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猪心房间隔穿刺的一种创新方法 被引量:1
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作者 杨力凡 潘文志 +6 位作者 张蕾 张晓春 李明飞 龙愉良 管丽华 周达新 葛均波 《复旦学报(医学版)》 CAS CSCD 北大核心 2023年第4期586-589,共4页
目的通过对猪心房间隔穿刺(atrial septum puncture,ASP)方法的改善,使操作更方便,心脏穿孔或心包积液的发生率更低,ASP更安全有效。方法在心腔内超声心动图(intra-cardiac echocardiography,ICE)引导下,使用0.014英寸SION导丝的尾端对2... 目的通过对猪心房间隔穿刺(atrial septum puncture,ASP)方法的改善,使操作更方便,心脏穿孔或心包积液的发生率更低,ASP更安全有效。方法在心腔内超声心动图(intra-cardiac echocardiography,ICE)引导下,使用0.014英寸SION导丝的尾端对28只约克夏白猪进行ASP。应用SPSS 22.0统计软件计算肺血流/全身血流平均值及平均ASP时间。术后4周观察房间隔穿刺孔闭合情况。结果成功对28只约克夏白猪进行ASP,超声心动图提示房间隔有左向右分流,无并发症发生。平均Qp/Qs为1.3±0.2(中位数1.3,95%CI:1.3~1.4),ASP平均用时(40.6±7.3)s(中位数41.0 s,95%CI:37.8~43.3 s)。手术4周后,28只猪的房间隔穿刺孔均内皮化导致闭合。结论在ICE引导下,使用0.014英寸SION导丝的尾端对约克夏白猪进行ASP安全且有效。 展开更多
关键词 房间隔穿刺(ASP) SION导丝 心腔内超声心动图(ICE)
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低密度碳粘接碳纤维复合材料(CBCF)抗氧化改性研究 被引量:8
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作者 师建军 张宗波 +3 位作者 冯志海 张大海 王筠 徐彩虹 《无机材料学报》 SCIE EI CAS CSCD 北大核心 2018年第7期728-734,共7页
以全氢聚硅氮烷(PHPS)为原料,采用浸渍-热转化方法,在低密度碳粘接碳纤维复合材料(CBCF)中短切碳纤维表面成功包覆硅氧氮(SiON)涂层。采用扫描电子显微镜(SEM)、能量色散X射线光谱(EDS)等分析测试手段对碳纤维表面的SiON涂层进行了形貌... 以全氢聚硅氮烷(PHPS)为原料,采用浸渍-热转化方法,在低密度碳粘接碳纤维复合材料(CBCF)中短切碳纤维表面成功包覆硅氧氮(SiON)涂层。采用扫描电子显微镜(SEM)、能量色散X射线光谱(EDS)等分析测试手段对碳纤维表面的SiON涂层进行了形貌和物相分析,结果表明:涂层主要由Si、O、N元素组成,在PHPS浓度为3wt%和5wt%条件下制备的涂层均匀、致密,随着PHPS浓度的提高,涂层厚度增加,但易发生结块。当PHPS浓度为10wt%和20wt%时,制备的SiON涂层出现结块并且存在裂纹。采用热重分析和等温氧化实验对纯CBCF和SiON涂层改性的CBCF复合材料抗氧化性能进行考核,结果显示碳纤维表面包覆SiON涂层能够显著提高CBCF复合材料的抗氧化性,随着PHPS浓度增大,低密度CBCF复合材料抗氧化性能显著提高。 展开更多
关键词 全氢聚硅氮烷 碳粘接碳纤维复合材料 浸渍-热转化法 SiON涂层 抗氧化
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SiON对Si基SiO_2AWG偏振补偿的数值分析 被引量:2
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作者 安俊明 郜定山 +3 位作者 李健 李建光 王红杰 胡雄伟 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2004年第7期858-862,共5页
采用全矢量交替方向隐含迭代方法系统分析了高折射率 Si ON薄膜对 Si基 Si O2 阵列波导光栅中波导应力双折射的影响 .分析结果表明在芯区上或下表面沉积 Si ON薄膜可以明显减小 Si基 Si O2 阵列波导光栅 (AWG)中波导的应力双折射 ,但这... 采用全矢量交替方向隐含迭代方法系统分析了高折射率 Si ON薄膜对 Si基 Si O2 阵列波导光栅中波导应力双折射的影响 .分析结果表明在芯区上或下表面沉积 Si ON薄膜可以明显减小 Si基 Si O2 阵列波导光栅 (AWG)中波导的应力双折射 ,但这两种补偿方法容易使模场偏移中心位置 ,不利于波导与光纤的耦合 .理想的补偿方法是在芯区上下同时补偿 ,可减小模场偏移 ,并用该方法设计了偏振无关的 1 6通道 AWG. 展开更多
关键词 SiON薄膜 Si基SiO2波导 应力 双折射 阵列波导光栅 偏振补偿 EEACC 4130
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Sub-pixel extraction of laser stripeand itsapplication in laser plane calibration 被引量:2
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作者 陈平 张志胜 +1 位作者 戴敏 陈恺 《Journal of Southeast University(English Edition)》 EI CAS 2015年第1期107-112,共6页
For calibrating the laser plane to implement 3D shape measurement, an algorithm for extracting the laser stripe with sub-pixel accuracy is proposed. The proposed algorithm mainly consists of two stages: two-side edge... For calibrating the laser plane to implement 3D shape measurement, an algorithm for extracting the laser stripe with sub-pixel accuracy is proposed. The proposed algorithm mainly consists of two stages: two-side edge detection and center line