Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “phase state”

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 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Microphysical growth state of ice particles and large-scale electrical structure of clouds

Cloud temperature, liquid water content, and vertical air velocity are all considered in evaluating the microphysical growth state of ice phase precipitation particles in the atmosphere. The large-scale observations taken together with in situ measurements indicated that the most prevalent growth condition for large ice particles in active convection is sublimation during riming, whereas the most prevalent growth condition in stratiform precipitation is vapor deposition. The large-scale electrical observations lend further support to the idea that particles warmed by riming into sublimation charge negatively and particles in vapor deposition charge positively in collisions with small ice particles.

Williams, Earle↗
NASA NTRS2000

Implications of SWAS Observations for Interstellar Chemistry and Star Formation

A long standing prediction of steady state gas-phase chemical theory is that H2O and O2 are important reservoirs of elemental oxygen and major coolants of the interstellar medium. Analysis of SWAS observations has set sensitive upper limits on the abundance Of O2 and has provided H2O abundances toward a variety of star forming regions. Based on these results, we show that gaseous H2O and O2 are not dominant carriers of elemental oxygen in molecular clouds. Instead the available oxygen is presumably frozen on dust grains in the form of molecular ices, with a significant portion potentially remaining in atomic form, along with CO, in the gas phase. H2O and O2 are also not significant coolants for quiescent molecular gas. In the case of H2O, a number of known chemical processes can locally elevate its abundance in regions with enhanced temperatures, such as warm regions surrounding young stars or in hot shocked gas. Thus, water can be a locally important coolant. The new information provided by SWAS, when combined with recent results from the Infrared Space Observatory, also provide several hard observational constraints for theoretical models of the chemistry in molecular clouds and we discuss various models that satisfy these conditions.

Bergin, Edwin A.↗
NASA NTRS2004

Sintering of BaCe(0.85)Y(0.15)O3-(Beta) With/Without SrTiO Dopant

The sintering behavior of BaCe(0.85)Y(0.15)O3-(Beta) doped with SrTiO is described. Complete reaction and crystallization of perovskite phase by solid state was achieved by calcining at 1200 degrees C for 24 hours.Smaples were sintered at 1450 degrees C, 1550 degrees C, and 1650 degrees C. SrTiOsub3 enhanced sintering, while optimal dopant level was different for powders synthesized by solid state and co-precipitation. Both powders exhibit similar grain growth behavior.

Dynys, Fred↗
NASA NTRS1998

Drug marker absorption in relation to pellet size, gastric motility and viscous meals in humans

PURPOSE: The objective of this study was to evaluate drug marker absorption in relation to the gastric emptying (GE) of 0.7 mm and 3.6 mm enteric coated pellets as a function of viscosity and the underlying gastric motility. METHODS: Twelve subjects were evaluated in a 3-way crossover study. 0.7 mm caffeine and 3.6 mm acetaminophen enteric coated pellets were concurrently administered with a viscous caloric meal at the levels of 4000, 6000 and 8000 cP. Gastric motility was simultaneously measured with antral manometry and compared to time events in the plasma profiles of the drug markers. RESULTS: Caffeine, from the 0.7 mm pellets, was observed significantly earlier in the plasma than acetaminophen, from the 3.6 mm pellets, at all levels of viscosity. Motility related size differentiated GE was consistently observed at all viscosity levels, however, less variability was observed with the 4000 cP meal. Specifically, the onset of absorption from the of 3.6 mm pellets correlated with the onset of Phase II fasted state contractions (r = 0.929, p < 0.01). CONCLUSIONS: The timeframe of drug marker absorption and the onset of motility events were not altered within the range of viscosities evaluated. Rather, the differences in drug marker profiles from the non-digestible solids were most likely the result of the interaction between viscosity and motility influencing antral flow dynamics. The administration of the two sizes of pellets and a viscous caloric meal with subsequent monitoring of drug marker profiles is useful as a reference to assess the influence of motility patterns on the absorption profile of orally administered agents.

