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Health monitoring of time-varying stochastic structures by latent components and fuzzy expert system
In this paper, a novel parametric model-based decomposition method is proposed for structural health monitoring of time-varying structures. For this purpose, the advanced Functional-Series Time-dependent Auto Regressive Moving Average （FS-TARMA） technique is used to estimate the parameters and innovation variance used in the parametric signal decomposition scheme. Additionally, a unique feature extraction and reduction method based on the decomposed signals, known as Latent Components （LCs）, is proposed. To evaluate the efficiency of the proposed method, numerical simulation and an experimental study in the laboratory were conducted on a time-varying structure, where various types of damage were introduced. The Fuzzy Expert System （FES） was used as a classification toot to demonstrate that the proposed method successfully identifies different structural conditions when compared with other methods based on non-reduced and ordinary feature extraction. 相似文献
93.
Y. Jafarian A. Sadeghi Abdollahi R. Vakili M.H. Baziar 《Soil Dynamics and Earthquake Engineering》2010
Cyclic triaxial tests on reconstituted sand samples are broadly employed in practice while they ignore the inherent characteristics of soil in field condition such as aging, fabric, and prior strain history. Relative state parameter index, ξR, is utilized in a probabilistic framework to adjust the cyclic triaxial resistance ratio of sands at 15 uniform cycles (CRRtx,15) to field condition. A wide-ranging database containing the results of cyclic triaxial tests conducted on reconstituted samples has been compiled to derive a correlation between relative state parameter index (ξR) and triaxial cyclic resistance ratio. The adjustment coefficients proposed by researchers are employed to correct CRRtx,15−ξR relationship for actual field condition. The adjusted CRRtx,15−ξR relationships are applied to a database of field liquefaction case histories composed of both SPT and CPT based data and their performances in field condition are evaluated. It is demonstrated that constant triaxial-to-field adjusting coefficients cannot ever predict conservative results. Logistic regression method is employed to derive a field probabilistic criterion that obtains the likelihood of liquefaction initiation in terms of ξR. The ξR-based boundary curve standing for 20% likelihood of liquefaction initiation is found to be the most conservative limit state boundary to be used in field conditions. Finally, the triaxial and field CRR−ξR relationships are composed and a probabilistic triaxial-to-field adjustment coefficient is proposed in terms of ξR and a given liquefaction probability. It is anticipated that the proposed relationship could reasonably correct the results of cyclic triaxial testing on freshly reconstituted sand samples. 相似文献
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Taravatrooy Narges Nikoo Mohammad Reza Sadegh Mojtaba Parvinnia Mohammad 《Natural Hazards》2018,93(2):905-920
In many parts of Canada, limited data are available for hydrodynamic model inputs, and the ability to generate quality flood grids through 1D, 2D or 3D methods is nonviable. In this paper, the capability of simplified flood models, which rely solely on digital terrain models (DTMs), was explored to assess the quality and speed of their results. Results were validated against historic floods in two locations. Three non-physics-based simplified conceptual flood models were tested: (1) planar method, (2) inclined plane and (3) height above nearest drainage network (HAND) model. The accuracy and performance were evaluated using three criteria: inundation extent, water depth and computation time. Findings show that the HAND model is the best predictor of inundation extent, with Probability of Detection and Critical Success Index being higher than 0.90 in both study areas. Though the preprocessing time for the HAND model is lengthy, once completed, the time to simulate flooding at a variety of water levels is rapid, making this model the most suitable choice for web-based, on-demand flood inundation mapping. Knowledge of the fit of these flood models and associated uncertainty can be helpful to emergency managers such that they can better understand exposure and vulnerability while preparing flood response plans. 相似文献
95.
