Nanostructured Ion-Selective MCM-48 Membranes

Templated MCM-48 silica was prepared using CTAB as surfactant. The MCM-48 powders and thin films were characterized by different techniques. MCM-48 layers were deposited on macroporous α-alumina supports and silicon nitride microsieves. The water permeability of MCM-48 was compared with the permeability of conventional mesoporous γ-alumina membranes. The applicability of MCM-48 as ion-selective electric field-driven switchable interconnect for microfluidic devices was demonstrated.     

Picosecond control of coherent magnetisation dynamics in permalloy thin films by picosecond magnetic field pulse shaping

We have measured the response of a 20×10 μm, 8 nm thin NiFe (80:20) permalloy film due to excitation by short in-plane magnetic field pulses. We will show that using a two-pulse-technique a complete control of the precessional motion of the magnetisation can be achieved on picosecond timescales. Furthermore, we will present numerical calculations which show that a complete suppression of magnetisation ringing after switching can only be realised by a cascade of short field pulses.     

Small silver particles in glass surface layers produced by sodium-silver ion exchange — their concentration and size depth profile

Small spherical silver particles in a surface layer of commercial flat glass were produced by means of sodium-silver ion exchange. In each volume element of the layer there is a Gaussian distribution of the particle diameters. The mean diameter increases with penetration depth. Within one individual sample it can vary from 4.5 nm immediately at the glass surface up to more than 50 nm at the end of the layer. Due to a special preparation technique the results were gained by microspectrophotometric measurements as well as by investigations carried out with the transmission electron microscope and the electron-probe microanalyzer on one and the same sample always as function of the penetration depth.     

Parallel processing of remotely sensed data: Application to the ATSR-2 instrument

Massively parallel computational paradigms can mitigate many issues associated with the analysis of large and complex remotely sensed data sets. Recently, the Beowulf cluster has emerged as the most attractive, massively parallel architecture due to its low cost and high performance. Whereas most Beowulf designs have emphasized numerical modeling applications, the Parallel Image Processing Environment (PIPE) specifically addresses the unique requirements of remote sensing applications. Automated, parallelization of user-defined analyses is fully supported. A neural network application, applied to Along Track Scanning Radiometer-2 (ATSR-2) data shows the advantages and performance characteristics of PIPE.     

Mesophase behaviour of 2,5-dibenzoyloxy-p-benzoquinone derivatives and tetrahydrobenzene tetraesters

The synthesis of 2,5-dibenzoyloxy-p-benzoquinone derivatives, their products after reduction and tetraesters from tetrahydroxybenzene prepared from those products is described. Their phase behaviour was investigated by differential scanning calorimetry and polarizing microscopy and is discussed in terms of their detailed structure.     

Many-neighbour interaction and non-locality in traffic models

The optimal-velocity model, as proposed by Bando et al. [1], shows unrealistic values of the acceleration for various optimal-velocity functions [2,3]. We discuss different approaches of how to correct this problem. Multiple look-ahead (many-neighbour interaction) models are the most promising candidates in reducing accelerations and decelerations to realistic values. We focus on two such models and, in particular, their linear stability and how these affect the vehicle dynamics and wave solutions. As found earlier [4], multiple look-ahead models reproduce many real flow features, and our results further support the necessity of this ansatz. However, the problem of non-locality arises when they are transformed into the corresponding continuum model. We discuss three methods of how to interpret many-neighbour interaction in macroscopic models.Received: 27 March 2004, Published online: 12 July 2004PACS: 45.70.Vn Granular models of complex systems; traffic flow - 89.90. + n Other topics in areas of applied and interdisciplinary physics - 47.50. + d Non-Newtonian fluid flows     

Highly edge‐connected detachments of graphs and digraphs

Let G = (V,E) be a graph or digraph and r : V → Z₊. An r‐detachment of G is a graph H obtained by ‘splitting’ each vertex ν ∈ V into r(ν) vertices. The vertices ν₁,…,ν_r(ν) obtained by splitting ν are called the pieces of ν in H. Every edge uν ∈ E corresponds to an edge of H connecting some piece of u to some piece of ν. Crispin Nash‐Williams 9 gave necessary and sufficient conditions for a graph to have a k‐edge‐connected r‐detachment. He also solved the version where the degrees of all the pieces are specified. In this paper, we solve the same problems for directed graphs. We also give a simple and self‐contained new proof for the undirected result. © 2003 Wiley Periodicals, Inc. J Graph Theory 43: 67–77, 2003     

Pricing and distributed QoS control for elastic network traffic

We study a processor-sharing model in which users choose between a high- and a low-priority service, based on their utility functions and prices charged by the service provider. The latter aims at revenue maximization. The model is motivated by file transmissions in data networks with distributed congestion control.