Nonlinear interactions of azimuthal surface waves in magnetoactive plasma filled waveguides

This paper deals with the theoretical studies of nonlinear interactions of azimuthal surface waves (ASW) in cylindrical metal waveguides fully filled by a uniform magnetoactive plasma. These surface-type wave perturbations propagate in azimuthal direction across an external magnetic field, which is directed along the waveguide axis. The ASW is a relatively new kind of surface waves and so far the nonlinear effects associated with their propagation are outside the scope of scientific issues. They are characterized by a discrete set of mode numbers values which define the ASW eigenfrequencies. This fact leads to several peculiarities of ASW compared with ordinary surface-type waves.

Space within the surface : the patterned surfaces of Florence Broadhurst and Jim Thompson

The Woods Bagot 2007 refurbishment of the Qantas and British Airways Bangkok Business lounge in the Survarnabhumi Airport features wall finishes designed by wallpaper designer, Florence Broadhurst (1899-1977) and Thai Silk trader, Jim Thompson (1906-1967). This distinctive selection, which is proclaimed on the airport’s website, of patterned wall surfaces side by side draws attention to their striking similarities and their defining differences . Thompson and Broadhurst would appear to be worlds apart, but here in the airport their work brings them together. Thompson, the son of a wealthy cotton family in America, worked as an architect before joining the army. He moved to Bangkok to start The Thai Silk Company in 1948. Broadhurst was born on a farm in Mt. Perry, Queensland. She began her career as a performance artist, as part of an Australian troupe in Shanghai, moving onto pursue a career in fashion design, catering to the middle and upper classes in London. Upon her return to Australia, Broadhurst started a print design company in 1959. Both Broadhurst and Thompson pursued multiple careers, lived many lives, and died under mysterious circumstances. Broadhurst was murdered in 1977 at her Sydney print warehouse, which remains an unsolved crime. Thompson disappeared in Malaysia in 1967 and his body has never been found. This chapter investigates the parallels between Thompson and Broadhurst and what lead them to design such popular patterns for wall surfaces towards the end of their careers. While neither designer was a household name, their work is familiar to most, seen in the costume and set design of films, on the walls of restaurants and cafes and even in family homes. The reason for the popularity of their patterns has not previously been analysed. However, this chapter suggests that the patterns are intriguing because they contain something of their designers’ identities. It suggests that the coloured surface provides a way of camouflaging and hiding its subjects’ histories, such that Broadhurst and Thompson, consciously or unconsciously, used the patterned surface as a plane in which their past lives could be buried. The revealing nature of the stark white wall, compared with the forgiveness provided by the pattern in which to hide, is elaborated by painter and advocate for polychromatic architecture, Fernand Léger in his essay, “The Wall, The Architect, The Painter (1965).” Léger writes that, “the modern architect has gone too far in his magnificent attempts to cleanse through emptiness,” and that the resultant white walls of modernity create ‘an impalpability of air, of slick, brilliant new surfaces where nothing can be hidden any longer …even shadows don’t dare to enter’. To counter the exposure produced by the white wall, Thompson and Broadhurst designed patterned surfaces that could harbour their personal histories. Broadhurst and Thompson’s works share a number of commonalities in their design production, even though their work in print design commenced a decade apart. Both designers opted to work more with traditional methods of pattern making. Broadhurst used hand-operated screens, and Thompson outsourced work to local weavers and refrained from operating out of a factory. Despite humble beginnings, Broadhurst and Thompson enjoyed international success with their wall patterns being featured in a number of renowned international hotels in Bahrain, Singapore, Sydney, and London in the 1970s and 1980s. Their patterns were also transferred to fabric for soft furnishings and clothing. Thompson’s patterns were used for costumes in films including the King and I and Ben Hur. Broadhurst’s patterns were also widely used by fashion designers and artists, such as Akira Isogowa‘s costume design for Salome, a 1998 production by the Sydney Dance Company. Most recently her print designs have been used by skin illustrator Emma Hack, in a series of works painting female bodies into Broadhurst’s patterns. Hack’s works camouflage the models’ bodies into the patterned surface, assimilating subject and surface, hinting at there being something living within the patterned wall. More than four decades after Broadhurst’s murder and five decades since Thompson’s disappearance, their print designs persist as more than just a legacy. They are applied as surface finishes with the same fervour as when the designs were first released. This chapter argues that the reason for the ongoing celebration of their work is that there is the impalpable presence of the creator in the patterns. It suggests that the patterns blur the boundary between subject and surface.

