9,412 research outputs found
Air and Water Flowrate Optimisation for a Fan Coil Unit in Heat Pump Systems
Full text linkThe degradation in efficiency of auxiliary components in heating/cooling systems when operating at part load is frequently reported. Through the use of variable speed components, the supplied capacity can be reduced to match the required load and hence reduce unnecessary energy consumption. However, for fan coil units, difficulties can arise when optimizing fan and pump speeds at part load. Practically locating optimal water and air flow rates from readily available information and for varying supplied capacities is necessary, in order to reduce the fan coil power consumption. This research attempts to identify whether optimal fan and pump speeds exist for a fan coil unit and how they can be implemented, in a practical manner, in a system control applications. Using an empirical fan coil and pump model, the total power consumption (fan and pump) for different combinations of fan and pump speeds over a range of capacities was calculated. It was observed that, for a given capacity, an optimal combination of fan and pump speeds exists and there was a significant change in power consumption for different combinations of fan and pump speeds supplying the same capacity. A control strategy is described that utilizes a simple fan coil capacity estimation model, coupled with air and water flow rates, along with nominal design data. The pump speed is optimized using PID control to maintain the space temperature at the chosen set-point, which matches the supplied capacity to the required capacity. At set-time intervals, the capacity estimation model is utilized to optimize the water and air flow rates for the required capacity. The control strategy is evaluated, using a full building simulation model for a daily load profile and is compared to two baseline conditions: for no control of the fancoils/pump combination and for PID circulation control of the pump only. The optimal fan and pump speed control resulted in a 43% and 24% decrease in power consumption with compared to the no control baseline and the PID controlled circulation pump strategy, respectively
Whose story is it anyway? The ethics of narration and the narration of ethics in Summertime and Die Sneeuslaper
No full textIncludes bibliographical references.This dissertation analyses and compares the narrative strategies in J.M. Coetzee’s Summertime and Marlene van Niekerk’s Die sneeuslaper and considers the implications of these strategies for the authors’ exploration of the ethics of writing. Much has been written about the literary oeuvres of both Coetzee and Van Niekerk, including studies of the translations of Van Niekerk’s Afrikaans novels into English. There are few “interlingual” comparative studies of contemporary works in Afrikaans and English, however, and certainly none to my knowledge which compares the work of Coetzee and Van Niekerk. My contribution to the conversation about Coetzee’s and Van Niekerk’s work, but also to an increasingly multilingual and interconnected South African literary criticism, will be a comparison of one recent work by each of these two authors, written in English and Afrikaans respectively. I draw on the theories of Bakhtin, Barthes and Levinas to consider the ethical dimension of texts in which “double-voicedness”, a questioning not only of existence, but of the self is fore grounded in the content and narrative structure; where there is a shift in focus from the author to the reader (“the birth of the reader”) and “utterances” are made with the response of “the other” in mind
Adjacency for scattering amplitudes from the Gröbner fan
No full textScattering amplitudes in planar N=4 super Yang-Mills theory exhibit singularities which reflect various aspects of the cluster algebras associated to the Grassmannians Gr(4,n) and their tropical counterparts. Here we investigate the potential origins of such structures and examine the extent to which they can be recovered from the Gröbner structure of the underlying Plücker ideals, focussing on the Grassmannians corresponding to finite cluster algebras.Starting from the Plücker ideal, we describe how the polynomial cluster variables are encoded in non-prime initial ideals associated to certain maximal cones of the positive tropical fan. Following [1] we show that extending the Plücker ideal by such variables leads to a Gröbner fan with a single maximal Gröbner cone spanned by the positive tropical rays. The associated initial ideal encodes the compatibility relations among the full set of cluster variables. Thus we find that the Gröbner structure naturally encodes both the symbol alphabet and the cluster adjacency relations exhibited by scattering amplitudes without invoking the cluster algebra at all.As a potential application of these ideas we then examine the kinematic ideal associated to non-dual conformal massless scattering written in terms of spinor helicity variables. For five-particle scattering we find that the ideal can be identified with the Plücker ideal for Gr(3,6) and the corresponding tropical fan contains a number of non-prime ideals which encode all additional letters of the two-loop pentagon function alphabet present in various calculations of massless five-point finite remainders
