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MULTI-PARAMETER TIKHONOV REGULARIZATION FOR LINEAR ILL-POSED OPERATOR EQUATIONS

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Journal of Computational Mathematics 2008年第1期26卷 37-55页

作者： Zhongying Chen Yao Lu yuesheng xu Hongqi Yang Department of Scientific Computing and Computer Applications Zhongshan University Guangzhou 510275 China Department of Mathematics Syracuse University Syracuse NY 13244-1150 USA

We consider solving linear ill-posed operator equations. Based on a multi-scale decomposition for the solution space, we propose a multi-parameter regularization for solving the equations. We establish weak and strong convergence theorems for the multi-parameter regularization solution. In particular, based on the eigenfunction decomposition, we develop a posteriori choice strategy for multi-parameters which gives a regularization solution with the optimal error bound. Several practical choices of multi-parameters are proposed. We also present numerical experiments to demonstrate the outperformance of the multiparameter regularization over the single parameter regularization.

关键词： Ill-posed problems Tikhonov regularization Multi-parameter regularization

经皮微创椎弓根钉内固定与传统开放手术在脊椎骨折患者治疗中的对比

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中外医疗 2024年第7期43卷 76-79页

作者：谢国庆刘仲徐跃胜泗洪中信医院骨科江苏宿迁223900

目的分析对比经皮微创椎弓根钉内固定与传统开放手术在脊椎骨折患者治疗中的治疗效果。方法方便选择2021年1月-2023年12月泗洪中信医院收治的84例脊椎骨折患者为研究对象,按随机数表法分为研究组(经皮微创椎弓根钉内固定,42例)和对照组... 详细信息

目的分析对比经皮微创椎弓根钉内固定与传统开放手术在脊椎骨折患者治疗中的治疗效果。方法方便选择2021年1月-2023年12月泗洪中信医院收治的84例脊椎骨折患者为研究对象,按随机数表法分为研究组(经皮微创椎弓根钉内固定,42例)和对照组(传统开放手术,42例)。对比两组临床指标、影像学检查结果、临床评分以及并发症状况。结果研究组的临床指标、Cobb角、疼痛评分、并发症总发生率明显低于对照组,伤椎前缘高度压缩比明显高于对照组,差异有统计学意义(P均<0.05);研究组预后评分为(11.41±1.44)分,明显高于对照组的(10.23±1.46)分,差异有统计学意义(t=3.729,P<0.05)。结论经皮微创椎弓根钉内固定可提高脊椎骨折患者的手术效率,促进骨折早日康复,手术安全性高。

关键词：经皮微创椎弓根钉内固定术脊椎骨折并发症

Effect of Rapid Thermal Process on Oxygen Precipitates in Heavily Sb-Doped Silicon Wafer

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Journal of Rare Earths 2006年第Z1期24卷 104-106页

作者： Sun Shilong Hao Qiuyan Zhao Liwei Teng Xiaoyun Liu Caichi xu yuesheng Institute of Information Functional Materials Hebei University of Technology Tianjin 300130 China Institute of Information Functional Materials Hebei University of Technology Tianjin 300130 China Institute of Information Functional Materials Hebei University of Technology Tianjin 300130 China Institute of Information Functional Materials Hebei University of Technology Tianjin 300130 China Institute of Information Functional Materials Hebei University of Technology Tianjin 300130 China Institute of Information Functional Materials Hebei University of Technology Tianjin 300130 China

Oxygen precipitates in heavily Sb-doped silicon after rapid thermal process (RTP) in Ar ambient were investigated by RTP at high temperature following annealing at 800 ℃ for 4 h and 1000 ℃ for 16 h. RTP temperature and cooling rates were changed from 1200 to 1260 ℃ and from 10 to 100 ℃·s-1, respectively. The experiment results show that high density of oxygen precipitates is observed in heavily Sb-doped wafer. It is found that the oxygen precipitates in heavily Sb-doped silicon are enhanced at high cooling rate.

关键词： oxygen precipitates vacancy RTP, DZ heavily Sb-doped silicon

Growth of Czochralski silicon under magnetic field

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Science China(Technological Sciences) 2004年第3期47卷 281-292页

作者： xu yuesheng LIU Caichi WANG Haiyun ZHANG Weilian YANG Qingxin LI Yangxian REN Binyan LIU Fugui Institute of Information Function Materials Hebei University of Technology Tianjin 300130 China

Growth of Czochralski (CZ) silicon crystals under the magnetic field induced by a cusp-shaped permanent magnet of NdFeB has been investigated. It is found that the mass transport in silicon melt was controlled by its diffusion while the magnetic intensity at the edge of a crucible was over 0.15 T. In comparison with the growth of conventional CZ silicon without magnetic field, the resistivity homogeneity of the CZ silicon under the magnetic field was improved. Furthermore, the Marangoni convection which has a significant influence on the control of oxygen concentration was observed on the surface of silicon melt. It is suggested that the crystal growth mechanism in magnetic field was similar to that in micro-gravity if a critical value was reached, named the growth of equivalent micro-gravity. The relationship of the equivalent micro-gravity and the magnetic intensity was derived as g=(v0/veff)g0. Finally, the orders of the equivalent micro-gravity corresponding to two crucibles with characteristic sizes were calculated.

关键词： Magnetic field equivalent micro-gravity diffusion-controlled mechanism Marangoni convection.