extraction. First, the two-side edge of laser stripe is detected using the principal component angle-based progressive probabilistic Hough transform and its width is calculated through the distance between these two edges. Secondly, the center line of laser strip is extracted with 2D Taylor expansion at a sub-pixel level and the laser plane is calibrated with the 3D reconstructed coordinates from the extracted 2D sub-pixel ones. Experimental results demonstrate that the proposed method can not only extract the laser stripe at a high speed, nearly average 78 ms/frame, but also calibrate the coplanar laser stripes at a low error, limited to 0.3 mm. The proposed algorithm can satisfy the system requirement of two-side edge detection and center line extraction, and rapid speed, high precision, as well as strong anti-jamming. 展开更多
关键词 sub-pixel extraction center line extraction laser plane calibration progressive probabilistic Hough transform (PPHT) principal component (PC) angle 2D Taylor expan- sion
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一种基于优化阈值函数的整体强化分解模型改进降噪方法 被引量:3
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作者 唐贵基 张文德 林琳 《科学技术与工程》 北大核心 2014年第16期134-138,共5页
以提高降噪效果为目的,提出了一种基于白噪声分解特性的EEMD优化阈值降噪方法。避免了小波分解时选择合适小波基函数的困难,具有自适应性,同时,也可以有效地避免频率混叠问题。方法从能量密度和对应平均周期乘积的变化率出发,提出了&qu... 以提高降噪效果为目的,提出了一种基于白噪声分解特性的EEMD优化阈值降噪方法。避免了小波分解时选择合适小波基函数的困难,具有自适应性,同时,也可以有效地避免频率混叠问题。方法从能量密度和对应平均周期乘积的变化率出发,提出了"跳变点"和"奇异点"的选择原则,并利用优化阈值函数对"跳变点"和"奇异点"对应的IMF分量进行量化处理,然后通过对处理后的IMF分量重构得到降噪信号。最后用仿真信号进行试验,证明本方法的有效性和优越性。 展开更多
关键词 整体强化分解模型(ensenble emprical MODE decompos sion EEMD) 优化阈值函数 降噪 跳变点 奇异点
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雪崩热电子注入对快速热氮化的SiO_xN_y膜陷阱的影响 被引量:4
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作者 陈蒲生 杨光有 《Journal of Semiconductors》 EI CAS CSCD 北大核心 1991年第7期405-411,共7页
本文研究了雪崩热电子注入对快速热氮化的SiO_zN_y膜体内电子陷阱和界面陷阱的影响.结果表明:快速热氮化的SiO_xN_y膜存在着不同类型的陷阱,其陷阱密度悬殊很大.雪崩热电子注入过程中在Si/SiO_xN_y界面上产生两类性质不同的快界面态陷阱... 本文研究了雪崩热电子注入对快速热氮化的SiO_zN_y膜体内电子陷阱和界面陷阱的影响.结果表明:快速热氮化的SiO_xN_y膜存在着不同类型的陷阱,其陷阱密度悬殊很大.雪崩热电子注入过程中在Si/SiO_xN_y界面上产生两类性质不同的快界面态陷阱.同时还给出这两种陷阱在禁带中的能级位置,界面态密度随雪崩注入的变化关系.文中并对实验结果进行讨论与分析. 展开更多
关键词 热电子注入 热氮化 SiON膜 陷阱
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Discriminative Latent Model Based Chinese Multiword Expression Extraction 被引量:2
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作者 Xiao, Sun 《China Communications》 SCIE CSCD 2012年第3期124-133,共10页
Discriminative Latent Model(DLM) is proposed for Multiword Expressions(MWEs) extraction in Chinese text to improve the performance of Machine Translation(MT) system such as Template Based MT(TBMT).For MT systems to be... Discriminative Latent Model(DLM) is proposed for Multiword Expressions(MWEs) extraction in Chinese text to improve the performance of Machine Translation(MT) system such as Template Based MT(TBMT).For MT systems to become of further practical use,they need to be enhanced with MWEs processing capability.As our study towards this goal,we propose DLM,which is developed for sequence