The present status of research on the generation of spiral patterns in the responsive density wave theory is discussed. The latter is based on a conjecture of symmetry breaking in the equations of motion of stellar orbits in differentially rotating stellar disks by an oval perturbation growing with time. Analytical approaches based on first-order epicyclic approximation as well as computer experiments are performed to investigate the consequences of this working hypothesis.
In the case of the 30 ns long laser pulses the jitter of distances of the pulse centers of mass is less than the jitter of distances when using the threshold discriminator. The paper describes an analog case of determination of the pulse center of mass.
The object of this paper is a microprocessor based control unit of step motors. This single-board unit controls simultaneously two step motors. Required data are supplied by the supervisor computer. New continous satellite tracking algoritmus is used. The maximum speed of the motors (with 800 steps/turn) is 1.2 turns/sec. This unit may be used as inherent part of the laser radar electronic system. The unit allows a small operator corrections in aiming during the satellite tracking.