6,758 research outputs found

    Urbanised forested landscape: Urbanisation, timber extraction and forest care on the Vișeu Valley, northern Romania

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    By looking at urbanisation processes from the vantage point of the forest, and the ways in which it both constitutes our living space while having been separated from the bounded space of the urban in modern history, the thesis asks: How can we (re)imagine urbanisation beyond the limits of the urban? How can a feminine line of thinking engage with the forest beyond the capitalist-colonial paradigm and its extractive project? and How can we “think with care” (Puig de la Bellacasa 2017) towards the forest as an inhabitant of our common world, instead of perpetuating the image of the forest as a space outside the delimited boundaries of the city? Through a case study research, introducing the Vișeu Valley in northern Romania as both a site engaged in the circulation of the global timber flow, a part of what Brenner and Schmid (2014) name “planetary urbanisation”, where the extractive logging operations beginning in the late XVIIIth century have constructed it as an extractive landscape, and a more than human landscape inhabited by a multitude of beings (animal, plant, and human) the thesis argues towards the importance of forest care and indigenous knowledge in landscape management understood as a trans-generational transmission of knowledge, that is interdependent with the persistence of the landscape as such. Having a trans-scalar approach, the thesis investigates the ways in which the extractive projects of the capitalist-colonial paradigm have and still are shaping forested landscapes across the globe in order to situate the case as part of a planetary forest landscape and the contemporary debates it is engaged in. By engaging with emerging paradigms within the fields of plant communication, forestry, legal scholarship and landscape urbanism that present trees and forests as intelligent beings, and look at urbanisation as a way of inhabiting the landscape in both indigenous and modern cultures, the thesis argues towards viewing forested landscapes as more than human living spaces. Thinking urbanisation through the case of the Vișeu Valley’s urbanised forested landscape, the thesis aligns with alternate ways of viewing urbanisation as co-habitation with more than human beings, particularly those emerging from interdisciplinary research in the Amazon river basin (Tavares 2017, Heckenberger 2012) and, in light of emerging discourses on the rights of nature, proposes an expanded concept of planetary citizenship, to include non-human personhood

    Beam scanning by liquid-crystal biasing in a modified SIW structure

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    A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium

    Signed double Roman domination on cubic graphs

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    The signed double Roman domination problem is a combinatorial optimization problem on a graph asking to assign a label from {±1,2,3}\{\pm{}1,2,3\} to each vertex feasibly, such that the total sum of assigned labels is minimized. Here feasibility is given whenever (i) vertices labeled ±1\pm{}1 have at least one neighbor with label in {2,3}\{2,3\}; (ii) each vertex labeled −1-1 has one 33-labeled neighbor or at least two 22-labeled neighbors; and (iii) the sum of labels over the closed neighborhood of any vertex is positive. The cumulative weight of an optimal labeling is called signed double Roman domination number (SDRDN). In this work, we first consider the problem on general cubic graphs of order nn for which we present a sharp n/2+Θ(1)n/2+\Theta(1) lower bound for the SDRDN by means of the discharging method. Moreover, we derive a new best upper bound. Observing that we are often able to minimize the SDRDN over the class of cubic graphs of a fixed order, we then study in this context generalized Petersen graphs for independent interest, for which we propose a constraint programming guided proof. We then use these insights to determine the SDRDNs of subcubic 2×m2\times m grid graphs, among other results

    The Diasporic Sublime in the Works of Bharati Mukherjee, Jhumpa Lahiri, and Chitra Banerjee Divakaruni

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    The doctoral research aims to redefine the theory of the sublime within the transcultural identities through the works of Bharati Mukherjee, Jhumpa Lahiri, and Chitra Banerjee Divakaruni. The involvement and elevation of Indian American women in migration has not been emphasised enough in the discussion of indentured labour, globalization and effects of cultural appropriation. Considering the German traditions of aesthetics, specifically Immanuel Kant’s theorization of the sublime in his Observations on the Feeling of the Beauty and the Sublime (1790/2011), the dissertation focuses to challenge the specific Kantian notion of female inability to be the sovereign and elevated (sublime) subject. ‘Diasporic sublime’ hence highlights the journey of Indian immigrant women in the United States of America and facing the conflicts to reach the sublime state of body and mind. The dissertation structures the conceptualisation of the postcolonial fear, power and agency through the changes of body, food and home to evince the manifestation of the sublime. Following the contemporary works of Christina Battersby, Bonnie Mann and Barbara Claire Freeman, the dissertation renegotiates the term sublime as a process to confront the submissive identity, dehumanised socio-economical state of immigrant women

