فهرس المقالات Singularity

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  1 - Full structure of the thermal plasma including the ion isothermal drag
  M. Khoram S. F. Masoudi
  10.1007/s40094-019-00364-2
  AbstractIn order to study the ion temperature effect on the space-charge structure and the plasma variables on the wall, the ion thermal force has been added to the ion motion equation in the plasma fluidal model. In the eigenvalue problem of plasma, the plasma equation أکثر

  AbstractIn order to study the ion temperature effect on the space-charge structure and the plasma variables on the wall, the ion thermal force has been added to the ion motion equation in the plasma fluidal model. In the eigenvalue problem of plasma, the plasma equations are numerically solved in a whole area from the plasma center to the wall and it is displayed that the ion temperature has significant effects on the plasma structure and floating variables. However, the fluidal theory of plasmas introduces a singular point among the space charge of plasma boundary layer if the static pressure and the inertial mass of the thermal ions are taken into account at the same time. Finding a full numerical solution for the thermal plasma equations needs to cross the singular point. The singular point and how crossing the point will be depicted too. تفاصيل المقالة
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  2 - An Axisymmetric Torsion Problem of an Elastic Layer on a Rigid Circular Base
  B Kebli S Berkane F Guerrache
  10.22034/jsm.2019.1868197.1441
  A solution is presented to a doubly mixed boundary value problem of the torsion of an elastic layer, partially resting on a rigid circular base by a circular rigid punch attached to its surface. This problem is reduced to a system of dual integral equations using the Bo أکثر

  A solution is presented to a doubly mixed boundary value problem of the torsion of an elastic layer, partially resting on a rigid circular base by a circular rigid punch attached to its surface. This problem is reduced to a system of dual integral equations using the Boussinesq stress functions and the Hankel integral transforms. With the help of the Gegenbauer expansion formula of the Bessel function we get an infinite algebraic system of simultaneous equations for calculating the unknown function of the problem. Both the two contact stresses under the punch and on the lower face of the layer are expressed as appropriate Chebyshev series. The effects of the radius of the disc with the rigid base and the layer thickness on the displacements, contact stresses as well as the shear stress and the stress singularity factor are discussed. A numerical application is also considered with some concluding results. تفاصيل المقالة
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  3 - An Axisymmetric Contact Problem of a Thermoelastic Layer on a Rigid Circular Base
  F Guerrache B Kebli
  10.22034/jsm.2019.668619
  We study the thermoelastic deformation of an elastic layer. The upper surface of the medium is subjected to a uniform thermal field along a circular area while the layer is resting on a rigid smooth circular base. The doubly mixed boundary value problem is reduced to a أکثر

  We study the thermoelastic deformation of an elastic layer. The upper surface of the medium is subjected to a uniform thermal field along a circular area while the layer is resting on a rigid smooth circular base. The doubly mixed boundary value problem is reduced to a pair of systems of dual integral equations. The both system of the heat conduction and the mechanical problems are calculated by solving a dual integral equation systems which are reduced to an infinite algebraic one using a Gegenbauer’s formulas. The stresses and displacements are then obtained as Bessel function series. To get the unknown coefficients, the infinite systems are solved by the truncation method. A closed form solution is given for the displacements, stresses and the stress singularity factors. The effects of the radius of the punch with the rigid base and the layer thickness on the stress field are discussed. A numerical application is also considered with some concluding results. تفاصيل المقالة
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  4 - Analysis of Nanoplate with a Central Crack Under Distributed Transverse Load Based on Modified Nonlocal Elasticity Theory
  M Rajabi H Lexian A Rajabi
  10.22034/jsm.2020.1901736.1607
  In this paper, using the complete modified nonlocal elasticity theory, the deflection and strain energy equations of rectangular nanoplates, with a central crack, under distributed transverse load were overwritten. First, the deflection of nanoplate was obtained using L أکثر

  In this paper, using the complete modified nonlocal elasticity theory, the deflection and strain energy equations of rectangular nanoplates, with a central crack, under distributed transverse load were overwritten. First, the deflection of nanoplate was obtained using Levy's solution and consuming it; strain energy of nanoplate was found. As regards nonlocal elasticity theory wasn’t qualified for predicting the static behavior of nanoplates under distributed transverse load, using modified nonlocal elasticity theory, the deflection of nanoplate with a central crack for different values of the small-scale effect parameter was achieved. It was gained with the convergence condition for the complete modified nonlocal elasticity theory. To verify the result, the results for the state of the small-scale effect parameter were placed equal to zero (plate with macro-scale) and then were compared with the numerical results as well as the classical analytical solution results available in the valid references. It was shown that the complete modified nonlocal elasticity theory does not show any singularity at the crack-tip unlike the classical theory; therefore, the method presented is a suitable method for analysis of the nanoplates with a central crack. تفاصيل المقالة
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  5 - Analysis of a Functionally Graded Finite Wedge Under Antiplane Deformation
  A. R Shahani I Shakeri
  10.22034/jsm.2021.1897498.1577
  The antiplane deformation of a wedge made of a functionally graded material (FGM) with finite radius has been investigated analytically in the present article. In relation to the boundary conditions imposed on the arc portion of the wedge, displacement or traction, two أکثر

