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Optimality Conditions and Duality for Nondifferentiable Multiobjective Semi-Infinite Programming Problems with Generalized(C,α,ρ,d)-Convexity

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Journal of Systems Science & Complexity 2015年第1期28卷 47-59页

作者： MISHRA Shashi Kant JAISWAL Monika hoai AN le thi Department of Mathematics Banaras Hindu University Laboratory of Theoretical and Applied Computer Science LITA UFR MIMUniversity of Lorraine

this paper obtains sufficient optimality conditions for a nonlinear nondifferentiable multiobjective semi-infinite programming problem involving generalized(C,α,ρ,d)-convex *** authors formulate Mond-Weir-type dual model for the nonlinear nondifferentiable multiobjective semiinfinite programming problem and establish weak,strong and strict converse duality theorems relating the primal and the dual problems.

关键词： Duality generalized convexity optimality conditions semi-infinite programming.

A New Inertial Self-adaptive Gradient Algorithm for the Split Feasibility Problem and an Application to the Sparse Recovery Problem

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Acta Mathematica Sinica,English Series 2023年第12期39卷 2489-2506页

作者： Nguyen The VINH Pham thi hoai le Anh DUNG Yeol Je CHO Department of Mathematical Analysis University of Transport and Communications3 Cau Giay StreetHanoiVietnam Department of Applied Mathematics School of Applied Mathematics and InformaticsHano University of Science and Technology1 Dai Co Viet RoadHanoiVietnam Department of Mathematics and Informatics Hanoi University of Education136 Xuan ThuyCau GiayHanoiVietnam Department of Mathematics Education Gyeongsang National UniversityJinju52828Republicof Korea

In this paper,by combining the inertial technique and the gradient descent method with Polyak's stepsizes,we propose a novel inertial self-adaptive gradient algorithm to solve the split feasi-bility problem in Hilbert spaces and prove some strong and weak convergence theorems of our method under standard *** examine the performance of our method on the sparse recovery prob-lem beside an example in an infinite dimensional Hilbert space with synthetic data and give some numerical results to show the potential applicability of the proposed method and comparisons with related methods emphasize it further.

关键词： Split feasibility problem CQ algorithm Hilbert space sparse recovery problem

ALMA observations of the circumstellar envelope around EP Aqr

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Research in Astronomy and Astrophysics 2019年第3期19卷 97-110页

作者： Pham thi Tuyet Nhung Do thi hoai Pham Tuan-Anh thibaut le Bertre Pierre Darriulat Pham Ngoc Diep Nguyen thi Phuong Nguyen thi Thao Jan Martin Winters Department of Astrophysics Vietnam National Space CenterVAST leRMA UMR 8112 CNRS and Observatoire de Paris PSL Research University Graduate University of Science and Technology VAST IRAM 300 rue de la Piscine Domaine Universitaire

Atacama Large Millimetre/sub-millimetre Array(ALMA) observations of CO(1–0) and CO(2–1) emissions from the circumstellar envelope of the asymptotic giant branch(AGB) star EP Aqr have been made with four times better spatial resolution than previously available. They are analysed with emphasis on the de-projection in space of the effective emissivity and flux of matter using as input a prescribed configuration of the velocity field, assumed to be radial. The data are found to display an intrinsic axisymmetry with respect to an axis making a small angle with respect to the line of sight. A broad range of wind configurations, from prolate(bipolar) to oblate(equatorial) has been studied and found to be accompanied by significant equatorial emission. Qualitatively, the effective emissivity is enhanced near the equator to produce the central narrow component observed in the Doppler velocity spectra and its dependence on star latitude generally follows that of the wind velocity with the exception of an omni-present depression near the poles. In particular, large equatorial expansion velocities produce a flared disc or a ring of effective emissivity and mass loss. The effect on the determination of the orientation of the star axis of radial velocity gradients, and possibly competing rotation and expansion in the equatorial disc, is discussed. In general,the flux of matter is found to reach a broad maximum at distances of the order of 500 AU from the *** are given that may be used to favour one wind velocity distribution over another. As a result of the improved quality of the data, a deeper understanding of the constraints imposed on morphology and kinematics has been obtained.

