Search Results (3,179)

Shaftless Pump-jet Thrusters (SPTs), which integrate the propulsion motor directly with impellers, provide a compact design and high propulsion efficiency. Despite this, their performance is significantly hampered by eddy current losses in conductive stator sleeves. This study introduces Titanium Matrix Composites (TMC) as superior alternatives to conventional titanium alloys (Ti-6Al-4V, Ti64), leveraging their tailorable anisotropic electromagnetic properties to effectively suppress eddy current losses. Through simulations and experimental validation, the electromagnetic performance of an SPT equipped with a TMC stator sleeve is systematically investigated. Electromagnetic simulations predict a dramatic reduction in eddy current loss of 53.5–79.8% and an improvement in motor efficiency of 5.8–8.5% across the 1500–2900 rpm operational range compared to the Ti64 baseline. Experimental measurements on prototype motors confirm the performance advantage, demonstrating a 3.5–5.7% reduction in input power under equivalent output conditions across the same speed range. After accounting for manufacturing tolerances and control strategies, the refined model demonstrated a markedly improved agreement with the experimental results. This research conclusively establishes TMCs as a high-performance containment sleeve material, which is promising not only for SPTs but also for a broad range of canned motor applications, where an optimal balance between electromagnetic and structural performance is critical. Full article

Electric Water Pumps (EWPs) are being adopted more widely to improve thermal management in internal combustion engines and electrified powertrain systems. In this context, the drive motor must deliver high efficiency and reliability despite a strict volume constraint. This paper addresses a key drawback of coreless printed circuit board (PCB) stator axial-flux permanent-magnet machines for EWP use: the PCB traces are directly exposed to the magnet flux, which increases AC loss, while the required phase resistance also leads to non-negligible DC copper loss. To mitigate both loss components within the same conductor design space, a pyramid trace concept is introduced. A magnetic equivalent circuit (MEC) based model is first used to estimate the baseline performance as the number of PCB stator modules changes, and the resulting scalability is examined in terms of module commonality. The final design then applies the pyramid trace layout with a layer-dependent trace width that is narrower on the layers closer to the magnets and wider on the layers farther away—the trade-off between AC loss and DC loss is optimized using 3D finite element analysis. Torque predictions from the simplified MEC model are cross-checked against 3D finite element analysis (FEA), and finally, a prototype is built to validate the analysis with experimental measurements; for the final selected model, the torque prediction error is 2.37% compared with the validation result. Full article

In the global wave of energy transition, ground-source heat pump (GSHP) systems are widely adopted for their ability to efficiently provide space heating and cooling. By utilizing stable shallow geothermal energy, these systems significantly reduce operational energy consumption in buildings, playing a crucial role in enhancing building energy efficiency and achieving low-carbon strategies. However, large-scale ground heat exchanger (GHE) clusters with non-identical circuits often face hydraulic and thermal imbalances, leading to degraded system performance. This study investigates the hydraulic and thermal behavior of a large-scale GHE system in Shandong Province, China. Hydraulic and thermal models are first developed based on Kirchhoff’s laws and the principle of energy conservation, and then used to simulate and analyze the influence of the number and depth of boreholes on hydraulic and thermal conditions. The results indicate that the flow imbalance rate and pipe length ratio follows a power-law relationship, δ_f = a (L_v/h)^{^b} + d, with fitted coefficients, a = 0.0677–0.1294, b = −0.7086 to −1.0805, d = 0.0036–0.0921, while the heat exchange imbalance rate follows a linear relationship, δ_q = kδ_f + o, with k = 0.0906–0.265 and o = 0.0028–0.0039. Increasing the number of boreholes or decreasing depth exacerbates flow imbalance (10–58%), but soil thermal resistance dominates, limiting the increase in the heat exchange imbalance rate (2.2–9%). The formula and the quantitative relationship proposed in this paper aim to provide guidance for the engineering design of large-scale non-identical circuit GHE clusters. Full article

