By choosing a PVC slice to simulate flexible vegetation, we carried out experiments in an open channel with submerged flexible vegetation. A 3D acoustic Doppler velocimeter （micro ADV） was used to measure local flow...By choosing a PVC slice to simulate flexible vegetation, we carried out experiments in an open channel with submerged flexible vegetation. A 3D acoustic Doppler velocimeter （micro ADV） was used to measure local flow velocities and Reynolds stress. The results show that hydraulic characteristics in non-vegetation and vegetation layers are totally different. In a region above the vegetation, Reynolds stress distribution is linear, and the measured velocity profile is a classical logarithmic one. Based on the concept of new-riverbed, the river compression parameter representing the impact of vegetation on river is given, and a new assumption of mixing length expression is made. The formula for time-averaged velocity derived from the expression requires less parameters and simple calculation, and is useful in applications.展开更多
Laser-induced breakdown spectroscopy （LIBS） was used to decipher the unique multi-elemental characteristics of Juncus effusus L. The spectral fingerprints of Juncus effusus L. were established based on elemental mic...Laser-induced breakdown spectroscopy （LIBS） was used to decipher the unique multi-elemental characteristics of Juncus effusus L. The spectral fingerprints of Juncus effusus L. were established based on elemental microanalysis via LIBS. Microanalysis and multimode sampling methodologies were designed in this study. The relative standard deviation （RSD） approach was performed to optimize the multi-shot measurements. Taking advantage of the capability with no or minimal sample pre-treatment of LIBS, a thermodynamic chart of four elements （Mg, Ca, Ba, and Na） was created from twelve collection regions. The diagram of elemental distribution on a micro-scale was generated to explore the nature of Juncus effusus L. by LIBS. The results demon- strated that LIBS is a promising technique for rapid elemental microanalysis of heterogeneous samples.展开更多
对于频率交叠严重且频率成分接近的多分量信号,常用的短时傅里叶变换(Short Time Fourier Transform,STFT)和S方法(S-Method,SM)频率分辨能力不足,重构精度低.针对该问题,本文结合逆Radon变换提出了基于短时迭代自适应-逆Radon变换(Shor...对于频率交叠严重且频率成分接近的多分量信号,常用的短时傅里叶变换(Short Time Fourier Transform,STFT)和S方法(S-Method,SM)频率分辨能力不足,重构精度低.针对该问题,本文结合逆Radon变换提出了基于短时迭代自适应-逆Radon变换(Short Time Iterative Adaptive Approach-Inverse Radon Transform,STIAA-IRT)的微多普勒特征提取方法.首先采用基于加权迭代自适应的STIAA时频分析方法分析了散射点模型的微多普勒特性,然后利用逆Radon变换分离重构不同散射点的微多普勒分量.该方法在低信噪比、邻近时频分布情况下能获得高分辨的多分量信号的完整微多普勒信息,性能分析显示STIAA-IRT重构精度较高,明显优于STFT-IRT(Short Time Fourier Transform-Inverse Radon Transform)和SM-IRT(S-Method-Inverse Radon Transform)特征提取方法.展开更多
目的探讨经侧裂-岛叶人路显微手术对基底节区高血压脑出血的疗效。方法回顾性分析2010年1月-2013年6月64例基底节高血压脑出血患者临床资料。其中41例行经侧裂-岛叶入路显微手术(A组);另23例行常规骨瓣开颅手术(B组),比较2组治疗效果及...目的探讨经侧裂-岛叶人路显微手术对基底节区高血压脑出血的疗效。方法回顾性分析2010年1月-2013年6月64例基底节高血压脑出血患者临床资料。其中41例行经侧裂-岛叶入路显微手术(A组);另23例行常规骨瓣开颅手术(B组),比较2组治疗效果及近远期预后。结果 A组手术时间(115.35±46.23)min、术后自动睁眼时间(5.22±3.43)h均短于B组(212.43±58.24)min、(8.74±4.51)h(P<0.05)。术后7 d A组GCS评分(11.92±2.73)分高于B组(9.85±2.46)分(P<0.05)。术后48 h行CT复查,A组血肿大部分清除率为80.49%(33/41)优于B组的56.52%(13/23)(P<0.05)。观察组与对照组并发症发生率无明显差异(39.02%vs.47.83%,P>0.05)。术后3个月随访,A组优良率为60.98%(25/41),明显高于B组的34.78%(8/23)(P<0.05)。术后12个月随访,A组优良率为72.50%(29/40),明显高于B组的47.62%(10/21)(P<0.05)。结论经侧裂-岛叶入路显微手术治疗脑出血是一种损伤小、疗效好、并发症少的治疗方法。展开更多
基金supported by the National Natural Science Foundation of China (Nos. 50679061, 50709025,50749031)
文摘By choosing a PVC slice to simulate flexible vegetation, we carried out experiments in an open channel with submerged flexible vegetation. A 3D acoustic Doppler velocimeter （micro ADV） was used to measure local flow velocities and Reynolds stress. The results show that hydraulic characteristics in non-vegetation and vegetation layers are totally different. In a region above the vegetation, Reynolds stress distribution is linear, and the measured velocity profile is a classical logarithmic one. Based on the concept of new-riverbed, the river compression parameter representing the impact of vegetation on river is given, and a new assumption of mixing length expression is made. The formula for time-averaged velocity derived from the expression requires less parameters and simple calculation, and is useful in applications.
基金supported by National Natural Science Foundation of China(No.81303218)Beijing Municipal Government for the University Affiliated with the Party Central CommitteeDoctoral Fund of Ministry of Education of China(No.20130013120006)
文摘Laser-induced breakdown spectroscopy （LIBS） was used to decipher the unique multi-elemental characteristics of Juncus effusus L. The spectral fingerprints of Juncus effusus L. were established based on elemental microanalysis via LIBS. Microanalysis and multimode sampling methodologies were designed in this study. The relative standard deviation （RSD） approach was performed to optimize the multi-shot measurements. Taking advantage of the capability with no or minimal sample pre-treatment of LIBS, a thermodynamic chart of four elements （Mg, Ca, Ba, and Na） was created from twelve collection regions. The diagram of elemental distribution on a micro-scale was generated to explore the nature of Juncus effusus L. by LIBS. The results demon- strated that LIBS is a promising technique for rapid elemental microanalysis of heterogeneous samples.
文摘目的探讨经侧裂-岛叶人路显微手术对基底节区高血压脑出血的疗效。方法回顾性分析2010年1月-2013年6月64例基底节高血压脑出血患者临床资料。其中41例行经侧裂-岛叶入路显微手术(A组);另23例行常规骨瓣开颅手术(B组),比较2组治疗效果及近远期预后。结果 A组手术时间(115.35±46.23)min、术后自动睁眼时间(5.22±3.43)h均短于B组(212.43±58.24)min、(8.74±4.51)h(P<0.05)。术后7 d A组GCS评分(11.92±2.73)分高于B组(9.85±2.46)分(P<0.05)。术后48 h行CT复查,A组血肿大部分清除率为80.49%(33/41)优于B组的56.52%(13/23)(P<0.05)。观察组与对照组并发症发生率无明显差异(39.02%vs.47.83%,P>0.05)。术后3个月随访,A组优良率为60.98%(25/41),明显高于B组的34.78%(8/23)(P<0.05)。术后12个月随访,A组优良率为72.50%(29/40),明显高于B组的47.62%(10/21)(P<0.05)。结论经侧裂-岛叶入路显微手术治疗脑出血是一种损伤小、疗效好、并发症少的治疗方法。
