Politecnio die Bari - Catalogo di prodotti della Ricerca
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Markov chain-based analytical model supporting service provisioning and network design in the Social Internet of Everything
Get PDFThe Internet of Everything has emerged as a prominent paradigm, enabling the development of advanced services by integrating
smart objects, individuals, processes, and data. In the context of social networking within this framework, addressing the inherent
uncertainty of the environment and developing secure service provisioning mechanisms is crucial. At present, there has been limited exploration into the stochastic behavior of the service fulfillment process, especially when considering the trustworthiness and
resource availability of service providers. Additionally, existing approaches supporting service provisioning often require continuous and computationally prohibitive efforts. To overcome these challenges, this paper introduces a Markov chain-based stochastic
model that effectively predicts the steady-state behavior of service providers within an IoE network. The proposed model integrates
both the trust levels and resource capabilities of providers to ensure successful service delivery, while simultaneously identifying
and excluding malicious entities without imposing significant computational overhead. The validity of the model is demonstrated by
comparing various performance metrics against results obtained from extensive simulations, highlighting its effectiveness and practical applicability. Ultimately, the model serves as a valuable tool for fostering trusted service provisioning, optimizing the design
of service communities within social networks, preventing data traffic loss, and enhancing the overall reliability and responsiveness
of the syste
Simultaneous Detection of 12CH4, 13CH4, and Related Isotope Ratio Exploiting a Frequency-Multiplexed Mid-Infrared Quartz-Enhanced Photoacoustic Sensor
No full textWe report the development of a dual-gas Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) sensor operating in the mid-infrared range for the simultaneous detection of 12CH4 and 13CH4. The sensor employs a frequency-modulated multiplexing scheme using two distributed-feedback quantum cascade lasers to independently excite the fundamental (fo) and overtone (f1) vibrational modes of a quartz tuning fork coupled with resonator tubes. The f0-demodulated signal is dedicated to monitoring 12CH4, while the f1-demodulated signal selectively quantifies 13CH4, enabling the analysis of the isotopic composition of methane samples. Calibration measurements demonstrated a linear response of the QEPAS signal to varying 13CH4 concentrations in CH4-based samples diluted in N2, with a precision of 1‰ in detecting isotopic delta ratio variations for 1% CH4 mixtures at 0.8 s integration time. The proposed system is suitable for real-time, high-precision isotopic methane sensing aimed at applications such as environmental monitoring, geochemical tracing, and industrial process control
Vertical Dense Jets in Crossflows: A Preliminary Study with Lattice Boltzmann Methods
No full textThe dramatic increase in domestic and industrial waste over recent centuries has significantly polluted water bodies, threatening aquatic life and human activities such as drinking, recreation, and commerce. Understanding pollutant dispersion is essential for designing effective waste management systems, employing both experimental and computational techniques. Among Computational Fluid Dynamics (CFD) techniques, the Lattice Boltzmann Method (LBM) has emerged as a novel approach based on a discretized Boltzmann equation. The versatility and parallelization capability of this method makes it particularly attractive for fluid dynamics simulations using high-performance computing. Motivated by its successful application across various scientific disciplines, this study explores the potential of LBM to model pollutant mixing and dilution from outfalls into surface water bodies, focusing specifically on vertical dense jets in crossflow (JICF), a key scenario for the diffusion of brine from desalination plants. A full-LBM scheme is employed to model both the hydrodynamics and the transport of the saline concentration field, and Large Eddy Simulations (LES) are employed in the framework of LBM to reduce computational costs typically associated with turbulence modeling, together with a recursive regularization procedure for the collision operator to achieve greater stability. Several key aspects of vertical dense JICF are considered. The simulations successfully capture general flow characteristics corresponding to jets with varying crossflow parameter (Formula presented.) and most of the typical vortical structures associated with JICF. Relevant quantities such as the terminal rise height, the impact distance, the dilution at the terminal rise height, and the dilution at the impact point are compared with experimental results and semi-empirical relations. The results show a systematic underestimation of these quantities, but the key trends are successfully captured, highlighting LBM’s promise as a tool for simulating wastewater dispersion in aquatic environments
Engineering the Structure and Optical Properties of Gold Nanostars with Microfluidics
No full textGold nanostars (AuNS) are anisotropic gold nanoparticles with structure-tunable optical properties. Most synthetic protocols rely on multistep procedures and on the use of cytotoxic and/or strongly bound chemicals, which can hamper AuNS applications. While the synthesis of AuNS with HEPES overcomes these limitations by using a biocompatible buffer that acts as both a shape-directing and a reducing agent, the resulting nanoparticles are highly heterogeneous and polydisperse. In this paper, we use a microfluidic chip to manipulate the morphology and optical properties of AuNS, while significantly improving their monodispersity. Notably, by adjusting microfluidic parameters, including viscosity of the organic phase, flow rate ratio, and buffer-to-gold ratio, this protocol can manipulate the growth mechanism of the nanoparticles, switching between seedless and seed-mediated-like growth, and it does so without the need to add a presynthesized seed. Such control is not possible with one-pot bench synthesis. Our results provide new opportunities to tailor the growth and formation of gold nanoparticles while significantly improving their monodispersity
Embedding a controlled layer of hydroxyapatite on a Ti- 6 Al- 4 V substrate in superplastic condition
