Métodos de excavación en roca en obras subterráneas.

Tesis (Ingeniero Constructor)RESUMEN: Esta investigación bibliográfica de excavación en roca en obras subterráneas tiene como objetivo general hacer un análisis técnico y económico de los dos métodos de excavación en roca como son Perforación y Tronadura y Excavación mecánica de la roca. Aquí se expone de un modo general desde los estudios previos a la construcción de una obra subterránea, pasando por conocimientos básicos de geología general hasta los estudios geológicos que se necesitan en toda obra de construcción de túneles. Además se encuentra lo necesario para ejecutar las faenas de excavación en roca como equipos, procedimientos seguros de realizar las excavaciones, sostenimientos que se utilizan en estas faenas, actividades de apoyo como son la ventilación al avance, topografía utilizadas en túneles hasta llegar a los rendimientos y parámetros que se utilizan para su predicción, finalizando con los costos de cada método. Las conclusiones obtenidas en esta investigación bibliográfica pueden ser de interés par, el lector porque logra saber en que condiciones se puede utilizar cada método y c~l es más viable económicamente según las condiciones del proyecto.ABTRACT: This bibliographical investigation of excavation in rock in underground works has as general objective to make a technical and economic analysis of the two excavation methods in rock Iike they are Perforatíon and Explosion and mechanical Excavation of the rock. Here it is exposed in a general way from the previous studies to the construction of an underground work, going by basic knowledge of general geology until the geologic studies that are needed in all work of construction of tunnels. Was also the necessary thing to execute the excavation tasks in rock Iike teams, sure procedures of carrying out the excavations, maintenances that are used in these tasks, support activities like they are the ventilation to the advance, topography used in tunnels until arriving to the yields and parameters that are used for their prediction, concluding with the costs of each method. The conclusfons obtained in this bibliographical investigation can being of interest for the reader because it is able to know in that condition you can use each method and which is viable economically according to the conditions of the project

Privatization in Colombia: A Plant Performance Analysis

This paper describes the privatization program carried out in the productive sector of the Colombian economy during the 1990s. It evaluates privatization within the policy context of general market deregulation and the promotion of private investment in the provision of public infrastructure and domiciliary public services. Two case studies are explored: the manufacturing and power sectors. The paper follows the ex-post measuring and econometric analysis of a set of operative and restructuring performance indicators for the privatized firms. For manufacturing, the study sample consists of 30 large manufacturing firms of which the Instituto de Fomento Industrial was the founding or supporting partner. The main findings suggest that those firms followed pro-cyclical behavior relative to their private competitors and undertook tight plant operative restructuring. For the power sector, the paper studies the impact of regulatory reform on market entry, ownership structure, market competition, and productive efficiency of the privatized holdings. The results suggest that privatization and entry competition in power generation have had a positive effect on the privatized utilities’ efficiency and investment. With respect to thermal generation, the measurement of productive efficiency follows a data envelope analysis technique based on a sample of 33 plants that account for 85% of the installed capacity. The sample units are plants that were active before the reform and new entrants that started business operations after the reform. The main outcome shows that efficiency scores have improved after the reform and that regulatory policy has had a positive effect on productive efficiency.

Ownership structure and risk at Colombian banks

The separation between ownership and the control of capital in banks generates differences in thepreferences for risk among shareholders and the manager. These differences could imply a corporate governance problem in banks with a dispersed ownership, since owners fail to exert control in the allocation of capital. In this paper we examine the relationship between the ownership structure and risk for Colombian banks. Our results suggest that a high ownership concentration leads to higher levels of risk.corporate governance and banking risk

Modeling the monetary policy reaction function of the colombian central bank

This paper proposes a simple Ordered Probit model to analyse the monetary policy reactionfunction of the Colombian Central Bank. There is evidence that the reaction function isasymmetric, in the sense that the Bank increases the Bank rate when the gap between observedinflation and the inflation target (lagged once) is positive, but it does not reduce the Bank rate whenthe gap is negative. This behaviour suggests that the Bank is more interested in fulfilling theannounced inflation target rather than in reducing inflation excessively. The forecasting performanceof the model, both within and beyond the estimation period, appears to be particularly good.Monetary policy reaction function, Ordered Probit model, Central Bank independence, Colombia

