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Articles 1 - 12 of 12
Full-Text Articles in Physical Sciences and Mathematics
Adaptive Fec-Based Error Control For Interactive Audio In The Internet, Jean Bolot
Adaptive Fec-Based Error Control For Interactive Audio In The Internet, Jean Bolot
Computer Science Department Faculty Publication Series
Excessive packet loss rates can dramatically decrease the audio quality perceived by users of Internet telephony applications. Recent results suggest that error control schemes using forward error correction (FEC) are good candidates for decreasing the impact of packet loss on audio quality. With FEC schemes, redundant information is transmitted along with the original information so that the lost original data can be recovered at least in part from the redundant information. Clearly, sending additional redundancy increases the probability of recovering lost packets, but it also increases the bandwidth requirements and thus the loss rate of the audio stream. This means …
Maintaining Temporal Coherency Of Virtual Datawarehouses, Raghav Srinivasan
Maintaining Temporal Coherency Of Virtual Datawarehouses, Raghav Srinivasan
Computer Science Department Faculty Publication Series
In Electronic Commerce applications such as stock trading, there is a need to consult sources available on the web for informed decision making. Because information such as stock prices keep changing, the web sourcesmust be queried continually to maintain temporal coherency of the collected data, thereby avoiding decisions based on stale information. However, because network infrastructure has failed to keep pace with ever growing web traffic, the frequency of contacting web servers must be kept to a minimum. This paper presents adaptive approaches for the maintenance of temporal coherency of data gathered from web sources. Specifically, it introduces mechanisms to …
Type-Based Alias Analysis, Amer Diwan, Kathryn S. Mckinley, J. Eliot B. Moss
Type-Based Alias Analysis, Amer Diwan, Kathryn S. Mckinley, J. Eliot B. Moss
Computer Science Department Faculty Publication Series
This paper evaluates three alias analyses based on programming language types. The first analysis uses type compatibility to determine aliases. The second extends the first by using additional high-level information such as field names. The third extends the second with a flow-insensitive analysis. Although other researchers suggests using types to disambiguate memory references, none evaluates its effectiveness. We perform both static and dynamic evaluations of type-based alias analyses for Modula-3, a statically-typed type-safe language. The static analysis reveals that type compatibility alone yields a very imprecise alias analysis, but the other two analyses significantly improve alias precision. We use redundant …
A Control Architecture Formulti-Modal Sensory Integration, Luiz M. G. Gonçalves, Roderic A. Grupen, Antonio A. F. Oliveira
A Control Architecture Formulti-Modal Sensory Integration, Luiz M. G. Gonçalves, Roderic A. Grupen, Antonio A. F. Oliveira
Computer Science Department Faculty Publication Series
This work describes the architecture of an integrated multi-modal sensory (vision and touch) computational system. We propose to use an approach based on robotics control theory that is motivated by biology and developmental psychology, in order to integrate the haptic and visual information processing. We show some results carried out in simulation and discuss the implementation of this system using a platform consisting on an articulated stereo-head and an arm, which is currently under development.
Between Mdps And Semi-Mdps:Learning, Planning, And Representing Knowledge At Multiple Temporal Scales, Richard S. Sutton
Between Mdps And Semi-Mdps:Learning, Planning, And Representing Knowledge At Multiple Temporal Scales, Richard S. Sutton
Computer Science Department Faculty Publication Series
Learning, planning, and representing knowledge at multiple levels of temporal abstraction are key challenges for AI. In this paper we develop an approach to these problems based on the mathematical framework of reinforcement learning and Markov decisions processes (MDPs). We extend the usual notion of action to include options--whole courses of behavior that may be temporally extended, stochastic, and contingent on events.
