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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

CHANDRA OBSERVES THE END OF AN ERA IN SN 1987A

Updated imaging and photometric results from Chandra observations of SN 1987A, covering the last 16 years, are presented. We find that the 0.5–2 keV light curve has remained constant at ∼8 × 10{sup −12} erg s{sup −1} cm{sup −2} since 9500 days, with the 3–8 keV light curve continuing to increase until at least 10,000 days. The expansion rate of the ring is found to be energy dependent, such that after day 6000 the ring expands faster in the 2–10 keV band than it does at energies <2 keV. Images show a reversal of the east–west asymmetry between 7000 and 8000 days after the explosion. The latest images suggest the southeastern side of the equatorial ring (ER) is beginning to fade. Consistent with the latest optical and infrared results, our Chandra analysis indicates the blast wave is now leaving the dense ER, which marks the beginning of a major change in the evolutionary phase of the supernova remnant 1987A.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1973

Experimental study of the dynamics of a spherical flame

Preliminary results of an experimental study conducted to investigate the dynamic behavior of flames in explosive gases are presented. The medium was an equimolar acetylene-oxygen mixture maintained initially at a pressure of 110 torr. and room temperature in an experimental vessel 9 cm in internal diameter. Ignition was performed by means of a neodymium laser beam focused on a 0.3 mm diameter steel wire. Experimental observations were performed by the use of a stroboscopic laser-schlieren system yielding a set of photographic records of wave phenomena at a frequency of 200,000 per second. The records reveal the existence of a number of shocks which by a thorough analysis of the blast wave generated by the ignition process, are shown to be due entirely to the flame generated flow field. The capability of a flame to form blast waves in an expanding spherical geometry is thus established, providing an experimental demonstration of the significance the dynamic effects of combustion can achieve.

Oppenheim, A. K.↗
NASA NTRS1971

A systematic exposition of the conservation equations for blast waves.

In order to provide a rational background for the analysis of experimental observations of blast wave phenomena, the conservation equations governing their nonsteady flow field are formulated in a general manner, without the usual restrictions imposed by an equation of state, and with proper account taken, by means of source terms, of other effects which, besides the inertial terms that conventionally dominate these equations, can affect the flow. Taking advantage of the fact that a blast wave can be generally considered as a spatially one-dimensional flow field whose nonsteady behavior can be regarded, consequently, as a function of just two independent variables, two generalized blast wave coordinates are introduced, one associated with the front of the blast wave and the other with its flow field. The conservation equations are accordingly transformed into this coordinate system, acquiring thereby a comprehensive character, in that they refer then to any frame of reference, being applicable, in particular, to problems involving either space or time profiles of the gas-dynamic parameters in the Eulerian system, or time profiles in the Lagrangian system.

Oppenheim, A. K.↗
NASA NTRS1981

Mathematical theory of cylindrical isothermal blast waves in a magnetic field

An analysis is conducted regarding the properties of cylindrically symmetric self-similar blast waves propagating away from a line source into a medium whose density and magnetic field (with components in both the phi and z directions) both vary as r to the -(omega) power (with omega less than 1) ahead of the blast wave. The main results of the analysis can be divided into two classes, related to a zero azimuthal field and a zero longitudinal field. In the case of the zero longitudinal field it is found that there are no physically acceptable solutions with continuous postshock variations of flow speed and gas density.

