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Rheological Properties and Incipient Motion of Cohesive Sediment in the Haine Estuary of China

China Ocean Engineering 2002年第4期17卷 483-498页

作者：白玉川 ng Chiu-on 沈涣庭王尚毅 Institute for Sedimentation on River and Coast Engineering Tianjin UniversityTianjin300072China Department of Mechanical Engineering The University of Hong KongHong KongChina The State Key Laboratory of Estuarine and Coastal Research East China Normal UniversityShanghai 200062China

The Haihe cohesive sediment, which is typical in China, is studied systematically for its basic physical and incipient motion properties. Following the requirements of dredging works in the Haihe Estuary, cohesive sediment samples were taken from three locations. Laboratory experiments were conducted to determine the rheological properties of these samples and to examine the incipient motion of the cohesive sediment. It is found that the cohesive sediment has an obvious yield stress tau(b), which increases with the mud density in a manner of an exponential function, and so does the viscosity parameter eta. The cohesive sediment behaves like a Bingham fluid when its density is below 1.38 similar to 1.40 g/cm(3), and when denser than these values, it may become a power-law fluid. The incipient motion experiment also revealed that the incipient velocity of the cohesive sediment increases with die density in an exponential manner. Therefore, the incipient motion is primarily related to the density, which is different from the case for non-cohesive sediment in which the incipient motion is con-elated with the diameter of sand particles instead. The incipient motion occurs in two different ways depending on the concentration of mud in the bottom. For sufficiently fine particles and a concentration lower than 1.20 g/cm(3), the cohesive sediment appears as fluidized mud, and the incipient motion is in the form of instability of an internal wave. For a higher concentration, the cohesive sediment appears as general quasi-solid-mud, and the incipient motion can be described by a series of extended Shields curves each with a different porosity for newly deposited alluvial mud.

关键词： incipient motion rheological properties cohesive sediment estuary and coast

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Predicting wax deposition using robust machine learning techniques

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Petroleum 2022年第2期8卷 167-173页

作者： Menad Nait Amar Ashkan jahanbani Ghahfarokhi Cuthbert Shang Wui ng Departement Etudes Thermodynamiques Division LaboratoiresSonatrachAvenue 1er Novembre35000BoumerdesAlgeria Department of Geoscience and Petroleum Norwegian University of Science and TechnologyS.P.Andersens veg 15b7031TrondheimNorway

Accurate prediction of wax deposition is of vital interest in digitalized systems to avoid many issues that interrupt the flow assurance during production of hydrocarbon *** present investigation aims at establishing rigorous intelligent schemes for predicting wax deposition under extensive production *** do so,multilayer perceptron(MLP)optimized with Levenberg-Marquardt algorithm(MLPLMA)and Bayesian Regularization algorithm(MLP-BR)were taught using 88 experimental *** latter were described by some independent variables,namely temperature(in K),specific gravity,and compositions of C1eC3,C4eC7,C8eC15,C16eC22,C23eC29 and C30þ.The obtained results showed that MLP-LMA achieved the best performance with an overall root mean square error of 0.2198 and a coefficient of determination(R2)of *** performance comparison revealed that MLP-LMA outperforms the prior approaches in the literature.

关键词： Wax deposition Multilayer perceptron Levenberg-marquardt algorithm Flow assurance

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Developmental impacts and toxicological hallmarks of silver nanoparticles across diverse biological models

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Environmental Science and Ecotechnology 2024年第3期19卷 60-79页

作者： Yán Wāng Yapeng Han De-Xiang Xu Department of Toxicology School of Public Health&Key Laboratory of Environmental Toxicology of Anhui Higher Education InstitutesAnhui Medical UniversityHefei230032China

Silver nanoparticles(AgNPs),revered for their antimicrobial prowess,have become ubiquitous in a range of products,from biomedical equipment to food ***,amidst their rising popularity,concerns loom over their possible detrimental effects on fetal development and subsequent adult *** review delves into the developmental toxicity of AgNPs across diverse models,from aquatic species like zebrafish and catfish to mammalian rodents and in vitro embryonic stem *** focus encompasses the fate of AgNPs in different contexts,elucidating associated hazardous results such as embryotoxicity and adverse pregnancy ***,we scrutinize the enduring adverse impacts on offspring,spanning impaired neurobehavior function,reproductive disorders,cardiopulmonary lesions,and *** hallmarks of developmental harm are identified,encompassing redox imbalances,inflammatory cascades,DNA damage,and mitochondrial ***,we explore potential explanations,linking immunoregulatory dysfunction and disrupted epigenetic modifications to AgNPsinduced developmental *** substantial progress,our understanding of the developmental risks posed by AgNPs remains incomplete,underscoring the urgency of further research in this critical area.

