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nonlinear dynamic modeling of planar moving Timoshenko beam considering non-rigid non-elastic axial effects

Applied mathematics and mechanics(English Edition) 2024年第3期45卷 479-496页

作者： m.ABBASI GAVARI m.R.HOmAEInEZHAD Faculty of mechanical Engineering K.N.Toosi University of TechnologyTehran 19991-43344Iran

Due to the importance of vibration effects on the functional accuracy of mechanical systems,this research aims to develop a precise model of a nonlinearly vibrating single-link mobile flexible *** manipulator consists of an elastic arm,a rotary motor,and a rigid carrier,and undergoes general in-plane rigid body motion along with elastic transverse *** accurately model the elastic behavior,Timoshenko’s beam theory is used to describe the flexible arm,which accounts for rotary inertia and shear deformation *** applying newton’s second law,the nonlinear governing equations of motion for the manipulator are derived as a coupled system of ordinary differential equations(ODEs)and partial differential equations(PDEs).Then,the assumed mode method(Amm)is used to solve this nonlinear system of governing equations with appropriate shape *** assumed modes can be obtained after solving the characteristic equation of a Timoshenko beam with clamped boundary conditions at one end and an attached mass/inertia at the *** addition,the effect of the transverse vibration of the inextensible arm on its axial behavior is *** the axial rigidity,the effect makes the rigid body dynamics invalid for the axial behavior of the ***,numerical simulations are conducted to evaluate the performance of the developed model,and the results are compared with those obtained by the finite element *** comparison confirms the validity of the proposed dynamic model for the *** to the mentioned features,this model can be reliable for investigating the system’s vibrational behavior and implementing vibration control algorithms.

关键词： planar moving Timoshenko beam non-rigid non-elastic axial effect as-sumed mode method(Amm) nonlinear motion analysis

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Analysis of PEm and AEm electrolysis by neural network pattern recognition, association rule mining and LImE

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Energy and AI 2023年第3期13卷 169-181页

作者： m.Erdem Gunay n.Alper Tapan Department of Energy Systems Engineering Istanbul Bilgi UniversityEyupsultanIstanbul 34060Turkey Department of Chemical Engineering Gazi UniversityMaltepeAnkara 06570Turkey

In this work,as an extension of previous machine learning studies,three novel techniques,namely local inter-pretable model-agnostic explanations(LImE),neural network pattern recognition and association rule mining(arm)were utilized for proton exchange membrane(PEm)and anion exchange membrane(AEm)electrolyzer database for hydrogen *** main goal of LImE was to determine the positive or negative effects of a variety of descriptor variables on current density,power density and *** this technique,it was possible to uncover rules or paths that lead to high current density,low power density and low *** provided the dominant rules leading to high current density such as using ELAT as the cathode gas diffusion layer,using pure Pt on the cathode surface and using pure carbon as the cathode *** addition,LImE and neural network pattern recognition successfully uncovered the importance of catalytic materials such as cath-ode/anode support/surface elements,operational variables like K_(2)CO_(3) or KOH concentration in the electrolyte,certain membrane types,gas diffusion layers,and applied potential on current *** was then concluded that machine learning can help determine the ideal conditions for developing a PEm and AEm electrolyzer to maximize hydrogen generation,which can also guide future research.

关键词： machine learning Data mining Hydrogen production Current density

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Petrographic composition of coal within the Benue Trough,nigeria and a consideration of the paleodepositional setting

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International Journal of Coal Science & Technology 2022年第3期9卷 67-90页

作者： A.D.mangs n.J.Wagner O.m.moroeng U.A.Lar DSI-nRF CImERA Department of GeologyUniversity of JohannesburgJohannesburgSouth Africa Department of Geology University of JosJosNigeria

