The dynamic flowsheet simulation of solids processes is an area of increasing interest in recent years. Compared to the well-established flowsheet modelling of liquid-gas systems, the modelling of granular materials r...
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The dynamic flowsheet simulation of solids processes is an area of increasing interest in recent years. Compared to the well-established flowsheet modelling of liquid-gas systems, the modelling of granular materials requires different approaches, strategies and algorithms. Therefore the new dynamic flowsheet simulation framework Dyssol has been developed within the Priority Program SPP 1679 "Dynamic simulation of interconnected solids processes (DYNSIM-FP)" of the German Research Foundation (DFG). In this contribution the architecture of the novel simulation framework and computational methods employed in it are presented. The system is based on the sequential-modular approach supplemented with partitioning and tearing methods. Waveform relaxation method, as well as several convergence methods and data extrapolation algorithms have been implemented to improve system performance and to increase convergence rate. To perform a correct calculation of multidimensional distributed parameters an approach with transformation matrices is used in the Dyssol system. Simulation case studies calculated with new system have showngood stability, convergence rate and agreement of simulation results with test systems and experimental results. (C) 2017 Elsevier B.V. All rights reserved.
The dynamic modelling and simulation of the three sections of a water desalination facility using the Solar Multiple Condensation Evaporation Cycle (SMCEC) technique are presented. The models are obtained using therma...
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The dynamic modelling and simulation of the three sections of a water desalination facility using the Solar Multiple Condensation Evaporation Cycle (SMCEC) technique are presented. The models are obtained using thermal energy and mass balances of the different sections of the unit. The resulting distributed parametric systems of equations are transformed into a system of ordinary differential equations using the orthogonal collocation method. The parametric study in the dynamic mode and the numerical simulation allow to predict the behaviour of output of each of the three unit sections following variations in the internal signals and external perturbations.
An analytical model that allows one to determine the high-frequency current distribution in a thin-film comb thermal converter is presented. This model takes into account the influence of the shunting effect of a ther...
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An analytical model that allows one to determine the high-frequency current distribution in a thin-film comb thermal converter is presented. This model takes into account the influence of the shunting effect of a thermopile on the high-frequency current distribution in the thermal converter. The structure of the thermal converter is treated as a distributed-parameter structure. The distributed parameters of the structure are analyzed as applied to a thermal converter in which hot thermojunctions of a thermopile are situated above a heater. A system of equations that relates the high-frequency currents and the voltage in the thermal converter and takes into account the capacitive and inductive couplings between the heater and the thermopile and the periodicity of these couplings and the resistance per unit length of the thermopile is obtained. This system of equations is solved analytically by its transformation to one parameter task. Expressions for the high-frequency currents in the heater and the thermopile are obtained. The present model is used to determine the high-frequency current distribution in the realistic structure of the thin-film comb thermal converter. (c) 2005 Elsevier B.V. All rights reserved.
A long grounded wire in the transient electromagnetic (TEM) surveys is usually considered by using the lumped parameter circuit model, which fails to explicate the early turn-OFF current with crucial importance for TE...
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A long grounded wire in the transient electromagnetic (TEM) surveys is usually considered by using the lumped parameter circuit model, which fails to explicate the early turn-OFF current with crucial importance for TEM surveys. In this paper, the transmission line model is introduced for the first time to explicate the early turn-OFF current in the long grounded wire considering the high frequency at early turn-OFF stage. The transmission line model suitable for the long grounded wire is constructed, then the calculation formulas of the distributed parameters and load impedance are analyzed, and the transfer function utilized to simulate the current at any position of the transmission line is also derived. The simulation is performed in the frequency domain with subsequent transformation into the time domain, and the simulation results are in good agreement with the experimental data. The early turn-OFF currents depending on the earth resistivity vary with the position in the long grounded wire. Therefore, the early time TEM response differs from that predicted by the classical theory of the TEM surveys. This proposed model can guide the realization of the minimum current turn-OFF duration, which will help to reduce the detection blind spot and this paper provides new ideas and prospects for early response data and current waveform data for interpretation in the geophysics detection.
The internal model proposed is a nonlinear system of a few partial differential equations. The boundary conditions for the differential equations are specified at the lumber board entrance and between the wood and air...
