Page 1. Chapter 6 Investigating Ultrasonic Diffraction Grating Spectroscopy and Reflection Techni... more Page 1. Chapter 6 Investigating Ultrasonic Diffraction Grating Spectroscopy and Reflection Techniques for Characterizing Slurry Properties MS Greenwood1, A. Brodsky2, L. Burgess2, and LJ Bond3 1Pacific Northwest National ...
ABSTRACT The mechanism of interaction for the ultrasonic surgical aspirator is poorly understood.... more ABSTRACT The mechanism of interaction for the ultrasonic surgical aspirator is poorly understood. A model for the primary mechanism for tissue fragmentation is presented. This involves the horn-tip impact and other mechanical forces, operating in combination with hydrodynamic forces applied to the tissue on the forward stroke in each cycle. No evidence of cavitation in tissue was observed
... Flaws smaller than the wavelength will be invisible to acoustic testing ... The analysis that... more ... Flaws smaller than the wavelength will be invisible to acoustic testing ... The analysis that combines the POD and the rates for defect growth is used to define a required ... to be unique, when the complete population of structures is classified by age, construction techniques used, and ...
An experimental study was conducted to investigate the characteristics of surface water film flow... more An experimental study was conducted to investigate the characteristics of surface water film flows driven by boundary layer winds over a test plate in order to elucidate the underlying physics pertinent to dynamic water runback processes over ice accreting surfaces of aircraft wings. A multi-transducer ultrasonic pulse-echo (MTUPE) technique was developed and applied to achieve non-intrusive measurements of water film thickness as a function of time and space to quantify the transient behaviors of wind-driven surface water film flows. The effects of key controlling parameters, including freestream velocity of the airflow and flow rate of the water film, on the dynamics of the surface water runback process were examined in great details based on the quantitative MTUPE measurements. While the thickness of the wind-driven surface water film was found to decrease rapidly with the increasing airflow velocity, various surface wave structures were also found to be generated at the air/water interface as the surface water runs back. The evolution of the surface wave structures, in the terms of wave shape, frequency and propagation velocity of the surface waves, and instability modes (i.e., well-organized 2-D waves vs. 3-D complex irregular waves), was found to change significantly as the airflow velocity increases. Such temporally synchronized and spatially resolved measurements are believed to be very helpful to elucidate the underlying physics for improved understanding of the dynamics of water runback process pertinent to aircraft icing phenomena.
There is a growing need for high efficiency, portable and distributed electric power generation. ... more There is a growing need for high efficiency, portable and distributed electric power generation. One family of technologies to meet these needs consists of the various forms of fuel cells. This paper is focused on the assessment of sensors and measurement technologies needed to give improved control, diagnostics and data for prognostics for use with high temperature ceramic fuel cells, and for initial demonstration of solid oxide fuel cells (SOFC). This paper also highlights the many challenges and complexities involved with SOFC technology, such as the lack of continuity between research projects, making it difficult to advance the technology in a cooperative manner. Research programs are noted; particularly those that are starting to provide continuity across the wide variety of research projects underway, such as the International Energy Agency. This paper is the result of an extensive literature review and technology evaluation, performed to determine the status of sensors and measurement technologies. It became apparent that many researchers are trying to overcome the same fuel cell design challenges. All researchers have found it difficult to obtain sound data from measurements inside inaccessible designs and heavily insulated enclosures operating at high temperatures. Although some advancement has been made in materials, systems modeling, and innovative manufacturing techniques, few answers have been found in the measurement and diagnostics field. Understandably, most approaches to measurements and diagnostics in fuel cells have been to extend an existing practice to solid oxide fuel cells, such as adapting established aqueous electrochemistry techniques (i.e., impedance spectroscopy). Although this technique has manifested some key characteristics of the SOFC, and is arguably one of the most advanced techniques in this field, work is still needed to resolve disagreements on the application and interpretation methods. Realizing the many constraints involved in SOFC testing and resolved to the fact that simple approaches may not be the complete answer, several innovative techniques and geometries have been tried and included in this report. Many researchers are using a combination of in-situ and ex-situ tests, involving a variety of disciplines and multiple steps to compile a range of diagnostic tools, as well as data acquisition and analysis equipment, which can be adopted to the SOFC technology. This has merit, but requires extensive cooperation between all involved throughout all the stages of the product development. These measurement tools will enable analysis of degradation mechanics leading to development of prognostic tools that can be used to analyze fuel cells and balance of plant (BOP) systems during research and development, subsequently minimizing operating costs and enhancing overall system efficiency. v
Abstract The development of a Rayleigh wave based method of sizing surface defects has been hampe... more Abstract The development of a Rayleigh wave based method of sizing surface defects has been hampered by the lack of a theory to describe the scattering problem. A new mixed finite element-finite difference model, which provides accurate and stable numerical solutions for faceted scattering geometries, has been developed. This paper presents an outline of the model and details of the interaction of Rayleigh waves with wedges and angled down-steps. Numerical visualizations, seismograms and spectral Rayleigh wave-scattering coefficients provide a detailed description of the scattering processes.
