Relaxation Limit for Aw-Rascle System

We study the relaxation limit for the Aw-Rascle system of traffic flow. For this we apply the theory of invariant regions and the compensated compactness method to get global existence of Cauchy problem for a particular Aw-Rascle system with source, where the source is the relaxation term, and we show the convergence of this solutions to the equilibrium state.     

含铁磁耦合Ni3单元的均苯三甲酸桥联双层镍(II)配合物

使用均苯三甲酸与碳酸镍在水热条件下反应得到了一例新的二维双层Ni(II)配位聚合物Ni3(BTC)2(μ-H2O)26H2O。二维层包含syn-syn羧酸桥和水桥连接的三核Ni3单元,进一步用均苯三甲酸上的苯环连接成二维层状结构。磁性研究表明,相邻Ni2+离子间存在弱的铁磁耦合作用。水桥连镍离子的桥联键角为122.8(3)deg,所以通过该水桥镍离子间应该呈现反铁磁耦合。因此,实验结果证明了syn-syn羧酸桥传递铁磁耦合,而且铁磁耦合大于反铁磁作用,最终配合物呈弱的铁磁耦合。基于本工作和文献报道的含syn-syn 羧酸混合桥联镍配合物的磁性,我们总结出下面结论：Ni–O–C–O–Ni的共面性与否决定了配合物的磁性。共面性好的Ni–O–C–O–Ni导致中等强度的反铁磁耦合,而共面性差会消弱反铁磁作用,甚至出现由反铁磁变为铁磁耦合。标题配合物中羧酸桥所传递的铁磁性可能就归因于Ni–O–C–O–Ni的不共平面性。因此,与含羧酸桥的混合桥联双核铜(II)配合物类似,轨道补偿效应(the orbital complementary effect (OCE))对于解释水/羧酸混合桥联镍(II)配合物的磁性也同样适用。     

Coherent Dynamics of Direct-Current-Driven Quantum-Dot-Array with Two Time-Dependent Embedded Impurities

The coherent dynamics of dc-driven quantum-dot array with two embedded time-dependent impurities is investigated, the exact crossings and avoided crossings in the quasienergies are associated with the evolution dynamics of the electron by the introduction of the envelope lines of the site＇s maximum returning probability. Through a perturbative scheme, the time-dependent Hamiltonian is replaced by an equivalent static one, whose structure reveals the new quantum tunnelling mechanism in the time-periodic driving system and sheds light on the alternative interpretation of dynamic localization and delocalization.     

干风冷水型转轮空调系统全寿命特性研究

干风冷水型转轮空调系统是一种新型的转轮除湿空调系统,它基于吸附除湿和再生式蒸发冷却技术能够在夏季同时输出干空气和较低温度的冷冻水,克服了现有转轮除湿空调显热处理能力的不足。本文采用全寿命周期研究方法,对此种新型转轮空调系统在上海夏季和冬季运行的模式下进行全寿命的能耗分析、全寿命经济分析及碳信用分析,并与传统蒸汽压缩式空调系统进行对比。     

Photoacoustic investigation of the effective diffusivity of two-layer semiconductors

The problem of the effective thermal diffusivity of two-layer systems is investigated using the photoacoustic spectroscopy. The experimental results are examined in terms of the effective thermal parameters of the composite system determined from a homogeneous material that produces the same physical response under an external perturbation in the detector device. It is shown that the effective thermal conductivity is not symmetric under exchange of the two layers of the composite, i.e. the effective thermal parameters depend upon which layer is illuminated in the photoacoustic experiments. Particular emphasis is given to the characterization of the interface thermal conductivity between the layer system.     

Supercritical carbon dioxide extraction of Usnea longissima (L.) Ach.: Optimization by Box-Behnken design (BBD)

Usnic acid (UA) was extracted from Usnea longissima (L.) Ach. in supercritical carbon dioxide (SC-CO₂) medium. The selected process parameters were extraction temperature (35–45 °C), amount of co-solvent (0%–5%) and extraction time (5–9 h). These parameters were applied to Box-Behnken design (BBD) belonging to response surface methodology (RSM) to determine optimum process parameters for the highest amount of UA in the extract. g UA/100g lichen, extraction yield % and UA content values were calculated in the range of 0.045–0.317, 2.77–5.4 and 71%–82% in different experimental conditions, respectively. The optimum conditions were predicted as 42 °C, 4.3% (ethanol) and 7.48 h. It was determined that the predicted and experimental values of g UA/100g lichen were compatible, and the suggested model was valid.     

Pole-placement controllers for linear systems with point delays

This paper presents a robust control algorithm for plants involvingboth internal (i.e. in the state) and external (i.e. in theoutput or input) known point delays. Several stabilizing controllerstructures are given and analysed for the case of perfectlymodelled plants with known parameters. The parametrized partsof two of the controller structures involve delays, while thoseof the two remaining controllers are delay-free. However, auxiliarycompensating signals which weight the plant input and outputintegrals are incorporated in all the controller structuresfor stabilization and model matching purposes.     

氢原子在过渡金属修饰的Mg(0001)面扩散的第一性原理研究

基于密度泛函理论(DFY)的第一性原理计算方法,对氢原子在过渡金属(Sc、Ti、Cr、Mn、Fe、Co、Ni、Cu、V、Zn)修饰的Mg(0001)表面扩散性能进行了研究.研究发现过渡金属元素Sc、Ti、V、Cr、Mn、Fe、Co、Ni和Cu选择替代在镁表面第二层稳定,而Zn则选择替代在第一层稳定.当镁表面掺杂Zn和Cu时,氢原子选择停留在表面稳定;当掺杂Sc、Ti、V、Cr、Mn、Fe、Co和Ni时,氢原子选择进入镁块体内部.值得一提的是氢原子通过从过渡金属顶部通道扩散进入镁块体内部的势垒大大降低,笔者用差分电荷密度分析后发现氢原子与过渡金属原子成键使扩散势垒降低.当氢原子进入镁块体内部后靠近Sc、Ti、V、Cu和Zn原子时,将与这些过渡金属原子成键,从而阻碍了氢原子继续向内部扩散;而氢原子靠近Cr、Mn、Fe、Co、Ni原子时,选择离开过渡金属从而促进了氢原子向块体内扩散,可以大幅改善镁基储氢材料的吸氢动力性能.