Epidemic Dynamics with Feedback Mechanism in Exponential Networks

We introduce a feedback mechanism to study the spreading of an epidemic by analytical methods and large scale simulations in exponential networks. It is found that introducing the feedback mechanism can reduce the density of infected individuals, Furthermore, it does not change the epidemic threshold （critical point） λc. These results can help us to understand epidemic spreading phenomena on social networks more practically and design appropriate strategies to control social infections.     

A Parametric Dynamic Model of Dark Energy

The double complex symmetric gravitational theory is extended to the parametric symmetric gravitational theory by introducing a parameter β. Hence parametric Friedmann-Robertson-Walker equations are obtained and some characters of dark energy in corresponding spaces are discussed by taking different values of β. In our method some previous results can be included as the special case of our results. It is worth noting that some characters of dark energy can be more intuitively described in our model. By analysis, we can predict that the fate of universe would be a Big Rip in the future, and also find that the state parameters for the two different constraint conditions wФ are consistent with the present cosmological observations.     

Study of W-Exchange Mode D0 → ФK0

We calculate the branching ratio of rare decay D^0→ФK using the perturbative QCD factorization approach based on kT factorization. Our result shows this branching ratio is （8.7 ± 1.4） x 10^-3, which is consistent with experimental data. We hope that the CLEO-C and BES-Ⅲ can measure it more accurately, which will help us to understand QCD dynamics and D meson weak decays.     

Entanglement dynamics in two-component Bose--Einstein condensates

Based on the exact solution of the time-dependent Schr\"{o}dinger equation for two-species Bose--Einstein condensates (BECs) consisting of two hyperfine states of the atoms coupled by a tuned adiabatic and time-varying Raman coupling, we obtain analytically the entanglement dynamics of the system with various initial states, particularly the SU(2) coherent state, for both of cases with and without the nonlinear interactions. It is shown that the effect of nonlinear interaction on the entanglement appears only in a longer time period depending on the BEC parameters.     

气溶胶单粒子粒径的实时测量方法研究

介绍了近期研制的一台实时测量大气气溶胶单粒子粒径和化学成分的仪器在如何测量气溶胶单粒子粒径方面的测量原理及特点，并结合激光解吸附电离飞行时间质谱技术，利用该仪器对木屑燃烧产生的烟气气溶胶粒子的实时测量结果. 关键词： 气溶胶粒子 空气动力学粒径测量方法 激光解吸附电离 飞行时间质谱     

表面人工低维结构的功能设计与构造

可控地构造具有一定功能的表面人工低维结构,并且总结、理解体系微观结构对其宏观性质影响的一般规律,不仅对探索低维基本物理以及其中的新奇量子现象至关重要,更是微电子工业保持持续发展的关键前提.这方面的研究包括发展新的生长技术实现对体系形成过程的精确控制,对获得的材料做高分辨率的表征;从理论上则要理解体系的生长过程,阐明热力学、动力学的作用机理,从而指导制备技术的发展.深入研究表面人工低维结构的性质更可能导致新物理现象与原理的发现,产生全新的器件概念,进一步反馈给体系功能的设计,推动基础研究与应用探索的发展.文章简要介绍了表面物理国家重点实验室近年来在表面人工低维结构的功能设计与构造方面的研究成果     

Sigma Meson Production in Nuclear Reactions

The sigma meson production in p ＋ ^12C and p A- ^40Ca reactions at the incident energy Ep = 1.5 GeV is investigated within the Quantum Molecular Dynamics model. The simulation results indicate a distinctive A dependence of the sigma production, that is, the increase of A is followed by an increase of the production cross sections. We find that the σ meson production in proton-induced reactions is strongly medium-dependent, and the produced σ mesons decaying in a denser medium experience a stronger mass shift towards lower masses. This mass shift is an experimentally accessible observable in the final state pion pairs, which do not suffer from reabsorption by the surrounding nucleons. It is pointed out that the ratio of measured sigma cross sections as a function of the sigma invariant-mass from various reactions is a good probe to explore the existence of the σ meson in a dense nuclear environment.     

Synchronization in Coupled Oscillators with Two Coexisting Attractors

Dynamics in coupled Dufling oscillators with two coexisting symmetrical attractors is investigated. For a pair of Dufl~ng oscillators coupled linearly, the transition to the synchronization generally consists of two steps： Firstly, the two oscillators have to jump onto a same attractor, then they reach synchronization similarly to coupled monostable oscillators. The transition scenarios to the synchronization observed are strongly dependent on initial conditions.     

矩阵特征体系与化学动力学参数估计

矩阵的特征系统在线性代数知识体系中作为最重要的一环,在实际教学中却面临学生无法直观体会其价值的困境.面对化学化工专业的线性代数课程教学中,针对矩阵特征体系在化学动力学中的应用,开辟与专业结合的应用专题.其目的在于阐明线性代数作为分析与计算工具的基础作用,同时也实现和专业课程的无缝衔接,以促进学生专业课程的学习.     

石墨毡载纳米δ-MnO2高性能除铵净水材料研究

首先制备了α-MnO₂纳米花簇、β-MnO₂纳米针和δ-MnO₂微米颗粒三种不同晶型的MnO₂粉末材料,对其结构、形貌及吸附除铵能力进行了表征和测试.结果表明,层间距（7.2Å）大于NH₄⁺直径（2.96Å）和水合NH₄⁺直径（6.62Å）的δ-MnO₂相比其他两种晶型的MnO₂有更高的NH₄⁺吸附量;接着研究采用KMnO₄原位氧化还原法在石墨毡（GF）上直接生长超薄δ-MnO₂纳米片（MnO₂NPs）阵列构筑了石墨毡载纳米MnO₂（MnO₂NPs/GF）多级结构材料,制备简单,无须成型造粒就可直接用作除铵净水材料,研究结果表明,MnO₂NPs/GF不仅具有较高的吸附量（15 mg·g^－1）与良好的选择性,同时还展现了优异的快速吸附和稳定的循环使用性能.MnO₂NPs/GF对水中NH₄⁺的吸附符合准二级动力学模型,其吸附等温线符合Langmuir吸附等温式,是吸附-离子交换法除铵的理想材料.