Search NASA⌕ Search

SEARCH · Search NASA

Results for “system adequacy”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

A failure effects simulation of a low authority flight control augmentation system on a UH-1H helicopter

A two-pilot moving base simulator experiment was conducted to assess the effects of servo failures of a flight control system on the transient dynamics of a Bell UH-1H helicopter. The flight control hardware considered was part of the V/STOLAND system built with control authorities of from 20-40%. Servo hardover and oscillatory failures were simulated in each control axis. Measurements were made to determine the adequacy of the failure monitoring system time delay and the servo center and lock time constant, the pilot reaction times, and the altitude and attitude excursions of the helicopter at hover and 60 knots. Safe recoveries were made from all failures under VFR conditions. Pilot reaction times were from 0.5 to 0.75 sec. Reduction of monitor delay times below these values resulted in significantly reduced excursion envelopes. A subsequent flight test was conducted on a UH-1H helicopter with the V/STOLAND system installed. Series servo hardovers were introduced in hover and at 60 knots straight and level. Data from these tests are included for comparison.

Corliss, L. D.↗
NASA NTRS1992

Modeling and analysis of the Space Station Freedom Active Thermal Control System radiators using SINDA/FLUINT

Detailed SINDA/FLUINT models have been developed to assess the adequacy of the Space Station Freedom External Thermal Control System's radiator design, as well as to simulate the effects of various operational scenarios. Design margins can be deduced by quantifying such real-world effects as flow maldistribution due to line-pressure drop and uneven heat loads. The factor which most reduced the heat-rejection capacity is an uneven heat load split between the two low temperature loops.

Andish, Kambiz K.↗
DOE OSTI2023

Modeling and analysis of the tritium fuel cycle for ARC- and STEP-class D-T fusion power plants

Abstract The limited tritium resources available for the first fusion power plants (FPPs) make fuel self-sufficiency and tritium inventory minimization leading issues in FPP design. This work builds on the model proposed by Abdou et al (2020 Nucl. Fusion 61 013001), which analyzed the fuel cycle (FC) of a DEMOnstration nuclear FPP-class FPP with a time-dependent system-level model. Here, we use a modified version of their model to analyze the FC of an Affordable, Robust, Compact (ARC)-class tokamak and two versions of a Spherical Tokamak for Energy Production (STEP)-class tokamak. The ARC-class tokamak breeds tritium in a 2LiF + BeF 2 liquid immersion blanket, while the STEP-class tokamak breeds tritium utilizing either a liquid-lithium blanket design or an encapsulated breeding blanket. A time-dependent system-level model is developed in Matlab Simulink ® to simulate the evolution of tritium flows and tritium inventories in the FC. The main goals of this work are to assess tritium self-sufficiency of the ARC- and STEP-class designs and to determine quantitative design requirements that can be used to analyze the adequacy of a proposed FC system. These design requirements are aimed at achieving a low tritium inventory doubling time ( t d ) and a low start-up inventory ( I s t a r t u p ) while keeping the required tritium breeding ratio (TBR r ) as low as possible. We also consider how improvements in FC technology and POs affect TBR r and I s t a r t u p . The model results show that TBR r for ARC- and STEP-class FPPs should be achievable if the tritium burn efficiency (TBE) reaches 0.5%–1% (TBR r < 1.2). This assumes significant, but attainable, improvements over current abilities. However, the model results indicate that an FPP must achieve ambitious performance targets, including FPP availability > 70%, tritium processing time < 4 h, and the implementation of direct internal recycling (DIR). If future research yields major improvements to achievable TBE, it may be possible to achieve tritium self-sufficiency while operating at lower availability and without implementing DIR.

Physics↗
NASA NTRS1972

Apollo experience report: S-band system signal design and analysis

A description is given of the Apollo communications-system engineering-analysis effort that ensured the adequacy, performance, and interface compatibility of the unified S-band system elements for a successful lunar-landing mission. The evolution and conceptual design of the unified S-band system are briefly reviewed from a historical viewpoint. A comprehensive discussion of the unified S-band elements includes the salient design features of the system and serves as a basis for a better understanding of the design decisions and analyses. The significant design decisions concerning the Apollo communications-system signal design are discussed providing an insight into the role of systems analysis in arriving at the current configuration of the Apollo communications system. Analyses are presented concerning performance estimation (mathematical-model development through real-time mission support) and system deficiencies, modifications, and improvements.

