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Fatigue properties and damage constitutive model of salt rock based on CT scanning
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作者 Junbao Wang Xiao Liu +3 位作者 Qiang Zhang Xinrong Liu Zhanping Song Shijin Feng 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第2期245-259,共15页
To investigate the macroscopic fatigue properties and the mesoscopic pore evolution characteristics of salt rock under cyclic loading,fatigue tests under different upper-limit stresses were carried out on salt rock,an... To investigate the macroscopic fatigue properties and the mesoscopic pore evolution characteristics of salt rock under cyclic loading,fatigue tests under different upper-limit stresses were carried out on salt rock,and the mesoscopic pore structures of salt rock before and after fatigue tests and under different cycle numbers were measured using CT scanning instrument.Based on the test results,the effects of the cycle number and the upper-limit stress on the evolution of cracks,pore morphology,pore number,pore volume,pore size,plane porosity,and volume porosity of salt rock were analyzed.The failure path of salt rock specimens under cyclic loading was analyzed using the distribution law of plane porosity.The damage variable of salt rock under cyclic loading was defined on basis of the variation of volume porosity with cycle number.In order to describe the fatigue deformation behavior of salt rock under cyclic loading,the nonlinear Burgers damage constitutive model was further established.The results show that the model established can better reflect the whole development process of fatigue deformation of salt rock under cyclic loading. 展开更多
关键词 Salt rock Cyclic loading ct scanning Mesoscopic pore evolution Constitutive model
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Three-dimensional finite element simulation and reconstruction of jointed rock models using CT scanning and photogrammetry
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作者 Yingxian Lang Zhengzhao Liang Zhuo Dong 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第4期1348-1361,共14页
The geometry of joints has a significant influence on the mechanical properties of rocks.To simplify the curved joint shapes in rocks,the joint shape is usually treated as straight lines or planes in most laboratory e... The geometry of joints has a significant influence on the mechanical properties of rocks.To simplify the curved joint shapes in rocks,the joint shape is usually treated as straight lines or planes in most laboratory experiments and numerical simulations.In this study,the computerized tomography (CT) scanning and photogrammetry were employed to obtain the internal and surface joint structures of a limestone sample,respectively.To describe the joint geometry,the edge detection algorithms and a three-dimensional (3D) matrix mapping method were applied to reconstruct CT-based and photogrammetry-based jointed rock models.For comparison tests,the numerical uniaxial compression tests were conducted on an intact rock sample and a sample with a joint simplified to a plane using the parallel computing method.The results indicate that the mechanical characteristics and failure process of jointed rocks are significantly affected by the geometry of joints.The presence of joints reduces the uniaxial compressive strength (UCS),elastic modulus,and released acoustic emission (AE) energy of rocks by 37%–67%,21%–24%,and 52%–90%,respectively.Compared to the simplified joint sample,the proposed photogrammetry-based numerical model makes the most of the limited geometry information of joints.The UCS,accumulative released AE energy,and elastic modulus of the photogrammetry-based sample were found to be very close to those of the CT-based sample.The UCS value of the simplified joint sample (i.e.38.5 MPa) is much lower than that of the CT-based sample (i.e.72.3 MPa).Additionally,the accumulative released AE energy observed in the simplified joint sample is 3.899 times lower than that observed in the CT-based sample.CT scanning provides a reliable means to visualize the joints in rocks,which can be used to verify the reliability of photogrammetry techniques.The application of the photogrammetry-based sample enables detailed analysis for estimating the mechanical properties of jointed rocks. 展开更多
关键词 X-ray computerized tomography(ct)scanning PHOTOGRAMMETRY Parallel computing Numerical simulation Uniaxial compression test Digital image processing
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Experiment of dynamic seepage of tight/shale oil under matrix fracture coupling
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作者 DU Meng YANG Zhengming +10 位作者 LYU Weifeng LI Zhongcheng WANG Guofeng CHEN Xinliang QI Xiang YAO Lanlan ZHANG Yuhao JIA Ninghong LI Haibo CHANG Yilin HUO Xu 《Petroleum Exploration and Development》 SCIE 2024年第2期403-415,共13页
