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Search Results (1,077)

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Keywords = flow–compaction

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18 pages, 3181 KB  
Article
Effect of Matrix Properties and Pipe Characteristics on Internal Erosion in Unsaturated Clayey Sand Slope
by Olaniyi Afolayan, Anna Lancaster and Jack Montgomery
Geosciences 2025, 15(10), 405; https://doi.org/10.3390/geosciences15100405 - 17 Oct 2025
Abstract
Soil piping is the process by which subsurface water creates and enlarges channels, or “pipes,” within soil, enabling rapid and preferential flow beneath the surface. The collapse of these eroded pipes can lead to land degradation, gully formation, and potential damage to overlying [...] Read more.
Soil piping is the process by which subsurface water creates and enlarges channels, or “pipes,” within soil, enabling rapid and preferential flow beneath the surface. The collapse of these eroded pipes can lead to land degradation, gully formation, and potential damage to overlying infrastructure. While the structural consequences of pipe collapse are well recognized, there is limited understanding of the factors controlling pipe collapse and how water within the pipe influences moisture levels within a slope. This study used physical models of unsaturated slopes to examine how compaction conditions, pipe characteristics, and hydraulic conditions affect the progression of internal erosion. Models were created with different initial pipe sizes, moisture contents, densities at compaction and levels of pipe connectivity. Volumetric water content (VWC) sensors and cameras were used to monitor the slope response to subsurface flow, and measurements of pipe geometry were collected after the tests. Results showed that lower initial soil water content was more susceptible to pipe collapse, while higher water content showed improved pipe stability and sustained preferential flow. Fully connected pipes grew through erosion due to the pipe flow, while disconnected pipes grew mainly through local pipe collapse. Hydraulic equilibrium and soil erodibility affected the final pipe morphology more than the initial pipe size. These experimental results demonstrate that soil fabric and hydraulic connectivity of the pipe control the progression of piping, likelihood of collapse, and movement of water within the soil matrix. Full article
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17 pages, 2060 KB  
Article
Continuous Optical Biosensing of IL-8 Cancer Biomarker Using a Multimodal Platform
by A. L. Hernandez, K. Mandal, B. Santamaria, S. Quintero, M. R. Dokmeci, V. Jucaud and M. Holgado
Bioengineering 2025, 12(10), 1115; https://doi.org/10.3390/bioengineering12101115 - 17 Oct 2025
Viewed by 54
Abstract
In this work, we used a label-free biosensor that provides optical readouts to perform continuous detection of human interleukin 8 (IL-8), which is especially overexpressed in certain cancers and, thus, could be an effective biomarker for cancer prognosis estimation and therapy evaluation. For [...] Read more.
In this work, we used a label-free biosensor that provides optical readouts to perform continuous detection of human interleukin 8 (IL-8), which is especially overexpressed in certain cancers and, thus, could be an effective biomarker for cancer prognosis estimation and therapy evaluation. For this purpose, we engineered a compact, portable, and easy-to-assemble biosensing module device. It combines a fluidic chip for reagent flow, a biosensing chip for signal transduction, and an optical readout head based on fiber optics in a single module. The biosensing chip is based on independent arrays of resonant nanopillar transducer (RNP) networks. We integrated the biosensing chip with the RNPs facing down in a simple and rapidly fabricated polydimethyl siloxane (PDMS) microfluidic chip, with inlet and outlet channels for the sample flowing through the RNPs. The RNPs were vertically oriented from the backside through an optical fiber mounted on a holder head fabricated ad hoc on polytetrafluoroethylene (PTFE). The optical fiber was connected to a visible spectrometer for optical response analysis and consecutive biomolecule detection. We obtained a sensogram showing anti-IL-8 immobilization and the specific recognition of IL-8. This unique portable and easy-to-handle module can be used for biomolecule detection within minutes and is particularly suitable for in-line sensing of physiological and biomimetic organ-on-a-chip systems. Cancer biomarkers’ continuous monitoring arises as an efficient and non-invasive alternative to classical tools (imaging, immunohistology) for determining clinical prognostic factors and therapeutic responses to anticancer drugs. In addition, the multiplexed layout of the optical transducers and the simplicity of the monolithic sensing module yield potential high-throughput screening of a combination of different biomarkers, which, together with other medical exams (such as imaging and/or patient history), could become a cutting-edge technology for further and more accurate diagnosis and prediction of cancer and similar diseases. Full article
(This article belongs to the Section Biosignal Processing)
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18 pages, 1493 KB  
Article
Influence of Guar Gum and Xanthan Gum on the Rheological Behavior, Texture, and Microstructure of Probiotic Low-Fat Yogurt
by Yaser Elderwy, Ratul Kalita, Mahmoud E. A. Hamouda, Pratibha Chaudhary, Mohamed S. Elfaruk, Pramith U. Don and Omar A. A. Abdelsater
Processes 2025, 13(10), 3301; https://doi.org/10.3390/pr13103301 - 15 Oct 2025
Viewed by 618
Abstract
The aim of this study was to investigate the effects of the addition of guar gum (GG) and xanthan gum (XG) on the proximate composition, texture, viscosity, syneresis, color characteristics, microbiological stability, sensory evaluation, rheological properties, and microstructure of a low-fat yogurt sample. [...] Read more.
