Surface finishing is one of the most significant steps in industries which are engaged with surface quality. Finishing by magnetic field is a new method of surface finishing. In this process, machining is executed in mechanical way and semi-homogeneous abrasive slurry performs finishing of surfaces. Needed force to grind surfaces is made by magnetic field. Therefor this method is considered as ...

Ball screw drives are widely used as the motion delivery mechanism due to their high stiffness and high accuracy. As the speed and precision requirements from machine tools increase, the effects of the structural flexibility of the drives on controller performance are becoming increasingly significant. The vibrations adversely affect the positioning accuracy and performance of the drive. The na...

The position error of a feed drive system is mostly caused by thermal deformation of a ball screw shaft. A high-speed ball screw system can generate massive heat with greater thermal expansion produced, and consequently have a negative effect on the positioning accuracy. In this study, we applied the computational approach using the finite element method (FEM) to simulate the thermal expansion ...

In this paper an optimal choice of actuator for an electric-type active mass driver (AMD) system for structural vibration control using linear quadratic controller has been developed. It is composed of an electric servomotor and a ball screw. The problems that commonly are associated with hydraulic AMD systems as noise, oil leakage, and laborintensive maintenance can be suppressed using an elec...

Exploitation of plant lignocellulosic biomass is hampered by our ignorance of the molecular basis for its properties such as strength and digestibility. Xylan, the most prevalent non-cellulosic polysaccharide, binds to cellulose microfibrils. The nature of this interaction remains unclear, despite its importance. Here we show that the majority of xylan, which forms a threefold helical screw in ...

The global screw-sense preference of an achiral helical oligomer may be controlled by a single chiral monomer located at one terminus. Remarkably, maximal control is induced in oligomers of the achiral quaternary amino acid Aib by a single C-terminal alaninamide residue, probably because the Ala side chain, though small, is compatible with a 310 helical conformation. The presence or absence of ...

We investigate a new screwlike liquid-crystalline ordering in solutions of helical biopolymers and its influence on the state of individual molecules. In the resulting mesophase translational and rotational motions of molecules are coupled in screw fluctuations. We show that in contrast to the case of conventional chiral liquid crystals the elastic distortion does not twist the screw order but ...

Oligoureas (up to n=6) of meso cyclohexane-1,2-diamine were synthesized by chain extension with an enzymatically desymmetrized monomer 2. Despite being achiral, the meso oligomers adopt chiral canonical 2.5-helical conformations, the equally populated enantiomeric screw-sense conformers of which are in slow exchange on the NMR timescale, with a barrier to screw-sense inversion of about 70 kJ mo...