检索结果-南通市图书馆

Journal of Materials Science & Technology 2021年第6期65卷 99-107页

作者： Cheng Gu Yan Lu Alan A.Luo Department of Materials Science and Engineering The Ohio State University2041 College Rd N.ColumbusOhio 43210USA Department of Integrated Systems Engineering The Ohio State University1971 NeilAve.ColumbusOhio 43210USA

Porosity is a major issue in solidification processing of metallic materials.In this work,wedge die casting experiments were designed to investigate the effect of cooling rate on microporosity in an aluminum alloy A356.Microstructure information including dendrites and porosity were measured and observed by optical microscopy and x-ray micro-computed tomography(xMCT).The effects of cooling rate on secondary dendrite arm spacing(SDAS)and porosity were discussed.The relationship between SDAS and cooling rate was established and validated using a mathematical model.Three-dimensional(3-D)porosity information,including porosity percentage,pore volume,and pore number,was determined by xMCT.With the cooling rate decreasing from a lower to a higher position of the wedge die,the observed pore number decreases,the porosity percentage increases,and the equivalent pore radius increases.Sphericity of the pores was discussed as an empirical criterion to distinguish the types of porosity.For different cooling rates,the larger the equivalent pore radius is,the lower the sphericity of the pores.This research suggests that xMCT is a useful tool to provide critical 3-D porosity information for integrated computational materials engineering(ICME)design and process optimization of solidification products.

关键词： x-ray computed tomography Casting micropore Quantitative evaluation Al alloy

In situ compression and x-ray computed tomography of flow battery electrodes

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2018年第5期27卷 1353-1361页

作者： Rhodri Jervis Matt D.R.Kok Tobias P.Neville Quentin Meyer Leon D.Brown Francesco Iacoviello Jeff T.Gostick Dan J.L.Brett Paul R.Shearing Electrochemical Innovation Lab Department of Chemical Engineering University College London Department of Chemical Engineering McGill University Porous Media Engineering and Analysis Lab Department of Chemical Engineering University of Waterloo

Redox flow batteries offer a potential solution to an increase in renewable energy generation on the grid by offering long-term, large-scale storage and regulation of power. However, they are currently un- derutilised due to cost and performance issues, many of which are linked to the microstructure of the porous carbon electrodes used. Here, for the first time, we offer a detailed study of the in situ effects of compression on a commercially available carbon felt electrode. Visualisation of electrode structure us- ing x-ray computed tomography shows the non-linear way that these materials compress and various metrics are used to elucidate the changes in porosity, pore size distribution and tortuosity factor under compressions from 0%-90%.

关键词： Redox flow battery x-ray computed tomography Compression Carbon felt RFB

Distinct root system acclimation patterns of seagrass Zostera japonica in sediments of different trophic status:a research by x-ray computed tomography

在线全文

学校读者我要写书评

暂无评论

Journal of Oceanology and Limnology 2021年第6期39卷 2267-2280页

作者： xiaoyue SONG Yi ZHOU Jiangning ZENG Lu SHOU xiaomei ZHANG Shidong YUE Wei GAO Weihua FENG Zhifu WANG Ping DU Key Laboratory of Marine Ecosystem Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China CAS Key Laboratory of Marine Ecology and Environmental Sciences Institute of OceanologyChinese Academy of SciencesQingdao 266071China College of Tropical Crops Hainan UniversityHaikou 570228China Key Laboratory of Engineering Oceanography Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China

Conspecific seagrass living in differing environments may develop different root system acclimation patterns.We applied x-ray computed tomography(CT)for imaging and quantifying roots systems of Zostera japonica collected from typical oligotrophic and eutrophic sediments in two coastal sites of northern China,and determined sediment physicochemical properties that might influence root system morphology,density,and distribution.The trophic status of sediments had little influence on the Z.japonica root length,and diameters of root and rhizome.However,Z.japonica in oligotrophic sediment developed the root system with longer rhizome node,deeper rhizome distribution,and larger allocation to below-ground tissues in order to acquire more nutrients and relieve the N deficiency.And the lower root and rhizome densities of Z.japonica in eutrophic sediment were mainly caused by fewer shoots and shorter longevity,which was resulted from the more serious sulfide inhibition.Our results systematically revealed the effect of sediment trophic status on the phenotypic plasticity,quantity,and distribution of Z.japonica root system,and demonstrated the feasibly of x-ray CT in seagrass root system research.

