SEARCH · Search NASA

Results for “PLS”

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 109 records · Page 6

All sources NASA NTRS DOE OSTI

DOE OSTI2023

Multi-Sourced Collaboration for the Production and Refining of Rare Elements and Critical Metals (Final Technical Report)

The project objective was to develop a feasible and cost-effective method for recovering rare earth elements (REEs) and critical materials (CMs) from coal and coal byproducts, resulting in high-purity individually separated REEs and CMs. The targeted REEs included Y, Pr, Nd, Gd, Dy, and Sm, with a purity of over 99.5%, while the CMs included Co, Mn, Ga, Sr, Li, Ni, Zn, and Ge, with a purity of over 90%. The project aimed to design a prototype facility capable of producing 1-3 tonnes/day of high-purity REO mixes. The work was divided into four designated circuits: 1) REE extraction and concentration, 2) REE separation and purification, 3) RE metal production, and 4) CM production. To achieve these goals, the project involved 11 tasks, including technology reviews, research, process flow diagram development, mass balance estimation, and preliminary technical-economic analysis. The project team included researchers from the University of Kentucky, University of Alabama and Virginia Tech as well as process specialists from Argonne National Laboratory. MP Materials provided technical support regarding rare earth markets and processing while Alliance Coal performed resource assessment. The project included a market analysis for Nd/Pr, Tb, Dy, Gd, Y, Co, Mn, Li, Sr, Ga, Ni, Zn, and Ge. These analyses provided insights into the supply and demand trends as well as historic and future projections of market price relative to purity requirements for these elements. Two coal resources were selected for the project: the West Kentucky No. 13 (Baker) Seam and an undisclosed lignite resource in the Illinois coal basin. The estimated quantities of REEs in these resources were calculated based on production samples and drilling data. It was estimated that there is adequate supply for an operation producing one metric ton daily of higher purity mixed rare earth oxides (MREO) for approximately 20 years at a site located in western Kentucky. In Circuit 1, project data was obtained from a pilot heap leach and REE concentration facility. It was concluded that the existing circuit, which generated a MREO concentrate, two types of CM mixed products, and Li- and Sr-containing waters, would be suitable feed for circuits 2-4. Data from the first-of-its-kind coal coarse refuse heap leach pilot pad played a crucial role in estimating reliable elemental concentrations of the pregnant leaching solution (PLS). The average total REE concentration in the PLS was found to be 28.6 ppm. In Circuit 2, several concepts were explored including a novel process referred to as solvent-assisted chromatography (SAC). This concept involved a novel columnar reactor that incorporated multiple mixer/settlers, thereby enabling the operation of counter-flowing aqueous and organic phases. Unfortunately, due to project time constraints, a complete fundamental modeling analysis could not be completed to fully evaluate the technology. Molten salt electrowinning was considered as an alternative for circuit 3 following circuit 2 purification circuit utilizing the novel SAC process. A mass and energy balance of Nd reduction to metal in a fluoride containing molten salt electrolyte was conducted. Comparisons were made with the current state of Asian molten salt electrorefining, and potential improvements in siphoning rare earth metals (REM) from the reactor were presented. A cost estimate was performed for the production of 1 tonne per day, which yielded a total of $2.29 million for the nine electrowinning (EW) cells required. The selected option for circuits 2 and 3 was a plasma distillation process, which initially separates rare earth elements (REEs) from other elements. This is followed by selective electrowinning in various ionic liquids. The selection was made on the basis of thermodynamic modeling and experimental data previously published by a project partner. The combination offers an innovative approach to integrated refining and RE metal production. For Circuit 4, an extensive literature review was conducted for the processing of the CMs. The ultimate decision was to utilize a combined plasma and ionic liquid process as well to produce individual high-purity concentrates of Zn, Ni, Co, Mn, and Mg. A separate flowsheet for Li and Sr was recommended, which would yield carbonates of these elements. Due to the lack of suitable experimental data at this time, a process recommendation could not be provided but several methods have been proposed for consideration. Lastly, a techno-economic analysis (TEA) was conducted to assess the effectiveness of the proposed process for further investigation. The TEA results revealed a capital expense (CapEx) of $737 million and an annual operational expense (OpEx) of $220 million. Due to the selected elements, the hypothetical heap leach pad can produce 1 metric tonne per day of REO equivalent, but a conscious decision was made to only treat targeted REEs, resulting in the production of 0.4 metric tonne of REM. An estimated annual revenue of $90.87 million was projected based on standard market pricing information provided by the funding agency. During the TEA, ten different modules were evaluated for costing purposes. The precipitation circuit was identified as the largest single operational expense, followed by the Mg/Mn process due to the amount of treated metal. In terms of capital expenditures, the heap leach process incurred the highest cost, followed by the Mg/Mn process. The scalability of the plasma process is a crucial consideration since the reactors cannot be scaled beyond the largest demonstrated size due to their reliance on surface area of the slag and vapor phase. The purity estimate for the REEs are generally 98%±2% to produce a metal. The purity level being lower than the project objective was due to the lack of specific experimental data needed to tighten the tolerance of the estimates. Based on literature and previous experience, the CMs are estimated as follows; Ga (95%+, metal), Sr (95%+, carbonate), Li (95%+, carbonate), Ni (98%±2%, metal), Zn (95%+, metal sponge), Ge (95%+, metal), Co (98%±2%, metal), and Mn (98%±2%, metal).

