g. ahmadi
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Iranian Journal of Numerical Analysis and Optimization, Volume:14 Issue: 4, Autumn 2024, PP 1016 -1036Sinc numerical methods are essential approaches for solving nonlinear problems. In this work, based on this method, the sinc neural networks (SNNs) are designed and applied to solve the fractional optimal control problem (FOCP) in the sense of the Riemann–Liouville (RL) derivative. To solve the FOCP, we first approximate the RL derivative using Grunwald–Letnikov operators. Then, according to Pontryagin’s minimum principle for FOCP and using an error function, we construct an unconstrained minimization problem. We approximate the solution of the ordinary differential equation obtained from the Hamiltonian condition using the SNN. Simulation results show the efficiencies of the proposed approach.Keywords: Sinc Numerical Method, Neural Network, Sinc Neural Network, Pontryagin’S Minimum Principle, Fractional Optimal Control Problem
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In the present study, the Multi-Relaxation Time Lattice Boltzmann method (MRT-LBM) was employed to solve the airflow inside a scaled room model with dimensions of 0.914×0.457×0.305 m. This room model is considered a representative space with a 1:10 scale to an actual room. The selected room is equipped with a ventilation system. For optimizing the inlet and outlet locations of the airflow, 32 different positions in terms of length, width, and height for the inlet and 4 positions for the outlet were considered. The Taguchi method was utilized for optimizing the inlet and outlet locations, reducing the required number of experiments from 128 to 16. To assess the number of suspended particles, 86400 particles with a size of 1µm were injected into the room. Then, the particle behaviors were examined for a total duration of 60 seconds. The obtained results indicate that the location of the air conditioning system significantly influences the concentration of airborne particles responsible for disease transmission. Utilizing the Taguchi optimization method, optimal positions for the inlet and outlet air were determined to minimize the number of suspended particles in the room (the best position) and maximize it (the worst position).Keywords: Optimization, Airborne Particles, MRT-LBM, Taguchi Method
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هدف پژوهش حاضر ارایه مدل ساختاری تاثیر اخلاق حرفه ای و سرسختی شغلی بر تدریس خلاق معلمان بوده است. این پژوهش از نظر هدف کاربردی و از نظر روش توصیفی - همبستگی است. جامعه آماری پژوهش شامل همه معلمان ابتدایی شهرستان کرج به تعداد 4830 نفر بوده است. نمونه آماری بر اساس جدول کرجسی و مورگان (1970) به تعداد 350 نفر و به شیوه نمونه گیری تصادفی طبقه ای با توجه به جنسیت معلمان انتخاب شده است. برای گردآوری اطلاعات از پرسشنامه های سرسختی شغلی مورنو- خیمنز و همکاران (2014)، تدریس خلاقانه چان و یوین (2014) و اخلاق حرفه ای کانیزالس-وارگاس (2002) استفاده شده است. برای بررسی روایی ابزارها از روش تحلیل گویه و برای بررسی پایایی از آزمون آلفای کرونباخ بهره گرفته شده است. برای تجزیه و تحلیل داده ها از آزمونهای توصیفی شامل میانگین و انحراف معیار و آزمونهای استنباطی شامل همبستگی پیرسون و مدل معادلات ساختاری استفاده شده و همه تحلیلها با نرم افزارهای SPSSو Amos انجام گرفته است. نتایج نشان داد که تدریس خلاق با اخلاق حرفه ای (0/46 =r) و سرسختی شغلی (0/36 =r) رابطه ای مثبت، مستقیم و معنادار دارد (0/001≥P). تاثیر مستقیم اخلاق حرفه ای بر تدریس خلاق معلمان (0/45=β) و تاثیر مستقیم سرسختی شغلی بر تدریس خلاق معلمان (0/57=β) به دست آمد. سرسختی شغلی می تواند در رابطه میان اخلاق حرفه ای معلمان و تدریس خلاق آنان، نقش میانجی را ایفا کند. مقدار این تاثیر غیرمستقیم (0/13=β) به دست آمد. مقادیر شاخصهای برازش (0/95= GFIو 0/93= AGFI و 0/92= NFI و 0/94= CFI و 0/91= IFI و 0/93= TLI و 0/06= RMSEA) نشان داد که مدل ارایه شده از برازش مطلوبی برخوردار است.
