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Results for “assessment procedures”

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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At least 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

In situ ply strengths - An initial assessment

The in situ ply strengths in several composites were calculated using a computational procedure developed for this purpose. Laminate fracture data for appropriate low modulus and high modulus fiber composites were used in the laminate analysis in conjunction with the method of least squares. The laminate fracture data were obtained from tests on Modmor-I graphite/epoxy, AS-graphite/epoxy, boron/epoxy and E-glass/epoxy. The results obtained show that the calculated in situ ply strengths can be considerably different from those measured in unidirectional composites, especially the transverse strengths and those in angleplied laminates with transply cracks.

Chamis, C. C.↗
NASA NTRS2019

GOES-16 and GOES-17 ABI INR Assessment

The Image navigation and registration (INR) Performance Assessment Tool Set (IPATS) measurement accuracy, within 0.06 pixels, is sufficient for INR assessment. IPATS is not a static system. Additional filters and/or sub-procedures were developed when the demand emerged, e.g. the development of Short Term AbNormal Dectection (STAND) and View Zenith Angle (VZA) filters in post-launch test (PLT) of GOES-16 and GOES-17 respectively. NAV INR accuracy improved with updates and tuning in PLT. Currently, NAV errors are about 1-2 urad for all assessed channels of both ABIs. IPATS NAV assessments will continue to provide feedback for tuning the navigation algorithms and parameters in future updates and future GOES-R series ABIs.

GOES-17↗
DOE OSTI2025

Characterizing secondary neutrons at BLIP for isotope production applications

Fast secondary neutrons created at the Brookhaven Linac Isotope Producer (BLIP) facility following proton irradiation were characterized by the foil activation technique and compared with FLUKA Monte Carlo simulations. The FLUKA-simulated neutron flux was spectrally adjusted following the maximum entropy formalism using the International Reactor Dosimetry and Fusion File (IRDFF-II), with predictions agreeing with experimental measurements to within 9 % following the adjustment procedure. Here, a multitude of degrader configurations were simulated to assess the feasibility of improving the fast (E n > 20 MeV) secondary neutron yield at the proposed neutron target position (“N-slot”). A configuration where the N-slot is closest to the proton degrader produced the highest fast neutron yield, with tungsten degraders achieving the best performance. Assuming the optimized target-degrader configuration proposed in this work, we discuss potential isotope production opportunities with secondary neutrons. In most cases the yields are in the order of several mCi.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2022

A Risk-Driven Probabilistic Approach to Quantify Resilience in Power Distribution Systems

It is of growing concern to ensure resilience in power distribution systems to extreme weather events. However, there are no clear methodologies or metrics available for resilience assessment that allows system planners to assess the impact of appropriate planning measures and new operational procedures for resilience enhancement. In this paper, we propose a resilience metric using parameters that define system attributes and performance. To represent extreme events (tail probability), the conditional value-at-risk of each of the parameters are combined using Choquet Integral to evaluate the overall resilience. The effectiveness of the proposed resilience metric is studied within the simulation-based framework under extreme weather scenarios with the help of a modified IEEE 123-bus system. With the proposed framework, system operators will have additional flexibility to prioritize one investment over the others to enhance the resilience of the grid.

Poudyal, Abodh↗
DOE OSTI2023

Drop C: The Drop-In, Ring-of-Power Heliostat (Final Report)

This report summarizes the work performed within the Drop-C: The Drop-In, Ring-of-Power Heliostat project. The Drop-C project aimed to develop a novel heliostat with an installed cost of $\$50$/m 2 ($\$2015$) which is a drastic cost reduction compared to the state-of-the-art. The resulting 27m 2 SunRing TM heliostat’s relative small size necessitates the parallel development of a wireless solar field network and a rapid calibration system. The SunRing heliostat is an evolution of the Ring-of-Power (ROP) design from Abengoa Solar LLC which had a reported installed cost of $114/m 2 . Cost savings relative to the ROP were sought by increasing the mirror area, improving the structural efficiency, a more accurate assessment of wind loads, and an improved assembly and installation procedure. The project spanned three Budget Periods (BP) where a digital heliostat was developed in BP1 using wind tunnel testing to define load conditions.

