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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

Exploring the Interplay between Job Stress,Work Performance,and Attitudes toward Professional Psychological Help among Employees

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International Journal of Mental Health Promotion 2024年第7期26卷 531-545页

作者： Cong Minh Le Son Van Huynh Ky Luu Quynh-Nhi ngoc Ho Van Thi Le Nguyen Vinh-Long tran-Chi Center for Mental Health Research and Support University of Social Sciences and HumanitiesVietnam National University Ho Chi Minh CityHo Chi Minh City700000Vietnam Faculty of Psychology Ho Chi Minh City University of EducationHo Chi Minh City700000Vietnam Faculty of Tourism College of BusinessUniversity of Economics Ho Chi Minh CityHo Chi Minh City700000Vietnam Scientific Management Department Dong A UniversityDa Nang500000Vietnam

Objective:This study explores the interplay between job stress,job-related factors,work performance,and attitudes toward seeking professional psychological help among Vietnamese ***:A total of 374 employees in Vietnam were surveyed using random sampling and an online questionnaire from November 07 to November 28,*** data and self-reported from three scales:The New Job Stress Scale(NJSS),Work Performance(WP),and Attitudes Toward Seeking Professional Psychological Help(ATSPPH_SF)were ***:Significant variations were found across several variables,including forms of work,operating hours,education levels,monthly income,numbers of daily working hours,and the presence of a psychological counseling department within the *** analysis has highlighted direct relationships between key latent *** who were more open to seeking professional help tended to report higher levels of job *** negative relationship was found between job stress and attitudes toward seeking professional ***,work effort was positively associated with work *** analyses revealed the influence of co-worker support on role expectation conflict and work effort,role expectation conflict and work-life balance,as well as interactions between role expectation conflict and attitudes needed toward seeking professional *** analyses showed that work effort mediated relationships between openness to seeking professional help,co-worker support,work-life balance,role expectation conflict,and work *** toward seeking professional help also mediated relationships between work-life balance,job stress,and work ***:The study highlights the complex dynamics surrounding job stress,job-related factors,work performance,and attitudes toward seeking professional psychological help among Vietnamese *** highlights the importance of addressing help-seeking barriers,promoting work engagement

关键词： Stress co-worker support work-life balance role expectation conﬂict professional psychological help-seeking

Tissue engineering using mesenchymal stem cells with periosteal wrap for bone defect repair in rabbits

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Plastic and Aesthetic Research 2015年第1期2卷 340-345页

作者： Trung-Hau LêThua Dang-Nhat Pham Khanh-Linh Lê Minh-Tuan Lê Quang-Ton-Quyen Nguyen Phan-Huy Nguyen ngoc-vu tran ngoc-Luong Nguyen Willy Boeckx Albert Demey Department of Plastic Reconstructive and Hand SurgeryCenter of Orthopaedic and Plastic SurgeryHue Central HospitalHue City 531120Vietnam Department of Hematology Hue Central HospitalHue City 531120Vietnam Department of Biology College of SciencesHue UniversityHue City 521120Vietnam Department of Plastic Surgery Brugmann University HospitalUniversitélibre de Bruxelles1020 BrusselsBelgium

Aim:Mesenchymal stem cells(MSCs)are an excellent potential source of cells for bone tissue engineering due to their excellent renewal ability and osteogenic differentiation *** study was designed to evaluate the bone formation properties of a demineralized cancellous bone scaffold seeded with MSCs,with or without periosteum,in a critical size bone defect model in ***:Rabbit culture-expanded bone marrow(BM)-MSCs were seeded onto a human demineralized cancellous bone(HDCB)*** defects measuring 15 mm in length were created in each radius.A total of 56 bone defects in 28 rabbits were randomly assigned to one of the 4 groups for scaffold implantation:Group 1:HDCB graft only;Group 2:periosteum-wrapped HDCB graft;Group 3:HDCB graft seeded with BM-MSCs and Group 4:periosteum-wrapped HDCB graft seeded with *** rabbits were sacrificed 12 weeks after surgery for gross observation,radiological assessment,histological analyses and biomechanical ***:New bone(NB)formation and bone healing were successfully achieved,both radiologically and histologically,on demineralized cancellous bone graft seeded with *** were improved when BM-MSCs were associated with ***:This study demonstrates that repair of bone defects in a rabbit model can be achieved through bone grafting using BM-MSCs,implanted on a demineralized cancellous bone *** formation of NB was optimized when combined with the preservation of periosteum at the site of injury.

