Stability of a twisted Plateau border with line tension and bending stiffness

The stability of a Plateau border between three soap films is considered, taking into account the effects of line tension and bending stiffness in the border. A simple geometry is considered, in which the border initially lies in equilibrium along the axis of a circular cylinder, with three equally-spaced films radiating outwards to meet the inside wall of the cylinder. The films are pinned at the two ends of the cylinder with a fixed relative twist, so the initial film surfaces are helicoids. The stability of this system to small perturbations, involving both the films and the border, is investigated as a function of the cylinder aspect ratio, twist angle, film surface tension, border line tension, and border bending stiffness. Analytically, the stability problem is reduced to finding the first occurrence of a zero eigenvalue of an infinite matrix, which is then estimated numerically. The results from this calculation are in good agreement with full numerical simulations

Stability of a helicoidal surface inside a cylinder with pinned diameters

A mathematical analysis is presented of the stability of a soap film with uniform surface tension when stretched between two diameters on the inside of a circular cylinder. The stability boundary is found as a critical twist angle θ between the two diameters, as a function of the aspect ratio l of the cylinder. Numerical and asymptotic results agree well with previous numerical simulations and experiments by Cox & Jones (J.\ Engr Math, 2014, 86, 1-7). Their hypothesis that the stability boundary for the multiple-vane case is identical to the single film case is confirmed. It is also shown that two distinct instability mechanisms operate. For moderate and small θ/l, the instability is driven by the decrease in area caused by the film moving to an off-diameter position. But for larger θ/l (more twisted films), the decrease in area is dominated by an internal rearrangement of the surface. The latter mechanism is more relevant to Plateau borders in foams, and our results indicate that straight Plateau borders should be stable at any length provided the total twist is less than π/√2

Web-based manipulation of multiresolution micro-CT images

Micro Computed-Tomography (mu-CT) scanning is opening a new world for medical researchers. Scientific data of several tens of gigabytes per image is created and usually requires storage on a common server such as Picture Archiving and Communication Systems (PACS). Previewing this data online in a meaningful way is an essential part of these systems. Radiologists who have been working with CT data for a long time are commonly looking at two-dimensional slices of 3D image stacks. Conventional web-viewers such as Google Maps and Deep Zoom use tiled multiresolution-images for faster display of large 2D data. In the medical area this approach is being adapted for high resolution 2D images. Solutions that include basic image processing still rely on browser external solutions and high-performance client-machines. In this paper we optimized and modified Brain Maps API to create an interactive orthogonal-sectioning image viewer for medical mu-CT scans, based on JavaScript and HTML5. We show that tiling of images reduces the processing time by a factor of two. Different file formats are compared regarding their quality and time to display. As well a sample end-to-end application demonstrates the feasibility of this solution for custom made image acquisition systems

Integration of chargeable web services into engineering applications

We discuss an engineering case-study in which we address the issues of integration and secure consumption of a specialist software package for finite element meshing through a web service based interface. This work focuses on demonstrating the end-to-end requirements of a framework allowing the transparent integration of the web service into the design workflow of an engineering user. After detailing an example engineering problem, we discuss server-side issues and required modules such as local accounting, security and resource management which provide a sample framework for a chargeable web service. We then demonstrate how the client can easily interface to and consume the web service from within the engineering scripting language Matlab

Grid-enabled electromagnetic optimisation (GEM) for industrial use.

We have developed a tool for parametric electromagnetic design studies using industrial analysis code for the design search and optimisation of photonic crystals. This software tool allows engineering users to transparently access Grid compute components for an end-to-end design of a photonic device using computational electromagnetics. In this paper, we give an overview of the industrial application background, present some aspects of the interface developed, and discuss some of the issues involved in the computational tasks and the storage of metadata

Using the MEAN Stack to implement a RESTful service for an Internet of Things Application

This paper examines the components of the MEAN development stack (MongoDb, Express.js, Angular.js, & Node.js), and demonstrate their benefits and appropriateness to be used in implementing RESTful web-service APIs for Inter- net of Things (IoT) appliances. In particular, we show an end- to-end example of this stack and discuss in detail the various components required. The paper also describes an approach to establishing a secure mechanism for communicating with IoT devices, using pull-communications