厄尔尼诺和南方涛动海气耦合模型中参数估计的变分方法

提出一种基于变分原理估计厄尔尼诺和南方涛动海气耦合模型中未知参数的方法. 首先将所研究的非线性海气耦合动力方程引入到目标泛函中; 接着利用变分方法导出伴随方程和待辨识参数泛函梯度的公式; 然后设计了估计未知参数的算法.数值试验结果表明变分方法是一 种能有效估计海气耦合非线性系统未知参数的方法.     

A new representation of permittivity versus temperature for alkanols of the same chain length

The alkanols of three carbon length have been studied by dielectric methods during many years and they do not obey any theoretical model. These substances have the same chain length and have one, two or three dipoles per molecule, so their ability to form hydrogen bridges changes from one substance to other, and one can obtain information by comparative studies. In previous works, we have measured the thermal dependence of permittivity of these substances and analysed the results with an empirical modification of the Onsager equation. Now we shall analyse and compare the results using a different representation. In this representation, the data shows straight lines, whose slopes depend on the quantity of dipoles of each molecule encouraging the high quality of the fittings obtained with the three substances, and also that they behave in the same dielectric way with the rise of temperature.     

Röntgenographische Strukturuntersuchung geschmolzener Magnesium-Blei Legierungen

Abstract

Um Aufschluß über die Atomanordnung in geschmolzenen Magnesium-Blei Legierungen zu erhalten, wurden rontgenographische Strukturuntersuchungen durchgeführt.     

Gaussian,non-Gaussian critical fluctuations in the Curie-Weiss model

It is known that at the critical temperature the Curie-Weiss mean-field model has non-Gaussian fluctuations and that internal fluctuations can be Gaussian. Here we compute the distribution of theq-mode magnetization fluctuations as a function of the temperature, the wave vectorq, and a fading out external field. We obtain new classes of probability distributions generated by this external field as well as new critical behavior in terms of its rate of fading out. We discuss also the susceptibility as the limitq tending to zero.     

A mean-field,effective medium theory of random binary alloys III. The ising model with competing interactions

The Ising model with competing interactions is studied in a mean field effective medium approach. The phase diagram of such model alloys is studied. We conclude that for all ratios of the competing interaction moments, a spin glass phase always exists at low temperatures for certain concentration regimes.     

Temperature dependence of the linewidth of the first-order Raman spectra for MnF2 crystal

The first-order Raman spectra ofE _gandA _1g modes in MnF₂ crystal were measured at temperatures from 4.2 to 563 K, and the values of the linewidths obtained. The temperature dependence of the linewidths was analyzed by the phonon dispersion curves based on the rigid ion model, and the result showed that it was caused approximately by the cubic anharmonic term in crystal potential energy.     

The size distribution for theA g RB f−g Model of polymerization

This paper gives the equilibrium distribution of polymer sizes for Flory'sA _g RB _f–g model of polymerization. In this model, the polymers are composed of structural units withg functional groups of the typeA and (f-g) functional groups of the typeB. Reaction is subject to three conditions: (1) Functional groups of the typeA react only with those of typeB, and vice versa. (2) Intramolecular reactions do not occur [and therefore only branched-chain (noncyclic) polymers and formed]. (3) Subject to conditions (1) and (2), all functional groups are equally reactive. The derivation employs Stockmayer's statistical mechanical method (first used on Flory'sRA _f model), coupled with a recursion giving the number of distinct polymers which may be assembled fromk units of theA _g RB _f–g type. We also give distributions for a limiting case of theA _g RB _f–g model, the so-calledA _g RB model. This paper completes the solution of the Smoluchowski coagulation equation (monodisperse case) for the kernelsa _ij =A + B(i +j)+ Cij. The proof will be given in another publication.     

有机层界面对双层有机发光二极管复合效率的影响

建立了双层有机发光二极管中载流子在有机层界面复合的无序跳跃理论模型.由于有机分子材料的空间及能带结构的无序性，采用刚体模型处理有机层界面问题是不恰当的，而采用无序跳跃模型比较合理.复合效率及复合电流由载流子跳跃距离、有机层界面的有效势垒高度及该界面处的电场强度分布所决定：在双层器件ITO/α-NPD/Alq₃/Al中，当所加电压小于19.5V时，复合效率随着载流子跳跃距离的增加而增加，而大于19.5V时，复合效率随着其距离的增加而减少；复合效率随着有机层界面有效势垒高度的增加而增加； 关键词： 有机层界面 双层有机发光二极管 复合效率 有效势垒高度 无序跳跃模型     

Bayesian linear prediction in finite populations

In this paper, Bayesian linear prediction of the total of a finite population is considered in situations where the observation error variance is parameter dependent. Connections with least squares prediction (Royall (1976, J. Amer. Statist. Assoc., 71, 657–664)) in mixed linear models (Theil (1971, Principles of Econometrics, Wiley, New York)), are established. Extensions to the case of dynamic (state dependent) superpopulation models are also proposed.     

最近邻弱交换相互作用对纳米管中Blume-Capel模型热学性质的研究

利用有效场理论研究了纳米管上最近邻弱交换相互作用下spin-1纳米管中Blume-Capel模型的内能、比热和自由能,得到了系统的内能、比热和自由能与最近邻弱交换相互作用和晶场的关系。结果表明：最近邻弱交换相互作用和晶场强度等诸多因素相互竞争,使系统表现出比 = = =1时的BC模型更为复杂的热学性质;系统内能随温度的变化曲线表现出不连续性;比热随温度的变化出现奇异性;高温对自由能的影响更加明显。