Search results for "Vector"
showing 10 items of 2660 documents
Autoencoders and Data Fusion Based Hybrid Health Indicator for Detecting Bearing and Stator Winding Faults in Electric Motors
2018
The main objective of a condition monitoring programs is to track the health status of critical components of a machine. In this paper, a hybrid health indicator is proposed to monitor the health status of bearings and stator winding of a motor. The proposed method is based on a feature learning from deep autoencoders and data fusion. The features can be learned by autoencoders using individual current and vibration signals, and then learning features are fused to make final health indicators. The experimental data from a permanent magnet synchronous motor is used to validate the proposed method. Promising results in detecting faults and severities of the stator and bearing faults at differ…
Downsizing the Electric Motors of Energy-Efficient Self-Contained Electro-Hydraulic Systems by Using Hybrid Technologies
2020
Abstract The ongoing tendency toward the electrification of hydraulic systems, mainly in the form of self-contained solutions, poses design challenges in high-power applications. An electric motor drives positive-displacement machines used to control the motion of the hydraulic actuator (nonhybrid systems encompassing one or two pumps exist in the technical literature). All the power managed by the actuator passes through the electric motor, which leads to often oversized arrangements. These detrimental characteristics are especially pronounced when the power level increases approximately above 35–40 kW. Therefore, this research paper presents and studies a self-contained, electro-hydraulic…
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.
Biorthonormal-basis method for the vector description of optical-fiber modes
1998
This paper gives the theoretical basis for the development of real vector modal methods to describe optical-fiber modes. To this end, the vector wave equations, which determine the electromagnetic fields, are written in terms of a pair of linear, nonself-adjoint operators, whose eigenvectors satisfy biorthogonality relations. The key of our method is to obtain a matrix representation of the vector wave equations in a basis that is defined by the modes of an auxiliary system. Our proposed technique can be applied to fibers with any profile, even those with a complex refractive index. An example is discussed to illustrate our approach.
Experimental demonstration of the physics of resonant cavities
2005
We describe an undergraduate experiment that demonstrates the physics of cavity resonators. A mobile wall lets students alter the position of the nodes, thus changing the mode pattern. The nodal structure is made apparent by placing a metallic plate at different positions inside the cavity. A technique for dielectric characterization also is introduced, which helps students understand the boundary conditions in dielectrics, as well as highlighting the characteristics of fields in cavities.
The electromagnetic and Proca fields revisited: A unified quantization
1997
Quantizing the electromagnetic field with a group formalism faces the difficulty of how to turn the traditional gauge transformation of the vector potential, Aμ(x) → Aμ(x) + ∂μφ(x), into a group law. In this paper, it is shown that the problem can be solved by looking at gauge transformations in a slightly different manner which, in addition, does not require introducing any BRST-like parameter. This gauge transformation does not appear explicitly in the group law of the symmetry but rather as the trajectories associated with generalized equations of motion generated by vector fields with null Noether invariants. In the new approach the parameters of the local group, U(1)(x, t), acquire dyn…
Noncoaxial Inductance Calculations Without the Vector Potential for Axisymmetric Coils and Planar Coils
2008
This paper presents an exact method for calculating the mutual inductance between a general axisymmetric coil and a second planar coil consisting of either a disk coil or a planar loop of essentially arbitrary shape. The approach is based directly on the magnetic field rather than the vector potential . The paper gives detailed results for two circular loops, a circular loop and an elliptic loop, and a circular loop and an annular disk coil. The method can be extended to cover the cases where all these loops and coils are extruded in the axial direction to give the corresponding solenoids. The method is also applicable to calculations for nuclear radiation detectors.
Highly efficient full-wave electromagnetic analysis of 3-D arbitrarily shaped waveguide microwave devices using an integral equation technique
2015
A novel technique for the full-wave analysis of 3-D complex waveguide devices is presented. This new formulation, based on the Boundary Integral-Resonant Mode Expansion (BI-RME) method, allows the rigorous full-wave electromagnetic characterization of 3-D arbitrarily shaped metallic structures making use of extremely low CPU resources (both time and memory). The unknown electric current density on the surface of the metallic elements is represented by means of Rao-Wilton-Glisson basis functions, and an algebraic procedure based on a singular value decomposition is applied to transform such functions into the classical solenoidal and nonsolenoidal basis functions needed by the original BI-RM…
Uncertainties in polarimetric 3D reconstructions of coronal mass ejections
2015
P.P. acknowledges STFC for financial support. Date of Acceptance: 21/01/2015 Aims. The aim of this work is to quantify the uncertainties in the three-dimensional (3D) reconstruction of the location of coronal mass ejections (CMEs) obtained with the so-called polarization ratio technique. The method takes advantage of the different distributions along the line of sight of total (tB) and polarized (pB) brightnesses emitted by Thomson scattering to estimate the average location of the emitting plasma. This is particularly important to correctly identify of CME propagation angles and unprojected velocities, thus allowing better capabilities for space weather forecastings. Methods. To this end, …
Robust Active Disturbance Rejection Control of Induction Motor Systems Based on Additional Sliding-Mode Component
2017
This paper deals with motion control systems with induction motor, subject to severe requirements on both dynamics and steady-state behavior. The proposed control methodology could be viewed as an advancement of the standard field oriented control. It consists of two control loops, i.e., the rotor flux and the speed control loops, designed using the active disturbance rejection control method, with the aim to cope with both exogenous and endogenous disturbances, which are estimated by means of two linear extended state observers and then compensated. Moreover, with the aim of achieving total robustness, a sliding-mode based component is designed, in order to take into account disturbance es…