Search

Considering the problems that quantitative analysis and optimization of the geometrical model of scroll compressor created from involute of circle with variable radii are incomplete, the changing trend of the working chamber volume from the beginning of the suction process to the end of the discharge process is given. The volume calculation differences of Green’s theorem method, the graphical method, and the normal isometric method are compared, the reasons for calculation errors are analyzed, and the correctness of the geometrical model is verified. The calculation formula of teeth area utilization rate is deduced, and the sensitivity models of suction volume and teeth area utilization rate are constructed. It is concluded that the influence of the base circle radius variation coefficient and the occurrence angle of the inner profile are particularly significant. A multi-objective optimization analysis model considering nonlinear constraints and taking the suction volume and teeth area utilization rate as the optimization goals is established. The results show that the multi-objective genetic algorithm NSGA-II has a better comprehensive performance than the multi-objective particle swarm algorithm MOPSO and the suction volume of the scroll compressor created from the involute of circle with variable radii for an automobile air conditioner has been increased by 6.5% and the teeth area utilization rate has been reduced by 4.27%. This paper can provide further theoretical reference for the optimal design and quantitative research of the scroll compressor constructed from involute of circle with variable radii.

Current mobility trend indicates that the number of private cars will decline in the near future. One of the reasons for this trend is the development of Mobility as a Service (MaaS), which in conjunction with information and communication technologies (ICT) drive the application of transport services in smart city, respond to environmental issues, and provide users with reliable mobility. Electric vehicle sharing (EVS) travel has been regarded as a feasible mainstream model of sustainable mobility services in the future, which can effectively improve the utilization rate of motor vehicles, solve the problems of traffic congestion, environmental pollution and urban land, and promote low-carbon and sustainable development. To help electric vehicle operators improve service quality, the establishment of EVS program service performance evaluation is an urgent problem to be solved. Based on this, this paper firstly constructs the evaluation index system from 5 aspects: electric vehicle, charge station, user experience, payment and intelligent services through literature review and Delphi method. Secondly, the criteria importance though intercriteria correlation (CRITIC) and the improved G1 method are introduced to overcome the shortcomings of the single method, and the combined weights are calculated by the multiplication normalization method. Finally, a decision model based on intuitionistic fuzzy soft set (IFSS)-prospect theory and VIse Kriterijumski Optimizacioni Racun (VIKOR) method is constructed to select the best service performance of EVS program, and its feasibility and effectiveness are verified by sensitivity analysis and comparative analysis. The result shows that EVCARD is the best performing EVS program, and shared electric vehicle and charge station are the key factors to be considered in the selection. This study provides scientific and feasible guidance for the optimal service performance selection of EVS programs, which is of great significance for users to choose EVS programs. [ABSTRACT FROM AUTHOR]

Understanding the temporal and spatial variations in the ideal inert tracer helium can provide insight into the dynamic evolution of the thermosphere. The magnitude of the thermospheric winter helium bulge was inversely correlated with the level of solar activity. However, this feature has been found to be not reproduced by the Thermosphere‐Ionosphere Electrodynamic General Circulation Model (TIEGCM), and the associated physical mechanisms remain unknown. Using the Thermosphere‐Ionosphere‐Mesosphere Electrodynamic General Circulation Model (TIME‐GCM), we found that mesospheric gravity wave drag (GWD) is a factor contributing to this inverse correlation. Specifically, the summer‐to‐winter circulation in thermosphere becomes the main cause of the helium bulge, as mesospheric GWD can play a role in strengthening this circulation. The GWD contributions to temperature change below the lower thermosphere do not depend prominently on solar activity. However, because the temperature impacts on the pressure gradient force are height‐integrated according to the background temperature of the neutral gas, the higher background temperature in the thermosphere at the solar maximum corresponds to a relatively weaker response in pressure gradient force in the thermosphere. Therefore, the response of the thermospheric circulation that might be expected to accompany increasing solar activity is suppressed due to the influence of mesospheric GWD, which results in a decrease in the magnitude of the winter helium bulge with increasing solar activity. Thus, our results demonstrated that lower atmosphere forcing can play a significant role in the response of thermospheric helium to solar activity. Plain Language Summary: A winter helium bulge is a phenomenon in which the density of helium in the winter thermosphere is greater than that in the summer thermosphere by 1–2 orders of magnitude. This bulge is closely related to the large‐scale summer‐to‐winter circulation in the thermosphere. Interestingly, the magnitude of the winter helium bulge is inversely related to the level of solar activity. However, the associated physical mechanisms remain unknown. In this study, we focused on the influence of mesospheric gravity wave drag on the solar cycle variation associated with thermospheric winter helium bulges. We found that mesospheric gravity wave drag can play a role in suppressing the enhancement of thermospheric circulation with increasing solar activity. Thus, this factor can lead to an inverse correlation of the thermospheric winter helium bulge with solar activity. Our simulation results indicate that lower atmosphere forcing may play a significant role in the response of thermospheric helium to changes in solar activity. Key Points: Mesospheric gravity wave drag (GWD) contributes to the inverse correlation between the thermospheric helium bulge and solar activityThe relative influence of mesospheric GWD on thermospheric circulation depends on solar activityThe variation in the winter helium bulge depends on both the circulation in the thermosphere and the lateral transport in the exosphere [ABSTRACT FROM AUTHOR]

Temperature is one of the key environmental factors influencing crop fertility and yield. Understanding how plants sense and respond to temperature changes is, therefore, crucial for improving agricultural production. In this study, we characterized a temperature-sensitive male sterile mutant in rice (Oryza sativa), glutamyl-tRNA synthetase 1-2 (ers1-2), that shows reduced fertility at high temperatures and restored fertility at low temperatures. Mutation of ERS1 resulted in severely delayed pollen development and meiotic progression at high temperatures, eventually leading to male sterility. Moreover, meiosis-specific events, including synapsis and crossover formation, were also delayed in ers1-2 compared with the wild type. However, these defects were all mitigated by growing ers1-2 at low temperatures. Transcriptome analysis and measurement of ascorbate, glutathione, and hydrogen peroxide (H2O2) contents revealed that the delayed meiotic progression and male sterility in ers1-2 were strongly associated with changes in reactive oxygen species (ROS) homeostasis. At high temperatures, ers1-2 exhibited decreased accumulation of ROS scavengers and overaccumulation of ROS. In contrast, at low temperatures, the antioxidant system of ROS was more active, and ROS contents were lower. These data suggest that ROS homeostasis in ers1-2 is disrupted at high temperatures but restored at low temperatures. We speculate that ERS1 dysfunction leads to changes in ROS homeostasis under different conditions, resulting in delayed or rescued meiotic progression and thermosensitive male fertility. ers1-2 may hold great potential as a thermosensitive material for crop heterosis breeding. Mutation of a glutamyl-tRNA synthetase leads to changes in ROS accumulation, resulting in thermosensitive meiotic progression and male sterility in rice. [ABSTRACT FROM AUTHOR]