Politecnio die Bari - Catalogo di prodotti della Ricerca
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Blockchain and Knowledge Representation for Service-oriented Smart Mobility Platforms
Full text linkThe Smart Mobility vision calls for dynamic resource and service discovery to cope with the intrinsic topology volatility of Internet of Things (IoT) platforms without sacrificing the required business continuity and service flexibility. For an extended automation of collaboration within and across enterprise boundaries, trust management is equally important, granting security, reliability and scalability at the same time. To tackle the above challenges, this paper proposes the integration of a semantic-based service management layer in an IoT infrastructure grounded on the Hyperledger Sawtooth blockchain. Every service in the outlined framework is annotated with reference to a domain ontology, so that smart contracts can exploit knowledge representation and non-standard reasoning for service registration, discovery, outcomes explanation and service selection. A case study on power management of Plug-in Electric Vehicles (PEVs) is proposed to clarify the benefits of the proposal. Early performance evaluation results support the feasibility and sustainability of the approach
Characterization of Markarian 421 during its most violent year: Multiwavelength variability and correlations
No full textAims. Mrk 421 was in its most active state around early 2010, which led to the highest TeV gamma-ray flux ever recorded from any active galactic nuclei (AGN).We aim to characterize the multiwavelength behavior during this exceptional year for Mrk 421, and evaluate whether it is consistent with the picture derived with data from other less exceptional years. Methods. We investigated the period from November 5, 2009, (MJD 55140) until July 3, 2010, (MJD 55380) with extensive coverage from very-high-energy (VHE; E > 100 GeV) gamma rays to radio with MAGIC, VERITAS, Fermi-LAT, RXTE, Swift, GASP-WEBT, VLBA, and a variety of additional optical and radio telescopes. We characterized the variability by deriving fractional variabilities as well as power spectral densities (PSDs). In addition, we investigated images of the jet taken with VLBA and the correlation behavior among di_erent energy bands. Results. Mrk 421 was in widely di_erent states of activity throughout the campaign, ranging from a low-emission state to its highest VHE flux ever recorded. We find the strongest variability in X-rays and VHE gamma rays, and PSDs compatible with power-law functions with indices around 1.5. We observe strong correlations between X-rays and VHE gamma rays at zero time lag with varying characteristics depending on the exact energy band. We also report a marginally significant (_3_) positive correlation between high-energy (HE; E > 100 MeV) gamma rays and the ultraviolet band. We detected marginally significant (_3_) correlations between the HE and VHE gamma rays, and between HE gamma rays and the X-ray, that disappear when the large flare in February 2010 is excluded from the correlation study, hence indicating the exceptionality of this flaring event in comparison with the rest of the campaign. The 2010 violent activity of Mrk 421 also yielded the first ejection of features in the VLBA images of the jet of Mrk 421. Yet the large uncertainties in the ejection times of these unprecedented radio features prevent us from firmly associating them to the specific flares recorded during the 2010 campaign. We also show that the collected multi-instrument data are consistent with a scenario where the emission is dominated by two regions, a compact and extended zone, which could be considered as a simplified implementation of an energy-stratified jet as suggested by recent IXPE observations
Techno-economic comparison between commercial energy recovery devices in complex Water Distribution Networks
No full textWater Distribution Networks (WDN) proved to be viable for the exploitation of throttling hydraulic energy. Researchers often focused their attention on the study of Pumps as Turbines (PaTs) for WDNs without considering other solutions. Actually, PaTs are not the only machines that can be employed. Indeed, other solutions exists, e.g. Cross-Flow Turbines, and commercially available Energy Harvesting Control Valves. The novelty of this study regards the selection, for each node, of the best technology among these machines rather than choosing only among PaTs, in order to help the water utilities in the techno-economic decision processes. Regarding PaTs, the authors have updated and integrated PaT-ID, their proprietary decision making tool. A complex real WDN has been used as a case study, characterized by 8 reservoirs and 16 Pressure Reducing Valves (PRVs) installed to balance the network and to reduce water leakages. Although all the three considered type of devices show at least 40% of recovered available energy within the WDN, the best solution form an energy point of view not always could be feasible from an economic point of view
