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Static analysis of corrugated panels using homogenization models and a cell-based smoothed mindlin plate element (CS-MIN3)

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Frontiers of Structural and Civil Engineering 2019年第2期13卷 251-272页

作者： Nhan NGUYEN-MINH Nha TRAN-VAN thang bui-xuan Trung NGUYEN-THOI Faculty of Applied Science Bach Khoa University (BKU)Ho Chi Minh CityVietnam Faculty of Mathematics and Computer Science Ho Chi Minh City University of Science (HCMUS)Ho Chi Minh CityVietnam Department of Mathematics L ouisiana State UniversityBaton RougeLA 70803USA Division of Computational Mathematics and Engineering Institute of Computational ScienceTon Due Thang UniversityHo Chi Minh CityVietnam Faculty of Civil Engineering Ton Due Thang UniversityHo Chi Minh CityVietnam

Homogenization is a promising approach to capture the behavior of complex structures like corrugated panels. It enables us to replace high-cost shell models with stiffness-equivalent orthotropic plate alternatives. Many homogenization models for corrugated panels of different shapes have been proposed. However, there is a lack of investigations for verifying their accuracy and reliability. In addition, in the recent trend of development of smoothed finite element methods, the cell-based smoothed three-node Mindlin plate element (CS-MIN3) based on the first-order shear deformation theory (FSDT) has been proposed and successfully applied to many analyses of plate and shell structures. Thus, this paper further extends the CS-MIN3 by integrating itself with homogenization models to give homogenization methods. In these methods, the equivalent extensional, bending, and transverse shear stiftriess components which constitute the equivalent orthotropic plate models are represented in explicit analytical expressions. Using the results of ANSYS and ABAQUS shell simulations as references, some numerical examples are conducted to verify the accuracy and reliability of the homogenization methods for static analyses of trapezoidally and sinusoidally corrugated panels.

关键词： homogenization corrugated panel asymptotic analysis smoothed finite element method (S-FEM) cell-based smoothed three-node Mindlin plate element (CS-MIN3)

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Exponentially Bounded C-semigroup and the Cauchy Initial Value Problems in Complete Random Normed Modules

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Acta Mathematica Sinica,English Series 2024年第9期40卷 2195-2212页

作者： Son TA CONG thang Dang HUNG Oanh Le THI Department of Mathematics University of ScienceVietnam National University 334 Nguyen TraiThanh XuanHanoiVietnam Faculty of Natural Sciences Hong Duc University565 Quang TrungDong VeThanh HoaVietnam

In this paper,the notion of C-semigroup of continuous module homomorphisms on a complete random normal(RN)module is introduced and *** existence and uniqueness of solution to the Cauchy problem with respect to exponen... 详细信息

关键词： C-semigroup Cauchy problem random normed modules L^(0)-Lipschitz

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Dry eye rate and its relationship with disease stage in patients with primary hypertension:a cross-sectional study in Vietnam

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International Journal of Ophthalmology(English edition) 2024年第4期17卷 653-658页

作者： Tran Tat thang Pham Hong Phuong Nguyen Sa Huynh Nguyen Trung Kien NguyenDuy Toan Nguyen Thi Thu Ha Le Ha Khoa Nguyen Huu Dung Thai Doan thang Le Viet thang Nghe An Eye Hospital Nghe An 43000Vietnam Nghe An Friendship General Hospital Nghe An 43000Vietnam Military Hospital 103 Ha Noi 100000Vietnam Vietnam Military Medical University Ha Noi 100000Vietnam Hanoi Medical University Ha Noi 100000Vietnam Bạch Mai Hospital Ha Noi 100000Vietnam TTH Vinh General Hospital Nghe An 100000Vietnam

