The paper presents a synchronous control scheme for a mechanically coupled dual ball screw system applied to wave makers driven by multiple servomotor/ball screw units or machine tools such as those of the gantry type. The hardware system is first established and modelled using a system identification approach. The controller is then designed with pseudo derivative feedback feedforward (PDFF) c...

The paper discusses a sliding mode control suitable for compensation of nonlinear microdynamic friction and parameter changes in a ball-screw driven slide system. The conventional, fixed-gain sliding mode control has a limited range of performance in the presence of varying nonlinear friction in submicrometer trajectory tracking. In this work, an algorithm that effectively calculates variable s...

The ability of urea-linked oligomers of achiral diamines (achiral analogues of the well-established chiral oligourea foldamers) to adopt helical conformations was explored spectroscopically. Up to four achiral units were ligated either to a well-formed helical trimer or to a single chiral diamine, and the extent to which they adopted a screw-sense preference was determined by NMR and CD. In the...

OBJECTIVE In pedicle screw fixation, the heads of monoaxial screws need to be directed in the same straight line to accommodate the rod placement by backing out during operation, which decreases the insertional torque and internal fixation strength. While polyaxial screws facilitate the assembly of the connecting rod, but its ball-in-cup locking mechanism reduces the static compressive bending ...

The crystal structure of an initiation-like 70S ribosome complex containing an 8-bp Shine-Dalgarno (SD) helix was determined at 3.8-A resolution. Translation-libration-screw analysis showed that the inherent anisotropic motions of the SD helix were biased along its helical axis, suggesting that during the first step of translocation, the SD helix moves along its helical screw axis. Contacts bet...

A weak topological insulator in dimension $3$ is known to have a topologically protected gapless mode along the screw dislocation. In this paper we formulate and prove fact with language of C*-algebra K-theory. The proof based on coarse index theory helical surface.

The size of the movement and the molecular identity of the moving parts of the voltage sensor of a voltage-gated ion channel are debated. In the helical-screw model, the positively charged fourth transmembrane segment S4 slides and rotates along negative counter charges in S2 and S3, while in the paddle model, S4 carries the extracellular part of S3 (S3b) as a cargo. Here, we show that S4 slide...

This paper aims to study the flow of an incompressible, isothermal Eyring-Powell fluid in a helical screw rheometer. The complicated geometry of the helical screw rheometer is simplified by "unwrapping or flattening" the channel, lands, and the outside rotating barrel, assuming the width of the channel is larger as compared to the depth. The developed second order nonlinear differential equatio...