01 COAL, LIGNITE, AND PEAT↗

DOE OSTI2022

Near-Infrared Spectroscopy can Predict Anatomical Abundance in Corn Stover

Feedstock heterogeneity is a key challenge impacting the deconstruction and conversion of herbaceous lignocellulosic biomass to biobased fuels, chemicals, and materials. Upstream processing to homogenize biomass feedstock streams into their anatomical components via air classification allows for a more tailored approach to subsequent mechanical and chemical processing. Here, we show that differing corn stover anatomical tissues respond differently to pretreatment and enzymatic hydrolysis and therefore, a one-size-fits-all approach to chemical processing biomass is inappropriate. To inform on-line downstream processing, a robust and high-throughput analytical technique is needed to quantitatively characterize the separated biomass. Predictive correlation of near-infrared spectra to biomass chemical composition is such a technique. Here, we demonstrate the capability of models developed using an “off-the-shelf,” industrially relevant spectrometer with limited spectral range to make strong predictions of both cell wall chemical composition and the relative abundance of anatomical components of the corn stover, the latter for the first time ever. Gaussian process regression (GPR) yields stronger correlations (average R 2 v = 88% for chemical composition and 95% for anatomical relative abundance) than the more commonly used partial least squares (PLS) regression (average R 2 v = 84% for chemical composition and 92% for anatomical relative abundance). In nearly all cases, both GPR and PLS outperform models generated using neural networks. These results highlight the potential for coupling NIRS with predictive models based on GPR due to the potential to yield more robust correlations.

09 BIOMASS FUELS↗

DOE OSTI2022

Comparing Calibration Algorithms for the Rapid Characterization of Pretreated Corn Stover Using Near-Infrared Spectroscopy

Rapid characterization of biomass composition is a key enabling technology for biorefineries—the ability to measure the chemical composition of biomass materials entering the biorefinery as well as the composition of key process intermediate streams would allow real-time process control and the development of robust models to predict process performance. The utility of near-infrared (NIR) spectroscopy for rapid characterization requires multivariate algorithms for building calibration models. The most prevalent algorithm used for building calibration models using NIR spectra is the linear modeling algorithm Partial Least Squares Regression (PLS). Nonlinear regression algorithms (which are typically more computationally intensive than linear modeling approaches) have gained popularity in recent years due to their ability to solve a wide variety of classification and regression problems and the dramatic increase in available computational resources. In this work, we demonstrate that a calibration model can predict the composition of corn stover process intermediate samples pretreated with three different treatments—hot water (HW), dilute acid (DA), and deacetylation followed by dilute acid (DDA). We quantitatively compare three different algorithms for building prediction models based on near-infrared spectroscopy—partial least squares (PLS), support vector machines (SVM), and random forests (RF). We demonstrate the utility of improving model performance by accounting for instrument performance variability using repeated measurements of standard materials (e.g., the “repeatability file” strategy) and investigate its performance with nonlinear regression techniques, and we discuss methods for quantifying the uncertainties of specific predictions among the three methods.

