SEARCH · Engineering Papers

Results for “two’s complement”

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.

SourceResearch connectionFrom yearThrough year

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

At least 325 records · Page 18

All sources NASA NTRS DOE OSTI

NASA NTRS1978

Interpretation of altimeter data

Two methods are used to interpret the whole range of signals contained in the Geos 3 altimeter data. They each address a different class of events and thus complement each other in their ability to provide information on the state of convection in the earth's mantle. The long wavelength section of the spectrum yields information on the depth of convection cells and the viscosity variations inside those cells through a study of the variations of the admittance as a function of wavelength. The short wavelength section of the spectrum provides information on the evolution of the lithosphere, considered as a thin elastic plate, by studying its response to loads at several points in its evolution. The variation of the flexural rigidity with age is obtained from that study.

Roufosse, M. C.↗

NASA NTRS1991

Failure prediction of thin beryllium sheets used in spacecraft structures

In an attempt to predict failure for cross-rolled beryllium sheet structures, high order macroscopic failure criteria are used. These require the knowledge of in-plane uniaxial and shear strengths. Test results are included for in-plane biaxial tension, uniaxial compression for two different material orientations, and shear. All beryllium specimens have the same chemical composition. In addition, all experimental work was performed in a controlled laboratory environment. Numerical simulation complements these tests. A brief bibliography supplements references listed in a previous report.

Roschke, Paul N.↗

NASA NTRS1993

University of Wisconsin Cirrus Remote Sensing Pilot Experiment

During the period of 26 October 1989 through 6 December 1989 a unique complement of measurements was made at the University of Wisconsin-Madison to study the radiative properties of cirrus clouds. Simultaneous observations were obtained from a scanning lidar, two interferometers, a high spectral resolution lidar, geostationary and polar orbiting satellites, radiosonde launches, and a whole-sky imager. This paper describes the experiment, the instruments deployed, and, as an example, the data collected during one day of the experiment.

Ackerman, Steven A.↗

NASA NTRS2017

An Assessment of Reduced Crew and Single Pilot Operations in Commercial Transport Aircraft Operations

Future reduced crew operations or even single pilot operations for commercial airline and on-demand mobility applications are an active area of research. These changes would reduce the human element and thus, threaten the precept that "a well-trained and well-qualified pilot is the critical center point of aircraft systems safety and an integral safety component of the entire commercial aviation system." NASA recently completed a pilot-in-the-loop high fidelity motion simulation study in partnership with the Federal Aviation Administration (FAA) attempting to quantify the pilot's contribution to flight safety during normal flight and in response to aircraft system failures. Crew complement was used as the experiment independent variable in a between-subjects design. These data show significant increases in workload for single pilot operations, compared to two-crew, with subjective assessments of safety and performance being significantly degraded as well. Nonetheless, in all cases, the pilots were able to overcome the failure mode effects in all crew configurations. These data reflect current-day flight deck equipage and help identify the technologies that may improve two-crew operations and/or possibly enable future reduced crew and/or single pilot operations.

Bailey, Randall E.↗

NASA NTRS2021

In Situ Performance of the Low Frequency Array for Advanced ACTPol

The Advanced Atacama Cosmology Telescope Polarimeter (AdvACT) is an upgrade for the Atacama Cosmology Telescope using Transition Edge Sensor (TES) detector arrays to measure cosmic microwave background (CMB) temperature and polarization anisotropies in multiple frequencies. The low frequency (LF) array was deployed early 2020. It consists of 292 TES bolometers observing in two bands centered at 27 GHz and 39 GHz. At these frequencies, it is sensitive to synchrotron radiation from our galaxy as well as to the CMB, and complements the AdvACT arrays operating at 90, 150 and 230 GHz. We present the initial LF array on-site characterization, including the time constant, optical efficiency and array sensitivity.

