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2009

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Articles 391 - 420 of 1345

Full-Text Articles in Computer Sciences

Fair Electronic Exchange Using Biometrics, Harkeerat Bedi Aug 2009

Fair Electronic Exchange Using Biometrics, Harkeerat Bedi

Masters Theses and Doctoral Dissertations

Fair exchange between two parties can be defined as an instance of exchange such that either both parties obtain what they expected or neither one does. Protocols that facilitate such transactions are known as “fair exchange protocols”. We analyze one such protocol by Micali that demonstrates fair contract signing, where two parties exchange their commitments over an already negotiated contract. In this research we show that Micali’s protocol is not completely fair and demonstrate the possibilities for one party cheating by obtaining the other party’s commitment and not offer theirs. A revised version of this protocol by Bao provides superior …

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Single Command Rendering With Sun Grid Engine, William Robinson Aug 2009

Single Command Rendering With Sun Grid Engine, William Robinson

All Theses

According to the Autodesk website, Autodesk Maya software is a powerful, integrated 3D modeling, animation, visual effects, and rendering solution. While this statement is true in every sense, one quality that this software and its competitors lack is in the area of resource management. Though not as critical to the other tasks in the production line, resource management is a crucial component of successful rendering. Until recently, Digital Production Arts students have been left to their own means to manage the rendering process; however, with the use of Sun Grid Engine, rendering tasks can be simplified to a single-command process, …

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Link Scheduling For Scalable Data Aggregation, Jamie Macbeth, Majid Sarrafzadeh Aug 2009

Link Scheduling For Scalable Data Aggregation, Jamie Macbeth, Majid Sarrafzadeh

Computer Science: Faculty Publications

We explore the link scheduling optimization problem in the context of scalable in-network data aggregation, extending results for broadcast networks to routing in general networks. The primary vehicle for resource preservation is transmission suppression. For certain types of queries, nodes can avoid transmitting records if they can locally infer that their data is not needed to execute the query. We introduce a novel protocol paradigm for duplicate-insensitive exemplary monotonic (e.g. MIN and MAX) data aggregation queries. Performance of query execution in these networks is measured through collective expected number of transmissions in the network, and is linked to the minimum …

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Fast Rendering Of Forest Ecosystems With Dynamic Global Illumination, Jay Steele Aug 2009

Fast Rendering Of Forest Ecosystems With Dynamic Global Illumination, Jay Steele

All Dissertations

Real-time rendering of large-scale, forest ecosystems remains
a challenging problem, in that important global illumination effects,
such as leaf transparency and inter-object light scattering, are
difficult to capture, given tight timing constraints and scenes
that typically contain hundreds of millions of primitives.
We propose a new lighting model, adapted from
a model previously used to light convective clouds and other
participating media,
together with GPU ray tracing, in order to achieve these global illumination
effects while maintaining near real-time performance. The lighting
model is based on a lattice-Boltzmann method in which
reflectance, transmittance, and absorption parameters are
taken from measurements …

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Dartmouth Internet Security Testbed (Dist): Building A Campus-Wide Wireless Testbed, Sergey Bratus, David Kotz, Keren Tan, William Taylor, Anna Shubina, Bennet Vance, Michael E. Locasto Aug 2009

Dartmouth Internet Security Testbed (Dist): Building A Campus-Wide Wireless Testbed, Sergey Bratus, David Kotz, Keren Tan, William Taylor, Anna Shubina, Bennet Vance, Michael E. Locasto

Dartmouth Scholarship

We describe our experiences in deploying a campus-wide wireless security testbed. The testbed gives us the capability to monitor security-related aspects of the 802.11 MAC layer in over 200 diverse campus locations. We describe both the technical and the social challenges of designing, building, and deploying such a system, which, to the best of our knowledge, is the largest such testbed in academia (with the UCSD's Jigsaw infrastructure a close competitor). In this paper we focus on the \em testbed setup, rather than on the experimental data and results.

