Search Results (344)

There is increasing interest in structured layered double hydroxide (LDH)-based catalysts because they combine tunable acid–base/redox chemistry with reactor architectures that can reduce diffusion lengths, improve heat management, and lower pressure-drop penalties. This review evaluates LDH, LDH-derived oxide (LDO/MMO), reduced metal/LDO, reconstructed hydroxide-rich, and mixed dynamic states integrated into honeycomb monoliths, open-cell foams, meshes/felts, thin films, washcoats, coated plates, microchannels, capillaries, and additively manufactured lattices. To move beyond descriptive comparison, the literature is assessed using unified evaluation dimensions: operative active state, support architecture, coating/integration route, active-phase loading, coating thickness and uniformity, reactor-volume-normalized productivity or STY, ΔP/L, axial/radial thermal gradients, time-on-stream, coating loss, regeneration recovery, and pilot-readiness. Representative benchmarks illustrate both the promise and reporting gaps of the field: NiFe-LDH-derived monoliths for CO₂ methanation have reached ~70% CO₂ conversion at 300 °C with >90% CH₄ selectivity and only 0.7% post-test mass loss; NiFe-LDH/iron-foam monoliths retained 85% ozone conversion after 168 h; high-entropy LDH-derived oxides showed T50/T90 values of 246/254 °C for toluene oxidation; and Au/LDH capillary films achieved 31.9% glycerol carbonate yield and 3.78 g h⁻¹ g⁻¹ productivity. The strongest current cases are pollution abatement and CO₂ methanation, whereas biomass upgrading, fine-chemical flow, high-entropy coatings, and photo/electrocatalytic films require deeper module-level validation. Overall, structured LDH catalysts should be treated as coupled chemistry–coating–reactor systems whose performance must be judged simultaneously by activity, accessible catalyst inventory, transport efficiency, pressure drop, thermal profile, durability, regeneration, and manufacturability. Full article

In single-phase PWM rectifiers, due to the inherent time-varying characteristics of the source voltage and current as well as the periodic operation of the converter bridge, the instantaneous input power on the AC side inevitably exhibits a twice-fundamental-frequency pulsation. This phenomenon consequently generates a double-line-frequency (100 Hz) voltage ripple on the DC-link capacitor, which causes an inherent contradiction in conventional voltage outer-loop control between steady-state ripple suppression and dynamic response speed. To address this issue, this paper proposes a control strategy based on an Adaptive Time-Delayed Feedforward Neural Network (Adaptive TD-FNN). The proposed method explicitly introduces the delayed voltage error of half a ripple period into the network state input, thereby achieving time-domain decoupling of the 100 Hz low-frequency disturbance. In addition, a physics-driven training framework is constructed by integrating the rectifier’s discrete difference equation, thereby strengthening the network’s capacity to learn the dynamic characteristics of the system. On this basis, a dynamic adaptive smoothness-weight penalty mechanism is designed to adjust the weighting factor of the current command smoothness constraint in the loss function according to the system operating state. Specifically, the penalty weight is increased under steady-state conditions to suppress command oscillations caused by ripple disturbances, while it is rapidly reduced during load or grid-voltage transients to release the network’s transient optimization capability. Simulation and experimental results show that the proposed Adaptive TD-FNN controller can simultaneously achieve smooth steady-state current command output and fast dynamic voltage regulation without introducing additional complex digital notch-filtering algorithms. Compared with conventional dual-loop control, the proposed strategy reduces the total harmonic distortion (THD) of the grid-side input current from 8.45% to 3.42%, satisfying grid-connected power quality requirements. Meanwhile, under large load transients and grid-voltage disturbance conditions, the DC-link voltage recovery time is about 40 ms, verifying the comprehensive advantages of the proposed method in ripple suppression, dynamic response, and operating-condition adaptability. Full article

