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Analyzing the characterization of pore structures and permeability of diesel contaminated clays under different aging conditions

《结构与土木工程前沿（英文）》   页码 1264-1280 doi: 10.1007/s11709-023-0921-x

摘要： In this study, mercury intrusion porosimetry (MIP) and X-ray micro-computed tomography (XRμCT) were used to characterize the pore structures and investigate the permeability characteristics of clay after aging and contamination with diesel. The results of the MIP tests showed that aging leads to reductions in porosity and average diameter, as well as an increase in tortuosity. The XRμCT analysis yielded consistent results; it showed that aging renders pores more spherical and isotropic and pore surfaces smoother. This weakens the pore connectivity. Micromorphological analysis revealed that aging led to the rearrangement of soil particles, tighter interparticle overlapping, and a reduction in pore space. The combination of MIP and XRμCT provided a comprehensive and reliable characterization of the soil pore structure. An increased diesel content increased the porosity and average diameter and reduced the tortuosity of the pores. Mechanistic analysis showed that aging weakens interparticle cohesion; this causes large agglomerates to break down into smaller agglomerates, resulting in a tighter arrangement and a subsequent reduction in porosity. An increase in diesel content increases the number of large agglomerates and pore spaces between agglomerates, resulting in increased porosity. Both aging and diesel content can weaken the permeation characteristics of soil.

关键词： MIP     XRμCT     aging     diesel content     pore structure     permeability characteristics    

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结合全变分最小化和稀疏字典学习后处理的低剂量CT重建 Article

Yong DING, Tuo HU

《信息与电子工程前沿（英文）》 2017年 第18卷 第12期   页码 2001-2008 doi: 10.1631/FITEE.1700287

摘要： 随着CT（computed tomography）中过量辐射剂量带来的健康风险日渐引发人们的担忧，低剂量CT得到了大量的关注。然而对于低剂量CT成像而言，在降低剂量的同时保证图像的高质量是一个很大的挑战。相比传统的滤波反投影算法，基于压缩感知的迭代重建法取得了良好的成像效果。但是迭代重建计算复杂度高，阻碍了其临床应用。

关键词： 低剂量CT；CT成像；全变分；稀疏字典学习    

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Simultaneous acquisition of CT angiography and whole brain CT perfusion images by using multiphase dynamic

Weiwei CHEN, Jianpin QI, Wenzhen ZHU, Wenhua HUANG, Jinmei SONG

《医学前沿（英文）》 2009年 第3卷 第2期   页码 230-235 doi: 10.1007/s11684-009-0023-8

摘要： We implemented a new protocol — multiphase dynamic helical scan to acquire CT angiography (CTA) and whole brain CT perfusion (CTP) images simultaneously with single scan on 16 multidetector CT (MDCT). A total of 90 patients who were randomly assigned into 3 groups were included in our study. Each group underwent CT scan by using the new protocol, traditional CTA and CTP protocol, respectively. The image quality of CTA, the CTP parameter values and the X-ray doses were measured and compared between the new protocol and the traditional protocols. There was no statistically significant difference in the CTA image quality between the above methods ( =0.55). For CTP parameters, the new protocol tended to overestimate the blood volume (BV) and blood flow (BF) value, and to underestimate the mean transit time (MTT) value compared with the traditional method. However, there was no statistically significant difference in BV, BF, and MTT value between the two methods except permeability surface (PS) ( >0.05). The volume CT dose index (CTDIvol) and dose length product (DLP) of our protocol were lower than the traditional one. The new protocol can obtain valuable diagnostic information in a shorter time without significant compromise in image quality. In addition, it reduces the radiation dose as well as contrast medium usage on the patient.

关键词： computed tomography angiography     computed tomography perfusion    

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Low-dose CT for lung cancer screening: opportunities and challenges

null

《医学前沿（英文）》 2018年 第12卷 第1期   页码 116-121 doi: 10.1007/s11684-017-0600-1

摘要：

Lung cancer is among the most frequently diagnosed cancers worldwide and the leading cause of cancer death in both males and females. Screening for lung cancer coupled with earlier intervention has long been studied as an approach to mortality reduction. However, minimal progress was achieved until recently, when low-dose spiral computed tomography (LDCT) screening demonstrated a 20% reduction in mortality from lung cancer in a randomized controlled trial (RCT), the National Lung Screening Trial, from the United States. On the basis of this finding, LDCT has been recommended for lung cancer screening in high-risk populations by several clinical guidelines. However, results from the following independent RCTs in Europe failed to show consistent conclusions. In addition, intractable problems gradually emerged with the progress of LDCT screening. This paper summarizes and discusses the main observations and challenges of LDCT screening for lung cancer. Before spreading implementation of LDCT screening, challenges, including high false-positive rates, overdiagnosis, enormous costs, and radiation risk, must be addressed. Complementary biomarkers and technical improvement are expected in the field of lung cancer screening in the near future.

