S. Wadia-fascetti - Academia.edu (original) (raw)
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Papers by S. Wadia-fascetti
Computational Fluid and Solid Mechanics, 2001
Computer‐Aided Civil …, 2001
Structural health monitoring systems rely on algorithms to detect potential changes in structural... more Structural health monitoring systems rely on algorithms to detect potential changes in structural parameters that may be indicative of damage. Parameterestimation algorithms seek to identify changes in structural parameters by adjusting parameters of an a priori finiteelement model of a structure to reconcile its response with a set of measured test data. Modeling error, represented as uncertainty in the parameters of a finite-element model of the structure, curtails capability of parameter estimation to capture the physical behavior of the structure. The performance of four error functions, two stiffness-based and two flexibility-based, is compared in the presence of modeling error in terms of the propagation rate of the modeling error and the quality of the final parameter estimates. Three different types of parameters are used in the parameter estimation procedure: (1) unknown parameters that are to be estimated, (2) known parameters assumed to be accurate, and (3) uncertain parameters that manifest the modeling
Journal of Structural …, 1999
A new error function is introduced to use natural frequencies and associated mode shapes measured... more A new error function is introduced to use natural frequencies and associated mode shapes measured at a selected subset of degrees of freedom for stiffness and mass parameter estimation at the element level. The incomplete mode shapes are used to form the modal stiffness-based ...
Applications of Advanced Technology in Transportation, 2006
2010 IEEE International Geoscience and Remote Sensing Symposium, 2010
Scattering from a subsurface point object, such as a reinforcing steel bar embedded concrete or a... more Scattering from a subsurface point object, such as a reinforcing steel bar embedded concrete or a tunnel buried in sand, results in a B-scan contour that is essentially hyperbolic as the Ground Penetrating Radar (GPR) passes over the object. The shape of the hyperbola can be used to determine the angle at which the GPR traveled over the point object.
2009 IEEE International Geoscience and Remote Sensing Symposium, 2009
Subsurface sensing modalities such as Ground Penetrating Radar (GPR) are increasingly being used ... more Subsurface sensing modalities such as Ground Penetrating Radar (GPR) are increasingly being used to assess the condition of aging civil infrastructure by evaluating deterioration within roadways and bridges, and to monitor the security of national borders through the detection of underground tunnels. The need to address these issues is intensifying and, while valuable data is collected using nondestructive evaluation there is urgency for improved understanding and analysis. Simulation of
IGARSS 2008 - 2008 IEEE International Geoscience and Remote Sensing Symposium, 2008
Computational modeling is effectively analyzes the wave propagation and interaction within bridge... more Computational modeling is effectively analyzes the wave propagation and interaction within bridge structures, providing valuable information for sensor selection and placement. It provides a good basis for the inverse problem for defect detection and reconstruction. The finite difference time domain (FDTD) method can be used to model nondestructive wave based sensing using air-coupled ground penetrating radar (GPR). A full 3D
Structural Control for Civil and Infrastructure Engineering - Proceedings of the 3rd International Workshop on Structural Control, 2001
Parameter estimation is commonly referred to as system identification or structural identificatio... more Parameter estimation is commonly referred to as system identification or structural identification. For this purpose, an a priori parametric analytical model that describes the response of a physical system is assumed, and then the system's actual response is measured experimentally. Through some correlation of the analytical model with the measured data the parameters of the analytical model are updated. This paper presents an overview of current challenges in the field of parameter estimation with a specific application to condition assessment of structures. Over the past 10 years, a large number of methods have been proposed to monitor structural performance. Based on deviations of the analytical model from the observed mechanical behavior the changes in the structural parameters are then estimated. Using these parameter estimates, the condition of the structure is diagnosed. Many of these methods have shown promise using simulated or laboratory data, and some have even been successful when applied in a field test. However, the use of parameter estimation techniques for structural condition monitoring has difficulties to become practical for implementation in operating structures. Many of the reasons are economic, but many aspects of this technology are still in need of development in order to make the benefits of this technology apparent to the civil engineering community.
... Javier Morales, Nayda Santiago UPRM Current CenSSIS FPGA Projects 1. Acceleration of the 3D ... more ... Javier Morales, Nayda Santiago UPRM Current CenSSIS FPGA Projects 1. Acceleration of the 3D FDTD Algorithm in Fixed-Point Arithmetic Using Reconfigurable Hardware ▪ Wang Chen, Miriam Leeser, Carey Rappaport 2. Phase Unwrapping for BioBED on the Annapolis ...
