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22nd Australasian Fluid Mechanics Conference, AFMC 2020

作者： Jagad, P. Samtaney, R. Mechanical Engineering Physical Science and Engineering Division King Abdullah University of Science and Technology Jeddah Saudi Arabia

ISBN: (纸本)9781742723419

The giant vortex in Jupiter's atmosphere, the great red spot (GRS), has grabbed attention of not only astrophysicists but also of fluid dynamists. What fluid dynamics/thermodynamics conditions might have formed it and made it extremely stable and long-lived are some fundamental questions of interest, and the present work addresses these. We model the GRS numerically using a structure-preserving Discrete Exterior Calculus (DEC) method. Our initial condition comprises of vortices embedded in a shearing zonal flow. We solve the continuity and momentum equation (that conserves the potential vorticity) on a sphere (thereby including sphericity and excluding domain boundary influence), for incompressible, inviscid flow with uniform fluid properties. We investigate the vorticity dynamics of vortices in shearing zonal flows for a range of parameters. Our simulations show evolution of a stable vortex in a zonal band similar to the GRS. © 2020 22nd Australasian Fluid Mechanics Conference, AFMC 2020. All rights reserved.

关键词： Vortex flow

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One-Dimensional Convolutional Neural Network for Automated Kimchi Cabbage Downy Mildew Detection Using Aerial Hyperspectral Images

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Remote Sensing 2025年第9期17卷 1626-1626页

作者： Lyu, Yang Kuswidiyanto, Lukas Wiku Wang, Pingan Noh, Hyun-Ho Jung, Hee-Young Han, Xiongzhe Interdisciplinary Program in Smart Agriculture College of Agricultural and Life Sciences Kangwon National University Chuncheon24341 Korea Republic of Department of Mechanical and Electrical Engineering Shandong Water Conservancy Vocational College Rizhao276826 China Residual Agrochemical Assessment Division Department of Agro-Food Safety and Crop Protection National Institute of Agricultural Science Rural Development Administration Jeonju55365 Korea Republic of Department of Plant Pathology College of Agricultural and Life Science Kyungpook National University Daegu41566 Korea Republic of Department of Biosystems Engineering College of Agricultural and Life Sciences Kangwon National University Chuncheon24341 Korea Republic of

Downy mildew poses a significant threat to kimchi cabbage, a vital agricultural product in Korea, adversely affecting its yield and quality. Traditional disease detection methods based on visual inspection are labor intensive and time consuming. This study proposes a non-destructive, field-scale disease detection approach using unmanned aerial vehicle (UAV)-based hyperspectral imaging. Hyperspectral images of the kimchi cabbage field were preprocessed, segmented at the pixel level, and classified into four categories: background, healthy, early-stage disease, and late-stage disease. Spectral analysis of the late and early stages of downy mildew infection revealed notable differences in the red-edge band, with infected plants exhibiting increased red-edge reflectance. To automate disease detection, various machine learning models, including Random Forest (RF), 1D Convolutional Neural Network (1D-CNN), 1D Residual Network (1D-ResNet), and 1D Inception Network (1D-InceptionNet), were developed. These models were trained based on a 0.2 sampling dataset, achieving overall accuracy scores of 0.907, 0.901, 0.909, and 0.914, along with F1 scores of 0.876, 0.845, 0.897, and 0.899, respectively. Overall, the results of this study revealed that the red-edge band reliably signaled the presence of downy mildew, and the 1D-InceptionNet model demonstrated the most effective performance for automatic disease detection. © 2025 by the authors.