labeling task including hidden structures,to extract MWEs for MT systems.DLM combines the advantages of existing discriminative models,which can learn hidden structures in sequence labeling task.In our evaluations,DLM achieves precisions ranging up to 90.73% for some type of MWEs,which is higher than state-of-the-art discriminative models.Such results demonstrate that it is feasible to automatically identify many Chinese MWEs using our DLM tool.With MWEs processing model,BLEU score of MT system has also been increased by up to 0.3 in close test. 展开更多
关键词 informationguage processing MT sions processing natural lan-DLM multiword expres-
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聚合物SiON波导的可变光衰减器性能研究
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作者 李九生 王少华 李建蕊 《中国计量学院学报》 2007年第3期208-210,227,共4页
利用弯曲聚合物SiON波导设计了一种新型可变光衰减器,该器件由输入、输出直波导,S型的弯曲波导,以及在聚合物SiON波导弯曲部位镀上的电极组成.通过外加电场的作用来调节波导覆盖层的折射率,从而达到衰减波导中光能量的目的.现采用光束... 利用弯曲聚合物SiON波导设计了一种新型可变光衰减器,该器件由输入、输出直波导,S型的弯曲波导,以及在聚合物SiON波导弯曲部位镀上的电极组成.通过外加电场的作用来调节波导覆盖层的折射率,从而达到衰减波导中光能量的目的.现采用光束传播法(BPM)对设计的新型光衰减器进行了仿真设计,结果表明,设计的光衰减器具有大的动态可调衰减范围(45.3 dB),低的插入损耗(0.8 dB). 展开更多
关键词 可变光衰减器 聚合物 SiON波导 光束传播法
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论邓小平的青年人才思想
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作者 王莉萍 《内蒙古社会科学》 CSSCI 北大核心 1995年第4期11-14,共4页
论邓小平的青年人才思想王莉萍建设有中国特色的社会主义理论是一个科学的体系,其中,邓小平同志的青年人才思想占有突出的地位并成为这个体系中的重要组成部分。邓小平同志应用马克思列宁主义毛泽东思想的人才理论,结合新时期建设有... 论邓小平的青年人才思想王莉萍建设有中国特色的社会主义理论是一个科学的体系,其中,邓小平同志的青年人才思想占有突出的地位并成为这个体系中的重要组成部分。邓小平同志应用马克思列宁主义毛泽东思想的人才理论,结合新时期建设有中国特色社会主义事业的伟大实践,创... 展开更多
关键词 :select of QUALIFIED MANPOWER THINK case BASE expansive deci- SION support system
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Carbon Footprint Analysis for Baby Strollers
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作者 Yu Ang Luo Yifan 《Chinese Journal of Population,Resources and Environment》 2012年第4期16-21,共6页
The increasing awareness of climate change has led organizations to demand a standard procedure to measure and communicate greenhouse gas(GHG) emissions linked to their products or services.The publicly available spec... The increasing awareness of climate change has led organizations to demand a standard procedure to measure and communicate greenhouse gas(GHG) emissions linked to their products or services.The publicly available specification PAS 2050 has been developed in response to broad community and industry desire for a consistent method-carbon footprint for assessing the life cycle GHG emissions of goods and services.Specifically,this paper illustrates the implementation of carbon footprint for a baby stroller in accordance with PAS 2050.A fial value of 321 kg per one stroller including package was calculated.Moreover,the study led to identify raw materials production of the stroller as the main source of GHS emissions where efforts need to focus for emission reduction opportunities.This case study is hoped to be a starting point for organizations to benefit from the increasing application of carbon footprint assessment. 展开更多