AIM:To determine the dry eye(DE)rate and its relationship with disease stage in patients with primary ***:A cross-sectional study included 432 patients with primary hypertension(with an equal number of patients in each group:144 in stage Ⅰ,Ⅱ,and Ⅲ hypertension)and 144 healthy subjects as a control *** Ocular Surface Disease Index(OSDI)and Schirmer Ⅰ test without anesthetics were conducted on all 576 *** with OSDI scores<13 and Schirmer Ⅰ values equal to or under 10 mm were diagnosed with ***:The ratio of DE in hypertension patients was higher than in the control group(41.7%versus 18.8%;P<0.001).The proportion of patients with DE increased gradually according to the hypertension stage:27.1% in stage Ⅰ,40.3% in stage Ⅱ,and 57.6% in stage Ⅲ,P<***,duration of hypertension,plasma urea,creatinine,and high-sensitivity C-reactive protein(CRP-hs)levels in hypertension patients with DE were higher than those without DE,P<*** age,a long duration of hypertension,diabetes mellitus,elevated plasma creatinine,and CRP-hs levels were independent factors associated with DE in primary hypertension patients,P<***:DE is a common disorder associated with advanced age,a long duration of hypertension,diabetes mellitus,elevated plasma CRP-hs,and creatinine levels in patients with primary hypertension.

关键词： primary hypertension dry eye stage of hypertension plasma creatinine

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Aggregation-induced emission polymers via reversible-deactivation radical polymerization Special Collection:Distinguished Australian Researchers

Aggregate

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Aggregate 2024年第1期5卷 16-46页

作者： Nicholas Kai Shiang Teo Bo Fan Aditya Ardana San H.thang School of Chemistry Monash UniversityClaytonVictoriaAustralia

Aggregation-induced emission(AIE)is a unique phenomenon whereby aggregation of molecules induces fluorescence emission as opposed to the more commonly known aggregation-caused quenching(ACQ).AIE has the potential to be utilized in the large-scale production of AIE-active polymeric materials because of their wide range of practical applications such as stimuli-responsive sensors,biological imaging agents,and drug delivery *** is evident from the increasing number of publications over the years since AIE was first *** addition,the evergrowing interest in this field has led many researchers around the world to develop new and creative methods in the design of monomers,initiators and crosslinkers,with the goal of broadening the scope and utility of AIE *** of the most promising approaches to the design and synthesis of AIE polymers is the use of the reversible-deactivation radical polymerization(RDRP)techniques,which enabled the production of well-controlled AIE materials that are often difficult to achieve by other *** this review,a summary of some recent works that utilize RDRP for AIE polymer design and synthesis is presented,including(i)the design of AIE-related monomers,initiators/crosslinkers;the achievements in preparation of AIE polymers using(ii)reversible addition–fragmentation chain transfer(RAFT)technique;(iii)atom transfer radical polymerization(ATRP)technique;(iv)other techniques such as Cu(0)-RDRP technique and nitroxide-mediated polymerization(NMP)technique;(v)the possible applications of these AIE polymers,and finally(vi)a summary/perspective and the future direction of AIE polymers.

关键词： aggregation-induced emission atom transfer radical polymerization nitroxide-mediated polymerization reversible addition–fragmentation chain transfer reversible-deactivation radical polymerization

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循环三轴试验加载频率和压实度对重塑砂土液化行为的影响

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岩土力学 2024年第6期45卷 1813-1823页

作者： THUY Do Van TIEP Pham Duc HIEU Nguyen Van thang Pham Cao 勒奎东技术大学特殊工程技术研究所越南河内越南航空科技协会越南河内

通过对各向同性固结不排水试样进行循环三轴试验,研究了饱和重塑砂土的液化行为。试验采用恒幅正弦载荷,通过测量剪切模量、阻尼比、轴向应变和超孔隙水压力比的变化,评估了加载频率(分别为0.1、0.5、1.0 Hz)和压实度(分别为0.95、0.90... 详细信息

通过对各向同性固结不排水试样进行循环三轴试验,研究了饱和重塑砂土的液化行为。试验采用恒幅正弦载荷,通过测量剪切模量、阻尼比、轴向应变和超孔隙水压力比的变化,评估了加载频率(分别为0.1、0.5、1.0 Hz)和压实度(分别为0.95、0.90和0.80)对砂土液化行为的影响。试验结果表明,对于压实度为0.95的砂样,在5000次加载循环中,0.1 Hz的加载频率对液化过程影响甚微;而对于压实度为0.90和0.80的砂样,此频率的影响显著。对于压实度为0.80的砂样,当频率增加到0.5 Hz时几乎一加载就直接发生液化。这表明增加加载频率会加快液化速度,而增加压实度则会减慢液化速度。因此,通过一系列的试验可以模拟现场砂土在不同频率下的动荷载条件。试验结果表明,饱和砂土的液化行为由以下因素决定:(1)试样的压实度越低,液化越容易发生;(2)加载频率越高,液化越容易发生;(3)循环轴向应变越大,发生液化所需的循环次数越少;(4)超孔隙水压力随加载循环次数增加,直至试样完全液化。

