Representation of odometry errors on occupancy grids

SOUZA, Anderson A. S. ; SANTANA, André M. ; BRITTO, Ricardo S. ; GONÇALVES, Luiz Marcos G. ; MEDEIROS, Adelardo A. D. Representation of Odometry Errors on Occupancy Grids. In: INTERNATIONAL CONFERENCE ON INFORMATICS IN CONTROL, AUTOMATION AND ROBOTICS, 5., 2008, Funchal, Portugal. Proceedings... Funchal, Portugal: ICINCO, 2008.

X-ray vision: mental representation of the human body’s inner morphology

This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Beneath the surface of the heritage enterprise. Governmentality and cultural representation of rural architecture in Portugal

This article focuses on the construction of heritage in rural Portugal. Drawing on anthropological fieldwork in the village of Castelo Rodrigo, it analyses the extensive protection and exhibition of domestic architecture in the framework of a State-led local development programme. By bringing in the messiness of daily practices, the article goes beyond neat theoretical formulations in the study of heritage such as Foucault’s theory of “governmentality” and Kirshenblatt-Gimblett’s notion of “second life as heritage”. It argues that the “conduct of conduct” is actually nowhere near as effective as its theoretical formulation might have us believe, and the second life as heritage suffocates the first life of houses as social habitats for the village population.

The ins and outs of biosecurity: bird 'flu in East Anglia and the spatial representation of risk

Avian influenza, or 'bird 'flu' arrived in Norfolk in April 2006 in the form of the low pathogenic strain H7N3. In February 2007 a highly pathogenic strain, H5N1, which can pose a risk to humans, was discovered in Suffolk. We examine how a local newspaper reported the outbreaks, focusing on the linguistic framing of biosecurity. Consistent with the growing concern with securitisation among policymakers, issues were discussed in terms of space (indoor–outdoor; local–global; national–international) and flows (movement, barriers and vectors) between spaces (farms, sheds and countries). The apportioning of blame along the lines of 'them and us'– Hungary and England – was tempered by the reporting on the Hungarian operations of the British poultry company. Explanations focused on indoor and outdoor farming and alleged breaches of biosecurity by the companies involved. As predicted by the idea of securitisation, risks were formulated as coming from outside the supposedly secure enclaves of poultry production.

Bahadur representation of linear kernel quantile estimator of VaR under mixing assumptions

Bahadur representation and its applications have attracted a large number of publications and presentations on a wide variety of problems. Mixing dependency is weak enough to describe the dependent structure of random variables, including observations in time series and longitudinal studies. This note proves the Bahadur representation of sample quantiles for strongly mixing random variables (including ½-mixing and Á-mixing) under very weak mixing coe±cients. As application, the asymptotic normality is derived. These results greatly improves those recently reported in literature.

Efficient representation of texture details in medical images by fusion of Ripplet and DDCT transformed images

Purpose: To evaluate and compare the performance of Ripplet Type-1 transform and directional discrete cosine transform (DDCT) and their combinations for improved representation of MRI images while preserving its fine features such as edges along the smooth curves and textures. Methods: In a novel image representation method based on fusion of Ripplet type-1 and conventional/directional DCT transforms, source images were enhanced in terms of visual quality using Ripplet and DDCT and their various combinations. The enhancement achieved was quantified on the basis of peak signal to noise ratio (PSNR), mean square error (MSE), structural content (SC), average difference (AD), maximum difference (MD), normalized cross correlation (NCC), and normalized absolute error (NAE). To determine the attributes of both transforms, these transforms were combined to represent the entire image as well. All the possible combinations were tested to present a complete study of combinations of the transforms and the contrasts were evaluated amongst all the combinations. Results: While using the direct combining method (DDCT) first and then the Ripplet method, a PSNR value of 32.3512 was obtained which is comparatively higher than the PSNR values of the other combinations. This novel designed technique gives PSNR value approximately equal to the PSNR’s of parent techniques. Along with this, it was able to preserve edge information, texture information and various other directional image features. The fusion of DDCT followed by the Ripplet reproduced the best images. Conclusion: The transformation of images using Ripplet followed by DDCT ensures a more efficient method for the representation of images with preservation of its fine details like edges and textures.