Lerche, I.↗
NASA NTRS1992

Analysis of TIMS performance subjected to simulated wind blast

The results of the performance of the Thermal Infrared Multispectral Scanner (TIMS) when it is subjected to various wind conditions in the laboratory are described. Various wind conditions were simulated using a 24 inch fan or combinations of air jet streams blowing toward either or both of the blackbody surfaces. The fan was used to simulate a large volume of air flow at moderate speeds (up to 30 mph). The small diameter air jets were used to probe TIMS system response in reaction to localized wind perturbations. The maximum nozzle speed of the air jet was 60 mph. A range of wind directions and speeds were set up in the laboratory during the test. The majority of the wind tests were conducted under ambient conditions with the room temperature fluctuating no more than 2 C. The temperature of the high speed air jet was determined to be within 1 C of the room temperature. TIMS response was recorded on analog tape. Additional thermistor readouts of the blackbody temperatures and thermocouple readout of the ambient temperature were recorded manually to be compared with the housekeeping data recorded on the tape. Additional tests were conducted under conditions of elevated and cooled room temperatures. The room temperature was varied between 19.5 to 25.5 C in these tests. The calibration parameters needed for quantitative analysis of TIMS data were first plotted on a scanline-by-scanline basis. These parameters are the low and high blackbody temperature readings as recorded by the TIMS and their corresponding digitized count values. Using these values, the system transfer equations were calculated. This equation allows us to compute the flux for any video count by computing the slope and intercept of the straight line that relates the flux to the digital count. The actual video of the target (the lab floor in this case) was then compared with a simulated target. This simulated target was assumed to be a blackbody at emissivity of .95 degrees and the temperature was assumed to be at ambient temperature as recorded by the TIMS for each scanline. Using the slope and the intercept the flux corresponding to this target was converted into digital counts. The counts were observed to have a strong correlation with the actual video as recorded by the TIMS. The attached graphs describe the performance of the TIMS when compressed air is blown at each one of the blackbodies at different speeds. The effect of blowing a fan and changing the room temperature is also being analyzed. Results indicate that the TIMS system responds to variation in wind speed in real time and maintains the capability to produce accurate temperatures on a scan line basis.

Jaggi, S.↗
DOE OSTI2017

Blast-Wave Characteristics Near Site 300

We have developed a procedure for calculating the maximum high-explosive weight limit for use at Site 300 based on the analysis of the blast-wave propagation behavior in the atmosphere. Both analytical and experimental efforts have been involved in the present work, including a literature search, evaluation of other data, measurements of local weather conditions, and implementation of relevant computational programs. Major results of the present effort are • Comparison of the LLNL data with other data reveals discrepancies, suggesting that local effects, such as weather conditions in the downrange regions, may play a role in affecting the wave-propagation behavior. Our measurements of the local weather conditions indeed show that they differ from those at Site 300. • Analyses of other, newer models and data have resulted in the implementation of relevant computer codes, such as the BLASTO code, to be used at Site 300. • A new procedure for predicting the weight limit at Site 300 has been recommended. This new procedure consists of - Site 300 and local valley weather measurements. - The LAP code. - The BLASTO code. The LAP code is a modified SIPS code and computes the acoustic ray trajectories, including the focus ("caustic") locations, under varying local weather conditions. The BLASTO code calculates the peak overpressure vs distance relationship for a given charge weight and weather condition. Both the LAP code and the BLASTO code have been implemented and are operational at Site 300. Future plans include conducting selective tests to verify the validity of the predictive procedure recommended for Site 300.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2023

Cost and life cycle analysis for deep CO 2 emissions reduction of steelmaking: Blast furnace-basic oxygen furnace and electric arc furnace technologies

Iron and steel manufacturing is the largest contributor to CO 2 emissions among heavy industries worldwide. This is mostly due to the use of coal in blast furnace-basic oxygen furnace (BF-BOF) process for virgin (primary) steel production. The electricity generation mix used in the electric arc furnace (EAF) process to recycle scrap steel also contributes to the CO 2 emission associated with secondary steel production. To decarbonize iron and steel sector, we investigated decarbonization options for BF-BOF and EAF processes, including energy efficiency, carbon capture and storage, and the use of clean energy sources, in various BF-BOF and EAF process configurations. Additionally, for each decarbonization approach, we evaluated the CO 2 reduction potential via life cycle analysis (LCA) and estimated the associated cost through techno-economic analysis (TEA). A typical U.S. BF-BOF for virgin steel production has a cradle-to-gate (CTG) CO 2 emissions of 1,990 kg/MT steel with a levelized cost of steel (LCOS) of $\$439$/MT steel, while a typical U.S. EAF process for secondary steel production in the United States has a CTG CO 2 emissions of 270 kg/MT steel with a LCOS of $\$365$/MT steel. Combining renewable energy sources and carbon capture, BF-BOF CTG CO 2 emissions can be reduced to 16 kg/MT steel, and EAF configurations can achieve similar deep reductions to reach 25 kg/MT steel. The corresponding LCOS with these decarbonization levels is estimated to increase to $\$542$/MT steel and $\$348$/MT steel, respectively. The estimated CO 2 avoidance costs vary from -$\$90$/MT CO 2 to $\$646$/MT CO 2 , depending on the various decarbonization technologies and energy prices.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
NASA NTRS2013

