A Stability Analysis Framework for Oscillation Analysis and Mitigation
This presentation showcases a framework for oscillation analysis and mitigation based on small-signal analysis.
24 POWER TRANSMISSION AND DISTRIBUTION↗
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Results for “distribution factor”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Utilization of available skills and materials in fire prevention
Procedures for installing fire protection systems in large buildings are discussed. Factors considered in the safety management are: (1) distribution of water supply, (2) design and location of exits, (3) emergency power system, and (4) maintenance procedures.
Martin, H. W.↗
The plasmatron: Advanced mode thermionic energy conversion
A theory of the plasmatron was developed. Also, a wide range of measurements were obtained with two versatile, research devices. To gain insight into plasmatron performance, the experimental results are compared with calculations based on the theoretical model of plasmatron operation. Results are presented which show that the plasma arc drop of the conventional arc (ignited) mode converter can be suppressed by use of an auxiliary ion source. The improved performance, however, is presently limited to low current densities because of voltage losses due to plasma resistance. This resistance loss could be suppressed by an increase in the plasma electron temperature or a decrease in spacing. Plasmatron performance characteristics for both argon and cesium are reported. The argon plasmatron has superior performance. Results are also presented for magnetic cutoff effects and for current distributing effects. These are shown to be important factors for the design of practical devices.
Hansen, L. K.↗
An investigation of the observability of ocean-surface parameters using GEOS-3 backscatter data
The degree to which ocean surface roughness can be synoptically observed through use of the information extracted from the GEOS-3 backscattered waveform data was evaluated. Algorithms are given for use in estimating the radar sensed waveheight distribution or ocean-surface impulse response. Other factors discussed include comparisons between theoretical and experimental radar cross section values, sea state bias effects, spatial variability of significant waveheight data, and sensor-related considerations.
Miller, L. S.↗
Analysis of eighty-four commercial aviation incidents - Implications for a resource management approach to crew training
A resource management approach to aircrew performance is defined and utilized in structuring an analysis of 84 exemplary incidents from the NASA Aviation Safety Reporting System. The distribution of enabling and associated (evolutionary) and recovery factors between and within five analytic categories suggests that resource management training be concentrated on: (1) interpersonal communications, with air traffic control information of major concern; (2) task management, mainly setting priorities and appropriately allocating tasks under varying workload levels; and (3) planning, coordination, and decisionmaking concerned with preventing and recovering from potentially unsafe situations in certain aircraft maneuvers.
Murphy, M. R.↗
Monitoring and control requirement definition study for Dispersed Storage and Generation (DSG). Volume 5, appendix D: Cost-benefit considerations for providing dispersed storage and generation for electric utilities
Cost benefit considerations are extremely important in obtaining the acceptance of dispersed storage and generation (DSG) by the electric utilities. These considerations involved somewhat different economic analyses depending on whether the generation is utility, customer, or combined ownership. It is necessary to get acceptance of more easily understood methods for evaluating the economics of DSG because much of the benefits of DSG may accrue in the generation and transmission portions of the utility system while the costs tend to be centered in the distribution portion of that system. The influence of factors, such as reliability, capital costs, and other economic measures were also investigated.
Source record↗
Stochastic analysis of multiple-passband spectral classifications systems affected by observation errors
The classification of targets viewed by a pushbroom type multiple band spectral scanner by algorithms suitable for implementation in high speed online digital circuits is considered. A class of algorithms suitable for use with a pipelined classifier is investigated through simulations based on observed data from agricultural targets. It is shown that time distribution of target types is an important determining factor in classification efficiency.
Tsokos, C. P.↗
Theoretical foundations for quantitative paleogenetics. III - The molecular divergence of nucleic acids and proteins for the case of genetic events of unequal probability
Theoretical equations are derived for molecular divergence with respect to gene and protein structure in the presence of genetic events with unequal probabilities: amino acid and base compositions, the frequencies of nucleotide replacements, the usage of degenerate codons, the distribution of fixed base replacements within codons and the distribution of fixed base replacements among codons. Results are presented in the form of tables relating the probabilities of given numbers of codon base changes with respect to the original codon for the alpha hemoglobin, beta hemoglobin, myoglobin, cytochrome c and parvalbumin group gene families. Application of the calculations to the rabbit alpha and beta hemoglobin mRNAs and proteins indicates that the genes are separated by about 425 fixed based replacements distributed over 114 codon sites, which is a factor of two greater than previous estimates. The theoretical results also suggest that many more base replacements are required to effect a given gene or protein structural change than previously believed.
Holmquist, R.↗
Advanced biostack experiment
The Advanced Biostack Experiment is described. The objectives are: (1) to confirm, complement, and enlarge the information obtained from the previous experiments by applying improved and advanced methods of localization and physical and biological evaluation, performing advanced experiments based on these data, and including additional biological specimens and additional radiation detectors; (2) to determine the biological importance of nuclear disintegration stars; (3) to determine the interference of HZE particle induced effects with those of other space flight factors (e.g., weightlessness); and (4) to determine the distribution of HZE particles and of disintegration stars at different locations inside the module and on the pallet.
Buecker, H.↗
Compact radio source 1413 + 135 is a far-IR extragalactic object
The radio source 1413 + 135 is shown to be one of the strongest known emitters of millimeter radiation. The energy distribution of this object, measured between meter and X-ray wavelengths, reveals that most of the power emitted by this object comes out at millimeter and far-IR wavelengths. If the emission at 1 mm is due to incoherent synchrotron radiation, then the source must be very compact, with a size around 25 micron arc sec, and contain a magnetic field larger than 10 G. The steep spectral index in the near-IR is attributed to a high-energy cutoff in the distribution of synchrotron emitting electrons at a Lorentz factor of approximately 300.