09 BIOMASS FUELS↗

DOE OSTI2024

Leveraging design of experiments to build chemometric models for the quantification of uranium (VI) and HNO3 by Raman spectroscopy

Partial least squares regression (PLSR) and support vector regression (SVR) models were optimized for the quantification of U(VI) (10–320 g L −1 ) and HNO 3 (0.6–6 M) by Raman spectroscopy with optimized calibration sets chosen by optimal design of experiments. The designed approach effectively minimized the number of samples in the calibration set for PLSR and SVR by selecting sample concentrations with a quadratic process model, despite complex confounding and covarying spectral features in the spectra. The top PLS2 model resulted in percent root mean square errors of prediction for U(VI), HNO 3 , and NO 3 − of 3.7%, 3.6%, and 2.9%, respectively. PLS1 models performed similarly despite modeling an analyte with a majority linear response (i.e., uranyl symmetric stretch) and another with more covarying vibrational modes (i.e., HNO 3 ). Partial least squares (PLS) model loadings and regression coefficients were evaluated to better understand the relationship between weaker Raman bands and covarying spectral features. Support vector machine models outperformed PLS1 models, resulting in percent root mean square error of prediction values for U(VI) and HNO 3 of 1.5% and 3.1%, respectively. The optimal nonlinear SVR model was trained using a similar number of samples (11) compared with the PLSR model, even though PLS is a linear modeling approach. The generic D-optimal design presented in this work provides a robust statistical framework for selecting training set samples in disparate two-factor systems. This approach reinforces Raman spectroscopy for the quantification of species relevant to the nuclear fuel cycle and provides a robust chemometric modeling approach to bolster online monitoring in challenging process environments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Improving Prediction of Peroxide Value of Edible Oils Using Regularized Regression Models

We present four unique prediction techniques, combined with multiple data pre-processing methods, utilizing a wide range of both oil types and oil peroxide values (PV) as well as incorporating natural aging for peroxide creation. Samples were PV assayed using a standard starch titration method, AOCS Method Cd 8-53, and used as a verified reference method for PV determination. Near-infrared (NIR) spectra were collected from each sample in two unique optical pathlengths (OPLs), 2 and 24 mm, then fused into a third distinct set. All three sets were used in partial least squares (PLS) regression, ridge regression, LASSO regression, and elastic net regression model calculation. While no individual regression model was established as the best, global models for each regression type and pre-processing method show good agreement between all regression types when performed in their optimal scenarios. Furthermore, small spectral window size boxcar averaging shows prediction accuracy improvements for edible oil PVs. Best-performing models for each regression type are: PLS regression, 25 point boxcar window fused OPL spectral information RMSEP = 2.50; ridge regression, 5 point boxcar window, 24 mm OPL, RMSEP = 2.20; LASSO raw spectral information, 24 mm OPL, RMSEP = 1.80; and elastic net, 10 point boxcar window, 24 mm OPL, RMSEP = 1.91. The results show promising advancements in the development of a full global model for PV determination of edible oils.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS1981

A survey of the plasma electron environment of Jupiter - A view from Voyager

A survey of the plasma environment within Jupiter's bow shock is given in terms of the in situ calibrated electron plasma measurements made between 10 eV and 5.95 keV by the Voyager Plasma Science Experiment (PLS). The measurements are analyzed and corrected for spacecraft potential variations; the data are reduced to nearly model independent macroscopic parameters of the local electron density and temperature. The electron parameters are derived without reference to or internal calibration from the positive ion measurements made in the PLS experiment. Extensive statistical and direct comparisons with other determinations of the local plasma charge density indicate clearly that the analysis procedures have successfully and routinely discriminated between spacecraft sheath and ambient plasmas.

Scudder, J. D.↗

NASA NTRS1983

Survey of low energy plasma electrons in Saturn's magnetosphere: Voyagers 1 and 2

The low energy plasma electron environment within Saturn's magnetosphere was surveyed by the Plasma Science Experiment (PLS) during the Voyager encounters with Saturn. Over the full energy range of the PLS instrument (10 eV to 6 keV) the electron distribution functions are clearly non-Maxwellian in character; they are composed of a cold (thermal) component with Maxwellian shape and a hot (suprathermal) non-Maxwellian component. A large scale positive radial gradient in electron temperature is observed, increasing from less than 1 eV in the inner magnetosphere to as high as 800 eV in the outer magnetosphere. Three fundamentally different plasma regimes were identified from the measurements: (1) the hot outer magnetosphere, (2) the extended plasma sheet, and (3) the inner plasma torus.

Sittler, E. C., Jr.↗

NASA NTRS1983

Plasma electron analysis: Voyager plasma science experiment

The Plasma Science Experiment (PLS) on the Voyager spacecraft provide data on the plasma ions and electrons in the interplanetary medium and the magnetospheres of the giant planets Jupiter and Saturn. A description of the analysis used to obtain electron parameters (density, temperature, etc.) from the plasma science experiment PLS electron measurements which cover the energy range from 10 eV to 5950 eV is presented. The electron sensor (D cup) and its transmission characteristics are described. A derivation of the fundamental analytical expression of the reduced distribution function F(e) is given. The electron distribution function F(e), used in the moment integrations, can be derived from F(e). Positive ions produce a correction current (ion feedthrough) to the measured electron current, which can be important to the measurements of the suprathermal electron component. In the case of Saturn, this correction current, which can either add to or subtract from the measured electron current, is less than 20% of the measured signal at all times. Comments about the corrections introduced by spacecraft charging to the Saturn encounter data, which can be important in regions of high density and shadow when the spacecraft can become negatively charged are introduced.