An Early and Comprehensive Millimetre and Centimetre Wave and X-Ray Study of SN 2011dh: a Non-Equipartition Blast Wave Expanding into a Massive Stellar Wind

Only a handful of supernovae (SNe) have been studied in multiwavelengths from the radio to X-rays, starting a few days after the explosion. The early detection and classification of the nearby Type IIb SN 2011dh/PTF 11eon in M51 provides a unique opportunity to conduct such observations. We present detailed data obtained at one of the youngest phase ever of a core-collapse SN (days 3-12 after the explosion) in the radio, millimetre and X-rays; when combined with optical data, this allows us to explore the early evolution of the SN blast wave and its surroundings. Our analysis shows that the expanding SN shock wave does not exhibit equipartition (epsilon(sub e)/epsilon(sub B) approx. 1000), and is expanding into circumstellar material that is consistent with a density profile falling like R(exp −2). Within modelling uncertainties we find an average velocity of the fast parts of the ejecta of 15 000 +/- 1800 km/s, contrary to previous analysis. This velocity places SN 2011dh in an intermediate blast wave regime between the previously defined compact and extended SN Type IIb subtypes. Our results highlight the importance of early (approx.1 d) high-frequency observations of future events. Moreover, we show the importance of combined radio/X-ray observations for determining the microphysics ratio epsilon(sub e)/epsilon(sub B).

gamma rays↗
DOE OSTI2017

Mercat

Mercat is a highly scalable property software package for robust of analysis of features in next-generation sequencing data and observed unique peptides from metaproteomic data. Mercat is offered in python 3.5/anaconda3, is multiparellel and is easily installed using bioconda/conda recipes. Mercat inputs include assembled contigs, raw sequence reads from any platform, and unique peptide files obtained from proteomics with feature abundance counts tables. Mercat is the only software available that allows for direct analysis of data properties without a data-dependent search tools such as BLAST or diamond for compositional analysis of whole community shotgun sequencing (e.g. metagenomes and/or metatranscriptomes) or metaproteomic data.

Source record↗
DOE OSTI2017

Mercat

Mercat is a highly scalable property software package for robust of analysis of features in next-generation sequencing data and observed unique peptides from metaproteomic data. Mercat is offered in python 3.5/anaconda3, is multiparellel and is easily installed using bioconda/conda recipes. Mercat inputs include assembled contigs, raw sequence reads from any platform, and unique peptide files obtained from proteomics with feature abundance counts tables. Mercat is the only software available that allows for direct analysis of data properties without a data-dependent search tools such as BLAST or diamond for compositional analysis of whole community shotgun sequencing (e.g. metagenomes and/or metatranscriptomes) or metaproteomic data.

