A high accuracy continuous wavelet function approximation for implantable device applications

2014 ◽  
Author(s):  
Qingyun Ma ◽  
Mohammad Rafiqul Haider
Keyword(s):  
Function Approximation ◽  
High Accuracy ◽  
Wavelet Function ◽  
Implantable Device ◽  
Continuous Wavelet ◽  
Device Applications

Interconnection and damping assignment control based on modified actor–critic algorithm with wavelet function approximation

2020 ◽  
Vol 101 ◽  
pp. 116-129
Author(s):  
Amir Gheibi ◽  
Amir Rikhtehgar Ghiasi ◽  
Sehraneh Ghaemi ◽  
Mohammad Ali Badamchizadeh
Keyword(s):  
Function Approximation ◽  
Wavelet Function

Time-domain explicit finite-difference method based on the mixed-domain function approximation for acoustic wave equation

Geophysics ◽  
2017 ◽  
Vol 82 (5) ◽  
pp. T237-T248 ◽  
Author(s):  
Zhikai Wang ◽  
Jingye Li ◽  
Benfeng Wang ◽  
Yiran Xu ◽  
Xiaohong Chen
Keyword(s):  
Wave Equation ◽  
Dispersion Relation ◽  
Finite Difference ◽  
Acoustic Wave ◽  
Function Approximation ◽  
High Accuracy ◽  
Acoustic Wave Equation ◽  
Space Domain ◽  
Time Space ◽  
Explicit Finite Difference

Explicit finite-difference (FD) methods with high accuracy and efficiency are preferred in full-waveform inversion and reverse time migration. The Taylor-series expansion (TE)-based FD methods can only obtain high accuracy on a small wavenumber zone. We have developed a new explicit FD method with spatial arbitrary even-order accuracy based on the mixed [Formula: see text] (wavenumber)-space domain function approximation for the acoustic wave equation, and we derived the FD coefficients by minimizing the approximation error in a least-squares (LS) sense. The weighted pseudoinverse of mixed [Formula: see text]-space matrix is introduced into the LS optimization problem to improve the accuracy. The new method has an exact temporal derivatives discretization in homogeneous media and also has higher temporal and spatial accuracy in heterogeneous media. Approximation errors and numerical dispersion analysis demonstrate that the new FD method has a higher numerical accuracy than conventional TE-based FD and TE-based time-space domain dispersion-relation FD methods. Stability analysis reveals that our proposed method requires a slightly stricter stability condition than the TE-based FD and TE-based time-space domain dispersion-relation FD methods. Numerical tests in the homogeneous model, horizontally layered model, and 2D modified Sigsbee2 model demonstrate the accuracy, efficiency, and flexibility of the proposed new FD method.

scholarly journals Fabrication of Implantable Capsule-Type Channel Sounders for the High-Accuracy Measurement of the Signal Loss of Out-Body to In-Body Channels

Electronics ◽  
2021 ◽  
Vol 10 (23) ◽  
pp. 2895
Author(s):  
Jaehyo Jung ◽  
Siho Shin ◽  
Meina Li ◽  
Youn Tae Kim
Keyword(s):  
Human Body ◽  
High Accuracy ◽  
Implantable Device ◽  
Wireless Transmission ◽  
Signal Loss ◽  
Accuracy Measurement ◽  
Channel Sounder ◽  
Capsule Type ◽  
Channel Properties ◽  
High Accuracy Measurement

This paper proposes a channel sounder to measure the channel properties of an implantable device that transmits data from inside to outside the human body. The proposed channel sounder measures the receiving power of a signal transmitted from outside the human body. The channel sounder is equipped with a Bluetooth module that enables the wireless transmission of the receiving power outside the human body. Wireless transmission enables the channel measurement by isolating the transmitter and receiver inside the channel sounder. Using the proposed channel sounder, the channel properties can be measured without any interference between the transmitter and the receiver.

scholarly journals Damping identification in multi-degree-of-freedom systems using the continuous wavelet transform

2005 ◽  
Vol 27 (1) ◽  
pp. 41-50 ◽  
Author(s):  
Nguyen Phong Dien
Keyword(s):  
Wavelet Transform ◽  
Continuous Wavelet Transform ◽  
Damping Ratio ◽  
Morlet Wavelet ◽  
Wavelet Function ◽  
Degree Of Freedom ◽  
Damping Coefficient ◽  
Steel Beam ◽  
Continuous Wavelet ◽  
Modal Damping

The identification of damping in multi-degree-of-freedom vibration systems is a well-known problem and appears to be of crucial interest. Compared to an estimation of the stiffness and mass, the damping coefficient or, alternatively, damping ratio is the most difficult quantity to determine. In this paper, the continuous wavelet transform based on the Morlet-wavelet function is used to identify the modal damping ratios of multi-degree-of-freedom vibration systems. A new wavelet-based method for the damping identification from measured free responses is presented. The proposed method was also tested by experiments on a steel beam.

