CFD simulation of fluidization quality in the three-dimensional fluidized bed

Multiphase computational fluid dynamics （CFD） has become an alternative method to experimental investigation for predicting the fluid dynamics in gas-solid fluidized beds. The model of Brandani and Zhang, which contains additional terms in both the gas- and solidphase momentum equations, is employed to explore homogeneous fluidization of Geldart type A particles and bubbling fluidization of Geldart type B particles in three-dimensional gas-fluidized beds. In this model, only a correlation for drag force is necessary to close the governing equations. Two kinds of solids, i.e., fine alumina powder （dp= 60 μm and pp = 1500 kg/m^3） and sand （dp = 610 μm and pp = 2500 kg/m^3）, are numerically simulated in a rectangular duct of 0.2 m （long） × 0.2 m （wide）× 0.5 m （high） size. The results show good agreement with the classic theory of Geldart.     

Evidence for metasomatic mantle carbonatitic magma extrusion in Mesoproterozoic ore-hosting dolomite rocks in the middle Kunyang rift, central Yunnan, China

The Kunyang rift lying on the western margin of the Yangtze platform is a rare Precambrian Fe-Cu mineralization zone. Wuding- Lufeng basin that is an important part of the zone is located on the west edge in the middle of the rift. The most important ore-hosting rocks are Mesoproterozoic dolomite rocks in the basin controlled by a ring fracture system, which is a fundamental structure of the basin. Plenty of silicate minerals and acicular apatite, feldspar phenocrysts and small vesicular, flown line and flown plane structures, melt inclusion and high temperature fluid inclusion found in most ore-hosting dolomites suggest that this kind of rocks could not be sedimentary dolomite, marble or hydrothermal carbonate rocks. The Zr/Hf and Nb/Ta values of the rocks are identical with those of associated mantle-derived rocks, and vary widely. For the monomineral dolomite, δ^18OSMOW‰=＋5.99 to ＋18.4 and δ^13CPDB‰ = -3.01 to ＋0.94, which fall within the range for all carbonatitic volcanic rocks of the world. As for the accessory minerals, the values of δ^18OSMOW‰ of magnetite （=＋3.47 to ＋5.99‰） are close to that of the mantle （〈5.7%）, and the δ^34S‰ values of sulfides （-5.09 to ＋5.78, averaging ＋1.50） are close to that of meteorite. For all the ore-bearing dolomite rocks, εNd = ＋0.19 to ＋2.27, and the calculated Isr=0.699143, while for the associated mantle-derived rocks, εnd = ＋3.18 to ＋3.72. All the data suggest that the mineral assemblage is not only igneous but also of metasomatic mantle origin. And the presence of acicular apatite indicates that the rocks were formed by magma rapidly cooling. And the phenocryst texture and vesicular, flown and ropy and pyroclastic structures suggest that the igneous rocks were extrusive. Therefore, the ore-bearing dolomite rocks are carbonatitic volcanic rocks. This conclusion implies that most iron and copper ore deposits hosted in the dolomite rocks should be of the carbonatite type.     

大学英语教师职业倦怠状况分析及应对措施研究

职业倦怠作为客观存在,已经成为许多人积极行为的障碍。许多大学英语教师由于职业特点及教师自我调节不当等原因,正面临着职业倦怠的危机。大学英语教师可以通过主、客观两个方面努力,解决职业倦怠的问题。     

三嗪类紫外线吸收剂的制备及应用性能

以三聚氯氰、对氨基苯磺酸和乙二胺为原料合成了一种三嗪类紫外线吸收剂,并利用红外光谱和紫外光谱进行了初步的表征.通过正交实验考察并得出了优化整理工艺,即浴比1:15,反应温度55℃,元明粉质量浓度35 g/L,反应时间20min,纯碱质量浓度20 g/L,田着温度80℃,固着时间20min.整理后织物应用性能测试表明,制备的紫外线吸收剂具有优良的防紫外线性能和耐洗涤性能,经50次洗涤后,织物的抗紫外指数保留率高于90%,且整理前后织物的物理机械性能变化较小,为一种优良的反应性紫外线吸收剂.     

