Vol. 6, No. 1 (2022): Regular Issue

In this paper, we establish sufficient conditions for the existence and uniqueness of solutions for a class of boundary value problems with integral condition for neutral fractional integro-differential equations. The results are established by the application of the contraction mapping principle, Leray-Schauder alternative theorem and Krasnoselskii fixed point theorem. An example is provided to illustrate the main results.

In order to effectively recognize and identify liquor quality by nuclear magnetic resonance (NMR) spectrum data, we propose a hybrid data processing and recognition algorithm. In this algorithm Kernel principal component analysis (KPCA) was used to remove the correlation and reduce dimension of the NMR spectrum, and then convolutional neural network (CNN) was used for classification and identification of the processed spectrum. The compared experiment result show that the proposed KPCA+CNN method can obtain higher accuracy than CNN and PCA+CNN methods based on the NMR spectrum. The KPCA+CNN algorithm has good application prospect and reference value.

An active research subject in robotics and aeronautics, underactuated mechanical systems (UMS) have been extensively explored for applications where maintaining stability and safety is of paramount importance. All contemporary control methodologies of recent have been applied to controlling various UMS designs. A great amount of effort is documented on a yearly basis by journals and conference proceedings claiming to offer effectively better solutions to improved UMS control. However, control design for UMS is still considered an open problem due to issues including parametric uncertainty, coupled nonlinear dynamics, and need for fewer control actuators. This presentation presents a comprehensive survey on the present state-of-affairs pertaining to the control of UMS of different configurations. Relevant references in the open literature dating as far back as 1990 are reviewed and meticulously categorized. Popular underactuated control techniques are reviewed, and their primary features re-examined, for their strengths and where they fall short in addressing properties of underactuation including coupled dynamics, nonlinearity and non-stationarity. No prior review articles have provided similarly critical while also in-depth review of published works on UMS control. This survey serves as an expanded reference for researchers and practitioners who seek to control UMS with efficacy.

A damping analysis method for power system stabilizer (PSS) based on transient circuit is proposed. The transient equivalent circuit of sixth order generator model and its energy function is obtained According to circuit theory, the damping of excitation system is analyzed. Based on the analysis, a PSS damping evaluation method is proposed. The simulation results of a single machine infinite bus system show that the proposed method can accurately evaluate the damping of PSS.

In this paper, two-dimensional dynamical systems with constant and linear vector fields are presented. Dynamical systems with one-vari- able vector fields are presented and the singular dynamics of two-dimensional linear systems was discussed. Based on the variable-inde- pendent and variable-crossing linear vector fields, the dynamics based on saddle, sink, source and center equilibriums are discussed. Two-dimensional linear dynamical systems with two linear vector fields are discussed, and local dynamics of the saddle and focus equilibriums are presented. The dynamics and stability of two-dimensional linear dynamical systems are presented comprehensively for a better understanding of dynamical behaviors of the two-dimensional linear systems.