In this work a model to predict the austenite decomposition into ferrite, pearlite, bainite and martensite during arbitrary cooling paths for thin sheet boron steel is used. The model is based on ...Kirkaldy’s rate equations. The basic rate equations has been modified to account for the austenite stabilization effect from the added boron. The model is implemented as part of a material subroutine in the Finite Element Program LS-DYNA 970. Both the obtained simulated volume fractions microconstituents and hardness profiles shows promising agreement to the corresponding experimental observations.
The aim of the book is to provide an understanding of the current science underpinning Carbon Capture and Sequestration (CCS) and to provide students and interested researchers with sufficient ...background on the basics of Chemical Engineering, Material Science, and Geology that they can understand the current state of the art of the research in the field of CCS. In addition, the book provides a comprehensive discussion of the impact of CCS on the energy landscape, society, and climate as these topics govern the success of the science being done in this field.
Expansion in the supply of intermittent renewable energy sources on the electricity grid can potentially benefit from implementation of large-scale compressed air energy storage in porous media ...systems (PM-CAES) such as aquifers and depleted hydrocarbon reservoirs. Despite a large government research program 30 years ago that included a test of air injection and production in an aquifer, and an abundance of literature on CAES mostly relevant to caverns, there remain fundamental questions about the hydrologic and energetic performance of PM-CAES. We have developed rigorous simulation capabilities for PM-CAES that include modeling the coupled wellbore–reservoir system. Through consideration of a prototypical PM-CAES wellbore–reservoir system representing a depleted hydrocarbon reservoir, we have simulated 100 daily cycles of PM-CAES. We find that (1) PM-CAES can store energy but that pervasive pressure gradients in PM-CAES result in spatially variable energy storage density in the reservoir, (2) the wellbore–reservoir storage component of PM-CAES is very efficient, (3) cap-rock and hydrologic seals along with proper sizing of the PM-CAES reservoir prevent excess pressure diffusion from being a problem, and (4) injection and production of air does not significantly mobilize residual liquid water in the reservoir.
•Soil heterogeneity has a distinct effect on surface methane concentrations.•Methane transport can be adequately represented with a Fickian model framework.•Saturation has a dominant effect over soil ...texture on gas migration through soil.
A major concern resulting from the increased use and production of natural gas has been how to mitigate fugitive greenhouse gas emissions (predominantly methane) from natural gas infrastructure (e.g., leaky shallow pipelines). Subsurface migration and atmospheric loading of methane from pipeline leakage is controlled by source configurations and subsurface soil conditions (e.g., soil heterogeneity and soil moisture) and are further affected by atmospheric conditions (e.g., wind and temperature). However, the transport and attenuation of methane under varying subsurface and atmospheric conditions are poorly understood, making it difficult to estimate leakage fluxes from methane concentration measurements at and above the soil surface. Based on a series of controlled bench-scale experiments using a large porous media tank interfaced with an open-return wind tunnel, this study investigated multiphase processes controlling migration of methane from a point source representing a buried pipeline leaking at fixed flow rate (kg/s) under various saturation and soil-texture conditions. In addition, potential effects of atmospheric boundary controls, wind (0.5 and 2.0ms−1) and temperature (22 and 35°C), were also examined. Results showed the distinct effects of soil heterogeneity and, to a varying degree, of soil moisture on surface methane concentrations. In addition, results also showed the pronounced effects of wind and, to a lesser degree, of temperature on surface methane concentrations in the presence of varying soil and moisture conditions. The observed subsurface methane profiles were simulated using the multiphase transport simulator TOUGH2-EOS7CA. Observed agreement between measured and simulated data demonstrates that for the conditions studied, multiphase migration of a multicomponent gas mixture (including methane) under density-dependent flow can be adequately represented with a Fickian advection-diffusion (or dispersion) model (ADM) framework. The dominant effect of saturation over the soil texture, could also be inferred from numerical characterization.
This article describes the process teachers at a public elementary school completed to develop and implement a developmentally appropriate, race-conscious, anti-bias curriculum in all K-5 classrooms. ...The study focuses on the experiences of the teachers and children in three early childhood classrooms using a case study design. Data were gathered and analyzed following one-on-one interviews with the principal and teachers, and an observation of an anti-bias lesson in one kindergarten classroom. Themes were identified following this analysis that concurred with existing literature on anti-bias education. The findings suggest the developmental appropriateness of teaching anti-bias topics to young children and the importance of iterative cycles of teacher reflection and learning as they engaged in this process. The findings further suggest that anti-bias education could be implemented at 1st-grade and kindergarten levels at a public school.
•An experimental procedure for sheet metal shearing is developed.•The shear process is studied in a finite element based perturbation analysis.•The experimental set-up allows well defined ...shearing.•Forces are measured with high accuracy.