Superconducting detectors↗

NASA NTRS2024

Exploring Standing and Reflected Slow-mode Waves in Flaring Coronal Loops: A Parametric Study Using 2.5D MHD Modeling

Abstract Recent observations of reflected propagating and standing slow-mode waves in hot flaring coronal loops have spurred our investigation into their underlying excitation and damping mechanisms. To understand these processes, we conduct 2.5D magnetohydrodynamic (MHD) simulations using an arcade active region model that includes a hot and dense loop. Our simulations allow for in-depth parametric investigations complementing and expanding our previous 3D MHD modeling results. We excite these waves using a large-amplitude, flow pulse applied at one footpoint of the loop in two distinct models as motivated by observations from the Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA). The first model (Model 1) incorporates classical compressive viscosity coefficient, while the second model (Model 2) adopts a 10-times enhanced viscosity coefficient. We obtain the following major results: (1) Our 2.5D MHD simulations reinforce previous conclusions derived from 1D and 3D MHD models that significantly enhanced viscosity is crucial for the rapid excitation of standing slow waves with damping times consistent with observations by Wang et al. (2015). (2)We uncover that nonlinearity in Model 1 delays the conversion of a reflected propagating wave into a standing wave. In contrast, Model 2 exhibits a much weak influence of nonlinearity on the excitation time of standing waves, thanks to the suppression of these effects by enhanced viscosity. (3) Our results reveal that the transverse temperature structure holds more influence on wave behavior than the density structure. In Model 1, increased loop temperature contrast significantly enhances wave trapping within the structure, mitigating the impact of temperature-dependent viscous damping. Conversely, in Model 2, the impact of temperature structure on wave behavior weakens in comparison to the effect of viscosity. (4) Model 1 displays evident nonlinear coupling to the fast and kink magnetoacoustic waves and pronounced wave leakage into the corona. Model 2 exhibits significantly weaker effects in this regard. Analyzing three observed wave events by SDO/AIA aligns with Model 2 predictions, providing further support for the substantial viscosity increase. Our 2.5D study unravels the complex interplay of wave-flow phenomena and nonlinear processes in coronal loops, extending our previous 1D modeling results to incorporate more realistic loop geometry. This provides insights into scenarios where 3D effects may be neglected, thereby enhancing our understanding of the intricate dynamics of the solar corona.

Tongjiang Wang↗

NASA NTRS1989

The Next Generation Space Telescope

In Space Science in the Twenty-First Century, the Space Science Board of the National Research Council identified high-resolution-interferometry and high-throughput instruments as the imperative new initiatives for NASA in astronomy for the two decades spanning 1995 to 2015. In the optical range, the study recommended an 8 to 16-meter space telescope, destined to be the successor of the Hubble Space Telescope (HST), and to complement the ground-based 8 to 10-meter-class telescopes presently under construction. It might seem too early to start planning for a successor to HST. In fact, we are late. The lead time for such major missions is typically 25 years, and HST has been in the making even longer with its inception dating back to the early 1960s. The maturity of space technology and a more substantial technological base may lead to a shorter time scale for the development of the Next Generation Space Telescope (NGST). Optimistically, one could therefore anticipate that NGST be flown as early as 2010. On the other hand, the planned lifetime of HST is 15 years. So, even under the best circumstances, there will be a five year gap between the end of HST and the start of NGST. The purpose of this first workshop dedicated to NGST was to survey its scientific potential and technical challenges. The three-day meeting brought together 130 astronomers and engineers from government, industry and universities. Participants explored the technologies needed for building and operating the observatory, reviewed the current status and future prospects for astronomical instrumentation, and discussed the launch and space support capabilities likely to be available in the next decade. To focus discussion, the invited speakers were asked to base their presentations on two nominal concepts, a 10-meter telescope in space in high earth orbit, and a 16-meter telescope on the moon. The workshop closed with a panel discussion focused mainly on the scientific case, siting, and the programmatic approach needed to bring NGST into being. The essential points of this panel discussion have been incorporated into a series of recommendations that represent the conclusions of the workshop. Speakers were asked to provide manuscripts of their presentation. Those received were reproduced here with only minor editorial changes. The few missing papers have been replaced by the presentation viewgraphs. The discussion that follows each speaker's paper was derived from the question and answer sheets, or if unavailable, from the tapes of the meeting. In the latter case, the editors have made every effort to faithfully represent the discussion.

