Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 20 for “"air-coupled"”.
-
Air-coupled ultrasonic tomographic imaging of concrete elements
… internal velocity variations can be constructed. Air-coupled UPV can allow for more automated and rapid collection of data for tomography of concrete. This research aims to integrate recent developments in air-coupled ultrasonic measurements with advanced tomography technology and apply them to …
-
Advancements in evaluation of air-coupled impact-echo test method
… work to investigate a recently-developed air-coupled impact-echo (IE) nondestructive testing (NDT) method, in which microphones replace the traditional physically-coupled IE sensors. To develop an optimum testing system and verify the new method, two concrete plates were tested in the …
-
Non-Contact NDT of Concrete Structures Using Air -Coupled Sensors
The second application is air-coupled impact-echo. Two reinforced concrete slabs containing different types of defects were inspected using an air-coupled impact test testing scheme. 2-D scanning impact-echo tests were conducted over the slab containing voids and delaminations. The 2-D scanning …
-
An air-coupled ultrasonic array scanning system for rapid through transmission NDT
… now being used frequently in the manufacture of aircraft. The complexity of the material manufacture necessitates that evaluation is required prior to final production and it is the development of a novel approach to this testing that constitutes the focus for the work of this Thesis. Existing …
-
Air-coupled non-destructive evaluation technology for condition assessment of railroad ties
This study describes the development of fully air-coupled non-destructive evaluation (NDE) technology for condition assessment of railroad ties. Ultrasonic surface waves are generated in railroad ties using an air-coupled ultrasonic sender. Surface waves are sensed at the receiving end using an …
-
Correlation-Based Detection and Classification of Rail Wheel Defects using Air-coupled Ultrasonic Acoustic Emissions
Defected wheel are one the major reasons endangered state of railroad vehicles safety statue, due to vehicle derailment and worsen the quality of freight and passenger transportation. Therefore, timely defect detection for monitoring and detecting the state of defects is highly critical. This …
-
Optimality of human acoustic perception of natural sounds, and violin acoustics elucidated with a non-corporeal musical instrument made by fully air-coupled finite-element-modeling of the Titian Stradivarius
… and build a non-corporeal instrument: a fully air-coupled finite-element-modeled Titian Stradivarius violin employing CT-scan reconstruction. The non-corporeal instrument is trained to play the first two measures of the Sonata No. 1 in G-minor, BWV 1001: II. Fuga. Allegro by Bach, using a …
-
Defect characterization in concrete elements using vibration analysis and imaging
… labor-intensive and time-consuming; contactless, air-coupled IE tests offer a solution to this limitation. In this study, effective implementation of air-coupled IE to characterize delamination defects in concrete structures is sought. Progress in this effort is reported here. First, the …
-
Fluidic ultrasound generation for nondestructive testing
… properties in numerous technical domains. Air-coupled ultrasound offers advantages in terms of measurement flexibility and reduced measurement time, but also presents challenges due to limitations in transmitted sound pressure amplitude and sensor positioning. Due to the high impedance …
-
Enhancing signal to noise ratio for electrostatic transducers
… Amplified Ultrasonic Transducer (FLAUT) for an air-coupled application. The transducer utilises a pipe as an amplification mechanism to increase the output pressure; and as a dissipation mechanism to reduce inherent noise within the transducer. The new transducer design introduces the concept of …
-
Development of Ground Penetrating Radar Signal Modeling and Implementation for Transportation Infrastructure
… GPR frequency range; to synthesize the reflected air-coupled radar signals and compare them with measured waveforms; to model and study the effects of simulated defects in concrete on the reflected air-coupled and ground-coupled radar signals; and to validate the research results in the field by …
-
Damage assessment in reinforced concrete using contactless ultrasound
… labor- and time-intensive. Contactless, or air-coupled, UT systems offer a solution to this limitation. In this thesis, high-performance contactless UT systems are studied, developed, implemented and verified in order to characterize several different type of damage (delamination, …
-
Acoustoelastic effects of surface waves in concrete subjected to compressive and bending stresses
… consist of R-waves generated using a partially air-coupled configuration. Several wave arrival detection methods are studied and results are compared to signals simulated using a finite element model. An optimal R-wave detection method is defined for the investigation's experimental work. …
-
INTELLIGENT NON-DESTRUCTIVE EVALUATION EXPERT SYSTEM FOR CARBON-CARBON COMPOSITES USING THERMOGRAPHY, ULTRASONICS, AND COMPUTED TOMOGRAPHY
… which include 2-D pitched based commercial aircraft disc brakes and asmolds, 3-D PAN based C/C composites, and carbon fiber reinforced plastic (CFRP) panels, were tested. Based on the performance testing results of thermography, air-coupled ultrasonic, and x-ray computed tomography, the …
-
Low noise techniques applied to a piezoceramic receiver for gas coupled ultrasonic flaw detection
… the viability of a robust and truly practical air-coupled Lamb wave scanner suitable for detecting defects in thin plates which can be made from almost any type of material. The complete system has sufficient sensitivity to allow rapid scanning without the requirement for transducer matching …
-
Fibrous tectonics
… field of architecture. Efficiency and durability coupled with a load bearing capacity make a strong case for the use of composites as a primary building material. We now possess the computational and digital manufacturing tools that make the development of a composite building viable.On a holistic …
-
Interaction of acoustic beam with elastic structures
… the interaction of acoustic beams in water and air with planar and cylindrical elastic structures. Ultrasonic reflection measurements have been used to elucidate the phenomena of guided wave generation and reradiation by selecting beam incidence at, or near, phase-matching conditions. Under …
-
Prediction of in-situ asphalt mixture density using ground penetrating radar: theoretical development and field verification
… common mid-point (XCMP) method using two air-coupled antenna systems was developed, and its implementation feasibility was explored. The XCMP method was found to provide better performance than the traditional surface-reflection method for thick pavement structures with multi-lifts. …
-
Prediction of asphalt concrete pavement density from processing ground-penetrating radar compaction data
… change during AC pavement compaction using air-coupled antennas. However, issues, including surface moisture effect due to water spray during compaction, vibration effect during continuous GPR survey, and signal processing complexity, may hinder AC density prediction accuracy. This study …
-
Application of Diagnostic Methods to Assess Ageing Processes in Polymers
… distinctive relationships using the current air-coupled design. The carried work contributes to the understanding of ageing of semi-crystalline polymers and provides significant contributions towards their deployment in high pressure applications. It also presents a novel outlook on the …