Alessandro Bozzoli

Characterization of a geometrical wireless signal propagation model for indoor ranging techniques

Wireless positioning systems are interesting for a variety of indoor applications such as security, home automation and ambient assisted living (AAL) services. Unfortunately, the accuracy of distance measurement techniques based on short-range wireless communication transceivers is generally quite poor, mainly because of multipath propagation phenomena. In this paper an analytical model describing the effect of multipath propagation on received signal power is presented. In particular, both the case of pure sine wave indoor propagation and the more involved scenario based on IEEE 802.15.4 Offset Quadrature Phase-Shift keying (OQPSK) signals are analyzed. Several experimental results collected in an anechoic chamber confirm a reasonably good agreement with the proposed model, thus paving the way to new strategies to improve indoor ranging accuracy based on wireless techniques.

A Novel RC-FDTD Algorithm for the Drude Dispersion Analysis

One of the main techniques for the Finite-Difierence Time-Domain (FDTD) analysis of dispersive media is the Recursive Convolution (RC) method. The idea here proposed for calculating the updating FDTD equation is based on the Laplace transform and is applied to the Drude dispersion case. A novel RC-FDTD algorithm, that we call modifled, is then deduced. We test our algorithm by simulating gold and silver nanospheres exposed to an optical plane wave and by comparing the results with the analytical solution. The modifled algorithm guarantees a better overall accuracy of the solution, in particular at the plasmonic resonance frequencies.

Development of a pellet boiler with Stirling engine for m-CHP domestic application

A new sustainable technology has been designed by Fondazione Bruno Kessler through its unit Renewable Energies and Environmental Technologies. This technology is realized integrating in a single system (1) a Stirling engine (mRT-1K) from a pre-engineering design of Allan J. Organ; (2) a micro-heat exchanger technology, to reduce the net transfer unit deficit on the hot side of the heat engine; (3) a customized pellet boiler, able to extract electrical and thermal power; and (4) a customized hydraulic circuit, connecting the cool side of the Stirling engine and the heat generation on the second section of the pellet boiler. The objective of this paper was to present a new technology for the micro-cogeneration of energy at a distributed level able to be integrated in domestic dwellings. Most part of the available biomass is used in buildings for the generation of thermal power for indoor heating and, in minor cases, for hot sanitary water. In the Province of Trento, 88% of the biomass is used for this purpose. The full system is actually under integration for the test phase and not yet tested. The first tests on the single components have confirmed preliminary results on the Stirling engine with respect to the tolerances, pressurization, and proper integration of the electrical generator-driven control system. The pellet boiler has been tested separately, confirming an overall thermal efficiency of 90%.

Parallel finite-difference time-domain modeling of an opal photonic crystal

Abstract. This work describes a computational approach for the optical characterization of an opal photonic crystal (PC). We intend, in particular, to validate our approach by comparing the transmittance of a crystal model, as obtained by numerical simulation, with the transmittance of the same crystal, as measured over 400- to 700-nm wavelength range. We consider an opal PC with a face-centered cubic lattice structure of spherical particles made of polystyrene (a nonabsorptive material with constant relative dielectric permittivity). Light-crystal interaction is simulated by numerically solving Maxwell’s equations via the finite-difference time-domain method and by using the Kirchhoff formula to calculate the far field. A method to study the propagating Bloch modes inside the crystal bulk is also sketched.

Heat Transfer Analysis for a Small-Size Direct-Flow Coaxial Concentrating Collector

A coaxial evacuated solar tube has been analyzed. The tube is included in a small-scale concentrated solar power (CSP) system, which runs a cogeneration Stirling engine unit. The engine provides electricity and at the same time generates hot water for heating and sanitary purposes, by cooling down the compression cylinder. The present work is focused on the thermodynamic characterization for a forced-flow in the coaxial evacuated tube, which can heat thermal oil up to 300 C, when coupled with a parabolic trough collector. The single coaxial tube is 2 m long, it has one glass penetration, it is provided with a glass–metal seal and it has an absorber tube in the focal point with a diameter of 12 mm. A model based on heat transfer analysis coupled with fluid dynamic is presented and discussed. The model is then used to investigate spatial temperature profiles and thermal behaviors for the whole solar collector. It improves previous works in the field of concentrating solar collectors and covers the research in small-size concentrating system using thermal oil as heat transfer fluid. [DOI: 10.1115/1.4007297]

A parallel computational FDTD approach to the analysis of the light scattering from an opal photonic crystal

This paper describes the parallel computational approach for the analysis of the multiple scattering of light from a three dimensional ensemble of many spherical particles having an ordered face-centered cubic lattice structure. The solution is obtained by numerically solving the Maxwells equations using the FDTD (Finite Difference Time Domain) method with an impinging electromagnetic plane. The aim is to simulate the reflectance and transmittance of the system in the 300÷700 nm wavelength range, calculating also the angular power distribution of the scattered light. This study is suitable for the optical characterization of opal photonic crystals.

A fine-grained temperature monitoring system for sustainable geothermal boreholes

Ground source heat pumps offer a technology for the thermal conditioning of buildings which is both renewable and economically competitive against fuel-based solutions. However, in spite of the good performances already proved by several studies, the optimal operation and the long-term sustainability of a specific geothermal plant is always affected by a certain degree of uncertainty. The installation of accurate and stable temperature monitoring systems within geothermal boreholes would hence contribute significantly to increase the confidence towards this kind of technology. Unfortunately, existing temperature acquisition systems can be expensive and difficult to deploy, especially in small (i.e. domestic) plants. In this paper, first the general requirements of this kind of monitoring systems are described, in order to find a reasonable tradeoff between measurement accuracy and installation costs. Then, two different solutions, one based on Pt100 sensors, the other based on a more innovative 1-Wire® system are presented and compared. Finally, some meaningful experimental results are reported and commented.