ABSTRACT The accuracy of the Born Approximation as a forward model of elastic wave scattering in ... more ABSTRACT The accuracy of the Born Approximation as a forward model of elastic wave scattering in the context of simulating Impact Echo tests of reinforced of concrete is investigated in this paper. The ability of a forward model to realistically simulate the physics of a system can be important when such a model is used as part of an inverse solution. Synthetic data of scattering by air void defects that are typically present in damaged civil engineering structures is generated by a two-dimensional Finite Difference in Time Domain (FDTD) model for elastic wave propagation in an infinite, homogeneous and isotropic concrete medium. Horizontal elongated cracks and air voids with compact shapes are considered in this study for comparison between the synthetic and the Born approximated data. It is observed that the Born Approximation simulates a compact air void better than a horizontal elongated one. This knowledge provides insight on Born Approximation as part of an inverse solution towards imaging of air voids of various shapes in a damaged civil engineering structure.
Research in Nondestructive Evaluation, 2009
Ground penetrating radar (GPR) for nondestructive testing is a relatively young technology, espec... more Ground penetrating radar (GPR) for nondestructive testing is a relatively young technology, especially with application to civil infrastructure such as bridges and roadways.
Computer-Aided Civil and Infrastructure Engineering, 2007
Ground penetrating radar (GPR) has become a viable technology for non-destructive condition asses... more Ground penetrating radar (GPR) has become a viable technology for non-destructive condition assessment of reinforced concrete structures. Interpretation of the radar signal is typically performed through preliminary filtering techniques and interpretation is based on viewing numerous signals in the form of a scan. Although anomalies can be evident in the scanned image, quantification and interpretation of the main issue remain ambiguous. This article presents the ambiguity and common methods of interpretation based on response amplitude and travel time. An integrated medium is developed and used as a forward modeling tool to generate a realistic radar reflection of a reinforced concrete bridge deck with defects. A healthy deck reflection is obtained from a separate model and is combined with an inverse solution to quantifiably estimate unknown subsurface properties such as layer thickness and dielectric constants of subsurface materials evident in the realistic radar trace as well as. The forward modeling tool and associated model based assessment provides an objective computational alternative to the interpretation of scanned images.
Research in Nondestructive Evaluation, 2009
Computational modeling is beneficial in the preparation for nondestructive wave-based sensing. Fo... more Computational modeling is beneficial in the preparation for nondestructive wave-based sensing. Forward models, which can be implemented through a variety of computational modeling techniques, enable parametric evaluations to assess the functionality of a sensor under different conditions, and are integral to the solution of the inverse problem. The focus of this article is on the comparison of two-dimensional (2D) and
Computational Fluid and Solid Mechanics, 2001
Computer‐Aided Civil …, 2001
Structural health monitoring systems rely on algorithms to detect potential changes in structural... more Structural health monitoring systems rely on algorithms to detect potential changes in structural parameters that may be indicative of damage. Parameterestimation algorithms seek to identify changes in structural parameters by adjusting parameters of an a priori finiteelement model of a structure to reconcile its response with a set of measured test data. Modeling error, represented as uncertainty in the parameters of a finite-element model of the structure, curtails capability of parameter estimation to capture the physical behavior of the structure. The performance of four error functions, two stiffness-based and two flexibility-based, is compared in the presence of modeling error in terms of the propagation rate of the modeling error and the quality of the final parameter estimates. Three different types of parameters are used in the parameter estimation procedure: (1) unknown parameters that are to be estimated, (2) known parameters assumed to be accurate, and (3) uncertain parameters that manifest the modeling
Journal of Structural …, 1999
A new error function is introduced to use natural frequencies and associated mode shapes measured... more A new error function is introduced to use natural frequencies and associated mode shapes measured at a selected subset of degrees of freedom for stiffness and mass parameter estimation at the element level. The incomplete mode shapes are used to form the modal stiffness-based ...
Applications of Advanced Technology in Transportation, 2006
2010 IEEE International Geoscience and Remote Sensing Symposium, 2010
Scattering from a subsurface point object, such as a reinforcing steel bar embedded concrete or a... more Scattering from a subsurface point object, such as a reinforcing steel bar embedded concrete or a tunnel buried in sand, results in a B-scan contour that is essentially hyperbolic as the Ground Penetrating Radar (GPR) passes over the object. The shape of the hyperbola can be used to determine the angle at which the GPR traveled over the point object.
