scholarly journals Prediction method of Ultra-wideband electromagnetic pulse coupling in slotted cavity

2021 ◽  
Vol 2085 (1) ◽  
pp. 012011
Author(s):  
Mingrui Wang ◽  
Mei Xu ◽  
Jiangfeng Wang ◽  
Yingying Guo
Keyword(s):  
Transfer Function ◽  
Test Data ◽  
Electromagnetic Pulse ◽  
Electromagnetic Compatibility ◽  
Prediction Method ◽  
Test Body ◽  
Ultra Wideband ◽  
Good Prediction ◽  
Field Response ◽  
Transmitting Antenna

Abstract With the develofpment of UWB electromagnetic pulse radiation systems, people are paying more and more attention to its serious threat to electronic equipment. The effect of UWB electromagnetic pulse has also become an important content in the field of electromagnetic compatibility. In an UWB radiation system, the distance between the device under test and the transmitting antenna is different, and the radiation field received is also different. Therefore, in actual tests, the test body is often placed at different distances from the antenna to perform multiple measurements to obtain test data as required. Based on this, this article takes the cavity as an example, and proposes a method of using the system transfer function to predict the response of the impulse field inside the cavity to simplify the test and quickly obtain the test data. Firstly, the impulse field response of a certain point with and without a cavity is measured respectively, and then the time domain response is inversely Fourier transformed to obtain the frequency domain transfer function of the test body. Finally, using the transfer function to convolute with the field to be measured, the response of the impulse field inside the cavity can be predicted under the condition of the field to be measured. It is verified by experiments that this method can better predict the response of the impulse field inside the cavity under different distance conditions, and has the characteristics of simple calculation and good prediction effect. At the same time, the transfer function obtained by this method can be used to predict the arbitrary impulse field response of the cavity in its frequency range.

Effectiveness of a Transfer Function Method for Evaluating Vibration Isolation Performance of Gloves When Used with Chipping Hammers

2002 ◽  
Vol 21 (3) ◽  
pp. 141-155 ◽  
Author(s):  
R.G. Dong ◽  
T.W. McDowell ◽  
D.E. Welcome ◽  
S. Rakheja ◽  
S. A. Caporali ◽  
...  
Keyword(s):  
Transfer Function ◽  
Function Method ◽  
Vibration Isolation ◽  
Prediction Method ◽  
Good Prediction ◽  
Mean Values ◽  
Transfer Function Method ◽  
Vibration Transmissibility ◽  
Vibration Isolation Performance ◽  
Isolation Performance

Anti-vibration gloves have been used as personal protective equipment to reduce the exposure intensity of hand-transmitted vibration. Although a method based upon the measured transfer function has been recently proposed to predict the tool-specific anti-vibration performance of these gloves, its validity for real tool applications has not been sufficiently evaluated. In this study, the effectiveness of the proposed prediction method was examined using two typical vibration-attenuation gloves when used in conjunction with two different pneumatic chipping hammers. Six adult male subjects were employed in the experiments involving measurement of gloves transmissibility while operating the selected tools. A comparison of the measured vibration transmissibility with the predicted values revealed that the transfer function method provides a reasonably good prediction of the vibration isolation performance of the gloves. The differences between the predicted and measured mean values of the weighted transmissibility were surprisingly small. It is concluded that the transfer function method can serve as an effective and convenient approach for estimating the effectiveness of anti-vibration gloves when used with pneumatic chipping hammers. A pneumatic chipping hammer is considered to represent a critical case for the evaluation of the method because they are typical percussive tools that generate impact vibration. It is thus anticipated that the transfer function method may also be widely employed to predict anti-vibration glove performance when used with many other vibrating tools.

scholarly journals Predicting drug–target interactions Based on the Ensemble Models of Multiple Feature Pairs

2021 ◽  
Vol 22 (12) ◽  
pp. 6598
Author(s):  
Cheng Wang ◽  
Jun Zhang ◽  
Peng Chen ◽  
Bing Wang
Keyword(s):  
Drug Target ◽  
Essential Feature ◽  
Characteristic Curve ◽  
Prediction Method ◽  
New Drugs ◽  
Good Prediction ◽  
Ensemble Model ◽  
Test Set ◽  
Multiple Feature ◽  
Validation Set

Backgroud: The prediction of drug–target interactions (DTIs) is of great significance in drug development. It is time-consuming and expensive in traditional experimental methods. Machine learning can reduce the cost of prediction and is limited by the characteristics of imbalanced datasets and problems of essential feature selection. Methods: The prediction method based on the Ensemble model of Multiple Feature Pairs (Ensemble-MFP) is introduced. Firstly, three negative sets are generated according to the Euclidean distance of three feature pairs. Then, the negative samples of the validation set/test set are randomly selected from the union set of the three negative sets in the validation set/test set. At the same time, the ensemble model with weight is optimized and applied to the test set. Results: The area under the receiver operating characteristic curve (area under ROC, AUC) in three out of four sub-datasets in gold standard datasets was more than 94.0% in the prediction of new drugs. The effectiveness of the proposed method is also shown with the comparison of state-of-the-art methods and demonstration of predicted drug–target pairs. Conclusion: The Ensemble-MFP can weigh the existing feature pairs and has a good prediction effect for general prediction on new drugs.

