Search Results (8,736)

Enzyme-assisted carbon capture is attracting massive interest, and absorbents composed of aqueous carbonate supplemented with carbonic anhydrase have proven particularly promising. Here, we study basic capture mechanisms using a novel approach grounded in comparative enzymology. We determined initial, steady-state capture rates in potassium carbonate under a range of conditions and observed a characteristic saturation behavior at high concentrations of either enzyme or CO₂. These results could be rationalized by a modified Michaelis–Menten framework applied to a “reaction zone” near the liquid surface. Capture rates corresponded directly to enzyme reaction rates in the reaction zone as determined by K_M and k_cat, and this explained the observed saturation behavior. The kinetic data suggested a depth of the reaction zone of about 20 µm. This meant that equilibrium between CO₂ and HCO₃⁻ was obtained within this shallow film and that enzymes deeper in the liquid had little or no influence on capture rates. This approach also allowed us to rationalize the effect of pH on enzyme-assisted capture rates. Overall, steady-state kinetics can be used in comparative and mechanistic analyses of enzyme-accelerated carbon capture. The approach is theoretically simple, requires limited experimental input, and offers key molecular insights. Full article

Recent space missions demand higher pointing accuracy, smoother attitude transitions and lower energy consumption than those typically achievable with conventional control approaches. This motivates the exploration of intelligent and nonlinear control methods. The FuzzyBuzz experiment investigates the application of fuzzy logic for spacecraft attitude control using NASA’s Astrobee robotic system aboard the International Space Station. Unlike traditional control methods, fuzzy logic introduces a rule-based approach capable of handling uncertainties and nonlinearities inherent in space environments, making it particularly suited for autonomous operations in microgravity. The objective of FuzzyBuzz is to evaluate the effectiveness of fuzzy controllers compared to traditional linear ones, such as Proportional–Integral–Derivative (PID) and $H_{\infty }$ controllers. In addition, a comparison with a nonlinear controller based on a Model Predictive Control (MPC) strategy is considered. The controllers will be tested through predefined attitude maneuvers, evaluating precision, energy efficiency, and real-time adaptability. This work presents the design of the FuzzyBuzz experiment, including the software architecture, simulation environment, experiment protocol, and the development of a fuzzy logic-based attitude control system for Astrobee robots. The proposed fuzzy controller and a PID controller are optimized using a Multi-Objective Particle Swarm Optimization (MOPSO) method, providing a range of operational points with different trade-offs between two metrics, related to convergence time and energy consumption. Results show that the PID controller is better suited for scenarios demanding low convergence times, whereas the fuzzy controller provides smoother responses, reduced steady-state error, and maintains convergence under significant parametric uncertainties. Results from $H_{\infty }$ and MPC controllers will be reported once the in-orbit experiment is performed. Full article

To address the low efficiency of tetracycline (TC) ozonation caused by low ozone solubility, short aqueous half-life, and mass-transfer limitations, an ozone micro-nano bubble (O₃-MNBs) oxidation system was designed and systematically compared with conventional ozone sparging (Conv-O₃). Thus, this study assessed the bubble size distribution, zeta potential, ozone dissolution and decay behaviors in water, ·OH concentration, and TC oxidation products, elucidating the degradation pathways and underlying mechanisms enabled by O₃-MNBs. Relative to Conv-O₃, O₃-MNBs increased the steady-state dissolved ozone concentration by 2.57–4.33 times, reduced the ozone decay rate constant by 41.3%, and enhanced ·OH generation by 2.3 times. TC degradation in the O₃-MNB system exhibited a distinct two-stage kinetic behavior, following second-order kinetics in the initial period (0–30 s) and first-order kinetics thereafter (30–120 s). Accordingly, the TC removal efficiency of O₃-MNBs reached 96.25% within 120 s, which was 81.25% higher than that of Conv-O₃. Notably, TC removal under Conv-O₃ obeyed first-order kinetics throughout, with an apparent rate constant only 7.14% of that obtained with O₃-MNBs. These improvements were attributed to the sustained and efficient supply of oxidants, high dissolved ozone and ·OH radicals, promoting the conversion of TC intermediates toward low m/z small-molecule end products, with greater ring opening and skeletal fragmentation. Our findings suggest that the enhanced biodegradability results in a markedly reduced burden and environmental risk for subsequent biological or advanced treatment processes. Therefore, this study highlights the potential of O₃-MNBs to enhance ozone utilization and oxidation intensity, providing mechanistic insights and technical support for rapid pretreatment of antibiotic-containing wastewater. Full article

