Search results for "Geometry"

Helicoid and Architectural application

2012

Questo articolo è un risultato parziale di una ricerca riguardante la rappresentazione di superfici complesse in geometria descrittiva. La padronanza e l’abilità nell’uso delle diverse tecniche di rappresentazione, consente di raggiungere risultati che altrimenti non sarebbero perseguibili. La Scuola di Disegno di Ingegneria, dell’Università di Palermo si è da sempre fatta promotrice della scienza della rappresentazione attraverso la sperimentazione di tecniche semplificative ed innovative della geometria descrittiva applicata all’architettura e all’ingegneria. In particolar modo, in questo lavoro, si riporta lo studio di una superficie complessa quale è l’elicoide che trova larga applicazi…

An efficient grid-based RF fingerprint positioning algorithm for user location estimation in heterogeneous small cell networks

2014

This paper proposes a novel technique to enhance the performance of grid-based Radio Frequency (RF) fingerprint position estimation framework. First enhancement is an introduction of two overlapping grids of training signatures. As the second enhancement, the location of the testing signature is estimated to be a weighted geometric center of a set of nearest grid units whereas in a traditional grid-based RF fingerprinting only the center point of the nearest grid unit is used for determining the user location. By using the weighting-based location estimation, the accuracy of the location estimation can be improved. The performance evaluation of the enhanced RF fingerprinting algorithm was c…

homogeneous embeddings of SL2(C) modulo a finite sub-group.

2000

L'objet de ce travail est l'étude des variétés algébriques normales complexes munies d'une action algébrique de $SL_{2}$ et qui contiennent $SL_{2}/H$ comme orbite ouverte, $H$ étant un sous-groupe fini de $SL_{2}$.Plus précisément on définit un plongement homogène de $SL_{2}/H$ comme la donnée d'une $SL_{2}$-variété irréductible $X$ (quasi-projective ou non) contenant $SL_{2}/H$ comme orbite ouverte et d'un morphisme $SL_{2}$-équivariant de $SL_{2}$ dans $X$.Les plongements homogènes lisses ainsi que les plongements minimaux (plongements lisses et complets qui ne sont pas des éclatements d'un autre plongement lisse complet) de $SL_{2}/\{Id\}$ et de $SL_{2}/\{\pm Id\}$ ont été déterminés pa…

Etude de certaines familles de variétés algébriques munies d'une action de groupe algébrique

2021

Time Unification on Local Binary Patterns Three Orthogonal Planes for Facial Expression Recognition

2019

International audience; Machine learning has known a tremendous growth within the last years, and lately, thanks to that, some computer vision algorithms started to access what is difficult or even impossible to perceive by the human eye. While deep learning based computer vision algorithms have made themselves more and more present in the recent years, more classical feature extraction methods, such as the ones based on Local Binary Patterns (LBP), still present a non negligible interest, especially when dealing with small datasets. Furthermore, this operator has proven to be quite useful for facial emotions and human gestures recognition in general. Micro-Expression (ME) classification is…

Anterolateral thigh perforator flap made by customized 3D-printing fabrication of fixed positioning guide for oromaxillofacial reconstruction:a preli…

2022

Oromaxillofacial carcinomas frequently result in serious tissue defect due to enlarged resection for treating their extensive invasion, which require challenging reconstruction. Three-dimensional (3D) printing is an advanced technology which has greatly promoted the progress of craniomaxillofacial reconstructive surgery. This present study aimed to investigate the advantages of anterolateral thigh (ALT) perforator flap manufactured by 3D printing fixed positioning guide template in curing oromaxillofacial defect. Twenty patients with oromaxillofacial defects resulted from severe primary malignant tumors were divided into experimental group assisted by digital technique (n=8) and controlled …

On the History of Differentiable Manifolds

2012

International audience; We discuss central aspects of history of the concept of an affine dif-ferentiable manifold, as a proposal confirming the need for using some quantitative methods (drawn from elementary Model Theory) in Mathematical Historiography. In particular, we prove that this geometric structure is a syntactic rigid designator in the sense of Kripke-Putnam.

Sentience and the Origins of Consciousness: From Cartesian Duality to Markovian Monism

2020

This essay addresses Cartesian duality and how its implicit dialectic might be repaired using physics and information theory. Our agenda is to describe a key distinction in the physical sciences that may provide a foundation for the distinction between mind and matter, and between sentient and intentional systems. From this perspective, it becomes tenable to talk about the physics of sentience and &lsquo

Equilibrium and structural studies of complexes with a hexadentate ligand containing amide, amine and pyridyl nitrogen donors. Crystal structures of …

2002

A novel potentially hexadentate ligand, 1,8-bis(2-pyridylcarbamoyl)-3,6-diazaoctane (pyctrien) has been synthesised as its tetrahydrochloride salt; its protonation constants and the stability constants of the copper(II) and nickel(II) chelates have been determined by potentiometry. Amide group deprotonation permits the formation of [MLH−1]+ and [MLH−2] species in all cases, whereas the detection of the neutral or the protonated species depends on the nature of the metal ions. The solid complexes of copper, nickel and cobalt with the neutral and the deprotonated ligand have been synthesised and characterised by IR and UV–VIS spectroscopy. The amidic groups are coordinated through the oxygen …

Monoamide Derivatives of EDTA Incorporating Pendent Carboxylates or Pyridyls: Synthesis, Metal Binding, and Crystal Structure of a Dinuclear Ca2+ Com…

2017

EDTA is a powerful, cheap and widely-used chelating unit for a large range of metal ions. To link it covalently to other molecules, the formation of an amide bond using one of the carboxylates is an attractive and simple approach, even though it may compromise metal ion binding as one of the four carboxylate donors is lost. Here we undertake a quantitative study of the metal ion binding of two new mono-amide derivatives of EDTA, namely AmGly1 and AmPy1, featuring an additional coordinating carboxylate or pyridyl group in the amide, respectively. The compounds are conveniently synthesised through alkylation of the tris-t-butyl ester of ethylenediamine-triacetic acid with the appropriate α-ch…