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Ultrasonic prediction of crack density using machine learning:A numerical investigation

Geoscience Frontiers 2022年第1期13卷 114-126页

作者： sadegh karimpouli Pejman Tahmasebi Erik HSaenger Mining Engineering Group Faculty of EngineeringUniversity of ZanjanZanjanIran Department of Petroleum Engineering University of WyomingLaramieWY 82071USA Bochum University of Applied Sciences 44801 BochumGermany Fraunhofer IEG Fraunhofer Research Institution for Energy Infrastructure and Geothermal Systems44801 BochumGermany Ruhr-University Bochum 44801 BochumGermany

Cracks are accounted as the most destructive discontinuity in rock, soil, and concrete. Enhancing our knowledge from their properties such as crack distribution, density, and/or aspect ratio is crucial in geo-systems. The most well-known mechanical parameter for such an evaluation is wave velocity through which one can qualitatively or quantitatively characterize the porous media. In small scales, such information is obtained using the ultrasonic pulse velocity(UPV) technique as a non-destructive test. In large-scale geo-systems, however, it is inverted from seismic data. In this paper, we take advantage of the recent advancements in machine learning(ML) for analyzing wave signals and predict rock properties such as crack density(CD) – the number of cracks per unit volume. To this end, we designed numerical models with different CDs and, using the rotated staggered finite-difference grid(RSG) technique, simulated wave propagation. Two ML networks, namely Convolutional Neural Networks(CNN) and Long Short-Term Memory(LSTM), are then used to predict CD values. Results show that, by selecting an optimum value for wavelength to crack length ratio, the accuracy of predictions of test data can reach R2> 96% with mean square error(MSE) < 25e-4(normalized values). Overall, we found that:(i) performance of both CNN and LSTM is highly promising,(ii) accuracy of the transmitted signals is slightly higher than the reflected signals,(iii) accuracy of 2D signals is marginally higher than 1D signals,(iv)accuracy of horizontal and vertical component signals are comparable,(v) accuracy of coda signals is less when the whole signals are used. Our results, thus, reveal that the ML methods can provide rapid solutions and estimations for crack density, without the necessity of further modeling.

关键词： Machine learning Crack density Ultrasonic wave Numerical computation

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Physics informed machine learning: Seismic wave equation

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Geoscience Frontiers 2020年第6期11卷 1993-2001页

作者： sadegh karimpouli Pejman Tahmasebi Mining Engineering Group Faculty of EngineeringUniversity of ZanjanZanjanIran Department of Petroleum Engineering University of WyomingLaramieWY82071USA

Similar to many fields of sciences,recent deep learning advances have been applied extensively in geosciences for both small-and large-scale ***,the necessity of using large training data and the’black box’nature of learning have limited them in practice and difficult to ***,including the governing equations and physical facts in such methods is also another challenge,which entails either ignoring the physics or simplifying them using unrealistic *** address such issues,physics informed machine learning methods have been developed which can integrate the governing physics law into the learning *** this work,a 1-dimensional(1 D)time-dependent seismic wave equation is considered and solved using two methods,namely Gaussian process(GP)and physics informed neural *** show that these meshless methods are trained by smaller amount of data and can predict the solution of the equation with even high *** are also capable of inverting any parameter involved in the governing equation such as wave velocity in our *** show that the GP can predict the solution of the seismic wave equation with a lower level of error,while our developed neural network is more accurate for velocity(P-and S-wave)and density inversion.

关键词： Gaussian process(GP) Physics informed machine learning(PIML) Seismic wave Optimization

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An investigation on prevalent strategies for XFEM-based numerical modeling of crack growth in porous media

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Frontiers of Structural and Civil Engineering 2021年第4期15卷 914-936页

作者： Mohammad REZANEZHAD Seyed Ahmad LAJEVARDI sadegh karimpouli Mining Engineering Group Faculty of EngineeringUniversity of ZanjanZanjan45371-38791Iran Materials Engineering Group Faculty of EngineeringUniversity of ZanjanZanjan45371-38791Iran

