Matlab 2010 A Crack In The Wall
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Abstract:The techniques of concrete crack detection, as well as assessments based on thermography coupled with ultrasound, have been presented in many works; however, they have generally needed an additional source of thermal infrared (TIR) radiance and have only been applied in laboratories. Considering the accessibility of thermal infrared cameras, a TIR camera (NEC F30W) was employed to detect cracking in the concrete wall of an historic house with a western architectural style in Kinmen, Taiwan, based on the TIR radiances of cracking. An operation procedure involving a series of image processing and statistical analysis processes was designed to evaluate the performance of the TIR camera in the assessment of the cracking width. This procedure using multiple measurements was implemented from March to August 2019, and the t-tests indicated that the temperature differences between the inside and outline of the concrete cracks remained insignificant as the temperature or relative humidity (RH) in the subtropical climate rose. The experimental results of the operation procedure indicated that the maximum focusing range, which is related to the size of the sensor array, and the minimum detectable crack width of a TIR camera should be 1.0 m and 6.0 mm, respectively, in order to derive a linear regression model with a determination coefficient R2 of 0.733 to estimate the cracking widths, based on the temperature gradients. The validation results showed that there was an approximate R2 value of 0.8 and a total root mean square error of 2.5 mm between the cracking width estimations and the observations.Keywords: thermal infrared radiances; width assessment of concrete crack; temperature gradients; image processing; statistical analysis
Numerous studies have applied optimization algorithms to minimize the final cost of CCR walls over the past few years. Optimization approaches simplify the design procedure by satisfying three primary criteria: geotechnical stability, structural strength, and economic efficiency. For example, Khajehzadeh et al. (2010) used particle swarm optimization, and then later employed a modified optimization method. Khajehzadeh and Eslami (2012) applied the gravitational search algorithm, Ceranic et al. (2001) utilized simulated annealing, Camp and Akin (2012) applied Big Bang Big Crunch, Aydogdu (2017) tried biogeography-based optimization algorithms, Gandomi et al. (2015c, 2017b, c) and Gandomi and Kashani (2018a, b) considered evolutionary and swarm optimization algorithms.
where Pf is the load at fracture, S is the span length, Ro and Ri are the mean outer and inner radii, Rm is the average of Ro and Ri, θC is the half-crack angle at fracture instability, and Fb is a geometry factor for a thick-walled pipe as defined by Takahashi (Takahashi, 2002).
The good correlation between the simulations and experiments also suggests that bubble collapse is a plausible reason for the cracking sound. This result is in agreement with the conclusions of Unsworth et al.2. The competing theory of tribonucleation-mediated bubble inception as the source of the sound stems from the observation that stable bubbles remain in the synovial fluid after an audible sound is heard4. Interestingly, our results show that a partial collapse of the cavitation bubble leads to physiologically consistent acoustics and leaves behind a stable micro-bubble, suggesting that the cavitation theory of knuckle cracking acoustics could indeed explain the experimental observation of stable micro-bubbles. The final micro-bubble in our simulations remains unchanged infinitely long as we assumed an impervious bubble wall. However, future numerical studies may model bubble inception and employ a more realistic bubble wall permeability to confirm and study the inception, terminal and long term dynamics of these bubbles. If the the role of bubble inception on acoustics is tested and the presence of these terminal micro-bubbles after a cavitation bubble collapse is confirmed, all the experimental observations in the literature can be reconciled and thus the disagreements surrounding the source of the sound can be resolved. 153554b96e
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