447 resultados para Infinity


Relevância:

20.00% 20.00%

Publicador:

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In the late 60s it had become clear how the environment technification had allowed some typologies (supermarkets, car parks, factories) to reach potentially unlimited built depths becoming, therefore, independent from the outside. The No-Stop City is born from a very simple idea: to extend this technification to the totality of built reality encompassing, not only almost all functions, but ultimately, the whole city. This operation has paradoxical effects: as architecture grows, it loses most of the features that have traditionally defined it. A dissolution by hypertrophy that gives rise to an homogeneous, concave and potentially infinite space. But beyond the pure technical feasibility, there are two key influences, seemingly contradictory, that explain this endeavor for an interior and endless city: Marxism and Pop Art. The project is, in many senses, a built manifesto reflecting the militancy of the group members within the Italian Marxism. But it is also the embodiment of the groups declared interest in Pop Art, popular culture and mass society. The cross-influence of communism and consumerism explains this "quantitative utopia" in which the society and the factory, the production and consumption, would match. A city based on the centrality of consumer products and the subsequent loss of prominence of architecture, in which the urban phenomenon, while spreading endlessly over territory, ignoring its rural exteriority, dissolves the home as a sphere of privacy, ignoring its domestic interiority. A project, also in the wake of Marshall McLuhan, that illustrates like few others the conversion of the urbane into a virtually omnipresent "condition" and that still interrogates us with questions that are, on the other hand, eternal: What is a building? What is a city?

Relevância:

20.00% 20.00%

Publicador:

Relevância:

20.00% 20.00%

Publicador:

Resumo:

2000 Mathematics Subject Classification: Primary: 34L25; secondary: 47A40, 81Q10.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The aim of this paper is to present new results on H-infinity control synthesis for time-delay linear systems. We extend the use of a finite order LTI system, called comparison system to H-infinity analysis and design. Differently from what can be viewed as a common feature of other control design methods available in the literature to date, the one presented here treats time-delay systems control design with classical numeric routines based on Riccati equations arisen from H-infinity theory. The proposed algorithm is simple, efficient and easy to implement. Some examples illustrating state and output feedback design are solved and discussed in order to put in evidence the most relevant characteristic of the theoretical results. Moreover, a practical application involving a 3-DOF networked control system is presented.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This paper discusses the claim of the situatedness of research in both theoretical and applied linguistics and some of its implications and argues that it is linked to the performativity of all assertions, including scientific ones. More importantly, I argue that it is the regressive infinity of performativity that makes inevitable the passage from presumably 'dispassionate' research to militancy.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Context. The enigmatic object HD 45166 is a qWR star in a binary system with an orbital period of 1.596 day, and presents a rich emission-line spectrum in addition to absorption lines from the companion star (B7 V). As the system inclination is very small (i = 0.77 degrees +/- 0.09 degrees), HD 45166 is an ideal laboratory for wind-structure studies. Aims. The goal of the present paper is to determine the fundamental stellar and wind parameters of the qWR star. Methods. A radiative transfer model for the wind and photosphere of the qWR star was calculated using the non-LTE code CMFGEN. The wind asymmetry was also analyzed using a recently-developed version of CMFGEN to compute the emerging spectrum in two-dimensional geometry. The temporal-variance spectrum (TVS) was calculated to study the line-profile variations. Results. Abundances and stellar and wind parameters of the qWR star were obtained. The qWR star has an effective temperature of T(eff) = 50 000 +/- 2000 K, a luminosity of log(L/L(circle dot)) = 3.75 +/- 0.08, and a corresponding photospheric radius of R(phot) = 1.00 R(circle dot). The star is helium-rich (N(H)/N(He) = 2.0), while the CNO abundances are anomalous when compared either to solar values, to planetary nebulae, or to WR stars. The mass-loss rate is. M = 2.2 x 10(-7) M(circle dot) yr(-1), and the wind terminal velocity is v(infinity) = 425 km s(-1). The comparison between the observed line profiles and models computed under different latitude-dependent wind densities strongly suggests the presence of an oblate wind density enhancement, with a density contrast of at least 8: 1 from equator to pole. If a high velocity polar wind is present (similar to 1200 km s(-1)), the minimum density contrast is reduced to 4:1. Conclusions. The wind parameters determined are unusual when compared to O-type stars or to typical WR stars. While for WR stars v(infinity)/v(esc) > 1.5, in the case of HD 45166 it is much smaller (v(infinity)/v(esc) = 0.32). In addition, the efficiency of momentum transfer is eta = 0.74, which is at least 4 times smaller than in a typical WR. We find evidence for the presence of a wind compression zone, since the equatorial wind density is significantly higher than the polar wind. The TVS supports the presence of such a latitude-dependent wind and a variable absorption/scattering gas near the equator.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We analyze the finite-size corrections to entanglement in quantum critical systems. By using conformal symmetry and density functional theory, we discuss the structure of the finite-size contributions to a general measure of ground state entanglement, which are ruled by the central charge of the underlying conformal field theory. More generally, we show that all conformal towers formed by an infinite number of excited states (as the size of the system L -> infinity) exhibit a unique pattern of entanglement, which differ only at leading order (1/L)(2). In this case, entanglement is also shown to obey a universal structure, given by the anomalous dimensions of the primary operators of the theory. As an illustration, we discuss the behavior of pairwise entanglement for the eigenspectrum of the spin-1/2 XXZ chain with an arbitrary length L for both periodic and twisted boundary conditions.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A planar k-restricted structure is a simple graph whose blocks are planar and each has at most k vertices. Planar k-restricted structures are used by approximation algorithms for Maximum Weight Planar Subgraph, which motivates this work. The planar k-restricted ratio is the infimum, over simple planar graphs H, of the ratio of the number of edges in a maximum k-restricted structure subgraph of H to the number edges of H. We prove that, as k tends to infinity, the planar k-restricted ratio tends to 1/2. The same result holds for the weighted version. Our results are based on analyzing the analogous ratios for outerplanar and weighted outerplanar graphs. Here both ratios tend to 1 as k goes to infinity, and we provide good estimates of the rates of convergence, showing that they differ in the weighted from the unweighted case.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We prove that for any a-mixing stationary process the hitting time of any n-string A(n) converges, when suitably normalized, to an exponential law. We identify the normalization constant lambda(A(n)). A similar statement holds also for the return time. To establish this result we prove two other results of independent interest. First, we show a relation between the rescaled hitting time and the rescaled return time, generalizing a theorem of Haydn, Lacroix and Vaienti. Second, we show that for positive entropy systems, the probability of observing any n-string in n consecutive observations goes to zero as n goes to infinity. (c) 2010 Elsevier B.V. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This paper is a continuation and a complement of our previous work on isomorphic classification of some spaces of compact operators. We improve the main result concerning extensions of the classical isomorphic classification of the Banach spaces of continuous functions on ordinals. As an application, fixing an ordinal a and denoting by X(xi), omega(alpha) <= xi < omega(alpha+1), the Banach space of all X-valued continuous functions defined in the interval of ordinals [0,xi] and equipped with the supremum, we provide complete isomorphic classifications of some Banach spaces K(X(xi),Y(eta)) of compact operators from X(xi) to Y(eta), eta >= omega. It is relatively consistent with ZFC (Zermelo-Fraenkel set theory with the axiom of choice) that these results include the following cases: 1.X* contains no copy of c(0) and has the Mazur property, and Y = c(0)(J) for every set J. 2. X = c(0)(I) and Y = l(q)(J) for any infinite sets I and J and 1 <= q < infinity. 3. X = l(p)(I) and Y = l(q)(J) for any infinite sets I and J and 1 <= q < p < infinity.