Robert Hay - Academia.edu (original) (raw)

Papers by Robert Hay

Fatigue is one of the most critical problems for steel bridges as well as for any steel structure... more Fatigue is one of the most critical problems for steel bridges as well as for any steel structures that needs to be considered during design and operation. The objectives of this study are to explore monitoring technologies, and to develop effective structural and data analysis strategies as well as implementation recommendations for evaluating performance of fatigue-sensitive details and retrofits in steel bridges. Acoustic emission (AE) was selected as a candidate inspection technology, and a monitoring system was installed on a bridge. In general, the performance of the monitoring system and associated software is satisfactory. The majority of AE monitoring challenges are associated with AE data analysis and interpretation of results. In this study, cluster analysis and non-linear mapping signal analysis techniques are used to group AE data with similar waveform characteristics. The presence of the signals that resemble the characteristics of crack opening signals, noise, and structural resonance is identified through waveform analysis. Once the presence of crack opening signals is confirmed, the source location plots are utilized to assess the concentration and the level of activity at the locations of interest. A significant difference is observed in the fatigue life calculated using measured stress, and the stresses calculated using finite element models loaded with a fatigue truck. Hence, a two-tier implementation process is recommended. Tier I process includes the assessment of bridges with repaired details. Tier II process recommends evaluating the entire bridge population with fatigue-sensitive details. Additional recommendations include implementing AE data interpretation capability in an on-line system to provide reliable input with minimal interpretation requirements for inspection-based maintenance management.

Abstract : The report describes in detail recent work on studies of plastic deformation of body-c... more Abstract : The report describes in detail recent work on studies of plastic deformation of body-centered cubic transition metals in the microyield regime and the vicinity of yielding. (Author)

2009 Joint Rail Conference, 2009

As part of an infrastructure subject to increased magnitude and frequency of loads, railroad trac... more As part of an infrastructure subject to increased magnitude and frequency of loads, railroad track systems require regular inspection to assure high reliability for the safety of the public and passengers and the safe and efficient movement of goods. Unattended work hardened layers on the surface of the rails are operational hazards due to the inevitability of rolling contact fatigue cracks. A novel method utilizing the higher order surface waves, also called as Sezawa waves, has been used to detect and characterize the work hardened layer in rails. The technique involves generating Sezawa waves using contact ultrasonic transducers and monitoring the cut-off frequency of these waves. Results from hardness tests and metallographic analyses on the work hardened layers are also reported. The tests using the Sezawa wave technology demonstrated the ability to interrogate and resolve traffic-hardened layers in the depth ranges of 0–1 mm, 1–3 mm, and 4–7 mm. The minimum Brinell Hardness (HB) gradient, between the hardened layer and underlying rail, required to support Sezawa wave generation was also investigated and determined to be greater than 20 HB.Copyright © 2009 by ASME

Microelectronics Reliability, 1979

A new methodology is developed for the analysis and prevention of failure in loadbearing structur... more A new methodology is developed for the analysis and prevention of failure in loadbearing structures and machine components subject to several competing or complementary deterioration modes. Top-down modeling is used to integrate several specialist disciplines into a multidisciplinary model. Both mechanistic and probabilistic aspects of the system under study are analyzed. Constitutive equations governing static equilibrium behavior of the structure are decoupled from the deterioration (irreversible) phenomena and separate formulations developed for the equilibrium and irreversible phenomena. The overall mechanistic formulation for the physical system under study is then obtained by using the formulations for the deterioration phenomena as feedbacks into transfer functions describing the equilibrium phenomena. This mechanistic formulation is amenable to solution by numerical-analog computer codes. An overall dynamic probabilistic formulation is then obtained directly from the mechanistic equations rather than independently by the reverse, bottom-up approach. The resulting set of dynamic probabilistic formulations is also amenable to solution by numerical-analog techniques. The model and the methodology are implementable for a great variety of analyses including design, materials selection, inspection optimization, information management schemes and cost-benefit analyses. Failure modes treated in this study include corrosion, corrosion fatigue, brittle fracture, and deflection using an example from the papermaking industry.

NDT & E International, 1992

Canadian Journal of Civil Engineering, 1974

Fracture mechanics is a design philosophy which has evolved over the three decades since World Wa... more Fracture mechanics is a design philosophy which has evolved over the three decades since World War II and is beginning to find use in standard design. This concept for fracture-safe design recognizes the general existence of flaws in engineering materials and provides an analytical basis for prediction of the mechanical behavior of a structure constructed of a flaw-bearing material.This article reviews the basic concepts of fracture mechanics. The material parameters, such as plane-strain fracture toughness KIc are derived and the experimental technique for obtaining KIc is presented.The impact of fracture mechanics on engineering practice, i.e. material selection and fabrication, mechanical and structural design, and nondestructive testing is also examined.

