598 research outputs found
Modelling and Experimental Analysis of a Polymer Electrolyte Membrane Water Electrolysis Cell at Different Operating Temperatures
Full text linkIn this paper, a simplified model of a Polymer Electrolyte Membrane (PEM) water electrolysis cell is presented and compared with experimental data at 60 °C and 80 °C. The model utilizes the same modelling approach used in previous work where the electrolyzer cell is divided in four subsections: cathode, anode, membrane and voltage. The model of the electrodes includes key electrochemical reactions and gas transport mechanism (i.e., H2, O2 and H2O) whereas the model of the membrane includes physical mechanisms such as water diffusion, electro osmotic drag and hydraulic pressure. Voltage was modelled including main overpotentials (i.e., activation, ohmic, concentration). First and second law efficiencies were defined. Key empirical parameters depending on temperature were identified in the activation and ohmic overpotentials. The electrodes reference exchange current densities and change transfer coefficients were related to activation overpotentials whereas hydrogen ion diffusion to Ohmic overvoltages. These model parameters were empirically fitted so that polarization curve obtained by the model predicted well the voltage at different current found by the experimental results. Finally, from the efficiency calculation, it was shown that at low current densities the electrolyzer cell absorbs heat from the surroundings. The model is not able to describe the transients involved during the cell electrochemical reactions, however these processes are assumed relatively fast. For this reason, the model can be implemented in system dynamic modelling for hydrogen production and storage where components dynamic is generally slower compared to the cell electrochemical reactions dynamics
Richardson, Barbauld, and the construction of an early modern fan club
No full textMPhilMuch has been written about the life and long works of the eighteenth century epistolary novelist, Samuel Richardson, but the prospect of his position as the first celebrity novelist – responsible for courting his own fame as well as initiating his own fan club – has largely been ignored. The body of manuscripts housed at the National Art Library in the Victoria and Albert Museum in London provides the modern scholar with evidence of the skeletal beginnings of an early fan club. This thesis aims to show how these manuscripts were turned into a saleable commodity by the publisher and entrepreneur Richard Phillips, while under the guiding hand of another, slightly later, literary celebrity, Anna Laetitia Barbauld. In order to restore Richardson’s reputation amongst a new nineteenth century audience, Barbauld was required to construct her own idea of him as an eighteenth century celebrity author, and in doing so the insecurities of a self-professed, apparently diffident man, are revealed. Barbauld’s capacious, but heavily edited selection of letters is analyzed in this thesis, providing ample evidence that Richardson’s correspondents were more than just eager letter writers. By using Barbauld’s biography of Richardson this thesis aims to show how she manipulates the genre of life writing in her construction of him.
This thesis offers an alternative reading of how the Richardson manuscripts are viewed, redefining them as not simply a collection of letters, but as a collective entity, deliberately selected and archived as evidence of an early modern fan club, and its celebrity managing director
Impedance characterization of high temperature proton exchange membrane fuel cell stack under the influence of carbon monoxide and methanol vapor
No full textThis work presents a comprehensive mapping of electrochemical impedance measurements under the influence of CO and methanol vapor contamination of the anode gas in a high temperature proton exchange membrane fuel cell, at varying load current. Electrical equivalent circuit model parameters based on experimental evaluation of electrochemical impedance spectroscopy measurements were used to quantify the changes caused by different contamination levels. The changes are generally in good agreement with what is found in the literature. It is shown that an increased level of CO contamination resulted in an increase in the high frequency and intermediate frequency impedances. When adding CO and methanol to the anode gas, the low frequency part of the impedance spectrum is especially affected at high load currents, which is clearly seen as a result of the high load current resolution used in this work. The negative effects of methanol vapor are found to be more pronounced on the series resistance. When CO and methanol vapor are both present in anode gas, the entire frequency spectrum and thereby all the equivalent circuit model parameters are affected. It is also shown that the trends of contamination effects are similar for all the test cases, namely, CO alone, methanol alone and a mix of the two, suggesting that effects of methanol may include oxidation into CO on the catalyst layer