Crack growth modeling has always been one of the major challenges in fracture *** all numerical methods,the extended finite element method(XFEM)has recently attracted much attention due to its ability to estimate the discontinuous deformation ***,XFEM modeling does not directly lead to reliable results,and choosing a strategy of implementation is inevitable,especially in porous *** this study,two prevalent XFEM strategies are evaluated:a)applying reduced Young’s modulus to pores and b)using different partitions to the model and enriching each part *** mention the advantages and limitations of each strategy via both analytical and experimental ***,the crack growth is modeled in a natural porous media(Fontainebleau sandstone).Our investigations proved that although both strategies can identically predict the stress distribution in the sample,the first strategy simulates only the initial crack propagation,while the second strategy could model multiple cracks *** strategies are reliable and highly accurate in calculating the stress intensity factor,but the second strategy can compute a more reliable reaction *** tests showed that the second strategy is a more accurate strategy in predicting the preferred crack growth path and determining the maximum strength of the sample.

关键词： numerical modeling extended finite element method porous media crack growth stress intensity factor

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Analysis of Spray Evaporation in a Model Evaporating Chamber:Effect of Air Swirl

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Journal of Thermal Science 2023年第2期32卷 837-853页

作者： Mohammad sadegh ABEDINEJAD Department of Mechanical Engineering Faculty of EngineeringAlzahra UniversityTehranIran

Spray evaporation of liquid fuels in a turbulent flow is a common process in various engineering applications such as *** between fuel droplets(discrete phase)and fluid flow(continuous phase)have a considerable effect on liquid fuel *** this paper,both the single-and two-phase modeling of liquid fuel injection into a model evaporating chamber are *** influences of important issues such as turbulence models,coupling between gas phase and droplets,secondary break-up and air swirling on the current spray simulation are ***,the shear stress transport turbulence model,Taylor analogy break-up and two-way coupling models are applied to simulate the two-phase *** and spray of fuel droplets in hot air are modeled employing an Eulerian-Lagrangian *** current results show an acceptable agreement with the *** the fuel atomizer,bigger droplets are detected near the spray edge and minor droplets are situated in the *** increasing the droplets axial position,the droplets diameter decreases with a finite *** smaller droplets have a deeper penetration,but their lifetime is smaller and they evaporate sooner.A linear relation between penetration and lifetime of smaller droplets is *** droplet penetration and mean axial velocity of gas phase are observed for no air swirling *** effect of variation of swirl number on the lifetime of droplets is almost *** enhancing the swirl number,the uniformity of droplet size distribution is reduced and some large droplets are formed up in the domain.

关键词： secondary break-up droplet evaporation air swirling fuel spray gas-droplets coupling

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Nonlinear finite time attitude control of flexible spacecraft based on a novel output redefinition method

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Chinese Journal of Aeronautics 2023年第11期36卷 373-385页

作者： Seyed Majid ESMAEILZADEH Mohammad sadegh ZEYGHAMI Department of Electrical Engineering Iran University of Science and TechnologyNarmakTehran 16846-13114Iran

A finite time attitude controller is designed for a flexible spacecraft based on a novel output redefinition method, in this paper. To make the flexible appendages vibration suppression effective, the appendage tip-point is selected as the output. First, a novel output redefinition method is proposed to overcome the non-minimum phase property of the dynamic model. The proposed method not only makes the system model minimum phase but also improves the attitude control system performance. Consequently, the precise attitude pointing and stabilization are ***, a nonlinear finite time H∞controller is designed based on the backstepping approach. For the situation where the modal variables measurements are not available, a modal observer is also designed. The simulation results show the effectiveness of the proposed method in the presence of the model uncertainties and environmental disturbances.

关键词： Finite time Output redefinition H1 control Attitude control Flexible spacecraft Backstepping Robust

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Nano-scale pore distribution characterisation of coal using small angle X-ray scattering

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Particuology 2023年第10期81卷 73-85页

作者： Peng Jia Jinzhang Jia sadegh Nadimi College of Safety Science and Engineering Liaoning Technical UniversityFuxinLiaoning123000China School of Engineering Newcastle UniversityNE17RUUK