The aim of this study was to investigate the effects of the addition of guar gum (GG) and xanthan gum (XG) on the proximate composition, texture, viscosity, syneresis, color characteristics, microbiological stability, sensory evaluation, rheological properties, and microstructure of a low-fat yogurt sample. The results showed that adding GG and XG at concentrations of 0.5 and 1% increased the hardness and viscosity of yogurt significantly (p < 0.05), with XG having a more pronounced effect. There was no significant difference (p > 0.05) in color characteristics between all treatments during the storage period. The viability of probiotics was enhanced in gum-supplemented yogurts, with XG providing better protection for Lactobacillus delbrueckii subsp. bulgaricus and Bifidobacterium bifidum during storage. Sensory evaluation results showed that XG samples gained higher scores as compared to GG samples. Rheological analysis revealed that both the hydrocolloids guar gum (GG) and xanthan gum (XG) significantly increased the parameters such as viscosity and yield stress of low-fat yogurt, with xanthan gum having a more pronounced effect on enhancing the flow behavior. Microstructural analysis using scanning electron microscopy revealed that XG supplementation improved the yogurt gel network, developing a more compact and cohesive structure; however, GG produced a looser and more dispersed network. Overall, both GG and XG enhanced the rheological, textural, and microstructural characteristics of low-fat yogurt, with XG showing superior effects on texture, gel structure, and probiotic stability. Full article
(This article belongs to the Section Food Process Engineering)
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12 pages, 958 KB  
Article
Evaluating Disinfection Performance and Energy Efficiency of a Dual-Wavelength UV-LED Flow-Through Device for Point-of-Use Water Treatment
by Yoontaek Oh, Hyun-Chul Kim, Laura Boczek and Hodon Ryu
Water 2025, 17(20), 2965; https://doi.org/10.3390/w17202965 - 15 Oct 2025
Viewed by 178
Abstract
Ultraviolet-light emitting diodes (UV-LEDs) offer several advantages over conventional mercury-based UV lamps, including wavelength selectivity, compact size, design flexibility, instant on/off, power output adjustment, and mercury-free operation. These features position UV-LEDs as ideal candidates for point-of-use (POU) water disinfection systems, particularly in decentralized [...] Read more.