关键词： Bone defects bone marrow bone tissue engineering mesenchymal stem cells periosteum

Building the ARIMA Model for Forecasting the Production of Vietnam’s Coffee Export

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Journal of Applied Mathematics and Physics 2024年第4期12卷 1237-1246页

作者： Duy Quang Phung Quoc Thang Trinh Quang Truong Do Ngan Giang Nguyen Van Ha Nguyen Gia Khiem Ngo Thi Minh ngoc tran Faculty of Technology and Data Science Foreign Trade University Hanoi Vietnam School of Economics and International Business Foreign Trade University Hanoi Vietnam

Coffee is a significant industry, accounting for 3% of Vietnam’s GDP, with annual export turnover consistently exceeding USD 3 billion. Despite global economic challenges affecting purchasing power at various times, Vietnam’s coffee exports in December 2023 continued to surge, reaching the highest level in the past 9 months at 190,000 tons, a 59.3% increase compared to November 2023, but still a slight 3.5% decrease from the same period last year. The export turnover reached USD 538 million, a 51% increase from November 2023 and a 26.4% increase from the same period last year. Therefore, forecasting the coffee export volume holds significant importance for coffee producers nationwide. This research employs the Box-Jenkins method to construct an ARIMA model for forecasting Vietnam’s coffee export volume based on annual data published by the General Statistics Office. Results indicate that among the models considered, the ARIMA(1, 1, 2) model is the most suitable. The study also provides short-term forecasts for Vietnam’s coffee export volume. However, the current model is limited to forecasting and is not yet optimized, as the assumed linearity in the model is a simplification.

关键词： ARIMA Forecasting Coffee Export Volume Data Science

An improved CRNN for Vietnamese Identity Card Information Recognition

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Computer Systems Science & Engineering 2022年第2期40卷 539-555页

作者： Trinh Tan Dat Le tran Anh Dang Nguyen Nhat Truong Pham Cung Le Thien vu vu ngoc Thanh Sang Pham Thi vuong Pham The Bao Information Science Faculty Sai Gon UniversityHCM City700000Vietnam Faculty of Electrical&Electronics Engineering University of TechnologyHCM City700000Vietnam

This paper proposes an enhancement of an automatic text recognition system for extracting information from the front side of the Vietnamese citizen identity(CID)***,we apply Mask-RCNN to segment and align the CID card from the ***,we present two approaches to detect the CID card’s text lines using traditional image processing techniques compared to the EAST ***,we introduce a new end-to-end Convolutional Recurrent Neural Network(CRNN)model based on a combination of Connectionist Temporal Classification(CTC)and attention mechanism for Vietnamese text recognition by jointly train the CTC and attention objective functions *** length of the CTC’s output label sequence is applied to the attention-based decoder prediction to make the final label *** process helps to decrease irregular alignments and speed up the label sequence estimation during training and inference,instead of only relying on a data-driven attention-based encoder-decoder to estimate the label sequence in long *** may directly learn the proposed model from a sequence of words without detailed *** evaluate the proposed system using a real collected Vietnamese CID card dataset and find that our method provides a 4.28%in WER and outperforms the common techniques.

关键词： Vietnamese text recognition OCR CRNN BLSTM attention mechanism joint CTC-Attention

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

Complex Network Analysis of the Robustness of the Hanoi, Vietnam Bus Network

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Journal of Systems Science & Complexity 2019年第5期32卷 1251-1263页

作者： tran vu Hieu CHEONG Siew Ann BUI ngoc Dung Faculty of Information Technology University of Transport and CommunicationsHanoiVietnam Division of Physics and Applied Physics School of Physical and Mathematical SciencesNanyang Technological University21 Nanyang Link637371Singapore Faculty of Information Technology University of Transport and CommunicationsHanoiVietnam.

