La diffusione

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Vrije Universiteit Brussel

Un modello per la diffusione di una sostanza in un soluzione

Education

Università degli Studi del Molise
Corso di Modelli Matematici
La diffusione
Dario Di Nucci
Gennaio 2010

Soluzione fondamentale
dell’equazione di diffusione

Il limite di concentrazione iniziale
infinita

Soluzione generale dell’equazione
di diffusione

Grafici in Matlab
video equazione di diffusione

Test case prioritization (TCP) is aimed at finding an ideal ordering for executing the available test cases to reveal faults earlier. To solve this problem greedy algorithms and meta-heuristics have been widely investigated, but in most cases there is no statistically significant difference between them in terms of effectiveness. The fitness function used to guide meta-heuristics condenses the cumulative coverage scores achieved by a test case ordering using the Area Under Curve (AUC) metric. In this paper we notice that the AUC metric represents a simplified version of the hypervolume metric used in many objective optimization and we propose HGA, a Hypervolume-based Genetic Algorithm, to solve the TCP problem when using multiple test criteria. The results shows that HGA is more cost-effective than the additional greedy algorithm on large systems and on average requires 36% of the execution time required by the additional greedy algorithm.

A false digital alibi on mac os x

Vrije Universiteit Brussel

Issues and implementation of a process for creating a false digital alibi. The aim is to produce a state of the personal computer that confirming a false digital alibi, following the execution of an automated procedure, without leaving any traces of automation. The aim is to answer to the questions: 1) How reliable is a digital alibi? 2) May have been artificially created? Within the project, are discussed the issues to consider while creating a false alibi on a machine running Mac OS X and is demonstrated that it is possible to produce artificially "human" traces of machine use.

Next! Navigator

Vrije Universiteit Brussel

Jointly owned companies as instruments of local government

Vrije Universiteit Brussel

L’obiettivo di questo lavoro è migliorare l’accuratezza dei risultati forniti da un motore di ricerca, attraverso il profiling degli utenti. Attraverso le query fornite dall’utente e i risultati da questo selezionati, il sistema acquisisce esperienza in modo da restituire, in seguito, risultati con un grado di correttezza crescente. Nella tesi sono messi in evidenza i modelli matematici utili al profiling.

Lightweight Detection of Android-specific Code Smells: the aDoctor Project

Vrije Universiteit Brussel

Code smells are symptoms of poor design solutions applied by programmers during the development of software systems. While the research community devoted a lot of effort to studying and devising approaches for detecting the traditional code smells defined by Fowler, little knowledge and support is available for an emerging category of Mobile app code smells. Recently, Reimann et al. proposed a new catalogue of Android- specific code smells that may be a threat for the maintainability and the efficiency of Android applications. However, current tools working in the context of Mobile apps provide limited support and, more importantly, are not available for developers interested in monitoring the quality of their apps. To overcome these limitations, we propose a fully automated tool, coined aDoctor, able to identify 15 Android-specific code smells from the catalogue by Reimann et al. An empirical study conducted on the source code of 18 Android applications reveals that the proposed tool reaches, on average, 98% of precision and 98% of recall. We made aDoctor publicly available.

Search-based testing of procedural programs:iterative single-target or multi-...

Vrije Universiteit Brussel

In the context of testing of Object-Oriented (OO) software systems, researchers have recently proposed search based approaches to automatically generate whole test suites by considering simultaneously all targets (e.g., branches) defined by the coverage criterion (multi-target approach). The goal of whole suite approaches is to overcome the problem of wasting search budget that iterative single-target approaches (which iteratively generate test cases for each target) can encounter in case of infeasible targets. However, whole suite approaches have not been implemented and experimented in the context of procedural programs. In this paper we present OCELOT (Optimal Coverage sEarch-based tooL for sOftware Testing), a test data generation tool for C programs which implements both a state-of-the-art whole suite approach and an iterative single-target approach designed for a parsimonious use of the search budget. We also present an empirical study conducted on 35 open-source C programs to compare the two approaches implemented in OCELOT. The results indicate that the iterative single-target approach provides a higher efficiency while achieving the same or an even higher level of coverage than the whole suite approach.

Software-Based Energy Profiling of Android Apps: Simple, Efficient and Reliable?

Vrije Universiteit Brussel

Modeling the power profile of mobile applications is a crucial activity to identify the causes behind energy leaks. To this aim, researchers have proposed hardware-based tools as well as model-based and software-based techniques to approximate the actual energy profile. However, all these solutions present their own advantages and disadvantages. Hardware-based tools are highly precise, but at the same time their use is bound to the acquisition of costly hardware components. Model-based tools require the calibration of parameters needed to correctly create a model on a specific hardware device. Software-based approaches do not need any hardware components, but they rely on battery measurements and, thus, they are hardware-assisted. These tools are cheaper and easier to use than hardware-based tools, but they are believed to be less precise. In this paper, we take a deeper look at the pros and cons of software-based solutions investigating to what extent their measurements depart from hardware-based solutions. To this aim, we propose a software- based tool named PETrA that we compare with the hardware- based Monsoon toolkit on 54 Android apps. The results show that PETrA performs similarly to M ONSOON despite not using any sophisticated hardware components. In fact, in all the apps the mean relative error with respect to M ONSOON is lower than 0.05. Moreover, for 95% of the analyzed methods the estimation error is within 5% of the actual values measured using the hardware-based toolkit.

Evoluzione della normazione ISO

D'Eugenio Elisa

People management

Vrije Universiteit Brussel