Ultraviolet-light emitting diodes (UV-LEDs) offer several advantages over conventional mercury-based UV lamps, including wavelength selectivity, compact size, design flexibility, instant on/off, power output adjustment, and mercury-free operation. These features position UV-LEDs as ideal candidates for point-of-use (POU) water disinfection systems, particularly in decentralized or resource-limited environments. In this study, we evaluated the microbial inactivation performance and energy efficiency of a bench-scale flow-through UV-LED POU system using indigenous heterotrophic plate count (HPC) bacteria, E. coli, and MS2 bacteriophage. The system was tested under various flow rates (1–4 L/min) and wavelength configurations (265 nm, 278 nm, and dual-wavelength combinations). MS2 bacteriophage was further used in collimated beam testing to validate UV-fluence-response curves and to estimate delivered doses in the flow-through POU device. HPC inactivation was enhanced under dual-wavelength conditions, suggesting wavelength-specific synergy, while E. coli showed high susceptibility across all wavelength configurations, achieving >2-log inactivation at significantly reduced UV-LED power (1/6 of that required for HPC) even at 4 L/min. Specific energy consumption analysis showed energy demands as low as 0.032–0.053 kWh/m3 for achieving 4-log inactivation of E. coli, with an estimated annual operating cost for UV-LED irradiation below $1.70. These findings demonstrate the potential of UV-LED-based POU devices as safe, energy-efficient, and cost-effective technologies for decentralized water treatment. Full article
(This article belongs to the Section Water Quality and Contamination)
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34 pages, 15906 KB  
Article
Investigation of the Relationship Between Reservoir Sensitivity and Injectivity Impedance in Low-Permeability Reservoirs
by Baolei Liu, Youqi Wang, Hongmin Yu, Xiang Li and Lingfeng Zhao
Processes 2025, 13(10), 3283; https://doi.org/10.3390/pr13103283 - 14 Oct 2025
Viewed by 246
Abstract
In low-permeability reservoirs, studying reservoir sensitivity is crucial for optimizing water flooding, as it identifies detrimental mineral-fluid interactions that can cause formation damage and reduce injection efficiency. However, existing diagnostic methods for sensitivity-induced damage rely on post-facto pressure monitoring and lack a quantitative [...] Read more.
In low-permeability reservoirs, studying reservoir sensitivity is crucial for optimizing water flooding, as it identifies detrimental mineral-fluid interactions that can cause formation damage and reduce injection efficiency. However, existing diagnostic methods for sensitivity-induced damage rely on post-facto pressure monitoring and lack a quantitative relationship between sensitivity factors and water injectivity impairment. Furthermore, correlating microscale interactions with macroscopic injectivity parameters remains challenging, causing current models to inadequately represent actual injection behavior. This study combines microscopic techniques (e.g., SEM, XRD, NMR) with macroscopic core flooding experiments under various sensitivity-inducing conditions to analyze the influence of reservoir mineral composition on flow capacity, evaluate formation sensitivity, and assess the dynamic impact on water injectivity. The quantitative relationship between clay minerals and injectivity impairment in low-permeability reservoirs is also investigated. The results indicate that flow capacity is predominantly governed by the type and content of sensitive minerals. In water-sensitive reservoirs, water injection induces clay swelling and migration, leading to flow path reconfiguration and water-blocking effects. In salt-sensitive formations, high-salinity water promotes salt precipitation within pore throats, reducing permeability. In velocity-sensitive formations, fine particle migration causes flow resistance to initially increase slightly and then gradually decline with continued injection. Acidizing generally enhances pore connectivity but induces pore-throat plugging in chlorite-rich reservoirs. Alkaline fluids can exacerbate heterogeneity and generate precipitates, though appropriate concentrations may improve connectivity. Under low effective stress, rock dilation increases porosity and permeability, while elevated stress causes compaction, increasing flow impedance. Full article
(This article belongs to the Special Issue Advanced Strategies in Enhanced Oil Recovery: Theory and Technology)
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24 pages, 5112 KB  
Article
Power Management for V2G and V2H Operation Modes in Single-Phase PV/BES/EV Hybrid Energy System
by Chayakarn Saeseiw, Kosit Pongpri, Tanakorn Kaewchum, Sakda Somkun and Piyadanai Pachanapan
World Electr. Veh. J. 2025, 16(10), 580; https://doi.org/10.3390/wevj16100580 - 14 Oct 2025
Viewed by 264
Abstract
A multi-port conversion system that connects photovoltaic (PV) arrays, battery energy storage (BES), and an electric vehicle (EV) to a single-phase grid offers a flexible solution for smart homes. By integrating Vehicle-to-Grid (V2G) and Vehicle-to-Home (V2H) technologies, the system supports bidirectional energy flow, [...] Read more.