This study examines the impact of fluid excitation forces on the dynamic response of high-temperature molten salt circulating primary pump rotor systems. Unsteady simulations were conducted in ANSYS CFX to characterize pressure pulsation and radial forces across all impeller stages. Critical speeds and vibration modes were subsequently analyzed using SAMCEF to evaluate transient responses under varying flow rates. Key findings: Numerical performance predictions align with experimental data within a 5% error margin. The first-stage impeller exhibits a pressure-pulsation frequency of twice the rotational frequency (2 f_R), while the fifth-stage impeller oscillates at the guide-vane passing frequency (f_DPF). Under rated conditions, the radial force on the first stage is significantly larger than on the other stages. As the flow rate varies, the radial forces on the first and fifth stages change in opposite directions due to rotor–stator interaction. The rotor system’s critical speed (1894.5 r/min) exceeds the operating speed, eliminating resonance risk. Without radial forces, impeller displacements follow elliptical trajectories with maximum amplitude at the fifth stage. When radial forces are included, displacements become irregular, and shaft constraints cause peak displacement at the fourth stage. These findings provide useful insight for the design and analysis of molten salt primary pump rotor systems. Full article

The blade outlet angle is a critical design parameter of vortex pump impellers, exerting a significant influence on the pump’s hydraulic performance and internal flow characteristics. In this study, numerical simulations combined with experimental validation were conducted to investigate a vortex pump, with three impellers featuring blade outlet angles of 50°, 60°, and 65° analyzed based on the SST k–ω turbulence model. To quantify irreversible energy losses, entropy production theory was adopted, while the Liutex method was utilized to characterize rigid-body vorticity. The results demonstrate that increasing the blade outlet angle leads to a reduction in head under both small-flow-rate and design-flow-rate conditions, impairs flow uniformity, strengthens vortex structures, and elevates total entropy production—with turbulent dissipation being the dominant contributor to energy losses. Additionally, larger outlet angles enhance the sensitivity of internal flow structures to off-design operating conditions. These findings offer valuable guidance for the optimization of impeller design and the development of energy-efficient vortex pumps. Full article

In 90° elbows, abrupt turning induces strong secondary flow, separation, and turbulence, increasing pressure loss and degrading velocity uniformity. A hydrogen pipeline elbow is optimized by combining a nature-inspired cross-section with a guide vane, while tuning vane position/angle and geometric radii/offsets using a multi-objective genetic algorithm (MOGA). Three-dimensional CFD is performed for compressible gaseous hydrogen using the Peng–Robinson equation of state and the SST k–ω turbulence model. Design points are generated by Latin hypercube sampling, and response surface models based on non-parametric regression (NPR) and genetic aggregation (GA) guide the search. Relative to the reference elbow, the GA-based optimum improves velocity uniformity by 5.825% and reduces the total pressure-drop coefficient by 0.470%; the NPR-based optimum yields 4.021% and 0.229%, respectively. Flow-field analysis shows reduced separation area, axial vorticity, turbulent kinetic energy, and dissipation, indicating suppressed secondary flow and smoother turning. These gains translate to lower pumping power and enhanced energy efficiency, supporting cost-effective deployment of carbon-neutral hydrogen infrastructure. Full article

This research presents the development of a new Hybrid Operational Strategy model for energy management optimization designed to evaluate the feasibility of implementing hybrid renewable energy modules in ports, aiming to improve their efficiency, sustainability, and innovation. The proposed system integrates photovoltaic, wind, and hydrokinetic energy sources, incorporating electronic components and assessing two energy storage technologies—Pump-as-Turbine (PAT) and battery systems—to determine the most viable solution for practical deployment. The optimization algorithm allows a concurrent refinement process for the power generation data of each renewable source. Four scenarios were analyzed within this optimization framework: two assessing the performance of single modules employing each storage technology individually, and two exploring configurations with multiple modules operating in parallel, either with independent storage units or a single centralized system. Battery storage was identified as the most feasible option based on the optimization outcomes. Considering the demand characteristics and generation capacity of the hybrid module, the configuration yielding the best overall performance consisted of a single module incorporating battery storage, achieving 90% demand coverage and demonstrating economic viability with a Net Present Value (NPV) of 9182.79 € and an Internal Rate of Return (IRR) of 10.88%. Full article

