409 research outputs found
LIPIcs, Volume 251, ITCS 2023, Complete Volume
LIPIcs, Volume 251, ITCS 2023, Complete Volum
LIPIcs, Volume 261, ICALP 2023, Complete Volume
LIPIcs, Volume 261, ICALP 2023, Complete Volum
The Vibrancy and Resilience of British High Streets
British high streets have endured significant economic and cultural challenges both in the leadup to and as a consequence of the COVID-19 pandemic. The volatile and challenging socio-economic environment has been brought about by the lingering effects of the 2008 recession, high business rates, competition from online retailers, and the impact and implications of the global pandemic. The changes to the high street retail landscape have been recorded using new sources of data that can supplement traditional data sources such as local government retail surveys. New sources of data such as consumer data, property portal data and mobility data are more spatially and temporally granular. As a result, local governments, the retail sector and stakeholders can use these emerging forms of data to create more easily updateable measures of high street composition and performance. This thesis utilises the Local Data Companyâs Britain-wide database on retail location, type and vacancy. The data ranges between the start of 2017 and June of 2021, containing around 800,000 records of occupiers. The analysis within this thesis starts by describing the composition and vibrancy of British high streets in the lead-up to the pandemic. Next, the thesis provides an evaluation of the impact of the COVID-19 pandemic and the subsequent shift towards remote working on the viable resilience of commuter towns. This section is followed by an exploration of the short-term impacts of the COVID-19 lockdown restrictions on the resilience of Britainâs high streets. Finally, the application of new forms of data in informing local government high street regeneration policy is studied as part of a knowledge exchange with the London Borough of Camden. This thesis contributes to our understanding of how the circumstances of different British high streets can be monitored and mapped, with the goal of improving understanding of vibrancy, resilience, and potential for regeneration
Analysis and Visualization of Higher-Order Tensors: Using the Multipole Representation
Materialien wie Kristalle, biologisches Gewebe oder
elektroaktive Polymere kommen hÀufig in verschiedenen
Anwendung, wie dem Prothesenbau oder der Simulation von
kĂŒnstlicher Muskulatur vor.
Diese und viele weitere Materialien haben gemeinsam, dass sie
unter gewissen UmstÀnden ihre Form und andere
Materialeigenschaften Àndern.
Um diese VerÀnderung beschreiben zu können, werden, abhÀngig
von der Anwendung, verschiedene Tensoren unterschiedlicher
Ordnung benutzt.
Durch die KomplexitÀt und die starke AbhÀngigkeit der
Tensorbedeutung von der Anwendung, gibt es bisher kein
Verfahren Tensoren höherer Ordnung darzustellen, welches
standardmĂ€Ăig benutzt wird.
Auch bezogen auf einzelne Anwendungen gibt es nur sehr wenig
Arbeiten, die sich mit der visuellen Darstellung dieser
Tensoren auseinandersetzt.
Diese Arbeit beschÀftigt sich mit diesem Problem.
Es werden drei verschiedene Methoden prÀsentiert, Tensoren
höherer Ordnung zu analysieren und zu visualisieren.
Alle drei Methoden basieren auf der sogenannte deviatorischen
Zerlegung und der Multipoldarstellung.
Mit Hilfe der Multipole können die Symmetrien des Tensors
und damit des beschriebenen Materials bestimmt werden.
Diese Eigenschaft wird in fĂŒr die Visualisierung
des Steifigkeitstensors benutzt.
Die zweite Methode basiert direkt auf den Multipolen und kann
damit beliebige Tensoren in drei Dimensionen darstellen.
Dieses Verfahren wird anhand des Kopplungs Tensors, ein Tensor
dritter Ordnung, vorgestellt.
Die ersten zwei Verfahren sind lokale Glyph-basierte Verfahren.
Das dritte Verfahren ist ein erstes globales
Tensorvisualisierungsverfahren, welches Tensoren beliebiger
Ordnung und Symmetry in drei Dimensionen mit Hilfe eines
linienbasierten Verfahrens darstellt.Materials like crystals, biological tissue or electroactive
polymers are frequently used in applications like prosthesis
construction or the simulation of artificial musculature.
These and many other materials have in common that they
change their shape and other material properties under
certain circumstances.
