1987929
Using speakeasy for ad hoc peer-to-peer collaboration
Peer-to-peer systems appear promising in terms of their ability to support ad hoc, spontaneous collaboration. However, current peer-to-peer systems suffer from several deficiencies that diminish their ability to support this domain, such as inflexibility in terms of discovery protocols, network usage, and data transports. We have developed the Speakeasy framework, which addresses these issues, and supports these types of applications. We show how Speakeasy addresses the shortcomings of current peer-to-peer systems, and describe a demonstration application, called Casca, that supports ad hoc peer-to-peer collaboration by taking advantages of the mechanisms provided by Speakeasy.
1624330
Recipes for digital living [ubiquitous computing in consumer electronics]
As networked devices become increasingly ubiquitous, the potential benefits to users increase exponentially. However, this potential can't be fully realized if it is entirely up to developers and manufacturers to expose the combined functionality buried in the expanding network. Recipes for digital living - created and modified by users themselves - offer an easy-to-understand, logically consistent way to capture and share the various ensembles possible in the expanding world of networked components.
15703762
Armi: a High Level Communication Library for Stapl
ARMI is a communication library that provides a framework for expressing fine-grain parallelism and mapping it to a particular machine using shared-memory and message passing library calls. The library is an advanced implementation of the RMI protocol and handles low-level details such as scheduling incoming communication and aggregating outgoing communication to coarsen parallelism. These details can be tuned for different platforms to allow user codes to achieve the highest performance possible without manual modification. ARMI is used by STAPL, our generic parallel library, to provide a portable, user transparent communication layer. We present the basic design as well as the mechanisms used in the current Pthreads/OpenMP, MPI implementations and/or a combination thereof. Performance comparisons between ARMI and explicit use of Pthreads or MPI are given on a variety of machines, including an HP-V2200, Origin 3800, IBM Regatta and IBM RS/6000 SP cluster.
3284353
Point-Based POMDP Algorithms: Improved Analysis and Implementation
Existing complexity bounds for point-based POMDP value iteration algorithms focus either on the curse of dimensionality or the curse of history. We derive a new bound that relies on both and uses the concept of discounted reachability; our conclusions may help guide future algorithm design. We also discuss recent improvements to our (point-based) heuristic search value iteration algorithm. Our new implementation calculates tighter initial bounds, avoids solving linear programs, and makes more effective use of sparsity.
2635609
Recent progress in local and global traversability for planetary rovers
Autonomous planetary rovers operating in vast unknown environments must operate efficiently because of size, power and computing limitations. Recently, we have developed a rover capable of efficient obstacle avoidance and path planning. The rover uses binocular stereo vision to sense potentially cluttered outdoor environments. Navigation is performed by a combination of several modules that each "vote" for the next best action for the robot to execute. The key distinction of our system is that it produces globally intelligent behavior with a small computational resource - all processing and decision making are done on a single processor. These algorithms have been tested on our outdoor prototype rover, Bullwinkle, and have recently driven the rover 100 m at a speed of 15 cm/sec. In this paper we report on the extension on the systems that we have previously developed that were necessary to achieve autonomous navigation in this domain.
12375394
The Alexandria digital earth prototype
This note summarizes the system development activities of the Alexandr ia Digital Earth Prototype (ADEPT) Project.5 ADEPT and the Alexandria Digital Library (ADL) are, respectively, the research and operational components of the Alexandria Digital Library Project. The goal of ADEPT is to build a distributed digital library (DL) of personalized collections of geospatially referenced information. This DL is characterized by: (1) services for building, searching, and using personalized collections; (2) collections of georeferenced multimedia information, including dynamic simulation models of spatially distributed processes; and (3) user interfaces employing the concept of a “Digital Earth”. Important near-term objectives for ADEPT are to build prototype collections that support undergraduate learning in physical, human, and cultural geography and related disciplines, and then to evaluate whether using such resources helps students learn to reason scientifically. Collections and services developed by ADEPT researchers will migrate to ADL as they mature.
7260476
Visual Explorations for the Alexandria Digital Earth Prototype
The Alexandria Digital Earth Prototype project addresses issues of access, browsing, delivery and understanding of georeferenced library items. Two visualization approaches that address these issues in different ways are under development: interfaces between some existing digital earth systems and the digital library, and spatial but nongeoreferenced information spaces. Both the abstract spatial and georeferenced projects are being evaluated for their educational potential in classroom and lectures, in labs and as tools for students to use on their own.