Efficient representation of short-time phase based on time-domain smoothed group delay

2003 ◽  
Vol 86 (10) ◽  
pp. 56-64
Author(s):  
Hideki Banno ◽  
Jinlin Lu ◽  
Satoshi Nakamura ◽  
Kiyohiro Shikano ◽  
Hideki Kawahara
Keyword(s):  
Time Domain ◽  
Group Delay ◽  
Efficient Representation ◽  
Short Time

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.

scholarly journals Very compact UWB antenna with group delay improvement

2015 ◽  
Vol 12 (2) ◽  
pp. 197-204 ◽  
Author(s):  
Esmaeel Tahanian ◽  
Hamidreza Hasani
Keyword(s):  
Time Domain ◽  
Return Loss ◽  
Group Delay ◽  
Frequency Characteristics ◽  
Back Side ◽  
Antenna Gain ◽  
Uwb Antenna ◽  
Delay Variations ◽  
The Time Domain

In this paper, very compact (12mm?17mm) and simple UWB antenna is proposed. The achieved bandwidth of the presented antenna is from 3.05 GHz to 12.5 GHz and in the most of the bandwidth, the return loss is less than -20dB. In addition to frequency characteristics, time characteristics such as group delay variations for three different antenna positions, namely, front to front, back to back and side by side using CST MW studio are simulated and discussed. To improve the group delay variations, by changing the radius of the circle on the back side of the antenna, the antenna gain in different frequencies will be tuned, therefore, the time domain characteristics of the proposed antenna are greatly improved.

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.

Position Estimation for IR-UWB Systems

2018 ◽  
pp. 274-316
Author(s):  
Eva Lagunas ◽  
Monica Navarro ◽  
Pau Closas ◽  
Montse Najar ◽  
Ricardo Garcia-Gutierrez ◽  
...  
Keyword(s):  
Wireless Networks ◽  
Time Domain ◽  
Spatial Domain ◽  
Position Estimation ◽  
Promising Candidate ◽  
Emitter Location ◽  
Step Procedure ◽  
Toa Estimation ◽  
Single Emitter ◽  
Short Time

IR-UWB has emerged as a promising candidate for positioning passive nodes in wireless networks due to its extremely short time domain transmitted pulses. The two-step approaches in which first different TOAs are estimated and then fed into a triangulation procedure are suboptimal in general. This is because in the first stage of these methods, the measurements at distinct anchors are independent and ignore the constraint that all measurements must be consistent with a single emitter location. In this chapter, the authors investigate two techniques to overcome this issue. First, a two-step procedure based on multi-TOA estimation is proposed. Second, a positioning approach omitting the intermediate known as DPE is presented. Complementarily, the authors explore the CS-based modeling of both approaches so that the temporal sparsity of the UWB received signal and the consequent sparseness of the discrete spatial domain are exploited to select the most significant TOAs and to reduce the amount of information to be sent to a central fusion unit in the DPE approach.

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