14 SOLAR ENERGY↗
NASA NTRS1972

The Valuation of Scientific and Technical Experiments

Rational selection of scientific and technical experiments for space missions is studied. Particular emphasis is placed on the assessment of value or worth of an experiment. A specification procedure is outlined and discussed for the case of one decision maker. Experiments are viewed as multi-attributed entities, and a relevant set of attributes is proposed. Alternative methods of describing levels of the attributes are proposed and discussed. The reasonableness of certain simplifying assumptions such as preferential and utility independence is explored, and it is tentatively concluded that preferential independence applies and utility independence appears to be appropriate.

Williams, F. E.↗
NASA NTRS1974

Fracture mechanics /Dryden Lecture/

A historical outline of the engineering discipline of fracture mechanics is presented, and current analytical procedures are summarized. The current status of the discipline is assessed, and engineering applications are discussed, along with recommended directions for future study.

Hardrath, H. F.↗
NASA NTRS1974

An evaluation of the ATM man/machine interface. Phase 3: Analysis of SL-3 and SL-4 data

The functional adequacy of human factored crew operated systems under operational zero-gravity conditions is considered. Skylab ATM experiment operations generated sufficient telemetry and voice transcript data to support such an assessment effort. Discussions are presented pertaining to the methodology and procedures used to evaluate the hardware, training and directive aspects of Skylab 3 and Skylab 4 manned ATM experiment operations.

Bathurst, J. R., Jr.↗
NASA NTRS1978

Flight experience with advanced controls and displays during piloted curved decelerating approaches in a powered-lift STOL aircraft

The control, display, and procedural features are described for a flight experiment conducted to assess the feasibility of piloted STOL approaches along predefined, steep, curved, and decelerating approach profiles. It was found to be particularly important to assist the pilot through use of the flight director computing capability with the lower frequency control-related tasks, such as those associated with monitoring and adjusting configuration trim as influenced by atmospheric effects, and preventing the system from exceeding powerplant and SAS authority limitations. Many of the technical and pilot related issues identified in the course of this flight investigation are representative of similarly demanding operational tasks that are thought to be possible only through the use of sophisticated control and display systems.

Hindson, W. S.↗
NASA NTRS1978

Atmospheric analysis modeling in support of Seasat

Atmospheric objective analysis models were developed and tested in preparation for assessing the utility of Seasat data. Of the several discretionary procedures in such computer programs, the effects of three were examined and documented: (1) the effect of varying the weights in the pattern conserving techniques; (2) the effect of varying the data influence region; (3) the effect of including wind information in analysis of mass-structure variables. The problem of inserting bogus reports is also examined.

Langland, R. A.↗
NASA NTRS1978

GASP- General Aviation Synthesis Program. Volume 1: Main program. Part 1: Theoretical development

The General Aviation synthesis program performs tasks generally associated with aircraft preliminary design and allows an analyst the capability of performing parametric studies in a rapid manner. GASP emphasizes small fixed-wing aircraft employing propulsion systems varying froma single piston engine with fixed pitch propeller through twin turboprop/ turbofan powered business or transport type aircraft. The program, which may be operated from a computer terminal in either the batch or interactive graphic mode, is comprised of modules representing the various technical disciplines integrated into a computational flow which ensures that the interacting effects of design variables are continuously accounted for in the aircraft sizing procedure. The model is a useful tool for comparing configurations, assessing aircraft performance and economics, performing tradeoff and sensitivity studies, and assessing the impact of advanced technologies on aircraft performance and economics.

Hague, D.↗
NASA NTRS1982

Proceedings of the Thirteenth Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting

Proceedings of an annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting are summarized. A transparent view of the state-of-the-art, an opportunity to express needs, a view of important future trends, and a review of relevant past accomplishments were considered for PTTI managers, systems engineers, and program planner. Specific aims were: to provide PTTI users with new and useful applications, procedures, and techniques; to allow the PTTI researcher to better assess fruitful directions for research efforts.

Wardrip, S. C.↗
NASA NTRS1983

Transformation of two and three-dimensional regions by elliptic systems

Finite difference methods for composite grids were analyzed. It was observed that linear interpolation between grids would suffice only where low order accuracy was required. In the context of fluid flow, this would be in regions where the flow was essentially free stream. Higher order interpolation schemes were also investigated. The well known quadratic and cubic interpolating polynomials would increase the formal accuracy of the overall numerical algorithm. However, it can also be shown that the stability of the algorithm may be adversely affected. Further numerical results are needed in order to assess the nature of this instability induced by the interpolation procedure. Finally, error analysis and the order of difference expressions on general curvilinear coordinates are discussed.

