求解分段常数图象分割模型的一个快速算法

针对Xue-ChengTai等提出的分段常数图象分割模型,我们提出了一个新的快速求解算法。通过引进一个函数来选择模型中的正则化参数β的值,并判断在迭代过程中何时求解不含惩罚项的泛函F。此函数的引入有效地加速了算法的收敛速度。结合原始-对偶Newton方法来求解总变差最小化问题。数值试验表明新算法具有很快的收敛速度与良好的分割效果,且算法对初始值的要求不高。     

含Nb微合金钢应变诱导析出的模拟

基于物理冶金原理建立了微合金钢在热轧过程中流变应力、回复、再结晶和析出模型，模拟了含Nb微合金钢Nb（C,N）析出动力学，并利用Thermo-Calc软件计算了不同条件下析出粒子形核驱动力和元素平衡含量值，同时考虑了回复和再结晶对析出的影响.计算结果表明，该模型对含Nb微合金钢在不同热轧形变条件下模拟结果与实验结果符合较好，因此可以有效预测在不同热轧形变条件下析出粒子体积分数和析出粒子尺寸. 关键词： 微合金钢 位错密度 回复 再结晶     

紫外分光光度法同时测定柠檬黄和日落黄

采用紫外分光光度法同时对饮料中柠檬黄、日落黄两种食用合成色素进行测定,确定了各色素的最大吸收波长λmax,及其最大吸收波长处的吸收系数a和摩尔吸收系数ε.结果表明:柠檬黄在λmax=426nm处的吸收系数为a=33.45 L·g-1,摩尔吸收系数为ε=1.79×104L·mol-1·cm-1.日落黄在λ=481nm处的吸收系数为a=34.00 L·g-1·cm-1,摩尔吸收系数为ε=1.54×104L·mol-1.cm-1.测定饮料中柠檬黄、日落黄含量分别为0.0067mg/mL,和0.0033mg/mL,相对标准偏差(RSD)分别为0.148%、1.026%,测定了两种色素在奥地利饮料中的回收率分别为:92.35%、96.77%.该方法操作简便,同时准确度高,精密度好.     

Experimental demonstration and cascadability analysis of a tunable optical buffer based on a re-circulating loop consisting of optical SSB modulator and FBG filter

We demonstrate a tunable optical buffer with variable time delays for label switching applications using an optical single sideband modulator in a fiber Bragg grating-filter loop. This optical buffer realizes payload storage with optional wavelength conversion function, providing flexibility in packet router design. Small sensitivity penalty is observed in our experiment after the payload circulating in the buffer loop three times. The cascadability of the tunable optical buffer is investigated. We provide analysis of the optical signal to noise ratio degradation due to accumulated amplified spontaneous emission noise, and the penalty caused by loss ripple and group delay ripple of the fiber Bragg grating.     

Non-equivalence of Faddeev-Jackiw method and Dirac-Bergmann algorithm and the modification of Faddeev-Jackiw method for keeping the equivalence

From the angle of the calculation of constraints, we compare the Faddeev-Jackiw method with Dirac-Bergmann algorithm, study the relations between the Faddeev-Jackiw constraints and Dirac constraints, and demonstrate that Faddeev-Jackiw method is not always equivalent to Dirac method. For some systems, under the assumption of no variables being eliminated in any step in Faddeev-Jackiw formalism, except for the Dirac primary constraints, we are possible to get some Dirac secondary constraints which do not appear in the corresponding Faddeev-Jackiw formalism, which will result in the contradiction between Faddeev-Jackiw quantization and Dirac quantization. At last, accordingly, we propose a modified Faddeev-Jackiw method which keeps the equivalence between Dirac-Bergmann algorithm and Faddeev-Jackiw method. However, one point must be stressed that the Faddeev-Jackiw method and quantization in this paper is these mentioned in [J. Barcelos-Neto, C. Wotzasek, Mod. Phys. Lett. A 7 (1992) 1737], not the initial Faddeev-Jackiw method mentioned in [L. Faddeev, R. Jackiw, Phys. Rev. Lett. 60 (1988) 1692], which is completely on basis of Darboux transformation, and must have the elimination of variables in every step of that, so it is reasonable that the constraints in this Faddeev-Jackiw method is fewer than the Dirac secondary constraints. Thus, we overcome the difficulty of the Non-equivalence of the Faddeev-Jackiw method and Dirac-Bergmann algorithm, and make the equivalence of the Faddeev-Jackiw method and Dirac-Bergmann algorithm restored.     

Attosecond pulse extreme-ultraviolet photoionization in a two-color laser field

Attosecond-pulse extreme-ultraviolet (XUV) photoionization in a two-color laser field is investigated. Attosecond pulse trains with different numbers of pulses are examined, and their strong dependence on photoelectronic spectra is found. Single-color driving-laser-field-assisted attosecond XUV photoionization cannot determine the number of attosecond pulses from the photoelectronic energy spectrum that are detected orthogonally to the beam direction and the electric field vector of the linearly polarized laser field. A two-color-field-assisted XUV photoionization scheme is proposed for directly determining the number of attosecond pulses from a spectrum detected orthogonally.     

Studies of some bioactive N-p-methacrylamidobenzoic esters

Preparations of four typical bioactive esters of N-p-methacrylamidobenzoic monomers and their reactive polymers as immobilized trypsin carriers are described. N-p-methacrylamidobenzoic active ester monomers containing ? COONB, ? COOSu, ? COOObt, or ? COOBT group can react with an aliphatic amine such as benzylamine at room temperature to give an identical product, N-benzyl-p-methacrylamidobenzamide. However, only monomers with ? COOObt or ? COOBT group can also react with an aromatic amine such as aniline to give N-phenyl-p-methacrylamidobenzamide. These monmoers polymerized readily in solution with azobisisobutyronitrile as free-radical initiator; the polymers were used to immobilize trypsin. Among the four different active esters for the immobilization of trypsin, thE HONB and HOSu active ester showed rather higher bioactivities than the HOObt or HOBT active ester under the same conditions. Both P(MABONB)-trypsin and P(MABOSu)-trypsin matrices possess higher biological activities by about four or three times that of P(MABOObt)-trypsin or P(MABOBT)-trypsin matrices, respectively. It is proposed that these rather high bioactivities may be attributed to the “specific” aminolysis of reactive polymer with ? COONB or ? COOSu active ester group by aliphatic amino substituents.     

团簇WOS3Cu3I(2-MePy)3激发态非线性光学性质

用Z扫描方法测量了团簇WOS3Cu3I(2 MePy) 3对 5 32nm、8ns激光脉冲的非线性光学响应曲线。以速率方程为基础对实验结果进行拟合 ,理论计算和实验结果符合得很好。应用激发态折射理论研究了非线性折射率系数的符号变化和折射度比值Kr 的关系 ,Kr>1时非线性折射率系数为正 ,Kr<1时折射率系数为负。