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Damage detection in steel plates using feed-forward neural network coupled with hybrid particle swarm optimization and gravitational search algorithm

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2021年第6期22卷 467-480页

作者： Long Viet HO Duong Huong NGUYEN Guido de ROECK thanh bu-tien Magd Abdel WAHAB Soete Laboratory Department of Electrical EnergyMetalsMechanical Constructions and SystemsFaculty of Engineering and ArchitectureGhent UniversityGent 9000Belgium Department of Bridge and Tunnel Engineering Faculty of Civil EngineeringUniversity of Transport and CommunicationsHo Chi Minh 700000Vietnam Department of Bridge and Tunnel Engineering Faculty of Bridge and RoadNational University of Civil EngineeringHanoiVietnam Department of Civil Engineering Structural MechanicsKatholieke Universiteit LeuvenB-3001 LeuvenBelgium Department of Bridge and Tunnel Engineering Faculty of Civil EngineeringUniversity of Transport and CommunicationsHanoiVietnam Division of Computational Mechanics Ton Due Thang UniversityHo Chi Minh CityVietnam Faculty of Civil Engineering Ton Due Thang UniversityHo Chi Minh CityVietnam

Over recent decades,the artificial neural networks(ANNs)have been applied as an effective approach for detecting damage in construction ***,to achieve a superior result of defect identification,they have to overcome some shortcomings,for instance slow convergence or stagnancy in local ***,optimization algorithms with a global search ability are used to enhance ANNs,*** increase the rate of convergence and to reach a global *** paper introduces a two-stage approach for failure identification in a steel *** the first step,the presence of defects and their positions are identified by modal *** the second step,a feedforward neural network,improved by a hybrid particle swarm optimization and gravitational search algorithm,namely FNN-PSOGSA,is used to quantify the severity of *** element(FE)models of the beam for two damage scenarios are used to certify the accuracy and reliability of the proposed *** comparison,a traditional ANN is also used to estimate the severity of the *** obtained results prove that the proposed approach can be used effectively for damage detection and quantification.

关键词： Feedforward neural network-particle swarm optimization and gravitational search algorithm(FNN-PSOGSA) Modal damage indices Damage detection Hybrid algorithm PSOGSA

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Spatio-temporal changes of underground coal fires during 2008-2016 in Khanh Hoa coal field(North-east of Viet Nam) using Landsat time-series data

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Journal of Mountain Science 2018年第12期15卷 2703-2720页

作者： Tuyen Danh VU thanh tien NGUYEN Department of Training Hanoi University of Natural Resources and Environment Faculty of Surveying Mapping and Geographic Information Hanoi University of Natural Resources and Environment

Underground coal fires are one of the most common and serious geohazards in most coal producing countries in the world. Monitoring their spatio-temporal changes plays an important role in controlling and preventing the effects of coal fires, and their environmental impact. In this study, the spatio-temporal changes of underground coal fires in Khanh Hoa coal field(North-East of Viet Nam) were analyzed using Landsat time-series data during the 2008-2016 period. Based on land surface temperatures retrieved from Landsat thermal data, underground coal fires related to thermal anomalies were identified using the MEDIAN+1.5×IQR(IQR: Interquartile range) threshold technique. The locations of underground coal fires were validated using a coal fire map produced by the field survey data and cross-validated using the daytime ASTER thermal infrared imagery. Based on the fires extracted from seven Landsat thermal imageries, the spatiotemporal changes of underground coal fire areas were analyzed. The results showed that the thermalanomalous zones have been correlated with known coal fires. Cross-validation of coal fires using ASTER TIR data showed a high consistency of 79.3%. The largest coal fire area of 184.6 hectares was detected in 2010, followed by 2014(181.1 hectares) and 2016(178.5 hectares). The smaller coal fire areas were extracted with areas of 133.6 and 152.5 hectares in 2011 and 2009 respectively. Underground coal fires were mainly detected in the northern and southern part, and tend to spread to north-west of the coal field.

关键词： Underground coal fires Spatio-temporal changes Khanh Hoa coal field (Viet Nam) Landsat time-series data

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A Simplified Approach of Open Boundary Conditions for the Smoothed Particle Hydrodynamics Method

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Computer Modeling in Engineering & Sciences 2021年第11期129卷 425-442页

作者： thanh tien bui Yoshihisa Fujita Susumu Nakata Graduate School of Information Science and Engineering Ritsumeikan UniversityShiga525-8577Japan College of Information Science and Engineering Ritsumeikan UniversityShiga525-8577Japan

