An experimental approach to the study of the sedimentation of dispersed particles in a centrifugal field

Summary  On the basis of an especially developed centrifuge, a PC-controlled separation analyser has been assembled for the continuous registration of particles' sedimentation process in a fluid, caused by centrifugal acceleration. The system enables the parallel investigation of up to eight samples. During the centrifugation, the radial and temporal variation of light transmission through the samples is registered by means of a CCD line detector. Experiments were carried out with the separation analyser on manipulated rigid and sphered red blood cells for the verification of an established one-dimensional mixture fluid model. In particular, the influence of particle volume concentration as well as of the angular velocity on the sedimentation process was investigated. Justification could be furnished for the one-dimensional model based on the theory of kinematic waves and shocks. In addition, an algorithm has been developed for the experimental determination of the suspension's effective or apparent viscosity. Received 20 March 2001; accepted for publication 23 August 2001 RID=" ID=" This work is an abridged version of a part of the first author's PhD thesis. The study was supported in part by the German Federal Ministry of Education and Research (project 03 TOU 2063) and the foundation Deutsche Forschungsgemeinschaft (project Le 734/1–2).     

Almost Sure Local Limit Theorems with Rate

We establish almost sure versions, with rate, of the local limit theorem for lattice distributed random variables. We also prove a new delicate correlation inequality for sums of i.i.d. lattice distributed random variables.     

Multilevel Additive Schwarz Method for the Version of the Galerkin Boundary Element Method

We study a multilevel additive Schwarz method for the - version of the Galerkin boundary element method with geometrically graded meshes. Both hypersingular and weakly singular integral equations of the first kind are considered. As it is well known the - version with geometric meshes converges exponentially fast in the energy norm. However, the condition number of the Galerkin matrix in this case blows up exponentially in the number of unknowns . We prove that the condition number of the multilevel additive Schwarz operator behaves like . As a direct consequence of this we also give the results for the -level preconditioner and also for the - version with quasi-uniform meshes. Numerical results supporting our theory are presented.

     

An alternative synthesis of a sex pheromone of the dry bean beetleCallosobruchus analis

A formal total synthesis of 3-methylhept-2(Z)-enoic acid, a sex pheromone of the dry bean beetleCallosobruchus analis, was performed on the basis of a highly stereoselective version of the Peterson olefination of ketones developed previously by the authors. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1389–1392, July, 1999.     

Improving microwave brightness temperature predictions based on Bayesian model averaging ensemble approach

The choices of the parameterizations for each component in a microwave emission model have significant effects on the quality of brightness temperature (T _b) simulation. How to reduce the uncertainty in the T _b simulation is investigated by adopting a statistical post-processing procedure with the Bayesian model averaging (BMA) ensemble approach. The simulations by the community microwave emission model (CMEM) coupled with the community land model version 4.5 (CLM4.5) over mainland China are conducted by the 24 configurations from four vegetation opacity parameterizations (VOPs), three soil dielectric constant parameterizations (SDCPs), and two soil roughness parameterizations (SRPs). Compared with the simple arithmetical averaging (SAA) method, the BMA reconstructions have a higher spatial correlation coefficient (larger than 0.99) than the C-band satellite observations of the advanced microwave scanning radiometer on the Earth observing system (AMSR-E) at the vertical polarization. Moreover, the BMA product performs the best among the ensemble members for all vegetation classes, with a mean root-mean-square difference (RMSD) of 4K and a temporal correlation coefficient of 0.64.     

ENDF/B-VIII.β与ENDF/B-VII.1中水的热中子散射截面数据对比分析

以常见的慢化剂材料轻水为例,分析了ENDF/B评价库中两个版本ENDF/B-VⅢ.β与之前ENDF/BVⅡ.1中热中子散射截面数据的差异。由于ENDF/B-VⅢ.β与ENDF/B-VⅡ.1等两个版本中热中子散射截面的温度不尽相同,为定量分析同一温度下二者的差异,通过插值方法得到了任意温度下的热中子散射截面数据。对比发现,二者在同一温度下的热中子散射数据存在差异。相对于ENDF/B-VⅡ.1评价库版本而言,基于ENDF/B-VⅢ.β评价库版本加工得到的束缚在水中的氢的热中子散射截面与ENDF/B-VⅡ.1存在较为明显的差异,两个版本给出的低温情况下的中子与靶核碰撞后的平均散射角余弦在热区的低能段出现极小的负值。此外,当温度高于室温时,在热区的低能段ENDF/B-VⅢ.β给出的平均次级中子能量要稍大于ENDF/B-VⅡ.1给出平均次级中子能量。This work takes the traditional moderator material H₂O for example, the differences between ENDF/B-VⅢ.β and ENDF/B-VⅡ.1 versions from the ENDF/B nuclear evaluated library are analyzed. In order to compare the thermal neutron scattering data between ENDF/B-VⅢ.β and ENDF/B-VⅡ.1 versions under the same temperature, the interpolation method is used to obtain the thermal neutron scattering data under arbitrary temperatures. There are some differences between ENDF/B-VⅢ.β and ENDF/B-VⅡ.1 versions, the thermal neutron scattering cross sections of H bound in H₂O within ENDF/B-VⅢ.β is different with that of ENDF/B-VⅡ.1, the scattering angle cosines of the neutron and target nuclei from the two libraries are slightly smaller than zero in lower energy range within thermal range. Moreover, the second scattering energy spectrum from ENDF/B-VⅢ.β is slightly harder than that from the ENDF/B-VⅡ.1 in higher energy range within thermal range when the temperature is higher than room temperature.     

A General Version of Standard Basis and its Application to T-Ideals

A very general version of standard basis is introduced. It covers a wide range of applications using this notion. Particularly, the standard basis of T-ideal in a free associate algebra is presented and a new variant of Spechts problem (concerning PI-algebras) is formulated. A strengthening of the Spechts conjecture is proved for nonmatrix finitely generated algebras. Mathematics Subject Classifications (2000) 16R10, 16Z05.     

Finite element solutions for three‐dimensional elliptic boundary value problems on unbounded domains

The finite element (FE) solutions of a general elliptic equation ?div([a_ij] ??u) + u = f in an exterior domain Ω, which is the complement of a bounded subset of R ³, is considered. The most common approach to deal with exterior domain problems is truncating an unbounded subdomain Ω_∞, so that the remaining part Ω_B = Ω\Ω _∞ is bounded, and imposing an artificial boundary condition on the resulted artificial boundary Γ_a = Ω _∞ ∩ Ω _B. In this article, instead of discarding an unbounded subdomain Ω_∞ and introducing an artificial boundary condition, the unbounded domain is mapped to a unit ball by an auxiliary mapping. Then, a similar technique to the method of auxiliary mapping, introduced by Babu?ka and Oh for handling the domain singularities, is applied to obtain an accurate FE solution of this problem at low cost. This method thus does have neither artificial boundary nor any restrictions on f. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006     

On Strassen's version of the law of the iterated logarithm for the two-parameter Gaussian process

Strassen's version of the law of the iterated logarithm is extended to the two-parameter Gaussian process {X(s, t); ε(s, t) [0, ∞)²} with the covariance function R((s₁,t₁),(s₂,t₂)) = min(s₁,s₂)min(t₁,t₂).