Dual-propulsion UAVs employ separate rotors for rotary-wing and fixed-wing modes to achieve VTOL (vertical take-off and landing) and high-speed cruise. This paper analyzes steady climb in high-speed flight by utilizing the redundant rotary-wing rotors. We develop the models of aerodynamic forces and thrust forces of a dual-propulsion UAV to obtain its longitudinal dynamic model. The maneuverability of the UAV is analyzed based on the dynamic model to reveal whether a steady climb at a given climb angle is possible within allowable thrust forces. The analytical results show that the climb flight performance of the UAV can be enhanced by utilizing the redundant control inputs during high-speed flights. Flight experiments not only demonstrate that several climb flight states predicted by the analysis are successfully realized, but also that steady climb at a higher climb angle, unattainable in conventional fixed-wing mode, is made possible by simultaneously using the rotors for rotary-wing mode. The enhanced flight performance would increase the number of missions that the UAV can accomplish. Full article

This study explores an integrated multi-physics design approach for a high-speed Interior Permanent Magnet Synchronous Motor (IPMSM) optimized for marine diesel engine Exhaust Gas Recirculation (EGR) blower systems. To satisfy the rigorous operational demands of marine environments, an IPMSM with a rated output of 150 kW and a base speed of 9000 rpm was developed. The design validity was rigorously verified through a comprehensive multi-physics framework using the Finite Element Method (FEM), ensuring a balance between electromagnetic, thermal, and mechanical performance. The investigation established a mathematical model for the IPMSM driven by a Space Vector Pulse-Width Modulation (SVPWM) inverter, facilitating a detailed analysis of steady-state characteristics within the EGR system. To guarantee long-term reliability at high rotational speeds, the study performed an integrated thermal analysis based on precise electrical loss separation and a rotor-dynamic evaluation focusing on unbalanced vibration responses of the shaft. Finally, the proposed design was validated by integrating the IPMSM into a full-scale EGR blower system. Experimental evaluations across the entire operating range confirm that the integrated design successfully achieves the high power density and mechanical robustness required for marine diesel applications. Full article

One of the key factors determining energy consumption and control stability in hydraulic servovalves with direct electric drive is the flow forces acting on the spool. These forces are complex in nature and consist of both steady-state and transient components, with the steady-state component exerting the dominant influence on the performance and dynamics of spool valves. In recent years, this issue has become the subject of intensive research aimed at reducing undesirable hydraulic loads while maintaining high nominal flow capacity, strong energy efficiency, and low manufacturing cost. In engineering practice, the most effective approach has proven to be the modification of the spool geometry in order to control the direction and jet angle of the outflow while keeping the valve sleeve design as simple as possible. This solution reduces the forces acting on the spool without the need to redesign the flow channels or increase production complexity. This study presents classical analytical methods used to calculate flow forces in typical spool valve designs, which serve as a reference point for subsequent investigations. Then, using CFD simulation tools, a method of flow force compensation is demonstrated for selected spool geometries, followed by a detailed comparative analysis of their effectiveness. The results may provide a foundation for developing more energy-efficient and dynamically stable direct-drive servovalve constructions. Full article

