4,090 research outputs found
The long road to unity
As Christianity grows ever more diverse, is unity an absurd hope – or even
desirable? A recent international conference in Durham confirmed that although
progress is slow, a new way of ‘doing’ecumenism is starting to bear fruit
The Probability of Failure of Solid Oxide Fuel Cells by the Integrated Modelling of Multiple Physical Processes
A three dimensional, coupled computational fluid dynamics and finite element model of
a single, anode supported solid oxide fuel cell has been developed in order to predict
the probability of failure of the ceramic components subjected to an idealised operating
duty cycle. The duty cycle represents cooling from sintering, warming to a uniform
temperature of 800◦C where anode chemical reduction takes place, operation at low,
medium and high power and finally cooling to room temperature.
The StarCDTM computational fluid dynamics code provided the platform to determine
the temperature distribution throughout the operating fuel cell by solving the
conservation equations for energy, mass and momentum, with additional subroutines
written to account for species transport, electrochemical reactions and heat generation.
An AbaqusTM finite element model used the temperature distribution predicted by the
computational fluid dynamics model at low, medium and high power to solve for the
thermal stress distribution for individual cases and throughout the duty cycle. The
finite element model included the effects of thermal expansion, residual stress from manufacture,
material properties changes due to chemical reduction of the anode and viscoplastic
creep. The maximum principal stress in the anode support layer at 800◦C and
low, medium and high power was found to be 5.0, 26.5, 33.2 and 39.8 MPa respectively.
The stress analysis results were used to determine the time independent and time
dependent (accounting for sub-critical crack growth) probability of failure, and showed
that over the duty cycle sub-critical crack growth significantly increased the predicted
probability of failure in the anode support layer from less than 1 ×10−12 to 0.54, and in
the cathode layer from 1.28 × 10−5 to 1.24 × 10−3. The probability of failure of SOFC
ceramic components is thus shown to be both time and history dependent
Degassing history of water, sulfur, and carbon in submarine lavas from Kilauea volcano, Hawaii
Major, minor, and dissolved volatile element concentrations were measured in tholeiitic glasses from the submarine portion (Puna Ridge) of the east rift zone of Kilauea Volcano, Hawaii. Dissolved H_(2)O and S concentrations display a wide range relative to nonvolatile incompatible elements at all depths. This range cannot be readily explained by fractional crystallization, degassing of H20 and S during eruption on the seafloor, or source region heterogeneities. Dissolved C0_2 concentrations, in contrast, show a positive correlation with eruption depth and typically agree within error with the solubility at that depth. We propose that most magmas along the Puna Ridge result from (I) mixing of a relatively volatile-rich, undegassed component with magmas that experienced low pressure (perhaps subaerial) degassing during which substantial H_(2)O, S, and C0_2 were lost, followed by (2) fractional crystallization of olivine, clinopyroxene, and plagioclase from this mixture to generate a residual liquid; and (3) further degassing, principally of C0_2 for samples erupted deeper than 1000 m, during eruption on the seafloor. The degassed end member may form at upper levels of the summit magma chamber (assuming less than lithostatic pressure gradients), during residence at shallow levels in the crust, or during sustained summit eruptions. The final phase of degassing during eruption on the seafloor occurs slowly enough to achieve melt/vapor equilibrium during
exsolution of the typically CO_(2)-rich vapor phase. We predict that average Kilauean primary magmas with
16% MgO contain ~0.47 wt% H_(2)O, ~900 ppm S, and have δD values of ~-30 to -40‰. Our model predicts that submarine lavas from wholly submarine volcanoes (i.e., Loihi), for which there is no opportunity to generate the degassed end member by low pressure degassing, will be enriched in volatiles relative to those from volcanoes whose summits have breached the sea surface (i.e., Kilauea and Mauna Loa)
Unbundling is over-rated: On the value of contributing to an edited book
Terry Clague sheds reasonable doubt on the assertion that contributing to edited book chapters is a waste of time. The sole aim of publication isn’t necessarily to maximise citations. If citations are the only measure of academic value then there’s a danger that academic research becomes the X-Factor. Furthermore, edited collections can also aid discovery of new material where new voices and approaches can be heard
Workforce Series #6 The Job Interview
This document provides insight for an individual in regards to how to get a job interview and how to prepare for the interview
Workforce Series #5 Filling Out a Job Application
This document provides insight on how to fill out a job application
Workforce Series #4 References and Letters of Recommendation
This document provides insight to the importance of references and letters of recommendation that is included in ones resume
Manx Language Revitalization and Immersion Education
The Manx language is currently enjoying a period of revitalization. The decline of the Manx language as the native vernacular language of the Isle of Man and the subsequent language shift to English are discussed in the first part of this paper. The paper then goes on to consider the revitalization of the language, with the emphasis on Manx-medium immersion education. The results of a questionnaire enquiring into parental motivations for choosing immersion education, and the linguistic backgrounds of the children are then examined in some detail
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