聚丙烯腈纤维预氧化过程中氧化反应和环化反应的动力学研究

采用差示扫描量热仪(DSC)研究了聚丙烯腈/衣糠酸共聚物纤维在氧化性气氛(空气)和非氧化性气氛(氩气)下环化反应和氧化反应受加热速率的影响,计算了不同气氛下的反应活化能.采用元素分析技术研究了不同温度下氧化反应速率的变化,分析了氧的扩散机制.研究结果表明:含氧气氛中的反应活化能高于惰性气氛中的反应活化能,预氧化初期整个...     

露天煤矿车辆的不确定调度模型与优化求解

以内蒙古一露天煤矿为研究对象,对露天矿车辆调度过程中的关键时间参数进行统计分析,确定其随机性,建立车辆调度的不确定模型.在对不确定调度模型优化分析的过程中,训练神经网络逼近函数,对于粒子群算法容易陷入局部收敛的缺陷,结合模拟退火算法的局部搜索技术,得到模拟退火算法和粒子群算法相结合的混合智能算法.计算实验结果证明该算法的有效性和优越性.     

白云鄂博稀土尾矿的工艺矿物学研究

采用X射线衍射、扫描电子显微镜、矿物解离分析仪(MLA)、电子探针,以及化学分析等分析手段对白云鄂博稀土尾矿的化学组成、矿物组成、矿物嵌布特征进行研究.结果表明:尾矿的矿物组成非常复杂,嵌布粒度很细.尾矿中稀土矿物为氟碳铈矿和独居石,铁元素主要赋存于赤铁矿中,氟元素主要赋存在萤石中,这三种矿物解离度较高,分别为87.28%,89.15%,96.70%.尾矿中铌元素主要赋存在烧绿石、铌铁矿、铌铁金红石、钛铁金红石等铌矿物中;钪元素主要分散在硅酸盐矿物中,钍元素主要以类质同象的形式赋存于稀土矿物中.此研究结果对白云鄂博稀土尾矿的高效综合利用具有一定的指导意义.     

一种新宏基因组DNA片段物种属性约简分类方法的研究

由于宏基因组学的迅猛发展,导致可测序的宏基因组数量激增,可测DNA序列也在扩大,但绝大部分DNA序列种属未知,故生物信息学面临的重要课题是研究一种如何针对这些巨大量宏基因组DNA信息属性约简并正确分类的方法.提出采用RandWPSO结合粗糙集的优化算法,分别对宏基因组中的DNA片段在不同属、同属不同种情况下进行属性约简并分类,经实验证明能够进行有效约简可取得较高的分辩准确率.     

采用球面调和函数刻画岩心孔隙形态研究

针对统计特征函数和传统的球面调和函数不能有效刻画岩心三维模型形态特征的问题,提出了一种岩心球面调和函数.首先将三维岩心分解成同心球模型,并根据同心球的不同半径得到一系列的球面函数.然后对生成的球面函数进行调和分析获得形态特征描述子.最后通过相似性判定函数比较形态特征描述子获得不同岩心三维模型的形态相似性.利用多组砂岩岩心样本进行了比较实验,结果表明新算法能够有效描述岩心三维模型的形态特征,并且比统计特征函数和传统的球面调和函数具有更为准确的刻画能力.     

公路对九寨沟县华西箭竹生长状况的影响

为了解公路对大熊猫(Ailuropoda melanoleuca)主食竹生长状况的影响,2014年在四川省九寨沟县大熊猫栖息地内的公路网中,设置距公路不同距离的调查样方,测量华西箭竹(Fargesia nitida)成竹的株高、基径、密度及环境因子等.研究结果显示:在距离道路垂直距离0~500m范围的5个梯度间,华西箭竹的株高、基径无显著差异,但密度差异显著;在0~100m的5个距离组间,华西箭竹的株高、基径和密度均无显著差异.华西箭竹株高、基径、密度与距公路距离均无显著相关性.华西箭竹株高主要与草本高度、苔藓层盖度和腐殖质盖度显著相关,基径主要与苔藓厚度显著相关,密度主要与上层植被盖度和草本层高度显著相关,即箭竹的生长状况主要受环境因子的影响.虽然公路运营对华西箭竹生长状况无显著影响,但公路建设对道路旁的竹类损毁严重,包括人为砍伐、家畜啃食与践踏等.     

