无单元法求解欧拉梁及梁系的自由振动问题

双变量无单元法以广义移动最小二乘法为理论基础,同时考虑挠度和转角双变量.采用双变量无单元法建立了欧拉粱的质量矩阵和刚度矩阵,并进行自由振动的计算.不同边界条件欧拉梁动力特性的算例表明:双变量无单元法比与只考虑挠度的单变量无单元法具有更高的插值精度,并能在高阶振型计算中获得明显优于有限元的计算精度.通过试算法对影响半径中的scale乘子进行了讨论,认为在动力计算中Scale取3.5较合理.最后在欧拉粱的基础上,将无单元法应用于梁系模型的自由振动计算,显示了该法在复杂模型中的精确性.     

基于无单元法的平面框架地震反应分析

无单元法在动力计算领域中的应用目前多以梁、板等简单构件的自振特性分析为主,对建筑结构的动力计算,尤其是地震反应分析尚未涉及.文中推导了无单元法的离散动力方程,以轴力杆、欧拉梁模型为基础,将简单构件的无单元动力计算推进到实际结构的地震反应分析,并给出了数值实现的基本流程.最后以一个十一层钢筋混凝土高层结构为算例,实现了多层多跨平面框架的无单元地震反应分析,达到了预期的效果,验证了无单元法应用于平面框架地震反应分析的可行性和有效性.     

Fe3+偶联的Eosin-Y染料敏化Pt/ZnO可见光制氢活性

以浸渍法制备了Eosin-Y染料敏化的EY-Pt/ZnO和Fe3+偶联的EY-Fe-Pt/ZnO光催化剂。利用XRD、UV-Vis漫反射光谱、FTIR光谱、XPS能谱和电化学方法对催化剂进行了表征。以三甲胺（TMA）为电子给体,考察了催化剂在可见光（λ≥420 nm）照射下的光催化分解水制氢活性。结果表明:Eosin-Y染料的敏化使Pt/ZnO对可见光有较强的吸收和放氢活性。Fe3+离子偶联后提高了Eosin-Y染料在Pt/ZnO光催化剂表面的吸附,促进了光生电子-空穴的分离,使催化剂可见光制氢活性和稳定性得以提高。最佳条件下,经过8 h光照,Fe3+离子偶联的催化剂EY（0.05）-Fe（0.003）-Pt/ZnO的制氢活性比单一用Eosin-Y染料敏化的催化剂EY（0.05）-Pt/ZnO的制氢活性提高了47%。     

AgIO_3 Composited with m-BiVO_4 as Enhanced Visible-light Heterojunction Photocatalysts for the Elimination of Aqueous Organic Pollutants

The heterojunction strategy was used to overcome the drawbacks of AgIO_3 for its wide band gap and of BiVO_4 for its low charge-separation efficiency. The photocatalytic per-formances of the as-prepared AgIO_3/BiVO_4 were assessed by the photodegradation of rhodamine B(Rh B) and tetracycline hydrochloride antibiotics(TC) under visible-light irradiation. All the as-prepared samples showed remarkable enhanced photocatalytic efficiency than pure AgIO_3 and BiVO_4. Especially, 40% AgIO_3/BiVO_4 exhibited optimum photocatalytic activities among all the prepared samples. The improvements may be ascribed to the synergetic effect between AgIO_3 and BiVO_4 including matching potentials and effective charge separation. Radical trap experiments determined that h+ radical plays a significant role in the photodegradation of RhB while e-is not the dominating reactive species.     

Effects of the density dependence of the symmetry energy on neutron stars

In this paper,we include the density dependence behavior of the symmetry energy in the improved quark mass density dependent （IQMDD） model.Under the mean field approximation,this model is applied to investigate neutron star matter and neutron stars successfully.Effects of the density dependence of the symmetry energy on neutron stars are described.     

一种改善FFH-OCDMA性能的非循环单重合码

分析了一种非循环单重合码的色散效应,并将色散效应等效为功率衰减因子,得出同时考虑差拍噪声和色散后FFH-OCDMA系统的误码率性能.结果表明,非循环单重合码的色散效应虽然比循环单重合码有所增加,但它大大降低了互相关干扰,也大大降低了差拍噪声,从而提高了系统的误码率性能.     

A novel symbol overlapping FFH-OCDMA system

A novel symbol overlapping optical fast frequency-hop code-division multiple access(FFH-OCDMA)sys-tem is proposed,and its bit error rate(BER)performance is investigated under consideration of avalanchephotonic diode(APD)noise auid thermal noise.An experimental symbol overlapping(SO)FFH-OCDMAtestbed is developed and some experimental results axe given.The theoretical and experimental resultsshow that the system is apt to implement and has larger throughput.     

A novel symbol overlapping FFH-OCDMA system

Anovel symbol overlapping optical fast frequency-hop code-division multiple access(FFH-OCDMA)system is proposed, and its bit error rate(BER) performance is investigated under consideration of avalanche photonic diode(APD) noise and thermal noise. An esperimental symbol overlapping(SO)FFH-OCDMA testbed is developed and some experimental results are given. The theoretical and experimental results show that the system is apt to implement and has larger throughput.     

光纤色度色散对快跳频光码分多址系统性能影响

利用仿真法研究光纤色度色散对快跳频光码分多址系统的影响,主要研究了光纤色散导致的码字自相关输出峰值、取样切普内光能量的减小、不同条件下所能达到的最大用户数据速率和最大传输距离.给出了几个具有不同q值的典型快跳频光码分多址系统的最大用户数据速率和传输距离.提出了减小q值以降低色散影响的码字优化法.讨论了该系统的应用场合问题.