Search Results (5,220)

Background/Objectives: The diagnostic value of Quantitative Flow Ratio (QFR) with respect to Fractional Flow Reserve (FFR) in real-world settings is not well described, and neither are the factors influencing the bias of QFR versus FFR well understood. The learning curve associated with QFR calculation has not been thoroughly investigated. Hence, we sought to evaluate the association between the QFR and FFR, to investigate the influence of clinical parameters on both values and their difference, and to analyze the learning curve associated with QFR measurement in a real-world setting. Methods: All patients who underwent FFR and QFR measurements in 2023 at our tertiary-care center were included. The bias was characterized using a Bland–Altman plot and multivariable regression was used to uncover its potential predictors. Results: QFR calculation was successful in 73% of 595 patients with 778 vessels with FFR measurement results. Median bias of QFR was 0.011, but in 7% of the cases, the difference between the two exceeded 0.10. A good correlation was found between the two indices. Receiver operating characteristic curve analysis showed that the area under the curve of QFR for predicting FFR ≤ 0.80 was 0.912. FFR and QFR values were lower in the left anterior descending artery; acute coronary syndrome indication was associated with higher QFR values. Right coronary artery localization was associated with a greater bias of QFR, whereas female gender and aortic stenosis were associated with a lower bias of QFR. Both measurement time and bias decreased in a non-linear fashion with increasing experience. Conclusions: Clinical and angiographic factors affect the bias of QFR versus FFR. QFR has a short learning curve with growing experience leading to shorter measurement time and less bias. Full article

Industrial processes such as cement, steel, and glass manufacturing rely heavily on fossil fuels for high-temperature heat, presenting a significant challenge for decarbonization. To enable continuous thermal output from intermittent renewable electricity, Electrified Thermal Solutions, Inc. is developing the Joule Hive™ Thermal Battery (JHTB), an electrically heated energy storage system capable of delivering process heat up to 1800 °C. The system employs electrically conductive firebricks (E-Bricks) as both heating elements and thermal storage media, arranged with insulating bricks (I-Bricks) to facilitate gas flow and heat exchange. The work combines experimental and numerical studies to evaluate the thermal, electrical, and structural performance of the JHTB. A small-scale charging experiment was conducted on a single E-Brick circuit in a 1500 °C furnace, showing good agreement with coupled thermal-electric finite element models that account for Joule heating, temperature-dependent properties, radiation, and natural convection. Structural modeling assessed stress induced by thermal gradients. In addition, a high-fidelity conjugate heat transfer model of the full JHTB core was developed to assess system-scale discharge performance, solving conservation equations with SST k-ω turbulence and radiation models. Simulations for two air channel geometries demonstrated the battery’s ability to deliver 5 MW of heat for at least five hours with air temperatures higher than 1000 °C, validating its potential for industrial decarbonization. Full article

A miniaturised bionic electronic nose system was developed to solve the problems of expensive equipment and long response time for soil pesticide residue detection. The structure of the bionic electronic nasal cavity is designed based on the spatial structure and olfactory principle of the sturgeon nasal cavity. Through experimental study, the structure of the nasal cavity of the sturgeon was extracted and analyzed. The 3D model of the bionic electronic nasal cavity was constructed and verified by Computational Fluid Dynamics (CFD) simulation. The results show that the gas flow distribution in the bionic chamber is more uniform than that in the ordinary chamber. The airflow velocity near the sensor in the bionic chamber is lower than in the ordinary chamber. The eddy current intensity near the bionic chamber sensor is 2.29 times that of the ordinary chamber, further increasing the contact intensity between odor molecules and the sensor surface and shortening the response time. The 10-fold cross-validation method of K-Nearest Neighbor (K-NN), Random Forest (RF) and Support Vector Machine (SVM) was used to compare the recognition performance of the bionic electronic nasal cavity with that of the ordinary electronic nasal cavity. The results showed that, when the bionic electronic nose detection system identified the concentration of pesticide residues in soil, the recognition rate of the above three recognition algorithms reached 97.3%, significantly higher than that of the comparison chamber. The bionic chamber electronic nose system can improve the detection performance of electronic noses and has a good application prospect in soil pesticide residue detection. Full article

