ELECTROSTATIC SCRUBBING OF SUBMICRON PARTICLES: EXPERIMENTAL AND MODELING

This work contributes to the development of the technology of Wet Electrostatic Scrubbing (WES) at industrial scale by improving the current knowledge on corona charger unit design and designing, by building and setting up a pilot scale WES for specific industrial applications. This work was developed jointly by the Department of Chemical, Material and Industrial Production Engineering of the University of Naples Federico II” and the Ecology Division of the Boldrocchi s.r.l. . The Wet Electrostatic Scrubber is an upgrade of a conventional wet scrubber: it was proved that the electric forces are the main responsible for particle capture, more than the other physical phenomena that might be present in the scrubber. Therefore, the first topic covered by the study was the assessment of design criteria to scale up corona charger for particle charging. To understand the actual particle charge distribution of an ensemble of particles entering a corona device, several parameters have to be defined: particles residence time, local electric field and ion concentration, particle shape and composition. These parameters are generally considered on their mean value, but this approach is not adequate for predicting particle charges for a more complex system. For this reason, using the simulation program Ansys Fluent to gain some information concerning particle behavior in the reactor, two different particle charging models will be compared to experimental data. To provide a reliable assessment of particle charge, we developed a particle capture model in a WES unit coupling the particle capture model with the results of a dedicated computational Fluid dynamic analysis performed using Ansys Fluent. The model was used to describe the experimental data obtained by our research group in a smaller WES pilot tested in several conditions during the EFP7 DEECON project. In particular, this model includes a dedicated assessment of droplets size and charge distribution, which can be achieved properly only by experimental data and the relevant fluid dynamic parameters as gas residence time distribution, droplets spatial distribution and gas-droplets relative velocities, which are evaluated through the computational program Ansys Fluent (explained in Chapter 3 in detail). Averaged values of particle charges were determined using theoretical models and mean values of electric field, ion concentration and residence time in the pilot scale corona charger. This predictive model was applied to the case study and compared with the experimental data. In order to overcome the limited knowledge on particle charging, a reversed approach to data analysis was proposed. In this case, the data on particle capture in the WES were used to calculate the charge deposited on the particles and the achieved data were considered in terms of total aerosol current, applied voltage and particle size. These information were used to define design and operating conditions for the pilot WES system (operating at gas flow rates ranging from 5500 to 10.000 Nm3/h) build and operated at the Boldrocchi factory in Biassono (MB, Italy). The pilot scale system was operated in several conditions using reference Arizona test dust particles. The experimental data demonstrated that the WES units are able to achieve particle removal efficiencies higher than 90% in number, for particles from 150 to 800 nm, with results consistent with the design specifications

Free global DSM assessment on large scale areas exploiting the potentialities of the innovative google earth engine platform

The high-performance cloud-computing platform Google Earth Engine has been developed for global-scale analysis based on the Earth observation data. In particular, in this work, the geometric accuracy of the two most used nearly-global free DSMs (SRTM and ASTER) has been evaluated on the territories of four American States (Colorado, Michigan, Nevada, Utah) and one Italian Region (Trentino Alto-Adige, Northern Italy) exploiting the potentiality of this platform. These are large areas characterized by different terrain morphology, land covers and slopes. The assessment has been performed using two different reference DSMs: the USGS National Elevation Dataset (NED) and a LiDAR acquisition. The DSMs accuracy has been evaluated through computation of standard statistic parameters, both at global scale (considering the whole State/Region) and in function of the terrain morphology using several slope classes. The geometric accuracy in terms of Standard deviation and NMAD, for SRTM range from 2-3 meters in the first slope class to about 45 meters in the last one, whereas for ASTER, the values range from 5-6 to 30 meters. In general, the performed analysis shows a better accuracy for the SRTM in the flat areas whereas the ASTER GDEM is more reliable in the steep areas, where the slopes increase. These preliminary results highlight the GEE potentialities to perform DSM assessment on a global scale

A new spectroscopic approach to collective excitations in solids: pump-probe quantum state tomography

