scholarly journals Thermal Noise Estimation and Removal in MRI: A Noise Cancellation Approach

2011 ◽  
pp. 47-54 ◽  
Author(s):  
Miguel E. Soto ◽  
Jorge E. Pezoa ◽  
Sergio N. Torres
Keyword(s):  
Thermal Noise ◽  
Noise Cancellation ◽  
Noise Estimation

scholarly journals A Research of Noise Estimation and Removal Techniques for Speech Signal

2019 ◽  
Vol 8 (2S3) ◽  
pp. 718-721
Keyword(s):  
Adaptive Filter ◽  
Speech Signal ◽  
Active Noise Control ◽  
Noise Cancellation ◽  
Noise Signal ◽  
Noise Estimation ◽  
Control Technique ◽  
Adaptive Noise Cancellation ◽  
Active Noise ◽  
Adaptive Noise

In this paper, authors made an attempt to implement the active noise control technique (ANC) to decrease the amplitude of noise communicating through the environment using an electro-acoustic (EA) system with the help of measurement sensors such as microphones and output actuators such as loudspeakers. In general, the noise signal is generated from ambient; therefore, it is easy to detect the noise in the vicinity of its source. The main objective of developing the ANC system is to generate an “anti-noise" that reduce the unwanted noise in a desired quiet region using an appropriate adaptive filter. The simulations were performed in the MATLAB 2015 environment and satisfactory results were obtained using the proposed technique. The problem under study is different from traditional adaptive noise cancellation techniques in two ways. Firstly, it is not possible to measure the desired response of a signal directly measured; only the signal with reduced magnitude is present. Secondly, the ANC system is required to take into consideration the secondary loudspeaker-to-microphone error (LME) path in its adaptation.

A Blocker-Tolerant Inductor-Less Wideband Receiver With Phase and Thermal Noise Cancellation

2015 ◽  
Vol 50 (12) ◽  
pp. 2948-2964 ◽  
Author(s):  
Hao Wu ◽  
Mohyee Mikhemar ◽  
David Murphy ◽  
Hooman Darabi ◽  
Mau-Chung Frank Chang
Keyword(s):  
Thermal Noise ◽  
Noise Cancellation

scholarly journals Thermal noise cancellation in symmetric magnetoelectric bimorph laminates

2008 ◽  
Vol 93 (7) ◽  
pp. 072906 ◽  
Author(s):  
Junyi Zhai ◽  
Zengping Xing ◽  
Shuxiang Dong ◽  
Jiefang Li ◽  
D. Viehland
Keyword(s):  
Thermal Noise ◽  
Noise Cancellation

scholarly journals ECG Noise Cancellation Based on Grey Spectral Noise Estimation

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 798 ◽  
Author(s):  
Shing-Hong Liu ◽  
Cheng-Hsiung Hsieh ◽  
Wenxi Chen ◽  
Tan-Hsu Tan
Keyword(s):  
Empirical Mode Decomposition ◽  
Noise Cancellation ◽  
Noise Estimation ◽  
Body Motion ◽  
Ecg Signal ◽  
Intrinsic Mode Functions ◽  
Reconstruction Process ◽  
Second Stage ◽  
Mode Decomposition ◽  
Electrocardiogram Ecg

In recent years, wearable devices have been popularly applied in the health care field. The electrocardiogram (ECG) is the most used signal. However, the ECG is measured under a body-motion condition, which is easily coupled with some noise, like as power line noise (PLn) and electromyogram (EMG). This paper presents a grey spectral noise cancellation (GSNC) scheme for electrocardiogram (ECG) signals where two-stage discrimination is employed with the empirical mode decomposition (EMD), the ensemble empirical mode decomposition (EEMD) and the grey spectral noise estimation (GSNE). In the first stage of the proposed GSNC scheme, the input ECG signal is decomposed by the EMD to obtain a set of intrinsic mode functions (IMFs). Then, the noise energies of IMFs are estimated by the GSNE. When an IMF is considered as noisy one, it is forwarded to the second stage for further check. In the second stage, the suspicious IMFs are reconstructed and decomposed by the EEMD. Then the IMFs are discriminated with a threshold. If the IMF is considered as noisy, it is discarded in the reconstruction process of the ECG signal. The proposed GSNC scheme is justified by forty-three ECG signal datasets from the MIT-BIH cardiac arrhythmia database where the PLn and EMG noise are under consideration. The results indicate that the proposed GSNC scheme outperforms the traditional EMD and EEMD based noise cancellation schemes in the given datasets.

Ultra-spatially resolved synchrotron powered FT-IR microspectroscopy of individual cells of biological material

1995 ◽  
Vol 53 ◽  
pp. 884-885
Author(s):  
David L. Wetzel ◽  
John A. Reffner ◽  
Gwyn P. Williams
Keyword(s):  
Thermal Noise ◽  
Spot Size ◽  
Acquisition Time ◽  
Thermal Source ◽  
Signal To Noise ◽  
Spatially Resolved ◽  
Good Spatial Resolution ◽  
Small Spot ◽  
Ft Ir ◽  
Ir Microspectroscopy

Synchrotron radiation is 100 to 1000 times brighter than a thermal source such as a globar. It is not accompanied with thermal noise and it is highly directional and nondivergent. For these reasons, it is well suited for ultra-spatially resolved FT-IR microspectroscopy. In efforts to attain good spatial resolution in FT-IR microspectroscopy with a thermal source, a considerable fraction of the infrared beam focused onto the specimen is lost when projected remote apertures are used to achieve a small spot size. This is the case because of divergence in the beam from that source. Also the brightness is limited and it is necessary to compromise on the signal-to-noise or to expect a long acquisition time from coadding many scans. A synchrotron powered FT-IR Microspectrometer does not suffer from this effect. Since most of the unaperatured beam’s energy makes it through even a 12 × 12 μm aperture, that is a starting place for aperture dimension reduction.

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