In this paper,we propose a simplified approach of open boundary conditions for particle-based fluid simulations using the weakly compressible smoothed-particle hydrodynamics(SPH)*** this scheme,the values of the inflow/outflow particles are calculated as fluid particles or imposed desired values to ensure the appropriate evolution of the flow field instead of using a renormalization process involving the fluid *** concentrate on handling the generation of new inflow particles using several simple approaches that contribute to the flow field *** advantages of theδ^(+).-SPH scheme,specifically the particle shifting technique,were successfully applied to correct the position,velocity,and pressure terms of the ***,unexpected errors were removed and tensile instabilities of the particles were *** proposed technique is validated for several benchmark test cases,and the tests show that the results match the reference solutions well.A viscous open-channel flow is used to demonstrate the stability of the flow field during the computational *** on this stability,we compress the computational domain to a lower resolution in a second test case while preserving the accuracy of the *** over a backward-facing step is used to highlight the challenges of inflow boundary conditions with prescribed or non-prescribed *** developed technique is well suited to the wall boundaries and the evolution of the flow *** results demonstrate the robustness and versatility of the proposed technique for a variety of simulations.

关键词： Fluid simulation smoothed particle hydrodynamics open boundaries

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Graphical method based on modified maximum force criterion to indicate forming limit curves of 22MnB5 boron steel sheets at elevated temperatures

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Journal of Iron and Steel Research International 2021年第8期28卷 1009-1018页

作者： thanh Luyen Quoc-Tuan Pham Thi-Bich Mac tien-Long Banh Duc-Toan Nguyen Faculty of Mechanical Engineering Hungyen University of Technology and EducationHungyen 160000Vietnam Division of Computational Mathematics and Engineering Institute for Computational ScienceTon Duc Thang UniversityHo Chi Minh City 70000Vietnam Faculty of Civil Engineering Ton Duc Thang UniversityHo Chi Minh City 70000Vietnam School of Mechanical Engineering Hanoi University of Science and TechnologyHanoi City 100000Vietnam

A new approach for predicting forming limit curves(FLCs)at elevated temperatures was proposed *** are often used to predict failure and determine the optimal forming parameters of automotive ***,a graphical method based on a modified maximum force criterion was applied to estimate the FLCs of 22MnB5 boron steel sheets at room temperature using various hardening ***,the predicted FLC data at room temperature were compared with corresponding data obtained from Nakazima's tests to obtain the best *** estimate the FLC at elevated temperatures,tensile tests were conducted at various temperatures to determine the ratios of equivalent fracture strains between the corresponding elevated temperatures and room *** at elevated temperatures could be established based on obtained ***,the predicted FLCs at elevated temperatures did not agree well with the corresponding FLC experimental data of Zhou et al.A new method was proposed herein to improve the prediction of FLCs at elevated *** FLC calculated at room tem-perature was utilized to predict the failure of Nakazima's samples via finite element *** on the simulation results at room temperature,the mathematical relationships between the equivalent ductile fracture strain versus stress triaxiality and strain ratio were established and then combined with ratios between elevated and room temperatures to calculate the FLCs at different *** predicted FLCs at elevated temperatures agree well with the corresponding experimental FLC data.

关键词： Forming limit curve Modified maximum force criterion Graphical method Hardening law Finite element method Boron steel sheet Elevated temperature

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Multiparticle^(nat)Sr(γ,xny p)reactions induced with bremsstrahlung end-point energies of 55,60,and 65 MeV

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Chinese Physics C 2022年第9期46卷 185-196页

作者： Nguyen Van Do Nguyen thanh Luan Nguyen Thi Xuan Kim tien thanh Nguyen Thi Hien Guinyun Kim Institute of Theoretical and Applied Research Duy Tan UniversityHanoi 100000Vietnam Faculty of Natural Sciences Duy Tan UniversityDa Nang 550000Vietnam Institute of Physics Vietnam Academy of Science and Technology10 Dao TanHanoi 10000Vietnam Department of Physics Kyungpook National UniversityDaegu 415661Republic of Korea Graduate School of Science and Technology Vietnam Academy of Science and Technology18 Hoang Quoc VietHanoiVietnam

This study measured the yields of the radionuclides^(82)Sr,^(83(m+g))Sr,^(85m)Sr,^(85g)Sr,^(87m)Sr,^(81(g+0.976m))Rb,^(82m)Rb,^(83g)Rb,^(84(m+g))Rb,and^(86(m+g))Rb produced in^(nat)Sr(γ,xnyp)multiparticle reactions with bremsstrahlung end-point energies of 55,60,and 65 *** bremsstrahlung radiation was generated using the 100-MeV electron linear accelerator at the Pohang Accelerator Laboratory,Korea,and the reaction yields were derived from the induced activitiesmeasured using off-lineγ-ray *** obtain accurate experimental results,we performed the necessaryγ-ray interference *** experimental results were compared with the theoretical predictions obtained using the TALYS-1.95 statistical nuclear model *** calculations were performed using six different level-density models to ascertain which model best fitted the experimental *** dependence of the reaction yield on the incident bremsstrahlung energy and on the number of nucleons emitted by the photonuclear reactions was also investigated.

