Speed flame propagation in Otto cycle engines is one of the principal characteristics of fuel and is fundamental in defining the ignition advance. The greater the propagation speed the less the negative work required to compress the mixture before the piston reaches the top dead center and the higher the cycle's efficiency. This paper presents experimental results of time measurements of the fuel's ignition and the maximum pressure rating in the combustion chamber of a Cooperative Fuel Research engine specially instrumented. The combustion duration measurements of oxygenated and non-oxygenated fuels were taken as a function of the compression ratio (8:1, 10:1 and 12:1) and lambda (k). The speed flame propagation in the combustion chamber is significantly changed with the change of the lambda different compression ratios. The VNG has a maximum in the speed flame propagation in the stoichiometric region (k = 1.0) in all compression rates in this study. Similar behavior occurs with ethanol and gasohol, but only in compression ratio 12:1. Ethanol and gasohol have the higher rate of flame propagation for all compression ratios measured as compared to the nonoxygenated (isooctane) and oxygenated fuels (MTBE and TAEE).

This paper addresses a comparative study concerning five control techniques applied to high-performance elevators active suspension systems, such as those employed in "skyscrapers". The main objective is to present the different control techniques and analyze the fundamental characteristics of each controller. To accomplish this, the development of the mathematical model of the controlled system is outlined and its integration with the control algorithms is presented. Besides three classic controllers (State Feedback, PID and Sky Hook), due to the significant dynamic behavior dependence on the mass of the passengers in the total mass transported, two adaptive control algorithms are used to compensate the effects of the mass oscillations of the system as the number of passengers varies along the operation cycle. Simulation results are employed to illustrate the behavior of the system when controlled by means of the presented algorithms.

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