On Computing Global Similarity In Images, S. Ravela
On Computing Global Similarity In Images, S. Ravela
Computer Science Department Faculty Publication Series
The retrieval of images based on their visual similarity to an example image is an important and fascinating area of research. Here, a method to characterize visual appearance for determining global similarity in images is described. Images are filtered with Gaussian derivatives and geometric features are computed from the filtered images. The geometric features used here are curvature and phase. Two images may be said to be similar if they have similar distributions of such features. Global similarity may, therefore, be deduced by comparing histograms of these features. This allows for rapid retrieval and examples from collection of gray-level and …
Macro-Actions In Reinforcement Learning: An Empirical Analysis, Amy Mcgovern, Richard S. Sutton
Macro-Actions In Reinforcement Learning: An Empirical Analysis, Amy Mcgovern, Richard S. Sutton
Computer Science Department Faculty Publication Series
Several researchers have proposed reinforcement learning methods that obtain advantages in learning by using temporally extended actions, or macro-actions, but none has carefully analyzed what these advantages are. In this paper, we separate and analyze two advantages of using macro-actions in reinforcement learning: the effect on exploratory behavior, independent of learning, and the effect on the speed with which the learning process propagates accurate value information. We empirically measure the separate contributions of these two effects in gridworld and simulated robotic environments. In these environments, both effects were significant, but the effect of value propagation was larger. We also compare …
Exploiting Relational Structure To Understand Publication Patterns In High-Energy, Amy Mcgovern, Lisa Friedland, Michael Hay, Brian Gallagher, Andrew Fast, Jennifer Neville, David Jensen
Exploiting Relational Structure To Understand Publication Patterns In High-Energy, Amy Mcgovern, Lisa Friedland, Michael Hay, Brian Gallagher, Andrew Fast, Jennifer Neville, David Jensen
Computer Science Department Faculty Publication Series
We analyze publication patterns in theoretical high-energy physics using a relational learning approach. We focus on four related areas: understanding and identifying patterns of citations, examining publication patterns at the author level, predicting whether a paper will be accepted by specific journals, and identifying research communities from the citation patterns and paper text. Each of these analyses contributes to an overall understanding of theoretical highenergy physics.
Real-Time Reliable Multicast Using Proactive Forward Error Correction, Dan Rubenstein
Real-Time Reliable Multicast Using Proactive Forward Error Correction, Dan Rubenstein
Computer Science Department Faculty Publication Series
Real-Time reliable multicast over a best-effort service network remains a challenging research problem. Most protocols for reliable multicast use repair techniques that result in significant and variable delay, which can lead to missed deadlines in real-time scenarios. In this paper we present a repair technique that combines forward error correction (FEC) with automatic repeat request (ARQ). The novel aspect of the technique is its ability to reduce delay in reliable multicast delivery by sending repairs proactively (i.e., before they are required). The technique requires minimal state at senders and receivers, and no additional active router functionality beyond what is required …
Afs And Hac: Domain-General Agent Simulation And Control, Marc S. Atkin, David L. Westbrook, Paul R. Cohen, Gregory D. Jorstad
Afs And Hac: Domain-General Agent Simulation And Control, Marc S. Atkin, David L. Westbrook, Paul R. Cohen, Gregory D. Jorstad
Computer Science Department Faculty Publication Series
We present two systems for simulating and designing agents, respectively. The first, the Abstract Force Simulator (AFS), is a domain-general simulator of agents applying forces; many domains can be characterized in this way. The second, Hierarchical Agent Control (HAC), is a general toolkit for designing an action hierarchy. It supports action abstraction, a multi-level computational architecture, sensor integration, and planning. It is particularly well suited to controlling large numbers of agents in dynamic environments. Together, AFS and HAC provide a very general framework for designing and testing agents.
Maps For Verbs, Paul Cohen
Maps For Verbs, Paul Cohen
Computer Science Department Faculty Publication Series
This paper describes a representation of the meanings of verbs based on the dynamics of interactions between two agents or objects. The representation treats interactions as having three phases, before, during and after contact. Maps for these phases are constructed. Trajectories through these maps correspond to different types of interactions and are denoted by different verbs. We summarize the results of experiments on learning and reasoning with maps.
Feature Detection And Identification Using A Sonar-Array, E. G. Araujo
Feature Detection And Identification Using A Sonar-Array, E. G. Araujo
Computer Science Department Faculty Publication Series
This work explores techniques for sonar sensor fusion in the context of environmental feature detection and identification for navigation tasks. By detecting common features in indoor environments and using them as landmarks, a robot can navigate reliably, recovering its pose when necessary. Preliminary results on a multiple hypothesis testing procedure for feature localization and identification show that accurate feature information can be acquired with adequate sonar models and configurations. In addition, a method that associates sonar configuration with the precision of feature extraction is discussed, as well as its utility for guiding an active sonar sensor.