Trench stability under bentonite pressure in purely cohesive clay

Trench stability is a conventional geotechnical problem; however, current evaluations are often based entirely on empiricism. This paper uses numerical finite-element upper and lower bound limit analysis to produce stability charts for two-dimensional and three-dimensional homogeneous and inhomogeneous undrained diaphragm wall trenches. Using the limit theorems cannot only provide a simple and useful way of analyzing the stability of the trench, but also avoid the shortcomings and arbitrary assumptions underpinning the limit equilibrium method. By considering the effects from the bentonite slurry pressures, the collapse load in this study has been bracketed to within ±8.5 or better by the numerical upper and lower bound limit analyses. The chart solutions can be used to predict either the critical depth or the safety factor of the trench and provide a convenient tool for preliminary designs by practicing engineers. © 2014 American Society of Civil Engineers.

Construction of extrusion limit diagram for AZ31 magnesium alloy by FE simulation

The maximum speed at which magnesium can be extruded is considerably slower than that of many common aluminium extrusion alloys. This affects both the economies of production and the final mechanical behaviour. The present work quantifies the limiting extrusion speeds and ratios of magnesium alloy AZ31 as a function of billet temperature. This is done by combining hot compression test results, FE simulations and extrusion trials. Hot working stress–strain curves displayed a distinct dynamic recrystallisation peak. These data were used as a “look-up” table for the FE simulations in which the cracking limit was assumed to occur when the surface temperature reaches the incipient melting point. The maximum extrusion ratio predicted using FE analysis dropped from 90 to 40 when the extrusion ram speed was raised from 5 to 50 mm/s. The predicted limits agree well with the occurrence of cracking in both a laboratory and a commercial extrusion trial.

When does physiology limit the foraging behaviour of freely diving mammals?

Diving animals offer a unique opportunity to study the importance of physiological constraint and the limitation it can impose on animal's behaviour in nature. This paper examines the interaction between physiology and behaviour and its impact on the diving capability of five eared seal species (Family Otariidae; three sea lions and two fur seals). An important physiological component of diving marine mammals is the aerobic dive limit (ADL). The ADL of these five seal species was estimated from measurements of their total body oxygen stores, coupled with estimates of their metabolic rate while diving. The tendency of each species to exceed its calculated ADL was compared relative to its diving behaviour. Overall, our analyses reveal that seals which forage benthically (i.e. on the sea floor) have a greater tendency to approach or exceed their ADL compared to seals that forage epipelagically (i.e. near the sea surface). Furthermore, the marked differences in foraging behaviour and physiology appear to be coupled with a species demography. For example, benthic foraging species have smaller populations and lower growth rates compared to seal species that forage epipelagically. These patterns are relevant to the conservation and management of diving vertebrates.

No limits : exploring the psychology of unsolicited credit card limit increase offers

The issue of credit card debt has become an increasing concern in recent years. In Australia, for example, there is currently $42.5 billion worth of outstanding debt on credit cards, with $30 billion (over 70 per cent) bearing interest. Further, in 2001, Visa reported that 32 per cent of consumers had not paid their card off in the previous 12 months, which suggests that interest-bearing debt in Australia is held by approximately only 113 of credit card borrowers. An important element of credit card marketing is the use of psychological manipulations to encourage consumers to take-up credit. In this article, we examine the use of language and imagery in unsolicited credit card limit increase offers, and how these might influence consumers' decisions to increase their credit card limit. The analysis found that the use of terms that focused on the benefits of credit card use, such as "choice", "freedom", and "peace of mind" were used consistently to convince consumers to increase their credit card limit, whereas the use the of terms that could be considered more pragmatic and with direct reference to the nature of the product, such as "debt", "repayment" and "loan", were rarely used. Similarly, the use of colour, text changes, and images, were used which may have an influence over a consumer's ability to rationally consider whether the increase is appropriate for them. The paper concludes by recommending that government and representative bodies need to take into account the psychological manipulations used by credit card providers when developing consumer policy and codes of ethics.

Congratulations, you're pre-approved! : an analysis of credit limit upselling letters

Consumer Action commissioned Dr Paul Harrison, Deakin Business School, Deakin University and Marta Massi, School of Marketing and Communication, Lumsa University (Rome), to study the psychological aspects of one form of credit marketing – unsolicited credit card limit-increase offers (UCCLIOs). The researchers studied 21 UCCLIO letters – 17 provided by consumers and four provided by banks – and applied theories developed from previous research in the fields of marketing, consumer behavior, behavioural economics and cognitive psychology, to describe likely ways in which UCCLIO’s influenced consumer behavior and decision making. The researchers make some recommendations from a behavioural perspective based on their findings, and Consumer Action proposes how these findings might be applied to consumer policy.

Sounding alien, touching the future : beyond the sonorous limit in science fiction film

In this paper I examine two particular aspects of sounding science fiction film: first, the ulterior, Othering sounds of the alien, whether it is creature, object, technology or environment; and second, the soundscape that accompanies or underscores the type of space travel that crosses temporal and spatial thresholds. In both instances of sounding science fiction film I suggest that human limits are reached and breached, leading to a deterritorialization of the self and a hearing that touches the future which is a moment of pure becoming. I focus on the womanly sonority of the alien to suggest that patriarchal and heterosexist sound devices can be ultimately corrupted. In the analysis of sounding space travel I suggest that science film can create a series of moments in which one experiences the double sublime. This spectacular rendering of a liquid chaos enables the viewer to experience the logic of sensation beyond bodily integrity. In this paper my over-arching position is one that hears in science fiction film the profound potential of a radical alterity that exists beyond the sonorous limit.

Three dimensional stability charts for slopes based on limit analysis methods

This paper uses finite element upper and lower bound limit analysis to produce chart solutions for three-dimensional (3D) natural slopes for both short- and long-term stability. The presented chart solutions are convenient tools that can be used for preliminary design purposes. The rigorous limit analysis results in this paper were found to bracket the true factor of safety within ±10% or better, which can be used as a benchmark for the solutions from other methods. The depth of the slip surfaces is observed to be generally shallow for most analyzed cases, particularly for the long-term slope stability problem. In addition, it was found that using a two-dimensional (2D) analysis may lead to significant differences in estimating safety factors, which can differ by 2%–60% depending on the slope geometry and soil properties. Therefore, great care and judgement are required when applying 2D analyses to 3D slope problems.

Limit analysis solutions for very gentle undrained slopes

In view of the demand for energy resources, offshore engineering has drawn the attention of many investigators over the past decade. Recent studies have revealed that seabed landslides can have a sig-nificant influence on the performance of offshore infrastructure, such as pipelines. The vulnerability triggered by seabed landslides can even lead to loss of life. In this context, the importance of offshore slope stability evaluation is obvious. Slope stability is generally assessed by the limit equilibrium method (LEM). However, the accuracy of the method is often questioned due to the underlying assumptions that it makes. This study utilises numerical finite element upper and lower bound limit analysis to produce solutions for very gentle undrained slopes. Using these techniques, the stability can be bracketed from above and below. In this paper, a range of slope geometries and the inhomogeneity of the natural soil have been taken into account. The solu-tions presented are useful tools for preliminary design.