Brain Topography, 1993

Automated artifact classification of quantified EEG (QEEG) epochs from 9 males using linear discr... more Automated artifact classification of quantified EEG (QEEG) epochs from 9 males using linear discriminant mmlysis showed greater than 85% agreement with judges' opinions. These results were replicated (n=600 epochs for each sample). Testing the entire sample (n=5800) illustrated reliable eye artifact (94%) but reduced muscle artifact classification (70%) accuracy. Agreement was lowest in the case of more subtle forms of muscle artifact 0.e., low amplitude muscle), however, less than 4% of these were wrongly classified as non-artifact. Improved data collection techniques retaining high frequency energies are anticipated to improve muscle artifact recogrfition, Results indicate that low levels of artifact contamination would result when only those epochs classified as non-artifact were accepted for inclusion in further analysis.

Review of Progress in Quantitative Nondestructive Evaluation, 1990

This computer-aided automated ultrasonic inspection and data collection system is designed for in... more This computer-aided automated ultrasonic inspection and data collection system is designed for inspection of submarine pressure-hull parent plate and weldments. At present, field inspectors carry out unassisted inspections in which each indication is treated as an equivalent type of defect. Accordingly, the condemnation limit is based on the most serious defect type. A permanent record of inspections and the ability to identify defects according to type are the first priorities in overhauling the outdated submarine condemnation criteria. With reliable inspection and an interpretation of the significance of real defect type, comprehensive new criteria can be generated which will eliminate wasteful defect removal. As a consequence, submarine refit schedules should be shortened considerably. The system provides computer assistance to an inspector during manual ultrasonic inspection in four ways: * permanently recording the defect indications * mapping the location of flaws * displaying standard ultrasonic information during the test * sorting the indications as to type of flaw, with particular reference to cracks, slag and porosity (1). The system places substantial computing power at the work station to permit automatic data entry of raw ultrasonic signal data and documentation of procedures, setup and other information needed for subsequent analysis and for archival storage. This computing power also allowed other on-line computations including continuous determination of the transducer location in x-y format and on-line computation and decision-making as an assist to the inspector. In addition, a capability was required to store data for more detailed analysis by specialists in the NDT laboratory. Accordingly, waveform and x-y coordinates are simultaneously recorded upon operator command for later retrieval. SYSTEM OVERVIEW The system, designated APHIUS (Automated Pressure Hull Intelligent Ultrasonic System) combines a computer-based ultrasonic development and analysis

The rapid evolution of information related to hydrogen safety is multidimensional ranging from de... more The rapid evolution of information related to hydrogen safety is multidimensional ranging from developing codes and standards to CFD simulations and experimental studies of hydrogen releases to a variety of risk assessment approaches. This information needs to be transformed into system design, risk decision-making and first responder tools for use by hydrogen community stakeholders. The Canadian Transportation Fuel Cell Alliance (CTFCA) has developed HySTARtm, an interactive Hydrogen Safety, Training And Risk System. The HySTARtm user interacts with a Web-based 3-D graphical user interface to input hydrogen system configurations. The system includes a Codes and Standards Expert System that identifies the applicable codes and standards in a number of national jurisdictions that apply to the facility and its components. A Siting Compliance and Planning Expert System assesses compliance with clearance distance requirements in these jurisdictions. Incorporating the results of other CTF...

The rapid evolution of information related to hydrogen safety is multidimensional ranging from de... more The rapid evolution of information related to hydrogen safety is multidimensional ranging from developing codes and standards to CFD simulations and experimental studies of hydrogen releases to a variety of risk assessment approaches. This information needs to be transformed into system design, risk decision-making and first responder tools for use by hydrogen community stakeholders. The Canadian Transportation Fuel Cell Alliance (CTFCA) has developed HySTARtm, an interactive Hydrogen Safety, Training And Risk System. The HySTARtm user interacts with a Web-based 3-D graphical user interface to input hydrogen system configurations. The system includes a Codes and Standards Expert System that identifies the applicable codes and standards in a number of national jurisdictions that apply to the facility and its components. A Siting Compliance and Planning Expert System assesses compliance with clearance distance requirements in these jurisdictions. Incorporating the results of other CTF...