关键词： Zostera japonica root system acclimation pattern sediment trophic status x-ray computed tomography

Microstructure Evolution of Sandstone Cemented by Microbe Cement Using x-ray computed tomography

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2013年第6期28卷 1134-1139页

作者： RONG Hui QIAN Chunxiang School of Materials Science and Engineering Southeast University Jiangsu Key Laboratory of Construction Material Research Institute of Green Construction Materials Southeast University

The bio-sandstone, which was cemented by microbe cement, was firstly prepared, and then the microstructure evolution process was studied by x-ray computed tomography （x-CT） technique. The experimental results indicate that the microstructure of bio-sandstone becomes dense with the development of age. The evolution of inner structure at different positions is different due to the different contents of microbial induced precipitation calcite. Besides, the increase rate of microbial induced precipitation calcite gradually decreases because of the reduction of microbe absorption content with the decreasing pore size in bio-sandstone.

关键词： microbe cement bio-sandstone microstructure evolution x-ray computed tomography calcite

Non-destructive 3D geometric modeling of maize root-stubble in-situ via x-ray computed tomography

在线全文

学校读者我要写书评

暂无评论

International Journal of Agricultural and Biological Engineering 2020年第3期13卷 174-179页

作者： xu Zhao Luyu xing Shifan Shen Jiaming Liu Daixing Zhang School of Mechanical Engineering&Automation University of Science and Technology LiaoningAnshan 114051China

No-tillage seeding has become an important approach to improve crop productivity,which needs colters of high performance to cut the root-stubble-soil composite.However,the difficulty of maize root-stubbles three-dimensional(3D)modeling hinders finite element(FE)simulation to improve development efficiency of such colters because of maize root system complexity and opaque nature of the soil.Fortunately,the non-destructive 3D geometric model of the maize root-stubble in-situ can be established via x-ray computed tomography(CT)following by a systematic procedure.The whole procedure includes CT scanning of the maize root-stubble-soil composite sample,image reconstruction via filtered back-projection(FBP)with the Hanning filter,segmentation of root-stubble via a variational level set method,and post-processing via morphological operations.The 3D reconstruction model of the maize root-stubble in-situ presents a complete,complex and in-situ geometrical morphology,which cannot be realized via other methods,including the destructive modelling after washing via CT.This study is the first to build a 3D geometric model of a maize root-stubble in-situ via CT,which opens up new possibilities for simulation of root-stubble-soil cutting using FEM,and much other research related to plant root-stubbles.

关键词： maize root-stubble non-destructive modeling x-ray computed tomography variational level set method

Material-SAM:Adapting SAM for Material xCT

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2024年第3期78卷 3703-3720页

作者： xuelong Wu Junsheng Wang Zhongyao Li Yisheng Miao Chengpeng xue Yuling Lang Decai Kong xiaoying Ma Haibao Qiao School of Materials Science and Engineering Beijing Institute of TechnologyBeijing100081China Senior Engineer at the Simulation Center Citic Dicastal Co.Ltd.Qinhuangdao066010China

x-ray computed tomography(xCT)enables non-destructive acquisition of the internal structure of materials,and image segmentation plays a crucial role in analyzing material xCT images.This paper proposes an image segmentation method based on the Segment Anything model(SAM).We constructed a dataset of carbide in nickel-based single crystal superalloys xCT images and preprocessed the images using median filtering,histogram equalization,and gamma correction.Subsequently,SAM was fine-tuned to adapt to the task of material xCT image segmentation,resulting in Material-SAM.We compared the performance of threshold segmentation,SAM,U-Net model,and Material-SAM.Our method achieved 88.45%Class Pixel Accuracy(CPA)and 88.77%Dice Similarity Coefficient(DSC)on the test set,outperforming SAM by 5.25%and 8.81%,respectively,and achieving the highest evaluation.Material-SAM demonstrated lower input requirements compared to SAM,as it only required three reference points for completing the segmentation task,which is one-fifth of the requirement of SAM.Material-SAM exhibited promising results,highlighting its potential as a novel method for material xCT image segmentation.

