Search results for "vector"
showing 10 items of 2660 documents
Interaction of carbon with microstructural defects in a W-Re matrix: An ab initio assessment
2019
The interaction of carbon atoms with point defects and the core of edge and screw dislocations with Burgers vector a 0 / 2 ⟨ 111 ⟩ in W and a W-Re matrix is studied by means of ab initio calculations. The structure and energetics of the ground-state atomic configurations are presented and rationalized. It is found that di-vacancies, which are thermally unstable in pure W according to the state-of-the-art ab initio calculations, can nucleate at C and Re-C complexes, which fill the gap in the explanation of the emergence of nanovoids observed experimentally under irradiation. Also, on the basis of the recent experimental evidence and our calculations, the temperature ranges for the manifestat…
Magnetic properties of exciton trapped by an off-center ionized donor in single quantum dot
2021
Abstract It is known that the lines of exciton (X) and exciton trapped by an ionized donor ( D + , X ) are often very close which makes very difficult their experimental identification. In order to facilitate their distinction in spherical quantum dots, we investigate the effect of an applied magnetic field studying the binding energy of the complex ( D + , X ) as function of dot size and the ionized donor position. Our calculation is using a variational approach taking into account the interactions between all charge carriers. Our results show that the complex is more sensitive to the magnetic field than the exciton and that the energy of the exciton is not sufficiently affected when the i…
Permanent magnet system to guide superparamagnetic particles
2017
A new concept of permanent magnet systems for guiding superparamagnetic particles on arbitrary trajectories is proposed. The basic concept is to use one magnet system with a strong and homogeneous (dipolar) magnetic field to magnetize and orient the particles. A second constantly graded field (quadrupolar) is superimposed to the first to generate a force. In this configuration the motion of the particles is driven solely by the component of the gradient field which is parallel to the direction of the homogeneous field. Then the particles are guided with constant force in a single direction over the entire volume. The direction can be adjusted by varying the angle between quadrupole and dipo…
Synchronous precessional motion of multiple domain in a ferromagnetic nanowire by perpendicular field pulses
2014
Magnetic storage and logic devices based on magnetic domain wall motion rely on the precise and synchronous displacement of multiple domain walls. The conventional approach using magnetic fields does not allow for the synchronous motion of multiple domains. As an alternative method, synchronous current-induced domain wall motion was studied, but the required high-current densities prevent widespread use in devices. Here we demonstrate a radically different approach: we use out-of-plane magnetic field pulses to move in-plane domains, thus combining field-induced magnetization dynamics with the ability to move neighbouring domain walls in the same direction. Micromagnetic simulations suggest …
Magnetic field control of gas-liquid mass transfer in ferrofluids
2020
Abstract Gas-liquid mass transfer plays a key role in a broad range of industrial processes. The magnetic field control over the morphology of the gas-liquid interface and solute transport is an attractive feature if it can be realized efficiently. However, the magnetic properties of typical liquids and gases are rather weak. The experimental investigation is carried out to evaluate the effect of the magnetic field, which is mediated by magnetic nanoparticles, on the gas-liquid mass exchange during the sparging run through a hydrocarbon ferrofluid. The results indicate that the gradient field is especially effective at controlling the gas-liquid contact volume: the foaming of the liquid dur…
Data-driven Fault Diagnosis of Induction Motors Using a Stacked Autoencoder Network
2019
Current signatures from an induction motor are normally used to detect anomalies in the condition of the motor based on signal processing techniques. However, false alarms might occur if using signal processing analysis alone since missing frequencies associated with faults in spectral analyses does not guarantee that a motor is fully healthy. To enhance fault diagnosis performance, this paper proposes a machinelearning based method using in-built motor currents to detect common faults in induction motors, namely inter-turn stator winding-, bearing- and broken rotor bar faults. This approach utilizes single-phase current data, being pre-processed using Welch’s method for spectral density es…
Space‐vector state dynamic model of SynRM considering self‐ and cross‐saturation and related parameter identification
2020
This study proposes a state formulation of the space-vector dynamic model of the Synchronous Reluctance Motor (SynRM) considering both saturation and cross-saturation effects. The proposed model adopts the stator currents as state variables and has been theoretically developed in both the rotor and stator reference frames. The proposed magnetic model is based on a flux versus current approach and relies on the knowledge of 11 parameters. Starting from the definition of a suitable co-energy variation function, new flux versus current functions have been initially developed, based on the hyperbolic functions and, consequently, the static and dynamic inductance versus current functions have be…
Oxy-nitrides characterization with a new ERD-TOF system
2017
Abstract A new time-of-flight (TOF) camera was installed on Elastic Recoil Detection (ERD) measurement setup on the Tandem Accelerator at Universite de Montreal. The camera consists of two timing detectors, developed and built by the Jyvaskyla group, that use a thin carbon foil and microchannel plates (MCP) to produce the start and stop signals. The position of the first detector is fixed at 18 cm from the target, while the position of the second detector can be varied between 50 and 90 cm from the first detector. This allows to increase time resolution by increasing the distance between the time-of-flight detectors or to increase solid angle by decreasing the distance. Moving the detector …
FOC with Resolver Implementation for PMSM Drives by Using a Low Cost Atmel SAM3X8E Microcontroller
2020
The aim of this paper is the low-cost experimental implementation of a field oriented control strategy for a Permanent Magnet Synchronous Motor (PMSM) by using an Atmel SAM3X8E microcontroller, mounted on an Arduino DUE board. In this electrical drive for PMSM, a resolver is used in order to measure the rotor position and speed: Therefore, the low-cost Arduino DUE performs not only FOC algorithm and phase currents data acquisition, but also a resolver-To-digital converter process, rotor position and speed data acquisition, and resolver signals management. The code has been implemented in the open source Arduino IDE, using C language, whereas the control and plot visualization interfaces hav…
Machine learning regression algorithms for biophysical parameter retrieval: Opportunities for Sentinel-2 and -3
2012
Abstract ESA's upcoming satellites Sentinel-2 (S2) and Sentinel-3 (S3) aim to ensure continuity for Landsat 5/7, SPOT-5, SPOT-Vegetation and Envisat MERIS observations by providing superspectral images of high spatial and temporal resolution. S2 and S3 will deliver near real-time operational products with a high accuracy for land monitoring. This unprecedented data availability leads to an urgent need for developing robust and accurate retrieval methods. Machine learning regression algorithms may be powerful candidates for the estimation of biophysical parameters from satellite reflectance measurements because of their ability to perform adaptive, nonlinear data fitting. By using data from …