关键词：液化行为加载频率循环三轴试验饱和固结不排水条件重塑砂土压实度

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Genetic diversity in two threatened species in Vietnam:Taxus chinensis and Taxus wallichiana

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Journal of Forestry Research 2017年第2期28卷 265-272页

作者： Dinh Duy Vu Thi Tuyet xuan bui Minh Tam Nguyen Dinh Giap Vu Minh Duc Nguyen Van thang bui Xiaohua Huang Yi Zhang College of Forestry Northwest A&F UniversityYangling 712100ShaanxiPeople's Republic of China Vietnam National Museum of Nature Vietnam Academy of Science and Technology(VAST)18 Hoang Quoc VietCau GiayHanoiVietnam Institute of Ecology and Biological Resource(VAST) 18 Hoang Quoc VietCau GiayHanoiVietnam Institute of Natural Products Chemistry(VAST) 18 Hoang Quoc VietCau GiayHanoiVietnam Institute of Forest Biotechnology Vietnam Forestry UniversityXuan MaiChuong MyHanoiVietnam

Taxus chinensis and T. wallichiana in have been threatened in their distribution areas in recent decades because of their over-exploitation and reduction and destruction of native habitats. Determining the genetic diversity in populations of the two species will provide guidelines for their protection and preservation. Two hundred and fifteen trees from six populations of T. chinensis and150 sampled trees of T. wallichiana were sampled. Six microsatellite primer pairs selected from 16 primer pairs were used to investigate genetic variation at the population and species levels. Five yielded polymorphic alleles, and among the 13 putative alleles amplified, 11 were polymorphic（accounting for 76.33 %）.Shannon＇s information index（I） and percentage of polymorphic bands（PPB）（I = 0.202 and PPB = 67.22 % for T. chinensis; I = 0.217 and PPB = 65.03 % for T. wallichiana）. Both species had low levels of genetic diversity（mean Ho= 0.107, He= 0.121 for T. chinensis; Ho= 0.095, He= 0.109 for T. wallichiana）. Genetic differentiation among populations was higher（FST= 0.189） for T. chinensis and lower（0.156） for ***, indicating limited gene flow（Nm） among populations for T. chinensis（0.68） and T. wallichiana（0.65）.Variation among individuals of T. chinensis was 63.59 and73.12 % for T. wallichiana. Thus, the threatened status of the two conifers is related to a lack of genetic diversity. All populations are isolated in small forest remnants. An ex situ conservation site should be established with a new population for these species that comprises all the genetic groups for the best chance to improve their fitness under environmental stresses.

关键词： Taxus populations alleles polymorphic microsatellite Vietnam primer accounting putative destruction

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越南杧果产业发展趋势预测与启示

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中国南方果树 2024年第4期53卷 251-258,264页

作者：邓志新 VU Thanh Hai 刘洋铭 PHAM Quang thang 西南林业大学绿色发展研究院昆明650224 越南国立农业大学越南河内云南机电职业技术学院昆明650201 越南有机农业工艺研究院越南河内

近年来,中国已成为越南杧果出口主要目标市场。本文以越南杧果产业为研究对象,运用“全程质量支撑技术体系”理论,分析其杧果产业发展现状及关键技术约束集,预测越南杧果产业发展趋势,推测其对中国杧果产业近期、中期、长期的影响,提出... 详细信息

近年来,中国已成为越南杧果出口主要目标市场。本文以越南杧果产业为研究对象,运用“全程质量支撑技术体系”理论,分析其杧果产业发展现状及关键技术约束集,预测越南杧果产业发展趋势,推测其对中国杧果产业近期、中期、长期的影响,提出我国应对策略建议,助力我国杧果产业发展。

关键词：越南杧果产业全程质量支撑技术体系中国大青杧

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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

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Predicting rock size distribution in mine blasting using various novel soft computing models based on meta-heuristics and machine learning algorithms

