Analysis and Automatic Classification of the Soundscape of a Natural Park Close to the Airport of Barcelona during the 2021 Lockdown Period

The noise caused by airports and its impact on human health, together with train, road traffic, leisure, and wind nose has been widely analyzed, even in the reports published in 2019 by the WHO. Noise effect has also been studied in the literature on other species, such as birds and amphibians. In this work, we focus on a natural environment of special singularity due to its location: the natural space of the Delta del Llobregat, next to the city of Barcelona. The Delta del Llobregat is placed in an area close to the Port of Barcelona, and directly on the route of the planes taking off from Barcelona airport. In this paper, we present a first analysis of the typology of the sounds found in the natural environment of the Delta del Llobregat after conducting a simultaneous recording campaign at three separate spots of biological interest, determined by the park’s curators. We identify the interfering sounds, as well as the amount of wildlife sounds in relation to the noises caused by the airport activity. The recordings and posterior analysis were made on 5 March 2021, when airport activity was still greatly diminished by the mobility restrictions. In addition, we apply machine learning techniques to classify the acoustic events produced by both airport activity and wildlife, aiming to build an automatic system that would allow us to gather labelled data in future works.

The Special Chao and Singularity in a Simple Traffic Model

We have proposed a modified traffic model in which a single car moves through a sequence of traffic lights controlled by a step function instead of a sine function. We have found the complex behaviors in this simple traffic model and given three kinds of bifurcation diagrams. We have found that in this model there are chaotic and complex periodic motions, as well as special singularity. In this paper, we will introduce two special kinds chao which is different from general chao and the singularities of the simple traffic model. There are three different kinds of singularity which are single singularity, unsymmetic and symmetic double singularity.

Dimensional Designing Study on a Novel 3-RPS Parallel Machine

Analysis on the singularity of the 3-RPS parallel machine which probably occurs in the engineering application is presented. The influence of the singular configurations in the workspace of the parallel machine is interpreted. To improve the orientation capacity of the moving platform, a novel complex spherical joint is designed, however a special singularity namely coaxial singularity is resulted in. By optimizing the dimension parameters and designing a special moving platform, the singularity can be averted in the wanted workspace, and the nutation angle of the parallel machine can be enlarged to ±45 degree.

LARGE VISCOUS SOLUTIONS FOR SMALL DATA IN SYSTEMS OF CONSERVATION LAWS THAT CHANGE TYPE

We study a quadratic system of conservation laws with an elliptic region. The second order terms in the fluxes correspond to type IV in Schaeffer and Shearer classification. There exists a special singularity for the EDOs associated to traveling waves for shocks. In our case, this singularity lies on the elliptic boundary. We prove that high amplitude Riemann solutions arise from Riemann data with arbitrarily small amplitude in the hyperbolic region near the special singularity. For such Riemann data there is no small amplitude solution. This behavior is related to the bifurcation of one of the codimension-3 nilpotent singularities of planar ODEs studied by Dumortier, Roussarie and Sotomaior.