Double-wall drill pipe reverse circulation drilling is expected to alleviate cutting-transport difficulties and the high risk of lost circulation during the shallow-section drilling of ultra-deep wells. Based on wellbore hydraulics theory and a transient solid–liquid two-phase flow model in the wellbore, considering the flow path transition effect at the reverse circulation converter near the bit, a corrected pressure loss method for the inner pipe accounting for cuttings influence is proposed, and a correlation for calculating the converter pressure loss is derived. A wellbore pressure calculation model for reverse circulation drilling using a double-wall drill pipe is then established. Furthermore, the influencing factors are investigated through sensitivity analysis, and a pump pressure selection chart is developed. Field-case calculations indicate that, under identical operating conditions, the bottomhole pressure in double-wall drill pipe reverse circulation drilling is reduced by approximately 6.31 MPa compared with conventional drilling. For shallow sections (well depth of about 1200 m) under flow rates of 20–40 L/s and drilling-fluid densities of 1200–1400 kg/m³, the maximum total circulating wellbore pressure loss, after incorporating surface flowline pressure losses, is approximately 10.91 MPa. In this case, a single pump can satisfy the circulation requirement, demonstrating the advantages of simplified equipment configuration and improved field adaptability for shallow-section operations. The proposed model and charts can provide a reference for parameter optimization and pressure-control design in double-wall drill pipe reverse circulation drilling. Full article

Background/Objectives: Efficient patient flow in urgent urology services is critical to timely care delivery, yet workflow bottlenecks in specialty clinics remain underexplored. This study aimed to identify workflow bottlenecks, evaluate patient flow and staff attitudes, and explore clinician readiness for digital decision-support in a high-volume NHS emergency urology walk-in clinic. Methods: A two-week observational study was conducted at an emergency urology service in London. Time-stamped pathway data were collected for 80 patient journeys to identify total clinic duration. Differences associated with investigation ordering and senior escalation were analyzed using t-tests. Clinicians (n = 34) completed a questionnaire assessing perceptions of AI, and nursing staff provided qualitative feedback on operational pressures. Results: Mean total clinic journey time was 2 h 42 min, with the post-assessment phase accounting for 64% of total duration. Investigation ordering was the principal source of delay: patients undergoing investigations remained significantly longer in clinic than those who did not (3 h 17 min vs. 2 h 15 min, p < 0.05), and doctor-to-discharge time more than doubled (2 h 20 min vs. 1 h 2 min, p < 0.005). Senior escalation did not significantly prolong patient flow. Staff surveys demonstrated moderate trust in and comfort with AI as a decision-support tool. Nursing feedback highlighted inappropriate attendances, limited staffing, and workspace constraints as key stressors. Discussion: Delays were primarily driven by investigation ordering rather than senior review, identifying investigation timing as a potential target for future pathway optimisation. Conclusions: Investigation-related delays were the dominant workflow bottleneck. While no AI system was deployed in this study, these findings provide empirical groundwork to inform the design and prospective evaluation of AI-supported triage in specialty acute care settings. Full article

To address fault-period DC-link overvoltage, the reduction in grid-side active-power regulation margin caused by reactive-current-priority operation, and the double-frequency current fluctuation induced by negative-sequence components under asymmetrical grid faults in a flywheel-assisted permanent-magnet direct-drive wind power system, this paper proposes a coordinated low-voltage ride-through (LVRT) strategy based on DC-link-voltage-threshold partitioning. According to the DC-link voltage level, the operating process is divided into a normal regulation region, a grid-side saturation region, and a flywheel activation region, thereby enabling coordinated regulation between grid-side reactive-current support and flywheel-side active-power absorption. To improve transient smoothness, an anti-windup mechanism together with a bumpless transfer scheme is incorporated into the coordinated control process to suppress integrator saturation and mitigate mode-transition disturbances. In addition, a grid-side proportional–integral–vector resonant controller (PI-VRC) is introduced to improve the suppression of double-frequency current fluctuation under asymmetrical faults and enhance converter capacity utilization. Simulation results show that the proposed strategy can effectively restrain fault-period DC-link voltage rise, improve three-phase current symmetry and grid power quality, and strengthen transient reactive-power support, thereby enhancing the asymmetrical-fault LVRT capability of the system. Full article

To accelerate the transition to sustainable energy, efficient methods for CO₂-free hydrogen production and carbon utilization are needed. This study presents a new, sustainable approach for the simultaneous production of hydrogen, valuable hydrocarbons, and functional carbon materials by converting methane in low-pressure microwave plasma. Compared to traditional methane reforming methods (such as steam reforming), our plasma-based process operates at low temperatures, eliminates direct CO₂ emissions, and enables the conversion of methane into three valuable products: (1) environmentally friendly hydrogen for fuel cells and energy storage systems, (2) a range of valuable organic products (C₂H₂, C₂H₄, C₂H₆), and (3) functional carbon films with self-improving catalytic properties. Optical emission spectroscopy (OES) and the Langmuir double probe method were used for plasma diagnostics, revealing an increase in the concentration of active species (CH, Hα, C₂) and electron temperature upon argon addition. The structure, morphology, and impurity composition of the deposited films were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and inductively coupled plasma mass spectrometry (ICP-MS), respectively. Gas-phase byproducts were analyzed using gas chromatography–mass spectrometry (GC-MS). Argon addition at an Ar/CH₄ ratio of 1 leads to the formation of carbon films with a more ordered structure, as confirmed by XRD data, and improved surface morphology. It was established that argon, by effectively participating in the excitation and dissociation processes of methane molecules through energy transfer from metastable states and increased electron temperature, optimizes plasma–chemical reactions, promoting the deposition of higher-quality carbon coatings. Full article

