The Experts below are selected from a list of 15 Experts worldwide ranked by ideXlab platform
Giancarlo Pennati - One of the best experts on this subject based on the ideXlab platform.
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possible benefits of catheters with lateral holes in coronary thrombus aspiration a computational study for different clot viscosities and Vacuum Pressures
Artificial Organs, 2014Co-Authors: S Soleimani, Gabriele Dubini, Giancarlo PennatiAbstract:According to a number of clinical studies, coronary aspiration catheters are useful tools to remove a thrombus (blood clot) blocking a coronary artery. However, these thrombectomy devices may fail to remove the blood clot entirely. Few studies have been devoted to a systematic analysis of factors affecting clot aspiration. The geometric characteristics of the aspiration catheter, the physical properties of the thrombus, and the Applied Vacuum Pressure are crucial parameters. In this study, the aspiration of a blood clot blocking a coronary bifurcation is computationally simulated. The clot is modeled as a highly viscous fluid, and a two-phase (blood and clot) problem is solved. The effects of geometric variations in the tip of the coronary catheter, including lateral hole size and location, are investigated considering different aspiration Pressures and clot viscosities. A Bird-Carreau model is adopted for blood viscosity, while a power law model is used to describe the clot rheology. Computational results for blood clot aspiration show that the presence of holes in the lateral part of the tip of the catheter can be beneficial depending on clot viscosity, hole features, and Applied aspiration Pressure. In general, the holes are beneficial when the clot viscosity is low, while aspiration catheters without any extra lateral holes exhibit better performance for higher clot viscosity. However, when higher aspiration Pressures are Applied, the catheters tend to behave relatively similarly in removing clots with various viscosities, reducing the role of the clot viscosity.
S Soleimani - One of the best experts on this subject based on the ideXlab platform.
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possible benefits of catheters with lateral holes in coronary thrombus aspiration a computational study for different clot viscosities and Vacuum Pressures
Artificial Organs, 2014Co-Authors: S Soleimani, Gabriele Dubini, Giancarlo PennatiAbstract:According to a number of clinical studies, coronary aspiration catheters are useful tools to remove a thrombus (blood clot) blocking a coronary artery. However, these thrombectomy devices may fail to remove the blood clot entirely. Few studies have been devoted to a systematic analysis of factors affecting clot aspiration. The geometric characteristics of the aspiration catheter, the physical properties of the thrombus, and the Applied Vacuum Pressure are crucial parameters. In this study, the aspiration of a blood clot blocking a coronary bifurcation is computationally simulated. The clot is modeled as a highly viscous fluid, and a two-phase (blood and clot) problem is solved. The effects of geometric variations in the tip of the coronary catheter, including lateral hole size and location, are investigated considering different aspiration Pressures and clot viscosities. A Bird-Carreau model is adopted for blood viscosity, while a power law model is used to describe the clot rheology. Computational results for blood clot aspiration show that the presence of holes in the lateral part of the tip of the catheter can be beneficial depending on clot viscosity, hole features, and Applied aspiration Pressure. In general, the holes are beneficial when the clot viscosity is low, while aspiration catheters without any extra lateral holes exhibit better performance for higher clot viscosity. However, when higher aspiration Pressures are Applied, the catheters tend to behave relatively similarly in removing clots with various viscosities, reducing the role of the clot viscosity.
Buddhima Indraratna - One of the best experts on this subject based on the ideXlab platform.
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predictions and performances of prefabricated vertical drain stabilised soft clay foundations
2006Co-Authors: Buddhima Indraratna, Cholachat RujikiatkamjornAbstract:In this paper, the analytical solution for radial consolidation of soft soils is proposed considering the impacts of the variation of volume compressibility and permeability. The Cavity Expansion Theory is employed to predict the smear zone caused by the installation of mandrel driven vertical drains in soft clay. The smear zone prediction is then compared to the data obtained from the large-scale radial consolidation tests. Furthermore, the advantages and limitations of Vacuum application through vertical drains in the absence of high surcharge embankments are discussed using the proposed solutions. The Applied Vacuum Pressure generates negative pore water Pressure, resulting in an increase in the effective stress, which leads to accelerated consolidation. Analytical and Numerical analysis incorporating the equivalent plane strain solution are conducted to predict the excess pore Pressures, lateral and vertical displacements. The equivalent plane strain solution can be used as a predictive tool with acceptable accuracy due to the significant progress that has been made in the past few years through rigorous mathematical modelling and numerical analysis developed by the primary author and co-workers (Indraratna et al., 1992 – 2005). Several case histories are discussed and analysed, including the site of the 2nd Bangkok International Airport. The predictions are compared with the available field data, confirming that the equivalent plane strain model can be used confidently to predict the performance with acceptable accuracy. Difficulties in assuring good performance can also be analysed and interpreted through mathematical modelling, thereby enabling due caution in the design and construction stages. The research findings verify that the role of smear, drain unsaturation, and Vacuum distribution can significantly affect soil consolidation, hence, these aspects need to be modelled appropriately in any numerical analysis to obtain reliable predictions.