Rosenberg, H. R.↗
NASA NTRS1997

In-Flight Flow Visualization Using Infrared Thermography

The feasibility of remote infrared thermography of aircraft surfaces during flight to visualize the extent of laminar flow on a target aircraft has been examined. In general, it was determined that such thermograms can be taken successfully using an existing airplane/thermography system (NASA Dryden's F-18 with infrared imaging pod) and that the transition pattern and, thus, the extent of laminar flow can be extracted from these thermograms. Depending on the in-flight distance between the F-18 and the target aircraft, the thermograms can have a spatial resolution of as little as 0.1 inches. The field of view provided by the present remote system is superior to that of prior stationary infrared thermography systems mounted in the fuselage or vertical tail of a subject aircraft. An additional advantage of the present experimental technique is that the target aircraft requires no or minimal modifications. An image processing procedure was developed which improves the signal-to-noise ratio of the thermograms. Problems encountered during the analog recording of the thermograms (banding of video images) made it impossible to evaluate the adequacy of the present imaging system and image processing procedure to detect transition on untreated metal surfaces. The high reflectance, high thermal difussivity, and low emittance of metal surfaces tend to degrade the images to an extent that it is very difficult to extract transition information from them. The application of a thin (0.005 inches) self-adhesive insulating film to the surface is shown to solve this problem satisfactorily. In addition to the problem of infrared based transition detection on untreated metal surfaces, future flight tests will also concentrate on the visualization of other flow phenomena such as flow separation and reattachment.

vanDam, C. P.↗
DOE OSTI2024

New Safety Feedback Control Design to Guarantee Adequate Frequency Performance in Microgrids

Safety analysis of power systems is concerned with the system's ability to maintain critical variables within specified limits following a disturbance. Frequency control adequacy has become increasingly important as the system inertia decreases due to the increase in renewable energy penetration. Various controllers for inverters have been proposed to improve the system frequency response and few are capable to ensure the safety of the response. In this article, a diesel-wind energy system is considered and modeled as a switching system between normal, faulted, and post-fault modes. Further, a safety feedback controller is designed as a supplementary signal for a wind turbine generator such that the speed of the diesel generator stays within a permissible range in the presence of a finite energy disturbance. Numerical results on the modified 33-bus microgrid system obtained of the proposed novel approach indicate that the suggested control configuration can guarantee adequate frequency response without excessive conservativeness.

barrier function↗
DOE OSTI2024

Evaluating Transmission's Role in Resource Adequacy

Transmission can play an important role in ensuring systems are resource adequate, yet in many cases quantifying that value can be difficult. This presentation explores different ways to understand transmission resource adequacy value, and in particular highlights how transmission can impact the tradeoff between reliability and cost.

ENERGY PLANNING, POLICY, AND ECONOMY,POWER TRANSMI↗
NASA NTRS1973

Effects of various runway lighting parameters upon the relation between runway visual range and visual range of centerline and edge lights in fog

Thirty six students and 54 commercial airline pilots were tested in the fog chamber to determine the effect of runway edge and centerline light intensity and spacing, fog density, ambient luminance level, and lateral and vertical offset distance of the subject from the runway's centerline upon horizontal visual range. These data were obtained to evaluate the adequacy of a balanced lighting system to provide maximum visual range in fog viewing both centerline and runway edge lights. The daytime system was compared against two other candidate lighting systems; the nighttime system was compared against other candidate lighting systems. The second objective was to determine if visual range is affected by lights between the subject and the farthestmost light visible through the fog. The third objective was to determine if college student subjects differ from commercial airline pilots in their horizontal visual range through fog. Two studies were conducted.

Haines, R. F.↗
NASA NTRS1991

Applicability of relative GPS to automated rendezvous between the space shuttle and Space Station

The purpose of this study is to determine the adequacy of the Global Positioning System (GPS) in providing relative navigation for automated rendezvous and proximity operations. The study was performed using the Proximity Operations Simulator (POS), Lockheed's high-fidelity, six-degree-of-freedom simulation of the Space Shuttle and Space Station. This simulation includes identical models of GPS receivers for each vehicle. The navigation software in each vehicle includes identical Kalman filters. Each vehicle estimates its own state, and the relative state is obtained by simply subtracting absolute states.

Clark, Fred D.↗
NASA NTRS1991

Applicability of relative GPS to automated rendezvous between the space shuttle and space station

The purpose of this study is to determine the adequacy of the Global Positioning System (GPS) in providing relative navigation for automated rendezvous and proximity operations. The study was performed using the Proximity Operations Simulator (POS), Lockheed's high-fidelity, 6 degree of freedom simulation of the space shuttle and space station. This simulation includes identical models of GPS receivers for each vehicle. The navigation software in each vehicle includes identical Kalman filters. Each filter computes the absolute state of its vehicle, and the relative state vector is obtained by simply subtracting absolute states.