Background: Proton pump inhibitors (PPIs) are commonly used to manage acid-related gastrointestinal conditions. Nevertheless, growing attention has been paid to their long-term safety, especially their possible link to dementia and Alzheimer’s disease (AD). Prior research has yielded inconsistent findings, underscoring the need for a comprehensive and current evaluation. Methods: A systematic search was conducted across PubMed, Embase (Ovid), and the Cochrane Library to identify relevant publications up to May 28, 2025, without language restrictions. Two investigators independently extracted study information and evaluated methodological quality as well as potential sources of bias. Eligible studies were observational in design and investigated the association between proton pump inhibitor (PPI) exposure and the risk of developing dementia compared with non-use. For the quantitative synthesis, pooled risk ratios (RRs) and corresponding confidence intervals were generated using a random-effects approach. Study Results: Eighteen studies, encompassing more than 6.3 million participants, met the inclusion criteria. The pooled estimate showed no statistically significant association between PPI use and overall dementia risk (RR = 1.14, 95% CI 0.98–1.33; I² = 99%). However, significant heterogeneity and variable risk of bias—particularly due to confounding, exposure misclassification, and immortal time bias—limit certainty in these findings. Subgroup analyses revealed significantly elevated risks among individuals aged ≥65 years (RR = 1.21, 95% CI 1.01–1.46) and in studies from Asia (RR = 1.31, 95% CI 1.12–1.52) and Europe (RR = 1.32, 95% CI 1.10–1.59), suggesting possible population- or context-specific vulnerability. Conclusions: Our findings reveal a lack of consistent evidence supporting a link between PPI use and dementia risk, primarily due to significant heterogeneity among existing studies. While no robust overall association was demonstrated, significant subgroup signals in older adults and specific regions suggest that clinical uncertainty remains. Rather than indicating a direct causal risk, these results underscore the importance of prescribing stewardship. Clinicians should focus on appropriate prescribing, ensuring long-term PPI therapy is reserved for patients with a clear therapeutic justification and utilized for the shortest effective duration. Full article

This study evaluates the performance and scalability of fluoride-salt-lubricated hydrodynamic journal bearings used in primary pumps for Fluoride-salt-cooled High-temperature Reactors (FHRs). Because full-scale pump prototypes have not been tested, a scaling analysis is used to relate laboratory results to commercial conditions. Bearings with different length-to-diameter (L/D) ratios were assessed over a range of shaft speeds to quantify geometric and hydrodynamic effects. High-temperature bushing test data in FLiBe at 650 °C were used as inputs to three-dimensional computational fluid dynamics (CFD) simulations in STAR-CCM+. Applied load, friction force, and power loss were computed across operating speeds. Applied load increases linearly with shaft speed due to hydrodynamic pressure buildup, while power loss increases approximately quadratically, indicating greater energy dissipation at higher speeds. The resulting correlations clarify scaling effects beyond small-scale testing and provide a basis for bearing design optimization, prototype development, and the deployment of FHR technology. This work benchmarks speed-scaling relations for fluoride-salt-lubricated hydrodynamic journal bearings within the investigated regime. Full article