A physical simulation method with a combination of dynamic displacement and imbibition was established by integrating nuclear magnetic resonance(NMR)and CT scanning.The microscopic production mechanism of tight/shale ... A physical simulation method with a combination of dynamic displacement and imbibition was established by integrating nuclear magnetic resonance(NMR)and CT scanning.The microscopic production mechanism of tight/shale oil in pore throat by dynamic imbibition and the influencing factors on the development effect of dynamic imbibition were analyzed.The dynamic seepage process of fracking-soaking-backflow-production integration was simulated,which reveals the dynamic production characteristics at different development stages and their contribution to enhancing oil recovery(EOR).The seepage of tight/shale reservoirs can be divided into three stages:strong displacement and weak imbibition as oil produced rapidly by displacement from macropores and fractures,weak displacement and strong imbibition as oil produced slowly by reverse imbibition from small pores,and weak displacement and weak imbibition at dynamic equilibrium.The greater displacement pressure results in the higher displacement recovery and the lower imbibition recovery.However,if the displacement pressure is too high,the injected water is easy to break through the front and reduce the recovery degree.The higher the permeability,the greater the imbibition and displacement recovery,the shorter the time of imbibition balance,and the higher the final recovery.The fractures can effectively increase the imbibition contact area between matrix and water,reduce the oil-water seepage resistance,promote the oil-water displacement between matrix and fracture,and improve the oil displacement rate and recovery of the matrix.The soaking after fracturing is beneficial to the imbibition replacement and energy storage of the fluid;also,the effective use of the carrying of the backflow fluid and the displacement in the mining stage is the key to enhancing oil recovery. 展开更多
关键词 tight oil shale oil physical simulation nuclear magnetic resonance ct scanning dynamic imbibition production performance EOR
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Quantitative investigation of multi-fracture morphology during TPDF through true tri-axial fracturing experiments and CT scanning 被引量:6
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作者 Ming-Hui Li Fu-Jian Zhou +3 位作者 Jin-Jun Liu Li-Shan Yuan Guo-Peng Huang Bo Wang 《Petroleum Science》 SCIE CAS CSCD 2022年第4期1700-1717,共18页
Due to the reservoir heterogeneity and the stress shadow effect, multiple hydraulic fractures within one fracturing segment cannot be initiated simultaneously and propagate evenly, which will cause a low effectiveness... Due to the reservoir heterogeneity and the stress shadow effect, multiple hydraulic fractures within one fracturing segment cannot be initiated simultaneously and propagate evenly, which will cause a low effectiveness of reservoir stimulation. Temporary plugging and diverting fracturing(TPDF) is considered to be a potential uniform-stimulation method for creating multiple fractures simultaneously in the oilfield. However, the multi-fracture propagation morphology during TPDF is not clear now. The purpose of this study is to quantitatively investigate the multi-fracture propagation morphology during TPDF through true tri-axial fracturing experiments and CT scanning. Critical parameters such as fracture spacing, number of perforation clusters, the viscosity of fracturing fluid, and the in-situ stress have been investigated. The fracture geometry before and after diversion have been quantitively analyzed based on the two-dimensional CT slices and three-dimensional reconstruction method. The main conclusions are as follows:(1) When injecting the high viscosity fluid or perforating at the location with low in-situ stress, multiple hydraulic fractures would simultaneously propagate. Otherwise, only one hydraulic fracture was created during the initial fracturing stage(IFS) for most tests.(2) The perforation cluster effectiveness(PCE) has increased from 26.62% during the IFS to 88.86% after using diverters.(3) The diverted fracture volume has no apparent correlation with the pressure peak and peak frequency during the diversion fracturing stage(DFS) but is positively correlated with water-work.(4) Four types of plugging behavior in shale could be controlled by adjusting the diverter recipe and diverter injection time, and the plugging behavior includes plugging the natural fracture in the wellbore, plugging the previous hydraulic fractures, plugging the fracture tip and plugging the bedding. 展开更多
关键词 Hydraulic fracturing Temporary plugging and diverting fracturing(TPDF) Multiple fracture Tri-axial experiment ct scanning
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Cryostructures and ground ice content in ice-rich permafrost area of the Qinghai-Tibet Plateau with Computed Tomography Scanning 被引量:1
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作者 FAN Xing-wen LIN Zhan-ju +6 位作者 GAO Ze-yong MENG Xiang-lian NIU Fu-jun LUO Jing YIN Guo-an ZHOU Fu-jun LAN Ai-yu 《Journal of Mountain Science》 SCIE CSCD 2021年第5期1208-1221,共14页