Sliding Viscoelastic Contacts: The Role of Adhesion, Boundary Conditions, and Finite Geometry
No full textIn this study, we investigate the tangential sliding of a rigid Hertzian indenter on a viscoelastic substrate, a problem of practical interest due to the crucial role that sliding contacts play in various applications involving soft materials. A finite element model is developed, where the substrate is modelled using a standard linear viscoelastic model with one relaxation time, and adhesion is incorporated using a Lennard–Jones potential law. We propose an innovative approach to model tangential sliding without imposing any lateral displacement, thereby enhancing the numerical efficiency. Our goal is to investigate the roles of adhesive regimes, boundary conditions (displacement and force-controlled conditions), and finite thickness of the substrate. Results indicate significant differences in the system’s behaviour depending on the boundary conditions and adhesion regime. In the short-range adhesion regime, the contact length L initially increases with sliding speed before decreasing, showing a maximum at intermediate speeds. This behaviour is consistent with experimental observations in rubber-like materials and is a result of the transition from small-scale to large-scale viscous dissipation regimes. For long-range adhesion, this behaviour disappears and L decreases monotonically with sliding speed. The viscoelastic friction coefficient μ exhibits a bell-shaped curve with its maximum value influenced by the applied load, both in long-range and short-range adhesion. However, under displacement control, μ can be unbounded near a specific sliding speed, correlating with the normal force crossing zero. Finally, a transition towards a long-range adhesive behaviour is observed when reducing the thickness t of the viscoelastic layer, which is assumed to be bonded to a rigid foundation. Moreover, the friction coefficient reduces when t tends to zero. These findings provide insights into the viscoelastic and adhesive interactions during sliding, highlighting the critical influence of boundary conditions on contact mechanics
Finite Element Analysis of a 3D-Printed Acetabular Prosthesis for an Acetabular Defect According to the Paprosky Classification
No full textThe treatment of Paprosky Type III acetabular defects is a significant challenge in orthopedic surgery, as standard components often do not fit properly. This study aims to evaluate the biomechanical efficacy of a custom 3D-printed PEEK acetabular prosthesis compared to a conventional titanium implant. A 3D model of the pelvis was created using a computed tomography scanner and a custom-made acetabular implant was designed. Finite element analysis (FEA) was performed using Ansys Workbench to evaluate the stress and strain distribution of two materials on the pelvic bone. The results showed that the titanium prosthesis model had less strain transmitted to the bone, while the PEEK model had better stress transmission and bone stimulation. The use of custom implants reduced the risk of stress shielding, potentially improving long-term bone health. Three-dimensional-printed acetabular prostheses therefore offer significant advantages over traditional implants, suggesting improved implant stability and reduced failure rates
A Low-Profile Dual-Polarized Transmitarray with Enhanced Gain and Beam Steering at Ku Band
Full text linkA low profile dual polarized transmitarray antenna, made of three identical layers, is proposed in this paper for Ku-band applications. The transmitarray comprises 22 × 22 symmetrical unit cells. A 3-bit phase compensation layer with less than αT = 1.3 dB transmission loss and 2π transmission phase coverage for both linear polarized components at the central frequency f0 = 12 GHz is designed. Moreover, for an incidence angle θ = 30°, the unit cell transmission loss is less than 2 dB; the transmission phase is close to the transmission phase at zero incidence angle θ = 0°. The fabricated transmitarray exhibits a measured peak gain of Gm0 = 21 dB at the frequency f0 = 12 GHz. The corresponding measured 1 dB gain bandwidth is BWg = 10.8% (11.1–12.4 GHz). The measured peak side lobe levels are SLL0 = −20.8 dB at f0 = 12 GHz. The transmitarray antenna can be used for beam steering up to an angle of γmax = ±30° with a measured scan loss △GMSL1 = 2.73 dB at f1 = 12.4 GHz
L’eredità di Alberto Magnaghi come patrimonio collettivo di una regione. L’esperienza del piano paesaggistico della Puglia
No full textIl contributo riflette sulla figura di Alberto Magnaghi coordinatore scientifico del piano paesaggistico della Puglia. Esso si concentra sull’importanza della prospettiva territorialista per restituire rilevanza alla pianificazione territoriale in una regione del Sud Italia, sulla capacità di Magnaghi di legare ricerca e azione superando il dilemma fra rigore scientifico e pertinenza, e sulle potenzialità generative del processo di pianificazione grazie all’originale mescolanza di visione utopica e pragmatismo
