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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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Real-time security margin control using deep reinforcement leamning

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Energy and AI 2023年第3期13卷 52-63页

作者： Hannes Hagmar Robert Eriksson Le anh tuan Chalmers University of Technology Gothenburg 41296Sweden Svenska kraftnat(Swedish National Grid) Sundbyberg 17224Sweden

This paper develops a real-time control method based on deep reinforcement learning aimed to determine the optimal control actions to maintain a sufficient secure operating *** secure operating limit refers to the limit to the most stressed pre-contingency operating point of an electric power system that can withstand a set of credible contingencies without violating stability *** developed deep reinforcement learning method uses a hybrid control scheme that is capable of simultaneously adjusting both discrete and continuous action *** performance is evaluated on a modified version of the Nordic32 test *** results show that the developed deep reinforcement learning method quickly learns an effective control policy to ensure a sufficient secure operating limit for a range of different system *** performance is also compared to a control based on a rule-based look-up table and a deep reinforcement learning control adapted for discrete action *** hybrid deep reinforcement learning control managed to achieve significantly better on all of the defined test sets,indicating that the possibility of adjusting both discrete and continuous action variables resulted in a more flexible and efficient control policy.

关键词： Deep reinforcement learning Preventive control Proximal policy optimization Secure operating limit

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Finsler Trudinger-Moser inequalities on R^(2)

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Science China Mathematics 2022年第9期65卷 1803-1826页

作者： nguyen tuan Duy Le Long Phi Faculty of Economics and Law University of Finance-MarketingHCM City ***Vietnam Institute of Research and Development Duy Tan UniversityDa Nang 550000Vietnam

The first aim of this article is to study the sharp singular(two-weight)Trudinger-Moser inequalities with Finsler norms on R^(2).The second goal is to propose a different approach to study a vanishing-concentration-compactness principle for the Trudinger-Moser inequalities and use this to investigate the existence and the nonexistence of the maximizers for the Trudinger-Moser inequalities in the subcritical ***,by applying our Finsler Trudinger-Moser inequalities to suitable Finsler norms,we derive the sharp affine Trudinger-Moser inequalities which are essentially stronger than the Trudinger-Moser inequalities with standard energy of the gradient.

关键词： Trudinger-Moser inequality Finsler norm sharp constants extremal functions affine energy

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A Grey Simulation-Based Fuzzy Hierarchical Approach for Diagnosing Healthcare Service Quality

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Computers, Materials & Continua 2023年第2期74卷 3231-3248页

作者： Phi-Hung nguyen Hong-anh Pham Faculty of Business FPT UniversityHanoi100000Vietnam

This study aims to assess and rank the service quality of the healthcare system utilizing a Fuzzy Analytical Hierarchical Process(Fuzzy AHP)andGreyRelationalAnalysis(Fuzzy GRA)*** this study,the six primary characteristics of healthcare service quality,comprising Tangibles(A),Healthcare Staff(B),Responsiveness(C),Relationships(D),Support Service(E),and Accessibility(F),are examined through a case study of 20 private and public hospitals in Hanoi,*** weighting results of Fuzzy AHP technique indicated that Responsiveness(C)has the highest ranking,followed by Relationships(D)and Healthcare Staff(B).Meanwhile,Tangibility has finally comprised the next priority for increasing satisfaction with the service quality in the healthcare ***,the highest service quality rankings are top 5 private hospitals via the Fuzzy GRA ***,this proposed approach may be applied to a complex decision-making process,which often makes sense with subjective data or imprecise information.

关键词： MCDM fuzzy sets AHP GRA healthcare Vietnam

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Contributions of Rotation,Expansion and Line Broadening to the Morphology and Kinematics of the Inner CSE of Oxygen-rich AGB Star R Hya

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Research in Astronomy and Astrophysics 2023年第1期23卷 40-47页

作者： Pham Tuyet Nhung Do Thi Hoai Pierre Darriulat Pham Ngoc Diep nguyen Bich Ngoc Tran Thi Thai Pham tuan-anh Department of Astrophysics Vietnam National Space CenterVietnam Academy of Science and Technology18Hoang Quoc VietNghia DoCau GiayHa NoiVietnam