To enhance the development efficiency of medium–deep geothermal resources in cold regions, this study focuses on a coaxial borehole heat exchanger (CBHE) located in Dapuzi Town, Xining City, Qinghai Province. Based on field-scale heat exchange experiments, a three-dimensional numerical model of the CBHE was developed using COMSOL Multiphysics 6.2, incorporating both conductive heat transfer in the surrounding geological formation and convective heat transfer within the wellbore. The model was calibrated and validated against measured data. On this basis, the effects of wellhead injection flow rate, injection temperature, and the thermal conductivity of the inner pipe on heat exchange performance were systematically analyzed. The results show that in cold regions with high altitudes (2000–3000 m) and medium–deep low-temperature geothermal reservoirs (68.8 °C), using a coaxial heat exchange system for space heating delivers good heat extraction performance, with a maximum average power output of 282.37 kW. Among the parameters, the injection flow rate has the most significant impact on heat extraction. When the flow rate increases from 10 m³/h to 30 m³/h, the heat extraction power increases by 57.58%. An increase in injection temperature helps suppress thermal short-circuiting and improves the effluent temperature, but excessively high temperatures lead to a decline in heat extraction. Additionally, increasing the thermal conductivity of the inner pipe significantly intensifies thermal short-circuiting and reduces overall heat exchange capacity. Under constant reservoir conditions, the thermal influence radius expands with both depth and operating time, reaching a maximum of 10.04 m by the end of the heating period. For the CBHE system in Dapuzi, maintaining an injection flow rate of 20–25 m³/h and an injection temperature of approximately 20 °C can achieve an optimal balance between effluent temperature and heat extraction. Full article

We studied the hemodynamics of abdominal aortic aneurysms (AAAs) by combining laboratory experiments and numerical simulations, with a focus on potential rupture mechanisms. In particular, we investigated the influence of geometrical features—beyond the commonly used maximum diameter—on flow patterns and the wall shear stress (WSS) distribution. Following our previous in vitro study performed utilizing a symmetrical bulge, we extended the analysis to an asymmetrical aneurysm geometry. Experiments and simulations were conducted under steady flow conditions while varying the Reynolds number over a wide range (490 < Re < 3930), to replicate the flow regimes occurring throughout the cardiac cycle. High-resolution, two-dimensional velocity fields were measured in the lab via image analysis and numerically computed using ANSYS Fluent^®. These data enabled a detailed characterization of both flow patterns and WSS distributions in healthy aorta and within the aneurysmal region. The good agreement between numerical and experimental results, as well as consistency with the literature, validates the adopted approach and supports its use for future investigations into AAA hemodynamics and rupture risk assessment. Full article

Monitoring surface water quality offers a clear understanding of its parameters over time and space. The Ibrahim River, one of the main rivers in Lebanon, was monitored over one hydrological year, from March 2021 to April 2022. Samples were collected from seven stations in the watershed, once every two weeks. A total of 504 samples were then analyzed for pH, conductivity, turbidity, total dissolved solids, dissolved oxygen, biochemical oxygen demand, dissolved nitrate, dissolved potassium, dissolved chloride, total alkalinity, fecal coliforms, and total coliforms. Principal Component Analysis (PCA) was able to highlight two principal components (PCs), representing spatial and temporal variations, identifying areas of pollution and the influence of flow on water quality. The adapted Water Quality Index (WQI) confirmed the PCA trend with an overall average for the entire watershed of 83.70 ± 4.97, indicating a “good” water quality. Full article

This essay focuses on the Greek adoptees’ search for identity and on the agrafa, or the “unwritten” territories, into which this search penetrates. The Greek adoptees represent an underresearched case study of the postwar intercountry adoption movement (1950–1975). Creating a narrative of the self is key to the adoptees’ identity formation, but their personal narrative is often undermined by stereotypes and denunciations that stunt its development. The research presented here has been guided by questions that interrogate the verdict-making or “sentencing” associated with the adoptees’ identity-shaping process: their sentencing to subjugation by stock opinions, the denouncing of their alternative viewpoints about “rescue” adoptions, and the verdict of their entrapment in feel-good master narratives. This essay also explores broader research questions pertaining to modes of interrogating “historic” adoptions from Greece. It is concerned with the why rather than with the how or the who of the oldest, post-WWII intercountry adoption flows. In what forums and genres (narrative, visual, journalistic, scholarly) are Greek adoption facts and legacies articulated, mediated, and/or materialized? How do memories, both positive and negative, underpin current projects of self-identification and transformation? What are the adoptees’ preferred outlets to speak about embodied experiences, and are those satisfactory? Based on a mixed methods approach, the essay ties these steps in identity growth to the Adoptee Consciousness Model, illustrating the five phases of consciousness that the adoptees may experience throughout their lives. Full article

