scholarly journals Pulse interference identification and suppression for OFDM signal

2021 ◽  
Vol 2108 (1) ◽  
pp. 012028
Author(s):  
Wei Wei ◽  
Tao Peng ◽  
Li Ye
Keyword(s):  
Information Acquisition ◽  
Low Voltage ◽  
Interference Signal ◽  
Communication Performance ◽  
Pulse Interference ◽  
The Core ◽  
Communication Module ◽  
The Time Domain ◽  
Short Time ◽  
Time Pulse

Abstract The new generation smart meter is the core node of information acquisition and flows in the power Internet of Things (IoT). Because it is powered by the low-voltage power line, various short-time pulse interference signals in the line can be easily coupled to the received signal of the communication module embedded in the meter, resulting in the degradation of communication performance. In view of this situation, an identification-suppression algorithm of the short-time pulse-interference signal is proposed. The core idea is to comprehensively judge the existence of the interference signal and its specific position in the time domain based on the energy ratio of adjacent OFDM symbols and the change of mean square error value between frequency domain amplitude signals. Based on this, an interference energy elimination scheme with an adaptive threshold is realized. Theoretical analysis and simulation results show that the scheme has low computational complexity, high accuracy of pulse interference identification and position judgment, and can effectively reduce the energy of pulse interference signal, and thus improving the decoding performance of OFDM while it receives signals.

scholarly journals Ultrasonic Assessment of Thickness and Bonding Quality of Coating Layer Based on Short-Time Fourier Transform and Convolutional Neural Networks

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 909
Author(s):  
Azamatjon Kakhramon ugli Malikov ◽  
Younho Cho ◽  
Young H. Kim ◽  
Jeongnam Kim ◽  
Junpil Park ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Coating Layer ◽  
Ultrasonic Pulse ◽  
Short Time Fourier Transform ◽  
Coating Materials ◽  
Time Frequency ◽  
High Attenuation ◽  
Bonding State ◽  
The Time Domain ◽  
Short Time

Ultrasonic non-destructive analysis is a promising and effective method for the inspection of protective coating materials. Offshore coating exhibits a high attenuation rate of ultrasonic energy due to the absorption and ultrasonic pulse echo testing becomes difficult due to the small amplitude of the second echo from the back wall of the coating layer. In order to address these problems, an advanced ultrasonic signal analysis has been proposed. An ultrasonic delay line was applied due to the high attenuation of the coating layer. A short-time Fourier transform (STFT) of the waveform was implemented to measure the thickness and state of bonding of coating materials. The thickness of the coating material was estimated by the projection of the STFT into the time-domain. The bonding and debonding of the coating layers were distinguished using the ratio of the STFT magnitude peaks of the two subsequent wave echoes. In addition, the advantage of the STFT-based approach is that it can accurately and quickly estimate the time of flight (TOF) of a signal even at low signal-to-noise ratios. Finally, a convolutional neural network (CNN) was applied to automatically determine the bonding state of the coatings. The time–frequency representation of the waveform was used as the input to the CNN. The experimental results demonstrated that the proposed method automatically determines the bonding state of the coatings with high accuracy. The present approach is more efficient compared to the method of estimating bonding state using attenuation.

Optimized Mooring Line Simulation Using a Hybrid Method Time Domain Scheme

2014 ◽  
Author(s):  
Niels Hørbye Christiansen ◽  
Per Erlend Torbergsen Voie ◽  
Jan Høgsberg ◽  
Nils Sødahl
Keyword(s):  
Hybrid Method ◽  
Time Domain ◽  
Computation Time ◽  
Mooring Line ◽  
Mooring Lines ◽  
Fem Model ◽  
Input Variables ◽  
The Time Domain ◽  
The Cost ◽  
Short Time

Dynamic analyses of slender marine structures are computationally expensive. Recently it has been shown how a hybrid method which combines FEM models and artificial neural networks (ANN) can be used to reduce the computation time spend on the time domain simulations associated with fatigue analysis of mooring lines by two orders of magnitude. The present study shows how an ANN trained to perform nonlinear dynamic response simulation can be optimized using a method known as optimal brain damage (OBD) and thereby be used to rank the importance of all analysis input. Both the training and the optimization of the ANN are based on one short time domain simulation sequence generated by a FEM model of the structure. This means that it is possible to evaluate the importance of input parameters based on this single simulation only. The method is tested on a numerical model of mooring lines on a floating off-shore installation. It is shown that it is possible to estimate the cost of ignoring one or more input variables in an analysis.

