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Multi-objective optimal design of braced frames using hybrid genetic and ant colony optimization

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Frontiers of Structural and Civil Engineering 2016年第4期10卷 472-480页

作者： mehdi BABAEI Ebrahim SANAEI Department of Civil Engineering Faculty of Engineering University of Zanjan Zanjan 45371-38791 Iran

In this article, multi-objective optimization of braced frames is investigated using a novel hybrid algorithm. Initially, the applied evolutionary algorithms, ant colony optimization （ACO） and genetic algorithm （GA） are reviewed, followed by developing the hybrid method. A dynamic hybridization of GA and ACO is proposed as a novel hybrid method which does not appear in the literature for optimal design of steel braced frames. Not only the cross section of the beams, columns and braces are considered to be the design variables, but also the topologies of the braces are taken into account as additional design variables. The hybrid algorithm explores the whole design space for optimum solutions. Weight and maximum displacement of the structure are employed as the objective functions for multi-objective optimal design. Subsequently, using the weighted sum method （WSM）, the two objective problem are converted to a single objective optimization problem and the proposed hybrid genetic ant colony algorithm （HGAC） is developed for optimal design. Assuming different combination for weight coefficients, a trade-offbetween the two objectives are obtained in the numerical example section. To make the final decision easier for designers, related constraint is applied to obtain practical topologies. The achieved results show the capability of HGAC to find optimal topologies and sections for the elements.

关键词： multi-objective hybrid algorithm ant colony genetic algorithm displacement weighted sum method steelbraced frames

A novel mitigation measure for normal fault-induced deformations on pile-raft systems

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 15-33页

作者： Mohammadreza Jahanshahi Nowkandeh mehdi Ashtiani Faculty of Civil Engineering Babol Noshirvani University of TechnologyBabolIran

Evidence from recent earthquakes has shown destructive consequences of fault-induced permanent ground movement on *** observations have increased the demand for improvements in the design of structures that are dramatically vulnerable to surface fault *** this study a novel connection between the raft and the piles is proposed to mitigate the hazards associated with a normal fault on pile-raft systems by means of 3D finite element(FE)*** embarking on the parametric study,the strain-softening constitutive law used for numerical modeling of the sand has been validated against centrifuge test *** exact location of the fix-head and unconnected pile-raft systems relative to the outcropping fault rupture in the free-field is parametrically investigated,revealing different failure *** performance of the proposed connection for protecting the pile-raft system against normal fault-induced deformations is assessed by comparing the geotechnical and structural responses of both types of *** results indicate that the pocket connection can relatively reduce the cap rotation and horizontal and vertical displacements of the raft in most *** proposed connection decreases the bending moment response of the piles to their bending moment capacity,verging on a fault offset of 0.6 m at bedrock.

关键词： normal fault rupture failure mechanism pile-raft system pocket connection finite element modeling

Strain hardening behavior, strain rate sensitivity and hot deformation maps of AISI 321 austenitic stainless steel

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International Journal of Minerals,Metallurgy and Materials 2021年第11期28卷 1799-1810页

作者： mehdi Shaban Ghazani Beitallah Eghbali Department of Materials Science Engineering University of BonabBonab***Iran Faculty of Materials Engineering Sahand University of TechnologyTabriz51335-1996Iran

Hot compression tests were performed on AISI 321 austenitic stainless steel in the deformation temperature range of 800–1200℃ and constant strain rates of 0.001,0.01,0.1,and 1 s^(−1).Hot flow curves were used to determine the strain hardening exponent and the strain rate sensitivity exponent,and to construct the processing *** of the strain hardening exponent with strain were used to predict the microstructural evolutions during the hot *** variations were distinguished reflecting the different microstructural *** on the analysis of the strain hardening exponent versus strain curves,the microstructural evolutions were dynamic recovery,single and multiple peak dynamic recrystallization,and interactions between dynamic recrystallization and *** strain rate sensitivity variations at an applied strain of 0.8 and strain rate of 0.1 s^(−1) were compared with the microstructural *** results demonstrate the existence of a reliable correlation between the strain rate sensitivity values and evolved ***,the power dissipation map at the applied strain of 0.8 was compared with the resultant microstructures at predetermined deformation *** microstructural evolutions strongly correlated to the power dissipation ratio,and dynamic recrystallization occurred completely at lower power dissipation ratios.