Permafrost is an important part of the cryosphere,playing an integral role in the hydrologic cycle,ecology,and influencing human activity.Melting of ground ice can drastically change landscapes and associated thaw sub... Permafrost is an important part of the cryosphere,playing an integral role in the hydrologic cycle,ecology,and influencing human activity.Melting of ground ice can drastically change landscapes and associated thaw subsidence may induce instability of infrastructure.The terrain conditions on the Qinghai-Tibet Plateau are complex,and the spatial distribution of ground ice is highly variable,so knowledge of its abundance and variability is required for impact assessments relating to the degradation of permafrost.This study examined 55 permafrost samples from warm,ice-rich permafrost region in Beiluhe Basin,Qinghai-Tibet Plateau.The samples were examined using Computed Tomography scanning,and the ice content and cryostructure were determined.The results indicated that:1)variation in volumetric ice content was considerable(0%-70%),with a mean value of 17%;2)seven cryostructures were identified,including crustal,vein,lenticular,ataxitic,reticulate and layered cryostructure;3)volumetric ice content varied by cryostructure,with the highest associated with layered and ataxitic cryostructures.Volumetric ice contents were lowest for samples with pore and lenticular cryostructures.This work provides detailed ground ice content and will be helpful for assessing thaw subsidence and infrastructure stability on Qinghai-Tibet Plateau. 展开更多
关键词 Qinghai-Tibet Plateau PERMAFROST ct scanning Volumetric ice content Cryostructure
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An online physical simulation method for enhanced oil recovery by air injection in shale oil 被引量:1
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作者 DU Meng LYU Weifeng +9 位作者 YANG Zhengming JIA Ninghong ZHANG Jigang NIU Zhongkun LI Wen CHEN Xinliang YAO Lanlan CHANG Yilin JIANG Sirui HUANG Qianhui 《Petroleum Exploration and Development》 SCIE 2023年第4期909-923,共15页
In order to understand the mechanism of air flooding shale oil, an online physical simulation method for enhanced shale oil recovery by air injection was established by integrating CT scanning and nuclear magnetic res... In order to understand the mechanism of air flooding shale oil, an online physical simulation method for enhanced shale oil recovery by air injection was established by integrating CT scanning and nuclear magnetic resonance(NMR). The development effect of shale oil by air flooding under different depletion pressures, the micro-production characteristics of pore throats with different sizes and the mechanism of shale oil recovery by air flooding were analyzed. The effects of air oxygen content, permeability, gas injection pressure, and fractures on the air flooding effect in shale and crude oil production in pores with different sizes were analyzed. The recovery of shale oil can be greatly improved by injecting air into the depleted shale reservoir, but the oil displacement efficiency and the production degree of different levels of pore throats vary with the injection timing. The higher the air oxygen content and the stronger the low-temperature oxidation, the higher the production degree of pores with different sizes and the higher the shale oil recovery. The higher the permeability and the better the pore throat connectivity, the stronger the fluid flow capacity and the higher the shale oil recovery. As the injection pressure increases, the lower limit of the production degree of pore throats decreases, but gas channeling may occur to cause a premature breakthrough;as a result, the recovery increases and then decreases. Fractures can effectively increase the contact area between gas and crude oil, and increase the air sweep coefficient and matrix oil drainage area by supplying oil to fractures through the matrix, which means that a proper fracturing before air injection can help to improve the oil displacement effect under a reasonable production pressure difference. 展开更多
关键词 shale oil air flooding ct scanning nuclear magnetic resonance EOR physics simulation
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Correlation between CT dynamic enhanced scanning parameters and serum tumor markers before and after radiofrequency ablation in patients with lung cancer
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作者 Yi Wang Xu Liang Rui-Yu Zhan 《Journal of Hainan Medical University》 2020年第22期19-23,共5页
Objective:To study the correlation between CT dynamic enhanced scanning parameters and serum tumor markers before and after radiofrequency ablation in patients with lung cancer.Methods:60 patients with advanced non-sm... Objective:To study the correlation between CT dynamic enhanced scanning parameters and serum tumor markers before and after radiofrequency ablation in patients with lung cancer.Methods:60 patients with advanced non-small cell lung cancer who were treated in this hospital between January 2015 and January 2017 were divided into control group(n=30)and observation group(n=30)by random number table method.Control group received conventional intravenous chemotherapy,and observation group received intravenous chemotherapy combined with radiofrequency ablation.The differences in CT dynamic enhanced scanning parameter levels and serum tumor marker contents were compared between the two groups of patients before and after treatment.Pearson test was used to evaluate the correlation between CT dynamic enhanced scanning parameters and serum tumor marker contents in patients with advanced non-small cell lung cancer.Results:Before treatment,the differences in CT dynamic enhanced scanning parameter levels,non-organ-specific tumor marker contents and vascular tumor marker contents were not statistically significant between the two groups of patients(P>0.05).After treatment,CT dynamic enhanced scanning parameters PH and perfusion value levels of observation group were lower than those of control group(P<0.05);serum non-organ specific tumor markers CA125,CA153,CEA and CYFRA21-1 contents of observation group were lower than those of control group;serum vascular tumor markers VEGF,Ang-2,HIF-1 and MMP-9 contents were lower than those of control group(P<0.05).Pearson test showed that CT dynamic enhanced scanning parameters PH and perfusion value levels in patients with non-small cell lung cancer were positively correlated with serum non-organ specific tumor marker and vascular tumor marker contents.Conclusion:Adjuvant radiofrequency ablation can significantly reduce the tumor malignancy of patients with advanced non-small cell lung cancer. 展开更多