This study utilized SRAP molecular markers to analyze the genetic basis of 106 multigerm sugar beet germplasm accessions. By revealing the genetic diversity, population structure, and differentiation patterns, it aimed to tap into the germplasm potential, guide core germplasm construction and hybrid combination optimization, and ultimately design a molecular breeding route to break through bottlenecks in sugar beet genetic breeding. In total, 24 core primer combinations were screened from 546 initial primer pairs for genomic DNA amplification. The results demonstrated that each primer combination amplified an average of five alleles. Genetic parameter calculations revealed moderate variation potential. Population structure analysis divided the germplasm into four genetic groups (G1–G4), highly consistent with cluster analysis and DAPC analysis results. Its reliability was jointly confirmed by STRUCTURE convergence verification (LnP(K) standard deviation) and cluster goodness-of-fit testing (r = 0.63166, p < 0.0001). Key findings indicated that Group G4 possesses a unique genetic background, and the maximum genetic distance exists between Group G1 and the other three groups, indicating its significant genetic differentiation characteristics. Gene exchange exists between the G3 and G4 populations. Genetic variation primarily originated from within populations (93%, F_ST = 0.1283). Genetic distances spanned from 0.385 (between accessions 66 and 71 within a group) to 0.836 (between accessions 47 and 85 across groups). Concurrently, gene flow analysis (Nm = 3.3977) indicated moderate genetic exchange among populations. This achievement established the first SRAP marker-based genetic architecture for multigerm sugar beet germplasm resources. It provides a quantitative population genetics basis for formulating targeted strategies for germplasm resource conservation and utilization, and lays the foundation for constructing an innovation system for sugar beet germplasm resources. Full article

As the demand for efficient heat dissipation in information devices continues to escalate, the heat flux of integrated packaging devices is poised to reach 100 W/cm² universally, rendering microchannel liquid cooling technology a pivotal solution in thermal management. In this work, the microchannel heat sink with spoiler cavities, optimized via field synergy principle, was integrated into the high-power electronics, and its flow and heat transfer performance were experimentally investigated using Al₂O₃-water nanofluid. The results show that the experimental and simulation results of the optimized microchannel heat sink integrated with IGBT devices are in good agreement. With structural optimization combined with an appropriate volume fraction of nanofluid, the microchannel heat sink exhibited significantly better heat dissipation performance than that of rectangular heat sinks under a heat flux of 100 W/cm². Furthermore, when the volumetric flow rate exceeded 0.6 mL/s, the heat transfer performance was improved by 38% compared to the rectangular microchannel heat sink with 1% volume fraction of Al₂O₃-water nanofluid. Full article

The main goal of this study is to create a computational solver that analyzes the effects of magnetohydrodynamics (MHD) on heat radiation in Cu–water-based Prandtl nanofluid flow using artificial neural networks. Copper nanoparticles are utilized to boost the water-based fluid’s thermal effect. This study primarily focuses on heat transfer over a horizontal sheet, exploring different scenarios by varying key factors such as the magnetic field and thermal radiation properties. The mathematical model is formulated using partial differential equations (PDEs), which are then transformed into a corresponding set of ordinary differential equations (ODEs) through appropriate similarity transformations. The bvp4c solver is then used to simulate the numerical behavior. The effects of relevant parameters on the temperature, velocity, skin friction, and local Nusselt number profiles are examined. It is discovered that the parameters of the Prandtl fluid have a considerable impact. The local skin friction and the local Nusselt number are improved by increasing these parameters. The dataset is split into 70% training, 15% validation, and 15% testing. The ANN model successfully predicts skin friction and Nusselt number profiles, showing good agreement with numerical simulations. This hybrid framework offers a robust predictive approach for heat management systems in industrial applications. This study provides important insights for researchers and engineers aiming to comprehend flow characteristics and their behavior and to develop accurate predictive models. Full article

In recent years, experts have associated forecasts of global energy consumption with energy transitions. This paper presents the research results of the paths and trajectories of the global transformations of world energy, including demographic, technological, energy, transport, and communication changes. After demonstrating the long-term trends in global energy consumption, fossil and renewable energy sources, and nuclear energy using neuroforecasting methods, this study explains global demographic development and its relationship with global innovation and technological processes as explained by the flow of global patent applications. The relationship between energy transition and the previously mentioned two factors is also justified based on the trajectories developed by the neural network forecasting. By leveraging the fundamental laws of energy conservation, robust patterns in the evolution and development of global energy could be identified. It is demonstrated that mankind has entered the era of four closely interconnected global transitions: demographic, energy, technological, and political–economic, all at once. According to the results, civilizational changes are currently taking place in global energy advancement, indicating an energy transition to a new quality of energy development. The permanent growth patterns of the energy density of energy sources used and their impact on labor productivity and the speed of movement of people and goods in the economy are also discussed. Finally, the contour of future developments in energy technologies is determined. It is also forecast that future energy technologies are expected to be largely associated with the exploration of outer space, development of robotics, and the expansion of artificial intelligence capabilities. Full article

