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At least 505 records · Page 28

All sources NASA NTRS DOE OSTI

NASA NTRS1980

A theoretical and experimental investigation of propeller performance methodologies

This paper briefly covers aspects related to propeller performance by means of a review of propeller methodologies; presentation of wind tunnel propeller performance data taken in the NASA Lewis Research Center 10 x 10 wind tunnel; discussion of the predominent limitations of existing propeller performance methodologies; and a brief review of airfoil developments appropriate for propeller applications.

Korkan, K. D.↗

NASA NTRS1980

Structural mapping from MSS-LANDSAT imagery: A proposed methodology for international geological correlation studies

A methodology is proposed for international geological correlation studies based on LANDSAT-MSS imagery, Bullard's model of continental fit and compatible structural trends between Northeast Brazil and the West African counterpart. Six extensive lineaments in the Brazilian study area are mapped and discussed according to their regional behavior and in relation to the adjacent continental margin. Among the first conclusions, correlations were found between the Sobral Pedro II Lineament and the megafaults that surround the West African craton; and the Pernambuco Lineament with the Ngaurandere Linemanet in Cameroon. Ongoing research to complete the methodological stages includes the mapping of the West African structural framework, reconstruction of the pre-drift puzzle, and an analysis of the counterpart correlations.

Dejesusparada, N.↗

NASA NTRS1980

Coal gasification systems engineering and analysis. Appendix E: Cost estimation and economic evaluation methodology

The cost estimation and economic evaluation methodologies presented are consistent with industry practice for assessing capital investment requirements and operating costs of coal conversion systems. All values stated are based on January, 1980 dollars with appropriate recognition of the time value of money. Evaluation of project economic feasibility can be considered a two step process (subject to considerable refinement). First, the costs of the project must be quantified and second, the price at which the product can be manufacturd must be determined. These two major categories are discussed. The summary of methodology is divided into five parts: (1) systems costs, (2)instant plant costs, (3) annual operating costs, (4) escalation and discounting process, and (5) product pricing.

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NASA NTRS1980

Cost-effectiveness methodology for computer systems selection

A new approach to the problem of selecting a computer system design has been developed. The purpose of this methodology is to identify a system design that is capable of fulfilling system objectives in the most economical way. The methodology characterizes each system design by the cost of the system life cycle and by the system's effectiveness in reaching objectives. Cost is measured by a 'system cost index' derived from an analysis of all expenditures and possible revenues over the system life cycle. Effectiveness is measured by a 'system utility index' obtained by combining the impact that each selection factor has on the system objectives and it is assessed through a 'utility curve'. A preestablished algorithm combines cost and utility and provides a ranking of the alternative system designs from which the 'best' design is selected.

Vallone, A.↗

NASA NTRS1981

A survey of load methodologies for shuttle orbiter payloads

Loads methods currently being used to design planetary spacecraft to be launched on the shuttle orbiter are summarized. Experiences gained from expendable launch vehicle payloads are used to develop methodologies for the space shuttle orbiter payloads. The objectives for the development of a new methodology for the shuttle payloads are to reduce the cost and schedule for the payload load analysis by decoupling the payload analysis from the launch vehicle to the maximum extent possible. Methods are described for payload member load estimation or obtaining upper bounds for dynamic loads, as well as load prediction or calculating actual transient member load time histories.

Chen, J. C.↗

NASA NTRS1981

A normative price for energy from an electricity generation system: An Owner-dependent Methodology for Energy Generation (system) Assessment (OMEGA). Volume 1: Summary

The utility owned solar electric system methodology is generalized and updated. The net present value of the system is determined by consideration of all financial benefits and costs (including a specified return on investment). Life cycle costs, life cycle revenues, and residual system values are obtained. Break even values of system parameters are estimated by setting the net present value to zero. While the model was designed for photovoltaic generators with a possible thermal energy byproduct, it applicability is not limited to such systems. The resulting owner-dependent methodology for energy generation system assessment consists of a few equations that can be evaluated without the aid of a high-speed computer.

Chamberlain, R. G.↗

NASA NTRS1981

Methodology evaluation: Effects of independent verification and intergration on one class of application

The effects of an independent verification and integration (V and I) methodology on one class of application are described. Resource profiles are discussed. The development environment is reviewed. Seven measures are presented to test the hypothesis that V and I improve the development and product. The V and I methodology provided: (1) a decrease in requirements ambiguities and misinterpretation; (2) no decrease in design errors; (3) no decrease in the cost of correcting errors; (4) a decrease in the cost of system and acceptance testing; (5) an increase in early discovery of errors; (6) no improvement in the quality of software put into operation; and (7) a decrease in productivity and an increase in cost.

Page, J.↗

NASA NTRS1981

Selecting a software development methodology

The state of the art analytical techniques for the development and verification of digital flight control software is studied and a practical designer oriented development and verification methodology is produced. The effectiveness of the analytic techniques chosen for the development and verification methodology are assessed both technically and financially. Technical assessments analyze the error preventing and detecting capabilities of the chosen technique in all of the pertinent software development phases. Financial assessments describe the cost impact of using the techniques, specifically, the cost of implementing and applying the techniques as well as the relizable cost savings. Both the technical and financial assessment are quantitative where possible. In the case of techniques which cannot be quantitatively assessed, qualitative judgements are expressed about the effectiveness and cost of the techniques. The reasons why quantitative assessments are not possible will be documented.

