Energy-Entropy-Momentum integration of discrete thermo-visco-elastic dynamics.

A novel time integration scheme is presented for the numerical solution of the dynamics of discrete systems consisting of point masses and thermo-visco-elastic springs. Even considering fully coupled constitutive laws for the elements, the obtained solutions strictly preserve the two laws of thermo dynamics and the symmetries of the continuum evolution equations. Moreover, the unconditional control over the energy and the entropy growth have the effect of stabilizing the numerical solution, allowing the use of larger time steps than those suitable for comparable implicit algorithms. Proofs for these claims are provided in the article as well as numerical examples that illustrate the performance of the method

Adding local rotational degrees of freedom to ANC beams

This work shows a simple finite element formulation that enables to impose concentrated moments and rotations to ANC beams which are finite elements that lack rotational degrees of freedom. The idea is based on an specific constraint that expresses in a simple form the relation between the deformation of the beam and the rotation of any of its sections. By controlling this sectional rotation, moments and angles can be easily imposed on any model

Dynamic analysis and control system design of a deployable space robotic manipulator

This thesis presents a dynamic analysis and a control system for a flexible space manipulator, the Deployable Robotic Manipulator or DRM, which has a deployable/retractable link. The link extends (or retracts) from the containing slewing link of the manipulator to change the DRM's length and hence its workspace. This makes the system dynamics time varying and therefore any control strategy has to adapt to this fact. The aim of the control system developed is to slew the manipulator through a predetermined angle given a maximum angular acceleration, to reduce flexural vibrations of the manipulator and to have a certain degree of robustness, all of this while carrying a payload and while the length of the manipulator is changing. The control system consists of a slewing motor that rotates the manipulator using the open-loop assumed torque method and two reaction wheel actuators, one at the base and one at the tip of the manipulator, which are driven by a closed-loop damping control law. Two closed-loop control laws are developed, a linear control law and a Lyapunov based control law. The linear control law is based on collocated output feedback. The Lyapunov control law is developed for each of the actuators using Lyapunov stability theory to produce vibration control that can achieve the objectives stated above for different payloads, while the manipulator is rotating and deploying or retracting. The response of the system is investigated by computer simulation for two-dimensional vibrations of the deployable manipulator. Both the linear and Lyapunov based feedback control laws are found to eliminate vibrations for a range of payloads, and to increase the robustness of the slewing mechanism to deal with uncertain payload characteristics

Efficiency in Saving Infant Lives: the Influence of Water and Sanitation Coverage

In this paper, we aim to assess the relationship between water and sanitation coverage and saved infant lives. Our hypothesis is that extended coverage implies measurable results in terms of reduced infant mortality. Moreover, we suspect that with the same resources, ceteris paribus, different countries can achieve better or worst results depending on the efficiency which the resources are used. We explore the policy consequences, simulating the effects that improvements in efficiency can yield in terms of the reduction in child mortality. Our approach is first to explore with a database of Latin American countries the "production function" of survivor infants on 1,000 births. Once we identify the causal relationship with an econometric model, we estimate a production frontier with Data Envelopment Analysis in order to determine the best performers: countries which can do better with the same "inputs". Finally, we simulate the consequence of catching up to the frontier in each country. The impressive quantitative results are interesting for policy concerns, since efficiency is reconciled with equity (in the sense that the winners of the coverage increases and the health improvements are the poorer).water; sanitation; health

Optomechanics assisted with a qubit: From dissipative state preparation to many-body physics

We propose and analyze nonlinear optomechanical protocols that can be implemented by adding a single atom to an optomechanical cavity. In particular, we show how to engineer the environment in order to dissipatively prepare the mechanical oscillator in a superposition of Fock states with fidelity close to one. Furthermore, we discuss how a single atom in a cavity with several mechanical oscillators can be exploited to realize nonlinear many-body physics by stroboscopically driving the mechanical oscillators. We show how to prepare non-classical many-body states by either applying coherent protocols or engineering dissipation. The analysis of the protocols is carried out using a perturbation theory for degenerate Liouvillians and numerical tools. Our results apply to other systems where a qubit is coupled to a mechanical oscillator via a bosonic mode, e.g., in cavity quantum electromechanics

Viabilidad y factibilidad para la creación de una granja productora de ovinos en la Guajira

Se muestra el proceso para determinar la viabilidad y factibilidad en la creación de una granja dedicada a la producción de ovinos por medio de un cruzamiento con hembras criollas de la región y machos puros de la raza Katahdin, en un programa de cría, levante y ceba, en el municipio de Maicao en el departamento de la Guajira (Colombia) mediante sistemas de producción semi-intensivo en pastoreo de gramíneas (Andropogon gayanus), forraje de corte de Sorgo forrajero (Sorghum bicolor), Maralfalfa (Pennisetum spp) y leguminosa como la Moringa (moringa oleífera). Para lograr este objetivo, se realizaron procesos correspondientes al análisis técnico, de mercado, legal, ambiental y financiero; lo cual arrojó como resultado principalmente una baja oferta en el mercado local, por lo que se considera una oportunidad de negocio, con una inversión de $107.000.000

Team handball goalkeeper and perceptual skills: kid’s training proposal

El portero es una figura clave en los equipos de balonmano con gran peso en el resultado final, sin embargo su entrenamiento ha sido siempre basado en la intuición y experiencia. Dada las características de sus acciones las habilidades perceptivas tienen especial relevancia, de ahí que en este trabajo se haga una revisión de las habilidades perceptivas más importantes y los estudios aplicados, con objeto de realizar una propuesta de entrenamiento perceptivo.Goalkeepers are crucial in team handball with a great relevance on results, but goalkeeper’s training has been traditionally based on experience and intuition. It’s particular actions needs specially perceptual skills, so this study makes a review of those abilities and their applied studies for making a proposal in perceptual skills training.peerReviewe

Master equation approach to optomechanics with arbitrary dielectrics

We present a master equation describing the interaction of light with dielectric objects of arbitrary sizes and shapes. The quantum motion of the object, the quantum nature of light, as well as scattering processes to all orders in perturbation theory are taken into account. This formalism extends the standard master equation approach to the case where interactions among different modes of the environment are considered. It yields a genuine quantum description, including a renormalization of the couplings and decoherence terms. We apply this approach to analyze cavity cooling of the center-of-mass mode of large spheres. Furthermore, we derive an expression for the steady-state phonon numbers without relying on resolved-sideband or bad-cavity approximations.Comment: 17 pages, 5 figure