Status of the GAMMA-400 Project

The preliminary design of the new space gamma-ray telescope GAMMA-400 for the energy range 100 MeV - 3 TeV is presented. The angular resolution of the instrument, 1-2{\deg} at E{\gamma} ~100 MeV and ~0.01^{\circ} at E{\gamma} > 100 GeV, its energy resolution ~1% at E{\gamma} > 100 GeV, and the proton rejection factor ~10E6 are optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of cosmic-ray electrons, positrons, and nuclei.Comment: 6 pages, 1 figure, 1 table, submitted to Advances in Space Researc

New type of drift tubes for gas-discharge detectors operating in vacuum: Production technology and quality control

A device for fabricating thin-wall (straw) drift tubes using polyethylene terephthalate film 36 μm thick by ultrasonic welding is described together with the technique for controlling their quality. The joint width amounts to 0.4–1.0 mm. The joint breaking strength is 31.9 kg/mm$^{2}$. The argon leakage from a tube of volume 188.6 cm$^{3}$ under a pressure gradient of 1.0 atm does not exceed 0.3 × 10$^{–3}$ cm$^{3}$/min, which is mainly related to the absence of metallization in the joint vicinity. The high strength, the low tensile creep due to the absence of glued layers, the small value of gas leakage makes the new tubes capable of reliable and long-term operation in vacuum, which is confirmed by the operation of 7168 straw tubes for two years in the NA62 experiment

Research on Segmentation of Brain Images Based on Active Contour Models

医学图像分割是计算机技术辅助病理分析和疾病的诊断与治疗的重要基础，是正常组织和病变组织的三维重建研究的重要步骤，是图像分割领域的重点和难点。而脑图像分割是医学图像分割领域中具有代表性的研究领域，具有重要的临床实用价值和学术研究价值。 脑图像分割的主要目的是将脑图像（MR图像，CT图像等）中感兴趣的组织分割出来。脑脊液是脑中的液体环境，对脑具有保护和支持的作用。脑脊液状态的异常是导致脑积水等疾病的原因。因此，从脑图像中分割脑脊液具有重要的意义，是本文关注的重点。本文以活动轮廓模型为基础，研究从脑图像中分割提取脑脊液边界的一系列方法。 本文的主要创新工作如下： 1.针对各种活动轮廓模型的优缺...Medical image segmentation is the important basis of computer technology-assisted pathology analysis and disease diagnosis and treatment. And it is also an important step of the research of three dimensional reconstruction of normal or diseased tissue. Besides, it’s the significant and challenging in image segmentation area. As a representative research branch of medical image segmentation, brain ...学位：工学硕士院系专业：信息科学与技术学院计算机科学系_计算机系统结构学号：2302009115272