High-performance operation of permanent magnet synchronous motors (PMSMs) strongly depends on the reliable availability of rotor position and speed information. Although this information is commonly obtained using physical position sensors, such sensors increase system cost and structural complexity and may reduce long-term reliability, particularly in demanding operating environments. In this study, a model-based, discrete-time, nonlinear gradient observer is adapted for the sensorless estimation of rotor speed and position in PMSMs. The developed Runge–Kutta model-based gradient observer (RKGO) utilizes stator voltage inputs and measured stator currents within a mathematical motor model to estimate the system states. In contrast to conventional sensorless estimation approaches, the adopted observer framework exploits discretization-based gradient dynamics to enhance numerical robustness and convergence behavior under nonlinear operating conditions. The observer design specifically targets stable and accurate state estimation in discrete-time implementations, with a particular focus on low-speed operating conditions. The performance of the adapted method is experimentally evaluated under low-speed operating conditions, including transient and steady-state operation. Real-time implementation is carried out on a dSPACE DS1104 control platform, including loaded acceleration scenarios to assess practical robustness. In addition, a comparative analysis with the Extended Kalman Filter (EKF) and the Runge–Kutta Extended Kalman Filter (RKEKF) is conducted at 60 rad/s under identical experimental conditions. Experimental results show that the RKGO method achieves accurate steady-state speed and position estimation with acceptable transient performance. The findings demonstrate that RKGO can be considered a viable alternative for low-speed sensorless PMSM drive applications. Full article

This paper presents the results of modeling and measuring the thermal properties of selected planar transformer designs. A compact thermal model for the steady state of the planar transformer is presented. A method for measuring its parameters is discussed. The investigation results, illustrating the practical usefulness of the considered thermal model for describing the thermal properties of transformers containing ferrite cores made of different materials, are presented and discussed. The influence of the transformer’s operating frequency and load resistance on the temperatures of each component of the tested transformers is discussed. It is demonstrated that the proposed model enables the correct determination of these steady-state temperatures over a wide range of operating conditions for transformers with cores made of different ferrite materials. Full article

This study investigates the operation of an air source heat pump (ASHP) working with combined radiant floor (RF) and fan coil unit (FCU) heating systems in hot summer and cold winter (HSCW) regions. Intermittent heating demands and ASHP sensitivity to supply water temperature in these regions lead to insufficient steady-state assumptions, while experimental evidence on transient heating behavior, thermal comfort development, and operational limits remains limited. In this study, experiments were conducted to analyze six supply water temperatures (ranging from 35 °C to 45 °C) with respect to the system’s dynamic thermal response, vertical air temperature difference, floor surface temperature, power consumption, and coefficient of performance (COP). The results show that start-up heating is dominated by FCU convection, causing pronounced vertical temperature stratification, while radiant heat becomes dominant as the system approaches steady operation. A good vertical air temperature difference with respect to breathing zones and ankle-level temperature differences below 2 °C was achieved after sufficient operating time. Increasing the supply water temperature accelerated the heating response, where the time required for the average indoor temperature to reach 18 °C decreased from 5.5 h at 35 °C to 2.2 h at 45 °C. However, this improvement was accompanied by reduced energy efficiency, with the mean ASHP unit COP declining from 2.5 to 2.3. Excessively high supply temperatures further induced premature indoor overheating and the frequent start–stop cycling of the heat pump, thereby limiting thermal benefits and increasing power demand. These findings provide experimentally grounded insight into the operation and performance limits of ASHP RF–FCU heating systems. Full article

Gangue backfilling has become an important technique for promoting environmentally friendly and low-carbon coal mining. The long-term creep behavior of cemented backfill plays a critical role in maintaining stope stability and controlling surface subsidence during long-term service. Although considerable research has been conducted on cemented tailings backfill, systematic investigations on the triaxial creep evolution, long-term strength characteristics, confining pressure effects, and the applicability of the classical Burgers model for gangue–gypsum cemented backfill under engineering-relevant confining pressures remain limited. In this study, the experimental scheme was designed based on field monitoring data from practical backfill mining operations, which indicate that the in situ backfill generally remains stable without significant deformation or instability under normal working conditions. Multi-stage loading triaxial creep tests were conducted on gangue–gypsum cemented backfill under confining pressures of 1, 2, 3, and 4 MPa. The creep deformation characteristics were analyzed using Chen’s superposition method, while the long-term strength was computed via inflection point method of isochronous stress–strain curves. The parameters of the Burgers creep model were identified using the Levenberg–Marquardt optimization algorithm, and numerical verification was performed using FLAC3D. Our findings demonstrate that the creep deformation process of the backfill consists of three typical stages: instantaneous deformation, attenuated creep, and steady-state creep, and no accelerated creep was observed within the applied stress range. The absolute creep strain surges nonlinearly with increasing stress level (S_L), whereas higher confining pressure significantly suppresses the creep response of the material. Within the investigated stress range, the backfill exhibits mainly linear viscoelastic behavior, and its critical long-term strength is not less than 0.9 times the failure deviatoric stress (qf). Although confining pressure enhances the long-term strength, the strengthening effect weakens as the confining pressure increases. Model fitting outcomes imply that Burgers model precisely describes the creep behavior of gangue–gypsum cemented backfill under all test conditions, with correlation coefficients (R²) exceeding 0.97. The identified parameters show systematic variation with S_L, reflecting stiffness degradation and viscous evolution during loading. Numerical simulation results agree well with the experimental data, providing theoretical guidance for mixture proportion optimization, long-term stability evaluation, and stope support parameter design in gangue backfill mining engineering. Full article