2009 Joint Rail Conference, 2009

2009 Joint Rail Conference, 2009

Applications of Artificial Intelligence IX, 1991

Oncogene, 2006

POU2F3 (OCT11, Skn-1a) is a keratinocyte-specific POU transcription factor whose expression is ti... more POU2F3 (OCT11, Skn-1a) is a keratinocyte-specific POU transcription factor whose expression is tied to squamous epithelial stratification. It is also a candidate tumor suppressor gene in cervical cancer (CC) because it lies in a critical loss of heterozygosity region on11q23.3 in that cancer, and its expression is lost in more than 50% of CC tumors and cell lines. We now report that the loss of POU2F3 expression is tied to the hypermethylation of CpG islands in the POU2F3 promoter. Bisulfite sequencing analysis revealed that methylation of specific CpG sites (À287 to À70 bp) correlated with POU2F3 expression, which could be reactivated with a demethylating agent. Combined bisulfite restriction analysis revealed aberrant methylation of the POU2F3 promoter in 18 of 46 (39%) cervical tumors but never in normal epithelium. POU2F3 expression was downregulated and inversely correlated with promoter hypermethylation in 10 out of 11 CC cell lines. Immunohistochemical analysis on a cervical tissue microarray detected POU2F3 protein in the epithelium above the basal layer. As the disease progressed, expression also decreased, especially in invasive squamous cell cancer (70% loss). Thus, aberrant DNA methylation of the CpG island in POU2F3 promoter appears to play a key role in silencing this gene expression in human CC. The results suggested that POU2F3 might be one of the CC-related tumor suppressor genes, which are disrupted by both epigenetic and genetic mechanisms.

Housing & Building National Research Center - HBRC-ISHMII - 2nd International Conference on Bridge Testing, Monitoring & Assessment

Acoustic emission is one of an ensemble of methods for the condition assessment of fracture criti... more Acoustic emission is one of an ensemble of methods for the condition assessment of fracture critical bridge members. This inspection method provides a unique input to risk-informed maintenance management and planning and to prescribe maintenance follow up actions with major financial implications. Knowledgeable bridge owner/operators over the last thirty years have used acoustic emission in over 500 bridge applications worldwide; wherein acoustic emission experts provide input into their engineering and economic planning consistent with established codes and standards. This paper outlines the acoustic emission approach and its application in bridge risk-informed maintenance management.

Fatigue is one of the most critical problems for steel bridges as well as for any steel structure... more Fatigue is one of the most critical problems for steel bridges as well as for any steel structures that needs to be considered during design and operation. The objectives of this study are to explore monitoring technologies, and to develop effective structural and data analysis strategies as well as implementation recommendations for evaluating performance of fatigue-sensitive details and retrofits in steel bridges. Acoustic emission (AE) was selected as a candidate inspection technology, and a monitoring system was installed on a bridge. In general, the performance of the monitoring system and associated software is satisfactory. The majority of AE monitoring challenges are associated with AE data analysis and interpretation of results. In this study, cluster analysis and non-linear mapping signal analysis techniques are used to group AE data with similar waveform characteristics. The presence of the signals that resemble the characteristics of crack opening signals, noise, and structural resonance is identified through waveform analysis. Once the presence of crack opening signals is confirmed, the source location plots are utilized to assess the concentration and the level of activity at the locations of interest. A significant difference is observed in the fatigue life calculated using measured stress, and the stresses calculated using finite element models loaded with a fatigue truck. Hence, a two-tier implementation process is recommended. Tier I process includes the assessment of bridges with repaired details. Tier II process recommends evaluating the entire bridge population with fatigue-sensitive details. Additional recommendations include implementing AE data interpretation capability in an on-line system to provide reliable input with minimal interpretation requirements for inspection-based maintenance management.

Abstract : The report describes in detail recent work on studies of plastic deformation of body-c... more Abstract : The report describes in detail recent work on studies of plastic deformation of body-centered cubic transition metals in the microyield regime and the vicinity of yielding. (Author)

2009 Joint Rail Conference, 2009

As part of an infrastructure subject to increased magnitude and frequency of loads, railroad trac... more As part of an infrastructure subject to increased magnitude and frequency of loads, railroad track systems require regular inspection to assure high reliability for the safety of the public and passengers and the safe and efficient movement of goods. Unattended work hardened layers on the surface of the rails are operational hazards due to the inevitability of rolling contact fatigue cracks. A novel method utilizing the higher order surface waves, also called as Sezawa waves, has been used to detect and characterize the work hardened layer in rails. The technique involves generating Sezawa waves using contact ultrasonic transducers and monitoring the cut-off frequency of these waves. Results from hardness tests and metallographic analyses on the work hardened layers are also reported. The tests using the Sezawa wave technology demonstrated the ability to interrogate and resolve traffic-hardened layers in the depth ranges of 0–1 mm, 1–3 mm, and 4–7 mm. The minimum Brinell Hardness (HB) gradient, between the hardened layer and underlying rail, required to support Sezawa wave generation was also investigated and determined to be greater than 20 HB.Copyright © 2009 by ASME