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Hardware-Assisted Secure Computation, Alexander Iliev Aug 2009

Hardware-Assisted Secure Computation, Alexander Iliev

Dartmouth College Ph.D Dissertations

The theory community has worked on Secure Multiparty Computation (SMC) for more than two decades, and has produced many protocols for many settings. One common thread in these works is that the protocols cannot use a Trusted Third Party (TTP), even though this is conceptually the simplest and most general solution. Thus, current protocols involve only the direct players---we call such protocols self-reliant. They often use blinded boolean circuits, which has several sources of overhead, some due to the circuit representation and some due to the blinding. However, secure coprocessors like the IBM 4758 have actual security properties similar to …

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A Study For Scalable Directory In Parallel File Systems, Yang Wu Aug 2009

A Study For Scalable Directory In Parallel File Systems, Yang Wu

All Theses

One of the challenges that the design of parallel file system for
HPC(High Performance Computing) has to face today is maintaining the
scalability to handle the I/O generated by parallel applications that
involve accessing directories containing a large number of entries and
performing hundreds of thousands of operations per second. Currently,
highly concurrent access to large directories is poorly supported in
parallel file systems. As a result, it is important to build a
scalable directory service for parallel file systems to support
efficient concurrent access to larger directories.
In this thesis we demonstrate a scalable directory service designed
for parallel …

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Non-Rigid Multi-Modal Object Tracking Using Gaussian Mixture Models, Prakash Chockalingam Aug 2009

Non-Rigid Multi-Modal Object Tracking Using Gaussian Mixture Models, Prakash Chockalingam

All Theses

This work presents an approach to visual tracking based on dividing a target into multiple regions, or fragments. The target is represented by a Gaussian mixture model in a joint feature-spatial space, with each ellipsoid corresponding to a different fragment. The fragment set and its cardinality are automatically adapted to the image data using an efficient region-growing procedure and updated according to a weighted average of the past and present image statistics. The fragment modeling is used to generate a strength map indicating the probability of each pixel belonging to the foreground. The strength map provides vital information about new …

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Accurate Tracking Of Objects Using Level Sets, Nalin Senthamil Aug 2009

Accurate Tracking Of Objects Using Level Sets, Nalin Senthamil

All Theses

Our current work presents an approach to tackle the challenging task of tracking objects in Internet videos taken from large web repositories such as YouTube. Such videos more often than not, are captured by users using their personal hand-held cameras and cellphones and hence suffer from problems such as poor quality, camera jitter and unconstrained lighting and environmental settings. Also, it has been observed that events being recorded by such videos usually contain objects moving in an unconstrained fashion. Hence, tracking objects in Internet videos is a very challenging task in the field of computer vision since there is no …

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Deploying And Maintaining A Campus Grid At Clemson University, Dru Sepulveda Aug 2009

Deploying And Maintaining A Campus Grid At Clemson University, Dru Sepulveda

All Theses

Many institutions have all the tools needed to create a local grid that aggregates commodity compute resources into an accessible grid service, while simultaneously maintaining user satisfaction and system security. In this thesis, the author presents a three-tiered strategy used at Clemson University to deploy and maintain a grid infrastructure by making resources available to both local and federated remote users for scientific research. Using this approach virtually no compute cycles are wasted. Usage trends and power consumption statistics collected from the Clemson campus grid are used as a reference for best-practices. The loosely-coupled components that comprise the campus grid …

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A Study Of Client-Based Caching For Parallel I/O, Bradley Settlemyer Aug 2009

A Study Of Client-Based Caching For Parallel I/O, Bradley Settlemyer

All Dissertations

The trend in parallel computing toward large-scale cluster computers running thousands of cooperating processes per application has led to an I/O bottleneck that has only gotten more severe as the the number of processing cores per CPU has increased. Current parallel file systems are able to provide high bandwidth file access for large contiguous file region accesses; however, applications repeatedly accessing small file regions on unaligned file region boundaries continue to experience poor I/O throughput due to the high overhead associated with accessing parallel file system data.
In this dissertation we demonstrate how client-side file data caching can improve parallel …