Writing and the rights of reality: usurpation and potentiality in Derrida, Plato, Nietzsche, and Beckett
Full text linkThe thesis critically evaluates Jacques Derrida's conferral of the rights of reality on writing, focussing on his theory of an arche-text in light of the speculative nature of this theory. The theory is initially considered in the context of Derrida's elucidation of the usurpatory status of writing within the Platonic and Nietzschean texts. This consideration reveals an admission of writing's usurpatory status by both writers while at the same time demonstrating their awareness of the intrinsically speculative nature of this view, the significance of writing lying in its ability to exteriorise the radically indeterminate status of consciousness m relation to reality rather than its ability to displace consciousness or reality The analyses, therefore, not only bring the Derridean hypothesis of a repressive or phonocentric metaphysical episteme into question but also exhibit the historical and philosophical role of potentiality in relation to writing, writing's ultimate significance lying in its capacity to exteriorise our existence as a mode of potentiality. Accordingly, in the second half of the thesis the Derridean theory of writing is countered with a specifically Aristotelian theory of the text as it is exhibited in the prose of Samuel Beckett, an author whose significance lies in his close alignment with Derridean theory within contemporary criticism. It is demonstrated that this identification has obviated an awareness of the significance of potentiality within the Beckettian text, his work consequently being appraised in the previously neglected context of Aristotelian metaphysics
Usability and acceptability of a website that provides tailored advice on falls prevention activities for older people
Full text linkThis article presents the usability and acceptability of a website that provides older people with tailored advice to help motivate them to undertake physical activities that prevent falls. Views on the website from interviews with 16 older people and 26 sheltered housing wardens were analysed thematically. The website was well received with only one usability difficulty with the action plan calendar. The older people selected balance training activities out of interest or enjoyment, and appeared to carefully add them into their current routine. The wardens were motivated to promote the website to their residents, particularly those who owned a computer, had balance problems, or were physically active. However, the participants noted that currently a minority of older people use the Internet. Also, some older people underestimated how much activity was enough to improve balance, and others perceived themselves as too old for the activities
HIV/AIDS and the Bible in Tanzania : A Contextual Re-reading of 2 Samuel 13:1-14:33
No full textZugl.: Pretoria, Univ. of South Africa (UNISA), Diss., 2011 u.d.T.: Muneja, Mussa Simon: Re-Reading 2 Samuel 13:1-14:33 in Tanzanian Contexts: Towards an HIV/AIDS Biblical HermeuneuticsThis volume was passed as doctoral thesis by the University of South Africa (UNISA). The author contends throughout the book that it is arguably clear that the AIDS epidemic has infected and affected our world in radical ways. Although every sector, including Biblical Studies, has come to its ‘senses’, by realising the urgency to respond; there still appears to be inadequate contextual engagement with the biblical text to stimulate empowering and transformative readings of the Bible.
The author presents his interpretative case aimed to contribute to scholarship by determining the extent to which the church, the academy and Persons with HIV have adhered to stigmatising interpretations. He uses reader response method theoretical framework as applied within the context of African theology because it is socially located.
Unlike many books, this one emerges from empirical findings. The data was collected through focus groups and personal interviews. The purposive sampling included 70 participants, who were divided into three key categories: academic theologians, university students and persons with HIV. All participants in the study re-read 2 Samuel 13:1-14:33 in order to ascertain if the characters therein could be relevant to the context of AIDS.
