检索结果-南通市图书馆

基于显微CT的地下工程SBS防水卷材微观研究

在线全文

学校读者我要写书评

暂无评论

地下空间与工程学报 2016年第1期12卷 281-286页

作者：王庆国杨其新蒋雅君杨娟 gu allen 西南交通大学交通隧道工程教育部重点实验室成都610031 西南交通大学土木工程学院成都610031 卡尔蔡司X射线显微镜公司加利福尼亚普莱森顿94588

利用X射线CT技术对地下工程SBS改性沥青防水卷材的微观结构进行研究,探讨该技术在微观研究中的适用性。通过剪取SBS防水卷材原状试样置于显微CT系统上进行扫描,获得一系列的2D显微CT切片图像,借助图像处理软件进行3D图像的重构,并进行... 详细信息

利用X射线CT技术对地下工程SBS改性沥青防水卷材的微观结构进行研究,探讨该技术在微观研究中的适用性。通过剪取SBS防水卷材原状试样置于显微CT系统上进行扫描,获得一系列的2D显微CT切片图像,借助图像处理软件进行3D图像的重构,并进行图像处理,最后基于重构图像进行数据的统计和分析。结果表明:对试样的3D重构图像进行分析可以获得添加物颗粒的相关参数,同时可以清楚观察到试样的层状分布形态;试样各区域材料的差异性较大;等效直径60μm是颗粒数目分布的转折点,其两侧表现出不同的分布规律;中等颗粒和大颗粒对颗粒总体积有很大贡献。研究结果证实了采用显微CT技术对地下工程防水卷材进行微观研究的可行性,为地下工程防水材料损伤及其耐久性研究提供了一种新的途径。

关键词：地下工程防水卷材微观研究显微CT 等效直径

Rapid Large Volume 3D Mineral Processing and Liberation Characterization Technique to Sub Micron Resolution

在线全文

学校读者我要写书评

暂无评论

矿物学报 2013年第S1期33卷 78-78页

作者： S H Lau Susan Candell Sylvia Yun allen gu YUN Wenbing Xradia Inc 4385 Hopyard RdPleasantonCA 94588USA

We describe a novel lab based X-ray computed tomography system based on the architecture of X-ray Microscopes (XRM) used in synchrotron radiation facilities to be adapted for mineral processing and mineral liberation analysis. As this is a tomographic technique performed with an XRM, it is non-destructive and does not require complex preparation of polished sections typical of SEM-EDS techniques (such as MLA and QEMSCAN). It complements these existing techniques by providing 3D information and mineral liberation of multi-phase particles with much larger sample volume statistics but at a fraction of the time. In several applications, the technique is superior. These include the characterization of tailing loss in precious minerals; the characterization of porosity, particle size distribution, crack and pore network analysis during comminution, heap leaching and for texture and exposure/lock class analysis for floatation.

关键词： mineral liberation analysis (MLA) 3D mineral processing X-ray microscopy (XRM) computed tomography precious base and industrial minerals

Non Destructive 3D, 4D Microscopy and Mineral Phase Characterization in Industrial Minerals, Composites to Construction Materials

在线全文

学校读者我要写书评

暂无评论

矿物学报 2013年第S1期33卷 77-77页

作者： S H Lau Arno Merkle Susan Candell Sylvia Yun allen gu Wenbing Yun XradiaInc 4385 Hopyard RdPleasantonCA 94588USA

Conventional electron and optical microscopy techniques require the sample to be sectioned, polished or etched to expose the internal surfaces for imaging. However, such sample preparation techniques have traditionally prevented the observation of the same sample over time, under realistic three-dimensional geometries and in an environment representative of real-world operating conditions. X-ray microscopy (XRM) is a rapidly emerging technique that enables non-destructive evaluation of buried structures within hard to soft materials in 3D, requiring little to no sample preparation. Furthermore in situ and 4D quantification of microstructural evolution under controlled environment as a function of time, temperature, chemistry or stress can be done repeatable on the same sample, using practical specimen sizes ranging from tens of microns to several cm diameter, with achievable imaging resolution from submicron to 50 nm. Many of these studies were reported using XRM in synchrotron beamlines. These include crack propagation on composite and construction materials; corrosion studies; microstructural changes during the setting of cement; flow studies within porous media to mention but a few.