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Inferring Player Rating From Performance Data In Massively Multiplayer Online Role-Playing Games (Mmorpgs), Kyong Jin Shim, Muhammad Aurangzeb Ahmad, Nishith Pathak, Jaideep Srivastava Aug 2009

Inferring Player Rating From Performance Data In Massively Multiplayer Online Role-Playing Games (Mmorpgs), Kyong Jin Shim, Muhammad Aurangzeb Ahmad, Nishith Pathak, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

This paper examines online player performance in EverQuest II, a popular massively multiplayer online role-playing game (MMORPG) developed by Sony Online Entertainment. The study uses the game's player performance data to devise performance metrics for online players. We report three major findings. First, we show that the game's point-scaling system overestimates performances of lower level players and underestimates performances of higher level players. We present a novel point-scaling system based on the game's player performance data that addresses the underestimation and overestimation problems. Second, we present a highly accurate predictive model for player performance as a function of past behavior. …

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Multi-Task Transfer Learning For Weakly-Supervised Relation Extraction, Jing Jiang Aug 2009

Multi-Task Transfer Learning For Weakly-Supervised Relation Extraction, Jing Jiang

Research Collection School Of Computing and Information Systems

Creating labeled training data for relation extraction is expensive. In this paper, we study relation extraction in a special weakly-supervised setting when we have only a few seed instances of the target relation type we want to extract but we also have a large amount of labeled instances of other relation types. Observing that different relation types can share certain common structures, we propose to use a multi-task learning method coupled with human guidance to address this weakly-supervised relation extraction problem. The proposed framework models the commonality among different relation types through a shared weight vector, enables knowledge learned from …

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Symphony: Enabling Search-Driven Applications, John C. Shafer, Rakesh Agrawal, Hady W. Lauw Aug 2009

Symphony: Enabling Search-Driven Applications, John C. Shafer, Rakesh Agrawal, Hady W. Lauw

Research Collection School Of Computing and Information Systems

We present the design of Symphony, a platform that enables non-developers to build and deploy a new class of search-driven applications that combine their data and domain expertise with content from search engines and other web services. The Symphony prototype has been built on top of Microsoft’s Live Search infrastructure. While Symphony naturally makes use of the customization capabilities exposed by Live Search, its distinguishing feature is the capability it provides to the application creator to combine their proprietary data and domain expertise with content obtained from Live Search. They can also integrate specialized data obtained from web services to …

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Data Mining For Software Engineering, Tao Xie, Suresh Thummalapenta, David Lo, Chao Liu Aug 2009

Data Mining For Software Engineering, Tao Xie, Suresh Thummalapenta, David Lo, Chao Liu

Research Collection School Of Computing and Information Systems

To improve software productivity and quality, software engineers are increasingly applying data mining algorithms to various software engineering tasks. However, mining SE data poses several challenges. The authors present various algorithms to effectively mine sequences, graphs, and text from such data.

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Reducing Source Load In Bittorrent, Brian Sanderson, Daniel Zappala Aug 2009

Reducing Source Load In Bittorrent, Brian Sanderson, Daniel Zappala

Faculty Publications

One of the main goals of BitTorrent is to reduce load on web servers by encouraging clients to share content between themselves. However, BitTorrent’s current design relies heavily on the original source to serve a disproportionate amount of the file. We modify standard BitTorrent software so that a source determines the current popularity of each of the blocks of a file and tries to serve only those blocks that are rare. Using extensive PlanetLab experiments, we show that this modification can save a significant amount of the source’s upload bandwidth, with the tradeoff of some increased peer download time. In …

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Multilayer Image Inpainting Approach Based On Neural Networks, Quan Wang, Zhaoxia Wang, Che Sau Chang, Ting Yang Aug 2009

Multilayer Image Inpainting Approach Based On Neural Networks, Quan Wang, Zhaoxia Wang, Che Sau Chang, Ting Yang

Research Collection School Of Computing and Information Systems

This paper describes an image inpainting approach based on the self-organizing map for dividing an image into several layers, assigning each damaged pixel to one layer, and then restoring these damaged pixels by the information of their respective layer. These inpainted layers are then fused together to provide the final inpainting results. This approach takes advantage of the neural network's ability of imitating human's brain to separate objects of an image into different layers for inpainting. The approach is promising as clearly demonstrated by the results in this paper.

