Subjects: Physics >> Nuclear Physics submitted time 2024-03-19
Abstract： In heavy ion collisions (HICs), the production of light particles plays an important role in extracting information about the equation of state (EoS) of nuclear matter. Based on the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model, the effect of the sequential decay on the collective flows and the nuclear stopping power of light particles in Au+Au collisions at intermediate energies were investigated, with the statistical decay model GEMINI++ is used to process the secondary decay of the primary fragments. It is found that due to the memory effect and the daughter nuclei produced by decay inherent part of the dynamic information of the parent nucleus, the experimental data can be better described by considering the sequential decay. And the influence of the sequential decay on the observables weakens with the increase of the collision energy. The results highlight that the sequential decay and the production of light particles in HICs have an obvious effect on the observables which sensitive to the EoS, and these effects should be considered when adopting these observables to extract the information of the EoS.
Subjects: Physics >> Nuclear Physics submitted time 2023-12-11
Abstract： Based on the self-consistent RBUU transport theory, the isospin-dependent in-medium $N Delta rightarrow N Delta$ cross section is investigated. It is found that the isospin effect has obvious influence on the effective mass, as well as the total $N Delta$ elastic scattering cross section in different density regions. With the increase of baryon density, the effective mass splitting between different isospin states of baryons increases gradually. Under the joint effect of density-dependent baryon effective mass splitting, coupling constant, as well as Born terms such as $ sigma- delta$, $ sigma- rho$, $ omega- delta$, $ omega- rho$, the elastic cross-sections of sub-channels with different isospin states exhibit different density-dependent behaviors. The total cross-section has an obvious reduction effect of medium in the low-energy region, and the medium effect is weakened in the high-energy region.
Subjects: Physics >> Nuclear Physics submitted time 2023-10-12
Abstract： The investigation of the equation of state (EoS) of nuclear matter, especially at high baryon densities is one of the hot topics in the frontier of nuclear physics. The impact of the EoS at 2-5 times saturation density ρ0 on the two-particle correlation is discussed with the ultra-relativistic quantum molecular dynamics (UrQMD) model. Focusing on the two π Hanbury-Brown-Twiss (HBT) correlations, by adopting different EoSs, the effects of potential interaction and phase transition on the HBT correlation and the spatiotemporal properties of the emission source of π are investigated. The results show that below 4~5 ρ0, the HBT radius and parameters are sensitive to the stiffness of the EoS. By comparing with the experiment data, a phase transition with a significant softening of the equation of state below 4 times nuclear saturation density can be excluded using HBT data, and the available data on the HBT radii in the investigated energy region favor a relatively stiff EoS at low densities, which then turns into a soft EoS at high densities. These results highlight that the pion's HBT radius and parameters are sensitive to the stiffness of the equation of state, and can be used to constrain and understand the equation of state in the high baryon density region.
Subjects: Library Science，Information Science >> Information Science submitted time 2023-04-01 Cooperative journals: 《图书情报工作》
Abstract： [Purpose/significance] Keywords, as a kind of vocabulary or term that can reveal the subject and core content of a text, can identify the functions and provide the underlying index support for fast and accurate acquisition of knowledge and documents.[Method/process] Aiming at the existing studies that are mostly limited to the semantic representation of symbols at the text level in vocabulary context modeling, this paper proposes a lexical function recognition model based on multi-feature fusion. On the basis of capturing the context-dependent features of keywords using the BERT model, the position information of keywords in the keyword list and the full text and prior knowledge of vocabulary functions are fused, and then the attention mechanism and feed-forward neural network are used for the identification of key words by problem-solving method.[Result/conclusion] The experimental results show that both the location information and priori knowledge of the keywords can improve their word function recognition effect, and the prior knowledge has a greater contribution to the recognition effect.
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-06-19 Cooperative journals: 《计算机应用研究》
Abstract： For image distortion classification, this paper proposes an algorithm based on Gabor wavelet and CNN (Convolutional Neural Network) . It uses the good characteristic of Gabor wavelet to extract rough feature of images firstly, and then uses the improved CNN to extract the key feature from rough feature. The main steps include: Images are preprocessed firstly (including labels setting, samples balance and samples expansion) ; Then it calculates eight directions Gabor wavelet to preprocessed images, and then add eight sub-bands to one sample for training; Finally, it uses a self-designed CNN and Softmax classifier to train the final model, and uses the methods of random gradient descent and error back propagation to optimize the parameters of convolution kernels during training. The final model is used to determine the type of image distortion, the classification accuracy on the LIVE standard image library is 95.62%, it shows that the proposed method has high accuracy and robustness.
Subjects: Astronomy >> Astrophysical processes submitted time 2018-05-24 Cooperative journals: 《天文研究与技术》
Abstract： 明安图射电频谱日像仪每天产生海量观测数据，传统的关系型数据库存储和管理这些数据时，面临着读写延迟高、性能和容量扩展能力有限以及可用性弱等诸多问题。针对这些问题，开展了基于NoSQL的海量数据存储与检索应用研究。首先，详细分析了明安图射电频谱日像仪数据特点、存储需要以及面临的问题；然后，对明安图射电频谱日像仪进行数据建模，给出了明安图射电频谱日像仪的列式非关系型数据模型，同时提出了元数据和数据在NoSQL中的同步存储方法，解决了二者的一致性问题，在此基础上实现了基于Cassandra的海量天文数据存储管理系统(MBDMS)，最后通过实验验证了系统存储与检索的高效性、扩展性以及可行性，从结果来看，MBDMS可以很好的满足数据管理需要，是解决当前数据存储问题的一种有效方案。
Subjects: Dynamic and Electric Engineering >> Engineering Thermophysics submitted time 2017-11-07 Cooperative journals: 《工程热物理学报》
Abstract：电厂烟气经SCR脱硝后，产生粘度大、腐蚀性强的硫酸氢钱，造成空预器堵塞和腐蚀，影响机组运行。针对SCR脱硝后回转式空预器运行环境的改变，在已有传热模型研究的基础上，结合回转式空预器的结构特点，提出了一种可用于SCR脱硝后的空预器传热计算模型。考虑SCR脱硝后烟气成分变化以及温度对物性的影响，可准确计算得到SCR脱硝后回转式空预器内部温度场，为电厂配置SCR脱硝装置后回转式空预器的设计和改造提供理论依据。对两分仓和SCR脱硝前后三分仓回转式空预器实例计算以及和现场实验结果比较，表明本文提出的传热计算模型适用面广、计算精度高。
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