Defects Diagnosis of Bearing by Means of Acoustic Emission and Continuous Wavelet Transform

2009 ◽  
Vol 413-414 ◽  
pp. 651-657 ◽  
Author(s):  
Ru Jiang Hao ◽  
Zhi Peng Feng ◽  
Fu Lei Chu
Keyword(s):  
Acoustic Emission ◽  
Wavelet Transform ◽  
Continuous Wavelet Transform ◽  
Rolling Bearing ◽  
Morlet Wavelet ◽  
Wavelet Function ◽  
Continuous Wavelet ◽  
Test Rig ◽  
Ae Signal ◽  
Transform Coefficients

The acoustic emission signals of rolling bearing with different type of defects are de-noised and illustrated by the continuous wavelet transform and scalogram. Morlet wavelet function is selected and the wavelet parameters are optimized based on the principle of minimal wavelet entropy. The soft-threshold de-noising is used to filter the wavelet transform coefficients. The de-noised signals obtained by reconstructing the wavelet coefficients show the obvious impulsive features. Based on the optimized waveform parameters, the wavelet scalogram is used to analyze the real AE signal from the defective rolling bearing in experimental test rig. The results indicate that the proposed method is useful and efficient for signal purification and features extraction.

A New 1,000 kV Electron Microscope

1967 ◽  
Vol 25 ◽  
pp. 260-261
Author(s):  
M. Nishigaki ◽  
S. Katagiri ◽  
H. Kimura ◽  
B. Tadano
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
Basic Research ◽  
Chromatic Aberration ◽  
High Accuracy ◽  
Biological Specimen ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron

The high voltage electron microscope has many advantageous features in comparison with the ordinary electron microscope. They are a higher penetrating efficiency of the electron, low chromatic aberration, high accuracy of the selected area diffraction and so on. Thus, the high voltage electron microscope becomes an indispensable instrument for the metallurgical, polymer and biological specimen studies. The application of the instrument involves today not only basic research but routine survey in the various fields. Particularly for the latter purpose, the performance, maintenance and reliability of the microscope should be same as those of commercial ones. The authors completed a 500 kV electron microscope in 1964 and a 1,000 kV one in 1966 taking these points into consideration. The construction of our 1,000 kV electron microscope is described below.

TEM and cathodoluminescence of precipitates in II-VI semiconductors

1988 ◽  
Vol 46 ◽  
pp. 488-489
Author(s):  
Joanna L. Batstone
Keyword(s):  
Crystal Growth ◽  
Band Gap ◽  
Local Strain ◽  
Wide Band ◽  
Optoelectronic Device ◽  
Wide Band Gap ◽  
Bulk Crystal Growth ◽  
Transmission Electron ◽  
Device Applications ◽  
Stoichiometry Control

Interest in II-VI semiconductors centres around optoelectronic device applications. The wide band gap II-VI semiconductors such as ZnS, ZnSe and ZnTe have been used in lasers and electroluminescent displays yielding room temperature blue luminescence. The narrow gap II-VI semiconductors such as CdTe and HgxCd1-x Te are currently used for infrared detectors, where the band gap can be varied continuously by changing the alloy composition x.Two major sources of precipitation can be identified in II-VI materials; (i) dopant introduction leading to local variations in concentration and subsequent precipitation and (ii) Te precipitation in ZnTe, CdTe and HgCdTe due to native point defects which arise from problems associated with stoichiometry control during crystal growth. Precipitation is observed in both bulk crystal growth and epitaxial growth and is frequently associated with segregation and precipitation at dislocations and grain boundaries. Precipitation has been observed using transmission electron microscopy (TEM) which is sensitive to local strain fields around inclusions.

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