A parallel finite element scheme for 3D resistivity method forward modeling is introduced in this article.The domain decomposition algorithm,along with a message passing interface,is used to implement parallelism.The ...A parallel finite element scheme for 3D resistivity method forward modeling is introduced in this article.The domain decomposition algorithm,along with a message passing interface,is used to implement parallelism.The computational domain is divided into subdomains,and mesh partitioning is combined with load balancing.Unstructured meshes and local mesh refinement strategies are used to realize high precision for complex topography models.Furthermore,an improved linear solver for multi-electrode resistivity method modeling is adopted.Recycling preconditioned conjugate gradient,which is a linear solver,is based on the similarity of linear systems between point sources.The multiple right-hand-side linear systems corresponding to different point source positions are constructed,and the accelerated convergence is obtained through recycling subspace using the linear solver.The computational accuracy and efficiency of the forward scheme for complex topography models are verified using the numerical test results.展开更多
In the leakage detection of reservoir dam bodies,traditional geophysical methods can only achieve one-time detection.Meanwhile,due to the non-uniqueness of geophysicalin version,how to improve the fidelity of geophysi...In the leakage detection of reservoir dam bodies,traditional geophysical methods can only achieve one-time detection.Meanwhile,due to the non-uniqueness of geophysicalin version,how to improve the fidelity of geophysical detection inversion profiles has become a key challenge in the industry.This study aims to construct a long-term real-time monitoring system using the time-lapse resistivity method,reveal the spatiotemporal evolution law of dam leakage,and provide technical support for accurate treatment.By integrating the Internet of Things(IoT),5G technology,and AI technology,real-time data acquisition,real-time transmission,and automatic inversionare realized.Through dynamic imaging analysis of the electrical anomaly characteristics of the leakage area and comparison between corresponding rainfall events,the leakage range and resistivity changes,the reliability and efficiency of dam leakagedete ction are significantly improved.This achieves long-termdynamic monitoring of dam leakage and provides a new perspective for the safe operation and maintenance of reservoirs.展开更多
Multi-electrodes Resistivity Imaging Survey(MRIS)is an array method of electrical survey.In practice how to choose a reasonable array is the key to get reliable survey results.Based on four methods of MRIS such as Wen...Multi-electrodes Resistivity Imaging Survey(MRIS)is an array method of electrical survey.In practice how to choose a reasonable array is the key to get reliable survey results.Based on four methods of MRIS such as Wenner,Schlumberger,Pole-pole and Dipole-dipole the authors established the model,by studying the result of the forward numerical simulation modeling and inverse modeling,and analyzed the differences among the different forms of detection devices.展开更多
To speed up three-dimensional （3D） DC resistivity modeling, we present a new multigrid method, the aggregation-based algebraic multigrid method （AGMG）. We first discretize the differential equation of the secondar...To speed up three-dimensional （3D） DC resistivity modeling, we present a new multigrid method, the aggregation-based algebraic multigrid method （AGMG）. We first discretize the differential equation of the secondary potential field with mixed boundary conditions by using a seven-point finite-difference method to obtain a large sparse system of linear equations. Then, we introduce the theory behind the pairwise aggregation algorithms for AGMG and use the conjugate-gradient method with the V-cycle AGMG preconditioner （AGMG-CG） to solve the linear equations. We use typical geoelectrical models to test the proposed AGMG-CG method and compare the results with analytical solutions and the 3DDCXH algorithm for 3D DC modeling （3DDCXH）. In addition, we apply the AGMG-CG method to different grid sizes and geoelectrical models and compare it to different iterative methods, such as ILU-BICGSTAB, ILU-GCR, and SSOR-CG. The AGMG-CG method yields nearly linearly decreasing errors, whereas the number of iterations increases slowly with increasing grid size. The AGMG-CG method is precise and converges fast, and thus can improve the computational efficiency in forward modeling of three-dimensional DC resistivity.展开更多
Since the ocean bottom is a sedimentary environment wherein stratification is well developed, the use of an anisotropic model is best for studying its geology. Beginning with Maxwell＇s equations for an anisotropic mo...Since the ocean bottom is a sedimentary environment wherein stratification is well developed, the use of an anisotropic model is best for studying its geology. Beginning with Maxwell＇s equations for an anisotropic model, we introduce scalar potentials based on the divergence-free characteristic of the electric and magnetic （EM） fields. We then continue the EM fields down into the deep earth and upward into the seawater and couple them at the ocean bottom to the transmitting source. By studying both the DC apparent resistivity curves and their polar plots, we can resolve the anisotropy of the ocean bottom. Forward modeling of a high-resistivity thin layer in an anisotropic half-space demonstrates that the marine DC resistivity method in shallow water is very sensitive to the resistive reservoir but is not influenced by airwaves. As such, it is very suitable for oil and gas exploration in shallowwater areas but, to date, most modeling algorithms for studying marine DC resistivity are based on isotropic models. In this paper, we investigate one-dimensional anisotropic forward modeling for marine DC resistivity method, prove the algorithm to have high accuracy, and thus provide a theoretical basis for 2D and 3D forward modeling.展开更多