    Non-equilibrium wall-bounded turbulence and associated noise generation

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    Abstract : The present study investigates the response of turbulence in a non-equilibrium flows such as transient periodic channel flows and spatially developing boundary layers subjected to pressure gradients. Such a fundamental study is important to understand noise generation in complex wall-bounded turbulent flows. First, to understand the flow dynamics in transient accelerating flows, direct numerical simulations (DNS) of periodic channel flows responding to an impulse acceleration are carried out. The turbulent flow undergoes reverse transition toward a quasi-laminar state, followed by a retransition phase to the new equilibrium state. To reduced simulation cost, the minimal-span methodology is applied and evaluated for simulations of transient flows. Detailed comparisons with a full-span case show that the small-span test case captures the essential dynamics during the transition process despite small, quantitative differences attributed to a slower streak transient growth. A small span is used to characterize accelerating channels with riblets. Results indicate that riblets delay the transition to high Reynolds number state, as it reduces streak meandering. Next, to study non-equilibrium boundary layer flows in the presence of convex wall curvature, DNS simulations over an airfoil (suction side) and a flat plate are compared. Both cases are characterized by matching adverse pressure gradient (APG) along the streamwise direction. For the airfoil boundary layer, existing DNS data obtained by \cite{wu2019effects} of flow around a controlled-diffusion (CD) airfoil is used. For the flat-plate boundary layer, a DNS simulation is carried out, with prescribed pressure gradient distribution that matches that of the airfoil flows in the APG region. Comparison between the two cases shows how the wall curvature affects turbulence in an APG boundary layer, important in industrial applications such as fan flows. Overall, the comparison shows that the boundary layer developments are very similar. This indicates that a flat-plate boundary layer can serve as a low-cost surrogate of an airfoil boundary layer in numerical studies of important features of an airfoil flow. The difference between the two cases represents the effect of a mild convex wall curvature. Specifically, in the region of weak APG, the curvature effect dominates that of the pressure gradient and yields a lower friction coefficient. In high-APG regions (near the trailing edge of the airfoil) the effects of wall curvature and APG appear to interact. Lastly, various existing analytical models are evaluated on their predictions of wall pressure fluctuations, which are essential for noise prediction in non-equilibrium boundary layer turbulent flows that develop on fan blades. Limitations of the existing models are evaluated; new parameters that do not involve the ill-defined wall friction in a boundary layer under strong adverse pressure gradients are proposed. The primary role of the mean velocity logarithmic layer in affecting the overlap range of the wall pressure spectrum is also demonstrated. A new wall pressure spectrum model is proposed and tested in a wide range of boundary layer flows under different Reynolds numbers and zero, adverse and favorable pressure gradients. The test database includes existing experimental data and various DNS flat-plate simulations. The new wall pressure spectrum model is the first generalized model designed for boundary layer flows with a wide range of pressure gradients and Reynolds numbers.Ce mĂ©moire Ă©tudie la rĂ©ponse de la turbulence dans des Ă©coulements hors Ă©quilibre, tels que les Ă©coulements transitoires dans un canal pĂ©riodique et les couches limites se dĂ©veloppant spatiallement soumises Ă  des gradients de pression. Une telle Ă©tude fondamentale est importante pour comprendre la gĂ©nĂ©ration du bruit dans des Ă©coulements complexes turbulents. PremiĂšrement, pour comprendre la dynamique d’écoulements transitoires soumis Ă  