关键词： stars: AGB and post-AGB (stars:) circumstellar matter stars: individual: EP Aqr stars:mass-loss radio lines: stars

On the central symmetry of the circumstellar envelope of RS Cnc

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Research in Astronomy and Astrophysics 2015年第5期15卷 713-724页

作者： Pham Tuyet Nhung Do thi hoai Jan Martin Winters Pierre Darriulat Eric Grard thibaut le Bertre VATLY INST 179 Hoang Quoc Viet Cau Giay Hanoi Vietnam leRMA UMR 8112 CNRS & Observatoire de Paris 61 av. de l’Observatoire F-75014 ParisFrance IRAM 300 rue de la Piscine Domaine Universitaire F-38406 St. Martin d’Heres France GEPI UMR 8111 CNRS & Observatoire de Paris 5 Place J. Janssen F-92195 Meudon CedexFrance

We present a phenomenological study of CO（1-0） and CO（2-1） emission from the circumstellar envelope （CSE） of the Asymptotic Giant Branch （AGB） star RS Cnc. It reveals departures from central symmetry that turn out to be efficient tools for the exploration of some of the properties of the CSE. We use a wind model including a bipolar flow with a typical wind velocity of ～8 km s^-1 that decreases to ～2 km s^-1 near the equator. this wind model is used to describe Doppler velocity spectral maps obtained by merging data collected at the IRAM Plateau de Bure Interferometer and Pico Veleta single dish radio telescope. Parameters describing the wind morphology and kinematics are obtained, together with the radial dependence of the gas temperature in the domain of the CSE probed by the CO observations. Significant north-south central asymmetries are revealed by the analysis, which we quantify using a simple phenomenological description. The origin of such asymmetries is unclear.

关键词： stars AGB and post-AGB -- stars individual (RS Cnc) -- stars mass loss -- radio lines general

Calibration of a neutron dose rate meter in various neutron standard fields

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Nuclear Science and Techniques 2020年第6期31卷 75-82页

作者： Tuan Khai Nguyen hoai-Nam Tran Quynh Ngoc Nguyen thi My Linh Dang Van Loat Bui thiansin Liamsuwan Ngoc-thiem le Vietnam Agency for Radiation and Nuclear Safety 113 Tran Duy HungHanoi 100000Vietnam Institute of Fundamental and Applied Sciences Duy Tan UniversityHo Chi Minh 700000Vietnam Faculty of Natural Sciences Duy Tan University3 Quang TrungDa Nang 550000Vietnam Institute for Nuclear Science and Technology VINATOM179 Hoang Quoc VietHanoi 100000Vietnam Faculty of Physics VNU University of Science334 Nguyen TraiHanoi 100000Vietnam Nuclear Research and Development Division Thailand Institute of Nuclear TechnologyOngkharakNakorn NayokThailand 7 Faculty of Medicine and Public HealthHRH Princess Chulabhorn College of Medical ScienceChulabhorn Royal AcademyBangkokThailand

this paper presents the calibration of a neutron dose rate meter and the evaluation of its calibration factors(CFs)in several neutron standard fields(i.e.,two standard fields with bare sources of252Cf and241Am-Be,and five simulated workplace fields with241Am-Be moderated sources).The calibration in standard fields with bare sources was conducted by following the recommendations of the ISO 8529 *** measured total neutron ambient dose equivalent rates,denoted as H*(10)tot,were analyzed to obtain direct components,denoted as H*(10)dir,using a reduced fitting *** CF was then calculated as the ratio between the conventional true value of the neutron ambient dose equivalent rate in a free field,denoted as H*(10)FF,and the value of H*(10)*** contrast,in the simulated workplace neutron fields,the calibration of the neutron dose rate meter was conducted by following the ISO 12789 *** CF was calculated as the ratio between the values of H*(10)totmeasured by a standard instrument(i.e.,Bonner sphere spectrometer)and the neutron dose rate *** CF values were obtained in the range of 0.88–*** standard uncertainties(k=1)of the CFs were determined to be in the range of approximately 6.6–13.1%.

