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Applied Mathematics and Mechanics(English Edition) 2024年第3期45卷 563-580页

作者： n.HUMnEKAR D.SRInIVASACHARYA Department of Mathematics National Institute of TechnologyWarangal 506004TelanganaIndia

The influence of variable viscosity and double diffusion on the convective stability of a nanofluid flow in an inclined porous channel is *** Darcybrinkman model is used to characterize the fluid flow dynamics in porous *** analytical solutions are obtained for the unidirectional and completely developed *** on a normal mode analysis,the generalized eigenvalue problem under a perturbed state is *** eigenvalue problem is then solved by the spectral ***,the critical Rayleigh number with the corresponding wavenumber is evaluated at the assigned values of the other flow-governing *** results show that increasing the Darcy number,the Lewis number,the Dufour parameter,or the Soret parameter increases the stability of the system,whereas increasing the inclination angle of the channel destabilizes the ***,the flow is the most unstable when the channel is vertically oriented.

关键词： nanofluid inclined channel variable viscosity linear stability double dif-fusion porous medium

Dynamic and electrical responses of a curved sandwich beam with glass reinforced laminate layers and a pliable core in the presence of a piezoelectric layer under low-velocity impact

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Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 155-178页

作者： n.SHAHVEISI S.FELI Department of Mechanical Engineering Razi UniversityKermanshah ***Iran

The dynamic responses and generated voltage in a curved sandwich beam with glass reinforced laminate(GRL)layers and a pliable core in the presence of a piezoelectric layer under low-velocity impact(LVI)are *** current study aims to carry out a dynamic analysis on the sandwich beam when the impactor hits the top face sheet with an initial *** the layer analysis,the high-order shear deformation theory(HSDT)and Frostig's second model for the displacement fields of the core layer are *** classical non-adhesive elastic contact theory and Hunter's principle are used to calculate the dynamic responses in terms of *** order to validate the analytical method,the outcomes of the current investigation are compared with those gained by the experimental tests carried out by other researchers for a rectangular composite plate subject to the *** element(FE)simulations are conducted by means of the AbAQUS *** effects of the parameters such as foam modulus,layer material,fiber angle,impactor mass,and its velocity on the generated voltage are reviewed.

关键词： analytical model piezoelectric layer curved sandwich beam glass reinforced laminate(GRL) pliable core low-velocity impact(LVI) classical non-adhesive elastic contact theory

Influence of biomass burning on ozone levels in the Megalopolis of Central Mexico during the COVID-19 lockdown

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Journal of Environmental Sciences 2024年第9期143卷 99-115页

作者： Victor Almanza Luis Gerardo Ruiz-Suárez Ricardo Torres-Jardón Agustín García-Reynoso Iván Y.Hernández-Paniagua Institute for Atmospheric Sciences and Climate Change National Autonomous University of MexicoCoyoacan 04510Mexico CityMexico

The massive reductions in anthropogenic emissions resulting from the COVID-19 lockdown provided a unique opportunity to evaluate the effect of mitigation measures aiming to abate air *** Mexico,the total lockdown period took place during the dry-hot season when biomass burning activity is ***,we investigate the role of biomass burning emissions on regional ozone levels in the Megalopolis of Central *** studied period covers the lockdown phases 2 and 3,and the first month of the new *** applied a factor separation technique and process analysis to estimate the pure and synergistic contributions of emission reductions under lockdown and that from biomass burning to daily ozone maximum concentrations in 7 metropolitan areas of different states in the *** results revealed that biomass burning plumes likely masked the effect of massive reductions from mobile emissions,impacted the PbL development during phase 3 and favored transition and mixed nO_(x)-limited and VOC-limited regional *** contributed to increased ozone production in the middle to lower PbL by changing the regional background levels which potentially could bias high ozone production efficiency *** the Megalopolis contribution to economic and societal development at national scale,our study suggests that ozone mitigation measures during the dry-hot season targeting mainly mobile emissions will likely be offset by biomass burning plumes.A regional and synergic policy aiming to control biomass burning would help to reduce the occurrence of high ozone levels in Central Mexico with the co-benefit of tackling short-lived climate pollutants.

