Image partition and video segmentation using the Mumford-Shah functional

2010 - 2011The aim of this Thesis is to present an image partition and video segmentation procedure, based on the minimization of a modified version of Mumford-Shah functional. The Mumford-Shah functional used for image partition has been then extended to develop a video segmentation procedure. Differently by the image processing, in video analysis besides the usual spatial connectivity of pixels (or regions) on each single frame, we have a natural notion of “temporal” connectivity between pixels (or regions) on consecutive frames given by the optical flow. In this case, it makes sense to extend the tree data structure used to model a single image with a graph data structure that allows to handle a video sequence. The video segmentation procedure is based on minimization of a modified version of a Mumford-Shah functional. In particular the functional used for image partition allows to merge neighboring regions with similar color without considering their movement. Our idea has been to merge neighboring regions with similar color and similar optical flow vector. Also in this case the minimization of Mumford-Shah functional can be very complex if we consider each possible combination of the graph nodes. This computation becomes easy to do if we take into account a hierarchy of partitions constructed starting by the nodes of the graph.[edited by author]X n.s

How future surgery will benefit from SARS-COV-2-related measures: a SPIGC survey conveying the perspective of Italian surgeons

COVID-19 negatively affected surgical activity, but the potential benefits resulting from adopted measures remain unclear. The aim of this study was to evaluate the change in surgical activity and potential benefit from COVID-19 measures in perspective of Italian surgeons on behalf of SPIGC. A nationwide online survey on surgical practice before, during, and after COVID-19 pandemic was conducted in March-April 2022 (NCT:05323851). Effects of COVID-19 hospital-related measures on surgical patients' management and personal professional development across surgical specialties were explored. Data on demographics, pre-operative/peri-operative/post-operative management, and professional development were collected. Outcomes were matched with the corresponding volume. Four hundred and seventy-three respondents were included in final analysis across 14 surgical specialties. Since SARS-CoV-2 pandemic, application of telematic consultations (4.1% vs. 21.6%; p < 0.0001) and diagnostic evaluations (16.4% vs. 42.2%; p < 0.0001) increased. Elective surgical activities significantly reduced and surgeons opted more frequently for conservative management with a possible indication for elective (26.3% vs. 35.7%; p < 0.0001) or urgent (20.4% vs. 38.5%; p < 0.0001) surgery. All new COVID-related measures are perceived to be maintained in the future. Surgeons' personal education online increased from 12.6% (pre-COVID) to 86.6% (post-COVID; p < 0.0001). Online educational activities are considered a beneficial effect from COVID pandemic (56.4%). COVID-19 had a great impact on surgical specialties, with significant reduction of operation volume. However, some forced changes turned out to be benefits. Isolation measures pushed the use of telemedicine and telemetric devices for outpatient practice and favored communication for educational purposes and surgeon-patient/family communication. From the Italian surgeons' perspective, COVID-related measures will continue to influence future surgical clinical practice

Regulation of traffic lights at road junctions

In this work, we aim to investigate the effects of traffic lights regulation at road junctions, modelled by a fluid dynamic approach. Numerical simulations prove that it is possible to plan some optimization strategies for green and red phases for networks consisting of more nodes

Optimization of traffic flows in urban networks

We deal with the optimization of traffic flows at road junctions, in order to manage congestion phenomena. Using a fluid-dynamic model for the description of the car densities evolution, the attention is focused on a decentralized approach. Different cost functionals have been considered and they have been optimized with respect to right of way parameters and distribution coefficients. The redistribution of flows at nodes so as to maximize the velocity of emergency vehicles on assigned paths is also considered. The obtained results have been tested by simulations of urban networks. In some cases, decongestion effects are confirmed estimating the time a car needs to cross a fixed route on the network

Simulation of telecommunication flows using fluid dynamic models

A software application, that simulates the information flow in a telecommunication network, is proposed. The simulator is based on a continuous model obtained impos-ing the conservation of the mean number of packets among two consecutive nodes. For dynamics at nodes, we con-sider two “routing algorithms”, RA1 and RA2. The main difference among the two algorithms is the possibility of redirecting packets by the RA2 algorithm. We show the different behavior of the information flow in a simple net-work, using these two different algorithms

Mathematica nella simulazione e ottimizzazione di sistemi a coda

Scopo di questo lavoro è presentare Mathematica come strumento per la simulazione ed ottimizzazione di sistemi reali che possono essere modellati attraverso sistemi e reti di code. Le potenzialità numeriche, grafiche e di programmazione di Mathematica sono state sfruttate per sviluppare sia simulazioni ad eventi discreti, che permettono di analizzare le prestazioni in regime transiente e stazionario di sistemi e reti di code con distribuzioni generali dei tempi di inter-arrivo e di servizio, sia algoritmi ricorsivi per lo studio di particolari sistemi, con discipline di servizio diverse dalla FIFO, per i quali l’attività di ricerca ha condotto alla determinazione di formule ricorsive per il calcolo delle probabilità stazionarie. Si presenterà in particolare un caso di studio, relativo alle file di attesa presenti in una banca, in cui il simulatore per sistemi a coda è stato integrato con una routine di ottimizzazione, il cui scopo è quello di individuare il numero di sportelli aggiuntivi che possono essere aperti senza superare il budget economico di cui dispone la banca. Inoltre si mostreranno risultati numerici sotto forma di indici di prestazione per un sistema a coda del tipo PH/PH/1/r, con il server che ricerca gli utenti da servire, una rete tandem esponenziale con servizio impaziente e una rete tandem con utenti negativi e disciplina con perdita o con bloccaggio. Per l'analisi di tali sistemi ci si è avvalsi di formule ricorsive

Optimal paths on urban networks using travelling times prevision

We deal with an algorithm that, once origin and destination are fixed, individuates the route that permits to reach the destination in the shortest time, respecting an assigned maximal travel time, and with risks measure below a given threshold. A fluid dynamic model for road networks, according to initial car densities on roads and traffic coefficients at junctions, forecasts the future traffic evolution, giving dynamical weights to a constrained K shortest path algorithm. Simulations are performed on a case study to test the efficiency of the proposed procedure

Spectrophotometric system and method for the identification and characterization of a particle in a bodily fluid

The present invention provides a method and apparatus for the detection of an infectious disease or disorder in a fluid, such as a mammalian blood sample, the detection of a specific protein in a urine sample, or the detection of a particle in a plasma. The identification of the particles of interest is enable by taking a transmission spectrum of a test sample in at least a portion of the ultraviolet, visible, near-infrared portion of the spectrum and comparing the spectrum with a standard sample spectrum. From the comparison it is then determined whether the fluid from the test sample contains an particle of interest, and an identity of the particle of interest is determined. Spectroscopic and multiwavelength turbidimetry techniques provide a rapid, inexpensive, and convenient means for diagnosis. The comparison and determination steps may be performed visually or by spectral deconvolution

Situation Awareness and Environmental Factors: The EVO Oil Production

The paper considers simulation results for a supply network, that deals with Extra Virgin Olive (EVO) oil production, an activity that is typical of Southern Italy. The phenomenon is studied by differential equations, that focus on goods on arcs and queues for the exceeding goods. Different numerical schemes are used for simulations. A strategy of Situation Awareness allows defining a possible choice of the input flow to the supply network. The achieved results indicate that Situa- tion Awareness permits to find good compromises for the modulation of production queues and the optimization of the overall system features