Alex Ho

A collaborative sensor grids framework

Integrating sensors and grid computing provides a way to gather, process and model real-time information from the environment for informed decision-support and timely actions, proactive or reactive, to events. We create a collaborative sensor grid framework to support the integration of a sensor grid with collaboration and other grids. The framework includes a grid builder tool for discovering and managing grid services and remote, distributed sensors. It provides a real-time collaborative client to enable distributed stakeholders to have a consistent view of displayed sensor streams. We illustrate the versatility of the framework by constructing a robot- based customizable application for shared situational awareness.

Grids for the GiG and real time simulations

We study the current architecture of the grid and Web services and that of the global information grid (GiG) with the Network Centric Operations and Warfare (NCOW) from the Department of Defense. We compare the GiG core enterprise services with those being developed for Grids (the open grid services architecture) and Web Services (so called WS-* specifications), identifying both similarities and differences. We discuss both modeling and simulation with HLA (high level architecture) and broad defense NCOW applications. We illustrate this analysis with an open geospatial community (OGC) compatible set of geographical information system grid services. We illustrate the use of grids to efficiently support realtime simulation by an application of grids to audio-video conferencing.

Measured characteristics of distributed cloud computing infrastructure for message-based collaboration applications

While the emerging cloud computing systems promise infrastructure resources to support application scalability, there are publications of systematic evaluation of this emerging information technology infrastructure in general, and no obvious publications for some representative collaboration applications in particular. We describe a methodology to study the characteristics of distributed cloud computing infrastructure for message-based collaboration applications. We report our findings of distributed cloud infrastructures in a multitude of dimensions, including performance, scalability and reliability at the network level using standard network performance tools for easy comparison of results with large quantity of literature on classic, non-cloud environments; at the message level using the NaradaBrokering system [1] by the Indiana University Community Grids Laboratory which supports a large number of practical communication protocols; and at the collaboration and communication applications level using the Anabas Impromptu, a message-based Web Conferencing system for synchronous, multipoint data collaboration, Voice-over IP communication, and Videoover IP conferencing traffics.

Learning to Plan Near-Optimal Collision-Free Paths

A new approach to find a near-optimal collision-free path is presented. The path planner is an implementation of the adaptive error back-propagation algorithm which learns to plan “good”, if not optimal, collision-free paths from human-supervised training samples. Path planning is formulated as a classification problem in which class labels are uniquely mapped onto the set of maneuverable actions of a robot or vehicle. A multi-scale representational scheme maps physical problem domains onto an arbitrarily chosen fixed size input layer of an error back-propagation network. The mapping does not only reduce the size of the computation domain, but also ensures applicability of a trained network over a wide range of problem sizes. Parallel implementation of the neural network path planner on hypercubes or Transputers based on Parasoft EXPRESS is simple and efficient, Simulation results of binary terrain navigation indicate that the planner performs effectively in unknown environment in the test cases.

MAC-CUBE, the Macintosh-based hypercube

The MAC-CUBE is a Macintosh-based hypercube. It uses AppleTalk hardware and software as the medium for the nodal connections. At the physical level AppleTalk has a bus topology. Hypercube connectivity is emulated on the AppleTalk local area network while the hypercube communication protocol is integrated in the AppleTalk software. Available for MAC-CUBE is the Crystalline Operating System III (CrOS III.) MAC-CUBE provides a programming environment similar to any other hypercube systems running CrOS III. It allows inexpensive hands-on experience with a concurrent machine. Data can be displayed on graphics monitor and/or stored locally at each node. In addition to the low cost, these capabilities of the Mac-Cube makes it an indispensable instructional and development tool for parallel processing. Some application programs which are taken from the book Solving Problems on Concurrent Processors [Fox 88] have been implemented with graphics enhancement on Mac-Cube. The applications are solving the Mandelbrot set in the complex plane, and solving a 2-dimensional Laplace equation using finite difference.

PC-CUBE, a personal computer based hypercube

PC-CUBE is an ensemble of IBM PCs or close compatibles connected in the hypercube topology with ordinary computer cables. Communication occurs at the rate of 115.2 K-baud via the RS-232 serial links. Available for PC-CUBE is the Crystalline Operating System III (CrOS III), Mercury Operating System, CUBIX and PLOTIX which are parallel I/O and graphics libraries. A CrOS performance monitor was developed to facilitate the measurement of communication and computation time of a program and their effects on performance. Also available are CXLISP, a parallel version of the XLISP interpreter; GRAFIX, some graphics routines for the EGA and CGA; and a general execution profiler for determining execution time spent by program subroutines. PC-CUBE provides a programming environment similar to all hypercube systems running CrOS III, Mercury and Cubix. In addition, every node (personal computer) has its own graphics display monitor and storage devices. These allow data to be displayed or stored at every processor, which has much instructional value and enables easier debugging of applications. Some application programs which are taken from the book Solving Problems on Concurrent Processors [Fox 88] were implemented with graphics enhancement on PC-CUBE. The applications range from solving the Mandelbrot set, Laplace equation, wave equation, long range force interaction, to Wa-Tor, an ecological simulation.

Portable Asteroids on Hypercube Or Transputers

A multi-player 3D Asteroids video game designed to be used as a testbed for evaluating controller algorithms was described in [l.] The original version of the game and a separate interactive 3D graphics interface for a human player were implemented, based on CrOS III and VERTEX, on an NCUBE-l hypercube equipped with a parallel Real-Time Graphics board. The Asteroids and interactive graphics interface programs are examples of parallel programs which communicate with each other in a space-shared multi-processor environment. We have successfully ported the Asteroids and the interactive graphics interface to run on NCUBE using ParaSoft EXPRESS. The new version of these programs were further ported to run on a SUN 386i with an add-on Transputer board. We present general design considerations that enable easy migration of communicating parallel programs to any other hardware platform that runs EXPRESS. We also report specific experience of porting Asteroids and an associated interactive player interface program on an NCUBE hypercube to a SUN 386i Transputer-based system, with no modification of codes.