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方程φ"+λφ-φ^3=0的L-S方法
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作者 孙业国 《淮南师范学院学报》 2006年第3期35-36,共2页
L-S方法是处理非线性方程的分歧性一个最常用的有效方法,文章用L-S方法处理典型方程$"+!$-$3=0,并求出它在分歧点附近的近似解。
关键词 分歧方程 l-S方法 分歧点
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多体系统动力学微分-代数方程L-稳定方法 被引量:1
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作者 李博文 丁洁玉 李亚男 《应用数学和力学》 CSCD 北大核心 2019年第7期768-779,共12页
针对多体系统动力学微分-代数方程形式,在时间区间上构造L-稳定方法,分别基于等距节点、Chebyshev节点和Legendre节点等非等距节点建立求解格式,依据Ehle定理及猜想,与Padé逼近式对比得到待定矩阵和向量,从而获得L-稳定求解公式,... 针对多体系统动力学微分-代数方程形式,在时间区间上构造L-稳定方法,分别基于等距节点、Chebyshev节点和Legendre节点等非等距节点建立求解格式,依据Ehle定理及猜想,与Padé逼近式对比得到待定矩阵和向量,从而获得L-稳定求解公式,循环求解过程采用Newton迭代法计算.以平面双连杆机械臂系统为例,使用L-稳定方法进行数值仿真,通过改变时间区间节点数和步长对各个指标结果进行比较,并与经典Runge-Kutta法对比.结果表明,该方法具有稳定性好、精度高等优点,适用于长时间情况下的多体系统动力学仿真. 展开更多
关键词 多体系统动力学 l-稳定方法 微分-代数方程 PADÉ逼近 稳定性
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非线性梁振动偏微分方程求解的L-稳定方法
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作者 尹延伟 丁洁玉 徐先宇 《应用数学进展》 2022年第1期33-41,共9页
基于高阶非线性梁振动偏微分方程的一般形式,构造了数值求解的L-稳定格式。首先,选取三角插值基函数,基于插值定理进行空间离散,将带有初边值条件的偏微分方程求解问题转化为微分–代数方程求解。然后在时间区间上构造L-稳定求解格式进... 基于高阶非线性梁振动偏微分方程的一般形式,构造了数值求解的L-稳定格式。首先,选取三角插值基函数,基于插值定理进行空间离散,将带有初边值条件的偏微分方程求解问题转化为微分–代数方程求解。然后在时间区间上构造L-稳定求解格式进行求解。以无轴向运动简支梁在外部激励下的强迫振动方程为例进行数值仿真,对梁的位移轨迹、边界条件及系统能量进行探究,并与龙格–库塔法、微分求积法进行对比,结果表明,L-稳定方法可以在较大步长下满足边界,位移轨迹与模型方程一致,在计算精度和稳定性上都有较好的体现。 展开更多
关键词 梁振动偏微分方程 微分–代数方程 l-稳定方法 非线性 稳定性
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求解非线性椭圆型方程边值问题的分歧方法 被引量:5
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作者 杨忠华 李业忠 《上海师范大学学报(自然科学版)》 2005年第2期17-20,共4页
用对称破缺分歧理论的方法计算了非线性椭圆型方程边值问题的多个解,讨论了非平凡解的各种对称性质,画出了从各个分歧点出发的具有各种对称性质的解.
