Synchronizing a modular robot colony for cooperative tasks based on intrainter robot communications

The implementation of robotic cooperative tasks such as pushing an object toward a desired destination or manipulating an object using mobile robots or robotic arms requires motion coordination between the robot colony. When a robot is built by the union of several robots, such as modular robot systems, it is critical to have the complete coordination of each robot configuration within the colony and also overall robot coordination of the colony. The paper presents a demonstration of parallel motion for modular robot configurations through the combination of two types of communications, i.e., Inter-robot and Intra-robot communications. The two types of communications are described and implemented in a real modular robot system. Experiments are executed to show the performance of the robot colony synchronizatio

Hacia la seguridad criptográfica en sistemas DaaS

El nuevo paradigma de computación en la nube posibilita la prestación de servicios por terceros. Entre ellos, se encuentra el de las bases de datos como servicio (DaaS) que permite externalizar la gestión y alojamiento del sistema de gestión de base de datos. Si bien esto puede resultar muy beneficioso (reducción de costes, gestión simplificada, etc.), plantea algunas dificultades respecto a la funcionalidad, el rendimiento y, en especial, la seguridad de dichos servicios. En este trabajo se describen algunas de las propuestas de seguridad en sistemas DaaS existentes y se realiza un análisis de sus características principales, introduciendo un nuevo enfoque basado en tecnologías no exclusivamente relacionales (NoSQL) que presenta ventajas respecto a la escalabilidad y el rendimiento.Investigación parcialmente financiada por el MINECO mediante el proyecto TIN2011-25452

Modelling of Modular Robot Configurations Using Graph Theory

Modular robots are systems that can change its geometry or configuration when connecting more modules or when rearranging them in a different manner to perform a variety of tasks. Graph theory can be used to describe modular robots configurations, hence the possibility to determine the flexibility of the robot to move from one point to another. When the robot’s configurations are represented in a mathematical way, forward kinematics can be obtained

Un análisis estadístico del paisaje de Bousso-Polchinski y otros modelos relacionados

Consideramos diferentes formas de contar estados metaestables en el paisaje de Bousso-Polchinski (BP). La fórmula exacta de contaje permite identificar una incompatibilidad (el "problema-alpha^*") entre la forma usual de contar y el mecanismo KKLT de estabilización. Este problema aparece debido a la falta de un estudio de estabilidad en el modelo BP, como demuestra el hecho de que el paisaje de Einstein-Maxwell multi-esfera, que construimos en detalle en 1+1 dimensiones, no posee tal problema

A modified Schwinger's formula for the Casimir effect

After briefly reviewing how the (proper-time) Schwinger's formula works for computing the Casimir energy in the case of "scalar electrodynamics" where the boundary conditions are dictated by two perfectly conducting parallel plates with separation "a" in the Z-axis, we propose a slightly modification in the previous approach based on an analytical continuation method. As we will see, for the case at hand our formula does not need the use of Poisson summation to get a (renormalized) finite result.Comment: 6 pages, DFTUZ/93/14 (a short version will appear in the Letters in Math. Phys.

A deterministic model for highly contagious diseases: The case of varicella

[EN] The classic nonlinear Kermack-McKendrick model based upon a system of differential equations has been widely applied to model the rise and fall of global pandemic and also seasonal epidemic by introducing a forced harmonic infectivity which would change throughout the year. These methods work well in their respective domains of applicability, and for certain diseases, but they fail when both seasonality and high infectivity are combined. In this paper we consider a Susceptible-Infected-Recovered, or SIR, model with two latent states to model the propagation and evolutionary history of varicella in humans. We show that infectivity can be calculated from real data and we find a nonstandard seasonal variation that cannot be fitted with a single harmonic. Moreover, we show that infectivity for the present strains of the virus has raised following a sigmoid function in a period of several centuries. This could allow the design of vaccination strategies and the study of the epidemiology of varicella and herpes zoster. (C) 2016 Elsevier B.V. All rights reserved.Acedo Rodríguez, L.; Moraño Fernández, JA.; Santonja, F.; Villanueva Micó, RJ. (2016). A deterministic model for highly contagious diseases: The case of varicella. Physica A: Statistical Mechanics and its Applications. 450:278-286. doi:10.1016/j.physa.2015.12.153S27828645

A modular robot system design and control motion modes for locomotion and manipulation tasks

This paper describes a modular robot system design SMART, based on three types of modules for urban search tasks. The system attempts to give a quick solution to natural and man-made disaster emergencies. It allows for rapid and cost-effective design and fabrication. The approach is based on the use of an inventory of three types of modules i.e., power and control module, joint module, and specialized module. They are interchangeable in different ways to form different robot configurations for a variety of tasks. Forward and inverse kinematics from assembled robot configurations are analyzed. Description of control motion modes for human-modular robot system interaction is presente

“External and total hip rotation range of motion predispose to low back pain in elite Spanish inline hockey player”

Low back pain (LBP) is a common ailment in competitive athletes. Although the association between limited range of motion (ROM) and prevalence of LBP has been widely investigated in other sports, there is no research about this topic in inline hockey (IH). The main purposes of this study in IH players were (1) to analyze the association between hip ROM and LBP and (2) to establish a diagnostic cuto for ROM of high risk of LBP. Twenty elite IH players from the two Spanish National Teams (male and female) were assessed for passive maximum hip ROMs; the movement evaluated were the hip external [HER] and internal [HIR] rotation, hip flexion with flexed [HF-KF] and extended [HF-KE] knee, hip adduction with flexed hip [HAD-HF], hip abduction with neutral [HAB] and flexed [HAB-HF] hip, and hip extension [HE]. LBP was retrospectively monitored for the last 12 months before the date of ROM assessment by using a questionnaire. The data were analyzed via a binary logistic regression and receiver operating characteristic curves. The 70% of players had developed LBP during the retrospective study period. Significant dierences between LBP group and asymptomatic group for HER (p = 0.013, d [Cohen’s eect size] = 1.17) and hip total rotation [HTR] (p = 0.032, d [Cohen’s eect size] = 1.05) were observed. The cuto points with the greatest discriminatory capacity were 56.5 for HER and 93 for HTR ROMs

Multiverso

El Universo que observamos presenta una serie de problemas que el modelo del Big Bang no es capaz de explicar, por ello a lo largo de los años 70 aparecen distintas teorías que intentan solucionar estos problemas. En primer lugar se desarrollan cuales son estos problemas y cómo las teorías inflacionarias los resuelven, para a continuación presentar la teoría que parecer resolverlos al fin: la inflación caótica eterna, y que da lugar a un escenario con un gran número universos formando el llamado multiverso. En la segunda parte se procede a caracterizar el multiverso abordando el problema de la constante cosmológica mediante tres componentes, un landscape de vacíos, un mecanismo para poblarlos y un criterio de selección. Además se profundiza en la taxonomía del multiverso de Tegmark y se compara el multiverso desarrollado con las ideas de los "muchos mundos" de Hugh Everett

Topological charges and the genus of surfaces

We show that the topological charge of the n-soliton solution of the sine-Gordon equation n is related to the genus g > 1 of a constant negative curvature compact surface described by this configuration. The relation is n=2(g-1), where n is even. The moduli space of complex dimension B(g)=3(g-1) corresponds precisely to the freedom to choosing the configuration with n solitons of arbitrary positions and velocities. We speculate also that the odd soliton states will describe the unoriented surfaces.Comment: 8 pages, Latex. To be published in Journal of Geommetry and Physic