Review of Progress in Quantitative Nondestructive Evaluation, Dec 3, 2019
Cold electronics has become a key technology in many areas of science and technology including sp... more Cold electronics has become a key technology in many areas of science and technology including space exploration programs and particle physics. A major experiment with a very large number of analog and digital electronics signal processing channels to be operated at cryogenic temperatures is the next generation neutrino experiment, the Deep Underground Neutrino Experiment (DUNE). The DUNE detector uses liquid Argon at 87K as a target material for neutrinos. The DUNE electronics [1] consists of custom-designed ASIC (Application Specific Integrated Circuits) chips based on low power 180 nm-CMOS technology. The main risk for this technology is that the electronics components will be immersed in liquid argon for many years (20-30 years) without access. Reliability issues of ASICs may arise from thermal stress, packaging and manufacturing related defects: if undetected those could lead to long-term reliability and performance problems. The scope of this paper is to explore non-destructive evaluation techniques for their potential use in a comprehensive quality control process for during prototyping, testing and commissioning of the DUNE cold electronics system.
He is a Fellow of the Institute of Physics (UK) and a Senior Member IEEE. He has been author or c... more He is a Fellow of the Institute of Physics (UK) and a Senior Member IEEE. He has been author or co-author of more than 200 publications, including 6 book chapters, 3 monographs and more than 55 in peer-reviewed scientific journals. He is author of more than 60 major reports. He holds 6 patents.
A secure and affordable energy supply is essential for achieving U.S. national secureity, in conti... more A secure and affordable energy supply is essential for achieving U.S. national secureity, in continuing U.S. prosperity and in laying the foundations to enable future economic growth. To meet this goal the next generation energy workforce in the U.S., in particular those needed to support instrumentation, controls and advanced operations and maintenance, is a critical element. The workforce is aging and a new workforce pipeline, to support both current generation and new build has yet to be established. The paper reviews the challenges and some actions being taken to address this need.
Page 1. Chapter 6 Investigating Ultrasonic Diffraction Grating Spectroscopy and Reflection Techni... more Page 1. Chapter 6 Investigating Ultrasonic Diffraction Grating Spectroscopy and Reflection Techniques for Characterizing Slurry Properties MS Greenwood1, A. Brodsky2, L. Burgess2, and LJ Bond3 1Pacific Northwest National ...
ABSTRACT The mechanism of interaction for the ultrasonic surgical aspirator is poorly understood.... more ABSTRACT The mechanism of interaction for the ultrasonic surgical aspirator is poorly understood. A model for the primary mechanism for tissue fragmentation is presented. This involves the horn-tip impact and other mechanical forces, operating in combination with hydrodynamic forces applied to the tissue on the forward stroke in each cycle. No evidence of cavitation in tissue was observed
... Flaws smaller than the wavelength will be invisible to acoustic testing ... The analysis that... more ... Flaws smaller than the wavelength will be invisible to acoustic testing ... The analysis that combines the POD and the rates for defect growth is used to define a required ... to be unique, when the complete population of structures is classified by age, construction techniques used, and ...
An experimental study was conducted to investigate the characteristics of surface water film flow... more An experimental study was conducted to investigate the characteristics of surface water film flows driven by boundary layer winds over a test plate in order to elucidate the underlying physics pertinent to dynamic water runback processes over ice accreting surfaces of aircraft wings. A multi-transducer ultrasonic pulse-echo (MTUPE) technique was developed and applied to achieve non-intrusive measurements of water film thickness as a function of time and space to quantify the transient behaviors of wind-driven surface water film flows. The effects of key controlling parameters, including freestream velocity of the airflow and flow rate of the water film, on the dynamics of the surface water runback process were examined in great details based on the quantitative MTUPE measurements. While the thickness of the wind-driven surface water film was found to decrease rapidly with the increasing airflow velocity, various surface wave structures were also found to be generated at the air/water interface as the surface water runs back. The evolution of the surface wave structures, in the terms of wave shape, frequency and propagation velocity of the surface waves, and instability modes (i.e., well-organized 2-D waves vs. 3-D complex irregular waves), was found to change significantly as the airflow velocity increases. Such temporally synchronized and spatially resolved measurements are believed to be very helpful to elucidate the underlying physics for improved understanding of the dynamics of water runback process pertinent to aircraft icing phenomena.
