Analysis of pressure distributions for a series of tip and trailing-edge controls on a 60 deg wing at Mach numbers of 1.61 and 2.01
Supersonic pressure distributions for tip and trailing edge controls on 60 deg delta wing
TRAILING EDGE↗
SEARCH · Engineering Papers
Results for “K edge”
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.
Utilization of cascade data in axial-flow compressor design and analysis - A critical review
Axial flow compressor off-design performance optimization by adjustable inlet guide vanes with variable trailing edge flaps
Serovy, G. K.↗
Low-speed aerodynamic characteristics of a 13.1-percent-thick, high-lift airfoil
Experimental study of the low-speed, sectional characteristics of a high-lift airfoil, and comparison of these characteristics with the predictions of the theoretical methods used in the airfoil's design. The 13.1% thick UI-1720 airfoil was found to achieve the predicted maximum lift coefficient of nearly 2.0. No upper-surface flow separation was found below the stall angle of attack of 16 deg; it appeared that stall was due to an abrupt leading-edge flow separation.
Sivier, K. R.↗
Low-speed aerodynamic characteristics of a 13.1-percent-thick, high-lift airfoil
Low speed sectional characteristics of a high lift airfoil are studied and a comparison is made of those characteristics with the predictions of the theoretical methods used in the airfoil's design. The 13.1 percent-thick, UI-1720 airfoil was found to achieve the predicted maximum lift coefficient of nearly 2.0. No upper-surface, flow separation was found below the stall angle of attack of 16 degrees; it appeared that stall was due to an abrupt leading edge flow separation.
Sivier, K. R.↗
Mass loss of TEOS-coated RCC subjected to the environment at the shuttle wing leading edge
Coated, reinforced carbon-carbon (RCC) is used for the leading edges of the Space Shuttle. The mass loss characteristics of RCC specimens coated with tetra-ethyl-ortho-silicate (TEOS) were determined for conditions which simulated the entry environment expected at the stagnation area of the wing leading edge. Maximum specimen temperature was 1632 K. Specimens were exposed for up to 100 missions. Stress levels up to 8.274 MPa caused an average increase in oxidation of 6 percent over unstressed specimens. Experimentally determined mass losses were compared with those predicted by an existing empirical analysis.
Stroud, C. W.↗
Bifurcation and post-buckling analysis of laminated composite plates via reduced basis technique
A reduced basis technique and a problem-adaptive computational algorithm are presented for the bifurcation and post-buckling analysis of laminated anisotropic plates. The computational algorithm can be conveniently divided into three distinct stages. The first stage is that of determining the bifurcation point. The plate is discretized by using displacement finite element (or finite difference) models. The special symmetries exhibited by the response of the anisotropic plate are used to reduce the size of the analysis region. The vector of unknown nodal parameters is expressed as a linear combination of a small number of basis vectors, and a Rayleigh-Ritz technique is used to approximate the finite element equations by a small system of algebraic equations. The reduced equations are used to determine the bifurcation point and the associated eigenmode of the panel. In the second stage of the bifurcation buckling mode is used to obtain a nonlinear solution in the vicinity of the bifurcation point and new (updated) sets of basis vectors and reduced equations are generated. In the third stage the reduced equations are used to trace the post-buckling paths. The effectiveness of the proposed technique for predicting the bifurcation and post-buckling behavior of plates is demonstrated by means of numerical examples for plates loaded by means of prescribed edge displacements.
Noor, A. K.↗
Optimal frequency domain textural edge detection filter
An optimal frequency domain textural edge detection filter is developed and its performance evaluated. For the given model and filter bandwidth, the filter maximizes the amount of output image energy placed within a specified resolution interval centered on the textural edge. Filter derivation is based on relating textural edge detection to tonal edge detection via the complex low-pass equivalent representation of narrowband bandpass signals and systems. The filter is specified in terms of the prolate spheroidal wave functions translated in frequency. Performance is evaluated using the asymptotic approximation version of the filter. This evaluation demonstrates satisfactory filter performance for ideal and nonideal textures. In addition, the filter can be adjusted to detect textural edges in noisy images at the expense of edge resolution.