Clark, Fred D.↗
NASA NTRS1993

NASA trend analysis procedures

This publication is primarily intended for use by NASA personnel engaged in managing or implementing trend analysis programs. 'Trend analysis' refers to the observation of current activity in the context of the past in order to infer the expected level of future activity. NASA trend analysis was divided into 5 categories: problem, performance, supportability, programmatic, and reliability. Problem trend analysis uncovers multiple occurrences of historical hardware or software problems or failures in order to focus future corrective action. Performance trend analysis observes changing levels of real-time or historical flight vehicle performance parameters such as temperatures, pressures, and flow rates as compared to specification or 'safe' limits. Supportability trend analysis assesses the adequacy of the spaceflight logistics system; example indicators are repair-turn-around time and parts stockage levels. Programmatic trend analysis uses quantitative indicators to evaluate the 'health' of NASA programs of all types. Finally, reliability trend analysis attempts to evaluate the growth of system reliability based on a decreasing rate of occurrence of hardware problems over time. Procedures for conducting all five types of trend analysis are provided in this publication, prepared through the joint efforts of the NASA Trend Analysis Working Group.

Source record↗
NASA NTRS2000

Remote Sensing and the Kyoto Protocol: A Workshop Summary

The Kyoto Protocol to the United Nations Framework Convention on Climate Change contains quantified, legally binding commitments to limit or reduce greenhouse gas emissions to 1990 levels and allows carbon emissions to be balanced by carbon sinks represented by vegetation. The issue of using vegetation cover as an emission offset raises a debate about the adequacy of current remote sensing systems and data archives to both assess carbon stocks/sinks at 1990 levels, and monitor the current and future global status of those stocks. These concerns and the potential ratification of the Protocol among participating countries is stimulating policy debates and underscoring a need for the exchange of information between the international legal community and the remote sensing community. On October 20-22 1999, two working groups of the International Society for Photogrammetry and Remote Sensing (ISPRS) joined with the University of Michigan (Michigan, USA) to convene discussions on how remote sensing technology could contribute to the information requirements raised by implementation of, and compliance with, the Kyoto Protocol. The meeting originated as a joint effort between the Global Monitoring Working Group and the Radar Applications Working Group in Commission VII of the ISPRS, co-sponsored by the University of Michigan. Tile meeting was attended by representatives from national government agencies and international organizations and academic institutions. Some of the key themes addressed were: (1) legal aspects of transnational remote sensing in the context of the Kyoto Protocol; (2) a review of the current and future and remote sensing technologies that could be applied to the Kyoto Protocol; (3) identification of areas where additional research is needed in order to advance and align remote sensing technology with the requirements and expectations of the Protocol; and 94) the bureaucratic and research management approaches needed to align the remote sensing community with both the science and policy communities.

Rosenqvist, Ake↗
DOE OSTI2024

Endogenizing Probabilistic Resource Adequacy Risks in Deterministic Capacity Expansion Models

In this work, we demonstrate how power system capacity expansion models can understate the stochastic effects of thermal outages when considering resource availabilities on an hourly expected value basis, yielding system designs with multiple orders of magnitude more shortfall risk than stated adequacy targets. We develop a novel approximation approach to efficiently endogenize awareness of this risk in a deterministic, linear capacity expansion framework. We compare this approach to exogenous tuning of an energy reserve margin, the leading alternative method to compensate for unmodeled probabilistic shortfall risk. Empirical results from a test system show that the new endogenous method cost-effectively meets all regional reliability targets with a single optimization solve, and produces a near-identical system design as the incumbent method without the need for repeated re-optimizations to find an appropriate reserve level. The endogenous method may also use iterative re-optimizations to further improve solution quality, although these incremental benefits were modest in the system studied.

capacity expansion modeling↗
DOE OSTI2023

Assessing the Resource Adequacy and Community Impacts of an Evolving Grid: Considerations for State Regulators

As U.S. power systems continue to decarbonize, state regulators must be able to broadly assess the cost and reliability implications of proposed fossil retirements and the corresponding resources that are coming online to replace them. Specifically, regulators must evaluate whether proposed infrastructure investments are sufficient to ensure the long-term reliability of the system, while also protecting rate payers by ensuring that such investments are necessary and not excessive. Broadly speaking, this objective is typically framed in terms of maintaining long-term resource adequacy at the lowest cost, while also ensuring that other social and/or environmental objectives are satisfied. System planners currently have a host of sophisticated analytical tools at their disposal to evaluate the cost-benefit trade-offs of different approaches to ensuring resource adequacy. However, most of these tools and associated metrics were designed with traditional power systems in mind. Over the past decade, it has become increasingly clear that the metrics and models that have reliably assessed resource adequacy in systems dominated by large thermal and hydropower resources will be insufficient for systems with significant contributions from emerging technologies such as wind, solar and storage. Therefore, in recent years many new metrics and modeling approaches have been developed, and are increasingly being implemented, to meet the needs of the clean energy transition.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1996