NASA Center JSC↗
NASA NTRS2012

Containerless Processing Studies in the MSFC Electrostatic Levitator

Levitation or containerless processing represents an important tool in materials research. Levitated specimens are free from contact with a container, which permits studies of deeply undercooled melts, and high-temperature, highly reactive materials. Containerless processing provides data for studies of thermophysical properties, phase equilibria, metastable state formation, microstructure formation, undercooling, and nucleation. Levitation techniques include: acoustic, aero-acoustic, electromagnetic, and electrostatic. In microgravity, levitation can be achieved with greatly reduced positioning forces. Microgravity also reduces the effects of buoyancy and sedimentation in melts. The European Space Agency (ESA) and the German Aerospace Center (DLR) jointly developed an electromagnetic levitator facility (MSL-EML) for containerless materials processing in space. The MSL-EML will be accommodated in the European Columbus Facility on the International Space Station (ISS). The electrostatic levitator (ESL) facility at the Marshall Space Flight Center provides support for the development of containerless processing studies for the ISS. The capabilities of the facility and recent results will be discussed.

Rogers, J. R.↗
NASA NTRS2012

Global Precipitation Measurement (GPM) Safety Inhibit Timeline Tool

The Global Precipitation Measurement (GPM) Observatory is a joint mission under the partnership by National Aeronautics and Space Administration (NASA) and the Japan Aerospace Exploration Agency (JAXA), Japan. The NASA Goddard Space Flight Center (GSFC) has the lead management responsibility for NASA on GPM. The GPM program will measure precipitation on a global basis with sufficient quality, Earth coverage, and sampling to improve prediction of the Earth's climate, weather, and specific components of the global water cycle. As part of the development process, NASA built the spacecraft (built in-house at GSFC) and provided one instrument (GPM Microwave Imager (GMI) developed by Ball Aerospace) JAXA provided the launch vehicle (H2-A by MHI) and provided one instrument (Dual-Frequency Precipitation Radar (DPR) developed by NTSpace). Each instrument developer provided a safety assessment which was incorporated into the NASA GPM Safety Hazard Assessment. Inhibit design was reviewed for hazardous subsystems which included the High Gain Antenna System (HGAS) deployment, solar array deployment, transmitter turn on, propulsion system release, GMI deployment, and DPR radar turn on. The safety inhibits for these listed hazards are controlled by software. GPM developed a "pathfinder" approach for reviewing software that controls the electrical inhibits. This is one of the first GSFC in-house programs that extensively used software controls. The GPM safety team developed a methodology to document software safety as part of the standard hazard report. As part of this process a new tool "safety inhibit time line" was created for management of inhibits and their controls during spacecraft buildup and testing during 1& Tat GSFC and at the Range in Japan. In addition to understanding inhibits and controls during 1& T the tool allows the safety analyst to better communicate with others the changes in inhibit states with each phase of hardware and software testing. The tool was very useful for communicating compliance with safety requirements especially when working with a foreign partner.

Dion, Shirley↗
NASA NTRS2014

GPM Timeline Inhibits For IT Processing

The Safety Inhibit Timeline Tool was created as one approach to capturing and understanding inhibits and controls from IT through launch. Global Precipitation Measurement (GPM) Mission, which launched from Japan in March 2014, was a joint mission under a partnership between the National Aeronautics and Space Administration (NASA) and the Japan Aerospace Exploration Agency (JAXA). GPM was one of the first NASA Goddard in-house programs that extensively used software controls. Using this tool during the GPM buildup allowed a thorough review of inhibit and safety critical software design for hazardous subsystems such as the high gain antenna boom, solar array, and instrument deployments, transmitter turn-on, propulsion system release, and instrument radar turn-on. The GPM safety team developed a methodology to document software safety as part of the standard hazard report. As a result of this process, a new tool safety inhibit timeline was created for management of inhibits and their controls during spacecraft buildup and testing during IT at GSFC and at the launch range in Japan. The Safety Inhibit Timeline Tool was a pathfinder approach for reviewing software that controls the electrical inhibits. The Safety Inhibit Timeline Tool strengthens the Safety Analysts understanding of the removal of inhibits during the IT process with safety critical software. With this tool, the Safety Analyst can confirm proper safe configuration of a spacecraft during each IT test, track inhibit and software configuration changes, and assess software criticality. In addition to understanding inhibits and controls during IT, the tool allows the Safety Analyst to better communicate to engineers and management the changes in inhibit states with each phase of hardware and software testing and the impact of safety risks. Lessons learned from participating in the GPM campaign at NASA and JAXA will be discussed during this session.

