光学微盘腔与三能级量子点系统中的模耦合研究

用一种全量子理论方法研究了波导、光学微盘腔与三能级量子点耦合系统的动力学过程,求出其耦合后的透射模和反射模的解析解. 由于微腔表面粗糙引起反向散射,在微腔内形成两简并回音壁耦合共振模,其耦合率为β;量子点的两激发态分别以耦合率g₁,g₂与回音壁耦合共振模产生耦合. 在实数空间里,得出透射光谱和反射光谱的数值解,这些三能级模型结果比二能级模型结果更接近真实光学微盘腔系统,能更好地显示耦合系统的动力学特性.     

高效异质结构四波长波分复用器的设计与优化

将两光子晶体单模波导平行、邻近放置构成一个光子晶体波导耦合结构.根据耦合和解耦合理论,设计了一种新型的高效异质结构四波长波分复用器.应用时域有限差分法模拟了该器件的效率,并通过改变一排介质柱的折射率,实现了较高的透射率.进一步发现在入射口处添加三对介质柱,可以有效地降低系统的反射,实现了四个波长的高效传输,四个波长的透射率均超过了90%.该器件不仅具有较高的透射率,而且其尺寸仅为36 μm×17 μm,在未来的光子集成回路中具有潜在的应用价值.     

二维链间扩展的极化子动力学研究

基于扩展的SSH模型,研究了有序耦合聚合物链系统中的极化子动力学,包括极化子的形成过程及其在外场下的输运.发现,当聚合物链间的耦合较强时,注入到系统中的电子会诱发二维链间扩展的极化子态,分布在多条聚合物链上.另外,动力学模拟表明,与一维链内定域极化子相比,在相同的电场强度下二维极化子具有更大的运动速度,这与实验结果一致.     

Ga和Sb纳米线声子结构和电子-声子相互作用的第一性原理研究

基于密度泛函理论的第一性原理方法,系统研究了Ga和Sb纳米线的电子能带结构和声子结构以及电子-声子耦合(EPC)作用.通过对声子的完整Brillouin区分析来研究纳米线的结构稳定性.结果表明,所考察的纳米线显示出不稳定性,不稳定声子波矢远离Brillouin区中心.与通常的Peierls变形机理相比,不稳定的横向声子模会导致一种无开口带隙的相变.Sb比Ga纳米线的EPC要强很多,并且横向变形导致的锯齿形结构使纳米线中的电子-声子相互作用增加了几个数量级.     

Exact solution of entanglement of the double Jaynes—Cummings model without rotating wave approximation

This paper investigates the influences of atom--field coupling and dipole--dipole coupling for atoms on the entanglement between two atoms by means of concurrence. The results show that the sudden death occurs when the atom--field coupling is strong enough, and the collapse and the revival appear when the dipole--dipole interaction is strong enough.     

Control of Aptian palaeobathymetry on turbidite distribution in the Buchan Graben,Outer Moray Firth,Central North Sea

It is widely recognised that palaeobathymetry is a key control on the distribution of turbidite deposits. Thus, the utilisation of palaeobathymetric surfaces as an input for numerical turbidity current modelling offers a potentially powerful method to predict the distribution of deep marine sands in ancient (subsurface or outcrop) successions. Such an approach has been tested on an Aptian turbidite deposit from the Buchan Graben, UK Central North Sea, where modelled sand distributions could be quality controlled against available well data.     

Sustainable development: Social outcomes of structural adjustments in a South Australian fishery

The assessment of sustainable development is a relatively recent advent in policy and the evaluation of industry structural adjustments. Although the elements of economic and environmental assessment have been relatively well developed and accepted, the effective inclusion of ‘social’ aspects in assessments of sustainable development are still being grappled with.     

辽宁省城市人居环境系统耦合协调度时空格局演变及驱动力研究

人居环境系统内部的耦合协调是保证人居环境均衡发展的基础。基于“人类-居住-支撑-自然-社会”5个子系统,构建人居环境系统耦合协调发展评价指标体系,将2个系统间的容量耦合模型扩展运用到人居环境5个子系统中,综合熵值法、GIS空间分析以及地理探测器对辽宁省2005~2016年人居环境系统耦合协调度的时空演化特征与驱动力进行探讨,阐述人居环境系统内部协调性。研究表明:①2005~2016年辽宁省人居环境系统内部的耦合度与耦合协调度整体呈缓慢浮动上升趋势;②辽宁省人居环境耦合协调度呈分散格局,并且呈现从中间向两侧递减的“屋脊”式格局和“双核结构”;东西方向上,空间演变趋势由倒U型逐渐向一字型演变,南北方向上由斜线型向“L”型演变。③全省出现了中耦合低协调区、中耦合过渡协调区、高耦合低协调区、高耦合过渡协调区、高耦合高协调区5种类型区。④空间分异驱动力主要包括人的需求、经济发展、住房、互联网发展等。     

Application of an ecosystem model for the environmental assessment of the reclamation and mitigation plans for seagrass beds in Atsumi Bay

An ecosystem model was used to evaluate the effects of reclaiming seagrass beds and creating artificial shallows with seagrass beds to mitigate the effects of the reclamation. The applied model can simulate the pelagic and benthic ecosystems including seagrass beds and tidal flats. The objectives of this study were (a) to investigate the likelihood of cultivating and maintaining seagrass beds in artificial shallows (Part 1), and (b) to understand the effects of the reclamation of seagrass beds and the creation of artificial shallows on the water quality in the estuary (Part 2). In Part 1, first, the nutrient turnover rates due to both biochemical and physical processes in the natural seagrass beds where reclamation is proposed were analyzed. Biological processes rather than physical processes were the most significant driving forces of nutrient cycles in seagrass beds. Second, the effects of filter feeding benthic fauna (suspension feeders) in the seagrass beds were analyzed. The scenario with suspension feeders resulted in higher transparency of the water column (8.7% decrease in the light attenuation coefficient) and an increase in nutrient supply (24.9% increase in NH₄-N in the water column) contributing to the high specific growth rate of seagrass. Third, the specific growth rate of seagrass on the proposed artificial shallows was measured. The value on the artificial shallows set at a depth of datum line minus 0.8 m (D.L. − 0.8 m) was approximately the same as that of the natural seagrass beds. In Part 2, first, water quality in the estuary was compared among the scenarios with/without natural seagrass beds and artificial shallows. Then, the defined values of the water purification capability of (a) artificial shallows with/without seagrass beds, and (b) natural seagrass beds per unit area were evaluated. The reclamation of the natural seagrass beds resulted in a decrease of the removal of phytoplankton and detritus from the pelagic system (i.e. resulted in a loss in the purification rate). In contrast, the creation of artificial shallows resulted in an increase of the removal of phytoplankton and detritus from the pelagic system (i.e. resulted in a gain in the purification rate). Based on an annual average, approximately twice as much phytoplankton was removed from the artificial shallows at the depth D.L. − 0.8 m, than at the depth, D.L. − 1.5 m, and the artificial shallows with seagrass beds removed pelagic DIN and DIP at a rate 120% higher than that without seagrass beds.     

多模式控制在关联系统中的应用研究

根据多模式控制器的设计理论,以偏差分段为基础,将控制过程分为几个阶段,用不同的模式加以控制,用加速储能控制来解决响应快速性的要求;用快速放能控制来解决响应平稳性要求;用稳态能量控制来解决系统的准确性要求。把控制模式用于双输入双输出关联系统的解耦系统中进行了仿真研究,与常规控制方法做了比较,多模式控制在关联系统中具有良好的动态响应性能。