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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Recap of DIP Workshop Series: #1 DIP Architecture and Data Integrations Services

This workshop will cover DIP architecture and data integration services to obtain feedback from America for Airlines (A4A) Air Traffic Management Council (ATMC). Participants will get a look at how the DIP architecture is set-up as well as how data integration services are planned to be hosted on the platform. The DIP architecture review is intended to cover how DIP was envisioned and how DIP is being developed to address data needs across the industry. Participants will have a chance to provide feedback on the DIP architecture and gain insight into how one might interface with the DIP to send or receive data. The data integration services portion is intended to cover DIP’s technical approach to data integration. As an example implementation, there will be a first look at possible data fusion on the platform, including utilizing NASA’s Fuser, and tailoring for industry data consumers. Descriptions, at a high-level, of input to and output of the Fuser will also be discussed.

ATM-X↗
NASA NTRS2003

Origin of Dips in 4U1915-05

This grant supported our participation in a proposal submitted by Didier Barret to conduct a study of the dipping LMXB 4U1915-05. In this Final Report, we summarize the Scientific Objectives of this investigation and the results achieved. Data analysis is still in progress and publication of results will be forthcoming.Our objectives in this work have been to study: 1. Spectra of dips in 4 Ul916-05: This low mass x-ray binary (LMXB) is a 50min binary system and the first to show x-ray dip behaviour. Our XMM observation was proposed to study the x-ray spectra of the dips to better constrain their physical properties. Of primary interest is the variation of the absorbing column density as a function of flux in the dip. We wish to isolate the absorption from Compton scattering components in the dip spectra, and to use the large throughput of XMM to better constrain short timescale variations of the spectrum in the dips. 2. Period of the dips and long-term ephemeris: We also seek to improve upon the long- term ephemeris of the dips by combining these more recent XMM data with earlier RXTE data to update the ephemeris for dips and the determination of the dip period to further test whether the dip period represents the true binary period of this LMXB. We shall extend the ephemeris published by Chou, Grindlay and Bloser 2001, ApJ, 549, 1135) to test the assertion of Retter, Chou et a1 2002, MNRAS, 330, 37 that the dips are indeed the binary period and not a precession period. 1 3 Results Achieved The observations for this program were delayed, presumably for reasons related to the general difficulty of scheduling XMM targets in this region moderately close to the Cygnus region. 4'171916-05 was finally observed (2lksec) on April 24, 2002, but the data have not been delivered. A second observation was conducted on September 9, 2002 (18ksec) and the data are still being analyzed. 4 Papers Presented and Published A paper is in preparation for Astronomy and Astrophysics in which the full results of this investigation will be reported. 1. Barret, D. et a1 2003, Astron. and Astophys.,in press. 2

Grindlay, Jonathan E.↗
NASA NTRS2002

Dip Spectroscopy of the Low Mass X-Ray Binary XB 1254-690

We observed the low mass X-ray binary XB 1254-690 with the Rossi X-ray Timing Explorer in 2001 May and December. During the first observation strong dipping on the 3.9-hr orbital period and a high degree of variability were observed, along with "shoulders" approx. 15% deep during extended intervals on each side of the main dips. The first observation also included pronounced flaring activity. The non-dip spectrum obtained using the PCA instrument was well-described by a two-component model consisting of a blackbody with kT = 1.30 +/- 0.10 keV plus a cut-off power law representation of Comptonized emission with power law photon index 1.10 +/- 0.46 and a cut-off energy of 5.9(sup +3.0, sub -1.4) keV. The intensity decrease in the shoulders of dipping is energy-independent, consistent with electron scattering in the outer ionized regions of the absorber. In deep dipping the depth of dipping reached 100%, in the energy band below 5 keV, indicating that all emitting regions were covered by absorber. Intensity-selected dip spectra were well-fit by a model in which the point-like blackbody is rapidly covered, while the extended Comptonized emission is progressively overlapped by the absorber, with the, covering fraction rising to 95% in the deepest portion of the dip. The intensity of this component in the dip spectra could be modeled by a combination of electron scattering and photoelectric absorption. Dipping did not occur during the 2001 December observation, but remarkably, both bursting and flaring were observed contemporaneously.

