6,737 research outputs found
Jettisoning system for a parachute's canister
Three-point automatically released suspension and jettisoning system operates independently of lander's power system and releases parachute on touchdown. The system is based on a ball-lock device operated by the shock of the parachute's opening and by the subsequent decay in the load on the main cord
A study of the sonic-boom characteristics of a blunt body at a Mach number of 4.14
An experimental and theoretical study has shown that the applicability of far-field sonic-boom theory previously demonstrated for more slender shapes may now be extended to bodies with ratios of diameter to length as great as 2 and to Mach numbers at least as high as 4.14. This finding is of special significance in view of the limitations to the use of existing methods for the extrapolation of close-in experimental data
Estimation of wing nonlinear aerodynamic characteristics at supersonic speeds
A computational system for estimation of nonlinear aerodynamic characteristics of wings at supersonic speeds was developed and was incorporated in a computer program. This corrected linearized theory method accounts for nonlinearities in the variation of basic pressure loadings with local surface slopes, predicts the degree of attainment of theoretical leading edge thrust, and provides an estimate of detached leading edge vortex loadings that result when the theoretical thrust forces are not fully realized
Large-Scale Radio Structure in the Universe: Giant Radio Galaxies
Giant radio galaxies (GRGs), with linear sizes larger than 1 Mpc (H0=50
km/s/Mpc), represent the biggest single objects in the Universe. GRGs are rare
among the entire population of radio galaxies (RGs) and their physical
evolution is not well understood though for many years they have been of
special interest for several reasons. The lobes of radio sources can compress
cold gas clumps and trigger star or even dwarf galaxy formation, they can also
transport gas from a host galaxy to large distances and seed the IGM with
magnetic fields. Since GRGs have about 10 to 100 times larger sizes than normal
RGs, their influence on the ambient medium is correspondingly wider and is
pronounced on scales comparable to those of clusters of galaxies or larger.
Therefore `giants' could play an important role in the process of large-scale
structure formation in the Universe. Recently, thanks to the new all sky radio
surveys, significant progress in searching for new GRGs has been made.Comment: To appear in Multiwavelength AGN Surveys, ed. R. Maiolino and R.
Mujica, Singapore: World Scientific, 2004, 2 page
Supersonic wings with significant leading-edge thrust at cruise
Experimental/theoretical correlations are presented which show that significant levels of leading edge thrust are possible at supersonic speeds for certain planforms which match the theoretical thrust distribution potential with the supporting airfoil geometry. The analytical process employed spanwise distribution of both it and/or that component of full theoretical thrust which acts as vortex lift. Significantly improved aerodynamic performance in the moderate supersonic speed regime is indicated
Estimation of attainable leading-edge thrust for wings at subsonic and supersonic speeds
The factors which place limits on the theoretical leading edge thrust are identified. An empirical method for the estimation of attainable thrust is presented. The method is based on the use of simple sweep theory to permit a two dimensional analysis, the use of theoretical airfoil programs to define thrust dependence on local geometric characteristics, and the examination of experimental two dimensional airfoil data to define limitations imposed by local Mach numbers and Reynolds numbers. Comparisons of theoretical and experimental aerodynamic characteristics for a series of wing body configurations are examined
Determinants of Real House Price Dynamics
We explore the dynamics of real house prices by estimating serial correlation and mean reversion coefficients from a panel data set of 62 metro areas from 1979-1995. The serial correlation and reversion parameters are then shown to vary cross sectionally with city size, real income growth, population growth, and real construction costs. Serial correlation is higher in metro areas with higher real income, population growth and real construction costs. Mean reversion is greater in large metro areas and faster-growing cities with lower construction costs. Empirically, substantial overshooting of prices can occur in high real construction cost areas, which have high serial correlation and low mean reversion, such as the coastal cities of Boston, New York, San Francisco, Los Angeles and San Diego.
Optimal probabilistic cloning and purification of quantum states
We investigate the probabilistic cloning and purification of quantum states.
The performance of these probabilistic operations is quantified by the average
fidelity between the ideal and actual output states. We provide a simple
formula for the maximal achievable average fidelity and we explictly show how
to construct a probabilistic operation that achieves this fidelity. We
illustrate our method on several examples such as the phase covariant cloning
of qubits, cloning of coherent states, and purification of qubits transmitted
via depolarizing channel and amplitude damping channel. Our examples reveal
that the probabilistic cloner may yield higher fidelity than the best
deterministic cloner even when the states that should be cloned are linearly
dependent and are drawn from a continuous set.Comment: 9 pages, 2 figure
- …