Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “CaS”

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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Metal ion dopant-induced famatinite to chalcostibite phase transformation of copper antimony sulphide colloidal nanostructures: effect on photophysical and pseudocapacitance properties

Here, the strategic doping of transition metal ions into copper antimony sulphide (CAS) semiconducting nanostructures can significantly influence their photophysical and pseudocapacitive properties, for which there are few reports and therefore is the focus of this study. Accordingly, highly crystalline metal ion (Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ and Zn 2+ ) doped off-stoichiometric copper rich/poor, antimony-rich/poor, and sulphur-poor CAS nanostructures (10–23 nm) were grown via colloidal (hot-injection) synthesis using metal diethyldithiocarbamate precursors. Importantly, metal ion doping significantly influences the structure and composition of the off-stoichiometric CAS nanostructures. Data from powder X-ray diffraction, Raman spectroscopy, high-resolution scanning/transmission electron microscopy, and energy dispersive X-ray spectroscopy confirm that the heavier metal ion dopants induce a novel phase transformation from famatinite (fCAS) to chalcostibite (cCAS) nanostructures. The influence of the metal ion dopants is also observed in the optical properties of as-synthesized nanostructures. This involves blue-shifted ultraviolet-visible absorption, reduced Urbach tailing, and tunable bandgaps between 2.17 and 2.38 eV. Also, the doped nanostructures display broad visible-near infrared photoluminescence via a triple radiative pathway with relatively short decay lifetimes between 0.2 and 6.1 ns. This is mediated by electronic transitions involving intrinsic (copper/antimony/sulphur interstitial) and extrinsic (metal ion interstitial) defect states. Additionally, electrodes prepared from Mn 2+ -doped fCAS nanostructures show enhanced pseudocapacitance via Na+ surface adsorption and intercalation relative to undoped fCAS electrodes, while Zn 2+ -doped cCAS electrodes exhibit pseudocapacitance via a combination of Na+ surface adsorption, intercalation, and redox reactions. These electrodes exhibit reduced charge transfer resistance, improved electronic conductivity and notably enhanced specific capacitance (∼222 F g −1 ), and charge transport, as measured in 1 M Na 2 SO 4 electrolyte via cyclic voltammetry and electrochemical impedance spectroscopy. To this end, the discovery of the metal ion-induced phase transformation presents a new avenue for optimizing the functional properties of fCAS and cCAS nanostructures, highlighting the critical role of metal ion-related defects in controlling the optical and electrochemical properties, towards potential solar absorption and energy storage applications.

25 ENERGY STORAGE↗
DOE OSTI2022

Decorating chromatin for enhanced genome editing using CRISPR-Cas9

CRISPR-associated (Cas) enzymes have revolutionized biology by enabling RNA-guided genome editing. Homology-directed repair (HDR) in the presence of donor templates is currently the most versatile method to introduce precise edits following CRISPR-Cas-induced double-stranded DNA cuts, but HDR efficiency is generally low relative to end-joining pathways that lead to insertions and deletions (indels). We tested the hypothesis that HDR could be increased using a Cas9 construct fused to PRDM9, a chromatin remodeling factor that deposits histone methylations H3K36me3 and H3K4me3 to mediate homologous recombination in human cells. Our results show that the fusion protein contacts chromatin specifically at the Cas9 cut site in the genome to increase the observed HDR efficiency by threefold and HDR:indel ratio by fivefold compared with that induced by unmodified Cas9. HDR enhancement occurred in multiple cell lines with no increase in off-target genome editing. These findings underscore the importance of chromatin features for the balance between DNA repair mechanisms during CRISPR-Cas genome editing and provide a strategy to increase HDR efficiency.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Functional characterization of diverse type I-F CRISPR-associated transposons

CRISPR-Cas systems generally provide adaptive immunity in prokaryotes through RNA-guided degradation of foreign genetic elements like bacteriophages and plasmids. Recently, however, transposon-encoded and nuclease-deficient CRISPR-Cas systems were characterized and shown to be co-opted by Tn7-like transposons for CRISPR RNA-guided DNA transposition. As a genome engineering tool, these CRISPR-Cas systems and their associated transposon proteins can be deployed for programmable, site-specific integration of sizable cargo DNA, circumventing the need for DNA cleavage and homology-directed repair involving endogenous repair machinery. Here, we selected a diverse set of type I-F3 CRISPR-associated transposon systems derived from Gammaproteobacteria, predicted all components essential for transposition activity, and deployed them for functionality testing within Escherichia coli. Our results demonstrate that these systems possess a significant range of integration efficiencies with regards to temperature, transposon size, and flexible PAM requirements. Additionally, our findings support the categorization of these systems into functional compatibility groups for efficient and orthogonal RNA-guided DNA integration. This work expands the CRISPR-based toolbox with new CRISPR RNA-guided DNA integrases that can be applied to complex and extensive genome engineering efforts.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Streamlining heterologous expression of top carbonic anhydrases in Escherichia coli : bioinformatic and experimental approaches