Smale, Alan P.↗
NASA NTRSDate not supplied

DIP Architecture and Data Integration Services

This workshop will cover DIP architecture and data integration services. Participants will get a look at how the DIP architecture is set-up as well as how data integration services are planned to be hosted on the platform. The DIP architecture review is intended to cover how DIP was envisioned and how DIP is being developed to address data needs across the industry. Participants will have a chance to provide feedback on the DIP architecture and gain insight into how one might interface with the DIP to send or receive data. The data integration services portion is intended to cover DIP’s technical approach to data integration. As an example implementation, there will be a first look at possible data fusion on the platform, including utilizing NASA’s Fuser, and tailoring for industry data consumers. Descriptions, at a high-level, of input to and output of the Fuser will also be discussed.

ATM-X↗
DOE OSTI2022

Anomalous dips in reflection spectra of optical polymers deposited on plasmonic metals

Abstract We have studied reflection spectra of dye-doped and undoped polymers deposited onto Ag and Au substrates and found anomalous dips in the UV spectral range. On top of Ag substrates, the λ ∼ 375 nm dips were observed in undoped PMMA, PVP, and PS polymers as well as PMMA doped with Rh590 and HITC laser dyes. In silver-based samples, the spectral positions of the observed reflection dips were close to singularities in the refractive indexes of surface plasmon polaritons (SPPs) propagating at the interface between Ag and polymer. The latter singularities can tentatively explain the λ ∼ 375 nm reflection dips, if the scattering of Ag and polymeric films is large enough to launch SPP without any prism or grating. The dips observed in reflection of Rh590:PMMA and HITC:PMMA on top of Au, were more pronounced than those on Ag, broader, shifted to shorter wavelengths, and their spectral positions had large standard deviations. Furthermore, no anomalous dips in gold-based samples were observed in the reflection spectra of undoped PMMA, PVP, and PS polymers, and a modest singularity in the SPP refractive index, predicted theoretically at λ ∼ 500 nm, cannot explain the dips in the UV reflection spectra observed experimentally. It appears likely that the origin of the reflection dips on top of Au substrates is different from that on top of Ag substrates.

36 MATERIALS SCIENCE↗
NASA NTRS1984

Transient dips of Cygnus X-1 observed from Tenma

The transient intensity dips of the binary system Cyg X-1 have been observed, using the gas scintillation proportional counter (GSPC) array onboard the Tenma X-ray astronomy satellite. The duration of the dips was in the range from several seconds to 10 minutes, with several dips occurring as much as 15 h before the superior conjunction. Within the dips, complex structures were observed with time scales of several seconds, and, in at least one case, shorter than two seconds. For a dip lasting longer than 10 minutes, a high-quality spectrum was obtained which reveals the K-absorption edge of iron at 7.18 + or - 0.18 keV. On the basis of the observed absorption, it is suggested that the dips are caused by absorption due to relatively cool matter (less than about 30,000 k); the low-energy excess observed during the dips is due either to an extended soft X-ray emitting corona or to partial obscuration of the X-ray source by multiple blobs. From the time structure of the dip, a blob size of the order of 10 to the 9th cm is derived.

Kitamoto, S.↗
NASA NTRSDate not supplied

DIP for Service Providers

The second DIP workshop’s topic is DIP for Service Providers. The workshop presentation covers topics such as DIP onboarding process, service authentication, catalog service capabilities, API requirements, NASA services and their access points, and data requirements for service providers. The Onboarding Process describes the required documentation that enables to collaborate with NASA as well as other industry partners through DIP. Also, step by step approach for the partner to take to register services or consme services through the DIP platform. The Catalog Service describes the different ways for the users to search for services that are of interest as well as registering services to the platform, so other users can search and discover. The API Requirements and Service Specifications describes the benefits of DIP's API management approach via API Gateway where services are managed centrally but ownership is decentralized and partners completely own the administration of their own services. NASA Services and Data Access Points topic describes the services, both data access service and machine learning prediction service, that NASA provides via the DIP platform in near time and post operations via REST API endpoints defined on the API Gateway. Also, NASA's approach for data storage process is explained. The Data Requirements for service providers describes the requirements for storing and exposing to support the performance of services that are provided by the service providers. Lastly, NASA's technology development plan with preliminary scheduler will be presented. There will be a Q&A session at the end of each segment of the presentation to solicit feedback from the participants.