We use archival ALMA observations of the CO(2-1)and SiO(5-4)molecular line emissions of AGB star R Hya to illustrate the relative contributions of rotation,expansion and line broadening to the morphology and kinematics of the circumstellar envelope(CSE)within some~70 au(~0."5)from the centre of the *** give evidence for rotation and important line broadening to dominate the inner region,within~14 au(~100 mas)from the centre of the *** former is about an axis that projects a few degrees west of north and has a projected rotation velocity of a few km s^(-1).The latter occurs within some 7-14 au(50-100 mas)from the centre of the star,with the line width reaching two to three times its value outside this *** suggest that it is caused by shocks induced by stellar pulsations and convective cell *** show the importance of properly accounting for the observed line broadening when discussing rotation and evaluating the radial dependence of the rotation velocity.

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

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Truly optimal semi-active damping to control free vibration of a single degree of freedom system

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Theoretical & Applied Mechanics Letters 2024年第2期14卷 142-145页

作者： Viet Duc La Ngoc tuan nguyen Institute of Mechanics Vietnam Academy of Science and TechnologyHanoi 10000Vietnam Graduate University of Science and Technology Vietnam Academy of Science and TechnologyHanoi 10000Vietnam

This paper studies a single degree of freedom system under free vibration and controlled by a general semiactive damping.A general integral of squared error is considered as the performance index.A one-time switching damping controller is proposed and *** pontryagin maximum principle is used to prove that no other form of semi-active damping can provide the better performance than the proposed one-time switching damping.

关键词： Analytical optimization Quadratic integral Lyapunov equation Pontryagin maximum principle

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A hybrid machine learning model to estimate self-compacting concrete compressive strength

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Frontiers of Structural and Civil Engineering 2022年第8期16卷 990-1002页

作者： Hai-Bang LY Thuy-anh nguyen Binh Thai PHAM May Huu nguyen Civil Engineering Department University of Transport TechnologyHanoi 100000Vietnam Civil and Environmental Engineering Program Graduate School of Advanced Science and EngineeringHiroshima UniversityHiroshima 739-8527Japan

This study examined the feasibility of using the grey wolf optimizer(GWO)and artificial neural network(ANN)to predict the compressive strength(CS)of self-compacting concrete(SCC).The ANN-GWO model was created using 115 samples from different sources,taking into account nine key SCC *** validation of the proposed model was evaluated via six indices,including correlation coefficient(R),mean squared error,mean absolute error(MAE),IA,Slope,and mean absolute percentage *** addition,the importance of the parameters affecting the CS of SCC was investigated utilizing partial dependence *** results proved that the proposed ANN-GWO algorithm is a reliable predictor for SCC’s *** that,an examination of the parameters impacting the CS of SCC was provided.

关键词： artificial neural network grey wolf optimize algorithm compressive strength self-compacting concrete

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Predicting shear strength of slender beams without reinforcement using hybrid gradient boosting trees and optimization algorithms

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Frontiers of Structural and Civil Engineering 2022年第10期16卷 1267-1286页

作者： Thuy-anh nguyen Hai-Bang LY Van Quan TRAN Department of Civil Engineering University of Transport TechnologyHanoi 100000Vietnam

Shear failure of slender reinforced concrete beams without stirrups has surely been a complicated occurrence that has proven challenging to adequately *** primary purpose of this work is to develop machine learning models capable of reliably predicting the shear strength of non-shear-reinforced slender beams(SB).A database encompassing 1118 experimental findings from the relevant literature was compiled,containing eight distinct *** Boosting(GB)technique was developed and evaluated in combination with three different optimization algorithms,namely Particle Swarm Optimization(PSO),Random Annealing Optimization(RA),and Simulated Annealing Optimization(SA).The findings suggested that GB-SA could deliver strong prediction results and effectively generalizes the connection between the input and output *** values and two-dimensional PDP analysis were then carried *** may use the findings in this work to define beam’s geometrical components and material used to achieve the desired shear strength of SB without reinforcement.

