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Shear band evolution and acoustic emission characteristics of sandstone containing non-persistent flaws
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作者 Shuting Miao Peng-Zhi Pan +1 位作者 Chuanqing Zhang Lei Huo 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第2期497-513,共17页
Direct shear tests were conducted on sandstone specimens under different constant normal stresses to study the coalescence of cracks between non-persistent flaws and the shear sliding characteristics of the shear-form... Direct shear tests were conducted on sandstone specimens under different constant normal stresses to study the coalescence of cracks between non-persistent flaws and the shear sliding characteristics of the shear-formed fault.Digital image correlation and acoustic emission(AE)techniques were used to monitor the evolution of shear bands at the rock bridge area and microcracking behaviors.The experimental results revealed that the shear stresses corresponding to the peak and sub-peak in the stressdisplacement curve are significantly affected by the normal stress.Strain localization bands emerged at both the tip of joints and the rock bridge,and their extension and interaction near the peak stress caused a surge in the AE hit rate and a significant decrease in the AE b value.Short and curvilinear strain bands were detected at low normal stress,while high normal stress generally led to more microcracking events and longer coplanar cracks at the rock bridge area.Furthermore,an increase in normal stress resulted in a higher AE count rate and more energetic AE events during friction sliding along the shearformed fault.It was observed that the elastic energy released during the crack coalescence at the prepeak stage was much greater than that released during friction sliding at the post-peak stage.More than 75%of AE events were located in the low-frequency band(0e100 kHz),and this proportion continued to rise with increasing normal stress.Moreover,more AE events of low AF value and high RA value were observed in specimens subjected to high normal stress,indicating that greater normal stress led to more microcracks of shear nature. 展开更多
关键词 Shear band evolution Acoustic emission(AE) Crack coalescence normal stress Shear sliding
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Inertial Parameters in Identical and Non-identical Bands at Normal Deformation
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作者 Zhang Jingye I.Ragnarsson and L.L. Riedinger(Department of Physics, University of Tennessee, Knoxville, TN 37996-1200Physics Department, Broohhaven National laboratory, Upton, NY 11973.Institute of Modern Phyaics, Lanzhou, Gansu PRC.Dept. of Math. Physics 《IMP & HIRFL Annual Report》 1994年第0期114-114,共1页
Inertial Parameters in Identical and Non-identical Bands at Normal DeformationZhangJingye;I.RagnarssonandL.L... Inertial Parameters in Identical and Non-identical Bands at Normal DeformationZhangJingye;I.RagnarssonandL.L.Riedinger(Depart... 展开更多
关键词 identical DEFORMATION Identical INERTIAL Non normal PARAMETERS and at bandS
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A tunable dual-broad-band branch-line coupler utilizing composite right/left-handed transmission lines