Predicting fan noise propagation in aeroengine bypass ducts
No full textThis thesis explores the prediction of rearwards fan noise propagation within the bypass duct and its radiation into the far feld. Two recently developed models: B-induct and
GXMunt, are exploited in application to real engine bypass ducts and their performance is evaluated. These methods are an improvement on current industry standards, allowing
realistic duct geometry and flow conditions to be modelled with reasonable computation and time demands. The main focus is on the model b-induct.B-induct predictions for bypass attenuation are integrated into an industry standard whole engine model, and predictions of far-feld noise are obtained for a modern high bypass-ratio engine. These predictions compare more favourably with measured data
from full-scale static engine tests than similar predictions made using a standard uni-form rectangular duct model for the bypass attenuations, indicating that b-induct is an improvement over the current model.Initial studies on the effect of duct geometry on noise propagation suggest a noise benefit for a duct with higher curvature when compared to a typical Baseline design. This
suggestion is confirmed using measured data from zero-flow rig tests. Predictions for three-dimensional duct geometries are also performed to show the effect of scattering due to bifurcations within the duct.B-induct allows for the specific bypass geometry and liner positions to be taken into account when performing impedance optimisations. A new optimisation procedure is proposed in which b-induct predictions are used within an existing whole aircraft noise prediction model. This procedure is used to select liner impedances for a modern engine bypass duct.
B-induct is demonstrated to be a promising new tool within the engine design process, for both analysis of the impact of rear fan noise on whole engine noise, and assessment
of potential low noise bypass configurations
"The day of the great writer is gone for ever": Author surrogacy in Martin Amis’s Money and J.M. Coetzee’s Summertime.
No full textThis study focuses on the use of author surrogacy in the novels Money: A Suicide Note by Martin Amis and Summertime: Scenes from Provincial Life by J.M. Coetzee. It addresses the connection between their use of author surrogacy and their comments on what scholars classify as the postmodern cultural condition. Both authors have written themselves into their novels with a different purpose but both used strikingly similar themes to incorporate this purpose, although the stress on these themes varies. Authorial power, the distinction between the real and the imagined, and the fading line between high- and lowbrow culture are examples of the topics discussed in this study with regards to author surrogacy and the postmodern cultural condition. This study concludes that, through their use of author surrogacy, J.M. Coetzee mainly aims to critique, while Martin Amis satirises postmodern culture.
Keywords: Amis, author surrogacy, authorial power, Coetzee, fact-fiction distinction, high- and lowbrow culture, postmodern cultural condition
O doświadczeniu obcości języka w twórczości J.M. Coetzeego. Słowo wstępne
Full text linkThe present foreword refers to the address delivered by J.M. Coetzee on the occasion of conferring upon him by the University of Silesia the doctor honoris causa degree. Particular attention is paid to his thoughts on the role of English in the world of today. The author of the foreword shows that reflection on language in general and its role in moulding one’s identity in present in the Nobel laureate’s works, including his most recent novels. Further into the foreword, the author briefly discusses text reprinted in Śląskie Studia Polonistyczne: the already mentioned address by J.M. Coetzee, the conversation with the Author, and an article devoted to his works written by Robert Kusek.The present foreword refers to the address delivered by J.M. Coetzee on the occasion of conferring upon him by the University of Silesia the doctor honoris causa degree. Particular attention is paid to his thoughts on the role of English in the world of today. The author of the foreword shows that reflection on language in general and its role in moulding one’s identity in present in the Nobel laureate’s works, including his most recent novels. Further into the foreword, the author briefly discusses text reprinted in Śląskie Studia Polonistyczne: the already mentioned address by J.M. Coetzee, the conversation with the Author, and an article devoted to his works written by Robert Kusek
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