To describe these changes, different tensors of different
order, dependent of the application, are used.
Due to the complexity and the strong dependency of the
tensor meaning of the application, there is, by now, no
visualization method that is used by default.
Also for specific applications there are only a few methods
that address the visual analysis of higher-order tensors.
This work adresses this problem.
Three different methods to analyse and visualize tensors of
higher order will be provided.
All three methods are based on the so called deviatoric
decomposition and the multipole representation.
Using the multipoles the symmetries of a tensor and, therefore,
of the described material, can be calculated.
This property is used to visualize the stiffness tensor.
The second method uses the multipoles directly and can be
used for each tensor of any order in three dimensions.
This method is presented by analysing the third-order
coupling tensor.
These two techniques are glyph-based visualization methods.
The third one, a line-based method, is, according to our
knowledge, a first global visualization method that can be
used for an arbitrary tensor in three dimensions
Future Trends in Advanced Materials and Processes
The Special Issue âFuture Trends in Advanced Materials and Processesâ contains original high-quality research papers and comprehensive reviews addressing the relevant state-of-the-art topics in the area of materials focusing on relevant or innovative applications such as radiological hazard evaluations of non-metallic materials, composite materials' characterization, geopolymers, metallic biomaterials, etc
X-ray Phase Contrast Tomography : Setup and Scintillator Development
X-ray microscopy and micro-tomography (ÎŒCT) are valuable non-destructive examination methods in many disciplines such as bio-medical research, archaeometry, material science and paleontology. Besides being implemented at synchrotrons radiation sources, laboratory setups using an X-ray tube and high-resolution scintillation detector routinely provide information on the micrometre scale. To improve the image contrast for small and low-density samples, it is possible to introduce a propagation distance between sample and detector to perform propagation-based phase contrast imaging (PB-PCI). This contrast mode relies on a sufficiently coherent illumination and is characterised by the appearance of an additional intensity modulations (âedge enhancement fringesâ) around interfaces in the image. The strength of this effect depends on hardware as well as geometry parameters. This thesis describes the development of a laboratory setup for X-ray ÎŒCT with a PB-PCI option. It contains the theoretical and technical background of the setup design as well the characterization of the achieved performance.Moreover, the optimization of the PB-PCI geometry was explored both theoretically as well as experimentally for three different setups. A simple rule for finding the optimal magnification to achieve high phase contrast for edge features was deduced. The effect of the polychromatic source spectrum und detector sensitivity was identified and included into the theoretical model.Besides application and methodological studies, the setup was used to test and characterise new X-ray scintillator materials. Recently, metal halide perovskite nanocrystals (MHP NCs) have gained attention due to their outstanding opto-electronic performance. The main challenge for their use and commercialization is their low long-term stability against humidity, temperature, and light exposure. Here, a CsPbBr3 scintillator comprised of an ordered array of nanowires (NW) in an anodized aluminium oxide (AAO) membrane is presented as a promising new scintillator for X-ray microscopy and ÎŒCT. It shows a high light yield under X-ray exposure which improves with smaller NW diameter and higher NW length. In contrast to many other MHP materials this scintillator shows good stability under continuous X-ray exposure and changing environmental conditions over extended time spans of several weeks. This makes it suitable for tomography, which is demonstrated by acquiring the first high-resolution tomogram using a MHP scintillator with the presented laboratory setup
LIPIcs, Volume 258, SoCG 2023, Complete Volume
LIPIcs, Volume 258, SoCG 2023, Complete Volum
Physics of Soil and Other Natural Porous Media
The purpose of this monograph is to review the early theoretical basis of
what is known today as soil physics and to serve as a textbook for intermediate
porous media physics or transport in porous media graduate courses.Comment: 219 pages, 42 figure
Multi-field modeling and simulation of fiber-reinforced polymers
This work proposes a new numerical approach for analyzing the behavior of fiber-reinforced materials, which have gained popularity in various applications. The approach combines theories and methods to model the fracture behavior of the polymeric matrix and the embedded fibers separately, and includes a modified plasticity model that considers the temperature-dependent growth of voids. Tests are conducted to explore different types and sequences of failure in long fiber-reinforced polymers
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