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作者 章瑜 胡黎 何赛灵 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2005年第6期483-486,共4页
A tunable dual-broad-band branch-line coupler (BLC) utilizing composite right/left-handed (CRLH) transmission lines is presented. Two λ/4 segments consisting of CRLH transmission lines are added to each port to broad... A tunable dual-broad-band branch-line coupler (BLC) utilizing composite right/left-handed (CRLH) transmission lines is presented. Two λ/4 segments consisting of CRLH transmission lines are added to each port to broaden the dual bands of the branch-line coupler. Numerical simulation and optimal design of the novel coupler are presented. The dual bands of the novel coupler are tunable and broad. The 1-dB bandwidth of each pass band is more than 16% of the central frequency. 展开更多
关键词 BLC 分歧线 双宽边 左右手定则 可调性
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Human Rights Protection under the New Normal State of Economy
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作者 常健 黄爱教 《The Journal of Human Rights》 2015年第4期312-324,共13页
The new normal state of economy is not only the overall trend of China's current economic development stage, but also the strategic choice of China for the future economic development, the anticipation for the eco... The new normal state of economy is not only the overall trend of China's current economic development stage, but also the strategic choice of China for the future economic development, the anticipation for the economic development and its outcome under the new strategy. It is of great strategic significance for the long-term development of China's human rights as a whole, yet it makes a short-term challenge to the realization of the rights of vulnerable groups. Under the new normal state of economy, it should be targeted to strengthen the protection of the rights of vulnerable groups, which is very important not only for the overall development of China's human rights causes, but also for China to cross over 'the middle-income trap' and to achieve sustainable development of economy. 展开更多
关键词 the new normal state of economy guarantee of human rights the middle-income trap rights of vulnerable groups
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Suppression of Log-Normal Distributed Weather Clutter Observed by an S-Band Radar
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作者 Shuji Sayama Seishiro Ishii 《Wireless Engineering and Technology》 2013年第3期125-133,共9页
We have observed weather clutter containing targets (ships) using an S-band radar with a frequency 3.05 GHz, a beam width 1.8°, and a pulsewidth 0.5 μs. To investigate the weather clutter amplitude statistics, w... We have observed weather clutter containing targets (ships) using an S-band radar with a frequency 3.05 GHz, a beam width 1.8°, and a pulsewidth 0.5 μs. To investigate the weather clutter amplitude statistics, we introduce the Akaike Information Criterion (AIC). We have found that the weather clutter amplitudes obey the log-normal, Weibull, and log-Weibull distributions with the shape parameters of 0.308 to 0.470, 4.42 to 4.51, and 