A multi-port conversion system that connects photovoltaic (PV) arrays, battery energy storage (BES), and an electric vehicle (EV) to a single-phase grid offers a flexible solution for smart homes. By integrating Vehicle-to-Grid (V2G) and Vehicle-to-Home (V2H) technologies, the system supports bidirectional energy flow, optimizing usage, improving grid stability, and supplying backup power. The proposed four-port converter consists of an interleaved bidirectional DC-DC converter for high-voltage BES, a bidirectional buck–boost DC-DC converter for EV charging and discharging, a DC-DC boost converter with MPPT for PV, and a grid-tied inverter. Its non-isolated structure ensures high efficiency, compact design, and fewer switches, making it suitable for residential applications. A state-of-charge (SoC)-based power management strategy coordinates operation among PV, BES, and EV in both on-grid and off-grid modes. It reduces reliance on EV energy when supporting V2G and V2H, while SoC balancing between BES and EV extends lifetime and lowers current stress. A 7.5 kVA system was simulated in MATLAB/Simulink to validate feasibility. Two scenarios were studied: PV, BES, and EV with V2G supporting the grid and PV, BES, and EV with V2H providing backup power in off-grid mode. Tests under PV fluctuations and load variations confirmed the effectiveness of the proposed design. The system exhibited a fast transient response of 0.05 s during grid-support operation and maintained stable voltage and frequency in off-grid mode despite PV and load fluctuations. Its protection scheme disconnected overloads within 0.01 s, while harmonic distortions in both cases remained modest and complied with EN50610 standards. Full article
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20 pages, 3107 KB  
Article
Observer-Based Volumetric Flow Control in Nonlinear Electro-Pneumatic Extrusion Actuator with Rheological Dynamics
by Ratchatin Chancharoen, Chaiwuth Sithiwichankit, Kantawatchr Chaiprabha, Setthibhak Suthithanakom and Gridsada Phanomchoeng
Actuators 2025, 14(10), 496; https://doi.org/10.3390/act14100496 - 14 Oct 2025
Viewed by 156
Abstract
Consistent volumetric flow control is essential in extrusion-based additive manufacturing, particularly when printing viscoelastic materials with complex rheological properties. This study proposes a control framework incorporating simplified rheological dynamics via a Kelvin–Voigt model that integrates nonlinear dynamic modeling, an unknown input observer (UIO), [...] Read more.
Consistent volumetric flow control is essential in extrusion-based additive manufacturing, particularly when printing viscoelastic materials with complex rheological properties. This study proposes a control framework incorporating simplified rheological dynamics via a Kelvin–Voigt model that integrates nonlinear dynamic modeling, an unknown input observer (UIO), and a closed-loop PID controller to regulate material flow in a motorized electro-pneumatic extrusion system. A comprehensive state-space model is developed, capturing both mechanical and rheological dynamics. The UIO estimates unmeasurable internal states—specifically, syringe plunger velocity—which are critical for real-time flow regulation. Simulation results validate the observer’s accuracy, while experimental trials with a curing silicone resin confirm that the system can achieve steady extrusion and maintain stable linewidth once transient disturbances settle. The proposed system leverages a dual-mode actuation mechanism—combining pneumatic buffering and motor-based adjustment—to achieve responsive and robust control. This architecture offers a compact, sensorless solution well-suited for high-precision applications in bioprinting, electronics, and soft robotics, and provides a foundation for intelligent flow regulation under dynamic material behaviors. Full article
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19 pages, 6415 KB  
Article
Combustion and Heat-Transfer Characteristics of a Micro Swirl Combustor-Powered Thermoelectric Generator: A Numerical Study
by Kenan Huang, Jiahao Zhang, Guoneng Li, Yiyuan Zhu, Chao Ye and Ke Li
Aerospace 2025, 12(10), 916; https://doi.org/10.3390/aerospace12100916 - 11 Oct 2025
Viewed by 237
Abstract
Micro-combustion-powered thermoelectric generators (μ-CPTEGs) combine the high energy density of hydrocarbons with solid-state conversion, offering compact and refuelable power for long-endurance electronics. Such characteristics make μ-CPTEGs particularly promising for aerospace systems, where conventional batteries face serious limitations. Their achievable performance [...] Read more.
