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

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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Crystallization and preliminary X-ray crystallographic analysis of YfcM: an important factor for EF-P hydroxylation

E. coli YfcM was expressed, purified and crystallized. Crystals of YfcM were obtained by the in situ proteolysis crystallization method. Using these crystals, an X-ray diffraction data set was collected at 1.45 Å resolution. Elongation factor P (EF-P) plays an essential role in the translation of polyproline-containing proteins in bacteria. It becomes functional by the post-translational modification of its highly conserved lysine residue. It is first β-lysylated by PoxA and then hydroxylated by YfcM. In this work, the YfcM protein from Escherichia coli was overexpressed, purified and crystallized. The crystal of YfcM was obtained by the in situ proteolysis crystallization method and diffracted X-rays to 1.45 Å resolution. It belonged to space group C2, with unit-cell parameters a = 124.4, b = 37.0, c = 37.6 Å, β = 101.2°. The calculated Matthews coefficient (V{sub M}) of the crystal was 1.91 Å{sup 3} Da{sup −1}, indicating that one YfcM molecule is present in the asymmetric unit with a solvent content of 35.7%.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Synthesis, Structure, IR-Spectroscopic Characterization, and Ionic Conductivity of Mg{sub 0.5}Zr{sub 2}(AsO{sub 4}){sub x}(PO{sub 4}){sub 3−x}

Mg{sub 0.5}Zr{sub 2}(AsO{sub 4}){sub x}(PO{sub 4}){sub 3−x} arsenate phosphates have been prepared by a sol–gel process and characterized by X-ray diffraction, IR spectroscopy, and impedance spectroscopy. The results indicate the formation of a continuous series of solid solutions with the Sc{sub 2}(WO{sub 4}){sub 3} structure (sp. gr. P2{sub 1/n}) in the composition range 0 < x < 3. The unit-cell parameters of the solid solutions increase linearly with composition, as a consequence of arsenic substitution for phosphorus, which has a smaller ionic radius. The number of observed stretching and bending bands of the AsO{sub 4}{sup 3-} and PO{sub 4}{sup 3-} ions in the IR spectra of the solid solutions agrees with that predicted by factor group analysis for space group P2{sub 1/n}. The observed gradual shift of the absorption bands of the AsO{sub 4} tetrahedra to lower frequencies with increasing arsenic content on the tetrahedral site supports the X-ray diffraction evidence of the formation of substitutional solid solutions. The cation conductivity of Mg{sub 0.5}Zr{sub 2}(AsO{sub 4}){sub x}(PO{sub 4}){sub 3−x} with 0 ≤ х ≤ 1 has been shown to exceed the conductivity of the parent magnesium zirconium arsenate.

36 MATERIALS SCIENCE↗
DOE OSTI2017

LUNUS, Version 0.1a

LUNUS software for generating 3D maps of diffuse scattering from macromolecular X-ray crystallography diffraction images. A set of tools needed for advanced refinement of crystal structures and crystallographic charge density models. Includes tools for processing X--ray diffraction images, charge density maps, and structure factors for analysis of diffuse X-ray scattering and charge density variations in crystallography. Specific methods include: elementary algebraic operations on images and 3D lattices; fourier transform of images and 3D lattices; image processing to measure diffuse intensity; crystallographic refinement; and 3D integration of diffuse intensity.

Wall, Michael↗
DOE OSTI2023

Factors Influencing Adoption of Pooled Rideshare An Explorative Study on User-Centered Design and Services

The rise of real-time information communication through smartphones and wireless networks enabled the growth of ridesharing services. While personal rideshare services (individuals ride alone or with people they know) initially dominated the market, the popularity of pooled ridesharing (individuals share rides with strangers) has grown globally. However, pooled rideshare remains less common in the U.S., where personal vehicle usage is still the norm. Vehicle design and rideshare services may need to be tailored to user preferences to increase pooled rideshare adoption. A national U.S. survey ( N = 5,385) used exploratory and confirmatory factor analyses to identify four key factors influencing riders’ willingness to consider pooled rideshare: comfort/ease of use, convenience, vehicle technology/accessibility, and passenger safety. Understanding and implementing these user-centered design principles and service-related factors may be critical for increasing the future use of pooled rideshare services

