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Transient response of doubly-curved bio-inspired composite shells resting on viscoelastic foundation subject to blast load using improved first-order shear theory and isogeometric approach

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Defence Technology（防务技术） 2024年第8期38卷 171-193页

作者： Thuy Tran Thi Thu Tu nguyen anh Hue nguyen Thi hong nguyen Thi School of Mechanical and Automotive Engineering Hanoi University of IndustryHanoiViet Nam Faculty of Technical Fundamental University of Transport TechnologyHanoiViet Nam Faculty of Mechanical Engineering Thuyloi University175 Tay SonDong DaHanoiViet Nam

Investigating natural-inspired applications is a perennially appealing subject for scientists. The current increase in the speed of natural-origin structure growth may be linked to their superior mechanical properties and environmental resilience. Biological composite structures with helicoidal schemes and designs have remarkable capacities to absorb impact energy and withstand damage. However, there is a dearth of extensive study on the influence of fiber redirection and reorientation inside the matrix of a helicoid structure on its mechanical performance and reactivity. The present study aimed to explore the static and transient responses of a bio-inspired helicoid laminated composite(B-iHLC) shell under the influence of an explosive load using an isomorphic method. The structural integrity of the shell is maintained by a viscoelastic basis known as the Pasternak foundation, which encompasses two coefficients of stiffness and one coefficient of damping. The equilibrium equations governing shell dynamics are obtained by using Hamilton's principle and including the modified first-order shear theory,therefore obviating the need to employ a shear correction factor. The paper's model and approach are validated by doing numerical comparisons with respected publications. The findings of this study may be used in the construction of military and civilian infrastructure in situations when the structure is subjected to severe stresses that might potentially result in catastrophic collapse. The findings of this paper serve as the foundation for several other issues, including geometric optimization and the dynamic response of similar mechanical structures.

关键词： Blast load Modified first-order shear theory Biological composite structures

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

Quadruple[6]Helicene Featuring Pyrene Core:Unraveling Contorted Aromatic Core with Larger Effective Conjugation

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Precision Chemistry 2024年第9期2卷 488-494页

作者： Christopher Wallerius Otgonbayar Erdene-Ochir Eva Van Doeselar Ronald Alle anh Tu nguyen Marvin F.Schumacher Arne Lützen Klaus Meerholz Sai Ho Pun Department of Chemistry University of CologneCologne 50939Germany Kekulé-Institute of Organic Chemistry and Biochemistry University of BonnBonn 53121Germany Department of Chemistry Hong Kong University of Science and TechnologyClean Water BayHong KongChina

Multiple helicenes display distinct aromatic cores characterized by highly twisted rings that are shared or fused with constituent helicene *** these aromatic cores unlocks avenues for creating multiple helicenes with distinct properties and *** we report the synthesis of a quadruple[6]helicene featuring pyrene as the aromatic *** synthesis involved key steps of the annulativeπ-extension reaction and Scholl *** extending multiple helicenes along the axial direction,the degree of contortion of the aromatic core can be controlled from nearly flat to highly ***,quadruple[6]-helicene exhibits a significant red-shift of 0.49 eV compared to quadruple[4]-helicenes,of which the red-shift arises from bothπ-extension and augmented effective conjugation due to enhanced *** chemical calculations demonstrate that the degree of contortion in the pyrene core adeptly governs the energy levels of the HOMO and LUMO,which offers an alternative strategy beyond mere enlargement of theπ*** intriguing serendipitous finding reveals the formation of one-molecule-thick supramolecular homochiral nanosheets through selfinterlocking interactions of enantiomers in single crystals,a rare packing motif for multiple helicenes.