关键词 Lung cancer Radiofrequency ablation ct dynamic enhanced scanning Tumor marker
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Classification of Brain Tumors Using Hybrid Feature Extraction Based on Modified Deep Learning Techniques
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作者 Tawfeeq Shawly Ahmed Alsheikhy 《Computers, Materials & Continua》 SCIE EI 2023年第10期425-443,共19页
According to the World Health Organization(WHO),Brain Tumors(BrT)have a high rate of mortality across the world.The mortality rate,however,decreases with early diagnosis.Brain images,Computed Tomography(CT)scans,Magne... According to the World Health Organization(WHO),Brain Tumors(BrT)have a high rate of mortality across the world.The mortality rate,however,decreases with early diagnosis.Brain images,Computed Tomography(CT)scans,Magnetic Resonance Imaging scans(MRIs),segmentation,analysis,and evaluation make up the critical tools and steps used to diagnose brain cancer in its early stages.For physicians,diagnosis can be challenging and time-consuming,especially for those with little expertise.As technology advances,Artificial Intelligence(AI)has been used in various domains as a diagnostic tool and offers promising outcomes.Deep-learning techniques are especially useful and have achieved exquisite results.This study proposes a new Computer-Aided Diagnosis(CAD)system to recognize and distinguish between tumors and non-tumor tissues using a newly developed middleware to integrate two deep-learning technologies to segment brain MRI scans and classify any discovered tumors.The segmentation mechanism is used to determine the shape,area,diameter,and outline of any tumors,while the classification mechanism categorizes the type of cancer as slow-growing or aggressive.The main goal is to diagnose tumors early and to support the work of physicians.The proposed system integrates a Convolutional Neural Network(CNN),VGG-19,and Long Short-Term Memory Networks(LSTMs).A middleware framework is developed to perform the integration process and allow the system to collect the required data for the classification of tumors.Numerous experiments have been conducted on different five datasets to evaluate the presented system.These experiments reveal that the system achieves 97.98%average accuracy when the segmentation and classification functions were utilized,demonstrating that the proposed system is a powerful and valuable method to diagnose BrT early using MRI images.In addition,the system can be deployed in medical facilities to support and assist physicians to provide an early diagnosis to save patients’lives and avoid the high cost of treatments. 展开更多
关键词 Brain cancer TUMORS early diagnosis CNN VGG-19 LSTMs ct scans MRI MIDDLEWARE
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Effect of seepage-induced erosion on soil macropore structure
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作者 HUANG Wen-bo HUANG Da +3 位作者 GAO Yi-kang LIU Yang LI Zhao MENG Qiu-jie 《Journal of Mountain Science》 SCIE CSCD 2023年第11期3402-3422,共21页
Internal erosion is one of the important factors causing geological disasters.The microstructure of soil can change with seepage erosion,resulting in changes in the hydraulic and mechanical properties of the soil.The ... Internal erosion is one of the important factors causing geological disasters.The microstructure of soil can change with seepage erosion,resulting in changes in the hydraulic and mechanical properties of the soil.The evolution of seepage erosion is investigated with X-ray computed tomography(CT)in this study.The change in macropore structure characteristics during the seepage erosion test is quantified and the influence of seepage erosion on soil deformation is analyzed.Moreover,a pore network model(PNM)is established for the specimens and the evolution of the connected pore size characteristics is assessed.The results show that the macropore structure is significantly affected by seepage erosion,especially in terms of the porosity and pore geometry characteristics.The changes in macropore structure characteristics are most obvious in the lower part of the specimen.The influence of seepage erosion on the pore size distribution(PSD)and soil deformation is heterogeneous and closely dependent on the spatial location of the soil.Moreover,seepage erosion enhances macropore connectivity and has a directional impact on macropore orientation.These findings can provide a reference for the theoretical modeling and numerical simulation of the seepage erosion and improve the understanding of the seepage erosion evolution in engineering practice. 展开更多
关键词 Seepage erosion HETEROGENEITY Macropore structure Pore size distribution MICROSTRUctURE ct scanning
