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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Propuesta de mejora para la reducción del sobredesperdicio del cemento y cerámico, basado en el análisis de los principales desperdicios generados en la construcción de edificaciones de gran altura en Lima Metropolitana / Improvement proposal for the reduction of cement and ceramic over-waste, based on the analysis of the main waste generated in the construction of high-rise buildings in metropolitan Lima

Chávez Rocha, Miguel Fernando, Javier Flores, Melissa Angélica 23 January 2019 (has links)
Un proyecto de construcción tiene como principales objetivos la rentabilidad y la obtención de utilidad. En la actualidad, en edificaciones de gran altura estos vienen siendo afectados por exceso de consumo de material no planificado, es decir el sobredesperdicio. La presente tesis tiene como finalidad analizar y darle seguimiento al flujo interno de dos de los materiales más incidentes en la construcción de una edificación: cemento y cerámico, con el fin de plantear como propuesta de mejora un procedimiento de trabajo que beneficie a la reducción de los sobredesperdicios. La metodología que se utilizó para obtener los datos del análisis consistió en el método de investigación de campo, dado que la recolección de datos se llevó a cabo directamente de tres proyectos de edificación mayor a los quince pisos de altura ubicados en la ciudad de Lima Metropolitana. Se hizo un análisis y seguimiento al flujo de distribución del material y de esta manera se obtiene, resultados que permiten determinar el problema raíz para poder analizarlo e implementar la mejor alternativa para reducir o eliminar estos factores que conllevan al aumento del desperdicio. Se concluye que las causas críticas o principales de estos sobredesperdicios son la falta de seguimiento, planificación, gestión y comunicación que se da en la mayoría de empresas constructoras. Luego de un análisis se establece un procedimiento de trabajo destinado al desarrollo de una actividad con el objetivo principal de disminuir los sobredesperdicios de los materiales identificados en su flujo de distribución. / A construction project has as its main objectives the profitability and the obtaining of utility. Currently, in high-rise buildings these are being affected by excess consumption of unplanned, over-wasted material. The purpose of this thesis is to analyze and monitor the internal flow of two of the most incidental materials in the construction of a building, cement and ceramic, in order to propose as a proposal for improvement a work procedure that benefits the reduction of the over-waste. The methodology that was used to obtain the data of the analysis consisted of the field research method, given that the data collection was carried out directly from three building projects greater than fifteen floors high located in the city of Metropolitan Lima An analysis and monitoring of the distribution flow of the material was made and, in this way, results are obtained that allow the root problem to be determined in order to analyze it and implement the best alternative to reduce or eliminate these factors that lead to an increase in waste. It is concluded that the critical or main causes of these over-waste are the lack of monitoring, planning, management and communication that occurs in most construction companies, thereby establishing a work procedure for the development of an activity with the main objective to reduce the over-waste of the materials identified in its distribution flow. / Tesis
2

Numerical Simulation of Flow Field Inside a Squeeze Film Damper and the Study of the Effect of Cavitation on the Pressure Distribution

Khandare, Milind Nandkumar 2010 December 1900 (has links)
Squeeze Film Dampers (SFDs) are employed in high-speed Turbomachinery, particularly aircraft jet engines, to provide external damping. Despite numerous successful applications, it is widely acknowledged that the theoretical models used for SFD design are either overly simplified or incapable of taking into account all the features such as cavitation, air entrainment etc., affecting the performance of a SFD. On the other hand, experimental investigation of flow field and dynamic performance of SFDs can be expensive and time consuming. The current work simulates the flow field inside the dynamically deforming annular gap of a SFD using the commercial computational fluid dynamics (CFD) code Fluent and compares the results to the experimental data of San Andrés and Delgado. The dynamic mesh capability of Fluent and a User Defined Function (UDF) was used to replicate the deforming gap and motion of the rotor respectively. Two dimensional simulations were first performed with different combinations of rotor whirl speed, operating pressures and with and without incorporating the cavitation model. The fluid used in the simulations was ISO VG 2 Mobil Velocite no. 3. After the successful use of the cavitation model in the 2D case, a 3D model with the same dimensions as the experimental setup was built and meshed. The simulations were run for a whirl speed of 50 Hz and an orbit amplitude of 74 μm with no through flow and an inlet pressure of 31kPa (gauge). The resulting pressures at the mid-span of the SFD land were obtained. They closely agreed with those obtained experimentally by San Andrés and Delgado.
3

Vliv nastaven­ ventilace na mnostv­ pivdÄn©ho vzduchu a jeho distribuci v kabinÄ automobilu / The effect of the ventilation settings on amount of fed air and its distribution in the car cabin

PolÄek, Filip January 2016 (has links)
This thesis deals with measuring of the distribution and volume of intake air inside vehicle cockpit under varying outdoor conditions and air conditioning settings. Fan characteristic was developed to determine the volume of air taken inside the cockpit. The measuring was made using speed probes in climatic chamber, where different outdoor conditions could be simulated. Following the measurements there is dependence between the air distribution and the outside temperature. The diploma thesis presents source materials to develop a mathematical model of car cabin.
4

Designing Reactive Power Control Rules for Smart Inverters using Machine Learning

Garg, Aditie 14 June 2018 (has links)
Due to increasing penetration of solar power generation, distribution grids are facing a number of challenges. Frequent reverse active power flows can result in rapid fluctuations in voltage magnitudes. However, with the revised IEEE 1547 standard, smart inverters can actively control their reactive power injection to minimize voltage deviations and power losses in the grid. Reactive power control and globally optimal inverter coordination in real-time is computationally and communication-wise demanding, whereas the local Volt-VAR or Watt-VAR control rules are subpar for enhanced grid services. This thesis uses machine learning tools and poses reactive power control as a kernel-based regression task to learn policies and evaluate the reactive power injections in real-time. This novel approach performs inverter coordination through non-linear control policies centrally designed by the operator on a slower timescale using anticipated scenarios for load and generation. In real-time, the inverters feed locally and/or globally collected grid data to the customized control rules. The developed models are highly adjustable to the available computation and communication resources. The developed control scheme is tested on the IEEE 123-bus system and is seen to efficiently minimize losses and regulate voltage within the permissible limits. / Master of Science

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