This paper presents an alternative approach to investigating the origin and the development process of knock vibrations that occur in an indirect injection (IDI) diesel engine. In contrast to the conventional analysis of the pressure rise rate, this study focuses on the analysis of instantaneous resonant frequencies at different moments during combustion. The smoothed pseudo-Wigner-Ville distribution (SPWVD) and Hilbert transform methods are applied to estimate the resonant frequency under different conditions representing various knock intensities. Two important factors are found significantly to influence knock development. Finally, design strategies and preferable fuel injection patterns are suggested for reducing knock intensity.
We study delayed cellular neural networks on time scales. Without assuming the boundedness of the activation functions, we establish the exponential stability and existence of periodic solutions. The results in this paper are completely new even in case of the time scale𝕋=ℝorℤand improve some of the previously known results.
This paper is concerned with the periodic solutions for a class of stochastic Cohen–Grossberg neural networks with time-varying delays. Since there is a non-linearity in the leakage terms of stochastic Cohen–Grossberg neural networks, some techniques are needed to overcome the difficulty in dealing with the nonlinearity. By applying fixed points principle and Gronwall–Bellman inequality, some sufficient conditions on the existence and exponential stability of periodic solution for the stochastic neural networks are established. Moreover, a numerical example is presented to validate the theoretical results. Our results are also applicable to the existence and exponential stability of periodic solution for the corresponding deterministic systems.
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