orthodontic miniscrews are widely used as temporary anchorage devices to facilitate orthodontic movements. miniscrew loosening is a common problem, which usually occurs during the first two weeks of treatment. macrodesign can affect the stability of a miniscrew by changing its diameter, length, thread pitch, thread shape, tapering angle and so on. in this study, a 3-d finite element analysis wa...

AbstractThe Darrieus turbine is used as an ocean current converter to generate renewable electrical energy. One way improve performance determine the optimal pitch angle. Therefore, purpose of this study was angle NACA 0018 airfoil with variations -6°, -2°, 0° and 2°. Numerical method help Ansy Fluent software carried out for construction turbine. The result research that 2° produces largest co...

Application of nanofluid and coiled tubes are two passive methods for increasing the heat transfer. In the present study, the turbulent flows of water and nanofluid in coiled tubes heat exchanger were numerically studied. CuO-water nanofluid containing 1 vol% copper oxide nanoparticles was used and single-phase approach was considered for nanofluid flow. The effect of different geometrical para...

By combining optical triangulation with the comb-fringe technique and dual-channel telemetry, wing kinematics and body attitudes accompanying muscle activities of free-flying male hawkmoths were recorded synchronously when they performed flight manoeuvres elicited by a female sex pheromone. The results indicate that the wing leading edge angular position at the ventral stroke reversal, which ca...

The estimation of forces in swimming using the quasi-static approach (Schleihauf, In: J. Terauds, J.P. Clarys (Eds.), Swimming III, International Series on Sports Sciences. Vol. 8, University Park Press, Baltimore, 1979, 70-109) has been popular in recent years as propulsion is an important determinant of performance. The aim of this study was to establish the accuracy and reliability of curren...

A detailed model of wind power station, including Double Fed Induction Generator, DFIG is presented in this paper. Two control mechanisms are included in the model. The inner control system uses stator flux oriented control for the rotor side converter and grid voltage vector control for the grid side converter. The outer control system is used for wind turbine pitch angle. PSCAD/EMTDC is us...

We consider a model for periodic patterns of charges constrained over a cylindrical surface. In particular we focus on patterns of chiral helices, achiral rings, or vertical lamellae, with the constraint of global electroneutrality. We study the dependence of the patterns' size and pitch angle on the radius of the cylinder and salt concentration. We obtain a phase diagram by using numerical and...

New observations of energetic helium ion ̄uxes in the Earth's radiation belts have been obtained with the CAMMICE/HIT instrument on the ISTP/GGS POLAR spacecraft during the extended geomagnetically low activity period April through October 1996. POLAR executes a high inclination trajectory that crosses over both polar cap regions and passes over the geomagnetic equator in the heart of the radiat...

The difficulty of describing the positions of the body-fixed axis of a rotating body is approached through the use of Euler angles: spin ψ̇, nutation θ and precession φ shown below in Figure 1. In this case we surmount the difficulty of keeping track of the principal axes fixed to the body by making their orientation the unknowns in our equations of motion; then the angular velocities and angula...

Since the conventional electro-mechanical converter of 2D valve had problems of step lose due to its small tooth-pitch angle, a novel rotary electromagnet with large tooth-pitch angle and coreless rotor structure was proposed. Combined with the approaches of magnetic circuit analysis, finite element simulation and experimental study, the static and dynamic characteristics of electromagnet inclu...