In the present paper, we offer a new model studying the influence of an external centrifugal field and the heat transfer on a neutral gas confined between two parallel horizontal rigid stationary plane plates. The system of nonlinear differential equations is solved analytically. The temperature and concentration are calculated with a broad range of Knudsen numbers, centrifugal Mach number, and temperatures ratio parameter. We utilized the moment method with suitable boundary conditions. Thermodynamic predictions and internal energy change are examined. Results are applied for laboratory argon gas. Three-dimensional, two-dimensional, and contour plots graphics are drawn, and their manner is discussed.

In this work, a dynamical system of four bodies is constructed. The forces which govern the motion are mutual gravitational attractions of the primaries, and radiation pressure force emitted from the more massive body. The equations of motion for the four bodies have taken into account the radiation pressure. We have deduced that these equations can be solved by Laplace transformations; the eigenvalues are obtained to study the motion about the libration points which are taken from the classical method, then the stability around the libration points is studied. The results obtained are presented. We remark that this model has special importance in astrodynamics to send spacecraft to stable regions to move in gravitational fields for some planetary system.

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In the present work, the equations of motion of the solar sail are derived in the restricted three–body system. The dimensionless coordinates are used to obtain the solution of the problem. The Laplace transformations are used to solve these systems of equations to obtain the components of the solar sail acceleration. The motion about L2, L4 and its stability are studied under obalteness effects. The results obtained are in good agreement with previous results in this field. It is remarked that this model has special importance in space-dynamics to enabling spacecraft to do some maneuvers depends on the solar sail acceleration.