Sittler, E. C., Jr.↗

NASA NTRS1983

Survey of low-energy plasma electrons in Saturn's magnetosphere - Voyagers 1 and 2

Sittler, E. C., Jr.↗

NASA NTRS1985

In situ measurements of the plasma bulk velocity near the Io flux tube

The flow around the Io flux tube was studied by analyzing the eleven spectra taken by the Voyager 1 Plasma Science (PLS) experiment in its vicinity. The bulk plasma parameters were determined using a procedure that uses the full response function of the instrument and the data in all four PLS sensors. The mass density of the plasma in the vicinity of Io is found to be 22,500 + or - 2,500 amu/cu cm and its electron density is found to be 1500 + or - 200/cu cm. The Alfven speed was determined using three independent methods; the values obtained are consistent and taken together yield V sub A = 300 + or - 50 km/sec, corresponding to an Alfven Mach number of 0.19 + or - 0.02. For the flow pattern, good agreement was found with the model of Neubauer (1980), and it was concluded that the plasma flows around the flux tube with a pattern similar to the flow of an incompressible fluid around a long cylinder obstacle of radius 1.26 + or - 0.1 R sub Io.

Barnett, A.↗

NASA NTRS1986

Thermal ions at Saturn - Plasma parameters and implications

Plasma data from the PLS experiment on Voyagers 1 and 2 are analyzed at the Saturn encounters. Measured ion currents are simulated using the full response function of the PLS instrument assuming plasma distributions are isotropic Maxwellians. The plasma velocity, densities, and temperatures which best simulate the observations are determined. Saturn's magnetosphere is found to subcorotate outside of L = 5.5 for Voyager 1 and L = 7 for Voyager 2. Large radial and vertical flows are observed, especially in the outer magnetosphere and on the nightside. Ion temperatures increase with L to a maximum at L = 10, outside of which they vary rapidly. A temperature anisotropy with T-perpendicular greater than T-parallel is necessary to account for the observed temperatures and densities. The ions present are H(+) and O(+); there is no evidence of heavier ions or higher charge states. Calculations of N(L-squared) show an O(+) peak at L = 10 for both encounters, indicating the major O(+) source is at L = 10.

Richardson, J. D.↗

NASA NTRS1988

Observational and theoretical evidence for anisotropies in Saturn's magnetosphere

A study of plasma anisotropies in Saturn's magnetosphere was conducted using data from the Voyager 1 plasma science (PLS) instrument together with an improved Voyager plasma data analysis routine of Sands (1987) and Sands and McNutt (1988). First, the degree of anisotropy required to reconcile differences in the inbound and outbound Voyager 1 plasma observations was determined. The anisotropies derived from the PLS plasma data were then compared with those required to reconcile inbound-outbound differences in plasma flux shell content. It was found that better fits to the data could be obtained if temperature anisotropies were allowed and that the magnitude of the anisotropies was roughly consistent with those required to provide azimuthal symmetry in the plasma flux tube content.

Richardson, John D.↗

NASA NTRS1988

Net current measurements and secondary electron emission characteristics of the Voyager plasma science experiment and their impact on data interpretation

The Voyager Plasma Science (PLS) instrument is capable of returning integral (DC) current measurements, similar in some respects to measurements made with a Langmuir probe or a retarding potential analyzer, although there are significant differences. The integral measurements were made during a calibration sequence in the solar wind, during Cruise Science Maneuvers, and within the magnetospheres of Jupiter and Saturn by Voyager 1. After the failure of the PLS experiment following the Saturn encounter, that instrument was placed in the DC return mode returning possibly usable data from early 1981 through early 1985. The DC return measurements are difficult to interpret and are above threshold values only for relatively large fluxes; the determination of the measured current level is dependent on the operating temperature of the preamplifiers which further complicates the interpretation. Nevertheless, these measurements can be used to determine the efficiency of the suppressor grid at preventing the loss of secondary electrons off the collector plate. Some DC return measurements have been invaluable in aiding in the interpretation of some electron plasma measurements not previously understood. It is found that electron spectra can be significantly modified by the presence of second generation secondary electrons produced by either first generation secondaries or photoelectrons on the support ring of the negative high voltage modulator grid within the instrument housing.