Townsend, J. K.↗
LWIR detector research in InAsSb/InAs
The InAsSb/InSb strained-layer system forms a type-II superlattice in the Sb-rich region of the phase diagram. The band gap of InAsSb/InSb strained-layer superlattices grown on lattice-matched buffers can be varied continuously to produce semiconducting systems with band gaps ranging from that of InSb (0.23 eV with an absorption edge at 5.5 microns at 77 K) to 0. The semiconductor to semimetal transition occurs at As concentrations of approximately 33 percent, with the precise value dependent upon the strain and quantum well dimensions. At higher As content, the system is a semimetal. The authors fabricated photovoltaic detectors with high D asterisk at 77 K at wavelengths beyond 10 microns, and both photovoltaic and photoconductive detectors have been demonstrated with response to 15 microns. The photoconductive detectors exhibit gain of up to 100. Details of the materials growth, studies of the band structure and properties, device processing and the detector performance observed to date in these systems are discussed.
Peercy, Paul S.↗
Response of silicon solar cell to pulsed laser illumination
The response of silicon solar cell(s) to pulsed laser illumination is discussed. The motivation was due to the interest of Earth to space/Moon power beaming applications. When this work began, it was not known if solar cells would respond to laser light with pulse lengths in the nanosecond range and a repetition frequency in the kHz range. This is because the laser pulse would be shorter than the minority carrier lifetime of silicon. A 20-nanosecond (ns) full width half max (FWHM) pulse from an aluminum-gallium/arsenide (Al-Ga-As) diode laser was used to illuminate silicon solar cells at a wavelength of 885 nanometers (nm). Using a high-speed digital oscilloscope, the response of the solar cells to individual pulses across various resistive loads was observed and recorded.
Willowby, D.↗
The Power of SS 433's Jets
We observed SS 433 for the third time with RXTE, this time simultaneously with a Nobeyama millimeter band monitoring campaign. These observations extended the RXTE coverage of SS 433's precession phases. and once again monitored the source during a binary eclipse. Our AO-2 campaign of a joint RXTE-VLBA-VLA-MERLIN observation was delayed to little more than a month before the AO-3 observations. We also had an AO-1 observation of SS 433. In each case we observed an eclipse of the compact ob'ect by the companion star, and had contemporaneous optical observations. We are analyzing all three sets of observations together. A publication is in preparation; Its completion will be supported by the remaining AO-2 funds. Here I will summarize the general results and point out the relevant features of the AO-3 observations. The spectrum is detected to approx. 50 keV, which is entirely within the PCA energy band. We find that the HEXTE data do not add significantly to the spectrum, and most of our fits are without HEXTE. We find that the continuum can be fit with a power law with an exponential cutoff; the photon index is usually approx. 1.4. A line at approx. 6.4 keV is definitely required, and the fits improve significant, if we add a second line, also with an energy in the iron K(alpha) complex, and an absorption edge. The edge usually has an energy of approx. 5.8 keV, which does not correspond to any known physical feature. and may be an instrumental artifact. This is under further investigation.
Band, David F.↗
Finite Element Modeling Used to Study Stress Distribution on the Foot
A method to study the stress distribution inside the forefoot during walking was developed at the Cleveland Clinic Foundation by a researcher from the NASA Glenn Research Center. In this method, a semiautomated process was outlined to create a three-dimensional, patient-specific, finite element model (FEM) of the forefoot using magnetic resonance images (MRI). The images were processed in Matlab using the k-nearest neighbor (k-NN) classification algorithm and Sobel edge detection to separate the different tissue types: bone, skin, fat, and muscle. This information was used to create curves and surfaces that were exported to an FEM preprocessor known as Truegrid. In Truegrid, eight-noded or brick elements were created by using surface mapping. The FEM was processed and postprocessed in Abaqus. Material properties of the models were obtained from past experiments such as fat pad confined compression, skin axial and biaxial tests, muscle in vivo compressive tests, and reference literature (bone properties). Nonlinear (hyperelastic) material models were used for the skin (epidermis and dermis), fat, and muscles; and a linear elastic model was used for the bones. Muscle activation during walking yielded uncertainties in the muscle material model since contracted muscles are stiffer than relaxed muscles. These uncertainties were resolved by performing a sensitivity analysis of the muscle material properties. The original properties were multiplied by arbitrary factors of 2, 3, 0.5, and 0.33. The strain and stress distributions, as well as the locations of peak values, were similar in all cases. The peak contact pressure P obtained for each case varied with respect to the applied factor f as follows:
Morales, Nelson↗
Actuator energy and drag minimization of a blended-wing-body with variable-camber continuous trailing-edge flaps
Explore the source record for details and available documents.
Wei Zhao↗
Unsupervised Test-Time Adaptation of Deep Neural Networks at the Edge: A Case Study
Explore the source record for details and available documents.