15.91 to 16.44, respectively, for small data within the beam width of an antenna. We have proposed the log-normal/CFAR circuit modified a Cell-Averaging (CA) LOG/CFAR circuit. It is found that weather clutter is suppressed with improvement of 51.58 dB by log-normal/CFAR. As a result, we have showed that weather clutter observed by S-band radar does not obey the Rayleigh distribution and our log-normal/CFAR circuit has an effect on suppression of clutter and detection of target, while conventional LOG/CFAR circuit does not. In addition, if our circuit can be realized, we will have an advantage economically. 展开更多
关键词 CFAR S-band RADAR WEATHER CLUTTER Log-normal Distribution
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经食道超声心动图右心声学造影中应用手振加血激活生理盐水显影对卵圆孔未闭的诊断价值
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作者 曹静 郭丽焱 《中国心血管病研究》 CAS 2024年第6期565-570,共6页
目的 探讨经食道超声心动图右心声学造影(TEE-cTTE)中应用手振加血激活生理盐水(ASB)显影对卵圆孔未闭(PFO)的诊断价值。方法 选取2020年7月至2023年1月临汾市人民医院疑似PFO患者106例,根据相关诊断标准分为PFO组(78例)与非PFO组(28例)... 目的 探讨经食道超声心动图右心声学造影(TEE-cTTE)中应用手振加血激活生理盐水(ASB)显影对卵圆孔未闭(PFO)的诊断价值。方法 选取2020年7月至2023年1月临汾市人民医院疑似PFO患者106例,根据相关诊断标准分为PFO组(78例)与非PFO组(28例),均行TEE-cTTE检查,根据造影剂类型分为ASB、手振激活50%葡萄糖溶液(AGB)、手振激活生理盐水(AS),对比3种造影剂右心开始显影到微气泡逐渐减少到每帧图像低于10个微气泡的时间(T-R)、两组卵圆孔内径和隧道长度,分析3种造影剂行TEE-cTTE检查对PFO、PFO类型及右向左分流(RLS)的诊断价值。结果 ASB静息状态下、Valsalva动作下T-R长于AGS、AS,AGS静息状态下、Valsalva动作下T-R长于AS(P<0.05);3种造影剂检测PFO组卵圆孔内径长于非PFO组(P<0.05);ASB、AGS检测的PFO组卵圆孔内径长于AS检测(P<0.05);ROC曲线分析,ASB行TEE-cTTE诊断PFO的AUC为0.872(95%CI 0.793~0.929),敏感度为92.31%(72/78),特异度为82.14%(23/28);AGS行TEE-cTTE诊断PFO的AUC为0.842(95%CI 0.758~0.905),敏感度为89.74%(70/78),特异度为78.57%(22/28);AS行TEE-cTTE诊断PFO行TEE-cTTEAUC为0.672(95%CI 0.574~0.760),敏感度为80.77%(63/78),特异度为53.57%(15/28),提示ASB、AGS行TEE-cTTE诊断PFO的价值优于AS;ASB行TEE-cTTE检查诊断PFO类型、RLS分级与临床诊断结果的一致性较高(Kapp值=0.819、0.838);AGS行TEE-cTTE检查诊断PFO类型、RLS分级与临床诊断结果的一致性一般(Kapp值=0.653、0.655);AS行TEE-cTTE检查诊断PFO类型与临床诊断结果的一致性较差(Kapp值=0.393),诊断RLS分级与临床诊断结果的一致性一般(Kapp值=0.480)。结论 TEE-cTTE检查中应用ASB显影能延长T-R时间,提高PFO诊断价值,且在诊断PFO类型、RLS分级方面表现出与临床诊断结果较高的一致性,有利于开展具有针对性、科学性的临床诊治工作。 展开更多
关键词 卵圆孔未闭 右向左分流 经食道超声心动图 右心声学造影 手振加血激活生理盐水 诊断价值
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青藏高原多尔索洞错水深反演与水量变化估算
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作者 崔剑 乔宝晋 +1 位作者 郭恒亮 杨洪 《人民长江》 北大核心 2024年第4期142-149,共8页
利用由实测水深空间插值获得的水下地形数据估算湖泊水量及其变化往往存在较大误差。以Landsat系列影像数据及多尔索洞错12 m以下实测水深数据为基础,建立多波段组合模型进行水深模拟,结合多时相Landsat影像获取的多尔索洞错边界数据获... 利用由实测水深空间插值获得的水下地形数据估算湖泊水量及其变化往往存在较大误差。以Landsat系列影像数据及多尔索洞错12 m以下实测水深数据为基础,建立多波段组合模型进行水深模拟,结合多时相Landsat影像获取的多尔索洞错边界数据获取水深变化,估算1996~2016年多尔索洞错水量变化。实验结果表明:多因子反演模型的相关系数(R^(2))均在0.90以上,平均绝对误差低至0.48 m,相比空间插值方法能更精确地模拟多尔索洞错水深在12 m以下区域的水深分布情况;近20 a来多尔索洞错不断扩张,水位升高约0.40 m/a,水量增加约0.18 km^(3)/a。 展开更多
关键词 水深反演 水量变化 归一化水体指数法(NDWI) 多波段组合模型 多尔索洞错
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正火冷却速度对20CrNiMo钢组织和性能的影响
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作者 杨维庆 杨仲书 +3 位作者 张宏福 杨超 韩仁杰 刘爱军 《金属加工(热加工)》 2024年第4期1-4,共4页
利用扫描电镜、金相显微镜和硬度计等检测手段研究不同正火冷却速度对20CrNiMo钢组织和性能的影响。结果表明:经炉冷的20CrNiMo钢组织中主要为珠光体和铁素体;经风冷的20CrNiMo钢组织中主要为珠光体和铁素体,此外还发现少量的马氏体;经... 利用扫描电镜、金相显微镜和硬度计等检测手段研究不同正火冷却速度对20CrNiMo钢组织和性能的影响。结果表明:经炉冷的20CrNiMo钢组织中主要为珠光体和铁素体;经风冷的20CrNiMo钢组织中主要为珠光体和铁素体,此外还发现少量的马氏体;经空冷+风冷的20CrNiMo钢组织中除了珠光体和铁素体外,还发现一定量的马氏体。随着正火冷却速度的增加,容易诱发马氏体相变。此外还发现,随着正火冷却速度的增加,20CrNiMo钢的洛氏硬度基本保持平稳,显微硬度部分区域有所上升,这与组织变化趋势相一致。 展开更多
