Longitudinal Transverse Direction Research Articles

Boundary Vibration Control of Variable Length Crane Systems in Two-Dimensional Space With Output Constraints

A variable length crane system under the external disturbances and constraints is studied in the two-dimensional space. The dynamical analysis of the cable system considers the variable length, variable tension, variable speed, and the coupled vibrations of the cable in longitudinal-transverse directions. Considering output constraint problems, boundary control algorithms with output signal barriers are designed and acted on the boundary of the cable to reduce the coupled vibrations of the flexible crane cable, and to ensure the stability of the system in theory. Effectiveness and performance of the proposed control schemes are depicted via several simulation examples.

Boundary Vibration Control of a Variable Length Crane System in Two Dimensional Space with Output Constraints

In this paper, a hoisting cable with varying length under the external disturbances is investigated. The dynamical modeling for cable system takes into account variable length, variable tension and variable speed. The coupled vibrations of the cable in the longitudinal-transverse directions are suppressed by the designed control inputs acted on the boundary of the cable. Considering the output constraint problems, a barrier Lyapunov function (BLF)-based control is proposed to generate novel boundary control algorithms which reduce the undesirable vibrations of the flexible crane system and to prove the boundedness of the states. Effectiveness and performance of the proposed control schemes are depicted via several simulation examples.

The role of grain structure in the creep and fatigue of ni-based superalloy PM 1000

A study of the monotonic and cyclic deformation behavior of the recently developed oxide-dispersion-strengthened, nickel-based superalloy PM 1000 was carried out at temperatures up to 1,200°C in air. The influence of grain structure and texture was investigated using two heats with an identical particle microstructure—a )100*-fiber-structured bar material with a grain aspect ratio of ten along the longitudinal direction and a pancake-structured sheet material with a grain aspect ratio of four and a )100*{011}-cube on edge texture. Both creep resistance and lifetime in cyclic deformation depend strongly on texture and weakly on the grain aspect ratio, which determines the fracture path. Instead, lifetime can be predicted on the basis of the different Young’s moduli in the longitudinal and longitudinal-transverse direction, respectively.