关键词 baby stroller carbon footprint greenhouse gas emis- sions life cycle PAS 2050
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全氢聚硅氮烷衍生法制备耐高温抗氧化SiON涂层 被引量:4
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作者 梁倩影 张宗波 +2 位作者 黄文文 周晓龙 徐彩虹 《涂料工业》 CAS CSCD 北大核心 2017年第7期1-5,共5页
以全氢聚硅氮烷为原料,经加热固化在金属表面制备得到致密均匀、厚度为2μm左右的SiON涂层。研究了全氢聚硅氮烷的固化过程,发现随固化温度升高,水解氧化反应程度提高,随之结构中Si—N、Si—H及N—H强度下降,Si—O强度升高。所得到的涂... 以全氢聚硅氮烷为原料,经加热固化在金属表面制备得到致密均匀、厚度为2μm左右的SiON涂层。研究了全氢聚硅氮烷的固化过程,发现随固化温度升高,水解氧化反应程度提高,随之结构中Si—N、Si—H及N—H强度下降,Si—O强度升高。所得到的涂层硬度达到9H以上,与金属基材之间结合良好,附着力0级。随固化温度升高,涂层表面润湿性能也随之变化,400℃固化得到的涂层表现为亲水性。SiON涂层具备较好的防腐蚀性能和耐高温抗氧化性能,对金属基材具有良好的保护作用,且随着固化温度升高,防腐蚀性能和耐高温性能随之增强。 展开更多
关键词 全氢聚硅氮烷 SiON涂层 耐高温 抗氧化性
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SiON钝化膜对硅衬底氮化镓绿光LED可靠性的影响 被引量:2
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作者 邱虹 刘军林 +1 位作者 王立 江风益 《发光学报》 EI CAS CSCD 北大核心 2011年第6期603-607,共5页
研制了4种不同表面钝化类型Si衬底GaN基绿光LED,分别标记为样品A、B、C、D。样品A无钝化层,样品B为台面SiON钝化,样品C为侧面SiON钝化,样品D为台面和侧面均钝化。将4种样品进行了常温60 mA(电流密度312 A/cm2)下168 h的加速老化,并对比... 研制了4种不同表面钝化类型Si衬底GaN基绿光LED,分别标记为样品A、B、C、D。样品A无钝化层,样品B为台面SiON钝化,样品C为侧面SiON钝化,样品D为台面和侧面均钝化。将4种样品进行了常温60 mA(电流密度312 A/cm2)下168 h的加速老化,并对比了老化前后的I-V和光衰等特性。结果表明:侧边的SiON钝化层可有效抑制有源区内非辐射复合缺陷的增加,从而有效降低器件老化后的漏电流和光衰。与台面上的SiON相比,侧边的SiON对钝化起到了决定性作用。 展开更多
关键词 SION SI衬底 GaN 光衰 LED
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PECVD SiON膜的性质及其在双层互连工艺中的应用 被引量:2
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作者 曾天亮 陈平 +1 位作者 江志庚 李志彭 《Journal of Semiconductors》 EI CAS CSCD 北大核心 1992年第6期386-390,共5页
我们在研制和生产双层布线的 3μm CMOS LSI器件时,采用了 PECVD SiON(等离子增强化学气相沉积的氮氧化硅)膜作金属层之间的绝缘层.这种薄膜具有很小的压应力,很低的针孔密度,良好的台阶覆盖性等优点.这种绝缘膜是采用PECVD沉积工艺,以... 我们在研制和生产双层布线的 3μm CMOS LSI器件时,采用了 PECVD SiON(等离子增强化学气相沉积的氮氧化硅)膜作金属层之间的绝缘层.这种薄膜具有很小的压应力,很低的针孔密度,良好的台阶覆盖性等优点.这种绝缘膜是采用PECVD沉积工艺,以氮冲稀的低浓度SiH_4(3%)和N_2O气体为原料制得的. 本文着重介绍 PECVD SiON膜的性质及其在双层互连工艺中的应用. 展开更多
关键词 SiON膜 PECVD沉积 双层互连工艺
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特种阻隔包装材料Si-O-N薄膜的制备
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作者 周美丽 《包装世界》 2010年第3期10-12,共3页
以六甲基二硅氧烷(HMDSO)和四甲基硅氧烷(TMDSO)为单体,以氧气以及氮气为反应气体,以氩气为电离气体,在载玻片、单晶硅片、PET等基材上采用13.56MHz射频等离子体聚合装置沉积硅氧氮薄膜。在薄膜的制备工艺中,通过改变各种工艺参数制备... 以六甲基二硅氧烷(HMDSO)和四甲基硅氧烷(TMDSO)为单体,以氧气以及氮气为反应气体,以氩气为电离气体,在载玻片、单晶硅片、PET等基材上采用13.56MHz射频等离子体聚合装置沉积硅氧氮薄膜。在薄膜的制备工艺中,通过改变各种工艺参数制备阻隔薄膜并研究所制备硅氧氮薄膜的性能。通过傅立叶红外光谱仪(FTIR)表征分析沉积膜的化学组成,采用透湿、透氧测试仪测试薄膜的阻隔性能,探讨工艺参数的变化对薄膜表面的成分和阻隔性能影响以及氮的加入对薄膜柔韧性的影响。 展开更多
关键词 阻隔包装 SION RF-PECVD 性能
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Ibrutinib alleviated LPS-induced neuroinflam⁃mation and synaptic defects in mouse model of depression 被引量:14
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作者 LI Wei-fen Tahir Ali +6 位作者 HE Kai-wu LIU Zi-zhen Fawad Ali Shah REN Qing-guo LIU Yan JIANG An-long LI Shu-peng 《中国药理学与毒理学杂志》 CAS 北大核心 2021年第9期684-685,共2页
