变截面微管道中高zeta势下幂律流体的旋转电渗滑移流动

本文研究高zeta势下具有Navier滑移边界条件的幂律流体,在变截面微管道中的垂向磁场作用下的旋转电渗流动.在不使用Debye–Hückel线性近似条件时,利用有限差分法数值计算外加磁场的旋转电渗流的电势分布和速度分布.当行为指数n=1时得到的流体为牛顿流体,将本文的分析结果与Debye–Hückel线性近似所得解析近似解作比较,证明本文数值方法的可行性.除此之外,还详细讨论行为指数n、哈特曼数Ha、旋转角速度?、电动宽度K及滑移参数β对速度分布的影响,得到当哈特曼数Ha>1时,速度随着哈特曼数Ha的增加而减小;但当哈特曼数Ha <1时, x方向速度u的大小随着Ha的增加而增加.     

中空介孔SiO2纳米球的制备、改性及其对Al3+荧光识别研究

中空介孔SiO2由于中空多孔的结构而常用作功能材料的基底.将中空介孔SiO2进行官能团修饰,并应用为荧光传感材料是中空介孔SiO2一个重要的研究领域.本论文采用聚丙烯酸(PAA)为中空模板,聚醚F127为造孔剂,正硅酸乙酯(TEOS)为硅源,氨水为催化剂在乙醇体系中制备了中空介孔SiO2纳米球.系统研究了搅拌速度和聚醚F127引入量对中空介孔SiO2纳米球形貌及比表面积的影响.通过透射电镜、N2-等温吸附脱附曲线等表征说明该合成方法具有很好的普适性,通过调节F127的引入可以实现对比表面积的有效控制.通过氨基化、席夫碱反应进行荧光修饰,进一步研究表明荧光修饰后的中空介孔SiO2纳米球在水溶液中能够实现对Al3+的有效检测,检测限为1.19×10 -7M.     

硫化镉反蛋白石光子晶体制备及光解水制氢

对硫化镉反蛋白石结构光子晶体薄膜进行了可控合成,用巯基乙酸修饰的纳米晶和P(St-MMA-SPMAP)高分子小球共组装,成功地构筑了反蛋白石结构并用于可见光光解水产氢。结果表明,在可见光(λ≥420 nm)照射下,Cd S-310反蛋白石结构薄膜的光解水产氢性能比硫化镉纳米颗粒提高了一倍。这主要是因为等级孔结构反蛋白石光子晶体特性对催化剂的光催化性能的提升:首先,反蛋白石的周期性结构增加了光子在材料中的传播,提高了催化剂对太阳光的利用率;同时,大孔孔壁是由纳米颗粒堆积而成的,在反应中提供了更多的反应活性位点;此外,孔结构有利于物质的传输和分子的吸附。     

基于NiCo2O4纳米片电极的非对称混合电容器

The looming global energy crisis and ever-increasing energy demands have catalyzed the development of renewable energy storage systems. In this regard, supercapacitors (SCs) have attracted widespread attention because of their advantageous attributes such as high power density, excellent cycle stability, and environmental friendliness. However, SCs exhibit low energy density and it is important to optimize electrode materials to improve the overall performance of these devices. Among the various electrode materials available, spinel nickel cobaltate (NiCo₂O₄) is particularly interesting because of its excellent theoretical capacitance. Based on the understanding that the performances of the electrode materials strongly depend on their morphologies and structures, in this study, we successfully synthesized NiCo₂O₄ nanosheets on Ni foam via a simple hydrothermal route followed by calcination. The structures and morphologies of the as-synthesized products were characterized by X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller (BET) surface area analysis, and the results showed that they were uniformly distributed on the Ni foam support. The surface chemical states of the elements in the samples were identified by X-ray photoelectron spectroscopy. The as-synthesized NiCo₂O₄ products were then tested as cathode materials for supercapacitors in a traditional three-electrode system. The electrochemical performances of the NiCo₂O₄ electrode materials were studied and the area capacitance was found to be 1.26 C·cm^-2 at a current density of 1 mA·cm^-2. Furthermore, outstanding cycling stability with 97.6% retention of the initial discharge capacitance after 10000 cycles and excellent rate performance (67.5% capacitance retention with the current density from 1 to 14 mA·cm^-2) were achieved. It was found that the Ni foam supporting the NiCo₂O₄ nanosheets increased the conductivity of the electrode materials. However, it is worth noting that the contribution of nickel foam to the areal capacitance of the electrode materials was almost zero during the charge and discharge processes. To further investigate the practical application of the as-synthesized NiCo₂O₄ nanosheets-based electrode, a device was assembled with the as-prepared samples as the positive electrode and active carbon (AC) as the negative electrode. The assembled supercapacitor showed energy densities of 0.14 and 0.09 Wh·cm^-3 at 1.56 and 4.5 W·cm^-3, respectively. Furthermore, it was able to maintain 95% of its initial specific capacitance after 10000 cycles. The excellent electrochemical performance of the NiCo₂O₄ nanosheets could be ascribed to their unique spatial structure composed of interconnected ultrathin nanosheets, which facilitated electron transportation and ion penetration, suggesting their potential applications as electrode materials for high performance supercapacitors. The present synthetic route can be extended to other ternary transition metal oxides/sulfides for future energy storage devices and systems.     

立方相KNbO3晶体本征空位点缺陷的电子结构研究

利用第一性原理从头计算方法对立方相KNbO3晶体的肖特基缺陷的稳定性、能带结构、电子态密度和磁性性质进行了研究.发现含本征点缺陷的KNbO3体系结构稳定;K,Nb空位诱导KNbO3缺陷晶体产生铁磁性;O空位则无此性质.K空位诱导KNbO3缺陷晶体磁性源于O原子2p轨道退简并;Nb空位诱导KNbO3缺陷晶体磁性源于O-2p电子极化.     

Hyperion高光谱遥感器的在轨自动化定标

利用布设在敦煌辐射校正场的自动化观测设备,对Hyperion高光谱遥感器开展定标试验;详细描述自动化定标的原理和方法,明确定标流程;针对高光谱遥感器的特点建立参考反射率数据库,以解决通道反射率与参考反射率光谱形状不匹配的问题;在2016年10月至2017年4月期间,对Hyperion高光谱遥感器共完成4次有效的自动化定标试验,并将试验结果与Hyperion高光谱遥感器观测的表观辐亮度进行比对验证。结果表明:在420～1044nm光谱范围内,场地自动化定标得到的表观辐亮度与卫星观测的表观辐亮度的相对偏差小于5%,标准方差小于2.3%;场地自动化定标结果与高光谱星上观测结果具有较高的一致性和稳定性。所提方法可以应用于高光谱遥感器的高频次在轨辐射定标。     

爆炸荷载下沉箱重力式码头模型毁伤效应

在野外条件下开展了不同爆炸荷载条件下沉箱重力式码头模型毁伤效应实验，得到了沉箱重力式码头模型在1 kg TNT当量空中爆炸、水下爆炸以及结构内部爆炸后的毁伤模式，并针对不同毁伤模式给出了相应的抢修建议。实验结果表明:空中爆炸荷载下码头仅面板局部破坏形成爆坑；水下爆炸荷载下码头迎爆面及相近区域形成大量裂缝；结构内部爆炸荷载下码头仓格大变形破坏且中间面板被掀飞；从横向对比来看，在相同爆炸当量下空中爆炸荷载下码头毁伤程度最小，结构内部爆炸荷载下码头毁伤程度最大。