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Full-Text Articles in Engineering
A Novel Method For Determination Of Dielectric Properties Of Materials Using A Combined Embedded Modulated Scattering And Near-Field Microwave Techniques-Part Ii: Dielectric Property Recalculation, R. Zoughi, Dana Hughes
A Novel Method For Determination Of Dielectric Properties Of Materials Using A Combined Embedded Modulated Scattering And Near-Field Microwave Techniques-Part Ii: Dielectric Property Recalculation, R. Zoughi, Dana Hughes
Electrical and Computer Engineering Faculty Research & Creative Works
The use of combined embedded modulated scattering technique and near-field microwave nondestructive testing techniques is investigated as a novel method for evaluating the dielectric properties of a material. The forward formulation for determining the reflection coefficient at the aperture of a waveguide radiating into a dielectric half-space in which a PIN diode-loaded dipole (i.e., modulated scattering technique probe) is embedded was presented in Part I of this paper. Here, in Part II, the recalculation of the dielectric properties, using the results of the forward model, is presented along with some associated experimental results.
A Novel Method For Determination Of Dielectric Properties Of Materials Using A Combined Embedded Modulated Scattering And Near-Field Microwave Techniques-Part I: Forward Model, Dana M. Hughes, R. Zoughi
A Novel Method For Determination Of Dielectric Properties Of Materials Using A Combined Embedded Modulated Scattering And Near-Field Microwave Techniques-Part I: Forward Model, Dana M. Hughes, R. Zoughi
Electrical and Computer Engineering Faculty Research & Creative Works
The use of combined embedded modulated scattering technique and near-field microwave nondestructive testing techniques is investigated as a novel method for evaluating the dielectric properties of a material. The forward formulation for determining the reflection coefficient at the aperture of a waveguide radiating into a dielectric half-space in which a PIN diode-loaded dipole (i.e., modulated scattering technique probe) is embedded is presented. This formulation is based upon calculating the near-field coupling between the waveguide and the dipole as a mutual impedance.
Evaluation Of Microwave Reflection Properties Of Cyclically Soaked Mortar Based On A Semiempirical Electromagnetic Model, Shanup Peer, K. E. Kurtis, R. Zoughi
Evaluation Of Microwave Reflection Properties Of Cyclically Soaked Mortar Based On A Semiempirical Electromagnetic Model, Shanup Peer, K. E. Kurtis, R. Zoughi
Electrical and Computer Engineering Faculty Research & Creative Works
Detection of chloride ingress and evaluation of its distribution and temporal movement in reinforced concrete structures is an important practical issue. Steel reinforcing bars embedded in good quality concrete are normally protected from corrosion. However, the presence of a sufficient concentration of free chloride ions in the region of the reinforcing steel can initiate the process of corrosion. Therefore, it is important to be able to detect ingress of chloride ions and their distribution in cement-based materials. Moreover, it is important to obtain this information nondestructively. In recent years, near-field microwave nondestructive evaluation methods, using open-ended rectangular waveguide probes, have …
Microwave And Millimeter Wave Imaging Of The Space Shuttle External Fuel Tank Spray On Foam Insulation (Sofi) Using Synthetic Aperture Focusing Techniques (Saft), Joseph Toby Case, J. Robbins, Sergey Kharkovsky, Frank L. Hepburn, R. Zoughi
Microwave And Millimeter Wave Imaging Of The Space Shuttle External Fuel Tank Spray On Foam Insulation (Sofi) Using Synthetic Aperture Focusing Techniques (Saft), Joseph Toby Case, J. Robbins, Sergey Kharkovsky, Frank L. Hepburn, R. Zoughi
Electrical and Computer Engineering Faculty Research & Creative Works
The Space Shuttle Columbia's catastrophic failure is thought to have been caused by a dislodged piece of external tank spray on foam insulation (SOFI) striking the left wing of the orbiter causing significant damage to some of the reinforced carbon/carbon leading edge wing panels. Microwave and millimeter wave nondestructive evaluation methods have shown great potential for inspecting SOFI for the purpose of detecting anomalies such as small air voids that may cause separation of the SOFI from the external tank during a launch. These methods are capable of producing relatively high-resolution images of the interior of SOFI particularly when advanced …
Determination Of Microwave Dielectric Properties Of Materials Using A Unique Application Of Embedded Modulated Scatterer Technique, Gabriel S. Freiburger, R. Zoughi
Determination Of Microwave Dielectric Properties Of Materials Using A Unique Application Of Embedded Modulated Scatterer Technique, Gabriel S. Freiburger, R. Zoughi
Electrical and Computer Engineering Faculty Research & Creative Works
The embedded modulated scatterer technique has been investigated in the past as a means of determining the dielectric properties of a material of interest using an open-ended rectangular waveguide and an embedded PIN diode-loaded dipole probe. This technique has been further explored in a unique application utilizing the complex ratio of dynamic reflection coefficients for the two states of the modulated dipole probe. By utilizing this ratio, the calculation of dielectric properties becomes independent of measurement parameters such as distance, orientation, and location of the dipole probe relative to the waveguide radiator. This paper explores this unique application of the …