Microelectronics Reliability, 1979

A new methodology is developed for the analysis and prevention of failure in loadbearing structur... more A new methodology is developed for the analysis and prevention of failure in loadbearing structures and machine components subject to several competing or complementary deterioration modes. Top-down modeling is used to integrate several specialist disciplines into a multidisciplinary model. Both mechanistic and probabilistic aspects of the system under study are analyzed. Constitutive equations governing static equilibrium behavior of the structure are decoupled from the deterioration (irreversible) phenomena and separate formulations developed for the equilibrium and irreversible phenomena. The overall mechanistic formulation for the physical system under study is then obtained by using the formulations for the deterioration phenomena as feedbacks into transfer functions describing the equilibrium phenomena. This mechanistic formulation is amenable to solution by numerical-analog computer codes. An overall dynamic probabilistic formulation is then obtained directly from the mechanistic equations rather than independently by the reverse, bottom-up approach. The resulting set of dynamic probabilistic formulations is also amenable to solution by numerical-analog techniques. The model and the methodology are implementable for a great variety of analyses including design, materials selection, inspection optimization, information management schemes and cost-benefit analyses. Failure modes treated in this study include corrosion, corrosion fatigue, brittle fracture, and deflection using an example from the papermaking industry.

NDT & E International, 1992

Canadian Journal of Civil Engineering, 1974

Fracture mechanics is a design philosophy which has evolved over the three decades since World Wa... more Fracture mechanics is a design philosophy which has evolved over the three decades since World War II and is beginning to find use in standard design. This concept for fracture-safe design recognizes the general existence of flaws in engineering materials and provides an analytical basis for prediction of the mechanical behavior of a structure constructed of a flaw-bearing material.This article reviews the basic concepts of fracture mechanics. The material parameters, such as plane-strain fracture toughness KIc are derived and the experimental technique for obtaining KIc is presented.The impact of fracture mechanics on engineering practice, i.e. material selection and fabrication, mechanical and structural design, and nondestructive testing is also examined.

Brain Topography, 1993

Automated artifact classification of quantified EEG (QEEG) epochs from 9 males using linear discr... more Automated artifact classification of quantified EEG (QEEG) epochs from 9 males using linear discriminant mmlysis showed greater than 85% agreement with judges' opinions. These results were replicated (n=600 epochs for each sample). Testing the entire sample (n=5800) illustrated reliable eye artifact (94%) but reduced muscle artifact classification (70%) accuracy. Agreement was lowest in the case of more subtle forms of muscle artifact 0.e., low amplitude muscle), however, less than 4% of these were wrongly classified as non-artifact. Improved data collection techniques retaining high frequency energies are anticipated to improve muscle artifact recogrfition, Results indicate that low levels of artifact contamination would result when only those epochs classified as non-artifact were accepted for inclusion in further analysis.

Review of Progress in Quantitative Nondestructive Evaluation, 1990

This computer-aided automated ultrasonic inspection and data collection system is designed for in... more This computer-aided automated ultrasonic inspection and data collection system is designed for inspection of submarine pressure-hull parent plate and weldments. At present, field inspectors carry out unassisted inspections in which each indication is treated as an equivalent type of defect. Accordingly, the condemnation limit is based on the most serious defect type. A permanent record of inspections and the ability to identify defects according to type are the first priorities in overhauling the outdated submarine condemnation criteria. With reliable inspection and an interpretation of the significance of real defect type, comprehensive new criteria can be generated which will eliminate wasteful defect removal. As a consequence, submarine refit schedules should be shortened considerably. The system provides computer assistance to an inspector during manual ultrasonic inspection in four ways: * permanently recording the defect indications * mapping the location of flaws * displaying standard ultrasonic information during the test * sorting the indications as to type of flaw, with particular reference to cracks, slag and porosity (1). The system places substantial computing power at the work station to permit automatic data entry of raw ultrasonic signal data and documentation of procedures, setup and other information needed for subsequent analysis and for archival storage. This computing power also allowed other on-line computations including continuous determination of the transducer location in x-y format and on-line computation and decision-making as an assist to the inspector. In addition, a capability was required to store data for more detailed analysis by specialists in the NDT laboratory. Accordingly, waveform and x-y coordinates are simultaneously recorded upon operator command for later retrieval. SYSTEM OVERVIEW The system, designated APHIUS (Automated Pressure Hull Intelligent Ultrasonic System) combines a computer-based ultrasonic development and analysis