ATM-X↗
DOE OSTI2022

Investigating the origin of observed central dips in radial metallicity profiles

ABSTRACT Radial metallicity trends provide a key indicator of physical processes such as star formation and radial gas migration within a galaxy. Large integral field unit surveys allow for detailed studies of these radial variations, with recent observations detecting central dips in the metallicity, which may trace the impact of various evolutionary processes. However, the origin of these dips has not been conclusively determined, with suggestions that they may be diagnostic dependent. In this paper, we use the Sloan Digital Sky Survey IV Mapping Nearby Galaxies at Apache Point Observatory survey to investigate whether the observed dips represent genuine decreases in the central metallicity, or whether they could be an artefact of the diagnostic used. Using a sub-sample of 758 local star-forming galaxies at low inclinations, we investigate in detail the impact of using different strong line diagnostics on the shapes of the returned profiles, and the prevalence of dips. We find no clear evidence of the dips being caused by changing values of the ionization parameter within galaxies. To investigate physical causes, we explore both global and spatially resolved parameters, finding that galaxies exhibiting central dips in the O3N2 metallicity profile have on average lower H α equivalent width values out to $R/R_{\rm {e}} \sim 1.5$, and higher values of DN(4000) in the central regions. We additionally find a higher prevalence of dips in galaxies with high stellar mass, and lower values of global specific star formation rate, suggesting a possible link to central quenching. Nevertheless, these results are dependent on the diagnostic used, suggesting caution should be taken when interpreting observed features in galaxy metallicity gradients.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2015

CSI 2264: Characterizing Young Stars in NGC 2264 With Short-Duration Periodic Flux Dips in Their Light Curves

We identify nine young stellar objects (YSOs) in the NGC 2264 star-forming region with optical CoRoT light curves exhibiting short-duration, shallow, periodic flux dips. All of these stars have infrared (IR) excesses that are consistent with their having inner disk walls near the Keplerian corotation radius. The repeating photometric dips have FWHM generally less than one day, depths almost always less than 15%, and periods (3 < P < 11 days) consistent with dust near the Keplerian co-rotation period. The flux dips vary considerably in their depth from epoch to epoch, but usually persist for several weeks and, in two cases, were present in data collected on successive years. For several of these stars, we also measure the photospheric rotation period and find that the rotation and dip periods are the same, as predicted by standard \disk-locking" models. We attribute these flux dips to clumps of material in or near the inner disk wall, passing through our line of sight to the stellar photosphere. In some cases, these dips are also present in simultaneous Spitzer IRAC light curves at 3.6 and 4.5 microns. We characterize the properties of these dips, and compare the stars with light curves exhibiting this behavior to other classes of YSO in NGC 2264. A number of physical mechanisms could locally increase the dust scale height near the inner disk wall, and we discuss several of those mechanisms; the most plausible mechanisms are either a disk warp due to interaction with the stellar magnetic field or dust entrained in funnel- ow accretion columns arising near the inner disk wall.

CSI 2264↗
NASA NTRS1984

SAS 3 observations of Cygnus X-1 - The intensity dips

In general, the dips are observed to occur near superior conjunctions of the X-ray source, but one pair of 2-minute dips occurs when the X-ray source is closer to the observer than is the supergiant companion. The dips are analyzed spectrally with the aid of seven energy channels in the range 1.2-50 keV. Essentially, there is no change in the spectral index during the dips. Reductions in the count rates are observed at energies exceeding 6 keV for some of the dips, but the dip amplitude is always significantly greater in the 1.2-3 keV band. It is believed that absorption by partially ionized gas may best explain these results, since the observations of Pravdo et al. (1980) rule out absorption by unionized material. Estimates for the intervening gas density, extent, and distance from the X-ray source are presented. Attention is also given to the problems confronting the models for the injection of gas through the line of sight, believed to be inclined by approximately 30 deg from the binary pole.