关键词： Drones

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Modification of low nickel biograde stainless steel with graphene oxide for enhanced corrosion resistance and in vivo biocompatibility

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Scientific Reports 2025年第1期15卷 1-16页

作者： Muslim, Doaa A. Abu Shahat, Amal S. El Basaty, A.B. Hassen, A. Elfadl, A. Abou Ali, Ahmed I. Tayel, A. Physics Department Faculty of Science Fayoum University El Fayoum 63514 Egypt Basic Science Department Faculty of Technology and Education Helwan University Saraya-El Koba El Sawah Street Cairo 11281 Egypt General Division of Main Medical Science Egyptian Drug Authority (EDA) Formally National Organization for Drug Control and Research (NODCAR) Cairo 12611 Egypt Nanotechnoloy Centre Helwan University Helwan Al Sharqia Cairo 11722 Egypt Department of Mechanical Engineering (Integrated Engineering Program) Kyung Hee University 1732 Deogyeong-Daero Gyeonggi Yongin 17104 South Korea

This study investigates the integration of graphene oxide (GO) into low nickel bio-grade stainless steel (LNBGSS) to enhance its corrosion resistance and assess its biocompatibility. Three concentrations of GO (0.5, 1.0, and 1.5 wt%) were added to the steel matrix using the powder metallurgy method and annealed in a nitrogen environment. X-ray diffraction and field-emission scanning electron microscopy analyses reveal that while the crystal structure of the steel remains largely unchanged, the morphology of the prepared samples exhibits minimal alteration post-GO integration. The average particle sizes (D_av) of the studied samples were calculated. It was found that D_av slightly changed with the content of GO. Based on the electrochemical analysis, the inhibition efficiency was determined in different ways and it increased markedly with increasing GO content in LNBGSS composites. Subsequently, biocompatibility assessment was conducted through in vivo studies on albino rats. Thirty-six rats were randomly allocated into six groups. The hematological parameters revealed a nonsignificant (P > 0.05) difference except for the rats treated with the low-nickel bio-grade stainless steel powder (LNBGSS) (S0), which had the lowest complete blood count in comparison with other groups. In spite, the hematological parameters of all groups were within the normal reference ranges. The biochemical indices also were not significantly (P > 0.05) different by assessment of liver enzymes and kidney functions for all examined groups. These findings suggested that the use of GO in modifying low nickel bio-grade stainless steel alloy is biologically safe and recommendable for enhancing this alloy’s properties. © The Author(s) 2025.

关键词： Albino rats Biocompatibility Biological indices Corrosion resistance Graphene oxide (GO) Hematological parameters Low nickel bio-grade stainless steel

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Optimizing electrochemical removal of perfluorooctanoic acid in landfill leachate using ceramic carbon foam electrodes by coupling CFD simulation and reactor design

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Chemosphere 2025年 376卷 144282页

作者： Pierpaoli, Mattia Jakóbczyk, Pawel Szopińska, Malgorzata Ryl, Jacek Giosué, Chiara Wróbel, Maciej Strugala, Gabriel Luczkiewicz, Aneta Fudala-Książek, Sylwia Bogdanowicz, Robert Faculty of Electronics Telecommunications and Informatics Department of Metrology and Optoelectronics Gdańsk University of Technology 11/12 Gabriela Narutowicza Street Gdańsk80-233 Poland Faculty of Civil and Environmental Engineering Department of Environmental Engineering Technology Gdańsk University of Technology 11/12 Gabriela Narutowicza Street Gdańsk80-233 Poland Faculty of Applied Physics and Mathematics Division of Electrochemistry and Surface Physical Chemistry Gdańsk University of Technology 11/12 Gabriela Narutowicza Street Gdańsk80-233 Poland Università Politecnica Delle Marche Via Brecce Bianche 12 Ancona60131 Italy Faculty of Mechanical Engineering and Ship Technology Department of Materials Science and Technology Gdańsk University of Technology 11/12 Gabriela Narutowicza Street Gdańsk80-233 Poland Faculty of Civil and Environmental Engineering Department of Sanitary Engineering Gdańsk University of Technology 11/12 Gabriela Narutowicza Street Gdańsk80-233 Poland