Mcnutt, Ralph L., Jr.↗

NASA NTRS1991

Personnel launch system autoland development study

The Personnel Launch System (PLS) Autoland Development Study focused on development of the guidance and control system for the approach and landing (A/L) phase and the terminal area energy management (TAEM) phase. In the A/L phase, a straight-in trajectory profile was developed with an initial high glide slope, a pull-up and flare to lower glide slope, and the final flare touchdown. The TAEM system consisted of using a heading alignment cone spiral profile. The PLS autopilot was developed using integral LQG design techniques. The guidance and control design was verified using a nonlinear 6 DOF simulation. Simulation results demonstrated accurate steering during the TAEM phase and adequate autoland performance in the presence of wind turbulence and wind shear.

Bossi, J. A.↗

NASA NTRS1990

Personnel Launch System definition

A lifting-body Personnel Launch System (PLS) is defined for assured manned access to space for future U.S. space missions. The reusable craft described is configured for reliable and safe operations, maintainability, affordability, and improved operability, and could reduce life-cycle costs associated with placing personnel into orbit. Flight simulations show the PLS to be a very flyable vehicle with very little control and propellant expenditure required during entry. The attention to crew safety has resulted in the design of a system that provides protection for the crew throughout the mission profile. However, a new operations philosophy for manned space vehicles must be adopted to fully achieve low-cost, manned earth-to-orbit transportation.

Piland, William M.↗

NASA NTRS1990

The Personnel Launch System

NASA has begun to study candidate vehicles for manned access to space in support of the Space Station or other future missions requiring on-demand transportation of people to and from earth orbit. One such system, which would be used to complement the present Shuttle or an upgraded version, is the Personnel Launch System (PLS), which is envisioned as a reusable priority vehicle to place people and small payloads into orbit using an experimental launch vehicle. The design of the PLS is based on a Space Station crew changeout requirement whereby eight passengers and two crew members are flown to the station and a like number are returned within a 72 hour mission duration. Experimental and computational aerothermodynamic heating studies have been conducted using a new two-color thermographic technique that involved coating the model with a phosphor that radiates at varying color intensities as a function of temperature when illuminated with UV light. A full-scale model, the HL-20, has been produced and will be used for man-machine research. Three launch vehicle concepts are being considered, a Titan IV, the Advanced Launch System, and a Shuttle equipped with liquid rocket boosters.

Piland, William M.↗

NASA NTRS1991

The HL-20 as the personnel launch system

To ensure manned access to space, the Personnel Launch System (PLS) is under consideration by NASA as a complement to the Space Shuttle. Its primary mission will be to transport crew and passengers to and from the Space Station Freedom in low earth orbit (LEO). There are currently two design studies being funded: a biconic, ballistic-shaped vehicle at JSC and a lifting body concept at LaRC. In the late 1950's, both NASA and the Air Force were engaged in the study of lifting bodies for LEO vehicles. Projects included the M2F2 series, the X24 series, and the HL-10. These lifting bodies derive their lift solely from the shape of the fuselage. By the mid-1960's, full scale models were actually built and tested with some success and some failure. Langley's HL-10 was one of the most successful of these projects. However, these studies were temporarily shelved while work progressed on the Space Shuttle. Some of the test results from these studies actually led to concept refinements on certain aspects of the Space Shuttle development. Due to the more recent successes of the Space Shuttle Program and a directive to place a Space Station in orbit, there has been renewed interest in developing a lifting body vehicle as the PLS. The vehicle, the HL-20, is an LaRC Project in the Space Systems Division, involving the efforts of a number of individuals. Data on the research carried out for peer and lay review has been available in hard copy format, but a need existed for actual video footage, combined with scientific visualization technology, for presentation and archival purposes. The purpose of this project was to satisfy this need.

Beam, Sherilee F.↗

NASA NTRS1991

The HL-20 lifting-body personnel launch system

The HL-20 early lifting-body personnel launch system (PSL) research, expected PSL mission requirements, the HL-20 concept design status, and those features which enhance aerodynamic and aerothermodynamic performance, operation, efficiency, maintainability, reliability, and crew safety are described. Results of the HL-20 PLS research to date show that the concept has definite advantages for efficiently satisfying future needs for assured manned access to space. The vehicle is designed with operational efficiency, low life-cycle costs, reliability, and safety as the primary criteria. It is shown that the HL-20 PLS can be developed and put into operation in the same timeframe that the Space Station Freedom is deployed.

Stone, Howard W.↗