A. Krishnan

K. S. Rangasamy College of Technology, Periyār, Tamil Nādu, India

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Publications (47)3.66 Total impact

  • M.Srinivasan, A.Krishnan
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    ABSTRACT: The Hot Spot Temperature (HST) value depends on the ambient temperature, the rise in the top oil temperature (TOT) over the ambient temperature, and the rise in the winding HST over the top oil temperature. In this paper a new semi-physical model comprising of the environmental variables for the estimation of HST in transformer is proposed and also MATLAB/Simulink-based valid model of hot spot temperature under variable environmental condition is proposed. The winding hot-spot temperature can be calculated as a function of the top-oil temperature that can be estimated using the transformer loading data, top oil temperature lagged regressor value, ambient temperature, wind velocity and solar heat radiation effect. The estimated HST is compared with measured data of a power transformer in operation. The proposed model has been validated using real data gathered from a 100 MVA power transformer
    IEEE Transactions on Power Systems 01/2013; 8(1):35-44. · 2.92 Impact Factor
  • M.Srinivasan, A.Krishnan
    [Show abstract] [Hide abstract]
    ABSTRACT: The Hot Spot Temperature (HST) value depends on the ambient temperature, the rise in the top oil temperature (TOT) over the ambient temperature, and the rise in the winding HST over the top oil temperature. In this paper a new semi-physical model comprising of the environmental variables for the estimation of HST and loss of insulation life in transformer is proposed. The winding hot-spot temperature can be calculated as a function of the top-oil temperature that can be estimated using the transformer loading data, top oil temperature lagged regressor value, ambient temperature, wind velocity and solar heat radiation effect. The estimated HST is compared with measured data of a power transformer in operation. The proposed model has been validated using real data gathered from a 100 MVA power transformer
    International Journal of Computer Applications. 10/2012; 55(5):43-48.
  • M.Srinivasan, A.krishnan
    [Show abstract] [Hide abstract]
    ABSTRACT: The Hot Spot Temperature (HST) value depends on the ambient temperature, the rise in the Top Oil Temperature (TOT) over the ambient temperature, and the rise in the winding HST over the top oil temperature. In this paper a new semi-physical model comprising of the environmental variables for the estimation of HST in transformer is proposed and also MATLAB/Simulink-based valid model of hot spot temperature under variable environmental condition is proposed. The winding hot-spot temperature can be calculated as a function of the top-oil temperature that can be estimated using the transformer loading data, top oil temperature lagged regressor value, ambient temperature, wind velocity and solar heat radiation effect. The estimated HST is compared with measured data of a power transformer in operation
    Journal of Global Research in Computer Science. 06/2012; 3(6):59-63.
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    Thangaprakash Sengodan, Ammasai Krishnan
    International Journal of Automation and Computing 04/2012; 9(2-1):200-210.
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    M Srinivasan, A Krishnan
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    ABSTRACT: The hot spot temperature (HST) plays a most important role in the insulation life of the transformer. Ambient temperature and environmental variable factors involved in the top oil temperature (TOT) computations in all transformer thermal models affects insu-lation lifetime either directly or indirectly. The importance of the ambient temperature in transformer's insulation life, a new semi-physically-based model for the estimation of TOT in transformers has been proposed in this paper. The winding hot-spot tem-perature can be calculated as function of the TOT that can be estimated by using the ambient temperature, wind velocity and solar heat radiation effect and transformer loading measured data. The estimated TOT is compared with measured data of a dis-tribution transformer in operation. The proposed model has been validated using real data gathered from a 100 MVA power transformer. For a semi-physically-based model to be acceptable, it must have the qualities of: adequacy, accuracy and consistency. We assess model adequacy using the scale: prediction R 2 , and plot of residuals against fitted values. To assess model consistency, we use: variance inflation factor (VIF) (which mea-sure multicollinearity), condition number. To assess model accuracy we use mean square error, maximum and minimum error values of semi-physically-based model parameters to the existing model parameters.
