采用不定Dogleg路径的非单调自适应信赖域算法解无约束极小化(英文)

In this paper, we combine the nonmonotone and adaptive techniques with trust region method for unconstrained minimization problems. We set a new ratio of the actual descent and predicted descent. Then, instead of the monotone sequence, the nonmonotone sequence of function values are employed. With the adaptive technique, the radius of trust region △k can be adjusted automatically to improve the efficiency of trust region methods. By means of the Bunch-Parlett factorization, we construct a method with indefinite dogleg path for solving the trust region subproblem which can handle the indefinite approximate Hessian Bk. The convergence properties of the algorithm are established. Finally, detailed numerical results are reported to show that our algorithm is efficient.     

利用模拟退火遗传算法实现图像阈值分割

本文提出了一种利用模拟退火算法和遗传算法相结合的图像阈值分割算法,试验结果表明该算法增强了算法的全局收敛性,加快了算法的收敛速度,提高了图像阈值分割的效率.     

最优切割次序模型

本文研究了截断切割的最优切割次序模型。利用简单的伸缩变换,我们将r≠1的情况统一到的情况;我们讨论了切割方式的一些性质,如描述互换相邻切割对费用的影响的交换引理,同时在此基础上经严格证明给出了e=0时的一种十分简明的优化准则,每次选择切去长度最长的切割;在e>0的情况下,利用我们给出的引理及准则,我们将需考虑的不同切割方式数由最初的90种减少到不到20种.我们讨论了所建立模型的优缺点,同时也对另一种“加工费用最少者优先”的准则作了简单评估。     

捕食模型高精度参数的估计

研究了捕食者模型在多种观测值条件下的非线性微分方程组参数拟合问题.首先利用龙格-库塔法进行微分方程数值计算,通过首次积分项变形建立线性回归方程,进行最小二乘拟合;其次,考虑到实验数据包含随机误差的扰动,引进正规方程组对模型进行误差分析;最后针对时间变量也出现误差,采用拉依达准则筛选,然后提出了一种较为简单的参数分段动态估计算法.     

粘度法对可溶解的聚氨酯交联大分子的溶液行为的研究

通过体积稀释法测定可溶性交联大分子溶液的特性粘数随交联度、浓度和时间的变化,发现聚氨酯可溶性交联大分子在溶液中出现与线型和支化型高分子溶液不一样的粘度行为.本文根据聚氨酯的特殊的结构对这些异常现象进行了解释.     

Schiff 碱双核配合物的磁性及催化性能的研究

This paper reports the catalytic properties of “porphyrin-like” Schiff base mononuclear complexes MH₂L {M=Mn(Ⅱ), Fe(Ⅲ)Cl, Cr(Ⅲ)Cl, Cu(Ⅱ), Co(Ⅱ), Ni(Ⅱ), Zn(Ⅱ); L=bis[N, N′-ethylene-2, 2′-(phenylmethylene)bis(3,4-dimethylpyrrole-5-aldimino)]} and dinuclear complexes MnML [M=Mn(Ⅱ), Fe(Ⅲ)Cl, Cr(Ⅲ)Cl, Cu(Ⅱ), Co(Ⅱ), Ni(Ⅱ), Zn(Ⅱ)] for cyclohexane monooxygenation with PhIO and magnetic properties of the dinuclear complexes. The magnetic investigations (4～300 K) of the dinuclear complexes revealed that their antiferromagnetic spin exchange with J ranged from -10.49 to -0.482 cm^-1 except MnZnL and antiferromagnetic spin exchange decreased in the following order: Mn^Ⅱ-Cu^Ⅱ > Mn^Ⅱ-Ni^Ⅱ > Mn^Ⅱ-Mn^Ⅱ > Mn^Ⅱ-Fe^Ⅲ > Mn^Ⅱ-Co^Ⅱ > Mn^Ⅱ-Cr^Ⅲ. The results of catalyzed oxidation of cyclohexane indicated that the catalytic property of the dinuclear complex was better than that of the corresponding mononuclear complex. It was found that there was the synergism decreased in the order: Mn-Fe > Mn-Cr > Mn-Cu > Mn-Mn > Mn-Co> Mn-Ni > Mn-Zn. It seems that this synergism increases with the increase of the number of unpaired d electrons and the magnetic exchange between the two metals in these dinuclear complexes.     

凝胶色谱-气相色谱-串联质谱法筛查茶叶中27种禁用农药

建立了茶叶中27种国家禁用农药的气相色谱-串联质谱分析方法。以27种国家禁用农药为目标分析物,样品经环己烷-乙酸乙酯超声提取、凝胶渗透色谱净化后进行定性和定量分析。方法检出限为0.02~2.82μg/kg,方法定量限为0.07~9.40μg/kg,在0.01~0.20 mg/L范围内方法线性相关系数均大于0.991,75%以上的农药的回收率在70%~110%之间,相对标准偏差在0.53%~7.1%之间。方法适用于茶叶中多种农药残留的检测分析。     

Structural transition of FeSe under high pressure

The density functional calculations of the energy band structure and density of state for the tetragonal PbO-type phase α-FeSe and hexagonal NiAs-type phase β-FeSe are reported in this paper. The structural phase transition from tetragonal to hexagonal FeSe under high pressure is investigated, it is found that the calculated transition pressure for the α → β phase transformation is 8.5 GPa. Some fluctuations in the transition pressure maybe occurred by different external factors such as temperature and stress condition. There is about 17% volume collapse accompanying the α → β phase transformation.     

钼酸镉晶体本征点缺陷的计算机模拟计算

本文利用GULP计算软件拟合了CdMoO4晶体势参数,在此基础上研究了该晶体的本征点缺陷,计算了本征点缺陷的生成能.结果表明,在CdMoO4晶体生长过程中,孤立缺陷主要以肖特基缺陷的形式(Vo2+和Vcd2-)存在.晶体中氧的夫伦克儿缺陷具有较低的生成能,是CdMoO4晶体的主要缺陷类型.Cd的夫伦克儿缺陷在高温条件下将起重要作用,由氧空位引起的F心和F+心与700 nm吸收带的形成有关.     

CdMoO4∶W6+晶体电子结构的模拟计算研究

采用基于密度泛函理论的嵌入团簇离散变分方法,计算了CdMoO4∶W6+晶体的电子结构.计算结果显示,在CdMoO4∶W6+晶体的禁带内出现了W的5d施主能态,这说明CdMoO4晶体受激发后出现的峰值在550 nm(2.25ev)的发射带与晶体中的钨类施主离子有关,合理地解释了CdMoO4晶体在500～ 600 nm区间的发射带的起源.