The research about subsurface characteristics by using transient electromagnetic method（TEM） and high density resistivity method（HDRM） were already conducted in Ordos. The objective of this research is to detect c...The research about subsurface characteristics by using transient electromagnetic method（TEM） and high density resistivity method（HDRM） were already conducted in Ordos. The objective of this research is to detect coalmine goaf areas based on rock resistivity. The data processing using wavelet transform, three point smoothing, RES2 DINV and Maxwell processing software to obtain 2D resistivity structure. The results showed that the layers with maximum resistivity values（30e33 U m on Line 1, 30e31 U m on Line 2, 32e40 U m on Line3） are founded at station 1e7, and 14e20 on Line 1,13e18 on Line 2, and 8e13 and 16e20 on Line 3 which is predicted as goaf layer, and the minimum resistivity values（20e26 U m of TEM, 45e75 U m of HDRM） at the other layers. This resistivity difference was caused by the geology and characteristics of the study area which is located close by the cleugh with rich coal, so the goaf area distinguishable with aquifer layer and coal seam. The results were also significant accidents and serious destruction of ecological environment.展开更多
Electrical measurement was employed to investigate the early hydration characteristics of cement pastes with different dosages of superplasticizer in the same W/C ratio. The hyperbolic method was applied to analyze th...Electrical measurement was employed to investigate the early hydration characteristics of cement pastes with different dosages of superplasticizer in the same W/C ratio. The hyperbolic method was applied to analyze the electrical resistivity development. The peak point （Ph） on the hyperbolic curve could be easily read. The time （th） to reach the point Ph had strong relations with the setting time. th was delayed with the increment of the dosage of superplasticizer. The time th was used to plot the relationship between the initial setting time and final setting time. The hyperbolic equation was established to predict the ultimate resistivity. The retardation effect of the superplasticizer was confirmed in the same W/C ratio by setting time and isothermal heat evolution.展开更多
The objective of this work is to develop a novel methodology for determining real resistivity of conductive asphalt concrete based on two-electrode method.Due to an influence of contact resistance,the measured resisti...The objective of this work is to develop a novel methodology for determining real resistivity of conductive asphalt concrete based on two-electrode method.Due to an influence of contact resistance,the measured resistivity is always not equal to the real resistivity.To determine the real resistivity,a linear relationship of the measured resistivity,contact resistance and the real resistivity was established.Then experiments for six specimens with varying graphite contents were designed and performed to validate the formulation.Results of experiments demonstrate that the slope of the line represents contact resistance,and the intercept indicates the real resistivity.The effects of graphite content on contact resistance and real resistivity are also revealed.Finally,results show that the influence of contact resistance on accuracy of resisitvity measurement becomes more serious if graphite content is beyond 3%.Hence,it is the time to choose this novel methodology to determine the real resistivity of asphalt concrete by taking account of contact resistance.展开更多
The detecting examples using the high density resistivity method, about the evaluation of containing water characteristic from the floor rock and the height of overburden failure, were given. It expresses that the hig...The detecting examples using the high density resistivity method, about the evaluation of containing water characteristic from the floor rock and the height of overburden failure, were given. It expresses that the high density resistivity method has good effect with strong maneuverability and continuous observing section during the prevention and cure for mine water disaster. At the same time, the article pointed out that the study of space data inversion and dynamic watching technology about the high density resistivity method must be enhanced in the future because of special condition of data collecting in mine.展开更多
The compressive strength development of Portland cement pastes was investigated by the electrical resistivity method and the maturity method.The experiments were carried out on the cement pastes with different water-c...The compressive strength development of Portland cement pastes was investigated by the electrical resistivity method and the maturity method.The experiments were carried out on the cement pastes with different water-cement ratios at different curing temperatures.The results show that the application of the maturity method has limitation to obtain the strength.It is found that both of the compressive strength and the electrical resistivity follow hyperbolic trend for all the mixes.The hyperbolic equation of each mix is obtained to estimate the ultimate resistivity value which can probably be reached.The relationship between electrical resistivity and compressive strength of the cement pastes is established based on the test results and interpreted by the empirical Archie equation and a strength-porosity equation.The relationship between the electrical resistivity after temperature correction and the compressive strength was linear and independent of curing temperature and water-cement ratio.展开更多
In large loop transient electromagnetic method(TEM),the late time apparent resistivity formula cannot truly reflect the geoelectric model,thus it needs to define the all-time apparent resistivity with the position inf...In large loop transient electromagnetic method(TEM),the late time apparent resistivity formula cannot truly reflect the geoelectric model,thus it needs to define the all-time apparent resistivity with the position information of measuring point.Utilizing very fast simulated annealing(VFSA) to fit the theoretical electromagnetic force(EMF) and measured EMF could obtain the all-time apparent resistivity of the measuring points in rectangular transmitting loop.The selective cope of initial model of VFSA could be confirmed by taking the late time apparent resistivity of transient electromagnetic method as the prior information.For verifying the correctness,the all-time apparent resistivities of the geoelectric models were calculated by VFSA and dichotomy,respectively.The results indicate that the relative differences of apparent resistivities calculated by these two methods are within 3%.The change of measuring point position has little influence on the tracing pattern of all-time apparent resistivity.The first branch of the curve of all-time apparent resistivity is close to the resistivity of the first layer medium and the last branch is close to the resistivity of the last layer medium,which proves the correctness of the arithmetics proposed.展开更多
