Capric acid (CA)-lauric acid (LA)/silica (SiO 2 ) nanocapsules were fabricated in this paper. The core material was acted by CA-LA eutectic mixture, and the shell material was supported by SiO 2 . The phase identification, chemical composition, micrograph, and thermal property of as-prepared samples were analyzed based on X-ray diffraction, Fourier transformation infrared spectroscope, Scanning electron microscope and Differential scanning calorimety, respectively. These results displayed that CA-LA eutectic mixture was well encapsuled into SiO 2 pore network. The CA-LA/SiO 2 nanocapsules were spherical with uniform particle size of about 100 nm. When the mole proportion of CA:LA was 65:35, the phase transition temperature of nanocapsules was measured as 18.98 °C, and latent heat was confirmed as 83.06 J/g. The phase change temperature of the nanocapsules was basically consistent with the calculation value of pure CA-LA eutectic, and latent heat was about 58% of the theoretical value, signifying a high encapsulation efficiency. Therefore, CA-LA/SiO 2 nanocapsules as PCMs could provide thermal energy storage for buildings.

本文采用探究式教学对电动力学课程的教学内容、教学方法、教学手段和考核形式进行了改革,提高了学生学习的积极性、开拓了学生的视野,培养了学生的能力,获得了较好的教学效果.

稀土夜光纤维是一种新型的具有蓄光功能的材料,逐渐被应用于越来越多的行业领域.它是先把吸收的某一波长的光储存起来,然后再自发地长时间持续发光.介绍了稀土夜光纤维的种类、发光机理和制备流程,重点综述了稀土夜光纤维常用的纺丝方法,为稀土夜光纤维的研制提供参考.

以硝酸镥、硝酸铝和硝酸铈为初始原料,采用溶剂热均匀沉淀-煅烧法合成了铈掺杂镥铝石榴石(Lu3Al5O12∶Ce,LuAG∶Ce)纳米粉体.采用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、透射电子显微镜(TEM)、光致发光谱(PL)及荧光寿命等分析测试手段对所合成样品进行表征,并计算了其CIE色坐标.结果 表明,Ce3+的掺入并未改变LuAG基质的晶格结构,且粉体结晶很好,近球形,颗粒尺寸约为20 nm;荧光光谱显示了Ce3+的5d→4f特征发射,CIE色坐标表明LuAG∶Ce荧光粉呈现出亮绿光;荧光寿命曲线遵循单指数衰减,其荧光寿命值为51 ns.

国内许多高校都开设有信息光学课程,实验教学在课程教学中具有重要的作用.虚拟仿真实验由于具有良好的互动性和直观生动的优点,在实验教学活动中得到了越来越广泛的应用.我们在本文中对信息光学实验教学中可以开展的若干虚拟仿真实验进行一些讨论.

采用溶剂热法研究起始材料硝酸镥(Lu (NO3)3· 6H2O)和硝酸铝(Al(NO3)3· 9H2O)中结晶水去除前后对镥铝石榴石(LuAG)纳米粉体合成的影响;比较高温热处理对LuAG纳米粉体合成的影响;利用X射线衍射仪、红外光谱仪、透射电子显微镜分析所得粉体的物相组成、微观形貌和分散情况.结果表明,对于含结晶水的起始材料采用溶剂热法能够合成纯相的LuAG纳米粉体,颗粒尺寸为100 nm左右且具有较好的分散性;高温热处理后,纳米粉体结构趋于完整,但纳米颗粒有团聚现象.认为原材料中结晶水的去除不利于溶剂热法合成LuAG纳米粉体,而高温热处理所得的LuAG纳米粉体均已结晶.

A fixed-space-step method and a fixed-time-step method are presented, respectively, for solving the Stefan problems with time-dependent boundary conditions. The evolution of the moving interface and the temperature distribution in the phase change domain are simulated numerically by using two methods for melting in the half-plane and outward spherical solidification. Numerical experiment results show that the numerical results obtained from the two methods are in good agreement for the different test examples, and the two methods can be applied to solve Stefan problems in engineering practice.

Lutetium aluminium garnet (Lu3Al5O12, LuAG) nanoparticles were well prepared via a facile and low temperature one-step solvothermal route using aluminium nitrate and lutetium nitrate as raw materials and ethylenediamine (en) solution as the reaction medium. Here, en was employed both as the chelating agent and structure-directing agent. Influences of the reaction medium, temperature, time and dispersant on the synthesis of crystalline LuAG nanoparticles were investigated. Characterisation of LuAG nanoparticles was performed using X-ray diffraction, Fourier transform infrared, transmission electron microscopy and selected area electron diffraction. Optimum synthesis conditions of single-phase LuAG nanoparticles have been determined. The addition of citric acid as a dispersant can effectively decrease the particle size and increase dispersion of crystalline LuAG nanoparticles.

To study the defects in lutetium aluminum garnet crystal grown by Czochraski method, samples are irradiated under ultraviolet light (UV) by 4 low pressure mercury lamps (254 nm-wavelength,36 W) placed 15 cm from the samples for 24 h at room temperature. Later,the 7 mmí7 mm surface of these samples is coated with silver films and then placed inside an evacuated cylindrical chamber,the exterior of which is submerged in liquid nitrogen during the experiment. Then, dielectric spectroscopy measurement is performed on both the irradiated and the original samples with a HP4194A impedance analyzer. The results show that the dielectric loss peaks of the irradiated samples appear relaxation effects. The dependency of these relaxation peaks on frequency indicates that the dielectric relaxation behavior is a response to the orientation polarization of a permanent dipole. It therefore can be inferred, according to the relaxation mechanism of the dipole, a certain number of defects may exist in lutetium aluminum garnet crystal.