Towards Ultrahigh Capacity and High Cycling Stability Lithium-Conducting Polymer Batteries by In Situ Construction of Nanostructured Porous Cathodes

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CCS Chemistry 2024年第3期6卷 749-760页

作者： Junkai Yang Jixing Yang Yunhua xu yuesheng Li School of Materials Science and Engineering Tianjin Key Laboratory of Composite and Functional MaterialsTianjin UniversityTianjin 300350

Conducting polymers(CPs)have long been studied as cathode materials for lithium-ion batteries,but the low doping level(maximum:30–50%or even lower)and poor cycling stability limit their ***,we have developed a method of nanoporeconfined in situ electropolymerization to prepare nanostructured polythiophene-type porous cathodes,achieving significantly improved doping availability and long cycle *** was verified that the nanosized polymer formed in situ and loose porous structure are conducive to the doping reaction and maintain high electrochemical *** constructed thieno[3,2-b]thiophene(TtTP)/active carbon cathode delivers an ultrahigh reversible capacity of 309.2 mAh g^(−1)(doping level up to 80.9%)along with an ultrahigh energy density of 1252.3 Wh Kg^(−1),and an ultrahigh rate capability(172.4 mAh g^(−1) at 30 A g^(−1)),which far exceed all the CPs and even all the p-type organic cathode materials ***,an excellent long cycle life of 2000 cycles at 5 A g^(−1) is also revealed,which is a new record for CPs-based cathode materials in nonaqueous lithium-ion *** method provides an effective strategy to improve the doping level and cycling stability of CP-based cathode materials.

关键词： organic cathode materials conducting polymers lithium-ion batteries porous carbon in situ electropolymerization

Wavelet Analysis and Applications 2007

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Tree wavelet approximations with applications

丛书名： Applied and Numerical Harmonic Analysis

2007年

作者： Tao Qian Mang I. Vai yuesheng xu

来源：畅想之星图书光盘版（南... 评论

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Science China Mathematics 2005年第5期48卷 680-702页

作者： xu yuesheng & ZOU Qingsong Department of Mathematics, Syracuse University, Syracuse, NY 13244, USA Institute of Mathematics, Academy of Mathematics and System Sciences, Chinese Academy of Sciences, Beijing 100080, China Department of Scientific Computing and Computer Science, Zhongshan University, Guangzhou 510275, China Department of Mathematics Syracuse University Syracuse USA Institute of Mathematics Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing China Department of Scientific Computing and Computer Science Zhongshan University Guangzhou China

We construct a tree wavelet approximation by using a constructive greedy scheme (CGS). We define a function class which contains the functions whose piecewise polynomial approximations generated by the CGS have a prescribed global convergence rate and establish embedding properties of this class. We provide sufficient conditions on a tree index set and on bi-orthogonal wavelet bases which ensure optimal order of convergence for the wavelet approximations encoded on the tree index set using the bi-orthogonal wavelet bases. We then show that if we use the tree index set associated with the partition generated by the CGS to encode a wavelet approximation, it gives optimal order of convergence.

关键词： greedy algorithms tree wavelet approximations Besov spaces.

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基于逆向有限元法的变形机翼鱼骨的变形重构

航空学报 2020年第8期41卷 244-254页

作者：张科袁慎芳任元强徐跃胜南京航空航天大学机械结构力学及控制国家重点实验室结构健康监测及预测研究中心南京210016

变形监测技术能够为自适应变形机翼的变形控制系统提供参考信息,是保证结构安全性以及优化结构的运行性能的重要手段。传统的基于光学成像的变形测量方法已经不能满足自适应智能结构的实时变形监测的要求。由于变形机翼表面受气动载荷影... 详细信息

变形监测技术能够为自适应变形机翼的变形控制系统提供参考信息,是保证结构安全性以及优化结构的运行性能的重要手段。传统的基于光学成像的变形测量方法已经不能满足自适应智能结构的实时变形监测的要求。由于变形机翼表面受气动载荷影响,不便于直接在变形机翼蒙皮表面布置应变传感系统,目前还没有针对鱼骨结构这种真实复杂机翼结构的变形重构研究,大多针对机翼翼型的变形重构研究是将整个机翼简化成简单的翼形板、梁结构。针对上述问题,本文首次以真实复杂变形机翼主承力结构——鱼骨为研究对象,提出了一种基于逆向有限元(iFEM)算法与位移分段叠加思想结合的变形监测方法,根据Mindlin板变形理论建立四节点逆向壳单元,采用应变传感系统测得鱼骨结构表面应变分布作为算法输入,然后基于最小二乘变分方程求解结构应变场和位移场之间的传递函数,重构鱼骨结构的变形形状,为反演机翼翼型的变形形状提供方法。针对真实自适应变形机翼的主要承力构件开展了变形实验,实验结果表明,机翼鱼骨在分别偏转5°、10°、15°的情况下,逆向有限元法能准确重构鱼骨变形形状,验证了基于逆向有限元法的变形重构方法在真实自适应变形机翼结构变形重构研究中的有效性和准确性。

关键词：结构变形监测变形重构逆向有限元算法自适应智能结构变形机翼

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垂直磁场条件下锗熔体粘度的测量

材料导报 2005年第F5期19卷 236-238页

作者：张雯徐岳生河北工业大学材料学院天津300130

设计制作了由永磁材料构成的，能提供均匀磁场的环形磁场。在锗熔体范围内引入此磁场提供的垂直譬场，采用旋转转子法，测定了不同温度不同磁场强度条件下锗熔体的粘度。结果表明，不同的条件下，锗熔体的粘度有不同程度的降低。粘度降... 详细信息

设计制作了由永磁材料构成的，能提供均匀磁场的环形磁场。在锗熔体范围内引入此磁场提供的垂直譬场，采用旋转转子法，测定了不同温度不同磁场强度条件下锗熔体的粘度。结果表明，不同的条件下，锗熔体的粘度有不同程度的降低。粘度降低的原因，可以用磁场对运动带电粒子的作用来解释。

关键词：垂直磁场锗熔体旋转转子法粘度