Browsing by Author "Ho, YT"

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Development of a fibre Bragg grating sensored ground movement monitoring system
(2006-07-01)
Ho, YT
;
Huang, AB
;
Lee, JT
;
土木工程學系
;
Department of Civil Engineering
Monitoring ground movement manually by lowering an inclinometer probe (IP) in a grouted-in-place casing has been in practice for decades. It is possible to install multiple IP units at various depths in an inclinometer casing to allow automated data logging. The high cost and other problems associated with transmitting signals electrically make an automated IP rather impractical for long term and/or massive deployment. In addition to its small size, available technologies allow optical signals to be transmitted over many kilometres and not be affected by electromagnetic interference. The optical fibre Bragg grating (FBG) is one of the many available fibre optic sensor technologies. The authors used FBG as a sensing medium and developed a ground movement monitoring device referred to as the FBG segmented deflectometer (FBG-SD). The FBG-SD, designed to be inserted into the conventional inclinometer casing, measures the relative deflection between the segments. The amount of lateral movement is computed on the basis of the distribution of the segmented deflections. To verify the effectiveness of the new system, the authors performed indoor as well as field experiments where results from FBG-SDs were compared with conventional IP readings. This paper introduces the design principles of the FBG-SD and describes the performance of the system in their indoor and field applications.
Ground movement monitoring using an optic Fiber Bragg Grating sensored system
(2004)
Huang, AB
;
Ma, JM
;
Zhang, BS
;
Wen, XG
;
Cao, JG
The authors have developed a fiber optic ground movement monitoring system using the optic Fiber Bragg Grating (FBG). A series of FBG's are glued to the outside of flexible plastic elements. These flexible elements are connected together to form a single probe. When the flexible element is bent, the FBG would sense the flexural strain as a result of the bending. Twice integration of the strains along the longitudinal axis of the probe yields the distribution of the displacement of the monitoring probe associated with the bending. The FBG sensored monitoring probe can be inserted in an inclinometer casing or directly grouted in a borehole to monitor ground movement. The sensitivity and range of allowable bending of the monitoring probe can be adjusted according to the need in the field. The new system can be used to monitor stability of natural slopes, man-made retaining structures (including darns or dikes), braced cuts, and tunnel excavations, etc. The FBG based monitoring system has been experimented to monitor the displacement distribution of a laterally loaded pile in Yuin-Lin, Taiwan and stability of a Yellow River dike in Honan, China. This paper describes the principles of the FBG sensored monitoring probe system and presents field applications of the new sensor systems.
Ground movement monitoring using an optic Fiber Bragg Grating sensored system
(2005)
Ho, YT
;
Huang, AB
;
Ma, JM
;
Zhang, BS
;
Cao, JG
The authors have developed a fiber optic ground movement monitoring system using the optic Fiber Bragg Grating (FBG). A series of FBG's are glued to the outside of flexible plastic elements. These flexible elements are connected together to form a single probe. When the flexible element is bent, the FBG's sense the flexural strain as a result of the bending. Twice integration of the strains along the longitudinal axis of the probe yields the distribution of the displacement of the monitoring probe associated with the bending. The sensitivity and range of allowable bending of the monitoring probe can be adjusted according to the need in the field. The FBG based monitoring system has been experimented to measure the displacement distribution of a laterally loaded pile in Yuin-Lin, Taiwan. This paper describes the principles of the FBG sensor monitoring probe system and presents a case of field application of the sensor system.
Measurement of inorganic acidic gases and particles from the stack of semiconductor and optoelectronic industries
(2004-06-01)
Huang, CH
;
Ho, YT
;
Tsai, CJ
;
環境工程研究所
;
Institute of Environmental Engineering
A method for sampling inorganic acids in the exhaust gas of semiconductor and optoelectronic industries was developed by using a porous metal denuder and an ion chromatograph analysis. The sampler consists of a Teflon filter to collect inorganic acidic aerosols followed by two coated porous metal discs for sampling inorganic acidic gases. The second disc was used to check if the gas broke through the first disc. The method detection limit of the sampler is appropriate for sampling the exhausted gas at semiconductor or photoelectric industries. Test results indicated that the calibration curves had good coefficients of correlation, and the concentrations of the laboratory and field blanks were found to be lower than the method detection limit. For the semiconductor and optoelectronic industries, the total concentration of acidic gases and particles for hydrofluoric acid, hydrochloric acid, nitric acid, phosphoric acid, and sulfuric acid was found to be 85-999, 40-820, 21-223, ND (not detectable) -404, and 49-535 mug/Nm(3) (at 0degreesC, 1 atm), respectively, by using the new method. The porous metal denuder is compact in size, sensitive in detection, and suitable for sampling several inorganic acids simultaneously in the exhausted gas for the semiconductor or photoelectric industries.