In the process of coal seam fracturing with liquid nitrogen(LN_(2)),the change of coal pore structure has an important influence on the efficiency of coalbed methane(CBM)*** nano-scale pore size distribution(PSD)in coal particles before and after freezing with LN_(2) are experimentally studied in this *** samples are collected from four coal mines,where coal and gas outburst accidents have *** angle X-ray scattering technology(SAXS)and scanning electron microscopy(SEM)are used to study the pore structure changes of coal samples quantitatively and *** is found that the scattering intensity of coal samples increases after *** PSD of all samples significantly changes in the range of 0.8–7 nm,showing new pore spaces in 0.8–4 nm and fewer pores in the 4–7 nm *** the pore fractal dimension and the radius of gyration of coal samples increase after freezing and are mainly affected by the changes in pores and the anisotropy of the coal *** expansion and pore connections are observed in the surface structure of the coal sample using *** study provides a better understanding of the nano-scale mechanism of coal seam fracturing with LN_(2) for the prevention of coal and gas outbursts.

关键词： Coalbed methane Small angle X-ray scattering LN2 freezing Pore size distribution(PSD) Particle characterisation Fractal dimension

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Mobile Multimedia Computing in Cyber-Physical Surveillance Services Through UAV-Borne Video-SAR:A Taxonomy of Intelligent Data Processing for IoMT-Enabled Radar Sensor Networks

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Tsinghua Science and Technology 2022年第2期27卷 288-302页

作者： Mohammad R.Khosravi sadegh Samadi Department of Electrical and Electronics Engineering Shiraz University of TechnologyShiraz 313-71555Iran

This study investigates the different aspects of multimedia computing in Video Synthetic Aperture Radar(Video-SAR)as a new mode of radar imaging for real-time remote sensing and *** research also considers new suggestions in the systematic design,research taxonomy,and future trends of radar data *** the conventional modes of SAR imaging,Video-SAR can generate video sequences to obtain online monitoring and green surveillance throughout the day and night(regardless of light sources)in all ***,an introduction to Video-SAR is ***,some specific properties of this imaging mode are ***,this research covers one of the most important aspects of the Video-SAR systems,namely,the systematic design requirements,and also some new types of visual distortions which are different from the distortions,artifacts and noises observed in the conventional imaging *** addition,some topics on the general features and high-performance computing of Video-SAR towards radar communications through Unmanned Aerial Vehicle(UAV)platforms,Internet of Multimedia Things(IoMT),Video-SAR data processing issues,and real-world applications are investigated.

关键词： Video Synthetic Aperture Radar(Video-SAR)imaging radar networks radar image processing high-performance computing Internet of Multimedia Things(IoMT) cybersecurity

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Formation evaluation and rock type classification of Asmari Formation based on petrophysical-petrographic data:A case study in one of super fields in Iran southwest

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Petroleum 2023年第2期9卷 143-165页

作者： Raeza Mirzaee Mahmoodabadi sadegh Zahiri Department of Geology Estahban BranchIslamic Azad UniversityEstahbanIran National Iranian South Oil Company(NISOC) AhvazIran

The Oligo-Miocene Asmari Formation is one of the most important hydrocarbon reservoirs in the Middle *** oilfield under study is one of the largest oilfields in the Zagros basin with the Asmari Formation being the major reservoir *** this study,petrographic analyses,petrophysical data and neural network clustering techniques were used for identifying rock types in the Asmari *** analysis of the Asmari Formation in the study area has resulted in the definition of 1 clastic lithofacies and 14 carbonate microfacies *** petrophysical logs from 43 wells and their correlation with capillary pressure(Pc)curves,led to the recognition of 7 electrofacies(EF1-EF7).Microscopic evidence of Electrofacies group C1 and S1 show that the sedimentary facies of these electrofacies are most commonly found in restricted and shoal facies belts ***,petrographic studies show that the sedimentary facies of C2,C3,C4,S2 and S3 were formed in the open marine,Lagoon,and Tidal flat facies belt zone of homoclinal ramp sedimentary environment during the Oligo-Miocene based on relative sea level changes *** link between electrofacies and geological data indicated that both sedimentary and diagenetic processes controlled the reservoir quality of the Asmari ***,permeability and water saturation were used to estimate the reservoir quality of each *** 1 and 2 with high porosity and permeability,low water saturation is considered as the best reservoir with regard to sedimentary textures(dolowackestone and dolograinstone)and the effect of diagenetic processes such as dolomitization ***,growth framework and interparticle porosities are major in EF-2,while the intercrystalline porosity is the major type in *** 3 and 4 show low values of porosity,permeability and high percentage of water saturations,which characterizes them as poor reservoir ***,EF-5 is the only electrofacies in the siliciclastic parts of

