Microscopic entropy of the three-dimensional rotating black hole of BHT massive gravity

Asymptotically AdS rotating black holes for the Bergshoeff-Hohm-Townsend (BHT) massive gravity theory in three dimensions are considered. In the special case when the theory admits a unique maximally symmetric solution, apart from the mass and the angular momentum, the black hole is described by an independent "gravitational hair" parameter, which provides a negative lower bound for the mass. This bound is saturated at the extremal case and, since the temperature and the semiclassical entropy vanish, it is naturally regarded as the ground state. The absence of a global charge associated with the gravitational hair parameter reflects through the first law of thermodynamics in the fact that the variation of this parameter can be consistently reabsorbed by a shift of the global charges, giving further support to consider the extremal case as the ground state. The rotating black hole fits within relaxed asymptotic conditions as compared with the ones of Brown and Henneaux, such that they are invariant under the standard asymptotic symmetries spanned by two copies of the Virasoro generators, and the algebra of the conserved charges acquires a central extension. Then it is shown that Strominger's holographic computation for general relativity can also be extended to the BHT theory; i.e., assuming that the quantum theory could be consistently described by a dual conformal field theory at the boundary, the black hole entropy can be microscopically computed from the asymptotic growth of the number of states according to Cardy's formula, in exact agreement with the semiclassical result.Comment: 10 pages, no figure

Interpreting Deep Visual Representations via Network Dissection

The success of recent deep convolutional neural networks (CNNs) depends on learning hidden representations that can summarize the important factors of variation behind the data. However, CNNs often criticized as being black boxes that lack interpretability, since they have millions of unexplained model parameters. In this work, we describe Network Dissection, a method that interprets networks by providing labels for the units of their deep visual representations. The proposed method quantifies the interpretability of CNN representations by evaluating the alignment between individual hidden units and a set of visual semantic concepts. By identifying the best alignments, units are given human interpretable labels across a range of objects, parts, scenes, textures, materials, and colors. The method reveals that deep representations are more transparent and interpretable than expected: we find that representations are significantly more interpretable than they would be under a random equivalently powerful basis. We apply the method to interpret and compare the latent representations of various network architectures trained to solve different supervised and self-supervised training tasks. We then examine factors affecting the network interpretability such as the number of the training iterations, regularizations, different initializations, and the network depth and width. Finally we show that the interpreted units can be used to provide explicit explanations of a prediction given by a CNN for an image. Our results highlight that interpretability is an important property of deep neural networks that provides new insights into their hierarchical structure.Comment: *B. Zhou and D. Bau contributed equally to this work. 15 pages, 27 figure

Otra forma de abordar un mundo tan complejo como es la danza

Obra ressenyada: D. AMADO, La danza entendida desde una perspectiva psicológica. Sevilla, Wanceulen, 201

