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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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9 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Modeling ozone episodes in the Baltimore-Washington region

Surface ozone (O3) concentrations in excess of the National Ambient Air Quality Standard (NAAQS) continue to occur in metropolitan areas in the United States despite efforts to control emissions of O3 precursors. Future O3 control strategies will be based on results from modeling efforts that have just begun in many areas. Two initial questions that arise are model sensitivity to domain-specific conditions and the selection of episodes for model evaluation and control strategy development. For the Baltimore-Washington region (B-W), the presence of the Chesapeake Bay introduces a number of issues relevant to model sensitivity. In this paper, the specific questions of the determination of model volume (mixing height) for the Urban Airshed Model (UAM) is discussed and various alternative methods compared. For the latter question, several analytic approaches, Cluster Analysis and classification and Regression Tree (CART) analysis are undertaken to determine meteorological conditions associated with severe O3 events in the B-W domain.

Ryan, William F.↗
DOE OSTI2020

Dynamic Response of a Semiactive Suspension System with Hysteretic Nonlinear Energy Sink Based on Random Excitation by means of Computer Simulation

This paper aims to investigate the property and behavior of the hysteretic nonlinear energy sink (HNES) coupled to a half vehicle system which is a nine-degree-of-freedom, nonlinear, and semiactive suspension system in order to improve the ride comfort and increase the stability in shock mitigation by using the computer simulation method. The HNES model is a semiactive suspension device, which comprises the famous Bouc–Wen (B-W) model employed to describe the force produced by both the purely hysteretic spring and linear elastic spring of potentially negative stiffness connected in parallel, for the half vehicle system. Nine nonlinear motion equations of the half vehicle system are derived in terms of the seven displacements and the two dimensionless hysteretic variables, which are integrated numerically by employing the direct time integration method for studying both the variables of vertical displacements, velocities, accelerations, chassis pitch angle, and the ride comfort and driver safety, respectively, based on the bump and random road inputs of the pseudoexcitation method as excitation signal. Simulation results show that, compared with the HNES model and the magnetorheological (MR) model coupled to the half vehicle system, the ride comfort and stability have been evidently improved. A successful validation process has been performed, which indicated that both the ride comfort and driver safety properties of the HNES model coupled to half vehicle significantly improved.

Chen, Hui↗
DOE OSTI2020

Materials Data on B2W by Materials Project

WB2 is hexagonal omega structure structured and crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. W6+ is bonded to twelve equivalent B3- atoms to form a mixture of edge and face-sharing WB12 cuboctahedra. All W–B bond lengths are 2.43 Å. B3- is bonded in a 3-coordinate geometry to six equivalent W6+ and three equivalent B3- atoms. All B–B bond lengths are 1.74 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BW2 by Materials Project

W2B is Khatyrkite structured and crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. W is bonded in a 4-coordinate geometry to four equivalent B atoms. All W–B bond lengths are 2.40 Å. B is bonded in a 8-coordinate geometry to eight equivalent W atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on B2W by Materials Project

WB2 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. W6+ is bonded in a 10-coordinate geometry to ten B3- atoms. There are a spread of W–B bond distances ranging from 2.22–2.38 Å. There are three inequivalent B3- sites. In the first B3- site, B3- is bonded in a 9-coordinate geometry to six equivalent W6+ and three equivalent B3- atoms. All B–B bond lengths are 1.74 Å. In the second B3- site, B3- is bonded in a 9-coordinate geometry to six equivalent W6+ and three equivalent B3- atoms. In the third B3- site, B3- is bonded in a 7-coordinate geometry to four equivalent W6+ and three equivalent B3- atoms. All B–B bond lengths are 1.86 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on B5W2 by Materials Project

W2B5 is Tungsten boride structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. W+4.50+ is bonded in a 10-coordinate geometry to thirteen B+1.80- atoms. There are a spread of W–B bond distances ranging from 2.31–2.63 Å. There are four inequivalent B+1.80- sites. In the first B+1.80- site, B+1.80- is bonded in a 10-coordinate geometry to four equivalent W+4.50+ and six B+1.80- atoms. There is three shorter (1.83 Å) and three longer (1.95 Å) B–B bond length. In the second B+1.80- site, B+1.80- is bonded to six equivalent W+4.50+ and six equivalent B+1.80- atoms to form distorted face-sharing BB6W6 cuboctahedra. In the third B+1.80- site, B+1.80- is bonded in a 9-coordinate geometry to six equivalent W+4.50+ and three equivalent B+1.80- atoms. All B–B bond lengths are 1.79 Å. In the fourth B+1.80- site, B+1.80- is bonded in a 9-coordinate geometry to six equivalent W+4.50+ and three equivalent B+1.80- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BW by Materials Project

BW1 is delta Molybdenum Boride structured and crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. W3+ is bonded in a 7-coordinate geometry to seven equivalent B3- atoms. There are a spread of W–B bond distances ranging from 2.33–2.50 Å. B3- is bonded in a 9-coordinate geometry to seven equivalent W3+ and two equivalent B3- atoms. Both B–B bond lengths are 1.90 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on B5W2 by Materials Project

W2B5 is Tungsten boride-like structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. W+4.50+ is bonded in a 10-coordinate geometry to thirteen B+1.80- atoms. There are a spread of W–B bond distances ranging from 2.33–2.64 Å. There are three inequivalent B+1.80- sites. In the first B+1.80- site, B+1.80- is bonded to six equivalent W+4.50+ and six equivalent B+1.80- atoms to form distorted face-sharing BB6W6 cuboctahedra. All B–B bond lengths are 1.83 Å. In the second B+1.80- site, B+1.80- is bonded in a 10-coordinate geometry to four equivalent W+4.50+ and six B+1.80- atoms. All B–B bond lengths are 1.96 Å. In the third B+1.80- site, B+1.80- is bonded in a 9-coordinate geometry to six equivalent W+4.50+ and three equivalent B+1.80- atoms. All B–B bond lengths are 1.79 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BW by Materials Project

BW1 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. W3+ is bonded in a 7-coordinate geometry to seven equivalent B3- atoms. There are a spread of W–B bond distances ranging from 2.34–2.51 Å. B3- is bonded in a 9-coordinate geometry to seven equivalent W3+ and two equivalent B3- atoms. Both B–B bond lengths are 1.87 Å.

36 MATERIALS SCIENCE↗