关键词： Helicenes Polycyclic aromatics Pyrene Core contortion Effective conjugation

Predicting 3D Radiotherapy Dose-Volume Based on Deep Learning

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Intelligent Automation & Soft Computing 2024年第2期39卷 319-335页

作者： Do Nang Toan lam Thanh Hien Ha Manh Toan nguyen Trong Vinh Pham Trung Hieu Institute of Information Technology Vietnam Academy of Science and TechnologyHanoi10072Vietnam Faculty of Information Technology Lac Hong UniversityBien HoaDong Nai76120Vietnam

Cancer is one of the most dangerous diseaseswith *** of the principal treatments is radiotherapy by using radiation beams to destroy cancer cells and this workflow requires a lot of experience and skill from doctors and *** our study,we focused on the 3D dose prediction problem in radiotherapy by applying the deeplearning approach to computed tomography(CT)images of cancer *** image data has more complex characteristics than normal image data,and this research aims to explore the effectiveness of data preprocessing and augmentation in the context of the 3D dose prediction *** proposed four strategies to clarify our hypothesis in different aspects of applying data preprocessing and *** strategies,we trained our custom convolutional neural network model which has a structure inspired by the U-net,and residual blocks were also applied to the *** output of the network is added with a rectified linear unit(Re-Lu)function for each pixel to ensure there are no negative values,which are absurd with radiation *** experiments were conducted on the dataset of the Open Knowledge-Based Planning Challenge which was collected from head and neck cancer patients treatedwith radiation *** results of four strategies showthat our hypothesis is rational by evaluating metrics in terms of the Dose-score and the Dose-volume histogram score(DVH-score).In the best training cases,the Dose-score is 3.08 and the DVH-score is *** addition,we also conducted a comparison with the results of another study in the same context of using the loss function.

关键词： CT image 3D dose prediction data preprocessing augmentation

Tuberculosis Diagnosis and Visualization with a Large Vietnamese X-Ray Image Dataset

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Intelligent Automation & Soft Computing 2024年第2期39卷 281-299页

作者： nguyen Trong Vinh lam Thanh Hien Ha Manh Toan Ngo Duc Vinh Do Nang Toan Faculty of Information Technology Lac Hong UniversityBien HoaDong Nai76120Vietnam Institute of Information Technology Vietnam Academy of Science and TechnologyHanoi10072Vietnam Faculty of Information Technology Hanoi University of IndustryHanoi11915Vietnam

Tuberculosis is a dangerous disease to human life,and we need a lot of attempts to stop and reverse ***,in theCOVID-19 pandemic,access to medical services for tuberculosis has become very *** late detection of tuberculosis could lead to danger to patient health,even *** one of the countries heavily affected by the COVID-19 pandemic,andmany residential areas as well as hospitals have to be isolated for a long *** demands a fast and effective tuberculosis diagnosis solution to deal with the difficulty of accessingmedical services,such as an automatic tuberculosis diagnosis *** our study,aiming to build that system,we were interested in the tuberculosis diagnosis problem from the chest X-ray images of Vietnamese *** chest X-ray image is an important data type to diagnose tuberculosis,and it has also received a lot of attention from deep learning *** paper proposed a novel method for tuberculosis diagnosis and visualization using the deeplearning approach with a large Vietnamese X-ray image *** detail,we designed our custom convolutional neural network for the X-ray image classification task and then analyzed the predicted result to provide visualization as a *** prove the performance of our network model,we conducted several experiments to compare it to another study and also to evaluate it with the dataset of this *** support the implementation,we built a specific annotation system for tuberculosis under the requirements of radiologists in the Vietnam National Lung Hospital.A large experiment dataset was also from this hospital,and most of this data was for training the convolutional neural network *** experiment results were evaluated regarding sensitivity,specificity,and *** achieved high scores with a training accuracy score of 0.99,and the testing specificity and sensitivity scores were over *** on the X-ray image classification result,we visualize pr

关键词： Tuberculosis classification Vietnamese chest X-ray deep learning

A Grey Simulation-Based Fuzzy Hierarchical Approach for Diagnosing Healthcare Service Quality

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Computers, Materials & Continua 2023年第2期74卷 3231-3248页

作者： Phi-Hung nguyen hong-anh Pham Faculty of Business FPT UniversityHanoi100000Vietnam

This study aims to assess and rank the service quality of the healthcare system utilizing a Fuzzy Analytical Hierarchical Process(Fuzzy AHP)andGreyRelationalAnalysis(Fuzzy GRA)*** this study,the six primary characteristics of healthcare service quality,comprising Tangibles(A),Healthcare Staff(B),Responsiveness(C),Relationships(D),Support Service(E),and Accessibility(F),are examined through a case study of 20 private and public hospitals in Hanoi,*** weighting results of Fuzzy AHP technique indicated that Responsiveness(C)has the highest ranking,followed by Relationships(D)and Healthcare Staff(B).Meanwhile,Tangibility has finally comprised the next priority for increasing satisfaction with the service quality in the healthcare ***,the highest service quality rankings are top 5 private hospitals via the Fuzzy GRA ***,this proposed approach may be applied to a complex decision-making process,which often makes sense with subjective data or imprecise information.