Towards the end, the author sums up his case by endorsing that, characters from 2 Samuel 13:1-14:33 can provide an empowering message in the context of AIDS. Although this biblical text has often been misused to promote stigma, this study confirmed that it was nonetheless possible to use the same text to unearth redemptive and empowering interpretations. Therefore the book recommends that the move towards an HIV/AIDS Biblical Hermeneutics invites socially engaged scholars along with ordinary readers to read the text together for transformative purposes
Experimental and FEM investigation into early gasket failure and its correlation to the clamping load and HT-PEMFC performance
No full textPerformance and degradation tests on high temperature proton exchange membrane fuel cells (HT-PEMFCs)
No full textMethanol steam reforming process can be a good solution for hydrogen generation in the case of fuel cells. The use of hydrogen generated by such process to fuel a fuel cell can eliminate the issues related to infrastructure and storage. But the hydrogen obtained through methanol steam reforming is not pure, containing impurities such as carbon dioxide, carbon monoxide, water vapor and unconverted methanol. Researches have been conducted on HT-PEM fuel cells to study the effects of fuel impurities. The current work investigates experimentally the effects of methanol-water vapor mixture concentrations in a H3PO4 doped PBI-based HT-PEM fuel cell. To isolate the effects of methanol-water vapor mixture from the whole reformate gas, the carbon dioxide and carbon monoxide are excluded from the experimental matrix. Two types of experiments are conducted: performance tests and degradation tests. The performance tests are realized in order to study the effect of temperature and the different vapor mixture concentrations on the fuel cell. The effect of startup-shutdown cycles is studied during the degradation tests. The analysis of these effects is made based on the impedance spectra measurements, polarization curves and cyclic voltammetry measurements. The results showed that temperature and methanol-water vapor mixture variations have an effect on the fuel cell performance. The increase in temperature increases the cathode catalyst active area and decreases the charge transfer resistance. Methanol-water vapor variations have an effect on the membrane conductivity when the cell is operated for longer times and cause a decrease in the catalyst active area of the cathode. During the startup/shutdown cycles performed with pure hydrogen the total voltage decay was of -46.3 mV, while the degradation rate for the case with methanol at a concentration of 3% was of -7.9 mV/h
Écriture de soi et traduction dans les oeuvres « jumelles » de Samuel Beckett et Wilfred R. Bion
Full text linkÉcriture de soi et traduction dans les oeuvres « jumelles » de Samuel Beckett et Wilfred R. Bion — Cet article envisage la problématique de la traduction à partir du champ psychanalytique. Wilfred R. Bion fut pour une brève période l'analyste de Samuel Beckett. L'auteur souhaite démontrer que les écrits de Samuel Beckett et Wilfred R. Bion peuvent être lus comme des oeuvres jumelles qui tentent à leur manière de traduire l'infigurable source du « secret » de la cure. L'auteur aborde l'étude du concept d'après coup en psychanalyse, la mise enjeu du mythe de Babel dans l'oeuvre théorique de Bion, la traduction de la langue-mère dans l'oeuvre de Beckett. Les oeuvres de Bion et Beckett tenteraient ainsi l'impossible traduction du trauma dans la langue maternelle.Writing the Seifand Translation in the "Twin" Works of Samuel Beckett and Wilfred R. Bion — This article takes the psychoanalytic field as its point of departure in its discussion of the problematics of translation. For a brief period, Wilfred R. Bion was Samuel Beckett's analyst. The author endeavors to show that the writings of Beckett and Bion can be read as "twin" works that attempt, in their way, to translate the elusive source of the cure's "secret." The author examines the concept of après coup (deferred action) in psychoanalysis, the role of the Babel myth in Bion's theoretical writings, and the translation of the mother tongue in Beckett's writings. Both Bion and Beckett's writings would thus attempt the impossible translation, that of translating trauma into the mother tongue
Advances in Hydrogen Energy
Full text linkThis book, which is a reprint of articles published in the Special Issue "Advances in Hydrogen Energy" in Energies, seeks to contribute to disseminating the most recent advancements in the field of hydrogen energy. It does so by presenting scientific works from around the world covering both modeling and experimental analysis. The focus is placed on research covering all aspects of the hydrogen energy, from production to storage and final use, including the development of other easy to transport and versatile hydrogen-based energy carriers via the power-to-x (PtX) route, such as ammonia and methanol.Hydrogen energy research and development has attracted growing attention as one of the key solutions for clean future energy systems. In order to reduce greenhouse gas emissions, governments across the world are developing ambitious policies to support hydrogen technology, and an increasing level of funding has been allocated for projects of research, development, and demonstration of these technologies. At the same time, the private sector is capitalizing on the opportunity with larger investments in hydrogen technology solutions.While intense research activities have been dedicated to this field, several issues require further research prior to achieving full commercialization of hydrogen technology solutions. This book addresses some of these issues by presenting detailed models to optimize design strategies and operating conditions for the entire hydrogen value chain, covering production via electrolysis, storage and use in different types of fuel cells and in different forms of energy carriers
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