A Critique of the Representation of Violence in American Literature:

The purpose of this thesis was to draw new insights on Thomas Berger’s classic American novel, Little Big Man, and his representation of fictional violence that is a substantial aspect of any text on the Indian Wars and “Custer’s Last Stand”. History’s major world wars led to shifts in the political climate and a noted change in the way that violence was represented in the arts. Historical, fictional, and cinematic treatments of “Custer’s Last Stand” and violence were each considered in relation to the text. Berger's version of the famed story is a revision of history that shows the protagonist as a dual-member of two violent societies. The thesis concluded that Berger’s updated American legends and unique “white renegade” character led to a representation of violence that spoke to the current state of affairs in 1964 when the world was becoming much more hostile and chaotic place.

A dedicated greedy pursuit algorithm for sparse spectral representation of music sound

A dedicated algorithm for sparse spectral representation of music sound is presented. The goal is to enable the representation of a piece of music signal as a linear superposition of as few spectral components as possible, without affecting the quality of the reproduction. A representation of this nature is said to be sparse. In the present context sparsity is accomplished by greedy selection of the spectral components, from an overcomplete set called a dictionary. The proposed algorithm is tailored to be applied with trigonometric dictionaries. Its distinctive feature being that it avoids the need for the actual construction of the whole dictionary, by implementing the required operations via the fast Fourier transform. The achieved sparsity is theoretically equivalent to that rendered by the orthogonal matching pursuit (OMP) method. The contribution of the proposed dedicated implementation is to extend the applicability of the standard OMP algorithm, by reducing its storage and computational demands. The suitability of the approach for producing sparse spectral representation is illustrated by comparison with the traditional method, in the line of the short time Fourier transform, involving only the corresponding orthonormal trigonometric basis.

A functional representation of almost isometries

For each quasi-metric space X we consider the convex lattice SLip(1)(X) of all semi-Lipschitz functions on X with semi-Lipschitz constant not greater than 1. If X and Y are two complete quasi-metric spaces, we prove that every convex lattice isomorphism T from SLip(1)(Y) onto SLip(1)(X) can be written in the form Tf = c . (f o tau) + phi, where tau is an isometry, c > 0 and phi is an element of SLip(1)(X). As a consequence, we obtain that two complete quasi-metric spaces are almost isometric if, and only if, there exists an almost-unital convex lattice isomorphism between SLip(1)(X) and SLip(1) (Y).

Cyclone systems over the Aegean Sea. A statistical representation of their main characteristics

Il Mar Egeo è un bacino chiuso dove ha luogo una parte significativa dell'attività ciclonica del Mediterraneo. Inoltre, è circondato da città densamente popolate e ricche di risorse, quindi essere in grado di tracciare ed esaminare le caratteristiche degli intensi fenomeni meteorologici come i cicloni può prevenire i pericoli naturali che provocano perdite umane e danni economici. Questo studio tratta le caratteristiche principali dei sistemi a bassa pressione avvenuti nel Mar Egeo dal 1979 al 2020 ed è basato sul dataset di ERA5. Nello specifico, si tratta di un’analisi statistica delle loro caratteristiche come il numero medio di occorrenza per ogni mese dell’anno, la loro velocità di propagazione, la loro durata, la distanza percorsa dal momento della loro formazione fino al punto della loro dissipazione, lo spostamento fra la posizione di formazione e di dissipazione nonché` la loro distribuzione spaziale nelle 4 stagioni. Quello che è stato osservato è un’attività ciclonica rilevante che ha luogo nel Mar Egeo che costituisce uno dei posti del Mediterraneo con attività ciclonica non trascurabile. Si è fatto un confronto quantitativo tra i cicloni e più in generale le attività cicloniche che passano o nascono nel Mar Egeo con i cicloni che hanno luogo nel Mediterraneo nel suo complesso e quello che è stato trovato è che il Mar Egeo è un’area del Mediterraneo con attività ciclonica rilevante, e con caratteristiche simili dei cicloni che avvengono nel Mar Mediterraneo.