关键词： Silver nanoparticles(AgNPs) Developmental toxicity Maternal exposure Fetal development Redox imbalance Mitochondrial dysfunction

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Formation of TiN Grid on NiTi by Laser Gas Nitriding for Improving Wear Resistance in Hanks' Solution

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journal of Materials Science & Technology 2016年第5期32卷 459-464页

作者： C.H.ng O.K.Chan H.C.Man Department of Industrial and Systems Engineering The Hong Kong Polytechnic University

Laser gas nitriding （LGN） is a common surface modification method to enhance the wear resistance of titanium （Ti） alloys, which are known to have poor tribological properties. In the present study, a titanium nitride （TIN） grid network was fabricated on the surface of nickel titanium （NiTi） by LGN. The laser processing parameters were selected to achieve nitriding without surface melting and hence to＇maintain a smooth surface finish. The characteristics of the grid-nitrided samples were investigated by scanningelectron microscopy, X-ray diffractometry, optical microscopy, 2-D profilometry, contact angle measurements and nanoindentation. The wear resistance of the nitrided samples was evaluated using reciprocating wear test against ultra-high-molecular-weight polyethylene （UHMWPE） in Hanks＇ solution. The results indicate that the wear rates of the grid-nitrided samples and the UHMWPE counter-body in the wear pair are both significantly reduced. The decrease in wear rates can be attributed to the combination of a hard TiN grid and a soft NiTi substrate. In Hanks＇ solution, the higher hydrophilicity of the nitrided samples also contributes to the better performance in wear test against hydrophobic UHMWPE.

关键词： Laser Nitriding Surface patterning Titanium alloys Wear

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Production optimization under waterflooding with long short-term memory and metaheuristic algorithm

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Petroleum 2023年第1期9卷 53-60页

作者： Cuthbert Shang Wui ng Ashkan jahanbani Ghahfarokhi Menad Nait Amar Department of Geoscience and Petroleum Norwegian University of Science and TechnologyTrondheimNorway Département Etudes Thermodynamiques Division LaboratoiresSonatrachBoumerdesAlgeria

In petroleum domain,optimizing hydrocarbon production is essential because it does not only ensure the economic prospects of the petroleum companies,but also fulfills the increasing global demand of ***,applying numerical reservoir simulation(NRS)to optimize production can induce high computational *** models are suggested to alleviate this challenge because they are computationally less demanding and able to yield reasonably accurate *** this paper,we demonstrated how a machine learning technique,namely long short-term memory(LSTM),was applied to develop proxies of a 3D reservoir *** techniques were employed to create numerous simulation cases which served as the training database to establish the *** blind validating the trained proxies,we coupled these proxies with particle swarm optimization to conduct production *** training and blind validation results illustrated that the proxies had been excellently developed with coefficient of determination,R2 of *** also compared the optimization results produced by NRS and the *** comparison recorded a good level of accuracy that was within 3%*** proxies were also computationally 3 times faster than ***,the proxies have served their practical purposes in this study.

关键词： Production optimization Numerical reservoir simulation Machine learning Long short-term memory(LSTM) Dynamic proxies Particle swarm optimization(PSO)

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Co-substitution of zirconium and neodymium on hyperfine interactions and AC susceptibility of SrFe12O19 nanohexaferrites

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journal of Rare Earths 2020年第3期38卷 265-273页

作者： M.A.Almessere Y.Slimani H.Güngünes A.Baykal Department of Physics College of ScienceImam Abdulrahman Bin Faisal UniversityP.O.Box 198231441DammamSaudi Arabia Department of Biophysics Institute for Research&Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityP.O.Box 198231441DammamSaudi Arabia Department of Physics Hitit University19030Cevre Yolu Bulvan-CorumTurkey Department of Nano-Medicine Research Institute for Research&Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityP.O.Box 198231441DammamSaudi Arabia