关键词： lung cancer     low-dose computerized tomography     early detection     opportunities     challenges    

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The dynamic correction of collimation errors of CT slicing pictures

LIU Ya-xiong, Sekou Sing-are, LI Di-chen, LU Bing-heng

《机械工程前沿（英文）》 2006年 第1卷 第2期   页码 168-172 doi: 10.1007/s11465-006-0016-0

摘要： To eliminate the motion artifacts of CT images caused by patient motions and other related errors, two kinds of correctors (A type and U type) are proposed to monitor the scanning process and correct the motion artifacts of the original images via reverse geometrical transformation such as reverse scaling, moving, rotating and offsetting. The results confirm that the correction method with any of the correctors can improve the accuracy and reliability of CT images, which facilitates in eliminating or decreasing the motion artifacts and correcting other static errors and image processing errors. This provides a foundation for the 3D reconstruction and accurate fabrication of the customized implants.
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Creep-fatigue crack growth behavior in GH4169 superalloy

Dianyin HU, Xiyuan WANG, Jianxing MAO, Rongqiao WANG

《机械工程前沿（英文）》 2019年 第14卷 第3期   页码 369-376 doi: 10.1007/s11465-018-0489-7

摘要： This study aims to examine the crack growth behavior of turbine disc GH4169 superalloy under creep-fatigue loading. Crack growth experiments were performed on compact tension specimens using trapezoidal waveform with dwell time at the maximum load at 650 °C. The crack growth rate of GH4169 superalloy significantly increased with dwell time. The grain boundaries oxidize during the dwell process, thereby inducing an intergranular creep-fatigue fracture mode. In addition, testing data under the same dwell time showed scattering at the crack growth rate. Consequently, a modified model based on the Saxena equation was proposed by introducing a distribution factor for the crack growth rate. Microstructural observation confirmed that the small grain size and high volume fraction of the d phase led to a fast creep-fatigue crack growth rate at 650 °C, thus indicating that two factors, namely, fine grain and presence of the d phase at the grain boundary, increased the amount of weakened interface at high temperature, in which intergranular cracks may form and propagate.

关键词： crack growth rate     creep-fatigue     GH4169 superalloy     CT specimen     dwell time    

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A pilot study on Paxlovid therapy for hemodialysis patients with severe acute respiratory syndrome coronavirus 2 infections

《医学前沿（英文）》 doi: 10.1007/s11684-023-1011-0

摘要： We aimed to investigate the safety and efficacy of nirmatrelvir/ritonavir (Paxlovid) therapy for hemodialysis-dependent patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Thirteen hemodialysis patients infected with the Omicron variant of SARS-CoV-2 from April 3 to May 30, 2022, were recruited. Laboratory parameters and chest CT (computed tomography) imaging were analyzed. The treatment group included six patients who received 150 mg/100 mg of Paxlovid orally once daily for 5 days, whereas the control group included seven patients who received basic treatment. No serious adverse reactions or safety events were recorded. Four control patients progressed to moderate disease, and none in the treatment group showed progression of chest CT findings (P < 0.05). Paxlovid therapy tended toward early viral clearance and low viral load on Day 8. Moreover, 83.3% of the patients in the treatment group and 57.1% of the patients in the control group turned negative within 22 days. In the Paxlovid treatment group, we found significantly increased levels of lymphocytes (P=0.03) and eosinophils (P=0.02) and decreased levels of D-dimer on Day 8 compared with those on Day 1. Paxlovid therapy showed a potential therapeutic effect with good tolerance in hemodialysis patients. The optimal dose and effectiveness evaluation must be further investigated in a largeer cohort.