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Liver Tumor Prediction with Advanced Attention Mechanisms Integrated into a Depth-Based Variant Search Algorithm
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作者 P.Kalaiselvi S.Anusuya 《Computers, Materials & Continua》 SCIE EI 2023年第10期1209-1226,共18页
In recent days,Deep Learning(DL)techniques have become an emerging transformation in the field of machine learning,artificial intelligence,computer vision,and so on.Subsequently,researchers and industries have been hi... In recent days,Deep Learning(DL)techniques have become an emerging transformation in the field of machine learning,artificial intelligence,computer vision,and so on.Subsequently,researchers and industries have been highly endorsed in the medical field,predicting and controlling diverse diseases at specific intervals.Liver tumor prediction is a vital chore in analyzing and treating liver diseases.This paper proposes a novel approach for predicting liver tumors using Convolutional Neural Networks(CNN)and a depth-based variant search algorithm with advanced attention mechanisms(CNN-DS-AM).The proposed work aims to improve accuracy and robustness in diagnosing and treating liver diseases.The anticipated model is assessed on a Computed Tomography(CT)scan dataset containing both benign and malignant liver tumors.The proposed approach achieved high accuracy in predicting liver tumors,outperforming other state-of-the-art methods.Additionally,advanced attention mechanisms were incorporated into the CNN model to enable the identification and highlighting of regions of the CT scans most relevant to predicting liver tumors.The results suggest that incorporating attention mechanisms and a depth-based variant search algorithm into the CNN model is a promising approach for improving the accuracy and robustness of liver tumor prediction.It can assist radiologists in their diagnosis and treatment planning.The proposed system achieved a high accuracy of 95.5%in predicting liver tumors,outperforming other state-of-the-art methods. 展开更多
关键词 Deep learning convolution neural networks liver tumors ct scans attention mechanism CLASSIFIER
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Analysis of the Microstructure of a Failed Cement Sheath Subjected to Complex Temperature and Pressure Conditions
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作者 Zhiqiang Wu Yi Wu +3 位作者 Renjun Xie Jin Yang Shujie Liu Qiao Deng 《Fluid Dynamics & Materials Processing》 EI 2023年第2期399-406,共8页
One of the main obstacles hindering the exploitation of high-temperature and high-pressure oil and gas is the sealing integrity of the cement sheath.Analyzing the microstructure of the cement sheath is therefore an im... One of the main obstacles hindering the exploitation of high-temperature and high-pressure oil and gas is the sealing integrity of the cement sheath.Analyzing the microstructure of the cement sheath is therefore an important task.In this study,the microstructure of the cement sheath is determined using a CT scanner under different temperature and pressure conditions.The results suggest that the major cause of micro-cracks in the cement is the increase in the casing pressure.When the micro-cracks accumulate to a certain extent,the overall structure of the cement sheath is weakened,resulting in gas channeling,which poses a direct threat to the safe production of oil and gas.A change in the casing temperature has a limited effect on the microstructure of the cement sheath. 展开更多
关键词 Cement sheath MICROSTRUctURE experimental study mesh model ct scan
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Optimum Threshold Estimation of Thorax CT Scan for COVID-19 Diagnosis in a Single Center in Cameroon
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作者 Anne Esther Njom Nlend Landry Bonyomo +6 位作者 Serges Abogo Serges Nga Nomo Luc Meka Moise Nna Beatrice Meva’a Arsene Brunelle Sandie Christiane Nsahlai 《Advances in Infectious Diseases》 CAS 2023年第1期12-20,共9页
Objective: To evaluate the lung CT scan as a possible predictive diagnostic method for COVID-19 in the Cameroonian context. Methods: We designed a cross sectional study. Suspected cases of COVID-19 during the first wa... Objective: To evaluate the lung CT scan as a possible predictive diagnostic method for COVID-19 in the Cameroonian context. Methods: We designed a cross sectional study. Suspected cases of COVID-19 during the first wave at the national social insurance fund (NSIF) hospital were screened with both COVID-19 with lung CT scan and a PCR test. Univariate analysis was performed for sample description and multivariate analysis to assess the correlation between positive results for the PCR and other parameters. We estimated the optimum threshold of sensitivity/specificity, and area under curve using the empirical method and package. Results: A total of 62 suspected COVID-19 cases were recorded, predominantly males (Sex Ratio = 2.2) with a median age of 58.5 (IQR = 19.7). Among our 62 patients, 29 (46.8%) were confirmed COVID-19 cases with positive PCR results. All the patients had a thorax CT scan with a median impairment of 40% (IQR = 20%). The optimum threshold estimate for CT scan for COVID-19 infection diagnosis was 60% (95% CI = 25% - 80%). Overall, the sensitivity and specificity estimates were 0.30 (95% CI = 0.15 - 0.49) and 0.87 (95% CI = 0.70 - 0.96), respectively, leading to an Area Under Curve (AUC) estimate of 0.59 (95% CI = 0.46, 0.71). Conclusion: In this setting, lung CT scan was neither sensitive nor specific to predict COVID-19 disease. 展开更多
