scholarly journals Impedance Analysis and Noise Measurements on Multi Walled Carbon Nanotube Networks

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7509
Author(s):  
Usha Philipose ◽  
Yan Jiang ◽  
Brianna Western ◽  
Michael Harcrow ◽  
Chris Littler ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Low Frequency ◽  
Impedance Analysis ◽  
Frequency Range ◽  
Electrical Measurements ◽  
Electrical Equivalent Circuit ◽  
Host Matrix ◽  
Multi Walled Carbon Nanotube ◽  
Frequency Independent ◽  
Noise Measurements

The electrical impedance characteristics of multi-walled carbon nanotube (MWCNTs) networks were studied as a function of CNT concentrations in the frequency range of 1 kHz–1 MHz. The novelty of this study is that the MWCNTs were not embedded in any polymer matrix and so the response of the device to electrical measurements are attributed to the CNTs in the network without any contribution from a polymer host matrix. Devices with low MWCNT packing density (0.31–0.85 µg/cm2) exhibit a frequency independent plateau in the low-frequency regime. At higher frequencies, the AC conductivity of these devices increases following a power law, characteristic of the universal dynamic response (UDR) phenomenon. On the other hand, devices with high MWCNT concentrations (>1.0 µg/cm2) exhibit frequency independent conductivity over the entire frequency range (up to 1 MHz), indicating that conduction in these devices is due to direct contact between the CNTs in the network. A simple single-relaxation time electrical equivalent circuit with an effective resistance and capacitance is used to describe the device performance. The electrical noise measurements on devices with different MWCNT packing densities exhibit bias-dependent low-frequency 1/f noise, attributed to resistance fluctuations.

RESEARCH AND MAPPING OF LOW FREQUENCY NOISE GENERATED BY POWER PLANTS OF INDUSTRIAL ENTREPRISES

Akustika ◽  
2021 ◽  
pp. 103
Author(s):  
Andrey Vasilyev
Keyword(s):  
Power Plants ◽  
Low Frequency ◽  
Environmental Noise ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Frequency Range ◽  
Noise Mapping ◽  
Industrial Enterprises ◽  
Noise Measurements ◽  
Urban Territory

Environmental noise level from industrial enterprises is constantly increasing, especially in low frequency range. This paper presents the results of research and mapping of low frequency noise generated by power plants of industrial enterprises. Environmental noise mapping results of urban territory of Samara region of Russia are also presented. Results of noise measurements during industrial enterprises operation (on the example of “KuibyshevAzot” company) are showing that in some measuring points there were exceeding values compared with Russian sanitary norms requirements. The most serious problem is low frequency noise impact.

scholarly journals The Sound of Gas-Turbine Installations

1970 ◽  
Author(s):  
Robert M. Hoover
Keyword(s):  
Control Problem ◽  
Gas Turbine ◽  
Sound Pressure ◽  
Noise Control ◽  
Low Frequency ◽  
Frequency Range ◽  
Level Data ◽  
Industry Performance ◽  
Noise Measurements ◽  
Control Criteria

In this overall review of gas-turbine sound and its control, the author discusses the variety of installations, the scope of the noise control problem, criteria, industry performance, noise specifications, and noise measurements. In particular, the magnitude of the noise control problem is indicated by discussion of the sound of an unmuffled 20 Mw turbine. Typical sound pressure level data on current installations are given, and suggestions are made for noise control criteria in the low frequency range.

Electromagnetic and microwave absorbing performance of ultra-thin Fe attached carbon nanotube hybrid buckypaper

2014 ◽  
Vol 07 (02) ◽  
pp. 1450006 ◽  
Author(s):  
Shaowei Lu ◽  
Xianjun Zeng ◽  
Peng Nie ◽  
Chunlin Feng ◽  
Xuhai Xiong ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Photoelectron Spectroscopy ◽  
Experimental Result ◽  
Light Weight ◽  
Vibrating Sample Magnetometer ◽  
Frequency Range ◽  
Filtration Method ◽  
Vacuum Filtration ◽  
X Ray ◽  
Multi Walled Carbon Nanotube

The ultra-thin Fe attached multi-walled carbon nanotube hybrid buckypaper ( Fe /MWCNT hybrid buckypaper) was fabricated by vacuum filtration method with monodispersion solutions of MWCNTs and Fe nanoparticles. The morphology, element composition and magnetic properties of buckypapers were characterized by field-emission scanning electron microscope, X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer. The complex permittivity and permeability, the reflection loss (RL) properties of buckypapers attached composite were investigated in the frequency range of 12.4–18 GHz. The Fe /MWCNTs hybrid buckypaper attached composite posses much broader absorbing bandwidth and larger reflectivity than those of pure MWCNTs buckypaper attached composite with the same absorbing thickness (dm = 0.1 mm). The best reflectivity below -5 dB is at 14.0–18 GHz, and the minimum value is -14.4 dB at 16.8 GHz. The experimental result indicates that Fe /MWCNTs hybrid buckypaper has potential application in thin thickness and light-weight microwave absorbers.

