Scielo RSS <![CDATA[Journal of applied research and technology]]> http://www.scielo.org.mx/rss.php?pid=1665-642320120005&lang=pt vol. 10 num. 5 lang. pt <![CDATA[SciELO Logo]]> http://www.scielo.org.mx/img/en/fbpelogp.gif http://www.scielo.org.mx <![CDATA[<b>A Reactive Behavior Agent</b>: <b>Including Emotions into a Video Game</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1665-64232012000500001&lng=pt&nrm=iso&tlng=pt Why we have emotions and how they influence human behavior are two questions we constantly ask ourselves. According to researchers in the field, there are two kinds of information that the person receives to make a decision. This information is integrated to generate a whole. One comes from ourselves it is proprioceptive and refers to emotions; the other one is external, it comes from the environment. Thus, emotions are immersed in different areas of a person's life, including social, functional, and cognitive aspects. It has an important role in the decision-making process. It is on this last point that this paper focuses its approach, which consists of including a cognitive structure of emotions in a reactive behavior in order to enrich behavior, including the information generated through internal evaluation of the external physical stimuli. Our work is based on the OCC theory (named after the name of its authors: Ortony, Collins and Clore). This theory proposes that a decision-making process is affected through different perspectives: a) goals and events, b) agents and their actions, and c) objects and their capacity for attraction. The case study is situated within a scenario that represents an approach that seeks to include a module of emotions within the design of the architecture of a videogame.<hr/>Por qué tenemos emociones y cómo influyen en el comportamiento humano son dos preguntas que constantemente nos hacemos. De acuerdo con investigadores en el campo, se trata de dos tipos de información que la persona recibe para tomar una decisión. Esta información se integra para generar un todo. La información que viene de nosotros mismos es la propiocepción y se refiere a las emociones; la otra es externa y proviene del medio ambiente. Así, las emociones están inmersas en diferentes áreas de la vida de una persona, incluidos los aspectos sociales, funcionales y cognitivos. Tienen un papel importante en la toma de decisiones. Es en este último punto que el trabajo centra su enfoque, que consiste en incluir una estructura cognitiva de las emociones en un comportamiento reactivo a fin de enriquecer el comportamiento, incluyendo la información generada a través de la evaluación interna de los estímulos físicos externos. Nuestro trabajo se basa en la Teoría OCC (por el nombre de sus autores: Ortony, Collins y Clore). Esta teoría propone que la toma de decisiones se ve afectada a través de perspectivas diferentes: a) las metas y los acontecimientos, b) los agentes y sus acciones, y c) los objetos y su capacidad de atracción. El caso de estudio se encuentra dentro de un escenario que representa un enfoque que trata de incluir un módulo de las emociones en el diseño de la arquitectura de un videojuego. <![CDATA[<b>Alternative Diffuse Lighting and Specular Reflection Approach Using YIQ Color Space for 3D Scene Visualization Using Programmable</b> <b>HLSL Shaders</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1665-64232012000500002&lng=pt&nrm=iso&tlng=pt In this work an alternative approach for diffuse lighting and specular reflections is presented that uses YIQ color space instead of traditional RGB color space. The classical illumination algorithms that rely on RGB color space may lead to unrealistic results either due to the fact that they cannot make the original color brighter (inherent limitation imposed by using the RGB color space) or produce incorrect shades when viewed from certain angles because in the calculation of the specular reflection the original texture color is not taken into account. The approach proposed in this work gets around the problem by applying illumination in YIQ color space using its "luma" component (Y). In this novel approach the diffuse lighting is capable of increasing the perceived brightness of the source texture and the resulting color is always dependant on the surface's texture and produces reasonably realistic results when viewed from any possible angle. The algorithm and its HLSL shader code are described in this work along with the experiments that illustrate the problem and the solution. The performance benchmarks are also provided, showing that the proposed approach is a viable and realistic solution for applications running in real-time.