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Computer Sciences Commons™

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2007

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Articles 601 - 630 of 1355

Full-Text Articles in Computer Sciences

A Dynamic Framework For Testing The Synchronization Behavior Of Java Monitors, Andres Yanes May 2007

A Dynamic Framework For Testing The Synchronization Behavior Of Java Monitors, Andres Yanes

Computer Science and Engineering Theses - Archive

A Java monitor is a specialized class that is used to synchronize the behavior of threads in a Java program. The monitors in a Java program must be adequately tested to ensure the correctness of the program. In this thesis we propose a dynamic framework in which a Java monitor is tested by exploring its state space in a depth-first manner. The state exploration procedure consists of dynamically creating method sequences to exercise the possible synchronization behavior of the monitor. During exploration, new threads will be created on the fly to simulate different scenarios that result from threads reaching the …

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Deckard: Scalable And Accurate Tree-Based Detection Of Code Clones, Lingxiao Jiang, Ghassan Misherghi, Zhendong Su, Stephane Glondu May 2007

Deckard: Scalable And Accurate Tree-Based Detection Of Code Clones, Lingxiao Jiang, Ghassan Misherghi, Zhendong Su, Stephane Glondu

Research Collection School Of Computing and Information Systems

Detecting code clones has many software engineering applications. Existing approaches either do not scale to large code bases or are not robust against minor code modifications. In this paper, we present an efficient algorithm for identifying similar subtrees and apply it to tree representations of source code. Our algorithm is based on a novel characterization of subtrees with numerical vectors in the Euclidean Rn and an efficient algorithm to cluster these vectors w.r.t. the Euclidean distance metric. Subtrees with vectors in one cluster are considered similar. We have implemented our tree similarity algorithm as a clone detection tool called DECKARD …

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Residual-Based Measurement Of Peer And Link Lifetimes In Gnutella Networks, Xiaoming Wang, Zhongmei Yao, Dmitri Loguinov May 2007

Residual-Based Measurement Of Peer And Link Lifetimes In Gnutella Networks, Xiaoming Wang, Zhongmei Yao, Dmitri Loguinov

Computer Science Faculty Publications

Existing methods of measuring lifetimes in P2P systems usually rely on the so-called create-based method (CBM), which divides a given observation window into two halves and samples users "created" in the first half every Delta time units until they die or the observation period ends. Despite its frequent use, this approach has no rigorous accuracy or overhead analysis in the literature. To shed more light on its performance, we flrst derive a model for CBM and show that small window size or large Delta may lead to highly inaccurate lifetime distributions. We then show that create-based sampling exhibits an inherent …

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On Node Isolation Under Churn In Unstructured P2p Networks With Heavy-Tailed Lifetimes, Zhongmei Yao, Xiaoming Wang, Dmitri Loguinov May 2007

On Node Isolation Under Churn In Unstructured P2p Networks With Heavy-Tailed Lifetimes, Zhongmei Yao, Xiaoming Wang, Dmitri Loguinov

Computer Science Faculty Publications

Previous analytical studies [12], [18] of unstructured P2P resilience have assumed exponential user lifetimes and only considered age-independent neighbor replacement. In this paper, we overcome these limitations by introducing a general node-isolation model for heavy-tailed user lifetimes and arbitrary neighbor-selection algorithms. Using this model, we analyze two age-biased neighbor-selection strategies and show that they significantly improve the residual lifetimes of chosen users, which dramatically reduces the probability of user isolation and graph partitioning compared to uniform selection of neighbors. In fact, the second strategy based on random walks on age-weighted graphs demonstrates that for lifetimes with infinite variance, the system …

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An Open Source Approach To Wireless Positioning Techniques, Seamus Rooney, Keith Gardiner, James Carswell May 2007

An Open Source Approach To Wireless Positioning Techniques, Seamus Rooney, Keith Gardiner, James Carswell