This study aims to develop a new model for windage losses, building upon existing formulation, complemented by dedicated experimental campaigns and a specific methodology designed to isolate and quantify windage losses. The model relies on an analytical approach to flow characterization, incorporating a correction factor accounting for air density reduction. The experimental investigation was carried out on a dedicated test bench and includes both spur and helical gears. The results demonstrate good agreement between the proposed model and the experimental data, with and without the presence of nearby obstacles, such as side flanges, highlighting the model’s robustness across different configurations. The proposed windage loss model reproduces the experimental results with significantly greater accuracy than the original one, yielding relative deviations below 5% compared to almost 20% for spur gears, and below 9% compared to over 21%, and in some cases up to 50%, for helical gears. Full article

The integration of axial flux motors into canned motor pumps offers a promising approach to overcome the efficiency and size limitations of traditional designs, particularly in critical sectors like aerospace. However, the hydrodynamics in magnetic gap between the stator and rotor are poorly understood. This study investigates the effect of magnetic gap on performance and internal flow. Six magnetic gap schemes are developed, ranging from 0.2 to 1.2 mm. Numerical simulations are conducted, and simulation results showed good agreement with experimental data. The magnetic gap exhibits a non-linear effect on performance. The peak head coefficient occurs at a 0.4 mm gap and maximum efficiency at 1.0 mm. At a 0.2 mm gap, strong viscous shear forces increase disk friction loss and create high-vorticity flow. As the gap widens, flow transitions from viscosity-dominated to inertia-dominated, leading to a more ordered flow structure. The blade passing frequency is the dominant frequency. For a gap of 0.8 mm, the pressure fluctuation intensity is lowest. By analyzing performance, head coefficient, velocity, vorticity, entropy production, and pressure fluctuations, a gap of 0.8 mm is identified as the optimal design. This study provides critical guidance for optimizing the design of axial flux canned motor pumps. Full article

This study introduces a cost-effective solution and sensor arrays for the multipoint liquid-level measuring sensor based on an intensity modulation technique. The sensor structure is based on the twisting of two fibers and creates cascading to achieve a multipoint detection. Three sensors are fabricated on a single illuminated polymer optical fiber. The twisting creates side-coupling between two fibers, and the coupled power is attenuated when liquid emerges in the coupled region. Each sensor has its own output source, which is connected to the power meter. When the liquid-level increases, the coupled power is continuously decreased. The multipoint liquid-level sensor is theoretical and experimentally tested. The experimental results show that sensors have a good response and linearity. The sensors are able to measure the liquid-level up to 12 cm and have a sensitivity of about 0.2726 μW/cm, 0.1715 μW/cm, and 0.1281 μW/cm, respectively. The different flow rate (50 mL/min–300 mL/min) is also analyzed to validate the dynamic response of the sensor. The sensor demonstrates a high sensitivity and resolution in the liquid-level detection. Meanwhile, the liquid-level variation is individually and simultaneously measured. The system does not require any decoupling technique as the system relies on a single LED source, and the coupled power is individually measured from each power meter. The system represents a significant advancement in precise liquid-level sensing technology, as the system has advantages of a flexible, durable, cost-effective, and active response with respect to changes in the liquid-level. Full article

Cavitating flows are of great interest in the fields of hydraulic machineries, which can significantly affect mechanical performance and safety. Despite various efforts being dedicated to figuring out the interaction between flow and cavitation fields, their correlation has not been clearly addressed. To this end, in this study, a convolutional neural network, U-Net, was adopted to build a model that can predict the vapor volume fraction from velocity fields. Large eddy simulations of cavitating flows around a Clark-Y hydrofoil were conducted, and the simulated snapshots with velocity and vapor volume fraction were adopted as a dataset for training the network. The predicted vapor volume fraction shows good agreement with the referred simulation results, with a L₁ deviation lower than 2 × 10⁻⁴, considering all the snapshots. The comparable L₁ deviation between the training and validation datasets suggests the existence of a strong correlation between velocity and cavitation fields. The cavitation–velocity interaction derived from using U-Net suggests that the location with zero velocity indicates the interior part of attached and cloud cavitations, and the local vortical velocity fields usually suggest the existence of cavitation shedding. Full article