George Dimitoglou

JHelioviewer: Visualizing Large Sets of Solar Images Using JPEG 2000

All disciplines that work with image data-from astrophysics to medical research and historic preservation-increasingly require efficient ways to browse and inspect large sets of high-resolution images. Based on the JPEG 2000 image-compression standard, the JHelioviewer solar image visualization tool lets users browse petabyte-scale image archives as well as locate and manipulate specific data sets.

From Simulation to Real Robots with Predictable Results: Methods and Examples

From a theoretical perspective, one may easily argue (as we will in this chapter) that simulation accelerates the algorithm development cycle. However, in practice many in the robotics development community share the sentiment that “Simulation is doomed to succeed” (Brooks, R., Mataric, M., Robot Learning, Kluwer Academic Press, Hingham, MA, 1993, p. 209). This comes in large part from the fact that many simulation systems are brittle; they do a fair-to-good job of simulating the expected, and fail to simulate the unexpected. It is the authors’ belief that a simulation system is only as good as its models, and that deficiencies in these models lead to the majority of these failures. This chapter will attempt to address these deficiencies by presenting a systematic methodology with examples for the development of both simulated mobility models and sensor models for use with one of today’s leading simulation engines. Techniques for using simulation for algorithm development leading to real-robot implementation will be presented, as well as opportunities for involvement in international robotics competitions based on these techniques.

The Virtual Solar Observatory: status and initial operational experience

The Virtual Solar Observatory (VSO) is a bottom-up grassroots approach to the development of a distributed data system for use by the solar physics community. The beta testing version of the VSO was released in December 2003. Since then it has been tested by approximately 50 solar physicists. In this paper we will present the status of the project, a summary of the communitys experience with the tool, and an overview of the lessons learned.

An efficient prefetching strategy for remote browsing of JPEG 2000 image sequences

This paper proposes an efficient prefetching strategy for interactive remote browsing of sequences of high resolution JPEG 2000 images. As a result of the inherent latency of client-server communication, the experiments of this study prove that a significant benefit, can be achieved, in terms of both quality and responsiveness, by anticipating certain data from the rest of the sequence while an image is being explored. This paper proposes a model based on the quality progression of the image in order to estimate which percentage of the bandwidth is dedicated to prefetch data. This solution can be easily implemented over any existing remote browsing architecture.

Deadlocks and methods for their detection, prevention and recovery in modern operating systems

%haring and allocating system resources between running and new processes is an operating system task. In a multiprocessing environment, allocation of resources can become a point of conflict. Such conflict may lead the system into a state known as deadlock. The scope of the topic is to identify the conditions for deadlocks, distinguish the different circumstances that lead to this undesirable state, and identify the methods for detection, prevention, and recovery.

A gaming approach for ad-hoc secure routing in education

The general nature of ad hoc routing lends itself to be insecure since all the nodes in the network must rely on their peers for success. The existing DARS routing simulator currently only takes into account a perfect routing simulation environment. All the nodes in the network work cooperatively and there are no malicious nodes to cause degradation to the network infrastructure. This project aims to add those elements of security vulnerabilities to paint a better picture of what ad hoc networks face in a real world environment. The second goal of this project is to add gaming concepts to the simulator to privide a learning experience for computer science students.

Algorithms and performance analysis for path navigation of Ackerman-steered autonomous robots

Autonomous robot navigation is one of the most important areas of robotics research. While waypoint-based navigation is well understood, particular design characteristics (e.g. steering mechanisms) of a robotic platform may render general navigation approaches inaccurate or ineffectual. In this paper, we develop a novel, deliberative-planning, waypoint-based robot navigation algorithm that allows accurate path following for Ackerman-steered vehicles. The algorithm is validated via simulation. Collected performance data provide insight on the relation of the algorithm to other mobility factors such as velocity.

Analysis of a novel docking technique for autonomous robots

Autonomous robot docking requires accurate path following and ultimately, accurate alignment with the target location, typically a docking station. In this paper we develop a novel, partially heuristic, technique that allows accurate docking for Ackerman-steered vehicles. The technique is validated via simulation. Multiple experiments were performed to better understand and analyze the heuristic element of the technique. The results underscore the impact of the vehicles steering characteristics in docking precision and may prove valuable in attempting to remove the heuristic element.

A System for Association Rule Discovery in Emergency Response Data

Association rule mining is used to find association relationships in data. Our work describes the use of association rule discovery as a basis for creating an early warning bio-terror attack system. The system establishes a baseline of “normal” behavior by mining historical emergency response (911) data. Using probabilistic models, we generate spatial and temporal statistics to correlate incident frequency and location in order to identify if a variation in future incidents carries an outbreak signature consistent with the effects of a biological warfare attack. Using three years of real emergency response data for experimentation, this work is focused on the activities relating to the processing and generation of detection rules. Preliminary results indicate that the system can provide reasonable detection rules but there is also more work to address inherent issues of both emergency response and biological warfare such as data quality during incident reporting and population mobility as it relates to outbreaks.