Carbonic anhydrase (CA) enzymes facilitate the reversible hydration of CO 2 to bicarbonate ions and protons. Identifying efficient and robust CAs and expressing them in model host cells, such as Escherichia coli, enables more efficient engineering of these enzymes for industrial CO 2 capture. However, expression of CAs in E. coli is challenging due to the possible formation of insoluble protein aggregates, or inclusion bodies. This makes the production of soluble and active CA protein a prerequisite for downstream applications. In this study, we streamlined the process of CA expression by selecting seven top CA candidates and used two bioinformatic tools to predict their solubility for expression in E. coli. The prediction results place these enzymes in two categories: low and high solubility. Our expression of high solubility score CAs (namely CA5-SspCA, CA6-SazCAtrunc, CA7-PabCA and CA8-PhoCA) led to significantly higher protein yields (5 to 75 mg purified protein per liter) in flask cultures, indicating a strong correlation between the solubility prediction score and protein expression yields. Furthermore, phylogenetic tree analysis demonstrated CA class-specific clustering patterns for protein solubility and production yields. Unexpectedly, we also found that the unique N-terminal, 11-amino acid segment found after the signal sequence (not present in its homologs), was essential for CA6-SazCA activity. Overall, this work demonstrated that protein solubility prediction, phylogenetic tree analysis, and experimental validation are potent tools for identifying top CA candidates and then producing soluble, active forms of these enzymes in E. coli. The comprehensive approaches we report here should be extendable to the expression of other heterogeneous proteins in E. coli.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Developing Multi-Gene CRISPRa/I Programs to Accelerate DBTL Cycles in ABF Hosts Engineered for Chemical Production (CRADA 468)

Bacterial metabolism is comprised of large and complex gene networks that can produce valuable chemical products. Sophisticated organism engineering efforts are required to optimize production of high-value compounds from these networks. In principle, synthetic multi-gene transcriptional programs could be constructed to reengineer these networks for efficient industrial chemical production. In practice, however, our incomplete ability to understand and model the underlying networks, combined with our limited ability to predictably control the expression of multiple genes makes achieving this goal difficult. To overcome these challenges, we will combine new CRISPR-Cas multi-gene expression programs with computational modeling, machine learning, and multi-omics data to enhance the efficacy of design-build-test-learn (DBTL) cycles. For industrially promising microorganisms in early stages of development, creating technologies for rapidly engineering complex multi-gene programs could be transformative for accelerating data- and model-driven strain design. New CRISPR-Cas tools allow programmable gene activation (CRISPRa) or repression (CRISPRi) at multiple genes simultaneously, using the catalytically inactive Cas9 protein (dCas9) with guide RNAs that recognize DNA targets through predictable Watson-Crick base pairing. To enable accelerated DBTL cycles, we will combine these technologies with advanced Agile BioFoundry (ABF) capabilities for multi-omics data collection and machine learning. We will demonstrate the immediate applicability of these tools by rapidly improving the production of an industrial aromatic in multiple ABF organisms. We recently identified and optimized new transcriptional activators that can be linked to programmable CRISPR-Cas DNA binding domains to activate gene expression in E. coli. We can now use these CRISPRa tools as generalizable trans-acting regulators for combinatorial multi-gene expression tuning that can be easily transferred to new pathways and networks without additional genome engineering. We anticipate these tools will also transfer to new hosts. We have recently found that CRISPRa systems developed in E. coli can be readily ported to Pseudomonas putida, suggesting that multi-gene CRISPRa/i programs for diverse ABF organisms may be within reach.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Evaluating spectral cloud effective radius retrievals from the Enhanced MODIS Airborne Simulator (eMAS) during ORACLES