关键词： Asmari formation Electrofacies Petrophysical log Rock typing Zagros basin

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Robust low-rank learning multi-output regression for incipient sediment motion in sewer pipes

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International Journal of Sediment Research 2023年第6期38卷 859-870页

作者： Mir Jafar sadegh Safari Shervin Rahimzadeh Arashloo Department of Civil Engineering Yasar University Department of Computer Engineering Bilkent University

The existing incipient sediment motion models typically apply conventional regression methods considering either velocity or shear *** the current study,incipient sediment motion is analyzed through a simultaneous and joint analysis of velocity and shear stress using the robust low-rank learning(RLRL) multi-output regression ***,the experimental data compiled from five different channels are utilized to develop a generic incipient sediment motion model valid for a channel of any cross-sectional *** efficiency of the developed method is examined and compared against the available conventional regression *** experimental results indicate that the RLRL model yields better results than its *** particular,while cross-section specific models fail to provide accurate estimates for shear stress or velocity for other cross sections,the proposed model provides satisfactory results for all channel *** better performance of the recommended approach can be attributed to the joint modeling of the shear stress and the velocity which is realized by capturing the correlation between these parameters in terms of a low rank output mixing matrix which enhances the prediction performance of the approach.

关键词： Low-rank learning Multi-output regression Sediment transport Sewer flow Shear stress approach Velocity approach

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Forty Years of Air Temperature Change over Iran Reveals Linear and Nonlinear Warming

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Journal of Meteorological Research 2022年第3期36卷 462-477页

作者： Majid KAZEMZADEH Zahra NOORI sadegh JAMALI Abdulhakim M.ABDI Faculty of Natural Resources University of Tehran77871-31587KarajIran Department of Technology and Society Lund UniversitySE-22100LundSweden Centre for Environmental and Climate Science Lund UniversitySE-22362LundSweden

Spatiotemporal analysis of long-term changes in air temperature is of prime importance for climate change research and the development of effective mitigation and adaptation *** there are considerable studies on air temperature change across the globe,most of them have been on linear trends and time series analysis of nonlinear trends have not received enough ***,spatiotemporal patterns of monthly and annual mean(Tmean),maximum(T_(max)),and minimum(T_(min))air temperature at 47 synoptic stations across climate zones in Iran for a 40-yr period(1978–2017)are analyzed.A polynomial fitting scheme(Polytrend)is used to both monthly and annual air temperature data to detect trends and classify them into linear and nonlinear(quadratic and cubic)*** significant(non-significant)trends in Tmean,T_(max),and T_(min) across all climate zones are 41.1%(58.9%),34.1%(65.9%),and 46%(54%),*** highest magnitude of increasing trends is observed in the annual T_(min)(0.47℃decade−1)and the lowest magnitude is for the annual T_(max)(0.4℃decade−1).Across the country,increasing trends(=37.2%)have higher spatial coverage than the decreasing trends(=3.2%).Warming trends in Tmean(65.3%)and T_(min)(73.1%)are mainly observed in humid climate zone while warming trends in T_(max) are in semi-arid(43.9%)and arid(34.1%)*** change with a positive trend is predominant in all Tmean(56.7%),T_(max)(67.8%),and T_(min)(71.2%)and for both monthly and annual ***,the linear trends have the highest warming rate in annual T_(min)(0.83℃decade^(−1))and Tmean(0.46℃decade^(−1))whereas the nonlinear trends have the highest warming rate in annual T_(max)(0.52℃decade^(−1)).The linear trend type is predominant across the country especially in humid climate zones whereas the nonlinear trends(quadratic and cubic)are mainly observed in the arid climate *** study highlights nonlinear changes and spatiotemporal trends in air temperature in Iran an

关键词： linear trends nonlinear trends time series analysis air temperature Polytrend Iran

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