Search results for "Vector"
showing 10 items of 2660 documents
Real-time Sub-pixel Cross Bar Position Metrology
2002
Many measurement application fields need to calculate cross bar intersection locations of horizontal and vertical bars. The system we developed and that we present in this paper is an embedded system that measures cross bar positions with sub-pixel accuracy on 1024×1024 pixel images delivered by a camera at a 50 MHz data rate in real time. This is done using an algorithm that looks for intersection areas and then locally calculates two lines representing horizontal and vertical bars. The two line intersection is considered to be the bar intersection. To achieve real time, we developed a hybrid architecture in which low level processes are implemented into FPGAs and others into DSPs. As a re…
A Comparative Study on Feature Selection for Retinal Vessel Segmentation Using FABC
2009
This paper presents a comparative study on five feature selection heuristics applied to a retinal image database called DRIVE. Features are chosen from a feature vector (encoding local information, but as well information from structures and shapes available in the image) constructed for each pixel in the field of view (FOV) of the image. After selecting the most discriminatory features, an AdaBoost classifier is applied for training. The results of classifications are used to compare the effectiveness of the five feature selection methods.
Human Figure Recognition and the Estimation of its Direction
2006
This work describes a method used to recognize a person situated in indoor environments. It estimates the direction in which the person is turned. The position coordinates are known to the system thanks to localization techniques that use Bluetooth technology. The utilization of such information in intelligent environments allows the execution of actions that interact with the customer. The paper focuses on our human figure recognition technique, which uses image analysis to calculate the direction angle a person is turned towards. Figure recognition is accomplished by comparing the colours of the body parts that mark it out, such as: hair colour, face colour, and clothes colour. The calcul…
Smartphone determination of fat in cured meat products
2017
Abstract A method has been developed to determine the fat content in different cold meat products by image processing using the camera of a mobile phone. Salchichon , chorizo , salami and cured ham pictures were taken with a Meizu M2 Mini mobile phone camera under fixed lighting conditions of the light emitting diode flash of the mobile phone. Images were treated with Matlab to obtain the mean pixels of average red, green and blue camera values colours (RGB) of the pixels and different data pretreatments were taken into account to correlate colour parameters with fat content values determined in a series of commercially available samples by the Soxhlet method. RGB values were used as input …
Plane foliations with a saddle singularity
2012
Abstract We study the set of planar vector fields with a unique singularity of hyperbolic saddle type. We found conditions to assure that a such vector field is topologically equivalent to a linear saddle. Furthermore, we describe the plane foliations associated to these vector fields. Such a foliation can be split in two subfoliations. One without restriction and another one that is topologically characterized by means of trees.
Role of Myzus persicae (Hemiptera: Aphididae) and its secondary hosts in plum pox virus propagation
2007
Plum pox virus (family Potyviridae, genus Potyvirus, PPV) is one of the most important viral pathogens of plants in the genus Prunus, particularly Prunus persica L. The role of the Myzus persicae (Sulzer) (Hemiptera: Aphididae) as a vector of PPV-M, and its role in spreading PPV-M, was investigated. PPV-M-infected peach trees were used as inoculum sources, and transmission to 15 herbaceous species commonly present in and around peach orchards was evaluated. The presence of PPV-M in secondary hosts after aphid transmission was verified by reverse transcription-polymerase chain reaction tests. The results indicate that Saponaria ocymoides L., Pisum sativum L., Trifolium repens L., Trifolium p…
Note: Precise radial distribution of charged particles in a magnetic guiding field.
2015
Current high precision beta decay experiments of polarized neutrons, employing magnetic guiding fields in combination with position sensitive and energy dispersive detectors, resulted in a detailed study of the mono-energetic point spread function (PSF) for a homogeneous magnetic field. A PSF describes the radial probability distribution of mono-energetic electrons at the detector plane emitted from a point-like source. With regard to accuracy considerations, unwanted singularities occur as a function of the radial detector coordinate which have recently been investigated by subdividing the radial coordinate into small bins or employing analytical approximations. In this note, a series expa…
Finite element approximation of vector fields given by curl and divergence
1981
In this paper a finite element approximation scheme for the system curl is considered. The use of pointwise approximation of the boundary condition leads to a nonconforming method. The error estimate is proved and numerically tested.
Determination of strain and stress distribution on shearwalls by using the speckle photography technique
2003
Abstract Speckle photography (SP) is a powerful tool that is adequate to determine small displacements in micrometer range. This information shows other characteristics of structure deformation under loads and can be determined as stress and strain distribution. In this paper we present the results of the application of the SP technique used to study the behaviour of discontinuities in a shearwall model. These structural elements are very important to the stability of buildings. The displacement whole field around the discontinuities and loading points was determined using the pointwise method. This allows us to determine stress distribution at the point of interest by means of the suitable…
σ-Continuous and Co-σ-continuous Maps
2009
In this chapter we isolate the topological setting that is suitable for our study. We first present 2.1–2.3 to follow an understandable logical scheme nevertheless the main contribution are presented in 2.4–2.7 and our main tool will be Theorem 2.32. An important concept will be the σ-continuity of a map Φ from a topological space (X, T) into a metric space (Y, g). The σ-continuity property is an extension of continuity suitable to deal with countable decompositions of the domain space X as well as with pointwise cluster points of sequences of functions Φn : X → Y, n = 1,2,… When (X,T) is a subset of a locally convex linear topological space we shall refine our study to deal with σ-slicely …