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A Modified and Simplified Full Nesterov–Todd Step O(N)Infeasible Interior-Point Method for Second-Order Cone Optimization

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Journal of the Operations Research Society of China 2018年第2期6卷 301-315页

作者： behrouz kheirfam Department of Applied Mathematics Azarbaijan Shahid Madani UniversityTabrizIran

We present a modified and simplified version of an infeasible interior-point method for second-order cone optimization published in 2013(Zangiabadi et *** J Optim Theory Appl,2013).In the earlier version,each iteration consisted of one socalled feasibility step and a few centering ***,each iteration consists of only a feasibility ***,the new algorithm improves the number of iterations and the improvement is due to a lemma which gives an upper bound for the proximity after the feasibility *** complexity result coincides with the best-known iteration bound for infeasible interior-point methods.

关键词： Second-order cone optimization Infeasible interior-point method Primal-dual method Polynomial complexity

Development of AZ91/SiC surface composite by FSP:effect of vibration and process parameters on microstructure and mechanical characteristics

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Advances in Manufacturing 2020年第1期8卷 82-96页

作者： behrouz Bagheri Mahmoud Abbasi Department of Mining and Metallurgy Amirkabir University of TechnologyTehranIran Faculty of Engineering University of Kashan.KashanIran

A surface composite layer enhances the mechanical characteristics of a surface while retaining the properties of the base *** stir processing(FSP)is a method for forming surface metal matrix composites(SMMCs)that reinforce a surface with *** the current study,a new method entitled friction stir vibration processing(FSVP)was applied to form SMMCs on the surface of AZ91 magnesium alloy with SiC particles as the reinforcing *** to FSP,in FSVP,the workpiece was vibrated normal to the processing line while the tool rotated and *** microstructure and mechanical properties of friction stir(FS)and friction stir vibration(FSV)processed specimens were ***,the effects of vibration frequency and process parameters on different characteristics of FS and FSV processed specimens were *** results showed that the stir zone grains for FSV processed specimens were finer than those for FS processed specimens,and the second phase particles(SiC particles)had a more homogenous distribution in the former specimens than in the latter *** was related to the effect of workpiece vibration during FSVP,which increased the material deformation and led to enhanced dynamic recrystallization and the breakdown of agglomerated SiC *** results indicated that the stir zone grain size decreased,and the distribution homogeneity of the SiC particles increased as vibration frequency *** was also observed that the stir zone grain size increased,and the mechanical properties of the processed specimens decreased as tool rotation speed increased.

关键词： Friction stir processing(FSP) Vibration AZ91 magnesium alloy Dynamic recrystallization Microstructure Mechanical properties

An efficient two-stage approach for structural damage detection using meta-heuristic algorithms and group method of data handling surrogate model

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Frontiers of Structural and Civil Engineering 2020年第4期14卷 907-929页

作者： Hamed FATHNEJAT behrouz AHMADI-NEDUSHAN Department of Civil Engineering Yazd UniversityYazd 89195-741Iran

In this study,the performance of an efficient two-stage methodology which is applied in a damage detection system using a surrogate model of the structure has been *** the first stage,in order to locate the damage accurately,the performance of the modal strain energy based index for using different numbers of natural mode shapes has been evaluated using the confusion *** the second stage,to estimate the damage extent,the sensitivity of most used modal properties due to damage,such as natural frequency and flexibility matrix is compared with the mean normalized modal strain energy(MNMSE)of suspected damaged ***,a modal property change vector is evaluated using the group method of data handling(GMDH)network as a surrogate model during damage extent estimation by optimization algorithm;in this part of methodology,the performance of the three popular optimization algorithms including particle swarm optimization(PSO),bat algorithm(BA),and colliding bodies optimization(CBO)is examined and in this regard,root mean square deviation(RMSD)based on the modal property change vector has been proposed as an objective ***,the effect of noise in the measurement of structural responses by the sensors has also been ***,in order to achieve the most generalized neural network as a surrogate model,GMDH performance is compared with a properly trained cascade feed-forward neural network(CFNN)with log-sigmoid hidden layer transfer *** results indicate that the accuracy of damage extent estimation is acceptable in the case of integration of PSO and ***,the GMDH model is also more efficient and mimics the behavior of the structure slightly better than CFNN model.

