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335 result(s) for "Gaglione, S."
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THE 3D RECONSTRUCTION OF THE SANSEVERO CHAPEL ANATOMICAL MACHINES: A GEOMATICS CHALLENGE
This work presents the results of a geomatic survey conducted on the Anatomical Machines within the Sansevero Chapel in Naples, Italy. These anatomical artifacts have the unique characteristics of being upright standing skeletons with nearly intact circulatory systems. Previous research revealed that the intricate vascular systems, once believed to be natural, are instead elaborate reconstructions made using materials such as beeswax and dyes.In response to the lack of metric data of these models, a series of geomatic surveys has been conducted to create the Machines’ 3D models. This study discusses the theoretical and practical challenges associated with surveying these complex and fragile artifacts, emphasising the need for accurate extraction techniques to overcome the limitations imposed by the wooden cases in which they are encased. Two distinct approaches were used: a photogrammetric reconstruction and a laser scanning survey to overcome some logistical difficulties encountered. Despite the challenges, the 3D models' analysis gave satisfactory results.This work addresses the palaeopathological and anatomical questions related to the Anatomical Machines by leveraging non-invasive geomatic methodologies, shedding light on the complexities of surveying historically significant artifacts and aiming at further establishing a valuable foundation for improving these modelling techniques.
GNSS Reliability Testing in Signal-Degraded Scenario
Multiconstellation satellite navigation is critical in signal-degraded environments where signals are strongly corrupted. In this case, the use of a single GNSS system does not guarantee an accurate and continuous positioning. A possible approach to solve this problem is the use of multiconstellation receivers that provide additional measurements and allows robust reliability testing; in this work, a GPS/GLONASS combination is considered. In urban scenario, a modification of the classical RAIM technique is necessary taking into account frequent multiple blunders. The FDE schemes analysed are the “Observation Subset Testing,” “Forward-Backward Method,” and “Danish Method”; they are obtained by combining different basic statistical tests. The considered FDE methods are modified to optimize their behaviour in urban scenario. Specifically a preliminary check is implemented to screen out bad geometries. Moreover, a large blunder could cause multiple test failures; hence, a separability index is implemented to avoid the incorrect exclusion of blunder-free measurements. Testing the RAIM algorithms of GPS/GLONASS combination to verify the benefits relative to GPS only case is a main target of this work too. The performance of these methods is compared in terms of RMS and maximum error for the horizontal and vertical components of position and velocity.
3D MODELS COMPARISON OF COMPLEX SHELL IN UNDERWATER AND DRY ENVIRONMENTS
In marine biology the shape, morphology, texture and dimensions of the shells and organisms like sponges and gorgonians are very important parameters. For example, a particular type of gorgonian grows every year only few millimeters; this estimation was conducted without any measurement instrument but it has been provided after successive observational studies, because this organism is very fragile: the contact could compromise its structure and outliving. Non-contact measurement system has to be used to preserve such organisms: the photogrammetry is a method capable to assure high accuracy without contact. Nevertheless, the achievement of a 3D photogrammetric model of complex object (as gorgonians or particular shells) is a challenge in normal environments, either with metric camera or with consumer camera. Indeed, the successful of automatic target-less image orientation and the image matching algorithms is strictly correlated to the object texture properties and of camera calibration quality as well. In the underwater scenario, the environment conditions strongly influence the results quality; in particular, water’s turbidity, the presence of suspension, flare and other optical aberrations decrease the image quality reducing the accuracy and increasing the noise on the 3D model. Furthermore, seawater density variability influences its refraction index and consequently the interior orientation camera parameters. For this reason, the camera calibration has to be performed in the same survey conditions. In this paper, a comparison between the 3D models of a Charonia Tritonis shell are carried out through surveys conducted both in dry and underwater environments.