Distributed energy systems (DES), such as photovoltaics (PV), heat pumps (HPs), and electric vehicles (EVs), are being rapidly integrated into low-voltage (LV) grids, while measurement coverage remains limited. This paper presents a concept for an LV grid digital twin designed to enable real-time state estimation (SE) and operation-oriented studies under constrained measurement availability. Based on this concept, an exemplary digital twin is developed and demonstrated for a test area with a high PV penetration. The proposed digital twin integrates a topology-aware grid model, realistic parameterization, standardized IEC 61850 data modeling, and a real-time estimation pipeline that processes heterogeneous measurement data, including PV inverter power and voltage as well as transformer and feeder measurements. The approach is demonstrated through software-in-the-loop (SIL) experiments using historical playback and accelerated simulations, as well as hardware-in-the-loop (HIL) tests for real-time operation. The SIL results show that the digital twin enables continuous grid monitoring, enhances transparency for distribution system operators (DSOs), and leverages existing infrastructure to increase the effective PV hosting capacity. Selective PV curtailment mitigates congestion and restores normal operation, indicating a potentially cost-effective alternative to grid reinforcement. The HIL experiments emphasize the importance of high-quality, standardized data. The achieved accuracy depends on data availability and synchronization, highlighting the need for improved data integration. Overall, the proposed approach provides a viable pathway toward data-driven planning and operation of LV grids with high DES penetration. Full article

The intestine–liver–muscle axis plays an essential role in drug and nutrient absorption, metabolism, and energy balance. Yet in vitro models capable of recapitulating this inter-organ communication remain limited. Here, we present a pump-free, 3D-printed multi-organ-on-a-chip device that enables dynamic co-culture of Caco-2 intestinal epithelial cells, HepG2 hepatocytes, and primary human skeletal myoblasts (HSkMs) under gravity-driven oscillatory flow. The device consists of five interconnected chambers designed to accommodate Transwell cell culture inserts for intestine and muscle compartments and hydrogel-embedded hepatocyte spheroids in the central hepatic compartment. The device was fabricated by low-cost fused deposition modeling (FDM) using acrylonitrile butadiene styrene (ABS) polymers. Under dynamic rocking, oscillatory perfusion promoted inter-organ communication without the need for external pumps or complex tubing. Biological assessments revealed that dynamic co-culture significantly enhanced the characteristics of skeletal muscle, as indicated by increased myosin heavy chain expression and elevated lactate production, while HepG2 spheroids exhibited improved hepatic function with higher albumin expression compared with monoculture. Additionally, Caco-2 cells maintained stable tight junctions and transepithelial electrical resistance, demonstrating preserved intestinal barrier integrity under dynamic flow. These results establish the device as a versatile, accessible 3D-printed platform for modeling the intestine–liver–muscle axis and investigating metabolic cross-talk in drug discovery and disease modeling. Full article

Smart agricultural systems need stable thermal environments for greenhouses, livestock housing, and on-farm processing. However, renewable heat sources such as solar collectors and heat pumps often cause fluctuations that challenge reliable operation. Thermal energy storage (TES)—particularly water-based sensible tanks, stratified reservoirs, and phase-change material (PCM) systems—provides an effective solution by decoupling heat supply and demand. In this review, tank-based TES technologies for agricultural applications, focusing on design, integration with renewable energy systems, and control strategies, are critically examined. Key performance aspects, including thermal stratification, state-of-charge estimation, and advanced predictive control, are analyzed to identify best practices and limitations. The review finds that sensible TES remains dominant in farm applications due to its low cost and durability, while latent (PCM/ice) and thermochemical storage provide a higher energy density and long-duration potential but are presently limited by material stability, system complexity, and cost. From an environmental perspective, TES contributes to reducing fossil fuel dependence, improving resource efficiency, lowering greenhouse gas emissions, and boosting the resilience of rural farming systems. Overall, TES is recognized as a key enabling technology for climate-smart, energy-efficient, and sustainable agricultural operations. However, remaining research gaps include long-term field validation, standardized performance metrics, and life-cycle environmental assessment. Full article