Beichman, C. A.↗
High frequency sound emission from moving point multipole sources embedded in arbitrary transversely sheared mean flows
Formulas are derived for the high frequency sound emission from moving point multipole sources embedded in an arbitrary unidirectional transversely sheared mean flow. The results are used to study the sound generated by non-axisymmetric turbulent jets. The effect of the asymmetry in both the mean flow and the source distribution is accounted for by a 'circumferential directivity factor', which is easily calculated from the solution of a second order ordinary differential equation in the general case and from an explicit formula when the mean flow is symmetric but the source location is not. This factor is used to assess the potential of employing asymmetric velocity profiles that redirect the sound upward to reduce the noise radiation below the flight path of a jet aircraft.
Goldstein, M. E.↗
Bifurcation and stability of low-order steady flows in horizontally and vertically forced convection
A nonlinear spectral model of two-dimensional, shallow Boussinesq convection which responds to heating in both the horizontal and vertical directions is examined. The governing partial differential system is converted to an infinite set of ordinary differential equations and truncated to a small set to permit detailed study of the number and types of transitions from one flow configuration to another. The Hadley number and the Rayleigh number are defined as the horizontal and vertical thermal forcing mechanisms, respectively, for inclusion in the nonlinear spectral model, which is composed of three equations. The model is then used to describe steady states, linearly stable solutions, and balancing factors in unstable stratification. The number and the distribution of the steady states are found to be qualitatively independent of the aspect ratio and the Prandtl number.
Yost, D. A.↗
Models of the millimeter-centimeter spectra of the giant planets
In the present comparison of various model atmosphere calculations with data for all four giant planets, the absorption profile of ammonia at centimeter wavelengths was assumed to be represented by a Ben Reuven (1966) line profile; this permitted the derivation of information on the vertical distribution of ammonia in these planets' atmospheres. It appeared that ammonia must be depleted in the upper atmospheres of all four planets by a factor of 4-5 with respect to the solar abundance for Jupiter and Saturn, and by a factor of 100-200 for Uranus and Neptune. Given the vertical ammonia distribution in the atmospheres, as derived from the cm-data, a best fit to mm-data on all four planets was found by changing the high frequency tail of the ammonium lineshape profile.
De Pater, I.↗
Modeling the radiant transfers of sparse vegetation canopies
The scattering dynamics of sparse vegetation canopies were studied within the framework of the three-dimensional radiative transfer model of Kimes (1984). The model was upgraded by including an algorithm for the anisotropic scattering of a soil boundary. Validation of the model was carried out using measured directional reflectance data for two canopies exhibiting typical scattering behavior with low and intermediate vegetation density. The canopies were: an orchard grass canopy; and a hard wheat canopy. A number of factors were found contributing to the final reflectance distribution of the canopies, including: (1) the strong anisotropic scattering properties of the soil; (2) the geometric effect of the vegetation probability gap function on the soil anisotropy and solar irradiance; and (3) the anisotropic scattering of vegetation which is controlled by the phase function and the layering of leaves. The application of the theoretical results to the development of earth-observing sensor systems is discussed.
Kimes, D. S.↗
A dynamical model of lithosphere extension and sedimentary basin formation
The effect of convection-induced stresses at the base of the continental lithosphere on surface and extensional deviatoric stresses is investigated. The biaxial strain in the continental lithosphere is controlled by power law creep in the upper and lower crust, brittle failure, and the Dorn plasticity law. The relationship between the lithosphere stress distribution and Moho temperatures is examined. The extension factors, basin subsidence, heat flow, and sediment loading of the lithosphere are studied.
Houseman, G.↗
Three-dimensional elliptic grid generation technique with application to turbomachinery cascades
Described is a numerical method for generating 3-D grids for turbomachinery computational fluid dynamic codes. The basic method is general and involves the solution of a quasi-linear elliptic partial differential equation via pointwise relaxation with a local relaxation factor. It allows specification of the grid point distribution on the boundary surfaces, the grid spacing off the boundary surfaces, and the grid orthogonality at the boundary surfaces. A geometry preprocessor constructs the grid point distributions on the boundary surfaces for general turbomachinery cascades. Representative results are shown for a C-grid and an H-grid for a turbine rotor. Two appendices serve as user's manuals for the basic solver and the geometry preprocessor.
Chen, S. C.↗
Nonlinear stability of a flow with bound eddies
Kovasznay (1948) obtained an exact solution of the Navier-Stokes equations that describes a flow with periodic bound eddies. The stability of this nonparallel flow with respect to three-dimensional finite amplitude disturbances is analyzed by use of the energy method. A sufficient condition for global stability is obtained. It is shown that the additional nonhomogeneity in shear stress distribution in a nonparallel flow is a destabilizing factor.
Lin, S. P.↗
Automation of Shuttle Tile Inspection - Engineering methodology for Space Station
The Space Systems Integration and Operations Research Applications (SIORA) Program was initiated in late 1986 as a cooperative applications research effort between Stanford University, NASA Kennedy Space Center, and Lockheed Space Operations Company. One of the major initial SIORA tasks was the application of automation and robotics technology to all aspects of the Shuttle tile processing and inspection system. This effort has adopted a systems engineering approach consisting of an integrated set of rapid prototyping testbeds in which a government/university/industry team of users, technologists, and engineers test and evaluate new concepts and technologies within the operational world of Shuttle. These integrated testbeds include speech recognition and synthesis, laser imaging inspection systems, distributed Ada programming environments, distributed relational database architectures, distributed computer network architectures, multimedia workbenches, and human factors considerations.
Wiskerchen, M. J.↗