Classical Physics

Abstract Electric and Hybrid Electric vehicles (EV and HEV) seem to be the future of transport in smart cities and the key for the total reduction of noise disturbance and pollution in urban areas. However, several problems have to be solved to guarantee the safety of these types of vehicle. Up to now, the use of HEV has shown the dangers of a “quiet” transport system in urban environments; in fact, it has been estimated that an HEV is twice as likely to be involved in a pedestrian crash as would be an internal combustion engine (ICE) vehicle in the same situation. With the aim of improving their safety, different kinds of warning sounds are being designed to increase the detectability of EV and HEV without themselves becoming new annoying sound sources. The sound directivity, frequency of emission and intensity of warning sound systems will guarantee their efficiency and limited noise impact. Several research works bring to the fore a significant variation of the pedestrian response time to different acoustic stimuli. However, it is necessary to examine the suitability of these warning sounds according to the urban environments in which they are going to be emitted. Distinct areas inside the city have different soundscapes whose spectral content can vary significantly, masking some of the sounds suggested as an alert. This paper analyses in detail the main characteristics of several warning sounds proposed by the industry, conducting a comparative study of the different design trends. A total of 131 sighted listeners were exposed to a virtual road-crossing test. The behaviour and appropriateness of warning sounds are analysed depending on the urban environment. For this purpose, three clearly different soundscapes have been selected: stopped vehicles at a traffic light, a pedestrian shopping area and the vicinity of a playground. The results highlight the wide variability in pedestrian reaction time for the different warning sounds used. Some signals considerably improve the detectability of the vehicle, providing results even above the ICE vehicle ones. However, other warning sounds do not decrease the reaction time with respect to the EV. In addition, a clear dependence is observed between the detectability and the soundscape involved, changing the results for the same warning sound depending on the acoustic environment.

This work shows the experimental data of excess properties at several temperatures and the vapor–liquid equilibria (VLE) obtained for four binary systems of alkyl methanoates (methyl to butyl) with decane, all measured at constant pressure of 101.32kPa. The isobaric VLE data were thermodynamically consistent according to the Fredenslund test and did not present an azeotrope. The experimental data of HmE

ABSTRACT The sound of a solid body electric guitar comes from the loudspeaker transducing into sound the string velocity. Because of mechanical string-structure coupling, the string vibration, and therefore the sound, substantially depends on the lutherie parameters. This study focuses on the comparison between ebony-fingerboard and rosewood-fingerboard guitars: is a change in the fingerboard wood perceived by the guitar players? In order to test the hypothesis that it is actually perceived, a psychological investigation is carried out. Two experimental methods are used: a free sorting task with recorded stimuli from the guitars (listening test) and a free verbalisation task where the guitarists play the guitars. In the listening test, the guitarists perceive differences between guitars, but the resulting clusters do not show an ebony/rosewood dichotomy. A linguistic analysis of the verbalisations exhibits psychological descriptors that are relevant for the discrimination of the wood of the fingerboard: PRECISION (referring to how each note stands out from others), and to a lesser extent ATTACK (referring to the guitar's response to musician's gesture) and BALANCE (referring to the frequency content). This study is part of a broader project aiming at establishing an explicite relation between mechanics, perception, and lutherie. A physical interpretation of the psychologically-relevant descriptors is eventually proposed in order to use them as hypotheses in a further hypothetico-deductive approach starting from physics and using psychophysical methods.

In this paper, we considered the study of Friedmann–Robertson–Walker (FRW) model in the framework of [Formula: see text] gravity, an extension of symmetric teleparallel gravity, recently defined by Xu et al. [[Formula: see text] gravity, Eur. Phys. J. C 79 (2019) 708]. The nonlinear model [Formula: see text], where [Formula: see text] and [Formula: see text] are constants, is taken into account. The equation of state of perfect fluid is assumed and 31 points of Hubble data are used to constrain the value of model parameter. To explore the evolution of the universe, the numerical solutions of cosmological implications, such as Hubble parameter, deceleration parameter, apparent magnitude and luminosity distance, are determined and the energy conditions are examined. The theoretical results of Hubble parameter are compared with [Formula: see text]CDM model. Further, 57 Supernova data (42 from Supernova cosmology project and 15 from Calán/Tolono supernova survey) are also used to have c...

Photoacoustic spectroscopy (PAS) is widely used for diverse applications in different areas. These include studies in material, environmental, and life sciences. In the present work the study of pigments from pottery surfaces and volumes of Mexican (Aztec) and Poblana cultures that were developed in central Mexico from 1325 to 1521 and 1521 to 1800, respectively, is reported. The optical absorption spectra from each archeological sample was obtained using PAS. The superficial spectra were also compared with standard color pigments and archeological registers. Complementary energy dispersive spectroscopy (EDS) analysis of these archeological potteries gave us their elemental composition which agreed with other studies about their composition and technology of the pottery manufacturing.