Advanced representation of the ocean/sea ice dynamics at high latitudes

Sea ice is a fundamental element of global climate system, with numerous impacts on the polar environment. The ongoing drastic changes in the Earth’s sea ice cover highlight the necessity of monitoring the polar regions and systematically evaluating the quality of different numerical products. The main objective of this thesis is to improve our knowledge of the representation of Arctic and Antarctic sea ice using comprehensive global ocean reanalyses and coupled climate models. The dissertation will explore (i) the Antarctic marginal ice zone (MIZ) and pack ice area in the ensemble mean of four global ocean reanalyses called GREP; (ii) historical representation of the Arctic and Antarctic sea ice state in HighResMIP models; (iii) the future evolution of Arctic sea ice in HighResMIP models. Global ocean reanalyses and GREP are found to adequately capture interannual and seasonal variability in both pack ice and MIZ areas at hemispheric and regional scales. The advantage of the ensemble-mean approach is proved as GREP smooths the strengths and weaknesses of single systems and provides the most consistent and reliable estimates. This work is intended to encourage the use of GREP in a wide range of applications. The analysis of sea ice representation in the coupled climate models shows no systematic impact of the increased horizontal resolution. We argue that a few minor improvements in sea ice representation with the enhanced horizontal resolution are presumably not worth the major effort of costly computations. The thesis highlights the critical importance to distinguish the MIZ from consolidated pack ice both for investigating changes in sea ice distribution and evaluating the product’s performance. Considering that the MIZ is predicted to dominate the Arctic sea ice cover, the model physics parameterizations and sea ice rheology might require modifications. The results of the work can be useful for modelling community.

Stochastic physics and representation of El Niño Southern Oscillation in climate models

El Niño-Southern Oscillation (ENSO) è il maggiore fenomeno climatico che avviene a livello dell’Oceano Pacifico tropicale e che ha influenze ambientali, climatiche e socioeconomiche a larga scala. In questa tesi si ripercorrono i passi principali che sono stati fatti per tentare di comprendere un fenomeno così complesso. Per prima cosa, si sono studiati i meccanismi che ne governano la dinamica, fino alla formulazione del modello matematico chiamato Delayed Oscillator (DO) model, proposto da Suarez e Schopf nel 1988. In seguito, per tenere conto della natura caotica del sistema studiato, si è introdotto nel modello lo schema chiamato Stochastically Perturbed Parameterisation Tendencies (SPPT). Infine, si sono portati due esempi di soluzione numerica del DO, sia con che senza l’introduzione della correzione apportata dallo schema SPPT, e si è visto in che misura SPPT porta reali miglioramenti al modello studiato.

Uber Kartenprojection. Abhandlungen von Lagrange (1779) und Gauss (1822)

Mode of access: Internet.

Modeling Yield Surfaces of Various Structural Shapes

This study investigates the possibility of custom fitting a widely accepted approximate yield surface equation (Ziemian, 2000) to the theoretical yield surfaces of five different structural shapes, which include wide-flange, solid and hollow rectangular, and solid and hollow circular shapes. To achieve this goal, a theoretically “exact” but overly complex representation of the cross section’s yield surface was initially obtained by using fundamental principles of solid mechanics. A weighted regression analysis was performed with the “exact” yield surface data to obtain the specific coefficients of three terms in the approximate yield surface equation. These coefficients were calculated to determine the “best” yield surface equation for a given cross section geometry. Given that the exact yield surface shall have zero percentage of concavity, this investigation evaluated the resulting coefficient of determination (