Satellite remote sensing retrievals of cloud effective radius (CER) are widely used for studies of aerosol–cloud interactions. Such retrievals, however, rely on forward radiative transfer (RT) calculations using simplified assumptions that can lead to retrieval errors when the real atmosphere deviates from the forward model. Here, coincident airborne remote sensing and in situ observations obtained during NASA's ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) field campaign are used to evaluate retrievals of CER for marine boundary layer stratocumulus clouds and to explore impacts of forward RT model assumptions and other confounding factors. Specifically, spectral CER retrievals from the Enhanced MODIS Airborne Simulator (eMAS) and the Research Scanning Polarimeter (RSP) are compared with polarimetric retrievals from RSP and with CER derived from droplet size distributions (DSDs) observed by the Phase Doppler Interferometer (PDI) and a combination of the Cloud and Aerosol Spectrometer (CAS) and the Two-Dimensional Stereo Probe (2D-S). The sensitivities of the eMAS and RSP spectral retrievals to assumptions about the DSD effective variance (CEV) and liquid water complex index of refraction are explored. CER and CEV inferred from eMAS spectral reflectance observations of the backscatter glory provide additional context for the spectral CER retrievals. The spectral and polarimetric CER retrieval agreement is case dependent, and updating the retrieval RT assumptions, including using RSP polarimetric CEV retrievals as a constraint, yields mixed results that are tied to differing sensitivities to vertical heterogeneity. Moreover, the in situ cloud probes, often used as the benchmark for remote sensing CER retrieval assessments, themselves do not agree, with PDI DSDs yielding CER values 1.3–1.6 µm larger than CAS and with CEV roughly 50 %–60 % smaller than CAS. Implications for the interpretation of spectral and polarimetric CER retrievals and their agreement are discussed.

Meyer, Kerry [NASA Goddard Space Flight Center (GS↗
NASA NTRS1978

Airborne infrared spectrophotometry of Mira variables

Airborne spectrophotometric observations of R Cas near minimum and maximum light, R Leo near minimum, and NML Tau near maximum are reported which were obtained over the wavelength range from 1.2 to 4 microns with 1.5% resolution. The spectral energy distributions of the three stars at the indicated times are presented, and it is shown that the H2O bands at 1.4, 1.9, and 2.7 microns are clearly evident in all the spectra, while the absorption bands of CO at about 1.6 and 2.3 microns are probably present although they are masked by the strong water vapor features. The results indicate that water vapor is the dominant opacity source in the atmospheres of Mira variables, that R Leo and NML Tau may be fitted well over the entire spectrum by respective single temperatures of 2250 and 1800 K, and that R Cas near both minimum and maximum cannot be adequately described by one temperature over the entire wavelength range investigated. The shapes and depths of the absorption bands are determined together with the apparent angular diameter of each star and the equivalent widths of the H2O + CO absorption bands. It is concluded that water vapor absorption is more strongly correlated with color temperature than with spectral type for R Cas and R Leo.

Strecker, D. W.↗
NASA NTRS1979

The crop assessment subsystem: System implementation and approaches used for the generation of crop production reports

The primary responsibility of the crop assessment subsystem (CAS) during the three phases of LACIE was to produce crop reports that included estimates of wheat area, yield, and production, as well as a specified set of associated statistical descriptors. The operations of CAS are described with emphasis on sampling strategy, input/output data, evolution of aggregation/reporting system capabilities, and CAS aggregation procedures.

Mcallum, W. E.↗
NASA NTRS1981

IUE spectra of F and late A stars

The International Ultraviolet Explorer (IUE) spectra of alpha CMi (F5 IV-V), beta Cas (F2 IV), alpha Car (F0 Ib), and gamma Boo (A7 III) in the context of the question as to whether chromospheres disappear in the early F late A portions of the Hertzsprung-Russell diagram. Both alpha CMi (Procyon) and beta Cas show bright emission line spectra indicative of chromospheres and transition regions, but neither alpha Car (Canopus) nor gamma Boo show any evidence of emission in their SWP spectra or at the Mg II lines, despite very deep exposures. Alpha CMi has emission line fluxes roughly 6 times those of the quiet Sun, but the rapidly rotating delta Scuti type variable beta Cas has surface fluxes 10 to 50 times those of the quiet Sun. Upper limits on emission line fluxes for alpha Car are 4 to 20 and for gamma Boo 15 to 80 times the quiet Sun. It is concluded that the apparent absence of emission lines in the spectra of alpha Car and gamma Boo should not be interpreted as due to the absence of nonradiatively heated outer atmospheres in stars hotter than spectral type F0, but rather to the inability to see emission lines with IUE against a background of scattered light and a bright photospheric absorption line spectrum either in low or high dispersion.