AbstractThe sediment yield model of the MUSLE (modified universal soil loss equation) is applied extensively throughout the world, but different performances have been reported of its success relative to measured data. A review of all the available literature is presented to assess the application of the model under different conditions and, ultimately, make a comprehensive judgement on the different aspects to allow readers to adjust their further research. A review of 49 papers showed the variable accuracy of the model, which depends on the manner of calculation and determination of the input and output, and the study time and space scales. There were differences in land use, in correspondence of the physiographic characteristics with those of the original conditions of model development, and even in the experience of researchers in applying the model. The results also show the need to consider the original application of the model, as proposed by its developers, to achieve comparable results.Editor Z.W. KundzewiczCitation Sadeghi, S.H.R., et al., 2014. A review of the application of the MUSLE model worldwide. Hydrological Sciences Journal, 59 (2), 365–375. 相似文献
96.
A Bonded Particle Model Simulation of Shear Strength and Asperity Degradation for Rough Rock Fractures 总被引：3，自引：3，他引：0
Mohammad Sadegh Asadi Vamegh Rasouli Giovanni Barla 《Rock Mechanics and Rock Engineering》2012,45(5):649-675
Different failure modes during fracture shearing have been introduced including normal dilation or sliding, asperity cut-off and degradation. Attempts have been made to study these mechanisms using analytical, experimental and numerical methods. However, the majority of the existing models simplify the problem, which leads to unrealistic results. With this in mind, the aim of this paper is to simulate the mechanical behaviour of synthetic and rock fracture profiles during direct shear tests by using the two-dimensional particle flow computer code PFC2D. Correlations between the simulated peak shear strength and the fracture roughness parameter D R1 recently proposed by Rasouli and Harrison (2010) are developed. Shear test simulations are carried out with PFC2D and the effects of the geometrical features as well as the model micro-properties on the fracture shear behaviour are studied. The shear strength and asperity degradation processes of synthetic profiles including triangular, sinusoidal and randomly generated profiles are analysed. Different failure modes including asperity sliding, cut-off, and asperity degradation are explicitly observed and compared with the available models. The D R1 parameter is applied to the analysis of synthetic and rock fracture profiles. Accordingly, correlations are developed between D R1 and the peak shear strength obtained from simulations and by using analytical solutions. The results are shown to be in good agreement with the basic understanding of rock fracture shear behaviour and asperity contact degradation. 相似文献
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A. Esmaeili E. Sadeghi 《International Journal of Environmental Science and Technology》2014,11(5):1271-1276
Among all environmental contaminations, industrial oil is one of the major pollutants of soil, water, and air. There are different chemical, physical, and biological methods to remove all types of oil pollutions. One of the common biological methods is to utilize the microorganisms like yeast, fungi or bacteria. Previous studies concerning the biodegradation of an aromatic compound in industrial waste water by Aspergillus niger have been reported. In this study, we tried to identify an oil-derived microorganism and evaluate its efficacy on self-removal of industrial oil. Firstly, the strain of isolated fungus from various bulks of used oil was defined via colonial identification and DNA sequencing. Secondly, bioremoval activity of defined fungus (Penicillium commune) was evaluated using gas chromatography–mass spectrometry. The optimum conditions in biological elimination of oil including the incubation time, pH level of culture, and amount of reagents were determined. In the best condition, a removal rate of 95.4 % was obtained. 相似文献
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Abdolvahab Kazemi Abbas Sadeghi Mohammad Hosein Adabi 《Arabian Journal of Geosciences》2014,7(2):655-664
In biostratigraphic studies of the Surgah formation in the Kuh-e-Surgah section, 145 samples were collected. The thickness of the Surgah formation is about 175 m, and it consists mainly of limestone and shale. The lower and upper boundaries of the Surgah formation are Sarvak and Ilam formations, respectively, and they are conformable with sharp lithology. Seventeen species which belong to six genera of planktonic foraminifera and four biozones have been identified in this study. Based on foraminifera assemblages and biozone determinations, the age of the Surgah formation is Late Turonian to Early Late Santonian. This section is correlated with the Tang-e-Gerab section. 相似文献
100.
Natural Resources Research - Fractal/multifractal modeling is a widely used geomathematical approach to capturing different populations in geochemical mapping. The rationale of this methodology is... 相似文献