Rational Design of Ultra-Short Anodic Alumina Nanotubes by Short-Time Pulse Anodization

2015 ◽  
Vol 154 ◽  
pp. 379-386 ◽  
Author(s):  
Ye Wang ◽  
Abel Santos ◽  
Andreas Evdokiou ◽  
Dusan Losic
Keyword(s):  
Rational Design ◽  
Anodic Alumina ◽  
Short Time ◽  
Time Pulse

scholarly journals Barycenter Theorem in Phase Characteristics of Symmetric and Asymmetric Windows

Symmetry ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 329
Author(s):  
Jiufei Luo ◽  
Haitao Xu ◽  
Kai Zheng ◽  
Xinyi Li ◽  
Song Feng
Keyword(s):  
Frequency Estimation ◽  
Random Noise ◽  
Estimation Algorithm ◽  
Frequency Component ◽  
Phase Response ◽  
Numeric Simulation ◽  
Simulation Results ◽  
The Time Domain ◽  
Short Time ◽  
The Relationship

Asymmetric windows are of increasing interest to researchers because of the nonlinear and adjustable phase response, as well as alterable time delay. Short-time phase distortion can provide an essential improvement in speech coding, and also has better performance in speech recognition. The merits of asymmetric windows in the aspect of spectral behaviors have an important function in frequency component detection and parameter estimation. In this paper, the phase response of windows were further studied, and the phase characteristics of symmetric and asymmetric windows are described. The relationship between the barycenter of windows in the time domain, and the phase characteristic at the center of the main lobe in the frequency domain, was established. In light of the relationship, an improved version of the asymmetric window- based frequency estimation algorithm was proposed. The improved algorithm has advantages of straightforward implementation and computational efficiency. The numeric simulation results also indicate that the improved approach is more robust than the traditional method against additive random noise.

scholarly journals Time-Domain Circuit Modelling for Hybrid Supercapacitors

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6837
Author(s):  
Fabio Corti ◽  
Michelangelo-Santo Gulino ◽  
Maurizio Laschi ◽  
Gabriele Maria Lozito ◽  
Luca Pugi ◽  
...  
Keyword(s):  
Time Domain ◽  
Black Box ◽  
Circuit Modeling ◽  
Hybrid Supercapacitor ◽  
Hybrid Supercapacitors ◽  
Linear Behavior ◽  
Modeling Techniques ◽  
The Time Domain ◽  
Short Time ◽  
Circuit Modelling

Classic circuit modeling for supercapacitors is limited in representing the strongly non-linear behavior of the hybrid supercapacitor technology. In this work, two novel modeling techniques suitable to represent the time-domain electrical behavior of a hybrid supercapacitor are presented. The first technique enhances a well-affirmed circuit model by introducing specific non-linearities. The second technique models the device through a black-box approach with a neural network. Both the modeling techniques are validated experimentally using a workbench to acquire data from a real hybrid supercapacitor. The proposed models, suitable for different supercapacitor technologies, achieve higher accuracy and generalization capabilities compared to those already presented in the literature. Both modeling techniques allow for an accurate representation of both short-time domain and steady-state simulations, providing a valuable asset in electrical designs featuring supercapacitors.

Design and Implementation of OFDM Modem for Low Voltage Narrowband Powerline Communication

2012 ◽  
Vol 505 ◽  
pp. 257-262
Author(s):  
Sheng Qing Zhang ◽  
Yi Feng Zhang ◽  
Zhao Li ◽  
Cai Rong Zou
Keyword(s):  
Low Voltage ◽  
Data Rate ◽  
Test Results ◽  
Powerline Communication ◽  
Module Design ◽  
Design And Implementation ◽  
Potential Market ◽  
Communication Module ◽  
Actual Test

Narrowband powerline communication has the great potential market application like Auto-Meter-Reading (AMR). This paper focuses on the design and implementation of narrowband powerline communication module with the OFDM technology. Firstly, it introduces the OFDM solution for low voltage powerline communication module design, then it describes the implementation of the sync module, Viterbi code translation module and FFT module based on FPGA platform in details. Finally, it provides the actual test results for the communication module. It shows, the communication data rate of the narrowband powerline communication is greatly improved with OFDM technology.

scholarly journals Far-Field Plume Characterization of a 100-W Class Hall Thruster

