Subjects: Geosciences >> Space Physics Subjects: Physics >> Geophysics, Astronomy, and Astrophysics Subjects: Astronomy >> Galaxy and Cosmology submitted time 2024-06-02
JI Jianghui
LI Haitao
ZHANG Junbo
LI Dong
FANG Liang
WANG Su
DENG Lei
CHEN Guo
LI Fei
DONG Yao
LI Baoquan
GAO Xiaodong
XIAN Hao
Abstract： The Closeby Habitable Exoplanet Survey (CHES) employs state-of-the-art, high-precision astrometry and positioning technology at the microarcsecond level in space. Its primary objective is to conduct a thorough survey of approximately 100 FGK-type stars within the Sun’s proximity (within 10 parsecs), with the goal of detecting potentially habitable Earth-like planets or super-Earths. This pioneering mission involves a detailed census of habitable planets, providing intricate information on their numbers, true masses, and three-dimensional orbits. Notably, CHES marks a historic milestone as the inaugural international space exploration mission exclusively dedicated to the study of terrestrial planets within the nearby habitable zone. CHES’s payload features a cutting-edge optical telescope with a 1.2 m aperture, a field of view measuring 0.44°×0.44°, and a focal length of 36 m. The telescope utilizes a coaxial three-mirror TMA optical imaging system. Impressively, CHES is designed with a positioning measurement accuracy of 1 μas, solidifying its status as the most precise space exploration project globally in terms of positioning accuracy. To achieve the detection objectives of CHES, it is essential to refine and further substantiate the scientific goals through comprehensive argumentation. Overcoming three key technological challenges is crucial: advancing optical systems for large field of view, developing high-quality space telescopes with minimal distortion; breaking through measurement technology for stellar separations at the 10–5 pixel level; and achieving high stability in satellite system attitude control and thermal control precision. CHES stands on the threshold of groundbreaking discoveries, with the exciting prospect of revealing 50 Earth-like planets. This announces a significant leap forward in China’s space science exploration technology.
Subjects: Mechanics >> Applied Mechanics submitted time 2023-03-20 Cooperative journals: 《应用力学学报》
Abstract： In order to improve the energy harvesting efficiency of the energy harvesting system at low windspeed range , a nonlinear dynamic magnet is introduced into the galloping energy harvesting system.A pairof magnets with opposite magnetic poles are installed at the end of the cantilever beam and the fixture,respectively.A dynamic magnet is connected to the base through a spring and it can move vertically withthe change of the magnetic repulsion force. Firstly , based on the energy method , the multi-field coupledvibration governing equation of dynamic magnetically coupled galloping energy harvesting system ( DM-GEH) is established. Next , the voltage outputs of the DM-GEH and the fixed magnetically coupled gallo-ping energy harvesting system ( FM-GEH ) under low wind speed are compared and analyzed by theRunge-Kutta method.Compared to the that of FM-CEH, the cut-in wind speed of the DM-GEH system is reduced by 81.82% , and the energy harvesting efficiency is increased by 124.22% in the wind speedrange of 1 m/s-5 m/s.Finally , the parameter of the spring support stiffness is optimized to improve theenergy harvesting eficiency at low wind speed. By changing the stiffness of elastic support , the vibrationfrequency will be varied and the cut-in wind speed of the system will be reduced.Compared to that of theDM-GEH with the spring stiffness of 1 000 N/m, the cut-in wind speed of the DM-CEH with the springstiffness of 500 N/m will be reduced by 54.55% , and the energy harvesting efficiency will be increased by15.35%.
Subjects: Biology >> Botany >> Applied botany submitted time 2022-03-18 Cooperative journals: 《广西植物》
Abstract： In order to provide new data for clarification of the generic relationship in Hypoxidacae, morphology, ultrastructure, and anatomy of leaf from five species in Hypoxidaceae were investigated using microscope, scanning electronic microscope (SEM), and paraffin section. It turned out that there were five points of views as below ： (1) Three types of leaf shapes were characterized, including small-even, middle-wave, and large-plicate. (2) Trichomes were single-celled and uniseriate, and grouped into pilose, strigose, and stellate. (3) Shapes of leaf epidermal cells were hexagon and pentagon, while stomata was paracytic and elliptic with a correlation between size and density. (4) Sculptures of wax in epidermis was classified into smooth, granular, scales, and crust. (5) Leaf anatomy revealed two types of vascular bundles and relevence between thickness of epidermis and size of epidermal cells. Based on comparative morphology and anatomy of leaf, it is suggested that complex of some characters would be helpful for understanding of generic relationships in Hypoxis L., Curculigo Gaertn. and Molineria Colla., while other characteristics for species identifications.
Subjects: Biology >> Botany >> Applied botany submitted time 2022-03-18 Cooperative journals: 《广西植物》
Abstract： As a traditional Dai medicine, “Dai-Bai-Jie” is a kind of antidote, and its source plant was firstly recorded as Dregea sinensis. Currently, the source plant has been corrected as Marsdenia tenacissima. In order to further clarify the source plants of “Dai-Bai-Jie”, we carried out an integrated analysis of the source plants of “Dai-Bai-Jie” and its related species in this study. Our key results were as follows: (1) Phylogenetic relationship of Marsdenia and other species of Marsdenieae using three DNA fragments (psbD-trnT, trnL-trnF, ITS) showed that all “Dai-Bai-Jie” samples were supported as monophyletic with the sample of M. tenacissima, and were sister to M. cavaleriei; (2) Comparative analyses of morphological characters with type specimen proved that morphological characters of the “Dai-Bai-Jie” samples were consistent with those of the type specimen of M. tenacissima and obviously different from those of M. cavaleriei. In this study, the source plant of “Dai-Bai-Jie” was identified as the species M. tenacissima. Meanwhile, it is easy to discriminate from M. cavaleriei in the leaf and floral characters. According to both morphological and molecular evidence, it has been confirmed that the source plant of “Dai-Bai-Jie” was M. tenacissima that can be used for rapid and accurate authentication of medicinal herbs in the market, and also benefit for the development and utilization of the “Dai-bai-jie” medicine in future.
Subjects: Management Science >> Management Engineering submitted time 2021-03-03
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