ETD at Indian Institute of Science
(528 recursos)
Repository of Theses and Dissertations of Indian Institute of Science, Bangalore, India. The repository has been developed to capture, disseminate and preserve research theses of Indian Institute of Science.
Mostrando recursos 1 - 20 de 27
1.
A Novel Approach for Tuning of Power System Stabilizer Using Genetic Algorithm - Singh, Ravindra
The problem of dynamic stability of power system has challenged power system engineers since over three decades now. In a generator, the electromechanical coupling between the rotor and the rest of the system causes it to behave in a manner similar to a spring mass damper system, which exhibits an oscillatory behaviour around the equilibrium state, following any disturbance, such as sudden change in loads, change in transmission line parameters, fluctuations in the output of turbine and faults etc. The use of fast acting high gain AVRs and evolution of large interconnected power systems with transfer of bulk power across...
2.
Compressed Domain Processing of MPEG Audio - Anantharaman, B
MPEG audio compression techniques significantly reduces the storage and transmission requirements for high quality digital audio. However, compression complicates the processing of audio in many applications. If a compressed audio signal is to be processed, a direct method would be to decode the compressed signal, process the decoded signal and re-encode it. This is computationally expensive due to the complexity of the MPEG filter bank. This thesis deals with processing of MPEG compressed audio. The main contributions of this thesis are
a) Extracting wavelet coefficients in the MPEG compressed domain.
b) Wavelet based pitch extraction in MPEG compressed domain.
c) Time Scale...
3.
Prediction based load balancing heuristic for a heterogeneous cluster - Saranyan, N
Load balancing has been a topic of interest in both academia and industry, mainly
because of the scope for performance enhancement that is available to be exploited in
many parallel and distributed processing environments. Among the many approaches
that have been used to solve the load balancing problem, we find that only very few
use prediction of code execution times. Our reasoning for this is that the field of code prediction
is in its infancy. As of this writing, we are not aware of any prediction-based
load balancing approach that uses prediction8 of code-execution times, and uses neither
the information provided by the user, nor an off-line...
4.
Algorithms for processing polarization-rich optical imaging data - R S, Umesh
This work mainly focuses on signal processing issues related to continuous-wave, polarization-based direct imaging schemes. Here, we present a mathematical framework to analyze the performance of the Polarization Difference Imaging (PDI) and Polarization Modulation Imaging (PMI). We have considered three visualization parameters, namely, the polarization intensity (PI), Degree of Linear Polarization (DOLP) and polarization orientation (PO) for comparing these schemes. The first two parameters appear frequently in literature, possibly under different names. The last parameter, polarization orientation, has been introduced and elaborated in this thesis. We have also proposed some extensions/alternatives for the existing imaging and processing schemes and analyzed...
5.
Synchronised Pulsewidth Modulation Strategies Based On Space Vector Approach For Induction Motor Drives - Narayanan, G
In high power induction motor drives, the switching frequency of the inverter is quite low due to the high losses in the power devices. Real-time PWM strategies, which result in reduced harmonic distortion under low switching frequencies and have maximum possible DC bus utilisation, are developed for such drives in the present work.
The space vector approach is taken up for the generation of synchronised PWM waveforms with 3-Phase Symmetry, Half Wave Symmetry and Quarter Wave Symmetry, required for high-power drives. Rules for synchronisation and the waveform symmetries are brought out. These rules are applied to the conventional and modified...
6.
Adaptive Control Of A General Class Of Finite Dimensional Stable LTI Systems - Shankar, H N
We consider the problem of Adaptive Control of finite-dimensional, stable, Linear Time Invariant (LTI) plants. Amongst such plants, the subclass regarding which an upper bound on the order is not known or which are known to be nonminimum phase (zeros in the unstable region) pose formidable problems in their own right. On one hand, if an upper bound on the order of the plant is not known, adaptive control usually involves some form of order estimation. On the other hand, when the plant is allowed to be either minimum phase or nonminimum phase, the adaptive control problem, as is well-known,...
7.
Study On Overmodulation Methods For PWM Inverter Fed AC Drives - Venugopal, S
A voltage source inverter is commonly used to supply a variable frequency variable voltage to a three phase induction motor in a variable speed application. A suitable pulse width modulation (PWM) technique is employed to obtain the required output voltage in the line side of the inverter. Real-time methods for PWM generation can be broadly classified into triangle comparison based PWM (TCPWM) and space vector based PWM (SVPWM).
