Subjects: Physics >> Nuclear Physics submitted time 2024-03-28
Abstract： Charge exchange reactions with the intermediate energy can be used to study the complex structure of atomic nuclei from the respect of spin-isospin excitation. By utilizing the radioactive beam line at the Institute of Modern Physics, Chinese Academy of Sciences, charge exchange reaction experiments in inverse kinematics can expand the target nuclides to be studied to neutron-rich nuclei and even unstable nuclei. Based on this, a detector system for charge exchange reaction experiments has been designed, which mainly consists of a 3He gas target, TPC and CsI(Tl) arrays, where the TPC and CsI(Tl) arrays form a ΔE-E system. Using simulation software such as Geant4 and Garfield++, the operating conditions of the TPC were optimized, the kinematic intervals and the basic design of the detector for the experimental study were determined, and the particle discrimination ability of the detection system was investigated. Based on the simulation, the detection system was built.
Subjects: Nuclear Science and Technology >> Nuclear Instrument and Meter submitted time 2024-01-15
Abstract： With the development of domestic semiconductor enterprise technology, some domestic components performance indicators have been comparable to imported components, to meet the performance needs of nuclear radiation monitoring instrumentation. A fully localized 𝛾 energy spectrometer based on a 1.5-inch LaBr3 scintillator, including scintillators, photomultiplier tubes, and electronic components, has been designed by using products of domestic manufacturers.The test results show that the resolution of the spectrometer can reach 2.8%@662keV at room temperature, the working temperature range can reach -40℃ to 50℃ , and the energy resolution is better than 3.0% in the whole temperature range, and the change rate of the all-around peak channel address of 137Cs with temperature is about -0.67/℃
, and the linearity is good. The high-voltage adjustment rate is 0.02V, which meets the requirement of 0.2V /℃ for the stable spectrum. The energy nonlinearity of the spectrometer is better than 0.01%. The experimental data show that the domestic LaBr3 scintillator, photomultiplier tube and electronic components can meet the design requirements of 𝛾 energy spectrometer.
Subjects: Statistics >> Social Statistics submitted time 2023-12-03 Cooperative journals: 《中国科学院院刊》
Abstract： By studying the technological innovation and industrial development process of semiconductor, digital computer and radio, this study analyzes the path, conditions and force of science-based technological innovation and its industrialization, establishes a chain reaction model of large-scale technological innovation and diffusion, and compares it with market-based technological innovation. It is found that the large-scale aggregation of scientific research institutions and industrial laboratories accelerates the speed of technological innovation, and diffuses along two paths of scientific research institutions to enterprises and enterprises to enterprises, forming a chain reaction of large-scale technological innovation. Strategic demand is the basic driving force for the establishment of technology-based industries, and the major scientific project creates critical conditions for the chain reaction. The total amount of regional resources and talents is the boundary condition of the innovation scale, and market demand is the basic driving force for the large-scale and leading technology industry. The research conclusion further improves the theory of industry-university collaborative innovation, which has important enlightening significance for China’s current scientific and technological innovation and industrial upgrading.
Subjects: Library Science，Information Science >> Information Science submitted time 2023-04-01 Cooperative journals: 《图书情报工作》
Abstract： [Purpose/significance] This study summarized the experience of International Image Interoperability Framework (IIIF) practical situation in university libraries abroad, aiming at providing reference for how to use IIIF to construct digital collections in the university libraries.[Method/process] We have investigated dozens of university libraries which are members of IIIF Consortium, and have summarized how to apply IIIF in university libraries from six aspects:origin of image, image viewer and image server, platform function, technical parameters, project basis and responsible department.[Result/conclusion] University libraries should apply IIIF in the digital collections in a variety of ways, such as focusing on the open sharing of collections, based on projects and technology, choosing appropriate IIIF tools according to image content and user experience, tracking the development of IIIF, taking advantage of community resources to help digital humanists and so on.
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2022-05-18 Cooperative journals: 《计算机应用研究》
Abstract： Aiming at the problems of long time delay and high computation cost of using complex bilinear mapping in the current LEO satellite network authentication scheme, this paper proposed an efficient certificateless authentication scheme based on the Gayathri’s certificateless authentication scheme. This scheme unifies the user's public key and real identity, so that need not the third party to participate in the authentication process and reduce the authentication delay; uses a small number of point multiplication and point addition operations on the elliptic curve to construct the authentication message, which does not involve the bilinear mapping and reduces the computation cost. Then this paper proves the authentication scheme’s security based on the assumption of elliptic curve discrete mathematics under the random oracle model. Finally, through experimental simulation, comparing with the existing LEO satellite identity authentication schemes, the proposed scheme has lower authentication delay, computational overhead and communication overhead.
