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Hydrogen roles approaching ideal electrical and optical properties for undoped and Al doped ZnO thin films

Journal of Materiomics 2022年第1期8卷 123-135页

作者： Dung Van Hoang Nam Hoang Vu Nga Thi Do anh tuan thanh pham Truong Huu Nguyen Jer-Lai Kuo Thang Bach Phan Vinh Cao Tran Laboratory of Advanced Materials University of ScienceHoChiMinh City700000Viet Nam Vietnam National University HoChiMinh City700000Viet Nam HoChiMinh City Institute of Physics HoChiMinh City700000Viet Nam Institute of Atomic and Molecular Sciences Academia SinicaTaipei10617Taiwan Center for Innovative Materials and Architectures(INOMAR) HoChiMinh City700000Viet Nam Faculty of Materials Science&Technology University of ScienceHoChiMinh City700000Viet Nam

This paper distinguished hydrogen roles to improve electron mobility and carrier concentration in ZnO and Al doped ZnO sputtered *** combining experimental evidences and theoretical results,we find out that hydrogen located at oxygen vacancy sites(H_(O))is the main factor gives rise to increase simultaneously mobility and carrier concentration which has not been mentioned *** appropriate hydrogen content during sputtering not only results in crystalline relaxation but also supports doping Al into ZnO,increasing carrier concentration and electron mobility in the *** principles calculations confirmed hydrogen substitutional stability for oxygen vacancy,significantly reducing electron conductivity effective mass and hence increasing electron *** particular,0.8%hydrogen partial pressure ratio achieved 61 cm^(2)V^(-1)s^(-1)maximum electron mobility,optical transmittance above 82%in visible and near-infrared regions,and 2×10^(20) cm^(-3)carrier concentrations for H-Al co-doped ZnO *** values approach ideal electrical and optical properties for transparent conducting oxide *** presence of one maximum electron mobility was attributed to competition between increasing mobility due to restoring effective electron mass and hydrogen passivation of native defects,and decreased electron mobility due to electron-phonon scattering.

关键词： High electron mobility Hydrogen roles Passivation effects Effective electron mass DFT calculations Doped ZnO thin Film

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Compensation of Zn substitution and secondary phase controls effective mass and weighted mobility in In and Ga co-doped ZnO material

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Journal of Materiomics 2021年第4期7卷 742-755页

作者： Oanh Kieu Truong Le anh tuan thanh pham Ngoc Kim pham Trang Huyen Cao pham Truong Huu Nguyen Dung Van Hoang Hanh Kieu Thi Ta Dai Cao Truong Hoa Thi Lai Thuy Dieu Thi Ung Vinh Cao Tran Thang Bach Phan aboratory of Advanced Materials University of ScienceHoChiMinh City700000Viet Nam Vietnam National University HoChiMinh City700000Viet Nam Faculty of Physics and Engineering Physics University of ScienceHoChiMinh City700000Viet Nam Faculty of Materials Science and Technology University of ScienceHoChiMinh City700000Viet Nam Center for Innovative Materials and Architectures(INOMAR) HoChiMinh CityViet Nam Institute of Materials Science Vietnam Academy of Science and TechnologyHanoi100000Viet Nam

Conductivity s and thermal conductivity k are directly related to carrier concentration while Seebeck coefficient S is inversely proportional to carrier ***,improving thermoelectric(TE)performance is ***,the first-time analysis of secondary phase-controlled TE performance in terms of density-of-state effective mass m*d,weighted mobility mw and quality factor B is discussed in ZnO *** results show that the secondary spinel phase Ga2O_(3)(ZnO)9 not only impacts on k but also on s and S at high temperature,while the effect of carrier concentration seem to be dominant at low *** the high-spinel-segregation sample,a compensation of dopant atoms from the spinel to substitutional sites in the ZnO matrix at high temperature leads to a low decreased rate of temperaturedependent m**** compensation process also induces a band sharpening,a small mw reduction,and a large B *** a result,In and Ga co-doped ZnO bulk with the highest spinel segregation achieves the greatest PF improvement by 112.8%,owing to enhanced Seebeck coefficient by 110%as compared to the good Zn-substitution sample.

