scholarly journals The Detailed Doubly Fed Induction Wind Generator for Electromagnetic Transients Calculations and its Initialization in ATP

2021 ◽  
Author(s):  
Guillermo David Guidi Venerdini ◽  
Enrique Esteban Mombello
Keyword(s):  
Steady State ◽  
Electromagnetic Transients ◽  
Model Parameters ◽  
State Behavior ◽  
Detailed Model ◽  
Steady State Condition ◽  
Wind Generator ◽  
Automatic Initialization ◽  
Doubly Fed ◽  
Two Stages

Abstract The Alternative Transients Program (ATP) is one of the most used electromagnetic transient programs due to its powerful modeling capability and versatility. However, it has limitations as regards the automatic initialization of power electronics devices and control systems. To overcome this drawback, a simple methodology is presented in this paper to initialize a detailed model of a doubly fed induction wind generator implemented in ATP. The methodology is based on the automatic initialization of this device and it is divided into two stages. The first one consists of offline calculations to obtain initial steady-state values of certain model variables and, in the second one, these results are used as ATP model parameters. The simulation is started by means of auxiliary switches also included in the model. To validate the methodology, the transient and steady-state behavior of 4 case studies was evaluated. The analysis of these results shows that the steady-state values calculated by ATP for t = 0 are the desired ones and the oscillograms present a steady-state condition. The proposed methodology makes it possible to accurately initialize a detailed DFIG-type generator model in ATP, without the need to sacrifice simulation time to wait for variables to reach a steady state.

An Empirical Model for the Prediction of Hemodialysis System Performance

2011 ◽  
Author(s):  
Jane Kang ◽  
Amit Jariwala ◽  
David W. Rosen
Keyword(s):  
Steady State ◽  
Time Constant ◽  
Empirical Model ◽  
Prediction Method ◽  
Fixed Time ◽  
State Behavior ◽  
Steady State Condition ◽  
Inverse Simulation ◽  
Optimal Inputs ◽  
Final Steady State

The examination of steady state behavior of hemodialysis treatment using the analytical model created by Olson et al. revealed that for each set of hemodialysis conditions, a fixed time constant exists that dictates how quickly the patient’s waste level cycle reaches a steady state condition. They also revealed that initial waste level does not affect the final steady state waste level. In this study, an empirical model for the time constant and the final steady state maximum waste level were found that lumps hemodialysis inputs such as flow rates, dialyzer properties, and patient waste generation by conducting a parametric study on a previous hemodialysis model from Olson et al. [1] The empirical model is validated by comparing the curve that predicts how the peak waste level of each cycle changes over time with the analytical model’s results. For all the tested input values which cover most of practical hemodialysis treatments, the curve closely matched the numerical model’s results with R2 value higher than .9973. The empirical model created in this study provides a much simpler prediction method without the use of complex numerical simulations. In addition, the Olson model cannot be used to run an inverse simulation to determine optimal inputs for desired outputs. This limitation is overcome by our empirical model, which further allows much easier and more extended exploration of different therapies (dose length and schedule) for both doctors and renal replacement system designers.

scholarly journals Development of a Marine Two-Stroke Diesel Engine MVEM with In-Cylinder Pressure Trace Predictive Capability and a Novel Compressor Model

2020 ◽  
Vol 8 (3) ◽  
pp. 204 ◽  
Author(s):  
Haosheng Shen ◽  
Jundong Zhang ◽  
Baicheng Yang ◽  
Baozhu Jia
Keyword(s):  
Steady State ◽  
Diesel Engine ◽  
Spark Ignition Engine ◽  
Model Parameters ◽  
Analytic Model ◽  
Cylinder Pressure ◽  
Simulation Accuracy ◽  
Steady State Condition ◽  
Pressure Trace ◽  
D Model

In this article, to meet the requirements of marine engine room simulator on both the simulation speed and simulation accuracy, a mean value engine model (MVEM) for the 7S80ME-C9.2 marine two-stroke diesel engine was developed and validated in the MATLAB/Simulink environment. In consideration of the significant influence of turbocharger compressor on both the engine steady state performance and transient response, a novel compressor model (mass flow rate and isentropic efficiency model) based on a previous study carried out by the first author was proposed with the aim of achieving satisfactory simulation accuracy within the whole engine operating envelope. The predictive and extrapolative capability of the proposed compressor model was validated by carrying out simulation experiments and analyzing the simulation results under steady state condition and during transient process. To make the traditional MVEM capable of predicting in-cylinder pressure trace, the cylinder pressure analytic model proposed by Eriksson and Andersson for the four-stroke SI (spark ignition) engine was adapted to the 7S80ME-C9.2 marine two-stroke diesel engine based on the characteristic of in-cylinder pressure trace of this type of engine and then coupled to the MVEM developed in this paper. Since there is no need to solve any differential equation as it is done in the 0-D model, the advantage of MVEM in running speed is not impaired. For achieving satisfactory simulation accuracy by using the analytic model, the model parameters were calibrated elaborately by using engine measured data and a 0-D model and the relevant tuning procedure was discussed in detail.

