scholarly journals Design and Implementation of a Test Fixture for ELF Schumann Resonance Magnetic Antenna Receiver and Magnetic Permeability Measurements

Electronics ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 171
Author(s):  
Giorgos Tatsis ◽  
Vasilis Christofilakis ◽  
Spyridon K. Chronopoulos ◽  
Panos Kostarakis ◽  
Hector E. Nistazakis ◽  
...  
Keyword(s):  
Magnetic Permeability ◽  
Low Frequency ◽  
Absolute Calibration ◽  
Permeability Measurement ◽  
Test Fixture ◽  
Input Noise ◽  
Prototype Test ◽  
Total Input ◽  
Northwestern Greece ◽  
Total Sensitivity

This paper presents a prototype test fixture for the absolute calibration and estimation of the equivalent magnetic flux noise of the extremely low frequency (ELF) Schumann resonant (SR) magnetic antenna receiver and rods’ magnetic permeability measurement. The test fixture, for ELF the SR detector’s calibration, consists of a constructed coil, the signal generator, and the oscilloscope. The ELF SR detector used has been operating since 2016 near the Doliana village in the Ioannina prefecture, Northwestern Greece. At precisely this spot, far away from electromagnetic noise, the whole setup and experiment took place. The experiments performed with the proposed test fixture showed a sensitivity of 70 nV/pT/Hz and an apparent magnetic permeability at around 250 for the magnetic antenna. The total sensitivity of the ELF receiver was 210 mV/pT near 20 Hz, while the total input noise was around 0.04 pT.

Determination of Physical Properties of Isotropic Porous Materials by Impedance Tube

2009 ◽  
Author(s):  
Sanjay Sharma ◽  
Dennis Siginer
Keyword(s):  
Porous Medium ◽  
Fluid Flow ◽  
Physical Properties ◽  
Porous Materials ◽  
Low Frequency ◽  
Permeability Measurement ◽  
Impedance Tube ◽  
Acoustical Properties ◽  
Acoustical Method

Simulation of fluid flow in porous materials depends upon the accuracy of permeability measurement. This study details the development of an acoustical method to determine permeability of porous medium. Standardized acoustical testing for low frequency using impedance tube is carried out to determine the acoustical properties of the fibers. Physical properties of porous medium are determined by reverse calculation from the acoustical properties. The acoustical method is validated by comparing the measured acoustical properties of the porous medium by the analytical method. A variety of foams and fibers are tested using this methodology.

scholarly journals A Compact Low-Distortion Low-Power Instrumentation Amplifier

2010 ◽  
Vol 5 (1) ◽  
pp. 33-41
Author(s):  
Jader A. De Lima
Keyword(s):  
Low Frequency ◽  
Design Parameters ◽  
Instrumentation Amplifier ◽  
Cmos Process ◽  
Output Stage ◽  
Noise Spectral Density ◽  
Class Ab ◽  
Input Noise ◽  
Low Distortion ◽  
Equivalent Input Noise

A CMOS instrumentation amplifier based on a simple topology that comprises a double-input Gm-stage and a low-distortion class-AB output stage is presented. Sub-threshold design techniques are applied to attain high figures of differential-gain and rejection parameters. Analyses of input-referred noise and CMRR are comprehensively carried out and their dependence on design parameters determined. The prototype was fabricated in standard n-well CMOS process. For 5V-rail-to-rail supply and bias current of 100nA, stand-by consumption is only 16μW. Low-frequency parameters are ADM=86dB, CMRR=89.3dB, PSRR+=87dB, PSRR-=74dB. For a 6.5pF-damping capacitor, ΦM=73º and GBW=47KHz. The amplifier exhibits a THD of –64.5dB @100Hz for a 1Vpp-output swing. Input-noise spectral density is 5.2μV/ Hz @1Hz and 1.9μV/ Hz @10Hz, which gives an equivalent input-noise of 37.6μV, over 1Hz-200Hz bandwidth. This circuit may be employed for low-frequency, low-distortion signal processing, advantageously replacing the conventional 3-opamp approach for instrumentation amplifiers.