Perfluorooctanoic acid (PFOA), a persistent and bioaccumulative pollutant classified as a 'forever chemical', poses a global environmental and health risk due to its widespread use and resistance to degradation. The development of effective and efficient removal technologies is crucial to mitigate its long-term impacts. In this study, we present a novel approach to address the growing concern of emerging contaminants, particularly PFOA, in landfill leachate. We investigate the use of ceramic carbon foam electrodes (CCFE) as a cost-effective and efficient alternative to traditional electrode materials for the electrochemical degradation of PFOA. Computed microtomography was used to reconstruct the actual three-dimensional geometries of the samples from which porosities were calculated. We also coupled computational fluid dynamics simulations of the actual geometries and optimized the working conditions to minimize pressure drop and improve treatment efficiency. Our design significantly reduces energy requirements by operating at lower potentials, a critical factor in sustainable waste management practices. The optimized CCFE system demonstrated superior performance in the degradation of PFOA in landfill leachate, offering a promising solution for the treatment of emerging contaminants. This study not only provides a viable method for mitigating the environmental impact of PFOA but also sets a precedent for the development of low-energy, high-efficiency treatment technologies for various persistent pollutants. In addition, the proposed solution, as part of closed-loop water systems, will enhance water reuse and recycling, thereby preserving and regenerating natural water bodies. © 2025 Elsevier Ltd

关键词： Leachate treatment

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Pre-treatment optimization to reduce membrane fouling during produced water treatment with an integrated FO-MD system

Science Talks

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science Talks 2025年 14卷

作者： Muhammad Saqib Nawaz Sofiane Soukane Muhammad Bilal Asif Veerabhadraiah Gudideni Sultan Alrubaish Noreddine Ghaffour Environmental Sciences and Engineering Program Division of Biological and Environmental Sciences and Engineering (BESE) King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia Physical Sciences and Engineering Division (PSE) King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia Energy Systems Division Process & Control Systems Department Saudi Aramco Dhahran Saudi Arabia

During oil exploration, fresh water that is injected into underground reservoirs returns to the surface loaded with hydrocarbons, salts, and other contaminants. This complex solution is typically known as produced water (PW). Generally, different PW streams are generated at a given site, which, after suitable treatment, are sent for re-injection for enhanced oil recovery or to disposal wells. However, there is a potential for water recovery from this hypersaline contaminated stream. Forward osmosis (FO) and membrane distillation (MD) are two low-pressure membrane treatment technologies successfully used in a single hybrid system for PW treatment. During operation, the key foulants on the FO membrane were CaSiO 3 , CaSO 4 , and NaCl, while for MD, they were SiO 2 and CaSO 4 plus emulsified oil, causing pore clogging. Some foulants were tightly bound and not removed by osmotic backwashing or hydraulic flushing, thus requiring pre-treatment. Different pre-treatment techniques, like ion exchange resins and polymeric and ceramic membrane-based ultrafiltration (UF), were assessed in this study. The resins were able to remove bivalent metallic ions successfully from lower concentration streams only and thus caused an increase in FO flux and a reduction in MD flux by disturbing the FO-MD system equilibrium. The higher concentrations of resins and chemicals required for their regeneration make them unsuitable for such applications. On the contrary, PW pre-treated with polymeric and ceramic UF membranes led to increased FO and MD fluxes without any chemical requirement and proved suitable for pre-treatment.

关键词： Pre-treatment Produced water Ion-exchange resins Ultrafiltration Forward osmosis Membrane distillation

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Mitigating offshore oily wastewater pollution: Sustainable strategies for treatment, disposal, and reuse

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Marine Pollution Bulletin 2025年 219卷

作者： Rajab Abousnina Noreddine Ghaffour Long D. Nghiem School of Civil and Mechanical Engineering Curtin University Perth 6102 Australia King Abdullah University of Science and Technology (KAUST) Environmental Science & Engineering Program Biological and Environmental Science & Engineering Division (BESE) Thuwal 23955-6900 Saudi Arabia Centre for Technology in Water and Wastewater University of Technology Sydney Ultimo NSW 2007 Australia

