Aiming at the problem that the time series forecasting method will produce a certain degree of lag due to its series autocorrelation, the multivariate equivalent ice thickness prediction using ...meteorological data as the feature is used. Aiming at the problem that the prediction accuracy of ice thickness is not high, the attention mechanism is used to assign adaptive weights to multi-dimensional feature parameters and time steps to highlight important information in different feature dimensions and time steps. At the same time, due to the change of ice cover with time, a Bi-directional Long Short-term Memory (Bi-LSTM) is used to establish an ice cover prediction model to make use of the past and future information provided at each time point in the process, and for the parameter selection problem of Bi-LSTM, the sparrow search algorithm (SSA) is used to select the hyperparameters to reduce the error caused by human intervention, and then improve the accuracy of line equivalent ice thickness prediction, and finally verify the validity of the model through experimental results.
A fluid dynamics model of electrolyte in mircroflow inspired by hemodynamic model of aortic is proposed and applied in the self-noise analysis of four-electrode microflow-electrochemical ...accelerometer. Three-dimensional finite element model is established and invested through numerical simulation, the variety of geometrical parameters on different location of electrode and varied time are considered, which can affect the microflow-electrochemical accelerometers self-noise. The result of numerical simulation indicates that, self-noise is related to electrode configuration as well as electrode geometrical parameters. In particular, convection-induced self-noise is correlated to variety of viscosity, and thermohydrodynamic self-noise is correlated to variety of diameter. Such a fluid dynamics model of electrolyte inspired by thermodynamics model can be also used for optimization of the self-noise.
Controllable reactors (CR) are general FACTS (Flexible AC Transmission System) apparatuses, which have played a crucial role in improving the power flow distribution of the system, adjusting the ...reactive power balance of the power grid, stabilizing the voltage, and improving the stability of the system. This paper summarizes the characteristics of various types of controllable reactors, classifies reactors with different structures, and compares different controllable reactors from the perspectives of reactance change, response speed, harmonic problem, and control accuracy. A transformer-type controllable reactor based on flux compensation is proposed, the design scheme of secondary side multi-winding is adopted to realize the large-capacity reactor, the unity of single control winding and multi-control winding in the application is expanded, and the general principle of controllable reactor is obtained through the control of the "linear two-port network" port, and the design principle of such reactor is summarized.
Insertion of the expression for a Gaussian beam into Maxwell's equations leads to four coupled equations governing the evolution of beam parameters in a logarithmically saturable nonlinear medium ...(LSNM). Analytical solutions to the coupled equations have been deduced for cases where the incident beam parameters slightly deviate from those of the spatial soliton. As a result, a detailed description to the Gaussian-type breath mode can be made. For general cases, a graphical analysis has been used to draw the main characteristics of the Gaussian-type breath mode propagating along the LSNM.
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The series active power filter based on magnetic flux compensation (MFC-APF) may lead to low-frequency oscillation of the amplitude of power grid current in the transient process. In the previous ...research, it has been found that the equivalent impedance of MFC-APF will show obvious negative damping characteristic in the low frequency range higher than the fundamental frequency. This paper analyzes that it may act together with the load impedance to make the system resonate. After simplifying the system reasonably, the transfer function model of system equivalent admittance including MFC-APF and the load is established. The analysis results of the model show that the amplitude of the equivalent admittance has a resonant peak near the fundamental frequency, resulting in the corresponding harmonic component of the current in the dynamic process, which is manifested as the low-frequency oscillation of the current amplitude. Finally, according to the impedance characteristics of MFC-APF, an improvement method is proposed, and effectiveness of the proposed model and method are verified by simulation in Matlab/Simulink.
This paper proposed a series hybrid active power filter (SHAPF) with the function of adjustable impedance. The principle of SHAPF based on magnetic flux compensation is addressed. A linear ...transformer with air gap and multiple secondary windings is chosen, which are injecting specific currents into multiple secondary windings respectively. The fundamental current of primary winding is detected and function as the initial reference signal. And the initial reference signal would be phase shifted to constitute the second type of current reference signals. The multiple secondary windings are also divided into two types, corresponding to be controlled by the two reference currents, so that the primary winding can almost present short circuit for harmonic currents and continuously variable impedance for fundamental current. Besides, the stability condition is derived and analyzed in detail. The simulation results have verified the effectiveness of the proposed SHAPF with adjustable fundamental impedance.
We propose a novel set of Poisson Cluster Process (PCP) models to detect Ultra-Diffuse Galaxies (UDGs), a class of extremely faint, enigmatic galaxies of substantial interest in modern astrophysics. ...We model the unobserved UDG locations as parent points in a PCP, and infer their positions based on the observed spatial point patterns of their old star cluster systems. Many UDGs have somewhere from a few to hundreds of these old star clusters, which we treat as offspring points in our models. We also present a new framework to construct a marked PCP model using the marks of star clusters. The marked PCP model may enhance the detection of UDGs and offers broad applicability to problems in other disciplines. To assess the overall model performance, we design an innovative assessment tool for spatial prediction problems where only point-referenced ground truth is available, overcoming the limitation of standard ROC analyses where spatial Boolean reference maps are required. We construct a bespoke blocked Gibbs adaptive spatial birth-death-move MCMC algorithm to infer the locations of UDGs using real data from a \textit{Hubble Space Telescope} imaging survey. Based on our performance assessment tool, our novel models significantly outperform existing approaches using the Log-Gaussian Cox Process. We also obtained preliminary evidence that the marked PCP model improves UDG detection performance compared to the model without marks. Furthermore, we find evidence of a potential new ``dark galaxy'' that was not detected by previous methods.
To deal with the icing of overhead lines caused by frequent ice disasters, this subject proposes a new uninterruptible electric ice-melting technology for distribution network. The deicing device is ...composed of adjustable reactor and earthing transformer. The head end of the device is connected to the substation power supply through a transformer, and the end is short-circuited with one-phase line in the ice- covered section through a ground wire to form a zero-sequence circuit, so as to provide zero-sequence current to the line to be deiced online to make the line heat up and melt the ice to achieve deicing without power outage. After the article puts forward this scheme, the model was built in Maxwell 3D software for verification, and the ice melting test is carried out on the pilot line, which proves the feasibility of this scheme.
