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Improved mechanical properties of siC fiber reinforced silica-based ceramic cores fabricated by stereolithography

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Journal of Materials science & Technology 2022年第21期116卷 161-168页

作者： W.Zheng J.M.Wu S.Chen K.B.Yu J.Zhang Y.s.shi state Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China Engineering Research Center of Ceramic Materials for Additive Manufacturing Ministry of EducationWuhan 430074China

silica-based ceramic cores have been widely used to fabricate aero-engine hollow blades due to their moderate high temperature mechanical properties and excellent leachability.In this study,silica-based ceramics with siC fiber addition were prepared via stereolithography,and the influence of siC fiber content on mechanical properties of the obtained silica-based ceramics was investigated.With the increase of siC fiber content,linear shrinkage gradually decreased,while room temperature flexural strength and high temperature flexural strength first increased and then decreased.As siC fiber content increased to 4.0 wt%,linear shrinkage was reduced to 0.62%resulting from the oxidation of siC.Furthermore,room temperature flexural strength was improved from 11.79 MPa to 23.83 MPa and high temperature flexural strength was enhanced from 15.64 MPa to 34.62 MPa with 4.0 wt%siC fiber addition due to the reinforcement of fibers and the enhancedβ-cristobalite content,which meets the need of ceramic cores.Therefore,it demonstrates the capability of fabricating high-performance and high-precision silica-based ceramic cores reinforced by siC fibers via stereolithography for rapid manufacturing of hollow blades.

关键词： silica-based ceramic cores stereolithography siC fiber Mechanical properties Hollow blades

Detection of diabetic retinopathy in its early stages using textural features of optical coherence tomography angiography

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Journal of Innovative Optical Health sciences 2022年第1期15卷 156-165页

作者： W.Gao B.Li S.Chen Y.shi P.Lin O.O.Myakinin V.P.Zakharov school of safety Engineering Ningbo University of Technology Ningbo P.R.China Department of Ophthalmology Ningbo First Hospital NingboP.R.China Department of Laser and Biotechnical systems samara University SamaraRussian Federation

The aim of this study is to detect whether the quantitative textural features of optical coherencetomography angiography (OCTA) images can be used to detect the eyes in the early stage ofdiabetic retinopathy (DR) from eyes with diabetes and no DR (NDR). Textural features includingfractal dimension, contrast, correlation, entropy, energy, and homogeneity were calculatedfrom the OCTA images. The student's t-test was performed to identify the textural featuresthat can be able to detect DR in the early stage. The area under the receiver operating characteristic(AUROC) curves, sensitivity, and specicity were calculated between the study groups.Our results indicated that the fractal dimension in ICP and sVP and the correlation in sVCshowed the statistical signicance between mild NPDR patients and NDR patients. The ROCanalysis results showed that the AUROC of the fractal dimension in ICP was 0.736 with 0.773sensitivity and 0.700 specicity. The cuto® point in ICP was 2.616. The OCTA-based fractaldimension was able to discriminate diabetic eyes with early retinopathy from healthy and NDRwith higher sensitivity and specicity. The OCTA-based correlation showed the power to differentiatethe mild NPDR eyes from the normal healthy and diabetic eyes. These results suggestthat texture-based features of OCTA have the potential to assist in the assessment of therapeuticinterventions to prevent early DR in diabetic subjects.

关键词： Optical coherence tomography angiography texture fractal dimension diabetic retinopathy

Dynamic mechanical properties,deformation and damage mechanisms of eutectic high-entropy alloy AlCoCrFeNi_(2.1)under plate impact

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Journal of Materials science & Technology 2023年第3期134卷 178-188页

作者： s.P.Zhao Z.D.Feng L.X.Li X.J.Zhao L.Lu S.Chen N.B.Zhang Y.Cai s.N.Luo The Peac Institute of Multiscale sciences ChengduChina Key Laboratory of Advanced Technologies of Materials Ministry of EducationSouthwest Jiaotong UniversityChengduChina

shock compression and spallation of a eutectic high-entropy alloy(HEA)AlCoCrFeNi_(2.1)with lamellar structure are investigated via plate impact loading with free-surface velocity measurements.The as-cast and postmortem samples are characterized with transmission electron microscopy,electron back-scatter diffraction and scanning electron microscopy.An accurate Hugoniot equation of state is determined.Af-ter shock compression to∼12 GPa,both the L1_(2)and B_(2)phases retain their ordered structures.Dense dislocations in the{111}slip planes,stacking faults and deformation twins are found in the L1_(2)phase,along with fewer dislocations in the{110}slip bands in the B(2)phase.shock-induced deformation twin-ning within the L1_(2)phase of this HEA is observed as a new deformation mechanism under various load-ing conditions.For spallation,both ductile and brittle damage modes are observed.The micro voids and cracks prefer to nucleate at the phase boundaries chiefly,then in the B(2)phase.Under similar shock stress,the spall strength of AlCoCrFeNi_(2.1)HEA is about 40%higher than those of other reported dual-phase HEAs due to the high stability of its semi-coherent phase boundaries.

关键词： High-entropy alloy Hugoniot spall damage Microstructure

Fast calculation of wave front amplitude propagation: a tool to analyze the 3D image on a hologram(Invited Paper)

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Chinese Optics Letters 2014年第6期12卷 95-98页

作者： J.-S.Chen D.P.Chu University of Cambridge Photonics and Sensors Group Department of Engineering9 JJ Thomson Avenue Cambridge UK

A simple approach to calculate the amplitude component of a wave front propagating in space from a hologram is proposed. It is able to calculate the amplitude distribution on a plane at any distance rapidly using a st... 详细信息

关键词： wave Fast calculation of wave front amplitude propagation a tool to analyze the 3D image on a hologram

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拥抱改变

科学新闻 2023年第5期 57-58页

作者： Jennifer S.Chen 倪伟波耶鲁大学

我觉得没有什么可失去的。在每周的Zoom电话会议上，博士生导师告诉我，系里另一位教授需要学生参与新冠病毒感染的紧急研究项目。“你有兴趣吗？”她问。我没有犹豫。在研究生院的前三年像是一场无休止的斗争，在一系列失败的实验后，...

