frequency noise
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2022 ◽  
Vol 9 ◽  
Author(s):  
Quanyi Gong ◽  
Ke Peng ◽  
Wei Wang ◽  
Bingyin Xu ◽  
Xinhui Zhang ◽  
...  

With the increase of various loads connected to the low-voltage distribution system, the difficulty of identifying low-voltage series fault arcs has greatly increased, which seriously threatens the electricity safety. Aiming at such problems, a neural network algorithm based on multi-feature fusion is proposed. The fault current has the characteristics of randomness, high frequency noise, and singularity. A GA-BP neural network model is built, and the wavelet analysis method (based on singularity), Fourier transform method (based on high frequency noise), current cycle difference method (based on randomness), and current cycle similarity derivation method (based on randomness) are used for feature extraction and can more comprehensively reflect the characteristics of arc faults. Simulation results show that the multi-feature fusion algorithm has a higher recognition rate than other algorithms. Moreover, compared with the support vector machine model, logistic regression model, and AlexNet model, the GA-BP neural network model has a higher recognition accuracy than the other three models, which can reach 99%.


2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Dongwan Kim ◽  
Mark Harfouche ◽  
Huolei Wang ◽  
Christos T. Santis ◽  
Yaakov Vilenchik ◽  
...  

AbstractWe have recently introduced a new semiconductor laser design which is based on an extreme, 99%, reduction of the laser mode absorption losses. In previous reports, we showed that this was achieved by a laser mode design which confines the great majority of the modal energy (> 99%) in a low-loss Silicon guiding layer rather than in highly-doped, thus lossy, III–V p$${}^+$$ + and n$${}^+$$ + layers, which is the case with traditional III–V lasers. The resulting reduced electron-field interaction was shown to lead to a commensurate reduction of the spontaneous emission rate by the excited conduction band electrons into the laser mode and thus to a reduction of the frequency noise spectral density of the laser field often characterized by the Schawlow–Townes linewidth. In this paper, we demonstrate theoretically and present experimental evidence of yet another major beneficial consequence of the new laser design: a near total elimination of the contribution of amplitude-phase coupling (the Henry $$\alpha $$ α parameter) to the frequency noise at “high” frequencies. This is due to an order of magnitude lowering of the relaxation resonance frequency of the laser. Here, we show that the practical elimination of this coupling enables yet another order of magnitude reduction of the frequency noise at high frequencies, resulting in a quantum-limited frequency noise spectral density of 130 Hz$$^2$$ 2 /Hz (linewidth of 0.4 kHz) for frequencies beyond the relaxation resonance frequency 680 MHz. This development is of key importance in the development of semiconductor lasers with higher coherence, particularly in the context of integrated photonics with a small laser footprint without requiring any sort of external cavity.


Author(s):  
Mingyuan Ren ◽  
Huijing Yang ◽  
Beining Zhang ◽  
Guoxu Zheng

This paper constructs and simulates the interface circuit of a temperature sensor based on SMIC 0.18 [Formula: see text]m CMOS. The simulation results show that when the power supply voltage is 1.8 V, the chopper op-amp gain is 89.44 dB, the low-frequency noise is 71.83 nV/Hz,[Formula: see text] and the temperature coefficient of the core temperature sensitive circuit is 1.7808 mV/[Formula: see text]C. The sampling rate of 10-bit SAR ADC was 10 kS/s, effective bit was 9.0119, SNR was 59.3256 dB, SFDR was 68.7091 dB, and THD was −62.5859 dB. The measurement range of temperature sensor interface circuit is −50[Formula: see text]C[Formula: see text]C, the relative temperature measurement error is ±0.47[Formula: see text]C, the resolution is 0.2[Formula: see text]C/LSB, and the overall average power consumption is 434.9 [Formula: see text]W.


2022 ◽  
Author(s):  
Jia-Hao Xu ◽  
Xing-Feng Zhu ◽  
Di-Chao Chen ◽  
Qi Wei ◽  
Da-Jian Wu

Abstract Broadband absorption of low-frequency sound waves via a deep subwavelength structure is of great and ongoing interest in research and engineering. Here, we numerically and experimentally present a design of a broadband low-frequency absorber based on an acoustic metaporous composite (AMC). The AMC absorber is constructed by embedding a single metamaterial resonator into a porous layer. The finite element simulations show that a high absorption (absorptance A > 0.8) can be achieved within a broad frequency range (from 290 Hz to 1074 Hz), while the thickness of AMC is 1/13 of the corresponding wavelength at 290 Hz. The broadband and high-efficiency performances of the absorber are attributed to the coupling between the two resonant absorptions and the trapped mode. A good agreement between the numerical simulation and experiment is obtained. Moreover, the high broadband absorption can be maintained under random incident acoustic waves. The proposed absorber provides potential applications in low-frequency noise reduction especially when limited space is demanded.