This study presents the influence of Zn and Nd co-substitution on structure,morphology,AC susceptibility and ZFC-FC magnetizations of Sr nanohexaferrites(NHFs),SrFe12-x(Zn,Nd)xO19(0.0≤x≤1.0),which was produced by sol-gel *** powder patterns,scanning electron microscopy(SEM) and high-resolution transmission electron spectroscopy(HR-TEM) approve the synthesis of Sr M-type *** spectra show that Zn^2+ions occupy 2 b and 4f1 sites while Nd3+ions locate at 2 a,4f2 and 12 k *** magnetic properties of the produced Sr-NHFs were investigated also by ZFC-FC magnetizations and AC *** to the MFC-MZFC results(between 2 and 400 K),no blocking temperature was detected which indicates the ferromagnetic(FM) behavior of *** lower temperatures,a super-spin glass like behavior is *** AC susceptibility indicates that the magnetic interactions are improved due to the inclusion of low content(x=0.1) of Nd^3+and Zn^2+ions into the ***,with further increasing the Nd^3+and Zn^2+contents(x=0.9),the magnetic interactions are weakened.

关键词： Sr hexaferrites Rare earths Mossbauer spectroscopy AC susceptibility ZFC-FC

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Insights on the solubilization products after combined alkaline and ultrasonic pre-treatment of sewage sludge

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journal of Environmental Sciences 2015年第3期27卷 97-105页

作者： Xinbo Tian Chong Wang Antoine Prandota Trzcinski Leonard Lin Wun jern ng Advanced Environmental Biotechnology Centre Nanyang Environment and Water Research Institute Nanyang Technological University School of Civil and Environmental Engineering Nanyang Technological University Public Utilities Board Water Reclamation (Plants) Department Nanyang Environment and Water Research Institute Nanyang Technological University

This work provides insights on the solubilization products after a simultaneous combination of alkaline and ultrasonic （ALK ＋ ULS） pre-treatment of sewage sludge. Soluble chemical oxygen demand （SCOD） increased from 1200 to 11,000 mg/L after such treatment. Organics with molecular weight around 5.6 kDa were solubilized because of the synergistic effect of ultrasound and alkali. Organics with molecular weight larger than 300 kDa increased from 7.8% to 60%, 16% and 42.3% after ULS, ALK and ALK ＋ ULS treatment, respectively. Excitation emission matrix fluorescence spectroscopy analysis identified soluble microbial product-like and humic acid-like matters as the main solubilization products. Sludge anaerobic biodegradability was significantly enhanced with the simultaneous application of ALK ＋ ULS pre-treatment. ALK ＋ ULS pre-treatment resulted in 37.8% biodegradability increase compared to the untreated sludge. This value was higher compared to the biodegradability increase induced by individual ALK pre-treatment （5.7%） or individual ULS pre-treatment （20.7%） under the same conditions applied.

关键词： Ultrasound AlkaliSewage sludge Molecular weight Excitation emission matrix (EEM) Anaerobic biodegradability

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Adoption of technologies that enhance soil carbon sequestration in East Africa. What influence farmers' decision?

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International Soil and Water Conservation Research 2020年第1期8卷 90-101页

作者： Stanley Karanja ng'ang'a Dorcas Anyango jalang'o Evan Hartunian Girvetz International Centre for Tropical Agriculture(CIAT) National Agricultural Research Laboratories-KawandaP.O.Box 6247KampalaUganda International Centre for Tropical Agriculture(CIAT) P.O.Box 823-00621NairobiKenya

The last two decades have seen a rise of interest in the adoption and diffusion of agricultural technologies aimed at improving the sustainability of agricultural lands among smallholder farmers in developing *** papers set out to understand factors that influence the adoption of technologies that enhance soil carbon sequestration among smallholder farmers,using secondary data recorded in the World Overview of Conservation Approaches and Technologies(WOCAT)database from 45 to 50 smallholders'farmers in selected places in Kenya and Ethiopia respectively.A Probit model was used to analyse whether socio-economic,institutional,off-farm income,technical know-how,farmers'percep-tions,and land use characteristics influences the adoption of technologies that enhance soil carbon *** results show that smallholder farmers that positively perceived net benefits of the soil carbon enhancing technologies were more likely to adopt such technologies that enhance soil carbon sequestration in both *** to off-farm income and land ownership with title deeds were also found to be positively associated with ***-farm income positively influences adoption among farmer with a moderate income(100-500US$per year)but not the rich(>500US$)*** to high level of skills and technical know-how required for implementing and maintaining a technology on the farm had a negative influence on *** shows that interventions,aimed at addressing specific factors such as inadequate skills and knowledge,change in perception among farmers,and off-farm income are likely to have the greatest impact in decisions relating to the adoption of the soil carbon enhancing practices among farmers in East Africa.