Gangadharaiah, Rakesh↗
DOE OSTI2022

Impact of Polymer Rheology on Gel Treatment Performance of Horizontal Wells with Severe Channeling

Summary Gel treatment has been a cost-effective method to control the conformance of a reservoir with severe heterogeneity problems. The water channels in such reservoirs can be classified as open fractures or high permeability porous media with pore-throat network. Many simulation studies have been conducted to discuss gel treatment performance for conformance control. However, nobody considered the polymer rheology difference in open fractures and porous media in simulation. Previous simulation studies also ignored the residual resistance factor as a function of rock permeability rather than a constant parameter. In this study, a conceptual simulation model was established to simulate the linear flow system for the reservoir with horizontal wells considering the two factors mentioned above. The results demonstrate that the gel treatment always provides the better placement results in the open fracture type channel than pore-throat network type channel. Moreover, it is very necessary to consider residual resistance factor as a function of permeability, which is based on the experimental results and can provide much greater plugging efficiency in the higher permeable channels than constant residual resistance factor. Sensitivity analysis studies and multifactor analysis indicate that increasing oil viscosity and permeability ratio has a strong positive influence on conformance control results, which indicate in-situ gel treatment can be better applied in heavy or viscous oil reservoirs with fracture-like channels. Besides, the results also indicate that in reservoirs with severe channeling problem where channel velocity was high, the differences of gelant placement and profile improvement in models with two different types of channels could be enlarged greatly.

Engineering↗
DOE OSTI2012

A new approach to quantification of margins and uncertainties for physical simulation data

Historically, Quantification of Margins and Uncertainties (QMU) for physical simulation test data has been centered on the calculation of a -factor and/or a regression analysis of the k -factor against age. The k- factor, in general, is defined as margin divided by uncertainty. The most common interpretation of this definition, employed in a data rich environment, is where the margin is estimated by the difference between a defined requirement and the average response of the data and the uncertainty is estimated by the sample standard deviation of the data. These definitions are captured in the Annual Assessment RMI and are shown below.

Newcomer, Justin T.↗
DOE OSTI2014

Enhanced Component Performance Study. Emergency Diesel Generators 1998–2013

This report presents an enhanced performance evaluation of emergency diesel generators (EDGs) at U.S. commercial nuclear power plants. This report evaluates component performance over time using Institute of Nuclear Power Operations (INPO) Consolidated Events Database (ICES) data from 1998 through 2013 and maintenance unavailability (UA) performance data using Mitigating Systems Performance Index (MSPI) Basis Document data from 2002 through 2013. The objective is to present an analysis of factors that could influence the system and component trends in addition to annual performance trends of failure rates and probabilities. The factors analyzed for the EDG component are the differences in failures between all demands and actual unplanned engineered safety feature (ESF) demands, differences among manufacturers, and differences among EDG ratings. Statistical analyses of these differences are performed and results showing whether pooling is acceptable across these factors. In addition, engineering analyses were performed with respect to time period and failure mode. The factors analyzed are: sub-component, failure cause, detection method, recovery, manufacturer, and EDG rating.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2019

Advanced truck and bus radial materials for fuel efficiencies (Final Report)