The strategies that minimize the overall solution time of multiple linear systems in 3D finite element method (FEM) modeling of direct current (DC) resistivity were discussed. A global stiff matrix is assembled and st...The strategies that minimize the overall solution time of multiple linear systems in 3D finite element method (FEM) modeling of direct current (DC) resistivity were discussed. A global stiff matrix is assembled and stored in two parts separately. One part is associated with the volume integral and the other is associated with the subsurface boundary integral. The equivalent multiple linear systems with closer right-hand sides than the original systems were constructed. A recycling Krylov subspace technique was employed to solve the multiple linear systems. The solution of the seed system was used as an initial guess for the subsequent systems. The results of two numerical experiments show that the improved algorithm reduces the iterations and CPU time by almost 50%, compared with the classical preconditioned conjugate gradient method.展开更多
By determining the distribution and extent of geological structures surrounding the Mingyan Tunnel,Xicheng Town,Helong City,Jilin Province,we can evaluate the stability of the rock mass and assess potential hazards du...By determining the distribution and extent of geological structures surrounding the Mingyan Tunnel,Xicheng Town,Helong City,Jilin Province,we can evaluate the stability of the rock mass and assess potential hazards during tunnel construction.We use the high-density resistivity method to analyze the subsurface structure of the study area.Conductive anomalies are likely to represent joint and fissure systems within strongly weathered host rocks,and the bedrock surrounding the tunnel is relatively stable and does not contain well-developed faults.High-density resistivity analysis can provide valuable information in the context of tunnel engineering and safety.展开更多
The authors employ the high-density resistivity method to image the subsurface structure of a mountain in Erdaojiang District,Tonghua City,Jilin Province,China,to evaluate the potential risk of slope failure on surrou...The authors employ the high-density resistivity method to image the subsurface structure of a mountain in Erdaojiang District,Tonghua City,Jilin Province,China,to evaluate the potential risk of slope failure on surrounding residential areas and infrastructure,and identify a shallow fault that extends across the center of the mountain and is perpendicular to the mountain slope and accurately locate the spatial position and depth of another fault on the southern side of the mountain.The results provide an important basis for evaluating mountain slope stability.This study also demonstrates that the high-density resistivity method is effective for detecting mountain faults.展开更多
The significant advantage of the complex resistivity method is to reflect the abnormal body through multi-parameters, but its inversion parameters are more than the resistivity tomography method. Therefore, how to eff...The significant advantage of the complex resistivity method is to reflect the abnormal body through multi-parameters, but its inversion parameters are more than the resistivity tomography method. Therefore, how to effectively invert these spectral parameters has become the focused area of the complex resistivity inversion. An optimized BP neural network (BPNN) approach based on Quantum Particle Swarm Optimization (QPSO) algorithm was presented, which was able to improve global search ability for complex resistivity multi-parameter nonlinear inversion. In the proposed method, the nonlinear weight adjustment strategy and mutation operator were used to enhance the optimization ability of QPSO algorithm. Implementation of proposed QPSO-BPNN was given, the network had 56 hidden neurons in two hidden layers (the first hidden layer has 46 neurons and the second hidden layer has 10 neurons) and it was trained on 48 datasets and tested on another 5 synthetic datasets. The training and test results show that BP neural network optimized by the QPSO algorithm performs better than the BP neural network without initial optimization on the inversion training and test models, and the mean square error distribution is better. At the same time, a double polarized anomalous bodies model was also used to verify the feasibility and effectiveness of the proposed method, the inversion results show that the QPSO-BP algorithm inversion clearly characterizes the anomalous boundaries and is closer to the values of the parameters.展开更多
BACKGROUND Helicobacter pylori(H.pylori),a globally prevalent pathogen,is exhibiting increasing rates of antimicrobial resistance.However,clinical implementation of pre-treatment susceptibility testing remains limited...BACKGROUND Helicobacter pylori(H.pylori),a globally prevalent pathogen,is exhibiting increasing rates of antimicrobial resistance.However,clinical implementation of pre-treatment susceptibility testing remains limited due to the organism’s fastidious growth requirements and prolonged culture time.AIM To propose a novel detection method utilizing antibiotic-supplemented media to inhibit susceptible strains,while resistant isolates were identified through urease-mediated hydrolysis of urea,inducing a phenol red color change for visual confirmation.METHODS Colombia agar was supplemented with urea,phenol red,and nickel chloride,and the final pH was adjusted to 7.35.Antibiotic-selective media were prepared by incorporating amoxicillin(0.5μg/mL),clarithromycin(2μg/mL),metronidazole(8μg/mL),or levofloxacin(2μg/mL)into separate batches.Gastric antral biopsies were homogenized and inoculated at 1.0×105 CFU onto the media,and then incubated under microaerobic conditions at 37°C for 28-36 hours.Resistance was determined based on a color change from yellow to pink,and the results were validated via broth microdilution according to Clinical and Laboratory Standards Institute guidelines.RESULTS After 28-36 hours of incubation,the drug-resistant H.pylori isolates induced a light red color change in the medium.Conversely,susceptible strains(H.pylori 26695 and G27)produced no visible color change.Compared with the conventional 11-day protocol,the novel method significantly reduced detection time.Among 201 clinical isolates,182 were successfully evaluated using the new method,resulting in a 90.5%detection rate.This was consistent with the 95.5%agreement rate observed when compared with microdilution-based susceptibility testing.The success rate of the novel approach was significantly higher than that of the comparative method(P<0.01).The accuracy of the new method was comparable to that of the dilution method.CONCLUSION The novel detection method can rapidly detect H.pylori drug resistance within 28-36 hours.With its operational simplicity and high diagnostic performance,it holds strong potential for clinical application in the management of H.pylori antimicrobial resistance.展开更多
