Search results for "cluster analysis."

Action expertise reduces brain activity for audiovisual matching actions: An fMRI study with expert drummers

2011

When we observe someone perform a familiar action, we can usually predict what kind of sound that action will produce. Musical actions are over-experienced by musicians and not by non-musicians, and thus offer a unique way to examine how action expertise affects brain processes when the predictability of the produced sound is manipulated. We used functional magnetic resonance imaging to scan 11 drummers and 11 age- and gender-matched novices who made judgments on point-light drumming movements presented with sound. In Experiment 1, sound was synchronized or desynchronized with drumming strikes, while in Experiment 2 sound was always synchronized, but the natural covariation between sound in…

Weighted Least-Squares Likelihood Ratio Test for Branch Testing in Phylogenies Reconstructed from Distance Measures

2005

A variety of analytical methods is available for branch testing in distance-based phylogenies. However, these methods are rarely used, possibly because the estimation of some of their statistics, especially the covariances, is not always feasible. We show that these difficulties can be overcome if some simplifying assumptions are made, namely distance independence. The weighted least-squares likelihood ratio test (WLS-LRT) we propose is easy to perform, using only the distances and some of their associated variances. If no variances are known, the use of the Felsenstein F-test, also based on weighted least squares, is discussed. Using simulated data and a data set of 43 mammalian mitochondr…

Scatter tabu search for multiobjective clustering problems

2011

We propose a hybrid heuristic procedure based on scatter search and tabu search for the problem of clustering objects to optimize multiple criteria. Our goal is to search for good approximations of the efficient frontier for this class of problems and provide a means for improving decision making in multiple application areas. Our procedure can be viewed as an extension of SSPMO (a scatter search application to nonlinear multiobjective optimization) to which we add new elements and strategies specially suited for combinatorial optimization problems. Clustering problems have been the subject of numerous studies; however, most of the work has focused on single-objective problems. Clustering u…

Developing international social capital: The role of communities of practice and clustering

2019

Abstract One criteria regarding where to invest in foreign markets is linked to the international social capital (ISC) that exists on the place, which enables the access to local knowledge and other location-specific advantages. There are alternative ways to create and make use of that ISC that are still unexplored by International Business literature. In this paper, we study the geographic communities of practice (CoP) that are formed by FDI firms from the same country-of-origin (the so-called country-of-origin clusters). For that purpose, the paper adopts a qualitative methodological approach through an inductive case study of expatriates from 13 Spanish subsidiaries co-located in China. …

Detecting multiple copies in tampered images

2010

Copy-move forgeries are parts of the image that are duplicated elsewhere into the same image, often after being modified by geometrical transformations. In this paper we present a method to detect these image alterations, using a SIFT-based approach. First we describe a state of the art SIFT-point matching method, which inspired our algorithm, then we compare it with our SIFT-based approach, which consists of three parts: keypoint clustering, cluster matching, and texture analysis. The goal is to find copies of the same object, i.e. clusters of points, rather than points that match. Cluster matching proves to give better results than single point matching, since it returns a complete and co…

Influence of bio-based additives on RAP clustering and asphalt binder rheology

2017

The use of high Reclaimed Asphalt Pavement (RAP) content in Hot Mix Asphalt (HMA) allows developing innovative materials for the construction and/or rehabilitation of sustainable infrastructures. The chemo-physical phenomena occurring during production of HMA containing high RAP content should be investigated and considered for the mix design optimization. In fact, when additives are used as rejuvenators of the aged bitumen, these phenomena can be affected causing significant variations in the mixture characteristics. This paper aims at studying the influence of two bio-based additives specifically on RAP clustering, phenomena which can significantly affect the performance of high-content R…

VIII Colloque International –VIII International Conference - A.S.I. Analyse Statistique Implicative ––Statistical Implicative Analysis

2015

Le huitième colloque A.S.I. 8 s’est déroulé dans un contexte d’espérance stimulée pour la démocratie tunisienne avec l’attribution du Prix Nobel de la Paix pour 2015. Comme on a pu le lire dans les journaux : « Le comité Nobel norvégien a décidé de récompenser, vendredi 9 octobre 2015, le quartet menant le dialogue national en Tunisie, qui s’est distingué pour «sa contribution décisive dans la construction d’une démocratie pluraliste en Tunisie après la “révolution du jasmin” de 2011 » ». (Le Monde) Un tel contexte est de toute évidence plus propice à la créativité scientifique, à l’exercice de la pensée critique qui fonde les dimensions épistémologique et méthodologique des champs scientif…

VI Colloque International –VI International Conference - A.S.I. Analyse Statistique Implicative ––Statistical Implicative Analysis

2012

Field estimation in wireless sensor networks using distributed kriging

2012

In this paper, we tackle the problem of spatial interpolation for distributed estimation in Wireless Sensor Networks by using a geostatistical technique called kriging. We present a novel Distributed Iterative Kriging Algorithm (DIKA) which is composed of two main phases. First, the spatial dependence of the field is exploited by calculating semivariograms in an iterative way. Second, the kriging system of equations is solved by an initial set of nodes in a distributed manner, providing some initial interpolation weights to each node. In our algorithm, the estimation accuracy can be improved by iteratively adding new nodes and updating appropriately the weights, which leads to a reduction i…

Constrained Clusterwise Linear Regression

2005

In market segmentation, Conjoint Analysis is often used to estimate the importance of a product attributes at the level of each single customer, clustering, successively, the customers whose behavior can be considered similar. The preference model parameter estimation is made considering data (usually opinions) of a single customer at a time, but these data are usually very few as each customer is called to express his opinion about a small number of different products (in order to simplify his/her work). In the present paper a Constrained Clusterwise Linear Regression algorithm is presented, that allows simultaneously to estimate parameters and to cluster customers, using, for the estimati…