Identification and dual adaptive control of a turbojet engine

The objective of this paper is to utilize the design methods of modern control theory to realize a dual-adaptive feedback control unit for a highly nonlinear single spool airbreathing turbojet engine. Using a very detailed and accurate simulation of the nonlinear engine as the data source, linear operating point models of unspecified dimension are identified. Feedback control laws are designed at each operating point for a prespecified set of sampling rates using sampled-data output regulator theory. The control system sampling rate is determined by an adaptive sampling algorithm in correspondence with turbojet engine performance. The result is a dual-adaptive control law that is functionally dependent upon the sampling rate selected and environmental operating conditions. Simulation transients demonstrate the utility of the dual-adaptive design to improve on-board computer utilization while maintaining acceptable levels of engine performance

Study of small turbofan engines applicable to general-aviation aircraft

The applicability of small turbofan engines to general aviation aircraft is discussed. The engine and engine/airplane performance, weight, size, and cost interrelationships are examined. The effects of specific engine noise constraints are evaluated. The factors inhibiting the use of turbofan engines in general aviation aircraft are identified

End to End Optimization of a Mars Hybrid Transportation Architecture

NASAs Mars Study Capability Team (MSCT) is developing a reusable Mars hybrid transportation architecture in which both chemical and solar electric propulsion systems are used in a single vehicle design to send crew and cargo to Mars. This paper presents a new integrated framework that combines Earth departure/arrival, heliocentric trajectory, Mars orbit reorientation, and vehicle sizing into a single environment and solves the entire mission from beginning to end in an effort to find a globally optimized solution for the hybrid architecture

Integrated Optimization of Mars Hybrid Solar-Electric/Chemical Propulsion Trajectories

NASAs Human Exploration and Operation Mission Directorate is developing a reusable hybrid transportation architecture in which both chemical and solar-electric propulsion systems are used to deliver crew and cargo to the Martian sphere of influence. By combining chemical and solar-electric propulsions into a single spacecraft and applying each where it is the most effective, the hybrid architecture enables a series of Mars trajectories that are more fuel efficient than an all chemical propulsion architecture without significant increase to trip time. Solving the complex problem of low-thrust trajectory optimization coupled with the vehicle sizing requires development of an integrated trajectory analysis frame- work. Previous studies have utilized a more segmented optimization framework due to the limitation of the tools available. A new integrated optimization framework was recently developed to address the deficiencies of the previous methods that enables higher fidelity analysis to be performed and increases the efficiency of large design space explorations

An inverter/controller subsystem optimized for photovoltaic applications

Conversion of solar array dc power to ac power stimulated the specification, design, and simulation testing of an inverter/controller subsystem tailored to the photovoltaic power source characteristics. Optimization of the inverter/controller design is discussed as part of an overall photovoltaic power system designed for maximum energy extraction from the solar array. The special design requirements for the inverter/ controller include: a power system controller (PSC) to control continuously the solar array operating point at the maximum power level based on variable solar insolation and cell temperatures; and an inverter designed for high efficiency at rated load and low losses at light loadings to conserve energy

\u3cem\u3eREGII SANGVINIS CLAMOR AD COELUM\u3c/em\u3e, By Dr. Peter du Moulin the Younger (1652), Translated Into English and with an Introduction

(From the Introduction) The beheading of Charles I on the black-draped scaffold outside Whitehall on 30 January, 1649, horrified the monarchs of Europe, for on that planking by the palace banquet room had been taught the most sanguine of all lessons concerning the relative effectiveness of Divine Right and popular will. The dismal negotiations to end the eight years of the English Civil War had aroused the fears of the Continental princes, and Charles\u27 execution confirmed them; this baneful tide of successful rebellion, refuted by theory and hedged by arms, against despotism must be halted at the Channel shore. As the progress of the English Civil War made clearer its possibilities for European thrones, Continental scholars and theologians alike swelled the accompanying paper war with partisan work on the English question. Conspicuous among these writers were the Huguenot humanists, and their occasional enthusiasm for the Royal cause was motivated by something more than a Gallic admiration for the English king\u27s bearing in adversity. The Edict of Nantes was a fiat easily to be swept away by a French king of more constricted view than Henry IV; moreover, St. Bartholomew\u27s Day, the Isle of Rhe, and La Rochelle were recent reminders of the contingency. Therefore, the need to prove loyalty to the French crown was alone a stimulus sufficient to stir the Huguenot scholars to defend the foreign Church of England and monarch who was its head

Beyond Bricks and Mortar: The Use of the City Setting in Fortunata y Jacinta and in Bleak House

In this essay I explore the use of the city settings in Bleak House and Fortunata y Jacinta— the intimate interior spaces and the public exterior venues enlivened, elucidated, placed in the background, and propelled to the forefront by the authors, who carefully select and craft the locales in which societies at large and individual characters live, locations that actively drive the narratives. How do Pérez Galdós and Dickens depict Madrid and London, their complex interiors and streets? In what ways do characters inhabit and move through these spaces? And, what do we learn from the settings in Fortunata y Jacinta and in Bleak House, and from tracing the evolving relationships that the characters maintain with their city environments

Study of small turbofan engines applicable to single-engine light airplanes

The design, efficiency and cost factors are investigated for application of turbofan propulsion engines to single engine, general aviation light airplanes. A companion study of a hypothetical engine family of a thrust range suitable to such aircraft and having a high degree of commonality of design features and parts is presented. Future turbofan powered light airplanes can have a lower fuel consumption, lower weight, reduced airframe maintenance requirements and improved engine overhaul periods as compared to current piston engined powered airplanes. Achievement of compliance with noise and chemical emission regulations is expected without impairing performance, operating cost or safety