Author(s):  
Jooyoung Pyo ◽  
Akio Ihara ◽  
Shun-ichiro OHMI

Abstract This paper investigated the low frequency noise (LFN) utilizing 1/f noise and random telegraph noise (RTN) characteristics of Hf-based metal/oxide/nitride/oxide/silicon (MONOS) nonvolatile memory (NVM) device with HfO2 and HfON tunneling layer (TL). The low frequency noise spectral density (SID ) was investigated to evaluate the interface characteristics with fresh and after programming/erasing (P/E) cycles of 104. Both devices show similar slope of ~1/f in all of the frequency regions. Although HfON TL shows high SID compared to HfO2 TL, increased ratio is 15.4 which is low compared to HfO2 TL of 21.3. As decreasing the channel length from 10 to 2 μm, HfON TL shows small increased ratio of SID . Due to the nitrided characteristics, HfON TL suppress the degradation of interface. Finally, it is found that trap site of HfO2 TL is located near the interface by RTN measurement with capture (τC) and emission time constant (τE).


Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 373
Author(s):  
Haoqiang Gao ◽  
Qun Yan ◽  
Xusheng Liu ◽  
Ying Zhang ◽  
Yongtao Sun ◽  
...  

In order to achieve the dual needs of single-phase vibration reduction and lightweight, a square honeycomb acoustic metamaterials with local resonant Archimedean spirals (SHAMLRAS) is proposed. The independent geometry parameters of SHAMLRAS structures are acquired by changing the spiral control equation. The mechanism of low-frequency bandgap generation and the directional attenuation mechanism of in-plane elastic waves are both explored through mode shapes, dispersion surfaces, and group velocities. Meanwhile, the effect of the spiral arrangement and the adjustment of the equation parameters on the width and position of the low-frequency bandgap are discussed separately. In addition, a rational period design of the SHAMLRAS plate structure is used to analyze the filtering performance with transmission loss experiments and numerical simulations. The results show that the design of acoustic metamaterials with multiple Archimedean spirals has good local resonance properties, and forms multiple low-frequency bandgaps below 500 Hz by reasonable parameter control. The spectrograms calculated from the excitation and response data of acceleration sensors are found to be in good agreement with the band structure. The work provides effective design ideas and a low-cost solution for low-frequency noise and vibration control in the aeronautic and astronautic industries.


2022 ◽  
Vol 904 ◽  
pp. 43-49
Author(s):  
Bai Xue Fu ◽  
Wei Wang ◽  
Zi Yuan Cheng ◽  
Yu Bao

Using ultrasonic time difference method to test automobile fuel consumption, the test accuracy mainly depends on the testing system timing accuracy and ultrasonic flow sensor output signal-to-noise ratio. At present, the timing accuracy of the single-chip can reach the level of picosecond, and the noise mixed in the output signal of the ultrasonic converter is the main factor affecting the accuracy of fuel consumption testing. When the receiving signal contains noise, it will cause the signal amplitude to fluctuate, making the measurement time error. The analysis of same-frequency noise, circuit noise and colored noise is carried out, and the feasible measures to eliminate noise are put forward to provide reference for accurate calculation of sound and development of high-precision automobile fuel consumption test instruments.


2022 ◽  
Vol 2152 (1) ◽  
pp. 012037
Author(s):  
Qunli Chen ◽  
Wengeng Wu ◽  
Xu Gao ◽  
Yibiao Huang ◽  
Xiangwen Chen ◽  
...  

Abstract In view of the low-frequency noise problem in urban substation, the sound absorption (SA) properties of aluminum silicate fibers (ASF) with different materials, unit weight, plate thickness and cavity thickness were tested in this paper. It was found that the high-purity ASF with larger unit weight, plate thickness and cavity thickness had larger low-frequency SA coefficient, which provided technical support for the development of new low-frequency noise reduction materials for substation.


2022 ◽  
Vol 961 (1) ◽  
pp. 012101
Author(s):  
Ban Ali Kamil ◽  
Hamid Athab Eedan AlJameel

Abstract The proper design of a road’s surface layer can result in pavements that are not only better in terms of ride comfort and safety, but also in terms of noise reduction. The use of low-noise pavements may be an effective measure to reduce the acoustic pollution generated by road traffic This study aims to consider the effect of changed pavement features on the noise level. Tire/pavement noise is a major contributor to traffic noise at highway speeds. The effects of pavement properties, including air-void content, gradation properties, roughness, texture, pavement surface condition are major contributors to traffic noise at highway speeds. As the overall texture and IRI, increase noise levels. The results showed that greater air void content decreases the level of high-frequency noise.


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