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The internal model proposed is a nonlinear system of a few partial differential equations. The boundary conditions for the differential equations are specified at the lumber board entrance and between the wood and air. The initial conditions are calibrated by solving the static model and by the technical experiment. In conclusion, it can be said that the consistency of the model with experimental results seems to be reasonably good and can be used for process simulation and control.
Based on several extended formulas to determine all frequency- and temperature-dependent distributed parameters of on-chip coupled asymmetrical and symmetrical interconnects on silicon substrates, the electromagnetic-...
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Based on several extended formulas to determine all frequency- and temperature-dependent distributed parameters of on-chip coupled asymmetrical and symmetrical interconnects on silicon substrates, the electromagnetic-thermal characteristics of interconnects were investigated in detail, including 1) wideband series impedances and shunt conductances, 2) conductive and dielectric attenuation constants of even(c) and odd (pi)-mode, 3) pulse waveform distortion and crosstalk, and 4) average power handling capability (APHC). In these investigations, a set of modified formulas were proposed to determine the mutual conductance and capacitance of asymmetrical configuration. Appropriate thermal models were employed to evaluate the rise in temperature of metal interconnects, where the lateral heat dissipation was taken into account for different spacings between two interconnects. Parametric calculations were performed to capture the hybrid effects of all geometric and physical parameters of metal interconnects, such as line thickness, line conductivity, and silicon conductivity. All numerical examples are believed to be useful in the design of (a)symmetrical interconnects for digital and radio frequency circuits.
This paper proposes a tool of assistance to prelocate insulation faults affecting electrical single-phase cables by using measurements of voltage and current available in source substation. An equivalent network model...
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This paper proposes a tool of assistance to prelocate insulation faults affecting electrical single-phase cables by using measurements of voltage and current available in source substation. An equivalent network modeling faults to the ground is analyzed by employing the distributed parameters approach. The per-unit length values of these parameters are calculated according to the geometrical data of the cable. The specificity of this tool is the introduction of a resistance to model sheath-ground insulation what allows studying various types of short-circuits to the ground (frank and resistive). Scenarios of fault are applied to the underground cable 150 kV, connecting high voltage (HTB) sub-stations of Tyna-Taparoura-Sidimansour in Sfax city of Tunisia. A study of validation is approved by the software Simulink-SimPowerSystems of Matlab. (C) 2012 Elsevier Ltd. All rights reserved.
This paper presents a fault location method suitable for untransposed four-circuit parallel transmission lines using the data available at one end of the line. The proposed method employs an accurate distributed param...
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This paper presents a fault location method suitable for untransposed four-circuit parallel transmission lines using the data available at one end of the line. The proposed method employs an accurate distributed parameter line model that fully accounts for mutual coupling between all the lines and shunt capacitance effects. The fault location algorithms are developed in phase-components, one for the case where the fault is in any one of the circuits, the second for the case where the fault involves any two circuits and the third for the case where the fault involves more than two circuits. The proposed method is tested using the transient data obtained by simulating a 500-kV four-circuit overhead transmission line under different fault conditions. The simulations are done using the software "DIgSILENT PoweFactory". Results obtained indicate that the method is capable of estimating the fault distance with high accuracy for various fault conditions. Also the robustness of the fault location method is investigated. (C) 2012 Elsevier Ltd. All rights reserved.
This paper presents an effective fault location technique for transmission grids based on phasor measurement units (PMUs). High accuracy in fault location is achieved by using both the fault observability with PMUs pl...
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This paper presents an effective fault location technique for transmission grids based on phasor measurement units (PMUs). High accuracy in fault location is achieved by using both the fault observability with PMUs placement and an accurate distributed parameter line model for the transmission lines. The work performed in this paper is provided with high performance which is simplicity, sensitivity, stability and featuring robustness to the uncertainties in fault inception angle, load current and fault path resistance, and the accuracy and reliability of the calculation for the technique is very high. This paper illustrates the characteristics of the proposed algorithm and evaluates its performance by using transient fault data obtained from PSCAD/EMTDC simulations. (C) 2012 Published by Elsevier Ltd.
Structures can be regarded as distributed-parameter systems characterized by mass, damping, and stiffness distributions. A perturbation technique converging iteratively to the parameter distributions is presented. The...
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Structures can be regarded as distributed-parameter systems characterized by mass, damping, and stiffness distributions. A perturbation technique converging iteratively to the parameter distributions is presented. The technique is based on the finite element method and does not require a full array of measurements.
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