Conference papers

There are several problems encountered when trying to determine the location of a mobile phone, including weather you are in an urban or rural environment. Also, it is well known that different positioning technologies can work better than others depending on the environment they are in. For example, GPS works well in rural areas but not as well in urban areas, GSM positioning accuracy can be acceptable in urban areas with the right triangulation technology, but is less accurate in rural areas. Positioning with other technologies such as WiFi, Bluetooth, and Semacode all have their own advantages and disadvantages also, …

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Type Inference, Type Improvement, And Type Simplification In A Language With User-Defined Polymorphic Relational Operators, Lajos Pál Nagy May 2007

Type Inference, Type Improvement, And Type Simplification In A Language With User-Defined Polymorphic Relational Operators, Lajos Pál Nagy

Theses and Dissertations

The overarching goal of the current thesis is to pave the road towards a comprehensive solution to the decades old problem of integrating databases and programming languages. For this purpose, we propose a record calculus as an extension of an ML-style functional programming language core. In particular, we describe: 1. a set of polymorphic record operations that are expressive enough to define the operators of the relational algebra; 2. a type system together with a type inference algorithm, based on the theory of qualified types, to correctly capture the types of said polymorphic record operations; 3. an algorithm for checking …

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Virtual Walls: Protecting Digital Privacy In Pervasive Environments, Apu Kapadia, Tristan Henderson, Jeffrey Fielding, David Kotz May 2007

Virtual Walls: Protecting Digital Privacy In Pervasive Environments, Apu Kapadia, Tristan Henderson, Jeffrey Fielding, David Kotz

Dartmouth Scholarship

As pervasive environments become more commonplace, the privacy of users is placed at an increased risk. The numerous and diverse sensors in these environments can record contextual information about users, leading to users unwittingly leaving “digital footprints.” Users must therefore be allowed to control how their digital footprints are reported to third parties. While a significant amount of prior work has focused on location privacy, location is only one specific type of footprint, and we expect most users to be incapable of specifying fine-grained policies for a multitude of footprints. In this paper we present a policy language based on …

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Parallel Nonnegative Matrix Factorization Algorithms For Hyperspectral Images, Lukasz Grzegorz Maciak May 2007

Parallel Nonnegative Matrix Factorization Algorithms For Hyperspectral Images, Lukasz Grzegorz Maciak

Theses, Dissertations and Culminating Projects

Hyperspectral imaging is a branch of remote sensing which deals with creating and processing aerial or satellite pictures that capture wide range of wavelengths, most of which are invisible to the naked eye. Hyperspectral images are composed of many bands, each corresponding to certain light frequencies. Because of their complex nature, image processing tasks such as feature extraction can be resource and time consuming. There are many unsupervised extraction methods available. A recently investigated one is Nonnegative Matrix Factorization (NMF), a method that given positive linear matrix of positive sources, attempts to recover them. In this thesis we designed, implemented …

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Comparing Features Of Three-Dimensional Object Models Using Registration Based On Surface Curvature Signatures, Timothy David Gatzke, Cindy M. Grimm May 2007

Comparing Features Of Three-Dimensional Object Models Using Registration Based On Surface Curvature Signatures, Timothy David Gatzke, Cindy M. Grimm

All Computer Science and Engineering Research

This dissertation presents a technique for comparing local shape properties for similar three-dimensional objects represented by meshes. Our novel shape representation, the curvature map, describes shape as a function of surface curvature in the region around a point. A multi-pass approach is applied to the curvature map to detect features at different scales. The feature detection step does not require user input or parameter tuning. We use features ordered by strength, the similarity of pairs of features, and pruning based on geometric consistency to efficiently determine key corresponding locations on the objects. For genus zero objects, the corresponding locations are …

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Unwoven Aspect Analysis, Morgan G. Deters May 2007

Unwoven Aspect Analysis, Morgan G. Deters

All Computer Science and Engineering Research

Various languages and tools supporting advanced separation of concerns (such as aspect-oriented programming) provide a software developer with the ability to separate functional and non-functional programmatic intentions. Once these separate pieces of the software have been specified, the tools automatically handle interaction points between separate modules, relieving the developer of this chore and permitting more understandable, maintainable code. Many approaches have left traditional compiler analysis and optimization until after the composition has been performed; unfortunately, analyses performed after composition cannot make use of the logical separation present in the original program. Further, for modular systems that can be configured with …