Many complex networks exist to facilitate the transport of material or information. In this capacity, the authors are often concerned with the continued flow of material or information when a fraction of the links in the complex network is disrupted. In other words, the authors are interested in the robustness of the complex network. In this paper, the authors survey measures of robustness like the average path length, the average clustering coefficient, the global efficiency, the size of largest cluster and use these to analyze the robustness of the bus network in Hanoi, Vietnam. The authors find that the bus network is robust against random failure but sensitive to targeted attack, in agreement with its scale-free character. By examining sharp drops in the average path length within the largest cluster of the Hanoi bus network under successive targeted attack, the authors identify five nodes whose loss lead to the fragmentation of the network into five or six disconnected clusters. These isolated clusters represent geographically the Central, Western, Southern, and Northwestern districts of Hanoi. Special considerations must therefore be given to these five nodes when planners wish to expand the bus network, or make it more robust.

关键词： Complex network hanoi bus network random failure robustness targeted attack

Kriging-based reliability analysis of the long-term stability of a deep driftconstructed in the Callovo-Oxfordian claystone

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第5期13卷 1033-1046页

作者： ngoc-Tuyen tran Duc-Phi Do Dashnor Hoxha Minh-ngoc vu Gilles Armand Univ.Orléans Univ.ToursINSA CVLLaméEA 7494France Andra R&D Division92298Chatenay-MalabryFrance

Callovo-Oxfordian(COx)claystone has been considered as a potential host rock for geological radioactive waste disposal in France(Cigéo project).During the exploitation phase(100 years),the stability of drifts(***/alveoli)within the disposal is assured by the liner,which includes two layers:concrete arch segment and compressible *** latter exhibits a significant deformation capacity(about 50%)under low stress(<3 MPa).Although the response of these underground structures can be governed by complex thermo-hydro-mechanical coupling,the creep behavior of COx claystone has been considered as the main factor controlling the increase of stress state in the concrete liner and hence the long-term stability of ***,by focusing only on the purely mechanical behavior,this study aims at investigating the uncertainty effect of the COx claystone time-dependent properties on the stability of an alveolus of Cigéo during the exploitation *** describe the creep behavior of COx claystone,we use Lemaitre’s viscoplastic model with three parameters whose uncertainties are identified from laboratory creep *** the reliability analysis,an extension of a well-known Kriging metamodeling technique is proposed to assess the exceedance probability of acceptable stress in the concrete liner of the *** open-source code Code_Aster is chosen for the direct numerical evaluations of the performance *** Kriging-based reliability analysis elucidates the effect of the uncertainty of COx claystone on the long-term stability of the concrete ***,the role of the compressible material layer between the concrete liner and the host rock is also highlighted.

关键词： Reliability analysis Kriging metamodeling Time-dependent behavior Compressible material Callovo-Oxfordian(COx)claystone Long-term stability

Effects of parental age on offspring growth and survival in both wild and domesticated strains of bighead catfish(Clarias macrocephalus Günther,1864)

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Aquaculture and Fisheries 2023年第2期8卷 141-147页

作者： Thuy Yen Duong Thet Su Win Thi ngoc tran Nguyen College of Aquaculture and Fisheries Can Tho UniversityCan Tho920000Viet Nam International Master Program in Aquaculture Course 4Can Tho UniversityCan Tho920000Viet Nam

Understanding the relationship between fish parental age and offspring performance over their life cycle is crucial for *** study investigates the effect of parental age for both 1-and 2-year-old fish on the growth and survival rates of their larval to grow-out stages for two wild and domesticated strains of bighead catfish(Clarias macrocephalus).Fish were sampled from the Vietnamese Mekong Delta where wild adult fish were collected from a conservation area in Ca Mau Province and domesticated fish were taken from a hatchery in Can *** offspring treatments of 1-and 2-year-old broodstock strains were reared for 3 successive periods:40 days for fingerling rearing in static tanks with water exchange,60 days for juveniles,and 90 days for grow-out in recirculating *** final weight of fish at 190 days varied from 96.7 to 144.7 *** growth of offspring was not affected by parental age(P>0.05),over the 3 rearing ***,the domesticated fish strain showed significantly better growth rates than the wild fish strain(P<0.05).Feed conversion ratios were comparable across fish *** rates did not differ at the fingerling(21.8%-36.4%)and juvenile(69.0%-73.3%)***,significant differences were found at the grow-out stage(69.3%-84.0%),with offspring from 2-year-old parents of both strains having greater survival ***,1-and 2-year-old fish appear to be suitable for bighead catfish breeders.

关键词： Parental age Clarias catfish Fish growth Strain evaluation Wild broodstock