RP-HPLC法分析罗红霉素含量

目的 建立用RP-HPLC法分析罗红霉素药物含量的方法.方法 以安捷伦ZORBAX Eclipse XDB-C18柱为色谱柱、乙腈(0.010mol/L)醋酸铵缓冲液(体积比70:30,Ph=6.5)为流动相,选择220nm为检测波长;柱温40℃,用反相高效液相色谱法测定罗红霉素(Roxithromycin,RM)的含量.结果 罗红霉素的浓度在1.150-100.8 mg/L范围内与峰面积呈良好线性关系,r=0.99977,平均回收率为99.57%,相对标准偏差为1.23%(n=5).结论 该方法操作简单、快速,可用于罗红霉素含量的测定.     

除草剂“草甘膦”对蟾蜍外周血红细胞微核及核异常的影响

本文研究了低毒除草剂“草甘膦”对蟾蜍外周血红细胞微核及核异常的影响，分别统计了微核细胞率；微核率；异常率和核异常率，研究结果表明，用草甘膦处理3天和5天后，不同浓度的药物对蟾蜍的红细胞微核率和核异常率均有一定程度的影响；但用不同黉度药物处理后红细胞的微核率和核异常率虽有差异，却没有出现显著的剂量效应。     

Attack Simulation Model and Channel Statistics in Underwater Acoustic Sensor Networks

In recent years,underwater acoustic wireless sensor networks have been used in many areas.There have been many field trials of acoustic propagation models and statistics for shallow water conditions.However,field trials are limited environmentally and,hence,not widely accepted.Simulations of the impulse response of a shallow underwater acoustic channel allows less expensive system tests that are reproducable.This paper presents a shallow water acoustic channel model based on the actual acoustic propagation ...     

基于逐层演化的群体智能算法优化

为能彻底解决群体智能算法早熟问题的同时保持原算法主体不变且可与现有优化理论协同优化,在前期仿真实验和理论证明的基础上,提出了一种逐层演化的改进策略.利用在原算法中构建基于搜索空间压缩理论的自适应系统,通过逐层的压缩、选择、再初始化的操作,以包括压缩后搜索空间在内的社会信息作为遗传知识,指导寻优过程,从而实现最终解精度的提升、避免早熟问题的出现.对基准函数进行仿真实验可以看出该策略在提升算法精度,增强后期个体活性方面具有良好的表现.     

电化学加工YT15硬质合金表面形貌特征实验研究

由于所含碳化物粉末与黏结金属的电极电位差等原因,硬质合金电化学加工的阳极表面蚀除过程较碳钢和其他金属更为复杂.以YT15硬质合金为实验对象,对试件原始表面进行统一加工条件下的研磨处理,使之具有一致的表面状态.在此基础上进行电化学加工实验,以SEM图像结合轮廓曲线,分析表面微观形貌的横向特征和纵向特征,获得表面材料溶解的特点和规律.实验发现,使用不同电解液获得的表面微观形貌特征差异显著,加工过程中的表面微观形态和腐蚀规律及变化特性也各不相同.研究认为,不同电解液产生的不同阳极表面膜特性和硬质合金材料固有的多组分特征是导致这种差异的原因,抑制硬质合金同类材料的边界腐蚀是获得良好加工效果的关键.NaOH去钝化能力较强,溶解速度快,适于成型加工电解液;NaNO_3及NaCl具有良好的钝化成膜能力,阳极膜无序破坏容易导致不均匀腐蚀,纯电化学加工不容易获得良好的加工效果,但通过合理施加外力控制阳极膜的有序破坏,则可提高表面质量,具有作为复合光整加工电解液的潜力;H_2SO_4+H_3PO_4成膜较均匀,活化作用较好,具有抑制材料不均匀溶解的能力,适用于具有一定表面质量要求条件下同时达到特定成型效果的加工.     

对乙基苯甲酸合成实验的探究式教学

介绍了以乙酸酐为乙酰化试剂、乙基苯和无水三氯化铝为原料合成对乙基苯乙酮;再利用碘仿反应,由对乙基苯乙酮合成对乙基苯甲酸的探究式教学方法。阐述了让学生查阅文献,自主设计方案,具体实施该实验,探究实验条件的具体做法和体会。通过该实验,对有机化学实验教学进行了一次有益的尝试,有效训练了学生独立分析问题、解决问题的能力和创新实践能力。