Micro-combustion-powered thermoelectric generators (μ-CPTEGs) combine the high energy density of hydrocarbons with solid-state conversion, offering compact and refuelable power for long-endurance electronics. Such characteristics make μ-CPTEGs particularly promising for aerospace systems, where conventional batteries face serious limitations. Their achievable performance hinges on how a swirl-stabilized flame transfers heat into the hot ends of thermoelectric modules. This study uses a conjugate CFD framework coupled with a lumped parameter model to examine how input power and equivalence ratio shape the flame/flow structure, temperature fields, and hot-end heating in a swirl combustor-powered TEG. Three-dimensional numerical simulations were performed for the swirl combustor-powered TEG, varying the input power from 1269 to 1854 W and the equivalence ratio from φ = 0.6 to 1.1. Results indicate that the combustor exit forms a robust “annular jet with central recirculation” structure that organizes a V-shaped region of high modeled heat release responsible for flame stabilization and preheating. At φ = 1.0, increasing Qin from 1269 to 1854 W strengthens the V-shaped hot band and warms the wall-attached recirculation. Heating penetrates deeper into the finned cavity, and the central-plane peak temperature rises from 2281 to 2339 K (≈2.5%). Consistent with these field changes, the lower TEM pair near the outlet heats more strongly than the upper module (517 K to 629 K vs. 451 K to 543 K); the inter-row gap widens from 66 K to 86 K, and the incremental temperature gains taper at the highest power, while the axial organization of the field remains essentially unchanged. At fixed Qin = 1854 W, raising φ from 0.6 to 1.0 compacts and retracts the reaction band toward the exit and weakens axial penetration; the main-zone temperature increases up to φ = 0.9 and then declines for richer mixtures (peak 2482 K at φ = 0.9 to 2289 K at φ = 1.1), cooling the fin section due to reduced transport, thereby identifying φ = 0.9 as the operating point that best balances axial penetration against dilution/convective-cooling losses and maximizes the TEM hot-end temperature at the fixed power. Full article
(This article belongs to the Special Issue Advances in Thermal Fluid, Dynamics and Control)
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18 pages, 3116 KB  
Article
A Study on the Structure and Properties of NiCr-DLC Films Prepared by Filtered Cathodic Vacuum Arc Deposition
by Bo Zhang, Lan Zhang, Shuai Wu, Xue Peng, Xiaoping Ouyang, Bin Liao and Xu Zhang
Coatings 2025, 15(10), 1136; https://doi.org/10.3390/coatings15101136 - 1 Oct 2025
Viewed by 300
Abstract
Diamond-like carbon (DLC) films are valued for their high hardness and wear resistance, but their application in harsh environments is limited by high internal stress and poor corrosion resistance. Co-doping with transition metals offers a promising route to overcome these drawbacks by tailoring [...] Read more.
Diamond-like carbon (DLC) films are valued for their high hardness and wear resistance, but their application in harsh environments is limited by high internal stress and poor corrosion resistance. Co-doping with transition metals offers a promising route to overcome these drawbacks by tailoring microstructure and enhancing multifunctional performance. However, the synergistic effects of Ni and Cr co-doping in DLC remain underexplored. In this study, Ni and Cr co-doped DLC (NiCr-DLC) films were fabricated using filtered cathodic vacuum arc deposition (FCVAD). By varying the C2H2 flow rate, the carbon content and microstructure evolved from columnar to fine-grained and compact structures. The optimized film (F55) achieved an ultralow surface roughness (Sa = 0.26 nm), even smoother than the Si substrate. The Ni–Cr co-doping promoted a nanocomposite structure, yielding a maximum hardness of 15.56 GPa and excellent wear resistance (wear rate: 4.45 × 10−7 mm3/N·m). Electrochemical tests revealed significantly improved corrosion resistance compared to AISI 304L stainless steel, with F55 exhibiting the highest corrosion potential, the lowest current density, and the largest impedance modulus. This work demonstrates that Ni-Cr co-doping effectively enhances the mechanical and corrosion properties of DLC films while improving surface quality, providing a viable strategy for developing robust, multifunctional protective coatings for demanding applications in aerospace, automotive, and biomedical systems. Full article
(This article belongs to the Section Thin Films)
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20 pages, 3712 KB  
Article
Analysis of Control Factors for Sensitivity of Coalbed Methane Reservoirs
by Peng Li, Cong Zhang, Bin Fan, Jie Zhang and Zhongxiang Zhao
Processes 2025, 13(10), 3133; https://doi.org/10.3390/pr13103133 - 29 Sep 2025
Viewed by 540
Abstract
Formation damage sensitivity is a primary constraint on productivity in coalbed methane (CBM) reservoirs. Conventional experimental methods, which often employ crushed or plug coal samples, disrupt the natural fracture network, thereby overestimating matrix damage and underestimating fracture-related damage. In this study, synchronous comparative [...] Read more.
