Study of bubbly flows in an open-source software

Bubbly flows occur everywhere in nature and engineering. The study of such flows can be done theoretically, experimentally or computationally. In the present thesis, latter option was chosen and multiphase computational fluid dynamics (M-CFD) simulation methods are tested for simulation of a specific situation of such flows. All the simulations done under this thesis are about an initially spherical bubble starting from rest in quiescent water. In order to accurately assess the dynamics of that bubble an open-source M-CFD software was used, OpenFOAM. The dynamics of the bubble was set by means of the study of three characteristics: rise velocity, trajectory and shape. Here, a Matlab algorithm was developed to get the rise velocity of the bubble. Two cases have been simulated based on Krishna et al. (1999) experimental, simulated and numerical data base, one in two dimensions and the other in three dimensions, both were computed to a range of bubble between 4 and 12 millimeters in diameter. The simulations were carried out using a geometric Volume-Of-Fluid (VOF) method, IsoAdvector which utilizes iso-surfaces in the subcell interface reconstruction step. This algorithm provides results that are close agreement with the experimental, simulated and numerical data already named, and also in close agreement with the experimental rise velocities of Haberman et al. (1953) investigation. Furthermore, the rise velocity equation proposed by Jamialahmadi et al. (1994) and the bubble shapes shown in Kumar Tripathi et al. (2015) simulations match with the simulations of the present study. Therefore, these results verify the capability of OpenFOAM simulations with IsoAdvector algorithm, which are powerful tools for a priori determination of the morphology and rise characteristics of an initially spherical bubble starting from rest in quiescent water and yield on the same level as ANSYS-CFX commercial software

Pointing Devices for Wearable Computers

We present a survey of pointing devices for wearable computers, which are body-mounted devices that users can access at any time. Since traditional pointing devices (i.e., mouse, touchpad, and trackpoint) were designed to be used on a steady and flat surface, they are inappropriate for wearable computers. Just as the advent of laptops resulted in the development of the touchpad and trackpoint, the emergence of wearable computers is leading to the development of pointing devices designed for them. However, unlike laptops, since wearable computers are operated from different body positions under different environmental conditions for different uses, researchers have developed a variety of innovative pointing devices for wearable computers characterized by their sensing mechanism, control mechanism, and form factor. We survey a representative set of pointing devices for wearable computers using an “adaptation of traditional devices” versus “new devices” dichotomy and study devices according to their control and sensing mechanisms and form factor. The objective of this paper is to showcase a variety of pointing devices developed for wearable computers and bring structure to the design space for wearable pointing devices. We conclude that a de facto pointing device for wearable computers, unlike laptops, is not likely to emerge

A methodological proposal to estimate changes of residential property value: case study developed in Bogota

This article is an empirical study of residential land values in the vicinity of the TransMilenio system (Bus Rapid Transit, BRT) in Bogota´ (Colombia). The results have been established through impact evaluation by means of nonparameteric approaches (Propensity Score Matching, PSM) and econometric approaches (Spatial Hedonic Price, SHP) indicating that access to the BRT system generates benefits on the change of property value

A methodological proposal to estimate changes of residential property value: case study developed in Bogota

This article is an empirical study of residential land values in the vicinity of the TransMilenio system (Bus Rapid Transit, BRT) in Bogota´ (Colombia). The results have been established through impact evaluation by means of nonparameteric approaches (Propensity Score Matching, PSM) and econometric approaches (Spatial Hedonic Price, SHP) indicating that access to the BRT system generates benefits on the change of property value

Una propuesta metodológica para estimar los cambios sobre el valor de la propiedad: estudio de caso para Bogotá aplicando Propensity Score Matching y Precios Hedónicos Espaciales

The aim of this study is to analyze and compare the results from Propensity Score Matching (PSM) and Spatial Hedonic Prices (SHP) methodologies estimating value fluctuations on residential proprieties in Bogotá (Colombia). Specifically, this study examines value fluctuations on residential properties nearby stations of the Bus Rapid Transit (BRT) system—Transmilenio—. The PSM and SHP approaches suggest additional value increases for residential properties close to BRT stations

Una propuesta metodológica para estimar los cambios sobre el valor de la propiedad: estudio de caso para Bogotá aplicando Propensity Score Matching y Precios Hedónicos Espaciales

The aim of this study is to analyze and compare the results from Propensity Score Matching (PSM) and Spatial Hedonic Prices (SHP) methodologies estimating value fluctuations on residential proprieties in Bogotá (Colombia). Specifically, this study examines value fluctuations on residential properties nearby stations of the Bus Rapid Transit (BRT) system—Transmilenio—. The PSM and SHP approaches suggest additional value increases for residential properties close to BRT stations

The political institutionalization of the social economy in Ecuador: Indigeneity and institutional logics

How differing social economy traditions within the global South can combine with state and market sectors to provide alternative development paths has increasingly become a focus of political and policy debate. This paper uses an institutional logics perspective to analyse the interaction between indigenous collective traditions and other institutional logics in Ecuador’s social economy. Results demonstrate how indigenous practice has interacted with other social economy elements to produce novel organizational and institutional forms. Findings from original primary research identify processes of co-existence, accommodation and conflict in the interaction of differing institutional civil society, state and market logics and the institutionalization of the social economy. Critically, processes of conflict generated by contradictory logics have over time helped close down many of the new political spaces, limiting the ongoing inclusion of indigenous institutions and the ability to construct an alternative, pluralistic path to development

The Design, Implementation, and Evaluation of a Pointing Device For a Wearable Computer

U.S. Air Force special tactics operators at times use small wearable computers (SWCs) for mission objectives. The primary pointing device of a SWC is either a touchpad or trackpoint, embedded into the chassis of the SWC. In situations where the user cannot directly interact with these pointing devices, the utility of the SWC is decreased. We developed a pointing device called the G3 that can be used for SWCs used by operators. The device utilizes gyroscopic sensors attached to the user’s index finger to move the computer cursor according to the angular velocity of his finger. We showed that, as measured by Fitts’s law, the overall performance and accuracy of the G3 was better than that of the touchpad and trackpoint. These findings suggest that the G3 can adequately be used with SWCs. Additionally, we investigated the G3\u27s utility as a control device for operating micro remotely piloted aircrafts