The petrographic composition of Cretaceous-age coals hosted in the Benue Trough,nigeria is presented and discussed in terms of the paleodepositional settings that infuenced the coal-bearing *** Benue Trough is a failed arm of the triple junction of an inland sedimentary basin that extends in a nE-SW direction from the Gulf of Guinea in the south,to the Chad Basin in the north.A total of twenty-nine(29)coal samples were obtained from nineteen coal localities in the Upper(UBT),middle(mBT),and Lower Benue Trough(LBT).The high average volatile matter yield,low average ash yield,high calorifc value(24.82 mJ/kg,on average),and low sulphur values indicate good quality coal *** organic matter is dominated by vitrinite,reported at an average of 59.3%by volume(mineral-matter free).Variation was noted in the inertinite content across three *** macerals were not commonly observed in the studied samples and were absent in the mBT *** facies studies decipher the paleoenvironmental conditions under which the vegetation *** commonly used are the gelifcation index(GI),tissue preservation index(TPI),ground water index(GWI and variations),vegetation index(VI),and wood index(WI).Comparing the array of coal facies models applied,the mBT samples difer from the UBT and LBT samples,concurring with the coal quality *** UBT and LBT coals formed in an upper deltaic to drier piedmont plane depositional environment,while the mBT coal formed in a lower deltaic marsh to wet forest swamp depositional *** samples indicate an ombrotrophic *** view of the modifed equations and the plots used,interpreting depositional environments from just a single model is not reliable.

关键词： Benue Trough Coal petrography Depositional environment microlithotypes Vitrinite

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Effectiveness of a home-environmental intervention package and an early child development intervention on child health and development in high-altitude rural communities in the Peruvian Andes: a cluster-randomised controlled trial

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Infectious Diseases of Poverty 2022年第3期11卷 95-96页

作者： néstor nuño Daniel mäusezahl Jan Hattendorf Hector Verastegui mariela Ortiz Stella m.Hartinger Department of Public Health and Epidemiology Swiss Tropical and Public Health InstituteKreuzstrasse 2CH-4123AllschwilSwitzerland 不详

Background: Unsafe drinking water,poor sanitation and hygiene,exposure to household air pollution and low cognitive and socio-emotional stimulation are risk factors affecting children in low-and middle-income *** implemented an integrated home-environmental intervention package(IHIP),comprising a kitchen sink,hygiene education and a certified improved biomass cookstove,and an early child development(ECD)programme to improve children´s health and developmental outcomes in the rural high-altitude Andes of ***: We conducted a one-year cluster-randomised controlled trial among 317 childrenmonths divided into 4 arms(IHIP+ECD,IHIP,ECD,and Control)and 40 clusters(10 clusters per arm).ECD status(socio-emotional,fine and gross motor,communication,cognitive skills,and an overall performance)measured with the Peruvian Infant Development Scale and the occurrence of self-reported child diarrhoea from caretakers were primary *** outcomes included the occurrence of acute respiratory infections and the presence of thermo-tolerant faecal bacteria in drinking *** trial was powered to compare each intervention against its control arm but it did not allow pairwise comparisons among the four *** analysis followed the intention-to-treat *** the statistical analysis,we employed generalised estimating equation models with robust standard errors and an independent correlation ***: We obtained ECD information from 101 children who received the ECD intervention(individually and combined with IHIP)and 102 *** who received the ECD intervention performed better in all the domains compared to *** found differences in the overall performance(64 vs.39%,odd ratio(OR):2.8;95%confidence interval(CI):1.6–4.9)and the cognitive domain(62 vs 46%,OR:1.9;95%CI:1.1–3.5).Data analysis of child morbidity included 154 children who received the IHIP intervention(individually and combined with ECD)and 156 ***

关键词： Child development Clinical trial Diarrhoea Improved biomass cookstoves Peru WASH

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Leachate Treatment by Heterogeneous Fenton on an Activated Carbon Substrate with Fe(II) Impregnated

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Journal of Environmental Protection 2017年第4期8卷 524-539页

作者： arm.n Alejandro may-marrufo Roger Iván mendez-novelo Icela Dagmar Barceló-Quintal Hugo Eduardo Solís-Correa Germán Giacoman-Vallejos Faculty of Engineering Autonomous University of Yucatan Merida Mexico Basic and Engineering Division Chemistry and Physical Chemistry of Environmental Area University Autonomous Metropolitan-Azcapotzalco Mexico City Mexico