Computer science↗
Materials Data on KYbF4 by Materials Project
KYbF4 crystallizes in the trigonal P3_2 space group. The structure is three-dimensional. there are six inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are a spread of K–F bond distances ranging from 2.66–3.23 Å. In the second K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YbF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six YbF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.59–3.20 Å. In the third K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.65–3.14 Å. In the fourth K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YbF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six YbF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.63–3.02 Å. In the fifth K1+ site, K1+ is bonded in a distorted body-centered cubic geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.63–2.90 Å. In the sixth K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YbF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six YbF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.62–3.10 Å. There are six inequivalent Yb3+ sites. In the first Yb3+ site, Yb3+ is bonded to seven F1- atoms to form YbF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent YbF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YbF7 pentagonal bipyramid. There are a spread of Yb–F bond distances ranging from 2.24–2.30 Å. In the second Yb3+ site, Yb3+ is bonded to seven F1- atoms to form YbF7 pentagonal bipyramids that share corners with five YbF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YbF7 pentagonal bipyramid. There are a spread of Yb–F bond distances ranging from 2.21–2.29 Å. In the third Yb3+ site, Yb3+ is bonded to seven F1- atoms to form YbF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent YbF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YbF7 pentagonal bipyramid. There are a spread of Yb–F bond distances ranging from 2.24–2.30 Å. In the fourth Yb3+ site, Yb3+ is bonded to seven F1- atoms to form YbF7 pentagonal bipyramids that share corners with five YbF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YbF7 pentagonal bipyramid. There are a spread of Yb–F bond distances ranging from 2.25–2.27 Å. In the fifth Yb3+ site, Yb3+ is bonded to seven F1- atoms to form YbF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent YbF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YbF7 pentagonal bipyramid. There are a spread of Yb–F bond distances ranging from 2.21–2.33 Å. In the sixth Yb3+ site, Yb3+ is bonded to seven F1- atoms to form YbF7 pentagonal bipyramids that share corners with five YbF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YbF7 pentagonal bipyramid. There are a spread of Yb–F bond distances ranging from 2.22–2.32 Å. There are twenty-four inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Yb3+ atoms. In the second F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two K1+ and two Yb3+ atoms. In the third F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two equivalent Yb3+ atoms. In the fourth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to one K1+ and two Yb3+ atoms. In the fifth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Yb3+ atoms. In the sixth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Yb3+ atoms. In the seventh F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Yb3+ atoms. In the eighth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two K1+ and two equivalent Yb3+ atoms. In the ninth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Yb3+ atoms. In the tenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Yb3+ atoms. In the eleventh F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two equivalent Yb3+ atoms. In the twelfth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Yb3+ atoms. In the thirteenth F1- site, F1- is bonded to three K1+ and one Yb3+ atom to form a mixture of edge and corner-sharing FK3Yb tetrahedra. In the fourteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Yb3+ atoms. In the fifteenth F1- site, F1- is bonded to three K1+ and one Yb3+ atom to form a mixture of distorted edge and corner-sharing FK3Yb tetrahedra. In the sixteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Yb3+ atoms. In the seventeenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Yb3+ atoms. In the eighteenth F1- site, F1- is bonded to three K1+ and one Yb3+ atom to form a mixture of distorted edge and corner-sharing FK3Yb tetrahedra. In the nineteenth F1- site, F1- is bonded in a 3-coordinate geometry to two K1+ and two Yb3+ atoms. In the twentieth F1- site, F1- is bonded to three K1+ and one Yb3+ atom to form a mixture of distorted edge and corner-sharing FK3Yb tetrahedra. In the twenty-first F1- site, F1- is bonded to three K1+ and one Yb3+ atom to form a mixture of distorted edge and corner-sharing FK3Yb tetrahedra. In the twenty-second F1- site, F1- is bonded in a 3-coordinate geometry to two K1+, two Yb3+, and one F1- atom. The F–F bond length is 2.00 Å. In the twenty-third F1- site, F1- is bonded in a 3-coordinate geometry to two K1+, two Yb3+, and one F1- atom. In the twenty-fourth F1- site, F1- is bonded to three K1+ and one Yb3+ atom to form a mixture of distorted edge and corner-sharing FK3Yb tetrahedra.
