Journal of AE, Volume 25, 2007 (ca. 26 MB) - AEWG

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4. Source Location Source location identifies the area of integrity loss. At present, most AE equipment incorporates the software for source location and clustering scheme and displays results in various user interfaces. High AE activity at a given area of a structure, or a cluster, implies the possible presence of flaw. The criteria of “high” activity always need careful attention; AE hit counts and rates, amplitude, and energy have initially formed the basis for the grading of clusters. An example of 2D-source location on a cyclically loaded wind-turbine blade is shown in Fig. 9, along with the photograph of damage location with sensors (Beattie [45]). Each AE event source was located in different triangles formed by the three nearest sensors. Damage development is clearly displayed on the source-location map of the fatigue-tested blade after 3.7+ million cycles. An excellent correspondence is displayed between observed damage and source locations. Source location in AE evolved from the procedures used in seismology. The original electromechanical system at Aerojet [1] developed into current PC-based systems. Recently, Ge [46] reviewed available source location algorithms thoroughly with theoretical background. These are applicable to both 2D-source location and 3D-source location. A simpler Zone-location scheme has been used in structures with high attenuation materials. This method works when the attenuation of AE signals is high and triangulation techniques require too many sensors (and attendant electronics). AE activities at the first-arriving sensor are associated with this sensor location and the “zone” surrounding it. While not as accurate, it identifies the regions of high AE activity. Figure 7b shown earlier is an example of zone location. Fig. 10 The AE locations of a 2-m thick depth interval between the floor of the intermediate level and the roof of the lower level (data of one year, 72,902 events). Spies and Eisenblätter [48]. 10
In geotechnical applications, the prediction of rock burst, and coal and gas outburst was historically important from the safety consideration [29, 47]. Increasing AE rates and spatial focusing were carefully evaluated to anticipate impending bursts. The stability of highway and railway slopes has also been much worked AE applications. The stability of excavation of underground cavities and openings is more recently examined, especially in connection with nuclear waste disposal. Microcracking changes the microstructure of the rock so that permeability might increase. Macrofracturing can lead to stability problems. Detected locations of microcracks in a radioactive waste disposal facility are shown in a plan view in Fig. 10 [48]. Geothermal energy extraction is another area AE is actively used for studying and monitoring the distribution of reservoirs, hydraulic fracturing, reservoir volume and hydro-circulation. Similar methods are now being applied to gas and oil production. In examining the evolution and distribution of AE sources in a cluster, fractal analysis has been used. A fractal dimension of three represents random events occurring in a volume and a fractal dimension of two signifies that the events have localized on a failure plane [49, 50]. An example of decreasing fractal dimension with the progress of fracturing in a rock sample is given in Fig. 11 [50]. Introducing fractal modeling processes, crack distribution is constructed for a real coalmine starting from AE data set and laboratory tests [51]. 400 3.5 350 3 Load (kN) 300 250 200 150 100 2.5 2 1.5 1 Fractal Dimension 50 0 0.00 0.02 0.04 0.06 0.08 0.10 0.12 Displacement (mm) Load Fractal Dimension Fig. 11 Load history and fractal dimension for the biaxial test of a rock. Iverson et al. [50]. Source location in an anisotropic or a dispersive propagation medium requires special consideration. Applications of wavelet transform and affine transformation are examples of such effort [52, 53]. The use of wavelet transform defines the arrival times at a given frequency with precision. See Fig. 12 for arrival time determination of L-mode and F-mode cylindrical waves at 190 kHz. The propagation of waves in a large pipeline has been of practical importance for many years, but it should be noted that different wave modes have different attenuation characteristics, as shown in Fig. 13 [54]. Note that fastest moving wave (presumably L(0,1)-mode cylindrical waves) and the second fastest attenuated more than slower moving waves of likely flexural modes. The affine transformation speeds up the source location algorithm in orthotropic plates 0.5 0 11
Page 3 and 4: JOURNAL OF ACOUSTIC EMISSION VOLUME
Page 5 and 6: 25-194 ACOUSTIC EMISSION SOURCE LOC
Page 7 and 8: Volume 25 (2007) AUTHORS INDEX DIMI
Page 9 and 10: YUICHI TOMODA, 25-021 T. TOUTOUNTZA
Page 11 and 12: Notes for Contributors 1. General T
Page 13 and 14: In Memoriam H. Reginald Hardy, Jr.