کلید واژگان: اخلاق حرفه ای, سرسختی شغلی, تدریس خلاق, معلمانTo encourage creativity in teaching, factors helping with its development need to be identified and strengthened. To this end the impact of professional ethics and occupational endurance on creativity in teaching was explored through analyses of data gathered from a randomly selected sample of 350 elementary school teachers utilizing appropriate instruments with assumed validity and reliability. Results show that creative teaching is positively correlated with both professional ethics (r=0.46) and occupational endurance (r= 0.36, P<0.001). Direct impact of both factors was relatively high (0.45 and 0.57, respectively). Further analyses revealed that the constructed model is of desirable goodness of fit.
Keywords: professional ethics, occupational endurance, creative teaching, teachers -
With the advent of various advanced materials, the idea of flying like birds has attracted considerable attention in recent years. In addition, aeroacoustics has become an important issue and is being widely studied. In this work, based on the shape of Owls’ wings, an attempt was made to improve the aeroacoustic and aerodynamic performances of conventional aircraft wings. For this purpose, wings with different elements, namely, square, triangular, and semicircular, on their top surface were examined. In addition, three different spatial distributions of the elements according to the Owl’s wings shape were considered. For incompressible airflow, aerodynamic and aeroacoustic parameters of wing with structured surfaces were investigated. Also, a wing with serrations was examined. The results indicate that wings with elements distributed starting from maximum section thickness and continuing up to the trailing edge are the most suitable case for both aerodynamic and aeroacoustic improvements. On the other hand, a two-sided serrated wing and a serrated wing in the trailing edge reduce the sound level significantly. In addition, the use of both elements and serrations delays wing stall and thus markedly increases the maximum lift coefficient.Keywords: Aeroacoustics, Aerodynamics, UAVs, Owl, Wing with structured surfaces
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Scientia Iranica, Volume:28 Issue: 5, Sep-Oct 2021, PP 2479 -2492Flow in river bends is associated with generation of secondary flows that leads to a rather complicated flow pattern around bridge piers located in the bend. In this study, the flow patterns around rectangular and oblong piers models with collar located at the 90o angle of a 180-degree sharp bend in an experimental plume were investigated. The 3D flow velocity data were collected using a Vectrino velocimeter. The experimental results indicated that the presence of the rectangular pier caused more intense deviation of the streamlines towards the outer bank of the bend. Furthermore, installation of the oblong pier, the maximum secondary flow power and angular velocity were decreased, respectively, by 35% and 45% in comparison with the installation of the rectangular pier. In addition, it was found that the maximum turbulence kinetic energy around the two piers was not significantly different, but by installing the rectangular pier, a region with high values of turbulence kinetic energy is formed at 90° near the inner bank. Also, installation of oblong pier reduces the values of shear stress in comparison with the use of the rectangular pier.Keywords: Flow Patterns, 180 Degree Sharp Bend, Oblong Pier, Rectangular Pier, Turbulence Kinetic Energy
