25,199 research outputs found
Basic Human Factors Task Data Relationships in Aerospace System Design and Development Final Report, Aug. - Dec. 1965
Basic human factors task data relationships in aerospace system design and developmen
AgRISTARS: Foreign commodity production forecasting. Country summary report, Australia
Australia is one of the world's major growers and exporters of wheat and as such is one of the countries of interest in the AgRISTARS program which endeavors to develop technology to estimate crop production using aerospace remote sensing. A compilation of geographic, political, and agricultural information on Australia is presented. Also included is a summary of the aerospace remote sensing, meteorological, and ground-observed data which were collected with respect to Australia, as well as a summary of contacts between AgRISTARS and Australia personnel
NOSS/ALDCS analysis and system requirements definition
The results of system analyses and implementation studies of an advanced location and data collection system (ALDCS) , proposed for inclusion on the National Oceanic Satellite System (NOSS) spacecraft are reported. The system applies Doppler processing and radiofrequency interferometer position location technqiues both alone and in combination. Aspects analyzed include: the constraints imposed by random access to the system by platforms, the RF link parameters, geometric concepts of position and velocity estimation by the two techniques considered, and the effects of electrical measurement errors, spacecraft attitude errors, and geometric parameters on estimation accuracy. Hardware techniques and trade-offs for interferometric phase measurement, ambiguity resolution and calibration are considered. A combined Doppler-interferometer ALDCS intended to fulfill the NOSS data validation and oceanic research support mission is also described
Parallel, iterative solution of sparse linear systems: Models and architectures
A model of a general class of asynchronous, iterative solution methods for linear systems is developed. In the model, the system is solved by creating several cooperating tasks that each compute a portion of the solution vector. A data transfer model predicting both the probability that data must be transferred between two tasks and the amount of data to be transferred is presented. This model is used to derive an execution time model for predicting parallel execution time and an optimal number of tasks given the dimension and sparsity of the coefficient matrix and the costs of computation, synchronization, and communication. The suitability of different parallel architectures for solving randomly sparse linear systems is discussed. Based on the complexity of task scheduling, one parallel architecture, based on a broadcast bus, is presented and analyzed
A model of asynchronous iterative algorithms for solving large, sparse, linear systems
Solving large, sparse, linear systems of equations is one of the fundamental problems in large scale scientific and engineering computation. A model of a general class of asynchronous, iterative solution methods for linear systems is developed. In the model, the system is solved by creating several cooperating tasks that each compute a portion of the solution vector. This model is then analyzed to determine the expected intertask data transfer and task computational complexity as functions of the number of tasks. Based on the analysis, recommendations for task partitioning are made. These recommendations are a function of the sparseness of the linear system, its structure (i.e., randomly sparse or banded), and dimension
Analysis of Meteorological Satellite location and data collection system concepts
A satellite system that employs a spaceborne RF interferometer to determine the location and velocity of data collection platforms attached to meteorological balloons is proposed. This meteorological advanced location and data collection system (MALDCS) is intended to fly aboard a low polar orbiting satellite. The flight instrument configuration includes antennas supported on long deployable booms. The platform location and velocity estimation errors introduced by the dynamic and thermal behavior of the antenna booms and the effects of the presence of the booms on the performance of the spacecraft's attitude control system, and the control system design considerations critical to stable operations are examined. The physical parameters of the Astromast type of deployable boom were used in the dynamic and thermal boom analysis, and the TIROS N system was assumed for the attitude control analysis. Velocity estimation error versus boom length was determined. There was an optimum, minimum error, antenna separation distance. A description of the proposed MALDCS system and a discussion of ambiguity resolution are included
Stencils and problem partitionings: Their influence on the performance of multiple processor systems
Given a discretization stencil, partitioning the problem domain is an important first step for the efficient solution of partial differential equations on multiple processor systems. Partitions are derived that minimize interprocessor communication when the number of processors is known a priori and each domain partition is assigned to a different processor. This partitioning technique uses the stencil structure to select appropriate partition shapes. For square problem domains, it is shown that non-standard partitions (e.g., hexagons) are frequently preferable to the standard square partitions for a variety of commonly used stencils. This investigation is concluded with a formalization of the relationship between partition shape, stencil structure, and architecture, allowing selection of optimal partitions for a variety of parallel systems
Case Study of the Kingsport Regional Education Alliance
The primary purpose of this study was to investigate the origin and evolution of the Kingsport Regional Education Alliance (KREA 2000). A total of 18 individuals, representing three categories, business, education, and community, were selected by purposeful sampling techniques to participate. Data were collected through qualitative methods. The analysis revealed attitudes, behaviors, and perceptions of those involved in the KREA 2000 activities. Through data analysis the investigator identified a core group of influencers who were primarily responsible for the creation of KREA 2000. The investigator identified four major categories that were critical to the evolution of KREA 2000. The four major categories were: leadership, communication, infrastructure, and collaboration. Based on the findings, the following recommendations were suggested: (1) KREA 2000 should set up a channel of leadership that will prepare future chairs; (2) KREA 2000 should become more proactive in the political arena in regard to educational issues; (3) the KREA 2000 should be staffed with a full time coordinator and a part-time clerical person, (4) KREA 2000 should appoint a volunteer liaison to each participant agency; and (5) KREA 2000 should concentrate on supporting initiatives within and among the participant agency, not create independent projects
Inventories of Delaware's coastal vegetation and land-use utilizing digital processing of ERTS-1 imagery
There are no author-identified significant results in this report
Spectral bounds for the cutoff Coulomb potential
The method of potential envelopes is used to analyse the bound-state spectrum
of the Schroedinger Hamiltonian H = -Delta -v/(r+b), where v and b are
positive. We established simple formulas yielding upper and lower energy bounds
for all the energy eigenvalues.Comment: 11 pages, 2 figure
- …