Oily wastewater, a major byproduct of petroleum oil and gas production, poses serious environmental risks if not effectively treated. This review analyses the composition of oily wastewater, assesses current treatment methods, and explores strategies to improve efficiency while reducing capital and operational costs. Data corroborated from this work suggests that integrated treatment systems are more effective than single-method approach. Membrane-based technologies such as reverse osmosis (RO), forward osmosis (FO), and membrane distillation (MD) show promise in improving pollutant removal and energy efficiency. However, persistent challenges such as membrane fouling, high capital and operational costs, and membrane stability necessitate further innovation in materials development and hybrid system design. This review highlights the potential of well-designed hybrid systems for offshore oily wastewater treatment. Such systems can significantly enhance contaminant removal while minimising energy consumption and operational costs. Overcoming technical challenges and advancing membrane technologies will be essential for more sustainable and cost-effective oily wastewater treatment.

关键词： Petroleum oil and gas Oily wastewater Hybrid system technologies Offshore Membrane technologies

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Integrated analytical workflow for quantifying and modeling the hydrocracking of vacuum gas oil and plastic pyrolysis oil

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Fuel 2025年 400卷

作者： Naydu Zambrano Suní Rodríguez Gontzal Lezcano David Trueba Idoia Hita Roberto Palos Alazne Gutiérrez Pedro Castaño Multiscale Reaction Engineering KAUST Catalysis Center (KCC) King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia Department of Chemical Engineering University of the Basque Country UPV/EHU PO Box 644 48080 Bilbao Spain Chemical Engineering Program Physical Science and Engineering (PSE) Division King Abdullah University of Science and Technology Saudi Arabia

The pressing need for more sustainably produced fuels has highlighted the co-feeding of plastics with conventional feedstocks as a promising alternative. However, challenges such as effective feeding, in-depth product characterization, or process optimization require thorough analysis to establish the feasibility of the overall process. This study demonstrates the validity of a workflow for the quantitative and kinetic analysis of the hydrocracking reaction of vacuum gas oil and plastic pyrolysis oil blends using a NiW on HY-zeolite catalyst in a semi-batch reactor. The reaction products are characterized using a combination of gas chromatography with various detectors, Fourier transform ion cyclotron resonance mass spectrometry, and simulated distillation. The workflow refines and integrates data from these techniques into comprehensive quantitative datasets applied to continuous lumping kinetic modeling. Hydrocracking of the blend converts 83 % of heavy cycle oil at 440 °C, yielding substantial amounts of naphtha and middle distillates. The continuous lumping kinetic model accurately predicts product distribution while providing key insights into the reactivity of heavy fractions and S and N removal.

关键词： Gas chromatography

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Mechanistic and kinetic effects of Ga on a Cu catalyst for CO 2 hydrogenation to methanol

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Journal of CO2 Utilization 2025年 96卷

作者： Yerrayya Attada Gontzal Lezcano Vijay K. Velisoju David Trueba Shekhar R. Kulkarni Ali Almofleh Hassan Aljama Pedro Castano Multiscale Reaction Engineering KAUST Catalysis Center (KCC) King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia Research and Development Center Saudi Aramco Dhahran 31311 Saudi Arabia Chemical Engineering Program Physical Science and Engineering (PSE) Division KAUST Thuwal Saudi Arabia