Organic components contained in leachates resulting from decomposition of waste are difficult to degrade. They also contain inorganic components, as nitrogen compounds, phosphates, and chlorides, also Ca, mg, K, and heavy metals. Leachate volume and its composition vary depending on biogeochemistry of type site of deposited residues, and age of sanitary landfill. In this study, it conducted a Heterogeneous Fenton, advanced oxidation process using lignitic activated carbon as solid matrix, with and without Fe2+ impregnation, for the treatment of leachate (Le) obtained from a sanitary landfill located in the city of mérida, Yucatan, mexico. In this study was determined the efficiency of Heterogeneous Fenton process for to remove Chemical Oxygen Demand (COD) and Color from crude leachates using mesoporous activated carbon, previously treated with HCl, HnO3, and a mixture of both acids and impregnated with Fe2+ on actived carbon. It was studied of activated carbon behavior previously treated with each acid and the mixture, washed with hot water and impregnated with Fe2+ using FeCl2.4H2O and FeSO4·7H2O salts. For leachate treatment by Heterogeneous Fenton reaction, it was selected carbon pretreatment with HCl acid and impregnation with FeSO4·7H2O. Treatment with HCl presented the advantage of not prematurely oxidize to Fe2+. In order to select an optimal dose and achieve an adequate concentration of HO· radicals dosage tests was carried out H2O2. By selecting the indicated procedure, it was obtained more than 80% performance in removing COD and Color from crude leachate. The confidence level for the selected variables (acids and impregnation) was determined by a statistical analyzes using the Centurion XVII software. Finally, mesoporous lignitic carbon used in this study was found to be adequate for this oxidation process, and this method presented the advantage of not producing sludge as in traditional Fenton reaction.

关键词： Heterogeneous Fenton Leachate Activated Carbon COD Color

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An improved analytical model of 4H-sic mESFET incorporating bulk and interface trapping effects

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Journal of Semiconductors 2015年第1期36卷 64-75页

作者： m.Hema Lata Rao n.V.L.narasimha murty School of Electrical Sciences IIT BhubaneswarBhubaneswar 751013India

An improved analytical model for the current–voltage（I–V） characteristics of the 4H-sic metal semiconductor field effect transistor（mESFET） on a high purity semi-insulating（HPSI） substrate with trapping and thermal effects is presented. The 4H-sic mESFET structure includes a stack of HPSI substrates and a uniformly doped channel layer. The trapping effects include both the effect of multiple deep-level traps in the substrate and surface traps between the gate to source/drain. The self-heating effects are also incorporated to obtain the accurate and realistic nature of the analytical model. The importance of the proposed model is emphasised through the inclusion of the recent and exact nature of the traps in the 4H-sic HPSI substrate responsible for substrate *** analytical model is used to exhibit DC I–V characteristics of the device with and without trapping and thermal effects. From the results, the current degradation is observed due to the surface and substrate trapping effects and the negative conductance introduced by the self-heating effect at a high drain voltage. The calculated results are compared with reported experimental and two-dimensional simulations（Silvaco -TCAD）. The proposed model also illustrates the effectiveness of the gate–source distance scaling effect compared to the gate–drain scaling effect in optimizing 4H-sic mESFET performance. Results demonstrate that the proposed I–V model of 4H-sic mESFET is suitable for realizing sic based monolithic circuits（mmICs） on HPSI substrates.

关键词： sic mESFET HPSI substrate deep-level traps mmICs

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Reduction in secondary dendrite arm spacing in cast eutectic Al–Si piston alloys by cerium addition

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International Journal of minerals,metallurgy and materials 2017年第1期24卷 91-101页

作者： R.Ahmad m.B.A.Asmael n.R.Shahizan S.Gandouz Department of manufacturing and Industrial Engineering Faculty of Mechanical and Manufacturing EngineeringUniversiti Tun Hussein Onn MalaysiaParit Raja86400 Batu PahatJohorMalaysia

The effects of Ce on the secondary dendrite arm spacing（SDAS） and mechanical behavior of Al-Si-Cu-mg alloys were investigated. The reduction of SDAS at different Ce concentrations was evaluated in a directional solidification experiment via computer-aided cooling curve thermal analysis（CA-CCTA）. The results showed that 0.1wt%-1.0wt% Ce addition resulted in a rapid solidification time, ？ts, and low solidification temperature, ？T_S, whereas 0.1wt% Ce resulted in a fast solidification time, Δ^（ta-Al）, of the α-Al phase. Furthermore, Ce addition refined the SDAS, which was reduced to approximately 36%. The mechanical properties of the alloys with and without Ce were investigated using tensile and hardness tests. The quality index（Q） and ultimate tensile strength of（UTS） Al-Si-Cu-mg alloys significantly improved with the addition of 0.1wt% Ce. moreover, the base alloy hardness was improved with increasing Ce concentration.

