Abstract The speed information is obtained by sensors in the control strategy of brushless doubly-fed machine (BDFM) independent power generation system. However, the use of sensors increases the hardware cost of the system, reduces the reliability and the sensors are difficult to adapt to the harsh environment such as high temperature and high humidity. In order to solve the above problems, a speed sensorless direct voltage control method for brushless doubly-fed machine independent generation system is proposed. At the same time, in order to improve the control quality, the improved particle swarm optimization algorithm is used to optimize the control parameters of the system. Simulation results show that the BDFM independent power generation system can still maintain excellent performance and can meet the performance requirements in various operating conditions with the control method proposed in this paper.
The language service platform is an online platform that provides real-time language services for enterprises and individuals. The demanders can obtain the required language services quickly and find professional language services immediately, saving time and effort. A language service platform was built based on client/server. The platform includes online, photo, manual translation and language selection. The service platform builds a corpus, provides standardized services and realizes applications with multiple interaction methods for multi-platform devices. The online translation uses Python to crawl data and implements corpus services through the. NET platform; manual translation builds an artificial translation module through the. NET platform and uses WebAPI to provide external services. The language service platform is part of the national language capacity, essential in promoting international economic and cultural exchanges.
In this work, we propose a convex optimization-based receding horizon control method for the station-keeping control of halo orbit in Earth-Moon system. we leverage the advantages of convex optimization and receding horizon control and design the method under the high-fidelity ephemeris model, making it feasible to actual mission. Simulation results show that our method reaches low tracking errors and control consumption and produces better performances than linear quadratic regulation method.
Since 2020, as the COVID-19 pandemic has swept the globe, most schools and offline education institutions around the world have been forced to close indefinitely and shift educational activities to online platforms.As different countries have different characteristics, this paper selects China, the United States, India and Nepal, which are four representative countries for specific analyses, to judge the current situation and future development trend of online education in the world.Firstly, this study makes detailed analyses of the current situation, positive factors and constraints of online education in four countries and its future development direction from the aspects of social background and user preference.Then, this paper discusses the development of online education in different regions of the world and its limiting factors.Finally, this paper gives the future development trend of global online education industry.
When the coal-rock is loaded, the radiation field changes to produce weak radiation, which is easily perturbed by the environment. In this article, the preprocessing method combining the three-sigma principle and the compound interpolation method was studied, based on the analysis of the composition of the radiation collected directly from the loaded coal-rock. Combined with the improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) algorithm, the K-Means algorithm based on Pearson distance, the DBi index, and improved Pearson coefficient, a radiation denoising method based on ICEEMDAN-PCK-Means-IP was proposed. Then, the effect of each link in the method on the noise reduction of the simulated loaded coal-rock radiation signal was analyzed. Finally, the infrared radiation (IR) signal directly obtained from uniaxial loading experiments on coal-rock was used as an example to compare and verify the denoising effect of the proposed method on the radiation of loaded coal-rock. The results show that the radiation from the directly collected loaded coal-rock will be disturbed by multiple sources, which will drown out the features due to the deformation. The preprocessing method in this article can effectively eliminate the "bad points" in the original data, and its results are highly similar to the data without "bad points." Moreover, each link of the ICEEMDAN-PCK-Means-IP method affects the denoising effect. Its denoising effect on simulated and real radiation is obviously better than that of other "EMD-like" denoising methods or its combined method, and can effectively extract the deformation-related signals from the original radiation.
In order to solve the problems of difficult medication monitoring and low dispensing efficiency in geriatric homes, this paper designs an intelligent spliced medicine box. The medicine box adopts STM32F407Z as the main control chip, uses the motor to control the rotation of the medicine box to as-sist patients to take out medicine, and has a voice to remind patients to take medicine in time. At the same time, the identification technology is utilized to avoid the elderly taking the wrong medicine. An application program is designed to realize the function of remote monitoring. In addition, the medicine box can be spliced together one by one to form a set of medicine box array, which is convenient for unified dispensing. And the dispensing strategy is optimized, which greatly improves the dispensing efficiency of the nursing homes for the elderly. Finally, intelligent management of medication reminder, medication remote monitoring and rapid dispensing is realized, which has certain practical value in the market.
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