This work investigates the mechanistic and kinetic effects of gallium (Ga) promotion on copper (Cu) catalysts for carbon dioxide hydrogenation using the density functional theory (DFT), in situ infrared spectroscopy, and mean-field microkinetic simulations. The DFT calculations reveal potential reaction pathways for methanol synthesis, emphasizing the role of formate (HCOO) and carboxyl (COOH) intermediates on Cu (111) and Ga–Cu (111) surfaces. The in situ infrared spectroscopic analysis identifies surface intermediates, validating DFT-predicted mechanistic trends and confirming the preferential COOH pathway on unpromoted Cu catalysts and the HCOO pathway on Ga–Cu catalysts. Microkinetic simulations demonstrate how Ga promotion alters reaction kinetics, favoring the HCOO pathway via H₂COO ** formation and explaining the enhanced methoxy intermediate generation on Ga–Cu, which is critical for dimethyl ether production. The temperature effects demonstrate a kinetic shift toward the COOH pathway on Cu catalysts, contrasting with the stability of the HCOO pathway on Ga–Cu. This integrative study demonstrates the significance of Ga in modulating surface chemistry and reaction mechanisms, offering a foundation for designing efficient methanol synthesis catalysts.

关键词： Carbon dioxide (CO 2 ) hydrogenation Methanol Density functional theory (DFT) Microkinetics Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS)

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Multifrequency excitation of a clamped–clamped microbeam:Analytical and experimental investigation

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Microsystems & Nanoengineering 2016年第1期2卷 278-283页

作者： Nizar Jaber Abdallah Ramini Mohammad I.Younis Physical Science and Engineering Division King Abdullah University of Science and TechnologyThuwal 23955-6900Saudi Arabia Department of Mechanical Engineering State University of New York at BinghamtonBinghamtonNY 13902USA

Using partial electrodes and a multifrequency electrical source,we present a large-bandwidth,large-amplitude clamped–clamped microbeam resonator excited near the higher order modes of *** analytically and experimentally investigate the nonlinear dynamics of the microbeam under a two-source harmonic *** first-frequency source is swept around the first three modes of vibration,whereas the second source frequency remains *** additive and subtractive resonances are *** illustrated that by properly tuning the frequency and amplitude of the excitation force,the frequency bandwidth of the resonator is *** microbeam is fabricated using polyimide as a structural layer coated with nickel from the top and chromium and gold layers from the *** the Galerkin method,a reduced order model is derived to simulate the static and dynamic response of the device.A good agreement between the theoretical and experimental data are reported.

关键词： multifrequency nonlinear dynamics wideband resonator electrostatic combination resonances

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Sensitivity study of resolution and convergence requirements for the extended overlap region in wall-bounded turbulence

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physical Review Fluids 2024年第8期9卷 L082601-L082601页

作者： Sergio Hoyas Ricardo Vinuesa Peter Schmid Hassan Nagib Instituto Universitario de Matemática Pura y Aplicada Universitat Politècnica de València FLOW Engineering Mechanics KTH Royal Institute of Technology Department of Mechanical Engineering Division of Physical Sciences and Engineering (PSE) King Abdullah University of Science and Technology (KAUST) Mechanical Materials and Aerospace Engineering Armour College of Engineering ILLINOIS TECH

Direct numerical simulations (DNSs) are among the most powerful tools for studying turbulent flows. Even though the achievable Reynolds numbers are lower than those obtained through experimental means, DNS offers a clear advantage: The entire velocity field is known, allowing for the evaluation of any desired quantity. This capability includes the computation of derivatives of all relevant terms. One such derivative provides the indicator function, which is the product of the wall distance and the wall-normal derivative of the mean streamwise velocity. This derivative may depend on mesh spacing and distribution, but it is extremely affected by the convergence of the simulation. The indicator function is crucial for understanding inner and outer interactions in wall-bounded flows and describing the overlap region between them. We find a clear dependence of this indicator function on the mesh distributions we examine, raising questions about classical mesh and convergence requirements for DNS and achievable accuracy. Within the framework of the logarithmic plus linear overlap region, coupled with a parametric study of channel flows and some pipe flows, sensitivities of extracted overlap parameters are examined. This study reveals a path to establishing their high-Reτ or nearly asymptotic values at modest Reynolds numbers, but larger than the ones used in this work, accessible by high-quality DNS with reasonable cost.

关键词： Boundary layers Complex fluids Three-dimensional turbulence Turbulence Turbulent boundary layers

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