关键词 非线性椭圆型方程 多解 对称破缺 分歧 l-S方法
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部分岭估计的岭参数确定方法 被引量:3
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作者 刘雁雨 李建伟 刘晓刚 《测绘科学技术学报》 北大核心 2007年第6期413-414,418,共3页
部分岭估计在许多实际的数据处理中是非常有效的,但其岭参数的确定始终是个难点问题。针对这个问题展开了分析,推导了广义交叉检核法、L-曲线法等几种常用的岭参数确定方法在部分岭估计模型下的具体形式。通过对其算例进行计算分析并比... 部分岭估计在许多实际的数据处理中是非常有效的,但其岭参数的确定始终是个难点问题。针对这个问题展开了分析,推导了广义交叉检核法、L-曲线法等几种常用的岭参数确定方法在部分岭估计模型下的具体形式。通过对其算例进行计算分析并比较了各自的优缺点。结果证明,L-曲线法虽然无法定义最优,但是适用性好,稳定性佳,与前两种方法相比有一定优势。 展开更多
关键词 部分岭估计 岭参数 l-曲线方法
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2维薛定谔方程的一种高精度紧致差分格式
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作者 依力米努尔·尼扎木 开依沙尔·热合曼 《江西师范大学学报(自然科学版)》 CAS 北大核心 2024年第2期189-193,共5页
该文对2维薛定谔方程利用局部一维化方法,将2维方程分裂为x、y方向的2个1维薛定谔方程,然后采用6阶紧致格式的离散方法来处理空间变量的2阶导数项,将薛定谔方程转化为一个常微分方程组.通过L-稳定Simpson方法对上述空间离散化得到的常... 该文对2维薛定谔方程利用局部一维化方法,将2维方程分裂为x、y方向的2个1维薛定谔方程,然后采用6阶紧致格式的离散方法来处理空间变量的2阶导数项,将薛定谔方程转化为一个常微分方程组.通过L-稳定Simpson方法对上述空间离散化得到的常微分方程进行离散化,得到了一种具有空间6阶精度和时间3阶精度的格式,并证明了该格式无条件稳定性.并通过数值模拟和对比方法验证了格式的有效性. 展开更多
关键词 2维薛定谔方程 高精度紧致差分格式 局部1维化方法 l-稳定Simpson方法
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求解非对称矩阵特征值问题的广义Lanczos方法的收敛性
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作者 尹宝才 《黑龙江大学自然科学学报》 CAS 1991年第4期26-30,50,共6页
文[1]中,Saad在矩阵只有实单特征值的情况下,证明了广义Lanczos方法是快速收敛的.本文将Saad这一结果推到一般复矩阵的情况.并给出了相应的误差界.
关键词 复矩阵 特征值 广义l-方法 收敛性
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L-S方法在周期系统的应用
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作者 卓相来 宋子兴 《山东矿业学院学报》 CAS 1996年第3期105-110,共6页
本文用分支函数法,通过几个较为一般的实例进一步说明了L-S方法在局部分支理论中的广泛应用,从而将确定局部周期解的个数转化成易懂的代数运算。
关键词 l-S方法 分支函数 周期解 周期系统 分支理论
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N-acetyl-L-cysteine combined with mesalamine in the treatment of ulcerative colitis: Randomized,placebo-controlled pilot study 被引量:2
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作者 Luis G Guijarro Jose Mate +9 位作者 Javier P Gisbert Jose Luis Perez-Calle Ignacio Marín-Jimenez Encarna Arriaza Tomás Olleros Mario Delgado Maria S Castillejo David Prieto-Merino Venancio Gonzalez Lara Amado Salvador Pea 《World Journal of Gastroenterology》 SCIE CAS CSCD 2008年第18期2851-2857,共7页
AIM: To evaluate the effectiveness and safety of oral N-acetyl-L-cysteine (NAC) co-administration with mesalamine in ulcerative colitis (UC) patients. METHODS: Thirty seven patients with mild to moderate UC were rando... AIM: To evaluate the effectiveness and safety of oral N-acetyl-L-cysteine (NAC) co-administration with mesalamine in ulcerative colitis (UC) patients. METHODS: Thirty seven patients with mild to moderate UC were randomized to receive a four-wk course of oral mesalamine (2.4 g/d) plus N-acetyl-L-cysteine (0.8 g/d) (group A) or mesalamine plus placebo (group B). Patients were monitored using the Modified Truelove-Witts Severity Index (MTWSI). The primary endpoint was clinical remission (MTWSI ≤ 2) at 4 wk. Secondary endpoints were clinical response (defined as a reduction from baseline in the MTWSI of ≥ 2 points) and drug safety. The serum TNF-α, interleukin-6, interleukin-8 and MCP-1 were evaluated at baseline and at 4 wk of treatment. RESULTS: Analysis per-protocol criteria showed clinical remission rates of 63% and 50% after 4 wk treatment with mesalamine plus N-acetyl-L-cysteine (group A) and mesalamine plus placebo (group B) respectively (OR = 1.71; 95% CI: 0.46 to 6.36; P = 0.19; NNT = 7.7). Analysis of variance (ANOVA) of data indicated a significant reduction of MTWSI in group A (P = 0.046) with respect to basal condition without significant changes in the group B (P = 0.735) during treatment. Clinical responses were 66% (group A) vs 44% (group B) after 4 wk of treatment (OR = 2.5; 95% CI: 0.64 to 9.65; P = 0.11; NNT = 4.5). Clinical improvement in group A correlated with a decrease of IL-8 and MCP-1. Rates of adverse events did not differ significantly between both groups. CONCLUSION: In group A (oral NAC combined with mesalamine) contrarily to group B (mesalamine alone), the clinical improvement correlates with a decrease of chemokines such as MCP-1 and IL-8. NAC addition not produced any side effects. 展开更多
关键词 Ulcerative colitis INTERLEUKIN MESALAMINE N-ACETYl-l-CYSTEINE
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Activity and Stability of Arginine Deiminase for Producing L-citrulline
