This work presents a detailed review of the development of distributed acoustic sensors (DAS) and their newest scientific applications. It covers most areas of human activities, such as the engineering, material, and humanitarian sciences, geophysics, culture, biology, and applied mechanics. It also provides the theoretical basis for most well-known DAS techniques and unveils the features that characterize each particular group of applications. After providing a summary of research achievements, the paper develops an initial perspective of the future work and determines the most promising DAS technologies that should be improved.
Since the early 1970s it has been pointed out that many higher education students have a fairly large number of mistaken ideas on some Physics topics. Indeed, the term "misconceptions" was introduced for the first time in 1972. This theme is worthy of investigation in order to improve the students' outcomes in basic Physics courses and to tackle the issue of the growing number of dropouts. Consisting of three main stages closely connected with each other, our research aims at identifying, comparing and overcoming the most significant and widespread misconceptions shown by first-year university students enrolled for engineering, in relation to their basic knowledge of Physics, with specific reference to Mechanics, Thermodynamics and Electromagnetism. It is being developed by Politecnico di Milano [ITA] along with Doshisha University [JAP] and Bauman Moscow State Technical University [RUS], which offer Physics and Engineering courses, as well as with Università degli Studi di Trento [ITA], which provides pedagogic support. First of all, data about the above mentioned misconceptions were gathered by each technical institution through the use of an ad hoc test, which consisted of 12 multiple choice quizzes administered to about 750 students attending the 7 courses globally involved in the research. Hence, misconceptions related to the main macro-areas were further classified according to specific headings, i.e. kinematics, heat engine, electric field, among others. Secondly, the misconceptions expressed by the students attending the different universities involved in the research were compared. They appear to be broadly widespread among the freshmen, with Electromagnetism being the macro-area where the students' results are the worst. Throughout the third and final stage of our study, a trial video has been produced to enable students to overcome some significant misconceptions.
Runways monitoring in civil airports is typically performed by enhanced radar surveillance systems operating in the so-called Precision Runway Monitor (PRM) system that provides position of airplanes and information on their trajectories. In this paper, we propose an additional measurement system that can be used jointly with the conventional PRM approach to monitor aircrafts position on land without using the radar approach or requiring visual inspection of the lanes. We propose a system made of ground-based distributed optical fiber sensors (OFSs), to be placed below the concrete floor of the take-off and landing lanes as well as along the different roads and intersections within the airport. OFSs will be read by a phase-sensitive OTDR (Φ-OTDR) driven by low-noise narrow-linewidth 1.55 mm laser. The laser field is used to inject the optical fiber with a pulsed signal and to read the phase shifts arising from vibrations and pressure waves produced by aircrafts moving, or even still with engines turned on, along the lanes. An absolute localization of different planes, with a few meters resolution and accuracy across the whole airport, would be possible after installing OFSs and adjustment of the detection system. The proposed ground monitoring system, in addition to the ones currently available, offers information redundancy at a promising low-cost and a backup aircraft-positioning tool in case of failure or malfunctioning of the existing video-or radio-based systems. Furthermore, the proposed system is inherently immune to e.m. interference and also to intentional disturbance or intrusion. Design of the laser source and of the Φ-OTDR measurement system is underway with the aim of precise and continuous monitoring of the on-land position and movement of different aircrafts or vehicles within the airport
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.