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An intelligent fault detection and classification for abnormal current data of transmission lines is proposed. According to the monthly report and the abnormal condition information stored in the system, four kinds of abnormal state data are chosen. By extracting three fault features of data, combining k-means algorithm and TSNE dimensionality reduction algorithm, fault categories can be clearly and intuitively distinguished, and the purpose of intelligent alarm for abnormal state current is realized.

Disturbance-Free-Payload is a novel spacecraft architecture proposed to achieve perfect vibration isolation performance of space applications. In this paper, the object under study is a DFP system in which a flexible umbilical connection between the support module (SM) and the payload module (PM) is introduced for data, power and fluid transfer. Bead model accounting for properties of mass and flexibility, is utilized to model the flexible umbilical. With incorporation of bead model, six degree-of-freedom multibody rigid-flexible dynamics for the DFP system is established via Newtonian mechanics. Along with rotational coupling between solar panels and SM, translational coupling, in particular, is taken into consideration since there is a stringent requirement on relative position between PM and SM. Based on the accurate motion equations of the DFP system, simulation studies are conducted to gain insight of the impact of umbilical connection and translational coupling on pointing performance of the DFP system. Simulation results validate effectiveness of DFP configuration in isolating vibrations transmitted from SM to PM. Besides, umbilical connection plays an important part in degrading pointing performance of PM whereas it exerts little impact on SM. Moreover, translational coupling leads to significant pointing performance degradation for both PM and SM.

In this paper, a three-dimensional (3D) impact-angle-control guidance law is proposed based on the approaches of nonsingular terminal sliding mode control and fixed-time convergence theory to intercept a maneuvering target. The guidance law is derived based on the coupled 3D engagement dynamics. To intercept the target with an expected impact angle, the nonsingular terminal sliding mode control is designed to ensure that the line-of-sight (LOS) angles and rates rapidly reach the desired values. Furthermore, the fixed-time convergence algorithm is proposed to guarantee that the LOS angles and rates are convergent in fixed time. The upper bound of the settling time can be obtained by presetting the parameters of the proposed guidance law, and it is independent of the initial conditions. The stability of the guidance system is proven via Lyapunov stability theory. The simulation results are presented to validate the efficiency and superiority of the proposed guidance law.

Pointing accuracy and pointing stability play an important role in gravitational wave detection spacecraft. This paper presents dynamics model, pointing accuracy and stability analysis of a payload-spacecraft system connected using umbilical and non-contact actuators. Accurate model of payload-umbilical-spacecraft is proposed which takes into account the translational stiffness and damping effects, as well as the torsional stiffness effect. The Lagrangian approach is applied to derive the rigid-flexible coupling dynamics model. Both of the open-loop and closed-loop simulation studies are conducted to investigate the pointing accuracy and stability of the payload. The results indicate that the umbilical significantly degrades the vibration isolation performance of the payload at low frequencies between 0.01 Hz and 1 Hz. Simulation of two other cases, the payload without umbilical and the payload with umbilical considering only the translational stiffness effect, are also performed. The results of these three cases show that the umbilical greatly degrades the pointing accuracy of the payload and lowers the pointing stability. The torsional stiffness also has a slight effect on the pointing accuracy of the payload.

Design tools for circular PCF have been developed to analyze the vector modes by giving the modal map of the cutoff condition of eigenmodes and colormap of minimum effective refractive index separation between different eigenmodes. We also analyze the effect of fiber parameters for mode quality.