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transient responses of double-curved sandwich two-layer shells resting on Kerr's foundations with laminated three-phase polymer/GNp/fiber surface and auxetic honeycomb core subjected to the blast load

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Defence Technology（防务技术） 2024年第5期35卷 222-247页

作者： Nguyen thi Hai Van thi Hong Nguyen researcher&Lecturer Faculty of Industrial EducationThe University of Danang-University of Technology and Education48 Cao ThangDanang550000Viet Nam researcher&Lecturer Faculty of Mechanical EngineeringThuyloi University175 Tay SonDong DaHanoi100000Viet Nam

this work uses refined first-order shear theory to analyze the free vibration and transient responses of double-curved sandwich two-layer shells made of auxetic honeycomb core and laminated three-phase polymer/GNp/fiber surface subjected to the blast *** of the two layers that make up the double-curved shell structure is made up of an auxetic honeycomb core and two laminated sheets of three-phase polymer/GNp/*** exterior is supported by a Kerr elastic foundation with three *** key innovation of the proposed theory is that the transverse shear stresses are zero at two free surfaces of each *** contrast to previous first-order shear deformation theories,no shear correction factor is ***'s exact solution was used to treat the double-curved shell problem with a single title boundary,while the finite element technique and an eight-node quadrilateral were used to address the other boundary *** ensure the accuracy of these results,a thorough comparison technique is employed in conjunction with credible *** problem model's edge cases allow for this kind of *** study's findings may be used in the post-construction evaluation of military and civil works structures for their ability to sustain explosive *** addition,this is also an important basis for the calculation and design of shell structures made of smart materials when subjected to shock waves or explosive loads.

关键词： Blast load Two-layer shell polymer/GNp/Fiber surface Auxetic honeycomb Shear connectors

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transient response of doubly-curved bio-inspired composite shells resting on viscoelastic foundation subject to blast load using improved first-order shear theory and isogeometric approach

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Defence Technology（防务技术） 2024年第8期38卷 171-193页

作者： Thuy tran thi Thu Tu Nguyen Anh Hue Nguyen thi Hong Nguyen thi School of Mechanical and Automotive Engineering Hanoi University of IndustryHanoiViet Nam Faculty of Technical Fundamental University of Transport TechnologyHanoiViet Nam Faculty of Mechanical Engineering Thuyloi University175 Tay SonDong DaHanoiViet Nam

Investigating natural-inspired applications is a perennially appealing subject for scientists. The current increase in the speed of natural-origin structure growth may be linked to their superior mechanical properties and environmental resilience. Biological composite structures with helicoidal schemes and designs have remarkable capacities to absorb impact energy and withstand damage. However, there is a dearth of extensive study on the influence of fiber redirection and reorientation inside the matrix of a helicoid structure on its mechanical performance and reactivity. The present study aimed to explore the static and transient responses of a bio-inspired helicoid laminated composite(B-iHLC) shell under the influence of an explosive load using an isomorphic method. The structural integrity of the shell is maintained by a viscoelastic basis known as the pasternak foundation, which encompasses two coefficients of stiffness and one coefficient of damping. The equilibrium equations governing shell dynamics are obtained by using Hamilton's principle and including the modified first-order shear theory,therefore obviating the need to employ a shear correction factor. The paper's model and approach are validated by doing numerical comparisons with respected publications. The findings of this study may be used in the construction of military and civilian infrastructure in situations when the structure is subjected to severe stresses that might potentially result in catastrophic collapse. The findings of this paper serve as the foundation for several other issues, including geometric optimization and the dynamic response of similar mechanical structures.

关键词： Blast load Modified first-order shear theory Biological composite structures

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Application of extreme gradient boosting in predicting the viscoelastic characteristics of graphene oxide modified asphalt at medium and high temperatures

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Frontiers of Structural and Civil Engineering 2024年第6期18卷 899-917页

作者： Huong-Giang thi HOANG Hai-Van thi MAI Hoang Long NGUYEN Hai-Bang LY University of transport Technology Hanoi 100000Vietnam

Complex modulus(G^(*))is one of the important criteria for asphalt classification according to AASHTO M320-10,and is often used to predict the linear viscoelastic behavior of asphalt *** addition,phase angle(φ)characterizes the deformation resilience of asphalt and is used to assess the ratio between the viscous and elastic *** is thus important to quickly and accurately estimate these two *** purpose of this investigation is to construct an extreme gradient boosting(XGB)model to predict G^(*)andφof graphene oxide(GO)modified asphaltat medium and high *** data sets are gathered from previously published experiments,consisting of 357 samples for G^(*)and 339 samples forφ,and the se are used to develop the XGB model using nine inputs representing theasphalt binder *** findings show that XGB is an excellent predictor of G^(*)andφof GO-modified asphalt,evaluated by the coefficient of determination r^(2)(r^(2)=0.990 and 0.9903 for G^(*)andφ,respectively)and root mean square error(rMSE=31.499 and 1.08 for G^(*)andφ,respectively).In addition,the model’s performance is compared with experimental results and five other machine learning(ML)models to highlight its *** the final step,the Shapley additive explanations(SHAp)value analysis is conducted to assess the impact of each input and the correlation between pairs of important features on asphalt’s two physical properties.

