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The traditional position-free control method of brushless direct current (DC) motor has some problems, such as difficulty in starting detection and phase delay caused by filter circuit. In order to solve this problem, it was proposed that when the upper bridge arm was modulated by pulse width and conducted (H_PWM_ON), at the same time the lower bridge arm always conducte (L_ON), the phase switching point was acquired to realize winding switching detection by comparing the voltage of the non-conducting phase end with that of the neutral point. This method does not need filtering circuit and has the characteristic of overcoming the defect of traditional method when starting the motor. The research results show that this method can be used in the no position control, and the motor can start up quickly in 0.2 s and run smoothly. [ABSTRACT FROM AUTHOR]

A wide wavelength range tunable guided-mode resonance filter (GMRF) with high peak efficiencies, narrow linewidths, and low sidebands is experimentally demonstrated. The resonance wavelength can be tuned under TM polarized light illumination by rotating the angle of incidence. The GMRF composed of a one-dimensional grating layer and two waveguide layers on a glass substrate is designed with rigorous coupled-wave analysis. The grating structure of the GMRF is patterned by interference lithography with two ultraviolet laser beams. The reflection colours of fabricated GMRF can be shifted from blue to red by rotating the angle of incidence. The measured full width at half-maximums of the reflection peaks located at 450.6, 500.9, 551.0, 601.1, and 651.3 nm are 3.1, 3.9, 4.3, 3.8, and 4.1 nm, respectively. The corresponding sidebands of measured spectra are below 0.2. Compared with previous experimental studies on tunable structures, the narrow linewidths and low sidebands of the proposed GMRF are remarkably improved. [ABSTRACT FROM AUTHOR]

• The voxel-based morphological process optimized the automatic extraction procedure of digital aggregates. • A robustness and accuracy analysis map was designed based on the virtual gradation of asphalt mixture. • The three-dimensional reconstruction algorithm can be evaluated quantitatively and then optimized purposefully. • Four types of internal defects generated by the traditional pixel-based method were detected. Three-dimensional image reconstruction plays a pivotal role in microstructure information extraction and virtual mechanical experiments of asphalt mixture. However, the traditional pixel-based reconstruction algorithm tends to be powerless in processing three-dimensional (3-D) mesostructure. Therefore, this paper aims to develop a robust and accurate algorithm for high-quality aggregate particle extraction. To this end, the global thresholding and three-dimensional mathematical morphological methods were conducted directly based on voxel operation. Then the calculated weight-based gradation was utilized to develop the robustness and accuracy analysis map (RAAM), which assesses and compares the traditional and novel reconstruction algorithms. As a sequence, the voxel-based method had higher accuracy and lower perturbation sensitivity than the existing procedures. Additionally, the computed efficiency was improved dramatically by breaking tight bounds and conservatism. Finally, the inevitable algorithm defects caused by multiple morphological treatments in the traditional method have disappeared in the novel one. [ABSTRACT FROM AUTHOR]

In the context of rapid urbanization and global warming, how to use urban green space (UGS) with high-efficiency to mitigate the urban heat islands (UHIs) effect in different climate zones has become an urgent issue. However, few studies have provided specific guidance for urban vegetation planning adapting to different climate zones on a global scale. In this study, a cooling effect framework was employed to analyze the influence of UGS patch characteristics, natural and anthropogenic factors on its cooling effect across different climatic zones. We found that the urban cooling islands (UCI) intensity, extent, and gradient of UGS increased with latitude, with lower cooling effect concentrated in arid zones around 30 °N, while the largest (0.38 ha) and smallest (0.24 ha) threshold value of efficiency (TVoE) were found in the temperate and arid climate zones. The larger the UGS area, the better the cooling effect in all climate zones. Moreover, complex shapes have a greater UCI intensity in tropical and temperate zones than other regions, while the normalized difference vegetation index (NDVI) has a stronger effect in arid zones. In the continental zone, patch characteristics had little effect. The overall explanation rate of natural and anthropogenic factors on the cooling effect of UGS was 53.5 %, among which natural factors were approximately twice that of anthropogenic factors. Notably, natural factors dominated in the tropical and arid zones affecting UCI, and anthropogenic factors dominated in the temperate and continental zones. The findings of this study expand our understanding of the cooling effect of UGS in different climatic zones around the world and provide insights for urban sustainable development. [Display omitted] • The distribution of cooling effect of urban green space in different climate was identified at global scale. • The different driving factors and mechanisms of urban green space cooling effect are revealed in different climatic regions. • The implication were suggested for climate adaption planning in different climate zones cities [ABSTRACT FROM AUTHOR]

Urban residents are gradually being exposed to increasing urban high temperatures and extreme heatwave events under rapid urbanization and global warming. Although there is an increase in air and surface temperatures observed, spatiotemporal changes in urban human thermal comfort and their drivers are rarely considered when assessing the urban thermal environment, especially at a national scale in China. Based on weather stations, we combined daily meteorological data, including air temperature, solar radiation, wind speed, and humidity, to comprehensively assess the annual dynamics of urban thermal comfort and their relationship with rapid urbanization and climate change in 183 Chinese cities from 1990 to 2016. Our results show that urban air temperature and solar radiation have increased, and urban humidity and wind speed have decreased at the national scale. Following these changes, urban residents' thermal comfort is deteriorating, with physiological equivalent temperature and uncomfortable days increasing in 68% and 59% of cities, respectively, during summer in China, predominantly located in temperate monsoon and continental climatic zones. The worsening of urban thermal comfort was largely explained by climate change, and rapid urbanization contributed 10.9% in our study. Climate change (e.g., global warming, precipitation, and wind speed decrease) and rapid urbanization had positive effects (P < 0.05) on the deteriorative urban thermal environment. Our findings could enrich the knowledge on spatiotemporal changes in the urban thermal environment under climate change and rapid urbanization. • Urban resident in China suffers from more and more heat stress during the summer period and feel extremely uncomfortable from 1990 to 2016. • The worsening of urban thermal comfort was largely explained by climate change, and rapid urbanization just contributed 10.9% for urban thermal comfort change. [ABSTRACT FROM AUTHOR]

To meet the performance test of the International Thermonuclear Experimental Reactor correction coil conductors, a 50-kA superconducting transformer has been manufactured, which allows rating of test samples under different operating conditions at the Institute of Plasma Physics of the Chinese Academy of Sciences (ASIPP). This transformer system is made up of two concentric layer-wound superconducting solenoids with the primary inside the secondary. The 50-kA secondary winding consists of 4-turn rectangular cable-in-conduit conductor type. This paper describes the design and manufacture techniques of the 50-kA transformer, including a secondary conductor. The secondary terminal design and manufacture are also discussed. Finally, the first test results of the 50-kA transformer are presented. [ABSTRACT FROM AUTHOR]