The overall motion induced interruptions as operability criterion for fishing vessels
A new index, namely the overall motion induced interruptions (OMII), is proposed as a seakeeping criterion for fishing vessels, to compare ships having different hull forms and dimensions by means of an only parameter, in a human centred approach, mainly related to the onboard risk level. Therefore, the first aim of the paper is to investigate the factors affecting fishing vessels’ seakeeping performances to improve them to reduce the high number of injuries occurring during fishing operations, mainly related to both risk perception and harsh weather conditions. Despite the classical approach, where motion induced interruption is determined for a certain sea state with regard to several location points, the new index accounts for all crew members’ positions on the working deck, all heading angles the vessel may experience during fishing operations, based on relevant operating scenario, and all sea states the ship may encounter in the fishing area. The influence of position, heading angles and sea states on the attained risk level is fully investigated, analysing seakeeping performances of four fishing vessels with different hull forms and dimensions. Finally, a new operability criterion is proposed, based on OMII, to investigate the influence of ship size and operating scenario on the risk of injuries during fishing operations. Main factors affecting fishing vessels’ seakeeping performances are fully discussed, paying attention to relevant correlation with ship roll natural period.
POSITION ACCURACY ANALYSIS OF A ROBUST VISION-BASED NAVIGATION
Using images to determine camera position and attitude is a consolidated method, very widespread for application like UAV navigation. In harsh environment, where GNSS could be degraded or denied, image-based positioning could represent a possible candidate for an integrated or alternative system. In this paper, such method is investigated using a system based on single camera and 3D maps. A robust estimation method is proposed in order to limit the effect of blunders or noisy measurements on position solution. The proposed approach is tested using images collected in an urban canyon, where GNSS positioning is very unaccurate. A previous photogrammetry survey has been performed to build the 3D model of tested area. The position accuracy analysis is performed and the effect of the robust method proposed is validated.
The satellite positioning evolution in coastal processes
In order to guarantee future generations, a fair and consistent level of environmental quality is necessary to ensure sustainable development of coastal resources. Adopting a static mode approach towards sea-level rise conflicts with sustaining a dynamic coastal system that responds to perturbations via sediment movement and long-term evolution. In the monitoring of this long-term evolution ancient technologies has played a very important role. Among these, satellite positioning is becoming more and more relevant. This paper presents a brief survey of the evolution of GNSS (Global Navigation Satellite Systems) application in coastal process. The Global Position System (NAVSTAR GPS) is the best known of these satellite navigation systems. Global Navigation Satellite System (GNSS) is the standard generic term for satellite navigation systems that provide autonomous geo-spatial positioning with global coverage. A GNSS allows small electronic receivers to determine their location (longitude, latitude, and height) to within a few metres using the signals as transmitted by the GNSS satellites. In the same process the receivers also calculate the precise time of the signal reception and as such GNSS receivers can be used as highly accurate clocks. Currently, the United States NAVSTAR Global Positioning System (GPS) is the only fully operational GNSS. The Russian GLONASS is a GNSS in the process of being restored to full operation. The European Union’s Galileo positioning system is a next generation GNSS in the initial deployment phase. China has indicated it may expand its regional Beidou (also called COMPASS) navigation system into a global system. India’s IRNSS, is also a next generation GNSS. However, its status and future is unclear as India seems to have entered into close cooperation with the Russians on the GLONASS system. Satellite Positioning, for this reason, is very popular and its accuracy can support a large
In vitro transformation of Pseudomonas corrugata by DNA of transgenic tomato plants
Occurrence of horizontal gene transfer from plants to soil bacteria has been shown by several studies, but very few studies have been carried out about gene transfer from GM plants to phytopathogenic bacteria. In the last years several analytical protocols have been developed in order to monitor transfer of DNA from transgenic plants to other microorganisms. These procedures are mainly based on the ability of bacteria to take up foreign DNA and integrate it into their genome by homologous recombination. Our preliminary experiments demonstrate that horizontal gene transfer occur, under optimized laboratory conditions, between GM tomato plants and the phytopatogenic bacterium Pseudomonas corrugata. Pseudomonas corrugata (pLaf nptII), carryng a plasmid with a deleted nptII gene, was able to capture DNA extracted from transgenic tomato plants and integrate it by homologous recombination. Restoration of nptII originated kanamycin-resistant transformants, that were detected when transformation was performed using plasmid DNA, plant DNA, and homogenates of tissues of GM plants carrying the functional gene nptII. DNA transfer was not detected when P. corrugata wild type strain (without nptII gene) was used as control.Greenhouse experiments are being planned to verify a possible transformation of P. corrugata by DNA of GM tomato plants in an in vivo interaction.
