Search results for "Geometry"
showing 10 items of 4487 documents
Potentiometric study of the formation of hydroxo complexes of [Cu(terpy)]2+. Synthesis and crystal structure of [Cu(terpy) (H2O)](CF3SO3)2
1992
Two complexes of formula [Cu(terpy)(H2O)](CF3SO3)2 (1) and [Cu(terpy)(OH)]BPh4 (2) (terpy=2,2′∶6′,2″-terpyridine and BPh4=tetraphenylborate anion) have been synthesized and characterized by spectroscopic techniques. The x-ray crystal structure of (1) has been determined by x-ray diffraction. The structure is made up of [Cu(terpy)(H2O)]2+ mononuclear cations plus semi-coordinated CF3SO3 − anions. The coordination geometry around the copper atom is approximately elongated tetragonal octahedral. The oxygen atom of water and the three nitrogen atoms of terpy occupy the equatorial sites whereas the apical ones are filled by trifluoromethanesulphonate oxygen atoms. The formation of hydroxo comple…
Automatic Dictionary Creation by Sub-symbolic Encoding of Words
2006
This paper describes a technique for automatic creation of dictionaries using sub-symbolic representation of words in cross-language context. Semantic relationship among words of two languages is extracted from aligned bilingual text corpora. This feature is obtained applying the Latent Semantic Analysis technique to the matrices representing terms co-occurrences in aligned text fragments. The technique allows to find the “best translation” according to a properly defined geometric distance in an automatically created semantic space. Experiments show an interesting correctness of 95% obtained in the best case.
Cost-driven framework for progressive compression of textured meshes
2019
International audience; Recent advances in digitization of geometry and radiometry generate in routine massive amounts of surface meshes with texture or color attributes. This large amount of data can be compressed using a progressive approach which provides at decoding low complexity levels of details (LoDs) that are continuously refined until retrieving the original model. The goal of such a progressive mesh compression algorithm is to improve the overall quality of the transmission for the user, by optimizing the rate-distortion trade-off. In this paper, we introduce a novel meaningful measure for the cost of a progressive transmission of a textured mesh by observing that the rate-distor…
FISICA QUANTISTICA E FUNZIONI MENTALI SUPERIORI III
2010
Questo saggio riprende alcuni concetti di anatomia comparata e di fisiologia, sviluppati in una mia precedente ricerca dal titolo Termodinamica, campi quantici e funzioni mentali. Il fine è di chiarire alcuni punti controversi posti dall’analisi scientifica, in riguardo a teoremi di neuro anatomia e di neurofisiologia. Il filosofo Heiddegger H. riteneva che il pensiero umano non può affidarsi interamente all’indagine scientifica, traducendo in schemi ed in formule la vivente realtà della natura, sia fisica che biologica. La ricerca scientifica si basa su un sapere rigoroso e preciso, altamente dimostrativo che può competere con la matematica, ritenuta la scienza delle scienze. Nonostante ci…
FISICA QUANTISTICA E FUNZIONI CEREBRALI SUPERIORI (II)
2010
Data una semplice perturbazione, il processo lineare tende a rimanere leggermente alterato. Data la stessa perturbazione, un processo non lineare tende a tornare al suo punto di partenza. Huygens C. (fisico olandese del XVI sec.) inventò l’orologio a pendolo e la disciplina classica della dinamica. S’imbatté in uno dei grandi esempi di questa forma di regolazione. Huygens notò che vari orologi a pendolo, appoggiati contro una parete stavano oscillando in modo perfettamente sincronizzato. Sapeva che gli orologi non potevano essere così precisi. Huygens ipotizzò che gli orologi fossero coordinati da vibrazioni trasmesse attraverso la parete. Al presente, il fenomeno è definito agganciamento d…
FISICA QUANTISTICA E FUNZIONI CEREBRALI SUPERIORI.
2010
Robust Synchronization-Based Graph Clustering
2013
Complex graph data now arises in various fields like social networks, protein-protein interaction networks, ecosystems, etc. To reveal the underlying patterns in graphs, an important task is to partition them into several meaningful clusters. The question is: how can we find the natural partitions of a complex graph which truly reflect the intrinsic patterns? In this paper, we propose RSGC, a novel approach to graph clustering. The key philosophy of RSGC is to consider graph clustering as a dynamic process towards synchronization. For each vertex, it is viewed as an oscillator and interacts with other vertices according to the graph connection information. During the process towards synchro…
How much geometry it takes to reconstruct a 2-manifold in R 3
2009
Known algorithms for reconstructing a 2-manifold from a point sample in R 3 are naturally based on decisions/predicates that take the geometry of the point sample into account. Facing the always present problem of round-off errors that easily compromise the exactness of those predicate decisions, an exact and robust implementation of these algorithms is far from being trivial and typically requires employment of advanced datatypes for exact arithmetic, as provided by libraries like CORE, LEDA, or GMP. In this article, we present a new reconstruction algorithm, one whose main novelties is to throw away geometry information early on in the reconstruction process and to mainly operate combina…
Soft Pyramid Symmetry Transforms
2005
Pyramid computation is a natural paradigm of computation in planning strategies and multi-resolution image analysis. This paper introduces a new paradigm that is based on the concept of soft-hierarchical operators implemented in a pyramid architecture to retrieve global versus local symmetries. The concept of symmetry is mathematically well defined in geometry whenever patterns are crisp images (two levels). Necessity for a soft approach occurs whenever images are multi-levels and the separation between object and background is subjective or not well defined. The paper describes a new pyramid operator to detect symmetries and shows some experiments supporting the approach. This work has bee…
Statistically validated networks in bipartite complex systems.
2011
Many complex systems present an intrinsic bipartite nature and are often described and modeled in terms of networks [1-5]. Examples include movies and actors [1, 2, 4], authors and scientific papers [6-9], email accounts and emails [10], plants and animals that pollinate them [11, 12]. Bipartite networks are often very heterogeneous in the number of relationships that the elements of one set establish with the elements of the other set. When one constructs a projected network with nodes from only one set, the system heterogeneity makes it very difficult to identify preferential links between the elements. Here we introduce an unsupervised method to statistically validate each link of the pr…