Pratt & Miller (United States)

A spatial control methodology is developed for six-step control based on deadbeat flux control. The methodology includes a spatial z-transform that allows a speed-invariant analysis of command tracking and disturbance rejection properties of six-step operation. Several design options for high-performance six-step controllers are examined, and fundamental trade-offs of six-step controllers such as speed-dependent bandwidths, limitations related to the Nyquist frequency, and critical frequencies for disturbance rejection are investigated. A key result of the analysis is that a fast deadbeat controller can result in lower dynamic stiffness than a low bandwidth or even a quasi-open-loop controller near the fundamental frequency. One way to provide excellent disturbance rejection at these frequencies is to know the disturbances in advance. This can only be achieved for a particular class of disturbances, i.e., repetitive disturbances. Therefore, a spatial repetitive controller is utilized, which can be easily included in the proposed framework.

Simple reduced order models (ROMs) for the aerodynamic coefficients - lift, drag, and pitch moment - of a pitching NACA0012 airfoil are presented. The ROMs are designed for quick computation of the transient aerodynamic characteristics of the airfoil and are developed utilizing computational fluid dynamics (CFD) simulation results. The entire aerodynamic system is modeled as a single input, multi output system yielding three independent systems to be characterized. A systematic, two step process is employed to develop the ROMs for each aerodynamic system. First, a CFD simulation is conducted to determine the linearity of each system, and any nonlinear system is restructured as a nonlinear operator followed by a linear system to allow for the use of linear system identification techniques. A second CFD simulation is conducted to determine the frequency response of each linear system, and the coefficients of each ROM are extracted by fitting a second order model to each frequency response function. The ROMs are validated against an independent CFD simulation of a pitching airfoil and are shown to accurately model each aerodynamic coefficient.

ABSTRACTWe described in this paper the development of a high fidelity vehicle aerodynamic model to fit wind tunnel test data over a wide range of vehicle orientations. We also present a comparison between the effects of this proposed model and a conventional quasi steady-state aerodynamic model on race vehicle simulation results. This is done by implementing both of these models independently in multi-body quasi steady-state simulations to determine the effects of the high fidelity aerodynamic model on race vehicle performance metrics. The quasi steady state vehicle simulation is developed with a multi-body NASCAR Truck vehicle model, and simulations are conducted for three different types of NASCAR race tracks, a short track, a one and a half mile intermediate track, and a higher speed, two mile intermediate race track. For each track simulation, the effects of the aerodynamic model on handling, maximum corner speed, and drive force metrics are analysed. The accuracy of the high-fidelity model is shown to reduce the aerodynamic model error relative to the conventional aerodynamic model, and the increased accuracy of the high fidelity aerodynamic model is found to have realisable effects on the performance metric predictions on the intermediate tracks resulting from the quasi steady-state simulation.

Classe 1965, novarese ma laziale d’adozione, Antonio Rezza rappresenta un caso di studio esemplare di un performer che afferma la propria radicale alterità e al tempo stesso s’inserisce in un contesto di azione multimediale, affrontando, con metodi e strategie calibrate, contesti espressivi differenti, partendo dal teatro e approdando alla televisione, al cinema e alla letteratura. Critici occasionali e recensori fedeli fanno esercizio di aggettivazione per descriverne azioni e affabulazioni: ciniche, dissacratorie, folli, ribelli, travolgenti, tracotanti, e così via. Tra i suoi (non molti) esegeti c’è anche chi ha scomodato Carmelo Bene e Antonin Artaud, almeno per compararne l’indole anarchica e la sfacciata aggressivi-tà nelle apparizioni pubbliche. Tuttavia Rezza è prima di tutto un artista contemporaneo. Insieme a Flavia Mastrella, scultrice con la quale collabora da oltre vent’anni, ha dato vita a una serie di lavori che tuttora attendono un’analisi organica, per quanto rischiosa. Il saggio qui proposto ha lo scopo di fornire un primo, parziale orientamento all’interno di un percorso artistico magmatico e, se si vuole, sconnesso come quello del duo Rezza-Mastrella, binomio che appare inscindibile per quel che riguarda la dimensione performativa (diversa e più individuale, infatti, l’attività letteraria, in cui Antonio Rezza firma da solo i romanzi pubblicati). Per questo, a una prima parte (firmata da Carlo Titomanlio) centrata sulla peculiare prassi generativa degli spettacoli e sulla corporeità di Rezza in relazione allo spazio scenico, seguirà una seconda (di Igor Vazzaz) focalizzata su alcune proposte interpretative del lavoro dei due artisti, alla luce delle numerose, e forse sorprendenti, connessioni tra il (non) fare scenico di Rezza e le teorie del teatro e del comico.