Bøker av Zheng Li

With the rapid development of military and aerospace industries, the performance requirements of numerical control equipment are constantly improving. Permanent magnet linear synchronous motor (PMLSM) has the advantages of high speed and high precision. Meanwhile, it overcomes the influence of various factors in the intermediate links such as the screw and gear in the rotating motor. Therefore, PMLSM has very important value in high-precision industrial servo applications that require high-precision linear servo drivers. This book mainly introduces the intelligent vector control strategy and sensorless control strategy of PMLSM. Compared with the traditional control strategy, the intelligent vector control strategy of the motor can better improve the control performance of the motor. In modern motor control systems, many new intelligent vector control strategies have been proposed. This paper focuses on the sliding mode control strategy, model predictive control strategy, adaptive control strategy, active disturbance rejection control strategy and model free control strategy of PMLSM. Relying on the mathematical model of PMLSM, the formula derivation of the above intelligent control strategies is explained in detail, and the system block diagram is drawn to help readers better understand the basic working principle of these intelligent control strategies. In the control system of the motor, in order to achieve better control performance, accurate speed information and mover position information of the PMLSM are required. The traditional collection of speed information and mover position information is realized by adding mechanical sensors, but the addition of mechanical sensors will lead to an increase in the cost of the motor. Meanwhile, the size and weight of the motor will be affected, and there will be some additional interference factors, which will have a certain impact on the control performance of the motor. In order to make the motor get rid of the dependence on mechanical sensors, the sensorless control strategy is introduced into the motor control system, and the position information and speed information of the motor are estimated through a certain control algorithm. At present, the common sensorless control strategies are high-frequency signal injection method and fundamental back EMF observation method. This paper introduces the design of the sliding mode observation method, the observation method based on the model reference adaptive system and the observation method based on the extended Kalman filter algorithm. The above sensorless control strategies are introduced in detail through the corresponding formula derivation and system block diagram.

Since the new leadership came to power in 2012, China''s domestic governance and public diplomacy have experienced some profound changes. At home, a far-reaching anti-corruption campaign significantly restored the government''s credibility and reinforced public trust in the party-state''s governance model, leading to a surge of nationalist pride. Internationally, the previous diplomatic principle, hide our capacities and bide our time, gradually faded away with the emerging ideas like China''s ideas and China''s wisdom. Good governance and anti-corruption efforts were expected to enhance soft power overseas. The party-state successfully governed the state for decades relying on its controversial governance approaches. The country also has visibly demonstrated economic and social development. However, China''s growing influence has failed to be recognised as soft power, being viewed rather as sharp power most times. The monograph investigates whether China is mindful of exporting its political ideas and whether it considers its governance model to be the pillar of its soft power portfolio. The monograph also analyses how Australia, a western country with close economic ties with China, interprets China''s intended narrative regarding its governance model and development. The questions are addressed through framing analysis of media coverage and in-depth interviews with Australian public diplomacy experts. Most studies in this field focus on externally directed soft power initiatives and the monograph fills the void by drawing attention to domestic affairs. The monograph sheds a new light on the relationship between domestic governance, soft power, and sharp power by examining the congruity between China''s projection and Australia''s mediation and also draws implications about China''s public diplomacy and the future global order by sketching out Beijing''s ambitions and attempts.

This book describes the scale and complexity of China's energy system, using Sankey diagrams to visualize the energy flows across the economy and categorizing the differences between provinces.