Spherically Symmetric Solution in (1+4)-Dimensionalf(T)Gravity Theories

A nondiagonal spherically symmetric tetrad field, involving four unknown functions of radial coordinaterplus an angleΦ, which is a generalization of the azimuthal angleϕ, is applied to the field equations of (1+4)-dimensionalf(T)gravity theory. A special vacuum solution with one constant of integration is derived. The physical meaning of this constant is shown to be related to the gravitational mass of the system and the associated metric represents Schwarzschild in (1+4)-dimension. The scalar torsion related to this solution vanishes. We put the derived solution in a matrix form and rewrite it as a product of three matrices: the first represents a rotation while the second represents an inertia and the third matrix is the diagonal square root of Schwarzschild spacetime in (1+4)-dimension.

Vacuum Ball-Collector

A lot of ping-pong balls may fall on ground round the ping-pong table, whenever people take part in the ping-pong sport,. In order to collect them conveniently, this paper puts forward a new method that applies aerodynamic principles. By vacuum, ping-pong balls are collected into the collecting box. The special vacuum ball-collector is designed and made. The results show that ball-collector is better than current other ping-pong ball-collectors at time and work. It has broad application worth.

Parallel Cooperation of Robots during Handling with Jumbo Glass Sheets

In the study, the mechanical behaviour of the robot, end effector – object – end effector, robot system is analyzed in terms of external forces affecting robots and their grippers as well as deformation forces influencing on the glass sheet through grippers provided that the robot kinematical structure and vacuum gripping head form an absolutely rigid system. The solution results are stress fields in the glass sheet, requirements for the robot path accuracy, and recommendations for solving special vacuum grippers for this type of robotic handling.

MASSLESS SPINNING TEST PARTICLES IN ALGEBRAICALLY SPECIAL VACUUM SPACE–TIMES

The motion of massless spinning test particles is investigated using the Newman–Penrose formalism within the Mathisson–Papapetrou model extended to massless particles by Mashhoon and supplemented by the Pirani condition. When the "multipole reduction world line" lies along a principal null direction of an algebraically special vacuum space–time, the equations of motion can be explicitly integrated. Examples are given for some familiar space–times of this type in the interest of shedding some light on the consequences of this model.

ON THE UNIQUENESS OF STRING THEORY

We show that bosonic strings may be viewed as a particular class of vacua for N=1 superstrings, and N=1 superstrings may be viewed as a particular class of vacua for N=2 strings. Continuing this line of string hierarchies, we are led to search for a universal string theory which includes all the rest as a special vacuum selection.