关键词： complex modulus phase angle graphene oxide asphalt extreme gradient boosting machine learning

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Towards a New Model of Teacher training in Europe

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Journalism and Mass Communication 2024年第4期14卷 260-266页

作者： Teodor pătrăuță “Vasile Goldiș”Western University of Arad AradRoumania

The current situation of European educational systems leads to the lack of historical precedents,considering that it implies the end of educational systems based on exclusion,configuring a new conception of educational systems that we are still not able to appreciate at their true value,because we were educated by and in the previous educational *** other references,we inevitably tend to compare current problems with previous situations,without understanding that the generalization of education to 100%of the population implies a qualitative change that modifies the objectives,forms of work,and the very essence of the educational *** stage change,marked by the acceleration of social changes,including the pandemic situation,explains why,despite the best educational system so far,teachers with the best levels of training and a financial and material endowment unimaginable until recently,try a sense of crisis and a general feeling of confusion is manifested among the teachers and parents of the children,seeing that education is no longer what it used to be(Esteve,1998).The key to defuse this apparent paradox is in the tendency to judge the new education system by the mentality and standards of the former selective education,in which most of the adults present were ***,although we continue to apply to the new general education situation the parameters of the previous situation,in which the selective system excluded every year the students who had behavior problems in the class or had difficulties regarding the mastery of certain educational subjects(Esteve,1998).In this way,we are currently criticizing the school failure of a percentage of our students,without realizing that their schooling itself is a success,because,although their level is low,they had no level *** speaks of a low educational level,when,in reality,the educational level is increasing—the general level of the people and the individual level of the best students(Baudelo

关键词： education model teacher education exclusion selection schooling

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Severe acute respiratory syndrome-coronavirus-2(SArS-COV-2)infection of pneumocytes with vaccination and drug therapy:Mathematical analysis and optimal control

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International Journal of Biomathematics 2024年第2期17卷 299-334页

作者： r.Viriyapong p.Inkhao Department of Mathematics Faculty of Science Naresuan University Phitsanulok65000Thailand

We propose a mathematical model studying a within-host infection dynamics of SArSCoV-2 in *** model incorporates immune response,vaccination and antiviral *** crucial properties of the model-the existence,positivity and boundary of solutions are *** points and the basic reproduction number are *** stability of each equilibrium point is *** control is applied to the model by adding three control variables:vaccination,treatment by Favipiravir and treatment by *** results show that each individual control could reduce SArS-CoV-2 infection in some aspects;however,with a combination of three controls,we obtain the best results in reducing SArS-CoV-2 *** study has emphasized the importance of prevention by vaccine and the antiviral treatments.

关键词： SArS-CoV-2 vaccination drug therapy immune response optimal control

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Enhanced entropy generation and heat transfer characteristics of magnetic nano-encapsulated phase change materials in latent heat thermal energy storage systems

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Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 1051-1070页

作者： p.S.rEDDY p.SrEEDEVI Department of Mathematics Rajeev Gandhi Memorial College of Engineering and TechnologyNandyal 518501India

The objective of the current study is to investigate the importance of entropy generation and thermal radiation on the patterns of velocity,isentropic lines,and temperature contours within a thermal energy storage device filled with magnetic nanoencapsulated phase change materials(NEpCMs).The versatile finite element method(FEM)is implemented to numerically solve the governing *** effects of various parameters,including the viscosity parameter,ranging from 1 to 3,the thermal conductivity parameter,ranging from 1 to 3,the rayleigh parameter,ranging from 102 to 3×10^(2),the radiation number,ranging from 0.1 to 0.5,the fusion temperature,ranging from 1.0 to 1.2,the volume fraction of NEpCMs,ranging from 2%to 6%,the Stefan number,ranging from 1 to 5,the magnetic number,ranging from 0.1 to 0.5,and the irreversibility parameter,ranging from 0.1 to 0.5,are examined in detail on the temperature contours,isentropic lines,heat capacity ratio,and velocity ***,the heat transfer rates at both the cold and hot walls are analyzed,and the findings are presented *** results indicate that the time taken by the NEpCMs to transition from solid to liquid is prolonged inside the chamber region as the fusion temperatureθf ***,the contours of the heat capacity ratio Cr decrease with the increase in the Stefan number Ste.

关键词： volume fraction of nano-encapsulated phase change material(NEpCM) radiation Stefan number heat capacity ratio entropy generation

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A Hybrid Optimization Approach of Single point Incremental Sheet Forming of AISI 316L Stainless Steel Using Grey relation Analysis Coupled with principal Component Analysiss

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Journal of Wuhan University of Technology(Materials Science) 2024年第1期39卷 160-166页

作者： A Visagan p Ganesh Department of production Technology Madras Institute of TechnologyChennai-600044India

We investigated the parametric optimization on incremental sheet forming of stainless steel using Grey relational Analysis(GrA) coupled with principal Component Analysis(pCA). AISI 316L stainless steel sheets were used to develop double wall angle pyramid with aid of tungsten carbide tool. GrA coupled with pCA was used to plan the experiment conditions. Control factors such as Tool Diameter(TD), Step Depth(SD), Bottom Wall Angle(BWA), Feed rate(Fr) and Spindle Speed(SS) on Top Wall Angle(TWA) and Top Wall Angle Surface roughness(TWASr) have been studied. Wall angle increases with increasing tool diameter due to large contact area between tool and workpiece. As the step depth, feed rate and spindle speed increase,TWASr decreases with increasing tool diameter. As the step depth increasing, the hydrostatic stress is raised causing severe cracks in the deformed surface. Hence it was concluded that the proposed hybrid method was suitable for optimizing the factors and response.