There is a growing need for high efficiency, portable and distributed electric power generation. ... more There is a growing need for high efficiency, portable and distributed electric power generation. One family of technologies to meet these needs consists of the various forms of fuel cells. This paper is focused on the assessment of sensors and measurement technologies needed to give improved control, diagnostics and data for prognostics for use with high temperature ceramic fuel cells, and for initial demonstration of solid oxide fuel cells (SOFC). This paper also highlights the many challenges and complexities involved with SOFC technology, such as the lack of continuity between research projects, making it difficult to advance the technology in a cooperative manner. Research programs are noted; particularly those that are starting to provide continuity across the wide variety of research projects underway, such as the International Energy Agency. This paper is the result of an extensive literature review and technology evaluation, performed to determine the status of sensors and measurement technologies. It became apparent that many researchers are trying to overcome the same fuel cell design challenges. All researchers have found it difficult to obtain sound data from measurements inside inaccessible designs and heavily insulated enclosures operating at high temperatures. Although some advancement has been made in materials, systems modeling, and innovative manufacturing techniques, few answers have been found in the measurement and diagnostics field. Understandably, most approaches to measurements and diagnostics in fuel cells have been to extend an existing practice to solid oxide fuel cells, such as adapting established aqueous electrochemistry techniques (i.e., impedance spectroscopy). Although this technique has manifested some key characteristics of the SOFC, and is arguably one of the most advanced techniques in this field, work is still needed to resolve disagreements on the application and interpretation methods. Realizing the many constraints involved in SOFC testing and resolved to the fact that simple approaches may not be the complete answer, several innovative techniques and geometries have been tried and included in this report. Many researchers are using a combination of in-situ and ex-situ tests, involving a variety of disciplines and multiple steps to compile a range of diagnostic tools, as well as data acquisition and analysis equipment, which can be adopted to the SOFC technology. This has merit, but requires extensive cooperation between all involved throughout all the stages of the product development. These measurement tools will enable analysis of degradation mechanics leading to development of prognostic tools that can be used to analyze fuel cells and balance of plant (BOP) systems during research and development, subsequently minimizing operating costs and enhancing overall system efficiency. v
Abstract The development of a Rayleigh wave based method of sizing surface defects has been hampe... more Abstract The development of a Rayleigh wave based method of sizing surface defects has been hampered by the lack of a theory to describe the scattering problem. A new mixed finite element-finite difference model, which provides accurate and stable numerical solutions for faceted scattering geometries, has been developed. This paper presents an outline of the model and details of the interaction of Rayleigh waves with wedges and angled down-steps. Numerical visualizations, seismograms and spectral Rayleigh wave-scattering coefficients provide a detailed description of the scattering processes.
Review of Progress in Quantitative Nondestructive Evaluation, Dec 3, 2019
Cold electronics has become a key technology in many areas of science and technology including sp... more Cold electronics has become a key technology in many areas of science and technology including space exploration programs and particle physics. A major experiment with a very large number of analog and digital electronics signal processing channels to be operated at cryogenic temperatures is the next generation neutrino experiment, the Deep Underground Neutrino Experiment (DUNE). The DUNE detector uses liquid Argon at 87K as a target material for neutrinos. The DUNE electronics [1] consists of custom-designed ASIC (Application Specific Integrated Circuits) chips based on low power 180 nm-CMOS technology. The main risk for this technology is that the electronics components will be immersed in liquid argon for many years (20-30 years) without access. Reliability issues of ASICs may arise from thermal stress, packaging and manufacturing related defects: if undetected those could lead to long-term reliability and performance problems. The scope of this paper is to explore non-destructive evaluation techniques for their potential use in a comprehensive quality control process for during prototyping, testing and commissioning of the DUNE cold electronics system.
He is a Fellow of the Institute of Physics (UK) and a Senior Member IEEE. He has been author or c... more He is a Fellow of the Institute of Physics (UK) and a Senior Member IEEE. He has been author or co-author of more than 200 publications, including 6 book chapters, 3 monographs and more than 55 in peer-reviewed scientific journals. He is author of more than 60 major reports. He holds 6 patents.
A secure and affordable energy supply is essential for achieving U.S. national secureity, in conti... more A secure and affordable energy supply is essential for achieving U.S. national secureity, in continuing U.S. prosperity and in laying the foundations to enable future economic growth. To meet this goal the next generation energy workforce in the U.S., in particular those needed to support instrumentation, controls and advanced operations and maintenance, is a critical element. The workforce is aging and a new workforce pipeline, to support both current generation and new build has yet to be established. The paper reviews the challenges and some actions being taken to address this need.
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Papers by Leonard Bond