Acquisition time minimisation techniques for high-speed analogue signal processing

1999 ◽  
Vol 35 (23) ◽  
pp. 1990 ◽  
Author(s):  
Young-Deuk Jeon ◽  
Seung-Hoon Lee
Keyword(s):  
Signal Processing ◽  
High Speed ◽  
Acquisition Time ◽  
Analogue Signal

Spin-polarized Scanning Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 768-769
Author(s):  
Kazuyuki Koike ◽  
Hideo Matsuyama
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Speed ◽  
Magnetic Thin Films ◽  
Electron Spin Polarization ◽  
Acquisition Time ◽  
Magnetization Direction ◽  
Spin Polarized ◽  
Conventional Methods ◽  
Scanning Electron

Spin-polarized scanning electron microscopy (spin SEM), where the secondary electron spin polarization is used as the image signal, is a novel technique for magnetic domain observation. Since its first development by Koike and Hayakawa in 1984, several laboratories have extensively studied this technique and have greatly improved its capability for data extraction and its range of applications. This paper reviews the progress over the last few years.Almost all the high expectations initially held for spin SEM have been realized. A spatial resolution of several hundreds angstroms has been attained, which is nearly one order of magnitude higher than that of conventional methods for thick samples. Quantitative analysis of magnetization direction has been performed more easily than with conventional methods. Domain observation of the surface of three-dimensional samples has been confirmed to be possible. One of the drawbacks, a long image acquisition time, has been eased by combining highspeed image-signal processing with high speed scanning, although at the cost of image quality. By using spin SEM, the magnetic structure of a 180 degrees surface Neel wall, magnetic thin films, multilayered films, magnetic discs, etc., have been investigated.

Editorial. Current-mode analogue signal processing

1990 ◽  
Vol 137 (2) ◽  
pp. 61 ◽  
Author(s):  
Chris Toumazou ◽  
John Lidgey ◽  
Brett Wilson
Keyword(s):  
Signal Processing ◽  
Current Mode ◽  
Analogue Signal

scholarly journals Three-Axis Inductive Displacement Sensor Using Phase-Sensitive Digital Signal Processing for Industrial Magnetic Bearing Applications

Actuators ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 115
Author(s):  
Teemu Sillanpää ◽  
Alexander Smirnov ◽  
Pekko Jaatinen ◽  
Jouni Vuojolainen ◽  
Niko Nevaranta ◽  
...  
Keyword(s):  
Signal Processing ◽  
Digital Signal Processing ◽  
Eddy Current ◽  
High Speed ◽  
Digital Signal ◽  
Magnetic Bearing ◽  
Air Gap ◽  
Sensor Design ◽  
Quadrature Demodulation ◽  
Displacement Sensors

Non-contact rotor position sensors are an essential part of control systems in magnetically suspended high-speed drives. In typical active magnetic bearing (AMB) levitated high-speed machine applications, the displacement of the rotor in the mechanical air gap is measured with commercially available eddy current-based displacement sensors. The aim of this paper is to propose a robust and compact three-dimensional position sensor that can measure the rotor displacement of an AMB system in both the radial and axial directions. The paper presents a sensor design utilizing only a single unified sensor stator and a single shared rotor mounted target piece surface to achieve the measurement of all three measurement axes. The sensor uses an inductive measuring principle to sense the air gap between the sensor stator and rotor piece, which makes it robust to surface variations of the sensing target. Combined with the sensor design, a state of the art fully digital signal processing chain utilizing synchronous in-phase and quadrature demodulation is presented. The feasibility of the proposed sensor design is verified in a closed-loop control application utilizing a 350-kW, 15,000-r/min high-speed industrial induction machine with magnetic bearing suspension. The inductive sensor provides an alternative solution to commercial eddy current displacement sensors. It meets the application requirements and has a robust construction utilizing conventional electrical steel lamination stacks and copper winding.

scholarly journals High-Speed Video Analysis of the Process Stability in Plasma Spraying

2021 ◽  
Author(s):  
K. Bobzin ◽  
M. Öte ◽  
M. A. Knoch ◽  
I. Alkhasli ◽  
H. Heinemann
Keyword(s):  
Plasma Spraying ◽  
High Speed ◽  
Plasma Jet ◽  
Plasma Jets ◽  
Time Dependent ◽  
Acquisition Time ◽  
Fast Fourier Transformation ◽  
Frequency Spectra ◽  
Dependent Signal ◽  
The Stability

AbstractIn plasma spraying, instabilities and fluctuations of the plasma jet have a significant influence on the particle in-flight temperatures and velocities, thus affecting the coating properties. This work introduces a new method to analyze the stability of plasma jets using high-speed videography. An approach is presented, which digitally examines the images to determine the size of the plasma jet core. By correlating this jet size with the acquisition time, a time-dependent signal of the plasma jet size is generated. In order to evaluate the stability of the plasma jet, this signal is analyzed by calculating its coefficient of variation cv. The method is validated by measuring the known difference in stability between a single-cathode and a cascaded multi-cathode plasma generator. For this purpose, a design of experiment, covering a variety of parameters, is conducted. To identify the cause of the plasma jet fluctuations, the frequency spectra are obtained and subsequently interpreted by means of the fast Fourier transformation. To quantify the significance of the fluctuations on the particle in-flight properties, a new single numerical parameter is introduced. This parameter is based on the fraction of the time-dependent signal of the plasma jet in the relevant frequency range.

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