Calibration of averaging total pressure flight wake rake and natural-laminar-flow airfoil drag certification

An averaging total pressure wake rake used by the Cessna Aircraft Company in flight tests of a modified 210 airplane with a laminar flow wing was calibrated in wind tunnel tests against a five-tube pressure probe. The model generating the wake was a full-scale model of the Cessna airplane wing. Indications of drag trends were the same for both instruments

A review of the planform effects on the low-speed aerodynamic characteristics of triangular and modified triangular wings

Planform effects on low speed aerodynamic characteristics of triangular and modified triangular wing

Feasibility study of aileron and spoiler control systems for large horizontal axis wind turbines

The feasibility of using aileron or spoiler controls as alternates to pitch control for large horizontal axis wind turbines was studied. The NASA Mod-0 100 kw machine was used as the basis for the study. Specific performance studies were conducted for 20% chord ailerons over the outboard 30% span, and for 10% chord spoilers over the same portion of the span. Both control systems utilized control deflections up to 60 deg. Results of the study show that either ailerons or spoilers can provide the control necessary to limit turbine power in high wind conditions. The aileron system, as designed, provides overspeed protection at hurricane wind speeds, low wind speed starting torque of 778 N-m (574 ft. lb) at 3.6 m/sec, and a 1.3 to 1.5% increase in annual energy compared to a fixed pitch rotor. The aileron control system preliminary design study includes aileron loads analysis and the design of a failsafe flyweight actuator for overspeed protection in the event of a hydraulic system failure

The Need for Speed: Eye-Position Signal Dynamics in the Parietal Cortex

Accurate eye-position signals are critically important for localizing targets in space when the eyes move. In this issue of Neuron, Xu et al. (2012) provide evidence that eye-position gain fields in area LIP remain spatially inaccurate for some time after a saccade, indicating they are not updated rapidly enough to play a role in the computation of target locations for upcoming saccades

Photoheliograph study for the Apollo telescope mount

Photoheliograph study for Apollo telescope moun

Nanoscale alpha-structural domains in the phonon-glass thermoelectric material beta-Zn4Sb3

A study of the local atomic structure of the promising thermoelectric material beta-Zn4Sb3, using atomic pair distribution function (PDF) analysis of x-ray- and neutron-diffraction data, suggests that the material is nanostructured. The local structure of the beta phase closely resembles that of the low-temperature alpha phase. The alpha structure contains ordered zinc interstitial atoms which are not long range ordered in the beta phase. A rough estimate of the domain size from a visual inspection of the PDF is <~10 nm. It is probable that the nanoscale domains found in this study play an important role in the exceptionally low thermal conductivity of beta-Zn4Sb3

Wave localization in binary isotopically disordered one-dimensional harmonic chains with impurities having arbitrary cross section and concentration

The localization length for isotopically disordered harmonic one-dimensional chains is calculated for arbitrary impurity concentration and scattering cross section. The localization length depends on the scattering cross section of a single scatterer, which is calculated for a discrete chain having a wavelength dependent pulse propagation speed. For binary isotopically disordered systems composed of many scatterers, the localization length decreases with increasing impurity concentration, reaching a mimimum before diverging toward infinity as the impurity concentration approaches a value of one. The concentration dependence of the localization length over the entire impurity concentration range is approximated accurately by the sum of the behavior at each limiting concentration. Simultaneous measurements of Lyapunov exponent statistics indicate practical limits for the minimum system length and the number of scatterers to achieve representative ensemble averages. Results are discussed in the context of future investigations of the time-dependent behavior of disordered anharmonic chains.Comment: 8 pages, 10 figures, submitted to PR

Fairness, Self-Interest, and the Politics of the Progressive Income Tax

All advanced democracies have adopted income taxes with considerable progression in marginal tax rates. To explain this we examine the nature of individual and collective preferences over alternative tax schedules, in the context of a simple two-sector model. We first consider the case of altruistic or "sociotropic" citizens who view the income tax as a means of achieving a fairer or more egalitarian distribution of income. We show that greater marginal-rate progressivity may well be less fair; that a "fairest" tax, however defined, is always a linear or "flat-rate" schedule in which all incomes are taxed at the same marginal rate; and that with a purely sociotropic electorate there exists a flat-rate schedule which is a majority equilibrium. We then show that with "self-interested" voters who seek to minimize their own tax burdens, greater marginal-rate progression may well be preferred by middle-and upper-income voters; that for middle-income citizens the optimal schedule is a sharply progressive one; and that within the set of individually optimal schedules there exists a majority equilibrium, which is a progressive schedule which minimizes the burden on median-income or middle class citizens, at the expense of lower-and upper-income taxpayers

Line element in quantum gravity: the examples of DSR and noncommutative geometry

We question the notion of line element in some quantum spaces that are expected to play a role in quantum gravity, namely non-commutative deformations of Minkowski spaces. We recall how the implementation of the Leibniz rule forbids to see some of the infinitesimal deformed Poincare transformations as good candidates for Noether symmetries. Then we recall the more fundamental view on the line element proposed in noncommutative geometry, and re-interprete at this light some previous results on Connes' distance formula.Comment: some references added. Proceedings of the Second Workshop on Quantum Gravity and Noncommutative Geometry, Universidade Lusofona, Lisbon 22-24 September 200