关键词： Paxlovid     hemodialysis     SARS-CoV-2     viral load     chest CT scan    

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Comparison of CT-guided aspiration to key hole craniotomy in the surgical treatment of spontaneous putaminal

ZHAO Jizong, WANG Dejiang, WANG Shuo, YUAN Ge, KANG Shuai, JI Nan, ZHAO Yuanli, YE Xun, ZHOU Liangfu, ZHOU Dingbiao, WANG Renzhi, WANG Mei

《医学前沿（英文）》 2007年 第1卷 第2期   页码 142-146 doi: 10.1007/s11684-007-0027-1

摘要： This study was designed to compare the approaches and efficacies of two different ways of neurosurgical management for spontaneous putaminal hemorrhage (SPH): computed tomographic-guided aspiration (CTGA) and the key-hole approach (KHA). The indications of the two approaches are also explored. From September 2001 to 2003, a total of 1077 cases of SPH distributed in 135 hospitals all over the mainland of China were included for analysis. All cases had three-month follow-up data. The study was designed in a single-blinded manner to compare the efficacies of the different approaches. There were 563 cases in the CTGA group, 165 in the KHA group, and 217 cases in the conventional open craniotomy (COC) group. In the CTGA and KHA groups, the mortalities at one month after operation (M1m) were 17.9% and 18.3%, respectively, while the mortalities at three months after operation (M3m) were 19.4% and 19.4%, respectively (>0.05). The postoperative complications due to CTGA (23.7%) were not significantly different from those due to KHA (25.7%) ( = 0.420). The M3m of patients with Glasgow coma scale (GCS) "d8 was 3.45 and 4.0 times as much as those with GCS>8, respectively. The M3m of patients with complications was 3.92 times as much as those without complications. The M3m of patients with hemorrhage volume "e70 mL was 2.67 times as much as those <70 mL. The CTGA is not better than KHA in the treatment of SPH in terms of a more favorable outcome or less mor tality and morbidity, but CTGA could be the first choice for those with bleeding volumes "d50mL, while KHA is the first choice for those with bleeding volumes >50 mL.

关键词： tomographic-guided aspiration     single-blinded manner     favorable outcome     operation     Glasgow    

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Trauma-induced “Macklin effect” with pneumothorax and large pneumomediastinum, disguised by allergy

null

《医学前沿（英文）》 2013年 第7卷 第3期   页码 386-388 doi: 10.1007/s11684-013-0278-y

摘要：

A 56-year-old man presented spontaneously to the Emergency Department complaining of facial and neck oedema after assumption of nonsteroidal anti-inflammatory drugs (NSAIDS). The triage nurse assigned the patient to Accident & Emergency (A&E) doctor as probable allergic reaction to NSAIDS. Chest X-ray (CXR), ordered after 24 hours, revealed a huge subcutaneous chest and neck emphysema without clearly visible pneumothorax. Subsequent chest CT scan showed a small left pneumothorax and a large amount of air in the mediastinum. The patient was conservatively treated since he was eupnoeic and hemodynamically stable. The pathophysiology of pneumomediastinum was first described by Macklin in 1939. The Macklin effect involves alveolar ruptures with air dissection along bronchovascular sheaths to the mediastinum. In this case the patient did not report in his history a recent blunt thoracic trauma and the initial suspicion of an allergic reaction has prevented physicians to immediately achieve the correct diagnosis.

关键词： thoracic trauma     differential diagnosis     critical care     pneumothorax     pneumomediastinum     CT scan     pitfalls     lung and airways physiology    

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A study on quality evaluation for bituminous mixture using X-ray CT

Satoshi TANIGUCHI, Keiichiro OGAWA, Jun OTANI, Itaru NISHIZAKI

《结构与土木工程前沿（英文）》 2013年 第7卷 第2期   页码 89-101 doi: 10.1007/s11709-013-0197-7

摘要： The objective of this paper is to propose a new quality evaluation method for asphalt concrete mixture using X-ray CT scanner. To achieve this aim, asphalt mixtures should be subjected to the X-ray CT scanning and its characteristics should be clarified. The approach employed in this study was as follows: 1) Coarse aggregate, fine aggregate, filler and bitumen were prepared; 2) dense-graded, coarse-graded and porous asphalt mixtures were made; 3) materials and mixtures were subjected to the X-ray CT scanning; 4) frequency of CT-value, threshold value, average slice CT-value, average segment CT-value were computed. In the material examination, CT-value of aggregate becomes smaller in the order of coarse aggregate, fine aggregate and filler and CT image of bitumen was nearly homogeneous. In the mixture examination, histograms of CT-value and four segmentation images made from CT images expressed the material and mixture characterization such as particle size and the difference in bitumen content and mixture type visibly and the bitumen content varies with the threshold values. In addition, the average segment CT-value without threshold value by dividing the fine aggregate from the coarse aggregate and average CT-value of the coarse aggregate, especially is highly correlated with average CT-value of the bitumen.