With rising global energy demand and the gradual depletion of petroleum-based resources, interest in alternative fuels for internal combustion diesel engines (ICDEs) has increased. In ICDEs, firing-related and mechanical excitations may result in adverse vibration and noise responses. This study examines whether incorporating sour cherry pit pyrolysis oil (SCPO) with n-butanol and 2-ethylhexyl nitrate (2-EHN) may reduce vibration and noise under constant-load, steady-state operating conditions compared with neat diesel (D100). For the experimental tests, five fuel types were prepared: one neat diesel fuel and four blended fuels with a constant diesel fraction of 40% and a fixed 2-ethylhexyl nitrate (2-EHN) content of 5%, while the SCPO and n-butanol fractions were varied (D40/SCPO0/B55/2-EHN5, D40/SCPO5/B50/2-EHN5, D40/SCPO10/B45/2-EHN5, and D40/SCPO15/B40/2-EHN5). Experiments were performed using a single-cylinder ICDE at a fixed load of 10 Nm under steady-state conditions at engine speeds of 1500, 1800, 2400, 3000, and 3600 rpm. For each operating condition, vibration and noise data were recorded over a 10.4 s window. Experimental findings indicate that D40/SCPO10/B45/2-EHN5 yielded the lowest mean overall RMS vibration, with a 37.5% reduction relative to neat diesel (D100), and the lowest equivalent sound level (LAeq) among the tested fuels. Under the investigated steady-state constant-load conditions, the D40/SCPO10/B45/2-EHN5 fuel blend demonstrates the potential to achieve lower measured vibration and noise levels than neat diesel. Full article

Serotonergic projections innervate both the dorsal and ventral cochlear nuclei; however, the electrophysiological consequences of serotonergic input in the ventral cochlear nucleus (VCN) remain incompletely understood. This study aimed to identify the serotonin receptor subtypes involved in serotonergic modulation of stellate cells in the mouse anteroventral cochlear nucleus (AVCN) and to determine the underlying ion channel mechanisms. Whole-cell patch-clamp recordings were performed in acute brain slices obtained from postnatal day 12–17 mice. Bath application of serotonin (25 µM) induced membrane depolarization (~5 mV) and increased action potential firing. Pharmacological experiments demonstrated that antagonists of 5-HT1A, 5-HT2A, and 5-HT2C receptors partially reversed the depolarization and reduced serotonin-induced inward currents, indicating that multiple receptor subtypes contribute to serotonergic excitation. Blockade of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels with extracellular Cs⁺ suppressed approximately 95% of the serotonin-induced depolarization and inward current, implicating HCN channel-mediated Ih as a principal ionic mechanism. Serotonin significantly increased Ih amplitude. Analysis of steady-state activation revealed no statistically significant shift in V0.5; however, under near-resting membrane potential conditions, serotonin significantly reduced the slope factor of the activation curve, consistent with altered voltage sensitivity of Ih gating. Immunohistochemical analysis confirmed the presence of 5-HT1A, 5-HT2A, and 5-HT2C receptors in the AVCN. Together, these findings indicate that serotonergic excitation of AVCN stellate cells is mediated by coordinated activation of multiple 5-HT receptor subtypes and primarily involves modulation of HCN-dependent subthreshold membrane dynamics. Full article

