Papers.

Give-to-Get: free-riding resilient video-on-demand in P2P systems

X-ray diffraction microscopy: Reconstruction with partial magnitude and spatial a priori information

The goal is to nondestructively reconstruct the structure of a fabricated integrated circuit using x-ray diffraction measurement. In particular, to detect any deviation from the specification of the circuit design. Determining phase is critical. However, additional information exists as the phase of the design specification is known. Further phase information is determined by oversampling and a better estimate of the correct phase is obtained through convex optimization. The authors illustrate this technique with a simulated one dimensional example and a simple two dimensional experimental sample.

Integrating Overlay and Social Networks for Seamless P2P Networking

Rainbow Network Flow of Multiple Description Codes

Enhanced Maintenance Services with Automatic Structuring of IT Problem Ticket Data

Reciprocal Velocity Obstacles for real-time multi-agent navigation

In this paper, we propose a new concept - the "Reciprocal Velocity Obstacle"- for real-time multi-agent navigation. We consider the case in which each agent navigates independently without explicit communication with other agents. Our formulation is an extension of the Velocity Obstacle concept [3], which was introduced for navigation among (passively) moving obstacles. Our approach takes into account the reactive behavior of the other agents by implicitly assuming that the other agents make a similar collision-avoidance reasoning. We show that this method guarantees safe and oscillation- free motions for each of the agents. We apply our concept to navigation of hundreds of agents in densely populated environments containing both static and moving obstacles, and we show that real-time and scalable performance is achieved in such challenging scenarios.

Free-Riding, Fairness, and Firewalls in P2P File-Sharing

Rainbow Network Flow with Network Coding

Near-Term Prospects for Semantic Technologies

An Online Platform for Web APIs and Service Mashups

On the newly programmable Web, mashups are flourishing. Designers create mashups by combining components of existing Web sites and applications. Although rapid mashup proliferation offers many opportunities, a lack of standarization and compatibility offers considerable challenges. IBM Sharable Code is an online service platform for developing and sharing situational Web 2.0 applications and mashups. The platform is based on an innovative domain-specific language that streamlines and standardizes the development and deployment of applications consuming and exposing Web APIs. Parts of the DSL and the resulting applications and mashups can be shared and reused by members of the IBM Sharable Code community. In this article, the authors offer an overview of the platform's architecture and the DSL language at its core.

A Web Search Analysis Considering the Intention behind Queries

Evolution of the Chilean Web: A Larger Study

Human or Automatic Answers? A User's Based Study

Hardware Objects for Java

Java, as a safe and platform independent language, avoids access to low-level I/O devices or direct memory access. In standard Java, low-level I/O it not a concern; it is handled by the operating system. However, in the embedded domain resources are scarce and a Java virtual machine (JVM) without an underlying middleware is an attractive architecture. When running the JVM on bare metal, we need access to I/O devices from Java; therefore we investigate a safe and efficient mechanism to represent I/O devices as first class Java objects, where device registers are represented by object fields. Access to those registers is safe as Java’s type system regulates it. The access is also fast as it is directly performed by the bytecodes getfield and putfield. Hardware objects thus provide an object-oriented abstraction of low-level hardware devices. As a proof of concept, we have implemented hardware objects in three quite different JVMs: in the Java processor JOP, the JIT compiler CACAO, and in the interpreting embedded JVM SimpleRTJ.

Trust evaluation in health information on the World Wide Web

Mobile Mashups: Thoughts, Directions, and Challenges

The twin mainstream computing shifts of mobility and programable Web are fundamentally impacting how humans interact, socialize, and accessinformation. Never before has computing been so disruptive and important in our daily activities. With such profound change looming what are the challengeswe still face and the challenges that we will increasingly have to deal with to make these coming changes as smooth and useful as possible?

An Algebraic Approach to Rule-Based Information Extraction

Auditing SQL Queries

Constant-Time Query Processing

Introducing Serendipity in a Content-Based Recommender System

Today recommenders are commonly used with various purposes, especially dealing with e-commerce and information filtering tools. Content-based recommenders rely on the concept of similarity between the bought/ searched/ visited item and all the items stored in a repository. It is a common belief that the user is interested in what is similar to what she has already bought/searched/visited. We believe that there are some contexts in which this assumption is wrong: it is the case of acquiring unsearched but still useful items or pieces of information. This is called serendipity. Our purpose is to stimulate users and facilitate these serendipitous encounters to happen. This paper presents the design and implementation of a hybrid recommender system that joins a content-based approach and serendipitous heuristics in order to mitigate the over-specialization problem with surprising suggestions.

Simulation of misfire and strategies for misfire recovery of gasoline HCCI

Modeling and control of a two stroke HCCI engine

Model-Independent Jets plus Missing Energy Searches

Reheating-volume measure in the landscape

I recently proposed the "reheating-volume" (RV) prescription as a possible solution to the measure problem in "multiverse" cosmology. The goal of this work is to extend the RV measure to scenarios involving bubble nucleation, such as the string theory landscape. In the spirit of the RV prescription, I propose to calculate the distribution of observable quantities in a landscape that is conditioned in probability to nucleate a finite total number of bubbles to the future of an initial bubble. A general formula for the relative number of bubbles of different types can be derived. I show that the RV measure is well-defined and independent of the choice of the initial bubble type, as long as that type supports further bubble nucleation. Applying the RV measure to a generic landscape, I find that the abundance of Boltzmann brains is always negligibly small compared with the abundance of ordinary observers in the bubbles of the same type. As an illustration, I present explicit results for a toy landscape containing four vacuum states and for landscapes with a single high-energy vacuum and a large number of low-energy vacua.