关键词： asphalt concrete mixture     aggregate     bitumen     bitumen content     quality evaluation     X-ray CT    

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A miniature triaxial apparatus for investigating the micromechanics of granular soils with

Zhuang CHENG, Jianfeng WANG, Matthew Richard COOP, Guanlin YE

《结构与土木工程前沿（英文）》 2020年 第14卷 第2期   页码 357-373 doi: 10.1007/s11709-019-0599-2

摘要： The development of a miniature triaxial apparatus is presented. In conjunction with an X-ray micro-tomography (termed as X-ray μCT hereafter) facility and advanced image processing techniques, this apparatus can be used for investigation of the micro-scale mechanical behavior of granular soils under shear. The apparatus allows for triaxial testing of a miniature dry sample with a size of (diameter height). triaxial testing of a 0.4–0.8 mm Leighton Buzzard sand (LBS) under a constant confining pressure of 500 kPa is presented. The evolutions of local porosities (i.e., the porosities of regions associated with individual particles), particle kinematics (i.e., particle translation and particle rotation) of the sample during the shear are quantitatively studied using image processing and analysis techniques. Meanwhile, a novel method is presented to quantify the volumetric strain distribution of the sample based on the results of local porosities and particle tracking. It is found that the sample, with nearly homogenous initial local porosities, starts to exhibit obvious inhomogeneity of local porosities and localization of particle kinematics and volumetric strain around the peak of deviatoric stress. In the post-peak shear stage, large local porosities and volumetric dilation mainly occur in a localized band. The developed triaxial apparatus, in its combined use of X-ray μCT imaging techniques, is a powerful tool to investigate the micro-scale mechanical behavior of granular soils.

关键词： triaxial apparatus     X-ray μCT     in situ test     micro-scale mechanical behavior     granular soils    

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analysis of soil failure on defective underground pipe due to cyclic water supply and drainage using X-ray CT

Toshifumi MUKUNOKI, Naoko KUMANO, Jun OTANI

《结构与土木工程前沿（英文）》 2012年 第6卷 第2期   页码 85-100 doi: 10.1007/s11709-012-0159-5

摘要： The ground subsidence on the underground pipe often is caused with the reduction of the effective stress and the loss of suction in the base course and then, soil drainage into the pipe. The final formation of the cavity growth in the ground was observed as the ground subsidence. Authors focused this problem and hence performed model tests with water-inflow and drainage cycle in the model ground. The mechanism of cavity generation in the model ground was observed using an X-ray Computed Tomography (CT) scanner. In those studies, water was supplied into the model grounds from the defected underground pipe model in case of the change of relative density and grain size distribution. As results, it was observed that the loosening area was generated from the defected part with water-inflow and some of the soil particles in the ground were drained into the underground pipe through the defected part. And afterward, the cavity was generated just above the defected part of the model pipe in the ground. Based on this observation, it might be said that the bulk density of soil around the defected pipe played one of key factor to generate the cavity in the ground. Moreover, the dimension of the defected part should be related to the magnification of the ground subsidence, in particular, crack width on a sewerage pipe and particle size would be the quantitative factor to evaluate the magnification of the ground subsidence. ?In this paper, it was concluded that the low relative density of soil would become the critical factor to cause the fatal failure of model ground if the maximum grain size was close to the dimension of crack width of defective part. The fatal collapse of the ground with high relative density more than 80% would be avoided in a few cycles of water inflow and soil drainage.

关键词： relative density     grain property     model test     road subsidence     underground pipe     image processing     X-ray CT    

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coefficient and microstructure parameters in concrete: A comparative analysis using NMR, MIP, and X-CT

Yurong ZHANG, Shengxuan XU, Yanhong GAO, Jie GUO, Yinghui CAO, Junzhi ZHANG

《结构与土木工程前沿（英文）》 2020年 第14卷 第6期   页码 1509-1519 doi: 10.1007/s11709-020-0681-9

摘要： Permeability is a major indicator of concrete durability, and depends primarily on the microstructure characteristics of concrete, including its porosity and pore size distribution. In this study, a variety of concrete samples were prepared to investigate their microstructure characteristics via nuclear magnetic resonance (NMR), mercury intrusion porosimetry (MIP), and X-ray computed tomography (X-CT). Furthermore, the chloride diffusion coefficient of concrete was measured to explore its correlation with the microstructure of the concrete samples. Results show that the proportion of pores with diameters<1000 nm obtained by NMR exceeds that obtained by MIP, although the difference in the total porosity determined by both methods is minimal. X-CT measurements obtained a relatively small porosity; however, this likely reflects the distribution of large pores more accurately. A strong correlation is observed between the chloride diffusion coefficient and the porosity or contributive porosity of pores with sizes<1000 nm. Moreover, microstructure parameters measured via NMR reveal a lower correlation coefficient versus the chloride diffusion coefficient relative to the parameters determined via MIP, as NMR can measure non-connected as well as connected pores. In addition, when analyzing pores with sizes>50 µm, X-CT obtains the maximal contributive porosity, followed by MIP and NMR.

