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Computer Science Technical Reports

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Articles 301 - 330 of 772

Full-Text Articles in Computer Sciences

Tr-2004010: Optimal Reversible Quantum Circuit For Multiplication, Anh Quoc Nguyen Jan 2004

Tr-2004010: Optimal Reversible Quantum Circuit For Multiplication, Anh Quoc Nguyen

Computer Science Technical Reports

No abstract provided.


Tr-2004011: Logic Of Knowledge With Justifications From The Provability Perspective, Sergei Artemov, Elena Nogina Jan 2004

Tr-2004011: Logic Of Knowledge With Justifications From The Provability Perspective, Sergei Artemov, Elena Nogina

Computer Science Technical Reports

No abstract provided.


Tr-2004012: Single-Hop Probing Asymptotics In Available Bandwidth Estimation: Sample-Path Analysis, Xiliang Liu, Kaliappa Ravindran, Benyuan Liu, Dmitri Loguinov Jan 2004

Tr-2004012: Single-Hop Probing Asymptotics In Available Bandwidth Estimation: Sample-Path Analysis, Xiliang Liu, Kaliappa Ravindran, Benyuan Liu, Dmitri Loguinov

Computer Science Technical Reports

No abstract provided.


Tr-2004014: A Homotopic/Factorization Process For Toeplitz-Like Matrices With Newton's/Conjugate Gradient Stages, Victor Y. Pan Jan 2004

Tr-2004014: A Homotopic/Factorization Process For Toeplitz-Like Matrices With Newton's/Conjugate Gradient Stages, Victor Y. Pan

Computer Science Technical Reports

No abstract provided.


Tr-2004017: Towards A Formal Concept Analysis Approach To Exploring Communities On The World Wide Web, Jayson E. Rome, Robert M. Haralick Jan 2004

Tr-2004017: Towards A Formal Concept Analysis Approach To Exploring Communities On The World Wide Web, Jayson E. Rome, Robert M. Haralick

Computer Science Technical Reports

No abstract provided.


Tr-2004018: Evidence-Based Common Knowledge, Sergei Artemov Jan 2004

Tr-2004018: Evidence-Based Common Knowledge, Sergei Artemov

Computer Science Technical Reports

No abstract provided.


Tr-2004019: Quantified Lp, Melvin Fitting Jan 2004

Tr-2004019: Quantified Lp, Melvin Fitting

Computer Science Technical Reports

No abstract provided.


Tr-2004002: Oopn: An Object-Oriented Petri Nets And Its Integrated Development Environment, Jinzhong Niu, Jing Zou, Aihua Ren Jan 2004

Tr-2004002: Oopn: An Object-Oriented Petri Nets And Its Integrated Development Environment, Jinzhong Niu, Jing Zou, Aihua Ren

Computer Science Technical Reports

No abstract provided.


Tr-2004005: A Parallel Monte Carlo Simulation Of Five-Dimensional Hyperspheres Using A Webcomputing Framework, P. A. Whitlock, Marvin Bishop, Dino Klein Jan 2004

Tr-2004005: A Parallel Monte Carlo Simulation Of Five-Dimensional Hyperspheres Using A Webcomputing Framework, P. A. Whitlock, Marvin Bishop, Dino Klein

Computer Science Technical Reports

No abstract provided.


Tr-2004008: Simultaneous Fuzzy Segmentation Of Multiple Objects, Bruno M. Carvalho, Gabor T. Herman, T. Yung Kong Jan 2004

Tr-2004008: Simultaneous Fuzzy Segmentation Of Multiple Objects, Bruno M. Carvalho, Gabor T. Herman, T. Yung Kong

Computer Science Technical Reports

No abstract provided.


Tr-2004009: A Reduction Of The Matrix Eigenproblem To Polynomial Rootfinding Via Similarity Transforms Into Arrow-Head Matrices, Victor Y. Pan Jan 2004

Tr-2004009: A Reduction Of The Matrix Eigenproblem To Polynomial Rootfinding Via Similarity Transforms Into Arrow-Head Matrices, Victor Y. Pan

Computer Science Technical Reports

No abstract provided.


Tr-2004013: Toeplitz And Hankel Meet Hensel And Newton: Nearly Optimal Algorithms And Their Practical Acceleration With Saturated Initialization, Victor Y. Pan, Brian Murphy, Rhys E. Rosholt, Xinmao Wang Jan 2004

Tr-2004013: Toeplitz And Hankel Meet Hensel And Newton: Nearly Optimal Algorithms And Their Practical Acceleration With Saturated Initialization, Victor Y. Pan, Brian Murphy, Rhys E. Rosholt, Xinmao Wang

Computer Science Technical Reports

No abstract provided.