关键词： strain hardening strain rate sensitivity processing map AISI 321 austenitic stainless steel hot compression

Design,development and evaluation of an online grading system for peeled pistachios equipped with machine vision technology and support vector machine

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Information Processing in Agriculture 2017年第4期4卷 333-341页

作者： Hosein Nouri-ahmadabadi Mahmoud Omid Seyed Saeid Mohtasebi Mahmoud Soltani Firouz Department of Agricultural Machinery Engineering Faculty of Agricultural Engineering and TechnologyUniversity of TehranKarajIran

In this study,an intelligent system based on combined machine vision(MV)and Support Vector Machine(SVM)was developed for sorting of peeled pistachio kernels and *** system was composed of conveyor belt,lighting box,camera,processing unit and sorting unit.A color CCD camera was used to capture *** images were digitalized by a capture card and transferred to a personal computer for further ***,images were converted from RGB color space to HSV color *** segmentation of the acquired images,H-component in the HSV color space and Otsu thresholding method were applied.A feature vector containing 30 color features was extracted from the captured images.A feature selection method based on sensitivity analysis was carried out to select superior *** selected features were presented to SVM *** SVM models having a different kernel function were developed and *** SVM model having cubic polynomial kernel function and 38 support vectors achieved the best accuracy(99.17%)and then was selected to use in online decision-making unit of the *** launching the online system,it was found that limiting factors of the system capacity were related to the hardware parts of the system(conveyor belt and pneumatic valves used in the sorting unit).The limiting factors led to a distance of 8 mm between the *** overall accuracy and capacity of the sorter were obtained 94.33% and 22.74 kg/h,respectively.

关键词： Pistachio kernel Sorting Machine vision Sensitivity analysis Support vector machine

Robust Control of Robotic Manipulators in the Task-Space Using an Adaptive Observer Based on Chebyshev Polynomials

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Journal of Systems Science & Complexity 2020年第5期33卷 1360-1382页

作者： GHOLIPOUR Reza FATEH Mohammad mehdi Department of Electrical and Robotic Engineering Shahrood University of Technology*** ShahroodIran

In this paper,an adaptive observer for robust control of robotic manipulators is *** lumped uncertainty is estimated using Chebyshev ***,the uncertainty upper bound is required in designing observer-controller ***,obtaining this bound is a challenging *** solve this problem,many uncertainty estimation techniques have been proposed in the literature based on neuro-fuzzy *** an alternative,in this paper,Chebyshev polynomials have been applied to uncertainty estimation due to their simpler structure and less computational *** on strictly-positive-rea Lyapunov theory,the stability of the closed-loop system can be *** Chebyshev coefficients are tuned based on the adaptation rules obtained in the stability ***,to compensate the truncation error of the Chebyshev polynomials,a continuous robust control term is designed while in previous related works,usually a discontinuous term is *** SCARA manipulator actuated by permanent magnet DC motors is used for computer *** results reveal the superiority of the designed method.

关键词： Adaptive observer Chebyshev polynomials electrically driven robot manipulators robust control uncertainty estimation

On subsurface box-shaped lined tunnel under incident SH-wave propagation

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Frontiers of Structural and Civil Engineering 2021年第4期15卷 948-960页

作者： mehdi PANJI Saeed MOJTABAZADEH-HASANLOUEI Department of Civil Engineering Zanjan BranchIslamic Azad UniversityZanjan45156-58145Iran

In this paper,a half-plane time-domain boundary element method is applied to obtain the seismic ground response,including a subsurface box-shaped lined tunnel deployed in a linear homogenous elastic medium exposed to obliquely incident *** the boundary around the tunnel is required to be *** prepare an appropriate model by quadratic elements,a double-node procedure is used to receive dual boundary fields at corners as well as change the direction of the normal *** encoding the method in a previously confirmed computer program,a numerical study is carried out to sensitize some effective parameters,including frequency content and incident wave angle for obtaining a surface *** depth and impedance ratio of the lining are assumed to be *** responses are illustrated in the time and frequency domains as two/three-dimensional *** results showed that subsurface openings with sharp corners distorted the propagation path of the anti-plane waves to achieve the critical states on the ground *** present approach can be proposed to civil engineers for preparing simple underground box-shaped models with angular boundaries.