No full textThe scientific research in the biomedical sector has underlined the importance of going beyond the basic requirements of the biomaterials, i.e., to be bioinert and avoid the occurrence of any adverse effects once in contact with a biological environment. In fact, the next generation of biomaterials must ensure anti-bacterial and bioactive properties to, for example, accelerate the bone regrowth. Therefore, the activation of a bioinert surface implies an additional step that is generally carried out after the manufacturing process. In the present work, an alternative route is investigated and is based on the mechanical deposition of hydroxyapatite (HA) particles on a Ti- 6 Al- 4 V ELI by applying a compressive load in superplastic conditions. Embedding tests were experimentally carried out using a designed equipment interfaced with a universal Instron testing machine. The applied load and the holding time were changed over three levels according to a full factorial plan and adopting a HA powder with a controlled particles size ranging from 80 to 150 μm. Post-embedding properties were initially analyzed via optical microscopy and further deepened via scanning electron microscopy (SEM). It was demonstrated that high level of the applied load combined with prolonged holding time led to the embedding of an 18 μm uniformly thick layer of HA. The scratch tests proved that embedding in superplastic conditions could ensure a level of adhesion strength comparable to other deposition techniques
A replicator model with transport dynamics on networks for species evolution
No full textThis paper proposes a network-based framework to model and analyze the evolution and dynamics of a marine ecosystem. The model involves two different length scales: the evolution of species in local reserves and the exchange of species between reserves. At the inter-reserve level, species evolution is ruled by the replicator equation, while a transport function accounts for the transport at the network level. This multi-scale approach allows for capturing both local dynamics within individual reserves and the broader connectivity and interactions across the network. We study how equilibria are modified due to the exchange between connected nodes and prove that evolutionarily stable states are asymptotically stable if the velocity transfer is contained within a condition involving the maximum degree of the network. A fourth-order P-(EC)formulation of the Gauss-Legendre Runge Kutta scheme is adopted. This numerical procedure is challenged against a suitable numerical experiment involving three species on a single node for validating the robustness of the scheme in terms of accuracy for a large observation time. Several numerical experiments are provided for characterizing the abilities and limitations of the model. Three prototypical networks are considered for the case of two- and three-agent games with both linear and nonlinear transport terms. Moreover, the ability of the proposed model to reproduce synchronization phenomena on networks is discussed. This approach has been demonstrated to have the potential to uncover insights into the stability, resilience, and long-term behavior of these ecosystems, offering valuable tools for their conservation and management
Castello grande. Brindisi
No full textIl progetto Monografie di Rilievo. Architetture fortificate di Puglia propone un approccio scientifico al rilievo e alla rappresentazione dell’architettura militare regionale, intesa come sistema integrato di difesa e controllo del territorio. L’indagine si fonda su rilievi sistematici, restituzioni grafiche e analisi morfologiche e tipologiche, con l’obiettivo di costruire un “atlante” delle architetture fortificate pugliesi. Tale ricerca si inserisce nella collana Monografie di Rilievo, che promuove la pubblicazione di rilievi del patrimonio architettonico monumentale nazionale e internazionale, valorizzando la fedeltà della traduzione grafica, la precisione delle osservazioni e la verificabilità dei dati. La monografia dedicata al Castello Grande di Brindisi costituisce il primo esito concreto di questo progetto, offrendo una base documentaria verificabile e replicabile. Le conclusioni evidenziano il carattere aperto dell’iniziativa: il rilievo non rappresenta una fine, ma un supporto dinamico per ulteriori studi e per la creazione di banche dati digitali a servizio della ricerca interdisciplinare e della costruzione di un abaco dell’architettura fortificata pugliese.The project Monografie di Rilievo. Architetture fortificate di Puglia proposes a scientific approach to the survey and representation of regional military architecture, understood as an integrated system of territorial defense and control. The investigation is based on systematic surveys, graphic restitutions, and morphological and typological analyses, with the goal of constructing an “atlas” of Apulian fortified architectures. This research is part of the Monografie di Rilievo series, which promotes the publication of surveys of national and international monumental architectural heritage, emphasizing the fidelity of graphic translation, the precision of observations, and the verifiability of data. The monograph dedicated to the Castello Grande of Brindisi represents the first concrete outcome of this project, providing a verifiable and replicable documentary foundation. The conclusions highlight the open-ended nature of the initiative: the survey is not conceived as a conclusion, but as a dynamic tool for further research and for the creation of digital databases serving interdisciplinary studies and the construction of a taxonomy of Apulian fortified architecture
Thue-Morse Code Implementation for the Design of a Concentric Hexagonal Ring Array
No full textThis work explores the performance improvement of a phased antenna array by modifying its topology. A non-conventional, quasiperiodic array configuration is proposed, where the radiating elements are arranged in a concentric hexagonal structure with an inter-ring spacing determined by a Thue-Morse sequence. The spacing between concentric hexagons is varied quasiperiodically to analyze its impact on key performance metrics, including half-power beamwidth, side lobe level, and directivity. The performance of the array is evaluated using MATLAB simulations, and the results demonstrate that this unconventional configuration can effectively enhance some key metrics for the antenna array
Il racconto è di scena. Un ricordo di Mauro Pagano
No full textNel 1988 moriva prematuramente lo scenografo Mauro Pagano, nato nel piccolo paese di Canneto sull’Oglio (Mantova) nel 1951. Con una rapidissima ascesa, arriva a collaborare con grandissimi registi, affermandosi per bellezza di segno e intensità narrativa nei maggiori teatri. Alla morte, la famiglia dona i bozzetti rimasti in proprio possesso al teatro del paese natio, che per l’occasione gli viene intitolato. Attraverso l’analisi di alcuni di questi disegni, la ricerca delle ascendenze e degli addensamenti narrativi, lo scritto intende analizzare le modalità dell’intento descrittivo, ipotizzando una collocazione di senso per il tipo di narrazione a esso sotteso