ETD at Indian Institute of Science
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.
Computer Science and Automation (csa)
Mostrando recursos 1 - 20 de 142
Studies In Automatic Management Of Storage Systems - Pipada, Pankaj
Autonomic management is important in storage systems and the space of autonomics in storage systems is vast. Such autonomic management systems can employ a variety of techniques depending upon the specific problem. In this thesis, we first take an algorithmic approach towards reliability enhancement and then we use learning along with a reactive framework to facilitate storage optimization for applications.
We study how the reliability of non-repairable systems can be improved through automatic reconfiguration of their XOR-coded structure. To this regard we propose to increase the fault tolerance of non-repairable systems by reorganizing the system, after a failure is detected, to...
Power Efficient Last Level Cache For Chip Multiprocessors - Mandke, Aparna
The number of processor cores and on-chip cache size has been increasing on chip multiprocessors (CMPs). As a result, leakage power dissipated in the on-chip cache has become very significant. We explore various techniques to switch-off the over-allocated cache so as to reduce leakage power consumed by it. A large cache offers non-uniform access latency to different cores present on a CMP and such a cache is called “Non-Uniform Cache Architecture (NUCA)”. Past studies have explored techniques to reduce leakage power for uniform access latency caches and with a single application executing on a uniprocessor. Our ideas of power optimized...
Learning Robust Support Vector Machine Classifiers With Uncertain Observations - Bhadra, Sahely
The central theme of the thesis is to study linear and non linear SVM formulations in the presence of uncertain observations. The main contribution of this thesis is to derive robust classfiers from partial knowledge of the underlying uncertainty.
In the case of linear classification, a new bounding scheme based on Bernstein inequality has been proposed, which models interval-valued uncertainty in a less conservative fashion and hence is expected to generalize better than the existing methods. Next, potential of partial information such as bounds on second order moments along with support information has been explored. Bounds on second order moments...
Sentiment-Driven Topic Analysis Of Song Lyrics - Sharma, Govind
Sentiment Analysis is an area of Computer Science that deals with the impact a document makes on a user. The very field is further sub-divided into Opinion Mining and Emotion Analysis, the latter of which is the basis for the present work. Work on songs is aimed at building affective interactive applications such as music recommendation engines. Using song lyrics, we are interested in both supervised and unsupervised analyses, each of which has its own pros and cons.
For an unsupervised analysis (clustering), we use a standard probabilistic topic model called Latent Dirichlet Allocation (LDA). It mines topics from songs,...
New Approaches And Experimental Studies On - Alegebraic Attacks On Stream Ciphers - Pillai, N Rajesh
Algebraic attacks constitute an effective class of cryptanalytic attacks which have come up recently. In algebraic attacks, the relations between the input, output and the key are expressed as a system of equations and then solved for the key. The main idea is in obtaining a system of equations
which is solvable using reasonable amount of resources. The new approaches proposed in this work and experimental studies on the existing algebraic attacks on stream ciphers will be presented.
In the first attack on filter generator, the input-output relations are expressed in conjunctive normal form. The system of equations is then solved using...
Visual Analysis Of Interactions In Multifield Scientific Data - Suthambhara, N
Data from present day scientific simulations and observations of physical processes often consist of multiple scalar fields. It is important to study the interactions between the fields to understand the underlying phenomena. A visual representation of these interactions would assist the scientist by providing quick insights into complex relationships that exist between the fields.
We describe new techniques for visual analysis of multifield scalar data where the relationships can be quantified by the gradients of the individual scalar fields and their mutual alignment. Empirically, gradients along with their mutual alignment have been shown to be a good indicator of the...
Rainbow Connection Number Of Graph Power And Graph Products - Arunselvan, R
The minimum number of colors required to color the edges of a graph so that any two distinct vertices are connected by at least one path in which no two edges are colored the same is called its rainbow connection number. This graph parameter was introduced by Chartrand et al. in 2008. The problem has garnered considerable interest and several variants of the initial version have since been introduced. The rainbow connection number of a connected graph G is denoted by rc(G). It can be shown that the rainbow connection number of a tree on n vertices is n -1....
A Novel Game Theoretic And Voting Mechanism Based Approach For Carbon Emissions Reduction - Shelke, Sunil Sitaram
Global warming is currently a major challenge facing the world. There are widespread ongoing efforts in the form of summits, conferences, etc., to find satisfactory ways of surmounting this challenge. The basic objective of all such efforts can be summarized as conception and formation of protocols to reduce the pace of global carbon levels. Game theory and mechanism design provide a natural modeling tool for capturing the strategic dynamics involved in global warming related problems. This dissertation explores for the first time the use of voting mechanisms in the context of solving the central problems, namely, allocation of emission caps...
Autonomous Spacecraft Mission Planning And Execution In A Petri Net Framework - Indra, A
Presently, most spacecraft are controlled from ground involving activities such as up-linking the schedule of daily operations and monitoring health parameters. These activities lead to a cognitive overload on human operators. Imaging/science opportunities are lost, if any discrepancies occur during the execution of pre-planned sequences. Consequently, advanced space exploration systems for future needs demand on-board intelligence and autonomy. This thesis attempts to solve the problem of providing an adequate degree of autonomy in future generation of spacecraft. The autonomous spacecraft accept high-level goals from users and make decisions on-board to generate detailed command schedules satisfying stringent constraints posed by the...
Two Player Game Variant Of The Erdos Szekeres Problem - Parikshit, K
The following problem has been known for its beauty and elementary character. The Erd˝os Szekeres problem:
For any integer k ≥ 3, determine if there exists a smallest positive integer N(k) such that any set of atleast N(k) points in general position in the plane(i.e no three points are in a line) contains k points that are the vertices of a convex k-gon.