非线性分数阶Klein-Gordon方程的新的显式解

本文应用一种新的$(G''/G)$-展开法构建了非线性分数阶Klein-Gordon方程的更多、更一般的精确解.利用分数阶复变换,非线性分数阶Klein-Gordon方程被转化为非线性常微分方程.应用扩展的$(G''/G)$-展开法构建非线性分数阶Klein-Gordon方程精确解.得到了一系列新的显式解,包括双曲函数解,三角函数解和负幂次解,利用该方法获得了比以往更丰富的解.     

高炉风口回旋区内温度分布的模拟分析

基于Fluent软件,采用预混燃烧模型对高炉风口回旋区内温度场进行模拟,分析风量、风压、喷煤量等参数对高炉风口回旋区内温度分布的影响。结果表明,随着风量、风压、喷煤量的增加,风口回旋区内温度最高处离风口端部的距离逐渐增大,风口回旋区内最高温度逐渐降低;风口的堵塞会使风口回旋区内温度最高处与风口端部的距离缩短,使风口回旋区内最高温度升高。     

Reaction mechanism for in-situ β-SiAlON formation in Fe3Si-Si3N4-Al2O3 composites

In this work, Fe₃Si-Si₃N₄-Al₂O₃ composites were prepared at 1300℃ in an N₂ atmosphere using fused corundum and tabular alumina particles, Al₂O₃ fine powder, and ferrosilicon nitride (Fe₃Si-Si₃N₄) as raw materials and thermosetting phenolic resin as a binder. The effect of ferrosilicon nitride with different concentrations (0wt%, 5wt%, 10wt%, 15wt%, 20wt%, and 25wt%) on the properties of Fe₃Si-Si₃N₄-Al₂O₃ composites was investigated. The results show that the apparent porosity varies between 10.3% and 17.3%, the bulk density varies from 2.94 g/cm3 and 3.30 g/cm3, and the cold crushing strength ranges from 67 MPa to 93 MPa. Under the experimental conditions, ferrosilicon nitride, whose content decreases substantially, is unstable; part of the ferrosilicon nitride is converted into Fe₂C, whereas the remainder is retained, eventually forming the ferrosilicon alloy. Thermodynamic assessment of the Si₅AlON₇ indicated that the ferrosilicon alloy accelerated the reactions between Si₃N₄ and α-Al₂O₃ fine powder and that Si in the ferrosilicon alloy was nitrided directly, forming β-SiAlON simultaneously. In addition, fused corundum did not react directly with Si₃N₄ because of its low reactivity.     

Effect of diboron trioxide on the crushing strength and smelting mechanism of high-chromium vanadium-titanium magnetite pellets

The effect of diboron trioxide (B₂O₃) on the crushing strength and smelting mechanism of high-chromium vanadium-titanium magnetite pellets was investigated in this work. The main characterization methods were X-ray fluorescence, inductively coupled plasma-atomic emission spectroscopy, mercury injection porosimetry, X-ray diffraction, metallographic microscopy, and scanning electron microscopy-energy-dispersive X-ray spectroscopy. The results showed that the crushing strength increased greatly with increasing B₂O₃ content and that the increase in crushing strength was strongly correlated with a decrease in porosity, the formation of liquid phases, and the growth and recrystallization consolidation of hematite crystalline grains. The smelting properties were measured under simulated blast furnace conditions; the results showed that the smelting properties within a certain B₂O₃ content range were improved and optimized except in the softening stage. The valuable element B was easily transformed to the slag, and this phenomenon became increasingly evident with increasing B₂O₃ content. The formation of Ti(C,N) was mostly avoided, and the slag and melted iron were separated well during smelting with the addition of B₂O₃. The size increase of the melted iron was consistent with the gradual optimization of the dripping characteristics with increasing B₂O₃ content.