# مقالههای A Heidari

**توجه:**محتویات این صفحه به صورت خودکار پردازش شده و مقالههای نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده میشوند.

##### ۱Constrained Optimization of the Submerged Arc Welding Process of Oil and Gas Pipes by TAANGA Method

اطلاعات انتشار:
دومین کنفرانس لوله و صنایع وابسته،
سال ۱۳۸۸

تعداد صفحات:
۱۰

Submerged arc welding (SAW) is used extensively in industry to join metals in the manufacture of pipes of different diameters and lengths. The main problem faced in the manufacture of pipes by the SAW process is the selection of the optimum combination of input variables for achieving the required qualities of weld. This problem can be solved by the development of mathematical models through effective and strategic planning and the execution of experiments. The main aim of this study is to optimize the welding process to reduce the residual stresses of the welded pipes. So a new combined method which is named TAANGA (Taguchi‐ANn‐GA) is used for optimization. This method is combination of taguchi method in design of experiment (DOE), artificial neural network (ANN) and genetic algorithm (GA). Taguchi method was used for better training of neural network.The orthogonal array L' 32 from taguchi standard arrays was chosen. Then according to this array by use of finite element model training data was produced. A neural network is used to construct the relationships between welding process parameters and residual stresses in submerged arc welding. An optimization algorithm called genetic algorithm is then applied to the network for searching theprocess parameters with an optimal residual stresses. Results show very much reduction in maximum welding residual stress using this new method.<\div>

##### ۲Modeling of MSMPR Potassium Nitrate Crystallizer

اطلاعات انتشار:
ششمین کنگره بین المللی مهندسی شیمی،
سال ۱۳۸۸

تعداد صفحات:
۶

In this research modeling of batch Mixed Suspension Mixed Product Removal (MSMPR) KNO3 crystallizer in aqueous solution is derived based on population balance approach. Governing equations is solved by moment method. Modeling results for second moment and system supersaturation are validated by experimental data during operation time. Particle Size Distribution (PSD) of crystals during the process is evaluated by use of Log–Normal distribution function from moments values. The changes in PSD behavior in the crystallizer during the time on basis of operation conditions, nucleation and growth terms effects are discussed.<\div>

##### ۳Removal of C.I. Acid Blue 25 from contaminated water by adsorption onto hardened paste of Portland cement as a lowcost adsorbent

اطلاعات انتشار:
سومین همایش ملی آب و فاضلاب با رویکرد بهره برداری،
سال ۱۳۸۸

تعداد صفحات:
۶

The present study was carried out to investigate the potencial of hardened paste of Portland cement (HPPC) as a low–cost adsorbent for the removal of Acid Blue 25 (AB 25) from contaminated water by using batch adsorption studies. In this work HPPC has been selected as adsorbent because of the main advantages such as high efficiency, simple separation of sludge,abundant availability and low–cost material. The removal of dye in aqueous medium through the process of adsorption with HPPC under a set of variables (contact time, initial dye concentration, adsorbent dosage and temperature) has been investigated. Results showed that removal of AB 25 increased with increasing adsorbent dosage, temperature, contact time and initial dye concentration decreasing and having 100 percent removal of dye over 75 min. From the experimental results, it may be concluded that HPPC was an efficient and economical adsorbent for AB 25 removal.<\div>

##### ۴Removal of Direct Red 23 From Contaminated Water Using Chitosan As a Polymeric Bioadsorbent by Adsorption Process

اطلاعات انتشار:
سومین همایش ملی آب و فاضلاب با رویکرد بهره برداری،
سال ۱۳۸۸

تعداد صفحات:
۷

The present study was carried out to investigate the effect of chitosan for the removal of Direct Red 23 (DR 23) from contaminated water in comparison with activated carbon by using batch adsorption studies. In present study chitosan has been selected as adsorbent because of advantages such as high adsorption capacity, potential of variety of pollutants removal, non toxic, abundant availability and low cost and high rate of adsorption. Also the effect of contact time, initial dye concentration, adsorbent dosage, temperature and pH were examined and then removal efficiency of chitosan as compared activated carbon has investigated. Results showed that removal of dyes increased with increasing contact time, adsorbent dosage, temperature and dye initial concentration decreasing. Also it may be concluded that chitosan was more efficient than activated carbon.<\div>

##### ۵THERMAL CONDUCTIVITY OF FUNCTIONALIZED MULTI–WALLED CARBON NANOTUBE\EPOXY COMPOSITES

اطلاعات انتشار:
دومین کنفرانس بین المللی کامپوزیت،
سال ۱۳۸۹

تعداد صفحات:
۶

Functionalization of multi–walled carbon nanotubes (MWCNTs) with benzene tricarboxylic acid (BTC) was conducted by using direct friedel–craft acylation. The friedel–craft modification was used to functionalize MWCNTs effectively and without damaging the carbon nanotubes (CNTs) surface. Epoxy–based nanocomposites reinforced with CNTs with and without functionalization were prepared by mechanical mixing and ultrasonication of BTC–MWCNTs and epoxy resin in tetrahydrofuran, followed by a cross–linking reaction with a curing agent. The changes of surface properties of MWCNTs were investigated using FTIR and thermogravimetric analysis. The effect of MWCNT functionalization and their weight percentage on the thermal conductivity of epoxy nanocomposites also were investigated. The results showed that grafting BTC molecules onto multi–walled carbon nanotubes surface improved the dispersion and solubility of carbon nanotubes in epoxy matrix. It is found that the addition of BTC–MWCNTs increases both the thermal and electrical conductivity of epoxy nanocomposites in comparison to Pristine–MWCNT<\div>