关键词 COVID-19 ct Scan LUNG DIAGNOSIS
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Treatment of Kidney Stones by Percutaneous Nephrolithotomy: Evaluation of the Results of the First Series of Our Experience in the Urology Department of the Idrissa Pouye General Hospital in Dakar
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作者 Mouhamadou Moustapha Mbodji Mohamed Jalloh +4 位作者 Medina Ndoye Abdourahmane Diallo Issa Labou Lamine Niang Serigne Magueye Gueye 《Open Journal of Urology》 2024年第2期104-114,共11页
The principle of PCNL is the extraction through a nephrostomy channel of kidney stones which are defined as the presence of crystalline concretions in the kidneys. Objectives: The objective of this work was to study t... The principle of PCNL is the extraction through a nephrostomy channel of kidney stones which are defined as the presence of crystalline concretions in the kidneys. Objectives: The objective of this work was to study the epidemiological, clinical and paraclinical aspects of patients with renal lithiasis treated by PCNL and on the other hand the different technical aspects of PCNL. Materials and Methods: This was a retrospective descriptive study, conducted in the urology department of HOGIP, covering the period from January 2015 to January 2019. We studied the demographic and clinical aspects of patients presenting renal lithiasis;we also studied the technical aspects and treatment outcomes. Statistical significance was set for α = 0.05. Results: Our series covered 82 PCNLs performed during the study period. The average age was 45.95 years, the age group [40 - 49 years] was more affected. Our study involved 44 men and 38 women, a sex ratio of 1.15. At the clinic, atypical lumbar pain was more frequent in 45.83% of cases. On URO-CT, the calculations were located more at the pyelic level (31.2%) and lower caliceal (27.2%). The size of stones measured between 15 and 20 mm in 30.52%. The stone density was between 500 and 1000 HU in 47.54% of cases. Intraoperatively, the patients were placed in lateral decubitus in 41.46% of cases. Only one access to the kidney was necessary in 87.8% of cases. The lithoclast was used in 65.85% of cases. The overall success rate (stone free) in our series was 96%. The majority of cases, 41.44%, drainage were done by natural means (totally tubeless). The average duration was 92 minutes. The complications encountered in our experience concerned 10 cases, a rate of 12.19%. Conclusion: Urinary lithiasis is more and more frequent in our regions. The development of Endo-urology offers several therapeutic options. Thus, PCNL occupies an important place in the management of kidney stones. 展开更多
关键词 HOGIP Kidney Stones PCNL Stone Free Uro ct Scan
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Pore structure characterization and seepage analysis of ionic rare earth orebodies based on computed tomography images 被引量:7
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作者 Xianping Luo Yongbing Zhang +4 位作者 Hepeng Zhou Kunzhong He Boyuan Zhang Dongming Zhang Weijing Xiao 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2022年第2期411-421,共11页
Pore network structure of ore body is a diffusion channel of leaching agent solution that exerts a significant influence on seepage.The ore body structure,pore distribution,pore and throat size,and pore network charac... Pore network structure of ore body is a diffusion channel of leaching agent solution that exerts a significant influence on seepage.The ore body structure,pore distribution,pore and throat size,and pore network characteristics of topsoil,weathered,and semiweathered layers of ionic rare earth ore in southern Jiangxi Province were explored in this study.The effect of leaching operation on the pore structure was investigated,and main factors affecting the seepage were analyzed.Results showed that the semiweathered layer presents a dense structure and a small number of unconnected pores.Pores of topsoil and weathered layers are mainly long and narrow column openings with some planar fractures.Even pore distribution and large size span were observed.Compared with the weathered layer,the topsoil layer demonstrates larger voids,smaller average pore volume and equivalent radius,and fewer coordination throats;however,the average equivalent radius of the throat in the topsoil layer is larger and largescale channels exist through ore body vertically.Hence,permeability of the topsoil layer is significantly higher than that of the weathered layer.Colloidal clay minerals migrate easily and the occurrence of silting in the small porosity blocks the throat and significantly decreases the permeability of the ore body in the leaching process.The equivalent radius of the throat is the key to the seepage.Reducing the migration of fine particles is an effective measure to protect the throat and shorten the leaching period. 展开更多
关键词 Ionic rare earth ore ct scanning 3D visualization Pore characteristics PERMEABILITY
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Effect of fatigue loading-confining stress unloading rate on marble mechanical behaviors: An insight into fracture evolution analyses 被引量:6
