The hypoelliptic operators with drift appears in many research fields, for instance, mathematical finance theory, kinetics and models of human vision. In this paper, we establish the Lorentz boundedness of fractional integral operators on homogeneous group, then applying this result and the relevant properties of the fundamental solutions, we obtain global Lorentz estimates of hypoelliptic operators with drift. These estimates expand the regularity of operators generated by vector fields.
This paper proposes an algorithm for extracting the instantaneous frequency of the incomplete signal under low SNR based on the Viterbi algorithm. We first set the corresponding parameters, and use STFT to project the signal onto the time frequency plane. Locate the maximum value of the plane, thereby positioning the signal component. Taking the time point as the axis, the time-frequency plane is divided into two parts before and after. The Viterbi algorithm with threshold detection is performed in the front and back parts to extract the instantaneous frequency of the signal, and connect them into a complete instantaneous frequency of the signal component. After that, zeroing is performed near the extracted IF path, and then the maximum value in the full plane is re-searched to extract the instantaneous frequency of the next component. Experiments show that the algorithm has achieved good results under the low signal-to-noise ratio condition.
As abuse and malicious rumor often occur in the " fans community ", which has an extremely bad impact on the society, we need to study the emotional tendency of the comment language of the " fans community " in the network, so as to identify the "loyal fans" and "black fans" and explore the language characteristics of the two types of fans. In this paper, more than 50,000 comments were extracted from common Chinese websites, and some data were pre-processed and manually annotated to construct a Chinese "fans community" comment dataset. The three supervised algorithms and one unsupervised algorithm for" fans community ". Emotional dictionary method are used to classify the " fans community " comment information. Then it is analyzed such as the content of the two types of fans comments in terms of sentences, word count, words, and so on. The experimental results show that all the methods adopted in this paper can effectively classify the comments of "loyal fans" and "black fans" by emotion dichotomy. In terms of language characteristics, the comments of "loyal fans" are characterized by multiple nouns, long sentences and regular comment time. "Black fans" comments are often verbs, short sentences and random comments.
Computer simulation technology is a new technology, which is developing rapidly at home and abroad in recent years, and has expanded this technology to many fields. From the perspective of practical application, computer simulation technology has made good achievements in the field of sports. Computer simulation technology can simulate human motion through high-speed photography and motion capture, and find the problems existing in the process of athletes through the calculation of system algorithm on the computer, so as to better improve sports performance. In the motion simulation system, the emerging new algorithm theory can carry out multi-dimensional data acquisition and input, and analyze the stress condition of human bones in detail, which is a good tool for athletes' training. Firstly, this paper summarizes the current research of computer simulation technology and motion simulation system, and then puts forward the problems and corresponding solutions of motion simulation technology in China, hoping to provide some references for motion simulation technology in China.
Based on the practical application background, photovoltaic (PV) grid inverter single-phase and three-phase inverter is studied in detail in this paper the basic working mechanism of inverter, including topology architecture, modulation strategy, parameter design, harmonic analysis and control method, and through the Matlab/Simulink simulation platform built simulation model of single phase/three-phase photovoltaic grid inverter, The correctness and effectiveness of the proposed design method are verified.