##### ۶Approximation of Seismic Earth Pressure on Retaining Wall by Artificial Neural Network

نویسنده(ها):
A Heidari

اطلاعات انتشار:
ششمین کنفرانس بین المللی زلزله شناسی و مهندسی زلزله،
سال ۱۳۹۰

تعداد صفحات:
۷

Estimation of the seismic earth pressure is an important topic of research for the safe design of retaining wall in the seismic zone. Design of retaining wall needs the complete knowledge of earth pressures for both active and passive conditions. In the present work, the seismic earthpressure on retaining wall is calculated by artificial neural network (ANN). It is a common practice to consider the seismic accelerations in both horizontal and vertical directions in terms of equivalent static forces. Force–based analysis is used to compute seismic earth pressure. Then the ANN is created and the seismic earth pressures are evaluated at any conditions. A significant benefit of the ANN is its ability to learn relationships between variables with repeated exposure to those variables. Therefore, instead of deriving an analytical relationship from mathematical formulations, the ANN learns the relationship through an adaptive training process. Numerical example shows the merit of the ANN.<\div>

##### ۷Analysis of Chatter in Tandem Rolling Mills based on Tresca Model

اطلاعات انتشار:
کنفرانس دو سالانه بین المللی مکانیک جامدات تجربی،
سال ۱۳۹۲

تعداد صفحات:
۹

During the cold rolling of thin strips, undesired mechanical vibration, generally referred to as chatter, is often observed. It causes unacceptable gauge variation to the strip and its surface finish. It has also been found that as the rolling speed is increased, the system goes to instability. As the need for low–cost and high–quality products increases, prevention of chatter phenomenon becomes an important task in the rolling industry. To overcome this phenomenon a deep understanding of the cause of chatter is required. In this research, a chatter model in tandem rolling mills based on the friction factor or Tresca model is proposed. To study chatter in rolling, it is necessary to set up models for the rolling process as well as the mill stand. The model relaxes certain assumptions by considering the influence of the material strain–hardening effect and the elastic deformation of the work roll. The results of the simulation are verified by comparing to experimental data obtained from a full scale industrial mill. The main chattering characteristic, i.e., the critical rolling speed, obtained from the simulation program has been found to be in good agreement with that of the experimental measurements.<\div>

##### ۸Analysis of Chatter in Tandem Rolling Mills based on Coulomb Model

اطلاعات انتشار:
کنفرانس دو سالانه بین المللی مکانیک جامدات تجربی،
سال ۱۳۹۲

تعداد صفحات:
۹

Cold rolling is the most vital process in manufacturing flat sheet products. During the cold rolling of thin metal sheets, undesired mechanical vibrations, generally referred to as chatter, are often generated. It usually lowers the surface finish of the sheet and in some cases causes gauge variation. It may also cause severe damage to the rolling mill and strip rupture under extreme conditions. In this research, a chatter model in tandem rolling mills is proposed based on the friction coefficient model or the Coulomb model. To study chatter in rolling, it is necessary to set up models for the rolling process as well as the mill stand. The model relaxes certain assumptions, by considering the influence of the material strain–hardening effect and the elastic deformation of the work roll. The results of the simulation are verified by comparing to experimental data obtained from a full scale industrial mill. The main chattering characteristic, i.e., the critical rolling speed, obtained from the simulation program has been found to be in good agreement with that of the experimental measurements.<\div>

##### ۹Comparison of equivalent linear and nonlinear ground response analysis methods in the time domain

اطلاعات انتشار:
سومین کنفرانس بین المللی پژوهشهای کاربردی در مهندسی عمران، معماری و مدیریت شهری،
سال ۱۳۹۴

تعداد صفحات:
۷

Earthquake resistant design is an important consideration for designing structures in seismic prone areas.On the other hand to get the design earthquake motion at the ground surface or at the foundation of a structure, engineers need to make a seismic site response analysis.The motion equation is a secondorder propagation type of equation. This equation can be solved in either frequency domain or time domainQUAKE\W is a geotechnical finite element software product used for the dynamic analysis of earth structures subjected to earthquake shaking and other sudden impact loadingThis softwaresolvesthe equation of motion in the time domain by integrating in a small time incrementInthis paper, the Coyote Lakeproblem is simulated by the softwareThis modeling iscarried out withoutanyboundary conditions and only by enough increasing the width of the soillayers.The analyses were done by equivalent linear and nonlinear methods.The peak ground acceleration and response spectrum at the ground surface are determined by the two approaches for the site.Comparison of the results shows that the nonlinear approach predicts closer response to real recorded datawith respect equivalent linear.<\div>

نمایش نتایج ۱ تا ۹ از میان ۹ نتیجه