Source record↗
DOE OSTI2015

RESONANT AMPLIFICATION OF TURBULENCE BY THE BLAST WAVES

We discuss the idea of whether spherical blast waves can amplify by a nonlocal resonant hydrodynamic mechanism inhomogeneities formed by turbulence or phase segregation in the interstellar medium. We consider the problem of a blast-wave-turbulence interaction in the Linear Interaction Approximation. Mathematically, this is an eigenvalue problem for finding the structure and amplitude of eigenfunctions describing the response of the shock-wave flow to forced oscillations by external perturbations in the ambient interstellar medium. Linear analysis shows that the blast wave can amplify density and vorticity perturbations for a wide range of length scales with amplification coefficients of up to 20, with increasing amplification the larger the length. There also exist resonant harmonics for which the gain becomes formally infinite in the linear approximation. Their orbital wavenumbers are within the range of macro- (l ∼ 1), meso- (l ∼ 20), and microscopic (l > 200) scales. Since the resonance width is narrow (typically, Δl < 1), resonance should select and amplify discrete isolated harmonics. We speculate on a possible explanation of an observed regular filamentary structure of regularly shaped round supernova remnants such as SNR 1572, 1006, or 0509-67.5. Resonant mesoscales found (l ≈ 18) are surprisingly close to the observed scales (l ≈ 15) of ripples in the shell's surface of SNR 0509-67.5.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

A Pilot Study of Whole-Blood Transcriptomic Analysis to Identify Genes Associated with Repetitive Low-Level Blast Exposure in Career Breachers

Repetitive low-level blast exposure is one of the major occupational health concerns among US military service members and law enforcement. This study seeks to identify gene expression using microRNA and RNA sequencing in whole-blood samples from experienced breachers and unexposed controls. We performed experimental RNA sequencing using Illumina’s HiSeq 2500 Sequencing System, and microRNA analysis using NanoString Technology nCounter miRNA expression panel in whole-blood total RNA samples from 15 experienced breachers and 14 age-, sex-, and race-matched unexposed controls. We identified 10 significantly dysregulated genes between experienced breachers and unexposed controls, with FDR corrected <0.05: One upregulated gene, LINC00996 (long intergenic non-protein coding RNA 996); and nine downregulated genes, IGLV3-16 (immunoglobulin lambda variable 3-16), CD200 (CD200 molecule), LILRB5 (leukocyte immunoglobulin-like receptor B5), ZNF667-AS1 (ZNF667 antisense RNA 1), LMOD1 (leiomodin 1), CNTNAP2 (contactin-associated protein 2), EVPL (envoplakin), DPF3 (double PHD fingers 3), and IGHV4-34 (immunoglobulin heavy variable 4-34). The dysregulated gene expressions reported here have been associated with chronic inflammation and immune response, suggesting that these pathways may relate to the risk of lasting neurological symptoms following high exposures to blast over a career.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

MerCat: a versatile k-mer counter and diversity estimator for database-independent property analysis obtained from metagenomic and/or metatranscriptomic sequencing data

MerCat is a parallel, highly scalable and modular property software package for robust analysis of features in next-generation sequencing data. MerCat inputs include assembled contigs and raw sequence reads from any platform resulting in feature abundance counts tables. MerCat allows for direct analysis of data properties without reference sequence database dependency commonly used by search tools such as BLAST and/or DIAMOND for compositional analysis of whole community shotgun sequencing (e.g. metagenomes and metatranscriptomes).

metabolomics↗
DOE OSTI2015

Measuring the Benefits of Public Chargers and Improving Infrastructure Deployments Using Advanced Simulation Tools: Preprint

With support from the U.S. Department of Energy's Vehicle Technologies Office, the National Renewable Energy Laboratory developed BLAST-V -- the Battery Lifetime Analysis and Simulation Tool for Vehicles. The addition of high-resolution spatial-temporal travel histories enables BLAST-V to investigate user-defined infrastructure rollouts of publically accessible charging infrastructure, as well as quantify impacts on vehicle and station owners in terms of improved vehicle utility and station throughput. This paper presents simulation outputs from BLAST-V that quantify the utility improvements of multiple distinct rollouts of publically available Level 2 electric vehicle supply equipment (EVSE) in the Seattle, Washington, metropolitan area. Publically available data on existing Level 2 EVSE are also used as an input to BLAST-V. The resulting vehicle utility is compared to a number of mock rollout scenarios. Discussion focuses on the estimated number of Level 2 stations necessary to substantially increase vehicle utility and how stations can be strategically sited to maximize their potential benefit to prospective electric vehicle owners.

