Search results for "DIF"
showing 10 items of 16936 documents
Super-fit and population size reduction in compact Differential Evolution
2011
Although Differential Evolution is an efficient and versatile optimizer, it has a wide margin of improvement. During the latest years much effort of computer scientists studying Differential Evolution has been oriented towards the improvement of the algorithmic paradigm by adding and modifying components. In particular, two modifications lead to important improvements to the original algorithmic performance. The first is the super-fit mechanism, that is the injection at the beginning of the optimization process of a solution previously improved by another algorithm. The second is the progressive reduction of the population size during the evolution of the population. Recently, the algorithm…
IMEX schemes for pricing options under jump–diffusion models
2014
We propose families of IMEX time discretization schemes for the partial integro-differential equation derived for the pricing of options under a jump-diffusion process. The schemes include the families of IMEX-midpoint, IMEX-CNAB and IMEX-BDF2 schemes. Each family is defined by a convex combination parameter [email protected]?[0,1], which divides the zeroth-order term due to the jumps between the implicit and explicit parts in the time discretization. These IMEX schemes lead to tridiagonal systems, which can be solved extremely efficiently. The schemes are studied through Fourier stability analysis and numerical experiments. It is found that, under suitable assumptions and time step restric…
Online anomaly detection using dimensionality reduction techniques for HTTP log analysis
2015
Modern web services face an increasing number of new threats. Logs are collected from almost all web servers, and for this reason analyzing them is beneficial when trying to prevent intrusions. Intrusive behavior often differs from the normal web traffic. This paper proposes a framework to find abnormal behavior from these logs. We compare random projection, principal component analysis and diffusion map for anomaly detection. In addition, the framework has online capabilities. The first two methods have intuitive extensions while diffusion map uses the Nyström extension. This fast out-of-sample extension enables real-time analysis of web server traffic. The framework is demonstrated using …
An Approach for Network Outage Detection from Drive-Testing Databases
2012
A data-mining framework for analyzing a cellular network drive testing database is described in this paper. The presented method is designed to detect sleeping base stations, network outage, and change of the dominance areas in a cognitive and self-organizing manner. The essence of the method is to find similarities between periodical network measurements and previously known outage data. For this purpose, diffusion maps dimensionality reduction and nearest neighbor data classification methods are utilized. The method is cognitive because it requires training data for the outage detection. In addition, the method is autonomous because it uses minimization of drive testing (MDT) functionalit…
Efficient Time Integration of Maxwell's Equations with Generalized Finite Differences
2015
We consider the computationally efficient time integration of Maxwell’s equations using discrete exterior calculus (DEC) as the computational framework. With the theory of DEC, we associate the degrees of freedom of the electric and magnetic fields with primal and dual mesh structures, respectively. We concentrate on mesh constructions that imitate the geometry of the close packing in crystal lattices that is typical of elemental metals and intermetallic compounds. This class of computational grids has not been used previously in electromagnetics. For the simulation of wave propagation driven by time-harmonic source terms, we provide an optimized Hodge operator and a novel time discretizati…
Research literature clustering using diffusion maps
2013
We apply the knowledge discovery process to the mapping of current topics in a particular field of science. We are interested in how articles form clusters and what are the contents of the found clusters. A framework involving web scraping, keyword extraction, dimensionality reduction and clustering using the diffusion map algorithm is presented. We use publicly available information about articles in high-impact journals. The method should be of use to practitioners or scientists who want to overview recent research in a field of science. As a case study, we map the topics in data mining literature in the year 2011. peerReviewed
Digital generations, but not as we know them
2019
The aim of this article is to see whether or not adolescents were the real leaders of the digital ‘revolution’ in the 1990s and whether they have sustained or even improved their position in the 2000s. The analysis is based on two surveys carried out in Italy, France, the United Kingdom, Germany, and Spain in 1996 ( N = 6609) and in 2009 ( N = 7255). The results show that the adolescents belonging to the first digital generation in 1996 were the most equipped with new technologies, although not the most intensive users. In 2009, the adolescents lost their position as the leading adopters and lagged behind youth and young adults regarding the use of new technologies and computer skills.
Riconfigurare i territori metroplitani. Forme di urbanizzazione e fenomeni di pressione insediativa sui sistemi di interesse naturale in Sicilia
2018
The consumption of the soil due to urbanization it is a phenomena already for many years under observations, but of which only the scientific environment has noticed the elevated environmental impact progress. From a disciplinary point of view, is possible to identify a line of research focusing on the analysis and identification of new morphologies of urbanization and on the interaction among different settlement patterns coexisting in a specific context. This reading complements with the scientific production about the forms of settlement pressure on environmental systems, producing change and deterioration on natural ecosystems and loss of biodiversity. A necessary reference for this lin…
Exploring relations between Big Five personality traits and musical emotions embodied in spontaneous dance
2022
We explored the hypothesis that musical emotions are embodied differentially by people according to their personality. Nine hundred and fifty two individuals completed the Big Five personality inventory. A subset of 60 participants were asked to spontaneously move to 30 short musical stimuli while being recorded with a motion-capture system. The musical stimuli were separately rated for perceived emotions. Embodied musical emotions were evaluated as the correlation between features derived from the motion-capture data and the mean ratings of perceived emotions. Correlations between embodied musical emotions and personality traits provided tentative support for our hypothesis. A series of l…
Equality and Difference in Olympe de Gouges’ Les droits de la femme. A La Reine
2019
This article examines Olympe de Gouges’ demands for the rights of woman in her famous but still understudied work Les droits de la femme. A La Reine [1791]. Particular emphasis is put on analysing how she combines her demand for equality with her conception of sexual difference. The article consists of three parts. The first part gives a brief overview of the demands for the equality of the sexes as they were presented in seventeenth-century France and critically reacted upon in eighteenth-century France, not least by Jean-Jacques Rousseau in his defence of sexual difference. The second and third parts focus on Gouges’ argumentation. First, by analysing how she argues for women’s active cit…