An efficient algorithm to generate large random uncorrelated Euclidean distances: the random link model

A disordered medium is often constructed by $N$ points independently and identically distributed in a $d$-dimensional hyperspace. Characteristics related to the statistics of this system is known as the random point problem. As $d \to \infty$, the distances between two points become independent random variables, leading to its mean field description: the random link model. While the numerical treatment of large random point problems pose no major difficulty, the same is not true for large random link systems due to Euclidean restrictions. Exploring the deterministic nature of the congruential pseudo-random number generators, we present techniques which allow the consideration of models with memory consumption of order O(N), instead of $O(N^2)$ in a naive implementation but with the same time dependence $O(N^2)$.Comment: 8 pages, 2 figures and 1 tabl

Acoustic event characterization for service robot using convolutional networks

This paper presents and discusses the creation of a sound event classification model using deep learning. In the design of service robots, it is necessary to include routines that improve the response of both the robot and the human being throughout the interaction. These types of tasks are critical when the robot is taking care of children, the elderly, or people in vulnerable situations. Certain dangerous situations are difficult to identify and assess by an autonomous system, and yet, the life of the users may depend on these robots. Acoustic signals correspond to events that can be detected at a great distance, are usually present in risky situations, and can be continuously sensed without incurring privacy risks. For the creation of the model, a customized database is structured with seven categories that allow to categorize a problem, and eventually allow the robot to provide the necessary help. These audio signals are processed to produce graphical representations consistent with human acoustic identification. These images are then used to train three convolutional models identified as high-performing in this type of problem. The three models are evaluated with specific metrics to identify the best-performing model. Finally, the results of this evaluation are discussed and analyzed

Orbit determination and control for the European Student Moon Orbiter

This paper presents the preliminary navigation and orbit determination analyses for the European Student Moon Orbiter. The severe constraint on the total mission Delta nu and the all-day piggy-back launch requirement imposed by the limited available budget, led to the choice of using a low-energy transfer, more specifically a Weak Stability Boundary one, with a capture into an elliptic orbit around the Moon. A particular navigation strategy was devised to ensure capture and fulfil the requirement for the uncontrolled orbit stability at the Moon. This paper presents a simulation of the orbit determination process, based on an extended Kalman filter, and the navigation strategy applied to the baseline transfer of the 2011-2012 window. The navigation strategy optimally allocates multiple Trajectory Correction Manoeuvres to target a so-called capture corridor. The capture corridor is defined, at each point along the transfer, by back-propagating the set of perturbed states at the Moon that provides an acceptable lifetime of the lunar orbit. (C) 2012 Elsevier Ltd. All rights reserved

Águilas y jaguares. Testimonios de la formación educativa de los antiguos nahuas

¿Cuáles fueron los orígenes de la educación en México? ¿Qué características tuvo la educación practicada por el Estado más poderoso al arribo de los europeos a estas tierras? ¿Qué objetivos perseguía dicha formación? Este tipo de preguntas consideramos que pueden responderse de mejor forma mediante la presentación de los principales textos del siglo XVI que describen la enseñanza y el adiestramiento de los jóvenes mexicas. Los códices Mendoza y Florentino, además de ofrecernos un inmejorable testimonio, ostentan interesantes imágenes donde se manifiesta el trabajo de los tlacuilos de los primeros años posteriores a la Conquista Militar de México-Tenochtitlán y son, por tanto, al mismo tiempo una invaluable muestra del sincretismo de dos culturas visuales o dos maneras de comunicar con las imágenes. Por otra parte, podemos adelantar desde ahora que la educación de los antiguos nahuas se caracterizó por una férrea disciplina, que les permitía formar física y mentalmente a los niños y jóvenes, el fomento del trabajo comunal y la firme vinculación de estos aspectos con lo sagrado y el funcionamiento propio del universo