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Essential Spreadsheet Modeling Course For Business Students, Thin Yin Leong, Michelle L. F. Cheong Aug 2009

Essential Spreadsheet Modeling Course For Business Students, Thin Yin Leong, Michelle L. F. Cheong

Research Collection School Of Computing and Information Systems

Ask any student at the Singapore Management University (SMU) to name one of the most practical and useful courses offered by the university. The answer would inevitably include CAT. CAT stands for the "Computer as an Analysis Tool" course. Originally based on a course of the same title offered by the Wharton Business School, the focus of CAT was shifted to provide business students the essential practical skills and necessary "real-world" exposure to better use personal computers for resolving business problems. The course is basically centered on using the Excel spreadsheet to work on ambiguous ill-defined problems.

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Game Action Based Power Management For Multiplayer Online Game, Bhojan Anand, A. L. Ananda, Mun Choon Chan, Long Thanh Le, Rajesh Krishna Balan Aug 2009

Game Action Based Power Management For Multiplayer Online Game, Bhojan Anand, A. L. Ananda, Mun Choon Chan, Long Thanh Le, Rajesh Krishna Balan

Research Collection School Of Computing and Information Systems

Current mobile devices embrace a wide range of functionalities including high speed network support, hardware accelerated 3D graphics, and multimedia capabilities. These capabilities have boosted the interest for enabling multiplayer online games (MOG) support on such devices. However, the lack of similar growth in battery technology limits the usability of these devices for MOGs. In this paper, we present energy conservation techniques for highly interactive MOGs. These are games, such as first-person shooters, where crisp user interaction is paramount to the overall game experience. Hence, conserving energy while preserving crisp user interaction becomes a critical consideration in this domain. We …

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Ssnetviz: A Visualization Engine For Heterogeneous Semantic Social Networks, Ee Peng Lim, Maureen Maureen, Nelman Lubis Ibrahim, Aixin Sun, Anwitaman Datta, Kuiyu Chang Aug 2009

Ssnetviz: A Visualization Engine For Heterogeneous Semantic Social Networks, Ee Peng Lim, Maureen Maureen, Nelman Lubis Ibrahim, Aixin Sun, Anwitaman Datta, Kuiyu Chang

Research Collection School Of Computing and Information Systems

SSnetViz is an ongoing research to design and implement a visualization engine for heterogeneous semantic social networks. A semantic social network is a multi-modal network that contains nodes representing di®erent types of people or object entities, and edges representing relationships among them. When multiple heterogeneous semantic social networks are to be visualized together, SSnetViz provides a suite of functions to store heterogeneous semantic social networks, to integrate them for searching and analysis. We will illustrate these functions using social networks related to terrorism research, one crafted by domain experts and another from Wikipedia.

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Extracting Paraphrases Of Technical Terms From Noisy Parallel Software Corpus, Xiaoyin Wang, David Lo, Jing Jiang, Lu Zhang, Hong Mei Aug 2009

Extracting Paraphrases Of Technical Terms From Noisy Parallel Software Corpus, Xiaoyin Wang, David Lo, Jing Jiang, Lu Zhang, Hong Mei

Research Collection School Of Computing and Information Systems

In this paper, we study the problem of extracting technical paraphrases from a parallel software corpus, namely, a collection of duplicate bug reports. Paraphrase acquisition is a fundamental task in the emerging area of text mining for software engineering. Existing paraphrase extraction methods are not entirely suitable here due to the noisy nature of bug reports. We propose a number of techniques to address the noisy data problem. The empirical evaluation shows that our method significantly improves an existing method by upto 58%

