Search results for "Computer vision"
showing 10 items of 2353 documents
An advanced numerical treatment of EM absorption in human tissue
2020
The numerical computation of local electromagnetic absorption at points within the human tissue is proposed by avoiding the mesh generation in the problem domain. Recently, meshless numerical methods have been introduced as an alter- native computational approach to mesh based methods. This is an important feature to generate competitive procedure able to provide final evaluations for large data amounts in real time. In this paper the smoothed particle hydrodynamics method is considered to compute the electromagnetic absorption. First experiments are performed in two dimension at single frequencies by considering incident TM plane wave on 2D cylinder simulating a simplified model of human t…
Computation of the field diffracted by a local surface defect: application to tip–sample interaction in the photon scanning tunneling microscope
1996
We use a method based on the Fourier transform of the electromagnetic field to compute the field diffracted by a local deformation of a plane boundary surface. We give a complete development of each step of the technique. To show the interaction that exists between the probe of a near-field optical microscope and the observed sample, we use the model of a truncated cone-shaped tip above a rectangular surface defect. We compute the electrical intensity along a line located between the tip and the local surface defect. We show the influence of the polarization of the incident wave and the effect of the position of the tip with respect to the position of the surface defect.
On the repeatability of the EMI for the monitoring of bonded joints
2015
We study the feasibility and the repeatability of the electromechanical impedance (EMI) method for the health monitoring of lightweight bonded joints. The EMI technique exploits the coupling between the displacement field and the potential field of a piezoelectric material, by attaching or embedding a piezoelectric transducer to the structure to be monitored. The sensor is excited by an external voltage and the electrical admittance which is the ratio between the electric current and the applied voltage is measured as it depends on the mechanical coupling between the transducer and the host structure. Owing to this interaction, the admittance may represent a signature for the health of the …
Emotions in a cognitive architecture for human robot interactions
2004
A robot architecture is proposed in which cognitive models of emotions are modelled in terms of conceptual spaces. The architecture has been implemented in a anthropomorphic robotic hand system. Experimental results are described related to an experimental setup in which the robot system plays Rock Paper Scissor against a human opponent Copyright © 2004, American Association for Artificial Intelligence (www.aaai.org).
Boosting Hankel matrices for face emotion recognition and pain detection
2017
HighligthsDynamics of face expression descriptors are modeled for emotion recognition.A set of Hankel matrices is built upon several multi-scale face representations.Boosting and random subspace projection are used for dynamics selection.Dynamics of Haar-like features and Gabor Energies are compared.Fine-grained dynamics of subtle expressions can be modeled at small spatial scales. Studies in psychology have shown that the dynamics of emotional expressions play an important role in face emotion recognition in humans. Motivated by these studies, in this paper the dynamics of face expressions are modeled and used for automatic emotion recognition and pain detection.Given a temporal sequence o…
The exploratory factor analysis of items: guided analysis based on empirical data and software
2017
El objetivo del presente trabajo es ilustrar cómo la aplicación adecuada o inadecuada del análisis factorial exploratorio (AFE) puede llevar a conclusiones muy diferentes. Para ello se evalúa el grado en que cuatro paquetes estadísticos diferentes que permiten realizar AFE de ítems, en concreto SPSS, FACTOR, PRELIS y MPlus, permiten o limitan la aplica- ción de los estándares actualmente recomendados en materia de análisis factorial. Asimismo se analizan y comparan los resultados que ofrecen di- chos programas cuando se factorizan datos empíricos de escalas que ajus- tan, según el caso, de manera inadecuada, ambigua u óptima a los supuestos del modelo AFE lineal clásico, a través de las dis…
Segmentation and Navigation Support of Clinical Data Sets to Simulate the Bronchoscopy and Rhinoscopy
2007
A training and simulation system for therapy planning is developed based on patient specific imaging data. A real endoscope is used for navigation through the virtual patient. For this purpose sensors were built in the endoscope in order to track the translation, rotation and the angle of the distal end. Pre-processing (segmentation, tissue characterization) speeds-up the volume rendering up to real-time. Collision detection enables a realistic fly through the virtual patient.
Endoscopic surgery of the rhinobasis with a computer-assisted localizer
1996
The endoscope is useful for the diagnosis and surgical therapy of diseases of the nose, the paranasal sinuses and its neighboring regions, and allows for microinvasive, functional approaches. The reduced invasiveness of therapeutic procedures is sometimes accompanied by insufficient clearness of the surgical field, however. This significant problem is solved by the computer-assisted-surgery (CAS) system, an intraoperative localizer. It allows continuous orientation based on three-dimensional reconstructed preoperative CT scans with superimposed positioning of the endoscope. We have now adapted CAS for endoscopic sinus surgery, which meant that a variety of visualization methods were tested.…
High-Definition Imaging in Spinal Neuroendoscopy
2010
BACKGROUND Spinal endoscopy is still under controversial discussion. An often acclaimed critic is the poor endoscopic image quality in comparison with the microscope. Since high-definition digital cameras have recently been introduced into spinal neuroendoscopy, the aim of the current study is to examine whether superior image quality has a relevant impact on intraoperativen orientation. MATERIAL AND METHODS A lumbar endoscopic discectomy was recorded simultaneously in High-Definition resolution (HD) and Standard-Definition resolution (SD). 10 experienced spinal surgeons were asked to identify predefined as well as not predefined anatomic structures in HD and SD resolution. Additionally, th…
Numerical Simulations of the Hydrodynamics of the Abdominal Aorta Aneurysm (AAA) Using a Smoothed Particle Hydrodynamics Code with Deformable Wall Pr…
2018
We present some preliminary results of the numerical simulations of the hydrodynamic characteristics of an abdominal aorta aneurysm (AAA) patient specific test case. Images of the AAA lumen have been acquired in 10 discrete time-steps through a stabilized cardiac cycle by electrocardiogram-gated computer tomography angiography, and are used to approximate the in vivo, time dependent kinematic fields of the (internal) arterial wall. The flow field is simulated by a Smoothed Particle SPH numerical model, where the kinematics of the boundary of the computational domain (the internal aortic vessel) is the one computed by the above procedure. The outputs of the SPH model, i.e., pressure and flow…