Using restored two-dimensional X-ray images to reconstruct the three-dimensional magnetopause

Astronomical imaging technologies are basic tools for the exploration of the universe,providing basic data for the research of astronomy and space physics.The Soft X-ray Imager(SXI)carried by the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)aims to capture two-dimensional(2-D)images of the Earth’s magnetosheath by using soft X-ray imaging.However,the observed 2-D images are affected by many noise factors,destroying the contained information,which is not conducive to the subsequent reconstruction of the three-dimensional(3-D)structure of the magnetopause.The analysis of SXI-simulated observation images shows that such damage cannot be evaluated with traditional restoration models.This makes it difficult to establish the mapping relationship between SXIsimulated observation images and target images by using mathematical models.We propose an image restoration algorithm for SXIsimulated observation images that can recover large-scale structure information on the magnetosphere.The idea is to train a patch estimator by selecting noise–clean patch pairs with the same distribution through the Classification–Expectation Maximization algorithm to achieve the restoration estimation of the SXI-simulated observation image,whose mapping relationship with the target image is established by the patch estimator.The Classification–Expectation Maximization algorithm is used to select multiple patch clusters with the same distribution and then train different patch estimators so as to improve the accuracy of the estimator.Experimental results showed that our image restoration algorithm is superior to other classical image restoration algorithms in the SXI-simulated observation image restoration task,according to the peak signal-to-noise ratio and structural similarity.The restoration results of SXI-simulated observation images are used in the tangent fitting approach and the computed tomography approach toward magnetospheric reconstruction techniques,significantly improving the reconstruction results.Hence,the proposed technology may be feasible for processing SXI-simulated observation images.

The Structural Responses of Columns under Various Loadings

This paper focuses on the seismic resistance of one-storied factories, which are commonly used in China due to their flexibility, low cost, and short construction period. With the increasing demand for construction materials, these factories play a vital role in meeting the demands of urbanization and infrastructure development. The seismic resistance of these factories is critical to ensure safety, and this paper presents research on this topic. The paper highlights the advantages of one-storied factories, such as low maintenance cost and seismic resistance, and emphasizes the importance of conducting research on their seismic resistance to ensure safety in construction projects.

CHARACTERISTIC FEATURES OF MUELLER MATRIX PATTERNS FOR POLARIZATION SCATTERING MODEL OF BIOLOGICAL TISSUES

We developed a model to describe polarized photon scattering in biological tissues.In this model,tissues are simplified to a mixture of scatterers and surrounding mpdium.There are t wo types ofscatterers in the model:solid spheres and infinitely long solid cylinders.Variables related to thescatterers include:the densities and sizes of the spheres and cylinders,the orientation and angulardistribution of cylinders.Variables related to the surrounding medium include:the refractiveindex,absorption coeficient and birefringence.In this paper,as a development we introduce anoptical activity effct to the model.By comparing experiments and Monte Carlo simulations,we analyze the backscater ing Mueller matrix patterms of several tissue-like media,and summarizethe different effects coming from anisotropic scattering and optical properties.In addition,wepropose a possible method to extract the optical activity values for tissues.Both the experimentaland simulated results show that,by analyzing the Mueller matrix patterns,the microstructureand optical properties of the medium can be obtained.The characteristic features of Muellermatrix patterns are potentilly powerful tools for studying the contrast mechanisms of polari-zation imaging for medical diagnosis.

MRI investigation for low-grade glioma after gamma knife radiosurgery

Objective： To evaluate the therapeutic efficacy of low-grade glioma （WHO grades Ⅰ-Ⅱ） patients treated with gamma knife radiosurgery and study on the efficacy evaluation method and radiobiological effect. Methods： 140 MRI data of 52 patients after gamma knife radiosurgery were analyzed in tumor size, necrosis or cyst formation, radiation-induced edema and MRI contrast enhancement and circumsciption change for therapeutic efficacy was evaluated. Results： The efficiency rate was 84.3%. The salient efficiency rates were 54.3% for total and 30%, 36.4%, 50%, 68%, 69.2%, and 73.1% for segmenting, respectively. Aggrandizement of tumor related to MRI contrast enhancement and necrosis or cyst formation. Radiation-induced oedema occurred for 32.7%. The MRI contrast enhancement occurred for 57.7% and showed special lace-like ring while some piece-like. Conclusion： Evaluation by MRI has showed gamma knife radiosurgery is efficient for low-grade glioma. The segmenting salient efficiency rate that increase with time is better for evaluation than the efficiency rate especially for long-term MRI follow-up. Radiobiological effect affect the efficacy evaluation. MRI contrast enhancement appears after therapy and shows special as lace-like ring and partly minificates or vanishes subsequently.

A Lunar-based Soft X-ray Imager(LSXI)for the Earth's magnetosphere

We propose to use the Moon as a platform to obtain a global view of Earth's magnetosphere by a Lunar-based Soft X-ray Imager(LSXI).LSXI is a wide field-of-view Soft X-ray telescope,which can obtain X-ray images of Earth's magnetosphere based on the solar wind charge exchange(SWCX)X-ray emission.Global perspective is crucial to understand the overall interaction of the solar wind with magnetosphere.LSXI is capable of continuously monitoring the evolution of geospace conditions under the impact of the solar wind by simultaneous observation of the bow shock,magnetosheath,magnetopause and cusps for the first time.This proposal is answering the call for the Chinese Lunar Exploration Program Phase IV.

Deriving the magnetopause position from wide field-of-view soft X-ray imager simulation

Imaging techniques provide essential information in astronomical and space physics studies.The Soft X-ray Imager(SXI)will obtain images of the Earth’s magnetosphere via the solar wind charge exchange process in a global view.However,it is a challenge to reconstruct its 3-D structures from the observed 2-D image(s).In this paper,a recently proposed method,Tangent Fitting Approach(TFA),is validated to reconstruct the large-scale magnetopause from a single X-ray image obtained by instrument simulation.It is revealed that the large-scale magnetopause under a medium solar wind number density can be well reconstructed,although the locations of maximum X-ray photon counts are scattered in the image due to instrumental effects and diffusive sky background.Higher solar wind number density leads to stronger signals and further leads to better reconstruction results.For lower solar wind density,the X-ray maximum photon counts may not be identified from the SXI simulations,preprocessing of the images shall be considered before applying TFA.Furthermore,the subsolar magnetopause can be well derived when the satellite is on the dayside orbits.