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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

A comparative study on kinetics and dynamics of two dump truck lifting mechanisms using MATLAB simscape

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Theoretical & Applied Mechanics Letters 2024年第2期14卷 146-156页

作者： Thong Duc Hong Minh Quang Pham Son cong Tran Lam Quang Tran Truong Thanh nguyen Faculty of Transportation Engineering Ho Chi Minh City University of Technology(HCMUT)Ho Chi Minh City 700000Vietnam Vietnam National University Ho Chi Minh City(VNU-HCM) Ho Chi Minh City 700000Vietnam Industrial Maintenance Training Center Ho Chi Minh City University of Technology(HCMUT)Ho Chi Minh City 700000Vietnam

In this paper,two lifting mechanism models with opposing placements,which use the same hydraulic hoist model and have the same angle of 50°,have been *** mechanical and hydraulic simulation models are established using MATLAB Simscape to analyze their kinetics and dynamics in the lifting and holding *** simulation findings are compared to the analytical calculation results in the steady state,and both methods show good *** the early lifting stage,Model 1 produces greater force and discharges goods in the container faster than Model ***,Model 2 reaches a higher force and ejects goods from the container cleaner than its counterpart at the end lifting *** established simulation models can consider the effects of dynamic loads due to inertial moments and forces generated during the system *** is crucial in studying,designing,and optimizing the structure of hydraulic-mechanical systems.

关键词： Dump truck Lifting mechanism Hydraulic MATLAB Simscape Kinetic dynamic analysis

采石场粉尘和海砂混合物力学性能试验和数值研究

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岩土力学 2024年第9期45卷 2728-2740页

作者： tiep Pham Duc TU nguyen Van PHONG Pham Duc CHINH Mai Viet PHONG nguyen Viet 越南勒奎东技术大学特殊工程技术研究所河内越南

越南等发展中国家的道路基础设施建设需要大量天然砂。河砂日益紧缺,其供应量将持续下降。因此,建筑行业必须实施可持续发展战略,将废弃材料与各种可利用资源相结合,以有效应对这一严峻形势。本研究的目的是测试采石场粉尘和海砂混合物... 详细信息

越南等发展中国家的道路基础设施建设需要大量天然砂。河砂日益紧缺,其供应量将持续下降。因此,建筑行业必须实施可持续发展战略,将废弃材料与各种可利用资源相结合,以有效应对这一严峻形势。本研究的目的是测试采石场粉尘和海砂混合物的力学性能,并评估其在高速公路路基层中的潜在应用。进行了一系列试验,包括材料的含水率、相对密度、休止角测试和三轴试验,以研究不同配比下混合物的组成。结合Plaxis土工试验中的校准进行了广泛的参数研究,得出了割线模量E_(50)和围压曲线。根据加州承载比CBR对公路路基层所用材料的评估结果,证明海砂和采石场粉尘混合物具有适当性能,可用于公路路基的建设。

关键词：采石场粉尘海砂土工试验模块固结试验三轴试验路基层公路加州承载比

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

A Study on Optimizing the Double-Spine Type Flow Path Design for the Overhead Transportation System Using Tabu Search Algorithm

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Intelligent Automation & Soft Computing 2024年第2期39卷 255-279页

作者： nguyen Huu Loc Khuu Thuy Duy Truong Quoc Dien Le Tran Thanh cong Vu Hoa Binh Tran Tuong Quan Vo Department of Mechatronics Faculty of Mechanical EngineeringHo Chi Minh City University of Technology(HCMUT)Ho Chi Minh CityVietnam Bach Khoa Research Center for Manufacturing Engineering Ho Chi Minh City University of Technology(HCMUT)Ho Chi Minh CityVietnam VietnamNational University Ho ChiMinh City Ho ChiMinh CityVietnam

Optimizing Flow Path Design(FPD)is a popular research area in transportation system design,but its application to Overhead Transportation Systems(OTSs)has been *** study focuses on optimizing a double-spine flow path design for OTSs with 10 stations by minimizing the total travel distance for both loaded and empty *** employ transportation methods,specifically the North-West Corner and Stepping-Stone methods,to determine empty vehicle travel ***,the Tabu Search(TS)algorithm is applied to branch the 10 stations into two main layout *** results obtained from our proposed method demonstrate a reduction in the objective function value compared to the initial feasible ***,we explore howchanges in the parameters of the TS algorithm affect the optimal *** validate the feasibility of our approach by comparing it with relevant literature and conducting additional tests on layouts with 20 and 30 stations.

