Search results for "Torque"
showing 10 items of 373 documents
A Novel Technique Using Polytetrafluoroethylene Tape to Solve Screw Loosening Complication in Implant-Supported Single Crowns
2020
This study aimed to analyze a novel technique to make screws with greater untightening resistance and to solve screw loosening in implant-supported single crowns. Thirty grade IV titanium straight abutments were screwed onto 30 external hex implants using grade IV titanium screws (30 Ncm). They were exposed to cyclic loading (300,000 cycles, 200 N). Samples were divided into 4 groups (15 samples per group): new screws (SCREW group) (control), reused screws (rSCREW group), new screws wrapped with polytetrafluoroethylene (PTFE) tape (PTFE group), and reused screws wrapped with PTFE tape (rPTFE group). Reverse torque values (RTVs) were recorded with a digitally calibrated implant motor. Mean R…
Analytical and experimental evaluation of a WECS based on a Doubly Fed Induction Generator fed by a matrix converter
2008
In this paper the control of a grid-connected Wind Energy Conversion System (WECS), based on a sensorless vector controlled Doubly-Fed Induction Generator (DFIG) fed by a matrix converter, is presented. The matrix converter is controlled using a space vector modulation algorithm. Stability issues related to the operation of the WECS connected to the grid using a matrix converter are also discussed in this work. The influence of a synchronous rotating filter in the dynamic of the proposed WECS is analysed. A Model Reference Adaptive System (MRAS) observer for sensorless control of the proposed WECS is used in this work. Using the speed estimated by the MRAS observer the electrical torque of …
Hybrid electric vehicle powertrain design: Construction of topologies and initial design schemes
2018
This paper introduces the generic representation and construction methods for the architectures of the four-wheel-drive hybrid electric vehicle (HEV) powertrain, which achieve the unified rules to represent and construct all types of HEV powertrains. To map the architecture into numerical variables and add it into optimization, the kinematic matrix of the HEV powertrain is extracted corresponding to the topological structure. Based on the torque distribution requirement of four-wheel-drive HEV, the initial design schemes (architecture and parameters) are created by charge-under-go feasibility inspection.
A Comparative Study of Cyclic Fatigue of 10 Different Types of Endodontic Instruments: an in Vitro Study
2019
Objective This study was designed to test the null hypothesis that there were no significant differences between size 25 files F360, F6 SkyTaper, Hyflex EDM, iRace, Neoniti, One Shape Protaper Next, Reciproc, Revo-S and Wave One Gold in terms of resistance to cyclic fatigue and length of broken fragments. Material and methods 300 new size 25 files of the systems studied were selected (n=30). The instruments were mechanized with a X-Smart Plus endo motor at the speed and torque recommended by the manufacturer, holding the instruments steady with a clamping mechanism, with passive adjustment and without pressure in a stainless-steel block. The time was calculated in seconds until fracture. Th…
Torque Control During Intrusion on Upper Central Incisor in Labial and Lingual bracket System - A 3D Finite Element Study
2018
Background The aim of present study was to investigate the difference of torque control during intrusive force on upper central incisors with normal, under and high torque in lingual and labial orthodontic systems through 3D finite element analysis. Material and methods Six 3D models of an upper right central incisor with different torque were designed in Solid Works 2006. Software ANSYS Version 16.0 was used to evaluate intrusive force on upper central incisor model . An intrusive force of 0.15 N was applied to the bracket slot in different torque models and the displacements along a path of nodes in the upper central incisor was assessed. Results On application of Intrusive force on under…
A Novel Digital Technique for Measuring the Accuracy of an Indirect Bonding Technique Using Fixed Buccal Multibracket Appliances
2021
The aim of this study was to analyze the accuracy and predictability of the indirect bonding technique of fixed buccal multibracket appliances using a customized iterative closest point algorithm. Materials and Methods: A total of 340 fixed buccal multibracket appliances were virtually planned and bonded on 34 experimental anatomically based acrylic resin models by using orthodontic templates designed and manufactured to indirectly bond the fixed buccal multibracket appliances. Afterwards, the models were submitted to a three-dimensional impression technique by an intraoral scanner, and the standard tessellation language digital files from the virtual planning and the digital impression wer…
Comparison of torque expression in esthetic brackets
2019
Background The objective of this work is to test the null hypothesis that there is no difference in the torque expression among different esthetic brackets. Material and methods Five ceramic self-ligating brackets (In-Ovation C - GAC, Damon Clear-Ormco, QuicKlear-Forestadent, Click-It -TP Orthodontics, Clarity SL-3M Unitek) and 4 ceramic conventional brackets (Inspire Ice-Ormco, InVu Ceramic-TP Orthodontics, Ceramic Roth-Morelli, Clarity Metal-Reinforced Ceramic Bracket-3M Unitek) were selected. Metallic Damon MX self-ligating bracket (Ormco) was used as control. Third-order moments were measured at 12o, 24o and 36o using an archwire torsion device associated with a Universal Testing Machin…
On thermo-mechanical issues induced by irradiation swelling inside the back-plate of the IFMIF target assembly
2011
Abstract Within the framework of the IFMIF R&D program and in close cooperation with ENEA-Brasimone, at the Department of Nuclear Engineering of the University of Palermo a research campaign has been launched to investigate the thermo-mechanical issues potentially induced by irradiation swelling in the threaded connections between frame and back-plate of IFMIF target assembly. The main aim of the research campaign has relied in the assessment of the maximum swelling-induced volumetric strain that may be accepted in order to allow screws to withstand thermo-mechanical stresses and work in safe conditions or to avoid unduly high unscrewing torques during back-plate remotely handled maintenanc…
V-Belt Winding along Archimedean Spirals During the Variator Speed Ratio Shift
2010
Starting from a previous model for the shift mechanics of rubber belt variators, this lecture elaborates practical design formulas for the torque and the axial thrust making use of the very close resemblance of the belt path to a linear spiral of Archimedes along a large part of the arc of contact. In addition, as an alternative to the modern calculus tools, it is shown how the drive variables can be equally calculated applying some propositions of Archimedes’ classical treatise πeρί ‘eλίκων (On Spirals).
Magnetic skyrmions: from fundamental to applications
2016
In this topical review, we will discuss recent advances in the field of skyrmionics (fundamental and applied aspects) mainly focusing on skyrmions that can be realized in thin film structures where an ultrathin ferromagnetic layer (<1 nm) is coupled to materials with large spin-orbit coupling. We review the basic topological nature of the skyrmion spin structure that can entail a stabilization due to the chiral exchange interaction present in many multilayer systems with structural inversion asymmetry. The static spin structures and the dynamics of the skyrmions are also discussed. In particular, we show that skyrmions can be displaced with high reliability and efficiency as needed for t…