Modeling and control design of a wind tunnel model support

The 12-Foot Pressure Wind Tunnel at Ames Research Center is being restored. A major part of the restoration is the complete redesign of the aircraft model supports and their associated control systems. An accurate trajectory control servo system capable of positioning a model (with no measurable overshoot) is needed. Extremely small errors in scaled-model pitch angle can increase airline fuel costs for the final aircraft configuration by millions of dollars. In order to make a mechanism sufficiently accurate in pitch, a detailed structural and control-system model must be created and then simulated on a digital computer. The model must contain linear representations of the mechanical system, including masses, springs, and damping in order to determine system modes. Electrical components, both analog and digital, linear and nonlinear must also be simulated. The model of the entire closed-loop system must then be tuned to control the modes of the flexible model-support structure. The development of a system model, the control modal analysis, and the control-system design are discussed

M5 on a torus and the three brane

We examine the D-3 brane from the point of view of the double dimensionally reduced M theory 5 brane on a torus. M-theory, IIB identifications are explicitly constructed and a possible reformulation of the D-3 brane is discussed. The duality transformation of the reduced 3-brane necessary to make the identification is discussed in detail.Comment: 20 pages, tex, no figure

Influence of an aperture on the performance of a two-degree-of-freedom iron-cored spherical permanent-magnet actuator

Abstract—This paper describes a computational and experimental study of a two-degree-of-freedom spherical permanent-magnet actuator equipped with an iron stator. In particular, it considers the effect of introducing an aperture in the stator core to facilitate access to the armature. The resultant magnetic field distribution in the region occupied by the stator windings, the net unbalanced radial force, and the resulting reluctance torque are determined by three-dimensional magnetostatic finite-element analysis. The predicted reluctance torque is validated experimentally, and its implications on actuator performance are described

Energy Efficient Engine Program Advanced Turbofan Nacelle Definition Study

Advanced, low drag, nacelle configurations were defined for some of the more promising propulsion systems identified in the earlier Benefit/Cost Study, to assess the benefits associated with these advanced technology nacelles and formulate programs for developing these nacelles and low volume thrust reversers/spoilers to a state of technology readiness in the early 1990's. The study results established the design feasibility of advanced technology, slim line nacelles applicable to advanced technology, high bypass ratio turbofan engines. Design feasibility was also established for two low volume thrust reverse/spoiler concepts that meet or exceed the required effectiveness for these engines. These nacelle and thrust reverse/spoiler designs were shown to be applicable in engines with takeoff thrust sizes ranging from 24,000 to 60,000 pounds. The reduced weight, drag, and cost of the advanced technology nacelle installations relative to current technology nacelles offer a mission fuel burn savings ranging from 3.0 to 4.5 percent and direct operating cost plus interest improvements from 1.6 to 2.2 percent

Classical Duality from dimensional reduction of Self Dual 4-form Maxwell Theory in 10 dimensions

By dimensional reduction of a self dual p-form theory on some compact space, we determine the duality generators of the gauge theory in 4 dimensions. In this picture duality is seen as a consequence of the geometry of the compact space. We describe the dimensional reduction of 10-dimensional self dual 4-form Maxwell theory to give a theory in 4-dimensions with scalar, one form and two form fields that all transform non trivially under duality.Comment: 8 pages, tex, no figures, typos corrected, To coincide with published version, references adde

Integration of Paralympic Athletes into Athletics Canada

This paper explores the integration of Paralympic athletes into Athletics Canada. Highlighting the charitable foundation of sport for the disabled as well as the issue of classification, this paper offers insight into the habitus of Paralympic athletics as a key factor influencing this integration process. Integration is conceptualized on a continuum of compliance where true integration is the goal and segregation is frowned upon. Using ethnographic data collected in participant observation roles as an athlete, administrator, and journalist, the paper illuminates the success of the Paralympics in capturing the imagination of the Canadian public. At the same time, the process of integration within Athletics Canada has been less than successful because the achievement of athletes with disabilities is not as valued, by those who administer the sport, as those of their "able" counterparts. To this end the integration process within Athletic Canada appears to be stuck at the uncomfortable point of accommodation, which means that a truly integrated sport system is still a goal to be achieved.Ce document examine l’intégration des athlètes paralympiques à Athlétisme Canada. Ce document, qui fait ressortir l’oeuvre de charité que constitue le sport pour les personnes handicapées ainsi que la question du classement, présente un aperçu de l’habitus de l’athlétisme paralympique comme facteur clé de ce processus d’intégration. L’intégration est conçue comme un continuum de conformité où la véritable intégration est l’objectif et la ségrégation est mal acceptée. Au moyen de données ethnographiques qu’il a recueillies à titre d’observateur comme athlète, administrateur et journaliste, l’auteur de l’étude démontre le succès qu’ont remporté les paralympiques en faisant appel à l’imagination du public canadien. Par ailleurs, le processus d’intégration à Athlétisme Canada n’a pas été un aussi grand succès parce que les réalisations des athlètes handicapés ne sont pas valorisées par les administrateurs du sport, comme celles de leurs homologues non handicapés. À cette fin, le processus d’intégration au sein d’Athlétisme Canada semble se limiter à une certaine tolérance; par conséquent, l’objectif d’un système sportif vraiment intégré n’est pas encore atteint

Ecosystem uptake and transfer of Sellafield-derived radiocarbon (14C). Part 1. The Irish Sea

Ecosystem uptake and transfer processes of Sellafield-derived radiocarbon (14C) within the Irish Sea were examined. Highly variable activities in sediment, seawater and biota indicate complex 14C dispersal and uptake dynamics. All east basin biota exhibited 14C enrichments above ambient background while most west basin biota had 14C activities close to background, although four organisms including two slow-moving species were significantly enriched. The western Irish Sea gyre is a suggested pathway for transfer of 14C to the west basin and retention therein. Despite ongoing Sellafield 14C discharges, organic sediments near Sellafield were significantly less enriched than associated benthic organisms. Rapid scavenging of labile, 14C-enriched organic material by organisms and mixing to depth of 14C-enriched detritus arriving at the sediment/water interface are proposed mechanisms to explain this. All commercially important fish, crustaceans and molluscs showed 14C enrichments above background; however, the radiation dose from their consumption is extremely low and radiologically insignificant

Quantum scale invariance on the lattice

We propose a scheme leading to a non-perturbative definition of lattice field theories which are scale-invariant on the quantum level. A key idea of the construction is the replacement of the lattice spacing by a propagating dynamical field -- the dilaton. We describe how to select non-perturbatively the phenomenologically viable theories where the scale invariance is broken spontaneously. Relation to gravity is also discussed.Comment: 5 page