MAGNETIC activity of one or both components of close binary systems can cause orbital period variation of the systems.Variation in gravitational quadropole moment will change the orbital period of the systems. In this article, we suppose that MAGNETIC FIELD is poloidal-troidal according to dynamo theory, and finds its relation with period change in the systems.

Introduction:MAGNETIC FIELDs are capable of altering the trajectory of electron beams andcan be used in radiation therapy. Theaim of this study was to produce regions with dose enhancement and reduction in the medium.Materials and Methods:The NdFeB permanent magnets were arranged on the electron applicator in several configurations. Then, after the passage of the electron beams (9 and 15 MeV Varian 2100C/D) through the non-UNIFORM MAGNETIC FIELD, the Percentage Depth Dose (PDDs) on central axis and dose profiles in three depths for each energy were measured in a 3D water phantom.Results:For all magnet arrangements and for two different energies, the surface dose increment and shift in depth of maximum dose (dmax) were observed. In addition, the pattern of dose distribution in buildup region was changed. Measurement of dose profile showed dose localization and spreading in some other regions.Conclusion:The results of this study confirms that using MAGNETIC FIELD can alter the dose deposition patterns and as a result can produce dose enhancement as well as dose reduction in the medium using high-energy electron beams. These effects provide dose distribution with arbitrary shapes for use in radiation therapy.

In this research, the behaviour of a single droplet of the dielectric FIELD under the effect of the applied external UNIFORM MAGNETIC FIELD has been investigated. Previously, it was thought that no force is applied to the dielectric fluids when exposed to the UNIFORM MAGNETIC FIELD. A stagnant droplet in a quiescent fluid column was considered in order to determination of the net effect of the applied UNIFORM MAGNETIC FIELD. Considering that the droplet behaviour has been investigated in the horizontal plane, the net effect of the gravity on the droplet and the surrounding fluid is also zero. Therefore, any change in the condition of the considered droplet will be due to the effect of the applied MAGNETIC FIELD. Numerical analysis has been used to perform this research. The governing equations of the problem are the continuity, momentum, level set equations for interface simulation, re-initialization and re-construction equations of the level set equations to control the mass dissipation of this method. The governing equations have been discretized and solved by developing code in the Fortran programming environment. The behaviour of the considered droplet in various regimes has been investigated under the different magnitudes of the applied MAGNETIC FIELD. The results of the research in various cases show that stagnant droplet deforms under the effect of the applied MAGNETIC FIELD and starts to vibrate which also induces the motion in the surrounding quiescent fluid.

In this study, the Least Square Method (LSM) is a powerful and easy to use analytic tool for predicting the temperature distribution in a porous fin which is exposed to UNIFORM MAGNETIC FIELD. The heat transfer through porous media is simulated using passage velocity from the Darcy’s model. It has been attempted to show the capabilities and wide-range applications of the LSM in comparison with a type of numerical analysis as Boundary Value Problem (BVP) in solving this problem. The results reveal that the present method is very effective and convenient, and it is suggested that LSM can be found widely applications in engineering and physics.

We theoretically demonstrate the interplay of UNIFORM spin-orbit coupling and UNIFORM Zeeman MAGNETIC FIELD on the topological properties of one-dimensional double well nano wire which is known as Su-Schrieffer-Heeger (SSH) model. The system in the absence of Zeeman MAGNETIC FIELD and presence of UNIFORM spin-orbit coupling exhibits topologically trivial/non–trivial insulator depending on the hopping amplitudes and spin-orbit coupling strength. Topological phases of this system can be determined by integers Z which are related to the Zak phase of occupied Bloch bands. In the phase diagram, there are three different regions with topologically distinct phases. The system is non-trivial insulator in two of them whereas one of the regions is related to the topologically trivial insulator. We find that the topologically trivial phase in the presence of both UNIFORM spin-orbit coupling and UNIFORM Zeeman MAGNETIC FIELD changes to a topologically non-trivial phase. The number of symmetry protected zero-energy edge states under open boundary conditions are also calculated, which suggest that the topological number Z reduces to the Z2 when applying Zeeman FIELD. Furthermore, the symmetries of the Hamiltonian are investigated, implying that the system has time-reversal, particle-hole, chiral and inversion symmetries and belongs to the BDI class either in the presence or absence of UNIFORM Zeeman MAGNETIC FIELD.

The purpose of the present study is to investigate the boundary layer separation point in a magnetohydrodynamics diffuser. As an innovation, the Re value on the separation point is determined for the non-Newtonian fluid flow under the influence of the non-UNIFORM MAGNETIC FIELD due to an electrical solenoid, in an empirical case. The governing equations including continuity and momentum are solved by applying the semi-analytical collocation method (C.M.). The analysis revealed that for specific values of De from 0.4 to 1.6, α from 20o to 2.5o and Ha from zero to 8, the Re value on the separation point is increased from 52.94 to 1862.78; thus, the boundary layer separation postponed. Furthermore, the impact of the MAGNETIC FIELD intensity on the separation point is analyzed from the physical point of view. It is observed the wall shear stress increases by increasing MAGNETIC FIELD intensity that leads to delaying the boundary layer separation.

The propagation of nonlinear waves such as ion acoustic, electron acoustic, dust acoustic in the plasma media have been studied in different equilibrium and non-equilibrium conditions. Meanwhile, the study of these waves in magnetized plasmas, due to the effect of the external MAGNETIC FIELD on the plasma with different angles of wave propagation has been less addressed. There are extensive studies on the propagation of acoustic waves in magnetized plasma, which show that when the intensity of the MAGNETIC FIELD is constant, these waves propagate as soliton waves with a stable profile in the plasma. In fact, the UNIFORM MAGNETIC FIELD does not interfere with the fluctuations of the plasma particles to produce dilute and dense regions and wave propagation, and for this reason, the harmonic soliton wave is propagated in the plasma. We know factors such as heating, particles collision and viscosity that cause perturbation in plasma particles fluctuations. In this situation, the propagation of the acoustic wave will no longer be in the soliton form and a shock wave may appear. On the other hand, we know that in actual conditions, the MAGNETIC FIELD governing laboratory plasmas such as tokamaks and also astrophysical and space plasmas are not constant at all. As a realistic example, the Earth's MAGNETIC FIELD intensity varies from 30000 nT in 0 (latitude): +60 (altitude) to 45000 nT in 10 (latitude): +90 (altitude), where the MAGNETIC FIELD is almost horizontal. Therefore it would interesting to study the presence of a non-UNIFORM MAGNETIC FIELD. For this purpose, we considered an ion-electron magnetized plasma model and numerically investigate the ion acoustic wave behavior in this medium, while the strength of the MAGNETIC FIELD is not the same in different parts of the plasma. In this situation, for simplicity in calculations, we assume the direction of the MAGNETIC FIELD to be constant. We use the second order Runge-Kutta method and by numerically solving the basic equations of the ion acoustic wave, it is shown that the stable behavior of the solitonic wave is perturbed in the presence of varying MAGNETIC FIELD and in this case, the wave propagates as a shock wave. Now we can introduce the non-UNIFORM MAGNETIC FIELD along with factors such as viscosity, heating, collision etc. as the new sources of producing the acoustic shock waves in plasmas. We also studied the cases where the collisional terms and gyro frequencies of the particles are considered. In this condition, the effects of the non-UNIFORM MAGNETIC FIELD are different. This subject can also be considered for other acoustic waves in different temperature and density models, various non-thermal plasmas and other features in astrophysical and laboratory plasmas.