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作者 李加友 曹瑜 +2 位作者 刘毅 钱绍松 焦庆才 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2005年第6期841-844,共4页
A novel Enterococcus faecalis strain designated N J402 was found with high activity of arginine deiminase (ADI). The optimum condition for catalytic activity was determined in terms of temperature (about 40℃), th... A novel Enterococcus faecalis strain designated N J402 was found with high activity of arginine deiminase (ADI). The optimum condition for catalytic activity was determined in terms of temperature (about 40℃), thermostability (available 37℃) and pH (6-7). The effects of substrate and product concentration were studied. The effects of various metal ions added in reaction mixtures on the biocatalyst were investigated and ADI of N J402 was found to exhibit Co^2+ dependence, different from previous reports. Surfactant, cetyl trimethyl ammonium bromide, was one of the most important keys for producing L-citrulline. The enzyme in resting cells possessed the quality of high stability for reuse. 展开更多
关键词 l-CITRULLINE l-ARGININE arginine deiminase ACTIVITY OPTIMIZATION
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Weighing Leaves based on Physical Measurements and L-system Simulation
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作者 Xinyuan Gu 《International Journal of Technology Management》 2015年第4期113-115,共3页
In this paper, we revisit foundations of the applications of physical measurement and Lindenmayer system to the modeling of plants. The measurement is proposed to a formal procedure and measuring the mass of leaves on... In this paper, we revisit foundations of the applications of physical measurement and Lindenmayer system to the modeling of plants. The measurement is proposed to a formal procedure and measuring the mass of leaves on a tree, tailored to branching plant structures with Simpson' s rule and Monte Carlo Methods. L-system is possible to visualize mathematical models of biological structures and processes. The formalism is illustrated using theoretical branching systems, and applied to analyze total leaves number as well as total weight of them. 展开更多
关键词 Leaf Mass Physical Measurement l-SYSTEM FRACTAL
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紊流场中固体颗粒运动轨迹的Lagrangian模型 被引量:8
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作者 李嘉 罗麟 +1 位作者 李克锋 张永泽 《水动力学研究与进展(A辑)》 CSCD 北大核心 1997年第1期96-101,共6页
本文用标准稳态K-ε双方程二阶湍流封闭模型模拟流场,在全面考虑固体颗粒受力情况的基础上,用跟踪颗粒运动的Lagrangian方法描述球形固体颗粒运动,数值求解了紊流场和颗粒运动轨迹。数值计算结果与实验结果相比是令人满意的。
关键词 固液两相液 紊流 两相流 l-方法
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Local Bifurcation of a Thin Rectangle Plate with the Friction Support Boundary
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作者 叶敏 张伟亿 《Transactions of Tianjin University》 EI CAS 2002年第2期114-118,共5页
The dynamical equations of a thin rectangle plate subjected to the friction support boundary and its plane force are established in this paper. The local bifurcation of this system is investigated by using L S method... The dynamical equations of a thin rectangle plate subjected to the friction support boundary and its plane force are established in this paper. The local bifurcation of this system is investigated by using L S method and the singularity theory. The Z 2 bifurcation in non degenerate case is discussed. The local bifurcation diagrams of the unfolding parameters and the bifurcation response characters referred to the physical parameters of the system are obtained by numerical simulation. The results of the computer simulation are coincident with the theoretical analysis and experimental results. 展开更多
关键词 thin rectangle plate L S method singularity theory local bifurcation numerical simulation
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横向磁场与机械载荷共同作用下简支条形板的稳定性分析
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作者 刘丽静 《河北科技师范学院学报》 CAS 2010年第1期56-59,共4页
针对横向磁场与机械载荷共同作用下简支条形板的磁弹性动力稳定性方程,利用L-S约化方法得到了系统的分岔方程,研究了当条形板只受到动载荷作用时,系统的分岔行为,并得到了分岔方程的转迁集和相应的分岔图。
关键词 简支条形板 稳定性分析 分岔方程 转迁集 l-S约化方法
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分岔问题F(x,λ)={-x_1x_2-λx_2+(λ_2-λ)x_1+λ~3,-x_2-x_1~2}的数值计算
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作者 徐千里 《益阳师专学报》 2000年第5期1-5,共5页
利用Liapunov -Schmidt (L -S)方法与分幂展开法研究了分岔问题F在平衡点附近解的结构 。
关键词 l-S方法 稳定性 分岔问题 数值计算