Formation damage sensitivity is a primary constraint on productivity in coalbed methane (CBM) reservoirs. Conventional experimental methods, which often employ crushed or plug coal samples, disrupt the natural fracture network, thereby overestimating matrix damage and underestimating fracture-related damage. In this study, synchronous comparative experiments were conducted using raw coal and briquette coal cores, integrated with scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR) analyses to characterize coal composition and pore structure. This approach elucidates the underlying mechanisms controlling reservoir sensitivity. The main findings are as follows: The dual-sample comparative system reveals substantial deviations in traditional experimental assessments. Due to post-dissolution compaction, briquette coal samples overestimate acid sensitivity while underestimating water sensitivity. Stress sensitivity is primarily attributed to the irreversible compression of natural fractures. Differences in acid sensitivity are governed by structural integrity: mineral dissolution leads to collapse in briquette coal, whereas fractures help maintain stability in raw coal. Raw coal exhibits a lower critical flow rate for velocity sensitivity and undergoes significant water sensitivity damage below 1 MPa. Both sample types show weak alkaline sensitivity, with damage acceleration observed within the pH range of 7 to 10. Full article
(This article belongs to the Section Energy Systems)
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16 pages, 3297 KB  
Article
Effect of High-Temperature Isothermal Annealing on the Structure and Properties of Multicomponent Compact Ti-Al(Nb,Mo,B)-Based Materials Fabricated via Free SHS-Compression
by Pavel Bazhin, Ivan Nazarko, Arina Bazhina, Andrey Chizhikov, Alexander Konstantinov, Artem Ivanov, Mikhail Antipov, Pavel Stolin, Svetlana Agasieva and Varvara Avdeeva
Metals 2025, 15(10), 1088; https://doi.org/10.3390/met15101088 - 29 Sep 2025
Viewed by 275
Abstract
This study investigates TNM-type titanium aluminide alloys, representing the third generation of β-stabilized γ-TiAl heat-resistant materials. The aim of this work is to study the combustion characteristics and to produce compact materials via the free SHS compaction method from initial powder reagents taken [...] Read more.
This study investigates TNM-type titanium aluminide alloys, representing the third generation of β-stabilized γ-TiAl heat-resistant materials. The aim of this work is to study the combustion characteristics and to produce compact materials via the free SHS compaction method from initial powder reagents taken in the following ratio (wt%): 51.85Ti–43Al–4Nb–1Mo–0.15B, as well as to determine the effect of high-temperature isothermal annealing at 1000 °C on the structure and properties of the obtained materials. Using free SHS compression (self-propagating high-temperature synthesis), we synthesized compact materials from a 51.85Ti–43Al–4Nb–1Mo–0.15B (wt%) powder blend. Key combustion parameters were optimized to maximize the synthesis temperature, employing a chemical ignition system. The as-fabricated materials exhibit a layered macrostructure with wavy interfaces, aligned parallel to material flow during compression. Post-synthesis isothermal annealing at 1000 °C for 3 h promoted further phase transformations, enhancing mechanical properties including microhardness (up to 7.4 GPa), Young’s modulus (up to 200 GPa) and elastic recovery (up to 31.8%). X-ray powder diffraction, SEM, and EDS analyses confirmed solid-state diffusion as the primary mechanism for element interaction during synthesis and annealing. The developed materials show promise as PVD targets for depositing heat-resistant coatings. Full article
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23 pages, 9649 KB  
Article
Two-Phase Flow Simulation of Bubble Cross-Membrane Removal Dynamics in Boiling-Desorption Mode for Microchannel Membrane-Based Generators
by Jianrong Zhai, Hongtao Gao and Yuying Yan
Energies 2025, 18(19), 5156; https://doi.org/10.3390/en18195156 - 28 Sep 2025
Viewed by 196
Abstract
Compact and efficient absorption refrigeration systems can effectively utilize waste heat and renewable energy when operated in a boiling-desorption mode, which maximizes the desorption rate. Hydrophobic membranes play a critical role in microchannel membrane-based generators; however, limited research has addressed bubble cross-membrane removal [...] Read more.