Computational strategies for surface fitting using thin plate spline finite element methods

Thin plate spline finite element methods are used to fit a surface to an irregularly scattered dataset [S. Roberts, M. Hegland, and I. Altas. Approximation of a Thin Plate Spline Smoother using Continuous Piecewise Polynomial Functions. SIAM, 1:208--234, 2003]. The computational bottleneck for this algorithm is the solution of large, ill-conditioned systems of linear equations at each step of a generalised cross validation algorithm. Preconditioning techniques are investigated to accelerate the convergence of the solution of these systems using Krylov subspace methods. The preconditioners under consideration are block diagonal, block triangular and constraint preconditioners [M. Benzi, G. H. Golub, and J. Liesen. Numerical solution of saddle point problems. Acta Numer., 14:1--137, 2005]. The effectiveness of each of these preconditioners is examined on a sample dataset taken from a known surface. From our numerical investigation, constraint preconditioners appear to provide improved convergence for this surface fitting problem compared to block preconditioners.

Effect of chute level on mill capacity

IN MANY FACTORIES, the feed chute of the first mill is operated with a high chute level for the purpose of maximising the cane rate through the mill. There is a trend towards trying to control chute level within a small control range near the top of a chute that can result in rapid changes in cane feeding rate to maintain the chute level set point. This paper reviews the theory that predicts higher cane rate with higher chute level and discusses the main weakness in the theory that it does not consider the beneficial effect on capacity of cane falling from the top of the chute to the top surface of the cane mat. An extension to the chute theory model is described that predicts higher capacity with lower chute level because of the effect of the falling cane. The original model and this extended model are believed to be the upper and lower limits to the true effect. The paper reports an experiment that measured the real effect of chute level on capacity and finds that increasing chute level does lead to higher capacity but that the trend is only about one-third as strong as the original theory predicted. The paper questions whether the benefits of slightly greater capacity outweigh the costs of operating with the small control range near the top of the chute.

Characterisation of the half-field beam penumbra for a variety of blocking set-ups

Measurements of half-field beam penumbra were taken using EBT2 film for a variety of blocking techniques. It was shown that minimizing the SSD reduces the penumbra as the effects of beam divergence are diminished. The addition of a lead block directly on the surface provides optimal results with a 10-90% penumbra of 0.53 ± 0.02 cm. To resolve the uncertainties encountered in film measurements, future Monte Carlo measurements of halffield penumbras are to be conducted.

Mapping Hydrophobicity on the Protein Molecular Surface at Atom-Level Resolution

A precise representation of the spatial distribution of hydrophobicity, hydrophilicity and charges on the molecular surface of proteins is critical for the understanding of the interaction with small molecules and larger systems. The representation of hydrophobicity is rarely done at atom-level, as this property is generally assigned to residues. A new methodology for the derivation of atomic hydrophobicity from any amino acid-based hydrophobicity scale was used to derive 8 sets of atomic hydrophobicities, one of which was used to generate the molecular surfaces for 35 proteins with convex structures, 5 of which, i.e., lysozyme, ribonuclease, hemoglobin, albumin and IgG, have been analyzed in more detail. Sets of the molecular surfaces of the model proteins have been constructed using spherical probes with increasingly large radii, from 1.4 to 20 A˚, followed by the quantification of (i) the surface hydrophobicity; (ii) their respective molecular surface areas, i.e., total, hydrophilic and hydrophobic area; and (iii) their relative densities, i.e., divided by the total molecular area; or specific densities, i.e., divided by property-specific area. Compared with the amino acid-based formalism, the atom-level description reveals molecular surfaces which (i) present an approximately two times more hydrophilic areas; with (ii) less extended, but between 2 to 5 times more intense hydrophilic patches; and (iii) 3 to 20 times more extended hydrophobic areas. The hydrophobic areas are also approximately 2 times more hydrophobicity-intense. This, more pronounced "leopard skin"-like, design of the protein molecular surface has been confirmed by comparing the results for a restricted set of homologous proteins, i.e., hemoglobins diverging by only one residue (Trp37). These results suggest that the representation of hydrophobicity on the protein molecular surfaces at atom-level resolution, coupled with the probing of the molecular surface at different geometric resolutions, can capture processes that are otherwise obscured to the amino acid-based formalism.