关键词： Segment Anything model x-ray computed tomography U-Net Ni-based superalloys foundation models

A projection-domain iterative algorithm for metal artifact reduction by minimizing the total-variation norm and the negative-pixel energy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Visual Computing for Industry,Biomedicine,and Art 2022年第1期5卷 1-11页

作者： Gengsheng L.Zeng Department of Computer Science Utah Valley UniversityOremUT 84058USA Department of Radiology and Imaging Sciences University of UtahSalt Lake CityUT 84108USA

Metal objects in x-ray computed tomography can cause severe artifacts.The state-of-the-art metal artifact reduction methods are in the sinogram inpainting category and are iterative methods.This paper proposes a projectiondomain algorithm to reduce the metal artifacts.In this algorithm,the unknowns are the metal-affected projections,while the objective function is set up in the image domain.The data fidelity term is not utilized in the objective function.The objective function of the proposed algorithm consists of two terms:the total variation of the metalremoved image and the energy of the negative-valued pixels in the image.After the metal-affected projections are modified,the final image is reconstructed via the filtered backprojection algorithm.The feasibility of the proposed algorithm has been verified by real experimental data.

关键词： Analytical image reconstruction Metal artifact reduction Projection-domain iterative algorithm x-ray computed tomography

Characterization on the formation of porosity and tensile properties prediction in die casting Mg alloys

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2022年第7期10卷 1857-1867页

作者： Zixin Li Dejiang Li Wenke Zhou Bo Hu xingfeng Zhao Jingya Wang Ming Qin Jiangkun xu xiaoqin Zeng National Engineering Research Center of Light Alloy Net Forming School of Materials Science and EngineeringShanghai Jiao Tong University800 Dongchuan RoadShanghai 200240China Hitachi(China)Research&Development Corporation Rui Jin BuildingNo.205 Maoming Road(S)Shanghai 200020China The State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University800 Dongchuan RoadShanghai 200240China

The 3D visualization of the porosity in high-pressure die casting(HPDC)Mg alloys AZ91D and Mg4Ce2Al0.5Mn(EA42)was investigated by x-ray computed tomography.It was demonstrated that the volumetric porosity at the near-gate location for alloy EA42 was significantly higher than that far from the gate location.This difference resulted from the low valid time during intensified casting pressure conditions.Specimens of alloy EA42 exhibited a narrow pore distribution in the side view(~0.5 mm)compared to the wide distribution(~1.8 mm)of alloy AZ91D,which was mainly attributed to the formation mechanism of the defect band.The formation of microporosity in the defect band of alloy EA42 was inhibited because of the significant latent heat released by a large amount of the Al11Ce3phase segregated in the defect band during solidification.Additionally,an effective estimator(Z-Propagation)was introduced,which is proposed to predict the projected area fraction of the porosity(f)involved during tensile failure with better effectiveness compared with traditional methods based on the actual fractured surface.By coupling the Z-Propagation method with the critical local strain model,the logarithmic fracture strain and true fracture stress of the specimens were predicted within 3.03%and 1.65%of the absolute value of the average relative error(AARE),respectively.

