IRIS Università degli Studi dell'Aquila
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Electronic Band Structure of Gallium Sulfide (GaS) with Thickness Reduction Unveiling Parabolic and Pudding Mold Band Dispersion
Get PDFMetal monochalcogenides (MXs) have attracted significant interest due to their unique electronic properties, which can be tuned by varying the thickness. Gallium sulfide (GaS) stands out among MX compounds for its potential in photocatalysis, thanks to its bandgap within the visible range. However, the theoretical predictions of its band structure have not been experimentally validated until now. To bridge this gap, we performed angle-resolved photoemission spectroscopy (ARPES) measurements on bulk GaS to investigate its electronic band structure which revealed that the VBM is located at the Gamma point, and from the analysis of isoenergy contours just below the Fermi level, the contours are relatively circular and centered around the Gamma point indicating a high degree of isotropy and symmetry in the electronic states. Additionally, density functional theory (DFT) calculations revealed that the valence bands are composed of Ga 4s, Ga 4p, and S 3p orbitals, while the deeper bands are from S 3s orbitals. Furthermore, the theoretical calculations are extended to monolayer, two-layer, and three layer to observe the evolution in the band structure. Our results highlight a unique "Pudding Mold" valence band maximum (VBM) at the Gamma point, featuring multiple maxima dispersed throughout the Brillouin zone. When the GaS sample is thinned to monolayers, this band transforms into a "Pudding Mold" shape, characterized by significant corrugation at the Gamma point. This transformation predicts an increase density of states (DOS), which is highly advantageous for photocatalysis. The higher DOS enhances the absorption and utilization of visible light, which is essential in photocatalytic applications, and also provides more active sites for catalytic reactions
Performance analysis of multiple access protocols for sidelink vehicular communications
Get PDFThe term ”Intelligent Transportation System (ITS)” refers to all systems that make use of
communication, information processing, and technology to enhance the current mobility ex-
perience and to improve infrastructure productivity, mobility, and safety. The new technolo-
gies that make up the so-called ITS need to be properly tested and verified, obtaining, when-
ever possible, simple yet accurate analytical models to study and optimize their operation.
Strict standards are in place to meet the ever-changing vehicle application, communication
and service requirements of connected vehicles, such as Cellular Vehicle-to-everything (C-
V2X) communications. 3rd Generation Partnership Project (3GPP) has created standards
for Vehicle-to-everything (V2X) based on the Long-Term Evolution (LTE) and 5th Genera-
tion New Radio (5G-NR) Air Interface, which go under the names Long-Term Evolution-V2X
(LTE-V2X), and New Radio-V2X (NR-V2X), respectively, to facilitate connected and au-
tonomous driving use cases. The performance of both technologies is significantly influenced
by the resource allocation mechanism and multiple-access interference in scenarios with high
mobility. The C-V2X approaches must be able to handle the demands of the V2X appli-
cations. Vehicle platooning benefits from Sidelink (SL) communications to meet stringent
latency requirements at the cost of uncertainty in reliability due to multiple-access inter-
ference. In this context, Intelligent Reflective Surface (IRS) is a disruptive communication
approach that allows the possibility of controlling the propagation environment and improv-
ing the quality of wireless communications, making it a promising option to improve V2X
applications.
In this thesis, we propose an analytical framework to model the performance of the LTE-
V2X mode 4 and NR-V2X mode 2 SL protocols. Furthermore, we examine how to integrate
IRS and use Virtual Line-of-sight (VLOS) SL communications in vehicle platoons driving
in urban scenarios. We evaluated the effectiveness, particularly concerning Sensing-based
Semi-persistent Scheduling (SB-SPS) defined in a vehicle platooning scenario, depending on
the available resources, the number of interfering vehicles, and their relative positions. A
Nakagami-Lognormal composite channel model is assumed and Moment Matching Approx-
imation (MMA) is used to approximate the statistics of Signal-to-Interference plus Noise
Ratio (SINR). Compared to existing studies in the literature, the proposed model offers a
compact, yet accurate approximation of achievable performance in terms of packet success
rate and allows planning and adapting the configuration and parameter setup of the vehicle
platoon. The results confirm a improvement in performance with NR-V2X versus LTE-V2X,
particularly for many vehicles with a high distance between vehicles, providing a concise,
yet accurate, modeling rationale without having to resort to extensive computer simulation
or experimental measurements. The analysis further shows conditions in which VLOS SL
communication induced by IRS can also outperform the corresponding Line-of-sight (LOS)
propagation scenario.