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A Linear-Time Algorithm For Broadcast Domination In A Tree, John Dabney May 2007

A Linear-Time Algorithm For Broadcast Domination In A Tree, John Dabney

All Theses

The broadcast domination problem is a variant of the classical minimum dominating set problem in which a transmitter of power p at vertex v is capable of dominating all vertices within distance p from v. Our goal is to assign a broadcast power f(v) to every vertex v in a graph such that the sum for all v over V of f(v) is minimized, and such that every vertex u with f(u) = 0 is within distance f(v) of some vertex v with f(v) > 0. The problem is solvable in polynomial time on a general graph, and Blair et al. …

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Employing Social Capital By Small & Medium Enterprises To Bear Fruit From Wireless Communications, Abdelnasser Abdelaal, Mehruz Kamal, Peter Wolcott May 2007

Employing Social Capital By Small & Medium Enterprises To Bear Fruit From Wireless Communications, Abdelnasser Abdelaal, Mehruz Kamal, Peter Wolcott

Information Systems and Quantitative Analysis Faculty Proceedings & Presentations

Wireless and mobile communications can save Small and Medium Enterprises (SMEs) significant time, money, and effort due to the mobility, flexibility, and ease of use mobile devices provide. SMEs that use such innovations can improve productivity, decrease costs, and enhance the quality of the business process. Lacking technical skills and financial resources, SMEs need special support from local communities and governments in order to survive the severe competition of big chain stores. This paper proposes a model for SMEs to adopt new innovations—those of wireless communications—by employing social capital. We have used a case study approach to show that social …

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Ets (Efficient, Transparent, And Secured) Self-Healing Service For Pervasive Computing Applications, Shameem Ahmed, Moushumi Sharmin, Sheikh Iqbal Ahamed May 2007

Ets (Efficient, Transparent, And Secured) Self-Healing Service For Pervasive Computing Applications, Shameem Ahmed, Moushumi Sharmin, Sheikh Iqbal Ahamed

Mathematics, Statistics and Computer Science Faculty Research and Publications

To ensure smooth functioning of numerous handheld devices anywhere anytime, the importance of self-healing mechanism cannot be overlooked. Incorporation of efficient fault detection and recovery in device itself is the quest for long but there is no existing self-healing scheme for devices running in pervasive computing environments that can be claimed as the ultimate solution. Moreover, the highest degree of transparency, security and privacy attainability should also be maintained. ETS Self-healing service, an integral part of our developing middleware named MARKS (Middleware Adaptability for Resource discovery, Knowledge usability, and Self-healing), holds promise for offering all of those functionalities.

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Serfs: Dynamically-Bound Parameterized Components, Nigamanth Sridhar May 2007

Serfs: Dynamically-Bound Parameterized Components, Nigamanth Sridhar

Electrical and Computer Engineering Faculty Publications

Parameterization is an effective technique for decoupling design decisions in software. Several languages such as C++ and Ada (and Java and C# more recently) offer language constructs for building parameterized software. Using template or generic constructs, one can postpone committing to specific design choices until the software system is ready for deployment. However, in cases where such choices are influenced by the execution environment, deployment time may not be late enough. Moreover, in the context of software systems that have to satisfy high availability constraints, or are long-running, changes in design choices may be warranted even after deployment. In this …

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Limbustrack: Stable Eye-Tracking In Imperfect Light Conditions, Wayne Ryan May 2007

Limbustrack: Stable Eye-Tracking In Imperfect Light Conditions, Wayne Ryan

All Theses

We are aware of only one serious effort at development of a cheap, accurate, wearable eye tracker: the open source openEyes project. However, its method of ocular feature detection is such that it is prone to failure in variable lighting conditions. To address this deficiency, we have developed a cheap wearable eye tracker. At the heart of our development are novel techniques that allow operation under variable illumination.