<hr/>En este trabajo se presenta un nuevo enfoque para iluminación difusa y reflexiones especulares que utiliza el espacio de color YIQ en vez del tradicional RGB. Los algoritmos clásicos de iluminación que utilizan el espacio de colores RGB pueden generar resultados no realísticos ya sea porque no pueden hacer el color de la textura original más brilloso (limitante que se origina por utilizar el espacio de color RGB) o pueden producir un tinte incorrecto en ciertos ángulos porque el cálculo de la reflexión especular no toma en cuenta el color de la textura original. El enfoque propuesto evita los problemas anteriormente mencionados aplicando la iluminación en el espacio de colores YIQ utilizando el componente de "luma" (Y). Con este enfoque novedoso en la iluminación difusa se puede incrementar el brillo perceptual de un color, el cual siempre depende de la textura original. Por lo tanto, el resultado se ve razonablemente realístico desde cualquier ángulo. El algoritmo y su código fuente HLSL están descritos junto con los experimentos que muestran el problema y el resultado. Además, las pruebas de desempeño también están adjuntas mostrando que el enfoque propuesto es una solución viable y realística para aplicaciones corriendo en tiempo real. <![CDATA[<b>A Methodology to Simulate Induction Motor Dynamic Performance in the ABC Reference Frame Considering Mixed Eccentricity Effects</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1665-64232012000500003&lng=pt&nrm=iso&tlng=pt This paper presents a methodology to compute the inductances of the abc induction motor model considering mixed eccentricity. The winding function method (WFM) is employed to calculate the magnetizing inductances. Moreover, the air gap is approximated by an expression which can consider the case mentioned before as well as the healthy case (i.e., with uniform air gap). Due to the fact that the dynamic performance of the machine depends strongly on its inductances, some basic dimensions of a real machine are used and a comparison between different free acceleration characteristics is given such as currents, electromagnetic torque and speed.<hr/>En este trabajo se presenta una metodología para el cálculo de las inductancias del motor de inducción considerando su modelo en el marco de referencia abc y bajo condiciones de excentricidad mixta. Se emplea el método de función de devanado (MFD) para calcular las inductancias de magnetización de la máquina. Asimismo, la distribución del entrehierro se aproxima por medio de una expresión la cual puede considerar el caso antes mencionado además del caso sano (i.e., entrehierro uniforme). Debido a que la dinámica de la máquina depende fuertemente de sus inductancias, se muestra la comparación de resultados de un arranque en vacío mostrando variables como corrientes, par electromagnético y velocidad, empleando algunas dimensiones básicas de una máquina real. <![CDATA[<b>An Improved MRAS Based Sensorless Vector Control Method for Wind Power Generator</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1665-64232012000500004&lng=pt&nrm=iso&tlng=pt This paper describes an improved sensorless vector control strategy for a squirrel cage induction generator used in variable speed wind energy conversion systems (WECS). The main goal is to design a robust control algorithm immune to generator parameter variations. In order to estimate the rotational speed of the induction generator, a model reference adaptive system (MRAS observer) is used. It is shown that a generator parameter mismatch has a great influence on the rotor speed estimation. In order to estimate the speed accurately, the generator stator resistance must be identified at the same time to correct the mismatched resistance value used in the observer. The proposed rotor speed estimator with parallel stator resistance identification is first verified by computer simulation. Finally, the experiment is conducted in order to verify the obtained simulation results. It is proved that this control scheme can enhance the efficiency of a variable speed WECS. <![CDATA[<b>A Study on Physical Aging of Semicrystalline Polyethylene Terephthalate below the Glass Transition Point</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1665-64232012000500005&lng=pt&nrm=iso&tlng=pt Physical aging of semicrystalline polyethylene terephthalate was studied using differential scanning calorimetry (DSC). PET samples with crystallinity content of 0.28 were aged at two different temperatures, 25 and 45°C. The samples were stored for several days and periodically tested using DSC method. The glass transition temperature for the samples aged at 25°C was about 73-74°C, and the position and intensity of endothermic peaks were approximately constant. Higher glass transition of the samples aged at 45°C, 73-86°C, was attributed to the enthalpy relaxation process of amorphous regions of semicrystalline PET. For the samples aged at 45°C, the endothermic peaks shifted to higher temperatures with increasing aging time. The position of the endothermic peaks determined by the temperature of the maximum, Tmax, tended to increase with aging time for samples aged at 45°C, and the intensity of the peaks continuously increased with time; however, the results showed that the aging of PET samples at 45°C even after 120 days continued the enthalpic relaxation of semicrystalline PET and that the process could be studied by DSC