关键词： COVID-19 Mexico Megalopolis Ozone Factor Separation Process Analysis

Magnetic,dielectric and electrical modulus of Ce^(3+) doped cobalt-magnesium ferrite nanoparticles

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Journal of Rare Earths 2024年第2期42卷 373-382,I0005页

作者： n.M.basfer Hanaa Almaghamsi Department of Physics Umm AL-Qura UniversityMakkahSaudi Arabia Physics Department College of Science and ArtKing Abdulaziz UniversityPOB344Rabigh291Saudi Arabi

In this work,the magnetic,dielectric properties and electric modulus of Ce^(3+) substituted cobaltmagnesium(Co_(0.7)Mg_(0.3)Ce_(x)Fe_(2-x)O_4)(labeled as CMCF) ferrite nanoparticles were investigated in *** magnetization decreases from 50.05 to 34.87 emu/g for further substituting Ce^(3+) ***,coercivity increases from 738.22 Gs for the CMCFO sample to 912.10 Gs for the CMCF2 sample,then decreases monotonically to 762.1 Gs for the CMCF5 *** cerium content and particle size play important roles in controlling the magnetization and coercivity of the CMCF *** CMCF nanoferrites are suitable for microwave applications since their high-frequency response ranges from 7.72 to 11.07 *** CMCF nanoferrites' dielectric parameter dispersion exhibits normal *** pristine Co-Mg nanoferrite only has ε' value of 28.25,but the nanoferrite MCMF2 has ε' value of365.03,with an enhancing ratio of 1192%.The conduction mechanism of the MCMF nanoferrites was determined by fitting the σ_(ac) results via the Jonscher power *** 653 K,large polaron tunnelling is thought to be responsible for this conduction process,which is followed by electron barrier hopping at higher ***-Cole diagrams at different temperatures,assuring the contributions of the grains and their boundaries at lower temperatures(653 K) and only the grains at higher *** on our results,the CMCF nanoferrites hold magnetic and semiconducting nature,which can be used in magnetic devices and dielectrics in lower-frequencies or conductors in higher-frequencies.

关键词： nanoferrites Rare earth ions Magnetic properties Dielectric parameters Impedance spectroscopy

Structural Stability of the Financial Market Model: Continuity of Superhedging Price and Model Approximation

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Journal of the Operations Research Society of China 2024年第1期12卷 215-241页

作者： Sergey n.Smirnov Faculty of Computational Mathematics and Cybernetics Lomonosov Moscow State UniversityMoscow119991Russian Federation

The present paper continues the topic of our recent paper in the same journal,aiming to show the role of structural stability in financial *** the context of financial market modeling,structural stability means that a specific“no-arbitrage”property is unaffected by small(with respect to the Pompeiu–Hausdorff metric)perturbations of the model’s *** formulate,based on our economic interpretation,a new requirement concerning“no arbitrage”properties,which we call the“uncertainty principle”.This principle in the case of no-trading constraints is equivalent to structural *** demonstrate that structural stability is essential for a correct model approximation(which is used in our numerical method for superhedging price computation).We also show that structural stability is important for the continuity of superhedging prices and discuss the sufficient conditions for this continuity.