OBJECTIVE Previous studies have demonstrated a close association between an altered immune system and major depressive disorders,and inhibition of neuroinflammation may represent an alternative mechanism to treat depr... OBJECTIVE Previous studies have demonstrated a close association between an altered immune system and major depressive disorders,and inhibition of neuroinflammation may represent an alternative mechanism to treat depression.Recently,the anti-inflammatory activ⁃ity of ibrutinib has been reported.However,the effect of ibrutinib on neuroinflammation-induced depression and its underlying mechanism has not been comprehensively studied.Therefore,we aimed to elucidate the potential anti-depres⁃sive role and mechanism of ibrutinib against neu⁃roinflammation-induced depression and synaptic defects.METHODS AND RESULTS Ibrutinib treatment significantly reduced lipopolysaccha⁃ride(LPS)-induced depressive-like behaviors and neuroinflammation via inhibiting NF-κB acti⁃vation,decreasing proinflammatory cytokine levels,and normalizing redox signaling and its downstream components,including Nrf2,HO-1,and SOD2,as well as glial cell activation mark⁃ers,such as Iba-1 and GFAP.Further,ibrutinib treatment inhibited LPS-activated inflammasome activation by targeting NLRP3/P38/caspase-1 signaling.Interestingly,LPS reduced the number of dendritic spines and expression of BDNF,and synaptic-related markers,including PSD95,snap25,and synaptophysin,were improved by ibrutinib treatment in the hippocampal area of the mouse brain.CONCLUSION Ibrutinib can allevi⁃ate neuroinflammation and synaptic defects,sug⁃gesting it has antidepressant potential against LPS-induced neuroinflammation and depression. 展开更多
关键词 ibrutinib NEUROINFLAMMATION depres⁃sion synaptic defects
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名物化后缀-t/sion在科技英语中的应用研究 被引量:3
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作者 宋艳 《西安航空学院学报》 2017年第2期65-68,共4页
以英国国家语料库、交大科技英语语料库分别作为参照语料库和观察语料库,从语料库语言学的角度分析了科技英语中名物化后缀-t/sion的使用情况。通过对比名物化后缀-t/sion与-ment,-ness,-ity在两个语料库中的使用,发现:科技英语文本中... 以英国国家语料库、交大科技英语语料库分别作为参照语料库和观察语料库,从语料库语言学的角度分析了科技英语中名物化后缀-t/sion的使用情况。通过对比名物化后缀-t/sion与-ment,-ness,-ity在两个语料库中的使用,发现:科技英语文本中名物化词汇使用较多,其中以-t/sion转换而来的名物化词汇在科技英语词汇中的使用最具典型性;语义层面,该名物化后缀主要用于描述科技领域中的各种现象、操作步骤和事物性质。 展开更多
关键词 语料库 科技英语 通用英语 名物化 -t/sion
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POLAR SETS OF MULTIPARAMETER BIFRACTIONAL BROWNIAN SHEETS 被引量:2
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作者 陈振龙 李慧琼 《Acta Mathematica Scientia》 SCIE CSCD 2010年第3期857-872,共16页
Let B^H'K={B^H'K(t), t∈R+^N} be an (N,d)-bifractional Brownian sheet with Hurst indices H = (H1,…,HN) C∈0,1)^N and K = (K1,…,KN) ∈ (0,1]^N. The properties of the polar sets of B^H'K are discussed. T... Let B^H'K={B^H'K(t), t∈R+^N} be an (N,d)-bifractional Brownian sheet with Hurst indices H = (H1,…,HN) C∈0,1)^N and K = (K1,…,KN) ∈ (0,1]^N. The properties of the polar sets of B^H'K are discussed. The sufficient conditions and necessary conditions for a compact set to be polar for B^H'K are proved. The infimum of Hausdorff dimensions of its non-polar sets are obtained by means of constructing a Cantor-type set to connect its Hausdorff dimension and capacity. 展开更多
