Numerical methods for finding multiple eigenvalues of matrices depending on parameters

Summary. Let be a square matrix dependent on parameters and , of which we choose as the eigenvalue parameter. Many computational problems are equivalent to finding a point such that has a multiple eigenvalue at . An incomplete decomposition of a matrix dependent on several parameters is proposed. Based on the developed theory two new algorithms are presented for computing multiple eigenvalues of with geometric multiplicity . A third algorithm is designed for the computation of multiple eigenvalues with geometric multiplicity but which also appears to have local quadratic convergence to semi-simple eigenvalues. Convergence analyses of these methods are given. Several numerical examples are presented which illustrate the behaviour and applications of our methods. Received December 19, 1994 / Revised version received January 18, 1996     

激光分子束外延方法生长的ZnO薄膜的发光特性

研究了不同温度和不同光激发强度下激光分子束外延方法生长的ZnO薄膜样品的发光性能,发现YAG脉冲激光激发,强度超过一定值时会在长波方向上出现一个新的发光峰,此峰可能起源于电子-空穴的复合。室温下氙灯激发的光谱中可以看到峰值位于381nm的近带边紫外发射峰和位于450nm的强的蓝绿带发射,根据光致发光激发光谱的特征给出了一个简单的蓝光发射模型。对比YAG脉冲激光激发和氙灯激发得到的实验光谱,我们认为不同的光谱特征和样品发光的激发机制有关,紫外峰发射需激发强度超过一定值才能观察到,而蓝带发射则在一定的激发强度下迅速饱和。     

共沉淀法制备Y_2O_2S∶Eu~(3+),Mg~(2+),Ti~(4+)红色长余辉材料

用共沉淀法制备了Y2O2S∶Eu3 ,Mg2 ,Ti4 红色长余辉材料。测量了材料的电子显微形貌、晶体结构和发射光谱。通过与固相法制备的Y2O2S∶Eu3 ,Mg2 ,Ti4 长余辉材料比较,发现两种方法都可以制备粒度基本相同的纯相Y2O2S基质晶体,但共沉淀法样品的颗粒结构更松散。研究了Eu3 浓度对两种方法制备样品的谱线发射强度的影响,通过比较共沉淀法和高温固相法制备的样品中Eu3 的5D1→7F3较高能级跃迁的587.6 nm谱线强度随Eu3 浓度的变化,发现共沉淀法更有利于Eu3 均匀进入Y2O2S基质晶格而形成有效的发光中心。     

The acoustic characteristics of clause, sentence and paragraph boundaries in Chinese Putonghua

The acoustic and perceptive characteristics of discourse units, including clauses, simple sentences, compound sentences and paragraphs, were studied. The acoustic characteristics were based on the analysis of a speech corpus consisted of ten monologues. The Perceived Boundary Strength (PBS) of the monologues was labeled on a five-point scale by 25 participants. The main results are as follows: (1) There is a significant difference in the PBS of clauses (corresponding to intonational phrase), sentences (including simple sentences and compound sentences) and paragraphs. But the PBS of simple sentences and compound sentences is the same, and the pitch reset and pause are also not significantly different between these two kinds of boundaries. (2) The pitch-based cue used to distinguish clauses, sentences and paragraphs appears to be the difference between pre- and post-boundary syllables, but not simply the pitch value of either syllable alone. (3) Declination mainly occurs within intonational phrases, whereas there is no consistent global declination in sentences or in paragraphs. (4) Pauses are longer and more varied at the boundary of larger discourse units. Moreover, there is a significant positive correlation between pause duration and degree of pitch reset at clause boundaries, but not at sentence or paragraph boundaries.     

355nm Nd∶YAG激光在H_2中的高效一级斯托克斯转换

对脉冲Nd∶YAG激光(355 nm)在H2和H2∶He-Ar混合气体中的受激拉曼散射(SRS)进行了研究。在0.5 MPa的氢气中,同时测量到从二级反斯托克斯到三级斯托克斯的多波长输出,其总转化效率达88%;而高压下只剩下一级和二级斯托克斯输出,其中二级斯托克斯最大能量转化效率达44%(对应量子效率为63%)。由于高级斯托克斯的竞争,纯氢气中一级斯托克斯的最大能量转换效率不超过43%。通过向3 MPa氢气中掺入2 MPaAr气后,很好地抑制了二级斯托克斯的产生,从而获得了能量转换效率高达71%(对应量子效率为83%)的一级斯托克斯输出。对四波混频和级联受激拉曼散射在氢气多级斯托克斯产生中的作用以及惰性气体对它们的影响进行了讨论。     

西部开发中能源配置模型的研究

开发西部丰富的能源资源,解决东部地区能源紧缺的矛盾,是东西部经济合作、优势互补、东西联动双赢战略研究的一项重要课题.在国家投资主体和市场经济条件下,以能源消费效益最大为目标,建立了基于边际效益均衡的能源空间配置优化模型;兼顾经济效益与环境效益的能源部门配置优化模型.结果显示,各地区、部门要获得更多的能源,就必须提高能源的使用效率,提高能源消费的边际效益,降低污染排放水平.     

镧系金属一氢化物有效芯势研究

采用Cundari和Stevens等推导的有效芯势对镧系金属一氢化物进行了理论计算，以探讨镧系金属元素与氢的相互作用。结果表明所有镧系金属一氢化物基态时理论上是稳定的，最稳定的是SmH,最不稳定的是DyH;键长计算结果显示，基态时镧系金属一招兵买马花物有独立王国 收缩现象发生；红外振动频率理论计算值与实验结果一致；成键轨道中，金属原子轨道的贡献主要是s轨道和d轨道：从CeH至ErH(GdH)例外）随着外层电子的增加s轨道成分逐渐增大d轨道成分逐渐减小；从TmH和LuH（包括GdH)，成键轨道中金属原子轨道的贡献主要是d轨道，约为90％；约大多数镧系金属一氧化物的成键轨道中金属原子轨道f成分小于1％。     

木质素在塑料中的应用

总结了国内外近10年来木质素在塑料中的应用进展，重点对木质素在PVC、PP、PE、PF、PU等5个方面的研究成果进行了系统阐述，并对该技术的发展方向进行了分析预测。     

《光谱学与光谱分析》2007年征订启事

The authors achieved the temporal coherent control in an Er^3＋ doped telluride glass, one kind of disordered solids. The upconversion at 670 nm was modulated and the dephasing time was simulated as 300 fs. Moreover, the photon echo signal gave the dephasing time due to the phonon interaction. The agreement between the two data indicates that the interaction between the wavepacket and the phonon leads to the fast disappearance of wavepackets interference, which is helpful for the tech- nique to be applied to the disordered solids.     

含外规范场和动力学费米子自能的狄拉克算符及费米子凝聚

将非阿贝尔规范理论中狄拉克算符行列式的计算从传统的只能含有硬费米子质量项的情况推广到可以含有动量相关的费米子自能的情况，并且行列式与费米子凝聚的计算都被推广到使之能够含有任意的外规范场. 关键词： 费米子自能 外规范场 狄拉克算符的行列式 费米子凝聚