关键词 正火 带状组织 冷却速度 力学性能
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所有权保留的雅努斯之面:从形式主义向功能主义
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作者 张永 《法治研究》 北大核心 2024年第3期131-146,共16页
《民法典》转向功能主义担保观,所有权保留从所有权构成转向担保权构成。卖方是担保权人,买方是所有权人,其处分是有权处分。若第三方是正常经营买受人,不管其是否知情,都取得完整所有权。若第三方不是正常经营买受人且所有权保留已登记... 《民法典》转向功能主义担保观,所有权保留从所有权构成转向担保权构成。卖方是担保权人,买方是所有权人,其处分是有权处分。若第三方是正常经营买受人,不管其是否知情,都取得完整所有权。若第三方不是正常经营买受人且所有权保留已登记,则其取得附所有权保留负担的所有权。若买方又在保留物上设定担保物权,则依《民法典》第414、415条统一排序。若满足第416条,则所有权保留有价款优先效力。若所有权保留没登记,则不能对抗善意承租人、善意购买人、扣押债权人、破产债权人。卖方转让债权时,保留的所有权作为从权利应随之转移。卖方的取回权是一种担保物权实现方式,不是合同解除权。 展开更多
关键词 所有权保留 功能主义 担保权构成 取回权 正常经营买受人
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Right pp Semigroups with Multiplicative Right Adequate Transversals 被引量:1
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作者 HU Yao-hua GUO Xiao-jiang 《Chinese Quarterly Journal of Mathematics》 CSCD 2011年第3期366-371,共6页
在这份报纸, rpp semigroups 的恰好足够的 transversals 的概念被介绍。我们以恰好正常的乐队和正确足够的 semigroups 与趋于增加的恰好足够的 transversals 建立 rpp semigroups 的结构。特别地,一些特殊情况被考虑。
关键词 rpp semigroup 恰好足够横过 恰好正常的乐队
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Establishment of adult right ventricle failure in ovine using a graded, animal-specific pulmonary artery constriction model 被引量:1
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作者 Michael Nguyen-Truong Wenqiang Liu +4 位作者 June Boon Brad Nelson Jeremiah Easley Eric Monnet Zhijie Wang 《Animal Models and Experimental Medicine》 CSCD 2020年第2期182-192,共11页
Background: Right ventricle failure(RVF) is associated with serious cardiac and pulmonary diseases that contribute significantly to the morbidity and mortality of patients. Currently, the mechanisms of RVF are not ful... Background: Right ventricle failure(RVF) is associated with serious cardiac and pulmonary diseases that contribute significantly to the morbidity and mortality of patients. Currently, the mechanisms of RVF are not fully understood and it is partly due to the lack of large animal models in adult RVF. In this study, we aim to establish a model of RVF in adult ovine and examine the structure and function relations in the RV.Methods: RV pressure overload was induced in adult male sheep by revised pulmonary artery constriction(PAC). Briefly, an adjustable hydraulic occluder was placed around the main pulmonary artery trunk. Then, repeated saline injection was performed at weeks 0, 1, and 4, where the amount of saline was determined in an animal-specific manner. Healthy, age-matched male sheep were used as additional controls. Echocardiography was performed bi-weekly and on week 11 post-PAC, hemodynamic and biological measurements were obtained.Results: This PAC methodology resulted in a marked increase in RV systolic pressure and decreases in stroke volume and tricuspid annular plane systolic excursion, indicating signs of RVF. Significant increases in RV chamber size, wall thickness, and Fulton's index were observed. Cardiomyocyte hypertrophy and collagen accumulation(particularly type III collagen) were evident, and these structural changes were correlated with RV dysfunction.Conclusion: In summary, the animal-specific, repeated PAC provided a robust approach to induce adult RVF, and this ovine model will offer a useful tool to study the progression and treatment of adult RVF that is translatable to human diseases. 展开更多