关键词： single point incremental forming AISI 316L taguchi grey relation analysis principal component analysis surface roughness scanning electron microscopy

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Some Mean Convergence Theorems for the Maximum of Normed Double Sums of Banach Space Valued random Elements

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Acta Mathematica Sinica,English Series 2024年第7期40卷 1727-1740页

作者： Andrew rOSALSKY Le Van THANH Nguyen thi THUY Department of Statistics University of FloridaGainesvilleFL 32611-8545USA Department of Mathematics Vinh UniversityVinhNghe AnViet Nam High School for Gifted Students Vinh UniversityVinhNghe AnViet Nam

In this correspondence,we establish mean convergence theorems for the maximum of normed double sums of Banach space valued random *** of the results pertain to random elements which are *** expand and improve a number of particular cases in the literature on mean convergence of random elements in Banach *** of the main contributions of the paper is to simplify and improve a recent result of Li,presnell,and rosalsky[Journal of Mathematical Inequalities,16,117–126(2022)].A new maximal inequality for double sums of M-dependent random elements is proved which may be of independent *** sharpness of the results is illustrated by four examples.

关键词： Double sum mean convergence rademacher type p Banach space Banach space valued random element M-dependent random elements

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Stability Analysis of DC Microgrid Clusters Based on Step-by-step System Matrix Building Algorithm

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Journal of Modern power Systems and Clean Energy 2024年第3期12卷 900-912页

作者： K.Jithin N.Mayadevi r.Hari Kumar V.p.Mini the Department of Electrical Engineering College of Engineering TrivandrumAPJ Abdul Kalam Technological University(APJAKTU)ThiruvananthapuramIndia

DC microgrids(DCMGs)are made up of a network of sources and loads that are connected by a number of power electronic converters(pECs).The increase in the number of these pECs instigates major concerns in system *** interconnecting the microgrids to form a cluster,the system stability must be *** paper proposes a novel stepby-step system matrix building(SMB)algorithm to update the system matrix of an existing DCMG cluster when a new microgrid is added to the cluster through a distribution *** stability of the individual DCMGs and the DCMG cluster is analyzed using the eigenvalue ***,the particle swarm optimization(pSO)algorithm is used to retune the controller gains if the newly formed cluster is not *** simulation of the DCMG cluster is carried out in MATLAB/Simulink environment to test the proposed *** results are also validated using the Op4510 real-time simulator(rTS).

关键词： Converter DC microgrid cluster eigenvalue interconnection particle swarm optimization system stability system matrix

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An isogeometric approach for nonlocal bending and free oscillation of magneto-electro-elastic functionally graded nanobeam with elastic constraints

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FrONTIErS OF StrUCTUrAL AND CIVIL ENGINEErING 2024年第9期18卷 1401-1423页

作者： thi, Thu Huong Nguyen tran, Van Ke pham, Quoc Hoa Hanoi Univ Ind Sch Mech & Automot Engn Hanoi 100000 Vietnam Le Quy Don Tech Univ Fac Mech Engn Hanoi 100000 Vietnam Nguyen Tat Thanh Univ Fac Engn & Technol Ho Chi Minh City 700000 Vietnam

this work uses isogeometric analysis (IGA), which is based on nonlocal hypothesis and higher-order shear beam hypothesis, to investigate the static bending and free oscillation of a magneto-electro-elastic functionally graded (MEE-FG) nanobeam subject to elastic boundary constraints (BCs). The magneto-electric boundary condition and the Maxwell equation are used to calculate the variation of electric and magnetic potentials along the thickness direction of the nanobeam. this study is innovative since it does not use the conventional boundary conditions. rather, an elastic system of straight and torsion springs with controllable stiffness is used to support nanobeams' beginning and end positions, creating customizable BCs. The governing equations of motion of nanobeams are established by applying Hamilton's principle and IGA is used to determine deflections and natural frequency values. Verification studies were performed to evaluate the convergence and accuracy of the proposed method. Aside from this, the impact of the input parameters on the static bending and free oscillation of the MEE-FG nanobeam is examined in detail. These findings could be valuable for analyzing and designing innovative structures constructed of functionally graded MEE materials.

关键词： elastic boundary conditions isogeometric analysis nanobeam via nonlocal theory grading of magneto-electro-elastic functions FrEE-VIBrATION DIFFErENTIAL-EQUATIONS TOpOLOGY OpTIMIZATION pLATES BEAMS BEHAVIOr NUrBS

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