Tr-2004015: Superfast Algorithms For Singular Toeplitz-Like Matrices, Victor Y. Pan Jan 2004

Tr-2004015: Superfast Algorithms For Singular Toeplitz-Like Matrices, Victor Y. Pan

Computer Science Technical Reports

No abstract provided.


Tr-2004016: Semantics And Tableaus For Lps4, Melvin Fitting Jan 2004

Tr-2004016: Semantics And Tableaus For Lps4, Melvin Fitting

Computer Science Technical Reports

No abstract provided.


Using Spki/Sdsi For Distributed Maintenance Of Attribute Release Policies In Shibboleth, Sidharth Nazareth, Sean W. Smith Jan 2004

Using Spki/Sdsi For Distributed Maintenance Of Attribute Release Policies In Shibboleth, Sidharth Nazareth, Sean W. Smith

Computer Science Technical Reports

The Shibboleth middleware from Internet2 provides a way for users at higher-education institutions to access remote electronic content in compliance with the inter-institutional license agreements that govern such access. To protect end-user privacy, Shibboleth permits users to construct attribute release policies that control what user credentials a given content provider can obtain. However, Shibboleth leaves unspecified how to construct these policies. To be effective, a solution needs to accommodate the typical nature of a university: a set of decentralized fiefdoms. This need argues for a public-key infrastructure (PKI) approach---since public-key cryptography does not require parties to agree on a secret …


Experimenting With Tcpa/Tcg Hardware, Or: How I Learned To Stop Worrying And Love The Bear, John Marchesini, Sean Smith, Omen Wild, Rich Macdonald Dec 2003

Experimenting With Tcpa/Tcg Hardware, Or: How I Learned To Stop Worrying And Love The Bear, John Marchesini, Sean Smith, Omen Wild, Rich Macdonald

Computer Science Technical Reports

Over the last few years, our group has been working on applications of secure coprocessors---but has been frustrated by the limited computational environment and high expense of such devices. Over the last few years, the TCPA (now TCG) has produced a specification for a trusted platform module (TPM)---a small hardware addition intended to improve the overall security of a larger machine (and tied up with a still-murky vision of Windows-based trusted computing). Some commodity desktops now come up with these TPMs. Consequently, we began an experiment to see if (in the absence of a Non-Disclosure Agreement) we could use this …


A Subgroup Algorithm To Identify Cross-Rotation Peaks Consistent With Non-Crystallographic Symmetry, Ryan H. Lilien, Chris Bailey-Kellogg, Amy C. Anderson, Bruce R. Donald Dec 2003

A Subgroup Algorithm To Identify Cross-Rotation Peaks Consistent With Non-Crystallographic Symmetry, Ryan H. Lilien, Chris Bailey-Kellogg, Amy C. Anderson, Bruce R. Donald

Computer Science Technical Reports

Molecular replacement (MR) often plays a prominent role in determining initial phase angles for structure determination by X-ray crystallography. In this paper, an efficient quaternion-based algorithm is presented for analyzing peaks from a cross-rotation function to identify model orientations consistent with non-crystallographic symmetry (NCS), and to generate NCS-consistent orientations missing from the list of cross-rotation peaks. Our algorithm, CRANS, analyzes the rotation differences between each pair of cross-rotation peaks to identify finite subgroups of NCS. Sets of rotation differences satisfying the subgroup axioms correspond to orientations compatible with the correct NCS. The CRANS algorithm was first tested using cross-rotation peaks …


A Probability-Based Similarity Measure For Saupe Alignment Tensors With Applications To Residual Dipolar Couplings In Nmr Structural Biology, Anthony K. Yan, Christopher J. Langmead, Bruce Randall Donald Oct 2003

A Probability-Based Similarity Measure For Saupe Alignment Tensors With Applications To Residual Dipolar Couplings In Nmr Structural Biology, Anthony K. Yan, Christopher J. Langmead, Bruce Randall Donald

Computer Science Technical Reports

High-throughput NMR structural biology and NMR structural genomics pose a fascinating set of geometric challenges. A key bottleneck in NMR structural biology is the resonance assignment problem. We seek to accelerate protein NMR resonance assignment and structure determination by exploiting a priori structural information. In particular, a method known as Nuclear Vector Replacement (NVR) has been proposed as a method for solving the assignment problem given a priori structural information [24,25]. Among several different kinds of input data, NVR uses a particular type of NMR data known as residual dipolar couplings (RDCs). The basic physics of residual dipolar couplings tells …


High-Throughput 3d Homology Detection Via Nmr Resonance Assignment, Christopher James Langmead, Bruce Randall Donald Sep 2003