Reheating-volume measure for random-walk inflation

The recently proposed "reheating-volume" (RV) measure promises to solve the long-standing problem of extracting probabilistic predictions from cosmological "multiverse" scenarios involving eternal inflation. I give a detailed description of the new measure and its applications to generic models of eternal inflation of random-walk type. For those models I derive a general formula for RV-regulated probability distributions that is suitable for numerical computations. I show that the results of the RV cutoff in random-walk type models are always gauge-invariant and independent of the initial conditions at the beginning of inflation. In a toy model where equal-time cutoffs lead to the "youngness paradox," the RV cutoff yields unbiased results that are distinct from previously proposed measures.

A volume-weighted measure for eternal inflation

I propose a new volume-weighted probability measure for cosmological "multiverse" scenarios involving eternal inflation. The "reheating-volume (RV) cutoff" calculates the distribution of observable quantities on a portion of the reheating hypersurface that is conditioned to be finite. The RV measure is gauge-invariant, does not suffer from the "youngness paradox," and is independent of initial conditions at the beginning of inflation. In slow-roll inflationary models with a scalar inflaton, the RV-regulated probability distributions can be obtained by solving nonlinear diffusion equations. I discuss possible applications of the new measure to "landscape" scenarios with bubble nucleation. As an illustration, I compute the predictions of the RV measure in a simple toy landscape.

The anatomy of a large query graph

Computational science research in support of petascale electromagnetic modeling

Computational science research components were vital parts of the SciDAC-1 accelerator project and are continuing to play a critical role in newly-funded SciDAC-2 accelerator project, the Community Petascale Project for Accelerator Science and Simulation (ComPASS). Recent advances and achievements in the area of computational science research in support of petascale electromagnetic modeling for accelerator design analysis are presented, which include shape determination of superconducting RF cavities, mesh-based multilevel preconditioner in solving highly-indefinite linear systems, moving window using h- or p- refinement for time-domain short-range wakefield calculations, and improved scalable application I/O.

Design and optimization of large accelerator systems through high-fidelity electromagnetic simulations

SciDAC-1, with its support for the 'Advanced Computing for 21st Century Accelerator Science and Technology' project, witnessed dramatic advances in electromagnetic (EM) simulations for the design and optimization of important accelerators across the Office of Science. In SciDAC2, EM simulations continue to play an important role in the 'Community Petascale Project for Accelerator Science and Simulation' (ComPASS), through close collaborations with SciDAC Centers and Insitutes in computational science. Existing codes will be improved and new multi-physics tools will be developed to model large accelerator systems with unprecedented realism and high accuracy using computing resources at petascale. These tools aim at targeting the most challenging problems facing the ComPASS project. Supported by advances in computational science research, they have been successfully applied to the International Linear Collider and the Large Hadron Collider in high energy physics, the JLab 12-GeV Upgrade in nuclear physics, and the Spallation Neutron Source and the Linac Coherent Light Source in basic energy sciences.

Stationary Measure in the Multiverse

We study the recently proposed "stationary measure" in the context of the string landscape scenario. We show that it suffers neither from the "Boltzmann brain" problem nor from the "youngness" paradox that makes some other measures predict a high CMB temperature at present. We also demonstrate a satisfactory performance of this measure in predicting the results of local experiments, such as proton decay.

Experience versus talent shapes the structure of the Web

Efficient Sensor Placement Optimization for Securing Large Water Distribution Networks

Efficient, scalable hardware engine for Boolean satisfiability and unsatisfiable core extraction

Interoperability for Searching Learning Object Repositories: The ProLearn Query Language

FOAFing the music: Bridging the semantic gap in music recommendation

ZemPod: A semantic web approach to podcasting

A probabilistic method to determine the minimum leakage vector for combinational designs in the presence of random PVT variations

Pirates and Samaritans: A decade of measurements on peer production and their implications for net neutrality and copyright

Scala Actors: Unifying thread-based and event-based programming

Searching for Directly Decaying Gluinos at the Tevatron

An adaptive method for industrial hydrocarbon flame detection

Large calculation of the flow over a hypersonic vehicle using a GPU

Reports a large-scale computational fluid dynamics calculation of the flow over a hypersonic vehicle carried out on a graphics processing unit, demonstrating order-of-magnitude speedups over CPU implementations for compressible Navier-Stokes solvers.

EEG- and context-based cognitive-state classifications lead to improved team performance in a vehicle crew

Former Soviet Union oil production and GDP decline: Granger causality and the multi-cycle Hubbert curve

On the counter-cyclicality of prices and markups in a Cournot model of entry

Using slice join for efficient evaluation of multi-way joins.

Comparison of image similarity queries in P2P systems

Given some of the recent advances in distributed hash table (DHT) based peer-to-peer (P2P) systems we ask the following questions: are there applications where unstructured queries are still necessary (i.e., the underlying queries do not efficiently map onto any structured framework), and are there unstructured P2P systems that can deliver the high bandwidth and computing performance necessary to support such applications. Toward this end, we consider an image search application which supports queries based on image similarity metrics, such as color histogram intersection, and discuss why in this setting, standard DHT approaches are not directly applicable. We then study the feasibility of implementing such an image search system on two different unstructured P2P systems: power-law topology with percolation search, and an optimized super-node topology using structured broadcasts. We examine the average and maximum values for node bandwidth, storage and processing requirements in the percolation and super-node models, and show that current high-end computers and high-speed links have sufficient resources to enable deployments of large-scale complex image search systems

Balancing Computation and Communication Costs: The Case for Hybrid Execution in Sensor Networks

SUPNET: An end-to-end solution to scalable unstructured P2P networking

Realizing quality improvement through test driven development: results and experiences of four industrial teams