This paper presents a systematic experimental comparison of three sliding-mode-based current control strategies—traditional sliding mode control (SMC), fast terminal sliding mode control (FTSMC), and super-twisting sliding mode control (STSMC)—applied to a grid-connected five-level active neutral point clamped flying capacitor (5L-ANPC-FC) inverter. Unlike existing studies that typically investigate a single controller or topology, this work provides a fair, hardware-validated benchmark under identical operating conditions, enabling a clear assessment of convergence speed, harmonic performance, robustness, and implementation complexity. All controllers are designed within a unified framework and their stability is rigorously analyzed using Lyapunov theory. Experimental evaluations are conducted under steady-state operation, step changes in reference current, grid-voltage sag/swell, and DC-link voltage variations. The results demonstrate that while all three controllers ensure robust current tracking and inherent DC-side capacitor voltage balancing without additional control loops, FTSMC achieves the lowest grid-current total harmonic distortion (THD) and fastest convergence. STSMC effectively suppresses chattering, and traditional SMC offers a simple yet reliable baseline solution. The presented findings provide practical design guidelines for selecting appropriate sliding-mode controllers in high-performance multilevel inverter applications. Among the assessed control techniques, FTSMC has the most rapid dynamic response, characterized by a rise time of 0.1 ms and a minimal grid-current THD of 1.95%, indicating exceptional steady-state and transient performance. STSMC markedly diminishes chattering and ripple, attaining a THD of 2.04% with enhanced waveform smoothness relative to traditional SMC. Conversely, traditional SMC offers a more straightforward implementation but demonstrates elevated ripple and THD levels of around 2.29%, along with a peak current inaccuracy of 6–8%. The results underscore the trade-offs between implementation simplicity, dynamic responsiveness, and harmonic performance of the evaluated control techniques. Full article

Accurate and physically consistent state prediction is essential for shipboard power systems (SPS) operating under dynamic conditions. However, purely data-driven models often exhibit degraded robustness and physically inconsistent outputs when exposed to transient disturbances or limited data coverage. To address these limitations, this paper proposes a physics-constrained hybrid prediction model that integrates a convolutional neural network–bidirectional long short-term memory (CNN–BiLSTM) architecture with wide residual connections (WRC) and a physics-constrained loss (PCL). The proposed modeling approach combines real operational measurement data with high-resolution simulation data to enhance data diversity and improve generalization capability. The CNN–BiLSTM structure captures nonlinear temporal dependencies, while the WRC preserves critical low-level transient electrical features during deep temporal modeling. In addition, multiple physical constraints, including power balance, voltage conversion relationships, and battery state-of-charge (SOC) dynamics, are incorporated into the training process to enforce physically consistent predictions. The model is validated using charging and discharging experiments on a laboratory-scale SPS under both steady-state and transient conditions. Comparative results demonstrate that the proposed approach achieves higher prediction accuracy, improved dynamic stability, and faster recovery following disturbances compared with conventional data-driven models. These results indicate that physics-constrained deep learning provides an effective and interpretable modeling framework for SPS state prediction, supporting digital twin-oriented monitoring and real-time prediction applications. Full article

Advances in regenerative medicine increasingly rely on human-relevant in vitro systems to model the multistage process of wound healing. However, the translation of research into effective therapies remains limited by the inability of traditional 2D cultures and animal models to faithfully replicate the structural and biochemical complexity of human skin. While existing reviews often focus on the structural composition of static skin equivalents, this review addresses a critical knowledge gap: the need for dynamic, time-dependent methodologies that can capture the spatiotemporal evolution of healing, from inflammation to remodeling, in both physiological and pathological conditions. To this end, we critically evaluate next-generation platforms, including 3D bioprinting, organ-on-chip systems, organoids, and iPSC-based models, highlighting their comparative advantages and technical hurdles like vascularization and scalability. The unique contribution of this work lies in providing a forward-looking framework that advocates for the convergence of bioengineering and computational modeling to move beyond “steady-state” snapshots toward predictive, high-resolution dynamic models. We conclude that the future of wound healing research depends on integrating vascular and immune components within these platforms to achieve truly human-relevant, personalized diagnostic and therapeutic tools. Full article