Introduction: This study evaluated the implications of intravenous acetaminophen (Ofirmev) on perioperative outcomes in patients undergoing robotic-assisted laparoscopic prostatectomy (RALP) for prostate cancer. The primary objective was to determine whether adding IV acetaminophen to standard analgesia could reduce hospital length of stay (LOS), pain intensity, and opioid use compared with placebo. Methods: This study was conducted as a secondary descriptive analysis of publicly available aggregate results from a previously completed randomized, double-blind, placebo-controlled Phase IV trial (NCT02369211). No individual patient-level data were accessed, and no new independent statistical analyses were performed. Eighty-six male patients were randomly assigned to receive either 1 g IV acetaminophen or saline placebo every six hours for four doses during the perioperative period. Primary endpoints were hospital and post-anesthesia care unit (PACU) LOS; secondary endpoints included postoperative pain scores and opioid consumption (morphine milligram equivalents). Results: Baseline characteristics were similar between groups (n = 43 each). Mean PACU stay was slightly shorter with IV acetaminophen (124 ± 58 min) than placebo (132 ± 63 min; not significant). Median hospital LOS was 0.81 days versus 0.82 days (p = 0.006), a statistically significant difference reported in the original trial dataset, although the absolute difference was clinically minimal. Pain scores and opioid requirements were lower with IV acetaminophen but not significantly different. No adverse events occurred in either group. Conclusions: IV acetaminophen was safe and well tolerated as part of multimodal analgesia for RALP. Although pain scores and opioid use numerically favored IV acetaminophen, these differences were not statistically significant. The reported difference in hospital LOS was statistically significant in the original trial record but clinically minimal; therefore, the findings should be interpreted as exploratory and hypothesis-generating regarding potential operational and economic implications. Full article

This work develops an analytical framework for nonlinear fractional partial differential equations that combine Kirchhoff-type terms, double-phase operators, and $\psi$-Hilfer fractional derivatives. This paper investigates two classes of problems involving variable-exponent growth conditions. The first problem analyzes general nonlinear sources and formulates the solution as a fixed point of a nonlinear operator. Precisely, by proving that the functional energy is coercive, hemicontinuous, and strictly monotone, we establish the existence and the uniqueness of weak solutions via monotone operator theory. The second problem incorporates a convection-type nonlinearity, which breaks variational structure and requires the more robust theory of pseudomonotone operators. Under suitable growth and mixed-order assumptions on the nonlinearity, we prove the existence of at least one weak solution. The main tools are grounded in variable-exponent Lebesgue and Musielak–Orlicz–Sobolev spaces, with compact embeddings, modular estimates, and fractional integral identities playing a key role in the proofs. We note that the results contribute to the mathematical modeling of phenomena involving nonlocal elasticity, viscoelastic materials, phase-transition media, and fractional dynamical systems where the stiffness of the medium depends on the total deformation (Kirchhoff effect) and the energy density alternates between distinct growth regimes (double-phase). The $\psi$-Hilfer derivative enhances the scope by enabling models with tunable memory and hereditary effects. Full article

