War reporting from afar: covering the covert drone war

This post is by Polis Summer School Student Carmen Zheng Prior to the 1990-91 Gulf War, a journalist coined the term The Powell Doctrine, named after then Joint Chiefs of Staff Colin Powell. Vowing to utilize every resource and tool available against the enemy to minimize United States casualties, The Powell Doctrine has been successful in being the driving force behind the U.S. military’s usage of unmanned aerial vehicles (UAV’s), also known as drones. The controversy over UAV’s is that drone strikes result in excessive collateral damage, sometimes killing more innocent civilians than military combatants at once

Tuning Rules for a Class of Passivity-Based Controllers for Mechanical Systems

In this paper, we propose several rules to tune the gains for a class of passivity-based controllers for nonlinear mechanical systems. Such tuning rules prescribe a desired local transient response behavior to the closed-loop system. To establish the tuning rules, we implement a PID passivity-based controller. Then, we linearize the closed-loop system, and we transform the matrix of the resulting system into a class of saddle point matrices to analyze the influence of the control gains, in terms of the oscillations and the rise time, on the transient response of the closed-loop system. Hence, the resulting controllers stabilize the plant and simultaneously address the performance of the closed-loop system. Moreover, our analysis provides a clear insight into how the kinetic energy, the potential energy, and the damping of the mechanical system are related to its transient response, endowing in this way the tuning rules with a physical interpretation. Additionally, we corroborate the analytical results through the practical implementation of a controller that stabilizes a two degrees-of-freedom (DoF) planar manipulator, where the control gains are tuned following the proposed rules.Comment: Final submission for journal: IEEE Control Systems Letter

Charting the recovery of dysphagia in two complex cases of post-thermal burn injury: physiological characteristics and functional outcomes

Purpose: This study examined the physiological deficits, recovery pattern, and outcomes observed clinically and instrumentally in two participants with dysphagia post-thermal burn. Methods: Participants were followed prospectively using clinical and instrumental tools of assessment until dysphagia recovery. Clinical swallowing examinations were carried out every 1-2 days, or as clinically indicated. Instrumental assessment using fiberoptic endoscopic examination of swallowing was carried out at fortnightly intervals. Results: Despite variability in the achievement of oral intake milestones, both cases demonstrated protracted recovery from dysphagia contributed to by medical instability and lengthy periods of ventilation and intubation. Instrumental assessment confirmed silent aspiration in both participants, likely owing to decreased laryngopharyngeal sensation. By discharge, participants had returned to their pre-morbid diets. Conclusions: This study highlights the protracted and complex recovery pattern associated with dysphagia following thermal burn injury. The presence of silent aspiration emphasizes the need for instrumental assessment to objectively assess aspiration risk and to facilitate dysphagia recovery within this population

Nodo de recolección y procesamiento de datos basado en GNU/Linux.

Proyecto de Graduación (Licenciatura en Ingeniería en Electrónica. Instituto Tecnológico de Costa Rica. Escuela de Electrónica, 2012.En la actualidad, han surgido problemas en varias infraestructuras de obras públicas en Costa Rica, entre estos inconvenientes se encuentran los daños estructurales en puentes. Se requieren proyectos enfocados en la monitorización de estas estructuras que permitan la lectura de variables físicas por parte de los encargados, para determinar el estado actual del puente. De esta manera, permitir así la resolución de los problemas con suficiente antelación para evitar daños materiales e inclusive pérdidas humanas. Varias escuelas del Tecnológico de Costa Rica se encuentran desarrollando en conjunto, bajo el nombre de grupo de investigación eBridge, el proyecto Predicción Remota de Fallas Estructurales en Puentes. El proyecto de eBridge consiste en una red de sensores colocados en varios puntos estratégicos de un puente. Consecuentemente, un sistema ubicado a no más de 100 metros del puente, se encuentra recolectando, fusionando y procesando los datos de los sensores, los cuales se envían al servidor de ese grupo. El sistema actual que realiza tales funciones es un PC, el cual desperdicia recursos, el consumo energético es alto y no es práctica la instalación cerca del puente. Por lo tanto, el objetivo de este documento es detallar cada paso del desarrollo de un sistema empotrado para la recolección, fusión y procesamiento de datos provenientes de sensores inalámbricos colocados en un puente y el envío posterior de éstos a un servidor de internet. El sistema diseñado se le instaló un Sistema Operativo, el cual maneja los diferentes módulos que se le acopla. Además, la conexión a Internet se da por medio de la red inalámbrica de telefonía móvil. ____________________________________________________________________ Abtract: Nowadays, several problems have arisen in public works infrastructure in Costa Rica; among these problems are structural damages in bridges. Specifics systems are needed to monitor these structures so the administrators can read the physical variables obtained by these systems. Hence, it allows the early resolution of problems avoiding any kind of damage and even loss of humans lifes. Several Tecnológicos de Costa Rica’s schools are developing together (the investigation group is named eBridge) the project Remote Prediction for Bridges’s Structural Failures, which is network of sensors placed in several strategic points under a bridge. Consequently, a system placed within 100 meters of the bridge, is collecting, joining and processing the sensors data, which are sent to the eBridge’s server. Currently, a Personal Computer is performing these functions, which is a waste of resources, has high energy consumption and is not practical to install near the bridge. Therefore, the purpose of this paper is to detail every step of the development of an embedded system for collection, fusion and processing of data from wireless sensors placed on a bridge and later sending them to an internet server

Estimating carbon dioxide residence time scales through noble gas and stable isotope diffusion profiles

The study of natural carbon dioxide reservoirs provides fundamental insight into processes involved in carbon capture and storage. However, the calculations of process rates such as dissolution of CO2 into formation water remain uncertain due to indirectly determined ages of the CO2 influx. The proposed ages for the Bravo Dome gas field in New Mexico, USA, vary from 56 ka to 1.5 Ma. Here we demonstrate that residence times can be estimated from simple modeling of noble gas and stable isotope diffusion profiles from the gas-water contact through the gas column. The Bravo Dome gas field shows a gradient in noble gas concentrations and isotopic ratios from east to west across the 70-km-wide field. A mantle-like end member with a 3He/4He (R/RA) ratio of up to 4.7 is found in the west in contrast to a groundwater end member with high concentrations of air- and crustal-derived noble gases in the east. The air- and crustal-derived noble gases decrease gradually toward the west. Stable isotope compositions (C and O) also vary across the field. Diffusion modeling of He, Ne, Ar, Kr, Xe, and δ13C data yield residence times for the CO2 between 14.1 ± 0.2 ka and 16.9 +1.1/–0.5 ka. This is far less than the previous estimates of 1.2–1.5 Ma based on apatite (U-Th)/He thermochronology, leading to a dissolution rate of 29,900 +11,800/–10,700 t/a to 35,900 ± 12,300 t/a, implying that 28% of the total emplaced CO2 dissolved. This new method can be applied to a wide variety of gas fields with variation in the concentration of groundwater-derived noble gases and allow a better assessment of the time scale of other diffusive fluid-fluid interactions