PPG Industries, Inc. and Bridgestone Americas Tire Operations (BATO) propose to develop a novel surface-modified silica technology and demonstrate 4-6% improved fuel efficiency of Truck and Bus Radial (TBR) tires built from the technology. The proposed fuel efficiency increase will be achieved while maintaining or improving tear strength and tread wear. During rubber mixing, distributing silica in the rubber matrix is a challenge. This is because silica has a very polar surface, while rubbers have little polarity. It was hypothesized that surface treatments could cover part of the surface by hydrophobic groups, and reduce the surface polarity, thus helping to wet the silica with rubber during mixing and improving silica dispersion. During the project, the effect of different silica surface treatments on the surface energy of silica were determined, and related to the silica dispersion in rubber compounds. The results demonstrated that reducing the surface energy of silica samples improved dispersion in rubber compounds. Also, the preference for silica to migrate to the different phases in polymer blends was determined. The studies performed in binary polymer blends showed that carbon black has a preference to distribute in the different polymer phases in the order: SBR>BR~NR. Commercially available silica samples (treated and untreated) showed a preference in the order of SBR>NR>BR. Finally, the silica prototypes showed a preference in the order SBR=NR>BR. The knowledge gained regarding dispersion of treated silicas in rubber compounds was used to perform a series of studies to develop a silica – rubber compound combination with optimum performance for TBR treads. Initially, two silica prototypes (BXR-990 and BXR-991) were developed and used for a tire build at BATO’s tire plant in Warren County, TN. Results were evaluated and further silica and compound optimization was performed, prior to a final tire build. Manufacturing of the final silica prototype (BXR-1006) for the final tire build was performed at the PPG Silicas Pilot Plant in Monroeville, PA. Afterwards, experimental tires with silica-filled treads and control tires with carbon black-filled treads were built at BATO’s Warren County tire plant. The experimental TBR tires with silica-filled treads achieved the project goals for lab performance indicators, tread hardness and tear strength. The tires showed a 2.2% improvement in fuel efficiency compared to the control tires. While this improvement is lower than the 4% goal set initially, the improvement is significant and there are indicators that up to a 5% improvement in fuel efficiency could be achieved. This is supported by the confirmation of the validity of the fuel efficiency indicators made at the beginning of the project, and by the improvement in hysteresis and rolling resistance from tires built earlier in the project. The experimental tires produced using the BXR-990 silica prototype showed 47% improvement in tan δ at 60°C and 16% improvement in rolling resistance. Based on the results obtained, it is valid to estimate that the tires built with BXR-990 could provide around a 5% improvement in fuel efficiency, should we perform a fuel efficiency test. Tire wear for the experimental tires was 31% worse than for the control tires with the carbon black-filled tread compound. Other tools and further analysis of factors affecting wear are necessary to be evaluated to produce a silica tire with wear comparable to carbon black. Experimental and control tires were provided to the DOE for independent testing.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2026

Human Factors Considerations for Hydrogen Rail Refueling and Maintenance

The Federal Railroad Administration (FRA) contracted Sandia National Laboratories to review the risks introduced specifically through human interactions within hydrogen rail refueling and maintenance activities and present recommendations for future system development and implementation. Due to the lack of domestic hydrogen-powered trains at the time of review, observational data was collected on analogous existing systems to consider various ways hydrogen might be implemented within future designs. The team developed 50 human factors design guidelines through analysis of human risk factors. Because hydrogen rail systems are still in the early design stage, the resulting human factors guidelines represent general best practices and do not include specific design features. The research team recommends design and regulatory agencies include a Human Factors Engineer in the design and review process to ensure the guidelines are appropriately implemented and verified.

08 HYDROGEN↗
DOE OSTI2017

A Multivariate Dynamic Spatial Factor Model for Speciated Pollutants and Adverse Birth Outcomes

Evidence suggests that exposure to elevated concentrations of air pollution during pregnancy is associated with increased risks of birth defects and other adverse birth outcomes. While current regulations put limits on total PM2.5 concentrations, there are many speciated pollutants within this size class that likely have distinct effects on perinatal health. However, due to correlations between these speciated pollutants, it can be difficult to decipher their effects in a model for birth outcomes. To combat this difficulty, we develop a multivariate spatio-temporal Bayesian model for speciated particulate matter using dynamic spatial factors. These spatial factors can then be interpolated to the pregnant women’s homes to be used to model birth defects. The birth defect model allows the impact of pollutants to vary across different weeks of the pregnancy in order to identify susceptible periods. Here, the proposed methodology is illustrated using pollutant monitoring data from the Environmental Protection Agency and birth records from the National Birth Defect Prevention Study.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

A User-Centered Design Exploration of Factors That Influence the Rideshare Experience