The measurement of resistivity in a compressed material within a diamond anvil cell presents significant challenges.The high-pressure exper-imental setup makes it difficult to directly measure the size changes induced...The measurement of resistivity in a compressed material within a diamond anvil cell presents significant challenges.The high-pressure exper-imental setup makes it difficult to directly measure the size changes induced by pressure in the three crystallographic directions of the sample.In this study,we introduce a novel and effective method that addresses these technical challenges.This method is anticipated to offer a valuable foundation for high-pressure investigations on quantum materials,particularly those with anisotropic layered structures.展开更多
The Jiaoshiba shale gasfield is located in the Fuling area of the Sichuan Basin,with the Upper Ordovician Wufeng-Lower Silurian Longmaxi Fm as the pay zone.At the bottom of the pay zone,a high-quality shale gas reserv...The Jiaoshiba shale gasfield is located in the Fuling area of the Sichuan Basin,with the Upper Ordovician Wufeng-Lower Silurian Longmaxi Fm as the pay zone.At the bottom of the pay zone,a high-quality shale gas reservoir about 20 m thick is generally developed with high organic contents and gas abundance,but its resistivity is relatively low.Accordingly,the gas saturation calculated by formulas(e.g.Archie)using electric logging data is often much lower than the experiment-derived value.In this paper,a new method was presented for calculating gas saturation more accurately based on non-electric logging data.Firstly,the causes for the low resistivity of shale gas reservoirs in this area were analyzed.Then,the limitation of traditional methods for calculating gas saturation based on electric logging data was diagnosed,and the feasibility of the neutronedensity porosity overlay method was illustrated.According to the response characteristics of neutron,density and other porosity logging in shale gas reservoirs,a model for calculating gas saturation of shale gas was established by core experimental calibration based on the density logging value,the density porosity and the difference between density porosity and neutron porosity,by means of multiple methods(e.g.the dual-porosity overlay method by optimizing the best overlay coefficient).This new method avoids the effect of low resistivity,and thus can provide normal calculated gas saturation of high-quality shale gas reservoirs.It works well in practical application.This new method provides a technical support for the calculation of shale gas reserves in this area.展开更多
The complex resistivity of coal and related rocks contains abundant physical property information,which can be indirectly used to study the lithology and microstructure of these materials.These aspects are closely rel...The complex resistivity of coal and related rocks contains abundant physical property information,which can be indirectly used to study the lithology and microstructure of these materials.These aspects are closely related to the fluids inside the considered coal rocks,such as gas,water and coalbed methane.In the present analysis,considering different lithological structures,and using the Cole-Cole model,a forward simulation method is used to study different physical parameters such as the zero-frequency resistivity,the polarizability,the relaxation time,and the frequency correlation coefficient.Moreover,using a least square technique,a complex resistivity“inversion”algorithm is written.The comparison of the initial model parameters and those obtained after inversion is used to verify the stability and accuracy of such approach.The method is finally applied to primary-structure coal considered as the experimental sample for complex resistivity measurements.展开更多
To reduce the shielding effect of hardened layers on electrical resistivity tomography,a ratio method based on the distortion correction principle and the isolation coefficient is proposed.The effects of the resistivi...To reduce the shielding effect of hardened layers on electrical resistivity tomography,a ratio method based on the distortion correction principle and the isolation coefficient is proposed.The effects of the resistivity and thickness of hardened concrete layers on the detection of target objects are explored.Both numerical simulations and indoor tank tests indicate that when the ratio method is employed to correct the original collected data,the maximum allowable error for the isolation coefficient should not exceed 1%.Notably,when the ratio of hardened layer thickness to electrode spacing does not exceed 1,correction through this method significantly enhances the recognition capability of target objects.However,when the hardened layer thickness is greater than the electrode spacing by a factor of 2 or more,the ratio method cannot achieve satisfactory results.The case study of flood control engineering detection in the Zhangxi section of the Huangpen River in Dongzhi County demonstrates that the detection effect after correction by the ratio method is comparable to that for the adjacent unhardened pavement,and the influence of the hardened layer is obviously weakened,resulting in more reliable results.展开更多
基金supported by the National Natural Science Foundation of China(No:42274182)Guangxi Natural Science Foundation(No:2020 GXNSFAA297079)。
文摘A parallel finite element scheme for 3D resistivity method forward modeling is introduced in this article.The domain decomposition algorithm,along with a message passing interface,is used to implement parallelism.The computational domain is divided into subdomains,and mesh partitioning is combined with load balancing.Unstructured meshes and local mesh refinement strategies are used to realize high precision for complex topography models.Furthermore,an improved linear solver for multi-electrode resistivity method modeling is adopted.Recycling preconditioned conjugate gradient,which is a linear solver,is based on the similarity of linear systems between point sources.The multiple right-hand-side linear systems corresponding to different point source positions are constructed,and the accelerated convergence is obtained through recycling subspace using the linear solver.The computational accuracy and efficiency of the forward scheme for complex topography models are verified using the numerical test results.