关键词 Bifractional Brownian sheet polar set Hausdorff dimension packing dimen- sion capacity
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Experimental analysis of crack tip fields in rubber materials under large deformation 被引量:5
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作者 Xia Xiao Hai-Peng Song +3 位作者 Yi-Lan Kang Xiao-Lei Li Xiao-Hua Tan Hao-Yun Tan 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第2期432-437,共6页
A three-nested-deformation model is proposed to describe crack-tip fields in rubber-like materials with large deformation. The model is inspired by the distribution of the measured in-plane and out-of-plane deformatio... A three-nested-deformation model is proposed to describe crack-tip fields in rubber-like materials with large deformation. The model is inspired by the distribution of the measured in-plane and out-of-plane deformation. The in- plane displacement of crack-tip fields under both Mode 1 and mixed-mode (Mode I-II) fracture conditions is measured by using the digital Moir6 method. The deformation character- istics and experimental sector division mode are investigated by comparing the measured displacement fields under differ- ent fracture modes. The out-of-plane displacement field near the crack tip is measured using the three-dimensional digital speckle correlation method. 展开更多
关键词 Crack-tip field. Large deformation Sector divi- sion mode. Three-nested-deformation model- Digital Moir6 method
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Wave Attenuation Properties of Double Trapezoidal Submerged Breakwaters on Flat-Bed 被引量:2
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作者 曹永港 蒋昌波 白玉川 《Transactions of Tianjin University》 EI CAS 2012年第6期401-410,共10页
This paper investigates the wave attenuation properties of the double trapezoidal submerged breakwaters on the flat-bed by conducting physical experiments subjected to linear and cnoidal incident waves.The method of G... This paper investigates the wave attenuation properties of the double trapezoidal submerged breakwaters on the flat-bed by conducting physical experiments subjected to linear and cnoidal incident waves.The method of Goda's two points is used to separate the heights of incident,reflected and transmitted waves based on the experimental data.The possible factors affecting the wave attenuation properties of the double trapezoidal submerged breakwaters(i.e.,the relative submerged water depth,relative breakwater spacing,wave steepness and relative wave height) are investigated with respect to the reflection and transmission coefficients.The results show that there is a range,within which the breakwater spacing has little impact on the reflection coefficient,and the transmission coefficient tends to be a constant.The influence of the wave steepness is reduced while the breakwater spacing is too large or too small.Within the range of the relative wave height tested in this study,the