Publications

HoloEasy, A Web Application for Computer Generated Holograms

If the appropriate phase and/or amplitude profile is placed on a Diffractive Optical Element (DOE) it can practically generate an image of an object (hologram) by diffraction of the light. The problem of generating computer holograms consists of calculating...

On the existence of conformal Killing vectors for ST-homogeneous Godel type space-times

Tsamparlis et al. [3] have developed a systematic method for computing of the conformal algebra of 1+3 space-times. The proper CKV’s are

A proposed method to validate anomalies detected with unsupervised models

This paper introduces a methodology aimed at validating anomalies identified through unsupervised techniques. Our approach is grounded in the assumption that machine learning models perform optimally when trained on data free of anomalies. Therefore, to assess the veracity of anomalies pinpointed by an unsupervised method, we undertake a two-fold process. Initially, anomalies are removed from the training dataset. Subsequently, we gauge the expected enhancement in the performance of classification models. To evaluate the effectiveness of our methodology, we employed three well-established unsupervised anomaly detection techniques: Local Outlier Factor (LOF), Isolation Forest (iForest), and Autoencoders. These methods were complemented by a voting system designed to identify anomalous data records. The reliability of these detected anomalies was rigorously tested using various classification models, including K-Nearest Neighbors, Logistic Regression, Decision Tree, Random Forest, AdaBoost, and Support Vector Classifier (SVC). This evaluation was conducted both before and after the removal of anomalies from the training dataset. Our methodology underwent rigorous testing across five distinct datasets: Breast Cancer, German Credit, Diabetes, Heart Failure Disease, and Titanic Survivor. The results provide evidence of its effectiveness, with notable improvements observed in the classification performance across four of the five datasets.

Modeling of dynamic mass coupled system with Runge-Kutta fourth order

This paper shows the mathematical modeling process of a mechanical system of masses coupled by two springs and a shock absorber. The process of capture of movement of the mass system coupled with springs was done with software Tracker video analysis and modeling tool. The motion capture of the coupled masses A and B was made with a duration of 20 seconds. A comparison of the results of the movement of the two masses will be established as a first instance, by adjusting trajectories of curves in time using Matlab software and as a second instance a numerical solution of the Mass-Spring model will be established using the Runge Kutta method of 4 order. With this last method, it is expected to achieve a better precision modeling of the initial value problem. Finally, a comparison of the two mathematical models will be made analyzing.

Effect of Preprocessing in Deep Learning Systems to Aid the Diagnosis Using X-Ray Pulmonary Images

The main objective of this research is to analyze the effect of applying some image preprocessing techniques on the performance of convolutional neural networks for the classification of COVID19, Pneumonia, and Normal patients from chest X-ray images. The normal...

Constants of motion of geodesics equations. Examples

Particular examples of constants of motion associated with non-Noetherian symmetries are found for pp-waves, Gödel cosmological solution and Kimura me

Diffuser in Fractional Fourier Optics

We propose a method for calculating a bandlimited diffuser with smooth spectrum in the Fresnel domain without any 2π phase ambiguities using the fractional Fourier transform. Such diffusers are necessary to avoid problems of speckles.

Higiene del odontólogo.

Exposicion de algunas reglas higienicas que son esenciales para el equilibrio fisico y mental del odontologo. Son reglas referidas a la higiene mental, general, del estomago, de los ojos, de las manos, de los pies, de los pulmones y del aparato respiratorio.

A radiating charge embedded in a De Sitter universe

An exact solution of the Einstein-Maxwell theory is presented. The solution represents the metric of a radiating charged particle embedded in a de Sitter universe.

Deep-learning enabled single-shot 3D feature detection in fringe projection profilometry

Reliably detecting or tracking 3D features is challenging. It often requires preprocessing and filtering stages, along with fine-tuned heuristics for reliable detection. Alternatively, artificial intelligence-based strategies have recently been proposed; however, these typically require many manually labeled images for training. We introduce a method for 3D feature detection by using a convolutional neural network and a single 3D image obtained by fringe projection profilometry. We cast the problem of 3D feature detection as an unsupervised detection problem. Hence, the goal is to use a neural network that learns to detect specific features in 3D images using a single unlabeled image. Therefore, we implemented a deep-learning method that exploits inherent symmetries to detect objects with few training data and without ground truth. Subsequently, using a pyramid methodology of rescaling each image to be processed, we achieved feature detections of different sizes. Finally, we unified the detections using a non-maximum suppression algorithm. Preliminary results show that the method provides reliable detection under different scenarios with a more flexible training procedure than other competing methods.

A low noise stenography method for medical images with QR encoding of patient information

This paper proposes an approach to facilitate the process of individualization of patients from their medical images, without compromising the inherent confidentiality of medical data. The identification of a patient from a medical image is not often the goal of security methods applied to image records. Usually, any identification data is removed from shared records, and security features are applied to determine ownership. We propose a method for embedding a QR-code containing information that can be used to individualize a patient. This is done so that the image to be shared does not differ significantly from the original image. The QR-code is distributed in the image by changing several pixels according to a threshold value based on the average value of adjacent pixels surrounding the point of interest. The results show that the code can be embedded and later fully recovered with minimal changes in the UIQI index - less than 0.1% of different.

On the Constants of Motion for the Time-Dependent Oscillator

We apply recent results on symmetries of equations of motion and equivalent Lagrangians in order to obtain the constants of motion and auxiliary conditions for the time-dependent oscillator.

Irradiation of accretion disks around young objects. Ii. Continuum energy distribution

Evolution of radiating charged spheres in general relativity

A method reported by Herrera et al. is extended to study radiating, charged, fluid spheres. A heuristic assumption relating pressure, energy density, the radial velocity of matter, and the electric-charge distribution is introduced. This ansatz, together with matching the boundaries with those of the Reissner–Nordstrom–Vaidya solution, leads to a system of ordinary differential equations for quantities evaluated at the surface. The integration allows one to obtain the profile of the physical variables for any piece of material via the Einstein–Maxwell equations. As an example of the procedure, a particular model is worked out in some detail.

Color segmentation to measure the percentage of the affected area in leaves with signs of chlorosis

No abstract is provided for this article.

Symmetries and conserved quantities in geodesic motion

Recently obtained results linking several constants of motion to one (non-Noetherian) symmetry to the problem of geodesic motion in Riemannian space-times are applied. The construction of conserved quantities in geodesic motion as well as the deduction of geometrical statements about Riemannian space-times are achieved.

Irradiation of accretion disks around young objects. Ii. Continuum energy distribution

No abstract is provided for this article.

Exploring Brain Network Changes During Mental Arithmetic Task With Minimum Spanning Tree

Electroencephalography (EEG) is a non-invasive and cost-effective method for studying the complexity of brain dynamics. In this study, we constructed Minimum Sp