Low-frequency test method for integrated RF substrates

2009 ◽  
Author(s):  
Abhilash Goyal ◽  
Madhavan Swaminathan ◽  
Abhijit Chatterjee
Keyword(s):  
Low Frequency ◽  
Test Method ◽  
Frequency Test

PRELIMINARY STUDY OF AN ARDUINO CONTROLLED SHAKE TABLE TO LOW-FREQUENCY TEST

2021 ◽  
Author(s):  
Ledymar F. Moreno ◽  
Marcus V. G. de Morais ◽  
Suzana M. Avila
Keyword(s):  
Low Frequency ◽  
Shake Table ◽  
Frequency Test ◽  
Preliminary Study

scholarly journals Comparative study of 0.1Hz very-low frequency withstand voltage test method and traditional method

2021 ◽  
Vol 2005 (1) ◽  
pp. 012175
Author(s):  
Dong Sun ◽  
Jinyu Gao ◽  
Yongxin Piao ◽  
Bo Guo ◽  
Chengjia Qu ◽  
...  
Keyword(s):  
Comparative Study ◽  
Traditional Method ◽  
Low Frequency ◽  
Test Method ◽  
Very Low Frequency

Parameter Identification of a Strongly Nonlinear Rotor-Bearing System Based on Reconstructed Constant Response Tests

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Genbei Zhang ◽  
Chaoping Zang ◽  
Michael I. Friswell
Keyword(s):  
Test Method ◽  
Fixed Frequency ◽  
Multiple Responses ◽  
Response Curves ◽  
Frequency Test ◽  
Strongly Nonlinear ◽  
Jump Phenomena ◽  
Rotor Bearing ◽  
Nonlinear Support ◽  
Bearing System

Abstract A strongly nonlinear rotor-bearing system often has multiple solutions under harmonic excitations and jump phenomena. For example, a hardening nonlinearity may include a jump-down in the acceleration process and jump-up in the deceleration process. It is challenging to measure all of these multiple responses and establish an accurate dynamic model from experimental data to predict these phenomena. This paper used a fixed frequency test method to measure all of these multiple responses under harmonic excitations and developed a novel strategy to characterize and identify nonlinearities in a strongly nonlinear rotor-bearing system based on reconstructing constant response tests from fixed frequency test data. The fixed frequency tests are achieved by monotonically increasing the voltage applied to the exciter at a fixed frequency and using the force drop-out phenomenon through the resonance to control the force applied to the structure. This test method could measure multivalued response curves of a strongly nonlinear rotor-bearing system in a nonrotating state. The constant response tests could be reconstructed from these multivalued response curves. The relationship of equivalent stiffness versus displacement can be established, and hence, the nonlinear stiffness is characterized and identified from constant response tests. A rotor-bearing system with a strongly nonlinear support is used to demonstrate the method, and the nonlinear support stiffness parameters are identified and validated in a nonrotating state. The identified nonlinear rotor-bearing model also could predict the jump phenomena in the acceleration or deceleration process. The results demonstrate the feasibility and effectiveness of the approach, and also show the potential for practical applications in engineering.

scholarly journals An Approach for Reconstruction of Realistic Economic Data Based on Frequency Characteristics between IMFs

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Hao Du ◽  
Hao Gong ◽  
Suyue Han ◽  
Peng Zheng ◽  
Bin Liu ◽  
...  
Keyword(s):  
Time Series ◽  
Data Analysis ◽  
Time Series Data ◽  
Low Frequency ◽  
Test Method ◽  
Series Data ◽  
Permutation Entropy ◽  
Intrinsic Mode Functions ◽  
Economic Data ◽  
Index Method

Reconstruction of realistic economic data often causes social economists to analyze the underlying driving factors in time-series data or to study volatility. The intrinsic complexity of time-series data interests and attracts social economists. This paper proposes the bilateral permutation entropy (BPE) index method to solve the problem based on partly ensemble empirical mode decomposition (PEEMD), which was proposed as a novel data analysis method for nonlinear and nonstationary time series compared with the T-test method. First, PEEMD is extended to the case of gold price analysis in this paper for decomposition into several independent intrinsic mode functions (IMFs), from high to low frequency. Second, IMFs comprise three parts, including a high-frequency part, low-frequency part, and the whole trend based on a fine-to-coarse reconstruction by the BPE index method and the T-test method. Then, this paper conducts a correlation analysis on the basis of the reconstructed data and the related affected macroeconomic factors, including global gold production, world crude oil prices, and world inflation. Finally, the BPE index method is evidently a vitally significant technique for time-series data analysis in terms of reconstructed IMFs to obtain realistic data.