36 MATERIALS SCIENCE↗
Materials Data on KTmF4 by Materials Project
KTmF4 crystallizes in the trigonal P3_2 space group. The structure is three-dimensional. there are six inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 4-coordinate geometry to nine F1- atoms. There are a spread of K–F bond distances ranging from 2.61–3.29 Å. In the second K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one TmF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six TmF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.54–3.05 Å. In the third K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.58–3.05 Å. In the fourth K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one TmF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six TmF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.58–3.01 Å. In the fifth K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.58–2.93 Å. In the sixth K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one TmF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six TmF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.60–3.05 Å. There are six inequivalent Tm3+ sites. In the first Tm3+ site, Tm3+ is bonded to seven F1- atoms to form TmF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent TmF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one TmF7 pentagonal bipyramid. There are a spread of Tm–F bond distances ranging from 2.12–2.28 Å. In the second Tm3+ site, Tm3+ is bonded to seven F1- atoms to form TmF7 pentagonal bipyramids that share corners with five TmF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one TmF7 pentagonal bipyramid. There are a spread of Tm–F bond distances ranging from 2.18–2.25 Å. In the third Tm3+ site, Tm3+ is bonded to seven F1- atoms to form TmF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent TmF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one TmF7 pentagonal bipyramid. There are a spread of Tm–F bond distances ranging from 2.12–2.27 Å. In the fourth Tm3+ site, Tm3+ is bonded to seven F1- atoms to form TmF7 pentagonal bipyramids that share corners with five TmF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one TmF7 pentagonal bipyramid. There are a spread of Tm–F bond distances ranging from 2.18–2.25 Å. In the fifth Tm3+ site, Tm3+ is bonded to seven F1- atoms to form TmF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent TmF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one TmF7 pentagonal bipyramid. There are a spread of Tm–F bond distances ranging from 2.12–2.27 Å. In the sixth Tm3+ site, Tm3+ is bonded to seven F1- atoms to form TmF7 pentagonal bipyramids that share corners with five TmF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one TmF7 pentagonal bipyramid. There are a spread of Tm–F bond distances ranging from 2.17–2.25 Å. There are twenty-four inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the second F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Tm3+ atoms. In the third F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two equivalent Tm3+ atoms. In the fourth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Tm3+ atoms. In the fifth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Tm3+ atoms. In the sixth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Tm3+ atoms. In the seventh F1- site, F1- is bonded in a distorted linear geometry to one K1+ and two Tm3+ atoms. In the eighth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two equivalent Tm3+ atoms. In the ninth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Tm3+ atoms. In the tenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the eleventh F1- site, F1- is bonded in a 3-coordinate geometry to one K1+ and two equivalent Tm3+ atoms. In the twelfth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Tm3+ atoms. In the thirteenth F1- site, F1- is bonded to three K1+ and one Tm3+ atom to form a mixture of edge and corner-sharing FK3Tm tetrahedra. In the fourteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the fifteenth F1- site, F1- is bonded to three K1+ and one Tm3+ atom to form a mixture of distorted edge and corner-sharing FK3Tm tetrahedra. In the sixteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the seventeenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the eighteenth F1- site, F1- is bonded to three K1+ and one Tm3+ atom to form a mixture of distorted edge and corner-sharing FK3Tm tetrahedra. In the nineteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the twentieth F1- site, F1- is bonded to three K1+ and one Tm3+ atom to form a mixture of distorted edge and corner-sharing FK3Tm tetrahedra. In the twenty-first F1- site, F1- is bonded to three K1+ and one Tm3+ atom to form a mixture of distorted edge and corner-sharing FK3Tm tetrahedra. In the twenty-second F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the twenty-third F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Tm3+ atoms. In the twenty-fourth F1- site, F1- is bonded to three K1+ and one Tm3+ atom to form a mixture of distorted edge and corner-sharing FK3Tm tetrahedra.
36 MATERIALS SCIENCE↗
Materials Data on K3TaO2F7 by Materials Project
K3TaO2F7 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a 4-coordinate geometry to four equivalent F atoms. There are two shorter (2.63 Å) and two longer (2.71 Å) K–F bond lengths. In the second K site, K is bonded in a 8-coordinate geometry to one O and seven F atoms. The K–O bond length is 3.00 Å. There are a spread of K–F bond distances ranging from 2.51–3.19 Å. Ta is bonded in a distorted pentagonal bipyramidal geometry to two equivalent O and five F atoms. Both Ta–O bond lengths are 2.12 Å. There are a spread of Ta–F bond distances ranging from 1.92–1.95 Å. O is bonded in a 3-coordinate geometry to one K, one Ta, and one O atom. The O–O bond length is 1.35 Å. There are five inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to two equivalent K and one Ta atom. In the second F site, F is bonded in a distorted single-bond geometry to two equivalent K and one Ta atom. In the third F site, F is bonded to four K atoms to form a mixture of distorted edge and corner-sharing FK4 trigonal pyramids. In the fourth F site, F is bonded in a distorted trigonal planar geometry to two equivalent K and one Ta atom. In the fifth F site, F is bonded in a distorted single-bond geometry to two equivalent K and one Ta atom.
