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Micro-crack detection of nonlinear Lamb wave propagation in three-dimensional plates with mixed-frequency excitation

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Chinese Physics B 2020年第1期29卷 336-345页

作者： Wei-guang Zhu Yi-Feng li li-qiang guan Xi-li Wan Hui-Yang Yu Xiao-Zhou liu College of Computer Science and Technology Nanjing Tech UniversityNanjing 211800China Key Laboratory of Modern Acoustics Ministry of EducationNanjing UniversityNanjing 210093China Key Laboratory of Modern Acoustics Ministry of EducationInstitute of Acoustics and School of PhysicsNanjing UniversityNanjing 210093China

We propose a nonlinear ultrasonic technique by using the mixed-frequency signals excited Lamb waves to conduct micro-crack detection in thin plate *** models of three-dimensional(3D)aluminum plates and composite laminates are established by ABAQUS software,where the aluminum plate contains buried crack and composite laminates comprises cohesive element whose thickness is zero to simulate delamination *** interactions between the S0 mode Lamb wave and the buried micro-cracks of various dimensions are simulated by using the finite element *** frequency spectrum analysis is applied to the received time domain signal and fundamental frequency amplitudes,and sum and difference frequencies are extracted and *** results indicate that nonlinear Lamb waves have different sensitivities to various crack *** is a positive correlation among crack length,height,and sum and difference frequency amplitudes for an aluminum plate,with both amplitudes decreasing as crack thickness increased,i.e.,nonlinear effect weakens as the micro-crack becomes *** amplitudes of sum and difference frequency are positively correlated with the length and width of the zero-thickness cohesive element in the composite ***,amplitude ratio change is investigated and it can be used as an effective tool to detect inner defects in thin 3D plates.

关键词： nonlinear Lamb wave mixed-frequency micro-cracks amplitude ratio

Prognostic values of serum cystatin C and β2 microglobulin, urinary β2 microglobulin and N-acetyl-β-D-glucosaminidase in early acute renal failure after liver transplantation

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Chinese Medical Journal 2008年第14期121卷 1251-1256页

作者： HEI Zi-qing li Xiao-yun SHEN Ning PANG Hong-yu ZHOU Shao-li guan Jian-qiang Department of Anesthesiology Third Affiliated Hospital Sun Yat-sen University Guangzhou Guangdong 510630 China

Background Acute renal failure （ARF） after liver transplantation is associated with high mortality and morbidity. Early therapeutic or preventive intervention is hampered by the lack of early effective prognostic factors. Recent studies indicated that serum levels of cystatin C and β2-microglobulin （β2 MG） as well as urinary β2 MG and N-acetyI-β-D- glucosaminidase （NAG） would increase in patients with early and mild renal impairment. In this study, these factors were detected during the different stages in patients who accepted orthotopic liver transplantation （OLT）, and their feasibilities to predict early ARF after OLT were also analyzed. Methods Sixty patients with normal blood urea nitrogen （BUN） and serum creatinine （SCr） who received modified piggyback liver transplantation without veno-venous bypass were prospectively studied. Blood samples were drawn from patients for the determination of serum β2 MG（n=60）, SCr （n=60） and serum Cystatin C （n=39） at following 5 intervals： before operation （TO）, 20 minutes before anhepatic phase （T1）, 25 minutes in anhepatic （T2）, 60 minutes after reperfusion （T3） and at the end of operation（T4）. Urinary B2 MG （n=60） and NAG （n=60） were also examined at following 3 intervals： before operation （TO）, 60 minutes after reperfusion （T3） and at the end of operation （T4）. According to the Rimola A criteria of ARF in 24 hours after operation, all the patients were divided into two groups： ARF group and non-ARF group. The data were statistically analyzed to evaluate the feasibiliy of regarding these factors as prognostic factors for early ARF after liver transplantation in patients with normal SCr and BUN before operation. Results Ten of sixty cases showed ARF（16.7%）. The Logistic regression analysis showed that the levels of serum and urinary β2 MG as well as serum cystatin C before operation were correlated with early ARF after liver transplantation （P 〈0.05）, while only serum levels of cystatin C and Cr at the end of operation c