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The Effects Of Gaze Guidance On Educational Software, Brian Murphy May 2007

The Effects Of Gaze Guidance On Educational Software, Brian Murphy

All Theses

There are currently three main kinds of eye tracking applications: gaze-responsive, gaze-aware, and gaze-contingent. A fourth classification, termed gaze-guiding, to our knowledge, coined and implemented for the first time. The gaze-guiding technique is the use of motion, light, color, or other visual stimuli to modify the user's fixation to predetermined locations when the user fixates on specific areas of interest. To test the technique, an education software program that teaches physics through the use of gaze-guidance was developed. It is suggested that a natural mapping exists between gaze-guidance and the software's built-in lesson plan. It is also speculated that gaze-guidance …

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An Infrastructure To Support Interoperability In Reverse Engineering, Nicholas Kraft May 2007

An Infrastructure To Support Interoperability In Reverse Engineering, Nicholas Kraft

All Dissertations

An infrastructure that supports interoperability among reverse engineering tools and other software tools is described. The three major components of the infrastructure are: (1) a hierarchy of schemas for low- and middle-level program representation graphs, (2) g4re, a tool chain for reverse engineering C++ programs, and (3) a repository of reverse engineering artifacts, including the previous two components, a test suite, and tools, GXL instances, and XSLT transformations for graphs at each level of the hierarchy. The results of two case studies that investigated the space and time costs incurred by the infrastructure are provided. The results of two empirical …

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Algorithms And Complexity For Alliances And Weighted Alliances Of Various Types, Lindsay Jamieson May 2007

Algorithms And Complexity For Alliances And Weighted Alliances Of Various Types, Lindsay Jamieson

All Dissertations

The concept of alliances was introduced in 2002 in a paper by Kristiansen, Hedetniemi and Hedetniemi. Although research has been published on the mathematical properties of various types of alliances, until recently, no research has been done to develop algorithms or establish the complexity of decision problems for alliances in graphs.
This thesis presents the first algorithmic study of alliances in graphs. We present linear algorithms for finding various alliance numbers in trees and series parallel graphs. These linear algorithms are designed using a new methodology based on the well-established Wimer methodology for designing polynomial algorithms on k-terminal graphs. Linear …

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Gprune: A Constraint Pushing Framework For Graph Pattern Mining, Feida Zhu, Xifeng Yan, Jiawei Han, Philip S. Yu May 2007

Gprune: A Constraint Pushing Framework For Graph Pattern Mining, Feida Zhu, Xifeng Yan, Jiawei Han, Philip S. Yu

Research Collection School Of Computing and Information Systems

In graph mining applications, there has been an increasingly strong urge for imposing user-specified constraints on the mining results. However, unlike most traditional itemset constraints, structural constraints, such as density and diameter of a graph, are very hard to be pushed deep into the mining process. In this paper, we give the first comprehensive study on the pruning properties of both traditional and structural constraints aiming to reduce not only the pattern search space but the data search space as well. A new general framework, called gPrune, is proposed to incorporate all the constraints in such a way that they …

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Achieving End-To-End Authentication In Intermediary-Enabled Multimedia Delivery Systems, Robert H. Deng, Yanjiang Yang May 2007

Achieving End-To-End Authentication In Intermediary-Enabled Multimedia Delivery Systems, Robert H. Deng, Yanjiang Yang

Research Collection School Of Computing and Information Systems

Considerable research and experiment results in recent years have shown that the server-proxy-user architecture represents an efficient and scalable new paradigm for multimedia content delivery. However, not much effort has been spent on the security issues in such systems. In this paper, we study data authentication in multimedia content delivery, and in particular, we focus on achieving end-to-end authentication from the multimedia server to end users in the server-proxy-user architecture where intermediary proxies transcode multimedia content dynamically. We present a formal model for the end-to-end authentication problem, and propose a basic construction for generic data modality and prove its security. …

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Analysis Of Topological Characteristics Of Huge Online Social Networking Services, Yong-Yeol Ahn, Seungyeop Han, Haewoon Kwak, Sue Moon, Hawoong Jeong May 2007

Analysis Of Topological Characteristics Of Huge Online Social Networking Services, Yong-Yeol Ahn, Seungyeop Han, Haewoon Kwak, Sue Moon, Hawoong Jeong