关键词： MCDM fuzzy sets AHP GRA healthcare Vietnam

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

Zirconium metal organic framework for design of tetragonal rare earth-doped zirconia nanoparticles

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Journal of Rare Earths 2019年第11期37卷 1230-1236页

作者： lam Thi Kieu Giang Lukasz Marciniak Krzysztof Kamil Zur Dinh Manh Tien nguyen Vu nguyen Thanh Binh Tran Kim anh Le Quoc Minh Institute of Materials Science Vietnam Academy of Science and Technology18 Hoang Quoc VietCau GiayHanoiViet Nam Graduate University of Science and Technology Vietnam Academy of Science and Technology18 Hoang Quoc VietCau GiayHanoiViet Nam Institute of Low Temperature and Structural Research Polish Academy of Sciencesul.Okolna 250-422 WroclawPoland Faculty of Mechanical Engineering Bialystok University of TechnologyWiejska 45C15-351 BialystokPoland Institute of Applied Physics and Scientific Instrument Vietnam Academy of Science and Technology18 Hoang Quoc VietCau GiayHanoiViet Nam Duy Tan University 03 Quang TrungDa NangViet Nam

Zirconium metal-organic frameworks ZrOBDC(where BDC=C6H4(COOH)2,terephthalic acid)doped and co-doped with rare earth ions Ln(ZrOBDC:Ln^3+,where Ln^3+=Eu3+and Tb^3+as well as Er^3+and Yb^3+)were used as precursors for the design of tetragonal rare earth doped zirconia nanoparticles(t-ZrO2:Ln^3+NPs)through annealing ***,characterization and luminescence properties of ZrOBDC:Ln^3+and ZrO2:Ln^3+NPs were *** as-obtained t-ZrO2:Ln^3+NPs have high purity with an average size of 20-30 *** luminescence spectra of ZrOBDC:Tb^3+and ZrOBDC:Eu3+display strong green and red emission at around 544 and 611 nm which correspond to 5D4→7F5 and 5D0→7F2 transitions of Tb^3+and Eu3+ions,*** green and red up-conversion emissions of ZrO2:Er^3+,Yb^3+NPs due to 2H11/2,4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of the Er^3+ions are observed under 976 nm laser excitation.

关键词： Zirconium Rare earth ZrOBDC ZrOBDC:Ln3+ ZrO2:Ln3+ Up-conversion

Comparative Study of Light Manipulation in Three-Level Systems Via Spontaneously Generated Coherence and Relative Phase of Laser Fields

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Communications in Theoretical Physics 2019年第8期71卷 947-954页

作者： nguyen Huy Bang Le nguyen Mai anh nguyen Tien Dung Le Van Doai Vinh University 182 Le Duan Street Vinh City Vietnam Nong lam University Ho Chi Minh City Vietnam (Received March 21 2019revised manuscript

We present a comparative study of the control of group velocity in three-level atomic systems including Λ-, Ladder-, and V-types via spontaneously generated coherence(SGC) and relative phase of laser *** the steady regime, expressions of group index are derived as an analytical function of controllable parameters related to SGC and relative *** is shown that the group velocity can be further slowed down or speeded up under SGC in which modifications of group velocity due to the SGC in Λ-and V-systems are stronger than that in *** particular, when interference strength of SGC p increases from 0.7 to 1.0, the light propagation is switched from superluminal to subluminal modes(for Λ-and Ladder-systems) or from subluminal to superluminal modes(for Vsystem).In the presence of relative phase, the group velocity changes between subluminal and superluminal modes with a period of 2π.In resonant region, the largest positive value of group index reaches at the relative phase φ=π while the largest negative value of group index reaches at φ= 0 and 2π for the Λ-and Ladder-systems, otherwise, for the V-system the largest positive group index occurs at φ= 0 and 2π, and the largest negative group index occurs at φ=π.

关键词： electromagnetically induced transparency spontaneously generated coherence group velocity