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Deflection amplification factor for estimating seismic lateral deformations of rC frames

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Earthquake Engineering and Engineering Vibration 2015年第2期14卷 373-384页

作者： Maryam Samimifar Asghar Vatani Oskouei Fayaz rahimzadeh rofooei Department of Civil Engineering Shahid Rajaee Teacher Training University Department of Civil Engineering Kharazmi University Department of Civil Engineering Sharif University of Technology

Different values have been assigned to the ratio of the defl ection amplifi cation factor(Cd) to the response modifi cation factor(r) for a specifi ed force-resisting system in the seismic design provisions while the same application is defi ned for it. An analytical study of the seismic responses of several reinforced concrete frames subjected to a suite of earthquake records performed in this research indicate that the stories’ overstrength and stiffness distribution along the structural height can affect local defl ections more than global ones. Therefore, the Cd/r ratio is calculated based on the ratio of both maximum inelastic to maximum elastic displacements and interstory drifts. Due to damage concentration in some specifi c stories, the defl ection amplifi cation factor calculated based on inelastic interstory drifts was larger than that of the inelastic displacements. Consequently, a minimum value of 1.0 is recommended for the Cd/r ratio in order to estimate maximum inelastic drifts. The ratio of inelastic to elastic displacement was generally found to increase slightly along the structural height for the studied rC models. In addition, it was detected that the story damage indices of the studied rC frames decrease when the inverted value of inelastic interstory drift ratios are increased through a(negative) power form.

关键词： deflection amplification factor nonlinear dynamic

Improving the seismic torsional behavior of plan-asymmetric,single-storey,concrete moment resisting buildings with fluid viscous dampers

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Earthquake Engineering and Engineering Vibration 2016年第1期15卷 61-78页

作者： Fayaz rahimzadeh rofooei Sahar Mohammadzadeh Civil Engineering Department Sharif University of Technology

The optimal distribution of fluid viscous dampers（FVD）in controlling the seismic response of eccentric,single-storey,moment resisting concrete structures is investigated using the previously defined center of damping constant（CDC）.For this purpose,a number of structural models with different one-way stiffness and strength eccentricities are considered.Extensive nonlinear time history analyses are carried out for various arrangements of FVDs.It is shown that the arrangement of FVDs for controlling the torsional behavior due to asymmetry in the concrete structures is very dependent on the intensity of the peak ground acceleration（PGA）and the extent of the structural stiffness and strength eccentricities.The results indicate that,in the linear range of structural behavior the stiffness eccentricity es which is the main parameter in determining the location of optimal CDC,is found to be less or smaller than the optimal damping constant eccentricity e＊d,i.e.,｜e＊d｜〉｜es｜.But,in the nonlinear range of structural behavior where the strength eccentricity er is the dominant factor in determining the location of optimal CDC,｜e＊d｜〉｜er｜.It is also concluded that for the majority of the plan-asymmetric,concrete structures considered in this study with er ≠ 0,the optimal CDC approaches the center of mass as er decreases.

关键词： plan-asymmetric concrete buildings torsion fluid viscous dampers weak torsional balance nonlinear timehistory analysis

robust low-rank learning multi-output regression for incipient sediment motion in sewer pipes

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International Journal of Sediment research 2023年第6期38卷 859-870页

作者： Mir Jafar Sadegh Safari Shervin rahimzadeh Arashloo Department of Civil Engineering Yasar University Department of Computer Engineering Bilkent University

The existing incipient sediment motion models typically apply conventional regression methods considering either velocity or shear stress.In the current study,incipient sediment motion is analyzed through a simultaneous and joint analysis of velocity and shear stress using the robust low-rank learning(rLrL) multi-output regression technique.Moreover,the experimental data compiled from five different channels are utilized to develop a generic incipient sediment motion model valid for a channel of any cross-sectional shape.The efficiency of the developed method is examined and compared against the available conventional regression models.The experimental results indicate that the rLrL model yields better results than its counterparts.In particular,while cross-section specific models fail to provide accurate estimates for shear stress or velocity for other cross sections,the proposed model provides satisfactory results for all channel shapes.The better performance of the recommended approach can be attributed to the joint modeling of the shear stress and the velocity which is realized by capturing the correlation between these parameters in terms of a low rank output mixing matrix which enhances the prediction performance of the approach.