文摘In the leakage detection of reservoir dam bodies,traditional geophysical methods can only achieve one-time detection.Meanwhile,due to the non-uniqueness of geophysicalin version,how to improve the fidelity of geophysical detection inversion profiles has become a key challenge in the industry.This study aims to construct a long-term real-time monitoring system using the time-lapse resistivity method,reveal the spatiotemporal evolution law of dam leakage,and provide technical support for accurate treatment.By integrating the Internet of Things(IoT),5G technology,and AI technology,real-time data acquisition,real-time transmission,and automatic inversionare realized.Through dynamic imaging analysis of the electrical anomaly characteristics of the leakage area and comparison between corresponding rainfall events,the leakage range and resistivity changes,the reliability and efficiency of dam leakagedete ction are significantly improved.This achieves long-termdynamic monitoring of dam leakage and provides a new perspective for the safe operation and maintenance of reservoirs.
基金Supported by Project of the National High Technology Research and Development Program of China(No.2007AA06Z215)
文摘Multi-electrodes Resistivity Imaging Survey(MRIS)is an array method of electrical survey.In practice how to choose a reasonable array is the key to get reliable survey results.Based on four methods of MRIS such as Wenner,Schlumberger,Pole-pole and Dipole-dipole the authors established the model,by studying the result of the forward numerical simulation modeling and inverse modeling,and analyzed the differences among the different forms of detection devices.
基金supported by the Natural Science Foundation of China(Nos.41404057,41674077 and 411640034)the Nuclear Energy Development Project of China,and the‘555’Project of Gan Po Excellent People
文摘To speed up three-dimensional （3D） DC resistivity modeling, we present a new multigrid method, the aggregation-based algebraic multigrid method （AGMG）. We first discretize the differential equation of the secondary potential field with mixed boundary conditions by using a seven-point finite-difference method to obtain a large sparse system of linear equations. Then, we introduce the theory behind the pairwise aggregation algorithms for AGMG and use the conjugate-gradient method with the V-cycle AGMG preconditioner （AGMG-CG） to solve the linear equations. We use typical geoelectrical models to test the proposed AGMG-CG method and compare the results with analytical solutions and the 3DDCXH algorithm for 3D DC modeling （3DDCXH）. In addition, we apply the AGMG-CG method to different grid sizes and geoelectrical models and compare it to different iterative methods, such as ILU-BICGSTAB, ILU-GCR, and SSOR-CG. The AGMG-CG method yields nearly linearly decreasing errors, whereas the number of iterations increases slowly with increasing grid size. The AGMG-CG method is precise and converges fast, and thus can improve the computational efficiency in forward modeling of three-dimensional DC resistivity.
基金financially supported by the National Hi-tech Research and Development Program of China(863 Program)(No.2012AA09A20103)
文摘Since the ocean bottom is a sedimentary environment wherein stratification is well developed, the use of an anisotropic model is best for studying its geology. Beginning with Maxwell＇s equations for an anisotropic model, we introduce scalar potentials based on the divergence-free characteristic of the electric and magnetic （EM） fields. We then continue the EM fields down into the deep earth and upward into the seawater and couple them at the ocean bottom to the transmitting source. By studying both the DC apparent resistivity curves and their polar plots, we can resolve the anisotropy of the ocean bottom. Forward modeling of a high-resistivity thin layer in an anisotropic half-space demonstrates that the marine DC resistivity method in shallow water is very sensitive to the resistive reservoir but is not influenced by airwaves. As such, it is very suitable for oil and gas exploration in shallowwater areas but, to date, most modeling algorithms for studying marine DC resistivity are based on isotropic models. In this paper, we investigate one-dimensional anisotropic forward modeling for marine DC resistivity method, prove the algorithm to have high accuracy, and thus provide a theoretical basis for 2D and 3D forward modeling.