High-Throughput 3d Homology Detection Via Nmr Resonance Assignment, Christopher James Langmead, Bruce Randall Donald

Computer Science Technical Reports

One goal of the structural genomics initiative is the identification of new protein folds. Sequence-based structural homology prediction methods are an important means for prioritizing unknown proteins for structure determination. However, an important challenge remains: two highly dissimilar sequences can have similar folds --- how can we detect this rapidly, in the context of structural genomics? High-throughput NMR experiments, coupled with novel algorithms for data analysis, can address this challenge. We report an automated procedure, called HD, for detecting 3D structural homologies from sparse, unassigned protein NMR data. Our method identifies 3D models in a protein structural database whose geometries …


An Improved Nuclear Vector Replacement Algorithm For Nuclear Magnetic Resonance Assignment, Christopher James Langmead, Bruce Randall Donald Sep 2003

An Improved Nuclear Vector Replacement Algorithm For Nuclear Magnetic Resonance Assignment, Christopher James Langmead, Bruce Randall Donald

Computer Science Technical Reports

We report an improvement to the Nuclear Vector Replacement (NVR) algorithm for high-throughput Nuclear Magnetic Resonance (NMR) resonance assignment. The new algorithm improves upon our earlier result in terms of accuracy and computational complexity. In particular, the new NVR algorithm assigns backbone resonances without error (100% accuracy) on the same test suite examined in [Langmead and Donald J. Biomol. NMR 2004], and runs in $O(n^{5/2} \log {(cn)})$ time where $n$ is the number of amino acids in the primary sequence of the protein, and $c$ is the maximum edge weight in an integer-weighted bipartite graph.


Bear: An Open-Source Virtual Secure Coprocessor Based On Tcpa, Rich Macdonald, Sean Smith, John Marchesini, Omen Wild Aug 2003

Bear: An Open-Source Virtual Secure Coprocessor Based On Tcpa, Rich Macdonald, Sean Smith, John Marchesini, Omen Wild

Computer Science Technical Reports

This paper reports on our ongoing project to use TCPA to transform a desktop Linux machine into a virtual secure coprocessor: more powerful but less secure than higher-end devices. We use TCPA hardware and modified boot loaders to protect fairly static components, such as a trusted kernel; we use an enforcer module---configured as Linux Security Module---to protected more dynamic system components; we use an encrypted loopback filesystem to protect highly dynamic components. All our code is open source and available under GPL from http://enforcer.sourceforge.net/


Formal Properties Of Linear Memory Types, Heng Huang, Lea Wittie, Chris Hawblitzel Aug 2003

Formal Properties Of Linear Memory Types, Heng Huang, Lea Wittie, Chris Hawblitzel

Computer Science Technical Reports

Efficient low-level systems need more control over memory than safe high-level languages usually provide. As a result, run-time systems are typically written in unsafe languages such as C. This report describes an abstract machine designed to give type-safe code more control over memory. It includes complete definitions and proofs of preservation, progress, strong normalization, erasure, and translation correctness.


Using Caching For Browsing Anonymity, Anna M. Shubina, Sean W. Smith Jul 2003

Using Caching For Browsing Anonymity, Anna M. Shubina, Sean W. Smith

Computer Science Technical Reports

Privacy-providing tools, including tools that provide anonymity, are gaining popularity in the modern world. Among the goals of their users is avoiding tracking and profiling. While some businesses are unhappy with the growth of privacy-enhancing technologies, others can use lack of information about their users to avoid unnecessary liability and even possible harassment by parties with contrary business interests, and to gain a competitive market edge. Currently, users interested in anonymous browsing have the choice only between single-hop proxies and the few more complex systems that are available. These still leave the user vulnerable to long-term intersection attacks. In this …


The Mistaken Axioms Of Wireless-Network Research, David Kotz, Calvin Newport, Chip Elliott Jul 2003

The Mistaken Axioms Of Wireless-Network Research, David Kotz, Calvin Newport, Chip Elliott

Computer Science Technical Reports

Most research on ad-hoc wireless networks makes simplifying assumptions about radio propagation. The ``Flat Earth'' model of the world is surprisingly popular: all radios have circular range, have perfect coverage in that range, and travel on a two-dimensional plane. CMU's ns-2 radio models are better but still fail to represent many aspects of realistic radio networks, including hills, obstacles, link asymmetries, and unpredictable fading. We briefly argue that key ``axioms'' of these types of propagation models lead to simulation results that do not adequately reflect real behavior of ad-hoc networks, and hence to network protocols that may not work well …