关键词： Uncertainty Structural stability no arbitrage Continuity of superhedging price Compact-valued multifunction Financial market model approximation Trading constraints

brain Tumor Retrieval in MRI Images with Integration of Optimal Features

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Journal of Harbin Institute of Technology(new series) 2024年

作者： n V Shamna b Aziz Musthafa Department of Computer Science and Engineering P A College of Engineering Department of Computer Science and Engineering bearys Institute of Technology

This paper presents an approach to improve medical image retrieval， particularly for brain tumors， by addressing the gap between low-level visual and high-level perceived contents in MRI， X-ray， and CT scans. Traditional methods based on color， shape， or texture are less effective. The proposed solution uses machine learning to handle high-dimensional image features， reducing computational complexity and mitigating issues caused by artifacts or noise. It employs a genetic algorithm for feature reduction and a hybrid residual Unet (HResUnet) model for region-of-interest (ROI) segmentation and classification， with enhanced image preprocessing. The study examines various loss functions， finding that a hybrid loss function yields superior results， and the GA-HResUnet model outperforms the HResUnet. Comparative analysis with state-of-the-art models shows a 4% improvement in retrieval accuracy.

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A note on Transition Kernels for the Most UnfavourableMixed Strategies of the Market

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Journal of the Operations Research Society of China 2024年第1期12卷 35-50页

作者： Sergey n.Smirnov Faculty of Computational Mathematics and Cybernetics Lomonosov Moscow State UniversityMoscowRussian Federation 119991

We consider a deterministic model of market evolution with trading constraints andapply a game-theoretic approach to the superhedging *** obtain sufﬁcientconditions for the game equilibrium and prove under these conditions the existenceof a borel-measurable transition kernel describing dependence on price prehistory ofthe most unfavourable mixed strategy of the market.

关键词： Superhedging Guaranteed deterministic approach Optimal mixedstrategies of the market borel-measurable transition kernel Game equilibrium

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Current Zoology 2024年第1期70卷 1-12页

作者： Lucia V.Sommaro Juan J.Martinez Marina b.Chiappero Andrea R.Steinmann Cristina n.Gardenal JoséW.Priotto Laboratorio de Ecologia Evolutiva y biogeografia Instituto de Ecorregiones Andinas(INECoA)Universidad Nacional de Jujuy-Consejo Nacional de Investigaciones Cientificas y Tecnicas(CONICET)San Salvador de JujuyJujuyArgentina Instituto de Diversidad y Ecologia Animal(IDEA) Consejo Nacional de Investigaciones Cientificas y Técnicas(CONICET)and Universidad Nacionalde CordobaCordobaArgentina Catedra de Genética de Poblaciones y Evolucion Facultad de Ciencias ExactasFisicas y NaturalesUniversidad Nacional de CordobaCordobaArgentina Grupo de Investigaciones en Ecologia Poblacional y Comportamental(GIEPCO) Instituto de Ciencias de la TierraBiodiversidad y Ambiente(ICBiA)Universidad Nacional de Rio Cuarto-Consejo Nacional de Investigaciones Cientificas y Técnicas(CONICET)Rio CuartoCordobaArgentina

The sex-biased dispersal and kinship dynamics are important factors shaping the spatial distribution of individuals and are key parameters affecting a variety of ecological and evolutionary ***,we studied the spatial distribution of related individuals within a population of corn mice Calomys musculinus in a seasonal cycle to infer dispersal *** sampling was carried out from spring 2005 to winter 2006 in field borders of intensively managed *** data from 346 individuals with 9 microsatellites showed spatial genetic structure was weak for males,but not for *** results indicate a complex spatial kinship dynamic of related females across all ***,contrary to our expectations,dispersal distances decrease with the increase of the population ***,male dispersal distances were greater when population abundance increased and thus the availability of active *** disperse greater distances to mate and sire offspring with distant females as a possible inbreeding avoidance *** study shows that *** is capable of much greater scattering distances than previously reported and that dispersal occurs fluidly and without barriers across the *** indirect benefit of dispersal on individual fitness could be related to relaxing the competition in the natal area and increasing the mating *** study highlights the value of combining genetic relatedness,fieldwork observations,and behavioral data to estimate dispersal at a fine geographical scale.