基金supported by the Institute of Seismology Foundation, China Earthquake Administration (201326126)
文摘The research about subsurface characteristics by using transient electromagnetic method（TEM） and high density resistivity method（HDRM） were already conducted in Ordos. The objective of this research is to detect coalmine goaf areas based on rock resistivity. The data processing using wavelet transform, three point smoothing, RES2 DINV and Maxwell processing software to obtain 2D resistivity structure. The results showed that the layers with maximum resistivity values（30e33 U m on Line 1, 30e31 U m on Line 2, 32e40 U m on Line3） are founded at station 1e7, and 14e20 on Line 1,13e18 on Line 2, and 8e13 and 16e20 on Line 3 which is predicted as goaf layer, and the minimum resistivity values（20e26 U m of TEM, 45e75 U m of HDRM） at the other layers. This resistivity difference was caused by the geology and characteristics of the study area which is located close by the cleugh with rich coal, so the goaf area distinguishable with aquifer layer and coal seam. The results were also significant accidents and serious destruction of ecological environment.
基金the National Natural Science Foundation of China(No.50778078)
文摘Electrical measurement was employed to investigate the early hydration characteristics of cement pastes with different dosages of superplasticizer in the same W/C ratio. The hyperbolic method was applied to analyze the electrical resistivity development. The peak point （Ph） on the hyperbolic curve could be easily read. The time （th） to reach the point Ph had strong relations with the setting time. th was delayed with the increment of the dosage of superplasticizer. The time th was used to plot the relationship between the initial setting time and final setting time. The hyperbolic equation was established to predict the ultimate resistivity. The retardation effect of the superplasticizer was confirmed in the same W/C ratio by setting time and isothermal heat evolution.
基金Project(51178348)supported by the National Natural Science Foundation of China
文摘The objective of this work is to develop a novel methodology for determining real resistivity of conductive asphalt concrete based on two-electrode method.Due to an influence of contact resistance,the measured resistivity is always not equal to the real resistivity.To determine the real resistivity,a linear relationship of the measured resistivity,contact resistance and the real resistivity was established.Then experiments for six specimens with varying graphite contents were designed and performed to validate the formulation.Results of experiments demonstrate that the slope of the line represents contact resistance,and the intercept indicates the real resistivity.The effects of graphite content on contact resistance and real resistivity are also revealed.Finally,results show that the influence of contact resistance on accuracy of resisitvity measurement becomes more serious if graphite content is beyond 3%.Hence,it is the time to choose this novel methodology to determine the real resistivity of asphalt concrete by taking account of contact resistance.
文摘The detecting examples using the high density resistivity method, about the evaluation of containing water characteristic from the floor rock and the height of overburden failure, were given. It expresses that the high density resistivity method has good effect with strong maneuverability and continuous observing section during the prevention and cure for mine water disaster. At the same time, the article pointed out that the study of space data inversion and dynamic watching technology about the high density resistivity method must be enhanced in the future because of special condition of data collecting in mine.
基金Funding by the National Natural Science Foundation of China (Nos.50778078 and 51178202)the Doctoral Research Fund from Wuhan Institute of Technology
文摘The compressive strength development of Portland cement pastes was investigated by the electrical resistivity method and the maturity method.The experiments were carried out on the cement pastes with different water-cement ratios at different curing temperatures.The results show that the application of the maturity method has limitation to obtain the strength.It is found that both of the compressive strength and the electrical resistivity follow hyperbolic trend for all the mixes.The hyperbolic equation of each mix is obtained to estimate the ultimate resistivity value which can probably be reached.The relationship between electrical resistivity and compressive strength of the cement pastes is established based on the test results and interpreted by the empirical Archie equation and a strength-porosity equation.The relationship between the electrical resistivity after temperature correction and the compressive strength was linear and independent of curing temperature and water-cement ratio.
基金Projects(40804027,41074085) supported by the National Natural Science Foundation of ChinaProject(09JJ3048) supported by the Natural Science Foundation of Hunan Province,ChinaProject(200805331082) supported by the Research Fund for the Doctoral Program of Higher Education,China
文摘In large loop transient electromagnetic method(TEM),the late time apparent resistivity formula cannot truly reflect the geoelectric model,thus it needs to define the all-time apparent resistivity with the position information of measuring point.Utilizing very fast simulated annealing(VFSA) to fit the theoretical electromagnetic force(EMF) and measured EMF could obtain the all-time apparent resistivity of the measuring points in rectangular transmitting loop.The selective cope of initial model of VFSA could be confirmed by taking the late time apparent resistivity of transient electromagnetic method as the prior information.For verifying the correctness,the all-time apparent resistivities of the geoelectric models were calculated by VFSA and dichotomy,respectively.The results indicate that the relative differences of apparent resistivities calculated by these two methods are within 3%.The change of measuring point position has little influence on the tracing pattern of all-time apparent resistivity.The first branch of the curve of all-time apparent resistivity is close to the resistivity of the first layer medium and the last branch is close to the resistivity of the last layer medium,which proves the correctness of the arithmetics proposed.