关键词： reaction yield activation method ^(nat)Sr(γ xnyp)reactions γ-ray spectrometry 55- 60- and 65-MeV bremsstrahlung.

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Structural and luminescent properties of (Eu,Tb) PO_4·H_2O nanorods/nanowires prepared by microwave technique

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Journal of Rare Earths 2011年第12期29卷 1170-1173页

作者： Nguyen thanh Huong Nguyen Duc Van Dinh Manh tien Do Khanh Tung Nguyen thanh Binh Tran Kim Anh Le Quoc Minh Institute of Materials Science Vietnam Academy of Science and Technology University of Engineering and Technology National University HanoiVietnam

Nanowires/nanorods of europium/terbium orthophosphate monohydrate with Eu^3＋ concentration of 6, 11, and 20 at.% were prepared by microwave synthesis method. The effects of Eu^3＋ doping concentration on structure, morphology and optical properties of nanomaterials were also investigated. The results showed that, for all studied Eu^3＋ doping concentrations, a single-crystalline phase of rhabdophane-type （Eu,Tb）PO4·H2O nanowires/nanorods was obtained by using microwave heating of an aqueous solution of terbium（Ⅲ） nitrate, europium（Ⅲ） nitrate and NH4H2PO4 with pH=2. The length and width of these nanowires/nanorods ranged from 150 to 300 nm and from 10 to 50 nm, respectively. The evidence of energy transfer from Tb^3＋ to Eu^3＋ due to the energy overlap between the donor Tb^3＋ and the acceptor Eu^3＋was observed obviously via a significant enhancement in the luminescent intensity of Eu^3＋. Keywords：

关键词： microwave technique nanowires/nanorods energy transfer fluorescence spectroscopy rare earths

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Effect of thinning intensity on tree growth and temporal variation of seed and cone production in a Pinus koraiensis plantation

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Journal of Forestry Research 2019年第3期30卷 835-845页

作者： thanh Tuan Nguyen Dinh tien Tai Peng Zhang Muhammad Razaq Hai-Long Shen School of Forestry Northeast Forestry University Harbin 150040People’s Republic of China Department of Forestry Vietnam Forestry University-Second CampusOkayamaDongnai 810000Vietnam Graduate School of Environmental and Life Science Okayama UniversityOkayamaJapan

Thinning of Korean pine (Pinus koraiensis Sieb. et Zucc.) is used to facilitate timber and cone production. The present study in Northeast China investigated the effects of thinning intensity on individual tree growth, temporal variation in cone yield, and seed quality in Korean pine plantation. In 2005, five thinning intensity levels (none, extreme, heavy, moderate and light) were set in 15 permanent plots in a 32-year-old Korean pine plantation at Mengjiagang Forest Farm, Jiamusi City, Heilongjiang Province. We recorded tree growth and seed cone production from 2013 to 2016, i.e., from 8 to 11 years after thinning. Except for height growth, thinning increased tree growth (diameter at breast height and crown size) and improved cone yield. The extreme thinning treatment (to 300 trees per hectare) resulted in the largest tree diameter, tree volume, crown size and 4-year cone production per tree. The highest cone yield per tree in the mast year (2014) was observed when stands were thinned to 500 trees per hectare (heavy thinning). Although the best cone and seed quality and the largest cone and seed mass per tree were recorded in the heavily thinned stand, no significant differences were found between heavy and moderate thinning stands (750 trees per hectare). At the stand level, the moderately thinned stand had the highest basal area, stock volume and seed cone production per stand. Our results suggest that thinning to 750 trees per hectare will improve timber and cone productivity in 40-year-old P. koraiensis stands.

关键词： Korean pine Thinning intensity Seed yield Tree growth Temporal variation in cone yield

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Minimizing Warpage for Macro-Size Fused Deposition Modeling Parts

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Computers, Materials & Continua 2021年第9期68卷 2913-2923页

作者： thanh Thuong Huynh tien V.T.Nguyen Quoc Manh Nguyen Trieu Khoa Nguyen Department of Mechanical Engineering Can Tho UniversityCampus IICan ThoVietnam Faculty of Mechanical Technology Industrial University of Ho Chi Minh CityHo Chi Minh70000Vietnam Mechanical Engineering Department National Kaohsiung University of Science and TechnologyKaohsiung80778Taiwan Faculty of Mechanical Engineering Hung Yen University of Technology and EducationHung Yen16000Vietnam

