从“学”的角度看实验的全方位作用

现代教育思想强调研究“学”的规律,特别注意过程和学习心理。本文试从“学”的角度,在对物理学习过程的规律和对学生学习心理的研究中阐述实验在中学物理教学中的全方位作用。     

磷钒钼蓝-Sephadex G-25凝胶相双波长分光光度法测定微量磷

应用葡聚凝胶（Sephadex)G-25从水溶液中吸附富集磷钒钼蓝杂多酸，在800nm和700nm处应用固相分光光度法直接测定磷钒钼蓝－凝胶相吸光度差，磷量在0－8μg/50mL范围内符合比尔定律，用于分析高纯硫酸钠中微量磷，结果良好。     

Analytical solutions to edge effect of composite laminates based on symplectic dual system

In the symplectic space composed of the original variables, displacements, and their dual variables, stresses, the symplectic solution for the composite laminates based on the Pipes-Pagano model is established in this paper. In contrast to the traditional technique using only one kind of variables, the symplectic dual variables include displacement components as well as stress components. Therefore, the compatibility conditions of displacement and stress at interfaces can be formulated simultaneously. After being introduced into the symplectic dual system, the uniform schemes, such as the separation of variables and symplectic eigenfunction expansion method, can be implemented conveniently to analyze composite laminate problems. An analytical solution for the free edge effect of composite laminates is obtained, showing the effectiveness of the symplectic dual method in analyzing composite laminates.     

ICP-AES测定青岛崂山绿茶中的微量元素

采用HNO3-H2O2混合酸,密闭微波消解样品,应用ICP-AES测定青岛崂山绿茶中Al、Ca、Cd、Co、Cr、Cu、Fe、K、Mg、Mn、Na、Ni、Pb、Se、Sr、V和Zn等17种营养元素及重金属元素的含量。测定结果的相对标准偏差均小于3.50%,对17种元素的加标回收率在90.0%—110.2%之间,采用该方法测得的茶叶标准物质（GBW10016）的17种元素的值均在标准值范围内,方法准确度高。实验结果表明青岛崂山绿茶中含有大量对人体有益的元素包括Ca、Co、Cr、Cu、Fe、K、Mg、Mn、Na、Ni、Se、Sr、V和Zn等,另外也检测到含有Al,Cd和Pb等有毒、有害元素,但是含量很低,对人体的不利影响可以忽略不计。     

多层多孔锂离子电池结构的导波频散特征及其应用EI北大核心CSCD

采用状态矩阵与勒让德级数联合法,同步联立Biot理论,构建多层多孔锂离子电池声传播特性理论模型,以厚1.9 mm软包钴酸锂电池为例,数值分析了荷电状态(State of Charge,SOC)对多模态频散曲线的影响规律。同时,建立了电池中的声传播特性频域仿真模型,提取频域仿真中的超声导波频散曲线。此外,以体积小、柔性强的压电纤维复合材料(Macro Fiber Composite,MFC)为基础,实验探究了不同SOC对锂离子电池中声学行为的影响。采用互相关分析获取电池放电过程中声波渡越时间的偏移规律,建立了1.9 mm软包钴酸锂电池的声学波动行为与电池SOC间的映射关系。     

改进最小费用流相位解包裹算法

在不同解包裹算法中,最小费用流(MCF)解包裹法可以限制残差点误差远程扩散,并将误差优先限制在低相干区域,有利于保证高相干区域解包裹结果不受干扰,精度较高,但残差点数量较多时计算效率很低。为缩短解包裹时间,提出一种残差点预处理方法。该方法将残差点视作正负电荷,通过电场力,引导距离较近的异号残差点互相抵消,大幅减少残差点数量,从而提高解包裹计算效率。仿真数据和实验数据表明,残差点预处理对MCF解包裹精度影响很小,在残差点数量超过3000时可以大幅提高解包裹计算效率。     

夹在两个柔性层中薄膜的正弦模态界面屈曲分析

当一层比较硬的薄膜被封闭在上下两层柔性层中,组成了三层材料结构.在压应力的作用下,这层薄膜可能会发生屈曲失稳.由可弯曲电路封装在柔性层中组成的三层材料系统能进一步提高其弯曲性能的事实得到启发,不同于广泛研究的双层材料结构表面屈曲问题,从理论上分析三层材料结构在压应力作用下的刚硬薄膜的正弦模态屈曲问题.柔性层和刚硬薄膜材料假定皆为各向同性.由于薄膜厚度远远小于柔性层厚度,柔性层在理论分析中认为是无穷厚的.刚硬薄膜可以用非线性薄板模拟,其变形为小应变但是允许有限转动,用于描述屈曲时的状态.利用线性扰动分析,得到了屈曲临界薄膜应力,波数和平衡状态下的波幅的解析表达式.结果表明,针对不同的刚硬薄膜和柔性层的弹性模量,当刚硬薄膜相对于上下柔性层越硬,就越容易发生界面屈曲.     

Dynamical localization effect in a coupled quantum dot array driven by an AC magnetic field

We have studied the transport properties of a ring-coupled quantum dot array driven by an AC magnetic field, which is connected to two leads, and we give the response of the transport current to the dynamical localization. We found that when the ratio of the magnetic flux to the total quantum dots number is a root of the zeroth order Bessel function, dynamical localization and collapse of quasi-energy occurs and importantly, the transport current displays a dip which is the signal of dynamical localization. The dynamical localization effect is strengthened as a result of the increase of the quantum dot number, and it is weakened on account of the increase of the dots-lead hopping rate.     

Vortex Structures and Behavior of a Flow Past Two Rotating Circular Cylinders Arranged Side-by-Side

We present a study on the vortex structures and behavior of a flow past two rotating circular cylinders arranged side-by-side at a range of absolute rotational speeds （｜a｜≤2） for two different gap spacings g＊= 1.5 and 0.7 at Reynolds numbers Re = 160 and 200. The results show that the flow becomes stabilized and finally steady beyond the critical rotational speed as ｜a｜ increases, regardless of the variation in Re and g＊. The value of critical rotational speed increases with increasing Re. The wake patterns change in the unsteady regimes for g＊ =1.5 and 0.7. With increasing ｜a｜, the time-averaged drag coemcient CD decreases and the lift coemcient CL increases, respectively. CD at Re = 160 and g＊ = 0.7 decreases rapidly, resulting in the smallest value at the same ｜a｜ for 1 ≤ ｜a｜≤ 2. CD augments with increasing g＊ at the same ｜a｜. For g＊=1.5, CD has a little disparity between the cases of Re= 160 and 200. For the flow past two still cylinders, CL is inversely proportional to g＊ of two cylinders for a fixed ｜a｜, and is not dependent on Re.