Ricerc@Sapienza

This paper presents a novel space-time recursive least-squares adaptive algorithm, which performs filter coefficients updates in space and postponed filtering in time. The algorithm is used for intersymbol interference suppression in optical camera communications, which is a subgroup of visible light communication systems. Optical camera communications uses image sensor receivers, as those available in smartphones, tablets, and laptops, to detect changes in light intensity in order to allow data transmission.

In indoor environments, visible light communications paradigm is emerging as a viable promising solution complementary to well-known radio frequency technology. At the same time, the information about user's location is useful for accessing the medium via space-division multiplexing, handling over or providing access to location-based contents. In this paper, we present two localization mechanisms based on the wavelength domain by assuming that each anchor point uses a spectrally dedicated signature for the user to readily identify it.

We experimentally and theoretically investigate complex temporal pulse reshaping that accompanies Kerr beam self-cleaning in multimode optical fibers. We also study the output beam shape dependence on initial conditions.

In this article a class AB single-ended power amplifier with 30-512 MHz frequency band and 100 W saturated output power has been designed and implemented using a GaN transistor. The measured compressed gain is 19 ± 1 dB, the average PAE is 61% and the return loss is always better than −7.5 dB.

Wearable technology is attracting most attention in healthcare for the acquisition of physiological signals. We propose a stand-alone wearable surface ElectroMyoGraphy (sEMG) system for monitoring the muscle activity in real time. With respect to other wearable sEMG devices, the proposed system includes circuits for detecting the muscle activation potentials and it embeds the complete real-time data processing, without using any external device. The system is optimized with respect to power consumption, with a measured battery life that allows for monitoring the activity during the day.

The classical problem represented by a planar thin conductive shield in the presence of vertical dipole field sources (electric or magnetic) is solved analytically in the time domain via the Cagniard-de Hoop technique. Comparisons with numerical solutions carried out by means of efficient integration algorithms are provided and discussed.

In this paper we present two resource allocations techniques in a visible light communication network with overlapping coverage areas due to the use of access points. Particularly, the first approach exploits the rate maximization criteria, and then aims at maximizing the network rate under constraints on minimum and maximum rates, while the other procedure focuses on achieving fairness in the rate of each user accessing the network. The proposed system relays on optical code division multiple access mechanism, and resource allocation is intended in terms of codes assigned to a given user.

The characterization of ancient and modern alizarin-based lakes is a largely studied topic in the literature. Analytical data on contemporary alizarin-based lakes, however, are still poor, though of primary importance, since these lakes might be indeed present in contemporary and fake paintings as well as in retouchings. In this work we systematically investigate the chemical composition and the optical features of fifteen alizarin-based lakes, by a multi-analytical technique approach combining spectroscopic methods (i.e.

Here, we present a new scheme of analysis combining micro-energy dispersive X-ray fluorescence spectrometry (μ-XRF) with a multivariate approach that allows to establish the inter-correlation of multiple elements and their elemental map in plants. The main advantage of this procedure is that XRF spectral profiles can be analysed directly, by means of principal component analysis (PCA), allowing a quick interpretation of the results.

NiTi shape memory alloy (SMA) are widely applied in many industrial domains, such as biomedical, aerospace, automotive and power plants, due to its outstanding functionality including superelasticity (SE) and shape memory effect (SME). The machining process of this material is challenging with a lot of barriers. Accordingly, joining techniques can be an alternative approach to design the shape memory components with more flexibility. Among all methods, laser welding process is a reliable and economical technique for joining of NiTi alloys.