关键词： eutectic alloys aluminum silicon alloys cerium microstructure dendrites spacing mechanical properties

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Effect of operating conditions and potassium content on Fischer-Tropsch liquid products produced by potassium-promoted iron catalysts

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Journal of natural Gas Chemistry 2008年第2期17卷 175-178页

作者： Francisco E.m.Farias Fernando G.Sales Fabiano A.n.Fernandes Universidade Federal do Ceará Departamento de Engenharia QuímicaCampus do PiciBloco 70960455-760 Fortaleza-CEBrazil

The dependencies of Fischer-Tropsch synthesis liquid hydrocarbon product distribution on operating pressure and temperature have been studied over three potassium-promoted iron catalysts with increasing potassium molar content. The study followed an experimental planning and the results were analyzed based on surface response methodology. The effects of different operating conditions and potassium contents on the liquid product distribution were compared based on number average carbon number and dispersion. Results showed that high pressures （25 to 30 arm） favored the production of waxes that could be converted into liquid fuels through hydrocracking, while greater direct selectivity towards diesel was favored by low pressure （20 arm） using catalysts with low potassium to iron molar ratios. The liquid product distribution produced using an iron catalyst with high potassium content presented higher number-average number of carbons when compared to the distribution obtained using an iron catalyst with low potassium content.

关键词： Fischer-Tropsch synthesis liquid fuels iron-based catalyst potassium

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Finite Element Analysis of Push-Out Test of sic Fiber Reinforced Titanium matrix Composites

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稀有金属材料与工程 2009年第A3期38卷 50-53页

作者： Yuan m n Yang Y Q Huang B Zhang R J School of materials Northwestern Polytechnical University Xi＇an 710072 China

Based on the interphase layer model and the spring layer model, an improved interface model was developed to evaluate the interfacial shear strength of Titanium matrix composites(TmCs) and to analyze the effects of various parameters on the interfacial properties. The results showed that the improved interface model is more suitable for calculating the interfacial properties of sic fiber reinforced titanium matrix composites. The interfacial shear strength of sic/Timetal-834 predicted is 500 mPa. In addition, in order to better understand the interfacial properties of composites, some push out phenomenon were analyzed.

关键词：复合材料剪切强度碳化硅纤维物理性能

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Joining of hybrid AA6063-6sicp-3Grp composite and AISI1030 steel by friction welding

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Defence Technology（防务技术） 2017年第5期13卷 338-345页

作者： n.Rajesh Jesudoss Hynes m.Vivek Prabhu P.nagaraj Senior Department of mechanical Engineering Mepco Schlenk Engineering CollegeSivakasi 626005Tamil NaduIndia Department of mechanical Engineering Velammal College of Engineering and TechnologyMadurai 625009Tamil NaduIndia

Joining of metals and aluminium hybrid metal matrix composites has significant applications in aviation,ship building and automotive industries. In the present work, investigation is carried out on Friction Welding of AISI 1030 steel and hybrid AA6063-6 sic_p-3 Gr_pcomposite, that are difficult to weld by fusion welding technique. Silicon carbide and graphite particle reinforced AA6063 matrix hybrid composite was developed successfully using stir casting method and the joining feasibility of AISI1030 steel with AA6063-6 sic_p-3 Gr_p hybrid composite was tried out by friction stud welding technique. During friction stage of welding process, the particulates(sic & Graphite) used for reinforcement, tend to increase the viscosity and lead to improper mixing of matrix and reinforcement. This eventually results in lower strength in dissimilar joints. To overcome this difficulty AA1100 interlayer is used while joining hybrid composite to AISI 1030 steel. Experimentation was carried out using Taguchi based design of experiments(DOE) technique. multiple regression methods were applied to understand the relationship between process parameters of the friction stud welding process. micro structural examination reveals three separate zones namely fully plasticized zone, partially deformed zone and unaffected base material zone. Ultra fine dynamically recrystallized grains of about 341 nm were observed at the fully plasticized zone. EDX analysis confirms the presence of intermetallic compound Fe_2 Al_5 at the joint interface. According to the experimental analysis using DOE, rotational speed and interlayer sheet thickness contribute about 39% and 36% respectively in determining the impact strength of the welded joints. It is found that joining with 0.5 mm interlayer sheet provides efficient joints. Developed regression model could be used to predict the axial shortening distance and impact strength of the welded joint with reasonable accuracy.

关键词： metal matrix composite Welding mechanical properties Scanning Electron microscopy

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