关键词： box-lined tunnel half-plane BEM surface response SH-wave time-domain

Application of Bernstein polynomials for solving Fredholm integro-differential-difference equations

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Applied Mathematics(A Journal of Chinese Universities) 2022年第4期37卷 475-493页

作者： Esmail Hesameddini mehdi Shahbazi Department of Mathematics Sciences Shiraz University of TechnologyP.O.Box 71555-313ShirazIran

In this paper,the Bernstein polynomials method is proposed for the numerical solution of Fredholm integro-differential-difference equation with variable coefficients and mixed *** method is using a simple computational manner to obtain a quite acceptable approximate *** main characteristic behind this method lies in the fact that,on the one hand,the problem will be reduced to a system of algebraic *** the other hand,the efficiency and accuracy of the Bernstein polynomials method for solving these equations are *** existence and uniqueness of the solution have been ***,an estimation of the error bound for this method will be shown by preparing some ***,some numerical experiments are presented to show the excellent behavior and high accuracy of this algorithm in comparison with some other well-known methods.

关键词： Fredholm integro-differential-difference equation Bernstein polynomials existence and uniqueness error estimate

On the dynamically formed oxide films in molten Mg

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Journal of Magnesium and Alloys 2020年第1期8卷 219-230页

作者： Mohammad Mahdi Jalilvand mehdi Akbarifar mehdi Divandari Hassan Saghafian School of Metallurgy and Materials Engineering Iran University of Science and Technology(IUST)NarmakTehran16846-13114Iran

The so-called“Oxide/Metal/Oxide sandwich”method is one of the technique used to investigate the dynamic oxidation of metals which happens during the casting *** this study,characteristics of the oxide films formed on the molten magnesium in dynamic conditions have been investigated using the aforementioned *** air bubbles were released into the cast sample at the pressure of 0.2 atm through a quartz tube of 1 mm internal *** interface of two adjacent entrapped bubbles is considered as the Oxide/Metal/Oxide(OMO)*** sandwiches were characterized by the aid of the optical and scanning electron microscopy and also X-Ray diffraction *** different approaches,including measuring the width of the folds formed on the oxide films and the edge of the sandwiches,were used to estimate the thickness of the *** thicknesses were estimated to be in the range of 200 to 800 *** features such as fold,wrinkle,and crack were observed on the OMO *** the microscopic scale,the oxide films were rough and *** is attributed to the non-protective behavior of oxide *** XRD patterns indicated that the oxide films formed on the pure molten magnesium in dynamic conditions are crystallized MgO.

关键词： Dynamic oxidation Bifilm Magnesium Oxide films Casting defects

Analytical investigation of γN→N^*,Δ^* transition helicity amplitudes

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Chinese Physics C 2020年第7期44卷 157-166页

作者： Farhad Zolfagharpour mehdi Aslanzadeh Department of Physics Faculty of SciencesUniversity of Mohaghegh ArdabiliP.O.Box 179ArdabilIran

We study the structure of nonstrange baryons by analytically calculating the electromagnetic transition helicity amplitudes of the nucleon andΔ*** employ an improved hypercentral constituent quark model and obtain the corresponding eigenenergies and eigenfunctions in closed ***,we calculate the transverse and longitudinal helicity amplitudes for nucleon andΔ*** comparison of evaluated observables and experimental data indicates good agreement between the proposed model and available data.

关键词： helicity amplitudes nucleon and delta resonances transition form factors