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We investigate some critical phenomena of a Ising ferrimagnetic system on a square lattice with spins $Q=\pm 7/2, \pm 5/2, \pm 3/2$ , and ±1/2 in a $B$ sublattice and spins $S=\pm 5/2, \pm 3/2$ , and ±1/2 in a $A$ sublattice in presence of an $h'$ external magnetic field, such that $Q$ and $S$ are the nearest-neighbors ferrimagnetically coupled. Using Monte Carlo simulations, we calculate the finite-temperature phase diagrams of magnetization, specific heat, and magnetic susceptibility of the model. The system is defined by a Hamiltonian $(\mathcal {H})$ that contains ferromagnetic next-nearest-neighbors interactions between $S$ spins ($J'_{2}$), as well as external magnetic field and anisotropy interactions at each point of lattice. For a defined range of parameters in $\mathcal {H}$ , the system exhibits discontinuities in their physical variables and spin compensation behaviors. In the planes $J'_{2}-k_{\mathrm{ B}}T'$ and $h'-k_{\mathrm{ B}}T'$ , we analyze the relationship between the critical, compensation, and discontinuous phase transition temperatures with the external magnetic field and the next-nearest-neighbors interaction between $S$ spins. We found that the existence of discontinuous phase transition depends on the strengths of $h'$ and $J'_{2}$. [ABSTRACT FROM AUTHOR]

The relationship between Maxwell’s equations and the wave equation is exploited to show how problems involving the latter can be converted from a second-order differential equation into one of the first order. As an immediate consequence, it becomes possible to solve the wave equation without resorting to double differentiation or integration. An example of application is given utilizing the Maxwellian equations to solve both electromagnetic and equivalent acoustic wave problems. [ABSTRACT FROM AUTHOR]

We propose a hybrid control system performing set-point regulation of an exhaust gas recirculation valve of a Diesel engine. The control technique is based on a first-order reset element (FORE) embedded with an adaptive feedforward action whose aim is to provide asymptotic rejection of disturbances acting at the plant input. The feedforward action is adapted by suitable resetting laws occurring whenever the FORE is reset to zero. We first provide a formal analysis of the effectiveness of the adaptive reset system to guarantee asymptotic set-point regulation, and then, we illustrate how the adaptive feedforward can be parameterized for improved transient performance. We experimentally illustrate the proposed solution on a Diesel engine testbench, which reveals substantial position accuracy improvement during a standard driving cycle, as compared with the production standard solution. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel computing paradigm aimed at solving constrained optimization problems in electric power systems (a.k.a. optimal power flow analysis). The insight is to formulate the OPF problem by a proper set of ordinary differential equations, whose equilibrium points correspond to the optimization problem solutions. Starting from the Lyapunov theory, it will be shown that this artificial dynamic system could be designed to be stable with an exponential asymptotic convergence to equilibrium points. This important feature allows the analyst to overcome some of the inherent limitations of the traditional iterative minimization algorithms that can fail to converge due to the highly nonlinearities of the first-order conditions. Extensive simulation studies aimed at assessing the effectiveness of the proposed computing paradigm are presented and discussed. [ABSTRACT FROM PUBLISHER]

In this brief, an efficient implementation of reconfigurable warped digital filter with variable low-pass, high-pass, bandpass, and bandstop responses is presented. The warped filters, obtained by replacing each unit delay of a digital filter with an all-pass filter, are widely used for various audio processing applications. However, warped filters require first-order all-pass transformation to obtain variable low-pass or high-pass responses, and second-order all-pass transformation to obtain variable bandpass or bandstop responses. To overcome this drawback, the proposed method combines the warped filters with the coefficient decimation technique. The proposed architecture provides variable low-pass or high-pass responses with fine control over cut-off frequency and variable bandwidth bandpass or bandstop responses at an arbitrary center frequency without updating the filter coefficients or filter structure. The design example shows that the proposed variable digital filter is simple to design and offers substantial savings in gate counts and power consumption over other approaches. [ABSTRACT FROM AUTHOR]