1,720,952 research outputs found
Airborne Wind Energy Systems for Mars Habitats
No full textUsing renewable energy to power a Mars habitat is a technological challenge because resources such as solar and wind are significantly weaker than on Earth. This work investigates the feasibility of using airborne wind energy (AWE) systems in combination with solar photovoltaic (PV) modules to power a Mars habitat. The Luchsinger model and the higher fidelity QSM are used to simulate the performance of the AWE system and compared. This thesis builds upon two earlier design synthesis exercise (DSE) projects by implementing a version of the quasi-steady model (QSM) that accounts for the transition phase, models a realistic retraction trajectory, and accounts for the mass of the airborne components. Additionally, the results of the first DSE indicate that the Luchsinger model used did not appear to consume any energy during the reel-in phase, which is not realistic and led to an over-prediction of mean cycle power. However, this thesis aims to implement the Luchsinger model correctly. Creating a road map for sizing AWE kite systems on Mars is the main objective of this thesis. Since the performance of the AWE system is varying in time and space, the Mars Climate Database (MCD) is used to retrieve atmospheric and surface solar flux data including wind Weibull probability distribution functions (PDF). The second DSE used the MCD and validated the results against wind data from various Mars landers. The MCD is based on numerical simulations of the Martian atmosphere using a general circulation model and validated with available observational data. Seasonal vertical wind profiles are generated from the meteorological data to characterise the boundary layer over time. A scaling study assesses how AWE on Mars differs from that on Earth, performing dimensional analysis. In the system characteristics chapter, the initial sizing of the kite area and mass is computed using the scaling study. The performance models create the power curves, which together with the wind PDFs and surface solar flux data are used in the habitat energy model to verify whether the power requirements are met. Due to an insufficient amount of quantitative information on the energy consumption of the robotic construction of the habitat, the design of the microgrid is covering only the use of the habitat, which is 10 kW of continuous power. This is similar to remote off-grid solutions on Earth, with the additional challenge of having lower resource availability, both for wind and solar. This thesis concludes that various configurations of a hybrid power plant can continuously provide 10 kW of power throughout the entire Martian year. Moreover, the results indicate that using kites alone could generate sufficient power for the habitat without using solar PV.Rhizome project: http://www.roboticbuilding.eu/project/rhizome-development-of-an-autarkic-design-to-robotic-production-and-operation-system-for-building-off-earth-habitats/ Published poster on thesis for Airborne Wind Energy Conference in Milano, Italy,: https://repository.tudelft.nl/islandora/object/uuid%3A4013ca0b-5508-4413-b8cb-5251ca1e7781 Video made to illustrate how Mars flight would look like.: https://www.youtube.com/watch?v=YS20vHhqgKk&ab_channel=AirborneWindEnergyOnlineRhizomeEuropean Wind Energy Masters (EWEM
Safety Assessment for the Implementation of Autonomous Haulage Systems in an Open-Pit Mine
No full textThe implementation of autonomous haulage systems in open-pit mines is a progressive step in the industry, but it brings potential safety risks that need careful evaluation. This study developed a discrete event simulation model to analyze and evaluate these risks in different operating scenarios -fully autonomous, hybrid (a mix of autonomous and human-operated vehicles), and non-autonomous operations.The simulation model was developed using the HAULSIM and Anylogic software, integrated mine layout, haulage operations, and various fleet compositions. It provided insights into collision risks, a significant concern in mining safety literature. Results showed that collisions were inversely proportional to the number of autonomous vehicles in operation, indicating the potential safety advantages of fully autonomous operations. However, certain high-traffic intersections were identified as high-risk areas, emphasizing the need for targeted risk mitigation strategies. Further, a profile risk matrix was developed to provide a comprehensive view of collision severity and likelihood in each scenario. This highlighted the impact of collisions on both human safety and project operations. Based on the results, risk mitigation strategies were proposed, with a focus on redesigning intersections, implementing strict rules for human-operated trucks in autonomous zones, and improving autonomous vehicle capabilities. The study, while insightful, was limited by assumptions and the generic nature of operational data used in the simulation. Therefore, future research should seek to incorporate more detailed, mine-specific data and empirical insights from projects that have implemented autonomous haulage systems. Continuous advancements in autonomous technology and simulation modeling will be key to ensuring a safe and productive mining environment.Applied Earth Science
Inflationary rigidities and stabilization policies
Full text linkLatin American countries provide the best living laboratory to study inflationary processes and stabilization programs. The purpose of this paper is to analyze the experience with orthodox stabilization policies, which are based on a tight fiscal stance and not supported by a system of price controls. The analysis of these policies is structured as follows. Part I analyzes in detail the question of why purely orthodox policies were especially effective in stopping hyperinflation as opposed to chronic inflation processes. Part II turns to chronic inflation countries and analyzes three basic types of stabilization. The first type is based almost exclusively on fiscal adjustment. The second considers programs which employ nominal anchors in conjunction with fiscal adjustments. The third type examines the exchange rate based stabilizations which often evolve out of a monetary-fiscal package. In the final part of the paper, the authors consider the long run view which extends beyond specific programs and emphasizes the importance of persistence in fiscal discipline and in adherence to nominal anchors.Environmental Economics&Policies,Inflation,Banks&Banking Reform,Economic Stabilization,Economic Theory&Research
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The virtual image : Brazilian literature in English translation
Full text linkThe
aim of this thesis is to
examine
how the virtual
image
of Brazil
and
its literature is
constructed
in the Anglo-American world. To this
end, a survey of
Brazilian literary
works
in English translation was
carried out.
Having
gathered this data, it became
possible to establish
correlations
between the historical
moments when such translations
were made, when their number
increased,
and the events occurring at
those times in the international
panorama, as well as to look into the
role of sponsors, publishers and translators in the
selection and
production of such translations.
The data
also allowed a profile of
Brazilian literary
works
in
English translation to be drawn. It became
possible to suggest that
such works
fall into four
main categories:
`authorial
works',
'topical
works',
`ambassadorial
works'
and `consumer-oriented
works'.
In
order
to look
more closely
into how the translation process
has helped to
shape
the
virtual
image
of Brazilian literary
works
in
the Anglo-American world, an analysis of a sample of
translations
of
such works was made. Included in this
sample were
the translations
of works
by Machado de Asis, by Indianist
and
Regionalist
wirters,
culminating
in
an examination of translations of
GuimarAes Rosa's
works.
Having looked
at these aspects of
the translation
process, what
remained
to be done
was to investigate
to what extent
Brazilian
literary
works
in English translation
are read
by the English-
speaking public.
To this
end, a survey of availability and
library
readership was undertaken. Finally,
a reading experiment was carried
out
in
which native speakers of
English
were asked to read the short
story
'A terceira
margem
do
rio',
by GuimarAes Rosa.
The
conclusion attempts to pull all these threads together and
to indicate directions for further
research
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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