关键词： Factors Influencing The adoption Soil carbon Sequestration East Africa

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Experimental and numerical investigation of Weibullian behavior of grain crushing strength

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Geoscience Frontiers 2020年第2期11卷 401-411页

作者： Quanshui Huang Wei Zhou Gang Ma Tang-Tat ng Kun Xu State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering Wuhan UniversityMinistry of EducationWuhan 430072China University of New Mexico AlbuquerqueNM87131USA

The Weibullian behavior of single grain crushing strength was investigated experimentally and numerically with the aim of enhancing the understanding of rock grain *** morphologies of pebble grains were obtained using white light 3D laser scanning and image processing.A grain shape library was constructed for grain shape analysis with different shape *** use of the shape library and grain stability analysis is discussed for a suggested procedure to rotate a grain to its most stable *** grain crushing tests were performed for 30 pebbles to obtain force-displacement curves and fracture *** grain was compressed diametrically between flat *** expected,the values of the stress at bulk fracture follow a Weibull distribution.A procedure for generating crushable agglomerates with realistic particle shapes was demonstrated,which was accomplished in the discrete element modeling(DEM)of the single grain crushing *** work presented here is novel in that both the heterogeneous micro-structures and randomly distributed flaws are *** DEM results demonstrate that the proposed modeling approach and calibrated parameters are reliable and can reflect the crushing behavior of rock ***,three parametric studies were presented evaluating the effects of micro-crack density,micro-crack disorder,and grain morphology on the Weibullian behavior of the crushing strength,none of which has previously been thoroughly *** three studies provide a deeper insight into the origin of the Weibullian behavior of single grain crushing strength.

关键词： Rock grain Grain crushing test Discrete element modeling 3D scanning technique Grain stability Weibullian behavior

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A review on 2D MoS_(2) cocatalysts in photocatalytic H_(2) production

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journal of Materials Science & Technology 2020年第21期56卷 89-121页

作者： Zizhan Liang Rongchen Shen Yun Hau ng Peng Zhang Quanjun Xiang Xin Li Key Laboratory of Energy Plants Resource and Utilization Ministry of Agriculture and Rural AffairsCollege of Forestry and Landscape ArchitectureSouth China Agricultural UniversityGuangzhou510642China School of Energy and Environment City University of Hong KongHong KongChina State Center for International Cooperation on Designer Low-Carbon&Environmental Materials(CDLCEM) School of Materials Science and EngineeringZhengzhou UniversityZhengzhou450001China State Key Laboratory of Electronic Thin Film and Integrated Devices University of Electronic Science and Technology of ChinaChengdu610054China

Owing to their unique physicochemical,optical and electrical properties,two-dimensional(2D)MoS_(2) cocatalysts have been widely applied in designing and developing highly efficient composite photocatalysts for hydrogen generation under suitable light *** this review,we first elaborated on the fundamental aspects of 2D MoS_(2) cocatalysts to include the structural design principles,synthesis strategies,strengths and ***,we thoroughly highlighted and discussed the modification strategies of 2D MoS_(2) H2-evolution cocatalysts,including doping heteroatoms(***,non-metals,and co-doping),designing interfacial coupling morphologies,controlling the physical properties(***,size,structural defects or pores),exposing the reactive facets or edge sites,constructing cocatalyst heterojunctions,engineering the interfacial bonds and confinement *** the future,the forefront challenges in understanding and in precise controlling of the active sites at molecular level or atomic level should be carefully studied,while various potential mechanisms of photogenerated-electrons interactions should be *** applications of MoS_(2) cocatalyst in the overall water splitting are also *** review may offer new inspiration for designing and constructing novel and efficient MoS_(2)-based composite photocatalysts for highly efficient photocatalytic hydrogen evolution.

关键词： 2D MoS2 cocatalysts Photocatalytic H2 production Heteroatom doping Cocatalyst heterojunctions Charge dynamics

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