Subjective listening experiments for annoyance investigation

Noise limits and guidelines that consider only the sound pressure level or the loudness of noises are not efficient in protecting people from all the adverse effects of noise. Other physical characteristics, e.g., tonality, modulation, and frequency content, should also be considered, especially when the noise level is low and it cannot cause hearing risk, but might lead to annoyance and disturbance. Annoying noises have an impact on health and well-being, but this impact and its relationship with the physical properties have not been sufficiently studied. Subjective annoyance caused by noises like those we experience in living spaces and offices should be further investigated via psychoacoustic laboratory experiments. The primary aim of this work was to develop systematic, effective, and reliable methodology to perform this type of psychoacoustic tests. The secondary aim was to investigate the objective metrics that best predict subjective annoyance in four typical noise conditions: ventilation noise in office spaces, traffic noise in homes, neighbors’ noise in homes, and noises with tonal components in homes. The main result was the development of the methodology, which in turn enabled us to define our own standards and guidelines. Furthermore, we identified the objective metrics that best correlated with subjective annoyance in each one of the four studied noise situations. In offices, five metrics predicted subjective ratings reasonably well. Noise with sound energy at higher frequencies was less tolerated. Noise with a slope of -7 dB per octave band increment resulted in the highest satisfaction. In dwellings, related to neighbors’ living sounds, four metrics of airborne sound insulation performed well to predict annoyance. We demonstrated that 50–80 Hz bands should not be included in the objective rating. In dwellings, related to five types of traffic noise transmitted through façade elements, one metric Rw+C50–3150 performed significantly better than the others. The last experiment proved that tonality is not properly considered in current standards and noise guidelines. The performed psychoacoustic research demonstrated that other physical properties than the sound pressure level should be considered when assessing noise annoyance, and it provided evidence to the objective metrics that would make noise guidelines more efficient with respect to health protection.Subjektiivisia kuuntelukokeita häiritsevyyden tutkimiseksi Melurajat ja ohjeet suojelevat ihmisiä melun haitallisista vaikutuksista, mutta ne ottavat enimmäkseen huomioon vain melun äänenpainetason tai voimakkuuden. Muut fyysiset ominaisuudet, kuten kapeakaistaisuus, modulaatio ja taajuussisältö, joilla on selvä vaikutus subjektiiviseen kokemukseen ja häiritsevyyteen, jätetään usein huomiomatta. Ärsyttävät äänet saattavat noudattaa lakia niiden kielteisistä vaikutuksista huolimatta, koska niiden äänenpainetaso ei ylitä yhtään melurajaa. Asuintilojen ja toimistojen melun aiheuttamaa subjektiivista ärsytystä tulisi tutkia tarkemmin psykoakustisten laboratoriokokeiden avulla. Työn ensisijaisena tavoitteena oli kehittää järjestelmällinen, tehokas ja luotettava menetelmä tämän tyyppisten psykoakustisten testien suorittamiseksi. Lisäksi selvitettiin, mitä muita objektiivisia mittareita, kuin äänenpainetaso tai äänenvoimakkuus, ennustavat parasta subjektiivista ärsytystä ja häiritsevyyttä. Työssä tutkittiin neljää tyypillistä meluolosuhdetta: toimistotilojen ilmanvaihdonääniä, kaupungin liikenteen melua kodeissa, naapurin melua kodeissa, ja kapeakaistaisia komponentteja sisältävää melua. Päätuloksena oli menetelmän kehittäminen, joka mahdollisti omien standardien ja toimintaohjeiden määrittämisen. Lisäksi tunnistettiin objektiiviset mittarit, jotka korreloivat paremmin subjektiivisen häiritsevyyden kanssa kussakin neljästä tutkitusta melutilanteesta. Toimistoissa viisi mittaria ennusti kohtuullisen hyvin subjektiivisia luokituksia. Kohinaa, joka kuului korkeammilla taajuuksilla toimivalla äänenergialla, siedettiin vähemmän. Asunnoissa, kun asumisääniä syntyy naapurin asunnossa, neljä ilmaääneneristysmittaria toimi hyvin ennustamaan asukkaiden subjektiivista ärsytystä. Osoitettiin, että 50–80 Hz: n kaistoja ei pitäisi sisällyttää objektiiviseen luokitukseen. Myös asunnoissa, liittyen viitteen eri liikennemeluun kantautumassa sisätilaan julkisivuelementtien kautta, yksi metrinen Rw+C50–3150 toimi huomattavasti paremmin kuin muut. Viimeinen koe osoitti, että tonaalisuutta ei oteta asianmukaisesti huomioon nykyisissä standardeissa ja meluohjeissa. Tämä tutkimus osoitti, että oikein suoritetut psykoakustiset kokeet tarjoavat laadullista ja määrällistä tietoa subjektiivisesta häiritsevyydestä, ja että näiden tietojen perusteella voidaan määrittää objektiiviset mittarit, jotka tekisivät ohjearvoista tehokkaampia melun haitallisilta vaikutuksilta suojauduttaessa

Heat and moisture insulation by means of air curtains: application to refrigerated chambers

The present study is devoted to the determination of the efficiency of air curtain units (ACUs) applied to heat and moisture insulation of refrigerated chambers. A detailed study of the fluid dynamics and heat and mass transfer of the ACU in the refrigerated space and the external ambient is carried out by means of large eddy simulations (LES). The heat and moisture entrainment through the doorway and their transport inside the inner space are fully described. Three different configurations are studied: non-recirculating, recirculating and twin-jet air curtains. The condensation produced in the cool walls of the refrigerated space is evaluated considering the warm humid air from the ambient which penetrates inside the chamber through the doorway. The influence of both the discharge velocities and the discharge angles on the sealing capabilities of the three different tested ACU configurations is determined.Peer ReviewedPostprint (author's final draft

A new statistical model for subgrid dispersion in large eddy simulations of particle-laden flows

This article is published under a CC BY licence. The Version of Record is available online at: http.//dx.doi.org/10.1088/1742-6596/745/3/032115Dispersed multiphase turbulent flows are present in many industrial and commercial applications like internal combustion engines, turbofans, dispersion of contaminants, steam turbines, etc. Therefore, there is a clear interest in the development of models and numerical tools capable of performing detailed and reliable simulations about these kind of flows. Large Eddy Simulations offer good accuracy and reliable results together with reasonable computational requirements, making it a really interesting method to develop numerical tools for particle-laden turbulent flows. Nonetheless, in multiphase dispersed flows additional difficulties arises in LES, since the effect of the unresolved scales of the continuous phase over the dispersed phase is lost due to the filtering procedure. In order to solve this issue a model able to reconstruct the subgrid velocity seen by the particles is required. In this work a new model for the reconstruction of the subgrid scale effects over the dispersed phase is presented and assessed. This innovative methodology is based in the reconstruction of statistics via Probability Density Functions (PDFs).Peer ReviewedPostprint (published version