Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Energy Transition”

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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Structure variation of the index of refraction of GaAs-AlAs superlattices and multiple quantum wells

A detailed calculation of the index refraction of various GaAs-AlAs superlattices is presented for the first time. The calculation is performed by using a hybrid approach which combines the k-p method with the pseudopotential technique. Appropriate quantization conditions account for the influence of the superstructures on the electronic properties of the systems. The results of the model are in very good agreement with the experimental data. In comparison with the index of refraction of the corresponding AlGaAs alloy, characterized by the same average mole fraction of Al, the results indicate that the superlattice index of refraction values attain maxima at the various quantized transition energies. For certain structures the difference can be as large as 2 percent. These results suggest that the waveguiding and dispersion relation properties of optoelectronic devices can be tailored to design for specific optical application by an appropriate choice of the superlattice structure parameters.

Kahen, K. B.↗
NASA NTRS1986

Optical constants of GaAs-AlGaAs superlattices and multiple quantum wells

The optical properties of GaAs-Al sub x Ga sub 1-xAs superlattices are calculated as a function of the frequency and superlattice structure. The comutations are performed using a partition method which combines the vectors k.p method with the pseudopotential technique. The influence of the super-structure on the electronic properties of the systems is accounted for by appropriate quantization conditions. The anisotropy and structure dependence of the dielectric constant result mainly from the contribution of the gamma region while the contributions of the other regions of the Brillouin zone are rather insensitive to the superlattice structure. The superlattice index of refraction values are shown to attain maxima at the various quantized transition energies, where for certain structures, the difference between the refractive indices of the superlattices and its corresponding Al sub x Ga sub 1-xAs alloy can be as large as 2%. In general results are in good agreement with the experimental data.

Kahen, K. B.↗
NASA NTRS1986

Shock temperatures in anorthite glass

Shock-temperature data and the high-pressure thermal behavior of anorthite glass are examined. Temperatures of anorthite glass shocked to pressures between 48-117 GPa were measured in the temperature range 2500-5600 K using optical pyrometry techniques. The time dependence observed in the emitted light of the glass is analyzed in terms of temperature dependence, emissivity dependences, and the time dependence of absorption or scattering of an intervening layer. The three phase transitions at pressures of about 55, 85, and 100 GPa and with transition energies of about 0.5 MJ/kg are studied.

Boslough, M. B.↗
NASA NTRS1986

Measurement of wavelengths and lamb shifts for inner-shell transitions in Fe XVIII-XXIV

The wavelengths of inner-shell 1s-2p transitions in the ions Fe XVIII-XXIV have been measured in solar flare spectra recorded by the Naval Research Laboratory crystal spectrometer (SOLFLEX) on the Air Force P78-1 spacecraft. The measurements are compared with previous measurements and with recently calculated wavelengths. It is found that the measured wavelengths are systematically larger than the wavelengths calculated using the Z-expansion method by up to 0.65 mA. For the more highly charged ions, these differences can be attributed to the QED contributions to the transition energies that are not included in the Z-expansion calculations.

Seely, J. F.↗
NASA NTRS1988

(1 + 1) resonant enhanced multiphoton ionization via the A2Sigma(+) state of NO - Ionic rotational branching ratios and their intensity dependence

Rotational branching ratios resulting from the (1 + 1) resonant enhanced multiphoton ionization spectroscopy of NO via the 0-0 transition of the A-X band for the four possible branches that can be assigned as R(21.5) are explored using calculation performed in the frozen-core approximation at the Hartree-Fock level. The four different branches, of which three are distinctly different in the perturbative limit, have rather different branching ratios. The mixed R12 + Q22(21.5) branch, which is not intense and has the lowest transition energy, appears to give the best agreement with experimental branching ratio for parallel detection. The agreement is less satisfactory for perpendicular detection. Neither the effect of finite-acceptance angle of the photoelectron detector nor high intensities can explain the discrepancy.

Rudolph, H.↗
NASA NTRS1988

Infrared monitoring of the Space Station environment

The measurement and monitoring of infrared emission in the environment of the Space Station has a twofold importance - for the study of the phenomena itself and as an aid in planning and interpreting Station based infrared experiments. Spectral measurements of the infrared component of the spacecraft glow will, along with measurements in other spectral regions, provide data necessary to fully understand and model the physical and chemical processes producing these emissions. The monitoring of the intensity of these emissions will provide background limits for Space Station based infrared experiments and permit the determination of optimum instrument placement and pointing direction. Continuous monitoring of temporal changes in the background radiation (glow) will also permit better interpretation of Station-based infrared earth sensing and astronomical observations. The primary processes producing infrared emissions in the Space Station environment are: (1) Gas phase excitations of Station generated molecules ( e.g., CO2, H2O, organics...) by collisions with the ambient flux of mainly O and N2. Molecular excitations and generation of new species by collisions of ambient molecules with Station surfaces. They provide a list of resulting species, transition energies, excitation cross sections and relevant time constants. The modeled spectrum of the excited species occurs primarily at wavelengths shorter than 8 micrometer. Emissions at longer wavelengths may become important during rocket firing or in the presence of dust.