An Information-theoretical Model for Breast Cancer Detection

2008 ◽  
Vol 47 (04) ◽  
pp. 322-327 ◽  
Author(s):  
D. Blokh ◽  
N. Zurgil ◽  
I. Stambler ◽  
E. Afrimzon ◽  
Y. Shafran ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Detection ◽  
Hamming Distance ◽  
Formal Model ◽  
Methodological Approach ◽  
Breast Cancer Detection ◽  
Receptor Expression ◽  
Diagnostic Model ◽  
Model Parameters ◽  
Two Stages

Summary Objectives: Formal diagnostic modeling is an important line of modern biological and medical research. The construction of a formal diagnostic model consists of two stages: first, the estimation of correlation between model parameters and the disease under consideration; and second, the construction of a diagnostic decision rule using these correlation estimates. A serious drawback of current diagnostic models is the absence of a unified mathematical methodological approach to implementing these two stages. The absence of aunified approach makesthe theoretical/biomedical substantiation of diagnostic rules difficult and reduces the efficacyofactual diagnostic model application. Methods: The present study constructs a formal model for breast cancer detection. The diagnostic model is based on information theory. Normalized mutual information is chosen as the measure of relevance between parameters and the patterns studied. The “nearest neighbor” rule is utilized for diagnosis, while the distance between elements is the weighted Hamming distance. The model concomitantly employs cellular fluorescence polarization as the quantitative input parameter and cell receptor expression as qualitative parameters. Results: Twenty-four healthy individuals and 34 patients (not including the subjects analyzed for the model construction) were tested by the model. Twenty-three healthy subjects and 34 patients were correctly diagnosed. Conclusions: The proposed diagnostic model is an open one,i.e.it can accommodate new additional parameters, which may increase its effectiveness.

Holdup and holdup profiles in the reciprocating plate extractor VPE

1990 ◽  
Vol 55 (11) ◽  
pp. 2648-2661 ◽  
Author(s):  
Helena Sovová ◽  
Vladislav Bízek ◽  
Jaroslav Procházka
Keyword(s):  
Steady State ◽  
Experimental Results ◽  
Model Parameters ◽  
Dispersed Phase ◽  
Pulse Form ◽  
Sieve Plates

In this work measurements of mean holdup of dispersed phase, of axial holdup profiles and of flooding points in a reciprocating plate contactor with both the VPE-type plates and the sieve plates were carried out. The experimental results were compared with a monodisperse model of steady-state column hydrodynamics and the model parameters were evaluated. Important differences in the behaviour of the two plate types could be identified. Comparison was also made between two reciprocating drives of different pulse form.

Steady-state stability of the doubly fed synchronous machine

1968 ◽  
Vol 4 (1) ◽  
pp. 18-19 ◽  
Author(s):  
R.D. Jackson ◽  
B.W. Phillips
Keyword(s):  
Steady State ◽  
Synchronous Machine ◽  
Doubly Fed ◽  
Steady State Stability

scholarly journals Computational Performance of Disparate Lattice Boltzmann Scenarios under Unsteady Thermal Convection Flow and Heat Transfer Simulation

Computation ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 65
Author(s):  
Aditya Dewanto Hartono ◽  
Kyuro Sasaki ◽  
Yuichi Sugai ◽  
Ronald Nguele
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Natural Convection ◽  
Lattice Boltzmann ◽  
Numerical Results ◽  
Convection And Heat Transfer ◽  
Steady State Condition ◽  
Physical Systems ◽  
Flow And Heat Transfer ◽  
Computational Performance

The present work highlights the capacity of disparate lattice Boltzmann strategies in simulating natural convection and heat transfer phenomena during the unsteady period of the flow. Within the framework of Bhatnagar-Gross-Krook collision operator, diverse lattice Boltzmann schemes emerged from two different embodiments of discrete Boltzmann expression and three distinct forcing models. Subsequently, computational performance of disparate lattice Boltzmann strategies was tested upon two different thermo-hydrodynamics configurations, namely the natural convection in a differentially-heated cavity and the Rayleigh-Bènard convection. For the purposes of exhibition and validation, the steady-state conditions of both physical systems were compared with the established numerical results from the classical computational techniques. Excellent agreements were observed for both thermo-hydrodynamics cases. Numerical results of both physical systems demonstrate the existence of considerable discrepancy in the computational characteristics of different lattice Boltzmann strategies during the unsteady period of the simulation. The corresponding disparity diminished gradually as the simulation proceeded towards a steady-state condition, where the computational profiles became almost equivalent. Variation in the discrete lattice Boltzmann expressions was identified as the primary factor that engenders the prevailed heterogeneity in the computational behaviour. Meanwhile, the contribution of distinct forcing models to the emergence of such diversity was found to be inconsequential. The findings of the present study contribute to the ventures to alleviate contemporary issues regarding proper selection of lattice Boltzmann schemes in modelling fluid flow and heat transfer phenomena.

Continuous determination of the volume of a space in a non steady state condition

1974 ◽  
Vol 36 (1) ◽  
pp. 59-66
Author(s):  
Oscar A. Gómez-Poviña ◽  
Carmen Sainz de Calatroni ◽  
Susana Orden de Puhl ◽  
Mariano J. Guerrero
Keyword(s):  
Steady State ◽  
State Condition ◽  
Steady State Condition ◽  
Continuous Determination
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