关键词： Low-rank learning Multi-output regression Sediment transport Sewer flow Shear stress approach Velocity approach

Prediction model for determining the optimum operational parameters in laser forming of fiber-reinforced composites

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Advances in Manufacturing 2020年第2期8卷 242-251页

作者： Annamaria Gisario Mehrshad Mehrpouya Atabak rahimzadeh Andrea De Bartolomeis Massimiliano Barletta Department of Mechanical and Aerospace Engineering Sapienza University of RomeVia Eudossiana 1800184 RomeItaly Department of Mechanical and Industrial Engineering The University of Roma TreVia Vito Volterra 6200146 RomeItaly Department of Mechanical Engineering University of BathBath BA27AYUK

Composite materials are widely employed in various industries,such as aerospace,automobile,and sports equipment,owing to their lightweight and strong structure in comparison with conventional materials.I aser material processing is a rapid technique for performing the various processes on composite materials.In particular,laser forming is a flexible and reliable approach for shaping fiber-metal laminates(FML.s),which are widely used in the aerospace industry due to several advantages,such as high strength and light weight.In this study,a prediction model was developed for determining the optimal laser parameters(power and speed)when forming FML composites.Artificial neural networks(ANNs)were applied to estimate the process outputs(temperature and bending angle)as a result of the modeling process.For this purpose,several ANN models were developed using various strategies.Finally,the achieved results demonstrated the advantage of the models for predicting the optimal operational parameters.

关键词： Laser forming(LF) Fiber-reinforced composite Fiber-metal laminates(FMLs) Glass laminate aluminum reinforced epoxy(GLArE) Artificial neural networks(ANNs)

EpiMap: Fine-tuning integrative epigenomics maps to understand complex human regulatory genomic circuitry

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Signal Transduction and Targeted Therapy 2021年第6期6卷 1627-1629页

作者： Dave S.B.Hoon Negin rahimzadeh Matias A.Bustos Department of Translational Molecular Medicine Division of Molecular OncologySaint John’s Cancer Institute at Providence Saint John’s Health CenterSanta MonicaCAUSA

In a recent paper published in Nature,Boix et al.1 developed an integrated platform on epigenomic maps that represents a significant updated resource in human regulatory circuitry as related to specific organ tissues and cells,as well as specific disease traits.The EpiMap(for epigenome integration across multiple annotation projects)is a highly valuable compendium comprising 10,000 epigenomic maps across 833 biospecimens and 33 tissue categories.The distinct biospecimens expanding coverage to life development(embryonic to adult)and different sample types including complex organ tissues as well as primary cells,and established normal and tumor cell lines.The biospecimen analysis provides a comprehensive view of human genome circuitry making EpiMap a remarkable platform for epigenomic landscapes assessment to the investigator.

关键词： maps tuning Map

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Analysis and Optimization of Operational and Pollutant Attributes of Diesel Engine with CNT-Infused Orange Peel Biodiesel-Diesel Blend Fuel

作者： (美)rahimzadeh Auri

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Journal of Thermal Science 2024年第2期33卷 761-778页

作者： ranjeet rAI r.r.SAHOO Mechanical Engineering Department GLA UniversityMathura281406India Mechanical Engineering Department IIT(BHU)Varanasi221005India

