Wyniki wyszukiwania - BazTech

1

Comparison of transformer modeling on riser pole arresters behavior during switching transients

Abbaszadeh A., Abedi M., Doustmohammadi A.

Archives of Electrical Engineering

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2017

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Vol. 66, nr 4

717--730

EN

Arresters are widely used in power systems to protect other equipment against overvoltages. However, in some conditions, they can’t operate successfully. One of the disturbances leading to the failure of the riser pole arresters is the ferroresonance overvoltages. In this paper, at first the influence of different transformer simulation models of ATP software on the occurrence of ferroresonance is studied and then the effect of ferroresonance on the riser pole arrester has been scrutinized through the thermal and electrical performance of the arrester in an underground distribution system. The results show that the arrester temperature rises due to energy dissipation in a ferroresonance circumstance, which indeed may result into the explosion of the arrester. Also, applying different models of the transformer in the ATP software and comparing the results, it is shown that the available models do not show the same effect on the arrester.

2

A neuromechanical modeling of spinal cord injury locomotor system for simulating the rehabilitation effects

Abedi M., Moghaddam M. M., Firoozabadi M.

Biocybernetics and Biomedical Engineering

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2016

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Vol. 36, no. 1

193--204

EN

Gait recovering after spinal cord injury (SCI) is a regular attempt in neurorehabilitation. For this purpose, various clinical techniques have been proposed until now. However, the feasibility of these techniques has not been theoretically investigated so much. This has been mainly for difficulties of gait modeling in SCI patients. Involving these problems, recently neuromechanical models of gait locomotion have been proposed for examining rehabilitation methods. However, these models were so simple that could not properly express rehabilitation effects. Notably, lesion intensity is a concern that was never attended in prior simulations. Due to this limitation, in this paper a new neuromechanical model is proposed that classifies patients based on intensity of trauma. Explicitly, the complete, severe and non-severe incomplete SCIs are imitated and effects of related clinical rehabi-litations are explored. Remarkably, the model indicates an incredible performance in explaining the rehabilitation effects through presenting the compliant results with clinical information. The suitability of this model is mainly for the applied neuromuscular plan that consists of a combined plan of central pattern generator (CPG) and neural reflexes that controls a double segment limb. The validity of this model is further proved by comparing the kinematic and kinetic results to the experimental data.

3

Exact and Numerical Elastic Analysis for the FGM Thick-Walled Cylindrical Pressure Vessels with Exponentially-Varying Properties

Nejad M. Z., Abedi M., Lotfian M. H., Ghannad M.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 3

1649--1654

EN

Assuming exponential-varying properties in the radial direction and based on the elasticity theory, an exact closed-form analytical solution is obtained to elastic analysis of FGM thick-walled cylindrical pressure vessels in the plane strain condition. Following this, radial distribution of radial displacement, radial stress, and circumferential stress are plotted for different values of material inhomogeneity constant. The displacements and stresses distributions are compared with the solutions of the finite element method (FEM).

4

Non-linear Analytical Extended Poincare's Model of Phase Saturated Self Excited Series Connected Synchronous Generators

Shariatmadar S. M., Nazarzadeh J., Abedi M.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 3b

126-134

PL

Wprowadzono model prądu magnesującego maszyny elektrycznej w rejonie nasycenia do analizy stanu nasycenia samowzbudnych generatorów synchronicznych. Wykorzystano model Poincare. Zamodelowano nieliniowość maszyny i obliczono warunki stabilności. Rezultaty symulacji pokazują że zaproponowany model może być wykorzystany do analizy różnych maszyn elektrycznych AC.

EN

In the present paper, first a magnetization current base model is introduced for the electrical machine analyzing that saturation is occurred for the phase that its current entered to saturation region. Other part of machine may be saturated or in the linear condition in order of their currents. Then a new analytical extended Poincare's map is introduced for modelling of self excited series connected synchronous generators in saturated conditions. Using the non-linear control theory, an analytical first order Poincare's map of the machines is computed. Then extended Poincare's map of the machine is introduced. After that characteristic multipliers of the self excited series connected synchronous generator are determined. Nonlinearity of the machine can be modelled with the new map and stability analysis of the system is investigated. The new map is capable for modelling, control, bifurcation and chaos analysis in the non-linear (saturation) conditions. Finally the simulation results of the new extended Poincare's map with experimental laboratory set-up results are compared. The results show that the new Poincare's map is an effective method for modelling and analysis of any ac electrical machines.

5

Application of various methods for 2D inverse modeling of residual gravity anomalies

Abedi M., Afshar A., Ardestani V.E., Narouzi G., Lucas C.

Acta Geophysica

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2010

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Vol. 58, no. 2

317-336

EN

This paper presents a neural network approach to determine 2D inverse modeling of a buried structure from gravity anomaly profile. The results of the applied neural network method are compared with the results of two other methods, least-squares minimization and the simple method. Sphere, horizontal cylinder and vertical cylinder and their gravity effects are considered as the synthetic models and the synthetic data, respectively. The synthetic data are also corrupted with noise to evaluate the capability of the methods. Then the Dehloran bitumen map in Iran is chosen as a real data application. Anomaly value of the cross-section, which is taken from the gravity anomaly map of Dehloran bitumen, is very close to those obtained from these methods.