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基于3DS MAX脚本的树木生成软件的实现 被引量:6
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作者 李小青 黄心渊 《农业网络信息》 2005年第7期14-17,共4页
使用计算机作为工具来模拟植物生长及其形态的方法,是随着计算机技术的发展而不断进步的。该软件建立在3DSMAX脚本语言基础上,实现了树的创建,这是实现森林虚拟环境的基础。树的整体创建采用了空间L系统方法,利用了3DSMAX中很重要的创... 使用计算机作为工具来模拟植物生长及其形态的方法,是随着计算机技术的发展而不断进步的。该软件建立在3DSMAX脚本语言基础上,实现了树的创建,这是实现森林虚拟环境的基础。树的整体创建采用了空间L系统方法,利用了3DSMAX中很重要的创建对象工具—MESH,并实现摄像机场景动画。 展开更多
关键词 3DS MAX脚本语言 空间l-系统方法 MESH 场景动画
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一类反应扩散方程的分歧分析 被引量:2
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作者 王华涛 《内江师范学院学报》 2009年第12期20-23,共4页
讨论了一类反应扩散方程的分歧(分岔)现象.运用一般线性全连续场谱定理和L-S(李雅普诺夫-施密特)约化方法得到了此方程的一阶近似形式并求出了从平凡解分歧出的非平凡解的具体表达式.最后运用一些经典分歧定理得到了一些重要的分歧结果... 讨论了一类反应扩散方程的分歧(分岔)现象.运用一般线性全连续场谱定理和L-S(李雅普诺夫-施密特)约化方法得到了此方程的一阶近似形式并求出了从平凡解分歧出的非平凡解的具体表达式.最后运用一些经典分歧定理得到了一些重要的分歧结果,给出了分歧图形. 展开更多
关键词 反应扩散 l-S约化方法 谱定理 一阶近似 分歧
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Test on Evaluation Method for Biodegradability of Lubricants 被引量:2
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作者 杨礼河 朱勇 +2 位作者 范国琛 孙玉德 解世文 《Transactions of Tianjin University》 EI CAS 2008年第1期61-65,共5页
Using carbon tetrachloride (CCl4) as extraction agent, the activated sludge from Tianjin Jizhuangzi Sewage Treatment Plant as inoculum, the test study on biodegradability of lubricants was carried out. The test flas... Using carbon tetrachloride (CCl4) as extraction agent, the activated sludge from Tianjin Jizhuangzi Sewage Treatment Plant as inoculum, the test study on biodegradability of lubricants was carried out. The test flasks containing the mineral medium, the test oil and the inoculum were placed in incubation together with flasks containing poisoned blanks for periods of 0 and 21 days, respectively. Flasks containing the reference materials in place of the test oil were run in parallel. At the end of the incubation period, the contents of the flasks were subjected to sonic vibration, and were acidified and extracted by using CCI4. The extracts were then analysed by infra-red (IR) spectrometer to measure the maximum absorption of the C-H stretch of CH2-CH3 band at wavelength of 2 930 cm^-1. The absorption values were used to calculate the residual oil contents of the poisoned and test flasks. Consequently the biodegradability of the test oil was calculated. The test results indicate that the differences in the biodegradability of test materials in different tests are within 5.5%, and consistent with the data described in Coordinating European Council (CEC) L-33- A-93. The biodegradability of lubricants can be evaluated by this method effectively. 展开更多
关键词 BIODEGRADABILITY LUBRICANT evaluating test CEC l-33-A-93
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Analysis of the PBL Model in the Application of Surgical Experiment Teaching
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作者 HU Xiaojian 《International English Education Research》 2016年第5期81-82,共2页
objective: to analyze the application value of the PBL in the surgical experimental teaching mode. Methods: choose between September 2013 and September 2013 128 clinical professional students, average by using the l... objective: to analyze the application value of the PBL in the surgical experimental teaching mode. Methods: choose between September 2013 and September 2013 128 clinical professional students, average by using the lottery will be divided into control group and the team, every 64 students for 1 set, in surgical experimental teaching as a research courses, the teaching methods for the traditional teaching method in the control group, while the team gives PBL teaching mode, the teaching effect of the final will be two groups of students are analyzed and compared. Results: through different teaching methods for teaching, compared with control group, the group at the student's test scores, and the ability to significantly higher, the difference of both P 〈 0.05, there is statistically significant. Conclusion: using PBL teaching mode in the surgical experimental teaching effect is remarkable, can promote the students' comprehensive ability and is worth popularizing application. 展开更多
关键词 PBL pattern Surgical experimental teaching The traditional teaching Application effect
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