Linsky, J. L.↗
NASA NTRS1983

On the nature of the bonding in Cu2 - An ab initio viewpoint

The bonding in Cu2 has been calculatively investigated. A CASSCF calculation is performed where the two 4s electrons are distributed in all possible ways among the 4s and 4p orbitals. The CAS results have a 3d population of 9.99. The corresponding orbitals between the CAS core orbitals at r(e) and the atomic SCF core orbitals show an overlap of 13.9992 out of a possible 14, with all of the change in sigma space. Thus, the CAS results show virtually no change in the d orbitals relative to the atom and can be considered as showing only a single bond. The reduction in 3d population, the decrease in r(e), and the increase in D(e) upon correlating the 3d shell indicates that the 3d electrons are slightly involved in the bonding, but there is no indication of the formation of a triple bond.

Bauschlicher, C. W., Jr.↗
NASA NTRS1984

Explosive nucleosynthesis in massive stars - Comparison with the Cassiopeia A fast-moving knots

If the ejecta of a Type II supernova do not undergo extensive mixing, then, based on the explosion of current presupernova models, only a small fraction approximately equal to or less than 0.1 solar mass of the mantle of a massive star can yield abundances similar to those observed in the fast-moving knots of Cas A. This is shown to be independent of the detailed structure of the mantle and the supernova energy. Lack of mixing in Cas A is indicated by strong upper limits on the abundance ratios Ne/O, and Fe/O. If this is confirmed by further observations, then either Cas A is not the result of a standard progenitor of approximately equal to or less than 25 solar masses disrupted by a Type II supernova, or the picture of the last stages of stellar evolution in massive stars needs to be modified substantially.

Johnston, M. D.↗
NASA NTRS1987

Far-ultraviolet observations of the Delta-Scuti variable Beta Cassiopeiae

FUV (115-200-nm) observations of Beta Cas, obtained at resolutions 5 and 0.15 A by the IUE during September 1984, are reported and analyzed. The data are presented graphically and compared with results for Procyon, a sharp-lined F star similar in temperature to Beta Cas. A sharp factor-of-two increase in H I Ly-alpha flux on a time scale comparable to its Delta Sct pulsation period was observed, but the data were insufficient to determine whether the increase was flarelike or pulsation-related. The outer edges of the Beta Cas emission are shown to be significantly wider than those of Procyon.

Ayres, Thomas R.↗
NASA NTRS1989

Computer-aided boundary delineation of agricultural lands

The National Agricultural Statistics Service of the United States Department of Agriculture (USDA) presently uses labor-intensive aerial photographic interpretation techniques to divide large geographical areas into manageable-sized units for estimating domestic crop and livestock production. Prototype software, the computer-aided stratification (CAS) system, was developed to automate the procedure, and currently runs on a Sun-based image processing system. With a background display of LANDSAT Thematic Mapper and United States Geological Survey Digital Line Graph data, the operator uses a cursor to delineate agricultural areas, called sampling units, which are assigned to strata of land-use and land-cover types. The resultant stratified sampling units are used as input into subsequent USDA sampling procedures. As a test, three counties in Missouri were chosen for application of the CAS procedures. Subsequent analysis indicates that CAS was five times faster in creating sampling units than the manual techniques were.

Cheng, Thomas D.↗
NASA NTRS1989

Preliminary design of a family of close air support aircraft

A family of three Close Air Support (CAS) aircraft is presented. These aircraft are designed with commonality as the main design objective to reduce the life cycle cost. The aircraft are low wing, twin-boom, pusher turbo-prop configurations. The amount of information displayed to the pilot was reduced to a minimum to greatly simplify the cockpit. The aircraft met the mission specifications and the performance and cost characteristics compared well with other CAS aircraft. The concept of a family of CAS aircraft seems viable after preliminary design.