关键词： slender beam shear strength gradient boosting optimization algorithms

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Gravitationally lensed extended sources: the case of QSO RXJ0911

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Research in Astronomy and Astrophysics 2013年第7期13卷 803-814页

作者： Do Thi Hoai Pham Tuyet Nhung Pham tuan anh Frederic Boone Pierre Darriulat Pham Ngoc Diep Pham Ngoc Dong nguyen Van Hiep nguyen Thi Thao VATLY INST179Hoang Quoc VietCau GiayHanoiVietnam IRAP 14avenue Edouard BelinF31400 ToulouseFrance

After a brief reminder of the mechanism of gravitational lensing of ex- tended sources, the particular case of the host galaxy of QSO RXJ0911, a high red-shift （z - 2.8） quadruply imaged quasar, is explored. The non linearity of the problem, together with the proximity of the source to a cusp of the lens inner caustic, has impor-tant consequences on the dependence of the image appearance on the size and shape of the source. Their expected main features and their interpretation in terms of source extension and shape are investigated in a spirit of simplicity and in preparation for the analysis of high sensitivity and spatial resolution images that will soon be within reach with the completion of the Atacama Large Millimeter/submillimeter Array （ALMA）. In particular, the information on source size carded by relative image brightness is dis-cussed. Extension of the results to other types of quadruply imaged quasars is briefly considered.

关键词： gravitational lensing - galaxies: high-redshift

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安庆-贵池矿集区宝树尖铜多金属矿床成因:来自岩石地球化学及年代学的约束

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岩石学报 2020年第1期36卷 184-204页

作者：汪海赵壮杨晓勇古黄玲郑荥 nguyen tuan anh 中国科学技术大学地球和空间科学学院湖南工业大学安徽省地勘局324地质队

宝树尖铜多金属矿床位于长江中下游成矿带安庆-贵池矿集区,是一个新发现的矽卡岩型矿床。本文主要通过岩石地球化学和年代学方法来解释矿床的成因。锆石U-Pb年代学研究表明,宝树尖岩体形成于148.6±3.2Ma,是长江中下游燕山晚期的产物,... 详细信息

宝树尖铜多金属矿床位于长江中下游成矿带安庆-贵池矿集区,是一个新发现的矽卡岩型矿床。本文主要通过岩石地球化学和年代学方法来解释矿床的成因。锆石U-Pb年代学研究表明,宝树尖岩体形成于148.6±3.2Ma,是长江中下游燕山晚期的产物,为长江中下游成矿带内发现的一个较早的中酸性含矿侵入体。对于该成矿岩体及矿床的深入研究,将为区内燕山期岩浆活动及成矿提供一个不可多得的范例。岩石属于高钾钙碱性、钙碱性系列,地球化学特征显示为埃达克质岩;矿区矿石金属硫化物以方铅矿、闪锌矿、黄铜矿和黄铁矿为主,非金属矿物有透辉石、石榴石、透闪石、石英、钠长石、方解石、绿泥石和绿帘石等。矿区侵入岩主要由闪长岩和闪长玢岩组成,总体上具有高的全碱含量,低的Al2O3、TiO 2、Fe2O3^T和P2O5含量,富集大离子亲石元素(U、Rb、Sr)和高场强元素(Nb、Ta、Ti),轻稀土富集、重稀土亏损。岩石具有高的La/Yb、Sr/Y比值,低的Yb、Y含量,属于埃达克质岩。锆石稀土元素配分图显示典型的轻稀土亏损、重稀土富集。锆石Ti温度计表明岩石形成的平均温度为674.3℃。全岩Sr-Nd-Pb同位素特征表明岩石起源于俯冲洋壳的部分熔融。矿石黄铁矿δ34 S变化范围为7.6‰~9.6‰,表明成矿物质来源于岩浆热液和地层。锆石Eu异常特征和Ce^4+/Ce^3+比值表明形成岩石的岩浆具有高氧逸度,这有利于Cu、Au、Zn等成矿物质的迁移。结合区域地质背景,我们认为宝树尖矽卡岩型矿床的形成过程是:燕山期太平洋板块向中国东部俯冲,导致板片部分熔融产生埃达克质岩浆,最后经埃达克质岩浆分异形成的含矿气水热液在地壳浅部与上覆寒武系灰岩发生接触交代作用。

关键词：宝树尖多金属矿床安庆贵池矿集区埃达克岩锆石U-Pb定年 Sr-Nd-Pb同位素俯冲洋壳长江中下游

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