une accĂ©lĂ©ration, des simulations directes d’écoulements instationnaires dans un canal pĂ©riodique soumis Ă  une accĂ©lĂ©ration impulsionnelle ont Ă©tĂ© rĂ©alisĂ©es. L’écoulement turbulent subit une transition inversĂ©e vers un Ă©tat quasi-laminaire, suivi par une nouvelle phase de transition vers un nouvel Ă©quilibre. Pour rĂ©duire le coĂ»t de calcul, la mĂ©thode de l’envergure minimale du domaine de calcul est appliquĂ©e et validĂ©e pour de telles simulations instationnaires. Des comparaisons dĂ©taillĂ©es avec un cas d’envergure complĂšte montrent que la simulation avec une envergure minimale capture l’essentiel de la dynamique de l’écoulement durant la phase de transition et ce malgrĂ© quelques petites diffĂ©rences attribuĂ©es Ă  la croissance plus lente des tourbillons longitudinaux le long de la paroi (“streaks”). Une envergure rĂ©duite est ensuite appliquĂ©e Ă  l’étude d’un Ă©coulement accĂ©lĂ©rĂ© dans un canal avec de micro-sillons ou “riblets”. Les rĂ©sultats montrent que les riblets retardent la transition du fait qu’ils stabilisent la turbulence de proche paroi. DeuxiĂšmement, pour Ă©tudier les couches limites hors Ă©quilibre sur une paroi convexe, des simulations directes sur l’extrados d’un profil aĂ©rodynamique et d’une plaque plane sont comparĂ©es. Les deux cas sont caractĂ©risĂ©s par le mĂȘme gradient de pression adverse dans la direction de l’écoulement. Pour la couche limite sur le profil, on utilise les donnĂ©es existantes de la simulation directe de Wu et al. (2019) autour du profil Ă  diffusion controllĂ©e (CD). Pour la couche limite sur la plaque plane, une nouvelle simulation directe a Ă©tĂ© rĂ©alisĂ©e avec le mĂȘme gradient de pression adverse que sur le profil. La comparaison des deux cas montre que la courbure de la paroi convexe peut modifier la turbulence dans une couche limite soumise Ă  un gradient de pression adverse qui est important dans les applications industrielles comme les Ă©coulements dans des ventilateurs. Cependant les modifications restent mineures et la comparaison montre que le dĂ©veloppement des couches limite turbulentes dans les deux cas est semblable. Ceci implique que la couche limite sur une plaque plaque sur un domaine rĂ©duit peut servir de substitut Ă  celle sur un profil aĂ©rodynamique qui requiert un domaine plus grand et des ressources de calcul plus importante. La diffĂ©rence observĂ©e entre les deux cas permet d’évaluer l’effet d’une paroi faiblement convexe. SpĂ©cifiquement, dans la rĂ©gion de faible gradient de pression adverse, les effets de courbure dominent ceux du gradient de pression et rĂ©duisent le coefficient de frottement pariĂ©tal. Dans les zones de fort gradient de pression adverse, prĂšs du bord de fuite, les effets de gradient de pression et de courbure interagissent. Finalement, la derniĂšre Ă©tape a Ă©tĂ© d’évaluer les diffĂ©rents modĂšles analytiques de fluctuations de pression pariĂ©tale qui sont au centre des prĂ©dictions de bruit dans les couches limites turbulentes hors Ă©quilibre qui se dĂ©veloppent sur les pales de ventilateurs. Les limites des modĂšles prĂ©cĂ©dents sont Ă©valuĂ©es et de nouveaux paramĂštres ne faisant pas intervenir le frottement pariĂ©tal mal dĂ©fini dans une couche limite Ă  fort gradient de pression adverse sont proposĂ©s. Le rĂŽle primordial de la zone logarithmique dans la couche limite turbulente sur le gabarit spectral des spectres de pression pariĂ©tale est aussi mis en Ă©vidence. Le nou veau modĂšle de spectre de pression pariĂ©tale est ensuite testĂ© sur plusieurs couches limites attachĂ©es avec des gradients de pression favorables, adverses, et des Ă©coulements dĂ©collĂ©s Ă  divers nombres de Reynolds basĂ©s sur l’épaisseur de quantitĂ© de mouvement. Les donnĂ©es proviennent de bases de donnĂ©es expĂ©rimentales et numĂ©riques existantes. Des simulations directes supplĂ©mentaires ont Ă©galement Ă©tĂ© rĂ©alisĂ©es pour Ă©tendre les rĂ©sultats numĂ©riques (notamment sur le profil CD) Ă  des nombres de Reynolds plus Ă©levĂ©s. Pour la premiĂšre fois, un modĂšle est capable de reproduire les spectres de pression pariĂ©tale pour tous ces types d’écoulement

