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Results for “phase analysis”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

A Comparative Analysis of Phase-Change Wastewater Processing Approaches for Microgravity

Two phase-change wastewater processing candidates, the ISS Vapor Compression Distillation (VCD) System and the Cascade Distiller System (CDS), are compared based on dynamic modeling of both technologies. Differences in fluid handling and energy recovery for the technologies are described and contrasted. Model predictions are presented showing how temperatures, pressures, and compositions vary locally within each distiller. These dynamic variations are difficult to observe experimentally and have implications regarding non-condensable buildup and salt precipitation potential. Alternative architectures involving VCD and CDS components are analyzed in terms of predicted performance and equivalent system mass (ESM). The addition of a downstream brine processor to increase water recovery is also evaluated. Options for reducing overall ESM are discussed, including the possibility of developing a single precipitation-tolerant primary wastewater processor.

Lange, Kevin↗
NASA NTRS1991

A new look at dust and clouds in the Mars atmosphere - Analysis of emission-phase-function sequences from global Viking IRTM observations

The present analysis of emission-phase function (EPF) observations from the IR thermal mapper aboard the Viking Orbiter encompasses polar latitudes, and Viking Lander sites, and spans a wide range of solar longitudes. A multiple scattering radiative transfer model which incorporates a bidirectional phase function for the surface and atmospheric scattering by dust and clouds yields surface albedos and dust and ice optical properties and optical depths for the variety of Mars conditions. It is possible to fit all analyzed EPF sequences corresponding to dust scattering with an albedo of 0.92, rather than the 0.86 given by Pollack et al. on the bases of Viking Lander observations.

Clancy, R. T.↗
DOE OSTI2020

Analysis of Allison Scanner Phase Portraits Using Action-Phase Coordinates

Allison scanners provide detailed information on the beam transverse phase space. An effective way for analyzing the beam distribution from these measurements is to use action-phase coordinates, where beam propagation in a linear lattice is reduced to advancing the phase. This report presents such analysis for measurements performed with a 2.1 MeV, 5 mA H⁻ beam in the MEBT of the PIP2IT test accelerator at Fermilab. In part, with the choice of calculating the Twiss parameters over the high intensity portion of the beam, the beam core is found to be phase-independent with intensity decreasing exponentially with action, while the beam tails exhibit a clear phase dependence that is stable over the beam line.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Data-Driven Global Sensitivity Analysis of Three-Phase Distribution System with PVs

Global sensitivity analysis (GSA) of distribution system with respect to stochastic PV variations plays an important role in designing optimal voltage control schemes. This paper proposes a Kriging, i.e., Gaussian process modeling enabled data-driven GSA method. The key idea is to develop a surrogate model that captures the hidden global relationship between voltage and real and reactive power injections from the historical data. With the surrogate model, the Sobol index can be conveniently calculated to assess the global sensitivity of voltage to various power injection variations. Comparison results with other model-based GSA methods on the IEEE 37-bus feeder, such as the polynomial chaos expansion and the Monte Carlo approaches demonstrate that the proposed method can achieve accurate GSA outcomes while maintaining high computational efficiency.

distribution system analysis↗
NASA NTRS1973

The second order gravitational redshift: Tracking analysis study

A first-phase, perturbation analysis is presented for the tracking requirements necessary for the measurement of the second-order redshift in a heliocentric probe experiment. The clock performance required for such an experiment is also investigated.

Jaffe, J.↗
DOE OSTI2022

Phase identification using statistical analysis

A device includes at least one processor configured to determine, based on (i) a first plurality of time-varying electrical measurements corresponding to a feeder head of a power distribution network having a plurality of phases and (ii) a second plurality of time-varying electrical measurements corresponding to a node in the power distribution network, and using statistical analysis, a predicted phase, from the plurality of phases, that corresponds to the node. The processor may be configured to use ranked correlation coefficients (such as the Kendall rank correlation coefficient) to determine the predicted phase and may use principle component analysis. The processor is also configured to cause at least one device of the power distribution network to modify operation based at least on part on the predicted phase.