Bely, Pierre-Yves↗

DOE OSTI2022

Unraveling higher-order contributions to spin excitations probed using resonant inelastic x-ray scattering

Resonant inelastic x-ray scattering (RIXS) is an evolving tool for investigating the spin dynamics of strongly correlated materials, which complements inelastic neutron scattering. In isotropic spin-$\frac{1}{2}$ Heisenberg antiferromagnetic (HAFM) spin chains, both techniques have observed non-spin-conserving (NSC) excitations confined to the two-spinon phase space. However, a recent O K-edge RIXS study of the one-dimensional HAFM Sr 2 CuO 3 observed spin-conserving (SC) four-spinon excitations outside the two-spinon phase space. Here, we demonstrate that analogous four-spinon excitations can also be accessed at the Cu L 3 edge in the related material SrCuO 2 . Through detailed modeling, we establish that these excitations appear in both the SC and NSC channels of the Cu L 3 edge, and are only captured by higher-order terms in the ultrashort core-hole lifetime expansion. Finally, since these terms encode information about spin-spin correlations extending beyond nearest neighbors, our results offer different possibilities for studying nonlocal spin correlations in quantum magnets.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2025

Optimizing Alabama’s CO 2 Storage in Shelby County (Project OASIS): Task 4.0 Deliverable – Geologic Analysis Report

Project OASIS (Optimizing Alabama’s CO 2 Storage in Shelby County) is a geologic and reservoir characterization study designed to evaluate deep saline formations for potential long-term carbon dioxide (CO 2 ) storage in central Alabama near the National Carbon Capture Center (NCCC) and Alabama Power’s Plant Gaston. The project centers on the Cambro-Ordovician Knox Group and underlying strata such as the Conasauga and Rome Formations, which were investigated through the drilling of two stratigraphic test wells to obtain electronic well logs, core, and sidewall core plugs. These data provide direct measurements of porosity, permeability, and lithologic variability critical for reservoir characterization. Complementing the well program, a limited 2D seismic survey was acquired to help select the site for Westover #2, and a more regional Seismic Exchange (SEI) seismic survey was licensed and interpreted to define structural and stratigraphic frameworks in a new Static Earth Model (SEM), map reservoir continuity, and identify potential sealing intervals. Integrated with geologic and reservoir modeling, these datasets form the basis for evaluating storage capacity, injectivity, and containment.

20 FOSSIL-FUELED POWER PLANTS↗

DOE OSTI2025

Optimizing Alabama’s CO 2 Storage in Shelby County (Project OASIS): Task 6.0 Deliverable – CarbonSAFE Phase III Readiness

The OASIS CarbonSAFE Phase II Project OASIS (Optimizing Alabama’s CO 2 Storage in Shelby County) is a geologic and reservoir characterization study designed to evaluate deep saline formations for potential long-term carbon dioxide (CO 2 ) storage in central Alabama near the National Carbon Capture Center (NCCC) and Alabama Power’s Plant Gaston. The project centers on understanding the potential of the Cambro-Ordovician Knox Group and underlying strata such as the Conasauga and Rome Formations for geologic storage of CO 2 . These formations were investigated as part of SECARB-USA (DE-FE0031830) and Project OASIS through the drilling of two stratigraphic test wells to obtain electronic well logs, core, and sidewall core plugs. These data provide direct measurements of porosity, permeability, and lithologic variability critical for reservoir characterization. Complementing the well program, a limited 2D seismic survey was conducted to help select the site for Westover #2 as part of SECARB-USA (DE-FE0031830), and a more regional Seismic Exchange (SEI) seismic survey was licensed and interpreted to define structural and stratigraphic frameworks in a new Static Earth Model (SEM), map reservoir continuity, and to identify potential sealing intervals. Integrated with geologic and reservoir modeling, these datasets form the basis for evaluating storage capacity, injectivity, and containment. While this document endeavors to provide readers with a high-level overview of Project OASIS activities and its suitability for subsequent CarbonSAFE Phases, such as a Phase III effort. Other project deliverables and milestones will provide more details on individual subjects.