Remillard, R. A.↗
NASA NTRS1997

ASCA Observation of the Dipping X-Ray Source X1916-053

We present the results of timing and spectral studies of the dipping X-ray source X1916-053, observed by ASCA during its Performance Verification phase. The detected dipping activity is consistent with previous observations, with a period of 3008s and an intermittent secondary dip observed roughly 0.4 out of phase with the primary dip. The energy spectra of different intensity states are fitted with a power law with partial covering fraction absorption and interstellar absorption. The increase in the hardness ratio during the primary and secondary dips, and the increase in the covering fraction and column density with decreasing X-ray intensity, all imply that the dipping is caused by the photo-absorbing materials which have been suggested to be where the accreted flow hits the outer edge of the disk materials. The spectra at all intensity levels show no apparent evidence for Fe or Ne emission lines. This may be due to the low metal abundance in the accretion flow. Alternatively, the X-ray luminosity of the central source may be too weak to excite emission lines, which are assumed to be produced by X-ray photoionization of the disk materials.

Ko, Yuan-Kuen↗
NASA NTRS2000

A Coordinated RXTE/ASCA Study of Absorption Dips in Circinus X-1 at Phase Zero

This proposal was for an Rossi X Ray Timing Explorer (RXTE) study of Circinus X-1 with the ASCA satellite for the purpose of studying the iron emission feature during intensity dips. These dips had been discovered previously with ASCA and they appeared to vary in equivalent width and in the energy of the iron K edge. Proper analyses requires good continuum measurements which Rossi X Ray Timing Explorer/Proportional Counter Array (RXTE/PCA) could provide. Also, the PCA data would show any temporal evolution correlated with spectral evolution. RXTE provided 90 ks of data during March 3-5, 1998 which included phase zero which is where the dips usually take place. The ASCA observations were taken by Dr. Neil Brandt of Penn State University. Unfortunately, the source intensity showed far less dipping activity than is typical near phase zero. The light curve exhibited only very narrow sporadic dips rather than some long deep dips necessary for sufficient statistics in the ASCA and RXTE instruments for spectral studies. This prevented us from carrying out the primary goal of the proposal.

Bradt, Hale↗
DOE OSTI2023

DIPS-Plus: The enhanced database of interacting protein structures for interface prediction

Abstract In this work, we expand on a dataset recently introduced for protein interface prediction (PIP), the Database of Interacting Protein Structures (DIPS), to present DIPS-Plus, an enhanced, feature-rich dataset of 42,112 complexes for machine learning of protein interfaces. While the original DIPS dataset contains only the Cartesian coordinates for atoms contained in the protein complex along with their types, DIPS-Plus contains multiple residue-level features including surface proximities, half-sphere amino acid compositions, and new profile hidden Markov model (HMM)-based sequence features for each amino acid, providing researchers a curated feature bank for training protein interface prediction methods. We demonstrate through rigorous benchmarks that training an existing state-of-the-art (SOTA) model for PIP on DIPS-Plus yields new SOTA results, surpassing the performance of some of the latest models trained on residue-level and atom-level encodings of protein complexes to date.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1976

Dip coating process: Silicon sheet growth development for the large-area silicon sheet task of the low-cost silicon solar array project

The technical and economic feasibility of producing solar cell quality sheet silicon by dip-coating one surface of carbonized ceramic substrates with a thin layer of large grain polycrystalline silicon was investigated. The dip-coating methods studied were directed toward a minimum cost process with the ultimate objective of producing solar cells with a conversion efficiency of 10% or greater. The technique shows excellent promise for low cost, labor-saving, scale-up potentialities and would provide an end product of sheet silicon with a rigid and strong supportive backing. An experimental dip-coating facility was designed and constructed, several substrates were successfully dip-coated with areas as large as 25 sq cm and thicknesses of 12 micron to 250 micron. There appears to be no serious limitation on the area of a substrate that could be coated. Of the various substrate materials dip-coated, mullite appears to best satisfy the requirement of the program. An inexpensive process was developed for producing mullite in the desired geometry.