reflection and transmission coefficients increase and decrease with the relative wave height,respectively.The double trapezoidal submerged breakwaters model indicates a good attenuation effect for larger wave steepness,big relative wave height and within the range of the relative breakwater spacing between 12.5 and 14 according to linear and cnoidal waves.The changes of wave energy spectra between the double submerged breakwaters on the flat-bed are investigated by the fast Fourier transform(FFT) method,showing that wave energy dissipation can be reached more effectively when the relative breakwater spacing is 12.5. 展开更多
关键词 linear wave cnoidal wave double trapezoidal submerged breakwaters reflection coefficient transmis- sion coefficient attenuation coefficient
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Theoretical and numerical investigation of HF elastic wave propagation in two-dimensional periodic beam lattices 被引量:1
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作者 B.Tie B.Y.Tian D.Aubry 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2013年第6期783-798,共16页
The elastic wave propagation phenomena in two-dimensional periodic beam lattices are studied by using the Bloch wave transform. The numerical modeling is applied to the hexagonal and the rectangular beam lattices, in ... The elastic wave propagation phenomena in two-dimensional periodic beam lattices are studied by using the Bloch wave transform. The numerical modeling is applied to the hexagonal and the rectangular beam lattices, in which, both the in-plane (with respect to the lattice plane) and out-of-plane waves are considered. The dispersion relations are obtained by calculating the Bloch eigenfrequencies and eigenmodes. The frequency bandgaps are observed and the influence of the elastic and geometric properties of the primitive cell on the bandgaps is studied. By analyzing the phase and the group velocities of the Bloch wave modes, the anisotropic behaviors and the dispersive characteristics of the hexagonal beam lattice with respect to the wave prop- agation are highlighted in high frequency domains. One im- portant result presented herein is the comparison between the first Bloch wave modes to the membrane and bend- ing/transverse shear wave modes of the classical equivalent homogenized orthotropic plate model of the hexagonal beam lattice. It is shown that, in low frequency ranges, the homog- enized plate model can correctly represent both the in-plane and out-of-plane dynamic behaviors of the beam lattice, its frequency validity domain can be precisely evaluated thanks to the Bloch modal analysis. As another important and original result, we have highlighted the existence of the retro- propagating Bloch wave modes with a negative group veloc- ity, and of the corresponding "retro-propagating" frequency bands. 展开更多
关键词 Elastic wave propagation Periodic beam lattice Bloch wave theory BANDGAPS ANISOTROPY Disper- sion relation
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