The finiteness of (k)is proved by Erd˝os and Szekeres using Ramsey theory.
In 1978, Erd˝os  raised a similar question on empty convex k-gon (convex k-gon without out any interior points) and it has been extensively studied....
Game Theoretic Models For Social Network Analysis - Narayanam, Ramasuri
With increasing demand for social network based activities, it is very important to understand not only the structural properties of social networks but also how social networks form, to better exploit their promise and potential. We believe the existing methods and tools for social network analysis have a major inadequacy: they do not capture the behavior (such as rationality and intelligence) of individuals nor do they model the strategic interactions that occur among these individuals. Game theory is a natural tool to overcome this inadequacy since it provides rigorous mathematical models of strategic interaction among autonomous, intelligent, and rational agents....
An Algorithmic Characterization Of Polynomial Functions Over Zpn - Guha, Ashwin
The problem of polynomial representability of functions is central to many branches of mathematics. If the underlying set is a finite field, every function can be represented as a polynomial. In this thesis we consider polynomial representability over a special class of finite rings, namely, Zpn, where p is a prime and n is a positive integer. This problem has been studied in literature and the two notable results were given by Carlitz(1965) and Kempner(1921).While the Kempner’s method enumerates the set of distinct polynomial functions, Carlitz provides a necessary and sufficient condition for a function to be polynomial using Taylor...
Reliability Modelling Of Whole RAID Storage Subsystems - Karmakar, Prasenjit
Reliability modelling of RAID storage systems with its various components such as RAID controllers, enclosures, expanders, interconnects and disks is important from a storage system designer's point of view. A model that can express all the failure characteristics of the whole RAID storage system can be used to evaluate design choices, perform cost reliability trade-offs and conduct sensitivity analyses.
We present a reliability model for RAID storage systems where we try to model all the components as accurately as possible. We use several state-space reduction techniques, such as aggregating all in-series components and hierarchical decomposition, to reduce the size...
Design Of Truthful Allocation Mechanisms For Carbon Footprint Reduction - Udaya Lakshmi, L
Global warming is currently a major challenge faced by the world. Reduction of carbon emissions is of paramount importance in the context of global warming. There are widespread ongoing efforts to find satisfactory ways of surmounting this challenge. The basic objective of all such efforts can be summarized as conception and formation of protocols to reduce the pace of global carbon levels. Countries and global companies are now engaged in understanding systematic ways of achieving
well defined emission targets. In this dissertation, we explore the specific problem faced by a global industry or global company in allocating carbon emission reduction units...
Boxicity And Cubicity : A Study On Special Classes Of Graphs - Mathew, Rogers
Let F be a family of sets. A graph G is an intersection graph of sets from the family F if there exists a mapping f : V (G)→ F such that, An interval graph is an intersection graph of a family of closed intervals on the real line. Interval graphs find application in diverse fields ranging from DNA analysis to VLSI design.
An interval on the real line can be generalized to a k dimensional box or k-box. A k-box B = (R1.R2….Rk) is defined to be the Cartesian product R1 × R2 × …× Rk, where each Ri is...
Scaling Context-Sensitive Points-To Analysis - Nasre, Rupesh
Pointer analysis is one of the key static analyses during compilation. The efficiency of several compiler optimizations and transformations depends directly on the scalability and precision of the underlying pointer analysis. Recent advances still lack an efficient and scalable context-sensitive inclusion-based pointer analysis. In this work, we propose four novel techniques to improve the scalability of context-sensitive points-to analysis for C/C++ programs.
First, we develop an efficient way of storing the approximate points-to information using a multi-dimensional bloom filter (multibloom). By making use of fast hash functions and exploiting the spatial locality of the points-to information, our multibloom-based points-to analysis...
Algorithms For Stochastic Games And Service Systems - Prasad, H L
This thesis is organized into two parts, one for my main area of research in the field of stochastic games, and the other for my contributions in the area of service systems. We first provide an abstract for my work in stochastic games.
The field of stochastic games has been actively pursued over the last seven decades because of several of its important applications in oligopolistic economics. In the past, zero-sum stochastic games have been modelled and solved for Nash equilibria using the standard techniques of Markov decision processes. General-sum stochastic games on the contrary have posed difficulty as they...
Graph Models For Query Focused Text Summarization And Assessment Of Machine Translation Using Stopwords - Rama, B
Text summarization is the task of generating a shortened version of the original text where core ideas of the original text are retained. In this work, we focus on query focused summarization. The task is to generate the summary from a set of documents which answers the query. Query focused summarization is a hard task because it expects the summary to be biased towards the query and at the same time important concepts in the original documents must be preserved with high degree of novelty.
Graph based ranking algorithms which use biased random surfer model like Topic-sensitive LexRank have been...
Network Centrality Measures And Their Applications - Sudarshan, S R
Study of complex networks by researchers from many disciplines has provided penetrating insights on various complex systems. A study of the world wide web from a network theoretic perspective has led to the design of new search engines . The spread of diseases is now better understood by analyzing the underlying social network . The study of metabolic networks, protein-protein interaction networks and the transcriptional regulatory networks with graph theoretic rigor, has led to the growing importance of an interdisciplinary approach .
Network centrality measures, which has been of interest to the social scientists, from as long as 1950 ,...
Image Structures For Steganalysis And Encryption - Suresh, V
In this work we study two aspects of image security: improper usage and illegal access of images. In the first part we present our results on steganalysis – protection against improper usage of images. In the second part we present our results on image encryption – protection against illegal access of images.
Steganography is the collective name for methodologies that allow the creation of invisible –hence secret– channels for information transfer. Steganalysis, the counter to steganography, is a collection of approaches that attempt to detect and quantify the presence of hidden messages in cover media.
First we present our studies...