A fully implicit multi-axial solution strategy for direct ratchet boundary evaluation : theoretical development

Ensuring sufficient safety against ratchet is a fundamental requirement in pressure vessel design. Determining the ratchet boundary can prove difficult and computationally expensive when using a full elastic-plastic finite element analysis and a number of direct methods have been proposed that overcome the difficulties associated with ratchet boundary evaluation. Here, a new approach based on fully implicit Finite Element methods, similar to conventional elastic-plastic methods, is presented. The method utilizes a two-stage procedure. The first stage determines the cyclic stress state, which can include a varying residual stress component, by repeatedly converging on the solution for the different loads by superposition of elastic stress solutions using a modified elastic-plastic solution. The second stage calculates the constant loads which can be added to the steady cycle whilst ensuring the equivalent stresses remain below a modified yield strength. During stage 2 the modified yield strength is updated throughout the analysis, thus satisfying Melan’s Lower bound ratchet theorem. This is achieved utilizing the same elastic plastic model as the first stage, and a modified radial return method. The proposed methods are shown to provide better agreement with upper bound ratchet methods than other lower bound ratchet methods, however limitations in these are identified and discussed

A fully implicit multi-axial solution strategy for direct ratchet boundary evaluation : implementation and comparison

Ensuring sufficient safety against ratcheting is a fundamental requirement in pressure vessel design. However, determining the ratchet boundary using a full elastic plastic finite element analysis can be problematic and a number of direct methods have been proposed to overcome difficulties associated with ratchet boundary evaluation. This paper proposes a new lower bound ratchet analysis approach, similar to the previously proposed Hybrid method but based on fully implicit elastic-plastic solution strategies. The method utilizes superimposed elastic stresses and modified radial return integration to converge on the residual state throughout, resulting in one Finite Element model suitable for solving the cyclic stresses (Stage 1) and performing the augmented limit analysis to determine the ratchet boundary (Stage 2). The modified radial return methods for both stages of the analysis are presented, with the corresponding stress update algorithm and resulting consistent tangent moduli. Comparisons with other direct methods for selected benchmark problems are presented. It is shown that the proposed method evaluates a consistent lower bound estimate of the ratchet boundary, which has not previously been clearly demonstrated for other lower bound approaches. Limitations in the description of plastic strains and compatibility during the ratchet analysis are identified as being a cause for the differences between the proposed methods and current upper bound methods

The Lloyd's Litigation

The purpose of this article is to provide a general background to the recent spate of litigation generated within the Lloyd's market. It is intended to provide an overview of the more important categories of cases, and of some of the more important decisions. It is not intended to deal with all the relevant decisions, or provide a detailed review or analysis of those decisions which are discussed

Hope labour and the psychic life of cultural work

How do we understand the psychic life of cultural workers under neoliberalism? ‘Hope labour’ is a defining quality of a cultural worker’s experience, practice and identity. Hope labour is unpaid or under-compensated labour undertaken in the present, usually for exposure or experience, with the hope that future work may follow. Hope labour is naturalised by neoliberal discourses but not fully determined by them. Drawing upon empirical research investigating the ‘creative industries’ in the North East of England, we ask how hope labour is made meaningful and worthwhile for cultural workers positioned as entrepreneurial subjects, despite its legitimisation of power asymmetries. We develop Foucauldian studies of governmentality by addressing how cultural work is lived through neoliberal categories, demonstrating the conflicting discourses and relations to self involved in the constitution of entrepreneurial subjectivity. We make a novel contribution to an understanding of hope and precarity by illustrating how cultural workers begin to occupy the site of the entrepreneurial subject amidst conflicting configurations of hope, desire, anxiety and uncertainty

The Geology of the Langholm-Ecclefechan Area, Eastern Dumfriesshire

Abstract Not Provided

Time Trends in Expenditures for Rural Veterans\u27 Healthcare

We studied rural-urban differences in medical spending trends over eleven years for VA as well as non-VA care received by male veterans who used any VA services, and compared those trends to trends for other healthcare-using men. Using inflation-adjusted annual medical expenditures for non-veterans, VA users, and other veterans who participated in Medical Expenditure Panel Surveys from 1996 through 2006, we examined trends in spending on inpatient, hospital-based outpatient, office-based, pharmacy, and other care, by major payers (self/family, private insurance, Medicare, other sources, and VA), to assess changes in expenditures for the care of rural veterans, younger or older than 65 years, compared with other healthcare users. For all groups, spending for pharmacy and office-based care increased fasterthan inflation, while other care categories did not change consistently. VA spending also increased for these but not other services, and it grew sharply for working-age rural veterans, possibly reflecting improved access through community-based care

Bags of sand and dirt : exploiting the British Geological Survey's environmental samples and database

Ask any member of the public or even the science community what samples they would expect to find in a geological survey organisation and they would undoubtedly list fossils, rocks and minerals, the traditional view of a geological collection. Few would think about the tons of sediment, soil, and water samples – environmental samples less glamorously referred to as bags of sand and dirt. This is hardly moon or gold dust yet collectively these samples are a valuable asset for the British Geological Survey (BGS) that require collating in a systematic and secure manner. The corporate BGS Geochemical Database contains some half-a-million samples and eight million analyte determinations. This Oracle database contains numerous tables describing the samples, the sites from where they were collected, details about the laboratories that have carried out analyses and the methods used, in addition to chemical analyses. It is an under-used environmental resource that contains BGS geochemical data gathered over a period of nearly 40 years. Bringing this collection of digital environmental data from disparate projects together into one database has required procedures to be developed to ensure consistent coding for the description of samples. The chemical data has to be verified as being fit for purpose through data conditioning to ensure a consistency of quality. The environmental data is increasingly being used for legislative purposes, for example the identification of contaminated land under the Environment Protection Act Part IIa. The data therefore has to be presented in a way that non-scientists can understand what it shows and, equally as important, what are the quality issues and limits associated with the data

A Study of Pion Photoproduction on Carbon-12 in the Delta Resonance Region

This thesis describes a study of the 12 C(gamma; pie + n) reaction in the Delta resonance re­ gion using tagged photons. The experiment was accomplished using the MAMI­B c.w. electron accelerator at the Institut f¨ur Kernphysik, Mainz. Bremsstrahlung photons, created when 855 MeV electrons strike a 4 ¯m Nickel radiator, were tagged with a 2 MeV resolution using the Glasgow tagging spectrometer installed in the MAMI A2 experimental hall. The data is presented as triple and (by integrating over the pion energy) double differential cross sections. A comparison is made with Distorted Wave Impulse Approximation (DWIA) predictions generated by the code THREEDEE. It is concluded that more reliable theoretical calculations are required. In particular, a better treatment of the distortion and absorption of the outgoing particles is needed. Initial comparisons with the microscopic theory of Carrasco are attempted and the problems faced in making such a comparison are described and solutions suggested