36 MATERIALS SCIENCE↗
Materials Data on KLaCO4 by Materials Project
LaKOCO3 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one K2O2 sheet oriented in the (0, 0, 1) direction and one LaCO3 sheet oriented in the (0, 0, 1) direction. In the K2O2 sheet, there are four inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to five O2- atoms to form a mixture of edge and corner-sharing KO5 square pyramids. There are a spread of K–O bond distances ranging from 2.57–2.98 Å. In the second K1+ site, K1+ is bonded to five O2- atoms to form a mixture of edge and corner-sharing KO5 square pyramids. There are a spread of K–O bond distances ranging from 2.56–2.98 Å. In the third K1+ site, K1+ is bonded to five O2- atoms to form a mixture of edge and corner-sharing KO5 square pyramids. There are a spread of K–O bond distances ranging from 2.56–2.98 Å. In the fourth K1+ site, K1+ is bonded to five O2- atoms to form a mixture of edge and corner-sharing KO5 square pyramids. There are a spread of K–O bond distances ranging from 2.57–2.98 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to five K1+ atoms to form a mixture of edge and corner-sharing OK5 square pyramids. In the second O2- site, O2- is bonded to five K1+ atoms to form a mixture of edge and corner-sharing OK5 square pyramids. In the third O2- site, O2- is bonded to five K1+ atoms to form a mixture of edge and corner-sharing OK5 square pyramids. In the fourth O2- site, O2- is bonded to five K1+ atoms to form a mixture of edge and corner-sharing OK5 square pyramids. In the LaCO3 sheet, there are four inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a distorted hexagonal planar geometry to six O2- atoms. There are a spread of La–O bond distances ranging from 2.38–2.49 Å. In the second La3+ site, La3+ is bonded in a distorted hexagonal planar geometry to six O2- atoms. There are a spread of La–O bond distances ranging from 2.38–2.49 Å. In the third La3+ site, La3+ is bonded in a distorted hexagonal planar geometry to six O2- atoms. There are a spread of La–O bond distances ranging from 2.38–2.49 Å. In the fourth La3+ site, La3+ is bonded in a distorted hexagonal planar geometry to six O2- atoms. There are a spread of La–O bond distances ranging from 2.38–2.49 Å. There are four inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both C–O bond lengths are 1.27 Å. In the second C4+ site, C4+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.26 Å) and one longer (1.27 Å) C–O bond length. In the third C4+ site, C4+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both C–O bond lengths are 1.26 Å. In the fourth C4+ site, C4+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both C–O bond lengths are 1.26 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom. In the second O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom. In the third O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom. In the fourth O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom. In the fifth O2- site, O2- is bonded to four La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In the sixth O2- site, O2- is bonded to four La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In the seventh O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom. In the eighth O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom. In the ninth O2- site, O2- is bonded to four La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In the tenth O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom. In the eleventh O2- site, O2- is bonded to four La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In the twelfth O2- site, O2- is bonded in a distorted L-shaped geometry to one La3+ and one C4+ atom.
36 MATERIALS SCIENCE↗
Aerothermodynamics of transatmospheric vehicles
A transatmospheric vehicle (TAV) using airbreathing propulsion requires a long acceleration period within the denser part of the atmosphere to reach orbital speed. The long flight time, coupled with the need for a low-drag configuration, results in severe heating of parts of the vehicle. The ascent peak stagnation point and wing leading edge equilibrium wall temperatures are about 3500 K and 2500 K, respectively, likely requiring some form of mass addition cooling. The corresponding temperatures during entry are 1000 K lower. The vehicle windward centerline temperatures are more moderate, with values peaking around 1300 K during both ascent and entry. Therefore, radiative cooling should be effective over large areas of the vehicle. The windward centerline heat loads during entry are comparable to those for low acceleration ascent trajectories. However, ascent heat loads for the stagnation point and the wing leading edge are about three times higher than those during entry. For comparison, the entry heat load for the TAV's stagnation point is about three times higher than the value for Shuttle. Therefore the ascent heat load at the TAV's stagnation point exceeds the Shuttle's entry value by an order of magnitude.
Tauber, M. E.↗