scholarly journals A Theory for Electromagnetic Radiation and Coupling

2021 ◽  
Author(s):  
gaobiao xiao
Keyword(s):  
Time Domain ◽  
Vector Potential ◽  
Poynting Vector ◽  
Electric Displacement ◽  
Radiative Energy ◽  
Total Power ◽  
Energy Term ◽  
Power Flux ◽  
Radiation Process ◽  
Short Time

A theory for analyzing the radiative and reactive electromagnetic energies of a radiator in vacuum is presented. In vacuum, the radiative electromagnetic energies will depart from their sources and travel to infinity, generating a power flux in the space. However, the reactive electromagnetic energies are bounded to their sources. They appear and disappear almost in the same time with their sources, and their fluctuation also causes a power flux in the space. In the proposed theory, the reactive electromagnetic energies of a radiator are defined by postulating that they have properties similar to the self-energies in the charged particle theory. More importantly, in addition to a main term of source-potential products, the reactive energies contain a special energy term which will last to exist a short time after the sources disappear. This oscillating energy is related to the electric displacement and the vector potential, and seems to be responsible for energy exchanging between the reactive energy and the radiative energy in the radiation process, performing like the Schott energy term. As the Poynting vector describes the total power flux density related to the total electromagnetic energy, it should include the contributions of the propagation of the radiative energies and the fluctuation of the reactive energies. The mutual electromagnetic couplings between two radiators are also defined in a similar way in which the vector potential plays a central role. The reactive electromagnetic energies can be evaluated with explicit expressions in time domain and frequency domain. The theory is verified with the Hertzian dipole and numerical examples.

scholarly journals A Theory for Electromagnetic Radiation and Coupling

2021 ◽  
Author(s):  
gaobiao xiao
Keyword(s):  
Time Domain ◽  
Vector Potential ◽  
Poynting Vector ◽  
Electric Displacement ◽  
Radiative Energy ◽  
Total Power ◽  
Energy Term ◽  
Power Flux ◽  
Radiation Process ◽  
Short Time

A theory for analyzing the radiative and reactive electromagnetic energies of a radiator in vacuum is presented. In vacuum, the radiative electromagnetic energies will depart from their sources and travel to infinity, generating a power flux in the space. However, the reactive electromagnetic energies are bounded to their sources. They appear and disappear almost in the same time with their sources, and their fluctuation also causes a power flux in the space. In the proposed theory, the reactive electromagnetic energies of a radiator are defined by postulating that they have properties similar to the self-energies in the charged particle theory. More importantly, in addition to a main term of source-potential products, the reactive energies contain a special energy term which will last to exist a short time after the sources disappear. This oscillating energy is related to the electric displacement and the vector potential, and seems to be responsible for energy exchanging between the reactive energy and the radiative energy in the radiation process, performing like the Schott energy term. As the Poynting vector describes the total power flux density related to the total electromagnetic energy, it should include the contributions of the propagation of the radiative energies and the fluctuation of the reactive energies. The mutual electromagnetic couplings between two radiators are also defined in a similar way in which the vector potential plays a central role. The reactive electromagnetic energies can be evaluated with explicit expressions in time domain and frequency domain. The theory is verified with the Hertzian dipole and numerical examples.

scholarly journals A Theory for Electromagnetic Radiation and Coupling

2021 ◽  
Author(s):  
gaobiao xiao
Keyword(s):  
Time Domain ◽  
Vector Potential ◽  
Poynting Vector ◽  
Electric Displacement ◽  
Radiative Energy ◽  
Total Power ◽  
Energy Term ◽  
Power Flux ◽  
Radiation Process ◽  
Short Time

A theory for analyzing the radiative and reactive electromagnetic energies of a radiator in vacuum is presented. In vacuum, the radiative electromagnetic energies will depart from their sources and travel to infinity, generating a power flux in the space. However, the reactive electromagnetic energies are bounded to their sources. They appear and disappear almost in the same time with their sources, and their fluctuation also causes a power flux in the space. In the proposed theory, the reactive electromagnetic energies of a radiator are defined by postulating that they have properties similar to the self-energies in the charged particle theory. More importantly, in addition to a main term of source-potential products, the reactive energies contain a special energy term which will last to exist a short time after the sources disappear. This oscillating energy is related to the electric displacement and the vector potential, and seems to be responsible for energy exchanging between the reactive energy and the radiative energy in the radiation process, performing like the Schott energy term. As the Poynting vector describes the total power flux density related to the total electromagnetic energy, it should include the contributions of the propagation of the radiative energies and the fluctuation of the reactive energies. The mutual electromagnetic couplings between two radiators are also defined in a similar way in which the vector potential plays a central role. The reactive electromagnetic energies can be evaluated with explicit expressions in time domain and frequency domain. The theory is verified with the Hertzian dipole and numerical examples.

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 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.

scholarly journals Electromagnetic Energy Balance Equations and Poynting Theorem

2020 ◽  
Author(s):  
gaobiao xiao
Keyword(s):  
Energy Balance ◽  
Flux Density ◽  
Poynting Vector ◽  
Power Balance ◽  
Time Varying ◽  
Balance Equations ◽  
Power Flux ◽  
Modified Method ◽  
Electromagnetic Power ◽  
Poynting Theorem

<p>Poynting theorem plays a very important role in analyzing electromagnetic phenomena. The electromagnetic power flux density is usually expressed with the Poynting vector. However, since Poynting theorem basically focuses on the power balance in a system, it is not so convenient in some situations to use it for evaluating the electromagnetic energies. The energy balance issue for time varying fields is revisited in this paper, and a set of energy balance equations are introduced, and a modified method for evaluating power flux is proposed.</p>

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.

Time-Domain Characteristics Analysis of Penetration Arc Sound Signal in MIG Welding

2010 ◽  
Vol 154-155 ◽  
pp. 453-456
Author(s):  
Li Jun Liu ◽  
Qi Wang ◽  
Lan Hu
Keyword(s):  
Time Domain ◽  
Sound Signal ◽  
Pitch Estimation ◽  
Zero Crossing ◽  
Butt Welding ◽  
Spray Transfer ◽  
Characteristics Analysis ◽  
Short Time ◽  
Arc Sound ◽  
Arc Sound Signal

Many important time-domain characteristic parameters are extracted through the short-time analysis of arc sound signal in MIG butt welding with spray transfer, which can be used for the diagnosis on the weld penetration status. And the short-time autocorrelation function and short-time average amplitude difference function are adopted to pitch estimation. The analysis results show that the penetration status can be accurately recognized via the short-time energy, average magnitude, average zero-crossing and zero-to-energy and so on. Meanwhile, the pitch estimation of arc sound signal in experiments is at 220 points, that is 5 ms or 200 Hz in cycle. The methods and results provide a foundation for the diagnosis on penetration based on analysis of arc sound signal and have great theoretical meaning and practical value.

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