Bridging the gap between theoretical heat exchanger analysis and physical intuition remains a persistent challenge in engineering education, particularly when students are confronted with real-system effects such as pressure losses, measurement uncertainty, and deviations from simplified models. This work addresses this challenge through the coupled development of a pedagogical framework and an experimental platform. A modular heat exchanger test bench was conceived, designed, and constructed by graduate students within a structured project-based learning environment, in which competitive and cooperative phases were combined to emulate real engineering practice. This approach positions the test bench not only as a laboratory tool, but as the outcome of an active learning process that integrates system design, instrumentation, and modeling. The resulting platform enables the comparative study of multiple heat exchanger technologies—including three water-to-water heat exchangers (plate, shell-and-tube, and double-pipe) and one air-to-water fin-and-tube heat exchanger—under parallel, counterflow, and crossflow arrangements across a wide range of operating conditions. Comprehensive instrumentation (temperature, flow rate, and pressure measurements) supports rigorous energy balance analysis, effectiveness evaluation, and hydraulic performance assessment. Beyond undergraduate experimentation, the test bench provides a framework for advanced learning objectives, including uncertainty propagation, $\epsilon$-NTU analysis, model development, and experimental validation. The confrontation between model predictions and experimental data, including observed discrepancies, is shown to play a central role in developing critical engineering judgment. The proposed approach demonstrates how the integration of project-based learning with a reconfigurable experimental platform can create a sustainable and scalable environment for heat transfer education. Full article

Inductive power transfer (IPT) systems commonly rely on complex control schemes or hybrid compensation networks with bulky ferrite-core inductors to realize constant-current/constant-voltage (CC/CV) charging and misalignment tolerance, which degrades system integration and power density. This paper proposes a hybrid dual-frequency IPT topology using a fully capacitive compensation structure, eliminating the need for large inductors. The proposed topology is composed of S–S and S–LCC compensation networks, which are switched by a Single-Pole Double-Throw (SPDT) relay switch for CC/CV mode transition. Two inherent zero phase angle (ZPA) operating frequencies are generated for CC and CV modes, enabling mode transition through simple frequency switching and SPDT relay switch-based topology switching without additional DC–DC stages or complex control. A unified parameter design and a unipolar duty cycle (UDC) control strategy are developed to allow fixed-parameter operation with enhanced tolerance to coupling variation. Experimental results validate stable ZPA operation in both modes. A 3.7 kW prototype achieves a peak efficiency of 96.07%. Full article

Pumps, as critical equipment in water supply and drainage systems, contribute significantly to energy use and carbon emissions throughout their life cycle. This study quantified the life-cycle carbon footprint (LCF) of water supply and drainage pumps by developing a life-cycle assessment (LCA)-based model covering raw material acquisition, production and processing, transportation, operation, and recycling. Using the 400S-40 single-stage double-suction centrifugal pump as a case, the results showed that: (1) the total LCF of the pump was 5567.56 t CO₂e per unit; and (2) the operational stage accounted for 99.69% of the total life-cycle emissions. The findings indicate that, for the studied case, use-phase electricity consumption dominates the overall carbon footprint under the stated assumptions. Accordingly, for water utilities and pump users, improving operating efficiency and reducing avoidable electricity consumption are critical to carbon reduction. For pump manufacturers, enhancing processing technology, adopting low-carbon materials, improving durability, and promoting component-level maintenance and replacement can reduce embodied carbon and avoid unnecessary emissions associated with premature full-unit replacement. Beyond carbon reduction, these measures are also conducive to resource conservation, sustainable manufacturing, and the low-carbon transition of urban water infrastructure. Therefore, this study provides methodological support for the green design, operation, and management of pump equipment, and contributes to the sustainable development of water supply and drainage systems. Full article

Achieving the coexistence of high energy density and fast-charging capability remains a fundamental challenge for lithium-ion batteries. Increasing electrode thickness and compaction density enhances energy density but simultaneously alters the pore structure and restricts lithium-ion transport, leading to concentration polarization, increased resistance, and lithium plating. In this work, we employ X-ray computed tomography (X-CT) and 3D reconstruction to establish quantitative relationships between particle size, compaction density, and key structural parameters (porosity, tortuosity, effective proportion of lithium-ion flux (f_eff)). Then, an electrochemical model is used to link the liquid-phase kinetic parameters (ionic conductivity (k₀) and liquid-phase diffusion coefficient), as corrected by the effective proportion of lithium-ion flux f_eff, to polarization and lithium-plating behavior, and the maximum current density without lithium plating under various fabrication conditions is finally determined. Results show that small-particle electrodes exhibit superior rate capability at moderate compaction levels, but suffer from rapidly increasing tortuosity and reduced transport efficiency under high compaction and large thickness. Moreover, a double-layer gradient electrode design effectively integrates the advantages of both large- and small-particle architectures, enabling high-rate operation without lithium plating. The double-layer gradient electrode (ρ = 1.6 g/cm³) exhibited ~50% higher performance at 1.5 C compared to the small-particle anode and enabled 2 C charging without lithium plating. This study offers a robust structural design strategy for optimizing thick-electrode architectures toward high-energy, fast-charging LIBs. Full article

