A Study on Frequency Response Functions in Pavement Engineering

Mechanical impedance (MI) defines the ability of a system to vibrate as a consequence of force application. In the recent years, the correlation of this parameter with tire-road noise and other characteristics has gained certain attention. Nevertheless, the information about this topic is still insufficient. Usually, the force is set through an impulse hammer as a master and the acceleration is measured through an accelerometer as a response in order to measure the corresponding Frequency Response Function (FRF). The objectives of the study presented in this paper are i) to analyse the differences between the axial mechanical impedance (complex ratio of force and velocity referred to the same point, named driving-point impedance) and the non-axial mechanical impedance (complex ratio of the force at the point i and velocity at the point j, named transfer impedance); ii) to analyse the effect of adding crumb rubber (2% by mixture weight) and of the percentage of bitumen on the mechanical impedance for the bituminous samples. Therefore, laboratory tests on asphalt concrete specimens have been performed, using an instrumentation system composed of i) an impact hammer reporting the impact force value; ii) an impedance head measuring the direct impact force and the direct acceleration at the hitting point location; iii) a piezoelectric accelerometer measuring the transfer acceleration at a certain distance from the hitting point location. Results demonstrate that the ratio between the repeatability and the average is quite constant, while for heights higher than 10 cm, also MI tends to be independent on the height. A number of recommendations have been made based on the results of the present research

Acoustical characterization of low-noise prototype asphalt concretes for electric vehicles

Euronoise 2021 (e-Congress), MADERE, PORTUGAL, 25-/10/2021 - 27/10/2021The paper deals with the acoustical characterization of low-noise asphalt concretes developed for noise reduction in urban areas within the LIFE E-VIA project (LIFE18 ENV/IT/000201). With the perspective of an increasing number of electric vehicles (EVs) in urban area, the asphalt concrete mixes have been optimized considering Life Cycle Cost with respect to actual best practices. Two very thin asphalt concretes (VTAC) of 6 mm maximum aggregate size have been implemented on a reference test track in France. Both are based on the same formulation, but one mix contains 1.9% crumb rubber by weight. The noise performance of these prototype test sections has been evaluated by means of close-proximity (CPX) tests and controlled pass-by (CPB) noise measurements for two EV models. CPX results have shown a noise reduction of about 2.5 dB(A) by comparison with a reference dense asphalt concrete 0/10, while an average pass-by noise reduction of about 4 dB(A) has been observed for the sample of EVs tested

Acoustical characterization of low-noise prototype asphalt concretes for electric vehicles

Euronoise 2021 (e-Congress), MADERE, PORTUGAL, 25-/10/2021 - 27/10/2021The paper deals with the acoustical characterization of low-noise asphalt concretes developed for noise reduction in urban areas within the LIFE E-VIA project (LIFE18 ENV/IT/000201). With the perspective of an increasing number of electric vehicles (EVs) in urban area, the asphalt concrete mixes have been optimized considering Life Cycle Cost with respect to actual best practices. Two very thin asphalt concretes (VTAC) of 6 mm maximum aggregate size have been implemented on a reference test track in France. Both are based on the same formulation, but one mix contains 1.9% crumb rubber by weight. The noise performance of these prototype test sections has been evaluated by means of close-proximity (CPX) tests and controlled pass-by (CPB) noise measurements for two EV models. CPX results have shown a noise reduction of about 2.5 dB(A) by comparison with a reference dense asphalt concrete 0/10, while an average pass-by noise reduction of about 4 dB(A) has been observed for the sample of EVs tested

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field