1,061 research outputs found

    Inverse turbulent cascades and conformally invariant curves

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    We offer a new example of conformal invariance far from equilibrium -- the inverse cascade of Surface Quasi-Geostrophic (SQG) turbulence. We show that temperature isolines are statistically equivalent to curves that can be mapped into a one-dimensional Brownian walk (called Schramm-Loewner Evolution or SLEÎș_\kappa). The diffusivity is close to Îș=4\kappa=4, that is iso-temperature curves belong to the same universality class as domain walls in the O(2) spin model. Several statistics of temperature clusters and isolines are measured and shown to be consistent with the theoretical expectations for such a spin system at criticality. We also show that the direct cascade in two-dimensional Navier-Stokes turbulence is not conformal invariant. The emerging picture is that conformal invariance may be expected for inverse turbulent cascades of strongly interacting systems.Comment: 4 pages, 6 figure

    Two-dimensional elastic turbulence

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    We investigate the effect of polymer additives on a two-dimensional Kolmogorov flow at very low Reynolds numbers by direct numerical simulations of the Oldroyd-B viscoelastic model. We find that above the elastic instability threshold the flow develops the elastic turbulence regime recently observed in experiments. We observe that both the turbulent drag and the Lyapunov exponent increase with Weissenberg, indicating the presence of a disordered, turbulent-like mixing flow. The energy spectrum develops a power-law scaling range with an exponent close to the experimental and theoretical expectations

    Market Innovation, Rational Housing Supply and Urban Quality at the Neighbourhood Scale

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    Innovation of product, process and markets are the three categories to assess the improvement of a sector. This document is aimed to provide a review of papers about innovation in housing market and analyses solutions adopted by the international market in terms of definition of attributes of housing products. Enlightening aspects linked to quality attributes of housing products and it has been tried to read a common scheme in any study analysed to provide solutions to set innovation hints to enhance market innovation in the sector. The idea of choice, user and buyer categories definition, assessment and rating system is the backbone of the paper, as the parallelism between marketing of industrial goods and services and built environment objects. Quality of the neighbourhood and the idea of an ex-post assessment is the theme behind the last case presented, based on a research made by ABC Department of Politecnico di Milano in a neighbourhood in Milano, aimed to assess its quality

    A retrospective study of cryptorchidectomy in horses: Diagnosis, treatment, outcome and complications in 70 cases

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    The aim of the study was to investigate the breed predisposition and the diagnostic and surgical management of horses referred for cryptorchidism. The breed, localization of retained testis, diagnosis, type of surgical treatment and complications were analyzed. Seventy horses were included in the study; the Western Riding horse breeds were the most affected (Quarter Horse 34/70, 48.5%; Appaloosa 9/70, 12.8%). In unilateral cryptorchids (65/70, 92.8%) the most common location for a retained testis was the left abdomen (28/65, 43%), while in bilateral cryptorchids (5/70, 7.1%), bilateral abdominal retention was the most frequent (3/5, 6%). Information about testis localization was achieved through transabdominal ultrasound (30/49 cases, 61.2%), through per rectum palpation (21/49 cases, 42.9%) and through inguinal palpation (14/49 cases, 28.9%). Cryptorchidectomy was achieved with standing laparoscopy (44/70 cases, 62.8%), or with open inguinal orchiectomy in general anesthesia (26/70 cases, 37.2%). Complications during laparoscopy were spleen puncture (1/44, 2.2%), a self-limiting bleeding from the spermatic cord (10/44 cases, 22.7%), hyperthermia (3/44 cases, 6.8%), and emphysema (15/44, 34%). During inguinal open cryptorchidectomy difficulties with identifying the inguinal testis during surgery (8/26 cases, 30.8%) and a moderate and self-limiting swelling of the inguinal region after surgery (17/26, 65.4%) were observed. For orchiectomy, a standing laparoscopy was confirmed as the preferred procedure for an abdominally retained testis with almost no complications

    Statistical conservation laws in turbulent transport

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    We address the statistical theory of fields that are transported by a turbulent velocity field, both in forced and in unforced (decaying) experiments. We propose that with very few provisos on the transporting velocity field, correlation functions of the transported field in the forced case are dominated by statistically preserved structures. In decaying experiments (without forcing the transported fields) we identify infinitely many statistical constants of the motion, which are obtained by projecting the decaying correlation functions on the statistically preserved functions. We exemplify these ideas and provide numerical evidence using a simple model of turbulent transport. This example is chosen for its lack of Lagrangian structure, to stress the generality of the ideas

    Site-selection on the basis of territorial analysis methods

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    The object of research is the site-selection process for the rental housing construction. This form of real estate is becoming more widespread in the west, while in Russia it's development is currently on initial stage. The article proposes the site-selection solution on the basis of existing methods of territorial analysis, calculation of employment shares, location quotients, Hirschmann-Herfindahl index and Kano model application, as well as application examples of the obtained databases in the conditions of a narrowly formulated problem. The research results are the mechanisms for solving three types of problems depending on the nature of the initial data according to correspondence between the properties of the object under construction and the urban territories

    Finitely generated free Heyting algebras via Birkhoff duality and coalgebra

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    Algebras axiomatized entirely by rank 1 axioms are algebras for a functor and thus the free algebras can be obtained by a direct limit process. Dually, the final coalgebras can be obtained by an inverse limit process. In order to explore the limits of this method we look at Heyting algebras which have mixed rank 0-1 axiomatizations. We will see that Heyting algebras are special in that they are almost rank 1 axiomatized and can be handled by a slight variant of the rank 1 coalgebraic methods

    Advection of a passive scalar field by turbulent compressible fluid: renormalization group analysis near d=4d = 4

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    The field theoretic renormalization group (RG) and the operator product expansion (OPE) are applied to the model of a density field advected by a random turbulent velocity field. The latter is governed by the stochastic Navier-Stokes equation for a compressible fluid. The model is considered near the special space dimension d=4d = 4. It is shown that various correlation functions of the scalar field exhibit anomalous scaling behaviour in the inertial-convective range. The scaling properties in the RG+OPE approach are related to fixed points of the renormalization group equations. In comparison with physically interesting case d=3d = 3, at d=4d = 4 additional Green function has divergences which affect the existence and stability of fixed points. From calculations it follows that a new regime arises there and then by continuity moves into d=3d = 3. The corresponding anomalous exponents are identified with scaling dimensions of certain composite fields and can be systematically calculated as series in yy (the exponent, connected with random force) and Ï”=4−d\epsilon=4-d. All calculations are performed in the leading one-loop approximation.Comment: 11pages, 6 figures, LATEX2e. arXiv admin note: substantial text overlap with arXiv:1611.00327; text overlap with arXiv:1611.0130

    Strong Universality in Forced and Decaying Turbulence

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    The weak version of universality in turbulence refers to the independence of the scaling exponents of the nnth order strcuture functions from the statistics of the forcing. The strong version includes universality of the coefficients of the structure functions in the isotropic sector, once normalized by the mean energy flux. We demonstrate that shell models of turbulence exhibit strong universality for both forced and decaying turbulence. The exponents {\em and} the normalized coefficients are time independent in decaying turbulence, forcing independent in forced turbulence, and equal for decaying and forced turbulence. We conjecture that this is also the case for Navier-Stokes turbulence.Comment: RevTex 4, 10 pages, 5 Figures (included), 1 Table; PRE, submitte
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