关键词： Neutron standard fields Neutron dose rate meter Calibration factor 252Cf source 241AmBe source

An isogeometric analysis approach for dynamic response of doubly-curved magneto electro elastic composite shallow shell subjected to blast loading

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Defence Technology（防务技术） 2024年第11期41卷 159-180页

作者： Pham Hoang Tu Tran Van Ke Vu Khac Trai le hoai Faculty of Automotive Engineering School of TechnologyVan Lang UniversityHo Chi Minh City 700000Viet Nam Faculty of Mechanical Engineering Le Quy Don Technical UniversityHanoi 100000Viet Nam Faculty of Engineering and Technology Nguyen Tat Thanh UniversityHo Chi Minh City 700000Viet Nam HUTECH Institute of Engineering HUTECH UniversityHo Chi Minh City 700000Viet Nam

For the first time, the isogeometric analysis(IGA) approach is used to model and analyze free and forced vibrations of doubly-curved magneto-electro-elastic(MEE) composite shallow shell resting on the visco-Pasternak foundation in a hygro-temperature environment. The doubly-curved MEE shallow shell types include spherical shallow shell, cylindrical shallow shell, saddle shallow shell, and elliptical shallow shell subjected to blast load are investigated. The Maxwell equation and electromagnetic boundary conditions are used to determine the vary of the electric and magnetic potentials. The MEE shallow shell's equations of motion are derived from Hamilton's principle and refined higher-order shear theory. Then, the IGA method is used to derive the laws of natural frequencies and dynamic responses of the shell under various boundary conditions. The accuracy of the model and method is verified through reliable numerical comparisons. Aside from this, the impact of the input parameters on the free and forced vibration of the doubly-curved MEE shallow shell is examined in detail. These results may be useful in the design and manufacture of military structures such as warships, fighter aircraft, drones and missiles.

关键词： IGA approach Free and forced vibration Doubly-curved MEE shallow shell Blast load

An Analytical Approach for Nonlinear Buckling Analysis of Torsionally Loaded Sandwich Carbon Nanotube Reinforced Cylindrical Shells with Auxetic Core

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Advances in Applied Mathematics and Mechanics 2023年第2期15卷 468-484页

作者： Dang Thuy Dong Nguyen thi Phuong Vu hoai Nam le Ngoc Ly Nguyen Van Tien Vu Minh Duc Tran Quang Minh Vu Tho Hung Nguyen thi Huong Giang Faculty of Civil Engineering University of Transport TechnologyHanoi 100000Vietnam Graduate School of Advanced Science and Engineering Hiroshima University1-4-1 KagamiyamaHigashi-HiroshimaHiroshima 739-8527Japan Faculty of Fundamental Science for Engineering University of Transport TechnologyHanoi 100000Vietnam

The main aim of this paper is to present an analytical approach on the postbuckling for torsionally loaded sandwich carbon nanotube(CNT)reinforced cylindrical shells with the auxetic *** considered shells consist of three layers,external and internal CNT reinforced layers,and the auxetic lattice core made by isotropic *** homogenization model for honeycomb auxetic lattice core is utilized,and the equilibrium equations are formulated based on the nonlinear Donnell’s thin shell theory with von Karman geometrical *** three terms of deflection are considered,the Airy’s stress function and Galerkin’s method are utilized,the explicit expression of critical buckling of torsionally loaded shells and load-deflection expression of postbuckling states are *** effects of two carbon nanotube reinforced layers,the auxetic core layer,the volume fraction of carbon nanotube on the torsional buckling behavior are examined and remarked.