关键词： two-stage method modal strain energy surrogate model GMDH optimization damage detection

Optimal design of double-layer barrel vaults using genetic and pattern search algorithms and optimized neural network as surrogate model

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Frontiers of Structural and Civil Engineering 2023年第3期17卷 378-395页

作者： Reza JAVANMARDI behrouz AHMADI-NEDUSHAN Department of Civil Engineering Yazd UniversityYazd 89195Iran

This paper presents a combined method based on optimized neural networks and optimization algorithms to solve structural optimization *** main idea is to utilize an optimized artificial neural network(OANN)as a surrogate model to reduce the number of computations for structural ***,the OANN is trained ***,the main optimization problem is solved using the OANN and a population-based *** algorithms considered in this step are the arithmetic optimization algorithm(AOA)and genetic algorithm(GA).Finally,the abovementioned problem is solved using the optimal point obtained from the previous step and the pattern search(PS)*** evaluate the performance of the proposed method,two numerical examples are *** the first example,the performance of two algorithms,OANN+AOA+PS and OANN+GA+PS,is *** the GA reduces the elapsed time by approximately 50%compared with using the *** show that both the OANN+GA+PS and OANN+AOA+PS algorithms perform well in solving structural optimization problems and achieve the same optimal ***,the OANN+GA+PS algorithm requires significantly fewer function evaluations to achieve the same accuracy as the OANN+AOA+PS algorithm.

关键词： optimization surrogate models artificial neural network SAP2000 genetic algorithm

Effective Action for Noncommutative U(1) Gauge Theory with Higher Dimensional Terms

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Communications in Theoretical Physics 2010年第8期54卷 308-316页

作者： behrouz Mirza Moslem Zarei Department of Physics Isfahan University of Technology

In this paper we apply the assumption of our recent work in noncommutative scalar models to the noncommutative U（1） gauge theories. This assumption is that the noneommutative effects start to be visible continuously from a scale ANC and that below this scale the theory is a commutative one. Based on this assumption and using background field method and loop calculations, an effective action is derived for noncommutative U（1） gauge theory. It will be shown that the corresponding low energy effective theory is asymptotically free and that under this condition the noncommutative quadratic IR divergences will not appear. The effective theory contains higher dimensional terms, which become more important at high energies. These terms predict an elastic photon-photon scattering due to the noncommutativity of space. The coefficients of these higher dimensional terms also satisfy a positivity constraint indicating that in this theory the related diseases of superluminal signal propagating and bad analytic properties of S-matrix do not exist. In the last section, we will apply our method to the noncommutative extra dimension theories.

关键词： noncommutative field theory background field method effective action

Microstructure and mechanical characteristics of AA6061-T6 joints produced by friction stir welding,friction stir vibration welding and tungsten inert gas welding:A comparative study

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International Journal of Minerals,Metallurgy and Materials 2021年第3期28卷 450-461页

作者： behrouz Bagheri Mahmoud Abbasi Amin Abdollahzadeh Department of Mining and Metallurgy Amirkabir University of TechnologyTehranIran Faculty of Engineering University of KashanRavandi Blvd.KashanIran Department of Materials Science and Engineering Faculty of EngineeringShahid Chamran University of AhvazAhvazIran

This study compared the microstructure and mechanical characteristics of AA6061-T6 joints produced using friction stir welding(FSW),friction stir vibration welding(FSVW),and tungsten inert gas welding(TIG).FSVW is a modified version of FSW wherein the joining specimens are vibrated normal to the welding line during *** results indicated that the weld region grains for FSVW and FSW were equiaxed and were smaller than the grains for *** addition,the weld region grains for FSVW were finer compared with those for *** also showed that the strength,hardness,and toughness values of the joints produced by FSVW were higher than those of the other joints produced by FSW and *** vibration during FSW enhanced dynamic recrystallization,which led to the development of finer *** weld efficiency of FSVW was approximately 81%,whereas those of FSW and TIG were approximately 74%and 67%,respectively.