Microwave And Millimeter Wave Testing For The Inspection Of The Space Shuttle Spray On Foam Insulation (Sofi) And The Acreage Heat Tiles, R. Zoughi, Sergey Kharkovsky, Frank L. Hepburn
Microwave And Millimeter Wave Testing For The Inspection Of The Space Shuttle Spray On Foam Insulation (Sofi) And The Acreage Heat Tiles, R. Zoughi, Sergey Kharkovsky, Frank L. Hepburn
Electrical and Computer Engineering Faculty Research & Creative Works
The utility of microwave and millimeter wave nondestructive testing and evaluation (NDT&E) methods, for testing the Space Shuttle's external fuel tank spray on foam insulation (SOFI) and the acreage heat tiles has been investigated during the past two years. Millimeter wave NDE techniques are capable of producing internal images of SOFI. This paper presents the results of testing several diverse panels with embedded voids and debonds at millimeter wave frequencies. Additionally, the results of testing a set of heat tiles are also presented. Finally, the attributes of these methods as well as the advantageous features associated with these systems are …
Dielectric Material Characterization By Complex Ratio Of Embedded Modulated Scatterer Technique States, Gabriel S. Freiburger, R. Zoughi
Dielectric Material Characterization By Complex Ratio Of Embedded Modulated Scatterer Technique States, Gabriel S. Freiburger, R. Zoughi
Electrical and Computer Engineering Faculty Research & Creative Works
The embedded modulated scatterer technique (MST) is an innovative tool which can be used for microwave dielectric characterization of infrastructure and composite structures. By impinging a microwave signal on a loaded thin dipole antenna embedded in a material whose dielectric properties are sought, the resulting refelction data can be used to inversely solve for the dielectric properties of interest. Previous investigations utilized reflection information from a single loaded dipole and required known system parameters, such as radiator polarization vs. dipole alignment and relative distance between radiator and probe, to solve for the sought-for dielectric properties. This paper explores a unique …
High-Temperature Monitoring Of Refractory Wall Recession Using Frequency-Modulated Continuous-Wave (Fm-Cw) Radar Techniques, Bivin Varghese, C. Deconick, G. Cartee, M. Velez, Robert E. Moore, R. Zoughi
High-Temperature Monitoring Of Refractory Wall Recession Using Frequency-Modulated Continuous-Wave (Fm-Cw) Radar Techniques, Bivin Varghese, C. Deconick, G. Cartee, M. Velez, Robert E. Moore, R. Zoughi
Electrical and Computer Engineering Faculty Research & Creative Works
Furnaces are among the most crucial components in the glass and metallurgical industry. Nowadays, furnaces are being operated at higher temperatures and for longer periods of time thus increasing the rate of wear on the furnace refractory lining. Consequently, there is a great need for a nondestructive tool that can accurately measure refractory wall thickness at high temperatures. In this paper the utility of a frequency-modulated continuous-wave (FM-CW) radar is investigated for this purpose.
Millimeter Wave Detection Of Localized Anomalies In The Space Shuttle External Fuel Tank Insulating Foam And Acreage Heat Tiles, Sergey Kharkovsky, R. Zoughi, J. T. Case, F. L. Hepburn
Millimeter Wave Detection Of Localized Anomalies In The Space Shuttle External Fuel Tank Insulating Foam And Acreage Heat Tiles, Sergey Kharkovsky, R. Zoughi, J. T. Case, F. L. Hepburn
Electrical and Computer Engineering Faculty Research & Creative Works
Undesired manufactured or in-service produced anomalies in the form of voids in the SOFI and unbonds in the heat tiles can significantly reduce their designed effectiveness. Additionally, unbonds in the heat tiles may cause their complete separation from the fuselage exposing it to extreme heat. Millimeter wave NDT methods are viable candidate for life-cycle inspection of the SOFI and the acreage heat tiles of the Space Shuttle fleet. The results of these investigations described in this paper clearly showed the utility of these methods for detecting localized anomalies in thick SOFI and acreage heat tiles. These methods are fast and …
Size Evaluation Of Corrosion Precursor Pitting Using Near-Field Millimeter Wave Nondestructive Testing Methods, Mohammad Tayeb Ahmad Ghasr, Brian D. Carroll, Sergey Kharkovsky, R. Zoughi, R. Austin
Size Evaluation Of Corrosion Precursor Pitting Using Near-Field Millimeter Wave Nondestructive Testing Methods, Mohammad Tayeb Ahmad Ghasr, Brian D. Carroll, Sergey Kharkovsky, R. Zoughi, R. Austin
Electrical and Computer Engineering Faculty Research & Creative Works
Early detection of corrosion precursor pitting and estimation of its overall dimensions directly affects the required effort and cost associated with repair and maintenance of critical aircraft structural components. The magnitude and phase of a reflected signal from a pitting are directly related to its dimensions. This paper presents a millimeter wave probe and a sizing procedure used to detect and evaluate overall pitting dimensions.