Influence of friction on roughening of the matt surface in aluminium pack rolling

A model has recently been presented to simulate inhomogeneous deformation of polycrystalline materials. This model was based on a finite element analysis using an isotropic plasticity model for the material with a distribution of strengths to simulate the crystallographic texture. By considering plane-strain compression of monolithic material, the displacements generated at the midplane successfully provided a prediction of the roughness at the interface of pack-rolled aluminium foil. In the current study, the predictions of the model are explored further. First, the influence of the friction coefficient μ at the interface between the sheets is assessed using a plane-strain compression model of two sheets. It is found that roughness does not depend greatly on μ when μ>0.1, being close to that predicted by the monolithic model. However, the roughness does increases significantly as μ falls below 0.1. Secondly, a plane-strain rolling model is used to clarify the effects of friction between the roll and the strip. It is found that neither the friction at the roll surface nor the roll diameter has a strong effect on the roughening of the internal matt surface. It is concluded that the model using plane-strain compression of monolithic material is appropriate to predict the roughness on the matt surface of pack-rolled materials.     

Choosing cross-over designs when few subjects are available

Cross-over designs are used extensively for experiments in many fields. If the n subjects are relatively scarce compared to the t treatments then universally optimal designs do not exist under these restrictions and a computational procedure is usually required to select the design. This arises, for example, if the subjects comprise several animals which are in short supply, due perhaps to weight or age limitations. It is shown that cyclic cross-over designs are available that have lower average variances for direct and carry-over elementary treatment contrasts than other cyclic cross-over designs described in the literature. Examples of these improved designs are given for typical values of t and n. It is further shown that in these circumstances it is sensible to guard against a choice of design that can become disconnected if a few observations are lost during the experimentation. These points are illustrated in detail by considering the selection of a cross-over design for an experiment involving seven treatments applied to four subjects.     

Systematic approaches to understanding and evaluating design trade-offs

The use of trade-off analysis as part of optimising designs has been an emerging technique for a number of years. However, only recently has much work been done with respect to systematically deriving the understanding of the system problem to be optimised and using this information as part of the design process. As systems have become larger and more complex then a need has arisen for suitable approaches. The system problem consists of design choices, measures for individual values related to quality attributes and weights to balance the relative importance of each individual quality attribute. In this paper, a method is presented for establishing an understanding of a system problem using the goal structuring notation (GSN). The motivation for this work is borne out of experience working on embedded systems in the context of critical systems where the cost of change can be large and the impact of design errors potentially catastrophic. A particular focus is deriving an understanding of the problem so that different solutions can be assessed quantitatively, which allows more definitive choices to be made. A secondary benefit is it also enables design using heuristic search approaches which is another area of our research. The overall approach is demonstrated through a case study which is a task allocation problem.     

A critical review of magnetic recording materials

A review of the methods of preparation and the relevant properties of materials which the authors consider suitable for incorporation in conventional magnetic recording surfaces such as tapes, disks, drums, strips, and cards is provided. This field is presently dominated by one material, gamma ferric oxide in fine particle form, and so it is not surprising that this material is discussed at greater length than its potential rivals. The reasons for this dominance are considered and found to be 1) the ability of gamma ferric oxide recording surfaces to perform adequately in the recording systems which have been developed so far, i.e., the magnetic properties of the oxide have apparently not been the limiting factors in the performance of recording systems; 2) the relative cheapness of the particles; 3) the existence of suitable binder systems of proven durability; and 4) the need for compatibility with existing recording devices.     

Specific muscle identities are regulated by Krüppel during Drosophila embryogenesis

During Drosophila embryogenesis, mesodermal cells are recruited to form a complex pattern of larval muscles. The formation of the pattern is initiated by the segregation of a special class of founder myoblasts. Single founders fuse with neighbouring nonfounder myoblasts to form the precursors of individual muscles. Founders and the muscles that they give rise to have specific patterns of gene expression and it has been suggested that it is the expression of these founder cell genes that determines individual muscle attributes such as size, shape, insertion sites and innervation. We find that the segmentation gene Krüppel is expressed in a subset of founders and muscles, regulates specific patterns of gene expression in these cells and is required for the acquisition of proper muscle identity. We show that gain and loss of Krüppel expression in sibling founder cells is sufficient to switch these cells, and the muscles that they give rise to, between alternative cell fates.     

A comparison of cognitive impairments in dementia of the Alzheimer type and depression in the elderly

General cognitive function and specific language and memory processing abilities were compared in dementia of the Alzheimer type (DAT), depressed and normal control subjects. Several tests clearly differentiated between DAT and depressed subjects including a verbal fluency task, several components of a word memory test, an IQ deterioration index, and the Mini-Mental State Examination. The inability of DAT subjects to take advantage of semantic cues in both the verbal fluency and in the memory test contrasted with the performance of depressed and normal subjects, who were able to benefit from semantic cues. Depressed patients displayed deficits compared with normal controls on the more effortful verbal fluency task but not on the memory test. Tasks that are least effortful, rely on semantic associations, and require declarative memory are most likely to discriminate between DAT and depression.     

Diffusion creep and superplasticity in aluminium alloys

The plastic deformation of two classes of fine-grained aluminium alloys at elevated temperatures and slow strain rates have been investigated. One class of material, Al–Cu–Zr, was processed to develop banded microstructures; the other class, based on Al–(Mg)–Mn, had near-equiaxed microstructures. In both classes, superplastic behaviour was found in the variants with the higher solute content. The evolution of the banded microstructures and the results from surface grid measurement in the Al–(Mg)–Mn alloys give results which indicate that the superplasticity is primarily a result of diffusion creep, and the effect of solute is proposed to be via an enhancement of solvent self-diffusion.     

Positive and negative emotion enhances the processing of famous faces in a semantic judgment task.

Previous work has consistently reported a facilitatory influence of positive emotion in face recognition (e.g., D’Argembeau, Van der Linden, Comblain, & Etienne, 2003). However, these reports asked participants to make recognition judgments in response to faces, and it is unknown whether emotional valence may influence other stages of processing, such as at the level of semantics. Furthermore, other evidence suggests that negative rather than positive emotion facilitates higher level judgments when processing nonfacial stimuli (e.g., Mickley & Kensinger, 2008), and it is possible that negative emotion also influences latter stages of face processing. The present study addressed this issue, examining the influence of emotional valence while participants made semantic judgments in response to a set of famous faces. Eye movements were monitored while participants performed this task, and analyses revealed a reduction in information extraction for the faces of liked and disliked celebrities compared with those of emotionally neutral celebrities. Thus, in contrast to work using familiarity judgments, both positive and negative emotion facilitated processing in this semantic-based task. This pattern of findings is discussed in relation to current models of face processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Design and implementation of an interactive test bed

An interactive test bed for programs written in the system development language CLSD is described. It consists of a compiler and an interactive interpreter. The test facilities and the internal design of the test and bed are described in detail. Experience has demonstrated this to be a very valuable tool in program development.