Treading in Mortimer's footsteps: the geochemical cycling of iron and manganese in Esthwaite water

A study of the geochemical cycling of iron and manganese in a seasonally stratified lake, Esthwaite water is described. This work is based on speculative ideas on environmental redox chemistry of iron which were proposed by C.H. Mortimer in the 1940's. These observations have been verified and some speculations confirmed, along with a new understanding of the manganese cycle, and detailed information on the particulate forms of both iron and manganese. Details on the mechanisms and transformations of iron have also emerged

Population Dynamics of Cyrtobagous salviniae on Common Salvinia in South Florida

Common salvinia (Salvinia minima Baker) is an exotic floating fern that has been in the U.S. from at least 1928(Small 1931). Its pest status in Florida is less clear perhaps due to the presence of the specialized herbivore Cyrtobagous salviniae (Coleoptera: Curculionidae). Our objective was to sample populations of adult C. salviniae in south Florida in order to assess temporal abundance and estimate density on common salvinia. (PDF has 4 pages.

Harnessing Technology in Schools Survey 2007: technical report

This technical report provides a detailed review of the methods used and the data gathered for this survey. The report also provides copies of the research instruments used in this survey

Integrated structural analysis tool using linear matching method part 2 : Application and verification

In an accompanying paper, a new integrated structural analysis tool using the LMM framework for the assessment of design limits in plasticity including load carrying capacity, shakedown limit, ratchet limit and steady state cyclic response of structures was developed using Abaqus CAE plug-­‐ins with graphical user interfaces. In the present paper, a demonstration of the use of this new LMM analysis tool is provided. A header branch pipe in a typical AGR power plant is analysed as a worked example of the current demonstration and verification of the LMM tool within the context of an R5 assessment. The detailed shakedown analysis, steady state cycle and ratchet analysis are carried out for the chosen header branch pipe. The comparisons of the LMM solutions with the results based on the R5 procedure and the step-­‐by-­‐step elastic-­‐plastic FEA verify the accuracy, convenience and efficiency of this new integrated LMM structural analysis tool

Integrated structural analysis tool using linear matching method part 1 : Software development

A number of direct methods based upon the Linear Matching Method (LMM) framework have been developed to address structural integrity issues for components subjected to cyclic thermal and mechanical load conditions. This paper presents a new integrated structural analysis tool using the LMM framework for the assessment of load carrying capacity, shakedown limit, ratchet limit and steady state cyclic response of structures. First, the development of the LMM for the evaluation of design limits in plasticity is introduced. Second, preliminary considerations for the development of the LMM into a tool which can be used on a regular basis by engineers are discussed. After the re-structuring of the LMM subroutines for multiple CPU solution, the LMM software tool for the assessment of design limits in plasticity is implemented by developing an Abaqus CAE plug-­in with graphical user interfaces. Further demonstration of this new LMM analysis tool including practical application and verification is presented in an accompanying paper

Verification of the linear matching method for limit and shakedown analysis by comparison with experiments

The Linear Matching Method (LMM), a direct numerical method for determining shakedown and ratchet limits of components, has seen significant development in recent years. Previous verifications of these developments against cyclic nonlinear finite element analysis have shown favourable results, and now this verification process is being extended to include comparisons with experimental results. This paper presents a comparison of LMM analysis with experimental tests for limit loads and shakedown limits available in the literature. The limit load and shakedown limits were determined for pipe intersections and nozzle-sphere intersections respectively, thus testing the accuracy of the LMM when analysing real plant components. Details of the component geometries, materials and test procedures used in the experiments are given. Following this a description of the LMM analysis is given which includes a description of how these features have been interpreted for numerical analysis. A comparison of the results shows that the LMM is capable of predicting accurate yet conservative limit loads and shakedown limits

Calculation of a lower bound ratchet limit part 1 – Theory, numerical implementation and verification

It is important to be able to calculate the ratchet limit of a component when performing integrity assessments of plant components. This paper details the addition of a lower bound ratchet limit calculation to the Linear Matching Method. The extension of Melan's theorem into the alternating plasticity region is explained, followed by its implementation into the Linear Matching Method calculation procedure. Finally, the convergence properties of this method are analysed by the analysis of a plate with a central hole subject to cyclic thermal and mechanical loadin

Development and implementation of the Abaqus subroutines and plug-in for routine structural integrity assessment using the linear matching method

In recent years the Linear Matching Method (LMM) has been developed as a tool for structural integrity assessments of components subjected to cyclic loading conditions. Its capabilities include, among others, calculation of the shakedown limit, ratchet limit, plastic strain range for low cycle fatigue, creep rupture time and fatigue creep interaction. The LMM is now incorporated into EDF Energy’s R5 research program for the high temperature assessment of structural components. The purpose of this paper is to describe the development of the LMM framework, its incorporation into Abaqus and current plans to take the method from being primarily research based into wider use by industry for routine structural assessments. The LMM calculations are primarily carried out using the UMAT subroutine, and the first topic discussed in this paper is the implementation of this user subroutine. This includes details of the coding scheme to allow use of multi-processors for the calculations. A brief comparison of the LMM with full cyclic FEA is also included to validate the method and to demonstrate its advantages. The second topic of this paper discusses the development of an Abaqus/CAE plug-in to aid wider adoption of the LMM as an analysis tool for industry. The structure of the plug-in is described alongside the processes used for data collection from the user and automatic configuration of the model