Discrete-Event Fluid Modeling Of Background Tcp Traffic, David M. Nicol, Guanhua Yan Jun 2003

Discrete-Event Fluid Modeling Of Background Tcp Traffic, David M. Nicol, Guanhua Yan

Computer Science Technical Reports

TCP is the most widely used transport layer protocol used in the internet today. A TCP session adapts the demands it places on the network to observations of bandwidth availability on the network. Because TCP is adaptive, any model of its behavior that aspires to be accurate must be influenced by other network traffic. This point is especially important in the context of using simulation to evaluate some new network algorithm of interest (e.g. reliable multi-cast) in an environment where the background traffic affects---and is affected by---its behavior. We need to generate background traffic efficiently in a way that captures …


Distributed Planning And Control For Modular Robots With Unit-Compressible Modules, Zack Butler, Daniela Rus Jun 2003

Distributed Planning And Control For Modular Robots With Unit-Compressible Modules, Zack Butler, Daniela Rus

Computer Science Technical Reports

Self-reconfigurable robots are versatile systems consisting of large numbers of independent modules. Effective use of these systems requires parallel actuation and planning, both for efficiency and independence from a central controller. This paper presents the PacMan algorithm, a technique for distributed actuation and planning for systems with two- or three-dimensional unit-compressible modules. We give two versions of the algorithm along with correctness analysis. We also analyze the parallel actuation capability of the algorithm, showing that it will not deadlock and will avoid disconnecting the robot. We have implemented PacMan on the Crystal robot, a hardware system developed in our lab, …


A Surface-Based Approach For Classification Of 3d Neuroanatomic Structures, Li Shen, James Ford, Fillia Makedon, Andrew Saykin Jun 2003

A Surface-Based Approach For Classification Of 3d Neuroanatomic Structures, Li Shen, James Ford, Fillia Makedon, Andrew Saykin

Computer Science Technical Reports

We present a new framework for 3D surface object classification that combines a powerful shape description method with suitable pattern classification techniques. Spherical harmonic parameterization and normalization techniques are used to describe a surface shape and derive a dual high dimensional landmark representation. A point distribution model is applied to reduce the dimensionality. Fisher's linear discriminants and support vector machines are used for classification. Several feature selection schemes are proposed for learning better classifiers. After showing the effectiveness of this framework using simulated shape data, we apply it to real hippocampal data in schizophrenia and perform extensive experimental studies by …


Digital Art Forensics, Siwei Lyu, Daniel Rockmore, Hany Farid Jun 2003

Digital Art Forensics, Siwei Lyu, Daniel Rockmore, Hany Farid

Computer Science Technical Reports

We describe a computational technique for digitally authenticating works of art. This approach builds statistical models of an artist from a set of authenticated works. Additional works are then authenticated against this model. The statistical model consists of first- and higher-order wavelet statistics. We show preliminary results from our analysis of thirteen drawings by Pieter Bruegel the Elder. We also present preliminary results showing how these techniques may be applicable to determining how many hands contributed to a single painting.


Efficient And Practical Constructions Of Ll/Sc Variables, Prasad Jayanti, Srdjan Petrovic Jun 2003

Efficient And Practical Constructions Of Ll/Sc Variables, Prasad Jayanti, Srdjan Petrovic

Computer Science Technical Reports

Over the past decade, LL/SC have emerged as the most suitable synchronization instructions for the design of lock-free algorithms. However, current architectures do not support these instructions; instead, they support either CAS or RLL/RSC (e.g. POWER4, MIPS, SPARC, IA-64). To bridge this gap, this paper presents two efficient wait-free algorithms for implementing 64-bit LL/SC objects from 64-bit CAS or RLL/RSC objects. Our first algorithm is practical: it has a small, constant time complexity (of 4 for LL and 5 for SC) and a space overhead of only 4 words per process. This algorithm uses unbounded sequence numbers. For theoretical interest, …


Efficient Security For Bgp Route Announcements, David M. Nicol, Sean W. Smith, Meiyuan Zhao May 2003

Efficient Security For Bgp Route Announcements, David M. Nicol, Sean W. Smith, Meiyuan Zhao

Computer Science Technical Reports

The Border Gateway Protocol (BGP) determines how Internet traffic is routed throughout the entire world; malicious behavior by one or more BGP speakers could create serious security issues. Since the protocol depends on a speaker honestly reporting path information sent by previous speakers and involves a large number of independent speakers, the Secure BGP (S-BGP) approach uses public-key cryptography to ensure that a malicious speaker cannot fabricate this information. However, such public-key cryptography is expensive: S-BGP requires a digital signature operation on each announcement sent to each peer, and a linear (in the length of the path) number of verifications …