On the optimum frequency range in the radio-astronomical method for the measurement of streams of cosmic particles of ultrahigh energy

2010 ◽  
Vol 16 (2) ◽  
pp. 17-22
Author(s):  
P.I. Golubnichii ◽  
◽  
A.D. Filonenko ◽  
Keyword(s):  
Ultrahigh Energy ◽  
Frequency Range ◽  
Optimum Frequency

AE Sources Localization Accuracy Improvement During Cross-country Gas Pipelines Testing

NDT World ◽  
2015 ◽  
Vol 18 (3) ◽  
pp. 40-42
Author(s):  
Жуков ◽  
Anton Zhukov
Keyword(s):  
Wall Thickness ◽  
Gas Pipelines ◽  
Frequency Range ◽  
Optimum Frequency ◽  
Localization Accuracy ◽  
Ae Signal ◽  
Cross Country ◽  
Pipeline Wall ◽  
Ae Signals ◽  
Operation Frequency

Introduction. The research was carried out to improve sources localization accuracy during cross-country gas pipelines testing. The research purpose is to determine an algorithm of choice for operation frequency range, AE transducers and input filters of AE equipment for different pipeline wall thicknesses Method. The AE signal was simulated on the pipelines with wall thickness from 8 to 24 mm. A few types of transducers with different amplitude-frequency characteristics were chosen for signal detection. Further we analyzed forms of the detected AE signals and stability of their velocity. Results. We have established that for each pipeline wall thickness there is a proper operation frequency range, within which the velocity of AE signals is stable and predictable. For example, for the 8 mm wall thickness the optimum frequency range is from 60 to 200 kHz. The suitable transducer for work within this range is GT200. If the work is held out of stated range, the AE signal velocity is not predictable and can vary from 500 to 5100 m/s; therefore localization of AE source turns to be impossible.

scholarly journals Effect of pulsating disintegrating airflow on electric arc depositing

2021 ◽  
Vol 9 (3B) ◽  
Author(s):  
Mohammad E. Matarneh ◽  
◽  
Vyacheslav Royanov ◽  
Irina Zakharova ◽  
◽  
...  
Keyword(s):  
Bond Strength ◽  
Bonding Strength ◽  
Metal Removal ◽  
Electric Arc ◽  
Pulsation Frequency ◽  
Process Performance ◽  
Frequency Range ◽  
Optimum Frequency ◽  
Electrical Arc ◽  
Arc Deposition

To limit the losses in sprayed metal in the process of electric arc deposition, the disintegrating airflow is pulsated. In this work, the effect of changing the pulsation frequency was studied on the process performance, mainly, the efficiency of metal removal and rate of deposition. Additionally, the bonding strength of the resulting sprayed metal was evaluated at different pulsation frequencies. The application of air pulsations increases the productivity and efficiency of sprayed material by increasing the efficiency of material used up to 30% and enhancing the rate of deposition up to 32%, at a frequency range 70–80 Hz. Moreover, at the optimum frequency of air pulsations, the bond strength increased up to 69%, measured by Steffensen’s dowel method. The results found in this work will allow for more rational usage of the electrical arc energy and material.

Selecting Filter Range of Hybrid Brain-Computer Interfaces by Mutual Information

2014 ◽  
Vol 981 ◽  
pp. 171-174 ◽  
Author(s):  
Li Wang ◽  
Xiong Zhang ◽  
Xue Fei Zhong ◽  
Zhao Wen Fan
Keyword(s):  
Mutual Information ◽  
Motor Imagery ◽  
Support Vector ◽  
Frequency Range ◽  
Fixed Frequency ◽  
Eeg Signals ◽  
Optimum Frequency ◽  
Computer Interfaces ◽  
Narrow Frequency Range ◽  
Better Than

The hybrid brain-computer interface (BCI) based on electroencephalography (EEG) become more and more popular. Motor imagery, steady state visual evoked potentials (SSVEPs) and P300 are main training Paradigms. In our previous research, BCI systems based on motor imagery can be extended by speech imagery. However, noise and artifact may be produced by different mental tasks and EEG signals are also different among users, so the classification accuracy can be improved by selecting optimum frequency range for each user. Mutual information (MI) is usually used to choose optimal features. After extracted the features from each narrow frequency range of EEG by common spatial patterns (CSP), the features are assessed by MI. Then, the optimum frequency range can be acquired. The final classification results are calculated by support vector machine (SVM). The average result of optimum frequency range from seven subjects is better than the result of a fixed frequency range.

scholarly journals Ultrahigh energy-dissipation elastomers by precisely tailoring the relaxation of confined polymer fluids

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jin Huang ◽  
Yichao Xu ◽  
Shuanhu Qi ◽  
Jiajia Zhou ◽  
Wei Shi ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Mechanical Energy ◽  
Operating Frequency ◽  
Ultrahigh Energy ◽  
Frequency Range ◽  
Polymer Fluids ◽  
Elastic Networks ◽  
Broad Frequency Range ◽  
Polymer Fluid ◽  
Confined Polymer

AbstractEnergy-dissipation elastomers relying on their viscoelastic behavior of chain segments in the glass transition region can effectively suppress vibrations and noises in various fields, yet the operating frequency of those elastomers is difficult to control precisely and its range is narrow. Here, we report a synergistic strategy for constructing polymer-fluid-gels that provide controllable ultrahigh energy dissipation over a broad frequency range, which is difficult by traditional means. This is realized by precisely tailoring the relaxation of confined polymer fluids in the elastic networks. The symbiosis of this combination involves: elastic networks forming an elastic matrix that displays reversible deformation and polymer fluids reptating back and forth to dissipate mechanical energy. Using prototypical poly (n-butyl acrylate) elastomers, we demonstrate that the polymer-fluid-gels exhibit a controllable ultrahigh energy-dissipation property (loss factor larger than 0.5) with a broad frequency range (10−2 ~ 108 Hz). Energy absorption of the polymer-fluid-gels is over 200 times higher than that of commercial damping materials under the same dynamic stress. Moreover, their modulus is quasi-stable in the operating frequency range.

Sign in / Sign up

Export Citation Format

Share Document