At Nikolaev, in 1978, a system for the improvement in the stability of the light path between the transit instrument and the meridian mires was designed. Its purpose is to improve the accuracy of the azimuth determination and that of the collimation. This system consists of twelve sections of 8 mm thick steel tube with 160 mm diameter, each nine meters long. These tubes are lying in special steel cradles which rest on brick support columns spaced 8 meters apart, and these can be moved vertically and horizontally by 100 mm and 50 mm, respectively. Thus it is possible to align the axis of the tube exactly.
Design and simulation of a new type of tubular steel electro-thermal actuator capable of vertical displacement is presented. The Tubular Thermal Actuator (TTA) consists of several multiple cascaded chevron-shaped structures, which are connected together by a top ring, as a platform to carry vertical displacement. The TTA is made from a 20 μm thick steel tube with an outer diameter of 1mm by laser micromachining technology. A finite element model was developed to simulate the behavior of the actuator and study the dominant heat transfer mode at this scale. The actuator could generate more than 7 μm linear motion and 2 mN forces at the top ring. In order to avoid operating the tubular actuator at its natural resonant frequencies, modal analysis has also been conducted.
Examination of Inspection Method for Outer-side Defect on Ferromagnetic Steel Tube by Velocity Effect Using Insertion-type Static Magnetic Field Sensor