On the problem of heat transfer in phase-change materials for small Stefan numbers

The problem of solidification of an infinite liquid slab by linear convection cooling from the adjacent air is considered. It is assumed that at the initial moment the slab has a critical temperature and that on one side the air temperature has diurnal fluctuations of relatively small amplitude. The solution is found in the form of power series of small parameters. The first three terms of each series are obtained. This permits construction of a simple formula for the total solidification time. Evaluation of the accuracy of the solution based on the integral heat balance equation is suggested. Some particular cases of the problem are considered on the assumption that one side of the slab is insulated. One of these cases is the simplest Stefan problem which has an exact solution. Comparison with this solution is made.     

惰性阳极基体材料NiFe2O4尖晶石的研制

本文用Ni2O3和Fe2O3为原料制备了铝电解用惰性阳极基体材料NiFe2O4尖晶石,详细介绍了整个制备过程。通过对NiFe2O4尖晶石的含量、真密度以及开口孔隙率等重要指标进行研究比较,最终得出了制备NiFe2O4尖晶石最佳工艺条件,并用最佳工艺条件重新制取试样进行热腐蚀实验。     

Amorphous TiO(2) nanotube arrays for low-temperature oxygen sensors

Titania nanotube arrays (TNTA) were synthesized on a titanium substrate using anodic oxidation in an electrolyte containing ammonium fluoride and evaluated for low-temperature oxygen sensing. Their sensing properties were tested at different temperatures (50, 100, 150, 200, 250 and 300?°C) when exposed to various oxygen concentrations. The as-prepared TNTA are amorphous and exhibit much higher carrier concentration than that of annealed TNTA. Such amorphous TNTA show much higher sensitivity than that of annealed TNTA, SrTiO(3) and Ga(2)O(3) sensors. This sample demonstrates the lowest detectable oxygen concentration of 200 ppm, excellent recovery and good linear correlation at 100?°C. These results indicate that TNTA are indeed very attractive oxygen-sensing materials.     

Preparation TiO2 core-shell nanospheres and application as efficiency drug detection sensor

In this paper, we report the facile preparation of monodisperse titanium dioxide-diltiazem/tetrachlorobismuth core-shell nanospheres (TiO₂@DTMBi), in which, diltiazem (DTM)/tetrachlorobismuth (BiCl₄) complexes were employed as electroactive materials. The morphology, size, formation, and structure of the obtained TiO₂@DTMBi spheres were investigated by transmission electron microscopy, scanning electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, and X-ray diffraction. The optimal condition of obtained monodisperse 40-nm TiO₂@DTMBi spheres was researched. The results of using TiO₂@DTMBi nanospheres as proposed drug sensor indicate a wide linear range (10^-7 to 10^-1 M) and a very low detection limit of 0.20 μg/mL.     

转炉终点预测模型中异常数据检验的研究

针对转炉终点神经网络预测模型数据预处理过程中多变量、大样本的特点,介绍并应用了一种识别及检验异常数据的方法;筛选了神经网络模型的数据样本集数据;并初步验证了筛选结果。经过筛选,神经网络预测模型训练集数据训练误差绝对值的平均值及最大值分别下降了267%和41%;测试集数据测试误差的平均值及最大值分别下降10%和45%。结果表明,该方法对于转炉预测模型的数据筛选行之有效,对转炉预测模型的进一步完善有一定的实用价值。     

影响铝电解槽阴极内衬寿命因素及其解决措施

讨论延长铝电解槽阴极内衬的使用寿命问题,揭示了阴极破损的十种现象,提出了延长槽寿命的若干措施,认为应用干防渗层具有重要的意义,是一项有力的措施。保持铝电解生产过程正常平稳是延长槽内衬寿命的保证。     

添加MgO对高炉喷煤煤粉燃烧率的影响

提出通过风口喷煤向高炉中加入含MgO物料,以替代烧结料中添加MgO的传统方法。通过试验考察了添加轻烧菱镁石对煤粉燃烧率的影响。结果表明：添加MgO有助于提高煤粉燃烧率,进一步富氧则助燃效果更明显。在安钢160kg／t喷煤比的条件下,适宜的轻烧菱镁石添加量为3％～4％。     

Synthesis and electrochemical properties of LiNi0.4Mn1.5Cr0.1O4 and Li4Ti5O12

Spinel compound LiNi_0.4Mn_1.5Cr_0.1O₄ (LNMCO) and Li₄Ti₅O₁₂ (LTO) were synthesized by the sol-gel method and the solid-state method, respectively. The particle sizes of the products LiNi_0.4Mn_1.5Cr_0.1O₄ and Li₄Ti₅O₁₂ were 0.5 to 2 um and 0.5 to 0.8 um, respectively. All samples exhibited excellent electrochemical properties. A LiNi_0.4Mn_1.5Cr_0.1O₄/Li₄Ti₅O₁₂ (LNMCO/LTO) cell was fabricated and was demonstrated to exhibit good electrochemical properties at the high current rate of 1 C. When the specific capacity was determined based on the mass of the LNMCO cathode, the LNMCO/LTO cell delivered 125 mAh g⁻¹ at 1 C and 77 mAh g⁻¹ at 5 C. The capacity retentions after 30 cycles were 94.4 % and 83.1 %, respectively.     

硅微粉填料对环氧灌封材料性能的影响

以液态双酚A环氧树脂为基料,苯酐为固化剂,味唑类为促进剂,苄基缩水甘油醚为稀释剂,硅微粉为填料制得了性能优异的电器灌封材料。考察了硅微粉的种类及用量对环氧灌封材料的凝胶化时间、冲击强度、吸水率、体积电阻率的影响。结果表明活性硅微粉对提高环氧灌封材料的性能有利,当活性硅微粉用量为150质量份时,环氧灌封材料的综合性能较佳。