Transmission Line Modeling of Laminar Liquid Wave Propagation in Tapered Tubes

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Travis Wiens ◽  
Jeremy ven der Buhs
Keyword(s):  
Wave Propagation ◽  
Transmission Line ◽  
High Frequency ◽  
Transfer Functions ◽  
Domain Modeling ◽  
Transmission Line Model ◽  
Computationally Efficient ◽  
Transmission Line Modeling ◽  
Time Domain Modeling ◽  
Pipe Inlet

This paper presents an improved method of time-domain modeling of pressure wave propagation through liquid media in rigid tapered pipes. The method is based on the transmission line model (TLM), which uses linear transfer functions and delays to calculate the pressures and/or flows at the pipe inlet and outlet. This method is computationally efficient and allows for variable rate simulation. The proposed form of the model differs from previous TLM models in the literature, allowing it to accurately model both low and high frequency characteristics.

Characteristic of Electromagnetic Noise Based on the Theory of Multiconductor Communication Line

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Yibo Ding ◽  
Kaiyan Zhang ◽  
Shishan Wang ◽  
Jian Guo
Keyword(s):  
Transmission Line ◽  
Transmission Lines ◽  
High Frequency ◽  
Transfer Functions ◽  
Communication Line ◽  
Electrical System ◽  
Electromagnetic Noise ◽  
Electrical Length ◽  
Voltage Loss ◽  
Small Voltage

Electromagnetic noise has serious influence on the performance of electrical system. In addition, while multiconductor cable harnesses play an important role in transmitting electromagnetic energy or signal between devices of electrical system, they are also the major path to transmit electromagnetic noise. Crosstalk, as typical electromagnetic noise within multi-conductor cable harnesses, is an important factor which affects the efficiency of transmission. In this paper, the n+1 transmission lines (n=2, n>2) are taken as the object of research. Based on the theory of Multi-conductor Transmission Line (MTL), the transmission of electromagnetic noise in transmission line is studied, including noise of generating line (called G-line) and line receiving interference (called R-line), the latter called crosstalk. Transfer functions of electromagnetic noise of G-line and R-line are simulated using FEKO (FEldberechnung bei Korpern mit beliebiger Oberflache). Two transfer functions are obtained to investigate the severity of noise of G-line and R-line. The characteristics of the parameters are also studied. Simulation results indicate that transfer functions have tight relationship with the electrical length. When the electrical length is small, voltage loss of interference line along the transmission line is relatively small, so is the far-end crosstalk; however, when the electrical length is large, voltage loss and the far-end crosstalk is larger, and resonances at high frequency. Keywords: Electromagnetic noise; FEKO; electrical length;

Modeling Arbitrarily Shaped Liquid Pipelines Using a Segmented Transmission Line Model

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Travis Wiens
Keyword(s):  
Transmission Line ◽  
Method Of Characteristics ◽  
Previous Method ◽  
New Method ◽  
Transmission Line Model ◽  
Computationally Efficient ◽  
Time Step ◽  
Line Model ◽  
Order Of Magnitude ◽  
Variable Time Step

Abstract This paper presents a new method of simulating the dynamic flow and pressure of laminar liquid flow through pipes of arbitrarily changing cross section. This method uses a segmented model based on the previously presented tapered transmission line model (TLM). This new method is computationally efficient and has comparable accuracy to previous methods such as the method of characteristics (MOC), but allow for more flexibility in solution time-step (such as accommodating variable time-step solvers), which is required if the rest of the system model has stiff equations. For the sample geometry presented, the new model calculates the dynamic response an order of magnitude faster than the previous method of characteristics solution, with minimal loss of accuracy.

H 2-Optimal Low Order Transmission Line Models

2019 ◽  
Author(s):  
Bernhard Manhartsgruber
Keyword(s):  
Power Systems ◽  
Transmission Line ◽  
Code Generation ◽  
Transfer Functions ◽  
Linear Time ◽  
State Space Model ◽  
Low Frequency ◽  
Transmission Line Model ◽  
Line Model ◽  
Low Order

Abstract Transmission line modeling has played a crucial role in understanding the dynamics of fluid power systems. A vast body of literature exists from simple lumped parameter approaches to fully coupled three-dimensional fluid structure interaction models. When it comes to computationally efficient, yet physically sound low order models needed for fast computations iteratively called by optimization codes or for the purpose of model based control design, there is still room for improvement. Modal approximations of the input-output behaviour of liquid transmission lines have been around for decades. The basic idea of tuning the parameters of a canonical linear time invariant state space model to fit the transfer functions of a transmission line model in the H2-optimal sense under passivity constraints has been published by the author of the present paper in the past. However, the method so far was barely usable due to numerical difficulties in the underlying optimization process. A new implementation of the method employing quadruple-precision floating point numbers has recently been found to resolve the convergence problems and is reported in the present paper. The new version of the method is based on analytic computation of the cost and constraint functions as well as their gradients in the computer algebra package Maple and automatic code generation for compilation in FORTRAN. Results are very promising because both the entire low frequency behaviour and the first three eigenmodes of a transmission line model can be accurately covered by a model of order eight only.

Time domain waveform inversion—A frequency domain view: How well we need to match waveforms?

1991 ◽  
Vol 81 (6) ◽  
pp. 2351-2370
Author(s):  
Zoltan A. Der ◽  
Robert H. Shumway ◽  
Michael R. Hirano
Keyword(s):  
Time Domain ◽  
High Frequency ◽  
Waveform Inversion ◽  
Quantitative Measure ◽  
Domain Modeling ◽  
Low Frequencies ◽  
Waveform Modeling ◽  
Time Domain Modeling ◽  
Frequency Components ◽  
The Time Domain

Abstract Waveform modeling in the time domain matches the various frequency components of seismic signals unevenly; the agreement is better at low frequencies and becomes progressively worse towards higher frequencies. The net effect of this kind of time-domain modeling is that the resolution in the spatial details of the source is less than optimal since the high-frequency components of the signal with their short wavelengths to resolve finer details do not fit the data. These problems are demonstrated by numerical simulations and by the reanalysis of some aspects of the El Golfo earthquake in using a new seismic imaging technique based on a generalization of an f-k algorithm. This procedure computes a statistic that can be used to derive confidence limits of the parameters sought in the inversion, thus providing a quantitative measure of the uncertainties in the results.

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