    A Theory of Emergent In-Context Learning as Implicit Structure Induction

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    Scaling large language models (LLMs) leads to an emergent capacity to learn in-context from example demonstrations. Despite progress, theoretical understanding of this phenomenon remains limited. We argue that in-context learning relies on recombination of compositional operations found in natural language data. We derive an information-theoretic bound showing how in-context learning abilities arise from generic next-token prediction when the pretraining distribution has sufficient amounts of compositional structure, under linguistically motivated assumptions. A second bound provides a theoretical justification for the empirical success of prompting LLMs to output intermediate steps towards an answer. To validate theoretical predictions, we introduce a controlled setup for inducing in-context learning; unlike previous approaches, it accounts for the compositional nature of language. Trained transformers can perform in-context learning for a range of tasks, in a manner consistent with the theoretical results. Mirroring real-world LLMs in a miniature setup, in-context learning emerges when scaling parameters and data, and models perform better when prompted to output intermediate steps. Probing shows that in-context learning is supported by a representation of the input's compositional structure. Taken together, these results provide a step towards theoretical understanding of emergent behavior in large language models

    Representative set statements for delta-matroids and the Mader delta-matroid

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    We present representative sets-style statements for linear delta-matroids, which are set systems that generalize matroids, with important connections to matching theory and graph embeddings. Furthermore, our proof uses a new approach of sieving polynomial families, which generalizes the linear algebra approach of the representative sets lemma to a setting of bounded-degree polynomials. The representative sets statements for linear delta-matroids then follow by analyzing the Pfaffian of the skew-symmetric matrix representing the delta-matroid. Applying the same framework to the determinant instead of the Pfaffian recovers the representative sets lemma for linear matroids. Altogether, this significantly extends the toolbox available for kernelization. As an application, we show an exact sparsification result for Mader networks: Let G=(V,E)G=(V,E) be a graph and T\mathcal{T} a partition of a set of terminals T⊆V(G)T \subseteq V(G), ∣T∣=k|T|=k. A T\mathcal{T}-path in GG is a path with endpoints in distinct parts of T\mathcal{T} and internal vertices disjoint from TT. In polynomial time, we can derive a graph Gâ€Č=(Vâ€Č,Eâ€Č)G'=(V',E') with T⊆V(Gâ€Č)T \subseteq V(G'), such that for every subset S⊆TS \subseteq T there is a packing of T\mathcal{T}-paths with endpoints SS in GG if and only if there is one in Gâ€ČG', and ∣V(Gâ€Č)∣=O(k3)|V(G')|=O(k^3). This generalizes the (undirected version of the) cut-covering lemma, which corresponds to the case that T\mathcal{T} contains only two blocks. To prove the Mader network sparsification result, we furthermore define the class of Mader delta-matroids, and show that they have linear representations. This should be of independent interest

    A Transcendent View of Things: The Persistence of Metaphysics in Modern German Lyric Poetry, 1771–1908

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    This dissertation explores the lyric poetry of Johann Wolfgang von Goethe, Eduard Mörike, and Rainer Maria Rilke, and it contends that these modern poets retain, albeit uneasily, a view of things as symbols of the transcendent divine. It thus disputes the secularization theory of post-Enlightenment aesthetics. This study specifically challenges the view of symbolism as mere metaphor—an image constructed of arbitrary signs (Nietzsche)—by showing how the epiphanies of modern lyric poetry remain grounded in the metaphysics of analogia, even where (as in Mörike) the writer seems to have left such entanglements behind. The modern poet’s desire to unveil a significant reality beyond subjective impression reveals that symbolic vision necessarily unfolds within the difference between the visible world and the transcendent divine. If signification entails likeness, yet lyric poetry always signifies in and through difference, then a constitutive analogy—that is, the simultaneity of likeness and even greater difference—emerges from within the dynamism of the lyric image itself. Part 1 begins by describing the symbolic image in Goethe’s lyric poetry to recover his view of things as expressing the “holy open mystery” of the cosmos. I show how his symbolism overcomes Enlightenment naturalism by depicting the antecedent order of analogia. Drawing primarily on Neoplatonic metaphysics, the Goethean symbol reveals the partial yet indisputable relatedness of things to the transcendent. Turning to Mörike, part 2 charts his transition to an equivocal understanding of symbol that would sever the image from its numinous source of significance by confining the image to the scope of the poet’s own gaze. Yet Mörike’s poetry also evinces a counter-veiling tendency to de-subjectivize the image, thus yielding a vision of things as they are prior to epistemic concerns, sentiment, and subjective preference. Part 3 contends that Rilke’s thing-poetry evinces a similar tendency to neutralize modernity’s biases against metaphysics. For his poetry recovers an apophatic understanding of symbolism as grounded in analogia that draws on Dionysian theology. His poems thus focus our attention on the thing’s unfathomable capacity for initiating a vision of the divine, of which the thing itself is a partial and fleeting manifestation.Doctor of Philosoph

    Ludotopia

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    Where do computer games »happen«? The articles collected in this pioneering volume explore the categories of »space«, »place« and »territory« featuring in most general theories of space to lay the groundwork for the study of spatiality in games. Shifting the focus away from earlier debates on, e.g., the narrative nature of games, this collection proposes, instead, that thorough attention be given to the tension between experienced spaces and narrated places as well as to the mapping of both of these

    The Freedom of Lights: Edmond JabĂšs and Jewish Philosophy of Modernity

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    Edmond Jabùs was one of the most intriguing Jewish thinkers of the 20th century – a poet for the public and a Kabbalist for those who read his work more closely. This book turns his writings into a ground-breaking philosophical achievement: thinking which is manifestly indebted to the Kabbalah, but in the post-religious and post-Shoah world. Loss, exile, negativity, God’s absence, writing and Jewishness are the main signposts of the negative ontology which this book offers as an interpretation of Jabùs’ work. On the basis of it, the book examines the nature of the miraculous encounter between Judaism and philosophy which occurred in the 20th century. Modern Jewish philosophy is a re-constructed tradition which adapts the intellectual and spiritual legacy of Judaism to answer purely modern questions
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