20 FOSSIL-FUELED POWER PLANTS↗

NASA NTRS1974

The scientific justification of a radar scatterometer and a passive microwave system on Seasat-A

The purpose of these two systems is to determine the winds over the ocean. The passive system may also provide data on precipitation over the ocean and sea surface temperature through clouds. They complement each other. The radar scatterometer will sense those sea surface properties that define the winds over the ocean through clouds so thick and so wet that the passive microwave system will have detected only the cloud properties. Both wind speed and direction can be found from the combined data to be obtained.

Pierson, W. J.↗

NASA NTRS1995

A New Approach to Measuring Safety with Flight Data

For over two decades, safety has been measured by screening flight data for deviations from prescribed operations. NASA and the FAA are developing a prototype system with a new approach, to complement these event-measurement systems. The premise is that, in addition to these events, much can be gained by analyzing all the flight data on a routine basis. The statistical analyses of this system enable the evaluation of normal as well as extreme operations. The trend analyses make it possible to foresee the potential occurrence of an unsafe operation and intervene before it occurs.

Chappell, Sheryl L.↗

NASA NTRS2008

The International Lunar Network

A new lunar science flight projects line has been introduced within NASA s Science Mission Directorate's (SMDs) proposed 2009 budget, including two new robotic missions designed to accomplish key scientific objectives and, when possible, provide results useful to the Exploration Systems Mission Directorate (ESMD) and the Space Operations Mission Directorate (SOMD) as those organizations grapple with the challenges of returning humans to the Moon. The first mission in this line will be the Lunar Reconnaissance Orbiter, an ESMD mission that will acquire key information for human return to the moon activities, which will transition after one year of operations to the SMD Lunar Science Program for a 2-year nominal science mission. The second mission, the Lunar Atmosphere and Dust Environment Explorer (LADEE) will be launch in 2011 along with the GRAIL Discovery mission to the moon. The third is delivery of two landed payloads as part of the International Lunar Network (ILN). This flight projects line provides a robust robotic lunar science program for the next 8 years and beyond, complements SMD s initiatives to build a robust lunar science community through R&A lines, and increases international participation in NASA s robotic exploration plans. The International Lunar Network is envisioned as a global lunar geophysical network, which fulfills many of the stated recommendations of the recent National Research Council report on The Scientific Context for Exploration of the Moon [2], but is difficult for any single space agency to accomplish on its own. The ILN would provide the necessary global coverage by involving US and international landed missions as individual nodes working together. Ultimately, this network could comprise 8-10 or more nodes operating simultaneously, while minimizing the required contribution from each space agency. Indian, Russian, Japanese, and British landed missions are currently being formulated and SMD is actively seeking partnership with these and other space agencies to establish the ILN.

Cohen, Barbara A.↗

NASA NTRS2018

Real-Time Monitoring and Prediction of Airspace Safety

The U.S. National Airspace System (NAS) has reached an extremely high level of safety in recent years. However, it will only become more difficult to maintain the current level of safety with the forecasted increase in operations, and so the FAA has been making revolutionary changes to the NAS to both expand capacity and ensure safety. Our work complements these efforts by developing a novel model-based framework for real-time monitoring and prediction of the safety of the NAS. Our framework is divided into two parts: (offline) safety analysis and modeling part, and a real-time (online) monitoring and prediction of safety. The goal of the safety analysis task is to identify hazards to flight (distilled from several national databases) and to codify these hazards within our framework such that we can monitor and predict them. From these we define safety metrics that can be monitored and predicted using dynamic models of airspace operations, aircraft, and weather, along with a rigorous, mathematical treatment of uncertainty. We demonstrate our overall approach and highlight the advantages of this approach over the current state-of-the-art through simulated scenarios.

safety metrics↗

NASA NTRS2021

Simulation Study for Interoperability of Urban Air Mobility Scheduling and Separation Services in Ideal Conditions

Provision of strategic scheduling and tactical separation services is vital to the safe and efficient operation of vehicles in the urban airspace. This paper describes the efforts made towards the integration of two such services in a simulation environment under ideal conditions and the subsequent studies done on evaluation of system performance. The scheduling and separation services are set up to complement each other to ensure safe separation between airborne aircraft. The utility of these services will become important as the level of traffic increases. This paper describes the simulation experiments conducted to identify cases where the system performance measured by the number of observed losses of separation degrades even with the scheduling and separation services active. From the results obtained, we identify conditions under which the required maneuvers increase and when we observe airborne conflicts even with separation service active. Results obtained will inform requirements for future advancements both in these services independently and in their joint operations.