关键词： 3D and 4D microscopy in situ characterization mineral phase discrimination Dual Energy X-ray Tomography industrial minerals gemstone construction materials

Screening antioxidants for the protection of cochlear sensory cells

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2018年第1期13卷 62-64页

作者： Dong gu Hur Arwa Kurabi allen F.Ryan Department of Surgery/Otolaryngology School of Medicine University of CaliforniaSan Diego Department of Otorhinolaryngology Gyeongsang National University Changwon Hospital Research Service Veterans Administration Medical Center

Sensory cell damage is a major cause of hearing loss： Sensorineural hearing loss （SNHL） is a common sensory deficit characterized by tissue damage and/or cell death in the cochlea. Moderate and severe SNHL causes deficits in communication, associated with increased isolation from human relationships, and negativly impacts employabflity. Many etiologies have been associated with SNHL： Noise overexposure, certain drugs, inner or middle ear infection or immune-induced inflammation being common. However, the most prevalent form of SNHL is presbycusis or age-related hearing loss, often aggravated by other factors including a history of noise exposure, diabetes or high blood pressure （Wong and Ryan, 2015）. Though systemic steroids are used in the treatment of sudden SNHL, other drugs to prevent or cure hearing loss have not yet been developed. Cochlear sensory cells, known as hair cells （HCs） and neurons have very limited repair capacity. Moreover since these cells do not regenerate, making any loss permanent, prevention of cell damage is critical to protecting hearing.

关键词： HC Screening antioxidants for the protection of cochlear sensory cells

Petrography and chronology of lunar meteorite Northwest Africa 6950

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2020年第4期63卷 182-194页

作者： Zemin BAO Yuruo SHI J.Lawford ANDERSON allen KENNEDY Zuokai KE Xiangping gu Peizhi WANG Xiaochao CHE Yuelan KANG Huiyi SUN Chen WANG Beijing SHRIMP Center Institute of Geology Chinese Academy of Geological Sciences John de Laeter Centre Curtin University Department of Earth and Environment Boston University School of Geosciences and Infophysics Central South University

Northwest Africa(NWA) 6950 is an olivine-gabbro lunar meteorite that has a distinctly different petrographic texture from other lunar basalts. In this contribution, we report the petrography, mineralogy,and U-Pb geochronology of baddeleyite and phosphate in this lunar meteorite and make a comparison with other NWA 773 paired meteorites. NWA 6950 consists mainly of coarse-grained olivine, pyroxene,and plagioclase, with minor ilmenite, chromite, troilite, baddeleyite, taenite, and apatite. The abundant rounded to euhedral olivine has a limited Fo ranging from 68 to 69. Pyroxenes include both augite and pigeonite, with a narrow range of Mg#=71–80, and composition, respectively, EnFsWoand EnFsWo. Plagioclase is mainly anhedral, conforming to the crystal margins of olivine and pyroxene. The plagioclase grains are elongated and several hundreds of microns in length. Raman spectra shows that plagioclase has been transformed into maskelynite, which is very calcic(An87-95) with low sodium and very low potassium(Ab4-9 Or 0.6-3.7). The weighted mean207 Pb/206 Pb ages of baddeleyite and phosphate measured using a sensitive high resolution ion micro probe(SHRIMP II) are 3119 ± 16 Ma(n = 9, MSWD= 2.5)(mean squared weighted deviates, MSWD) and 3119 ± 18 Ma(n = 15, MSWD = 2.1), respectively,giving the crystallization age of the meteorite. NWA 6950 has similar mineral compositions, geochemical characteristics, and an almost identical age of crystallization to the magnesian gabbro of the NWA 773 *** conclude that NWA 6950 and NWA 773 are paired meteorites, which crystallize at ca. 3119 Ma, and represent magmatic activities in the KREEP(potassium(K), rare earth elements(REE) and phosphorus(P) rich lunar material) region of the Moon.

关键词： Northwest Africa 6950 lunar meteorite U-Pb chronology baddeleyite phosphate

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

市政供配水管网无线监测系统和实践

中国给水排水 2022年第8期38卷 1-9页

作者：顾遥 Michael allen 赛莱默<中国>有限公司上海200051

管道结构监测是市政供配水系统的重大挑战。特别是在管道发生故障后,应尽快进行检测和故障定位,并预先确定市政供配水管网的重点区域,或更有可能发生结构性故障的区域。WaterWiSe是一个系统平台,负责管理和分析来自智能无线传感器节点... 详细信息

管道结构监测是市政供配水系统的重大挑战。特别是在管道发生故障后,应尽快进行检测和故障定位,并预先确定市政供配水管网的重点区域,或更有可能发生结构性故障的区域。WaterWiSe是一个系统平台,负责管理和分析来自智能无线传感器节点网络的数据,持续监测水力、声学和水质参数。该平台支持许多应用,包括用水需求和水力状态的动态预测,爆管等事件的在线检测,以及用于识别长期趋势的数据挖掘。重点介绍部署于新加坡的WaterWiSe@SG项目,包括WaterWiSe在监测、检测和预测异常事件(表明管道出现结构性故障,如爆管或漏水)方面的使用情况,可为同行提供借鉴。