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Setting Discrete Bid Levels Adaptively In Repeated Auctions, Jilian Zhang, Hoong Chuin Lau, Jialie Shen Aug 2009

Setting Discrete Bid Levels Adaptively In Repeated Auctions, Jilian Zhang, Hoong Chuin Lau, Jialie Shen

Research Collection School Of Computing and Information Systems

The success of an auction design often hinges on its ability to set parameters such as reserve price and bid levels that will maximize an objective function such as the auctioneer revenue. Works on designing adaptive auction mechanisms have emerged recently, and the challenge is in learning different auction parameters by observing the bidding in previous auctions. In this paper, we propose a non-parametric method for determining discrete bid levels dynamically so as to maximize the auctioneer revenue. First, we propose a non-parametric kernel method for estimating the probabilities of closing price with past auction data. Then a greedy strategy …

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Are Male And Female Avatars Perceived Equally In 3-D Virtual Worlds?, David Dewester, Fiona Fui-Hoon Nah, Sarah Gervais, Keng Siau Aug 2009

Are Male And Female Avatars Perceived Equally In 3-D Virtual Worlds?, David Dewester, Fiona Fui-Hoon Nah, Sarah Gervais, Keng Siau

Research Collection School Of Computing and Information Systems

Virtual worlds are three-dimensional, computer-generated worlds in which users take the form of avatars and use those avatars to interact with objects and other avatars in the virtual world. Virtual worlds are growing in importance in both educational institutions and businesses. Educational institutions have adopted virtual worlds as a medium for instructional delivery whereas businesses are using virtual worlds for recruitment, training, collaboration, and marketing. Given these emerging phenomena, a better understanding of behavioral and perceptual issues in virtual worlds is warranted. We propose a research model to study the interaction effects of gender stereotypicality of male and female avatars …

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3-D Virtual Worlds And Higher Education, X. Chen, Keng Siau, Fiona Fui-Hoon Nah Aug 2009

3-D Virtual Worlds And Higher Education, X. Chen, Keng Siau, Fiona Fui-Hoon Nah

Research Collection School Of Computing and Information Systems

Conducting education in three-dimensional (3-D) virtual worlds is an emerging phenomenon in the educational arena. The objective of this research is to investigate the factors influencing students’ intention to adopt the 3-D virtual worlds for delivery of education. Drawing on existing technology acceptance models as well as studies in traditional and distance education, we developed a model to study students’ acceptance of using a 3-D virtual world for education and propose to test the model empirically using survey data collected from college students. We also study the use of two instructional methods in the 3-D virtual world. This study contributes …

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Measuring Method Complexity: Uml Versus Bpmn, Jan Recker, Michael Zur Muehlen, Keng Siau, John Erickson, Marta Indulska Aug 2009

Measuring Method Complexity: Uml Versus Bpmn, Jan Recker, Michael Zur Muehlen, Keng Siau, John Erickson, Marta Indulska

Research Collection School Of Computing and Information Systems

Graphical models are used to depict relevant aspects of real-world domains intended to be supported by an information system. Various approaches for modeling exist and approaches such as object-oriented and process-oriented modeling methods are in widespread use. These modeling methods differ in their expressive power as well as in their complexity of use, thereby leading to an important investment decision for organizations seeking to conduct modeling projects. In this paper, we used an established approach for evaluating the complexity of conceptual modeling methods and compared two important industry standards for modeling, Unified Modeling Language and Business Process Modeling Notation, based …

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A Distributed Spatial Index For Error-Prone Wireless Data Broadcast, Baihua Zheng, Wang-Chien Lee, Ken C. K. Lee, Dik Lun Lee, Min Shao Aug 2009

