• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1
  • Tagged with
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 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

Simulation and Comparison of Operational Modes in Simulated Moving Bed Chromatography and Gas-Phase Adsorptive Separation

Yu, Yueying 14 January 2016 (has links)
This dissertation describes the simulation and optimization of adsorptive and chromatographic separation processes. The first part focus on the simulation and comparison of operational modes in simulated moving bed (SMB) chromatography for separation and purification in bioprocesses. The second part includes the simulation of gas-phase adsorptive processes by pressure swing adsorption and temperature swing adsorption technologies. The applications of SMB chromatography are popular in separating and purifying enantiomers, petrochemicals, pharmaceuticals and biochemicals with higher yield and lower solvent consumption. We simulate and compare several operational modes of simulated moving bed (SMB) for a binary and a ternary bioprocess using Aspen Chromatography. These operational modes are able to improve the separation efficiency of the basic SMB process by our simulation and optimization. We compare their separation performances and identify heuristics that will guide the selection of operational modes across a variety of systems. Pressure swing adsorption (PSA) and temperature swing adsorption (TSA) are two of the main technologies for gas-phase adsorption separation processes. We simulate and demonstrate a PSA model for air separation system and a TSA model for CO2 capture system in Aspen Adsorption. We present their separation performance plots to provide the physical insights of these two systems. / Ph. D.
2

Concepção de um índice para localização de trincas em eixos rotativos através da análise do SDI (Shape and Directivity Index) /

Oliveira, Lucas Rangel de. January 2019 (has links)
Orientador: Gilberto Pechoto de Melo / Resumo: A identificação de trincas ainda é um desafio na área de monitoramento da integridade estrutural em eixos rotativos. Embora muitas técnicas e modelos tenham sido desenvolvidos, encontrar uma técnica eficiente que possa localizar uma única ou múltiplas trincas ao longo do eixo, ainda é um grande desafio. Nesse trabalho, um novo índice para localização de trincas em eixos rotativos é apresentado. A equação do movimento do rotor com trinca utiliza a notação em coordenadas complexas a fim de separar as contribuições dos modos de precessão direta e retrógrada. O índice SDI (shape and directivity index) é calculado para o rotor, cujo modelo matemático considera a variação instantânea da rigidez do elemento finito devido à abertura e o fechamento gradual da trinca, conhecido como efeito breathing. Através da manipulação do SDI no modelo de cores HSV (hue, saturation and value), desenvolve-se uma escala métrica, visualizada em um mapa de cores, que possibilita localizar a anisotropia causada pela trinca ao longo do eixo. Profundidade e posição da trinca, presença de múltiplas trincas, entre outros fatores que afetam a assinatura da trinca em outros métodos de identificação são analisados. Bons resultados demonstram a eficiência e robustez do novo índice para diversos casos de operação do rotor. Essa métrica de dano acrescenta uma contribuição para os métodos de localização de trincas em sistemas rotativos. / Abstract: Crack identification is still a challenge in the area of structural health monitoring dedicated to rotating shafts. Although many techniques and models have been developed, finding an efficient technique capable of locating a single or multiple cracks along the shaft is still a challenge. In this work, a new index for locating cracks in rotating shafts is proposed. The equation of motion of the cracked rotor uses notation in complex coordinates in order to separate the contributions of forward and backward precession modes. The SDI (shape and directivity index) is calculated for the cracked rotor, which mathematical model considers the instantaneous variation of the finite element stiffness due to the gradual opening and closing of the crack, known as the breathing effect. By manipulating the SDI in the HSV (hue, saturation and value) color model, a metric scale is developed to locate the anisotropy caused by cracks along the shaft, visualized on a color map. Depth and position of the crack, presence of multiple cracks, among other factors that affect the signature of the crack in other identification methods are analyzed. Good results demonstrate the efficiency and robustness of the new index for several rotor operation conditions. This damage metric contributes to crack localization methods in rotating systems. / Doutor

Page generated in 0.1228 seconds