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analytical and numerical modeling of soft soil stabilized by prefabricated vertical drains incorporating Vacuum preloading
International Journal of Geomechanics, 2005Co-Authors: Buddhima Indraratna, Cholachat Rujikiatkamjorn, Iyathurai Sathananthan, A S BalasubramaniamAbstract:This paper describes the analytical formulation of a modified consolidation theory incorporating Vacuum Pressure, and numerical modeling of soft clay stabilized by prefabricated vertical drains, with a linearly distributed ~trapezoidal! Vacuum Pressure for both axisymmetric and plane strain conditions. The effects of the magnitude and distribution of Vacuum Pressure on soft clay consolida- tion are examined through average time-dependent excess pore Pressure and consolidation settlement analyses. The plane strain analysis was executed by transforming the actual vertical drains into a system of equivalent parallel drain walls by adjusting the coefficient of permeability of the soil and the Applied Vacuum Pressure. The converted parameters are incorporated in the finite element code ABAQUS, employing the modified Cam-clay theory. Numerical analysis is conducted to study the performance of a full-scale test embankment constructed on soft Bangkok clay. The performance of this selected embankment is predicted on the basis of four different Vacuum Pressure distributions. The predictions are compared with the available field data. The assumption of distributing the Vacuum Pressure as a constant over the soil surface and varying it linearly along the drains seems justified in relation to the field data.
Cholachat Rujikiatkamjorn - One of the best experts on this subject based on the ideXlab platform.
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predictions and performances of prefabricated vertical drain stabilised soft clay foundations
2006Co-Authors: Buddhima Indraratna, Cholachat RujikiatkamjornAbstract:In this paper, the analytical solution for radial consolidation of soft soils is proposed considering the impacts of the variation of volume compressibility and permeability. The Cavity Expansion Theory is employed to predict the smear zone caused by the installation of mandrel driven vertical drains in soft clay. The smear zone prediction is then compared to the data obtained from the large-scale radial consolidation tests. Furthermore, the advantages and limitations of Vacuum application through vertical drains in the absence of high surcharge embankments are discussed using the proposed solutions. The Applied Vacuum Pressure generates negative pore water Pressure, resulting in an increase in the effective stress, which leads to accelerated consolidation. Analytical and Numerical analysis incorporating the equivalent plane strain solution are conducted to predict the excess pore Pressures, lateral and vertical displacements. The equivalent plane strain solution can be used as a predictive tool with acceptable accuracy due to the significant progress that has been made in the past few years through rigorous mathematical modelling and numerical analysis developed by the primary author and co-workers (Indraratna et al., 1992 – 2005). Several case histories are discussed and analysed, including the site of the 2nd Bangkok International Airport. The predictions are compared with the available field data, confirming that the equivalent plane strain model can be used confidently to predict the performance with acceptable accuracy. Difficulties in assuring good performance can also be analysed and interpreted through mathematical modelling, thereby enabling due caution in the design and construction stages. The research findings verify that the role of smear, drain unsaturation, and Vacuum distribution can significantly affect soil consolidation, hence, these aspects need to be modelled appropriately in any numerical analysis to obtain reliable predictions.
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analytical and numerical modeling of soft soil stabilized by prefabricated vertical drains incorporating Vacuum preloading
International Journal of Geomechanics, 2005Co-Authors: Buddhima Indraratna, Cholachat Rujikiatkamjorn, Iyathurai Sathananthan, A S BalasubramaniamAbstract:This paper describes the analytical formulation of a modified consolidation theory incorporating Vacuum Pressure, and numerical modeling of soft clay stabilized by prefabricated vertical drains, with a linearly distributed ~trapezoidal! Vacuum Pressure for both axisymmetric and plane strain conditions. The effects of the magnitude and distribution of Vacuum Pressure on soft clay consolida- tion are examined through average time-dependent excess pore Pressure and consolidation settlement analyses. The plane strain analysis was executed by transforming the actual vertical drains into a system of equivalent parallel drain walls by adjusting the coefficient of permeability of the soil and the Applied Vacuum Pressure. The converted parameters are incorporated in the finite element code ABAQUS, employing the modified Cam-clay theory. Numerical analysis is conducted to study the performance of a full-scale test embankment constructed on soft Bangkok clay. The performance of this selected embankment is predicted on the basis of four different Vacuum Pressure distributions. The predictions are compared with the available field data. The assumption of distributing the Vacuum Pressure as a constant over the soil surface and varying it linearly along the drains seems justified in relation to the field data.
Gabriele Dubini - One of the best experts on this subject based on the ideXlab platform.
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possible benefits of catheters with lateral holes in coronary thrombus aspiration a computational study for different clot viscosities and Vacuum Pressures
Artificial Organs, 2014Co-Authors: S Soleimani, Gabriele Dubini, Giancarlo PennatiAbstract:According to a number of clinical studies, coronary aspiration catheters are useful tools to remove a thrombus (blood clot) blocking a coronary artery. However, these thrombectomy devices may fail to remove the blood clot entirely. Few studies have been devoted to a systematic analysis of factors affecting clot aspiration. The geometric characteristics of the aspiration catheter, the physical properties of the thrombus, and the Applied Vacuum Pressure are crucial parameters. In this study, the aspiration of a blood clot blocking a coronary bifurcation is computationally simulated. The clot is modeled as a highly viscous fluid, and a two-phase (blood and clot) problem is solved. The effects of geometric variations in the tip of the coronary catheter, including lateral hole size and location, are investigated considering different aspiration Pressures and clot viscosities. A Bird-Carreau model is adopted for blood viscosity, while a power law model is used to describe the clot rheology. Computational results for blood clot aspiration show that the presence of holes in the lateral part of the tip of the catheter can be beneficial depending on clot viscosity, hole features, and Applied aspiration Pressure. In general, the holes are beneficial when the clot viscosity is low, while aspiration catheters without any extra lateral holes exhibit better performance for higher clot viscosity. However, when higher aspiration Pressures are Applied, the catheters tend to behave relatively similarly in removing clots with various viscosities, reducing the role of the clot viscosity.