关键词： liver transplantation acute renal failure cystatin C β2-microglobulin

Emerging progress: photochemical transformation of nitroso compounds

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Science China Chemistry 2025年第1期68卷 118-133页

作者： Ze-Le Chen qiang-qiang li Armido Studer Jun Xuan Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials School of Chemistry & Chemical Engineering Anhui University Organisch-Chemisches Institut Universitat Münster

Nitroso compounds have emerged as highly valuable reaction partners or reagents in organic synthesis due to their rich *** versatile profile of these compounds allows them to function as electrophiles, nucleophiles, diradicals, and radical acceptors in diverse transformations. In recent years, notable progress has been made in harnessing photochemical reactions with nitroso compounds to prepare N,O-containing structures using mild and eco-friendly conditions. Various nitroso compounds like nitrosoarenes, acyloxy nitroso compounds, N-nitrosoamines and nitrites have received significant attention for their ability to introduce NO moieties into complex molecules that are otherwise difficult to access. In this review, we provide an overview of the recent advancements in the visible light-induced conversion of nitroso compounds, with particular emphasis on their role as bifunctional reagents and acceptors of radicals, carbenes and nitrenes.

关键词： nitroso compounds photochemistry radical reaction carbene transformation nitrosoarenes

Recent development in electrode design for wide-temperature supercapacitors

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Science China Chemistry 2025年第1期68卷 96-117页

作者： Jianhong liu qiang Zhou Yuxiao lin Xinsheng Zhao guangmin Zhou Xiaoxiao li School of Physics and Electronic Engineering Jiangsu Normal University Tsinghua-Berkeley Shenzhen Institute & Tsinghua Shenzhen International Graduate School Tsinghua University

An ever-increasing market demand has stimulated the soaring enthusiasm of researchers to develop wide-temperature supercapacitors(SCs). The active electrode is one of the most important parts of SC, which is directly related to the energy density,power transmission and long-term cyclability of the device in the wide-temperature environment. Compared with the SC electrodes aimed for room-temperature application, the SC electrodes for operating at wide-temperature scene often face greater challenges. In this review, the main challenges of SC electrodes under various temperature conditions, including low, high and cross-fade temperatures, are summarized. The relevant performance decay and failure mechanisms of wide-temperature SC electrodes are analyzed. In addition, this review deals with the recent studies and developments in robust wide-temperature SC electrodes with respect to the rational design of electrode structures and the exploitation of advanced active materials. Finally, the future directions for exploring reliable wide-temperature SCs are also proposed.

关键词： supercapacitor wide-temperature electrode design active materials

Investigation of bubbles escape behavior from low basicity mold flux for high-Mn high-Al steels using 3D X-ray microscope

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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 102-110页

作者： qiang liu Xiang li Shen Du Ming Gao Yanbin Yin Jiongming Zhang State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

During the continuous casting process of high-Mn high-Al steels,various types of gases such as Ar need to escape through the top of the *** which,the behavior of bubbles traversing the liquid slag serves as a restrictive link,closely associated with viscosity and the thickness of liquid *** contrast to two-dimensional surface observation,three-dimensional(3D)analysis method can offer a more intuitive,accurate,and comprehensive ***,this study employs a 3D X-ray microscope(3D-XRM)to obtained spatial distribution and 3D morphological characteristics of residual bubbles in mold flux under different basicity of liquid slag,different temperatures,and different holding *** results indicate that as basicity of slag increases from 0.52 to 1.03,temperature increases from 1423 to 1573 K,the viscosity of slag decreases,the floating rate of bubbles *** addition,when holding time increases from 10 to 30 s,the bubbles floating distance increases,and the volume fraction and average equivalent sphere diameter of the bubbles solidified in the mold flux gradually *** one word,increasing the basicity,temperature,and holding time leading to an increase in the removal rate of bubbles especially for the *** findings of bubbles escape behavior provide valuable insights into optimizing low basicity mold flux for high-Mn high-Al steels.

