Self-propulsion of a spherical electric or magnetic microbot in a polar viscous fluid

Self-propulsion of a spherical electric or magnetic microbot in a polar viscous fluid.

The self-propulsion of a sphere immersed in a polar liquid or ferrofluid is studied on the basis of ferrohydrodynamics. In the electrical case an oscillating charge density located inside the sphere generates an electrical field that polarizes the fluid. The lag of polarization with respect to the electrical field due to relaxation generates a time-independent electrical torque density acting o...

Self-propulsion of a counter-rotating cylinder pair in a viscous fluid

Dynamics and Self-Propulsion of a Spherical Body Shedding Coaxial Vortex Rings in an Ideal Fluid

We describe a model for the dynamic interaction of a sphere with uniform density and a system of coaxial circular vortex rings in an ideal fluid of equal density. At regular intervals in time, a constraint is imposed that requires the velocity of the fluid relative to the sphere to have no component transverse to a particular circular contour on the sphere. In order to enforce this constraint, ...

a comparative study of the relationship between self-, peer-, and teacher-assessments in productive skills

تمایل به ارزیابی جایگزین و تعویض آن با آزمون سنتی مداد و کاغذ در سالهای اخیر افزایش یافته است. اکثر زبان آموزان در کلاس های زبان از نمره نهایی که استاد تعیین میکند ناراضی اند. این تحقیق جهت بررسی ارزیابی در کلاس های زبان انگلیسی به هدف رضایتمندی زبان آموزان از نمره هایشان انجام گرفته است که در آن نمرات ارائه شده توسط سه گروه ارزیاب (ارزیابی خود دانشجو، همسالان واستاد) در مهارت های تولید (تکل...

Spherical top-hat collapse of a viscous unified dark fluid

In this paper, we test the spherical collapse of a viscous unified dark fluid (VUDF) which has constant adiabatic sound speed and show the nonlinear collapse forVUDF, baryons, and dark matter, which are important in forming the large-scale structure of our Universe. By varying the values of the model parameters α and ζ0, we discuss their effects on the nonlinear collapse of the VUDF model, and ...