Keywords: C-V2X, LTE-V2X, Mode 4, NR-V2X, Mode 2, Vehicular Communications,
SL Communications, IRS, LOS, VLOS, Multiple-access interference, Platooning
Perturbations of positive semigroups Factorized via AM– and AL-spaces
Get PDFIn this note we extend perturbation results for positive C_0 -semigroups on AM- and AL-spaces
generalizing them to arbitrary Banach lattices in case the perturbation can be factorized appropriately. The
abstract results are applied to domain perturbations of generators, a heat equation with boundary feedback
and perturbations of the first derivative
AUTONOMIA REGIONALE ED ESERCIZIO DEL POTERE GIURISDIZIONALE: LA PROSPETTIVA DEL CONFLITTO INTERSOGGETTIVO
No full textIl contributo intende analizzare il conflitto intersoggettivo fra Stato e regioni nella prospettiva del rapporto fra esercizio del potere giurisdizionale ed autonomia regionale. In particolare la riflessione muove dall’ampliamento dell’oggetto dei conflitti, dall’atto amministrativo all’atto giurisdizionale, e successivamente si concentra sulle attuali dinamiche del conflitto intersoggettivo, in particolare sui profili legati all’insindacabilità dei consiglieri regionali ed all’autonomia dei consigli regionali nell’esercizio della funzione legislativa e regolamentare
Sensori e Interfacce per l'Industria e la Biomedica
No full textThe design and development of sensor readout circuits are fundamental to modern signal processing systems. This research study focuses on investigating, designing, and analyzing novel circuits for sensor interfacing, especially for industrial and biomedical fields. A broad range of original oscillator-based and bridge-based conditioning circuits are discussed and analyzed. A significant contribution is the exploration of second-generation voltage conveyor oscillators, for which 34 novel VCII-based sinusoidal oscillator circuits have been discovered. Among these, 30 schemes are single-frequency oscillators, while the remaining 4 can also be used as variable-frequency oscillators. These circuits are particularly suitable for resistive and capacitive sensor interfacing. For the case in which these VCII interfaces have to be implemented on an integrated circuit, the design of a new low-voltage, low-power VCII topology in 150 nm CMOS technology is also presented. This design aims to represent a valid alternative to commercial VCII when low-power battery-powered portable applications are of concern, as is often the case. Concerning bridge-based interfaces, this research study also presents a novel bridge interface specifically designed for a research-level biomedical sensor used for NaCl concentration measurement. Differently from other solutions reported in the literature, the proposed interface has the advantage that it can also be used with non-purely resistive or capacitive sensors, such as the one considered here. Experimental and simulation results are reported for all the proposed solutions. These validate the theoretical treatment of the analysis performed and provide insight about the circuit performance. The obtained results confirm the suitability of the proposed schemes for implementing sensor interfaces meant to be used with several industrial and biomedical sensors in a broad range of applications
Observation of radio-frequency Mie resonances in high-permittivity dielectric spheres
Get PDFWe investigate Mie resonances in a high-permittivity dielectric (ceramic) sphere within the radio-frequency (RF) range, exploring its potential application in magnetic resonance imaging (MRI). Using a transmitting and a receiving RF coil, we observe Mie resonance signatures in both the transmission frequency spectrum and the magnetic field distribution surrounding a 40 mm-diameter sphere. Through full-wave numerical simulations and a standard fitting technique, we identify and characterize the lowest-frequency transverse-electric resonance modes of the sphere at 141.6, 201.4, 259.6, and 282.6 MHz, each exhibiting high-quality factors ( ∼ 300 ). Remarkably, we experimentally map the magnetic field distributions corresponding to each Mie resonance. Our results provide valuable insights for developing innovative approaches to manipulate RF waves, particularly by shaping and controlling the near-field outside the dielectric resonator through Mie resonances, an area largely unexplored in MRI technology
BVHSE Batch Vacuum-Heated Solvent Extraction with an innovative intensified evaporator/extractor SKID
No full textThis work aims to illustrate the results of experimental and plant research conducted in a chemical plant in Bussi sul Tirino. This plant specializes in the production of the Tetraconazole (TCZ) molecule, an active ingredient for fungicidal agro pharmaceuticals.
A by-product of the process is wastewater with solid suspensions and traces of aromatic substances that contain a high percentage of DiMethylSulfOxide (DMSO), a pricey solvent (€/kg) that is essential in the synthesis of Tetraconazole (TCZ). The disposal of treated wastewater, due to its high sulfur concentration, generates increasing difficulties in management and incineration costs that significantly impact the economy of the process as the local regulatory standards advance.
The promising technological solution to this problem is the BVHSE, 'Batch Vacuum Heated Solvent Extraction.' We have carefully researched and developed this technology by heating the wastewater batch to about 160°C under a controlled mid-vacuum, causing the DMSO to evaporate and then condense back, allowing for the separation of toluene and the recovery of DMSO in aqueous solution. A 'dry' solid waste with low sulfur content is obtained, a significant environmental benefit, and hence, easier disposed.
The experimental runs conducted on a bench scale led to design a new intensified evaporator called SKID and optimize the whole BVHSE plant, which have proven to be crucial for promoting reducing waste, dependence on raw materials through their reuse, and atmospheric emissions from hazard waste incineration in line with UN 2030 Sustainable Development Agenda and the EU Green Deal 2050.
The first economic feasibility analyses highlight how this initiative can significantly benefit the overall economy of TCZ production. The analyses indicate that the BVHSE technology can reduce waste disposal
and incineration costs, resulting in a payback time on investment return of about a year
Expanding Diversity of Fused Steroid-Quinoline Hybrids by Sequential Amination/Annulation/Aromatization Reactions
Get PDFViable alternative approaches to a variety of ring A
and ring D-fused steroid-quinoline hybrids, along with ring A, Dfused,
and/or ring A-fused, side chain-substituted steroid-bisquinolines
were explored by means of sequential amination/
annulation/aromatization reactions of suitable ketosteroids with 2-
acyl-substituted anilines. Key factors directing the chemoselective
behavior of polyfunctionalized substrates were investigated.
Remarkably, the use of TMSOTf as an alternative promoter/
catalyst enabled the direct synthesis of the desired hybrids,
avoiding the protection/deprotection steps of the conventional
procedures when the starting substrates contained labile functional
groups