method. The results also showed that the aging process could affect the final degree of crystallinity of c-PET samples and the samples stored at 45°C showed higher degree of crystallinity than the samples aged at 25°C. <![CDATA[<b>Optimal Threshold Computing in Automatic Image Thresholding using Adaptive Particle Swarm Optimization</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1665-64232012000500006&lng=pt&nrm=iso&tlng=pt Selecting an optimal threshold value is the most important step in image thresholding algorithms. For a bimodal histogram which can be modeled as a mixture of two Gaussian density functions, estimating these densities in practice is not simply feasible. The objective of this paper is to use adaptive particle swarm optimization (APSO) for the suboptimal estimation of the means and variances of these two Gaussian density functions; then, the computation of the optimal threshold value is straightforward. The comparisons of experimental results in a wide range of complex bimodal images show that this proposed thresholding algorithm presents higher correct detection rate of object and background in comparison to the other methods including Otsu's method and estimating the parameters of Gaussian density functions using genetic algorithm (GA). Meanwhile, the proposed thresholding method needs lower execution time than the PSO-based method, while it shows a little higher correct detection rate of object and background, with lower false acceptance rate and false rejection rate. <![CDATA[<b>An Optimal Transportation Schedule of Mobile Equipment</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1665-64232012000500007&lng=pt&nrm=iso&tlng=pt Motivated by a problem faced by road construction companies, we develop a new model to obtain an optimal transportation schedule of mobile machines which have to travel to execute tasks. In this problem, each task is characterized by the location where it is to be executed, a work-content in terms of machine-time units, and one or more time intervals within which it can be performed. The machines can be transported from one location to another at any time, thus the problem has an indefinite number of variables. However, this indefinite number of variables can be reduced to a definite one because, as we prove, the problem has an optimal solution in which the arrivals of machines occur only at certain time instants. The objective is to minimize the total transportation cost such that all the tasks are executed within their time intervals. The constraints ensuring that the tasks are processed within their prescribed time intervals are nonlinear; nevertheless, due to the sets of the possible arrival times of the machines forming bounded convex polyhedra, our problem can be transformed into a mixed integer linear program by the same device used in the decomposition principle of Dantzig-Wolfe.<hr/>Motivados por un problema que enfrentan las compañías de la construcción, desarrollamos un modelo nuevo para obtener un calendario óptimo del transporte de máquinas móviles que tienen que viajar para realizar tareas. En este problema, cada tarea está caracterizada por el lugar donde ésta tiene que ser realizada, una carga de trabajo en términos de tiempo-máquina, y uno o más intervalos de tiempo dentro de los cuales la tarea puede ser procesada. Las máquinas se pueden transportar desde un lugar hasta otro en cualquier momento, por lo tanto el problema tiene un número indefinido de variables. Sin embargo, este número indefinido de variables se puede reducir a uno definido porque, como se demuestra, el problema tiene una solución óptima en la que las llegadas de las máquinas ocurren solamente en ciertos momentos. El objetivo es minimizar el costo total de transporte tal que todas las tareas sean ejecutadas dentro de sus intervalos de tiempo. Las restricciones que aseguran que cada tarea sea procesada dentro de sus intervalos de tiempo prescritos son no lineales; sin embargo, debido a que los conjuntos de los posibles tiempos de llegada de las máquinas forman poliedros convexos acotados, nuestro problema puede transformarse en un programa lineal entero mixto por el mismo artificio usado en el principio de descomposición de Dantzig-Wolfe. <![CDATA[<b>Sensitivity Analysis of the Dynamic Behavior of a Salient-Pole Synchronous Machine Considering the Static Rotor Eccentricity Effect</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1665-64232012000500008&lng=pt&nrm=iso&tlng=pt This paper presents the sensitivity analysis of the behavior of a synchronous machine using the winding function theory considering the effect of static air-gap eccentricity. The winding function theory as a method to calculate the inductances of synchronous machines from the geometry and the actual arranging of the windings is presented. Then, detailed numerical simulations are carried out to examine the impact of eccentricity on the steady state regimes. The important role of static eccentricity and its links with various symmetrical and asymmetrical operating conditions are discussed as well as its influence on the machine parameters and performance are investigated. Experimental and analytical parameter results are presented for a 60 Hz, six-pole laboratory synchronous machine connected to an infinite bus under various static eccentricity conditions.