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Multi-layer perceptron-based data-driven multiscale modelling of granular materials with a novel Frobenius norm-based internal variable

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Journal of Rock.Mechanics and Geotechnical Engineering 2024年第6期16卷 2198-2218页

作者： Mengqi Wang y.T.Feng Shaoheng Guan Tongming Qu Zienk.ewicz Centre for Computational Engineering Faculty of Science and EngineeringSwansea UniversitySwanseaWalesSA18EPUK Institute of Theoretical and Computational Physics Graz University of TechnologyGraz8010Austria Department of Civil and Environmental Engineering Hong Kong University of Science and TechnologyClearwater BayKowloonHong KongChina

One objective of developing machine learning(ML)-based material models is to integrate them with well-established numerical methods to solve boundary value problems(BVPs).In the family of ML models,recurrent neural network.(RNNs)have been extensively applied to capture history-dependent constitutive responses of granular materials,but these multiple-step-based neural network. are neither sufficiently efficient nor aligned with the standard finite element method(FEM).Single-step-based neural network. lik. the multi-layer perceptron(MLP)are an alternative to bypass the above issues but have to introduce some internal variables to encode complex loading *** this work.one novel Frobenius norm-based internal variable,together with the Fourier layer and residual architectureenhanced MLP model,is crafted to replicate the history-dependent constitutive features of representative volume element(RVE)for granular *** obtained ML models are then seamlessly embedded into the FEM to solve the BVP of a biaxial compression case and a rigid strip footing *** obtained solutions are comparable to results from the FEM-DEM multiscale modelling but achieve significantly improved *** results demonstrate the applicability of the proposed internal variable in enabling MLP to capture highly nonlinear constitutive responses of granular materials.

关键词： Granular materials History-dependence Multi-layer perceptron(MLP) Discrete element method FEM-DEM Machine learning

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Multi-population particle swarm optimization algorithm for automatic design of steel frames

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Frontiers of Structural and Civil Engineering 2024年第1期18卷 89-103页

作者： Wenchen SHAN Jiepeng LIU yao DING y.Frank.CHEN Junwen ZHOU Institute of Smart City and Intelligent Transportation Southwest Jiaotong UniversityChengdu 610000China School of Civil Engineering Chongqing UniversityChongqing 400045China Department of Civil Engineering the Pennsylvania State UniversityMiddletownPA 17057USA

Steel structures are widely used;however,their traditional design method is a trial-and-error procedure which is neither efficient nor cost ***,a multi-population particle swarm optimization(MPPSO)algorithm is developed to optimize the weight of steel frames according to standard design *** are made to improve the algorithm performances including the constraint-based strategy,piecewise mean learning strategy and multi-population cooperative *** proposed method is tested against the representative frame tak.n from American standards and against other steel frames matching Chinese design *** related parameter influences on optimization results are *** the representative frame,MPPSO can achieve greater efficiency through reduction of the number of analyses by more than 65% and can obtain frame with the weight for at least 2.4%lighter.A similar trend can also be observed in cases subjected to Chinese design *** addition,a migration interval of 1 and the number of populations as 5 are recommended to obtain better MPPSO *** purpose of the study is to propose a method with high efficiency and robustness that is not confined to structural scales and design *** aims to provide a reference for automatic structural optimization design problems even with dimensional *** proposed method can be easily generalized to the optimization problem of other structural systems.

关键词： steel frame multi-population particle swarm optimization automatic structural optimization design

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Direct scaling of residual displacements for bilinear and pinching oscillators

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Earthquak. Engineering and Engineering Vibration 2024年第1期23卷 129-149页

作者： Mohammad Saifullah Vinay k.Gupta Department of Civil Engineering Indian Institute of Technology KanpurKanpur 208016India

The estimation of residual displacements in a structure due to an anticipated earthquak. event has increasingly become an important component of performance-based earthquak. engineering because controlling these displacements plays an important role in ensuring cost-feasible or cost-effective repairs in a damaged structure after the *** attempt is made in this study to obtain statistical estimates of constant-ductility residual displacement spectra for bilinear and pinching oscillators with 5%initial damping,directly in terms of easily available seismological,site,and model *** of the available models for the bilinear and pinching oscillators are useful when design spectra for a seismic hazard at a site are not *** statistical estimates of a residual displacement spectrum are proposed in terms of earthquak. magnitude,epicentral distance,site geology parameter,and three model parameters for a given set of ductility demand and a hysteretic energy capacity coefficient in the case of bilinear and pinching models,as well as for a given set of pinching parameters for displacement and strength at the break.oint in the case of pinching model *** proposed scaling model is applicable to horizontal ground motions in the western *** earthquak. magnitudes less than 7 or epicentral distances greater than 20 k..