关键词 animal models FIBROSIS pulmonary artery banding pulmonary hypertension right heart failure
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Effect of Changes in Sea-Surface State on Statistical Characteristics of Sea Clutter with X-Band Radar 被引量:1
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作者 Seishiro Ishii Syuji Sayama Koichi Mizutani 《Wireless Engineering and Technology》 2011年第3期175-183,共9页
We have made observations of X-band radar sea clutter from the sea surface and sea-surface state in the Uraga Suido Traffic Route, which is used by ships entering and leaving Tokyo Bay, and the nearby Daini Kaiho Sea ... We have made observations of X-band radar sea clutter from the sea surface and sea-surface state in the Uraga Suido Traffic Route, which is used by ships entering and leaving Tokyo Bay, and the nearby Daini Kaiho Sea Fortress. We estimated the distributions of reflected amplitudes due to sea clutter using models that assume Weibull, Log-Weibull, Log-normal, and K-distributions. We then compared the results of estimating these distributions with sea-surface state data to investigate the effects of changes in the sea-surface state on the statistical characteristics of sea clutter. As a result, we showed that observed sub-ranges not containing a target conformed better to the Weibull distribution regardless of Significant Wave Height (SWH). Further, sub-ranges conforming to the Log-Weibull or Log-normal distribution in areas contained a target when the SWH was large, and as SWH decreases, sub-ranges conforming to a Log-normal. We also showed that for observed sub-ranges not containing a target, the shape parameter, c, of both Weibull and Log-Weibull distribution correlated with SWH. The correlation between wave period and shape parameters of Weibull and Log-Weibull distribution showed a weak correlation. 展开更多
关键词 X-band Radar Sea CLUTTER SIGNIFICANT Wave HEIGHT Weibull DISTRIBUTION Log-normal DISTRIBUTION
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Influence of the Fitted Straight Line for Confidence Bands Algorithm in Q-Q Plots
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作者 Sonia Castillo-Gutiérrez María Dolores Estudillo-Martínez Emilio Damián Lozano-Aguilera 《Open Journal of Statistics》 2021年第6期925-930,共6页
Confidence bands in a Normal Q-Q Plot allow us to detect non-normality of a data set rigorously, and in such a way that the conclusion does not depend on the subjectivity of the observer of the graph. In the construct... Confidence bands in a Normal Q-Q Plot allow us to detect non-normality of a data set rigorously, and in such a way that the conclusion does not depend on the subjectivity of the observer of the graph. In the construction of the graph, it is usual to fit a straight line to the plotted points, which serves both to check the hypothesis of normality (linear configuration of the plotted points) and to produce estimates of the parameters of the distribution. We can opt for dif-ferent types of lines. In this paper, we study the influence of five types of fitted straight lines in a Normal Q-Q Plot used for construction the confidence bands based on the exact distribution of the order statistics. 展开更多
