An Alternative Approach to the Static Spherically Symmetric, Vacuum Global Solution to the Einstein Equations

We propose an alternative description of the Schwarzschild black hole based on the requirement that the solution is static not only outside the horizon but also inside it. As a consequence of this assumption, we are led to a change of signature implying a complex transformation of an angle variable. There is a “phase transition” on the surface R=2m, producing a change in the symmetry as we cross this surface. Some consequences of this situation on the motion of test particles are investigated.

Study on Process Parameters on Single Point Incremental Forming of PVC

Effects of polyvinylchloride (PVC) sheet thickness (t), feed speed (υ), spindle speed (ω), Z-axis feed rate (p) and tool head diameter (Φ) as well as their interactions during the single point incremental forming (SPIF) on forming performance of the PVC sheet material were studied through an orthogonal experimental test. In this experiment, the angle-variable cone was used and the maximum forming limiting angle was taken as the experimental index. Results showed that and ω×Φ influence forming performance of PVC sheet material significantly. υ is the main influencing factor of SPIF performance of PVC sheet material. Small υ is good for sheet material forming. p and Φ are proportional to forming performance of sheet material. Over ω will cause material wear-out. Effect of t could be neglected.

Front and Back Movement Analysis of a Triangle-Structured Three-Wheeled Omnidirectional Mobile Robot by Varying the Angles between Two Selected Wheels

Omnidirectional robots can move in all directions without steering their wheels and it can rotate clockwise and counterclockwise with reference to their axis. In this paper, we focused only on front and back movement, to analyse the square- and triangle-structured omnidirectional robot movements. An omnidirectional mobile robot shows different performances with the different number of wheels and the omnidirectional mobile robot’s chassis design. Research is going on in this field to improve the accurate movement capability of omnidirectional mobile robots. This paper presents a design of a unique device of Angle Variable Chassis (AVC) for linear movement analysis of a three-wheeled omnidirectional mobile robot (TWOMR), at various angles (θ) between the wheels. Basic mobility algorithm is developed by varying the angles between the two selected omnidirectional wheels in TWOMR. The experiment is carried out by varying the angles (θ= 30°, 45°, 60°, 90°, and 120°) between the two selected omniwheels and analysing the movement of TWOMR in forward direction and reverse direction on a smooth cement surface. Respectively, it is compared to itself for various angles (θ), to get its advantages and weaknesses. The conclusion of the paper provides effective movement of TWOMR at a particular angle (θ) and also the application of TWOMR in different situations.

Stability of Subharmonic Oscillations in a Pipe Conveying Fluid under Harmonic Excitation

The existence and stability of subharmonic oscillations in a two end-fixed fluid conveying pipe whose base is subjected to a harmonic excitation are investigated. A Galerkin approach is utilized to reduce the equation of motion to a second order nonlinear differential equation. The conditions for the existence of subharmonic oscillations are given by using Melnikov method. The stability of subharmonic oscillations is discussed in detail by using action-angle variable and averaging method. It is shown that the velocity of fluid plays an important role in the stability of subharmonic oscillations.

Simulation and Analysis of Angle-Variable Linkage of Multi-Functional Mechanical Based on ADAMS

Based on the epidemic of multi-functional furnishing, this paper presents the design of an angle-variable linkage through introducing the movement and compositing of this mechanism, modeling as well as analyzing the motion, excising kinematics simulation to the key parts. The mechanism presented successfully deforms accurately and locks stably under various conditions, satisfying the functional requirements of multi-functional furnishing.