Sensorless Control of Permanent Magnet Synchronous Motor Based on the Improved Sliding Mode Observer

Sliding mode observer (SMO) which has a strong robustness is used in the sensorless control system of permanent magnet synchronous motor (PMSM). The method is usually used to estimate the rotor position although it has the chattering problem. According to the causes of the chattering in traditional SMO, the method of improved sliding mode observer (ISMO) is proposed in this paper. Sign function is replaced by the saturation function to suppress the chattering problem, and the speed of PMSM is estimate when combined with field oriented control (FOC) method. A hardware platform of 2.7 kW, 10 000 r/min PMSM is built to verify the control effectiveness of ISMO. Simulation analysis and experimental result show that ISMO can estimate the rotor speed accuracy and reduce the chatting at the same time.

Research on Crowdsourcing Camera Mode System based on Block Chain Technology

As a new business model, the crowdsourcing camera mode has been paid close attention in recent years. However, traditional crowdsourcing operations rely too much on centralized institutions, which have many drawbacks. It is precisely because of this that the superiority of block chain technology is reflected. With the flourishing development of the Internet and the ever-changing block chain technology, this paper provides the research on crowdsourcing camera mode based on block chain technology from four aspects including the analysis of decentralization, the strengthen of security precautions, the establishment of appropriate systems and the gradually transition of token system.

Application of Improved Eclat Algorithm in Students’ Evaluation of Teaching

The evaluation system of students is to find a way to solve the status way according to the exact needs of students and the teaching requirements of teachers, so as to improve the teaching level of teachers and improve the quality of school education. This paper uses the real evaluation sample and uses the data mining association rule algorithm to comprehensively analyze the massive data of the evaluation data and the basic information of the teacher. The purpose is to obtain the association rules between the teacher’s comprehensive information and its evaluation results. Using the evaluation data to explore its core issues. In this paper, the Eclat algorithm of association rules improves the problem of insufficient memory and occupying a large amount of time when searching for frequent itemsets in the data. The breadth-first algorithm is added to save operation time and improve the efficiency of the algorithm. The effectiveness of the improved algorithm is verified by comparative experiments and applied to the evaluation system so as to provide suggestions for the professional development of teachers from an objective perspective, and to build a harmonious, "people-oriented" evaluation system for students.

One signal processing method of OCT based on colored noise extended Kalman filter

When an optical current transformer is used to measure current, its output signal is mostly non-linear and contains colored noise; on the other hand, when the power system is in steady state operation, the frequency is not stable. This paper proposes an optical current transformer signal processing method based on colored noise extended Kalman filter which can reduce the measurement error caused by colored noise and realize frequency tracking. The following two cases are considered: 1) the dynamic noise is colored noise; 2) the observation noise is colored noise. In these two cases, the corresponding formulas of the proposed method are analyzed and derived. Simulation results showed that the extended Kalman filtering method based on colored noise can effectively filter the colored noise, and the output waveform and output error obtained by this method are improved effectively.

Modeling of joint water-supply scheduling with multi-source in Beijing under uncertain conditions

After the Middle Route of South-to-North Water Transfer Project (SNWTP) finished, a pattern of joint water-supply including SNWTP water, the surface water of Miyun reservoir and underground water has been formed in Beijing. In view of the uncertainty in water-supply scheduling, this study takes 2020 as the planning year, and the influence of uncertain factors on the system cost was fully considered by interval two stages planning method. In order to minimize the total water-supply cost, a joint water-supply scheduling model in Beijing has been established, which reflects the actual situation of the joint watersupply system with multiple sources. The results illustrate that the minimum water-supply cost of Beijing will be [14.6, 25.4] billion yuan in 2020, and the optimal water-supply of Miyun reservoir, groundwater and SNWTP water expected to be 0.54, 2.05 and 0.95 billion m ³ , respectively.

Analysis of Complementary Characteristics of Wind/PV/hydro Power Based on the Bundled Output

There is complementarity among wind, photovoltaic, and hydro power (wind/PV/hydro power), which is closely related to the bundled installed capacity of wind/PV/hydro complementary power generation system and regulating ability of hydropower. This paper evaluates the complementary characteristics among wind, PV, and hydro power though the ability of the system to output power smoothly. First, the ratio of installed capacity of wind to PV power is determined by minimizing the volatility of wind/PV joint power generation. Second, an optimization model, with the objective of maximizing grid-connected and steady output of wind/PV/hydro complementary system in the dry season, to determine the bundled output of the system is proposed. Third, the complementary characteristics of wind/PV/hydro power are analyzed by the bundled output and the absorptive rate of new energy in the dry season. The implication in the Yalong River shows that: (1) The optimum ratio of installed capacity of wind to PV power is 0.7. (2) The bundled output of wind/PV/hydro system is 1.742GW, in which 6.3GW are bundled capacity of wind/PV/hydro power. (3) The complementarity of wind/PV/hydro power will be strengthened with the increase of runoff in the dry season and the decrease of the new energy installed capacity. The research can provide guidelines for the planning and design of the clean energy complementary base.

P300 Acetyltransferase Mediates Stiffness-Induced Activation of Hepatic Stellate Cells Into Tumor-Promoting Myofibroblasts

Hepatic stellate cells (HSCs) contribute to desmoplasia and stiffness of liver metastases by differentiating into matrix-producing myofibroblasts. We investigated whether stiffness due to the presence of tumors increases activation of HSCs into myofibroblasts and their tumor-promoting effects, as well as the role of E1A binding protein p300, a histone acetyltransferase that regulates transcription, in these processes.

Research Update: Hard carbon with closed pores from pectin-free apple pomace waste for Na-ion batteries

Direct bandgap type-I GeSn/GeSn quantum well on a GeSn- and Ge- buffered Si substrate

Detection and evaluation of weld defects in stainless steel using alternating current field measurement