2009 IEEE International Geoscience and Remote Sensing Symposium, 2009
Subsurface sensing modalities such as Ground Penetrating Radar (GPR) are increasingly being used ... more Subsurface sensing modalities such as Ground Penetrating Radar (GPR) are increasingly being used to assess the condition of aging civil infrastructure by evaluating deterioration within roadways and bridges, and to monitor the security of national borders through the detection of underground tunnels. The need to address these issues is intensifying and, while valuable data is collected using nondestructive evaluation there is urgency for improved understanding and analysis. Simulation of
IGARSS 2008 - 2008 IEEE International Geoscience and Remote Sensing Symposium, 2008
Computational modeling is effectively analyzes the wave propagation and interaction within bridge... more Computational modeling is effectively analyzes the wave propagation and interaction within bridge structures, providing valuable information for sensor selection and placement. It provides a good basis for the inverse problem for defect detection and reconstruction. The finite difference time domain (FDTD) method can be used to model nondestructive wave based sensing using air-coupled ground penetrating radar (GPR). A full 3D
Structural Control for Civil and Infrastructure Engineering - Proceedings of the 3rd International Workshop on Structural Control, 2001
Parameter estimation is commonly referred to as system identification or structural identificatio... more Parameter estimation is commonly referred to as system identification or structural identification. For this purpose, an a priori parametric analytical model that describes the response of a physical system is assumed, and then the system's actual response is measured experimentally. Through some correlation of the analytical model with the measured data the parameters of the analytical model are updated. This paper presents an overview of current challenges in the field of parameter estimation with a specific application to condition assessment of structures. Over the past 10 years, a large number of methods have been proposed to monitor structural performance. Based on deviations of the analytical model from the observed mechanical behavior the changes in the structural parameters are then estimated. Using these parameter estimates, the condition of the structure is diagnosed. Many of these methods have shown promise using simulated or laboratory data, and some have even been successful when applied in a field test. However, the use of parameter estimation techniques for structural condition monitoring has difficulties to become practical for implementation in operating structures. Many of the reasons are economic, but many aspects of this technology are still in need of development in order to make the benefits of this technology apparent to the civil engineering community.
... Javier Morales, Nayda Santiago UPRM Current CenSSIS FPGA Projects 1. Acceleration of the 3D ... more ... Javier Morales, Nayda Santiago UPRM Current CenSSIS FPGA Projects 1. Acceleration of the 3D FDTD Algorithm in Fixed-Point Arithmetic Using Reconfigurable Hardware ▪ Wang Chen, Miriam Leeser, Carey Rappaport 2. Phase Unwrapping for BioBED on the Annapolis ...
ABSTRACT The accuracy of the Born Approximation as a forward model of elastic wave scattering in ... more ABSTRACT The accuracy of the Born Approximation as a forward model of elastic wave scattering in the context of simulating Impact Echo tests of reinforced of concrete is investigated in this paper. The ability of a forward model to realistically simulate the physics of a system can be important when such a model is used as part of an inverse solution. Synthetic data of scattering by air void defects that are typically present in damaged civil engineering structures is generated by a two-dimensional Finite Difference in Time Domain (FDTD) model for elastic wave propagation in an infinite, homogeneous and isotropic concrete medium. Horizontal elongated cracks and air voids with compact shapes are considered in this study for comparison between the synthetic and the Born approximated data. It is observed that the Born Approximation simulates a compact air void better than a horizontal elongated one. This knowledge provides insight on Born Approximation as part of an inverse solution towards imaging of air voids of various shapes in a damaged civil engineering structure.
Research in Nondestructive Evaluation, 2009
Ground penetrating radar (GPR) for nondestructive testing is a relatively young technology, espec... more Ground penetrating radar (GPR) for nondestructive testing is a relatively young technology, especially with application to civil infrastructure such as bridges and roadways.
Computer-Aided Civil and Infrastructure Engineering, 2007
Ground penetrating radar (GPR) has become a viable technology for non-destructive condition asses... more Ground penetrating radar (GPR) has become a viable technology for non-destructive condition assessment of reinforced concrete structures. Interpretation of the radar signal is typically performed through preliminary filtering techniques and interpretation is based on viewing numerous signals in the form of a scan. Although anomalies can be evident in the scanned image, quantification and interpretation of the main issue remain ambiguous. This article presents the ambiguity and common methods of interpretation based on response amplitude and travel time. An integrated medium is developed and used as a forward modeling tool to generate a realistic radar reflection of a reinforced concrete bridge deck with defects. A healthy deck reflection is obtained from a separate model and is combined with an inverse solution to quantifiably estimate unknown subsurface properties such as layer thickness and dielectric constants of subsurface materials evident in the realistic radar trace as well as. The forward modeling tool and associated model based assessment provides an objective computational alternative to the interpretation of scanned images.
Research in Nondestructive Evaluation, 2009
Computational modeling is beneficial in the preparation for nondestructive wave-based sensing. Fo... more Computational modeling is beneficial in the preparation for nondestructive wave-based sensing. Forward models, which can be implemented through a variety of computational modeling techniques, enable parametric evaluations to assess the functionality of a sensor under different conditions, and are integral to the solution of the inverse problem. The focus of this article is on the comparison of two-dimensional (2D) and