This paper presents the design, modeling and experimental validation of an on-grid photovoltaic system with self-consumption, sized for the sustainable supply of a water pumping station. The system, composed of 68 photovoltaic panels, uses an architecture based on a Boost DC-DC converter controlled by the Perturb and Observe algorithm, raising the operating voltage to a high-voltage DC bus to maximize the conversion efficiency. The study integrates dynamic performance analysis through simulations in the Simulink environment, testing the stability of the DC bus under sudden irradiance shocks, with rigorous experimental validation based on field production data. The simulation results, which indicate a peak DC power of approximately 34 kW, are confirmed by real monitoring data that records a maximum of 35 kW, the error being justified by the high efficiency of the panels and system losses. Long-term validation, carried out over three years of operation (2023–2025), demonstrates the reliability of the technical solution, with the system generating a total of 124.68 MWh. The analysis of energy flows highlights a degree of self-consumption of 60.08%, while the absence of chemical storage is compensated for by injecting the surplus of 49.78 MWh into the national grid, which is used as an energy buffer. The paper demonstrates that using the grid to balance night-time or meteorological deficits, in combination with a stabilized DC bus, represents an optimal technical-economic solution for critical pumping infrastructures, eliminating the maintenance costs of the accumulators and ensuring continuous operation. Full article

Acute kidney injury (AKI) affects thousands of hospitalized patients annually, yet early detection remains challenging as serum creatinine elevation lags behind clinical deterioration. Decreased urine output (UO) represents a key diagnostic criterion of AKI, sometimes manifesting hours before biochemical changes; however, current manual monitoring methods are labor-intensive and prone to error. Here, we developed and validated a simple, cost-effective automated urine flow meter using non-contact optical sensors, a peristaltic pump, and microcontroller-based automation for precise, real-time monitoring of urine output in clinical settings, named P-meter. Three successive prototypes (V1, V2, V3) were validated against gold-standard gravimetric measurements over 285 h of testing during animal experiments that required bladder catheterization. Iterative refinement addressed miniaturization challenges, fluid dynamics optimization, and sensor positioning to achieve progressively improved accuracy. The optimized V3 prototype demonstrated further enhanced volumetric precision, stability, and flow accuracy with near-unity linearity vs. reference method (R² = 0.9889), minimal bias (mean error −0.1 mL), and 94.18% agreement within confidence limits (n = 86), outperforming the initial V1 prototype (R² = 0.9971, mean error −1.69 mL, n = 207) and intermediate V2 design (R² = 0.9941, mean error 3.63 mL, n = 390), primarily in terms of reduced bias and improved agreement. The P-meter offers accurate urine output monitoring at a lower cost than commercial systems, facilitating its use in early AKI detection and thereby improving patient outcomes. Full article

To investigate the hydraulic instability mechanisms of low-specific-speed pump–turbines operating in turbine mode, this study experimentally characterized the pressure distribution and pulsation evolution on the guide vanes of a model unit (ns = 28) using an embedded sensor technique. By overcoming the accessibility limitations of traditional measurement methods, this research reveals the distinct pressure response mechanisms on the guide vane Front Side (upstream-facing) and Back Side (runner-facing). The results demonstrate that the time-averaged pressure distribution is highly sensitive to the Guide Vane Opening (GVO). Specifically, pressure on the Front Side increases with GVO, dominated by the improvement of flow pattern and stagnation effect, whereas pressure on the Back Side decreases monotonically, governed by the Bernoulli effect. Increasing the GVO significantly improves pressure uniformity, reducing the surface pressure gradient by 55%. Regarding dynamic characteristics, pressure fluctuation intensity on the Back Side is significantly higher than that on the Front Side. Furthermore, fluctuations are notably amplified near the tongue, confirming that flow distortion induced by the tongue is a key factor driving circumferential non-uniformity. Spectral analysis identifies the Blade Passing Frequency (BPF) as the dominant frequency, verifying Rotor–Stator Interaction (RSI) as the primary excitation source, while the guide vane channel exhibits a significant low-pass filtering effect on high-order harmonics. These findings provide a solid theoretical foundation and data support for the optimal design and stability control of pump–turbine guide vanes. Full article