关键词： Nonlinear postbuckling carbon nanotube reinforced composite cylindrical shell torsion auxetic core

Xanthine oxidase inhibitors from Archidendron clypearia(Jack.) I.C. Nielsen: Results from systematic screening of Vietnamese medicinal plants

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Asian Pacific Journal of Tropical Medicine 2017年第6期10卷 619-626页

作者： Nguyen Thuy Duong Pham Duc Vinh Phuong thien Thuong Nguyen thi hoai le Nguyen Thanh Tran The Bach Nguyen Hai Nam Nguyen Hoang Anh Department of Pharmacology Hanoi University of Pharmacy Department of Pharmaceutical Analysis and Standardization National Institute of Medicinal Materials Department of Pharmacognosy Hue University of Medicine and Pharmacy Institute of Marine Biochemistry Vietnam Academy of Science and Technology Institute of Ecology and Biological Resources Vietnam Academy of Science and Technology Department of Medicinal Chemistry Hanoi University of Pharmacy

Objective: To screen Vietnamese medicinal plants for xanthine oxidase(XO) inhibitory activity and to isolate XO inhibitor(s) from the most active plant. Methods: The plants materials were extracted by methanol. The active plant materials were fractionated using different organic solvents, including n-hexane, ethyl acetate, and n-butanol. Bioassay-guided fractionation and column chromatography were used to isolate compounds. The compounds structures were elucidated by analysis of spectroscopic data, including IR, MS, and NMR. Results: Three hundreds and eleven methanol extracts(CME) belonging to 301 Vietnamese herbs were screened for XO inhibitory activity. Among these plants, 57 extracts displayed XO inhibitory activity at 100 μg/m L with inhibition rates of over 50%. The extracts of Archidendron clypearia, Smilax poilanei, Linociera ramiflora and Passiflora foetida exhibited the greatest potency with IC_(50) values below 30 μg/m L. Chemical study performed on the extract of Archidendron clypearia resulted in the isolation of six compounds, including 1-octacosanol, docosenoic acid, daucosterol, methyl gallate, quercitrin and(-)-7-O-galloyltricetiflavan. The compound(-)-7-O-galloyltricetiflavan showed the most potent XO inhibitory activity with an IC_(50) value of 25.5 μmol/L. Conclusions: From this investigation, four Vietnamese medicinal plants were identified to have XO inhibitory effects with IC_(50) values of the methanol extracts below 30 μg/m L. Compound(-)-7-O-galloyltricetiflavan was identified as an XO inhibitor from Archidendron clypearia with IC_(50) value of 25.5 μmol/L.

关键词： Xanthine oxidase Inhibitor Medicinal plants Vietnam

Evaluation of the calibration factors of neutron dose rate meters in a 241Am–Be neutron field

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Nuclear Science and Techniques 2019年第9期30卷 18-23页

作者： thiem Ngoc le Sy Minh Tuan Hoang Quynh Ngoc Nguyen hoai-Nam Tran Institute for Nuclear Science and Technology VINATOM 179 Hoang Quoc Viet Hanoi Vietnam Institute of Fundamental and Applied Sciences Duy Tan University Ho Chi Minh City Vietnam

Calibrations were performed for three types of neutron ambient dose equivalent rate meters, i.e., Aloka TPS-451C (Hitachi), KSAR1U.06 (Baltic Scientific Instruments), and Model 12-4 (Ludlum), using a standard field of a 241Am–Be source. The measured total neutron ambient dose equivalent rates, H*(10)' tot, were analyzed to obtain the direct neutron ambient dose equivalent rates, H*(10)' dir, using the ISO 8529-2-recommended generalized- fit method, semiempirical fit method, and reducedfitting method (RFM) fit methods. The calibration factor (CF), defined as the ratio between the conventional true value of the neutron ambient dose equivalent rates in a free field, H*(10)' FF, and H*(10)' dir, was evaluated as one of the important characteristics of the neutron meters in the present work. The fitting results show that the H*(10)' dir values of the meters are in good agreement within the theoretical data within 4%. The averaged CFs of the three neutron meters were evaluated as 0:99 ± 0:01, 1:00 ± 0.03;and 0:99 ± 0:08, respectively. The largest standard uncertainty of these values was determined to be approximately 18.47%(k =1). The standard uncertainty of the CFs obtained using the RFM method was less than 4.23%(k=1), which is the smallest uncertainty among the three methods.

关键词： Neutron meter Calibration factor ^241 Am–Be source