Search results for " Torque"
showing 10 items of 108 documents
Comparative evaluation of molecular methods for the quantitative measure of torquetenovirus (TTV) viremia, the new surrogate marker of immune compete…
2019
Background Torquetenovirus (TTV) viremia is emerging as a promising tool to assess functional immune competence, to predict posttransplant immune-related complications, and eventually to customize immunosuppression. Methods In this study, 327 blood samples were tested using two real-time PCR (rtPCR) assays both targeted to the untranslated region of the TTV genome. The first assay was an in-house rtPCR developed by our group, the second one was the recently marketed TTV R-GENE assay. Results In the validation study, the TTV R-GENE showed good performances in precision and reproducibility, and sensitivity as low as 12 TTV DNA copies/mL, like previously reported for the in-house rtPCR. The Bl…
Identifying the origin of the nonmonotonic thickness dependence of spin-orbit torque and interfacial Dzyaloshinskii-Moriya interaction in a ferrimagn…
2020
Electrical manipulation of magnetism via spin-orbit torques (SOTs) promises efficient spintronic devices. In systems comprising magnetic insulators and heavy metals, SOTs have started to be investigated only recently, especially in systems with interfacial Dzyaloshinskii-Moriya interaction (iDMI). Here, we quantitatively study the SOT efficiency and iDMI in a series of gadolinium gallium garnet (GGG) / thulium iron garnet (TmIG) / platinum (Pt) heterostructures with varying TmIG and Pt thicknesses. We find that the non-monotonic SOT efficiency as a function of the magnetic layer thickness is not consistent with the 1/thickness dependence expected from a simple interfacial SOT mechanism. Mor…
Spin-transfer torque driven motion, deformation, and instabilities of magnetic skyrmions at high currents
2020
In chiral magnets, localized topological magnetic whirls, magnetic skyrmions, can be moved by spin polarized electric currents. Upon increasing the current strength, with prospects for high-speed skyrmion motion for spintronics applications in mind, isolated skyrmions deform away from their typical circular shape. We analyze the influence of spin-transfer torques on the shape of a single skyrmion, including its stability upon adiabatically increasing the strength of the applied electric current. For rather compact skyrmions at uniaxial anisotropies well above the critical anisotropy for domain wall formation, we find for high current densities that the skyrmion assumes a non-circular shape …
A Cogging Torque Minimization Procedure for Interior Permanent Magnet Synchronous Motors Based on a Progressive Modification of the Rotor Lamination …
2022
This article describes a simple cogging torque minimization procedure for interior permanent magnet synchronous machines (IPMSMs), consisting of a progressive modification of the rotor lamination geometry. This procedure can be generalized for the main topologies of PMSM, independently of the number of stator slots or the location of the permanent magnets. For this purpose, a basic IPMSM structure is analyzed by means of the FEM (finite element method) approach, and then, several other IPMSM geometries, obtained by adequately modifying the rotor lamination geometry of the basic IPMSM model without changing its stator configuration, are proposed and discussed. The trends of the cogging torqu…
Spin-orbit-torque-induced skyrmion dynamics for different types of spin-orbit coupling
2018
Abstract We investigate current-induced skyrmion dynamics in the presence of Dzyaloshinskii-Moriya interaction and spin-orbit spin-transfer torque corresponding to various types of spin-orbit coupling. We determine the symmetries of Dzyaloshinskii-Moriya interaction and spin-orbit spin-transfer torque based on linear spin-orbit coupling model. We find that like interfacial Dzyaloshinskii-Moriya interaction (Rashba spin-orbit coupling) and bulk Dzyaloshinskii-Moriya interaction (Weyl spin-orbit coupling), Dresselhaus spin-orbit coupling also has a possibility for stabilizing skyrmion and current-induced skyrmion dynamics.
EKF-based estimation and control of electric drivetrain in offshore pipe racking machine
2016
A typical challenge for electric drivetrains is to reduce the number of sensors required for control action or system monitoring. This is particularly important for electric motors operating in offshore conditions, since they work in hostile environment which often damages data acquisition systems. Therefore, this paper deals with verification and validation of the extended Kalman filter (EKF) for sensorless indirect field-oriented control (IFOC) of an induction motor operating in offshore conditions. The EKF is employed to identify the speed of the induction motor based on the measured stator currents and voltages. The estimated speed is used in the motor speed control mode instead of a ph…
Performance Comparison of Electrical Motors equipped with slightly Asymmetrical Windings
2019
This paper presents a comparison between the performances of electrical machines equipped with slightly asymmetrical windings. More in detail, by modifying the stator geometry of an Interior Permanent Magnet Synchronous Machine equipped with a symmetrical winding configuration, other two slightly asymmetrical winding topologies are obtained. The three models are, then, analyzed by means of a finite element method (FEM) and the related results are compared in terms of cogging torque, static characteristics and leakage factor. The obtained results demonstrate that the adoption of slightly asymmetrical windings could be an interesting alternative solution during the design stage of electrical …
Torque peak reduction and overload monitoring of induction motors in offshore drilling operations
2015
Current drivetrain design procedures for electric actuation systems operating in offshore conditions typically consider two major requirements: to provide sufficient steady-state and maximum motor torques. As a result of this, no information regarding the transient state (e.g. during motor acceleration) is utilized when selecting drivetrain components. This leads to potentially dangerous situations when motors undergo saturation in these regions due to too high dynamic loads. A common reason for this (apart from lack of information about transient state when designing a drivetrain) is applying trapezoidal reference motion profiles that cause discontinuities in system acceleration and infini…
Dynamical Compensation of the Load Torque in a High-Performance Electrical Drive with an Induction Motor
2018
This paper describes a new method for dynamical estimation of load disturbance in induction motors by using Nonlinear Unknown Input Observers (NUIO). This estimation is then used to compensate dynamically the load torque in a Field Oriented Control (FOC) induction motor drive to increase its load-rejection capability. The method has been verified both in simulation and experimentally on a experimental rig.
Angle Displacement Robust Controller for the Port Plate of the Hydraulic Transformer
2013
The hydraulic transformer is used in the hydraulic system to enhance the efficiency. However, how to control the angle displacement of the port plate is becoming a critical issue because of the new structure of the hydraulic transformer. This paper presents a new method for the angle displacement control system. Firstly, the basic principle of the system is presented. Then, the disturbance which is mainly the friction torque between the port plate and the cylinder block is calculated to estimate the range. Furthermore, the guaranteed cost control (GCC) is analyzed and combined with the disturbance and the characteristics of parameter uncertainties. Finally, the proposed control method is co…