数学建模的思想和方法在纺织科学与技术的研究中应用非常广泛，有必要对纺织专业学生数学建模能力进行系统的培养。本文首先对数学建模方法在纺织学科研究中的应用进行简单概括；然后应用多元化的教学方法，开展了一系列有关纺织专业学生数学建模能力培养的研究与实践，确保了教学质量的提高和人才培养目标的实现。

结合多年数字电路实验教学的经验,认识到Multisim软件在教学中的优势,举例说明Muldsim在数字电路实验教学中的辅助作用,以提高教学效率.

构造定时间步长方法求解一类相变热传导问题，数值模拟了相变过程中移动边界的运动及介质内温度场的变化。数值实验表明定时间步长方法求解相变热传导问题是可行的，并且具有较高的精度。

In order to investigate the influences upon solid melting process caused by constant heat source boundary condition,the fixed space?step method and the fixed time?step method are constructed. The evolution of moving boundary and the temperature distribution in the phase change process are studied. The simulation results of two numerical methods are compared with the exact results. The numerical simulations show that the evolutions of moving boundary in the phase change process are influenced significantly by Stefan numbers and the temperature distributions in the phase change zone show linear decreasing trends. Moreover,the simulation results of two numerical methods have high precision and also there is a good agreement between the simulation results and the exact results ,which indicate that the two numerical methods constructed are feasible. Therefore,these researches can provide a reference for solving the solid melting problem.

Two finite difference schemes, the explicit and implicit schemes, were established to solve the one-di-mensional melting problem with periodic heat source, while the moving boundary model of the melting problem was transformed to a fixed boundary model by a simple stretching of the spatial coordinate.The numerical stabilities of the explicit and implicit schemes were studied.The computational complexity and efficiency of these two schemes were compared.Also the evolution of the moving boundary and the temperature distribution were simulated numerically by u-sing these two finite difference schemes for the one-dimensional melting problem with periodic heat source.Numerical experiment results showed that the results obtained from these two schemes were in good agreement, but the computa-tional efficiency of the implicit scheme was much higher than that of the explicit scheme.

Stefan问题也称为移动边界问题,其特点是区域内存在着一个随时间运动的边界,如冰的融化、金属铸件的凝固、微粒扩散和种群繁衍等.求解Stefan问题,由于问题的非线性性质和移动边界的未知位置,只有一些特殊情况才能获得解析解,通常只能用近似方法或数值方法求解.

Combined with studentsˊ major and course features of charm of nanotechnologies and nanomaterials, teaching contents, teaching methods and teaching means in the information technology environment are mainly studied and fulfilled in this paper. By introducing the information technology into the classroom teaching, the teaching mode is improved, the atmosphere of the classroom teaching is optimized, the studentsˊ learning initiative is stimulated, the studentsˊ scientific exploration ability is trained, the teaching quality is improved, and good teaching effect is achieved.

作为新一代可充电电池，锂离子电池具有工作电压高、比能量高、循环寿命长及无记忆效应等特点，是理想的“绿色电池”。尖晶石型钛酸锂作为锂离子电池重要的负极材料，在充放电过程中几乎不发生结构改变，循环性能良好；有很好的充放电平台；不与电解液反应；与商品化的碳负极材料相比，通常具有更好电化学性能和安全性。本文介绍了尖晶石型钛酸锂的特点，重点综述了钛酸锂的几种不同制备方法及其优缺点，并对其发展前景进行了展望。

Finite difference method with fixed time-step is established to calculate spherical and cylindrical melting problems with periodically oscillating heat sources . The evolution of the moving interface and the temperature field within the liquid media in the melting process are numerically simulated. Also the effects of the Stefan number, the amplitude and frequency of the periodically oscillating heat sources on the evolution of the moving interface and the temperature distribution are analyzed. Numerical experiment results show that the Stefan number strongly influences the temperature distribution and the evolution of the moving interface, while the effect of the periodically oscillating heat sources on the evolution of the moving interface diminishes the phase change domain grows. Numerical simula?tion of the problem provides an important theoretical reference for phase change heat transfer problems in engineer?ing practice.

The numerical methods course is closely related with computer science, provides the most efficient algorithm for the numerical study of the various mathematical problems and has become a required course for many science and engineering majors. In this paper, aiming at the current application personnel training objectives, combining with teaching practice of numerical methods courses, the common problems in numerical methods course teaching are firstly briefly analyzed, and then a series of reform and practice on numerical methods course teaching is carried out by using the diversification of teaching methods, which can get rid of the boring state of traditional teaching mode and ensure the enhancement of the teaching quality and the realization of the goal of talents cultivation.

Origin 8 software has powerful data and graphic processing capabilities, and can effectively analyze the complex data. This paper explained the application of Origin 8 software on experimental data and graphic processing by typical examples, such as importing the experimental data, setting the coordinate axis, comparing the data and fitting the curves. This paper can provide useful guidance for the further application.