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A part of the CELSS Test Facility design effort is the Engineering Development Unit (EDU), a closed crop growth system. The crop growth chamber and system hardware are contained in an enclosure that isolates them from the laboratory environment. The control system includes active differential pressure control. This paper describes a linear optimal quadratic performance index design technique that was used to synthesize a state feedback controller. Performance results of the closed loop linear system as predicted by simulation is presented.

This paper presents details of the mathematical modeling and simulation of the shoot side subsystem of a closed crop growth chamber. A discussion of the derivation of the mathematical model and the development of the simulation is presented, including a computer simulation with temperature control. The objective is to design a temperature and pressure control system.

The objective of this paper is to study the lean limit operation of a spark ignited internal combustion engine. The aim is to reduce the combustion duration and cyclic variation in lean mixtures; both of which are sensitive to the initial stage of combustion. This work involves increasing the burning rate in lean mixtures by minimizing the ignition delay through the use of a multiple electrode spark plug that has a total gap length of 10.2 mm. The multiple electrode spark plug was tested on a single cylinder engine and its performance was compared with a conventional spark plug in the following areas: lean limit air-to-fuel ratio; CO, HC, and NO emissions: cyclic variations; and combustion duration.