Adaptive wall technology for minimization of wall interferences in transonic wind tunnels

Modern experimental techniques to improve free air simulations in transonic wind tunnels by use of adaptive wall technology are reviewed. Considered are the significant advantages of adaptive wall testing techniques with respect to wall interferences, Reynolds number, tunnel drive power, and flow quality. The application of these testing techniques relies on making the test section boundaries adjustable and using a rapid wall adjustment procedure. A historical overview shows how the disjointed development of these testing techniques, since 1938, is closely linked to available computer support. An overview of Adaptive Wall Test Section (AWTS) designs shows a preference for use of relatively simple designs with solid adaptive walls in 2- and 3-D testing. Operational aspects of AWTS's are discussed with regard to production type operation where adaptive wall adjustments need to be quick. Both 2- and 3-D data are presented to illustrate the quality of AWTS data over the transonic speed range. Adaptive wall technology is available for general use in 2-D testing, even in cryogenic wind tunnels. In 3-D testing, more refinement of the adaptive wall testing techniques is required before more widespread use can be planned

An experimental AWTS process and comparisons of ONERA T2 and 0.3-m TCT AWTS data for the ONERA CAST-10 aerofoil

An experimental Adaptive Wall Test Section (AWTS) process is described. Comparisons of the ONERA T2 and the 0.3-m TCT (transonic cryogenic tunnel) AWTS data for the ONERA CAST-10 airfoil are presented. Most of the 0.3-m TCT data is new and preliminary and no sidewall boundary layer control is involved. No conclusions are given

Supersonic wind tunnel nozzles: A selected, annotated bibliography to aid in the development of quiet wind tunnel technology

This bibliography, with abstracts, consists of 298 citations arranged in chronological order. The citations were selected to be helpful to persons engaged in the design and development of quiet (low disturbance) nozzles for modern supersonic wind tunnels. Author, subject, and corporate source indexes are included to assist with the location of specific information

Exact solutions of semilinear radial Schrodinger equations by separation of group foliation variables

Explicit solutions are obtained for a class of semilinear radial Schrodinger equations with power nonlinearities in multi-dimensions. These solutions include new similarity solutions and other new group-invariant solutions, as well as new solutions that are not invariant under any symmetries of this class of equations. Many of the solutions have interesting analytical behavior connected with blow-up and dispersion. Several interesting nonlinearity powers arise in these solutions, including the case of the critical (pseudo-conformal) power. In contrast, standard symmetry reduction methods lead to nonlinear ODEs for which few if any explicit solutions can be derived by standard integration methods.Comment: typos have been corrected; 30 pages, 3 tables; published versio

ECONOMICS OF HEIFER RAISING OPTIONS

As dairy farms grow and specialize in milking cows, one enterprise that may be removed from the dairy farm to allow for milk cow herd expansion is heifer raising. Custom heifer raising is increasingly common across the country and purchasing heifers may be preferred to raising heifers. However, these alternatives are not suitable for all dairy farmers. In this article, we examine heifer enterprise costs relative to using a custom raiser or purchasing heifers. We identify factors that should be considered in making the proper decision relative to the heifer enterprise.Livestock Production/Industries,

Parent and Student Voices on the First Year of the DC Opportunity Scholarship Program

In the 50 years since economist Milton Friedman published “The Role of Government in Education” scholars and policy makers have been debating how parental choice through market mechanisms can and does operate in education. Market “optimists” argue that education is a service that can be produced under a variety of arrangements and that parents are natural education consumers. Market “pessimists” argue that education is a public good that should be produced in government-run schools, and that school choice programs suffer “market failure” because only advantaged families will have the resources and experience to choose effectively

The role of memory and restricted context in repeated visual search

Previous studies have shown that the efficiency of visual search does not improve when participants search through the same unchanging display for hundreds of trials (repeated search), even though the participants have a clear memory of the search display. In this article, we ask two important questions. First, why do participants not use memory to help search the repeated display? Second, can context be introduced so that participants are able to guide their attention to the relevant repeated items? Experiments 1–4 show that participants choose not to use a memory strategy because, under these conditions, repeated memory search is actually less efficient than repeated visual search, even though the latter task is in itself relatively inefficient. However, when the visual search task is given context, so that only a subset of the items are ever pertinent, participants can learn to restrict their attention to the relevant stimuli (Experiments 5 and 6)

Hyperkahler geometry and Teichmuller space

We consider the hyperk???????hler extension of Teichm???????ller space with the Weil- Petersson metric. We describe its recent construction as a hyperk???????hler quotient and examine the defining equations for the resulting moduli space. We examine relations between this moduli space and the quasi-Fuchsian deformation space of the surface, with particular attention to the connection with the canonical holomorphic symplectic structure. We also consider the connection with Taubes moduli space of hyperbolic germs and whether it is possible to extend the hyperk???????hler structure in any fashion.Imperial Users onl