Andre Goforth

Ada as a parallel language for high performance computers: experience and results

This paper reports on experimental results which demonstrate the potential of Ada as a parallel programming language for large scale, scientific applications on high performance multiprocessors. Reported performance results show a linear speed-up of a factor of 10 over 10 processors. A linear speed-up performance over a larger number of processors is indicated given the availability of higher performance configurations and larger data sets. The results were obtained for an Ada program written to take advantage of the multiprocessing of the Sequent Balance and Symmetry computer series, which performed the classification of stars in a large infrared astronomical database, (IRAS). The classification procedure and algorithms, which were developed at NASA Ames Research Center and were originally coded in a Lisp program called AutoClassII, use an approximate Bayesian criterion. The procedure has been applied to a wide variety of classification domains besides astronomy. Through its tasking structure, Ada possesses the intrinsic ability to support parallel processing at the language level; however, much remains to be learned about the implementation of concurrent software systems in Ada on multiprocessor architectures. The paper provides a case study of the design issues faced in the attempt to exploit the inherent concurrency of the procedure and algorithms in the implementation of a portable version of AutoCIassII in Ada for benchmarking multiprocessors.

Intelligent Information Fusion in the Aviation Domain: A Semantic-Web based Approach

*, } Information fusion from multiple sources is a critical requirement for envisioned “System Wide Information Management” in the National Airspace (NAS). NASA and the FAA envision creating an “integrated pool” of information originally coming from different sources, into which users, intelligent agents and NAS decision support tools (DSS) can tap into. In this paper we present the results of our initial investigations into the requirements and prototype development of such an integrated information pool for the NAS. We have attempted to ascertain key requirements for such an integrated pool based on a survey of DSS tools that will benefit from this integrated information pool. We then advocate key technologies from computer science research areas such as the semantic web, information integration, and intelligent agents that we believe are well suited to achieving the envisioned system wide information management capabilities. I. Introduction onsider a situation where bad weather around a particular airport requires that the controllers suspend landing and take-off of any aircraft from that airport for a 2 hour period. All flights scheduled to land into or take-off from this airport in that specified period then need to be rerouted or rescheduled. Naturally this disruption causes flight delays, inconveniences air passengers, and may result in additional expenses for the airlines and the FAA. Can we deal efficiently and optimally with such situations i.e., can we do the required re-scheduling and rerouting by minimizing the flight delays and missed connections and also minimizing the additional financial costs to the airlines and authorities ? This is precisely the goal of the NASA FAA System Wide Information Management (SWIM) initiative. The SWIM initiative proposes to have various distributed information sources and services in National Airspace (NAS) connected seamlessly so that end users such as air-traffic controllers, other decision makers and decision aids such as decision support tools (DSS) or intelligent agents have integrated access to all the information needed to make informed decisions in the above kinds of situations. In this paper we present the results of our initial investigation into a critical as pect of SWIM which is the information integration issue. Seamless integrated access needs to be provided to the various distributed, heterogeneous and autonomously created and maintained information sources and services in the NAS. One of our thrusts has been to ascertain the information integration requirements in the NAS domain by talking to various potential stake-holders and familiarizing ourselves with the information access needs in the NAS. The other thrust has been to then evaluate what concepts, technologies, approaches and systems we can take from the state-of-the-art in computer science and information management research to apply to the information integration problem in the NAS. This has been with the goal of developing a prototype Aviation Information Integration and Monitoring System (AIMS) demonstrating the information access and integration capabilities. We present our findings on the above in the following sections concluding with recommendations for further activity.

Secured Advanced Federated Environment (SAFE): a NASA solution for secure cross-organization collaboration

This paper discusses the challenges and security issues inherent in building complex cross-organizational hierarchy and inter-organizational federation, the Secured Advanced Federated Environment (SAFE) is laying the foundation for a collaborative virtual infrastructure for the NASA community. A key element of SAFE is the Micro Security Domain (MSD) concept, which balances the need to collaborate and the need to enforce enterprise and local security rules. With the SAFE approach, security is an integral component of enterprise software and network design, not an afterthought.

Al, Automation And The Flight Telerobotic Servicer

NASA has recently completed a study for the preliminary definition of a teleoperated robotic device. The Flight Telerobotic Servicer (FTS) will be used to assist astronauts in many of the on-board tasks of assembly, maintenance, servicing and inspection of the Space Station. This paper makes an assessment of the role that Artificial Intelligence (AI) may have in furthering the automation capabilities of the FTS and, hence, extending the FTS capacity for growth and evolution. Relevant system engineering issues are identified, and an approach for insertion of AI technology is presented in terms of the NASA/NBS Standard Reference Model (NASREM) control architecture.

Embedded Data Processor and Portable Computer Technology testbeds

Attention is given to current activities in the Embedded Data Processor and Portable Computer Technology testbed configurations that are part of the Advanced Data Systems Architectures Testbed at the Information Sciences Division at NASA Ames Research Center. The Embedded Data Processor Testbed evaluates advanced microprocessors for potential use in mission and payload applications within the Space Station Freedom Program. The Portable Computer Technology (PCT) Testbed integrates and demonstrates advanced portable computing devices and data system architectures. The PCT Testbed uses both commercial and custom-developed devices to demonstrate the feasibility of functional expansion and networking for portable computers in flight missions.

Parallel programming in Ada: experience and results

The authors report how they used Adas features for parallel processing, the task and the rendezvous, to achieve near-linear speedup on parallel computers that hosted an Ada parallel run-time environment. In addition, they discuss the availability, performance, and productivity of Ada for the programmer familiar with single-program, multiple-data (SPMD)-style programming in parallel Fortran.<<ETX>>