Subjects: Physics >> Nuclear Physics submitted time 2024-01-17
Abstract： The research in hypernuclear physics provides crucial information for uncovering the characteristics of baryon-baryon interactions in the nuclear medium and understanding the internal structure of atomic nuclei and neutron stars. Based on the density-dependent relativistic Hartree-Fock (RHF) theory, the $ Lambda N$ effective interaction in the model is obtained by fitting experimental data of hyperon separation energies for single-$ Lambda$ hypernuclei. The inclusion of the Fock term alters the dynamic equilibrium of the effective nuclear force in the hyperon channel, resulting in a meson-hyperon coupling strength that differs from the relativistic mean-field model and influences the description of hyperon spin-orbit splitting. Considering the uncertainty in the values of the effective nuclear force within the model, further research is conducted to explore the dependence of hypernuclear bulk and single-particle properties on the hyperon coupling strength, aiming to identify possible ways to constrain its range of values. Taking the $^{16}_{ Lambda}$O hypernucleus as an example, the effects of the nuclear medium and Fock terms are systematically analyzed by adjusting the hyperon coupling strength in the isoscalar channel within the hypernuclear energy functional. The results suggest a possible linear relationship between the ratio of hyperon coupling strength and quantities such as hyperon spin-orbit splitting, Dirac effective mass, and hypernuclear characteristic radius. Therefore, by constraining these quantities through experimental or theoretical means, it is possible to impose stronger limitations on the effective nuclear force associated with hyperons in the nuclear medium.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： The Tibetan Plateau and surrounding mountains contain the largest glacier storage outsides the north and south polar regions. Under the global warming, recently glaciers in China are generally experiencing rapid melting and shrinkage. This rapid glacier change impacts the water resource that supplied by melt-water, and also favors glacial hazards, such as glacier collapse, glacier surging, glacial debris flow, and glacial lake outburst flood. Those glacial hazards show their spatio-temporal distribution characters, dynamic processes and mechanisms. Accompanying with the recent rapid glacier change, which reduces the glacier stability by warming, glacial hazards become more frequent. Furthermore, since global warming continues and human activity intensifies, the uncertainty and risk of glacial disasters will intensify. Therefore, scientific solution and countermeasures are needed based on the researches on glacial changes and hazards.
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2020-09-28 Cooperative journals: 《计算机应用研究》
Abstract： To improve the performance of multi-accent Mandarin speech recognition task, this paper present a method for hybrid end-to-end automatic speech recognition(ASR) by combining Connectionist Temporal Classification (CTC) and MutiHead Attention by using a multiobjective training and joint decoding. Our analysis shows that hybrid model with lower CTC weight and deeper encoder layers performance better learning capacity. And we trained a very deep models with up to 48 layers for encode-decoder Architecture, which outperform all previous end-to-end ASR approaches on Aidatatang 200h multi-accent dataset, achieve 5.6% Character Error Rate(CER) and 26.2% Sentence Error Rate(SER) . The experiment proves that the recognition rate of the end-to-end model proposed in this paper exceeds the general end-to-end model, and it has certain advancedness in solving the Mandarin recognition with accents.
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2017-09-20 Cooperative journals: 《中国科学院院刊》
Abstract：西风与印度季风两大环流是控制青藏高原气候与环境变化的决定性因素。研究显示两大环流的影响范围和程度具有明显的空间分异：基于降水稳定同位素实测与模型模拟发现青藏高原现代西风与印度季风的相互作用特征表现为3种模态，即印度季风模态、西风模态和过渡模态。基于湖泊沉积记录的分析，发现3种模态主控范围在历史时期不断发生变化。3种模态对现代青藏高原环境产生连锁式环境效应，使得该区的冰川、湖泊、生态系统变化具有明显的区域特征，具体表现为印度季风模态的冰川强烈退缩，湖泊趋于萎缩；西风模态的冰川趋于稳定甚至部分出现前进，湖泊趋于扩张；过渡模态的冰川退缩程度减弱，湖泊变化不明显。西风模态的植被返青期提前，印度季风模态的植被返青期推后，而过渡模态的植被过程比较复杂。
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