1,721,260 research outputs found
Genetic operators for hierarchical graph clustering
No full textIn this paper we propose an encoding scheme and ad hoc operators for a genetic approach to hierarchical graph clustering. Given a connected graph whose vertices correspond to points within a Euclidean space and a fitness function, a hierarchy of graphs in which each vertex corresponds to a connected subgraph of the graph below is generated. Both the number of clustering levels and the number of clusters on each level are not fixed a priori and are subject to optimization. © 1998 Elsevier Science B.V. All rights reserved
Clustering by discovery on maps
No full textThis paper describes an algorithm for clustering on-line learned maps, requiring no 'a priori' knowledge of the environment. It uses the nearest neighbour rule, coupled with a threshold mechanism. Experimental results are shown on real and fictitious maps. © 1992
Solving open polygonals in elastic correction of dead-reckoning errors
No full textA major problem in map building is due to the imprecision of sensor measures. In a previous paper we proposed a technique, called elastic correction, for correcting the dead-reckoning errors made during the exploration of an unknown environment by a robot capable of identifying landmarks. Elastic correction is based on an analogy between the relational graph modelling the environment and a mechanical structure: the map is regarded as a truss where each route is an elastic bar and each landmark a node; errors are corrected as a result of the deformations induced from the forces arising within the structure as inconsistent measures are taken. The main weakness of this method lies in the way positional inconsistencies are solved when routes are covered for the first time. In this paper we improve first-sight elastic correction by replacing the heuristics previously adopted with a new approach which considers all the knowledge of the surrounding map acquired so far; this is achieved by calculating the minimum forces to be applied in order to restore metric consistency. The effectiveness of the new approach is demonstrated by presenting some experimental tests
CICERO: An assistant for planning visits to a museum
No full textIn this paper we present Cicero, a system for the assisted planning of personalized itineraries to visit the Ducal Palace in Urbino, Italy. The graphic interface gives users a structured and exhaustive view of the artistic content of the museum, and enables them to choose consciously which aspects to privilege during the visit. According to the user preferences, the system derives a set of constraints and then determines a personalized itinerary by means of a heuristic path-planning algorithm
View materialization vs. indexing: Balancing space constraints in data warehouse design
No full textView materialization and indexing are the most effective techniques adopted in data warehouses to improve query performance. Since both materialization and indexing algorithms are driven by a constraint on the disk space made available for each, the designer would greatly benefit from being enabled to determine a priori which fractions of the global space available must be devoted to views and indexes, respectively, in order to optimally tune performances. In this paper we first present a comparative evaluation of the benefit (saving per disk page) brought by view materialization and indexing for a single query expressed on a star scheme. Then, we face the problem of determining an effective trade-off between the two space fractions for the core workload of the warehouse. Some experimental results are reported, which prove that the estimated trade-off is satisfactorily near to the optimal one. © Springer-Verlag Berlin Heidelberg 2003
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Architetture pioniere. Forme e immagini per il mutamento della sensibilità estetica.
No full textI caratteri del paesaggio raccontano la storia delle culture locali e delle loro incessanti trasformazioni. La loro evoluzione è caratterizzata da gesti e idee progettuali che spesso aspirano a divenire modelli pervasivi di riferimento per nuove sensibilità estetiche e nuove modalità dell’abitare il territorio. Tuttavia tali gesti possono rimanere isolati, frammenti di visioni e rappresentazioni che non conosceranno mai gli sviluppi auspicati. L’imma¬gine rimane tutto ciò che di tali progetti esisterà; ma grazie alla sua elaborazione e al suo divenire pubblica il progetto può iniziare comunque a vivere.
L’immagine è, infatti, il seme del progetto. Può trovare un immaginario fertile e germogliare, oppure può depositarsi e rimanere in attesa di condizioni propizie per la sua potenziale metamorfosi in realtà. Sebbene non realizzate e talvolta irrealizzabili, le architetture vivono attraverso le loro immagini che, nel divenire pubbliche, danno vita a circuiti di critiche, speculazioni, dibattiti non dissimili da quelli generati dagli edifici effettivamente realizzati. Sono, queste, le manifestazioni della lotta tra una realtà che resiste alla trasformazione, e un futuro che – attraverso le immagini del progetto – tenta di forzare l’equilibrio esistente e scardinare le sensibilità estetiche consolidate così che possano accogliere le ipotesi trasformative che le rappresentazioni ambiscono ad anticipare
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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