This paper extends the approach proposed by Richard et al (2007) to analyze the axial and torsional vibrations of drilling systems that are excited by the particular boundary conditions at the drag bit-rock interface, by basing the formulation of the model on a continuum representation of the drillstring rather than on a characterization of the drilling structure by a two degree of freedom syst...

OBJECTIVE In developing countries, tibial shaft fractures are frequently stabilised using Surgical Implant Generation Network (SIGN) nails. Despite widespread use throughout the world, little is known regarding their biomechanical properties. This study aimed to compare the mechanical stiffness of the SIGN tibial nail with a standard hollow tibial nail. METHODS A fracture gap model was create...

Despite growing evidence suggesting the importance of enzyme conformational dynamics (ECD) in catalysis, a consensus on how precisely ECD influences the chemical step and reaction rates is yet to be reached. Here, we characterize ECD in Cyclophilin A, a well-studied peptidyl-prolyl cis-trans isomerase, using normal and accelerated, atomistic molecular dynamics simulations. Kinetics and free ene...

The article shows the effect of torsional rigidity of beam elements onto spatial work of bridges, floorings and other plate-ribbed systems It is shown that, in determining the torsional rigidity using existing methods it is necessary to have spatial spiral cracks, but torsional rigidity when normal cracks is not researched. A method is described for determining the torsional rigidity of reinfor...

For remote offshore wind farms, transmitting power to the main onshore grid via a Voltage Source Converter High Direct Current (VSC-HVDC) system is mainstream of transmission. It not only cost-effective in long-distance transmission, but also can fully meet side requirements such as black start, voltage support, fault ride through and frequency support. However, it still has some problems, poss...

Torsional nystagmus was noted in a patient with hypothalamic hamartoma. Magnetic resonance imaging revealed an exophytic hypothalamic mass extending into the pre-pontine cistern and abutting ventral mesencephalon. The quickphase of the torsional nystagmus was directed towards the left side, ipsilateral to the side of compression by the hamartoma. Ipsi-lesionally directed pure torsional nystagmu...

The classical dynamics of interaction between molecular rotation and large-amplitude internal rotation is studied for a rigid twister model of hydrogen peroxide, obtained by assuming an adiabatic separation of the torsional degree of freedom from the remaining 3N 7 vibrational modes. Use of the Augustin-Miller canonical transformation to express the molecule-fixed components of the total angule...

The cyclopropene radical cation (c-C3H₄⁺) is an important but poorly characterized three-membered-ring hydrocarbon. We report on a measurement of the high-resolution photoelectron and photoionization spectra of cyclopropene and several deuterated isotopomers, from which we have determined the rovibrational energy level structure of the X⁺ (2)B2 ground electronic state of c-C3H₄⁺ at low energies...

Flexural wave speeds on beams or plates depend upon the bending stiffnesses which differ by the well-known factor (1 - nu2). A quantitative analysis of a plate of finite lateral width displays the plate-to-beam transition, and permits asymptotic analysis that shows the leading order dependence on the width. Orthotropic plates are analyzed using both the Kirchhoff and Kirchhoff-Rayleigh theories...

Nonlinear torsional-flexural modal ;nteractions of a torsionally excited cantilever beam are studied in the case of one-to-one internal resonance. Discrete two DOF model is derived from the equations of motion for the continuous canthwer beam by using the Galerkin mode approx;mat;on method. The method of averaging is used to obtain the approx;mat;on to the response of the discrete model. Steady...