The nutritional adequacy of a limited vegan diet for a Controlled Ecological Life-Support System

Purdue University, as well as the Johnson and Kennedy Space Centers and NASA Ames Research Center, are investigating approximately 5-10 plants that will be grown hydroponically to provide not only the energy and nutrients, but also the oxygen for humans habitating in Mars and lunar bases. The growth and nutritional status of rats fed either a control diet (adequate in all macro- and micronutrients) or a strict vegetarian diet consisting of 5 (vegan-5) or 10 (vegan-10) candidate crop species were investigated. In addition, vegan-10 diets were supplemented with mineral and/or vitamin mix at a level similar to the control diets to assess the effect of supplementation on nutrient status. The assessment of inedible plant material as an alternative food source was also investigated. Results of this study demonstrated that consumption of the vegan-10 diet significantly improved weight gain of rats compared to that for rats fed the vegan-5 diet. Mineral supplementation, at a level present in the control diet, to the vegan-10 diet improved growth and nutrient status, but growth was significantly lower compared to the control-fed rats. Inclusion of inedible plant material, high in ash content, improved some indices of nutrient status, without improving growth.

NASA Discipline Number 93-10↗
DOE OSTI2025

Solar and Storage Integration in the U.S. Southeast: Implications for Resource Adequacy

Resource adequacy concerns may be very different in electricity systems that have higher levels of solar and storage, requiring changes to existing planning models. This study explores a novel approach to evaluating resource adequacy under future scenarios with higher solar and storage in the Southeast U.S. It uses NREL’s Probabilistic Resource Adequacy Suite (PRAS), a collection of probabilistic resource adequacy modeling tools, and compares results when interacting PRAS and a portfolio planning tool with a more traditional modeling approach. The results suggest that traditional models perform reasonably well with lower levels of solar PV, but at higher levels of solar probabilistic tools better capture the changes in resource adequacy concerns—such as winter energy availability—associated with higher solar systems. This is the final study in the Preparing Southeast Markets for Reliable and Affordable Integration of Solar into Operations and Planning project. Two prior reports can be found at: Solar and Storage Integration in the Southeastern United States: Economics, Reliability, and Operations. https://emp.lbl.gov/publications/solar-and-storage-integration Solar and Wind Forecast Error Reserve Sharing in a Multi-Utility Region. https://eta-publications.lbl.gov/sites/default/files/2024-11/multiutility_fe_reserve_sharing_final.pdf

14 SOLAR ENERGY↗
NASA NTRS1972

Redundancy management of multiple inertial systems for Space Shuttle.

Failure detection and isolation techniques are developed for application to off-the-shelf type four-gimbaled inertial measurement units such as the KT-70 or Carousel IV. By using simulated boost and entry shuttle trajectories with specific gimbaled IMU models, failure detection thresholds are developed based upon red-line life dependent requirements and warning thresholds are given within the red-line thresholds based upon expected worst case IMU performance. Using these trajectories, established trajectory thresholds, and multiple IMU models, various failure detection and isolation techniques are evaluated for application in both powered and unpowered flight phases. The adequacy of off-the-shelf systems for both attitude and velocity detection methods is evaluated and recommendations for shuttle application are made.

Dove, D. W.↗
DOE OSTI2026

Long-Term Impacts of Constrained Transmission Deployment on the Cost-Reliability Tradeoff

Traditional Resource Adequacy (RA) frameworks in the U.S. undervalue the contributions of inter-regional transmission to resource adequacy during stress periods, focusing on the availability of nameplate capacity instead. However, availability of nameplate capacity does not always translate into electricity delivery, especially during tail events. Moreover, the rapid deployment of energy-limited resources and increasing electricity demand challenge existing resource adequacy frameworks and couple regional electricity demand and availability of supply via transmission. We propose a two-stage framework that goes beyond the existing capacity-centered approaches to reveal the RA contributions of transmission. In the first stage we introduce a multi-objective optimization framework to quantify the merits of transmission expansion via Pareto Frontiers under alternative futures of no transmission investment, primary energy resources availability and demand growth. The second stage focuses on tail events and leverages the results of the first stage to characterize the risk profile of regional consumers across the U.S. under the alternative energy futures. We find that no new transmission can lead to a more expensive and less reliable national grid across scenarios, however, the impact on regional RA can vary. The probabilistic analysis reveals that transmission investments can alleviate the tail risk of consumers, however, the availability of fuel resources does not always alleviate regional tail risks. Our findings inform policymakers and utilities on the prioritization of transmission investments to mitigate the risk of widespread outages, also for tail events, and ensure reliable and affordable electricity delivery to all.

24 POWER TRANSMISSION AND DISTRIBUTION↗