25 ENERGY STORAGE↗
DOE OSTI2018

Semi‐dominant mutation in the cysteine‐rich receptor‐like kinase gene, ALS 1 , conducts constitutive defence response in rice

Abstract Plants have evolved a sophisticated two‐branch defence system to prevent the growth and spread of pathogen infection. The novel Cys‐rich repeat ( CRR ) containing receptor‐like kinases, known as CRK s, were reported to mediate defence resistance in plants. For rice, there are only two reports of CRK s. A semi‐dominant lesion mimic mutant als1 (apoptosis leaf and sheath 1) in rice was identified to demonstrate spontaneous lesions on the leaf blade and sheath. A map‐based cloning strategy was used for fine mapping and cloning of ALS 1 , which was confirmed to be a typical CRK in rice. Functional studies of ALS 1 were conducted, including phylogenetic analysis, expression analysis, subcellular location and blast resistance identification. Most pathogenesis‐related ( PR ) genes and other defence‐related genes were activated and up‐regulated to a high degree. ALS 1 was expressed mainly in the leaf blade and sheath, in which further study revealed that ALS 1 was present in the vascular bundles. ALS 1 was located in the cell membrane of rice protoplasts, and its mutation did not change its subcellular location. Jasmonic acid ( JA ) and salicylic acid ( SA ) accumulation were observed in als1 , and enhanced blast resistance was also observed. The mutation of ALS 1 caused a constitutively activated defence response in als1 . The results of our study imply that ALS 1 participates in a defence response resembling the common SA ‐, JA ‐ and NH 1 ‐mediated defence responses in rice.

Du, D.↗
DOE OSTI2020

Effects of High Fuel Loading and CO2 Dilution on Oxy-Methane Ignition Inside a Shock Tube at High Pressure

Abstract Ignition delay times were measured for methane/O2 mixtures in a high dilution environment of either CO2 or N2 using a shock tube facility. Experiments were performed between 1044 K and 1356 K at pressures near 16 ± 2 atm. Test mixtures had an equivalence ratio of 1.0 with 16.67% CH4, 33.33% O2, and 50% diluent. Ignition delay times were measured using OH* emission and pressure time-histories. Data were compared to the predictions of two literature kinetic mechanisms (ARAMCO MECH 2.0 and GRI Mech 3.0). Most experiments showed inhomogeneous (mild) ignition which was deduced from five time-of-arrival pressure transducers placed along the driven section of the shock tube. Further analysis included determination of blast wave velocities and locations away from the end wall of initial detonations. Blast velocities were 60–80% of CJ-Detonation calculations. A narrow high temperature region within the range was identified as showing homogenous (strong) ignition which showed generally good agreement with model predictions. Model comparisons with mild ignition cases should not be used to further refine kinetic mechanisms, though at these conditions, insight was gained into various ignition behavior. To the best of our knowledge, we present first shock tube data during ignition of high fuel loading CH4/O2 mixtures diluted with CO2 and N2.

Energy & Fuels↗
DOE OSTI2019

Energy Consumption and CO 2 Emissions in Ironmaking and Development of a Novel Flash Technology

The issues of energy consumption and CO 2 emissions of major ironmaking processes, including several new technologies, are assessed. These two issues are interconnected in that the production and use of fuels to generate energy add to the total amount of CO 2 emissions and the efforts to sequester or convert CO 2 require energy. The amounts of emissions and energy consumption in alternate ironmaking processes are compared with those for the blast furnace, currently the dominant ironmaking process. Although more than 90% of iron production is currently through the blast furnace, intense efforts are devoted to developing alternative technologies. Recent developments in alternate ironmaking processes, which are largely driven by the needs to decrease CO 2 emissions and energy consumption, are discussed in this article. This discussion will include the description of the recently developed novel flash ironmaking technology. This technology bypasses the cokemaking and pelletization/sintering steps, which are pollution prone and energy intensive, by using iron ore concentrate. This transformational technology renders large energy saving and decreased CO 2 emissions compared with the blast furnace process. Economic analysis indicated that this new technology, when operated using natural gas, would be economically feasible. As a related topic, we will also discuss different methods for computing process energy and total energy requirements in ironmaking.

36 MATERIALS SCIENCE↗