Heaps, J. D.↗
NASA NTRSDate not supplied

Digital Information Platform (DIP) Request for Information (RFI) Informational Session

DIP published an RFI on March 23, 2021. An information session is being hosted to go over the concept of DIP, review the content of the RFI and clarify what is being asked. Important information is emerging in digital form and additional effort is required to utilize the information. DIP will provide the capability to integrate key data sources to data processing services that are used to build aviation services for the traditional/commercial community and new emergents. DIP is currently planning and will take a community-involved, collaborative approach to define and develop the framework. DIP is seeking community and stakeholder input to operational needs, metrics of interest, and demonstration contribution. Participants will have an opportunity to ask questions at the end.

Mirna Johnson↗
NASA NTRSDate not supplied

Digital Information Platform (DIP) Overview

On March 24, 2021, NASA’s Digital Information Platform (DIP) released a Request for Information (RFI) to the aviation community. The RFI was intended to request two things: 1) DIP concept input such as current challenges and needs for data and services and 2) Interest in participating in collaborative demonstrations. On July 29, 2021, DIP team will meet with Airlines for America (A4A) to share a summary of information received from the RFI responses. The objective of the meeting is to follow up with respondents with takeaways the DIP team identified that will inform the concept and demonstration plans. The forum will give participants an opportunity to add on and provide feedback to the summary. The meeting will also describe the roadmap for the Collaborative Demonstrations and next steps for partner engagement.

Digital Information Platform (DIP) RFI summary↗
DOE OSTI2021

Elevated temperature ductility dip in an additively manufactured Al-Cu-Ce alloy

The deformation and failure mechanisms of Al-9Cu-6Ce (wt%) based alloys fabricated with laser powder bed fusion were investigated from room temperature to 400°C. The yield and ultimate tensile strengths decreased monotonically with increase in temperature, but the tensile elongation dipped unexpectedly at elevated temperatures and exhibited a minimum at 300°C. The dip in tensile elongation occurred with a concomitant dip in strain-rate sensitivity (SRS) of deformation. The as-fabricated alloy microstructure was heterogeneous, and the heat affected zone (HAZ) underneath the melt pool boundary was prone to strain localization. At 300 °C, the reduced SRS promoted the progression of strain localization in the HAZ leading to failure initiation and the dip in tensile elongation. Furthermore, a higher SRS or strain-hardening rate at other temperatures improved the tensile elongation by slowing the progression of strain localization in the HAZ such that failure initiated by other mechanisms elsewhere in the microstructure. Notably, the tensile elongation was limited by the defect structure only in a narrow temperature range (150 - 200 °C) while at other temperatures it was limited by the inherent microstructural features. This investigation exemplifies unexpected deformation and failure mechanisms possible in heterogeneous microstructures that result from additive manufacturing.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Characterisation of the dip-bump structure observed in proton–proton elastic scattering at $\sqrt{s}$ = 8 TeV

The TOTEM collaboration at the CERN LHC has measured the differential cross-section of elastic proton–proton scattering at √s = 8TeV in the squared four-momentum transfer range 0.2GeV 2 < |t| < 1.9GeV 2 . This interval includes the structure with a diffractive minimum (“dip”) and a secondary maximum (“bump”) that has also been observed at all other LHC energies, where measurements were made. A detailed characterisation of this structure for √s = 8 TeV yields the positions, |t| dip = (0.521 ± 0.007)GeV 2 and |t| bump = (0.695 ± 0.026)GeV 2 , as well as the cross-section values, dσ/dt| dip = (15.1 ± 2.5)μb/GeV 2 and dσ/dt| bump = (29.7 ± 1.8)μb/GeV 2 , for the dip and the bump, respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