关键词 normal Q-Q Plot Confidence bands Fitted Straight Line Goodness of Fit
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The Establishment of Intellectual Property Rights
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作者 邹文静 于正河 《科技信息》 2013年第1期287-289,共3页
A common act taken by every innovation-oriented country is its protection for intellectual property. The main mission for establishing intellectual property rights is to normalize the rights and laws over its entire d... A common act taken by every innovation-oriented country is its protection for intellectual property. The main mission for establishing intellectual property rights is to normalize the rights and laws over its entire domain of jurisdiction. This article introduces the new concept of "intellectual-property-rights-ization", and discusses about the role and importance of this concept; a country that has normalized intellectual property rights are characterized by a people that realize the importance of intellectual property rights, a presence of a rule system that protects one 's intellectual property, an administration that regulates intellectual property rights, a specialization of labor in protecting IPR, and a strong education system. 展开更多
关键词 知识产权 法律 著作权法 作者
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Normal Orthodox Semigroups with Inverse Transversals
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作者 ZHU Feng-lin(Department of Mathematics, University of Science and Technology of China, Hefei 230026, China) 《Chinese Quarterly Journal of Mathematics》 CSCD 2003年第2期198-204,共7页
A normal orthodox semigroup is an orthodox semigroup whose idempotent elements form a normal band.We deal with congruces on a normal orthodox semigroup with an iverse transversal .A structure theorem for such semigrou... A normal orthodox semigroup is an orthodox semigroup whose idempotent elements form a normal band.We deal with congruces on a normal orthodox semigroup with an iverse transversal .A structure theorem for such semigroup is obtained.Munn(1966)gave a fundamental inverse semigroup Following Munn's idea ,we give a fundamental normal orthodox semigroup with an inverse transversal. 展开更多
关键词 逆断面 正规纯正半群 同余 正则带 结构定理 基本纯正半群
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Asymptotic Normality of the Nelson-Aalen and the Kaplan-Meier Estimators in Competing Risks
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作者 Didier Alain Njamen Njomen 《Applied Mathematics》 2019年第7期545-560,共16页
This paper studies the asymptotic normality of the Nelson-Aalen and the Kaplan-Meier estimators in a competing risks context in presence of independent right-censorship. To prove our results, we use Robelledo’s theor... This paper studies the asymptotic normality of the Nelson-Aalen and the Kaplan-Meier estimators in a competing risks context in presence of independent right-censorship. To prove our results, we use Robelledo’s theorem which makes it possible to apply the central limit theorem to certain types of particular martingales. From the results obtained, confidence bounds for the hazard and the survival functions are provided. 展开更多