关键词： permeability     microstructure     NMR     MIP     X-CT    

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苏通大桥基础工程的挑战与创新

游庆仲,董学武,吴寿昌

《中国工程科学》 2007年 第9卷 第6期   页码 22-26

摘要：

介绍了苏通大桥超大深水群桩基础利用工程钢护筒搭设施工平台、5000t承台钢吊箱整体同步沉放 及其与防船撞结构相结合构成永久防船撞设施、永久冲刷防护等三项技术创新；提出了特大型桥梁基础工程经 济合理的设计方案和安全可靠的施工法；阐明了理念创新和技术集成对大型复杂工程建设的重要性。

关键词： 苏通大桥     施工平台     钢吊箱     防撞结构     整体沉放     永久冲刷防护    

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基于实时CT扫描技术的CO2和N2交替注入条件下煤吸附膨胀和解吸收缩规律研究 Article

张广磊, P.G. Ranjith, Herbert E. Huppert

《工程（英文）》 2022年 第18卷 第11期   页码 88-95 doi: 10.1016/j.eng.2022.03.010

摘要： 本文采用原位同步辐射X射线显微CT扫描技术，首次在原位条件下直接证明了注入氮气（N2）可以置换解吸CO2并减小因CO2吸附引起的煤基质膨胀

关键词： CCS     CO2-ECBM     碳中和     X 射线成像     煤渗透率    

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标题 作者 时间 类型 操作

Analyzing the characterization of pore structures and permeability of diesel contaminated clays under different aging conditions

期刊论文

结合全变分最小化和稀疏字典学习后处理的低剂量CT重建

Yong DING, Tuo HU

期刊论文

Simultaneous acquisition of CT angiography and whole brain CT perfusion images by using multiphase dynamic

Weiwei CHEN, Jianpin QI, Wenzhen ZHU, Wenhua HUANG, Jinmei SONG

期刊论文

Low-dose CT for lung cancer screening: opportunities and challenges

null

期刊论文

The dynamic correction of collimation errors of CT slicing pictures

LIU Ya-xiong, Sekou Sing-are, LI Di-chen, LU Bing-heng

期刊论文

Creep-fatigue crack growth behavior in GH4169 superalloy

Dianyin HU, Xiyuan WANG, Jianxing MAO, Rongqiao WANG

期刊论文

A pilot study on Paxlovid therapy for hemodialysis patients with severe acute respiratory syndrome coronavirus 2 infections

期刊论文

Comparison of CT-guided aspiration to key hole craniotomy in the surgical treatment of spontaneous putaminal

ZHAO Jizong, WANG Dejiang, WANG Shuo, YUAN Ge, KANG Shuai, JI Nan, ZHAO Yuanli, YE Xun, ZHOU Liangfu, ZHOU Dingbiao, WANG Renzhi, WANG Mei

期刊论文

Trauma-induced “Macklin effect” with pneumothorax and large pneumomediastinum, disguised by allergy

null

期刊论文

A study on quality evaluation for bituminous mixture using X-ray CT

Satoshi TANIGUCHI, Keiichiro OGAWA, Jun OTANI, Itaru NISHIZAKI

期刊论文

A miniature triaxial apparatus for investigating the micromechanics of granular soils with

Zhuang CHENG, Jianfeng WANG, Matthew Richard COOP, Guanlin YE

期刊论文

analysis of soil failure on defective underground pipe due to cyclic water supply and drainage using X-ray CT

Toshifumi MUKUNOKI, Naoko KUMANO, Jun OTANI

期刊论文

coefficient and microstructure parameters in concrete: A comparative analysis using NMR, MIP, and X-CT

Yurong ZHANG, Shengxuan XU, Yanhong GAO, Jie GUO, Yinghui CAO, Junzhi ZHANG

期刊论文

苏通大桥基础工程的挑战与创新

游庆仲,董学武,吴寿昌

期刊论文

基于实时CT扫描技术的CO2和N2交替注入条件下煤吸附膨胀和解吸收缩规律研究

张广磊, P.G. Ranjith, Herbert E. Huppert

期刊论文