An examination of isotherm generation : impact of bottle-point method upon potassium ion exchange with strong acid cation resin

This paper relates to the importance of impact of the chosen bottle-point method when conducting ion exchange equilibria experiments. As an illustration, potassium ion exchange with strong acid cation resin was investigated due to its relevance to the treatment of various industrial effluents and groundwater. The “constant mass” bottle-point method was shown to be problematic in that depending upon the resin mass used the equilibrium isotherm profiles were different. Indeed, application of common equilibrium isotherm models revealed that the optimal fit could be with either the Freundlich or Temkin equations, depending upon the conditions employed. It could be inferred that the resin surface was heterogeneous in character, but precise conclusions regarding the variation in the heat of sorption were not possible. Estimation of the maximum potassium loading was also inconsistent when employing the “constant mass” method. The “constant concentration” bottle-point method illustrated that the Freundlich model was a good representation of the exchange process. The isotherms recorded were relatively consistent when compared to the “constant mass” approach. Unification of all the equilibrium isotherm data acquired was achieved by use of the Langmuir Vageler expression. The maximum loading of potassium ions was predicted to be at least 116.5 g/kg resin.

The development of virtual leaf surface models for interactive agrichemical spray applications

This project constructed virtual plant leaf surfaces from digitised data sets for use in droplet spray models. Digitisation techniques for obtaining data sets for cotton, chenopodium and wheat leaves are discussed and novel algorithms for the reconstruction of the leaves from these three plant species are developed. The reconstructed leaf surfaces are included into agricultural droplet spray models to investigate the effect of the nozzle and spray formulation combination on the proportion of spray retained by the plant. A numerical study of the post-impaction motion of large droplets that have formed on the leaf surface is also considered.

Automated 3D mapping & shape analysis of the lateral ventricles via fluid registration of multiple surface-based atlases

We developed and validated a new method to create automated 3D parametric surface models of the lateral ventricles, designed for monitoring degenerative disease effects in clinical neuroscience studies and drug trials. First we used a set of parameterized surfaces to represent the ventricles in a manually labeled set of 9 subjects' MRIs (atlases). We fluidly registered each of these atlases and mesh models to a set of MRIs from 12 Alzheimer's disease (AD) patients and 14 matched healthy elderly subjects, and we averaged the resulting meshes for each of these images. Validation experiments on expert segmentations showed that (1) the Hausdorff labeling error rapidly decreased, and (2) the power to detect disease-related alterations monotonically improved as the number of atlases, N, was increased from 1 to 9. We then combined the segmentations with a radial mapping approach to localize ventricular shape differences in patients. In surface-based statistical maps, we detected more widespread and intense anatomical deficits as we increased the number of atlases, and we formulated a statistical stopping criterion to determine the optimal value of N. Anterior horn anomalies in Alzheimer's patients were only detected with the multi-atlas segmentation, which clearly outperformed the standard single-atlas approach.

Study of surface evolution in the wheel-rail interface

This paper aims to trace surface evolution in the wheel-rail interface using data obtained from a twin-disc testing machine and the surface replication technique. Changes in the surface profile of the rail testing disc are explicitly analysed according to the wear mechanism, which helps elaborate a better understanding of the attrition of asperities during the wearing-in process of surface modification. The surface profile amplitude was seen to decrease during the initial running-in phase of the experiment cycle, and after reaching a saturation value, the profile amplitude then increased. Ultimately the results show that grinding will roughen the rail surface and the wheel-rail contact conditions will then remove this surface damage to some saturation value of the profile height. The variation in the rail surface profile beyond this point is then only dependant on the contact conditions which exist between the wheel and rail during normal operation.