关键词： High-pressure die casting Porosity Tensile property Magnesium alloy x-ray computed tomography

3D anisotropy in shear failure of a typical shale

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2023年第1期20卷 212-229页

作者： Zi-Dong Fan Li Ren He-Ping xie Ru Zhang Cun-Bao Li Hui-Jun Lu An-Lin Zhang Qin Zhou Wei-Qiang Ling MOE Key Laboratory of Deep Earth Science and Engineering Sichuan UniversityChengduSichuan 610065China College of Architecture and Environment Sichuan UniversityChengduSichuan 610065China Institute of Deep Earth Sciences and Green Energy Shenzhen UniversityShenzhenGuangdong 518052China College of Water Resources and Hydropower Sichuan UniversityChengduSichuan 610065China

It is inadequate to study the shear failure anisotropy of shale in only 2D space.Aiming at a 3D analysis,a series of direct shear tests was conducted on Longmaxi shale with three typical bedding orientations:arrester,divider and short-transverse orientations.During testing,acoustic emission(AE)and digital image correlation(DIC)techniques were simultaneously employed to monitor failure development,after testing,x-ray computed tomography(CT)scanning was adopted to acquire and reconstruct the fractures inside typical ruptured samples for more detailed analysis.The results indicated that the shear strength parameters exhibited 3D anisotropies and those of the arrester sample did not have equivalent shear strength parameters to the shale matrix.The maximum(minimum)shear strength and cohesion were obtained with the divider(short-transverse)orientation,and the internal friction angle reached its maximum(minimum)with the divider(arrester)orientation.Combining the AE,DIC and CT techniques,four characteristic stress levels that can capture the progressive shear failure process of shale rocks were identified,and the onset and accelerated development of shear damage-induced dilation were observed at the crack initiation and coalesce stress thresholds,respectively.During the crack coalescence stage,the dominated microcracking mechanism transferred from tensile-mode to shear-mode.For the arrester and divider orientations,more tensile-mode AE events were generated due to the microcracking along the vertical beddings.Compared with the divider samples,a more complex fracture network with a larger fracture area and volume was obtained in the arrester samples,whose strengths were smaller.

关键词： Shale Shear Acoustic emission Digital image correlation x-ray computed tomography Fracture network

Malignant giant cell tumors of the tendon sheath of the right hip:A case report

在线全文

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2022年第29期10卷 10763-10771页

作者： Wen-Peng Huang Ge Gao Qi Yang Zhao Chen Yong-Kang Qiu Jian-Bo Gao Lei Kang Department of Nuclear Medicine Peking University First HospitalBeijing 100034China Department of Medical Imaging Peking University First HospitalBeijing 100034China Department of Radiology The First Affiliated Hospital of Zhengzhou UniversityZhengzhou 450052Henan ProvinceChina

BACKGROUND Malignant giant cell tumor of the tendon sheath(MGCTTS)is an extremely rare malignant tumor originating from synovial and tendon sheath tissue with highly aggressive biological behavior and a high rate of local recurrence and distant metastasis which should be considered a highly malignant sarcoma and managed aggressively.How to systemically treat MGCTTS remains a challenge.In this case,a patient with MGCTTS suffered a recurrence after 2 surgical resections received adjuvant chemotherapy and radiation therapy,but the treatment outcome remained poor.More clinical trials and better understanding of the biology and molecular aspects of this subtype of sarcoma are needed while novel medicines should be developed to efficiently target particular pathways.CASE SUMMARY A 52-year-old man presented with persistent dull pain in the right groin accompanied by limited right hip motion starting 6 mo ago.Two months before his attending to hospital,the patient’s pain worsened,presenting as severe pain when standing or walking,limping,and inability to straighten or move the right lower extremity.Surgical excision was performed and MGCTTS was confirmed by pathology examination.Two recurrences occurred after surgical resection,moreover,the treatment outcome remained poor after adjuvant chemotherapy and radiation therapy.The patient died only 10 mo after the initial diagnosis.CONCLUSION MGCTTS is characterized by a joint mass with pain and limited motion.It typically grows along the tendons and infiltrated into the surrounding muscle and bone tissue,with a stubborn tendency to relapse,as well as pulmonary metastasis.Radically surgical resection provides a choice of treatment whereas post-operation care should be taken to preserve the function of the joint.Chemotherapy and radiotherapy can be used as alternative treatments when radical resection cannot be performed.

关键词： Malignant Tenosynovial giant cell tumor Recurrence Magnetic resonance imaging Bone scintigraphy Treatment x-ray computed tomography Case report