltage of 6.13 V, an on/off current ratio of 1.09 × 10⁸, and a voltage gain of 11.77 in the corresponding inverter. However, when the V_O concentration deviated from this optimal range, whether in excess or deficiency, the gain was reduced and power consumption increased. This V_O engineering strategy enables the simultaneous optimization of both TFT and inverter performance without relying on rare elements, offering a promising pathway toward the development of low-cost, large-area, flexible, and transparent electronic devices. Full article

Very large floating structures (VLFSs) typically employ a modular design approach to mitigate significant hydroelastic loads. A mooring system is commonly employed to maintain the position and heading of a VLFS against the forces of waves, wind, and currents, while a connector is utilized to restrict the relative motion among the modules. In this paper, we propose a comprehensive connector model based on elastic beam theory. The aim is to establish a unified mathematical model that accommodates various types of flexible connectors by adjusting the specific stiffness and damping parameters. To assess the effectiveness of the model, numerical and experimental studies are conducted on a VLFS composed of three rigid bodies connected in a series by multiple flexible connectors. The results obtained demonstrate that the general connector model is reasonable and can be applied to different types of connectors, thereby facilitating an analysis of the influence of the mechanical properties of the connectors on the motion response of the VLFS. Full article