EXCESS LOW FREQUENCY NOISE IN SINGLE-WALL CARBON NANOTUBE

2006 ◽  
Vol 06 (01) ◽  
pp. L45-L55 ◽  
Author(s):  
S. SOLIVERES ◽  
A. HOFFMANN ◽  
F. PASCAL ◽  
C. DELSENY ◽  
M. S. KABIR ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Noise Sources ◽  
Single Wall Carbon Nanotube ◽  
Single Wall Carbon ◽  
Noise Measurements ◽  
Nanotube Defects

Low frequency noise measurements have been performed on a single-wall carbon nanotube connected by Ti/Au electrodes. It has been found that the 1/f noise decreases when the measurements are undertaken under vacuum and when the nanotube is partially degassed, showing a correlation between the fluctuation inducing the 1/f noise and the presence of gases. We show that the 1/f noise sources are located at the metal/nanotube contacts. When the device is annealed under vacuum at 450K, some Lorentzian shapes are observable and can be related to nanotube defects or to strongly bound molecules.

IDENTIFICATION OF OPTOCOUPLER DEVICES WITH RTS NOISE

2006 ◽  
Vol 06 (04) ◽  
pp. L395-L404 ◽  
Author(s):  
A. KONCZAKOWSKA ◽  
J. CICHOSZ ◽  
A. SZEWCZYK ◽  
B. STAWARZ
Keyword(s):  
Low Frequency ◽  
Noise Signal ◽  
Gaussian Component ◽  
Current Transfer ◽  
Frequency Range ◽  
Scattering Pattern ◽  
Transfer Ratio ◽  
Noise Measurements ◽  
Non Gaussian ◽  
Rts Noise

The results of noise measurements in low frequency range for CNY 17 type optocouplers are presented. The research were carried out on devices with different values of Current Transfer Ratio (CTR). The methods for identification of Random Telegraph Signal (RTS) in noise signal of optocouplers were proposed. It was found that the Noise Scattering Pattern method (NSP method) enables to identify RTS noise as non-Gaussian component of noise signal of the optocoupler. The NSP method proves to be very fast and simple.

Electrical Conductivity and Electromagnetic Interference Shielding of Multi-walled Carbon Nanotube Filled Polymer Composites

2004 ◽  
Vol 858 ◽  
Author(s):  
Yonglai Yang ◽  
Mool C. Gupta ◽  
Kenneth L. Dudley ◽  
Roland W. Lawrence
Keyword(s):  
Carbon Nanotube ◽  
Electromagnetic Interference ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Frequency Range ◽  
Sem Images ◽  
Percolation Behavior ◽  
Multi Walled Carbon Nanotube ◽  
X Band ◽  
Conducting Networks

ABSTRACTMulti-walled carbon nanotube (MWNT) filled polystyrene (PS) composites were synthesized for electromagnetic interference (EMI) shielding applications. SEM images of composites showed the formation of the conducting networks through MWNTs within the PS matrix. The measured DC conductivity of composites increased with increasing MWNT loading, showing a typical percolation behavior. EMI shielding characteristics of MWNT-PS composites were investigated in the frequency range of 8.2–12.4 GHz (X-band). It was observed that the shielding effectiveness (SE) of such composite increased with the increase of MWNT loading. The SE of the composite containing 7 wt% MWNTs could reach more than 26 dB in the measured frequency region.

Microwave Properties of Mechanosynthesized Fe-Paraffin Nanocomposites

2010 ◽  
Vol 168-169 ◽  
pp. 345-348 ◽  
Author(s):  
A.N. Maratkanova ◽  
S.F. Lomayeva ◽  
D.A. Petrov ◽  
Konstantin N. Rozanov ◽  
A.A. Chulkina ◽  
...  
Keyword(s):  
Wall Motion ◽  
Low Frequency ◽  
Domain Wall Motion ◽  
Microwave Properties ◽  
Frequency Range ◽  
Slight Effect ◽  
Host Matrix ◽  
Frequency Peak ◽  
Dielectric Host ◽  
Properties Of Composites

The structure and microwave properties of composites consisting of paraffin as a dielectric host matrix and Fe particles as inclusions have been studied. The composites were prepared by the mechanochemical synthesis and contain 7.7% vol. concentration of the inclusions. The microwave properties were studied in 0.1 to 6 GHz frequency range. The microwave properties of the composites are shown to depend mostly on the size and shape of the inclusions, with the phase composition of the inclusions exerting only a slight effect. With decreasing the inclusions size, the low-frequency peak (300−400 MHz) attributed to the domain wall motion diminishes.

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