Dimian is Associate Professor in Electrical
Engineering and Computer Science Department at “Stefan cel
His research in the area of magnetic recording is focused on viable alternatives to the magnetization reversal, both in traditional longitudinal magnetic media and in its promising alternatives: perpendicular media and nanoparticulate media. He offered a rigorous comparison of the main characteristics, such as critical field and switching time, for damping and precessional switchings and designed magnetic field pulses for precessional switching by using the direct and inverse methods He applied perturbation and multi-scale methods for the evaluation of dissipative effects and relaxation phenomena.
Another direction of his research is the analysis of nonlinear systems with hysteresis driven by stochastic processes. The behavior of hysteretic system affected by thermal fluctuations or noise can be described as a nonlinear hysteretic transformation of stochastic input. One of his main results in this area was the spectral analysis of hysteretic systems. The developed method takes full advantage of the fact that numerous hysteretic nonlinearities can be constructed trough Preisach formalism as a weighted superposition of rectangular loop operators that are individually driven by the same stochastic process. Then the mathematical theory of stochastic processes on graphs is used to circumvent the difficulties related to the fact that outputs of hysteretic systems are not Markovian processes. Due to the universality of Preisach model and the general form of the input process, the method can be applied for the calculation of spectral densities for hysteretic nonlinearities of various physical origins (such as magnetism, superconductivity, mechanical structures, and shape-memory alloy)
A special interest in his research is devoted to the surface effects that have a strong bearing on nanoparticle properties. In order to describe these contributions, he uses a multi-spin model of a nanoparticle which is capable of distinguishing among various atomic environments. The multi-spin dynamics is modeled by Landau-Lifshitz type equations for each spin while the effective field is derived from a Dirac-Heisenberg Hamiltonian. He had analyzed the quasi-static and dynamic properties of magnetic nanoparticles and had illustrated their dependence on various physical parameters considered in the problem.
In addition to the above mentioned directions, his research experience also includes topics related to the landmine detection using hyperspectral images, human detection using infrared cameras, terahertz-wave technology, and noise and fluctuations in semiconductor devices.