Tuschhoff, Jeff↗
NASA NTRS2004

A Study of the Non-Thermal X-ray Emission of Shell-Type Supernova Remnants

The term of the forth year of the award is the period from March 15, 2003 to March 14, 2004. During this year, Dr. Thomas Pannuti, who had been performing most of the analyses, made a transition to a new position at Caltech. As of September 2003, Dr. Michael Stage began performing most of the analyses. Dr. Stage has begun constructing a detailed catalog of the spatial and spectral properties of young supernova remnants as described in sections 1 and 4 of the proposal. Specifically, he has focused on the analysis of Chandra ACIS data. The exquisite spatial resolution of the Chandra telescope and the modest spectral resolution of the CCDs make these data ideal. Dr. Stage has developed a standard set of procedures to reduce the data, generate telescope and detector response libraries and handle instrumental and celestial background subtraction. He has also adapted some existing code to automate spectral extraction and fitting. This code enables us to analyze the spectra of tens of thousands of small subregions of supernova remnants. Dr. Stage has recently applied this process to ACIS data for the supernova remnants Cas A and Kepler. The results include maps of the fitted parameters, such as individual line intensities and centroids (i.e. Doppler shifts), the electron temperature, and the absorption column density. These maps are more accurate than simple energy-cut images because it is difficult (and sometimes impossible) to cleanly separate the line emission from the underlying continuum (especially at low energies). It is now possible to identify the locations at which emission from each element is produced. Some of the elements are seen to be layered. The electron temperature maps demonstrate that the outer edges of Cas A and Kepler are very hot with weak lines. This emission is almost certainly synchrotron dominated. Therefore, not only are the maps interesting in and of themselves, but they also provide an unbiased means of easily identifying features in the remnants that can be studied in more detail using, for example, synchrotron models. Over the next year, Dr. Stage will refine the analysis procedures, expand the analyses to include several other remnants, present the results at major scientific conferences and publish a catalog of the results. Since this work is producing impressive results, we have applied for very long Chandra observations of Kepler and Tycho to obtain enough counts to take lull advantage of the technique. A i Ms observation of Cas A is already scheduled. Over the past year, I completed a joint, spectra,l analysis of some X-ray, radio, and gamma-ray data for the supernova remnant SN 1006. The results of this analysis show that the synchrotron and, hence, electron spectrum of the remnant is curved. The amount of curvature in the electron spectrum is quantitatively consistent with predictions of the amount of curvature in the proton spectrum of the remnant. A paper describing this work is nearly complete. When Dr. Pannuti left, he was analyzing X-ray data for the young supernova remnant G266.2-1.2. Dr. Pannuti found the first evidence of thermal X-ray emission from this remnant. Furthermore, like SN 1006, the cutoff frequency varies with azimuth along the bright northeastern rim. This work will be published during the coming year.

Allen, Glenn E.↗
NASA NTRS1989

Theoretical studies of the infrared emission from circumstellar dust shells: the infrared characteristics of circumstellar silicates and the mass-loss rate of oxygen-rich late-type giants

We have modeled the infrared emission of spherically symmetric, circumstellar dust shells with the aim of deriving the infrared absorption properties of circumstellar silicate grains and the mass-loss rates of the central stars. As a basis for our numerical studies, a simple semianalytical formula has been derived that illustrates the essential characteristics of the infrared emission of such dust shells. A numerical radiative transfer program has been developed and applied to dust shells around oxygen-rich late-type giants. Free parameters in such models include the absorption properties and density distribution of the dust. An approximate, analytical expression is derived for the density distribution of circumstellar dust driven outward by radiation pressure from a central source. A large grid of models has been calculated to study the influence of the free parameters on the emergent spectrum. These results form the basis for a comparison with near-infrared observations. Observational studies have revealed a correlation between the near-infrared color temperature, Tc, and the strength of the 10 micrometers emission or absorption feature, A10. This relationship, which essentially measures the near-infrared optical depth in terms of the 10 micrometers optical depth, is discussed. Theoretical A10-Tc relations have been calculated and compared to the observations. The results show that this relation is a sensitive way to determine the ratio of the near-infrared to 10 micrometers absorption efficiency of circumstellar silicates. These results as well as previous studies show that the near-infrared absorption efficiency of circumstellar silicate grains is much higher than expected from terrestrial minerals. We suggest that this enhanced absorption is due to the presence of ferrous iron (Fe2+) color centers dissolved in the circumstellar silicates. By using the derived value for the ratio of the near-infrared to 10 micrometers absorption efficiency, the observed A10-Tc relation can be calibrated in terms of the total dust column density of the circumstellar shell and thus the mass-loss rate of late-type giants can easily be derived. Detailed models have been made of the infrared emission of three well-studied Miras: R Cas, IRC 10011, and OH 26.5+0.6, with the emphasis on the shape of the 10 micrometers emission or absorption feature. The results show that the intrinsic shape of the 10 micrometers resonance varies from a very broad feature in R Cas to a relatively narrower feature in OH 26.5+0.6, with IRC 10011 somewhere in between. Possible origins of this variation are discussed. The mass-loss rates from these objects are calculated to be 3 x 10(-7), 2 x 10(-5), and 2 x 10(-4) M Sun yr-1 for R Cas, IRC 10011, and OH 26.5+0.6, respectively. These results are compared to other determinations in the literature.

