C. S. Kao
ExxonMobil
Digital image correlationGeologyBrittlenessArtificial intelligenceComposite materialTime of arrivalFree surfaceAcoustic emissionPattern recognitionGeotechnical engineeringMaterials scienceInstabilityNoise (signal processing)Surface (mathematics)Structural health monitoringDisplacement (orthopedic surgery)Computer scienceFracture (geology)Displacement (vector)MechanicsFracture mechanicsSpallStructural engineeringCluster analysisSignal-to-noise ratioStress (mechanics)Hierarchical clusteringShear (geology)
14Publications
6H-index
101Citations
Publications 14
Newest
Mar 25, 2016 in CPM (Combinatorial Pattern Matching)
#1Ali Tarokh (UMN: University of Minnesota)H-Index: 8
#2C. S. Kao (ExxonMobil)H-Index: 6
Last. Joseph F. Labuz (UMN: University of Minnesota)H-Index: 32
view all 4 authors...
Surface spalling is a complex failure phenomenon that features crack propagation and detachment of thin pieces of rock near free surfaces, particularly in brittle rock around underground excavations when large in situ stresses are involved. A surface instability apparatus was used to study failure of rock close to a free surface, and damage evolution was monitored by digital image correlation (DIC). Lateral displacement at the free face was used as the feedback signal to control the post-peak re...
5 CitationsSource
#1C. S. Kao (ExxonMobil)H-Index: 6
#2Ali Tarokh (UMN: University of Minnesota)H-Index: 8
Last. Joseph F. Labuz (UMN: University of Minnesota)H-Index: 32
view all 4 authors...
Spalling near a free surface in laboratory experiments on two sandstones was characterized using acoustic emission and digital image correlation. A surface instability apparatus was used to reproduce a state of plane strain near a free surface in a modeled semi-infinite medium subjected to far-field compressive stress. Comparison between AE locations and crack trajectory mapped after the test showed good consistency. Digital image correlation was used to find the displacements in directions para...
6 CitationsSource
#1Ali Tarokh (UMN: University of Minnesota)H-Index: 8
#2C. S. Kao (ExxonMobil)H-Index: 6
Last. Joseph F. LabuzH-Index: 32
view all 4 authors...
Failure of rock close to a free surface is reproduced in laboratory tests on two types of sandstone. Digital image correlation is used to study the in-plane displacement fields prior to and during the successive formation of surface-parallel fractures. The axial and lateral displacements suggest that the displacement gradient is uniform in both directions at early loading stages; as the axial load increases, the free-face effect starts to influence the displacement contours, especially the later...
6 CitationsSource
#1Ali Tarokh (UMN: University of Minnesota)H-Index: 8
#2Joseph F. LabuzH-Index: 32
Last. A. Fakhimi (TMU: Tarbiat Modares University)H-Index: 1
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1 Citations
#1C. S. KaoH-Index: 6
University of Minnesota Ph.D. dissertation. December 2011. Major: Civil engineering. Advisor: Joseph F. Labuz. 1 computer file (PDF); v, 150, appendices A.
4 Citations
#1C. S. Kao (UMN: University of Minnesota)H-Index: 6
#2Fernanda C.S. Carvalho (UMN: University of Minnesota)H-Index: 5
Last. Joseph F. Labuz (UMN: University of Minnesota)H-Index: 32
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Abstract Acoustic emission (AE) events were located and characterized from a mode I fracture test on Charcoal granite. An AE source was modeled as a displacement discontinuity, a microcrack, with a displacement vector b , normal n , and area Δ A . For convenience, the source parameters were recovered through a moment tensor representation, the components of which were estimated by minimizing the error between theoretical and measured displacements at sensor positions, with an appropriate constra...
40 CitationsSource
#1C. S. Kao (UMN: University of Minnesota)H-Index: 6
#2Joseph F. Labuz (UMN: University of Minnesota)H-Index: 32
Last. Luigi Biolzi (Polytechnic University of Milan)H-Index: 26
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1 Citations
#1Nuri F. Ince (UMN: University of Minnesota)H-Index: 18
#2C. S. Kao (UMN: University of Minnesota)H-Index: 6
Last. Joseph F. Labuz (UMN: University of Minnesota)H-Index: 32
view all 5 authors...
This paper reports on the feasibility of locating microcracks using multiple-sensor measurements of the acoustic emissions (AEs) generated by crack inception and propagation. Microcrack localization has obvious application in non-destructive structural health monitoring. Experimental data was obtained by inducing the cracks in rock specimens during a surface instability test, which simulates failure near a free surface such as a tunnel wall. Results are presented on the pair-wise event correlati...
20 CitationsSource
Apr 19, 2009 in ICASSP (International Conference on Acoustics, Speech, and Signal Processing)
#1Nuri F. Ince (UMN: University of Minnesota)H-Index: 18
#2C. S. Kao (UMN: University of Minnesota)H-Index: 6
Last. Joseph F. Labuz (UMN: University of Minnesota)H-Index: 32
view all 5 authors...
Localizing micro cracks in critical components is crucial in the field of continuous structural health monitoring. In this paper, we utilize several signal processing and machine learning techniques such as hierarchical clustering and support vector machines (SVM) to process multisensor acoustic emission (AE) data generated by the inception and propagation of cracks. We present preliminary laboratory results that explore the pairwise event correlation of AE waveforms generated in the process of ...
10 CitationsSource
#1Nuri F. InceH-Index: 18
#2C. S. KaoH-Index: 6
Last. Joseph F. LabuzH-Index: 32
view all 5 authors...
This paper presents a sequence of signal processing and hierarchical clustering techniques utilized to process signals with low signal-to-noise ratio (SNR) measured by multiple AE sensors. Noise and other extraneous events present major challenges for the detection and monitoring of AE signals generated by the inception of microcracks and their growth. Characteristics of AE waveforms released during controlled mode-I fracture are explored, and these characteristics are used for clustering AE and...
2 Citations