关键词： residual displacement spectrum bilinear hysteresis model pinching hysteresis model nonlinear analysis scaling model

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Analysis of the Oscillatory Flows of Multiple Shock.Waves in a Constant Area Duct

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Journal of Thermal Science 2024年第3期33卷 794-806页

作者： k.JAMES Jintu k.M Heuy Dong Department of Mechanical Engineering Andong National UniversityAndong36729Republic of Korea CAD-IT k.rea Co. Ltd.Seoul08591Republic of Korea

The oscillatory response of multiple shock.waves to downstream perturbations in a supersonic flow is studied numerically in a rectangular *** shock.waves are formed inside the duct at a shock.Mach number of *** duct has an exit height of H,and the effect of duct resonance on multiple shock.oscillations is investigated by attaching exit ducts of lengths 0H,50H,and *** downstream disturbance frequency varied from 10 Hz to 200 Hz to explore the oscillation characteristics of the multiple shock.*** oscillatory response of shock.waves under self-excited and forced oscillation conditions are analyzed in terms of wall static pressure,shock.train leading-edge location,shock.train length,and the size of the separation *** extent of the initial shock.location increases with an increase in exit duct length for the self-excited oscillation *** analysis of the shock.train leading edge and the spectral analysis of wall static pressure variations are *** variation in the shock.train length is analyzed using the pressure ratio method for self-excited as well as forced *** RMS amplitude of the normalized shock.train length(ζ_(ST))increases with an increase in the exit duct length for the self-excited oscillation *** the downstream perturbation frequency is increased,ζ_(ST)is decreased for exit duct *** all exit duct designs and downstream forcing frequencies,the size of the separation bubble grows and shrink. during the shock.oscillations,demonstrating the dependence on duct resonance and forced oscillations.

关键词： shock.train downstream disturbance supersonic flow shock.wave boundary layer interaction duct resonance flow separation

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Impact of Fin Arrangement on Heat Transfer and Melting Characteristics of Phase Change Material

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Journal of Thermal Science 2024年第2期33卷 435-456页

作者： Arun UNIyAL yogesh k.PRAJAPATI Department of Mechanical Engineering National Institute of Technology UttarakhandSrinagar(Garhwal)246174India Department of Mechanical Engineering BIT SindriDhanbadJharkhand828123India

Present work.investigates the heat transfer and melting behaviour of phase change material(PCM) in six enclosures(enclosure-1 to 6) filled with paraffin *** enclosures are equipped with distinct arrangements of the fins while k.eping the fin's surface area equal in each *** analysis has been presented to recognize the suitable fin arrangements that facilitate improved heat transfer and melting rate of the *** wall of the enclosure is maintained isothermal for the temperature values 335 k.350 k.and 365 *** length of the enclosure including fins is ranging between 0 and *** have been illustrated through the estimation of important performance parameters such as energy absorbing capacity,melting rate,enhancement ratio,and Nusselt *** has been found that melting time(to melt 100% of the PCM) is 60.5%less in enclosure-2(with two fins of equal length) as compared to the enclosure-1,having no *** the fin surface area equal,if the longer fin is placed below the shorter fin(enclosure-3),melting time is further decreased by 14.1% as compared to ***,among all the configurations,enclosure-6 with wire-mesh fin structure exhibits minimum melting time which is 68.4% less as compared to the *** on the findings,it may be concluded that fins are the main driving agent in the enclosure to transfer the heat from heated wall to the *** design and positioning of the fins improve the heat transfer rate followed by melting of the PCM in the entire area of the *** of the favourable vortices and natural convection current in the enclosure accelerate the melting phenomenon and help to reduce charging time.

关键词： phase change material enclosure fin melting fraction energy storage heat transfer

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Isolation of Microcrystalline Cellulose from Wood and Fabrication of Polylactic Acid (PLA) Based Green Biocomposites

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Journal of Renewable Materials 2024年第8期12卷 1455-1474页

作者： Sek.r S.M. Nagarajan R. Selvak.mar P. Oluwarotimi I.S. k.ishnan k. Mohammad F. Shaik.M.R. Ayrilmis N. Department of Mechanical Engineering Kalasalingam Academy of Research and Education Krishnankoil 626126 India Department of Mechanical Engineering SSM Institute of Engineering and Technology Dindigul 624002 India Department of Engineering Centre for Engineering Research School of Physics Engineering and Computer Science University of Hertfordshire Hatfield AL10 9AB United Kingdom INTI International University Persiaran Perdana BBN Nilai 71800 Malaysia Department of Chemistry College of Science King Saud University P.O. Box 2455 Riyadh 11451 Saudi Arabia Department of Wood Mechanics and Technology Faculty of Forestry Istanbul University–Cerrahpasa Bahcekoy Sariyer Istanbul 34473 Turkey