<hr/>Este artículo presenta el análisis de sensibilidad del comportamiento de una máquina síncrona utilizando la teoría de función de devanado para considerar el efecto de excentricidad estática. Se presenta la teoría de función de devanado para el cálculo de las inductancias a partir de la geometría y del arreglo de los devanados. Se realizan simulaciones numéricas para analizar el impacto de la excentricidad en el estado estacionario. Se discute la importancia de la excentricidad y su relación con sus condiciones de operación simétrica y asimétrica así como la influencia sobre los parámetros y comportamiento de la máquina. Se presentan resultados experimentales y analíticos de una máquina de laboratorio de seis polos, 60Hz , conectada a un bus infinito bajo diferentes condiciones de excentricidad estática. <![CDATA[<b>Design, Simulation and Implementation of an Active Sound-Noise Cancellation System for Use in a Cockpit Intercommunication System</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1665-64232012000500009&lng=pt&nrm=iso&tlng=pt In this paper, an active noise control system for denoising the intercommunication signal of an airplane cockpit is proposed. Noise sources such as engines degrade the quality of the intercommunication signal, especially in the case of the pilot and copilot headsets. A two-microphone active adaptive noise controller is designed by using an adaptive FIR filter in an active structure. The designed system is simulated and also implemented in real environment using real speech signals, periodic noise and AWGN noise. Also, an FPGA-based hardware implementation utilizing a novel method is provided. The whole design is considered an FPGA hardware core with low resource utilizations which is suitable for HW/SW codesign and System-on-Programmable-Chip (SoPC) applications. The codes have been written by using the VHDL93 hardware description language, the XilKernel embedded operating system and a finite state machine. The obtained results showed competent functionality and performance of the proposed system. This ICS noise removal architecture can be used on any cargo, civil or fighter platform (such as C-130, IR-AN 140 and F5-F) and also in radar and electronic warfare (EW) systems (for clutter/interference compensation) with minimum hardware or software changes. <![CDATA[<b>Unified Processing Structure for Communication and Navigation signals in modems for lightweight satellite stations</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1665-64232012000500010&lng=pt&nrm=iso&tlng=pt The present article shows the design and test of a unified-processing device for detection and demodulation of narrow and broadband communication signals, as well as navigation signals from GLONASS and GPS systems. The specific processing for each type of signal is described within the general framework of the proposed device. Performance indicators, such as symbol error probability (SEP) and energy losses, were computed using simulations of the device and the corresponding results are presented for discussion.<hr/>En este artículo se muestran los resultados concernientes al diseño de un dispositivo de procesamiento unificado que permite detectar y demodular tanto señales de comunicación de banda angosta y banda ancha, como señales de navegación de los sistemas GLONASS y GPS. Se esclarece la especificidad de procesamiento para cada tipo de señal enmarcado en la estructura general del dispositivo. Los valores de probabilidad de error de símbolo y las pérdidas energéticas del sistema, obtenidos en un simulador del dispositivo, son presentados. <![CDATA[<b>Fingerprint Recognition Using Local Features and Hu Moments</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1665-64232012000500011&lng=pt&nrm=iso&tlng=pt Person identification systems based on fingerprint patterns called Automatic Fingerprint Identification Systems, AFIS, are some of the most widely used biometric methods since they provide a high degree of success. The accuracy of AFIS is mainly due to some unique characteristics called minutiae, which are points where a curve track finishes, intersects with another curve track, or branches off. During past decades several efficient minutia-based fingerprint recognition algorithms have been proposed which achieve false recognition rates close to 1%, however, their recognition rate may be still improved. To this end, this paper presents a fingerprint recognition method using a combination of the Fast Fourier Transform (FFT) with Gabor filters for image enhancement. Next, fingerprint recognition is carried out using a novel recognition stage based on Local Features and Hu invariant moments for verification.