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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

Velocity equation for grenades while impacting on dry sand media

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Defence Technology（防务技术） 2024年第5期35卷 168-173页

作者： Martin Macko xuan Son Bui Kongsathit Phanthavong Duc Hung pham Van Gion Do Van Minh Do Jiri Skala University of Defence BrnoCzech Republic Le Quy Don Technical University Ha NoiViet Nam

This paper deals with the collision of sphere shape grenades with sand *** central issue of the article is the establishing of an empirical velocity equation of the grenade while impacting on sand that is used to solve motion equations of the mechanical mechanism inside the impact grenade *** paper focuses on impact velocities that are lower than 5 m s^(-1).An experiment was conducted to study the velocity of the grenade while impacting on dry sand.A high-speed camera video was used to capture the grenade *** grenade velocity in the impact process was generated from these video *** types of fitting curves are used to regress the velocity equation of the grenade while interacting with the sand media and the best-fitting model is *** result shows the regression curve has a high correlation with the experiment data for grenade velocities below 5 m s^(-1).The received regression equation is useful for analyzing the working ability of the inertial mechanism inside the impact grenade or analyzing and choosing the appropriate parameters of each part in the inertial mechanism to meet the required characteristics of the mechanism.

关键词： Dynamic response Impact velocity Impact grenade Low-velocity impact

Generating highly active oxide-phosphide heterostructure through interfacial engineering to break the energy scaling relation toward urea-assisted natural seawater electrolysis

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Journal of Energy Chemistry 2024年第10期97卷 687-699,I0014页

作者： Ngoc Quang Tran Nam Hoang Vu Jianmin Yu Khanh Vy pham Nguyen Thuy Tien Nguyen Tran Thuy-Kieu truong Lishan Peng Thi Anh Le Yoshiyuki Kawazoe Center for Innovative Materials and Architectures Ho Chi Minh City 700000Vietnam Vietnam National University Ho Chi Minh City 700000Vietnam Faculty of Materials Science and Technology University of ScienceHo Chi Minh City 700000Vietnam Department of Mechanical Engineering Hanbat National University(HBNU)Daejeon 34158Republic of Korea Key Laboratory of Rare Earths Ganjiang Innovation AcademyChinese Academy of SciencesGanzhou 341119JiangxiChina School of Chemical Engineering-Hanoi University of Science and Technology Hanoi 10000Vietnam New Industry Creation Hatchery Center Tohoku UniversitySendai 980-8579Japan

Urea-assisted natural seawater electrolysis is an emerging technology that is effective for grid-scale carbon-neutral hydrogen mass production yet *** scaling relations is an effective strategy to break through the bottleneck of natural seawater ***,by DFT calculation,we demonstrated that the interface boundaries between Ni_(2)P and MoO_(2) play an essential role in the selfrelaxation of the Ni-O interfacial bond,effectively modulating a coordination number of intermediates to control independently their adsorption-free energy,thus circumventing the adsorption-energy scaling *** this conceptual model,a well-defined 3D F-doped Ni_(2)P-MoO_(2) heterostructure microrod array was rationally designed via an interfacial engineering strategy toward urea-assisted natural seawater *** a result,the F-Ni_(2)P-MoO_(2) exhibits eminently active and durable bifunctional catalysts for both HER and OER in acid,alkaline,and alkaline sea water-based *** in-situ analysis,we found that a thin amorphous layer of NiOOH,which is evolved from the Ni_(2)P during anodic reaction,is real catalytic active sites for the OER and UOR ***,such electrode-assembled urea-assisted natural seawater electrolyzer requires low voltages of 1.29 and 1.75 V to drive 10 and600 mA cm^(-2)and demonstrates superior durability by operating continuously for 100 h at 100 mA cm^(-2),beyond commercial Pt/C||RuO_(2) and most previous reports.

关键词： Interfacial engineering Break scaling relationships Doping Natural seawater splitting Urea electrolysis

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

ON BOUNDEDNESS PROPERTY OF SINGULAR INTEGRAL OPERATORS ASSOCIATED TO A SCHRODINGER OPERATOR IN A GENERALIZED MORREY SPACE AND APPLICATIONS

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Acta Mathematica Scientia 2020年第5期40卷 1171-1184页

作者： xuan truong LE Thanh Nhan NGUYEN Ngoc Trong NGUYEN Division of Computational Mathematics and Engineering Institute for Computational ScienceTon Due Thang UniversityHo Chi Minh CityVietnam Faculty of Mathematics and Statistics Ton Due Thang UniversityHo Chi Minh CityVietnam Department of Mathematics Ho Chi Minh City University of EducationHo Chi Minh CityVietnam Department of Primary Education Ho Chi Minh City University of EducationHo Chi Minh CityVietnam

In this paper,we provide the boundedness property of the Riesz transforms associated to the Schrodinger operator■=-Δ+V in a new weighted Morrey space which is the generalized version of many previous Morrey type *** additional potential V considered in this paper is a non-negative function satisfying the suitable reverse Holder's *** results are new and general in many cases of *** an application of the boundedness property of these singular integral operators,we obtain some regularity results of solutions to Schrodinger equations in the new Morrey space.