Research Collection School Of Computing and Information Systems

Social networking services are a fast-growing business in the Internet. However, it is unknown if online relationships and their growth patterns are the same as in real-life social networks. In this paper, we compare the structures of three online social networking services: Cyworld, MySpace, and orkut, each with more than 10 million users, respectively. We have access to complete data of Cyworld's ilchon (friend) relationships and analyze its degree distribution, clustering property, degree correlation, and evolution over time. We also use Cyworld data to evaluate the validity of snowball sampling method, which we use to crawl and obtain partial network …

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Cognitive Evaluation Of Information Modeling Methods, Keng Siau, Yuan Wang May 2007

Cognitive Evaluation Of Information Modeling Methods, Keng Siau, Yuan Wang

Research Collection School Of Computing and Information Systems

In the field of information system engineering, information modeling method is a technique to capture user requirements and to understand system complexity. The importance of information modeling has been recognized by practitioners and researchers, but little has been explored to analyze the available information modeling methods or to evaluate them in terms of their strengths, weaknesses, and effectiveness. This research analyzes six information-modeling methods: use case diagram, rich picture diagram, entity-relationship diagram, Trochim’s concept mapping, repertory grid, and causal mapping. These information-modeling methods are analyzed from a cognitive perspective in order to better understand their nature, the assumptions, and the …

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Learning To Classify E-Mail, Irena Koprinska, Josiah Poon, James Clark, Jason Yuk Hin Chan May 2007

Learning To Classify E-Mail, Irena Koprinska, Josiah Poon, James Clark, Jason Yuk Hin Chan

Research Collection School Of Computing and Information Systems

In this paper we study supervised and semi-supervised classification of e-mails. We consider two tasks: filing e-mails into folders and spam e-mail filtering. Firstly, in a supervised learning setting, we investigate the use of random forest for automatic e-mail filing into folders and spam e-mail filtering. We show that random forest is a good choice for these tasks as it runs fast on large and high dimensional databases, is easy to tune and is highly accurate, outperforming popular algorithms such as decision trees, support vector machines and naive Bayes. We introduce a new accurate feature selector with linear time complexity. …

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Management Of An Intelligent Argumentation Network For A Web-Based Collaborative Engineering Design Environment, Xiaoqing Frank Liu, Man Zheng, Ganesh K. Venayagamoorthy, Ming-Chuan Leu May 2007

Management Of An Intelligent Argumentation Network For A Web-Based Collaborative Engineering Design Environment, Xiaoqing Frank Liu, Man Zheng, Ganesh K. Venayagamoorthy, Ming-Chuan Leu

Computer Science Faculty Research & Creative Works

Conflict resolution is one of the most challenging tasks in collaborative engineering design. In our previous research, a web-based intelligent collaborative system was developed to address this challenge based on intelligent computational argumentation. However, two important issues were not resolved in that system: priority of participants and self-conflicting arguments. In this paper, we develop two methods for incorporating priorities of participants into the computational argumentation network: 1) weighted summation and 2) re-assessment of strengths of arguments based on priority of owners of the argument using fuzzy logic inference. In addition, we develop a method for detection of self-conflicting arguments. Incorporation …

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Forgery Attack To An Asymptotically Optimal Traitor Tracing Scheme, Yongdong Wu, Feng Bao, Robert H. Deng May 2007

Forgery Attack To An Asymptotically Optimal Traitor Tracing Scheme, Yongdong Wu, Feng Bao, Robert H. Deng

Research Collection School Of Computing and Information Systems

In this paper, we present a forgery attack to a black-box traitor tracing scheme [2] called as CPP scheme. CPP scheme has efficient transmission rate and allows the tracer to identify a traitor with just one invalid ciphertext. Since the original CPP scheme is vulnerable to the multi-key attack, we improved CPP to thwart the attack. However, CPP is vulnerable to a fatal forgery attack. In the forgery attack, two traitors can collude to forge all valid decryption keys. The forged keys appear as perfect genuine keys, can decrypt all protected content, but are untraceable by the tracer. Fortunately, we …

