Simulation analysis of the effects of methanol-polyoxymethylene dimethyl ethers blends on combustion and emissions of a PCCI engine

The effects of methanol/polyoxymethylene dimethyl ethers (PODE) mixture with different blending ratios on premixed charge compression ignition (PCCI) combustion and emission performance have been researched through the anlysis of CFD software CONVERGE. Premixed combustion is achieved by a single early injection of fuel into the cylinder. The results show that the combustion start point delays and the peak pressure decreases with the increase of methanol blend ratio. The effects of injection timing on the combustion and emission characteristics of PCCI were studied by using a mixture of the same proportion of methanol. The results show that the advance of injection time leads to more homogeneous mixture and higher peak heat release. But too early injection reduces the temperature in the cylinder and makes the combustion worse, resulting in the increase of HC, soot and CO emissions. NOx emissions decrease with the advance of the injection time.

Controllability of Semilinear Systems with Multiple Variable Delays in Control

In the paper semilinear, finite-dimensional, control systems with multiple time variable point delays in admissible controls are considered. Using Rothe’s fixed-point theorem, sufficient controllability conditions are formulated. The results of the paper are generalization to many time variable delays in control, of the results published recently.

On finite-time consensus objectives in time-varying interconnected discrete linear dynamic systems under internal and external delays

This article formulates the properties of achievable consensus of linear interconnected discrete systems with multiple internal and external point delays. The formulation is stated in an algebraic generic context as the ability of achievement of (a non-necessarily zero) finite-time common error between the various subsystems. The consensus signals are generically defined so that they can be, in general, distinct of the output or state components. However, the consensus signals of all the interconnected subsystems have the same dimension for coherency reasons. A particular attention is paid to the case of weak interconnection couplings in both the open-loop case and the closed-loop one under, in general, linear output feedback. Some further extensions are given related to consensus over intervals and related to consensus of positive interconnected systems.

Positivity and Stability of the Solutions of Caputo Fractional Linear Time-Invariant Systems of Any Order with Internal Point Delays

This paper is devoted to the investigation of the nonnegative solutions and the stability and asymptotic properties of the solutions of fractional differential dynamic systems involving delayed dynamics with point delays. The obtained results are independent of the sizes of the delays.

Global Stability of Polytopic Linear Time-Varying Dynamic Systems under Time-Varying Point Delays and Impulsive Controls

This paper investigates the stability properties of a class of dynamic linear systems possessing several linear time-invariant parameterizations (or configurations) which conform a linear time-varying polytopic dynamic system with a finite number of time-varying time-differentiable point delays. The parameterizations may be timevarying and with bounded discontinuities and they can be subject to mixed regular plus impulsive controls within a sequence of time instants of zero measure. The polytopic parameterization for the dynamics associated with each delay is specific, so that(q+1)polytopic parameterizations are considered for a system withqdelays being also subject to delay-free dynamics. The considered general dynamic system includes, as particular cases, a wide class of switched linear systems whose individual parameterizations are timeinvariant which are governed by a switching rule. However, the dynamic system under consideration is viewed as much more general since it is time-varying with timevarying delays and the bounded discontinuous changes of active parameterizations are generated by impulsive controls in the dynamics and, at the same time, there is not a prescribed set of candidate potential parameterizations.