Search results for "Linear"
showing 10 items of 7165 documents
Effective and Efficient Interpolation for Mutual Information based Multimodality Elastic Image Registration
2009
Mutual information (MI) is a popular similarity metric for multimodality image registration purpose. However, it is negatively influenced by artifacts due to interpolation effects. As a result, registration algorithms performance could be affected. In this paper a novel interpolation scheme is presented. It is both effective and efficient. Effective because it limits the presence of local maxima in the mutual information curve, efficient because it is simple to compute being based on simple and optimized distance measures. The method is validated and compared against other techniques both from performance and time complexity persepectives. Differently from other reference works, which perfo…
An FPGA Implementation of a Quadruple-Based Multiplier for 4D Clifford Algebra
2008
Geometric or Clifford algebra is an interesting paradigm for geometric modeling in fields as computer graphics, machine vision and robotics. In these areas the research effort is actually aimed at finding an efficient implementation of geometric algebra. The best way to exploit the symbolic computing power of geometric algebra is to support its data types and operators directly in hardware. However the natural representation of the algebra elements as variable-length objects causes some problems in the case of a hardware implementation. This paper proposes a 4D Clifford algebra in which the variable-length elements are mapped into fixed-length elements (quadruples). This choice leads to a s…
Normalised compression distance and evolutionary distance of genomic sequences: comparison of clustering results
2009
Genomic sequences are usually compared using evolutionary distance, a procedure that implies the alignment of the sequences. Alignment of long sequences is a time consuming procedure and the obtained dissimilarity results is not a metric. Recently, the normalised compression distance was introduced as a method to calculate the distance between two generic digital objects and it seems a suitable way to compare genomic strings. In this paper, the clustering and the non-linear mapping obtained using the evolutionary distance and the compression distance are compared, in order to understand if the two distances sets are similar.
Assessment of Cardiorespiratory Interactions During Spontaneous and Controlled Breathing: Non-linear Model-free Analysis
2022
In this work, nonlinear model-free methods for bivariate time series analysis have been applied to study cardiorespiratory interactions. Specifically, entropy-based (i.e. Transfer Entropy and Cross Entropy) and Convergent Cross Mapping asymmetric coupling measures have been computed on heart rate and breathing time series extracted from electrocardiographic (ECG) and respiratory signals acquired on 19 young healthy subjects during an experimental protocol including spontaneous and controlled breathing conditions. Results evidence a bidirectional nature of cardiorespiratory interactions, and highlight clear similarities and differences among the three considered measures.
Memoria, disinganno, composizione: Goethe, Kniep e la funzione del disegno durante il viaggio in Sicilia
2018
This article focuses on Goethe’s specific concept of drawing as it appears to the reader through the pages of his Italian journey. A fundamental role is played in this discourse by Christoph Heinrich Kniep, a young German draughtsman who has been recommended to Goethe by his friend, the painter Tischbein, and who accompanied the poet during his trip to Sicily. The key function of Kniep’s linear drawings was to create a visual archive destined to keep memory of his experience for future times, free from picturesque effects and potentially capable to force the recipient’s imagination. The relationship between the two travellers turned into a kind of creative symbiosis as can be seen from Goet…
Glossing the Old Frisian Psalter: Pragmatics and Competence
2014
The essay takes into examination the interlinear glosses in Old Frisian in the fragment of Psalter in ms. Groningen, Universiteitsbibliotheek 404. This is the oldest medieval Frisian fragmentary codex to survive and contains verses of Psalms XVII, XXVII, and XVIII, accompanied by glosses in the vernacular. This essay is the first lengthy study specifically devoted to the typology of the glosses themselves and their peculiarities (within the field of interlinear glosses). On close inspection, the OF glosses show a large internal coherence and individual quality. As far as the lexicon is concerned, the glosses feature a series of words belonging to the juridical lexicon, whereas other word-ch…
MR3038546, Brešar, Matej; Klep, Igor A local-global principle for linear dependence of noncommutative polynomials. Israel J. Math. 193 (2013), no. 1,…
2014
Let F be a eld of characteristic zero and FhXi the free associative algebra on X = fX1;X2; : : : g over F; i.e., the algebra of polynomials in the non-commuting variables Xi 2 X. A set of polynomials in FhXi is called locally linearly dependent if their evaluations at tuples of matrices are always linearly dependent. In [Integral Equations Operator Theory 46 (2003), no. 4, 399{454; MR1997979 (2004f:90102)], J. F. Camino et al., in the setting of free analysis, motivated by systems engineering, proved that a nite locally linearly dependent set of polynomials is linearly dependent. In this paper the authors give an alternative algebraic proof of this result based on the theory of polynomial i…
A counterexample to a conjecture on linear systems on ℙ3
2004
In this paper [1] Ciliberto proposes a conjecture in order to characterize special linear systems of IPn through multiple base points. In this note we give a counterexample to this conjecture by showing that there is a substantial difference between the speciality of linear systems on IP 2 and those of IP3.
Sign-preserving solutions for a class of asymptotically linear systems of second-order ordinary differential equations
2022
We study multiplicity of solutions to an asymptotically linear Dirichlet problem associated with a planar system of second order ordinary differential equations. The existence of two sign-preserving component-wise solutions is guaranteed when the Morse indexes of the linearizations at zero and at infinity do not coincide, and one of the asymptotic problems has zero-index. The proof is developed in the framework of topological and shooting methods and it is based on a detailed analysis and characterization of the phase angles in a two-dimensional setting.
First and second critical exponents for an inhomogeneous Schrödinger equation with combined nonlinearities
2022
AbstractWe study the large-time behavior of solutions for the inhomogeneous nonlinear Schrödinger equation $$\begin{aligned} iu_t+\Delta u=\lambda |u|^p+\mu |\nabla u|^q+w(x),\quad t>0,\, x\in {\mathbb {R}}^N, \end{aligned}$$ i u t + Δ u = λ | u | p + μ | ∇ u | q + w ( x ) , t > 0 , x ∈ R N , where $$N\ge 1$$ N ≥ 1 , $$p,q>1$$ p , q > 1 , $$\lambda ,\mu \in {\mathbb {C}}$$ λ , μ ∈ C , $$\lambda \ne 0$$ λ ≠ 0 , and $$u(0,\cdot ), w\in L^1_{\mathrm{loc}}({\mathbb {R}}^N,{\mathbb {C}})$$ u ( 0 , · ) , w ∈ L loc 1 ( R N , C ) . We consider both the cases where $$\mu =0$$ μ = 0 and $$\mu \ne 0$$ μ ≠ 0 , respectively. We establish existence/nonexistence of global weak solutions. In ea…