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Geoscience Frontiers 2021年第3期12卷 458-472页

作者： Chengyu Xie Hoang Nguyen xuan-Nam bui Yosoon Choi Jian Zhou Thao Nguyen-Trang School of Environment and Resources Xiangtan UniversityXiangtan 411105China Institute of Research and Development Duy Tan UniversityDa Nang 550000Viet Nam Department of Surface Mining Mining FacultyHanoi University of Mining and Geology18 Pho VienDuc Thang wardBac Tu Liem districtHanoi 100000Viet Nam Center for Mining Electro-Mechanical researchHanoi University of Mining and Geology18 Pho VienDuc Thang wardBac Tu Liem districtHanoi 100000Viet Nam Department of Energy Resources Engineering Pukyong National UniversityBusan 48513Republic of Korea School of Resources and Safety Engineering Central South UniversityChangsha 410083HunanChina Division of Computational Mathematics and Engineering Institute for Computational ScienceTon Duc Thang UniversityHo Chi Minh City 700000Viet Nam Faculty of Mathematics and Statistics Ton Duc Thang UniversityHo Chi Minh City 700000Viet Nam

Blasting is well-known as an effective method for fragmenting or moving rock in open-pit *** evaluate the quality of blasting,the size of rock distribution is used as a critical criterion in blasting operations.A high percentage of oversized rocks generated by blasting operations can lead to economic and environmental ***,this study proposed four novel intelligent models to predict the size of rock distribution in mine blasting in order to optimize blasting parameters,as well as the efficiency of blasting operation in open ***,a nature-inspired algorithm(i.e.,firefly algorithm-FFA)and different machine learning algorithms(i.e.,gradient boosting machine(GBM),support vector machine(SVM),Gaussian process(GP),and artificial neural network(ANN))were combined for this aim,abbreviated as FFA-GBM,FFA-SVM,FFA-GP,and FFA-ANN,***,predicted results from the abovementioned models were compared with each other using three statistical indicators(e.g.,mean absolute error,root-mean-squared error,and correlation coefficient)and color intensity *** developing and simulating the size of rock in blasting operations,136 blasting events with their images were collected and analyzed by the Split-Desktop *** which,111 events were randomly selected for the development and optimization of the ***,the remaining 25 blasting events were applied to confirm the accuracy of the proposed ***,blast design parameters were regarded as input variables to predict the size of rock in blasting ***,the obtained results revealed that the FFA is a robust optimization algorithm for estimating rock fragmentation in bench *** the models developed in this study,FFA-GBM provided the highest accuracy in predicting the size of fragmented *** other techniques(i.e.,FFA-SVM,FFA-GP,and FFA-ANN)yielded lower computational stability and ***,the FFA-GBM model can be used as a powerful

关键词： Mine blasting Rock fragmentation Artificial intelligence Hybrid model Gradient boosting machine Meta-heuristic algorithm

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Hydrodynamics and heat transfer of gas-solid two-phase mixtures flowing through packed beds——a review

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Progress in Natural Science:Materials International 2008年第10期18卷 1185-1196页

作者： Ngoc thang Cong Institute of Particle Science & Engineering University of LeedsClarendon RoadLeeds LS2 9JTUK

Flow of a gas-solid two-phase mixture through a packed bed is relevant to a number of industrial processes such as heat recovery and filtration of dusty flue gases,iron making in shaft reactors,gas purification,and sorption enhanced reaction *** spite of the industrial relevance,little work has been reported in the *** limited amount of research work has mainly addressed the mac- roscopic hydrodynamics in terms of pressure drop and solids hold-ups at the ambient *** little is done,until fairly recent, on solids motion at the single particle level,hydrodynamics at elevated temperatures and heat *** paper reviews the recent development in the field including both the hydrodynamics and heat transfer of gas-solid two-phase mixtures flowing through packed beds,which is believed to represent the state-of-the-art in the *** review is not aimed to be exhaustive but rather focused on our own work carried out over the past few years in the Institute of Particle Science & Engineering at the University of *** some of our results are compared with that of other groups.

关键词： Gas-solid two-phase flow Hydrodynamics Heat transfer PEPT Euler-Euler multi-fluid model

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