Search results for "Similarity"
showing 10 items of 474 documents
Operator (Quasi-)Similarity, Quasi-Hermitian Operators and All that
2016
Motivated by the recent developments of pseudo-Hermitian quantum mechanics, we analyze the structure generated by unbounded metric operators in a Hilbert space. To that effect, we consider the notions of similarity and quasi-similarity between operators and explore to what extent they preserve spectral properties. Then we study quasi-Hermitian operators, bounded or not, that is, operators that are quasisimilar to their adjoint and we discuss their application in pseudo-Hermitian quantum mechanics. Finally, we extend the analysis to operators in a partial inner product space (PIP-space), in particular the scale of Hilbert spaces generated by a single unbounded metric operator.
Soft Topographic Map for Clustering and Classification of Bacteria
2007
In this work a new method for clustering and building a topographic representation of a bacteria taxonomy is presented. The method is based on the analysis of stable parts of the genome, the so-called “housekeeping genes”. The proposed method generates topographic maps of the bacteria taxonomy, where relations among different type strains can be visually inspected and verified. Two well known DNA alignement algorithms are applied to the genomic sequences. Topographic maps are optimized to represent the similarity among the sequences according to their evolutionary distances. The experimental analysis is carried out on 147 type strains of the Gammaprotebacteria class by means of the 16S rRNA…
Generalised stage-discharge relationship for rectangular weirs
2018
Rectangular weirs, which are very common hydraulic structures used in irrigation channels as water measuring devices, can be used for measuring very small discharges as well as high flow rates. From the practical point of view the availability of a unique stage-discharge formula that can be applied for the different types of the rectangular weirs would be of great practical importance. At first, in this paper the Buckingham’s Theorem of the dimensional analysis and the self-similarity theory are used to deduce the stage-discharge curve of different kinds of rectangular weirs such as slit and partially contracted ones. Then the proposed formula is calibrated using both the experimental data …
A new approach for deducing the stage-discharge relationship of triangular in plan sharp-crested weirs
2013
Abstract In this paper, the outflow process of a triangular in plan sharp-crested weir is studied using the dimensional analysis and the incomplete self-similarity theory. The new stage-discharge is theoretically deduced and its testing is carried out using measurements available in literature.
A method for quantifying atrial fibrillation organization based on wave-morphology similarity
2002
A new method for quantifying the organization of single bipolar electrograms recorded in the human atria during atrial fibrillation (AF) is presented. The algorithm relies on the comparison between pairs of local activation waves (LAWs) to estimate their morphological similarity, and returns a regularity index (/spl rho/) which measures the extent of repetitiveness over time of the detected activations. The database consisted of endocardial data from a multipolar basket catheter during AF and intraatrial recordings during atrial flutter. The index showed maximum regularity (/spl rho/=1) for all atrial flutter episodes and decreased significantly when increasing AF complexity as defined by W…
Improving similarity measures for re-identification of vehicles using AMR sensors
2013
The use of Anisotropic Magneto-Resistive (AMR) sensors for road traffic monitoring has gained popularity in recent years. The Earth magnetic field variations caused by vehicles passing over this kind of sensors can be measured and used for various purposes, including vehicle re-identification at different sensing zones. AMR sensors provide data that allow the calculation of traffic parameters by using simple signal processing techniques. But when vehicle re-identification is the objective, it is not clear which is the best method to compare the signals from different sensors in order to know whether or not they belong to the same vehicle. This paper presents an experimental study with the o…
Generalized singly-implicit Runge-Kutta methods with arbitrary knots
1985
The aim of this paper is to derive Butcher's generalization of singly-implicit methods without restrictions on the knots. Our analysis yields explicit computable expressions for the similarity transformations involved which allow the efficient implementation of the first phase of the method, i.e. the solution of the nonlinear equations. Furthermore, simple formulas for the second phase of the method, i.e. computation of the approximations at the next nodal point, are established. Finally, the matrix which governs the stability of the method is studied.
Views selection for SIFT based object modeling and recognition
2016
In this paper we focus on automatically learning object models in the framework of keypoint based object recognition. The proposed method uses a collection of views of the objects to build the model. For each object the collection is composed of N×M views obtained rotating the object around its vertical and horizontal axis. As keypoint based object recognition using a complete set of views is computationally expensive, we focused on the definition of a selection method that creates, for each object, a subset of the initial views that visually summarize the characteristics of the object and should be suited for recognition. We select the views by determining maxima and minima of a function, …
An enhanced random walk algorithm for delineation of head and neck cancers in PET studies
2017
An algorithm for delineating complex head and neck cancers in positron emission tomography (PET) images is presented in this article. An enhanced random walk (RW) algorithm with automatic seed detection is proposed and used to make the segmentation process feasible in the event of inhomogeneous lesions with bifurcations. In addition, an adaptive probability threshold and a k-means based clustering technique have been integrated in the proposed enhanced RW algorithm. The new threshold is capable of following the intensity changes between adjacent slices along the whole cancer volume, leading to an operator-independent algorithm. Validation experiments were first conducted on phantom studies:…
Anam-Net: Anamorphic Depth Embedding-Based Lightweight CNN for Segmentation of Anomalies in COVID-19 Chest CT Images.
2021
Chest computed tomography (CT) imaging has become indispensable for staging and managing coronavirus disease 2019 (COVID-19), and current evaluation of anomalies/abnormalities associated with COVID-19 has been performed majorly by the visual score. The development of automated methods for quantifying COVID-19 abnormalities in these CT images is invaluable to clinicians. The hallmark of COVID-19 in chest CT images is the presence of ground-glass opacities in the lung region, which are tedious to segment manually. We propose anamorphic depth embedding-based lightweight CNN, called Anam-Net, to segment anomalies in COVID-19 chest CT images. The proposed Anam-Net has 7.8 times fewer parameters …