Reduction of connections for multibus organization

The multibus interconnection network is an attractive solution for connecting processors and memory modules in a multiprocessor with shared memory. It provides a throughput which is intermediate between the single bus and the crossbar, with a corresponding intermediate cost.Postprint (published version

A real-time simulator of a turbofan engine

A real-time digital simulator of a Pratt and Whitney F100 engine has been developed for real-time code verification and for actuator diagnosis during full-scale engine testing. This self-contained unit can operate in an open-loop stand-alone mode or as part of closed-loop control system. It can also be used for control system design and development. Tests conducted in conjunction with the NASA Advanced Detection, Isolation, and Accommodation program show that the simulator is a valuable tool for real-time code verification and as a real-time actuator simulator for actuator fault diagnosis. Although currently a small perturbation model, advances in microprocessor hardware should allow the simulator to evolve into a real-time, full-envelope, full engine simulation

Space Station Freedom data management system growth and evolution report

The Information Sciences Division at the NASA Ames Research Center has completed a 6-month study of portions of the Space Station Freedom Data Management System (DMS). This study looked at the present capabilities and future growth potential of the DMS, and the results are documented in this report. Issues have been raised that were discussed with the appropriate Johnson Space Center (JSC) management and Work Package-2 contractor organizations. Areas requiring additional study have been identified and suggestions for long-term upgrades have been proposed. This activity has allowed the Ames personnel to develop a rapport with the JSC civil service and contractor teams that does permit an independent check and balance technique for the DMS

Graphs, Friends and Acquaintances

As is well known, a graph is a mathematical object modeling the existence of a certain relation between pairs of elements of a given set. Therefore, it is not surprising that many of the first results concerning graphs made reference to relationships between people or groups of people. In this article, we comment on four results of this kind, which are related to various general theories on graphs and their applications: the Handshake lemma (related to graph colorings and Boolean algebra), a lemma on known and unknown people at a cocktail party (to Ramsey theory), a theorem on friends in common (to distanceregularity and coding theory), and Hall’s Marriage theorem (to the theory of networks). These four areas of graph theory, often with problems which are easy to state but difficult to solve, are extensively developed and currently give rise to much research work. As examples of representative problems and results of these areas, which are discussed in this paper, we may cite the following: the Four Colors Theorem (4CTC), the Ramsey numbers, problems of the existence of distance-regular graphs and completely regular codes, and finally the study of topological proprieties of interconnection networks.Preprin

Applications and requirements for real-time simulators in ground-test facilities

This report relates simulator functions and capabilities to the operation of ground test facilities, in general. The potential benefits of having a simulator are described to aid in the selection of desired applications for a specific facility. Configuration options for integrating a simulator into the facility control system are discussed, and a logical approach to configuration selection based on desired applications is presented. The functional and data path requirements to support selected applications and configurations are defined. Finally, practical considerations for implementation (i.e., available hardware and costs) are discussed

A Task Manager for a Multiprocessor Computer System

The advent of the 32-bit microprocessor has sparked the manufacture of a number of 32-bit single-board computers (SBCs). These SBCs rival [performance of minicomputers for a fraction of the cost, and a number of them conform to standard 32-bit bus structures. A 32-bit multiprocessor computer system can be created by connecting two or more SBCs on a 32-bit bus. This computer system has the potential of providing many times the power as a single-processor computer system as well as a significant reduction in cost. The Multiprocessor Task Manager is designed to efficiently distribute software tasks, schedule their execution, and manage data flow between them, such that an effective and reliable multiprocessor is realized

NASA Tech Briefs, January 1990

Topics include: Electronic Components and Circuits. Electronic Systems, Physical Sciences, Materials, Computer Programs, Mechanics, Machinery, Fabrication Technology, Mathematics and Information Sciences, and Life Science

System data communication structures for active-control transport aircraft, volume 2

The application of communication structures to advanced transport aircraft are addressed. First, a set of avionic functional requirements is established, and a baseline set of avionics equipment is defined that will meet the requirements. Three alternative configurations for this equipment are then identified that represent the evolution toward more dispersed systems. Candidate communication structures are proposed for each system configuration, and these are compared using trade off analyses; these analyses emphasize reliability but also address complexity. Multiplex buses are recognized as the likely near term choice with mesh networks being desirable for advanced, highly dispersed systems

Routing and switching in teleconferencing networks.

Leung, Yiu-Wing.Thesis (Ph.D.)--Chinese University of Hong Kong, 1992.Includes bibliographical references (leaves 150-157).AcknowledgmentsAbstractChapter Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Background --- p.1Chapter 1.2 --- Broadband Video Services --- p.1Chapter 1.3 --- Videoconference Services --- p.7Chapter 1.4 --- Videoconference Systems --- p.8Chapter 1.5 --- Chapter Summary and Thesis Organization --- p.18Chapter Chapter 2 --- Efficient Algorithms for Multiple Destinations Routing --- p.20Chapter 2.1 --- Background --- p.20Chapter 2.2 --- Integer Programming Formulation of the MDR Problem --- p.26Chapter 2.3 --- Heuristics for Multiple Destinations Routing --- p.27Chapter 2.4 --- Performance Comparisons --- p.40Chapter 2.5 --- Chapter Summary --- p.50Chapter Chapter 3 --- Connection Optimization for Two Types of Videoconferences --- p.51Chapter 3.1 --- Background --- p.51Chapter 3.2 --- The Videoconference Services --- p.52Chapter 3.3 --- Connection Optimization --- p.54Chapter 3.4 --- Performance Analysis --- p.62Chapter 3.5 --- Chapter Summary --- p.80Chapter Chapter 4 --- A TDM-based Multibus Packet Switch --- p.81Chapter 4.1 --- Background --- p.81Chapter 4.2 --- Architecture of the Multibus Switch --- p.89Chapter 4.3 --- Operation of the Multibus Switch --- p.93Chapter 4.4 --- Performance Analysis --- p.95Chapter 4.5 --- Numerical Results --- p.106Chapter 4.6 --- Discussions --- p.109Chapter 4.7 --- Chapter Summary --- p.113Chapter Chapter 5 --- A Modular Shared Media Video Switch --- p.114Chapter 5.1 --- System Architecture and Operation --- p.114Chapter 5.2 --- Slot Assignment for Point-to-Point Transmissions --- p.129Chapter 5.3 --- Slot Assignment for Point-to-Multipoint Transmissions --- p.132Chapter 5.4 --- Network Design Example --- p.136Chapter 5.5 --- Chapter Summary --- p.143Appendix --- p.144Chapter Chapter 6 --- Conclusions --- p.147References --- p.15

The system and hardware design of real-time fan beam scatterometer data processors

There are no author-identified significant results in this report