12,276 research outputs found
PUBLIC AFFAIRS EDUCATION FOR COMMUNITY DEVELOPMENT IN ALABAMA
Community/Rural/Urban Development,
Aerodynamics, Stability and Control of the 1903 Wright Flyer
The Los Angeles Chapter of the American Institute of Aero and
Astronautics is building two replicas of the 1903 Wright Flyer airplane;
one to wind-tunnel test and display, and a modified one to fly. As part
of this project the aerodynamic characteristics of the Flyer are being
analyzed by modern wind-tunnel and analytical techniques. Tnis paper
describes the Wright Flyer Project, and compares key results from
small-scale wind-tunnel tests and from vortex-lattice computations for
this multi-biplane canard configuration. Analyses of the stability and
control properties are summarized and their implications for closed-loop
control by a pilot are derived using quasilinear pilot-vehicle analysis
and illustrated by simulation time histories.
It is concluded that, although the Wrights were very knowledgeable
and ingenious with respect to aircraft controls and their interactions
(e.g., the good effects of their wing-warp-to-rudder linkage are
validated), they were largely ignorant of dynamic stability
considerations. The paper shows that the 1903 Flyer was readily
controllable about all axes but was intrinsically unstable in pitch and
roll, and it could barely be stabilized by a skilled pilot
Where do Innovations Come From? Transformations in the U.S. Economy, 1970-2006
This article brings to bear new data on the issue of structuring national innovation systems. Drawing on a unique data set of prize winning innovations between 1971 and 2006, we document three key changes in the U.S. economy. The first is an expanding role of interorganizational collaborations in producing award winning innovations. The second is the diminishing role of the largest corporations as sources of innovation. The third is the expanded role of public institutions and public funding in the innovation process. This leads us to the surprising conclusion that the U.S. increasingly resembles a Developmental Network State in which government initiatives are critical in overcoming network failures and in providing critical funding for the innovation process. The paper concludes by addressing the implications of these finding for debates over the appropriate regime for intellectual property rights.
An approximate viscous shock layer technique for calculating chemically reacting hypersonic flows about blunt-nosed bodies
An approximate axisymmetric method was developed which can reliably calculate fully viscous hypersonic flows over blunt nosed bodies. By substituting Maslen's second order pressure expression for the normal momentum equation, a simplified form of the viscous shock layer (VSL) equations is obtained. This approach can solve both the subsonic and supersonic regions of the shock layer without a starting solution for the shock shape. The approach is applicable to perfect gas, equilibrium, and nonequilibrium flowfields. Since the method is fully viscous, the problems associated with a boundary layer solution with an inviscid layer solution are avoided. This procedure is significantly faster than the parabolized Navier-Stokes (PNS) or VSL solvers and would be useful in a preliminary design environment. Problems associated with a previously developed approximate VSL technique are addressed before extending the method to nonequilibrium calculations. Perfect gas (laminar and turbulent), equilibrium, and nonequilibrium solutions were generated for airflows over several analytic body shapes. Surface heat transfer, skin friction, and pressure predictions are comparable to VSL results. In addition, computed heating rates are in good agreement with experimental data. The present technique generates its own shock shape as part of its solution, and therefore could be used to provide more accurate initial shock shapes for higher order procedures which require starting solutions
ANALYZING THE 1983 PAYMENT IN KIND PROGRAM AT THE FARM LEVEL
Agricultural and Food Policy, Agricultural Finance,
Reactive Attachment Disorder of Infancy or Early Childhood
Since its introduction into DSM-Ill, reactive attachment disorder has stood curiously apart from other diagnoses for two reasons: it remains the only diagnosis designed for infants, and it requires the presence of a specific etiology. This paper describes the pattern of disturbances demonstrated by some children who meet DSM-Ill-R criteria for reactive attachment disorder. Three suggestions are made: (1) the sensitivity and specificity of the diagnostic concept may be enhanced by including criteria detailing the developmental problems exhibited by these children; (2) the etiological requirement should be discarded given the difficulties inherent in obtaining complete histories for these children, as well as its inconsistency with ICD-10; and (3) the diagnosis arguably is not a disorder of attachment but rather a syndrome of atypical development. J.Am. Acad. Child Adolesc. Psychiatry,1994, 33, 3: 328-332. Key Words: reactive attachment disorder, maltreatment, DSM-Ill-
THE BAYESIAN DECISION MODEL WITH MORE THAN ONE PREDICTOR--AN APPLICATION TO THE STOCKING RATE PROBLEM
Research Methods/ Statistical Methods,
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