Inhibits↗
NASA NTRS2015

Lidar Observations of Atmospheric CO2 Column During 2014 Summer Flight Campaigns

Advanced knowledge in atmospheric CO2 is critical in reducing large uncertainties in predictions of the Earth' future climate. Thus, Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) from space was recommended by the U.S. National Research Council to NASA. As part of the preparation for the ASCENDS mission, NASA Langley Research Center (LaRC) and Exelis, Inc. have been collaborating in development and demonstration of the Intensity-Modulated Continuous-Wave (IM-CW) lidar approach for measuring atmospheric CO2 column from space. Airborne laser absorption lidars such as the Multi-Functional Fiber Laser Lidar (MFLL) and ASCENDS CarbonHawk Experiment Simulator (ACES) operating in the 1.57 micron CO2 absorption band have been developed and tested to obtain precise atmospheric CO2 column measurements using integrated path differential absorption technique and to evaluate the potential of the space ASCENDS mission. This presentation reports the results of our lidar atmospheric CO2 column measurements from 2014 summer flight campaign. Analysis shows that for the 27 Aug OCO-2 under flight over northern California forest regions, significant variations of CO2 column approximately 2 ppm) in the lower troposphere have been observed, which may be a challenge for space measurements owing to complicated topographic condition, heterogeneity of surface reflection and difference in vegetation evapotranspiration. Compared to the observed 2011 summer CO2 drawdown (about 8 ppm) over mid-west, 2014 summer drawdown in the same region measured was much weak (approximately 3 ppm). The observed drawdown difference could be the results of the changes in both meteorological states and the phases of growing seasons. Individual lidar CO2 column measurements of 0.1-s integration were within 1-2 ppm of the CO2 estimates obtained from on-board in-situ sensors. For weak surface reflection conditions such as ocean surfaces, the 1- s integrated signal-to-noise ratio (SNR) of lidar measurements at 11 km altitude reached 376, which was equivalent to a 10-s CO2 error 0.33 ppm. For the entire processed 2014 summer flight campaign data, the mean differences between lidar remote sensed and in-situ estimated CO2 values were about -0.013 ppm. These results indicate that current laser absorption lidar approach could meet space measurement requirements for CO2 science goals.

Lin, Bing↗
NASA NTRS2017

ISRU-Based Robotic Construction Technologies For Lunar And Martian Infrastructures

Economically viable and reliable building systems and tool sets are being sought, examined and tested for extraterrestrial infrastructure buildup. This project utilizes a unique architecture weaving the robotic building construction technology with designs for assisting rapid buildup of initial operational capability Lunar and Martian bases. The project intends to develop and test methodologies to construct certain crucial infrastructure elements in order to evaluate the merits, limitations and feasibility of adapting and using such technologies for extraterrestrial application. High priority infrastructure elements suggested by our NASA advisors to be considered include landing pads and aprons, roads, blast walls and shade walls, thermal and micrometeorite protection shields and dust-free platforms utilizing the well-known insitu resource utilization (ISRU) strategy. Current extraterrestrial settlement buildup philosophy holds that in order to minimize the materials needed to be flown in, at great transportation costs, strategies that maximize the use of locally available resources must be adopted. Tools and heavy equipment flown as cargo from Earth are proposed to build required infrastructure to support future missions and settlements on the Moon and Mars. Several unique systems including the Lunar Electric Rover, the unpressurized Chariot rover, the versatile light-weight crane and Tri-Athlete cargo transporter as well as the habitat module mockups and a new generation of spacesuits are undergoing coordinated tests at NASAs D-RATS. This project intends to draw up a detailed synergetic plan to utilize these maturing systems coupled with modern robotic fabrication technologies based primarily on 3D Printing, tailored for swift and reliable Lunar and Martian infrastructure development. This project also intends to increase astronaut safety, improve buildup performance, ameliorate dust interference and concerns, and reduce time-to-commission, all in an economic manner. The goal stated in our Phase I proposal was a high fidelity demonstration at D-RATS to be conducted at the conclusion of the Phase II study. In the course of the Phase I study, however, it became clear that such demonstration was neither possible (due to the maximum Phase II budget limitation and the cost of NASA assets and related overhead expenses to support such demonstrations), nor necessary (due to NASA's low TRL expectation of Phase II results). These important facts were revealed to us only after interacting with the NIAC administrators and meetings with potential future partners at JPL and KSC. Accordingly, it was decided by the team that in order to make best use of resources we should investigate novel directions in the adaptation of our fabrication technologies by using in-house laboratories and to produce truly useful technologies and data, and then proceed with high fidelity demonstration at a later opportunity when sufficient resources become available. Furthermore, we have recognized that in addition to our building scale 3D printing technology called Contour Crafting, variations of some of our other fabrication technologies under development are suitable for construction of infrastructure elements such as regolith based ceramic tiles and hence we have decided to include some related preliminary research in this Phase II proposal.