  The antiplane deformation of a wedge made of a functionally graded material (FGM) with finite radius has been investigated analytically in the present article. In relation to the boundary conditions imposed on the arc portion of the wedge, displacement or traction, two problems have been studied. In each of the problems three various kinds of boundary conditions (traction-displacement, displacement-displacement and traction-traction) have been applied to the radial edges of the wedge. The governing differential equations have been solved by employing finite Fourier transforms and Green’s function method. The closed form solutions for stress and displacement distribution have been achieved for the whole domain. Explicit relations have been extracted for the order of stress singularity in all cases. These relations indicated the dependence of the order of stress singularity on the boundary conditions, material property and wedge angle. In fact, despite of an isotropic wedge, for which the order of stress singularity depends only the geometry of the wedge, in an FG wedge the order of stress singularity depends both the geometry as well as the material property. تفاصيل المقالة
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  6 - Comparison of original and weighted singularity indexin separation of Pb- Zn mineralized zone in the Haft Savaran district, Central Iran
  Feridon Ghadimi Massume Khavari
  10.30495/ijes.2019.665321
  The Haft Saravan area is located in 90 km SE Arak in the central Iran. This area is a part of Malyer-Isfahan metallogenic belt. The article's objective is determining the most suitable method for identifying mineralized zones using original singularity and weighted sing أکثر

  The Haft Saravan area is located in 90 km SE Arak in the central Iran. This area is a part of Malyer-Isfahan metallogenic belt. The article's objective is determining the most suitable method for identifying mineralized zones using original singularity and weighted singularity methods in three-dimensional space. In weighted singularity method, mineralized zones have a greater volume relative to original singularity method. Coefficient of areal association showed that percentage of overlapping of two methods is less than 50% for Pb, Fe and Mn and less than 55% for Zn. Two methods were compared by modified singularity method in order to select the best method. Percentage of overlapping is more than 98% both original and modified singularity methods for Pb, Zn and Mn and is less than 45% for weighted singularity method. Therefore, it can be said that original singularity method is suitable relative to weighted singularity in identifying mineralized zones due to the high overlapping of original and modified singularity method. تفاصيل المقالة
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  7 - Underwater robot trajectory control using nonsingular terminal sliding mode controller
  Majid Shamsabadi Reihaneh Kardehi Moghaddam
  10.30495/ijsee.2021.684013
  Sliding mode control is one of the most effective methods of controlling nonlinear systems with bounded uncertainty. Exponential convergence of tracking error is one of the most important problem of classic sliding mode control. One way to solve this problem is use of t أکثر

  Sliding mode control is one of the most effective methods of controlling nonlinear systems with bounded uncertainty. Exponential convergence of tracking error is one of the most important problem of classic sliding mode control. One way to solve this problem is use of terminal sliding mode control. The great thing about terminal sliding mode control, is it’s robustness in face of model uncertainty and external disturbances while can guarantee tracking error converge to zero in finite time simultaneously. Usually terminal sliding mode controller, is limited by singularity at the origin and infinite control signal. This article attempts to the singularity problem in controlling underwater robots and decreasing the convergence time by defining a new sliding surface for terminal sliding mode controller. simulation results shows the efficiency of proposed controller as it effectively improves the convergence time and accuracy in under water robots with are faced by structural and environmental uncertainties. تفاصيل المقالة
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  8 - بررسی عوامل مؤثر بر مشارکت پذیری دانش آموزان از دیدگاه دبیران مدارس متوسطه اول دخترانه مناطق شمال شهر تهران
  شادی بنانی
  بررسی عوامل موثر بر مشارکت پذیری دانش آموزان از دیدگاه دبیران مدارس متوسطه اول دختران مناطق شمال شهر تهران ( بهار 97)شادی بنانیدکتر محمدنقی ایمانی گله پردسریچکیدههدف این تحقیق تعیین عوامل موثر بر مشارکت پذیری دانش آموزان از دیدگاه دبیران متوسطه اول شمال شهر تهران بوده ا أکثر

  بررسی عوامل موثر بر مشارکت پذیری دانش آموزان از دیدگاه دبیران مدارس متوسطه اول دختران مناطق شمال شهر تهران ( بهار 97)شادی بنانیدکتر محمدنقی ایمانی گله پردسریچکیدههدف این تحقیق تعیین عوامل موثر بر مشارکت پذیری دانش آموزان از دیدگاه دبیران متوسطه اول شمال شهر تهران بوده است. روش تحقیق از نظر شیوه جمعآوری اطلاعات، توصیفی(پیمایشی) و از نظر هدف، کاربردی است. جامعه اماری پژوهش شامل کلیه دبیران مدارس متوسطه اول دخترانه شمال شهر تهران (شامل مناطق آموزش و پرورش1و2و3و4) می باشد. که تعداد آنها 950 نفر می باشد. حجم نمونه با فرمول کوکران 274 نفر برآورد شده است و این تعداد با استفاده از روش نمونه گیری تصادفی خوشه ای و طبقه ای (براساس منطقه) از بین جامعه آماری انتخاب شده است. ابزار تحقیق پرسشنامه 54 گویه ای محقق ساخته بوده که نمره گذاری آن در مقیاس 5 درجه ای لیکرت صورت گرفته است. برای تعیین روایی از روایی صوری و محتوایی استفاده شده و برای اطمینان از پایایی پرسشنامهها نیز، آن را روی نمونه ای با حجم 30 نفر به صورت آزمایشی اجرا و پایایی آن با روش آلفای کرونباخ 85/0 برآوردگردیده است. تجزیه و تحلیل داده ها در دو سطح توصیفی و استنباطی به کمک نرم افزار SPSS صورت گرفته است. در سطح توصیفی از جدولهای فراوانی، نمودارهای متناسب با نوع دادهها، شاخص های شاخص های مرکزی، شاخص های پراکندگی و شاخص های توزیع داده ها استفاده شده و در سطح استنباطی از آزمون هایی چون K_S برای بررسی نحوه توزیع نمرات، آزمون t تفاصيل المقالة