An Advanced Test Method to Determine Viscous Damping of Floating Structures

2010 ◽  
Author(s):  
Z. J. Huang ◽  
B. J. O’Donnell ◽  
T. W. Yung ◽  
S. T. Slocum
Keyword(s):  
Low Frequency ◽  
Test Method ◽  
Total Force ◽  
Viscous Damping ◽  
Damping Force ◽  
Restoring Force ◽  
Viscous Forces ◽  
Motion Time ◽  
Research Company ◽  
Time Histories

ExxonMobil Upstream Research Company developed an advanced model test method to determine reliable damping values for predicting low frequency motions of an FLNG barge and an LNG carrier. Since viscous damping forces are a very small portion of the total force on the model, how to separate the viscous forces from the total forces is the key technical challenge. To better isolate viscous damping forces, an inertial compensation system consisting of springs was employed in the test. The spring stiffness was designed such that the restoring force cancelled the large inertial loads at the oscillation frequency. Furthermore, double-body models were built and were deeply submerged to minimize surface wave damping. With such an experimental setup, the total force measured was mainly the viscous damping force. Viscous damping was derived from the measured force and motion time histories.

Determination of Viscous Damping for Low Frequency Motions of Floating Structures

2011 ◽  
Author(s):  
Z. J. Huang ◽  
B. J. O’Donnell ◽  
T. W. Yung ◽  
S. T. Slocum
Keyword(s):  
Forced Oscillation ◽  
Low Frequency ◽  
Test Method ◽  
Irregular Waves ◽  
Viscous Damping ◽  
Damping Force ◽  
Near Resonance ◽  
Research Company ◽  
Decay Tests ◽  
Scale Motion

ExxonMobil Upstream Research Company developed an advanced model test method to determine reliable damping values for predicting low frequency motions of an FLNG barge and an LNG carrier [1]. An inertial compensation system was introduced in the test to confidently isolate the relatively very small viscous damping force from the total measured forces in the forced oscillation tests. In the system, the spring stiffness in the restoring mechanism was tuned such that the test was done near resonance. This method has been successfully applied to ExxonMobil forced oscillation tests to measure damping of deeply submerged, double body models. Three types of motions were generated in the tests: sinusoidal motions, decay motions and motions with multiple frequencies. In this paper, the authors attempt to correlate the damping obtained from decay tests and from tests with motions of multiple frequency components. Findings from this work help determine damping for predictions of full scale motion in irregular waves.

scholarly journals Research progress on human feel test method of Substation low frequency noise

2020 ◽  
Vol 782 ◽  
pp. 032116
Author(s):  
Wei Chen ◽  
Sheng Hu ◽  
Wei Wen ◽  
Xiaowen Wu ◽  
Hao Cao ◽  
...  
Keyword(s):  
Low Frequency ◽  
Test Method ◽  
Research Progress ◽  
Frequency Noise ◽  
Low Frequency Noise

Study on Absorbing Properties of Honeycomb Absorbing Materials

2013 ◽  
Vol 815 ◽  
pp. 645-649
Author(s):  
Hui Min Sun ◽  
Zhao Zhan Gu ◽  
Ran Ran Yang
Keyword(s):  
Layer Thickness ◽  
High Frequency ◽  
Free Space ◽  
Low Frequency ◽  
Resonance Peak ◽  
Test Method ◽  
Electromagnetic Parameters ◽  
Frequency Wave ◽  
Absorbing Materials

Honeycomb absorbing materials were measured using the method of free space in this paper. The reflectance of honeycomb absorbing materials was calculated and simulated, and it was verified based on the measured results. It was demonstrated that this test method was feasible. Through studying on absorbing properties of honeycomb, the results have showed that the radar absorbing properties of honeycomb are related to electromagnetic parameters, as well as thickness of the dip-coatings. With the increase of thickness of the dipping layer, the radar absorbing capability of high frequency and low frequency wave are significantly increased. It is worth noting that the resonance peak moved to the low frequency with the increase of dipping layer thickness. These results are useful for design of honeycomb absorbing materials.

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