关键词： Thermoelectrics In and Ga co-Doped ZnO Secondary phase Zn substitution DOS effective Mass Weighted mobility

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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

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Spherical Fuzzy WASPAS-based Entropy Objective Weighting for International Payment Method Selection

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Computers, Materials & Continua 2022年第7期72卷 2055-2075页

作者： Phi-Hung Nguyen thanh-tuan Dang Kim-anh Nguyen Hong-anh pham Faculty of Business FPT UniversityHanoi100000Vietnam Department of Business Management National Taipei University of TechnologyTaipei1068Taiwan Department of Industrial Engineering and Management National Kaohsiung University of Science and TechnologyKaohsiung80778Taiwan

In international trade,exporters prefer to receive payments as quickly as possible,and importers want to make payments as late as *** this respect,the payment field,an essential condition for trade transactions,also represents the positions of exporters and importers *** addition,there are many cases in which various variables must be considered rather than only one specific variable representatively affecting payment,particularly in the case of import-export Small and Medium-Sized Enterprises(SMEs)from emerging countries.A selection of proper payment methods can be categorized as a Multi-Criteria Decision-Making(MCDM)***,this study aims to propose a novel and efficient Spherical Fuzzy Weighted Aggregated Sum Product Assessment based Entropy Objective Weighting method(SF-EW and WASPAS-SF)to evaluate international payment methods with uncertain ***,SF-EW model is applied to determine the relative weights of critical ***,international payment method alternatives are prioritized by the WASPAS-SF *** essential factors for four international payment methods are proposed based on experts’opinions and the existing literature.A real-world case study from Vietnamese import-export SMEs is presented to validate the applicability of the proposed *** results indicated that“Characteristics of payment method(PA)”had the most significant impact on international payment method *** comparison,“Letters of Credit(L/C)”was the most reliable payment method with the highest ranking available to international ***,a sensitivity analysis was performed to examine the validity and robustness of the proposed decision support ***,this study could contribute to international payment services and in the context of globalization and international trade.

关键词： International payment Vietnam MCDM spherical fuzzy theory entropy WASPAS

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A Neural-network-based Approach to Study the Energy-optimal Hovering Wing Kinematics of a Bionic Hawkmoth Model

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Journal of Bionic Engineering 2019年第5期16卷 904-915页

作者： anh tuan Nguyen Ngoc Doan Tran thanh Trung Vu thanh Dong pham Quoc Tru Vu Jae-Hung Han Faculty of Aerospace Engineering Le Quy Don Technical University236 Hoang Quoc VietVietnam Office of International Cooperation Le Quy Don Technical University236 Hoang Quoc VietVietnam Department ofAerospace Engineerings Korea Advanced Institute of Science and Technology Daejeon 34141Republic ofKorea

This paper presents the application of an artificial neural network to develop an approach to determine and study the energy-optimal wing kinematics of a hovering bionic hawkmoth model.A three-layered artificial neural network is used for the rapid prediction of the unsteady aerodynamic force acting on the wings and the required *** this artificial network is integrated into genetic and simplex algorithms,the running time of the optimization process is reduced *** validity of this new approach is confirmed in a comparison with a conventional method using an aerodynamic model based on an extended unsteady vortex-lattice method for a sinu soidal wing kinematics *** studying the obtained results,it is found that actual hawkmoths do not hover under an energy-optimal ***,by tilting the stroke plane and lowering the wing positions,they can compromise and expend some energy to enhance their maneuverability and the stability of their flight.

关键词： optimal hovering wing kinematics artificial neural network insect flight genetic algorithm unsteady vortex-lattice method bionics

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Hybrid model to optimize object-based land cover classification by meta-heuristic algorithm:an example for supporting urban management in Ha Noi,Viet Nam

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International Journal of Digital Earth 2019年第10期12卷 1118-1132页

作者： Quang-thanh Bui Manh pham Van Nguyen Thi Thuy Hang Quoc-Huy Nguyen Nguyen Xuan Linh pham Minh Hai Tran anh tuan pham Van Cu Center for Applied Research in Remote sensing and GIS(CARGIS) VNU University of ScienceHa NoiViet Nam VNU University of Science Ha NoiViet Nam Vietnam Institute of Geodesy and Cartography Ha NoiViet Nam Ministry of Education and Training Ha NoiViet Nam

