腐殖酸对汞的吸附特性与动力学研究

采用静态吸附法研究了汞在腐殖酸上的吸附特性和动力学特征.结果表明,20℃以下,平衡吸附量随温度的升高而增加,20℃以上,吸附反应受温度的影响却很小.溶液的pH在5～9范围内,具有最高的吸附效率,有利于腐殖酸吸附更大量的汞.吸附过程符合伪二级吸附速率方程,吸附速率常数k2随初始浓度的增加反而减小,这与快吸附反应比例F以及到达F的时间有关.腐殖酸对汞的吸附活化能为20.37kJ/mol,说明吸附反应属于化学吸附过程.     

溶剂热法合成六方氮化硼纳米晶的影响因素研究

以Li_3N和BBr3为原料,采用溶剂热法在220 ℃合成了h-BN纳米晶,研究了反应时间、表面活性剂和诱导晶粒对产物的影响.研究结果表明:反应产物主要为h-BN,同时含有少量c-BN,随着反应时间从12 h延长至36 h,晶粒尺寸从20 nm增大至80 nm;十二烷基苯磺酸钠的引入可以控制产物颗粒尺寸在10 nm左右,并且使球形度得到提高;以h-AlN为诱导晶粒时,产物中六方相含量增加,并且出现了h-BN纳米棒.     

需求弹性在价格决策中的应用

将着眼点由总收益改变为总利润,对于需求弹性用于价格决策,利用微积分方法,分5种情况进行推导,得到的结论修正和补充了现行"经济数学"、"市场营销学"和"管理经济学"等教科书里讲的内容,并在此基础上进一步研究了最佳调价量问题.     

光信息科学与技术专业实践教学的探索

在四年办学经验的基础上,探索了适合地方经济建设的光信息科学与技术的本科专业的实践教学体系,进一步提升了办学水平。     

混沌Arneodo系统的输出反馈同步

对Arneodo混沌系统进行输出线性反馈同步.基于线性稳定性定理,给出了一个同步渐近稳定的充分条件,和同步渐近稳定的反馈系数的范围.对同步系统进行数值仿真,验证了方法的有效性和抗噪声能力. 关键词：     

Sulfur-Containing Bent N-Heteroacenes

A series of novel sulfur-containing bent N-heteroacenes were constructed and characterized by NMR and UV/Vis spectroscopy, cyclic voltammetry, and single-crystal X-ray diffraction. By introducing sulfur-containing groups (thio, sulfinyl, and sulfonyl) into bent azaacenes, their electronic delocalization was improved and frontier energy levels were modulated. The target products displayed tunable optical and electronic properties through altering the valence of sulfur and fused length of the azaacenes. For the first time, typical products were utilized as organic field effect transistor materials, affording promising results.     

A Renormalization Group Study of the Ising Model on a Triangular Lattice with Long-Range Interactions

The critical exponents of the triangular lattice Ising model with long-range interactions γ^-s are calculated by the real space renormalization group. Using the simplest Kadanoff blocks and the lowest approximation of cumulant expansion, it is shown that there exists a finite critical temperature when 4(1 - ㏑2/㏑3) < s < 4.     

数值积分公式中间点的渐近性质及其应用

主要研究了三类数值积分公式的中间点的渐近性质,得到了更一般性的结果.基于中间点的渐近性质,获得了数值积分的校正公式及其条件误差估计.数值例子显示了校正公式的精度明显高于对应的计算公式.     

用于数据挖掘的聚类算法

数据挖掘用于从超大规模数据库中提取感兴趣的信息。聚类是数据挖掘的重要工具,根据数据间的相似性将数据库分成多个类,每类中数据应尽可能相似。从机器学习的观点来看,类相当于隐藏模式,寻找类是无监督学习过程。目前已有应用于统计、模式识别、机器学习等不同领域的几十种聚类算法。该文对数据挖掘中的聚类算法进行了归纳和分类,总结了7类算法并分析了其性能特点。     

Electrochemical Performance of LiMn2O4/LiFePO4 Blend Cathodes for Lithium Ion Batteries

A series of LiMn₂O₄/LiFePO₄ blend cathodes was prepared by hand milling and ball milling in order to compensate the disadvantage of spinel LiMn₂O₄ and olivine LiFePO₄. The morphologies of the blends were studied by scanning electron microscopy, and their electrochemical properties were studied by charge-discharge cycling, cyclic voltammetry and electrochemical impedance spectroscopy. It is easy to obtain uniform LiMn₂O₄/LiFePO₄ blends by the hand milling technique, while significant particle agglomeration is caused by the ball milling technique. When the LiMn₂O₄:LiFePO₄ mass ratio is 1:1, the nano-sized LiFePO₄ powders not only uniformly cover the micron-sized LiMn₂O₄ particles but also effectively fill in the cavities of the LiMn₂O₄ space. Such morphology offers a good electrical contact and a high tap density, which leads to a high discharge capacity and good cycle stability.