基金Projects(40974077,41164004)supported by the National Natural Science Foundation of ChinaProject(2007AA06Z134)supported by the National High Technology Research and Development Program of China+2 种基金Projects(2011GXNSFA018003,0832263)supported by the Natural Science Foundation of Guangxi Province,ChinaProject supported by Program for Excellent Talents in Guangxi Higher Education Institution,ChinaProject supported by the Foundation of Guilin University of Technology,China
文摘The strategies that minimize the overall solution time of multiple linear systems in 3D finite element method (FEM) modeling of direct current (DC) resistivity were discussed. A global stiff matrix is assembled and stored in two parts separately. One part is associated with the volume integral and the other is associated with the subsurface boundary integral. The equivalent multiple linear systems with closer right-hand sides than the original systems were constructed. A recycling Krylov subspace technique was employed to solve the multiple linear systems. The solution of the seed system was used as an initial guess for the subsequent systems. The results of two numerical experiments show that the improved algorithm reduces the iterations and CPU time by almost 50%, compared with the classical preconditioned conjugate gradient method.
基金Supported by The National Natural Science Foundation of China(41504076)Jilin Science and Technological Development Program(20180101093JC)。
文摘By determining the distribution and extent of geological structures surrounding the Mingyan Tunnel,Xicheng Town,Helong City,Jilin Province,we can evaluate the stability of the rock mass and assess potential hazards during tunnel construction.We use the high-density resistivity method to analyze the subsurface structure of the study area.Conductive anomalies are likely to represent joint and fissure systems within strongly weathered host rocks,and the bedrock surrounding the tunnel is relatively stable and does not contain well-developed faults.High-density resistivity analysis can provide valuable information in the context of tunnel engineering and safety.
基金Supported by National Key R&D Program of China and Fundamental Research Funds for the Central Universities(2017YFC0601305)。
文摘The authors employ the high-density resistivity method to image the subsurface structure of a mountain in Erdaojiang District,Tonghua City,Jilin Province,China,to evaluate the potential risk of slope failure on surrounding residential areas and infrastructure,and identify a shallow fault that extends across the center of the mountain and is perpendicular to the mountain slope and accurately locate the spatial position and depth of another fault on the southern side of the mountain.The results provide an important basis for evaluating mountain slope stability.This study also demonstrates that the high-density resistivity method is effective for detecting mountain faults.
文摘The significant advantage of the complex resistivity method is to reflect the abnormal body through multi-parameters, but its inversion parameters are more than the resistivity tomography method. Therefore, how to effectively invert these spectral parameters has become the focused area of the complex resistivity inversion. An optimized BP neural network (BPNN) approach based on Quantum Particle Swarm Optimization (QPSO) algorithm was presented, which was able to improve global search ability for complex resistivity multi-parameter nonlinear inversion. In the proposed method, the nonlinear weight adjustment strategy and mutation operator were used to enhance the optimization ability of QPSO algorithm. Implementation of proposed QPSO-BPNN was given, the network had 56 hidden neurons in two hidden layers (the first hidden layer has 46 neurons and the second hidden layer has 10 neurons) and it was trained on 48 datasets and tested on another 5 synthetic datasets. The training and test results show that BP neural network optimized by the QPSO algorithm performs better than the BP neural network without initial optimization on the inversion training and test models, and the mean square error distribution is better. At the same time, a double polarized anomalous bodies model was also used to verify the feasibility and effectiveness of the proposed method, the inversion results show that the QPSO-BP algorithm inversion clearly characterizes the anomalous boundaries and is closer to the values of the parameters.
