The Solar Upper Transition Region Imager (SUTRI) is an extreme ultraviolet solar imaging telescope that focuses on dynamically observing the solar transition region within a narrow band at 46.5nm. This paper describes the optical parameters, optomechanical structural design, finite element simulation, and on-ground environmental testing. To satisfy the narrow band requirement, the telescope employs multilayers coated on Ritchey-Chrétien optics and filters mounted at the front aperture and ahead of the focal plane. The primary and secondary mirrors are glued to invar frames that provide peripheral support. The telescope contains three mechanisms, which are a focus mechanism, a filter wheel, and a front door. In addition, this paper carried out finite element simulation of modal analysis, optical performance and structural strength. These simulations verified that the opto-mechanical system design is feasible. Finally, the telescope successfully underwent a series of on-ground environmental testing and was subsequently launched carried by SATech-01 satellite in July 2022.
With the deepening process of higher education reform,the economic activities in universities become increasingly diverse and complex,university have gained a new understanding of internal control demand,they are establishing and perfecting systems of internal control,strengthening internal control management to ensure that higher education have a rapid and healthy development.In this paper we analyzed the internal control problems and their causes exist in Chinese Universities,proposed some specific methods to strengthen internal control management of Universities,in order to upgrade the level of university management.
To promote a more reasonable allocation of global forestry resources, this study used the complex networks method to analyze the node characteristics, overall network characteristics, and group changes in the global wood forest products trade network based on trade data from 1995 to 2020, and to study the evolution of the trade network. The results show that the trade relationship between countries is deepening. Compared with resource-based primary wood forest products, the trade of deeply processed wood forest products is larger in scale, more complex in structure, and more closely linked. With changes in world forestry development goals and national forestry policies, trade relationships for deeply processed wood forest products have changed markedly. The core countries in global wood forest products trade mainly comprise North American and European countries, but several developing countries in Asia with abundant forest and labor endowments are gradually joining the core tier and jointly control the trade market.
The IGBT module is characterized as a multi-layer composite structure. Due to the large difference in the coefficients of thermal expansion among the materials in the module, different structures have distinctive thermal expansion and cooling shrinkage in the process of intense temperature change during the packaging process, resulting in internal stress in the module and warpage of the baseplate. The warpage of the baseplate will not only detrimentally reduce the heat dissipation efficiency of the module, but also render the ceramic of the substrate to bear greater stress and cause brittle fracture of the ceramic. In this paper, the warpage of baseplate in the packaging process is positively designed from the point of view of overall structural design.. Firstly, the combination of material and structural parameters that minimize the baseplate deformation is obtained through simulation. Then, reverse deformation is pre-set for the raw material of the baseplate, so as to compensate the deformation of the baseplate during the packaging process, and further reduce the warpage value of baseplate in the finished module. Through the forward design of the baseplate warpage, the baseplate deformation in the packaging process is effectively reducedand the baseplate warpage value of the finished module is minimized, which plays an important guiding role in the development of IGBT module.
An off-axis rotation absolute measurement method by regarding random shift-rotation movement as off-axis rotation is proposed. The off-axis rotation center is calculated by matching feature points on the measured surface. Then the surface profile is calculated relying on Zernike polynomial fitting. Multiple rotations are carried out to reduce symmetrical and environment errors. N(N-1)/2 results can be collected after N times rotation. Compared to traditional methods, this method can obtain accurate results with high efficiency and does not need high precision positioning.
The Solar Upper Transition Region Imager (SUTRI) onboard the Space Advanced Technology demonstration satellite (SATech-01), which was launched to a sun-synchronous orbit at a height of 500 km in July 2022, aims to test the on-orbit performance of our newly developed Sc-Si multi-layer reflecting mirror and the 2kx2k EUV CMOS imaging camera and to take full-disk solar images at the Ne VII 46.5 nm spectral line with a filter width of 3 nm. SUTRI employs a Ritchey-Chretien optical system with an aperture of 18 cm. The on-orbit observations show that SUTRI images have a field of view of 41.6'x41.6' and a moderate spatial resolution of 8" without an image stabilization system. The normal cadence of SUTRI images is 30 s and the solar observation time is about 16 hours each day because the earth eclipse time accounts for about 1/3 of SATech-01's orbit period. Approximately 15 GB data is acquired each day and made available online after processing. SUTRI images are valuable as the Ne VII 46.5 nm line is formed at a temperature regime of 0.5 MK in the solar atmosphere, which has rarely been sampled by existing solar imagers. SUTRI observations will establish connections between structures in the lower solar atmosphere and corona, and advance our understanding of various types of solar activity such as flares, filament eruptions, coronal jets and coronal mass ejections.
Abstract This paper describes a fabrication process for the hyperboloidal concave mirror of a 46.5 nm telescope. The 180 mm aperture hyperboloidal concave mirror and 70 mm aperture compensator are machined directly from chemical mechanical polishing of a spherical surface to a high-accuracy aspherical surface by ion beam figuring. The aspherical measurement method is the Dall null test. To minimize system errors in the measurement process, the rotational measurement method with six rotations is used in the null test. The results of the analysis for the ME (first solve the machined surface profile, then solve the system errors) and EM (first solve the system errors, then solve the machined surface profile) methods of calculation in the measurement are given. The ME method is a more accurate rotational test method, and the six rotations are appropriate for rotational measurements. After the figuring process, the hyperboloidal concave mirror surface profile reached 8.27 nm rms and the compensator surface profile is approximately 4 nm rms. The roughness of the hyperboloidal concave mirror is smooth to 0.160 nm rms.
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