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قرن بیستم را می توان قرن رویکردهای جنسیتی به شمار آورد. از جنبشهای تندرو و یک طرفه تا تفکرات میانه رو و بی طرف درباره جنسیت، پیرامون بشر قرن گذشته را احاطه کرده بود که البته خاستگاه همگی دستیابی به عدالت جنسیتی بوده است، اما هرکدام به مثابه تعریف متفاوت از عدالت به رویکردی متفاوت دست یافته اند. برنامه درسی نیز از این قاعده مستثنی نبوده و نیست. هدف از پژوهش حاضر، تنظیم یک پیوستار از رویکردهای جنسیتی است که تاکنون در جهان مطرح بوده اند تا بتوان از این طریق به خلا موجود در میان این پیوستار دست یافت، چرا که به نظر می رسد هیچ یک از رویکردهای مطرح نتوانسته است پاسخی کامل به مسئله نوع برخورد به جنسیت در برنامه درسی ارایه کند. پژوهش حاضر از نوع کیفی و به شیوه توصیفی- تحلیلی است که با استفاده از روش ترکیب سازوار (ترکیب نظریه های مختلف) در پنج گام و با رعایت اصل عدم همجواری پاره های ناهمخوان صورت گرفته است. پس از تجزیه و تحلیل یافته های پژوهشی و شناخت خلا موجود، با هدف ایجاد توازن در پیوستار رویکردهای جنسیتی در دو گروه اصلی تفکیکی و غیرتفکیکی، به نظر می رسد، «آموزش هوشیار به جنسیت» برگرفته از مبانی دینی و نگاه اسلامی به موضوع جنسیت و دلالتهای آن در موضوع آموزش مبتنی بر اهداف هوشمندانه و برنامه ریزی شده پنهان و غیرصریح، می تواند پاسخی بر نوع تفکر عدالت- محور به مساله جنسیت باشد. در پایان، مجموعه ای از دلالتها بر رویکرد هوشیار به جنسیت در برنامه درسی ارایه شده است تا بتواند مقدمه ای بر طراحی چنین برنامه درسی باشد.
کلید واژگان: جنسیت, آموزش, رویکردهای جنسیتی, هوشیار به جنسیتThe twentieth century can be considered the century of gender approaches. From extremist and one-sided movements to moderate and neutral schools of thought about gender, which have surrounded the last century and all of them had originated in achieving gender justice, but each has taken a different approach as a different definition of equity. The curriculum is no exception to this rule. The purpose of the present study is to compile a continuum of gender approaches that have been proposed in the world so far in order to bridge the gap between these continuums, because it seems that none of the proposed approaches has been able to provide a complete answer to the issue of gender attitudes in the curriculum. The present study is a qualitative research type and based on a descriptive-analytical method which has been performed by using the method of consistent combination (combination of different theories) in five steps through observing the principle of non-adjacency of inconsistent parts. After analyzing the research findings and recognizing the existing gap, with the aim of creating a balance in the continuum of gender approaches in the two main groups of segregation and non-segregation, it seems that "gender-oriented education" which is derived from religious principles and Islamic view of the issue of gender and its implications for the subject of education based on intelligent, hidden, and implicitly planned goals, can be an answer to the type of equity-oriented thinking on the issue of gender. Finally, a set of implications for a gender-oriented approach to curriculum is provided as an introduction to the design of such a curriculum.
Keywords: gender, education, gender approaches, gender-oriented education -
The aim of this paper is to study the deposition and dispersion of nano particles in fully developed laminar pipe flows numerically. To simulate particle transport and to locate the position of particles, the Eulerian - Lagrangian method is used under the conditions of one-way coupling. Due to studied range of particle diameters from 5 nm to 100 nm, the main effective force for particle deposition is the Brownian diffusion force. After studying the mesh independency and validating results, time history analysis of particle transport is also performed by injecting the particles from the inlet surface and tracking them at each moment. Furthermore, the effective parameters, i.e. particle diameter, pipe length and diameter, temperature and particle density are studied comprehensively. The results of time history analysis of particle transport show that nano particles with less diameters are more deposited in less time. Furthermore, maximum number of escaped particles from the pipe occurred at 0.035 s after injecting the particles for all studied particle diameters due to the studied flow rate and length of the pipe. The output of this study can provide a guideline for evaluating nano particle transport and deposition in fully developed laminar pipe flows.Keywords: Two Phase Gas – Solid Flow, Nano Particles, Particle Deposition, Fully Developed Laminar Flow, Lagrangian Particle Tracking
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