This study proposed a novel object-based hybrid classification model named GMNN that combines Grasshopper Optimization Algorithm(GOA)and the multiple-class Neural network(MNN)for urban pattern detection in Hanoi,*** bands of SPOT 7 image and derivable NDVI,NDWI were used to generate image segments with associated attributes by PCI Geomatics *** segments were classified into four urban surface types(namely water,impervious surface,vegetation and bare soil)by the proposed ***,three training and validation datasets of different sizes were used to verify the robustness of this *** all tests,the overall accuracies of the classification were approximately 87%,and the Area under Receiver Operating Characteristic curves for each land cover type was ***,the performance of this model was examined by comparing several statistical indicators with common benchmark *** results showed that GMNN out-performed established methods in all comparable *** results suggested that our hybrid model was successfully deployed in the study area and could be used as an alternative classification method for urban land cover *** a broader sense,classification methods will be enriched with the active and fast-growing contribution of metaheuristic algorithms.

关键词： Urban remote sensing object-based classification neural network grasshopper optimization algorithm

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Novel Criteria for Exponential Stability of Linear Non-Autonomous Functional Differential Equations

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Journal of Systems Science & Complexity 2019年第2期32卷 479-495页

作者： pham HUU anh Ngoc THAI BAO Tran CAO thanh Tinh NGUYEN DINH Huy Department of Mathematics Vietnam National University-HCMC International University Faculty of Information Systems Vietnam National University-HCMC University of Information Technology Department of Mathematics Vietnam National University-HCMC University of Information Technology Division of Applied Mathematics Faculty of Applied Sciences Vietnam National University-HCMC Ho Chi Minh city University of Technology

General linear non-autonomous functional differential equations are considered. Explicit criteria for exponential stability are given. Furthermore, the authors present an explicit robust stability bound for systems su... 详细信息

关键词： Exponential stability linear functional differential equations perturbation

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A fully automated framework for helicopter rotor blades design and analysis including aerodynamics,structure, and manufacturing

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Chinese Journal of Aeronautics 2016年第6期29卷 1602-1617页

作者： Ngoc anh Vu Jae Woo Lee tuan Phuong Nam Le Song thanh Thao Nguyen Division of Computational Mechatronics Institute for Computational Science Ton Duc Thang University Faculty of Electrical & Electronics Engineering Ton Duc Thang University Department of Aerospace Information Engineering Konkuk University Faculty of Mechanical Engineering Industrial University of Ho Chi Minh City Department of Aerospace Engineering Ho Chi Minh City University of Technology Vietnam National University-Ho Chi Minh City

This study describes an integrated framework in which basic aerospace engineering aspects(performance, aerodynamics, and structure) and practical aspects(configuration visualization and manufacturing) are coupled and considered in one fully automated design optimization of rotor blades. A number of codes are developed to robustly perform estimation of helicopter configuration from sizing, performance analysis, trim analysis, to rotor blades configuration representation. These codes are then integrated with a two-dimensional airfoil analysis tool to fully design rotor blades configuration including rotor planform and airfoil shape for optimal aerodynamics in both hover and forward flights. A modular structure design methodology is developed for realistic composite rotor blades with a sophisticated cross-sectional geometry. A D-spar cross-sectional structure is chosen as a baseline. The framework is able to analyze all realistic inner configurations including thicknesses of D-spar, skin, web, number and ply angles of layers of each composite part,and materials. A number of codes and commercial software(ANSYS, Gridgen, VABS, Pre VABS,etc.) are implemented to automate the structural analysis from aerodynamic data processing to sectional properties and stress analysis. An integrated model for manufacturing cost estimation ofcomposite rotor blades developed at the Aerodynamic Analysis and Design Laboratory(AADL),Aerospace Information Engineering Department, Konkuk University is integrated into the framework to provide a rapid and dynamic feedback to configuration design. The integration of three modules has constructed a framework where the size of a helicopter, aerodynamic performance analysis, structure analysis, and manufacturing cost estimation could be quickly investigated. All aspects of a rotor blade including planform, airfoil shape, and inner structure are considered in a multidisciplinary design optimization without an exception of critical configuration.