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作者 Yu Wang Dongqiao Liu +2 位作者 Jianqiang Han Changhong Li Hao Liu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2020年第6期1249-1262,共14页
Rocks in underground works usually experience rather complex stress disturbance.For this,their fracture mechanism is significantly different from rocks subjected to conventional triaxial compression conditions.The eff... Rocks in underground works usually experience rather complex stress disturbance.For this,their fracture mechanism is significantly different from rocks subjected to conventional triaxial compression conditions.The effects of stress disturbances on rock geomechanical behaviors under fatigue loading conditions and triaxial unloading conditions have been reported in previous studies.However,little is known about the dependence of the unloading rate on fatigue loading and confining stress unloading(FL-CSU)conditions that influence rock failure.In this paper,we aimed at investigating the fracture behaviors of marble under FL-CSU conditions using the post-test X-ray computed tomography(CT)scanning technique and the GCTS RTR 2000 rock mechanics system.Results show that damage accumulation at the fatigue stage can influence the final fracture behaviors of marble.The stored elastic energy for rock samples under FL-CSU tests is relatively larger compared to those under conventional triaxial tests,and the dissipated energy used to drive damage evolution and crack propagation is larger for FL-CSU tests.In FL-CSU tests,as the unloading rate increases,the dissipated energy grows and elastic energy reduces.CT scanning after the test reveals the impacts of the unloading rate on the crack pattern and a fracture degree index is therein defined in this context to represent the crack dimension.It shows that the crack pattern after FL-CSU tests depends on the unloading rate,and the fracture degree is in agreement with the analysis of both the energy dissipation and the amount of energy released.The effect of unloading rate on fracture evolution characteristics of marble is revealed by a series of FL-CSU tests. 展开更多
关键词 Fatigue loading Confining stress unloading Unloading rate Energy evolution Computed tomography(ct)scanning
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Image reconstruction based on total-variation minimization and alternating direction method in linear scan computed tomography 被引量:6
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作者 张瀚铭 王林元 +3 位作者 闫镔 李磊 席晓琦 陆利忠 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第7期582-589,共8页
Linear scan computed tomography (LCT) is of great benefit to online industrial scanning and security inspection due to its characteristics of straight-line source trajectory and high scanning speed. However, in prac... Linear scan computed tomography (LCT) is of great benefit to online industrial scanning and security inspection due to its characteristics of straight-line source trajectory and high scanning speed. However, in practical applications of LCT, there are challenges to image reconstruction due to limited-angle and insufficient data. In this paper, a new reconstruction algorithm based on total-variation (TV) minimization is developed to reconstruct images from limited-angle and insufficient data in LCT. The main idea of our approach is to reformulate a TV problem as a linear equality constrained problem where the objective function is separable, and then minimize its augmented Lagrangian function by using alternating direction method (ADM) to solve subproblems. The proposed method is robust and efficient in the task of reconstruction by showing the convergence of ADM. The numerical simulations and real data reconstructions show that the proposed reconstruction method brings reasonable performance and outperforms some previous ones when applied to an LCT imaging problem. 展开更多
关键词 linear scan ct image reconstruction total variation alternating direction method
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Creep Damage Characteristics of Soft Rock under Disturbance Loads 被引量:3
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作者 付志亮 郭华 高延法 《Journal of China University of Geosciences》 SCIE CSCD 2008年第3期292-297,共6页
This article focuses on the process of rock creep damage and micro-damage evolution properties of gray green mudstone under impacting disturbance load conditions for the first time using the real time computerized tom... This article focuses on the process of rock creep damage and micro-damage evolution properties of gray green mudstone under impacting disturbance load conditions for the first time using the real time computerized tomography (CT) testing technique. The results indicate that axial load comes into limit strength neighborhood, rock micro-crack links into larger crack, creep rate increases in a short time, larger plastic deformation happens; this is called disturbance accelerating creep stage. When rock is within limit strength neighborhood, there occurs creep micro-damage under smaller disturbance load. When disturbance load is larger, rock directly enters into disturbance accelerating creep stage, failure occurs instantaneously. On the basis of experimental research, the CT scanning method was used to describe the creep micro-damage of soft rock, also helpful in the prediction of roadways' service life and evaluation of geotechnical engineering stability. 展开更多
关键词 ct scanning micro-damage impacting disturbance MICRO-CRACK creep.