关键词： dispersal distances kinship dynamics microsatellite small mammals spatial autocorrelation

Inclusion of CoTiO_(3) to ameliorate the re/dehydrogenation properties of the Mg–na–Al system

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Journal of Magnesium and Alloys 2024年第3期12卷 1215-1226页

作者： n.A.Ali n.Y.Yusnizam n.A.Sazelee Sami-ullah Rather Haizhen Liu M.Ismail Energy Storage Research Group Faculty of Ocean Engineering TechnologyUniversiti Malaysia Terengganu21030 Kuala NerusTerengganuMalaysia Department of Chemical and Materials Engineering King Abdulaziz UniversityP.O.Box80204Jeddah 21589Saudi Arabia Guangxi novel battery Materials Research Center of Engineering Technology School of Physical Science and TechnologyGuangxi UniversityNanning 530004China State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures Nanning 530004China

For the first time,the MgH_(2)–naAlH_(4)(ratio 4:1)destabilized system with CoTiO_(3) addition has been *** CoTiO_(3)-doped MgH_(2)–naAlH_(4) sample begins to dehydrogenate at 130℃,which is declined by 40℃ compared to the undoped MgH_(2)–naAlH_(4).Moreover,the de/rehydrogenation kinetics characteristics of the CoTiO_(3)-doped MgH_(2)–naAlH_(4) were greatly *** the inclusion of CoTiO_(3),the MgH_(2)–naAlH_(4) composite absorbed 5.2 wt.%H_(2),higher than undoped MgH_(2)–naAlH_(4).In the context of dehydrogenation,the CoTiO_(3)-doped MgH_(2)–naAlH_(4) sample desorbed 2.6 wt.%H_(2),almost doubled compared to the amount of hydrogen desorbed from the undoped MgH_(2)–naAlH_(4) *** activation energy obtained by the Kissinger analysis for MgH_(2) decomposition was significantly lower by 35.9 kJ/mol than the undoped MgH_(2)–naAlH_(4) *** reaction mechanism demonstrated that new phases of MgCo and AlTi_(3) were generated in situ during the heating process and are likely to play a substantial catalytic function and be useful in ameliorating the de/rehydrogenation properties of the destabilized MgH_(2)–naAlH_(4) system with the inclusion of CoTiO_(3).

关键词： Destabilize system Magnesium hydride Sodium alanate Hydrogen storage Additive.

EP Aquarii:A new Picture of the Circumstellar Envelope

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Research in Astronomy and Astrophysics 2024年第3期24卷 83-105页

作者： Pham T.nhung Do T.Hoai Pierre Darriulat Pham Tuan-Anh Pham n.Diep nguyen b.ngoc Tran T.Thai Department of Astrophysics Vietnam National Space CenterVietnam Academy of Science and Technology18Hoang Quoc VietNghia DoCau GiayHa Noivietnam

new analyses of earlier ALMA observations of oxygen-rich AGb star EP Aquarii are presented,which complete a previously published analysis and offer a different interpretation of the morpho-kinematics of the circumstellar *** birth of the equatorial density enhancement(EDE)is shown to occur very close to the star where evidence for rotation has been *** to the star and where outflows have been observed:their interaction with the gas of the nascent EDE is seen to play an important role in the development of the wind and the evolution of its radial velocity from 8 to 10 km s^(-1) on the polar symmetry axis to~2 km s^(-1) at the *** implies complex morpho-kinematics:making reliable interpretations with reasonable confidence is *** particular,it questions an earlier interpretation implying the presence of a white dwarf companion orbiting the star at an angular distance of -0″4 from its *** proposes instead an interpretation in terms of a standard mass ejection associated with a shock wave leaving a void of emission in its *** Doppler velocity wings are seen to consist of two components,the upper velocity end of the global wind,reaching above±12 km s^(-1),and an effective line broadening,confined within 200 mas from the center of the star,reaching above±20 km s^(-1) and interpreted as caused by the pattern of shock waves resulting from the interaction between stellar pulsation and convective cell partition.

关键词： stars AGb and post-AGb-(stars) circumstellar matter-radio lines stars