In this paper we have studied the effect of magneto-static field on
propagation of thermal wave generated in metal by pulsed laser. In fact this interaction
generate acoustic wave in different mechanisms. However, always the common
mechanism in the interactions of laser pulse and metal is the thermo-elastic wave
generation. Applying the suitable magneto-static field on the surface of interaction of
laser pulse and metal can trap the propagation of thermal wave in thermo-elastic regime.
The physical mechanism of trapping and experimental results have investigated in this
paper. We obtained maximum reduction in 2D thermal wave propagation around
in simulation and around 5.3% by metallography. پرونده مقاله

Optically pumped helium magnetometers are important instruments which
have many applications in military, mass spectroscopy and space applications. In this
paper, the working principles of helium magnetometers have been explained. There is
also an introduction of a new method for finding the resonant frequency, which has
advantages to the typical method such as more sample rate possibility and realizing with
cheaper prices. پرونده مقاله

In this study, an experimental investigation on the synthesis method of a ferro-fluid was conducted in order to obtain a highly stable ferro-fluid. For this purpose, various surfactants are applied for colloidal stabilization among which tetra methyl ammonium hydroxide (TMAOH) showed the best performance. Several methods of characterization were chosen to characterize synthesized ferro-fluids such as Zeta potential and the particle size analysis by Dynamic Light Scattering (DLS). Based on the DLS results, the average diameter of Fe3O4 nano-particles was about 30 nm. Besides, the Zeta potential analysis was applied to investigate the stability of synthesized ferro-fluids. Moreover, the dynamic viscosity of the ferro-fluid is estimated at four different temperatures (20 oC, 35 oC, 50 oC, 65 oC). Based on the results, the ferro-fluid viscosity is decreased significantly by the temperature increase. Further, it is obvious that the viscosity of the ferro-fluid is decreased exponentially in terms of shear rate which determines its shear thinning (non-Newtonian) behavior. پرونده مقاله