NASA Discipline Exobiology↗
NASA NTRS2004

Evidence for Natural Variability in Marine Stratocumulus Cloud Properties Due to Cloud-Aerosol

In this study, aircraft observations from the Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter are used to characterize the variability in drizzle, cloud, and aerosol properties associated with cloud rifts and the surrounding solid clouds observed off the coast of California. A flight made on 16 July 1999 provided measurements directly across an interface between solid and rift cloud conditions. Aircraft instrumentation allowed for measurements of aerosol, cloud droplet, and drizzle spectra. CCN concentrations were measured in addition to standard thermodynamic variables and the winds. A Forward Scatter Spectrometer Probe (FSSP) measured size distribution of cloud-sized droplets. A Cloud Imaging Probe (CIP) was used to measure distributions of drizzle-sized droplets. Aerosol distributions were obtained from a Cloud Aerosol Scatterprobe (CAS). The CAS probe measured aerosols, cloud droplets and drizzle-sized drops; for this study. The CAS probe was used to measure aerosols in the size range of 0.5 micron - 1 micron. Smaller aerosols were characterized using an Ultrafine Condensation Particle Counter (CPC) sensor. The CPC was used to measure particles with diameters greater than 0.003 micron. By subtracting different count concentrations measured with the CPC, this probe was capable of identifying ultrafine particles those falling in the size range of 3 nanometers - 7 nanometers that are believed to be associated with new particle production.

Albrecht, Bruce↗
NASA NTRS2016

Serious Gaming for Test & Evaluation of Clean-Slate (Ab Initio) National Airspace System (NAS) Designs

Incremental approaches to air transportation system development inherit current architectural constraints, which, in turn, place hard bounds on system capacity, efficiency of performance, and complexity. To enable airspace operations of the future, a clean-slate (ab initio) airspace design(s) must be considered. This ab initio National Airspace System (NAS) must be capable of accommodating increased traffic density, a broader diversity of aircraft, and on-demand mobility. System and subsystem designs should scale to accommodate the inevitable demand for airspace services that include large numbers of autonomous Unmanned Aerial Vehicles and a paradigm shift in general aviation (e.g., personal air vehicles) in addition to more traditional aerial vehicles such as commercial jetliners and weather balloons. The complex and adaptive nature of ab initio designs for the future NAS requires new approaches to validation, adding a significant physical experimentation component to analytical and simulation tools. In addition to software modeling and simulation, the ability to exercise system solutions in a flight environment will be an essential aspect of validation. The NASA Langley Research Center (LaRC) Autonomy Incubator seeks to develop a flight simulation infrastructure for ab initio modeling and simulation that assumes no specific NAS architecture and models vehicle-to-vehicle behavior to examine interactions and emergent behaviors among hundreds of intelligent aerial agents exhibiting collaborative, cooperative, coordinative, selfish, and malicious behaviors. The air transportation system of the future will be a complex adaptive system (CAS) characterized by complex and sometimes unpredictable (or unpredicted) behaviors that result from temporal and spatial interactions among large numbers of participants. A CAS not only evolves with a changing environment and adapts to it, it is closely coupled to all systems that constitute the environment. Thus, the ecosystem that contains the system and other systems evolves with the CAS as well. The effects of the emerging adaptation and co-evolution are difficult to capture with only combined mathematical and computational experimentation. Therefore, an ab initio flight simulation environment must accommodate individual vehicles, groups of self-organizing vehicles, and large-scale infrastructure behavior. Inspired by Massively Multiplayer Online Role Playing Games (MMORPG) and Serious Gaming, the proposed ab initio simulation environment is similar to online gaming environments in which player participants interact with each other, affect their environment, and expect the simulation to persist and change regardless of any individual player's active participation.

Allen, B. Danette↗