A Distributed Spatial Index For Error-Prone Wireless Data Broadcast, Baihua Zheng, Wang-Chien Lee, Ken C. K. Lee, Dik Lun Lee, Min Shao

Research Collection School Of Computing and Information Systems

Information is valuable to users when it is available not only at the right time but also at the right place. To support efficient location-based data access in wireless data broadcast systems, a distributed spatial index (called DSI) is presented in this paper. DSI is highly efficient because it has a linear yet fully distributed structure that naturally shares links in different search paths. DSI is very resilient to the error-prone wireless communication environment because interrupted search operations based on DSI can be resumed easily. It supports search algorithms for classical location-based queries such as window queries and kNN queries …

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Evaluating Straddle Carrier Deployment Policies: A Simulation Study For The Piraeus Container Terminal, Eleni Hadjiconstantinou, Nang Laik Ma Aug 2009

Evaluating Straddle Carrier Deployment Policies: A Simulation Study For The Piraeus Container Terminal, Eleni Hadjiconstantinou, Nang Laik Ma

Research Collection School Of Computing and Information Systems

Most container terminals in the world today are operating up to their capacities. In this paper, we have developed a decision support system to optimise yard operations by considering all container flows (import, export and transshipment) through the yard with the view to improving the terminal performance and efficiency. In another paper, we proposed an optimisation model that determines optimal container locations and straddle carrier (SC) movements with the objective of minimising the overall storage and handling cost of containers. In this paper, a discrete event simulation tool for container terminal operations has been developed with three objectives: (i) to …

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On Efficient Mutual Nearest Neighbor Query Processing In Spatial Databases, Yunjun Gao, Baihua Zheng, Gencai Chen, Qing Li Aug 2009

On Efficient Mutual Nearest Neighbor Query Processing In Spatial Databases, Yunjun Gao, Baihua Zheng, Gencai Chen, Qing Li

Research Collection School Of Computing and Information Systems

This paper studies a new form of nearest neighbor queries in spatial databases, namely, mutual nearest neighbour (MNN) search. Given a set D of objects and a query object q, an MNN query returns from D, the set of objects that are among the k1 (≥ 1) nearest neighbors (NNs) of q; meanwhile, have q as one of their k2(≥ 1) NNs. Although MNN queries are useful in many applications involving decision making, data mining, and pattern recognition, it cannot be efficiently handled by existing spatial query processing approaches. In this paper, we present …

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Optimal-Location-Selection Query Processing In Spatial Databases, Yunjun Gao, Baihua Zheng, Gencai Chen, Qing Li Aug 2009

Optimal-Location-Selection Query Processing In Spatial Databases, Yunjun Gao, Baihua Zheng, Gencai Chen, Qing Li

Research Collection School Of Computing and Information Systems

This paper introduces and solves a novel type of spatial queries, namely, Optimal-Location-Selection (OLS) search, which has many applications in real life. Given a data object set D_A, a target object set D_B, a spatial region R, and a critical distance d_c in a multidimensional space, an OLS query retrieves those target objects in D_B that are outside R but have maximal optimality. Here, the optimality of a target object b \in D_B located outside R is defined as the number of the data objects from D_A that are inside R and meanwhile have their distances to b not exceeding …

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A Fair Assignment Algorithm For Multiple Preference Queries, Leong Hou U, Nikos Mamoulis, Kyriakos Mouratidis Aug 2009

A Fair Assignment Algorithm For Multiple Preference Queries, Leong Hou U, Nikos Mamoulis, Kyriakos Mouratidis

Research Collection School Of Computing and Information Systems

Consider an internship assignment system, where at the end of each academic year, interested university students search and apply for available positions, based on their preferences (e.g., nature of the job, salary, office location, etc). In a variety of facility, task or position assignment contexts, users have personal preferences expressed by different weights on the attributes of the searched objects. Although individual preference queries can be evaluated by selecting the object in the database with the highest aggregate score, in the case of multiple simultaneous requests, a single object cannot be assigned to more than one users. The challenge is …

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