393 research outputs found
Advanced 3D photogrammetric surface reconstruction of extensive objects by UAV camera image acquisition
This paper proposes a replicable methodology to enhance the accuracy of the
photogrammetric reconstruction of large-scale objects based on the optimization of the procedures
for Unmanned Aerial Vehicle (UAV) camera image acquisition. The relationships between the
acquisition grid shapes, the acquisition grid geometric parameters (pitches, image rates, camera
framing, flight heights), and the 3D photogrammetric surface reconstruction accuracy were studied.
Ground Sampling Distance (GSD), the necessary number of photos to assure the desired overlapping,
and the surface reconstruction accuracy were related to grid shapes, image rate, and camera framing
at different flight heights. The established relationships allow to choose the best combination of grid
shapes and acquisition grid geometric parameters to obtain the desired accuracy for the required
GSD. This outcome was assessed by means of a case study related to the ancient arched brick
Bridge of the Saracens in Adrano (Sicily, Italy). The reconstruction of the three-dimensional surfaces of
this structure, obtained by the efficient Structure-From-Motion (SfM) algorithms of the commercial
software Pix4Mapper, supported the study by validating it with experimental data. A comparison
between the surface reconstruction with different acquisition grids at different flight heights and the
measurements obtained with a 3D terrestrial laser and total station-theodolites allowed to evaluate
the accuracy in terms of Euclidean distances
Ontology-based data access with databases: a short course
Ontology-based data access (OBDA) is regarded as a key ingredient of the new generation of information systems. In the OBDA paradigm, an ontology defines a high-level global schema of (already existing) data sources and provides a vocabulary for user queries. An OBDA system rewrites such queries and ontologies into the vocabulary of the data sources and then delegates the actual query evaluation to a suitable query answering system such as a relational database management system or a datalog engine. In this chapter, we mainly focus on OBDA with the ontology language OWL 2QL, one of the three profiles of the W3C standard Web Ontology Language OWL 2, and relational databases, although other possible languages will also be discussed. We consider different types of conjunctive query rewriting and their succinctness, different architectures of OBDA systems, and give an overview of the OBDA system Ontop
Experimental evaluation of the operating temperature impact on solid oxide anode-supported fuel cells
On the k-Boundedness for Existential Rules
The chase is a fundamental tool for existential rules. Several chase variants
are known, which differ on how they handle redundancies possibly caused by the
introduction of nulls. Given a chase variant, the halting problem takes as
input a set of existential rules and asks if this set of rules ensures the
termination of the chase for any factbase. It is well-known that this problem
is undecidable for all known chase variants. The related problem of boundedness
asks if a given set of existential rules is bounded, i.e., whether there is a
predefined upper bound on the number of (breadth-first) steps of the chase,
independently from any factbase. This problem is already undecidable in the
specific case of datalog rules. However, knowing that a set of rules is bounded
for some chase variant does not help much in practice if the bound is unknown.
Hence, in this paper, we investigate the decidability of the k-boundedness
problem, which asks whether a given set of rules is bounded by an integer k. We
prove that k-boundedness is decidable for three chase variants, namely the
oblivious, semi-oblivious and restricted chase.Comment: 20 pages, revised version of the paper published at RuleML+RR 201
Telenoid android robot as an embodied perceptual social regulation medium engaging natural human–humanoid interaction
The present paper aims to validate our research on human–humanoid interaction (HHI) using the
minimalist humanoid robot Telenoid. We conducted the human–robot interaction test with 142 young people who had no prior interaction experience with this robot. The main goal is the analysis of the two social dimensions (‘‘Perception’’ and ‘‘Believability’’) useful for increasing the natural behaviour between users and Telenoid.Weadministered our custom questionnaire to human subjects in association with a well defined experimental setting (‘‘ordinary and goal-guided task’’). A thorough analysis of the questionnaires has been carried out and reliability and internal consistency in correlation between the multiple items has been calculated. Our experimental results show that the perceptual behaviour and believability, as implicit social competences, could improve the meaningfulness and the natural-like sense of human–humanoid interaction in everyday life task-driven activities. Telenoid is perceived as an autonomous cooperative agent for a shared environment by human beings
Fitting regression model and experimental validation for a high pressure PEM electrolyzer
Abstract. Hydrogen production is the main obstacle today to develop a real future hydrogen economy. Research has focused many efforts in extracting it from clean and renewable sources. Different processes are analysed: photolysis, thermochemical cycles, algae, etc; these processes are still far from practical use. Electrolysis has represented the most studied and experimented area for obtaining hydrogen without employing fuel cracking. Nevertheless, for its practical storage, the hydrogen produced at low pressure needs to be mechanically compressed, with a high consumption of electric power. Advanced materials and improved design allow to obtain hydrogen from electrolysis directly at medium-high pressure (70 bar) with no need of mechanical compression stages. This single-step process is more efficient than the twostep electrolysis + mechanical compression process. In this paper the authors display the experimental results obtained with a prototype of high pressure PEM electrolyzer manufactured by Giner Electrochemical Systems LLC, including the description of the test bench for the experimental characterization. The experimental design, based on Design of Experiments techniques, studied the effect of the main operation factors (temperature, pressure, water flow) at different levels of power load, presenting a regression model of the electrolyzer voltage as a function of the operating factors, at different values of the electric load
Feature-Based Modelling of Laryngoscope Blades for Customized Applications
AbstractLaryngoscopes are used as diagnostic devices for throat inspection or as an aid to intubation. Their blade must be geometrically compatible with patients' anatomy to provide a good view to doctors with minimal discomfort to patients. For this reason, this paper was aimed to investigate the feasibility of producing customized blades.The customizable blade model was developed following a feature-based approach with eight morphological parameters. The thickness of such a blade was determined through numerical simulations of ISO certification tests, where the finite element mesh was obtained by morphing a 'standard' mesh.The following procedure was applied: the model was built from the selected parameters; the blade was tested in silico; finally, the blade was produced by additive manufacturing with an innovative biodegradable material (Hemp Bio-Plastic® -HBP-) claimed to feature superior mechanical properties. The procedure evidenced that the mechanical properties of current biodegradable materials are unsuitable for the application unless the certification norm is revised, as it is expected
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