Thompson, J. F.↗
NASA NTRS1985

Spectral methods for modeling supersonic chemically reacting flow fields

A numerical algorithm was developed for solving the equations describing chemically reacting supersonic flows. The algorithm employs a two-stage Runge-Kutta method for integrating the equations in time and a Chebyshev spectral method for integrating the equations in space. The accuracy and efficiency of the technique were assessed by comparison with an existing implicit finite-difference procedure for modeling chemically reacting flows. The comparison showed that the procedure presented yields equivalent accuracy on much coarser grids as compared to the finite-difference procedure with resultant significant gains in computational efficiency.

Drummond, J. P.↗
NASA NTRS1985

Spectral methods for modeling supersonic chemically reacting flow fields

A partial implicit numerical algorithm has been developed for solving the equations describing chemically reacting supersonic flows. The algorithm employs a two-stage Runge-Kutta method for integrating the equations in time and a Chebyshev spectral method for integrating the equations in space. The accuracy and efficiency of the new technique have been assessed by comparison with an existing implicit finite-difference procedure for modeling chemically reacting flows. The comparison showed that the new procedure yielded equivalent accuracy on much coarser grids as compared to the finite-difference procedure with resultant significant gains in computational efficiency.

Drummond, J. P.↗
NASA NTRS1987

Diagnosis of vertical motion from VAS retrievals

Satellite-derived temperature profiles are used to determine if reliable estimates of synoptic-scale vertical motion can be obtained from the adiabatic, vorticity, and omega equation techniques. The period of study contains a short-wave trough over the Midwest and a convective outbreak over the middle Mississippi River Valley. Satellite soundings are available at 1-3 h intervals at five times. The emphasis is on assessing the strengths and weaknesses of the three vertical motion procedures, and determining the effects of short-interval observations on the calculations. Results show that the quasi-geostrophic omega equation provided patterns and magnitudes most consistent with observed weather events and 12 h radiosonde-derived motions. The vorticity method produced less satisfactory results, while adiabatic motions were unacceptable. The time derivative term dominated adiabatic motions and was a major influence in the vorticity method. Unrealistic temperature tendencies resulted from the retrieval algorithm; i.e., a diurnal temperature bias extended upwards to 500 mb, and there was a compensating effect at higher levels.

Fuelberg, Henry E.↗
NASA NTRS1989

Mercury ion thruster technology

The Mercury Ion Thruster Technology program was an investigation for improving the understanding of state-of-the-art mercury ion thrusters. Emphasis was placed on optimizing the performance and simplifying the design of the 30 cm diameter ring-cusp discharge chamber. Thruster performance was improved considerably; the baseline beam-ion production cost of the optimized configuration was reduced to Epsilon (sub i) perspective to 130 eV/ion. At a discharge propellant-utilization efficiency of 95 percent, the beam-ion production cost was reduced to about 155 eV/ion, representing a reduction of about 40 eV/ion over the corresponding value for the 30 cm diameter J-series thruster. Comprehensive Langmuir-probe surveys were obtained and compared with similar measurements for a J-series thruster. A successful volume-averaging scheme was developed to correlate thruster performance with the dominant plasma processes that prevail in the two thruster designs. The average Maxwellian electron temperature in the optimized ring-cusp design is as much as 1 eV higher than it is in the J-series thruster. Advances in ion-extraction electrode fabrication technology were made by improving materials selection criteria, hydroforming and stress-relieving tooling, and fabrications procedures. An ion-extraction performance study was conducted to assess the effect of screen aperture size on ion-optics performance and to verify the effectiveness of a beam-vectoring model for three-grid ion optics. An assessment of the technology readiness of the J-series thruster was completed, and operation of an 8 cm IAPS thruster using a simplified power processor was demonstrated.

Beattie, J. R.↗
NASA NTRS1989

Planetary protection issues for sample return missions

Planetary protection (PP) issues for both a comet nucleus sample return (CNSR) mission and a Mars rover sample return (MRSR) mission are discussed, with special attention given to the PP requirements for such missions, the exobiology science objectives for the CNSR and MRSR missions, and a qualitative PP risk assessment for both mission types. A set of contamination control procedures for both missions is presented, which identify procedures for each of the mission phases (i.e., the prelaunch, launch, sample handling, transit vehicle, and earth return). Recommendations for further research and technology development are discussed.

Devincenzi, D. L.↗