The current study is performed to find sustainable solutions for the future of transportation and environmental well-being.Both conventional methods and experimental design table(L16 Orthogonal Array)techniques have been employed to examine and optimize a diesel-powered engine's operational and pollutant parameters.The L16 Orthogonal Array is obtained through Taguchi's experimental design approach using Minitab 16 software.The experimental design incorporated three control variables,namely engine speed,fuel type,and engine load,each with four levels.The operational parameters,namely brake thermal efficiency(BTE)and brake specific fuel consumption(BSFC),as well as the emission characteristics,including hydrocarbon(HC),carbon monoxide(CO),nitrogen oxide(NO),and smoke emissions,were acquired using the L16 orthogonal array(OA) and subsequently examined.The utilization of methodologies such as signal-to-noise(S/N) ratio and grey analysis was employed to determine the optimal operational state of the engine to achieve maximum performance while minimizing emissions.The engine's ideal state of operation,in terms of BTE and BSFC,was determined to be at 75% engine load,1000 r/min engine speed,and using 10^(-4)(in vol) carbon nanotube incorporated 20% orange peel biodiesel(OPB20CNT100) blended fuel(A3-B1-C4).The study indicated that engine load significantly influenced BTE and BSFC,with 84.05% and 87.79% contribution factors,respectively.At 25% engine load,1000 r/min,and OPB20CNT100 fuel(A1-B1-C4) CO,smoke,NO,and HC emissions were the lowest.Engine load affects emissions the most.Engine BSFC increased 3.10% and NO emissions 1.77%.BTE,CO,smoke,and HC emissions decreased by 1.9%,12.29%,47.05%,and 47.22%,respectively,at optimal operating conditions concerning diesel fuel.This study shows that Taguchi-Grey's experimental design optimizes diesel engine operational and pollutant attributes.The outcomes revealed that orange peel biodiesel infused with CNT can replace diesel fuel in an environmentally friendly way.This alternative

关键词： Taguchi-Grey method OPB20CNT100 transesterification S/N ratio GrG HC CO and NO

A Combination of residual Distribution and the Active Flux Formulations or a New Class of Schemes That Can Combine Several Writings of the Same Hyperbolic Problem:Application to the 1D Euler Equations

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Communications on Applied Mathematics and Computation 2023年第1期5卷 370-402页

作者： r.Abgrall Institute of Mathematics University of ZürichWinterthurerstrasse 190CH 8057 ZurichSwitzerland

We show how to combine in a natural way(i.e.,without any test nor switch)the conservative and non-conservative formulations of an hyperbolic system that has a conservative form.This is inspired from two different classes of schemes:the residual distribution one(Abgrall in Commun Appl Math Comput 2(3):341–368,2020),and the active flux formulations(Eyman and roe in 49th AIAA Aerospace Science Meeting,2011;Eyman in active flux.PhD thesis,University of Michigan,2013;Helzel et al.in J Sci Comput 80(3):35–61,2019;Barsukow in J Sci Comput 86(1):paper No.3,34,2021;roe in J Sci Comput 73:1094–1114,2017).The solution is globally continuous,and as in the active flux method,described by a combination of point values and average values.Unlike the“classical”active flux methods,the meaning of the point-wise and cell average degrees of freedom is different,and hence follow different forms of PDEs;it is a conservative version of the cell average,and a possibly non-conservative one for the points.This new class of scheme is proved to satisfy a Lax-Wendroff-like theorem.We also develop a method to perform nonlinear stability.We illustrate the behaviour on several benchmarks,some quite challenging.

关键词： Hyperbolic problems high order Active flux MOOD residual distribution methods

激光功率对Nd:YAG激光焊接钛管材料的显微组织和力学性能的影响

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Journal of Central South University 2023年第4期30卷 1064-1074页

作者： r.PALANIVEL Department of Mechanical Engineering College of EngineeringShaqra UniversityDawadmiRiyadh 11911Saudi Arabia

采用Nd:YAG激光束焊接连接2级钛管。通过组织表征和力学试验研究了激光功率的影响。结果表明,随着激光功率的增加,焊珠的几何形状从楔形变成了平行形,焊接区呈粗糙、不均匀、锯齿状的粗颗粒结构。激光功率对晶粒的位向角分布也有显著影... 详细信息

采用Nd:YAG激光束焊接连接2级钛管。通过组织表征和力学试验研究了激光功率的影响。结果表明,随着激光功率的增加,焊珠的几何形状从楔形变成了平行形,焊接区呈粗糙、不均匀、锯齿状的粗颗粒结构。激光功率对晶粒的位向角分布也有显著影响。高功率激光导致焊接区出现了较大的孔隙,还有高密度的位错和亚晶界。通过激光焊接,材料的强度得到提高,但通过显微硬度分析发现,高功率激光下材料的强度提高较小,而在较低功率的激光下,材料可以获得更高的抗拉强度。通过断口分析发现,焊接区存在的微小空隙导致材料出现韧性断裂。

关键词：激光束焊接钛管接头显微结构硬度抗拉强度