Unconditionally stable symplectic integrators for the Navier-Stokes equations and other dissipative systems
Symplectic integrators offer vastly superior performance over traditional numerical techniques for conservative dynamical systems, but their application to \\emph{dissipative} systems is inherently difficult due to dissipative systems' lack of symplectic structure. Leveraging the intrinsic variational structure of higher-order dynamics, this paper presents a general technique for applying existing symplectic integration schemes to dissipative systems, with particular emphasis on viscous fluids modeled by the Navier-Stokes equations. Two very simple such schemes are developed here. Not only are these schemes unconditionally stable for dissipative systems, they also outperform traditional methods with a similar degree of complexity in terms of accuracy for a given time step. For example, in the case of viscous flow between two infinite, flat plates, one of the schemes developed here is found to outperform both the implicit Euler method and the explicit fourth-order Runge-Kutta method in predicting the velocity profile. To the authors' knowledge, this is the very first time that a symplectic integration scheme has been applied successfully to the Navier-Stokes equations. We interpret the present success as direct empirical validation of the canonical Hamiltonian formulation of the Navier-Stokes problem recently published by Sanders~\\emph{et al.} More sophisticated symplectic integration schemes are expected to exhibit even greater performance. It is hoped that these results will lead to improved numerical methods in computational fluid dynamics.
Cigarette Butt Decomposition and Associated Chemical Changes Assessed by 13C CPMAS NMR
Cigarette butts (CBs) are the most common type of litter on earth, with an estimated 4.5 trillion discarded annually. Apart from being unsightly, CBs pose a serious threat to living organisms and ecosystem health when discarded in the environment because they are toxic to microbes, insects, fish and mammals. In spite of the CB toxic hazard, no studies have addressed the effects of environmental conditions on CB decomposition rate. In this study we investigate the interactive effects of substrate fertility and N transfer dynamics on CB decomposition rate and carbon quality changes. We carried out an experiment using smoked CBs and wood sticks, used as a slow decomposing standard organic substrate, incubated in both laboratory and field conditions for two years. CB carbon quality changes during decomposition was assessed by 13C CPMAS NMR. Our experiment confirmed the low degradation rate of CBs which, on average, lost only 37.8% of their initial mass after two years of decomposition. Although a net N transfer occurred from soil to CBs, contrary to our hypothesis, mass loss in the medium-term (two years) was unaffected by N availability in the surrounding substrate. The opposite held for wood sticks, in agreement with the model that N-rich substrates promote the decomposition of other N-poor natural organic materials with a high C/N ratio. As regards CB chemical quality, after two years of decomposition 13C NMR spectroscopy highlighted very small changes in C quality that are likely to reflect a limited microbial attack.
Smartphone GNSS Performance in an Urban Scenario with RAIM Application
In an urban scenario, GNSS performance is strongly influenced by gross errors in the measurements, usually related to multipath and non-line-of-sight phenomena. The use of RAIM algorithms is a common approach to solve this issue. A significant amount of the existing GNSS receivers is currently mounted on smart devices, above all, smartphones. A typical drawback of these devices is the unavailability of raw measurements, which does not allow fully exploiting the GNSS potential; in particular, this feature limits the use of RAIM algorithms. Since 2016, for few smart devices, it has been finally possible to access GNSS raw measurements, allowing the implementation of specific algorithms and enabling new services. The Xiaomi Mi 8 is equipped with the Broadcom BCM47755 receiver, able to provide dual-frequency raw measurements from quad-constellation GPS, Glonass, Galileo, BeiDou. In this work, the performance in an urban area of the Xiaomi Mi8 GNSS was analyzed. An important issue of smartphone GNSS is related to the antenna, which is not able to protect from the multipath phenomenon; this issue has a large probability to emerge in hostile environments like urban areas. As a term of comparison, the high-sensitivity receiver NVS NV08C-CSM, connected to a patch antenna, was used. In particular, the considered receivers were placed in the same location, and their positions were estimated in single point positioning, applying a classical RAIM algorithm. An error analysis was carried out, and the obtained results demonstrated the effectiveness of RAIM when applied to Xiaomi Mi8 GNSS measurements.