Compact and efficient absorption refrigeration systems can effectively utilize waste heat and renewable energy when operated in a boiling-desorption mode, which maximizes the desorption rate. Hydrophobic membranes play a critical role in microchannel membrane-based generators; however, limited research has addressed bubble cross-membrane removal dynamics under boiling-desorption conditions, particularly the influence of membrane hydrophobicity. In this study, a two-phase flow bubble-removal model was developed to accurately represent boiling-desorption behavior. Numerical simulations were performed to investigate the effects of membrane hydrophobicity and heating power on bubble dynamics, wall temperature, venting rate, and channel pressure drop. Results show that bubble venting proceeds through four stages: nucleation and growth, liquid-film rupture with deformation, lateral spreading, and sustained vapor removal. Hydrophobicity effects become most significant from the third stage onwards. Increased hydrophobicity reduces wall temperature, with greater reductions at higher heat fluxes, and enhances venting performance by increasing total vapor removal and reducing removal time. Channel pressure fluctuations comprise high-frequency components from bubble growth and low-frequency components from venting-induced flow interruptions, with relative contributions dependent on hydrophobicity and heat flux. These findings provide new insights into bubble-removal mechanisms and offer guidance for the design and optimization of high-performance microchannel membrane-based generators. Full article
(This article belongs to the Section J1: Heat and Mass Transfer)
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14 pages, 2376 KB  
Article
Experimental Study on Water Reduction of Grouting Slurry by Ultrasonic
by Ruilin Yao, Dayang Xuan, Jialin Xu, Jian Li and Chengwei Ma
Appl. Sci. 2025, 15(19), 10425; https://doi.org/10.3390/app151910425 - 25 Sep 2025
Viewed by 302
Abstract
Overburden isolated grouting injection is an efficient and green mining technology. During the filling process, fly ash or gangue powder is mainly used as grouting material, and compaction grouting is carried out in the main stratum under the key stratum, thus realizing the [...] Read more.
Overburden isolated grouting injection is an efficient and green mining technology. During the filling process, fly ash or gangue powder is mainly used as grouting material, and compaction grouting is carried out in the main stratum under the key stratum, thus realizing the control of surface subsidence and the protection of buildings (structures). In the process of grouting filling, slurry with high water-cement ratio (1:1) is needed to ensure its injectability and certain flow radius, which leads to large water demand and limited application in water-deficient mining areas. In addition, special geological structures such as faults have potential risks of slurry flowing into the working face. On the premise of not affecting the grout injectability, how to reduce the total water consumption of grout is one of the difficult problems to be solved urgently in the overburden isolated grouting injection. The experimental study on the feasibility of ultrasonic water reduction of grouting slurry is carried out in this paper, and the influence of ultrasonic cavitation on the fluidity of slurry is studied through experiments. The results show that ultrasonic waves can effectively improve the fluidity of slurry. Under the same fluidity, the water used for slurry preparation is reduced by 20% to 26%, and when the slurry with water-cement ratio of 0.8:1 is modified, its fluidity is equivalent to that of the slurry with a water-cement ratio of 1:1 in conventional engineering applications. The action time and power of the ultrasonic waves are the key factors affecting the modification effect of the slurry, and the ultrasonic power has a more significant influence on the action effect. The proposed ultrasonic cavitation water reduction modification method can effectively reduce the water used for slurry preparation, improve the efficiency, reliability and economic benefits of grouting filling, and provide important support for the application of the grouting filling method in restricted mining areas such as water-deficient mining areas. Full article
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18 pages, 1809 KB  
Article
Utilization of Waste Marble Sludge in Self-Compacting Concrete: A Study on Partial Replacement of Cement and Fine Aggregates
by Hadi Bahmani, Hasan Mostafaei, Reza Mohamad Momeni and Sayyed Mehran Khoshoei
Sustainability 2025, 17(19), 8523; https://doi.org/10.3390/su17198523 - 23 Sep 2025
Viewed by 376
Abstract
This study presents a novel approach to the development of self-compacting concrete (SCC) by partially replacing both cement and fine aggregate (sand) with waste marble sludge (WMS), a byproduct of the marble industry. The research aims to evaluate the feasibility of incorporating this [...] Read more.