Use of a Zero-Gravity Suspension System for Testing a Vibration Isolation System

1998 ◽  
Vol 41 (6) ◽  
pp. 42-46
Author(s):  
M. Idle ◽  
R. Cobb ◽  
J. Sullivan ◽  
J. Goodding
Keyword(s):  
Vibration Isolation ◽  
Performance Test ◽  
Low Frequency ◽  
Infrared Camera ◽  
Open Loop ◽  
Isolation System ◽  
Loop Control ◽  
Test Fixture ◽  
Ballistic Missile Defense ◽  
Loop Control System

The Air Force Research Laboratory team has been confronted with many unique testing challenges in the Ballistic Missile Defense Organization sponsored Vibration Isolation and Suppression System (VISS) performance test program, VISS incorporates a combination passive/active vibration mitigation technology in a Stewart platform configuration to provide a mechanically quiet platform for a medium-wavelength, infrared camera. VISS actuator stiffnesses, insufficient to support the payload in a l-g field, require a gravity off-load system to simulate the free boundary conditions of space A performance test series characterized the test fixture dynamics, VISS payload dynamics and the open loop control system plant. Passive performance has been characterized and the active performance measured in the laboratory will be verified when VISS is on-orbit. VISS goals include demonstrating good passive-based vibration isolation at high frequencies, augmenting low-frequency isolation with closed loop control, suppressing an on-board disturbance due to a cryocooler, and demonstrating steering capabilities of the payload with a prescribed amplitude and spectral content.

B31 J SIF and k-Factor Test of Sweeplus®

2019 ◽  
Author(s):  
Yuqing Liu ◽  
Ismat El Jaouhari ◽  
Philip Diwakar ◽  
Dan Lin
Keyword(s):  
High Frequency ◽  
Thermal Loading ◽  
Low Frequency ◽  
Flow Induced Vibration ◽  
Test Fixture ◽  
Labview Software ◽  
K Factor ◽  
Piping Systems ◽  
Out Of Plane ◽  
Vibration Parameters

Abstract Formerly, an entire catalogue of 90 deg. branch connections called Sweeplus® was developed and accessed to mitigate acoustic induced vibration (AIV) in piping systems exposed to high frequency vibration. Parameters related to cyclic loading was completed on the Sweeplus® fitting to determine the stress intensification factor (SIF) and flexibility factor (k-factor), in accordance with the latest revision of ASME B31J-2017 code and reported in this paper. A Sweeplus® fitting was welded in a Markl test fixture and controlled through LabView software. The testing configuration and equipment were those used in Kahn test reported in WRC 329. K-factor tests were conducted for the in-plane thru both branch and header piping, and the out-of-plane thru branch. SIF tests were performed in the out-of-plane thru branch. The tests confirmed the SIF of Sweeplus® is less than one which means the fatigue life of Sweeplus® is significantly extended, not only under high frequency AIV excitation, but also under low frequency flow induced vibration (FIV) and thermal loading.

A high-resolution tunneling magneto-resistance sensor interface circuit

2017 ◽  
Vol 31 (04) ◽  
pp. 1750030 ◽  
Author(s):  
Xiangyu Li ◽  
Liang Yin ◽  
Weiping Chen ◽  
Zhiqiang Gao ◽  
Xiaowei Liu
Keyword(s):  
Band Gap ◽  
Temperature Coefficient ◽  
Low Frequency ◽  
Low Noise ◽  
Instrumentation Amplifier ◽  
Interface Circuit ◽  
Input Noise ◽  
Rejection Ratio ◽  
Equivalent Input Noise ◽  
Magneto Resistance

In this paper, a chopper instrumentation amplifier and a high-precision and low-noise CMOS band gap reference in a standard 0.5 [Formula: see text] CMOS technology for a tunneling magneto-resistance (TMR) sensor is presented. The noise characteristic of TMR sensor is an important factor in determining the performance of the sensor. In order to obtain a larger signal to noise ratio (SNR), the analog front-end chip ASIC weak signal readout circuit of the sensor includes the chopper instrumentation amplifier; the high-precision and low-noise CMOS band gap reference. In order to achieve the low noise, the chopping technique is applied in the first stage amplifier. The low-frequency flicker noise is modulated to high-frequency by chopping switch, so that the modulator has a better noise suppression performance at the low frequency. The test results of interface circuit are shown as below: At a single 5 V supply, the power dissipation is 40 mW; the equivalent offset voltage is less than 10 uV; the equivalent input noise spectral density 30 nV/Hz[Formula: see text](@10 Hz), the equivalent input noise density of magnetic is 0.03 nTHz[Formula: see text](@10 Hz); the scale factor temperature coefficient is less than 10 ppm/[Formula: see text]C, the equivalent input offset temperature coefficient is less than 70 nV/[Formula: see text]C; the gain error is less than 0.05%, the common mode rejection ratio is greater than 120 dB, the power supply rejection ratio is greater than 115 dB; the nonlinear is 0.1% FS.

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