MIMO PID Controller Tuning Method for Quadrotor Based on LQR/LQG Theory

In this work, a new pre-tuning multivariable PID (Proportional Integral Derivative) controllers method for quadrotors is put forward. A procedure based on LQR/LQG (Linear Quadratic Regulator/Gaussian) theory is proposed for attitude and altitude control, which suposes a considerable simplification of the design problem due to only one pretuning parameter being used. With the aim to analyze the performance and robustness of the proposed method, a non-linear mathematical model of the DJI-F450 quadrotor is employed, where rotors dynamics, together with sensors drift/bias properties and noise characteristics of low-cost commercial sensors typically used in this type of applications are considered. In order to estimate the state vector and compensate bias/drift effects in the measures, a combination of filtering and data fusion algorithms (Kalman filter and Madgwick algorithm for attitude estimation) are proposed and implemented. Performance and robustness analysis of the control system is carried out by employing numerical simulations, which take into account the presence of uncertainty in the plant model and external disturbances. The obtained results show the proposed controller design method for multivariable PID controller is robust with respect to: (a) parametric uncertainty in the plant model, (b) disturbances acting at the plant input, (c) sensors measurement and estimation errors

Neural Network Based Min-Max Predictive Control. Application to a Heat Exchanger

IFAC Adaptation and Learning in Control and Signal Processing. Cemobbio-Como. Italy. 2001Min-max model predictive controllers (MMMPC) have been proposed for the control of linear plants subject to bounded uncertainties. The implementation of MMMPC suffers a large computational burden due to the numerical optimization problem that has to be solved at every sampling time. This fact severely limits the class of processes in which this control is suitable. In this paper the use of a Neural Network (NN) to approximate the solution of the min-max problem is proposed. The number of inputs of the NN is determined by the order and time delay of the model together with the control horizon. For large time delays the number of inputs can be prohibitive. A modification to the basic formulation is proposed in order to avoid this later problem. Simulation and experimental results are given using a heat exchanger

Implementation of min–max MPC using hinging hyperplanes. Application to a heat exchanger

Min–max model predictive control (MMMPC) is one of the few control techniques able to cope with modelling errors or uncertainties in an explicit manner. The implementation of MMMPC suffers a large computational burden due to the numerical min–max problem that has to be solved at every sampling time. This fact severely limits the range of processes to which this control structure can be applied. An implementation scheme based on hinging hyperplanes that overcome these problems is presented here. Experimental results obtained when applying the controller to the heat exchanger of a pilot plant are given.Ministerio de Ciencia y Tecnología DPI2001-2380-C02-01Ministerio de Ciencia y Tecnología DPI2002-04375-C03-0

Feedback control ideas for call center staffing

European Control Conference 2009 • Budapest, Hungary, August 23–26, 2009Call centers are nowadays a widespread solution to deal with customer support and as platform for different kind of business. Call center staffing is crucial to provide adequate service levels at acceptable costs. The task is usually accomplished using heuristics with the help of a human experts or with some static offline optimization based on operations research. Simulators based on queue theory are in some cases also used. The aim of the paper is to show that call center staffing can be posed as a feedback control problem with the advantage of getting a higher level of automation, and a wealth of results from control theory that can help to obtain the best possible staffing. In the paper the authors briefly describe the working procedures of call centers and how the staffing is usually made. They propose a feedback controller that it is used with a call center simulator. The results show that good call center staffing can be obtained even with a not very sophisticated controller

The splendor of form. H.U. von Balthasar: a metaphysical proposal

¿Es posible describir una metafísica en la obra de H.U. von Balthasar? El artículo que sigue propone una lectura ontológica del monumento cultura del pensador suizo desde tres claves importantes: el ser y los trascendentales, en la particular ordenación que Balthasar les dar; la cuestión de la diferencia y la forma en la perspectiva de la belleza.Is it possible to describe a Metaphysics in the writings from H. U. Balthasar? This paper proposes an ontological review of the big cultural monument from the Swiss philosopher, from three important keys: the human being and the transcendence, following the particular order given by Balthasar, the question of the difference and the form from the beauty perspective