Unveiling the Water Built Heritage: Preliminary Results Towards a Systematic Cataloguing of Italian Ports
No full textSince ancient times, Italian ports served as fundamental landing places for travellers and played a crucial role in trade and tourist routes. Between the end of the 19th and the beginning of the 20th century, industrial development caused progressive physical and functional obsolescence of port areas, due to the overcoming of the production models, which they were conceived for. While some structures and infrastructures were upgraded to support the new maritime traffic, others were inadequate for the modern requirements and, thus, dismissed and abandoned, resulting nowadays in assets with a poor state of conservation. From recognizing the value of such built environments related to the maritime culture and processes of cultural stratification, the definition of methods and tools to support recovery and reuse plans is paramount. The present work proposes a cognitive framework to define heritage features of port environments and set up a systematic categorisation process.
To this aim, a cataloguing card was proposed and validated on 63 Italian port areas, including their relationship with the territorial surroundings, particularly the urban context, and the functions hosted within. The most recurrent types of heritage assets (over 300 items) were then evaluated, with the support of two national platforms, following a classification among modern, historical, industrial, archaeological, infrastructural and artistic heritage. At the end of the survey, it was found that the available platforms are lacking in data and non-properly meeting the specific research goals. In fact, even when heritage structures and infrastructures are catalogued, relevant information, such as the chronology of historical evolution and graphic descriptive contents, are missed. The results of this work provide some preliminary insights and a starting point for detailed analysis aimed at developing systematic cataloguing systems for the benefit of technicians, administrators and safeguard entities
On the user-based assessments of virtual reality for public safety training in urban open spaces depending on immersion levels
No full textThe increasing use of VR (Virtual Reality) training tools in safety-related fields has prompted the scientific community to explore methods for assessing their effectiveness across different levels of immersion. While numerous studies have been conducted in sectors such as healthcare, transportation, agriculture, aviation, mining, firefighting, and construction, one area that remains underexplored is risk training for general public
against natural and man-made disasters in both indoor and outdoor built environments. In this context, the paper aims at validating a prototype for VR multi-risk (heat wave and earthquake) training in urban open spaces that was developed according to a Serious Game (SG) approach. To address insights on its extensive adoption, the VR-SG was tested for comparison of three modes: traditional by video recording, non-immersive by desktop,
immersive by headset. Outputs from feedback questionnaires on knowledge gain and transfer to expansive contexts, as well as on user experience, suggest that the effectiveness of knowledge acquisition differs significantly between headset and video, as well as between desktop and video, but shows no significant difference between headset and desktop. Additionally, while headset outperforms desktop in terms of engagement,
perceived usefulness, and realism, it falls behind in ease of use. Finally, further analyses on training outcome by age, contents of open-ended answers, in-game errors and administration procedures supported the discussion of key aspects in targeting VR for public safety communication
Radiation Damage on SiPM for High Energy Physics Experiments in space missions
Full text linkSilicon photomultipliers (SiPMs) are a popular choice for various applications, especially in astroparticle physics. These devices are coupled with organic or inorganic scintillators, allowing them to detect scintillation light and Cherenkov light. They are particularly promising for space missions because of their compact size, low operating bias, and non sensitivity to magnetic fields. We studied the effects of proton irradiation at fluences up to 1 × 1011p/cm2 on FBK’s NUV-HD-lowCT SiPMs with 40 μm and 15 μm cell pitches. Proton-induced bulk damage increased the dark count rate (DCR) and dark current, with no significant changes in the breakdown voltage. These results align with previous studies on radiation effects in SiPMs and provide insights to mitigate performance degradation in space applications