关键词： friction stir welding vibration tungsten inert gas welding mechanical characteristics microstructure

A new bracing system for improvement of seismic performance of steel jacket type offshore platforms with float-over-deck

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Petroleum Science 2013年第3期10卷 373-384页

作者： behrouz Asgarian Hamed Rahman Shokrgozar Department of Civil Engineering K. N. Toosi University of TechnologyNo. 1346 Valiasr Street Mirdamad Intersection 19967 P.O. Box. 15875-4416Tehran Iran

In this paper, the seismic response of a newly designed steel jacket offshore platform with a float over deck （FOD） system in the Persian Gulf was investigated through incremental dynamic analysis. Comparison of incremental dynamic analysis results for both directions of the platform shows that the lateral strength of the platform in the float over direction is less than its lateral strength in other direction. Dynamic characteristics measurement of a scale model of platform was also performed using forced vibration tests. From experimental measurement of the scaled model, it was observed that dynamic characteristic of the platform is different in the float over direction compared to the other direction. Therefore, a new offshore installed bracing system for the float over direction was proposed for improvement of seismic performance of this type of platform. Finally, the structure with the modified system was assessed using the probabilistic seismic assessment method as well as experimental measurement of its dynamic characteristics. It was observed that the proposed offshore installed bracing system improves the performance of platforms subjected to strong ground motion.

关键词： Steel jacket type offshore platform float-over deck mean annual frequency force vibration test seismic performance dynamic characteristics

Solvent Effects on Complexation of Molybdenum（Ⅵ） with Nitrilotriacetic Acid in Different Aqueous Solutions of Propanol

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Chinese Journal of Chemistry 2007年第3期25卷 284-288页

作者： MOHAMMADI behrouz MOHAMMADI Jalalb Chemistry Department Shahid Beheshti University Tehran Evin Iran Chemistry Department Tabriz University Tabriz Iran

By using spectrophotometric and potentiometric techniques the formation constants of the species formed in the systems H^＋＋ Mo（Ⅵ）＋nitrilotriacetic acid and H^＋＋ nitrilotriacetic acid have been determined in aqueous solutions of propanol at 25 ℃ and constant ionic strength 0.1 molodm^-3 sodium perchlorate. The composition of the complex was determined by the continuous variation method. It was shown that molybdenum（Ⅵ） forms a mononuclear 1 ： 1 complex with nitrilotriacetic acid of the type MoO3L^-3 at -lg[H^＋] =5.8. The formation constants in various media were analyzed in terms of Kamlet and Taft＇s parameters. Linear relationships were observed when lg Ks was plotted versusp. Finally, the results were discussed in terms of the effect of solvent on complexation.

关键词： solvent effect molybdenum(Ⅵ) nitrilotriacetic acid (NTA) propanol

Seismic progressive-failure analysis of tall steel structures under beam-removal scenarios

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Frontiers of Structural and Civil Engineering 2019年第4期13卷 904-917页

作者： behrouz BEHNAM Fahimeh SHOJAEI Hamid Reza RONAGH School of Civil and Environmental Engineering Amirkabir University of Technology Tehran 13496 Iran Independent Researcher Earthquake Engineer Parand 37611 Iran Centre for Infrastructure Engineering Western Sydney University NSW 2751 Australia

Investigating progressive collapse of tall structures under beam removal scenarios after earthquake is a complex subject because the earthquake damage acts as an initial condition for the subsequent scenario. An investigation is performed here on a 10 story steel moment resisting structure designed to meet the life safety level of performance when different beam removal scenarios after earthquake are considered. To this end, the structure is first subjected to the design earthquake simulated by Tabas earthquake acceleration. The beam removal scenarios are then considered at different locations assuming that both ends connections of the beam to columns are simultaneously detached from the columns;thus the removed beam falls on the underneath floor with an impact. This imposes considerable loads to the structure leading to a progressive collapse in all the scenarios considered. The results also show that the upper stories are much more vulnerable under such scenarios than the lower stories. Hence, more attention shall be paid to the beam-to-column connections of the upper stories during the process of design and construction.

关键词： progressive collapse tall steel moment-resisting frames non-linear dynamic analysis beam-removal scenario impact