    International Journal of Reliability Quality and Safety Engineering 01/2012; 20(19).
  • M. Arun, A Krishnan
    Journal of Computer Science, USA. 01/2011; 7(4):471-474.
  • M. Arun, A. Krishnan
    International Journal of Inovative Computing, Information and Control, Kyushu Tokia University, Japan. 01/2011;
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    Ponnusamy Kumar, A. Krishnan
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    ABSTRACT: This paper presents a performance study of the distributed coordination function (DCF) of 802.11 networks considering erroneous channel and capture effects under non-saturated traffic conditions employing a basic access method. The aggregate throughput of a practical wireless local area network (WLAN) strongly depends on the channel conditions. In a real radio environment, the received signal power at the access point from a station is subjected to deterministic path loss, shadowing, and fast multipath fading. The binary exponential backoff (BEB) mechanism of IEEE 802.11 DCF severely suffers from more channel idle time under high bit error rate (BER). To alleviate the low performance of IEEE 802.11 DCF, a new mechanism is introduced, which greatly outperforms the existing methods under a high BER. A multidimensional Markov chain model is used to characterize the behavior of DCF in order to account both non-ideal channel conditions and capture effects. KeywordsIEEE 802.11–distributed coordination function (DCF)–binary exponential backoff (BEB)–erroneous channel–capture–fading–bit error rate (BER)–non-saturation throughput
    International Journal of Automation and Computing 01/2011; 8(2):236-243.
  • M. Arun, A Krishnan
    Australian Journal of Electrical & Electronics Engineering, Australia. 01/2011; 8(3):1-10.
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    M. Arun, A Krishnan
    International Journal of Automation and Computing 01/2011;
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    ABSTRACT: This paper describes a fully automated method of measuring the cold and hot resistance of a transformer. The measuring scheme was developed by using a code composer studio (CCS) environment, TMS320F2812 digital signal processor and external interface hardware. The CCS allows a high degree of software modularity and provides the features that are required for sensor zero adjustment, data acquisition through ADC and analysis, and automated presentation of results. Furthermore, the experimental setup described in this paper could be used to obtain the cold and hot resistance of other electromechanical devices. The real-time implementation of cold and hot resistance measured setup and the results from a test on transformer are presented in the paper.
    Int. J. Instrumentation Technology. 01/2011; 1.
  • E. Jayabalan, A. Krishnan
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    ABSTRACT: Image Registration is the basic step used for the target tracking in aerial videos. Image Registration is a process, which finds the location where optimal matching is obtained by matching a template image called the reference image over the searching region of an input image using a suitable similarity measures. The method although computationally intensive, is simple, straightforward and robust and requires no apriori information about the two images. A number of image registration algorithms are studied on images with varying size of search space and reference image. All these algorithms are based on similarity measure between the reference image and search space. The key issues in image registration are the time required for registration and the accuracy of registration viz., measure of how close is the match between sub image in the search space and the reference image.
    01/2011;
  • E. Jayabalan, A. Krishnan
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    ABSTRACT: In real time situations, non rigid object tracking is a challenging and important problem. Due to the non rigid nature of objects in most of the tracking applications, deformable models are appealing in tracking tasks because of their capability and flexibility. The proposed approach uses an observation model based on optical flow information used to know the displacement of the objects present in the scene. After finding the moving regions in the initial frame, we are applying active contour model (ACM) to track the moving objects in the further frames dynamically. These models have been used as a natural means of incorporating flow information into the tracking. The formulation of the Active Contour Model by incorporating an additional force driven optical flow field improves the tracking speed. This algorithm efficiently works to track for low contrast videos like Aerial videos.
    01/2011;
  • M. Arun, A Krishnan
    International Journal of Computers and Applications, ACTA press, Canada. 01/2011; 33(4).
