Structural Health Monitoring Using Smart Sensors - ideals ...

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1 Normalized accumulated stress 0.8 0.6 0.4 0.2 0 3 4 5 6 7 8 9 1011 7 8 9 10 111213 1415 1112 1314 151617 1819 Element ID Figure 8.8. Normalized accumulated stress in sensor community 1, 2, and 3 (the SDLV method). by the three cluster head nodes. Element 8 is detected as an element with the normalized accumulated stress smaller than the threshold value, 0.3. The intermediate and final results of the two DLV methods such as singular values, DLVs, and the normalized accumulated stress are also calculated on a PC based on the centrally collected acceleration time histories. The results calculated on the Imote2 are the same as those on the PC with the same precision of the data type. The damage detection capability of the proposed SHM framework implemented on a network of Imote2s has been demonstrated in this section. Further investigation of the capabilities of the approach will be pursued in section 8.8 by replacing other elements of the truss. 8.5 DCS logic Upon completing calculation of the normalized accumulated stresses, the three cluster heads exchange their damage detection results to perform the DCS logic given in Figure 7.22. The log of the associated session recorded on the base station is presented in Figures 8.9 and 8.10. These figures correspond to the damage detection results in Figures 8.7 and 8.8, respectively. Because no inconsistency is reported, retake flags are set to zero as indicated by lines2, 9, and 16 in Figures 8.9 and 8.10. When no inconsistency is found, the results are reported to the base station, and the Imote2s prepare to enter a sleep mode. Though element 18 is identified as a damaged element by the mass perturbation DLV method, this false-positive is likely to be avoided if sensor community 4 also monitors this element because of the redundancy. When inconsistency is detected, the DCS algorithm is repeatedly applied. Figure 8.11 shows the report to the base station when inconsistency is observed. Sensor communities 3, 4, and 5 monitor the truss to detect damage at element 21. Sensor communities 3 and 4 organized by cluster head nodes 73 and 135 find inconsistency. Sensor community 3 identifies element 16 as damaged, while sensor community 4 does not. After all three cluster heads finish reporting, only sensor communities 3 and 4 repeat acceleration measurement and data processing. The DCS 143
1 2 Node ID 67 RETAKE 0 3 4 ID 67 # of Damaged Element: 1 5 6 Damaged Element ID: 8 7 8 9 Node ID 81 RETAKE 0 10 11 ID 81 # of Damaged Element: 1 12 13 Damaged Element ID: 8 14 15 16 Node ID 73 RETAKE 0 17 18 ID 73 # of Damaged Element: 1 19 20 Damaged Element ID: 18 21 Figure 8.9. DCS logic log (the mass perturbation DLV method). 1 2 Node ID 67 RETAKE 0 3 4 ID 67 # of Damaged Element: 1 5 6 Damaged Element ID: 8 7 8 9 Node ID 81 RETAKE 0 10 11 ID 81 # of Damaged Element: 1 12 13 Damaged Element ID: 8 14 15 16 Node ID 73 RETAKE 0 17 18 ID 73 # of Damaged Element: 0 Figure 8.10. DCS logic log (the SDLV method). logic is applied again, and the results are reported to the base station as shown from lines 30 to 46 in Figure 8.11. No inconsistency is reported this time and all of the Imote2s are ready to enter the sleep mode. 144
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NSEL Report Series Report No. NSEL-
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The Newmark Structural Engineering
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Contents Page CHAPTER 1 INTRODUCTIO
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9.2.3 Power harvesting . . . . . .
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damage/deterioration is intrinsical
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scalability to a large number of sm
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logic circuit. However, FPGAs are m
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easons, smart sensors spatially dis
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Figure 2.1. EYES project sensor pro
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Table 2.1. Smart Sensor Specificati
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While a number of sensor boards for
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need to be within the coordinator's
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eing examined (Moore et al., 2001).