An innovative microcrystalline cellulose (MCC) natural fibre powder-reinforced PLA biocomposite was investigated using the hand lay-up technique. The polymer matrix composite (PMC) samples were prepared by varying the weight percentages (wt.%) of both PLA matrix and MCC reinforcement: pure PLA/100:0, 90:10, 80:20, 70:30, 60:40 and 50:50 wt.%, respectively. From the results obtained, MCC powder, with its impressive aspect ratio, proved to be an ideal reinforcement for the PLA, exhibiting exceptional mechanical properties. It was evident that the 80:20 wt.% biocomposite sample exhibited the maximum improvement in the tensile, flexural, notched impact, compressive strength and hardness by 28.85%, 20.00%, 91.66%, 21.53% and 35.82%, respectively compared to the pure PLA sample. Similarly, during the thermogravimetric analysis (TGA), the same 80:20 wt.% biocomposite sample showed a minimum weight loss of 20% at 400°C, among others. The morphological study using Field Emission Scanning Electron Microscopy (FE-SEM) revealed that the uniform distribution of cellulose reinforcement in the PLA matrix actively improved the mechanical properties of the biocomposites, especially the optimal 80:20 wt.% sample. Importantly, it was evident that the optimal PLA/cellulose biocomposite sample could be a suitable and alternative sustainable, environmentally friendly and biodegradable material for semi/structural applications, replacing synthetic and traditional components. © 2024 The Authors.

关键词： biocomposite characterizations environmental pollution FESEM micro crystalline cellulose Polylactic acid

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Radiative heat transfer analysis of a concave porous fin under the local thermal non-equilibrium condition:application of the clique polynomial method and physics-informed neural network.

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Applied Mathematics and Mechanics(English Edition) 2024年第9期45卷 1613-1632页

作者： k.CHANDAN k.k.RTHIk.k.V.NAGARAJA B.C.PRASANNAk.MARA R.S.VARUN k.MAR T.MUHAMMAD Amrita School of Artificial Intelligence Amrita Vishwa VidyapeethamBengaluru 560035KarnatakaIndia Department of Studies in Mathematics Davangere UniversityDavangere 577002KarnatakaIndia Computational Science Lab Amrita School of EngineeringAmrita Vishwa VidyapeethamBengaluru 560035KarnatakaIndia Department of Pure and Applied Mathematics School of Mathematical SciencesSunway UniversityPetaling Jaya 47500Malaysia Department of Mathematics College of ScienceKing Khalid UniversityAbha 61413Saudi Arabia

The heat transfer through a concave permeable fin is analyzed by the local thermal non-equilibrium(LTNE)*** governing dimensional temperature equations for the solid and fluid phases of the porous extended surface are modeled,and then are nondimensionalized by suitable dimensionless ***,the obtained nondimensional equations are solved by the clique polynomial method(CPM).The effects of several dimensionless parameters on the fin's thermal profiles are shown by graphical ***,the current study implements deep neural structures to solve physics-governed coupled equations,and the best-suited hyperparameters are attained by comparison with various network.*** results of the CPM and physicsinformed neural network.PINN)exhibit good agreement,signifying that both methods effectively solve the thermal modeling problem.

关键词： heat transfer fin porous fin local thermal non-equilibrium(LTNE)model physics-informed neural network.PINN)

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The Impact of Privatization on Terminal Efficiency: A Case Study of Tema Port

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Journal of Transportation Technologies 2024年第3期14卷 358-371页

作者： Bernard k.ei Tetteh Calvin Elorm Atsunyo alex Boateng College of Transport and Communications Shanghai Maritime University Shanghai China Department of Transport Regional Maritime University Accra Ghana

Port and terminal efficiency are of utmost importance to the container shipping industry due to their significance in enhancing the competitive advantage of ports within a region. Consequently, there have always been notable variations of studies around it. This paper analyzes the impact of privatization on terminal efficiency using the Port of Tema as a Case Study. The main objective of this paper is to analyze the efficiency trends of the public and private terminals in the port over the years. To achieve this objective, DEA-CCR methodology was employed to calculate the annual technical efficiency trends of the private and public terminals using four input variables and three output variables. The main results of the paper indicated that the public and private terminals were efficient for multiple years. However, the efficiency scores over the years demonstrated inconsistency, exhibiting notable fluctuations. The findings of this study will aid policymak.rs across the region on policies relating to the efficiency and ownership structure of ports and terminals.