关键词 Censored Data right-Censoring COUNTING Process Competing Risks Nelson-Aalen and Kaplan-Meier ESTIMATORS Asymptotic Properties of ESTIMATORS CONFIDENCE bands
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基于机载高光谱的长江口北港悬沙浓度反演
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作者 栾奎峰 林丹丹 +3 位作者 李慧 裘诚 潘与佳 高春梅 《海洋测绘》 CSCD 北大核心 2023年第3期68-72,共5页
机载高光谱遥感是悬沙浓度反演的重要方法。针对高光谱悬沙浓度反演中敏感波段和反演方法的确定,以机载高光谱影像为数据源,采用相关性分析法确定单波段模型和双波段组合模型的敏感波段,并基于敏感波段构建单变量回归模型,确定最佳反演... 机载高光谱遥感是悬沙浓度反演的重要方法。针对高光谱悬沙浓度反演中敏感波段和反演方法的确定,以机载高光谱影像为数据源,采用相关性分析法确定单波段模型和双波段组合模型的敏感波段,并基于敏感波段构建单变量回归模型,确定最佳反演模型并获取长江口北港区域的悬沙浓度空间分布特征。结果发现,基于归一化差值指数(NDWI)构建的二次多项式模型为最佳反演模型,精度上优于其他5种常用的反演模型;且长江口北港区域的悬沙浓度与水下地形基本上呈倒数关系。相较于基于多光谱卫星影像进行遥感反演,本文的结果表明高光谱影像的精细化光谱能够更为准确地表达含沙水体的光谱信息变化,在复杂的水环境反演研究中具有重要的应用价值。 展开更多
关键词 机载高光谱 悬沙浓度 双波段组合模型 归一化差值指数 长江口北港
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节制索上右束支起源的特发性室性心律失常的心电图特征及射频消融疗效
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作者 胡志鹏 梁卓 +2 位作者 刘旭 张涛 王云龙 《中国介入心脏病学杂志》 CSCD 2023年第11期862-866,共5页
目的研究右心室节制索(MB)上右束支(RBB)起源的特发性室性心律失常(VAs)的电生理特征及射频消融疗效。方法回顾性分析2019年4月至2022年7月于首都医科大学附属北京安贞医院心律失常中心经电生理检查及射频消融证实起源于右心室MB上RBB... 目的研究右心室节制索(MB)上右束支(RBB)起源的特发性室性心律失常(VAs)的电生理特征及射频消融疗效。方法回顾性分析2019年4月至2022年7月于首都医科大学附属北京安贞医院心律失常中心经电生理检查及射频消融证实起源于右心室MB上RBB的10例特发性VAs患者。通过在MB处行激动及起搏标测,分析其体表心电图特征、电生理特点、成功消融靶点处电位特征并观察分析射频消融的疗效。结果起源于MB上RBB的特发性VAs体表心电图呈典型的左束支传导阻滞(LBBB)图形,电轴左偏,发作VAs时呈现较窄的QRS波,V1、V2导联为rS波,且S波无顿挫,VAs时R波均移行于V4~V6导联,晚于窦性心律,V6导联均有正向R波。在VAs时最早激动位点处均有领先的RBB电位,术中消融领先RBB电位均有效地消除了VAs,消融后6例出现右束支传导阻滞,随访过程中2例恢复。结论MB上RBB的特发性VAs体表心电图表现为较窄的QRS波,典型LBBB,电轴左偏,胸前导联R波移行晚于窦性心律。消融最早激动位点前领先的RBB电位成功消除了VAs。 展开更多
关键词 射频消融 节制索 右束支 室性心律失常
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基于结巴分词的领域自适应分词方法研究 被引量:2
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作者 邢玲 程兵 《计算机仿真》 北大核心 2023年第4期310-316,503,共8页
利用Jieba分词(结巴分词)对中文文本进行分词时,对于领域词组分词效果不是很理想,需要通过加载自定义词典解决这个问题。提出一种领域自适应分词方法,将结巴分词后相邻词语组合为词组,利用标准化点互信息(NPMI)及词频统计两种方法分别... 利用Jieba分词(结巴分词)对中文文本进行分词时,对于领域词组分词效果不是很理想,需要通过加载自定义词典解决这个问题。提出一种领域自适应分词方法,将结巴分词后相邻词语组合为词组,利用标准化点互信息(NPMI)及词频统计两种方法分别计算词组凝聚度,利用左右信息熵计算词组自由度,通过设定凝聚度与自由度阈值识别领域词组,利用文中提出的词性约束规则进一步筛选词组,将得到的词组作为自定义词典加入到结巴分词中,再次对文本进行分词。通过在自己构建的金融和法律领域语料库进行实验,证明了所提算法可以有效发现领域词组,利用该算法进行领域分词时,准确率和召回率高于只利用结巴分词的准确率和召回率。最后提出了一种基于区分不同领域的领域自适应分词算法评价方法。实验结果表明,上述算法能够有效区分不同领域,即可以有效实现领域分词。 展开更多
关键词 结巴分词 领域自适应 标准化点互信息 词频统计 左右信息熵 词性约束
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基于准正则模式的全电介质超材料宽带反射器机理
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作者 蒋乐昕 谢振龙 +2 位作者 郭泽虹 丘伊宁 陈溢杭 《物理学报》 SCIE EI CAS CSCD 北大核心 2023年第20期339-348,共10页
全电介质超材料宽带反射器具备损耗低、反射效率高、结构紧凑等优点,深入理解其反射带的形成机理对超材料结构和性能的优化、以及进一步设计新型光子器件均具有重要意义.本文利用离散的硅纳米柱阵列和硅膜底层连接的硅纳米柱阵列分别构... 全电介质超材料宽带反射器具备损耗低、反射效率高、结构紧凑等优点,深入理解其反射带的形成机理对超材料结构和性能的优化、以及进一步设计新型光子器件均具有重要意义.本文利用离散的硅纳米柱阵列和硅膜底层连接的硅纳米柱阵列分别构造了两个全电介质超材料宽带反射器,通过求解其准正则模式,结合散射矩阵理论拟合出了超材料的反射谱.发现零频准正则模式对拟合准确性有重要影响,并提出了用色散关系分析法准确求解零频准正则模式.进一步用高Q值和低Q值准正则模式分别拟合出共振反射谱和背景反射谱.结果表明,超材料反射器的宽带反射源于低Q值的准正则模式造成的背景反射.本文提出的研究方法可进一步拓展,用于分析Mie共振、准连续域束缚态等共振现象,为超材料光谱特性的解释提供新的思路. 展开更多
关键词 全电介质超材料 宽带反射 准正则模式 散射矩阵
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