关键词： weighted Morrey spaces Schodinger operator riesz transforms Regularity estima tes

A New Species of Rhacophorus(Amphibia:Anura:Rhacophoridae)from Vietnam

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Asian Herpetological Research 2017年第4期18卷 221-234页

作者： Tao Thien NGUYEN Cuong The pham truong Quang NGUYEN Hoa Thi NINH Thomas ZIEGLER Vietnam National Museum of Nature Vietnam Academy of Science and Technology18 Hoang Quoc Viet RoadHanoiVietnam Institute of Ecology and Biological Resources Vietnam Academy of Science and Technology18 Hoang Quoc VietHanoiVietnam Graduate University of Science and Technology Vietnam Academy of Science and Technology18 Hoang Quoc VietCau GiayHanoiVietnam The Kyoto University Museum Kyoto UniversityYoshida HonmachiSakyokuKyoto 606-8501Japan Hanoi National University of Education 136 Xuan ThuyCau GiayHanoiVietnam AG Zoologischer Garten K6ln Riehler Strasse 173D-50735 CologneGermany Institute of Zoology University of CologneZiilpicherStrafle 47bD-50674 CologneGermany

We describe a new species of Rhacophorus based on two adult specimens collected from Hoa Binh Province, northern Vietnam. Rhacophorus hoabinhensis sp. nov. is distinguishable from its congeners on the basis of a combination of the following morphological characters： size small （SVL 31.1-32.5 mm in males）; head slightly longer than wide; vomerine teeth absent; snout short （SNL/SVL 0.16）; dorsal skin smooth; forearm and tarsus with dermal fringes; dermal appendage at vent present; webbing formula on fingers I12/3-12/3II1-2III1-1IV and on toes I3/4-1II1/2- IIII1/2-1IVI-1/2V; dorsal surface grey yellow with brown spots; lower jaw region dark grey, throat, chest and belly cream; anterior and posterior thighs, as well as ventral surface of tibia orange. The interspecific uncorrected genetic distances （16S rRNA gene） between the new species from Hoa Binh and other analyzed congeners varied from 9.8% to 17.4%. In the phylogenetic analyses, the new species revealed to be a representative of Rhacophorus and was nested within the R. hoanglienensis-orlovi species group.

关键词： Rhacophorus hoabinhensis sp.nov karst forest molecular phylogeny taxonomy Hoa Binh Province

Evaluation of five gridded rainfall datasets in simulating streamflow in the upper Dong Nai river basin,Vietnam

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International Journal of Digital Earth 2019年第3期12卷 311-327页

作者： pham Thi Thao Nhi Dao Nguyen Khoi Nguyen xuan Hoan Institute of Research and Development Duy Tan UniversityDa NangVietnam Institute for Computational Science and Technology Tan Hiep Chanh WardDistrict 12Ho Chi Minh CityVietnam Faculty of Environment University of ScienceVietnam National University Ho Chi Minh City227 Nguyen Van Cu StreetDistrict 5Ho Chi Minh CityVietnam Ho Chi Minh City University of Food Industry 140 Le Trong Tan StreetTan Phu DistrictHo Chi Minh CityVietnam

Rainfall data with an appropriate spatial resolution is a key input to hydrological ***,networks of rain gauges are often sparsely and unevenly distributed in large catchments,especially in developing ***-resolution rainfall datasets,such as the Asian Precipitation Highly Resolved Observational Data Integration Towards Evaluation of Water Resources(APHRODITE),the Climate Forecast System Reanalysis(CFSR),the Climatic Research Unit Time Series(CRUTS),the Global Precipitation Climatology Centre(GPCC)and the Tropical Rainfall Measuring Mission(TRMM),have become available to overcome such *** objective of this study was to evaluate the impacts of four land-based rainfall products(APHRODITE,CFSR,CRU-TS,and GPCC)and a satellite-based rainfall product(TRMM)on streamflow of the upper catchment of Tri An reservoir in Vietnam using the Hydrological Modeling System(HEC-HMS).In addition,the available rain gauges data were used for comparison *** indicates that the TRMM and GPCC data show their best match to rain gauges data in simulating the streamflow in the period 1999–***,the results indicate that the TRMM and GPCC data could be alternative solutions.

关键词： APHRODITE CFSR CRU-TS GPCC TRMM rainfall streamflow HEC-HMS model

Incorporation of hydroxyapatite in crosslinked gelatin/chitosan/poly(vinyl alcohol) hybrids utilizing as reinforced composite sponges, and their water absorption ability

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Progress in Natural Science:Materials International 2021年第5期31卷 664-671页

作者： Thi Sinh Vo Tran Thi Bich Chau Vo truong Sinh Nguyen Nhan Duy pham School of Mechanical Engineering Sungkyunkwan University Department of Chemistry Memorial University of Newfoundland Department of Industrial Management Can Tho University

The crosslinked gelatin/chitosan/poly(vinyl alcohol)/hydroxyapatite(GEL/CTS/PVA/HAp, GCPH) sponges were fabricated by a freeze-drying method to yield the reinforced composite sponges with proper features. The porosity value and pore size of the crosslinked GCPH sponges reached ～80% and 50–100 μm, respectively, which can be an appropriate range to allow cells to migrate into the reinforced composite sponges in the tissue engineering technology. Besides, the proper bonding presence between HAp particles and the crosslinked polymeric matrix or the crosslinked network formation between the polymers were also proved through fourier-transform infrared spectroscopy(FTIR), X-ray diffraction(XRD) and thermal gravimetric(TG/DTG) analysis. Owing to incorporation of HAp particles and good distribution of HAp particles inside the crosslinked polymeric matrix, their mechanical properties were improved through the determination of compression tests. Concomitantly, their water absorption ability reached effectively in both the distilled water and Na Cl solution, and their recovery also maintained well for 10 absorbing–squeezing cycles to be considered as an effective reusability for the crosslinked sponge ***, the crosslinked GCPH sponge prepared in the present study can become a potential candidate to apply especially in the biomedical/medical applications and tissue engineering technology.

关键词： Reinforced composite sponge Gelatin Chitosan Poly(vinyl alcohol) Hydroxyapatite Water absorption ability Reusability

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