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structural damage, the analysis to
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that sensor installation cost inclu
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(2004) indicated that this accelero
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different type of sensors connected
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Chapter 3 SHM ARCHITECTURE This cha
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Modal operation Several modal opera
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its spatial gradient, which is clai
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Manager node Cluster head node Leaf
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commands; execution timing cannot b
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Table 3.2. Desirable Characteristic
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Table 3.2. Desirable Characteristic
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Figure 4.1. Foil strain gage. strai
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dB A s Figure 4.4. AA filter design
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8.32F 3V 3.45F 3V Input 1K 1K 1K 1K
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Strain ( ) 80 w/o Digital Filter 60
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performance was experimentally vali
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anges from 10 to 20. If 50 percent
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Node 1 x1 i =1,2,…,ns E x 1
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Correlation function estimate (m 2
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Figure 5.5. Effect of data loss and
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Frobenius norm. Because only a limi
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90 80 70 60 50 Node1 Node2 Node3 No
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On reception of a NACK, the sender
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Sender SendLData.send() Pack parame
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If there are missing packets, the r
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Sender SendLData.bcast() Pack param
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Sender Send a packet • Sender sen
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utilized in SHM applications follow
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where R xxref is a vector consistin
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Time (sec) 80 60 40 20 0 -20 -40 -6
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Difficulties encountered in realizi
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1.8715 x10 5 #ofdatablocks 1.871 me
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Before this decimation is applied,
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where xn is the original signal,
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Timer firing every T3 110 data poin
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locks before or after the current b
Page 99 and 100: Chapter 6 ALGORITHMS In this chapte
Page 101 and 102: The eigenproblem of the system matr
Page 103 and 104: where M 0 is the mass matrix of the
Page 105 and 106: same community, eliminating the nee
Page 107 and 108: measurement or mass perturbation ca
Page 109 and 110: these algorithms are implemented on
Page 111 and 112: 10 0 10 -2 10 -4 0 500 1000 1500 20
Page 113 and 114: Table 7.1. SVD Accuracy Check on Ma
Page 115 and 116: 7.1.4 Complex matrix inverse A comp
Page 117 and 118: Figure 7.9. Details of the joint (G
Page 119 and 120: Figure 7.13. Amplifier (Gao, 2005).
Page 121 and 122: 0.08 0.2 Acceleration (g) 0.04 0 -0
Page 123 and 124: 3 Imote2_2/Imote2_1 Imote2_1/Siglab
Page 125 and 126: 200 3 Phase of spectral densities (
Page 127 and 128: 1.5 x10-17 Time (sec) Difference in
Page 129 and 130: input forces applied at nodes in th
Page 131 and 132: CH1 CH2 CH3 …. CHn-1 CHn Initiali
Page 133 and 134: 1 2 Node ID 102 RETAKE 1 3 4 INCONS
Page 135 and 136: Initialization: within local sensor
Page 137 and 138: PC Base station Manager sensor Clus
Page 143 and 144: Table 7.7. Instructions in DCS Code
Page 145 and 146: EXPERIMENTAL VERIFICATION Chapter 8
Page 147 and 148: 8 x10-3 Time (sec) Correlation func
Page 149: Table 8.2. Mass Normalization Const
Page 153 and 154: for a SHM strategy does not necessa
Page 155 and 156: are saved. The 420 seconds listed a
Page 157 and 158: 1 1 Normalized accumulated stress m
Page 163 and 164: Table 8.5. Summary of False Damage
Page 165 and 166: Table 8.7. Summary of False Damage
Page 167 and 168: e scalability, autonomous distribut
Page 169 and 170: The lowest frequencies of interest
Page 171 and 172: structural vibration is considered
Page 173 and 174: REFERENCES Actis, R. L. & Dimarogon
Page 175 and 176: Casciati, F., Faravelli, L, Borghet
Page 177 and 178: Feldman, M. & Braun, S. (1995). “
Page 179 and 180: Kling, R. (2003). “Intel Mote: an
Page 181 and 182: Mufti, A. A. (2003). “Integration
Page 183 and 184: Sazonov, E., Janoyan, K., & Jha, R.
Page 185 and 186: Yi, J.-H. & Yun, C.-B. (2004). “C
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