Veda, Santosh Sambamoorthy↗
NASA NTRS1987

A combined Eulerian-Lagrangian analysis for computation of two-phase flows

A combined Eulerian-Lagrangian analysis, which combines a linearized block implicit Navier-Stokes analysis for the continuous phase with a Lagrangian analysis for the motion of the droplet phase to simulate evaporating two-phase flows, has been developed. A unique aspect of this analysis is that the Lagrangian equations for the droplet motion have been transformed into the Eulerian computational space using coordinate transformation resulting in better computational efficiency. Use of the present implicit procedure for the continuous phase makes it possible to efficiently use a locally highly refined mesh. The coupling of the continuous phase and the droplet phase analyses is such that it allows the use of convergence acceleration techniques for steady-state problems, as well as making it possible to simulate transient flows. A rapidly evaporating two-phase flow caused by spray of liquid nitrogen in gaseous nitrogen has been used as a test problem to demonstrate the computer code using this analysis.

Sabnis, J. S.↗
DOE OSTI2022

Time-of-Flight Calculations with Multiple Beam Phase Monitors: Calibration, Jitter Analysis & Energy Measurement

This report describes time-of-flight (ToF) beam energy measurements with multiple phase monitors in a beam line with no acceleration. Measurement uncertainty is quantified via rigorous treatment of beam-based phase monitor calibration and jitter analysis of the accelerator system. Experimental results in the Superconducting Linac (SCL) of the Spallation Neutron Source (SNS) are presented.

43 PARTICLE ACCELERATORS↗
NASA NTRS2001

Robust Strategy for Rocket Engine Health Monitoring

Monitoring the health of rocket engine systems is essentially a two-phase process. The acquisition phase involves sensing physical conditions at selected locations, converting physical inputs to electrical signals, conditioning the signals as appropriate to establish scale or filter interference, and recording results in a form that is easy to interpret. The inference phase involves analysis of results from the acquisition phase, comparison of analysis results to established health measures, and assessment of health indications. A variety of analytical tools may be employed in the inference phase of health monitoring. These tools can be separated into three broad categories: statistical, rule based, and model based. Statistical methods can provide excellent comparative measures of engine operating health. They require well-characterized data from an ensemble of "typical" engines, or "golden" data from a specific test assumed to define the operating norm in order to establish reliable comparative measures. Statistical methods are generally suitable for real-time health monitoring because they do not deal with the physical complexities of engine operation. The utility of statistical methods in rocket engine health monitoring is hindered by practical limits on the quantity and quality of available data. This is due to the difficulty and high cost of data acquisition, the limited number of available test engines, and the problem of simulating flight conditions in ground test facilities. In addition, statistical methods incur a penalty for disregarding flow complexity and are therefore limited in their ability to define performance shift causality. Rule based methods infer the health state of the engine system based on comparison of individual measurements or combinations of measurements with defined health norms or rules. This does not mean that rule based methods are necessarily simple. Although binary yes-no health assessment can sometimes be established by relatively simple rules, the causality assignment needed for refined health monitoring often requires an exceptionally complex rule base involving complicated logical maps. Structuring the rule system to be clear and unambiguous can be difficult, and the expert input required to maintain a large logic network and associated rule base can be prohibitive.

Santi, L. Michael↗
NASA NTRS1971

Conceptual design study of a nuclear Brayton turboalternator-compressor

A comprehensive analysis and conceptual design study of the turboalternator-compressor components using HeXe as the working fluid was performed. The study was conducted in three phases: general configuration analysis (Phase 1), design variations (Phase 2), and conceptual design study (Phase 3). During the Phase 1 analysis, individual turbine, alternator, compressor, and bearing and seal designs were evaluated. Six turboalternator-compressor (TAC) configurations were completed. Phase 2 consisted of evaluating one selected Phase 1 TAC configuration to calculate its performance when operating under new cycle conditions, namely, one higher and one lower turbine inlet temperature and one case with krypton as the working fluid. Based on the Phase 1 and 2 results, a TAC configuration that incorporated a radial compressor, a radial turbine, a Lundell alternator, and gas bearings was selected. During Phase 3 a new layout of the TAC was prepared that reflects the cycle state points necessary to accommodate a zirconium hydride moderated reactor and a 400 Hz alternator. The final TAC design rotates at 24,000 rpm and produces 160 kWe, 480 V, 3-phase, 400 hertz power.