In this study,we investigated warpage and corner lifting minimization for three-dimensional printed parts generated by macro-size fused deposition modeling(FDM).First,the reasons for warpage were theoretically *** approach revealed that the thermal deformation and differential volumetric shrinkage of the extruded molten plastic resulted in warpage of FDM *** addition,low adhesion between the deposited model and the heated or non-heated printing bed may intensify warpage *** a next step,initial small-size and medium-size models were used to identify parameters to manage and minimize warpage in a way that would reduce material consumption and running ***,a macro-size model was built to experimentally investigate and verify the technical solutions to minimize the warpage of FDM *** conclusion,an improved part with reduced warpage was efficiently produced after detailed consideration of thermal effects and adhesion *** exists to widen the application scope of FDM technology in manufacturing for processes like thermoforming that involve mold core fabrication with *** technology,which has applications not only in mechanical engineering but also in related engineering fields,is convenient and could readily be applied to practical manufacturing industries.

关键词： Fused deposition modeling corner lifting volumetric shrinkage thermal deformation acrylonitrile butadiene styrene filament

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One-step hydrothermal synthesis of Sn-doped α-Fe_(2)O_(3) nanoparticles for enhanced photocatalytic degradation of Congo red

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Journal of Semiconductors 2022年第12期43卷 22-31页

作者： Van Nang Lam Thi Bich Vu Quang Dat Do Thi thanh Xuan Le tien Dai Nguyen T-thanh-Bao Nguyen Hoang Tung Do Thi Tu Oanh Nguyen Department of Natural Sciences Hoa Lu UniversityNinh NhatNinh Binh CityViet Nam Institute of Theoretical and Applied Research Duy Tan UniversityHanoi 100000Viet Nam Faculty of Natural Sciences Duy Tan UniversityDa Nang 550000Vietnam Institute of Physics Vietnam Academy of Science and Technology10 Dao TanBa DinhHanoiVietnam Institute of Materials Science Vietnam Academy of Science and Technology18 Hoang Quoc VietCaugiayHanoiVietnam

We report on the synthesis of Sn-doped hematite nanoparticles(Sn-α-Fe_(2)O_(3) NPs)by the hydrothermal *** prepared Sn-α-Fe_(2)O_(3) NPs had a highly pure and well crystalline rhombohedral phase with an average particle size of 41.4 *** optical properties of as-synthesizedα-Fe_(2)O_(3) NPs show a higher bandgap energy(2.40-2.57 eV)than that of pure bulkα-Fe_(2)O_(3)(2.1 eV).By doping Sn intoα-Fe_(2)O_(3) NPs,the Sn-doped hematite was observed a redshift toward a long wavelength with in-creasing Sn concentration from 0%to 4.0%.The photocatalytic activity of Sn-dopedα-Fe_(2)O_(3) NPs was evaluated by Congo red(CR)dye *** degradation efficiency of CR dye using Sn-α-Fe_(2)O_(3) NPs catalyst is higher than that of pureα-Fe_(2)O_(3) *** highest degradation efficiency of CR dye was 97.8%using 2.5%Sn-dopedα-Fe_(2)O_(3) NPs catalyst under visible-light *** results suggest that the synthesized Sn-dopedα-Fe_(2)O_(3) nanoparticles might be a suitable approach to develop a photocatalytic degradation of toxic inorganic dye in wastewater.

关键词： α-Fe_(2)O_(3)nanoparticles Sn Congo red photocatalytic properties photodegradation

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Fitting a Probability Distribution to Extreme Precipitation for a Limited Mountain Area in Vietnam

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Journal of Geoscience and Environment Protection 2017年第5期5卷 92-107页

作者： Nguyen tien thanh Department of Hydrometeorological Modeling and Forecasting Thuy Loi University Hanoi Vietnam

In this paper, an analysis of adapted 20 extreme precipitation indices is calculated for a limited mountain area in southern Vietnam. The daily precipitation data from four stations in the period of more than 30 years are selected. The statistical characteristics of maximum, minimum, mean, standard deviation, skewness, and kurtoris for each index are also analysed. A variety of distributions such as Normal, Lognormal, Beta, Gamma, Exponential, Loglogistic, and Johnson is used to find the best fit probability distribution for this area on the basic of the highest score. The scores are estimated based on the ranking of statistical goodness of fit test. The goodness of fit tests is the Anderson-Darling and Shapiro-Wilks tests. The best fit distribution for each index of extreme precipitation at each station is found out. Results revealed that the Johnson distribution is the best fit distribution to the data of very heavy precipitation days greater than 50 mm. Over a limited mountain area, it is difficult to fit a probability distribution to the precipitation fraction due to extremely wet days, number of extremely wet days, and number of extremely wet days when precipitation greater than 99 percentage. The lognormal, Johnson, and Loglogistic distribution are the best choices to fit most of the extreme precipitation indices over this area.

关键词： Extreme Precipitation Mountain Distribution Vietnam

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