关键词： Privatization Terminal Efficiency DEA Tema Port

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Nitrate reduction capacity of the oral microbiota is impaired in periodontitis:potential implications for systemic nitric oxide availability

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International Journal of Oral Science 2024年第1期16卷 52-61页

作者： Bob T.Rosier William Johnston Miguel Carda-Diéguez Annabel Simpson Elena Cabello-yeves k.ystyna Piela Robert Reilly Alejandro Artacho Chris Easton Mia Burleigh Shauna Culshaw alex Mira Department of Genomics and Health FISABIO FoundationCenter for Advanced Research in Public HealthValenciaSpain Department of Biological and Biomedical Sciences Glasgow Caledonian UniversityGlasgowUK Oral Sciences University of Glasgow Dental SchoolSchool of MedicineDentistry and NursingCollege of MedicalVeterinary and Life SciencesUniversity of GlasgowGlasgowUK Sport and Physical Activity Research Institute University of the West of ScotlandBlantyreScotland Instituto de Biomedicina de Valencia Consejo Superior de Investigaciones Científicas(IBV-CSIC)ValenciaSpain CIBER Center for Epidemiology and Public Health MadridSpain

The reduction of nitrate to nitrite by the oral microbiota has been proposed to be important for oral health and results in nitric oxide formation that can improve cardiometabolic conditions. Studies of bacterial composition in subgingival plaque suggest that nitrate-reducing bacteria are associated with periodontal health, but the impact of periodontitis on nitrate-reducing capacity(NRC)and, therefore, nitric oxide availability has not been evaluated. The current study aimed to evaluate how periodontitis affects the NRC of the oral microbiota. First, 16S rRNA sequencing data from five different countries were analyzed, revealing that nitratereducing bacteria were significantly lower in subgingival plaque of periodontitis patients compared with healthy individuals(P y, subgingival plaque, saliva, and plasma samples were obtained from 42 periodontitis patients before and after periodontal treatment. The oral NRC was determined in vitro by incubating saliva with 8 mmol/L nitrate(a concentration found in saliva after nitrate-rich vegetable intak.) and compared with the NRC of 15healthy individuals. Salivary NRC was found to be diminished in periodontal patients before treatment(P y levels 90 days post-treatment. Additionally, the subgingival levels of nitrate-reducing bacteria increased after treatment and correlated negatively with periodontitis-associated bacteria(P y only be revealed after nitrate intak.. Our results suggest that an impaired NRC in periodontitis could limit dietary nitrate-derived nitric oxide levels, and the effect on systemic health should be explored in future studies.

关键词： impaired intak. nitrate

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First-principles calculations to investigate structural,electronic,magnetic,optical and thermodynamic properties of RE_(2)Rh_(3)Ge(RE=Pr,Sm)

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Journal of Rare Earths 2024年第7期42卷 1385-1393,I0007页

作者： A.Ezaier R.Masrour M.Hamedoun J.k.arbach A.Rezzouk.A.Hourmatallah N.Benzak.ur k.Bouslyk.ane Laboratory of Solid Physics Faculty of Sciences Dhar El MehrazSidi Mohamed Ben Abdellah UniversityBP 1796FezMorocco Equipe de Physique du Solide LaboratoiresLIPIEcole Normale SupérieureBensoudaFèsMorocco

In this paper,we analyzed the physical characteristics of the ternary alloys RE_(2)Rh_(3)Ge(RE=Pr and Sm)using the first principles calculation based on functional density theory integrated in the Wien2k.*** calculated formation energies of Pr_(2)Rh_(3)Ge and Sm_(2)Rh_(3)Ge are−5.3827 and−5.2782 eV/atom,respectively,showing that these alloys may exist *** results of the band structure and density of states indicate that all of the compounds tested are magnetic metals,and their magnetism is mostly related to the contribution of Pr and Sm *** total magnetic moments of Pr_(2)Rh_(3)Ge and Sm_(2)Rh_(3)Ge are 4.07245 and 11.16161μB/f.u,*** parameters such as heat capacity at constant pressure,entropy,Debye temperature,lattice volume,compressibility coefficients,and Grüneisen parameter alloys were calculated using the Gibbs algorithm and studied in depth over a large temperature range of 0-900 *** Debye temperature increases with increasing pressure and decreases with decreasing ***,the Debye temperatures calculated at p=0 GPa and T=300 k.are equal to be 342 and 322 k.for Pr_(2)Rh_(3)Ge and Sm_(2)Rh_(3)Ge,*** optical characteristics such as the real and imaginary portions of the dielectric function,the absorption coefficient,the energy-loss function,and the refractive index were investigated and discussed in more depth.

关键词： Magnetic metals Functional density theory Density of states Magnetic moment Optical and thermodynamic properties Rare earths

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