Kostiuk, Theodor↗
NASA NTRS1989

Auger electron intensity variations in oxygen-exposed large grain polycrystalline silver

Auger electron spectroscopic studies of the grains in oxygen-charged polycrystal-line silver show significant intensity variations as a function of crystallographic orientation. These intensity variations were observed by studies of the Auger images and line scans of the different grains (randomly selected) for each silver transition energy. The results can be attributed to the diffraction of the ejected Auger electrons and interpreted by corresponding changes in the electron mean-free path for inelastic scattering and by oxygen atom accumulation in the subsurface. The subsurface (second layer) octahedral sites increased in size because of surface relaxation and serve as a stable reservoir for the dissolved oxygen.

Lee, W. S.↗
NASA NTRS1993

Photoluminescence from narrow InAs-AlSb quantum wells

We report on photoluminescence spectra from narrow InAs-AlSb quantum wells. Strong, clearly resolved peaks for well widths from 2 to 8 monolayers were observed. Transmission electron micrographs show direct evidence for the structural quality of the quantum well structures. The transition energies of the narrowest wells suggest a strong influence of the AlSb X-barrier on the electronic states in the conduction band.

Brar, Berinder↗
NASA NTRS1995

Photoluminescence spectroscopy and the effective mass theory of strained (In,Ga)As/GaAs heterostructures grown on (112)B GaAs substrates

The photoluminescence characteristics of pseudomorphic In(0.19)Ga(0.81)As/GaAs quantum well structures grown on both the conventional (001) and the unconventional (112)B GaAs substrate are investigated. It is found that the emission spectra of the structures grown on the (112)B surface exhibit some spectral characteristics not observed on similar structures grown on the (001) surface. A spectral blue shift of the e yields hh1 transition with increasing optical pump intensity is observed for the quantum wells on the (112) surface. This shift is interpreted to be evidence of a strain-induced piezoelectric field. A second spectral feature located within the band gap of the In(0.19)Ga(0.81)As layer is also observed for the (112) structure; this feature is thought to be an impurity-related emission. The expected transition energies of the quantum well structures are calculated using the effective mass theory based on the 4 x 4 Luttinger valence band Hamiltonian, and related strain Hamiltonian.

Henderson, R. H.↗
NASA NTRS2005

Chirality Characterization of Dispersed Single Wall Carbon Nanotubes

Raman scattering and optical absorption spectroscopy are used for the chirality characterization of HiPco single wall carbon nanotubes (SWNTs) dispersed in aqueous solution with the surfactant sodium dodecylbenzene sulfonate. Radial breathing mode (RBM) Raman peaks for semiconducting and metallic SWNTs are identified by directly comparing the Raman spectra with the Kataura plot. The SWNT diameters are calculated from these resonant peak positions. Next, a list of (n, m) pairs, yielding the SWNT diameters within a few percent of that obtained from each resonant peak position, is established. The interband transition energies for the list of SWNT (n, m) pairs are calculated based on the tight binding energy expression for each list of the (n, m) pairs, and the pairs yielding the closest values to the corresponding experimental optical absorption peaks are selected. The results reveal that (1, 11), (4, 11), and (0, 11) as the most probable chiralities of the semiconducting nanotubes. The results also reveal that (4, 16), (6, 12) and (8, 8) are the most probable chiralities for the metallic nanotubes. Directly relating the Raman scattering data to the optical absorption spectra, the present method is considered the simplest technique currently available. Another advantage of this technique is the use of the E(sup 8)(sub 11) peaks in the optical absorption spectrum in the analysis to enhance the accuracy in the results.

Namkung, Min↗
NASA NTRS2012

Atomic Decay Data for Modeling K Lines of Iron Peak and Light Odd-Z Elements*

Complete data sets of level energies, transition wavelengths, A-values, radiative and Auger widths and fluorescence yields for K-vacancy levels of the F, Na, P, Cl, K, Sc, Ti, V, Cr, Mn, Co, Cu and Zn isonuclear sequences have been computed by a Hartree-Fock method that includes relativistic corrections as implemented in Cowan's atomic structure computer suite. The atomic parameters for more than 3 million fine-structure K lines have been determined. Ions with electron number N greater than 9 are treated for the first time, and detailed comparisons with available measurements and theoretical data for ions with N less than or equal to 9 are carried out in order to estimate reliable accuracy ratings.

modeling K lines↗
NASA NTRS2015

NASA's Space Launch System: An Evolving Capability for Exploration

Designed to enable human space exploration missions, including eventually landings on Mars, NASA's Space Launch System (SLS) represents a unique launch capability with a wide range of utilization opportunities, from delivering habitation systems into the lunar vicinity to high-energy transits through the outer solar system. The vehicle will be able to deliver greater mass to orbit than any contemporary launch vehicle. SLS will also be able to carry larger payload fairings than any contemporary launch vehicle, and will offer opportunities for co-manifested and secondary payloads.