Single-phase current source (SCS) converters typically necessitate a bulky inductor to mitigate DC current fluctuations. Furthermore, open circuit conditions must be avoided in these systems. Active power decoupling (APD) offers an effective solution by eliminating double-line frequency ripple power without a bulky inductor. However, it introduces additional power losses due to the extra devices. To address this issue, this paper proposes an efficient and reliable bridgeless power factor correction (PFC) APD converter. A diode is incorporated into the converter to construct new current paths. The new paths decrease the number of semiconductor devices to lower conduction losses and provide an inherent freewheeling path for DC current to enhance system reliability. Through a specific modulation strategy, the utilization of new paths is maximized, and switching losses are reduced. This paper begins by describing the operating modes of the proposed converter. It then introduces a specific modulation strategy. A detailed analysis of power losses is presented. Finally, a 360 W prototype is constructed, and experimental results demonstrate an efficiency improvement of 2.5%. Full article

Water-level monitoring in rice paddies supports sustainable farming, responsible water management, and greenhouse gas emission mitigation. SAR-based remote sensing is an effective alternative for estimating water levels, especially in regions where optical observations are limited. This study evaluates ten ALOS-2/PALSAR-2 L-band SAR-derived polarimetric parameters for their contribution and effectiveness in water-level estimation across rice-growing phases using random forest regression in the Subang District, which is one of the largest rice-yield areas in West Java, Indonesia. Overall, L-band polarimetric information is clearly related to water-level dynamics throughout the rice-growing cycle, confirming its strong potential for quantitative water-level retrieval. The highest estimation accuracy was achieved by integrating all polarimetric parameter groups (MAE = 1.37 cm, RMSE = 1.79 cm, R² = 0.52, r = 0.73), indicating that no single group can adequately represent the complex scattering mechanisms governing water-level variability across an entire cropping season. Variable importance analysis shows a relatively uniform contribution (7.63–12.90%), suggesting synergies across parameters in water-level estimation. Phase-specific evaluation further reveals that Phase 2, corresponding to the vegetative-to-generative transition, is the optimal temporal window for L-band SAR-based water-level retrieval due to enhanced double-bounce scattering and reduced signal saturation. While Phase 2 data maximizes physical sensitivity and correlation, whole-phase modeling provides greater robustness and lower absolute errors, making it more suitable for L-band SAR-based operational water-level monitoring applications. Full article

To accurately evaluate the electric and magnetic field distribution characteristics around transmission lines under different tower structures and operating conditions, this study systematically investigates the spatial electric and magnetic fields of transmission line towers based on Grid Information Model (GIM) file parsing and finite element simulation. First, key information, including tower geometric configuration, conductor suspension point locations, and voltage level, is extracted by parsing the GIM file. A unified transformation method from geographic coordinates to three-dimensional Cartesian coordinates is established, and a three-dimensional electric and magnetic field calculation model is constructed in the ANSYS Maxwell platform, incorporating a catenary conductor model and an equivalent representation of bundled conductors. Furthermore, the accuracy of the proposed calculation method is validated based on field measurement data. Second, under single-circuit operating conditions, the spatial electric and magnetic field distributions of the Goblet-shaped suspension tower and the Drum-type transmission tower are analyzed under different phase sequence arrangements and different conductor-to-ground heights, and the shielding effect of the tower structure on the local electric field is investigated. On this basis, an electric field fitting method based on a proportional polynomial model is proposed, enabling the prediction of electric field distribution under tower-present conditions using simulation results obtained without tower structures. Subsequently, the influence of different phase sequence combinations on the spatial electric field distribution is systematically examined. The fitting method is further extended to double-circuit transmission lines, and its accuracy and effectiveness in rapid electric field assessment are verified. Finally, from an engineering practice perspective, the effects of the presence of jumper conductors and variations in conductor turning angles on the spatial electric field distribution of double-circuit towers are analyzed, and an optimized estimation approach for electric fields under different turning angle conditions is proposed. The results demonstrate that tower structural configuration and conductor arrangement significantly affect the electric field distribution, and the proposed fitting method effectively reduces modeling complexity while maintaining computational accuracy. The findings of this study provide a theoretical basis and technical reference for electric and magnetic environment assessment and engineering design of transmission lines. Full article