Aerospace ◽  
2020 ◽  
Vol 7 (5) ◽  
pp. 58
Author(s):  
Thibault Hallouin ◽  
Stéphane Mazouffre
Keyword(s):  
Energy Distribution ◽  
Current Density ◽  
Low Voltage ◽  
Ion Current ◽  
Hall Thruster ◽  
Far Field ◽  
Ion Energy ◽  
Ion Energy Distribution ◽  
The Core ◽  
Ion Current Density

The 100 W-class ISCT100-v2 Hall Thruster (HT) has been characterized in terms of far-field plume properties. By means of a Faraday Cup and a Retarding Potential Analyzer, both the ion current density and the ion energy distribution function have been measured over a 180 ∘ circular arc for different operating points. Measurements are compared to far-field plume characterizations performed with higher power Hall thrusters. The ion current density profiles remain unchanged whatever the HT input power, although an asymptotic limit is observed in the core of the plume at high discharge voltages and anode mass flow rates. In like manner, the ion energy distribution functions reveal that most of the beam energy is concentrated in the core of the plume [ − 40 ∘ ; 40 ∘ ] . Moreover, the fraction of low energy ion populations increases at large angles, owing to charge exchange and elastic collisions. Distinct plume regions are identified; they remain similar to the one described for high-power HTs. An efficiency analysis is also performed in terms of current utilization, mass utilization, and voltage utilization. The anode efficiency appears to be essentially affected by a low voltage utilization, the latter originating from the large surface-to-volume ratio inherent to low-power HTs. Experimental results also show that the background pressure clearly affects the plume structure and content.

The armies of the Ṣaffārids

1968 ◽  
Vol 31 (3) ◽  
pp. 534-554 ◽  
Author(s):  
C. E. Bosworth
Keyword(s):  
Ninth Century ◽  
The South ◽  
The West ◽  
Islamic World ◽  
North West ◽  
The Third ◽  
The Core ◽  
The North ◽  
Frontier Region ◽  
Short Time

It is not too much to describe the Ṣaffārids of S‚stān as an archetypal military dynasty. In the later years of the third/ninth century, their empire covered the greater part of the non-Arab eastern Islamic world. In the west, Ya'qūb. al-Laith's army was only halted at Dair al-'Āqūl, 50 miles from Baghdad; in the north, Ya'qūb and his brother 'Arm campaigned in the Caspian coastlands against the local 'Alids, and 'Amr made serious attempts to extend his power into Khwārazm and Transoxania; in the east, the two brothers pushed forward the frontiers of the Dār al-Islām into the pagan borderlands of what are now eastern Afghanistan and the North-West Frontier region of West Pakistan; and in the south, Ṣaffārid authority was acknowledged even across the persion Gulf in ‘Umān. This impressive achievement was the work of two soldiers of genius, Ya'qūub and 'Amr, and lasted for little more than a quarter of a century. It began to crumble when in 287/900 the Sāmānid Amīr Ismā'īl b. Aḥmad defeated arid captured ‘Amr b. al-Laith, and 11 years later, the core of the empire, Sīstān itself, was in Sāmānid hands. Yet such was the effect in Sīstān of the Ṣaffārid brothers’ achievement, and the stimulus to local pride and feeling which resulted from it, that the Ṣaffārids returned to power there in a very short time. For several more centuries they endured and survived successive waves of invaders of Sīstān—the Ghaznavids, the Seljūqs, the Mongols—and persisted down to the establishment of the Ṣafavid state in Persia.

Meshless - The Finite Element of a Direct Coupling Method Mechanical Problems in the Application

2012 ◽  
Vol 548 ◽  
pp. 421-424
Author(s):  
Jin Ping Wang ◽  
Yu Jing Gao ◽  
De Hua Wang
Keyword(s):  
Finite Element ◽  
Shape Function ◽  
Direct Coupling ◽  
Coupling Method ◽  
New Method ◽  
Field Function ◽  
The Core ◽  
Definition Of ◽  
Short Time ◽  
The Brain

Coupling method is developed in recent years to solve numerical problems a new method, meshless - the finite element of a direct coupling method is based on the definition of the generalized unit of coupling of the new method . The core of this method is the use of each unit in the shape function to the assumption that the brain that the whole sub-domain to be seeking to solve the unknown field function. Coupling with other compared with the method is simple to calculate the advantages of a short time.

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