Search results for "Algorithm"

Classification of Plant Ecological Units in Heterogeneous Semi-Steppe Rangelands: Performance Assessment of Four Classification Algorithms.

2021

Plant Ecological Unit’s (PEUs) are the abstraction of vegetation communities that occur on a site which similarly respond to management actions and natural disturbances. Identification and monitoring of PEUs in a heterogeneous landscape is the most difficult task in medium resolution satellite images datasets. The main objective of this study is to compare pixel-based classification versus object-based classification for accurately classifying PEUs with four selected different algorithms across heterogeneous rangelands in Central Zagros, Iran. We used images of Landsat-8 OLI that were pan-sharpened to 15 m to classify four PEU classes based on a random dataset collected in the field (40%). …

Unsupervised recognition of retinal vascular junction points.

2014

Landmark points in retinal images can be used to create a graph representation to understand and to diagnose not only different pathologies of the eye, but also a variety of more general diseases. Aim of this paper is the description of a non-supervised methodology to distinguish between bifurcations and crossings of the retinal vessels, which can be used in differentiating between arteries and veins. A thinned representation of the binarized image, is used to identify pixels with three or more neighbors. Junction points are classified into bifurcations or crossovers according to their geometrical and topological properties. The proposed approach is successfully compared with the state-of-t…

Image Compression by 2D Motif Basis

2011

Approaches to image compression and indexing based on extensions to 2D of some of the Lempel-Ziv incremental parsing techniques have been proposed in the recent past. In these approaches, an image is decomposed into a number of patches, consisting each of a square or rectangular solid block. This paper proposes image compression techniques based on patches that are not necessarily solid blocks, but are affected instead by a controlled number of undetermined or don't care pixels. Such patches are chosen from a set of candidate motifs that are extracted in turn from the image 2D motif basis, the latter consisting of a compact set of patterns that result from the autocorrelation of the image w…

Maximum likelihood for target location in the presence of substitutive noise .

2001

We consider the optimal likelihood algorithm for the estimation of a target location when the images are corrupted by substitutive noise. We show the relationship between the optimal algorithm and the sliced orthogonal nonlinear generalized (SONG) correlation. The SONG correlation is based on the application of a linear correlation to corresponding binary slices of both the input scene and the reference object with appropriate weight factors. For a particular case, we show that the optimal strategy is a function of only the number of pixels for which the gray values in the noisy image match the ones of the reference image when the substitutive noise is uniformly distributed. This is exactly…

A low-level spectrometer with a planar low-energy HPGe: shielding arrangement tests and system performance for 210Pb determination in air filter samp…

2001

A system for low-energy photon spectrometry using a planar germanium detector with appropriate specifications is presented. A spectrometric background investigation has been carried out with various detector shielding arrangements. The characteristics of the system for measurements of 210Pb in air-particulate matter on filters have been determined.

Conductivity imaging with interior potential measurements

2011

In this article, we present two reconstruction methods intended to be used for conductivity imaging with data obtained from a planar electrical impedance tomography device for breast cancer detection. The inverse problem to solve is different from the classical inverse conductivity problem. We reconstruct the electrical conductivity of a two-dimensional domain from boundary measurements of currents and interior measurements of the potential. One reconstruction algorithm is based on a discrete resistor model; the other one is an integral equation approach for smooth conductivity distributions.

The geography of hybrid speciation in plants

2015

The effect of Quaternary climatic changes on plant distribution and evolution

1998

Abstract Climatic oscillations in the Quaternary have played a major role in changing the geographical distribution of plant species. Recent molecular work has provided new insights into the location of glacial refugia and routes of postglacial expansion. A comparative analysis shows that phylogeographic patterns in Europe appear to be less congruent than in North America. The change of geographical distribution has also provided opportunities for speciation through isolation, and hybridization after secondary contact. However, a complete understanding of the significance of the Quaternary climatic changes for plant speciation requires further research into the estimation of reliable and ac…

Large-Eddy Simulation of Flow and Heat Transfer in Compact Heat Exchangers

1994

LES results are presented for different heat exchanger geometries. Subgrid terms were usually computed by the Smagorinsky model; preliminary comparative results are also given for the ‘dynamic’ subgrid model. The numerical methods used were those implemented in a commercial general-purpose code (CFDS-FLOW3D); they included a finite-volume approach, colocated body-fitted grids, central differencing for the advection terms, the SIMPLEC algorithm, and Crank-Nicolson time stepping. Predictions arc compared with experimental measurements (including local Nu distributions), and with results from a low-Reynolds number k-e model. In most cases, LES was more ‘robust’ and required little more CPU tim…

TRIC: an automated alignment strategy for reproducible protein quantification in targeted proteomics

2016

Nature Methods, 13 (9)