关键词：供配水系统无线传感器网络在线事件检测定位压力瞬变水锤监测

Efficient Dual Algorithms for Image Segmentation Using TV-allen-Cahn Type Models

在线全文

学校读者我要写书评

暂无评论

Communications in Computational Physics 2011年第4期9卷 859-877页

作者： Li-Lian Wang Ying gu Division of Mathematical Sciences School of Physical and Mathematical SciencesNanyang Technological University637371Singapore

Variational image segmentation based on the Mumford and Shah model[31],together with implementation by the piecewise constant level-set method(PCLSM)[26],leads to fully nonlinear Total Variation(TV)-allen-Cahn *** commonlyused numerical approaches usually suffer from the difficulties not only with the nondifferentiability of the TV-term,but also with directly evolving the discontinuous piecewise constant-structured *** this paper,we propose efficient dual algorithms to overcome these *** use of a splitting-penalty method results in TVallen-Cahn type models associated with different"double-well"potentials,which allow for the implementation of the dual algorithm of Chambolle[8].Moreover,we present a new dual algorithm based on an edge-featured penalty of the dual variable,which only requires to solve a vectorial allen-Cahn type equation with linear∇(div)-diffusion rather than fully nonlinear diffusion in the Chambolle’s ***,more efficient numerical algorithms such as time-splitting method and Fast Fourier Transform(FFT)can be *** numerical tests show that two dual algorithms are much faster and more stable than the primal gradient descent approach,and the new dual algorithm is at least as efficient as the Chambolle’s algorithm but is more *** demonstrate that the new method also provides a viable alternative for image restoration.

关键词： Variational models image segmentation TV-allen-Cahn type equations dual algorithms splitting-penalty methods FFT.

Identification of ring current proton precipitation driven by scattering of electromagnetic ion cyclotron waves

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Fundamental Research 2023年第2期3卷 257-264页

作者： Binbin Ni Yang Zhang Xudong gu Department of Space Physics School of Electronic InformationWuhan UniversityWuhanHubei 430072China CAS Center for Excellence in Comparative Planetology Hefei 230026China MNR Key Laboratory for Polar Science Polar Research Institute of ChinaShanghai 200136China

Among the most intense emissions in the Earth's magnetosphere,electromagnetic ion cyclotron(EMIC)waves are regarded as a critical candidate contributing to the precipitation losses of ring current protons,which however lacks direct multi-point observations to establish the underlying physical *** upon a robust conjunction between the satellite pair of Van allen Probe B and NOAA-19,we perform a detailed analysis to capture simultaneous enhancements of EMIC waves and ring current proton *** assuming that the ring current proton precipitation is mainly caused by EMIC wave scattering,we establish a physical model between the wave-driven proton diffusion and the ratio of precipitated-to-trapped proton count rates,which is subsequently applied to infer the intensity of EMIC waves required to cause the observed proton *** simulations indicate that the model results of EMIC wave intensity,obtained using either the observed or empirical Gaussian wave frequency spectrum,are consistent with the wave observations,within a factor of *** study therefore strongly supports the dominant contribution of EMIC waves to the ring current proton precipitation,and offers a valuable means to construct the global profile of EMIC wave intensity using low-altitude NOAA POES proton measurements,which generally have a broad L-shell coverage and high time resolution in favor of near-real-time conversion of the global EMIC wave distribution.

关键词： Electromagnetic ion cyclotron waves Ring current protons Wave-particle interactions Conjugate observations Precipitation losses

Hemispheric Distribution of Lower-band Chorus Waves Observed by Van allen Probes

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

空间科学学报 2020年第2期40卷 186-196页

作者： CHENG Xiaowei gu Xudong NI Binbin ZHANG Yang Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072

Whistler mode chorus waves are important electromagnetic emissions due to their dual roles in acceleration and loss processes of Earth's radiation belt electrons.A detailed global survey of lower-band chorus is performed using EMFISIS data from Van allen Probes in near-equatorial *** addition to the confirmation of the positive correlation of chorus wave intensities to geomagnetic activity and dayside-nightside distribution asymmetry of wave amplitude and occurrence probability,the analysis results find that in statistics lower-band chorus emissions exhibit higher wave occurrence rates and larger normalized peak wave frequencies in the magnetically northern hemisphere but somehow stronger peak wave intensities in the magnetically southern *** overall the differences between the two magnetically hemispheric distributions tend to be not significant,it is important to establish the magnetically hemispheric distribution profiles of lowerband chorus with respect to L-shell,magnetic local time,and geomagnetic latitude for improved understanding of chorus-induced dynamics of radiation belt electrons.

关键词： Lower-band chorus Hemispheric distribution Wave intensities Occurrence rates Normalized peak wave frequency