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An experimental study on microscopic characteristics of gas-bearing sediments under different gas reservoir pressures 被引量:2
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作者 Zhenqi Guo Tao Liu +3 位作者 Lei Guo Xiuting Su Yan Zhang Sanpeng Li 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2021年第10期144-151,共8页
Gas-bearing sediments are widely distributed in five continents all over the world.Most of the gases exist in the soil skeleton in the form of discrete large bubbles.The existence of gas-phase may increase or decrease... Gas-bearing sediments are widely distributed in five continents all over the world.Most of the gases exist in the soil skeleton in the form of discrete large bubbles.The existence of gas-phase may increase or decrease the strength of the soil skeleton.So far,bubbles’structural morphology and evolution characteristics in soil skeleton lack research,and the influence of different gas reservoir pressures on bubbles are still unclear.The micro characteristics of bubbles in the same sediment sample were studied using an industrial CT scanning test system to solve these problems.Using the image processing software,the micro variation characteristics of gas-bearing sediments in gas reservoir pressure change are obtained.The results show that the number and volume of bubbles in different equivalent radius ranges will change regularly under different gas reservoir pressure.With the increase of gas reservoir pressure,the number and volume of tiny bubbles decrease.In contrast,the number and volume of large bubbles increase,and the gas content in different positions increases and occupies a dominant position,driving the reduction of pore water and soil skeleton movement. 展开更多
关键词 micro characteristics ct scanning gas content number and volume of bubbles gas reservoir pressure seabed sediments
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Investigating microscopic seepage characteristics and fracture effectiveness of tight sandstones:a digital core approach 被引量:1
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作者 Jing Li Xiao-Rong Li +3 位作者 Ming-Shui Song Hui-Min Liu Yong-Cun Feng Chen Liu 《Petroleum Science》 SCIE CAS CSCD 2021年第1期173-182,共10页
Microscopic seepage characteristics are critical for the evaluation of tight sandstone reservoirs.In this study,a digital core approach integrating microscopic seepage simulation and CT scanning was developed to chara... Microscopic seepage characteristics are critical for the evaluation of tight sandstone reservoirs.In this study,a digital core approach integrating microscopic seepage simulation and CT scanning was developed to characterize microscopic seepage and fracture effectiveness(the ratio of micro-fractures that contributes to fluid flow)of tight sandstones.Numerical simulations were carried out for characterizations of tight sandstones.The results show that the axial permeability of the investigated cylindrical tight sandstone from Junggar Basin in China is 0.460μm~2,while the radial permeability is 0.3723μm~2,and the axial and radial effective fracture ratios are 0.4387 and 0.4806,respectively,indicating that cracks are not fully developed and the connectivity between micro-cracks is poor.Directional permeability that is difficult to measure by laboratory experiments can be obtained readily using the proposed method in this paper.The results provide important information for improving the exploration and development of tight sandstone reservoirs. 展开更多
关键词 Tight sandstone Digital core approach ct scanning Microscopic seepage characteristics Fracture effectiveness
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Optimized Deep Learning-Inspired Model for the Diagnosis and Prediction of COVID-19 被引量:2
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作者 Sally M.Elghamrawy Aboul Ella Hassnien Vaclav Snasel 《Computers, Materials & Continua》 SCIE EI 2021年第5期2353-2371,共19页
Detecting COVID-19 cases as early as possible became a critical issue that must be addressed to avoid the pandemic’s additional spread and early provide the appropriate treatment to the affected patients.This study a... Detecting COVID-19 cases as early as possible became a critical issue that must be addressed to avoid the pandemic’s additional spread and early provide the appropriate treatment to the affected patients.This study aimed to develop a COVID-19 diagnosis and prediction(AIMDP)model that could identify patients with COVID-19 and distinguish it from other viral pneumonia signs detected in chest computed tomography(CT)scans.The proposed system uses convolutional neural networks(CNNs)as a deep learning technology to process hundreds of CT chest scan images and speeds up COVID-19 case prediction to facilitate its containment.We employed the whale optimization algorithm(WOA)to select the most relevant patient signs.A set of experiments validated AIMDP performance.It demonstrated the superiority of AIMDP in terms of the area under the curve-receiver operating characteristic(AUC-ROC)curve,positive predictive value(PPV),negative predictive rate(NPR)and negative predictive value(NPV).AIMDP was applied to a dataset of hundreds of real data and CT images,and it was found to achieve 96%AUC for diagnosing COVID-19 and 98%for overall accuracy.The results showed the promising performance of AIMDP for diagnosing COVID-19 when compared to other recent diagnosing and predicting models. 展开更多
关键词 Convolutional neural networks coronavirus disease 2019(COVID-19) ct chest scan imaging deep learning technique feature selection whale optimization algorithm
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