基金Supported by the Guangxi Science and Technology Major Projects,No.AA23073012the National Natural Science Foundation of China,No.32360035 and No.32060018。
文摘BACKGROUND Helicobacter pylori(H.pylori),a globally prevalent pathogen,is exhibiting increasing rates of antimicrobial resistance.However,clinical implementation of pre-treatment susceptibility testing remains limited due to the organism’s fastidious growth requirements and prolonged culture time.AIM To propose a novel detection method utilizing antibiotic-supplemented media to inhibit susceptible strains,while resistant isolates were identified through urease-mediated hydrolysis of urea,inducing a phenol red color change for visual confirmation.METHODS Colombia agar was supplemented with urea,phenol red,and nickel chloride,and the final pH was adjusted to 7.35.Antibiotic-selective media were prepared by incorporating amoxicillin(0.5μg/mL),clarithromycin(2μg/mL),metronidazole(8μg/mL),or levofloxacin(2μg/mL)into separate batches.Gastric antral biopsies were homogenized and inoculated at 1.0×105 CFU onto the media,and then incubated under microaerobic conditions at 37°C for 28-36 hours.Resistance was determined based on a color change from yellow to pink,and the results were validated via broth microdilution according to Clinical and Laboratory Standards Institute guidelines.RESULTS After 28-36 hours of incubation,the drug-resistant H.pylori isolates induced a light red color change in the medium.Conversely,susceptible strains(H.pylori 26695 and G27)produced no visible color change.Compared with the conventional 11-day protocol,the novel method significantly reduced detection time.Among 201 clinical isolates,182 were successfully evaluated using the new method,resulting in a 90.5%detection rate.This was consistent with the 95.5%agreement rate observed when compared with microdilution-based susceptibility testing.The success rate of the novel approach was significantly higher than that of the comparative method(P<0.01).The accuracy of the new method was comparable to that of the dilution method.CONCLUSION The novel detection method can rapidly detect H.pylori drug resistance within 28-36 hours.With its operational simplicity and high diagnostic performance,it holds strong potential for clinical application in the management of H.pylori antimicrobial resistance.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1403900 and 2021YFA1401800)the NSF of China(Grant Nos.U2032214 and 12104487).
文摘The measurement of resistivity in a compressed material within a diamond anvil cell presents significant challenges.The high-pressure exper-imental setup makes it difficult to directly measure the size changes induced by pressure in the three crystallographic directions of the sample.In this study,we introduce a novel and effective method that addresses these technical challenges.This method is anticipated to offer a valuable foundation for high-pressure investigations on quantum materials,particularly those with anisotropic layered structures.
文摘The Jiaoshiba shale gasfield is located in the Fuling area of the Sichuan Basin,with the Upper Ordovician Wufeng-Lower Silurian Longmaxi Fm as the pay zone.At the bottom of the pay zone,a high-quality shale gas reservoir about 20 m thick is generally developed with high organic contents and gas abundance,but its resistivity is relatively low.Accordingly,the gas saturation calculated by formulas(e.g.Archie)using electric logging data is often much lower than the experiment-derived value.In this paper,a new method was presented for calculating gas saturation more accurately based on non-electric logging data.Firstly,the causes for the low resistivity of shale gas reservoirs in this area were analyzed.Then,the limitation of traditional methods for calculating gas saturation based on electric logging data was diagnosed,and the feasibility of the neutronedensity porosity overlay method was illustrated.According to the response characteristics of neutron,density and other porosity logging in shale gas reservoirs,a model for calculating gas saturation of shale gas was established by core experimental calibration based on the density logging value,the density porosity and the difference between density porosity and neutron porosity,by means of multiple methods(e.g.the dual-porosity overlay method by optimizing the best overlay coefficient).This new method avoids the effect of low resistivity,and thus can provide normal calculated gas saturation of high-quality shale gas reservoirs.It works well in practical application.This new method provides a technical support for the calculation of shale gas reserves in this area.
基金This research was funded by the National Natural Science Foundation under Grant No.[41974151]by the Jiangsu Province Natural Science Foundation under Grant No.[BK20181360]+1 种基金by the Major Scientific and Technological Innovation Project of Shandong Province of China under Grant No.[2019JZZY010820]by the Shaanxi Province Science and Technology Innovation Guidance Special No.[2020CGHJ-005].
文摘The complex resistivity of coal and related rocks contains abundant physical property information,which can be indirectly used to study the lithology and microstructure of these materials.These aspects are closely related to the fluids inside the considered coal rocks,such as gas,water and coalbed methane.In the present analysis,considering different lithological structures,and using the Cole-Cole model,a forward simulation method is used to study different physical parameters such as the zero-frequency resistivity,the polarizability,the relaxation time,and the frequency correlation coefficient.Moreover,using a least square technique,a complex resistivity“inversion”algorithm is written.The comparison of the initial model parameters and those obtained after inversion is used to verify the stability and accuracy of such approach.The method is finally applied to primary-structure coal considered as the experimental sample for complex resistivity measurements.
基金National Key Research and Development Program of China(No.2021YFC3000103).
文摘To reduce the shielding effect of hardened layers on electrical resistivity tomography,a ratio method based on the distortion correction principle and the isolation coefficient is proposed.The effects of the resistivity and thickness of hardened concrete layers on the detection of target objects are explored.Both numerical simulations and indoor tank tests indicate that when the ratio method is employed to correct the original collected data,the maximum allowable error for the isolation coefficient should not exceed 1%.Notably,when the ratio of hardened layer thickness to electrode spacing does not exceed 1,correction through this method significantly enhances the recognition capability of target objects.However,when the hardened layer thickness is greater than the electrode spacing by a factor of 2 or more,the ratio method cannot achieve satisfactory results.The case study of flood control engineering detection in the Zhangxi section of the Huangpen River in Dongzhi County demonstrates that the detection effect after correction by the ratio method is comparable to that for the adjacent unhardened pavement,and the influence of the hardened layer is obviously weakened,resulting in more reliable results.