Throughout the industrial processes of sheet metal manufacturing and refining, shear cutting is widely used for its speed and cost advantages over competing cutting methods. Industrial shears may include some force measurement possibilities, but the force is most likely influenced by friction losses between shear tool and the point of measurement, and are in general not showing the actual force applied to the sheet. Well defined shears and accurate measurements of force and shear tool position are important for understanding the influence of shear parameters. Accurate experimental data are also necessary for calibration of numerical shear models. Here, a dedicated laboratory set-up with well defined geometry and movement in the shear, and high measurability in terms of force and geometry is designed, built and verified. Parameters important to the shear process are studied with perturbation analysis techniques and requirements on input parameter accuracy are formulated to meet experimental output demands. Input parameters in shearing are mostly geometric parameters, but also material properties and contact conditions. Based on the accuracy requirements, a symmetric experiment with internal balancing of forces is constructed to avoid guides and corresponding friction losses. Finally, the experimental procedure is validated through shearing of a medium grade steel. With the obtained experimental set-up performance, force changes as result of changes in studied input parameters are distinguishable down to a level of 1%.
According to internal observations within a German shipping company, obvious risk-behaviour persists among the crew members coming from the Pacific Island State of Kiribati and representing a large ...part of the crew aboard merchant vessels of this company. These observations were related to excessive eating habits. This study aims to assess the cardiovascular risk among seafarers and to compare lifestyle factors between Kiribati and European crew members.
In the present maritime field study 81 sailors (48 Kiribati, 33 European, average age at 38.9 and 36.8 years respectively) were examined from April until August 2014 aboard four container ships crossing the Atlantic Ocean (participation rate of 90.9%).
Based on the number of established risk factors, 35.4% of the Kiribati and 16.7% of the European crew members were regarded as a high risk group for cardiovascular diseases. The HDL-values of Kiribati were found to be considerably lower (34.9 mg/dl) than the references values given by the WHO and in comparison to the European crew members (44.8 mg/dl) (p = 0.002). 91.7% of Kiribati and 51.5% of European participants were found to be overweight according to WHO-criteria - with a mean Body Mass Index (BMI) of 30.3 kg/m
and 25.6 kg/m
(p < 0.001). Regarding lifestyle factors Kiribati often claimed to eat significantly larger amounts of food aboard while most European sailors stated to eat less or about the same during their shipboard stay (p = 0.017). Daily sleeping hours were slight on both sides; however with a mean of 5.2 h a day Kiribati crew members had significant fewer sleep (p = 0.038). The examined Kiribati sailors had a mean increase in weight of 6 kg over a 12 months period of observation.
In total the compiled data points towards a higher risk of cardiovascular diseases particularly due to alimentary habits within the Kiribati crew members. The distinct weight-gain measured among the Kiribati in spite of higher energy consumption levels at sea is alarming. Thus, the results of this study confirm the necessity of health-improving interventions aboard cargo vessels.
Shear cutting is common within several sheet metal industry processing steps, e.g. in cut to length lines, slitting lines, end cropping. Shearing is fast and cheap relative to competing cutting ...methods like laser and plasma cutting, but involves large forces on the equipment that increase with increased sheet material strength. Accurate shear experiments are a prerequisite to increase the knowledge of shearing parameters, improve industrial shearing, and provide data for validation of numerical shear models. Here, the two shear parameters clearance and clamp configuration, identified as important to the shear results, were studied in an experimental set-up with well defined tool movement and high measurability of tool position and force. In addition to force measurements, the sheared edge geometry was characterized. Steels of low, medium, and high strength were selected for the study. Throughout the experimental study, the shear tool penetration before fracture decreased with increased material strength. The required shear force decreased and the force attempting to separate the two shear tools increased when one side of the sheet was left unclamped and free to move. Further, the maximum shear force increased with decreased clearance. Clearance changes were small and moreover continuously measured during all shear experiments.
Knowledge of concentrations or loads in wastewater flows is a basic prerequisite for the design of wastewater treatment units and the assessment of the environmental impacts. With respect to new ...sanitation concepts that are based on the source-separation of domestic wastewater flows not much general data is available yet on characteristics or design values of the different flows. A desk study of more than 130 references was carried out in order to arrive at design values for different source-separated wastewater flows including the fractions urine, faeces and greywater. The evaluation was carried out focussing on European data. The different values were analysed by the use of statistical parameters. In order to arrive at design values for different parameters, the median as well as minimum-maximum ranges of the available data were calculated. The collected data include volumes and characteristics like organic pollution (COD and BOD), nutrients (N, P, K & S) and heavy metals for the different source-separated flows. Loads and concentrations are listed respectively. A comparison is drawn between data from different regions in order to assess the impact of differences in nutrition and habits.
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