关键词： Overhead transportation systems tabu search double-spine layout transportationmethod empty travel flow path design

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

Electronic Band Structure of Carbon Nanotubes with Kekule Structure

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Chinese Physics Letters 2013年第9期30卷 97-100页

作者： nguyen Ngoc Hieu Le cong Nhan Center of Research and Development Duy Tan UniversityK7/25 Quang TrungDa NangViet Nam Department of Environmental Science Saigon University273 An Duong VuongHo Chi Minh cityViet Nam

Electronic band structure of carbon nanotubes with the Kekule structure is studied by the tight-binding *** give a complete geometrical approach to structural properties of carbon nanotubes with bond alternation,including chiral and achiral *** the Kekule is introduced,all carbon nanotubes become semiconducting with a small band gap at the Fermi *** band gap of the carbon nanotubes depends only on the difference between C–C bond lengths or the resonance integrals.

关键词： carbon structure Fermi

Heat Transfer and Fluid Flow of Nanofluids in Laminar Radial Flow Cooling Systems

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Journal of Thermal Science 2005年第4期14卷 362-367页

作者： Gilles ROY Samy Joseph PALM cong Tam nguyen Faculty of Engineering Universite de MonctonMonctonNBCanadaElA 3E9

Nanofluids are considered as interesting alternatives to conventional coolants. It is well known that traditional fluids have limited heat transfer capabilities when compared to common metals. It is therefore quite conceivable that a small amount of extremely fine metallic particles placed in suspension in traditional fluids will considerably increase their heat transfer performances. A numerical investigation into the heat transfer enhancement capabilities of coolants with suspended metallic nanoparticles inside a radial, laminar flow cooling configuration is presented. Temperature dependant nanofluid properties are evaluated from experimental data available in recent literature. Results indicate that considerable heat transfer increases are possible with the use of relatively small volume fractions of nanoparticles. Generally, however, these are accompanied by considerable increases in wall shear-stress. Results also show that predictions obtained with temperature variable nanofluid properties yield greater heat transfer capabilities and lower wall shear stresses when compared to predictions using constant properties.

关键词： nanofluids nanoparticles heat transfer laminar flow confined radial flow.

Thermal Performance Prediction in the Air Gap of a Rotor-Stator Configuration: Effects of Numerical Models

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Journal of Thermal Science 2020年第1期29卷 206-218页

作者： DANG Dinh-Dong PHAM Xuan-Tan nguyen Chi-cong Department of Mechanical Engineering École de technologie supérieureMontrealQCCanada Hydro-Québec’s research institute VarennesQCCanada

This study is dedicated to a numerical investigation of convective heat transfer on the rotor surfaces of a rotor-stator configuration that is typically found in large *** computational fluid dynamics calculations with two turbulence modelling approaches are used to predict the flow structure and heat transfer in the air gap of the rotor-stator *** steady state mixing plane approach is employed at the interface to couple the rotor and stator *** show that the location of mixing plane interface in the air gap plays an important role in the prediction of heat transfer on the pole ***,it is indicated that the prediction of temperature distribution on the pole face is greatly affected by the turbulence models ***,through a comparison between the pure convective and conjugate heat transfer methodologies,it is shown that the inclusion of solid domain into the numerical model significantly improves the thermal prediction of the solid components of the machine.

关键词： hydro-generators electrical cooling mixing plane windage loss conjugate heat transfer