<hr/>Los sistemas de identificación de personas basados en huellas dactilares AFIS (Automatic Fingerprint Identification System), son uno de los sistemas más utilizados ya que proporcionan un alto grado de exactitud. La exactitud de un AFIS es debido principalmente a sus características únicas, llamadas minucias, las cuales son puntos donde los bordes terminan o se dividen. En los últimos años, varios algoritmos de reconocimiento de huella dactilar han sido propuestos los cuales alcanzan porcentajes de falso reconocimiento de alrededor del 1%. Sin embargo, este porcentaje puede ser mejorado. Para esto, este artículo presenta un método de reconocimiento de huella dactilar usando una combinación de Transformada Rápida de Fourier (FFT) y filtros de Gabor para un mejoramiento de la imagen. Después, el reconocimiento es realizado usando una novedosa etapa basada en características locales y momentos invariantes Hu para verificación. <![CDATA[<b>Studies of the Precessing Vortex Core in Swirling Flows</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1665-64232012000500012&lng=pt&nrm=iso&tlng=pt Large scale coherent structures play an important role in the behavior of the combustion regime inside any type of combustor stabilized by swirl, with special impact on factors such as flame stability, blow off, emissions and the occurrence of thermo-acoustic oscillations. Lean premixed combustion is widely used and is known to impact many of these factors, causing complex interrelationships with any coherent structure formed. Despite the extensive experimentation in this matter, the above phenomena are poorly understood. Numerical simulations have been used to try to explain the development of different regimes, but their extremely complex nature and lack of time dependent validation show varied and debatable results. The precessing vortex core (PVC) is a well-known coherent structure whose development, intensity and occurrence has not been well documented. This paper thus adopts an experimental approach to characterize the PVC in a simple swirl burner under combustion conditions so as to reveal the effects of swirl and other variables on the latter. Aided by a high speed photography (HSP) system, the recognition and extent of several different types of PVCs were observed and discussed.<hr/>Las estructuras coherentes de larga escala juegan un importante papel en el comportamiento de la combustión dentro de cualquier quemador estabilizado por arremolinamiento, impactando especialmente en factores como la estabilidad y extinción de la flama, emisiones y la aparición de oscilaciones termo-acústicas. La combustión en estado pobre es ampliamente utilizada y es sabido que impacta también en estos factores, causando una compleja interrelación con las estructuras que se forman. A pesar del extensivo trabajo experimental en el campo, el fenómeno antes mencionado no es completamente entendido. Se han utilizado simulaciones numéricas para explicar el desarrollo de diferentes regímenes, pero su extremamente compleja naturaleza y la falta de validación temporal han llevado a grandes debates en el campo. El centro de vórtice precesor (CVP) es una estructura coherente bien conocida cuyo desarrollo, intensidad y ocurrencia no se han documentado completamente. Por ello, este artículo adopta una aproximación experimental para caracterizar al CVP en un quemador sencillo bajo condiciones de combustión que revelen el efecto de arremolinamiento así como otras variables. Se llevó a cabo el reconocimiento de muchos diferentes tipos de CVP con la ayuda de un sistema de fotografía de alta velocidad. <![CDATA[<b>Concurrent Dynamic Visualizations With Expressive Petri Net Representations to Enrich the Understanding of Biological and Pathological Processes</b>: <b>an Application to Signaling Pathways</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1665-64232012000500013&lng=pt&nrm=iso&tlng=pt Dynamic visualizations and expressive representations are needed in systems biology to handle multiple interactions occurring during the biological processes of biopathway representations. Dynamic visualizations allow users an ease of interaction with pathway models. At the same time, representations of biopathways should express how interactions take place. In spite of the fact that diverse databases provide users with pathways, their information and representation are frequently different from each other and show restricted interactions because of their static visualization. An adopted solution is to merge diverse representations to obtain a richer one. However, due to different formats and the multiple links involved in the pathway representations, the merge results frequently in erroneous models and in a tangle web of relations very hard to be manipulated. Instead, this work introduces a concurrent dynamic visualization (CDV) of the same pathway, which is retrieved from different sites and then transformed into Petri net representations to facilitate the understanding of their biological processes by interacting with them. We applied this approach to the analysis of the Notch signaling pathway, associated with cervical cancer; we obtained it from different sources which we compared and manipulated simultaneously by interacting with the provided CDV until the user generated a personalized pathway.