Search results for "Abstract"
showing 10 items of 1959 documents
Graph Comparison and Artificial Models for Simulating Real Criminal Networks
2021
Network Science is an active research field, with numerous applications in areas like computer science, economics, or sociology. Criminal networks, in particular, possess specific topologies which allow them to exhibit strong resilience to disruption. Starting from a dataset related to meetings between members of a Mafia organization which operated in Sicily during 2000s, we here aim to create artificial models with similar properties. To this end, we use specific tools of Social Network Analysis, including network models (Barabási-Albert identified to be the most promising) and metrics which allow us to quantify the similarity between two networks. To the best of our knowledge, the DeltaCo…
Graph-based minimal path tracking in the skeleton of the retinal vascular network
2012
This paper presents a semi-automatic framework for minimal path tracking in the skeleton of the retinal vascular network. The method is based on the graph structure of the vessel network. The vascular network is represented based on the skeleton of the available segmented vessels and using an undirected graph. Significant points on the skeleton are considered nodes of the graph, while the edge of the graph is represented by the vessel segment linking two neighboring nodes. The graph is represented then in the form of a connectivity matrix, using a novel method for defining vertex connectivity. Dijkstra and Floyd-Warshall algorithms are applied for detection of minimal paths within the graph…
A New Simple Friction Model for S. I. Engine
2009
Internal combustion engine modeling is nowadays a widely employed tool for modern engine development. Zero and mono dimensional models of the intake and exhaust systems, combined with multi-zone combustion models, proved to be reliable enough for the accurate evaluation of in-cylinder pressure, which in turn allow the estimation of the engine performance in terms of indicated mean effective pressure (IMEP). In order to evaluate the net engine output, both the torque dissipation due to friction and the energy drawn by accessories must be taken into consideration, hence a model for the friction mean effective pressure (FMEP) evaluation is needed. One of the most used models accounts for engin…
A photographic method to estimate the shading effect of obstructions
2012
Abstract A new, simplified photographic method is proposed to estimate the shading effects of obstructions. In spite of the complex mathematical background of the new tool, its practical application is very simple, and only requires the measurements of three angles for each photograph. The proposed method is particularly useful for overcoming the difficulties caused by the need to accurately describe surrounding objects to estimate shading effects. The new method uses the information contained in a picture and allows one to draw daily solar paths directly on the photograph. The procedure is useful to verify the suitability of a generic site for solar exploitation; its main benefit is the si…
Ionic shortcut currents via manifolds in reverse electrodialysis stacks
2020
Abstract Reverse electrodialysis (RED) is a blue energy technology for clean and sustainable electricity harvesting from the mixing entropy of salinity gradients. Recently, many efforts have been devoted to improving the performance of RED units by developing new ion-exchange membranes and by reducing the detrimental phenomena affecting the process. Among these sources of “irreversibility”, the shortcut currents (or parasitic currents) flowing through alternative pathways may affect the process efficiency. Although such phenomena occur in several electrochemical processes (e.g. fuel cells, bipolar plate cells and vanadium redox flow batteries), they have received a poor attention in RED uni…
CFD analysis of the fluid flow behavior in a reverse electrodialysis stack
2012
Salinity Gradient Power by Reverse Electrodialysis (SGP-RE) technology allows the production of electricity from the different chemical potentials of two differently concentrated salty solutions flowing in alternate channels suitably separated by selective ion exchange membranes. In SGP-RE, as well as in conventional ElectroDialysis (ED) technology, the process performance dramatically depends on the stack geometry and the internal fluid dynamics conditions: optimizing the system geometry in order to guarantee lower pressure drops (DP) and uniform flow rates distribution within the channels is a topic of primary importance. Although literature studies on Computational Fluid Dynamics (CFD) a…
An Ambient Intelligence Architecture for Extracting Knowledge from Distributed Sensors
2009
Precisely monitoring the environmental conditions is an essential requirement for AmI projects, but the wealth of data generated by the sensing equipment may easily overwhelm the modules devoted to higher-level reasoning, clogging them with irrelevant details. The present work proposes a new approach to knowledge extraction from raw data that addresses this issue at different levels of abstraction. Wireless sensor networks are used as the pervasive sensory tool, and their computational capabilities are exploited to remotely perform preliminary data processing. A central intelligent unit subsequently extracts higher-level concepts represented in a geometrical space and carries on symbolic re…
A Novel Recruitment Policy to Defend against Sybils in Vehicular Crowdsourcing
2021
Vehicular Social Networks (VSNs) is an emerging communication paradigm, derived by merging the concepts of Online Social Networks (OSNs) and Vehicular Ad-hoc Networks (VANETs). Due to the lack of robust authentication mechanisms, social-based vehicular applications are vulnerable to numerous attacks including the generation of sybil entities in the networks. We address this important issue in vehicular crowdsourcing campaigns where sybils are usually employed to increase their influence and worsen the functioning of the system. In particular, we propose a novel User Recruitment Policy (URP) that, after extracting the participants within the event radius of a crowdsourcing campaign, detects …
A general theoretical framework for designing cognitive architectures: Hybrid and meta-level architectures for BICA
2012
In this paper, we will discuss hybrid architectures in which different processing modules coexist and cooperate in a principled way. A fundamental and essential role is played by modules performing meta-computation, i.e., computation about computation itself. Meta-level architectures, therefore, become an essential complement of hybrid architectures for biologically inspired cognitive architectures (BICA). Engineering and modeling BICAs is a hard task due to the lack of techniques for developing and implementing their features. We propose a new concept of intelligent agent as a useful abstraction for developing BICAs and having means for representing all the involved entities together with …
A Data Association Algorithm for People Re-Identification in Photo Sequences
2010
In this paper, a new system is presented to support the user in the face annotation task. Every time a photo sequence becomes available, the system analyses it to detect and cluster faces in set corresponding to the same person. We propose to model the problem of people re-identification in photos as a data association problem. In this way, the system takes advantage from the assumption that each person can appear at most once in each photo. We propose a fully automated method for grouping facial images, the method does not require any initialization neither a priori knowledge of the number of persons that are in the photo sequence. We compare the results obtained with our method and with s…