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Enhancing The Performance Of Semi-Supervised Classification Algorithms With Bridging, Jason Yuk Hin Chan, Josiah Poon, Irena Koprinska May 2007

Enhancing The Performance Of Semi-Supervised Classification Algorithms With Bridging, Jason Yuk Hin Chan, Josiah Poon, Irena Koprinska

Research Collection School Of Computing and Information Systems

Traditional supervised classification algorithms require a large number of labelled examples to perform accurately. Semi-supervised classification algorithms attempt to overcome this major limitation by also using unlabelled examples. Unlabelled examples have also been used to improve nearest neighbour text classification in a method called bridging. In this paper, we propose the use of bridging in a semi-supervised setting. We introduce a new bridging algorithm that can be used as a base classifier in any supervised approach such as co-training or selflearning. We empirically show that classification performance increases by improving the semi-supervised algorithm’s ability to correctly assign labels to previouslyunlabelled …

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Modeling Architectural Strategy Using Design Structure Networks, C. Jason Woodard May 2007

Modeling Architectural Strategy Using Design Structure Networks, C. Jason Woodard

Research Collection School Of Computing and Information Systems

System architects face the formidable task of purposefully shaping an evolving space of complex designs. Their task s further complicated when they lack full control of the design process, and therefore must anticipate the behavior of other stakeholders, including the designers of component products and competing systems. This paper presents a conceptual tool called a design structure network (DSN) to help architects and design scientists reason effectively about these situations. A DSN is a graphical representation of a system’s design space. DSNs improve on existing representation schemes by providing a compact and intuitive way to express design options—the ability to …

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Experiment Planning For Protein Structure Elucidation And Site-Directed Protein Recombination, Xiaoduan Ye May 2007

Experiment Planning For Protein Structure Elucidation And Site-Directed Protein Recombination, Xiaoduan Ye

Dartmouth College Ph.D Dissertations

In order to most effectively investigate protein structure and improve protein function, it is necessary to carefully plan appropriate experiments. The combinatorial number of possible experiment plans demands effective criteria and efficient algorithms to choose the one that is in some sense optimal. This thesis addresses experiment planning challenges in two significant applications. The first part of this thesis develops an integrated computational-experimental approach for rapid discrimination of predicted protein structure models by quantifying their consistency with relatively cheap and easy experiments (cross-linking and site-directed mutagenesis followed by stability measurement). In order to obtain the most information from noisy and …

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To Repair Or Not To Repair: Helping Ad Hoc Routing Protocols To Distinguish Mobility From Congestion, Qiuyi Duan, Roger Pack, Manoj Pandey, Lei Wang, Daniel Zappala May 2007

To Repair Or Not To Repair: Helping Ad Hoc Routing Protocols To Distinguish Mobility From Congestion, Qiuyi Duan, Roger Pack, Manoj Pandey, Lei Wang, Daniel Zappala

Faculty Publications

In this paper we consider the problem of distinguishing whether frame loss at the MAC layer has occurred due to mobility or congestion. Most ad hoc routing protocols make the faulty assumption that all frame loss means the destination node has moved, resulting in significant overhead as they initiate the repair of routes that have not been broken. We design a mobility detection algorithm, MDA, that properly detects the cause of a lost frame, then coordinates with the routing protocol so that it reacts properly. This approach dramatically reduces routing protocol overhead and significantly increases application throughput. We use a …

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Probabilistic Searching Using A Small Unmanned Aerial Vehicle, Steven R. Hansen, Timothy W. Mclain, Michael A. Goodrich May 2007

Probabilistic Searching Using A Small Unmanned Aerial Vehicle, Steven R. Hansen, Timothy W. Mclain, Michael A. Goodrich

Faculty Publications

Ground breaking concepts in optimal search theory were developed during World War II by the U.S. Navy. These concepts use an assumed detection model to calculate a detection probability rate and an optimal search allocation. Although this theory is useful in determining when and where search effort should be applied, it offers little guidance for the planning of search paths. This paper explains how search theory can be applied to path planning for an SUAV with a fixed CCD camera. Three search strategies are developed: greedy search, contour search, and composite search. In addition, the concepts of search efficiency and …

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