<hr/>En biología de sistemas la visualización dinámica y las representaciones expresivas son necesarias para representar interacciones múltiples que ocurren durante los procesos biológicos en bioredes. La visualización dinámica facilita a los usuarios interactuar con modelos de bioredes, mientras que las representaciones deben expresar como se llevan a cabo las interacciones dentro de éstas. A pesar de que diversas bases de datos proveen de redes a los usuarios, generalmente la información y representación contenidas en cada una son diferentes, y la interacción usuario-biored es restringida debido a la visualización estática. Una solución que se ha adoptado es hacer converger varias representaciones para obtener una más completa. Sin embargo, debido al uso de diferentes formatos incompatibles entre ellos y a las múltiples conexiones involucradas en las redes, la integración frecuentemente resulta en modelos erróneos y en una maraña de conexiones representadas en la red que son muy difíciles de analizar y manipular. En este trabajo introducimos la visualización dinámica concurrente (VDC) de una misma vía, la cual es recuperada de diferentes bases de datos y transformada a representaciones en redes de Petri para facilitar el entendimiento de los procesos biológicos y modificar las vías obtenidas interactuando con ellas. Hemos aplicado esta estrategia al análisis de la vía de señalización de Notch, asociada a cáncer cérvicouterino, obteniéndola de tres diferentes fuentes, comparándolas y manipulándolas simultáneamente interactuando con la VDC provista, hasta la generación de una vía personalizada. <![CDATA[<b>Pseudorandom Sequences in Spread-Spectrum Communications Generated by Cellular Automata</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1665-64232012000500014&lng=pt&nrm=iso&tlng=pt Dynamical systems methods have been recently used in spread-spectrum digital communication systems. The expansion of the spectrum using a pseudorandom sequence with a higher frequency than the information signal is the key feature for its robustness against the signal traveling interference through the channel. In this work, we propose to generate pseudorandom sequences by employing cellular automata and we check these sequences have the necessary properties which are required in modern communication systems. The computed sequences obtained by the cellular automata are tested in a quadrature phase shift keying (QPSK) spread-spectrum communication system. The efficiency of the system is analyzed by computing the bit error rate under different signal to noise ratio conditions. These results are compared with systems that employ Golden code and other typical pseudorandom sequences.<hr/>Métodos de sistemas dinámicos se han estado utilizando recientemente en sistemas digitales de comunicación de espectro expandido. La expansión del espectro mediante el uso de una secuencia pseudo-aleatoria de frecuencia mayor que la frecuencia de la señal de información es la clave que lo caracteriza para su robustez en contra de la interferencia de la señal en el canal. En este trabajo se propone generar secuencias pseudo-aleatorias mediante el uso de autómatas celulares y verificar que esta secuencias tengan las propiedades necesarias que se requieren para sistemas de comunicación modernos. Las secuencias generadas con autómatas celulares son probadas en un sistema de espectro expandido que utiliza modulación por cuadratura de fase QPSK. La eficiencia del sistema es analizada mediante el cálculo de la taza de error de bit bajo diferentes condiciones de la razón señal a ruido. Estos resultados son comparados con sistemas que emplean otras secuencias pseudo-aleatorias y secuencias Golden code. <![CDATA[<b>Eigenvalue Analysis of a Network Connected to a Wind Turbine Implemented with a Doubly-Fed Induction Generator (DFIG)</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1665-64232012000500015&lng=pt&nrm=iso&tlng=pt Recently, the growing integration of wind energy into power networks has had a significant impact on power system stability. Amongst types of large capacity wind turbines (WTs), doubly-fed induction generator (DFIG) wind turbines represent an important percentage. This paper attemps to study the impact of DFIG wind turbines on the power system stability and dynamics by modeling all components of a case study system (CSS). Modal analysis is used for the study of the dynamic stability of the CSS. The system dynamics are studied by examining the eigenvalues of the matrix system of the case study and the impact of all parameters of the CSS are studied in normal, subsynchronous and super-synchronous modes. The results of the eigenvalue analysis are verified by using dynamic simulation software. The results show that each of the electrical and mechanical parameters of the CSS affect specific eigenvalues.