Dispersion distortions of wide spectrum signals during their propagation in the Earth ionosphere

Antennas ◽  
2021 ◽  
Author(s):  
M. M. Ivoylova ◽  
A. V. Kashin ◽  
V. A. Kozlov
Keyword(s):  
Electromagnetic Compatibility ◽  
Wide Spectrum ◽  
Radio Pulse ◽  
Current Trend ◽  
Polarization Plane ◽  
Leading Edge ◽  
Ultrashort Pulses ◽  
Ultra Wideband ◽  
Engineering Systems ◽  
Middle Latitudes

The current trend in the development of radio engineering systems (RES) is to use wide spectrum signals, the application of which provides an increase in the resolution and secrecy of the radar operation, an increase in the speed and volume of transmitted information for communication and telemetry systems. The class of such signals includes ultrashort pulses (USP signals), radio pulses with linear frequency modulation (chirp signals). Also of interest are ultra-wideband (UWB) noise signals (UWBN signals), which have high electromagnetic compatibility, stealth and noise immunity. When designing promising ground-based and space-based RES using wide spectrum signals, an important task is to determine the distortions of their envelope shape and distortions of spectrum, as well as the change in the polarization of the emitted wave when passing through the Earth's ionosphere, since taking these distortions into account will provide conditions for optimal reception. This article presents the numerical assessment results of the expected distortions of the wide spectrum signals main types of the decimeter wavelength range, for middle latitudes at heights from 100 km to 1000 km. The conversion of the emitted pulse into a frequency modulated radio pulse is typical for the USP signal. For a chirp radio pulse with a monotonically increasing frequency, an initial decrease in duration with an increase in amplitude and subsequent stretching in time with further spread is typical (the amplitude change is estimated due to a change in the signal shape without taking into account spread). For a chirp radio pulse with a monotonically falling frequency and a UWBN signal, dispersion distortions manifest themselves as an increase in their duration with a decrease in amplitude. For all signal types under consideration that have passed through the ionosphere, a leading edge lag is observed, the dependences of frequency on time at an altitude of 1000 km are repeated and are close to hyperbolic character, the energy spectra envelope shape of the considered signals is almost not distorted. The polarization plane rotation for signals with a spectrum concentrated in the frequency range above 0.7 GHz does not exceed 45

Minimax vs. Bayes Prediction

1995 ◽  
Vol 9 (1) ◽  
pp. 53-58 ◽  
Author(s):  
D. Blackwell
Keyword(s):  
Infinite Sequence ◽  
Prediction Method ◽  
Good Prediction ◽  
Bayes Prediction

Let x = (x1, x2, …) be an infinite sequence of 0's and 1's, initially unknown to you. On day n = 1,2,…, you observe hn = (x1, …, xn–1), the first n – 1 terms of the sequence, and must predict xn. What is a good prediction method, and how well can you do?

A flutter prediction method with low cost and low risk from test data

2019 ◽  
Vol 86 ◽  
pp. 542-557 ◽  
Author(s):  
Weiwei Zhang ◽  
Zhen Lv ◽  
Qiangqiang Diwu ◽  
Huashou Zhong
Keyword(s):  
Test Data ◽  
Low Cost ◽  
Prediction Method ◽  
Low Risk

scholarly journals Measurement and evaluation of radar cross section for furniture in an indoor propagation channel

2014 ◽  
Vol 12 ◽  
pp. 273-278 ◽  
Author(s):  
M. M. Maw ◽  
P. Supanakoon ◽  
S. Promwong ◽  
J. Takada
Keyword(s):  
Transfer Function ◽  
Cross Section ◽  
Indoor Environment ◽  
Radar Cross Section ◽  
Ultra Wideband ◽  
Indoor Propagation ◽  
Measurement And Evaluation ◽  
Propagation Prediction ◽  
Ridged Waveguide ◽  
Radar Equation

Abstract. This paper has attempted to evaluate the radar cross section (RCS) of two furniture items in an indoor environment in a frequency range of 3–7 GHz of the ultra-wideband (UWB) range. The RCS evaluation is achieved through an extended version of the radar equation that incorporates the channel transfer function of scattering. The time-gating method was applied to remove the multipath effect, a phenomenon which typically occurs in the indoor environment. Two double-ridged waveguide horn antennas for both vertical and horizontal polarizations were used to obtain the transfer function of scattering of the furniture prior to analysis in order to derive their bistatic RCS. The RCS results validate the applicability of the proposed extended radar equation to the indoor propagation prediction.

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