This study presents a novel approach to the development of self-compacting concrete (SCC) by partially replacing both cement and fine aggregate (sand) with waste marble sludge (WMS), a byproduct of the marble industry. The research aims to evaluate the feasibility of incorporating this industrial waste into SCC to enhance sustainability without compromising performance. To assess the fresh and hardened properties of the proposed mixtures, a comprehensive experimental program was conducted. Tests included slump flow, T50, and V-funnel for evaluating workability, as well as measurements of specific gravity, compressive strength, flexural strength, Brazilian tensile strength, and water absorption at 28 days of curing. The results demonstrated that the mix containing 5% cement replacement and 20% sand replacement with marble sludge exhibited the highest mechanical performance, achieving a compressive strength of 48.2 MPa, tensile strength of 3.9 MPa, and flexural strength of 4.4 MPa. Furthermore, increasing the percentage of cement replacement led to enhanced flowability, as evidenced by an increase in slump flow diameter and a reduction in V-funnel flow time, indicating improved workability. Overall, the findings suggest that controlled incorporation of WMS can produce SCC with desirable mechanical and rheological properties, offering a promising pathway for sustainable concrete production. In addition to the technical performance, a carbon footprint analysis was conducted to examine the environmental benefits of marble sludge utilization. The mixture with 10% cement and 20% sand replacement exhibited the lowest carbon footprint, while the 7.5% replacement level provided the best balance between strength and sustainability. Full article
(This article belongs to the Special Issue Carbon Capture, Utilization, and Storage (CCUS) for Clean Energy)
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28 pages, 2938 KB  
Article
Boiling and Condensing Two-Phase Frictional Pressure Drop Within Minichannel Tubes—Comparison and New Model Development Based on Experimental Measurements
by Calos Martínez-Lara, Alejandro López-Belchí and Francisco Vera-García
Energies 2025, 18(18), 5010; https://doi.org/10.3390/en18185010 - 20 Sep 2025
Viewed by 780
Abstract
This study presents a comprehensive experimental investigation into the frictional pressure drop of two-phase flows—boiling and condensation—in horizontal minichannels, emphasizing its impact on the energy efficiency of vapor compression systems. A total of 3553 data points were obtained using six low-GWP refrigerants (R32, [...] Read more.
This study presents a comprehensive experimental investigation into the frictional pressure drop of two-phase flows—boiling and condensation—in horizontal minichannels, emphasizing its impact on the energy efficiency of vapor compression systems. A total of 3553 data points were obtained using six low-GWP refrigerants (R32, R134a, R290, R410A, R513A, and R1234yf) across a wide range of operating conditions in multiport aluminum tubes with hydraulic diameters of 0.715 mm and 1.16 mm. The dataset covers mass fluxes from 200 to 1230 kgm2s1, saturation temperatures between 5 °C and 55 °C, and vapor qualities from 0.05 to 0.95. Results showed a strong dependence of frictional pressure gradient on vapor quality, mass flux, and channel size. Boiling flows generated higher frictional losses than condensation, and high-density refrigerants such as R32 exhibited the largest pressure penalties, which can directly translate into increased compressor power demand. Conversely, higher saturation temperatures were associated with lower frictional losses, highlighting the role of thermophysical properties in improving energy performance. Additionally, an inverse correlation between saturation temperature and frictional pressure gradient was observed, attributed to variations in thermophysical properties such as viscosity and surface tension. Existing correlations from the literature were assessed against the experimental dataset, with notable deviations observed in several cases, particularly for R134a under high-quality conditions. Consequently, a new empirical correlation was developed for predicting the frictional pressure drop in two-phase flow through minichannels. The proposed model, formulated using a power-law regression approach and incorporating dimensionless parameters, achieved better agreement with the experimental data, reducing prediction error to within ±20%, improving the accuracy for the majority of cases. This work provides a robust and validated dataset for the development and benchmarking of predictive models in compact heat exchanger design. By enabling the more precise estimation of two-phase pressure drops in compact heat exchangers, the findings support the design of refrigeration, air-conditioning, and heat pump systems with minimized flow resistance and reduced auxiliary energy consumption. This contributes to lowering compressor workload, improving coefficient of performance (COP), and it ultimately advances the development of next-generation cooling technologies with enhanced energy efficiency. Full article
(This article belongs to the Special Issue Advances in Numerical and Experimental Heat Transfer)
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