40,700 research outputs found
Observations of Mariner IV with the Parkes 210-ft Radio Telescope
Radio telescope test results from Mariner IV OBSERVATION
HCMM and LANDSAT imagery for geological mapping in northwest Queensland
The author has identified the following significant results. Photographic prints made from negatives of day-visible and day-IR cover of selected areas were compared with enhanced color composites generated from LANDSAT computer compatible tapes and films. For geological mapping purposes, HCMM imagery is of limited value. While large scale features like the Mikadoodi anticlinorium, contrasting lithological units, and major structures may be distinguished on day-visible and day-IR cover, the spectral bands are too broad and the resolution too coarse even for regional mapping purposes. The imagery appears to be most useful for drainage studies. Where drainage is seasonal, sequential imagery permits monitoring of broad scale water movement while the day-IR imagery yields valuable information on former channels. In plains areas subject to periodic change of stream courses, comparable IR cover at a larger scale would offer considerable potential for reconstruction of former drainage patterns essential for the correct interpretation of geochemical data relative to mineral exploration
Assessing the Early Impact of School of One: Evidence from Three School-Wide Pilots
For more than 150 years, education has been organized around classrooms in which one teacher attempts to meet the needs of a large group of students who have a wide range of prior experiences, knowledge, and ways of learning. This structure makes it exceedingly difficult to ensure that all students meet the same standards of performance. School of One (SO1) is an innovative, technology-enhanced math program that seeks to "meet students where they are," by creating individual learning plans, offering multiple teaching strategies, and using daily assessments to monitor progress and adapt lessons as needed. This report evaluates SO1's impact on students' state test scores during the first year of school-wide implementation in three New York City middle schools. It also presents exploratory analysis examining whether exposure to more SO1 material, or mastery of SO1 skills, is associated with improved math performance. Given the early stage of the program's development, the authors caution that the evaluation should not be interpreted as a definitive assessment of SO1's effectiveness. Rather, the findings provide a preliminary assessment of SO1's initial impact on students' math achievement and offer insights that may contribute to the program's development and inform future research
The evolution of electron density and temperature distributions in the topside ionosphere during magnetic storms
The latitudinal distributions of electron density and temperature during geomagnetic storms in the mid-latitude topside ionosphere are observed to change in a manner than can be related to the evolution of ring current particle populations. The region of auroral precipitation is characterized by correlated increases in electron temperature and density. Equatorwards of this region, there is a broad belt of elevated electron temperatures and depressed electron densities which is usually much broader than any stable auroral red arc distinguishable from the ground, but which is nevertheless the same basic physical phenomenon. The changes of position of this belt can be related to prior bursts of geomagnetic activity and injection of ring current particles into the magnetosphere
A consistent design procedure for supercritical airfoils in free air and a wind tunnel
A computational inverse procedure for transonic airfoils in which shapes are determined supporting prescribed pressure distributions is presented. The method uses the small disturbance equation and a consistent analysis-design differencing procedure at the airfoil surface. This avoids the intermediate analysis-design-analysis iterations. The effect of any openness at the trailing edge is taken onto account by adding an effective source term in the far field. The final results from a systematic expansion procedure which models the far field for solid, ideal slotted, and free jet tunnel walls are presented along with some design results for the associated boundary conditions and those for a free flight
Investigation of the effects of a moving acoustic medium on jet noise measurements
Noise from an unheated sonic jet in the presence of an external flow is measured in a free-jet wind tunnel using microphones located both inside and outside the flow. Comparison of the data is made with results of similar studies. The results are also compared with theoretical predictions of the source strength for jet noise in the presence of flow and of the effects of sound propagation through a shear layer
The Flow of a Viscous Compressible Fluid Through a Very Narrow Gap
The effect of compressibility on the pressure distribution
in the narrow gap between a rotating cylinder and a plane in a viscous fluid was studied by Taylor and Saffman [1] during an investigation of the centripetal pump effect discovered by Reiner [2]
Ligand Discrimination in Myoglobin from Linear-Scaling DFT+U
Myoglobin modulates the binding of diatomic molecules to its heme group via
hydrogen-bonding and steric interactions with neighboring residues, and is an
important benchmark for computational studies of biomolecules. We have
performed calculations on the heme binding site and a significant proportion of
the protein environment (more than 1000 atoms) using linear-scaling density
functional theory and the DFT+U method to correct for self-interaction errors
associated with localized 3d states. We confirm both the hydrogen-bonding
nature of the discrimination effect (3.6 kcal/mol) and assumptions that the
relative strain energy stored in the protein is low (less than 1 kcal/mol). Our
calculations significantly widen the scope for tackling problems in drug design
and enzymology, especially in cases where electron localization, allostery or
long-ranged polarization influence ligand binding and reaction.Comment: 15 pages, 3 figures. Supplementary material 8 pages, 3 figures. This
version matches that accepted for J. Phys. Chem. Lett. on 10th May 201
Acceleration of Slender Bodies of Revolution through Sonic Velocity
The linearized theory of slender bodies in arbitrary motion at zero angle of attack has been worked out. The results have been applied to a smooth body accelerating uniformly through sonic velocity. The results theory can be used to estimate the nonlinear or transonic effects.
For an accelerating body, the parameter (bl/c^2)^½ is important where 2b = acceleration, 2l = length of body, c = sound speed at infinity. For sufficiently high (bl/c^2)^½, transonic effects can be neglected. Using linearized theory to estimate the ratio of nonlinear terms in the differential equation gives
λ= (nonlinear terms/significant linear terms) = 3/4 (γ+1) δ^2/(bl/c^2)^(1/2) {log2/δ^2 (c^2/bl)^(1/2) − 9/4}
, where δ = thickness ratio of body. The result above is evaluated at the maximum thickness of a symmetric parabolic arc body at the instant it passes through sonic velocity. For λ1 they begin to dominate. For practical applications the result shows that there is a possibility of a sufficiently long and slender missile accelerating fast enough to avoid transonic effects (e.g., 50 feet long, 5 percent thick, 3g acceleration). For conventional aircraft, transonic effects will dominate. An interesting side result is that when the acceleration is sufficiently large so that transonic effects do not matter the drag coefficient near sonic speed is independent of the acceleration (C_D≐3δ^2 for parabolic arc body)
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