Source record↗
DOE OSTI2025

Probing the Mechanism of Selective Phosphate Adsorption from Wastewater Using Aqueous and Synchrotron X-ray Characterization

Ion exchange shows promise for recovering phosphate from wastewater as value-added products, but requires high phosphate selectivity to compete with conventional treatment. Hybrid anion exchange (HAIX) resins, which contain non-selective basic functional groups and selective iron oxide nanoparticles (FeOnp), can effectively remove phosphate from wastewater. However, knowledge gaps remain regarding the mechanisms of phosphate selectivity and influence of competing ions, hindering needed efforts to model adsorption dynamics and design scalable adsorption processes for varying wastewaters. To address these gaps, we integrated aqueous-phase adsorption analysis with solid-phase, synchrotron-based X-ray characterization; this integration facilitated elucidation of the distribution and speciation of iron, phosphate, and competing anions on HAIX resins. We compared a quaternary ammonium-functionalized HAIX resin (SBA) to a tertiary amine version (WBA) to determine the role of functional groups. X-ray radiography revealed differences in FeOnp speciation (goethite vs. ferrihydrite) and distribution (peripheral vs. homogeneous) between the resins, resulting in varied phosphate affinity and intraparticle diffusion resistance. Using micro-X-ray fluorescence (μ-XRF) and micro-X-ray absorption near-edge structure (μ-XANES) spectroscopy, we identified differences in where and how phosphate binds across resin types and wastewaters. Across wastewater compositions, FeOnp sites in WBA contribute more to phosphate adsorption than in SBA, possibly due to variations in Fe distribution and speciation. Phosphate adsorption densities calculated from quantitative μ-XRF maps matched those from aqueous analysis, demonstrating the effectiveness of this integrated approach. Altogether, results demonstrate the use of synchrotron-based X-ray characterization for investigating adsorption mechanisms and advance HAIX as a phosphate recovery technology from complex wastewaters.

Nutrient recovery↗
DOE OSTI2021

Optimizing Treatment in Intermediate-Risk Prostate Cancer: Secondary Analysis of a Randomized Phase 3 Trial

To identify patients with intermediate-risk prostate cancer (IRPC) benefiting from de-escalation of androgen deprivation therapy (ADT) and/or dose escalated radiation therapy (DERT), we performed a secondary analysis of a phase 3 trial by measuring biochemical failure (BF), distant metastases, prostate cancer–specific mortality, overall survival (OS), and distant metastases-free survival (DMFS) rates according to prognostic intermediate risk factors (IRF).

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2022

Probing ethane phase changes in bead pack via high-field NMR spectroscopy

Phase equilibria analysis in two-phase systems requires discernment of the individual phases as well as the interfacial region. The phase behavior of fluids in constraint geometries have been studied through several techniques. High-Field Nuclear Magnetic Resonance (HF-NMR) can be used to detect fluid phases, i.e. gas, liquid, or supercritical fluid, in the bulk or under confinement. In solution-state HF-NMR, each phase exhibits a distinct chemical shift that correlates to the phase density. In turn, the emergence of multimodal in NMR spectra reveals the coexistence of multiple phases in fluid systems. Our results for ethane show that HF-NMR can enable tracking phase changes in the bulk, but also in macro-scale (10–100's μm in pore size) porous systems at various pressure and temperature conditions, even when the system us out of equilibrium. Finally, these results creates potential opportunities to investigate phase changes influenced by confinement in porous systems, though additional steps are necessary.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