The rise of real-time information communication through smartphones and wireless networks enabled the growth of ridesharing services. While personal rideshare services (individuals riding alone or with acquaintances) initially dominated the market, the popularity of pooled ridesharing (individuals sharing rides with people they do not know) has grown globally. However, pooled ridesharing remains less common in the U.S., where personal vehicle usage is still the norm. Vehicle design and rideshare services may need to be tailored to user preferences to increase pooled rideshare adoption. Based on a large, national U.S. survey (N = 5385), the results of exploratory and confirmatory factor analyses suggested that four key factors influence riders’ willingness to consider pooled ridesharing: comfort/ease of use, convenience, vehicle technology/accessibility, and passenger safety. A binomial logistic regression was conducted to determine how the four factors influence one’s willingness to consider pooled ridesharing. The two factors that positively influence riders’ willingness to consider pooled ridesharing are vehicle technology/accessibility (B = 1.10) and convenience (B = 0.94), while lack of passenger safety (B = –0.63) and comfort/ease of use (B = –0.17) are pooled ridesharing deterrents. Understanding user-centered design and service factors are critical to increase the use of pooled ridesharing services in the future.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2014

Stress Intensity of Delamination in a Sintered-Silver Interconnection: Preprint

In automotive power electronics packages, conventional thermal interface materials such as greases, gels, and phase-change materials pose bottlenecks to heat removal and are also associated with reliability concerns. The industry trend is toward high thermal performance bonded interfaces for large-area attachments. However, because of coefficient of thermal expansion mismatches between materials/layers and resultant thermomechanical stresses, adhesive and cohesive fractures could occur, posing a reliability problem. These defects manifest themselves in increased thermal resistance. This research aims to investigate and improve the thermal performance and reliability of sintered-silver for power electronics packaging applications. This has been experimentally accomplished by the synthesis of large-area bonded interfaces between metalized substrates and copper base plates that have subsequently been subjected to thermal cycles. A finite element model of crack initiation and propagation in these bonded interfaces will allow for the interpretation of degradation rates by a crack-velocity (V)-stress intensity factor (K) analysis. A description of the experiment and the modeling approach are discussed.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2023

Source apportionment of soot particles and aqueous-phase processing of black carbon coatings in an urban environment

Abstract. The impacts of soot particles on climate and human health depend on the concentration of black carbon (BC) as well as the thickness and composition of the coating material, i.e., organic and inorganic compounds internally mixed with BC. In this study, the size-resolved chemical composition of BC-containing aerosol was measured using a high-resolution soot particle aerosol mass spectrometer (SP-AMS) during wintertime in Fresno, California, a location influenced by abundant combustion emissions and frequent fog events. Concurrently, particle optical properties were measured to investigate the BC absorption enhancement. Positive matrix factorization (PMF) analysis was performed on the SP-AMS mass spectral measurements to explore the sources of soot particles and the atmospheric processes affecting the properties of BC coatings. The analysis revealed that residential woodburning and traffic are the dominant sources of soot particles. Alongside primary soot particles originating from biomass burning (BBOABC) and vehicles (HOABC) two distinct types of processed BC-containing aerosol were identified: fog-related oxidized organic aerosol (FOOABC) and winter-background OOABC (WOOABC). Both types of OOABC showed evidence of having undergone aqueous processing, albeit with differences. The concentration of FOOABC was substantially elevated during fog events, indicating the formation of aqueous secondary organic aerosol (aqSOA) within fog droplets. On the other hand, WOOABC was present at a relatively consistent concentration throughout the winter and was likely related to the formation of secondary organic aerosol (SOA) in both the gas phase and aerosol liquid water. By comparing the chemical properties and temporal variations in FOOABC and WOOABC, we gain insights into the key aging processes of BC aerosol. It was found that aqueous-phase reactions facilitated by fog droplets had a significant impact on the thickness and chemical composition of BC coatings, thereby affecting the light absorption and hygroscopic properties of soot particles. These findings underscore the important role of chemical reactions occurring within clouds and fogs and influencing the climate forcing of BC aerosol in the atmosphere.

54 ENVIRONMENTAL SCIENCES↗