76,557 research outputs found
Integrable Fredholm Operators and Dual Isomonodromic Deformations
The Fredholm determinants of a special class of integral operators K
supported on the union of m curve segments in the complex plane are shown to be
the tau-functions of an isomonodromic family of meromorphic covariant
derivative operators D_l. These have regular singular points at the 2m
endpoints of the curve segments and a singular point of Poincare index 1 at
infinity. The rank r of the vector bundle over the Riemann sphere on which they
act equals the number of distinct terms in the exponential sums entering in the
numerator of the integral kernels. The deformation equations may be viewed as
nonautonomous Hamiltonian systems on an auxiliary symplectic vector space M,
whose Poisson quotient, under a parametric family of Hamiltonian group actions,
is identified with a Poisson submanifold of the loop algebra Lgl_R(r) with
respect to the rational R-matrix structure. The matrix Riemann-Hilbert problem
method is used to identify the auxiliary space M with the data defining the
integral kernel of the resolvent operator at the endpoints of the curve
segments. A second associated isomonodromic family of covariant derivative
operators D_z is derived, having rank n=2m, and r finite regular singular
points at the values of the exponents defining the kernel of K. This family is
similarly embedded into the algebra Lgl_R(n) through a dual parametric family
of Poisson quotients of M. The operators D_z are shown to be analogously
associated to the integral operator obtained from K through a Fourier-Laplace
transform.Comment: PlainTeX 32g
Swashplate feedback control for tilt-rotor aircraft
Changes in angle of attack in system were sensed indirectly by gages which responded to strains induced in wing structure. Output signals were amplified, filtered, and used to activate swashplate actuators. System provided significant reduction in blade loads and desirable changes in hub forces and moments
Urban and regional land use analysis: CARETS and Census Cities experiment package
There are no author-identified significant results in this report
Urban and regional land use analysis: CARETS and Census Cities experiment package
There are no author-identified significant results is this report
Development of a real-time aeroperformance analysis technique for the X-29A advanced technology demonstrator
The X-29A advanced technology demonstrator has shown the practicality and advantages of the capability to compute and display, in real time, aeroperformance flight results. This capability includes the calculation of the in-flight measured drag polar, lift curve, and aircraft specific excess power. From these elements many other types of aeroperformance measurements can be computed and analyzed. The technique can be used to give an immediate postmaneuver assessment of data quality and maneuver technique, thus increasing the productivity of a flight program. A key element of this new method was the concurrent development of a real-time in-flight net thrust algorithm, based on the simplified gross thrust method. This net thrust algorithm allows for the direct calculation of total aircraft drag
Statistical inference for the mean outcome under a possibly non-unique optimal treatment strategy
We consider challenges that arise in the estimation of the mean outcome under
an optimal individualized treatment strategy defined as the treatment rule that
maximizes the population mean outcome, where the candidate treatment rules are
restricted to depend on baseline covariates. We prove a necessary and
sufficient condition for the pathwise differentiability of the optimal value, a
key condition needed to develop a regular and asymptotically linear (RAL)
estimator of the optimal value. The stated condition is slightly more general
than the previous condition implied in the literature. We then describe an
approach to obtain root- rate confidence intervals for the optimal value
even when the parameter is not pathwise differentiable. We provide conditions
under which our estimator is RAL and asymptotically efficient when the mean
outcome is pathwise differentiable. We also outline an extension of our
approach to a multiple time point problem. All of our results are supported by
simulations.Comment: Published at http://dx.doi.org/10.1214/15-AOS1384 in the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org
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