The rapid evolution of information related to hydrogen safety is multidimensional ranging from de... more The rapid evolution of information related to hydrogen safety is multidimensional ranging from developing codes and standards to CFD simulations and experimental studies of hydrogen releases to a variety of risk assessment approaches. This information needs to be transformed into system design, risk decision-making and first responder tools for use by hydrogen community stakeholders. The Canadian Transportation Fuel Cell Alliance (CTFCA) has developed HySTARtm, an interactive Hydrogen Safety, Training And Risk System. The HySTARtm user interacts with a Web-based 3-D graphical user interface to input hydrogen system configurations. The system includes a Codes and Standards Expert System that identifies the applicable codes and standards in a number of national jurisdictions that apply to the facility and its components. A Siting Compliance and Planning Expert System assesses compliance with clearance distance requirements in these jurisdictions. Incorporating the results of other CTF...

The rapid evolution of information related to hydrogen safety is multidimensional ranging from de... more The rapid evolution of information related to hydrogen safety is multidimensional ranging from developing codes and standards to CFD simulations and experimental studies of hydrogen releases to a variety of risk assessment approaches. This information needs to be transformed into system design, risk decision-making and first responder tools for use by hydrogen community stakeholders. The Canadian Transportation Fuel Cell Alliance (CTFCA) has developed HySTARtm, an interactive Hydrogen Safety, Training And Risk System. The HySTARtm user interacts with a Web-based 3-D graphical user interface to input hydrogen system configurations. The system includes a Codes and Standards Expert System that identifies the applicable codes and standards in a number of national jurisdictions that apply to the facility and its components. A Siting Compliance and Planning Expert System assesses compliance with clearance distance requirements in these jurisdictions. Incorporating the results of other CTF...

2009 Joint Rail Conference, 2009

2009 Joint Rail Conference, 2009

Applications of Artificial Intelligence IX, 1991

Oncogene, 2006

POU2F3 (OCT11, Skn-1a) is a keratinocyte-specific POU transcription factor whose expression is ti... more POU2F3 (OCT11, Skn-1a) is a keratinocyte-specific POU transcription factor whose expression is tied to squamous epithelial stratification. It is also a candidate tumor suppressor gene in cervical cancer (CC) because it lies in a critical loss of heterozygosity region on11q23.3 in that cancer, and its expression is lost in more than 50% of CC tumors and cell lines. We now report that the loss of POU2F3 expression is tied to the hypermethylation of CpG islands in the POU2F3 promoter. Bisulfite sequencing analysis revealed that methylation of specific CpG sites (À287 to À70 bp) correlated with POU2F3 expression, which could be reactivated with a demethylating agent. Combined bisulfite restriction analysis revealed aberrant methylation of the POU2F3 promoter in 18 of 46 (39%) cervical tumors but never in normal epithelium. POU2F3 expression was downregulated and inversely correlated with promoter hypermethylation in 10 out of 11 CC cell lines. Immunohistochemical analysis on a cervical tissue microarray detected POU2F3 protein in the epithelium above the basal layer. As the disease progressed, expression also decreased, especially in invasive squamous cell cancer (70% loss). Thus, aberrant DNA methylation of the CpG island in POU2F3 promoter appears to play a key role in silencing this gene expression in human CC. The results suggested that POU2F3 might be one of the CC-related tumor suppressor genes, which are disrupted by both epigenetic and genetic mechanisms.

Housing & Building National Research Center - HBRC-ISHMII - 2nd International Conference on Bridge Testing, Monitoring & Assessment

Acoustic emission is one of an ensemble of methods for the condition assessment of fracture criti... more Acoustic emission is one of an ensemble of methods for the condition assessment of fracture critical bridge members. This inspection method provides a unique input to risk-informed maintenance management and planning and to prescribe maintenance follow up actions with major financial implications. Knowledgeable bridge owner/operators over the last thirty years have used acoustic emission in over 500 bridge applications worldwide; wherein acoustic emission experts provide input into their engineering and economic planning consistent with established codes and standards. This paper outlines the acoustic emission approach and its application in bridge risk-informed maintenance management.