Subjects: Astronomy >> Astronomical Instruments and Techniques submitted time 2022-03-15
Abstract：
High energy gamma-rays carry the fundamental information of the astrophysical sources in extreme conditions. The space detection of gamma-rays is distinguished by the wide energy range, the observation continuity as well as the high energy resolution. With the experience in constructing and running the DArk Matter Particle Explorer (DAMPE), we propose a new satellite mission——Very Large Area gamma-ray Space Telescope (VLAST). VLAST has an acceptance of ~10 m2·sr at GeV energies and ~ 1 m2·sr at MeV energies. Together with a much better energy resolution, VLAST is expected to increase the sensitivity of Fermi Large Area Telescope by a factor of 10. In this work, the main scientific objectives, the detection principle, the payload and the expected performance of VLAST are introduced.
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Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2019-11-13 Cooperative journals: 《天文研究与技术》
Abstract： 高海拔宇宙线观测站（LHAASO）的核心科学目标是探索高能宇宙线起源以及相关的宇宙演化、高能天体运动和新物理前沿的研究。通过大面积铺设μ子探测器（MD）极大的压低宇宙射线背景，从而提高高能伽马射线探测的灵敏度。作为MD的核心部件之一的光电倍增管（PMT）负责接收水中的切伦科夫光子并将其转换成电信号输出，因此PMT的性能好坏直接影响MD的性能。稻城实验室2%抽样测试结果表明PMT的各性能达到MD的指标要求，与批量测试结果的相对偏差小于2%。
Subjects: Astronomy >> Astrophysical processes submitted time 2019-04-26 Cooperative journals: 《天文研究与技术》
Abstract： 为了测试用于南极CSTAR（Chinese Small Telescope Array）望远镜的CCD（Charge Coupled Device）控制器视频采样电路的性能并对其进行低温可靠性验证，设计了一款基于FPGA的CCD视频波形发生器，它能产生CCD探测器输出的视频波形。上位机通过USB2.0接口与视频波形发生器进行指令通讯，可以改变波形的幅度、周期、上升沿时间以及叠加的噪声。通过设定不同参数的波形输入到CCD控制器的视频采样电路可以在不同温度下对电路的性能进行充分测试，不仅提高了测试效率而且有效地避免了安装CCD测试造成的风险。测试结果表明CCD控制器的视频采样电路性能满足要求并可以在低至-80℃下稳定工作。
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-04-19 Cooperative journals: 《计算机应用研究》
Abstract： For the problems such as the aliasing phenomenon of signal and noise wavelet packet coefficients, threshold function discontinuity at threshold, and constant deviation between original coefficient and estimation coefficient in traditional threshold denoising, this paper proposed an improved wavelet packet threshold denoising algorithm. The algorithm first calculated the Teager energy operator for the wavelet packet coefficients, making the difference between voice and noise coefficients larger, which is favorable for threshold selection. Then, for the problems of pseudo Gibbs effect and constant deviation, this paper proposed an improved threshold function, which not only overcomes the problem of discontinuity and constant deviation of commonly used functions, but also has superior mathematical characteristics. The experimental results show that the improved algorithm has higher signal-to-noise ratio and reduces the mean square error, which demonstrates the algorithm eliminates the noise to the greatest extent and avoids the signal distortion, and has higher practical value.
Subjects: Medicine, Pharmacy >> Preclinical Medicine submitted time 2017-12-27 Cooperative journals: 《南方医科大学学报》
Abstract： Objective To explore the association between preoperative platelet count and the outcomes of patients with colorectal cancer (CRC). Methods This study was conducted among a cohort of 486 CRC patients, who underwent surgery in Sichuan Provincial Cancer Hospital between January, 2010 and July, 2013 and were prospectively followed up for their outcomes. The association between preoperative platelet counts and clinicopathologic factors of the patients were analyzed. Survival analysis of the patients was performed using log-rank test, and the factors affecting the patients' outcomes were analyzed by univariate and multivariate analyses using the Cox proportional hazard model. Results In this cohort, preoperative platelet count was significantly associated with the tumor site, depth of tumor invasion (T), and distant metastasis (M) (all P<0.05). Log-rank tests showed that in patients with CRC and rectal cancer, the overall postoperative survival differed significantly between high and low preoperative platelet count groups (χ2=8.813, P=0.003 and χ2=5.110, P= 0.024, respectively), but this difference was not observed in patients with colon cancer (P<0.05). Multivariate analysis indicated that CRC patients with a high preoperative platelet count had a higher risk of death compared to those with a low platelet level after adjustment for tumor site, tumor grade, TNM stage, vascular invasion, perineural invasion, and preoperative CEA level (RR=1.814, 95% CI: 1.056-3.115). In subgroup analysis, preoperative platelet count was identified as an independent prognostic factor in patients with rectal cancer (RR=2.718, 95% CI: 1.132-6.526), but not in patients with colon cancer (RR=1.396, 95%CI: 0.705-2.765). Conclusion As an independent prognostic factor in CRC patients, preoperative platelet count may serve as an important indicator for predicting the outcomes of rectal cancer, but its prognostic value for colon cancer needs further clarification.
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