In TCPWM methods such as sine-triangle PWM, three phase reference modulating signals are compared against a common triangular carrier to generate the PWM signals for the three phases.
In SVPWM methods, a revolving reference...
8.
Resonant Transition Topologies For Push-Pull And Half-Bridge DC-DC Converters - Swaminathan, B
Switched mode power supplies (SMPS) are being extensively used in most power conversion processes. The analysis, design and modeling processes of hard-switched converters are mature, where the switching frequency was limited to a few 10's of kHz. The present direction of evolution m SMPS is towards higher efficiency and higher power density. These twin objectives demand high switching frequency and low overall losses. Soft switching results in practically zero switching losses and extends the switching frequency to 100's of kHz and beyond.
This thesis presents novel variants of push-pull and half-bridge DC-DC converters with soft switching properties. The proposed topology uses...
9.
Bounds For Scheduling In Non-Identical Uniform Multiprocessor Systems - Darera, Vivek N
With multiprocessors and multicore processors becoming ubiquitous, focus has shifted from research on uniprocessors to that on multiprocessors. Results derived for the uniprocessor case unfortunately do not always directly extend to the multiprocessor case in a straightforward manner. This necessitates a paradigm shift in the approach used to design and analyse the behaviour of such processors. In the case of Real-time systems, that is, systems
characterised by explicit timing constraints, analysis and performance guarantees are more important, as failure is unacceptable. Scheduling algorithms used in Real-time systems have to be carefully designed as the performance of the system depends critically on...
10.
Analysis Of Multi-lingual Documents With Complex Layout And Content - Pati, Peeta Basa
A document image, beside text, may contain pictures, graphs, signatures, logos, barcodes, hand-drawn sketches and/or seals. Further, the text blocks in an image may be in Manhattan or any complex layout. Document Layout Analysis is an important preprocessing step before subjecting any such image to OCR. Here, the image with complex layout and content is segmented into its constituent components. For many present day applications, separating the text from the non-text blocks is sufficient. This enables the conversion of the text elements present in the image to their corresponding editable form.
In this work, an effort has been made to separate...
11.
A Study Of Utility Of Smile Profile For Face Recognition - Bhat, Srikrishna K K
Face recognition is one of the most natural activities performed by the human beings. It has wide range of applications in the areas of Human Computer Interaction, Surveillance, Security etc. Face information of people can be obtained in a non-intrusive manner, without violating privacy. But, robust face recognition which is invariant under varying pose, illumination etc is still a challenging problem. The main aim of this thesis is to explore the usefulness of smile pro?le of human beings as an extra aid in recognizing people by faces.
Smile pro?le of a person is the sequence of images captured by a camera...
12.
A Study On High Voltage AC Power Transmission Line Electric And Magnetic Field Coupling With Nearby Metallic Pipelines - Gupta, Abhishek
In the recent years, there has been a trend to run metallic pipelines carrying petroleum products and high voltage AC power lines parallel to each other in a relatively narrow strip of land. The case of electromagnetic interference between high voltage transmission lines and metallic pipelines has been a topic of major concern since the early 60s. The main reasons for that are:
The ever increasing cost of right-of-ways, suitable for power lines and pipelines, along with recent environmental regulations, aiming to protect nature and wildlife, has forced various utilities to share common corridors for both high voltage power lines...
13.
Application Of ANN Techniques For Identification Of Fault Location In Distribution Networks - Ashageetha, H
Electric power distribution network is an important part of electrical power systems for delivering electricity to consumers. Electric power utilities worldwide are increasingly adopting the computer aided monitoring, control and management of electric power distribution systems to provide better services to the electrical consumers. Therefore, research and development activities worldwide are being carried out to automate the electric power distribution system.
The power distribution system consists of a three-phase source supplying power through single-, two-, or three-phase distribution lines, switches, and transformers to a set of buses with a given load demand. In addition, unlike transmission systems, single-, two-, and...
14.
