36,949 research outputs found
The supercritical profile of the supercritical wing
The profile wing design for supercritical structures is discussed. Emphasis is placed on the flow of air surrounding the wing and variations in flow fields are examined. Modifications to the profile for flight below transonic level are presented that increase the uplift pressure and permit the achievement of critical Mach numbers on the order of 0.85. The uplift pressure along the upper side of the profile is compared for a classical and a Peaky profile. A comparison of classical and supercritical wing cross sections indicates a flatter upper side, a large nose radius, and a thicker profile to the supercritical wing
Secondary iron-air batteries
Self discharge, capacity maintenance, oxidation, and water loss problems in secondary iron-air batterie
Deregulation Using Stealth “Science” Strategies
In this Article, we explore the “stealth” use of science by the Executive Branch to advance deregulation and highlight the limited, existing legal and institutional constraints in place to discipline and discourage these practices. Political appointees have employed dozens of strategies over the years, in both Democratic and Republican administrations, to manipulate science in ends-oriented ways that advance the goal of deregulation. Despite this bald manipulation of science, however, the officials frequently present these strategies as necessary to bring “sound science” to bear on regulatory decisions. To begin to address this problem, it is important to reconceptualize how the administrative state addresses science-intensive decisions. Rather than allow agencies and the White House to operate as a cohesive unit, institutional bounds should be drawn around the scientific expertise lodged within the agencies. We propose that the background scientific work prepared by agency staff should be firewalled from the evaluative, policymaking input of the remaining officials, including politically appointed officials, in the agency
Around Podewski's conjecture
A long-standing conjecture of Podewski states that every minimal field is
algebraically closed. It was proved by Wagner for fields of positive
characteristic, but it remains wide open in the zero-characteristic case.
We reduce Podewski's conjecture to the case of fields having a definable (in
the pure field structure), well partial order with an infinite chain, and we
conjecture that such fields do not exist. Then we support this conjecture by
showing that there is no minimal field interpreting a linear order in a
specific way; in our terminology, there is no almost linear, minimal field.
On the other hand, we give an example of an almost linear, minimal group
of exponent 2, and we show that each almost linear, minimal group
is elementary abelian of prime exponent. On the other hand, we give an example
of an almost linear, minimal group of exponent 2, and we show that
each almost linear, minimal group is torsion.Comment: 16 page
Gravitational spectra from direct measurements
A simple rapid method is described for determining the spectrum of a surface field from harmonic analysis of direct measurements along great circle arcs. The method is shown to give excellent overall trends to very high degree from even a few short arcs of satellite data. Three examples are taken with perfect measurements of satellite tracking over a planet made up of hundreds of point-masses using (1) altimetric heights from a low orbiting spacecraft, (2) velocity residuals between a low and a high satellite in circular orbits, and (3) range-rate data between a station at infinity and a satellite in highly eccentric orbit. In particular, the smoothed spectrum of the Earth's gravitational field is determined to about degree 400(50 km half wavelength) from 1 D x 1 D gravimetry and the equivalent of 11 revolutions of Geos 3 and Skylab altimetry. This measurement shows there is about 46 cm of geoid height remaining in the field beyond degree 180
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