Electric Coupling Parameters Research Articles

Evaluation of the benefits of Functional Open Coupling of trains for railway undertakings and passengers

Within the Shift2Rail Joint Undertaking (S2R JU), technologies are developed to improve the future railway system. An important S2R innovation is "Functional Open Coupling" (FOC), an interoperable coupling of trains. Research on FOC is carried out in the S2R projects CONNECTA-1/2/3. With FOC it is possible to couple trains of different manufacturers, classes, and series as it is not possible today due to different control and electrical coupling parameters. To assess the overall impact of S2R innovations such as FOC on the railway system, an integrated methodology using key performance indicators (KPI) is developed in the cross-cutting activity Project IMPACT-2. The cooperation of the two S2R projects made it possible to conduct an in-depth analysis of the potential impact of FOC on the KPI life cycle costs, capacity and customer satisfaction.

Structural multi-modal damping by optimizing shunted piezoelectric transducers

The capacity of different auto-supplied devices using shunted piezoelectric circuits are studied here to improve structural damping by avoiding implementation of complex and heavy control devices. The presented technique uses a dedicated numerical piezo-mechanical model combining both mechanical and electrical coupling parameters. An original methodology are also introduced for optimizing the parameters of electrical shunt circuits connected to piezoelectric elements and also structural locations of these integrated transducers. The results, experimentally validated (on beams and a plate), demonstrate that vibrations can be significantly reduced when shunted piezoelectric devices are mounted on a real structure. Finally, the proposed methodology is used for optimizing shape and location of the shunted piezoelectric patches to damp several modes of a plate.

Structural multi-modal damping by optimizing shunted piezoelectric transducers

The capacity of different auto-supplied devices using shunted piezoelectric circuits are studied here to improve structural damping by avoiding implementation of complex and heavy control devices. The presented technique uses a dedicated numerical piezo-mechanical model combining both mechanical and electrical coupling parameters. An original methodology are also introduced for optimizing the parameters of electrical shunt circuits connected to piezoelectric elements and also structural locations of these integrated transducers. The results, experimentally validated (on beams and a plate), demonstrate that vibrations can be significantly reduced when shunted piezoelectric devices are mounted on a real structure. Finally, the proposed methodology is used for optimizing shape and location of the shunted piezoelectric patches to damp several modes of a plate.

Measurement of interstrand conductance in multistrand superconducting cables

Multistrand superconducting cables are widely used in large scale applications to obtain large current carrying capacity. Stability is one of the key issues that ensure continuous and reliable operation of superconducting cables. Knowledge of interstrand conductance is essential for analysis of current distribution and redistribution processes that substantially influence the stability of multistrand superconducting cables. In this paper, an approach to measure interstrand conductance is developed using parametric estimation method as used in control theory. First, a distributed parameter circuit model is adopted to calculate the current and voltage distribution in superconducting cables. Then, strand voltage differences at cable ends are measured by experiment. Finally, least squares method is applied to estimate the interstrand conductance which gives the minimum error of the voltage difference at cable ends between calculated and measured data. The interstrand conductance between the subcables in different cabling stages in a cable-in-conduit conductor (CICC) has been studied under different conditions (different temperatures and different cable lengths). The results are consistent, accurate, and fit the distributed parameters circuit model well. This method provides a convenient approach to evaluate electrical coupling parameters in multistrand superconducting cables under different conditions. The estimated parameters can be used to improve the accuracy of analysis of current distribution and cable stability.

Analysis of Inductance Coefficients in Multistrand Cables: Analytical, Numerical, and Experimental Results

The evaluation of electrical coupling parameters in multistrand cables is a fundamental prerequisite for the calculation of current distribution and ac-losses in superconducting cables. The theoretical evaluation of these parameters requires a detailed description of the cable geometry. A code for the geometric description of generic multistrand multistage cables and for the calculation of the strand self- and mutual inductance coefficients has been developed. An extensive measurement campaign using straight and wound twisted multistage copper cables has been performed in order to validate the numerical model. An indirect measurement method has been used for the evaluation of the self-inductances of the wires in the straight cable. These results build a database that can be used to validate several numerical codes written in recent years for the analysis of electrical coupling parameters in superconducting cables.