Discovering Frequent Episodes : Fast Algorithms, Connections With HMMs And Generalizations - Laxman, Srivatsan
Temporal data mining is concerned with the exploration of large sequential (or temporally ordered) data sets to discover some nontrivial information that was previously unknown to the data owner. Sequential data sets come up naturally in a wide range of application domains, ranging from bioinformatics to manufacturing processes. Pattern discovery refers to a broad class of data mining techniques in which the objective is to unearth hidden patterns or unexpected trends in the data. In general, pattern discovery is about finding all patterns of 'interest' in the data and one popular measure of interestingness for a pattern is its frequency...
15.
Investigations On Lightning Surge Response Of Isolated Down Conductors - Jyothirmayi, R
Lightning is a natural phenomenon involving transient high current discharge in the atmosphere. Cloud-to-ground lightning, wherein the discharge occurs between the cloud and the ground is quite hazardous to systems on the ground. Apart from threat to life, the devastating effects of lightning can be mainly of thermal, mechanical and electromagnetic origin. Many a times, thermal and electromagnetic effects are of main concern.
A direct hit, wherein the system under consideration becomes a part of the
lightning path, could be quite catastrophic to many vulnerable systems like oil rigs, chemical factories, missile/satellite launch pads. From the safety and operational point...
16.
Lightning Protection System To Indian Satellite Launch Pads : Stroke Classification And Evaluation Of Current In The Intercepted Strokes - Hegde, Vishwanath
Satellites have become absolute necessity in the growing modern space technology. At present, launch pads are the only means for launching of satellites or any other space vehicles. Due to the large magnitude of current and the associated rate of rise, a lightning strike to launch pads can be quite disastrous.
Satellite launch complex forms typically the tallest object in that region. This makes them the more vulnerable to cloud-to-ground lightning. In addition, most of the launch pads are situated near the coastal area, where the isokeraunic levels are quite high. In view of these, almost all the satellite launch...
17.
Development Of Algorithms For Bad Data Detection In Power System State Estimation - Musti, S S Phaniram
Power system state estimation (PSSE) is an energy management system function responsible for the computation of the most likely values of state variables viz., bus voltage magnitudes and angles. The state estimation is obtained within a network at a given instant by solving a system of mostly non-linear equations whose parameters are the redundant measurements, both static such as transformer/line parameters and dynamic such as, status of circuit breakers/isolators, transformer tap positions, active/reactive power flows, generator active/reactive power outputs etc. PSSE involves solving an over determined set of nonlinear equations by minimizing a weighted norm of the measurement residuals. Typically,...
18.
Direct Time Domain Modelling Of First Return Stroke Of Lightning - Dileepkumar, K P
Being one of the most spectacular events in nature, lightning is basically a transient high current electric discharge in the atmosphere, which extends up to kilometres. Cloud to ground discharge is the most hazardous one as far as ground based structures are considered. Among the different phases of a lightning flash, return stroke is considered to be the most energetic phase and is basically responsible for most of the damages. Hence, much emphasis has been given to return stroke modeling. A more realistic modeling of return stroke is very essential to accurately study the interaction of return stroke with the...
19.
Modeling, Analysis And Control Of Single-Phase And Three-Phase PWM Rectifiers - Ghosh, Rajesh
Pulse width modulation (PWM) rectifiers are extensively used in battery charger, regulated dc voltage source, UPS systems, ac line conditioner and motor drives. The conventional control schemes for these rectifiers require PLL, transformations, and input voltage sensing, which increase the cost and complexity of the controller. Simple control schemes based on resistance emulation control are developed in this thesis work for different PWM boost rectifiers. Modeling, analysis and design methods for these rectifier systems are presented. The effect of computational delay involved in digital implementation on the performance of the above rectifier systems is studied.
A single-switch boost rectifier system...
20.
Power System Data Compression For Archiving - Das, Sarasij
Advances in electronics, computer and information technology are fueling major changes in the area of power systems instrumentations. More and more microprocessor based digital instruments are replacing older type of meters. Extensive deployment of digital instruments are generating vast quantities of data which is creating information pressure in Utilities. The legacy SCADA based data management systems do not support management of such huge data. As a result utilities either have to delete or store the metered information in some compact discs, tape drives which are unreliable.
Also, at the same time the traditional integrated power industry is going through a...
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