Page 15 and 16: STRUCTURAL INTEGRITY EVALUATION USI
Page 17 and 18: The power-law AE behavior was recen
Page 19 and 20: sorting out the original signals, e
Page 21 and 22: Wood [36] in Australia has been usi
Page 23: One needs to appreciate the difficu
Page 27 and 28: methods include the use of combined
Page 29 and 30: should take. Past attempts for stru
Page 31 and 32: 11. Suzuki, T., Ohtsu, M., Aoki, M.
Page 33 and 34: 40. http://en.wikipedia.org/wiki/Ma
Page 35 and 36: Abstract ACOUSTIC EMISSION TECHNIQU
Page 37 and 38: Fig. 1 Damage qualification by the
Page 39 and 40: After adding the data of a tested s
Page 41 and 42: Fig. 8 Sketch of a reinforced concr
Page 43 and 44: (3) Corrosion Process of Reinforced
Page 45 and 46: analysis. Corrosion cracking was si
Page 47 and 48: ACOUSTIC EMISSION MONITORING OF REI
Page 49 and 50: which - contrary to current beliefs
Page 51 and 52: Fig. 4. Applied load (actuator 1) a
Page 53 and 54: concrete and the jacket. Visual ins
Page 55 and 56: Based on conventional analysis, AE
Page 57 and 58: 2. Experimental The model pipe syst
Page 59 and 60: pressure, respectively. This is ana
Page 61 and 62: Fig. 6: Power spectra from fast Fou
Page 63 and 64: small leaks (below 0.1 mm diameter)
Page 65 and 66: ACOUSTIC EMISSION TECHNIQUE APPLIED
Page 67 and 68: parameters in time domain and (c) m
Page 69 and 70: above the threshold level of 40 dB
Page 71 and 72: energy, i.e., high amplitude and lo
Page 73 and 74: An optical microscopy observation o
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Continuous WT (CWT) is defined as a
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Fig. 8. Typical AE waveforms, their
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followed by abrupt jumps in the det
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E. Landis (1999), “Micro-macro fr
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EVALUATION OF REPAIR EFFECT FOR DET
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Fig. 2 Sensor array for tomography
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2 [ ] 2 k 3 9 2 2 1 f () 0 f ()
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At these depths, a complicated and
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The number of AE hits after repair
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damage indices of Calm and Load rat
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PVDF is a semicrystalline polymer,
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After these preliminary tests, the
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of PVDF sensors does not seem to ha
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Fig. 10. Evolution of a typical PAD
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Fig. 17. Evolution of a typical dur
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I-G. Kim, H-Y. Lee and J-W. Kim (20
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Pencil-lead breaks are monopoles an
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Fig. 1 Displacement vs. time, sourc
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Fig. 5 Displacement vs. time, sourc
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Fig. 8 Displacement versus time for
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Fig. 10 Displacement vs. time. Sour
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Fig. 14 Signal amplitude versus tim
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To better relate these PLB and FEM
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HIGH-TEMPERATURE ACOUSTIC EMISSION
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thickness of 9 μm. The AlN element
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Fig. 5 Experimental setup for AE mo
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scales (and possibly salt cracks at
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DAMPING, NOISE, AND IN-PLANE RESPON
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The sharper resonance in Fig. 1c is
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i 2 RMS VDCC0 k BT = , g m 2 i
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ecause in-plane motion mostly produ
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4. B. Bahreyni, C. Shafai, Fabricat
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We first introduce our new quadridi
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Fig. 4 Amplitude profile as a funct
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Fig. 6 Change of room temperature (
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3) There are slight time lags in th
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Function Generator (FG) The functio
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Table 1 Results for continuous sens
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Fig. 7 pulse response XXX, filter :
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Fig. 11: Noise spectrum VS30-SIC-46
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waves propagate in a plate like str
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0.15 0 100kHz Driving pulse 10 100k
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0.45 0 100kHz Driving pulse 30 100k
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the sensor response to different fr
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CHARACTERISTICS OFACOUSTIC EMISSION
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Results and Discussion Shrinkage pr
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sapwood. Norway spruce wood consist
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most of the cells reached the fiber
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CHARACTERIZATION OF TITANIUM HYDRID
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Growth behavior of hydrides We stud
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were determined by the tensile test
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Figure 9 shows the Mode-I cracks in
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Results obtained are summarized as
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process of hydrogen destruction of
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Amplitude [dB] 60 55 50 45 40 35 30
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(Fig. 7) relative to the material a
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is shown in Table 1. Test specimens
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Fig. 4 Two types of AE signals dete
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the charging solution at 25 o C, by
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ANALYSIS OF ACOUSTIC EMISSION FROM
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nearly same waveforms for the first
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values). Most (11 of 14) of the rec
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Type-D (at 3.45 ms). In this sample
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NEURAL NETWORK BURST PRESSURE PREDI
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temperature, while the remaining se
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not properly set). This results in
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Conclusions Table 3 Summary of trai
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accurate source locations could be
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Fig. 1 Group velocities versus freq
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plane source orientation. But the l
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Fig. 9 Out-of-plane displacement vs
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Fig. 11 WTs of Fig. 8 with superimp
