Bulk diffusivity of lattice gases close to criticality

We consider lattice gases where particles jump at random times constrained by hard-core exclusion (simple exclusion process with speed change). The conventional theory of critical slowing down predicts that close to a critical point the bulk diffusivity vanishes as the inverse compressibility. We confirm this claim by proving a strictly positive lower bound for the conductivity.     

Effect of Viscous Dissipation on a Quasi-Parallel Free Convection Boundary-Layer Flow over a Vertical Flat Plate in a Porous Medium

Transport in Porous Media -     

临界增长条件下一类半线性椭圆方程解的存在性

用变分方法研究了半线性椭圆方程Dirichlet迫值同题-△μ=f(x,μ） h（x）对几乎所有的x∈Ω，μ=0在δΩ上解的存在性，在临界增长情况下得到了所解的一个存在性定理．     

基于遗传算法的企业风险管理组合模型的分析

本提出了企业关键风险体的概念，建立了基于关联成本和关联收益的风险管理组合净收益模型。并通过一个典型算例详细说明企业风险管理组合选择的标准和过程。实验结果表明该方法具有简单快速准确等特点，对企业的风险管理和决策具有一定的帮助和指导意义。     

Phase Equilibria in a Water-block Copolymer System

Mixtures containing water and a PEO–PPO–PEO block copolymer, i.e. apolyoxyethylene–polyoxypropylene–polyoxyethylene glycol, have been investigated and the phase boundaries determined. The phase diagram shows similarities with non-ionic surfactant systems of the n-alkyl-polyoxyethylene glycol family, with occurrence of different lyotropic liquid crystalline phases and of upper consolute boundaries. Added sodium salts have a pronounced effect on the critical solution boundaries, which can be shifted upwards (downwards), depending on the counterion. A qualitative explanation of the above effects is given in terms of adsorption and/or depletion of the electrolytes at the polar-apolar interface of the aggregates formed by block copolymers. This revised version was published online in July 2006 with corrections to the Cover Date.     

聚苯乙烯的热释电行为

聚苯乙烯的热释电行为盛京，李凤奎（天津大学材料科学与工程系天津３０００７２）关键词聚苯乙烯，松弛现象，热释放电流谱聚苯乙烯（ＰＳ）的松弛过程有大量研究。应用热释电法（ＴＳＣ）研究聚苯乙烯的松弛报道较少［１，２］。无规ＰＳ是典型的非晶态聚合物，它的玻璃...     

Power-law falloff in two-dimensional Coulomb gases at inverse temperature β>8π

We consider two-dimensional Coulomb gases (standard or hard-core) with activityz, and prove that for any >8 the two-point external charges correlation function exhibits the power-law falloff characteristic of the Kosterlitz-Thouless phase at sufficiently low activity.     

自由电子激光对芳香聚酰胺纤维热处理的研究

用红外自由电子激光方法处理芳香聚酰胺纤维.  实验结果表明, 芳香聚酰胺纤维在自由电子激光辐照时在外力拉伸下可出现“缩颈”现象. 红外光谱研究结果表明, 经自由电子激光处理的芳香聚酰胺纤维样品未出现热裂解. 这种方法有可能发展成一种热处理芳香聚酰胺纤维的新方法.     

Morse theory for some lower-C 2 functions in finite dimension

Using inf-regularization methods, we prove that Morse inequalities hold for some lower-C ² functions. For this purpose, we first recall some properties of the class of lower-C ² functions and of their Moreau-Yosida approximations. Then, we establish, under some qualification conditions on the critical points, that it is possible to define a Morse index for a lower-C ² functionf. This index is preserved by the Moreau-Yosida approximation process. We prove in particular that the Moreau-Yosida approximations are twice continuolusly differentiable around such a critical point which is shown to be a strict local minimum of the restriction off and of its approximations to some affine space. In a last step, Morse inequalities are written for Moreau-Yosida approximations and with the aid of deformation retractions we prove that these inequalities also hold for some lower-C ² functions.     

Modelling hydrological data with and without long memory

The paper focuses on the problem of long-range dependence when analysing time series of hydrological data. Three time series are analysed: the monthly rainfall in the town of Florence, Italy; the daily minimum temperatures in the same town; and, finally, the daily water inflow to Lake Maggiore, Italy. Heuristic methods and maximum likelihood estimation of a parametric model are used to investigate the Hurst phenomena and to detect whether long-range dependence is present in any of the time series. We found that long-range dependence is not present in the first series but it is present in the last two. The daily water inflow to Lake Maggiore was modelled by a fractionally differenced arima model (farima) which contains a long-range dependence component. It is shown that the fit is much better than the one provided by more traditional arima models that do not have such a component.

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Sommario Lo studio considera il problema dell'identificazione dei fenomeni di dipendenza a lungo termine (long range dependence) nelle serie temporali di dati idrologici. Allo scopo sono state analizzate tre serie temporali, rispettivamente quella dei totali mensili di precipitazione rilevati alla stazione dell'Osservatorio Ximeniano de Firenze, quella delle temperature minime giornaliere per la stessa stazione e quella degli afflussi giornalieri al Lago Maggiore. Per identificare la presenza di fenomeni di dipendenza long range, attraverso la valutazione della consistenza del fenomeno di Hurst, sono stati utilizzati sia metodi euristici, sia la stima a massima verosimiglianza di un modello parametrico. Due delle tre serie analizzate sono risultate caratterizzate da tale dipendenza. Per la serie degli afflussi al Lago Maggiore, si è inoltre proceduto alla simulazione attraverso un modello arima a differenziazione frazionaria (farima), la cui struttura contiene una componente long-range. I risultati ottenuti, mostrano che tale modello fornisce risultati significativamente migliori dei tradizionali modelli arima, privi di tale componente.