Recent content by Hassan2

Hello all, We might have observed that by tightening a string of a musical instrument, the natural frequency of the string changes. But I can not describe this phenomenon by the theory of linear elasticity. Also if we simulate the vibration of a bar with the help of structural software tools...

Thank you very much indeed. Your advice clarified many aspects of the job. I need to resist my manager's ambitions then.

Unlike in electromagnetics, the nonlinearity of mechanical structures is not only due to the material property. It could be due to large deformation and contact as well. Even though I will be implementing the existing and popular methods, I am still scared and I feel it is not a job that can be...

You would still need to follow some procedure to get the final expression but remember that your vector field depends on r only and in (1) it has one component only. So you only need to consider the derivation with respect to r. This makes the derivation much easier.

Be happy now! Your problem is simple. At first I though you have partial differential equations. Use the divergence formula in Cylindrical coordinate system( or Spherical depending on the definition of r). Also there are vector calculus identity for divergence of product of a vector vector...

Revise your equations first: In (1). a.r is a scalar and you have a dot product between this scalar and another r. In(2), the left-hand side is a scalar and right hand-side is a vector.

Nothing very clever here because I just summed up the partial field created by each moment. But since you seem to be well familiar with the physics of the problem, I would like to share with you more details: I do not really have magnetic moments in the problem. Instead, in a simplified version...

@Charles Link Yes, you got it right! The array is the result of discretizing an infinitely long rectangular prism whose edges are parallel with x, y, and z axis of Cartesian coordinate system. into cubic cells and. The prism is uniformly magnetized in x direction and I have excludes the field...

if a is a vector and w =a×∇b, then yes. w then is the magnetic field, a is a unit vector normal to x-y plane, b is the magnetic vector potential, and f(x,y) is the electric current density that creates the magnetic field.

While I was was numerically integrating the magnetic field caused by an infinite array of magnetic moments, I observed the interesting limit ( limit (1) in the image). It may seem difficult to prove it mathematically but from the physics point of view, I think it can be proved relatively...

Thank you qsal and your friend. I knew a little about the magnetic amplifiers but this time I read more on them. Some sort of saturable core devices are still in use and there are leading companies in China producing medium and high voltage motor soft starters based on the idea. At such...

Thanks for your effort to understand the problem, for your help, your corrections and clarifications. There is no rush and I only need to find out if applying a very strong but practical DC current in the DC coil causes a significant reduction in the inductance of AC coil . For the middle values...

Yes exactly how you described it.　 I have attached a figure illustrating the device. In the figure, cores 1 and 2 are the AC and DC ones respectively and they are coplanar. For comparison , another device could be made of one core only with the DC coil around another leg of the square core. The...

Thanks qsal for replying. Indeed your explanation is intuitive and helpful. But here, by magnetic field, I mean the so-called H-field. And to know what I mean by response in other direction, consider an inductance made up of a coil and a closed magnetic path with a very narrow air gap to...

Dear all, I have a question about magnetic saturation and I can't find any sources addressing my questions. I am relatively familiar with magnetic saturation and that the relative permeability of highly saturated iron becomes rather small. There are numerous sources with figures showing...