Robinson, Kimberly F.↗
NASA NTRS2017

Influence of Plasma Environment on K-Line Emission in Highly Ionized Iron Atoms Evaluated Using a Debye-Huckel Model

The influence of plasma environment on the atomic parameters associated with the K-vacancy states has been investigated theoretically for several iron ions. To do this, a time-averaged Debye-Huckel potential for both the electron-nucleus and electron-electron interactions has been considered in the framework of relativistic multiconfiguration Dirac-Fock computations. More particularly, the plasma screening effects on ionization potentials, K-thresholds, transition energies, and radiative rates have been estimated in the astrophysical context of accretion disks around black holes. In the present paper, we describe the behavior of those atomic parameters for Ne-, Na-, Ar-, and K-like iron ions.

Deprince, J.↗
DOE OSTI2022

Industrial Load Flexibility, the U.S. Power Grid and Ammonia

A variable renewable power grid is a new technological regime that involves real time harvesting and low-cost availability of energy resources coupled with storage to meet additional needs. Decarbonization through electrification of end uses formerly met by combustion processes will be a concurrent trend. Taken together, these two changes may make flexibility on the demand side more valuable to the grid and to industrial users. Industry accounted for 26% of US power demand in 2021. Traditionally, industrial processes for producing ammonia and other basic materials have been optimized for a system based on fossil resources, where energy can be called upon according to needs. Large capital expenditures as well as safety considerations have favored plants running at steady state at close to their maximum capacity. It is possible, however, that the renewable energy transition will offer opportunities to sectors that can operate in a more flexible manner. Innovations that make use of flexibility to enhance their business model to move forward, individuals and groups active in their development, use and regulation, together with institutions and infrastructures, can be considered as a technological innovation system (TIS). Beyond economic and technical factors on their own, the TIS is an important analysis framework for studying the development and diffusion of technologies. This work attempts to map the TIS of flexible industrial loads and their interaction with electric power in the US, with a particular focus on ammonia as a case study. We have conducted interviews with stakeholders involved in ammonia projects, working in system operators, trade groups, regulators and utilities. We assess to what extent a technological innovation system is functioning and document characteristics that allow industries to operate flexibly.

ammonia↗
DOE OSTI2022

NETL’s Techno-Economic Models for Assessing CO2 Pipeline Transport and Geologic Storage

Presentation at Society of Petroleum Engineers (SPE) Workshop: Future Energy Roadmap – Navigating Through the Energy Transition, held in Galveston, Texas, August 22-23, 2022. The presentation provides an overview of the techno-economic models NETL has developed for assessing performance characteristics and cost drivers for CO2 pipeline transport (FECM/NETL CO2 Transport Cost Model or CO2_T_COM), CO2 saline storage (FECM/NETL CO2 Saline Storage Cost Model or CO2_S_COM), and oil production and CO2 storage using CO2 enhanced oil recovery (EOR) (FE/NETL CO2 Prophet Model or CO2_Prophet and FE/NETL Onshore CO2 EOR Cost Model or CO2_E_COM). A high-level description of each model is presented along with useful outputs that can be generated with each model. These tools can be used individually to evaluate the economic opportunity for specific CCUS components, or they can be used in tandem to assess an integrated CCUS value chain.

Morgan, David↗
DOE OSTI2022

Carbon Storage and Utilization: Perspective on Water Usage and Opportunities

Disseminate technical and non-technical perspective on the opportunities for water recovery from produced water and CO2 storage in the I-WEST region. Concerned citizens and advocacy groups; farmers and ranchers; tribal, state, city, and county leaders; and project leaders working on water-related initiatives are all encouraged to participate in the workshop. This workshop is an opportunity for regional stakeholders to join the conversation about the challenges and opportunities water presents for energy transition in the Inter- Mountain West.

Vikara, Derek↗
DOE OSTI2023

Process-based cost estimation framework for assessing economic viability of environmentally and socially sustainable rare earth element feedstocks

Rare Earth Elements (REEs) are critical raw material inputs that are required to enable the energy transition. Constraints on the U.S. supply of conventional REE feedstocks and the desire to diversify U.S. reliance on foreign supply chains have motivated the pursuit of REE recovery from unconventional feedstocks including waste products. Recovery of REEs from unconventional sources is also motivated by environmental and social considerations, including the potential to offset new mining activity and subsidize the remediation of REE-containing wastes from coal, natural gas, and other mineral extraction activities. Sourcing REEs from unconventional feedstocks would reduce supply chain constraints and minimize the environmental impacts of REE extraction, but current processes to exploit these feedstocks have uncertain technical and economic performance and the processes have not been demonstrated at scale. This work aims to reduce uncertainty in evaluating the performance of new REE production pathways. A database of operating and capital expenses for REE recovery and establish consistent process unit costs for common stages in the conventional supply chain are developed. Market prices are used to develop well-defined methods for determining product values for a diverse set of products that can be generated (e.g. oxalates, alloys, end-use products such as magnets) but are not typically considered in technoeconomic analyses. Finally, to provide insight on the effects of economies of scale and feedstock purity on capital and operating costs, process unit level cost functions relating total costs per kilogram of REE produced are reported. These tools can be applied to assess and facilitate scale-up of REE production from diverse sources of REEs.

Fritz, Alison↗