Jones, R. E.↗

NASA NTRS1982

A design methodology for nonlinear systems containing parameter uncertainty: Application to nonlinear controller design

A design methodology capable of dealing with nonlinear systems, such as a controlled ecological life support system (CELSS), containing parameter uncertainty is discussed. The methodology was applied to the design of discrete time nonlinear controllers. The nonlinear controllers can be used to control either linear or nonlinear systems. Several controller strategies are presented to illustrate the design procedure.

Young, G.↗

NASA NTRS1982

Evaluation of automated decisionmaking methodologies and development of an integrated robotic system simulation. Volume 2, Part 2: Appendixes B, C, D and E

The derivation of the equations is presented, the rate control algorithm described, and simulation methodologies summarized. A set of dynamics equations that can be used recursively to calculate forces and torques acting at the joints of an n link manipulator given the manipulator joint rates are derived. The equations are valid for any n link manipulator system with any kind of joints connected in any sequence. The equations of motion for the class of manipulators consisting of n rigid links interconnected by rotary joints are derived. A technique is outlined for reducing the system of equations to eliminate contraint torques. The linearized dynamics equations for an n link manipulator system are derived. The general n link linearized equations are then applied to a two link configuration. The coordinated rate control algorithm used to compute individual joint rates when given end effector rates is described. A short discussion of simulation methodologies is presented.

Lowrie, J. W.↗

NASA NTRS1982

Development of test methodology for dynamic mechanical analysis instrumentation

Dynamic mechanical analysis instrumentation was used for the development of specific test methodology in the determination of engineering parameters of selected materials, esp. plastics and elastomers, over a broad range of temperature with selected environment. The methodology for routine procedures was established with specific attention given to sample geometry, sample size, and mounting techniques. The basic software of the duPont 1090 thermal analyzer was used for data reduction which simplify the theoretical interpretation. Clamps were developed which allowed 'relative' damping during the cure cycle to be measured for the fiber-glass supported resin. The correlation of fracture energy 'toughness' (or impact strength) with the low temperature (glassy) relaxation responses for a 'rubber-modified' epoxy system was negative in result because the low-temperature dispersion mode (-80 C) of the modifier coincided with that of the epoxy matrix, making quantitative comparison unrealistic.

Allen, V. R.↗

NASA NTRS1983

Three-dimensional viscous design methodology for advanced technology aircraft supersonic inlet systems

A broad program to develop advanced, reliable, and user oriented three-dimensional viscous design techniques for supersonic inlet systems, and encourage their transfer into the general user community is discussed. Features of the program include: (1) develop effective methods of computing three-dimensional flows within a zonal modeling methodology; (2) ensure reasonable agreement between said analysis and selective sets of benchmark validation data; (3) develop user orientation into said analysis; and (4) explore and develop advanced numerical methodology.

Anderson, B. H.↗

NASA NTRS1983

A Formal Semantics for the SRI Hierarchical Program Design Methodology

A formal statement of what it means to use (a subset of) the methodology is presented. It is formally defined that some specified module exists and what it means to say that another module is paid correctly implemented on top of it. No attention is to motivation, either of the methodology or of the formal development of it. Concentration is entirely upon mathematical succinctness and precision. A discussion is presented of how to use certain INTERLISP programs which implement the formal definitions. Among these are a program which generates Floyd like verification conditions sufficient to imply the correctness of a module implementation.

Boyer, R. S.↗

NASA NTRS1982

Acoustic methodology review

It is important for industry and NASA to assess the status of acoustic design technology for predicting and controlling helicopter external noise in order for a meaningful research program to be formulated which will address this problem. The prediction methodologies available to the designer and the acoustic engineer are three-fold. First is what has been described as a first principle analysis. This analysis approach attempts to remove any empiricism from the analysis process and deals with a theoretical mechanism approach to predicting the noise. The second approach attempts to combine first principle methodology (when available) with empirical data to formulate source predictors which can be combined to predict vehicle levels. The third is an empirical analysis, which attempts to generalize measured trends into a vehicle noise prediction method. This paper will briefly address each.

Schlegel, R. G.↗

NASA NTRS1984

Three-dimensional viscous design methodology for advanced technology aircraft supersonic inlet systems

Anderson, B. H.↗

NASA NTRS1983

A design methodology for nonlinear systems containing parameter uncertainty

In the present design methodology for nonlinear systems containing parameter uncertainty, a generalized sensitivity analysis is incorporated which employs parameter space sampling and statistical inference. For the case of a system with j adjustable and k nonadjustable parameters, this methodology (which includes an adaptive random search strategy) is used to determine the combination of j adjustable parameter values which maximize the probability of those performance indices which simultaneously satisfy design criteria in spite of the uncertainty due to k nonadjustable parameters.

Young, G. E.↗

NASA NTRS1984

Basic principles, methodology, and applications of remote sensing in agriculture

The basic principles of remote sensing applied to agriculture and the methods used in data analysis are described. Emphasis is placed on the importance of developing a methodology that may help crop forecast, basic concepts of spectral signatures of vegetation, the methodology of the LANDSAT data utilization in agriculture, and the remote sensing program application of INPE (Institute for Space Research) in agriculture.

Moreira, M. A.↗

NASA NTRS1984

Application of the Hardman methodology to the Single Channel Ground-Airborne Radio System (SINCGARS)

The HARDMAN methodology was applied to the various configurations of employment for an emerging Army multipurpose communications system. The methodology was used to analyze the manpower, personnel and training (MPT) requirements and associated costs, of the system concepts responsive to the Army's requirement for the Single Channel Ground-Airborne Radio System (SINCGARS). The scope of the application includes the analysis of two conceptual designs Cincinnati Electronics and ITT Aerospace/Optical Division for operating and maintenance support addressed through the general support maintenance echelon.

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