Extraterrestrial↗
NASA NTRS2018

An Intelligent Propulsion Control Architecture to Enable More Autonomous Vehicle Operation

This paper describes an intelligent propulsion control architecture that coordinates with the flight control to reduce the amount of pilot intervention required to operate the vehicle. Objectives of the architecture include the ability to: automatically recognize the aircraft operating state and flight phase; configure engine control to optimize performance with knowledge of engine condition and capability; enhance aircraft performance by coordinating propulsion control with flight control; and recognize off-nominal propulsion situations and to respond to them autonomously. The hierarchical intelligent propulsion system control can be decomposed into a propulsion system level and an individual engine level. The architecture is designed to be flexible to accommodate evolving requirements, adapt to technology improvements, and maintain safety.

autonomy↗
NASA NTRS2017

An Intelligent Propulsion Control Architecture to Enable More Autonomous Vehicle Operation

This paper describes an intelligent propulsion control architecture that coordinates with the flight control to reduce the amount of pilot intervention required to operate the vehicle. Objectives of the architecture include the ability to: automatically recognize the aircraft operating state and flight phase; configure engine control to optimize performance with knowledge of engine condition and capability; enhance aircraft performance by coordinating propulsion control with flight control; and recognize off-nominal propulsion situations and to respond to them autonomously. The hierarchical intelligent propulsion system control can be decomposed into a propulsion system level and an individual engine level. The architecture is designed to be flexible to accommodate evolving requirements, adapt to technology improvements, and maintain safety.

autonomy↗
NASA NTRS2020

Organic Matter in the Aguas Zarcas (CM2) Meteorite: High Abundance of Aliphatic Carbon in Metal-Rich Lithology

The Aguas Zarcas meteorite is a new CM2 chondrite which fell on 23 April 2019 (local time) in Costa Rica. Aguas Zarcas is brecciated and contains several different lithologies, e.g., metal-rich lithology and CI-like lithology. This fresh CM2 chondrite gives us good op-portunities for analyses of organic matter (OM) without terrestrial contamination and weathering, particularly some stones which were collected before rain fell over the fall site. We also aim to characterize local hetero-geneities and associations of organic and mineral phases using state-of-the-art microscopic techniques to con-strain the origin and evolutionally processes of OM during pre- and post-accretion.

Kebukawa, Y.↗
NASA NTRS2020

Aircraft System Identification from Multisine Inputs and Frequency Responses

The identification of aircraft flight dynamics is often performed using frequency responses, which are nonparametric models that quantify the steady-state magnitude and phase of a dynamic system response to sinusoidal inputs, as a function of frequency. Frequency responses are computed from measured input and output data, and then model parameters, such as stability and control derivatives, are estimated to best fit a parametric model to the empirical frequency response data. The utility of this approach is due to the familiarity of engineers with frequency responses, a number of theoretical and practical advantages under specific conditions, the availability of software packages, and many other reasons.

System identification↗
NASA NTRS2020

Turbulent mixing in supercritical jets: effect of compressibility factor and inflow condition

Fuel injection and turbulent mixing at supercritical pressures determines ignition and combustion in numerous engineering applications. Flow evolution under such conditions is characterized by strong non-linear coupling between dynamics, transport coefficients, and thermodynamics. Experimental studies observe that the jets injected at supercritical pressures exhibit significantly different dynamics from the jets at subcritical conditions, owing to the lack of distinct liquid and gas phases in supercritical state. Thus, the averaged flow quantities such as the potential core length, jet spatial growth rate and velocity decay profiles differ in the two conditions, resulting in different mixed-fluid distributions. In this study, turbulent jet direct numerical simulations (DNS) are performed to examine the variations in flow statistics between injection of Nitrogen (N₂) in Nitrogen (N₂) at both subcritical (perfect-gas) and supercritical conditions. In all cases, isothermal round jets at Reynolds number (Re_{D}), based on jet diameter (D) and jet orifice velocity (U₀), of 5000 are considered. For mixing analyses, a passive scalar transported with the flow is examined.

