Search results for " propagation"
showing 10 items of 488 documents
Generalised bisection method for optimum ultrasonic ray tracing and focusing in multi-layered structures
2021
Ultrasonic testing has been used for many decades, proving itself very efficient for detecting defects in many industrial sectors. The desire to apply ultrasonic testing to geometrically complex structures, and to anisotropic, inhomogeneous materials, together with the advent of more powerful electronics and software, is constantly pushing the applicability of ultrasonic waves to their limits. General ray tracing models, suitable for calculating the proper incident angle of single element probes and the proper time delay of phased array, are currently required. They can support the development of new imaging techniques, as Full Matrix Capture and Total Focusing Method, and the execution of …
Stable and simple quantitative phase-contrast imaging by Fresnel biprism
2018
Digital holographic (DH) microscopy has grown into a powerful nondestructive technique for the real-time study of living cells including dynamic membrane changes and cell fluctuations in nanometer and sub-nanometer scales. The conventional DH microscopy configurations require a separately generated coherent reference wave that results in a low phase stability and a necessity to precisely adjust the intensity ratio between two overlapping beams. In this work, we present a compact, simple, and very stable common-path DH microscope, employing a self-referencing configuration. The microscope is implemented by a diode laser as the source and a Fresnel biprism for splitting and recombining the be…
Observation of classically 'forbidden' electromagnetic wave propagation and implications for neutrino detection.
2018
Ongoing experimental efforts in Antarctica seek to detect ultra-high energy neutrinos by measurement of radio-frequency (RF) Askaryan radiation generated by the collision of a neutrino with an ice molecule. An array of RF antennas, deployed either in-ice or in-air, is used to infer the properties of the neutrino. To evaluate their experimental sensitivity, such experiments require a refractive index model for ray tracing radio-wave trajectories from a putative in-ice neutrino interaction point to the receiving antennas; this gives the degree of signal absorption or ray bending from source to receiver. The gradient in the density profile over the upper 200 meters of Antarctic ice, coupled wi…
Effects of plant density and cutting-type on rooting and growth of an extensive green roof of Sedum sediforme (Jacq.) Pau in a Mediterranean environm…
2020
Abstract Species of the Sedum genus are a popular choice for green roofs as they thrive in shallow growth layers and are resilient to extreme environmental conditions; they are also easy to propagate from seed, plantlings or plant parts. The use of rooted cuttings is most widespread due to good rates of establishment. In the interest of cost reduction, the direct spreading of Sedum cuttings over the roof area, especially over large areas, has attracted attention in recent years. Considering the interest on the above method and the seeming lack of experimental data available, this study aims to further knowledge in this area. Experimental tests on direct spreading of unrooted cuttings of Sed…
Grafting affects yield and phenolic profile of Solanum melongena L. landraces
2016
Abstract The influence of grafting on agronomical and qualitative characteristics of four Sicilian eggplant landraces was investigated. Grafted and ungrafted plants were compared in the open field in the northern coast of Sicily. Solanum torvum seedlings were used as rootstock. Regardless of genotypes tested, grafting significantly increased total fruit production, marketable production, and number of marketable fruits, but did not affect weight of marketable fruits and waste production. Landrace 2 (Sciacca), with black epidermal tissue and pyriform fruit shape, when grafted onto S. torvum not only gave a higher yield performance than ungrafted plants, but also showed a higher phenolic anti…
An eco-physiological and biotechnological approach to conservation of the world-wide rare and endangered aquatic liverwort Riella helicophylla (Bory …
2016
AbstractThe rare aquatic liverwortRiella helicophylla(Bory et Mont.) Mont., inhabitant of temporary shallow ponds around the Mediterranean basin, is considered threatened throughout its distribution range. In addition, little is known of its biology and ecology or of its role in such an important ecosystem where environmental conditions vary yearly in unpredictable ways. In these variable habitats, due to the seasonal fluctuation of water levels, there is no guarantee of yearly spore input into the spore bank. Spore germination rate and the effects of different culture media in an axenic culture establishment, as well as propagation procedures ofR. helicophylla,were tested. New insights int…
Predicting the invasion of the acoustic niche: Potential distribution and call transmission efficiency of a newly introduced frog in Cuba
2021
8 pages; International audience; Leptodactylus fragilis is a recently introduced frog in Cuba, where it may impact local populations of amphibians in different ways. Here, we combined two methods to predict the invasion of the acoustic niche of Cuban amphibians by L. fragilis. We first use species distribution models to predict the spread and establishment of L. fragilis in Cuba. We then performed sound propagation experiments to evaluate the potential invasion of the acoustic niche in predicted suitable areas for the presence of L. fragilis. This species could have a successful establishment, spreading mainly in open areas, where its advertisement calls propagate efficiently, with low atte…
Thorough analysis of Raspberry Pi devices in outdoor/indoor communications in terms of QoS
2020
The proliferation of commercial low-cost Small Board Computers (SBC) devices have allowed the deployment of many Wireless Sensor Networks (WSN) focused on different applications, mainly based on monitoring issues. These networks are characterized by a set of these SBCs devices working in a collaborative way where each device is sensing, processing and later sending out the data to the sink. These devices are equipped with power supply, a processing unit and communications capabilities (in particular WiFi), making themselves very interesting to fit in many topologies. However, their performance in terms of communications basically depends on the environment and usually heuristic techniques a…
Towards Intelligent IoT Networks: Reinforcement Learning for Reliable Backscatter Communications
2019
Backscatter communication is becoming the focal point of research for low-powered Internet of things (IoT). However, the intelligence aspect of the backscattering devices is not well-defined. Since future IoT networks are going to be a formidable platform of intelligent sensing devices operating in a self-organizing manner, it is necessary to incorporate learning capabilities in backscatter devices. Motivated by this objective, this paper aims to employ reinforcement learning for improving the performance of backscatter networks. In particular, a multicluster backscatter communication model is developed for shortrange information sharing. This is followed by a power allocation algorithm usi…
Location-Aware MAC Scheduling in Industrial-Like Environment
2018
We consider an environment strongly affected by the presence of metallic objects, that can be considered representative of an indoor industrial environment with metal obstacles. This scenario is a very harsh environment where radio communication has notorious difficulties, as metallic objects create a strong blockage component and surfaces are highly reflective. In this environment, we investigate how to dynamically allocate MAC resources in time to static and mobile users based on context awareness extracted from a legacy WiFi positioning system. In order to address this problem, we integrate our WiFi ranging and positioning system in the WiSHFUL architecture and then define a hypothesis t…