In a classical description the displacement of the atoms along the vibrational eigenmodes of a crystal can be measured with unlimited precision. Conversely, in the quantum formalism positions and momenta of the atoms can be determined simultaneously only within the boundary given by the Heisenberg uncertainty principle. For this reason, in real materials, in addition to the thermal disorder, the atomic displacements are subject to fluctuations which are intrinsic to their quantum nature. Because a crystalline solid has symmetries, these vibrations can be analyzed in terms of collective modes of motion of the atoms. These modes correspond to collective excitations called phonons. The aim of this thesis is to study the quantum fluctuations of the atoms involved in such collective vibrations. The motivation of studying the quantum proprieties of phonons in crystals comes from various evidences, recently reported in the literature, suggesting that quantum fluctuations of the atoms in solids may be of relevance in determining the onset of intriguing and still not completely understood material properties, such as quantum para-electricity, charge density waves, or high temperature superconductivity. The time evolution of phonons in crystals is usually addressed in the framework of ultrafast optical spectroscopy by means of pump-probe experiments. In these experiments the phonon dynamics is driven by an intense ultrashort laser pulse (the pump), and then the collective excitation is investigated in time domain through the interaction with a weaker pulse (the probe). Unfortunately this method typically provides information only about the average position of the atoms and an intense scientific debate is on-going about the possibility to have access also to the fluctuations of such positions measured with respect to a bound level for the shot-noise limit (intrinsic quantum noise limit). In this research activity a new approach to investigate quantum fluctuations of collective atomic vibrations in crystals is proposed. It combines time resolved optical spectroscopy techniques (pump and probe experiments) and quantum optics techniques (balanced homodyne detection). The novel spectroscopic tool, pumpprobe quantum state tomography, consists in the time domain characterization of the quantum state of probing light pulses after the interaction with the photo-excited material. The approach has been tested by investigating quantum fluctuations of the atomic positions in \u3b1-quartz, which serves as a case study for transparent materials. However, it can be in principle generalized to the study any collective excitations in crystals

Traveling in a fragile world: the value of ecoturism

What is ecotourism and why is it a current topic today more than ever? Tourism represents a significant economic sector and further forecasted to grow at a global level – exceeding even in the first few months of 2018 the most optimistic growth expectations according to WTTC (2018a)1. According to the International Ecotourism society2, ecotourism can be defined as a form of responsible tourism that prefers natural areas and that focuses its attention and commitment to conserve the environment and sustain the well-being of local people through interpretation (of heritage, traditions) and education (habitats, animals, cultures). Ecotourism has the potential to contribute, directly or indirectly, to all the objectives set by the 2030 Agenda3 for Sustainable Development4, which establishes ambitious global targets for people, planet, prosperity and peace through partnerships (UNWTO 2019; WCED 1987). Moreover, it provides the opportunity to preserve natural areas, through natural resources management and increasing environmental awareness and eco-friendly practices; provide sustainable economic growth of local communities in countries like Nepal, Costa Rica or Ecuador; preserve indigenous culture and tradition through educational programs; and reinvest money for conservation efforts like the protection of species or reforestation. However, critics to Ecotourism claim the negative impacts that this industry has on local people and environments as consequence of long travel distances (like the pollution generated by planes) and the negative impacts deriving from the presence of tourists in delicate environments (and the related production of waste or pollution). This paper aims to provide a general examination of the available data about the ecotourism activities on a global level, presenting examples from representative countries worldwide. We consider both the qualitative and quantitative aspects of this industry, trying to focus on what it represents in terms of its impacts and benefits for the country’s natural resources, communities and economy. In the first part of the manuscript, we compare ecotourism to other forms of natural resources’ use such as trophy hunting and mass tourism, trying to evaluate whether these represent a preferable alternative or not in terms of sustainability and economic benefits. The next section is divided by regions: Africa, The Americas, Europe, and Australia. For the study, we used statistics made available mainly by the World Travel and Tourism Council (WTTC) and the UN Environment World Conservation Monitoring Centre (UNEP-WCMC), together with information from specialized international literature

Industrial symbiosis: a sustainable approach for territorial development through the reuse of biomass