Sharan, Nek↗
DOE OSTI2024

Development of a rate-based ENRTL-RK process model for a water-lean solvent

Advanced water-lean solvents (WLS) for post-combustion CO2 capture offer several advantages over the aqueous amine solvents . WLS have lower parasitic energy penalty, lower corrosion, lower temperature and high-pressure CO2 regeneration leading to lower cost of CO2 capture. RTI International, with funding from the US Department of Energy, has been developing its novel water-lean solvent, that has shown specific reboiler duty of 2.3 GJ/t-CO2 at the 60-kWe pilot testing unit (Tiller Plant, SINTEF, Norway) and 2.6 GJ/t-CO2 at the engineering scale testing system (12 MWe) at the Technology Centre Mongstad (TCM) in Norway. All heat duties, including the one from TCM testing, were consistent with Aspen Plus modeling of the specific configuration of each test plant. This work focuses on the development of a detailed process model using in-house laboratory measurements and process data at pilot scale. The eNTRL-RK model used in this work is based on an unsymmetric activity coefficient model with the reference states chosen to be pure liquids for solvents and ideal dilute solution at unit solute molality (resulting in activity coefficient of unity at infinite dilution) for electrolytes. It uses the Redlich-Kwong equation of state for vapor phase properties and Henry’s law for solubility of supercritical gases. The model was validated using process data from the pilot-scale campaign at the Tiller plant, and the engineering scale test campaign at TCM. Data on CO2 capture rate, absorber, and regenerator temperature profiles and specific reboiler duties from two different test campaigns at Tiller and TCM, were used to further refine and validate the model and the model compares favorably to experimental data. The validation results against TCM campaign will be presented in this work.

CO2 capture↗
DOE OSTI2024

Ultrafast state-selective tunneling in two-dimensional semiconductors with a phase- and amplitude-controlled THz-scanning tunneling microscope

THz-pulse driven scanning tunneling microscopy (THz-STM) enables access to the ultrafast quantum dynamics of low-dimensional material systems at simultaneous ultrafast temporal and atomic spatial resolution. State-selective tunneling requires precise amplitude and phase control of the THz pulses combined with quantitative near-field waveform characterization. Here, we employ our state-of-the-art THz-STM with multi-MHz repetition rates, efficient THz generation, and precisely tunable THz waveforms to investigate a single sulfur vacancy in monolayer MoS2. We demonstrate that 2D transition metal dichalcogenides (TMDs) are an ideal platform for near-field waveform sampling by THz cross-correlation. Furthermore, we determine the THz voltage via QEV scans, which measure the THz rectified charge Q as a function of THz field amplitude E and dc bias Vdc. Mapping the complex energy landscape of localized states with a resolution down to 0.01 electrons per pulse facilitates state-selective tunneling to the HOMO and LUMO orbitals of a charged sulfur vacancy.

Materials Science↗
DOE OSTI2022

Dissipative Floquet Dynamics: from Steady State to Measurement Induced Criticality in Trapped-ion Chains

Quantum systems evolving unitarily and subject to quantum measurements exhibit various types of non-equilibrium phase transitions, arising from the competition between unitary evolution and measurements. Dissipative phase transitions in steady states of time-independent Liouvillians and measurement induced phase transitions at the level of quantum trajectories are two primary examples of such transitions. Investigating a many-body spin system subject to periodic resetting measurements, we argue that many-body dissipative Floquet dynamics provides a natural framework to analyze both types of transitions. We show that a dissipative phase transition between a ferromagnetic ordered phase and a paramagnetic disordered phase emerges for long-range systems as a function of measurement probabilities. A measurement induced transition of the entanglement entropy between volume law scaling and sub-volume law scaling is also present, and is distinct from the ordering transition. The two phases correspond to an error-correcting and a quantum-Zeno regimes, respectively. The ferromagnetic phase is lost for short range interactions, while the volume law phase of the entanglement is enhanced. An analysis of multifractal properties of wave function in Hilbert space provides a common perspective on both types of transitions in the system. Our findings are immediately relevant to trapped ion experiments, for which we detail a blueprint proposal based on currently available platforms.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