  • E. Jayabalan, A. Krishnan
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    ABSTRACT: Today surveillance cameras are used in many places like hospitals, museums, ATM centres etc for security purpose. Since videos captured by such cameras are time consuming, most of them are never watched. Inorder to conserve time, an abstract of the video is generated using the Rack-through Method. In the abstract video, most of the activity of the long video is condensed by simultaneously showing several actions, even when they originally occurred at different times. The abstract video also gives an index into the original video by pointing to the original time of each activity. KeywordsImage Processing–Background Subtraction–Object Detection–Rack-through Method
    12/2010: pages 472-474;
  • E. Jayabalan, A. Krishnan
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    ABSTRACT: A technique is proposed to drastically reduce the update cost. Specifically, we propose to model the current position of a moving object as the distance from its starting position, along a given route. The distance continuously increases as a function of time, without being updated. In the context of position attributes that change continuously with time, the main issues that are addressed are position-update policies and imprecision. To accomplish tracking with certain accuracy, each wireless device monitors its real position (its TRAVEL DATABASE position) and compares this with a local copy of the position that the central database assumes. When needed in order to maintain the required accuracy in the database, the wireless device issues an update to the server. KeywordsTracking–Video–Database–Wireless–Travel-Database–Update–Moving Object
    12/2010: pages 302-304;
  • E. Jayabalan, A. Krishnan
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    ABSTRACT: Object tracking in video sequences is a very important topic and has various applications in video compression, surveillance, robot technology, etc. In many applications, the focus is on tracking moving object. Object tracking is the problem of generating an inference about the motion of an object from the sequence of frames in a video. In this paper, we propose a method for tracking moving objects in video sequences. KeywordsObject–Tracking–Video–frames–Compression
    12/2010: pages 39-43;
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    ABSTRACT: This paper presents a mathematical model that analyzes the throughput of the IEEE 802.11b distributed coordination function (DCF) with the collision aware rate adaptation (CARA) algorithm. IEEE 802.11 WLANs provide multiple transmission rates to improve system throughput by adapting the transmission rate to the current channel conditions. The system throughput is determined by some stations using low transmission rates due to bad channel conditions. CARA algorithm does not disturb the existing IEEE 802.11b formats and it can be easily incorporated into the commercial wireless local area networks (WLAN) devices. Finally, we verify our findings with simulation. KeywordsDistributed coordination function (DCF)-IEEE 802.11-collision aware rate adaptation (CARA)-multirate-medium access control (MAC)
    International Journal of Automation and Computing 11/2010; 7(4):571-577.
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    P Babu, A Krishnan
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    ABSTRACT: Several approaches have been introduced in literature for active noise control (ANC) systems. Since FxLMS algorithm appears to be the best choice as a controller filter, researchers tend to improve performance of ANC systems by enhancing and modifying this algorithm. In this paper, the existing FxLMS algorithm is modified which provides a new structure for improving the noise reduction and convergence rate. Here the proposed method uses two variable step sizes, one for control filter and another for modelling filter. The control filter step size is varied based on the secondary path threshold signal λ . The modelling filter step size is varied based on error signal) (n f . It is shown that in the proposed method ANC system noise reduction rate and convergence rate are improved dynamically than the FxLMS variable step size methods. The computer simulations results indicate effectiveness of the proposed method. KEYWORDS Active noise control, FxLMS algorithm, Wavelet transform, Soft threshold, Variable Step Size (VSS).
    International journal of computer science & information Technology. 09/2010; 2.
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    Babu P, Krishnan A
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    ABSTRACT: Several approaches have been introduced in literature for active noise control (ANC) systems. Since FxLMS algorithm appears to be the best choice as a controller filter, researchers tend to improve performance of ANC systems by enhancing and modifying this algorithm. In this paper, modification is done in the existing FxLMS algorithm that provides a new structure for improving the tracking performance and convergence rate. The secondary signal y(n) is dynamic thresholded by Wavelet transform to improve tracking. The convergence rate is improved by dynamically varying the step size of the error signal.
    International Journal of Computer Science and Information Security. 01/2010;