The worldwide demand of raw materials is facing an exponential increase since the economic boom registered in the second post-war scenario. The energy and the manufacturing industries are strictly dependent on the employment of non-renewable resources in the transformation and production processes, by contributing to the improvement of greenhouse gas emissions in the atmosphere and to the loss of natural capital. With the aim of increasing the environmental preservation in terms of biodiversity and raw materials access, this study contributes to examine the benefits of the circular economy approach for the promotion of industrial symbiosis practices, based on the horizontal collaboration and cooperation. According to this approach, the waste of one company can become secondary raw materials for other companies operating in the same or even in different sectors, by implementing territorial integration and networks in the industrial system

A Novel Approach to Reduce the Environmental Footprint of Maritime Shipping

Maritime shipping is a strategic sector with a strong international vocation and management. The need to define regulations valid for many different countries without generating disparities of treatment slowed down the formulation of environmental regulations, especially for atmospheric emissions. In particular, regulations pertaining to the reduction of sulphur compounds allowed two distinct approaches: the use of low-sulphur fuels or exhaust gas cleaning systems, the so-called Scrubbers. The actual implementation of these solutions presents specific concerns either related to the toxicity of atmospheric by-products and to the fuel cost or to the generation of polluting washwaters that may need treatment before discharge. In this paper we analyzed the potential environmental benefit deriving from the use of a distillate fuel, not compliant with current IMO Sulphur Regulations, together with a Scrubber. The pilot-scale experimental results indicated that a limited amount of water and/or scrubber volume is needed to reduce sulphur emissions below regulations on maritime shipping, especially with the addition of NaOH reaching a water-saving between 25%-33% compared to the use of pure seawater. Experiments indicated that scrubber washwater PAHs emissions are within the available water quality standards indicated by EU and USA guidelines. A bottom-up analysis on heavy metals concentration shed light on the prominent role of metal-parts corrosion on the washwater emissions. Taking into account for corrosion phenomena, the actual heavy metals concentration in the washwater deriving from scrubbing was normally below the water quality standards

Photon number statistics uncover the fluctuations in non-equilibrium lattice dynamics

Fluctuations of the atomic positions are at the core of a large class of unusual material properties ranging from quantum para-electricity to high temperature superconductivity. Their measurement in solids is the subject of an intense scientific debate focused on seeking a methodology capable of establishing a direct link between the variance of the atomic displacements and experimentally measurable observables. Here we address this issue by means of non-equilibrium optical experiments performed in shot-noise limited regime. The variance of the time dependent atomic positions and momenta is directly mapped into the quantum fluctuations of the photon number of the scattered probing light. A fully quantum description of the non-linear interaction between photonic and phononic fields is benchmarked by unveiling the squeezing of thermal phonons in $\alpha$-quartz.Comment: 7 pages (main text), 5 figures, 11 pages (supplementary information

Pulsed homodyne Gaussian quantum tomography with low detection efficiency

Pulsed homodyne quantum tomography usually requires a high detection efficiency limiting its applicability in quantum optics. Here, it is shown that the presence of low detection efficiency ($<50\%$) does not prevent the tomographic reconstruction of quantum states of light, specifically, of Gaussian type. This result is obtained by applying the so-called "minimax" adaptive reconstruction of the Wigner function to pulsed homodyne detection. In particular, we prove, by both numerical and real experiments, that an effective discrimination of different Gaussian quantum states can be achieved. Our finding paves the way to a more extensive use of quantum tomographic methods, even in physical situations in which high detection efficiency is unattainable

Towards weighing the condensation energy to ascertain the Archimedes force of vacuum

The force exerted by the gravitational field on a Casimir cavity in terms of Archimedes force of vacuum is discussed, the force that can be tested against observation is identified, and it is shown that the present technology makes it possible to perform the first experimental tests. The use of suitable high-Tc superconductors as modulators of Archimedes force is motivated. The possibility is analyzed of using gravitational wave interferometers as detectors of the force, transported through an optical spring from the Archimedes vacuum force apparatus to the gravitational interferometer test masses to maintain the two systems well separated. The use of balances to actuate and detect the force is also analyzed, the different solutions are compared, and the most important experimental issues are discussed.Comment: Revtex, 33 pages, 8 figures. In the final version, the title has been changed, and all sections have been improved, while 2 appendices have been adde