Urban Air Mobility↗

NASA NTRSDate not supplied

Simulation Study for Interoperability of Urban Air Mobility Scheduling and Separation Services in Ideal Conditions

Urban Air Mobility↗

NASA NTRSDate not supplied

Flow Physics Study of Sweeping Jet Actuation on an NACA 0015 Swept Wing Configuration

Results from a recently completed active flow control (AFC) experiment on a low aspect ratio, AR = 4.35, 30 degree swept, semispan wing with a 30% chord trailing edge flap are presented. The constant chord NACA 0015 wing is configured with sweeping jet actuators at the flap shoulder to facilitate our study of three-dimensional, swept wing separated and AFC controlled flowfields on the flap. Two flap deflection angles (delta_f = 0 degrees and 20 degrees) are examined. Oil and tuft flow visualization data, steady and unsteady pressure data, and particle image velocimetry (PIV) complement the balance lift and drag data. These results are used to examine smooth body separation, fixed separation, and the AFC-controlled flap flowfield downstream of a sweeping jet actuator. A momentum coefficient of 1.1% reattaches the flow to the flap surface when flap delta_f = 20 degrees increasing lift by approximately 0.26. This fundamental study is a first step in a research effort focused on improving the efficiency of AFC systems for swept wing applications.

active flow control↗

NASA NTRSDate not supplied

Validation of Fitness for Duty Standards Using Pre- and Post-Flight Capsule Egress and Suited Functional Performance Tasks in Simulated Reduced Gravity (Pilot Egress Fitness)

As NASA prepares for exploration missions, it will be critical to understand and build upon known crew capabilities. Specifically, we need to know the functional capacities of crew at different stages of a mission and characterize these profiles so that the appropriate vehicle requirements and mission concepts of operations (ConOps) can be developed. One of the most complex phases of any missions is when there is a transition between gravity environments. For instance, both physiological adaptation to microgravity and subsequent re-entry into a gravity environment result in reduced functional capacity, even with rigorous adherence to inflight countermeasures. Quantification of the astronauts’ post-landing functional performance is necessary to design ConOps for exploration missions. Specifically, these two high-risk tasks may have to be performed soon after gravity transitions: •Unassisted capsule egress task after return to Earth •Planetary extravehicular activity (EVA) soon after landing on Mars or the Moon This study has been broken down into two phases. A pilot phase to assess the overall feasibility and demonstrate the capability to do these tasks shortly after landing and the full Egress Fitness study, which will be part of the CIPHER complement. This study uses a functional task approach to characterize performance of these high-risk tasks in long-duration ISS crewmembers before flight and shortly after return to Earth. Prior to any testing, each astronaut subject completes a suit fit check to ensure adequate sizing and mobility to be able to complete the EVA tasks. Pilot Egress Fitness pre-flight and post-flight testing includes an Earth based emergency egress out of a functional capsule mockup, and a short Mars gravity EVA simulation including suit donning, hatch egress, ladder descent, task board cable operations, baggage transfer over sand/rocky regolith, alignment with a rear entry port, and suit egress. Pre-flight testing can occur almost anytime pre-flight, but post-flight scheduling is much more critical with the capsule egress test occurring 1-4 hours after landing and the planetary EVA approximately 18-36 hours after landing. Data collected for both tasks includes task completion time, photo, and video. The EVA portion also includes collection of metabolic and heart rate. Pilot Egress Fitness study has completed baseline pre-flight testing on 3 astronaut subjects. Post-flight testing of the first two subjects will be completed in November 2021 and the final subject around March 2022. Results and lessons learned from this pilot study will inform the full Egress Fitness study, which will incorporate additional pre-flight sessions, longer EVA tasks, and post-flight testing on R+1, 4, and 7 to characterize the timeframe of recovery

J R Norcross↗