28,591 research outputs found
Methods for predicting thermal stress cracking in turbine stator or rotor blades Summary report
Test rig for predicting thermal stress cracking in turbine stator or rotor blade
A first order iteration process for simultaneous equations
First order iteration process for solutions of simultaneous equation
A Precise Determination of from the C-parameter Distribution
We present a global fit for , analyzing the available
C-parameter data measured at center-of-mass energies between and
GeV. The experimental data is compared to a NLL +
+ theoretical prediction (up to the
missing 4-loop cusp anomalous dimension), which includes power corrections
coming from a field theoretical nonperturbative soft function. The dominant
hadronic parameter is its first moment , which is defined in a scheme
which eliminates the renormalon ambiguity. The
resummation region plays a dominant role in the C-parameter spectrum, and in
this region a fit for and is sufficient. We find
and with
for bins of data. These results agree with the
prediction of universality for between thrust and C-parameter within
1-.Comment: 24 pages, 19 figure
A review of NASA's propulsion programs for aviation
A review of five NASA engine-oriented propulsion programs of major importance to civil aviation are presented and discussed. Included are programs directed at exploring propulsion system concepts for (1) energy conservation subsonic aircraft (improved current turbofans, advanced turbofans, and advanced turboprops); (2) supersonic cruise aircraft (variable cycle engines); (3) general aviation aircraft (improved reciprocating engines and small gas turbines); (4) powered lift aircraft (advanced turbofans); and (5) advanced rotorcraft
Gust alleviation system to improve ride comfort of light airplanes
System consists of movable auxiliary aerodynamic sensors mounted on fuselage and connected to trailing-edge flaps by rigid mechanical linkages. System achieves alleviation by reducing lift-curve slope of airplane to such a small value that gust-induced angles of attack will result in small changes in lift
Continuous Transition of Defect Configuration in a Deformed Liquid Crystal Film
We investigate energetically favorable configurations of point disclinations
in nematic films having a bump geometry. Gradual expansion in the bump width
{\Delta} gives rise to a sudden shift in the stable position of the
disclinations from the top to the skirt of the bump. The positional shift
observed across a threshold {\Delta}th obeys a power law function of
|{\Delta}-{\Delta}th|, indicating a new class of continuous phase transition
that governs the defect configuration in curved nematic films.Comment: 8pages, 3figure
Automatic holographic droplet analysis for liquid fuel sprays
The basic scheme for automated holographic analysis involves an optical system for reconstruction of the three dimensional real image of the droplet field, a spatial scanning system to transport a digitizing X-y image sensor through the real image, and processing algorithms for droplet recognition which establish the droplet sizes and positions. The hardware for system demonstrated includes the expanded and collimated beam from a 5 mW helium-neon laser for hologram reconstruction, an imaging lens for magnification of the real image field, and a video camera and digitizer providing 512-by-512 pixel resolution with 8-bit digitization. A mechanical stage is used to scan the hologram in three dimensional space, maintaining constant image magnification. A test droplet hologram is used for development and testing of the image processing algorithms
Global search algorithm for optimal control
Random-search algorithm employs local and global properties to solve two-point boundary value problem in Pontryagin maximum principle for either fixed or variable end-time problems. Mixed boundary value problem is transformed to an initial value problem. Mapping between initial and terminal values utilizes hybrid computer
Hard Matching for Boosted Tops at Two Loops
Cross sections for top quarks provide very interesting physics opportunities,
being both sensitive to new physics and also perturbatively tractable due to
the large top quark mass. Rigorous factorization theorems for top cross
sections can be derived in several kinematic scenarios, including the boosted
regime in the peak region that we consider here. In the context of the
corresponding factorization theorem for collisions we extract the last
missing ingredient that is needed to evaluate the cross section differential in
the jet-mass at two-loop order, namely the matching coefficient at the scale
. Our extraction also yields the final ingredients needed to
carry out logarithmic resummation at next-to-next-to-leading logarithmic order
(or NLL if we ignore the missing 4-loop cusp anomalous dimension). This
coefficient exhibits an amplitude level rapidity logarithm starting at
due to virtual top quark loops, which we treat using
rapidity renormalization group (RG) evolution. Interestingly, this rapidity RG
evolution appears in the matching coefficient between two effective theories
around the heavy quark mass scale .Comment: 35 pages, 3 figures, v2: added extraction of 3-loop anon. dimension,
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