关键词： mold flux low basicity bubbles three-dimensional X-ray microscope viscosity

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改进的多模式脑肿瘤图像混合分割算法

信号处理 2018年第3期34卷 340-346页

作者：童云飞李锵关欣天津大学微电子学院天津300072

脑肿瘤是一种高危疾病,在治疗过程中,任何有关位置和大小的信息都至关重要。为了有效检测和诊断脑肿瘤,针对多模式MRI脑肿瘤图像:FLAIR、T2和T1C,本文提出一种改进的多模式脑肿瘤图像混合分割算法。首先对三种模式的MRI图像分别进行中... 详细信息

脑肿瘤是一种高危疾病,在治疗过程中,任何有关位置和大小的信息都至关重要。为了有效检测和诊断脑肿瘤,针对多模式MRI脑肿瘤图像:FLAIR、T2和T1C,本文提出一种改进的多模式脑肿瘤图像混合分割算法。首先对三种模式的MRI图像分别进行中值滤波和快速模糊C均值聚类,之后将图像灰度值按照线性比例FLAIR∶T2∶T1C=5∶4∶1融合得到预处理图像。之后使用快速模糊C均值算法和自动阈值对预处理图像进行聚类分割,得到脑肿瘤的欠分割图像,最后,使用混合水平集算法对欠分割图像进行分割得到脑肿瘤分割图像。分割的脑肿瘤图像与金标准对比,平均Dice达到0.90;与同类算法对比,经本文算法得到的Dice最佳,稳定性好,实时性高,能够满足医学临床需要。

关键词：脑肿瘤多模式快速模糊C均值混合水平集

耦合Gross-Pitaevskii方程的变分原理

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西北师范大学学报（自然科学版） 2009年第5期45卷 44-47页

作者：李冠强彭娉陕西科技大学理学院陕西西安710021

运用半反推方法,首次对耦合Gross-Pitaevskii方程进行变分分析,建立了一个简单的变分公式,其耦合项来源于不同分量之间的交叉相互作用.该公式为通过变分迭代寻求两分量玻色凝聚体中新型孤立波解提供了一个理论依据.

关键词：耦合Gross—Pitaevskii方程变分原理半反推法

Effects of the extrusion parameters on microstructure,texture and room temperature mechanical properties of extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy

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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 136-146页

作者： Chenjin Zhang guangyu Yang Lei Xiao Zhiyong Kan Jing Guo qiang li Wanqi Jie State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China College of Materials Science and Engineering Fuzhou UniversityFuzhou 350108China College of Chemistry and Environmental Science Qujing Normal UniversityQujing 655011China

Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusion speeds(3 and 6 mm/s).The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy,and the second phase showed streamline distribution along the extrusion direction(ED).With extrusion temperature increased from 260 to 320℃,the microstructure,texture,and mechanical properties of alloys changed *** dynamic recrystallization(DRX)degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1,and the strength gradually decreased but elongation(EL)*** the extrusion speed increased from 3 to 6 mm/s,the grain sizes and DRX degree increased significantly,and the samples presented the typical-rare-earth(RE)*** alloy extruded at 260℃ with extrusion ratio of 10:1 and extrusion speed of 3 mm/s showed the tensile yield strength(TYS)of 213 MPa and EL of 30.6%.After quantitatively analyzing the contribution of strengthening mechanisms,it was found that the grain boundary strengthening and dislocation strengthening played major roles among strengthening *** results provide some guidelines for enlarging the industrial application of extruded Mg-RE alloy.

关键词： Mg-rare earth alloys extrusion temperature extrusion ratio extrusion speed strengthening mechanisms

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90°视向角口腔内窥镜光学系统设计

光子学报 2009年第6期38卷 1482-1485页

作者：赵秋玲王霞关立强青岛科技大学数理学院光电子科学与技术研究所山东青岛266042

基于实际应用设计了一个90°视向角的光学系统,可用于1/4″CCD口腔内窥镜成像.系统具有62°视场角,孔径为F/7,各视场的光学传递函数在80lp/mm处取值良好、景深大、像面照度均匀,整个系统的最大镜头口径小于4.6mm.

关键词：口腔内窥镜 CCD 视向角