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Fig. 13 WTs of Fig. 10 with superim
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Table 3 At 102 kHz, WT peak arrival
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Fig. 17 Frequency of maximum WT int
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Fig. 18 Arrangement of sensors (#1,
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location calculation result that yi
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NOVEL ACOUSTIC EMISSION SOURCE LOCA
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tion resolution. It should be noted
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The specimen with numerous holes wa
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Fig. 5. Comparison of location meth
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Conclusions Delta-T source location
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Our approach This conceptual view c
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Voronoi Construction: Taking a case
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Fig. 6: Source location on a clamp
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PROBABILITY OF DETECTION FOR ACOUST
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POD is determined at the convergenc
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Fig. 2: Setup for illustrative runs
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Fig. 7: Probability of location (PO
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AE signals were filtered by high-pa
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Fig. 3 Accuracy and variations of a
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Fig. 7 Accuracy and variations of a
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eference data. The absolute values
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REAL-TIME DENOISING OF AE SIGNALS B
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600 500 400 300 200 kHz700 Frequenc
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the STFT result (Fig. 4(b)). Theref
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MONITORING THE EVOLUTION OF INDIVID
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the type of filtering, number of su
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was observed for either actuator. F
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Conclusions An experimental methodo
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the onset of pulses, consequently,
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zeros. The locations where a patter
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The reliability of the additional p
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AE MONITORING OF SOIL CORROSION OF
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Fig. 2 Cumulative AE counts with ap
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cumulative event counts and amplitu
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AE was monitored using three types
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Our conclusion from these tests is
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measurements with an Exxon Nuclear
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equipment manufacturer), CISE (AE t
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Automatic testing of receptacles du
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The finalized standards are: • EN
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14. Tscheliesnig P., Lackner G., He
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Fig. 1. Typical high-temperature cr
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• Emission rates are much higher
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Fig. 4. Results of AE monitoring of
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examination at 2000-5000X was able
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samples extracted from the beam aft
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The relative comparison of the size
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Fig. 3. Schema of VB Application fo
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Fig. 5. Microstructural observation
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Fig. 7 AE source locations for diff
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Fig. 9 CT images and corresponding
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A.M. Brandt, G. Prokopski, J. Mater
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conducted with AE technique. The AE
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After location of the events, inter
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The transit times of the individual
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6) B. Schechinger, T. Vogel, Acoust
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greater than the available anchorag
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location uncertainty and is the roo
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Figures 4 and 5 illustrate all loca
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ig cracks form, localization of AE
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ased on magnetic induction, while i
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Fig. 3. AE sensors positioning on b
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As a further evaluation of the degr
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EARLY FAULT DETECTION AT GEAR UNITS
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Acoustic Emission Analysis at Rotat
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The fixed bearing at the beginning
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The time-frequency components of a
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Additionally, the gear test bench h
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APPLICATION OF ACOUSTIC EMISSION IN
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Measurements of the acoustic backgr
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Fig. 6. RMS for different ranges of
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which indicate the transition from
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surface condition. It has already b
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( 2 1) 2) ! kx1 ! k c ! x + c ! k (
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Fig. 6: Signal above normal and def
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DAMAGE ASSESSMENT OF GEARBOX OPERAT
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The waveform streaming can be trigg
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Extracting features using different
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The classifier was used to identify
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ASL spectral energy is further calc
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2 #_ of _ Sensors 2 2 2 ( x ) (
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Simulated Failure Plane One hundred
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It has been documented that the ini
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(a) (b) (c) (d) 95% _ 98% 98% _ 100
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IMPACT IMAGING METHOD TO MAP DAMAGE
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e) Step d) was repeated until the a
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Panel A Panel B Panel C Panel D Fig
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Journal of AE, Volume 25, 2007 (ca. 26 MB) - AEWG

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