Electrical Coupling Parameter Reconstruction From System Model in Multistrand Superconducting Cables

Current distribution in multistrand superconducting cables has substantial influence on stability. Any analysis of current distribution requires knowledge of the electrical coupling parameters, (e.g., self and mutual inductances, and the interstrand contact conductance). In this paper, a new approach that reconstructs the parameters from distributed parameter circuit model of multistrand superconducting cable is proposed. The strand currents are measured by experiment and treated as known conditions. The unknown parameters are then extracted from the partial differential equations that describe the current distribution. The desired results are found to be the minimum norm least squares solution that best fit the system equations and minimize errors. A code is developed to implement this reverse identification process. The results are validated by substituting the reconstructed parameters to the system equations for simulation and then comparing with current distribution experiments. The parameters are also compared with those from conventional experimental methods, (e.g., DC four-point method to measure interstrand conductance). This method, using parametric identification theory, provides a way to evaluate the electrical coupling parameters in multistrand superconducting cables under different conditions (current density and frequency, mechanical loads, etc.). The calculated parameters can be used in analysis of current distribution and cable stability.

The window Josephson junction: a coupled linear nonlinear system

We investigate the interface coupling between the two-dimensional sine-Gordon equation and the two-dimensional wave equation in the context of a Josephson window junction using a finite volume numerical method and soliton perturbation theory. The geometry of the domain as well as the electrical coupling parameters are considered. When the linear region is located at each end of the nonlinear domain, we derive an effective one-dimensional model, and using soliton perturbation theory, compute the fixed points that can trap either a kink or antikink at an interface between two sine-Gordon media. This approximate analysis is validated by comparing with the solution of the partial differential equation and describes kink motion in the one-dimensional window junction. Using this, we analyze steady-state kink motion and derive values for the average speed in the one- and two-dimensional systems. Finally, we show how geometry and the coupling parameters can destabilize kink motion.

Ethanol uncouples dentate granule neurons by increasing junctional resistance: A multineuronal system model approach

The effects of an acute intoxicating concentration of ethanol (50 mM) on the electrotonic membrane properties of hippocampal dentate granule neurons were studied using a system model incorporating electrotonic coupling between neurons. Uncoupling of cells by other alcohols has been shown in several tissues. The system model allows a quantitative estimation of the changes in coupling and other neuronal electrotonic properties. The input impedance of a neuron was measured from the voltage decay of a short hyperpolarizing current pulse. An analytic expression of the input impedance has been written incorporating somatic, dendritic and electrical coupling parameters. Using this particular current stimulation, the modelling results showed that ethanol selectively increased the junctional resistance by more than 2.5 times, hence uncoupling the neurons. A 30% increase in the final time-constant, τ 0, was also obtained from the voltage transient. Other parameters were not significantly affected. A neuronal model without electrotonic coupling to other neurons gave rise to physiologically impossible values for the membrane resistance and capacitance. With resistive and capacitive coupling in the model, uncoupling did not occur with ethanol. It is concluded that ethanol uncouples neurons by increasing the effective gap junctional resistance in dentate granule neurons.

General crosstalk equations between two braided coaxial cables in free space

Earlier theoretical studies consider current dominant coupling only as being responsible for crosstalk between two coaxial cables and ignore coupling due to electric field parameters. In the paper, general crosstalk equations between two similar braided coaxial cables are derived by including both electric and magnetic coupling parameters in the analysis. The numerical studies based on the derived coupling models are applied to various braid constructions and load configurations are imposed on the tertiary circuit to assess the relative importance of each coupling parameter. From these studies, it is shown that the theoretical treatments which are based on the current dominant coupling give an incomplete assessment of the physical process and, even with a short-circuited tertiary, electric coupling parameters may play an important role in determining the coupling pattern for certain braid constructions.

Terminal Response of Braided-Shield Cables to External Monochromatic Electromagnetic Fields

This paper has two purposes: (1) to assess the relative importance of magnetic and electric coupling parameters of braided shields in the determination of terminal response of braided-shield cables to external electromagnetic fields and (2) to compare a postulated coupling model with those on which various experimental determinations of shielding effectiveness have been based. In the first case, formulas for certain special conditions of wave incidence and sheath-conductor terminations are obtained, but their implications are not explored in detail. In the second case, certain discrepancies among various published methods of measurement and between the measurements and the postulated model are noted. The paper also shows formally how the external-field coupling parameters to each conductor of a multiconductor cable may be determined. A review of earlier work indicated that measurements made in the past have been largely incomplete. In some cases, only the effect of the inductance parameter was measured; in others, the composite effect of both inductive and capacitive coupling was measured, but attributed to inductance only. In either category, this analysis shows that the use of such a limited physical model will generally lead to inaccurate predictions of cable terminal response.