关键词： Design optimization Helicopter rotor blades Integrated framework Modular structure design methodology Perform estimation

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Graphical method based on modified maximum force criterion to indicate forming limit curves of 22MnB5 boron steel sheets at elevated temperatures

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Journal of Iron and Steel Research International 2021年第8期28卷 1009-1018页

作者： thanh Luyen Quoc-tuan pham Thi-Bich Mac Tien-Long Banh Duc-Toan Nguyen Faculty of Mechanical Engineering Hungyen University of Technology and EducationHungyen 160000Vietnam Division of Computational Mathematics and Engineering Institute for Computational ScienceTon Duc Thang UniversityHo Chi Minh City 70000Vietnam Faculty of Civil Engineering Ton Duc Thang UniversityHo Chi Minh City 70000Vietnam School of Mechanical Engineering Hanoi University of Science and TechnologyHanoi City 100000Vietnam

A new approach for predicting forming limit curves(FLCs)at elevated temperatures was proposed *** are often used to predict failure and determine the optimal forming parameters of automotive ***,a graphical method based on a modified maximum force criterion was applied to estimate the FLCs of 22MnB5 boron steel sheets at room temperature using various hardening ***,the predicted FLC data at room temperature were compared with corresponding data obtained from Nakazima's tests to obtain the best *** estimate the FLC at elevated temperatures,tensile tests were conducted at various temperatures to determine the ratios of equivalent fracture strains between the corresponding elevated temperatures and room *** at elevated temperatures could be established based on obtained ***,the predicted FLCs at elevated temperatures did not agree well with the corresponding FLC experimental data of Zhou et al.A new method was proposed herein to improve the prediction of FLCs at elevated *** FLC calculated at room tem-perature was utilized to predict the failure of Nakazima's samples via finite element *** on the simulation results at room temperature,the mathematical relationships between the equivalent ductile fracture strain versus stress triaxiality and strain ratio were established and then combined with ratios between elevated and room temperatures to calculate the FLCs at different *** predicted FLCs at elevated temperatures agree well with the corresponding experimental FLC data.

关键词： Forming limit curve Modified maximum force criterion Graphical method Hardening law Finite element method Boron steel sheet Elevated temperature

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SeVe： automatic tool for verification of security protocols

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Frontiers of Computer Science 2012年第1期6卷 57-75页

作者： anh tuan LUU Jun SUN Yang LIU Jin Song DONG Xiaohong LI thanh Tho QUAN School of Computing National University of Singapore Singapore 119077 Singapore School of Computing Singapore University of Technology and Design Singapore 138682 Singapore Department of Computer Science Tianjin University Tianjin 300222 China Department of Computer Science HoChiMinhCity University of Technology HoChiMinh City 162903 Vietnam

Security protocols play more and more important roles with wide use in many applications nowadays. Cur- rently, there are many tools for specifying and verifying secu- rity protocols such as Casper/FDR, ProVerif, or AVISPA. In these tools, the intruder＇s ability, which either needs to be specified explicitly or set by default, is not flexible in some circumstances. Moreover, whereas most of the existing tools focus on secrecy and authentication properties, few supports privacy properties like anonymity, receipt freeness, and coer- cion resistance, which are crucial in many applications such as in electronic voting systems or anonymous online transac- tions. In this paper, we introduce a framework for specifying security protocols in the labeled transition system （LTS） se- mantics model, which embeds the knowledge of the par- ticipants and parameterizes the ability of an attacker. Us- ing this model, we give the formal definitions for three types of privacy properties based on trace equivalence and knowledge reasoning. The formal definitions for some other security properties, such as secrecy and authentica- tion, are introduced under this framework, and the veri- fication algorithms are also given. The results of this pa- per are embodied in the implementation of a SeVe mod- ule in a process analysis toolkit （PAT） model checker, which supports specifying, simulating, and verifying se- curity protocols. The experimental results show that a SeVe module is capable of verifying many types of secu- rity protocols and complements the state-of-the-art securityverifiers in several aspects. Moreover, it also proves the abil- ity in building an automatic verifier for security protocols re- lated to privacy type, which are mostly verified by hand now.

关键词： security protocols model checking processanalysis toolkit (PAT) authentication secrecy privacy

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