我觉得没有什么可失去的。在每周的Zoom电话会议上，博士生导师告诉我，系里另一位教授需要学生参与新冠病毒感染的紧急研究项目。“你有兴趣吗？”她问。我没有犹豫。在研究生院的前三年像是一场无休止的斗争，在一系列失败的实验后，我的研究热情迅速消退。我不知道新项目会把我带向何方——但我知道自己需要改变。18个月过去了，现在回想起来，我知道自己做出了正确的决定。事实证明，新项目硕果累累，

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shock compression and spallation damage of high-entropy alloy Al_(0.1)CoCrFeNi

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Journal of Materials science & Technology 2022年第33期128卷 1-9页

作者： N.B.Zhang J.Xu Z.D.Feng Y.F.sun J.Y.Huang X.J.Zhao X.H.Yao S.Chen L.Lu s.N.Luo Key Laboratory of Advanced Technologies of Materials Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China The Peac Institute of Multiscale sciences Chengdu 610031China Department of Engineering Mechanics South China University of TechnologyGuangzhou 510641China

shock compression and spallation damage of a face-center cubic phase high-entropy alloy(HEA)Al_(0.1)CoCrFeNi were investigated via plate impact experiments along with free surface velocity measurements.Postmortem samples were characterized with transmission electron microscopy and electron backscatter diffraction.The Hugoniot equation of state and spall strength at different impact strengths were determined.There exists a power-law relation between spall strength and strain rate.The spall strength of Al_(0.1)CoCrFeNi HEA is about 50%higher than those of previously studied HEAs and comparable to those widely applied structural stainless steels at the same shock stress.Dislocation glide and stacking faults are the important deformation mechanisms in the Al_(0.1)CoCrFeNi HEA.Nanotwins are only observed at high shock stress.Damage in the Al_(0.1)CoCrFeNi HEA is ductile in nature.Voids are nucleated preferentially in grain interiors,and the intragranular voids show a strong dependence on grain boundary misorientation and peak stress.

关键词： Al_(0.1)CoCrFeNi High-entropy alloy Hugoniot spall damage Microstructure

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转型期中国的犯罪治理政策：堵还是疏？

经济学（季刊） 2012年第1期11卷 743-764页

作者：陈硕复旦大学经济学院香港科技大学社会科学部

面对日益上升的犯罪率,依靠快速增加司法投入来减少犯罪是否有效,这需要进行政策评估。在用中国省政法委书记的政治资历作为司法投入的工具变量,控制了司法投入和犯罪率之间的联立性内生问题之后,本文发现司法投入对犯罪率没有显著影响... 详细信息

面对日益上升的犯罪率,依靠快速增加司法投入来减少犯罪是否有效,这需要进行政策评估。在用中国省政法委书记的政治资历作为司法投入的工具变量,控制了司法投入和犯罪率之间的联立性内生问题之后,本文发现司法投入对犯罪率没有显著影响。相比之下,不断增长的犯罪率更大程度上是转型期多种社会经济特征综合所致。本文的政策含义是,中国的犯罪治理应以疏为主,以堵为辅。对非法行为进行直接打击虽然必不可少,但政策重点应该转向增加福利支出、提高教育水平、改善收入分配及给予外来居民户籍。此外,青春期男孩具有较高的犯罪倾向值得关注,由于人口密度增加而导致的犯罪上升也是城市化进程中特别需要注意的现象。

关键词：司法投入犯罪率内生性

Antiplane sH-deformations near a surface rigid foundation above a subsurface rigid circular tunnel

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Earthquake Engineering and Engineering Vibration 2002年第1期1卷 27-35页

作者： V.W.Lee M.E.Manoogian S.Chen Civil & Envir.Eng.Dept. Univ.of Southern CaliforniaLos AngelesCaliforniaU.S.A.Associate Professor Civil Eng.& Envir:sci.Dept. Loyola Marymount Univ.Los AngelesCaliforniaU.S.A.Associate Professor Civil & Envir.Eng.Dept. Univ.of Southern CaliforniaLos AngelesCaliforniaU.S.A. Research Associate

The problem on the dynamic response of a rigid embedded foundation in the presence of an underground rigid tunnel and subjected to excitation of incident anti-plane sH waves is analyzed.By using the exact analytical solution for the two-dimensional sH-wave propagation in and around both the surface rigid foundation and subsurface rigid tunnel,those aspects of the resulting ground motions that are of special interest and importance for seismic resistant design in earthquake analyses have been examined.The computed amplitudes of the resulting periodic ground motions display a very complicated wave-interference between the surface foundation and underground tunnel that lead to observed standing wave patterns, together with abrupt changes in the wave amplitudes and large amplification of the incident motions.

关键词： sH waves wave-interference embedded foundation underground tunnel analytical solution

EFFECT OF ELEVATED TEMPERATUREs ON HEAVY CONCRETE sTRUCTURAL sTRENGTH IN QINsHAN PHAsE 3 CANDU 6 REACTOR BUILDINGs

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EFFECT OF ELEVATED TEMPERATURES ON HEAVY CONCRETE STRUCTURAL...