Solitary waves and their bifurcations of KdV like equation with higher order nonlinearity

We investigate the KdV like equation with higher order nonlinearity ut + a(1 +bun)unux + uxxx = 0with n ≥ 1, a, b ∈ R and α≠ 0. The bifurcations and explicit expressions of solitary wave solutions for theequation are discussed by using the bifurcation method and qualitative theory of dynamical systems. Thebifurcation diagrams, existence and number of the solitary waves are given.     

α－萘甲酰呋喃甲酰甲烷的合成及谱学性质的研究

本文用Ｃｌａｉｓｅｎ缩合反应合成了未见文献报道的一种新的β－二酮，α－萘甲酰呋喃甲酰甲烷（α－ＮＦＭ），考察了该化合物的红外光谱、质谱及核磁共振氢谱。确定其存在着互变异构。     

镧系离子与L-羟脯氨酸、DL-瓜氨酸配位作用研究

稀土与体内广泛存在的生物配体氨基酸的配位作用，尤其是三元体系的研究对于阐明稀土元素在体内的存在形态及探索稀土生物效应具有重要意义．羟脯氨酸和瓜氨酸均是人体中存在的重要氨基酸，它们在人体血浆中的浓度与必需的氨基酸相近［‘j．稀土与氨基酸配位作用的研究已有较多报道「’‘，但模拟生理条件下稀土离子与羟脯氨酸、瓜氨酸的二元、三元配合物的PH电位法研究尚未见报道．本文报道在模拟生理条件下（37C，0·15mol／LNaCI）湖系离子（Pm和Lu除外）与上述2种氨基酸的二元及三元配合物PH电位法研究结果．1实验部分1．1试剂和仪…     

基于新型相似日选取和VMD-NGO-BiGRU的短期光伏功率预测

光伏功率预测在现代电力系统调度和运行中起着重要作用.针对光伏发电功率的多变性和复杂性,提出了一种基于新型相似日选取和北方苍鹰算法（Northern Goshawk Optimization, NGO）优化双向门控循环单元（Bidirectional Gated Recurrent Unit, BiGRU）的短期光伏功率预测方法.首先,利用斯皮尔曼相关系数选取主要气象因子,通过变分模态分解（Variational Mode Decomposition, VMD）将原始光伏功率和最大气象因子分解重构为一系列子信号.其次,通过构建新的评价指标筛选出相似日数据集,利用一组BiGRU建立以相似日子信号为网络输入的深度学习模型,并利用NGO对每个BiGRU网络的超参数进行有效优化.最后,对各子信号的预测结果进行综合,得到最终的光伏功率预测值.仿真结果表明,所提混合深度学习方法在预测精度和计算效率方面均优于其他方法.     

二阶三点数值微分公式的外推算法

利用Taylor公式，给出了二阶三点数值微分公式在各点的截断误差的渐近展开式，并利用Richardson外推算法，提高二阶三点数值微分公式的收敛阶数，得到高精度的二阶数值微分公式．     

碳纤维改善水泥石韧性试验研究

针对油田中后期开发面临的固井质量问题，即水泥环脆性破裂问题，对水泥石韧性测定方法进行了讨论，采用水泥试件抗折强度和弹性模量试验以及薄片分析对碳纤维改善水泥石的韧性进行了考察，并分析了碳纤维改善水泥石韧性的机理。结果表明，纤维的加入可以使水泥石的抗折强度提高30％以上；随纤维掺量的增加，水泥石的弹性模量减小，泊松比增加；纤维在水泥石中的分布有效地阻止了裂纹的发展，增强了水泥石的韧性抗断裂能力。对于水泥石的抗折强度存在着最佳纤维长度和纤维掺量，本试验条件下，纤维的最佳长度为700～l400μm，最佳掺量为0．12％～0．19％。     

Gauss-Legendre求积公式的收敛性

1问题现阶段∫abf(x)dx两点、三点Gauss-Legendre求积公式只给出了其求积公式而并没有求积余项,其复化公式也同样如此.但有时在计算过程中往往要用到它们的求积余项及其复化公式高阶收敛的性质,因此有必要计算出它们的求积公式余项,并证明较其他形式复化公式而言复化Gauss-Lege     

Research on Flax Fiber Reinforced Polylactide Environmental Friendly Composite

Biodegradable polylactide acid （PLA） resin can be combined with flax fibers to produce biodegradable composite materials. In our study, commercial PLA fibers were mixed with flax fibers by a non-woven method so as to make non- woven pre-forms, which can be generated into flax fiber reinforced PLA environmental friendly composites by heat pressing technology. The tensile, flexural and impact properties are tested in order to evaluate the basic physical properties of the composites, and the influenced factors listed as making technology of the pre-forms, weight ratio of flax fibers and heat pressing technology are discussed and optimized, which can be described as weight ratio of flax fibers and PLA fibers is 50/50, heating temperature, time and pressure are respectively 195℃, 20 rain and 12.5 Mpa. Preliminary results show that mechanical properties of the flax/PLA composites are quite promising compared with flax/PP composites in coclrnon commercial automotive use. Scanning electron microscope （SEM） is used to analyze the tensile specimen fracture surfaces, which shows voids and gaps occurring between flax fibers and PLA matrix and sign of fiber pull.out, the strength of flax/PLA interface can be further improved.     

Analysis of secondary electron emission using the fractal method

Based on the rough surface topography with fractal parameters and the Monte–Carlo simulation method for secondary electron emission properties, we analyze the secondary electron yield(SEY) of a metal with rough surface topography. The results show that when the characteristic length scale of the surface, G, is larger than 1 × 10^-7, the surface roughness increases with the increasing fractal dimension D. When the surface roughness becomes larger, it is difficult for entered electrons to escape surface. As a result, more electrons are collected and then SEY decreases. When G is less than 1 × 10^-7,the effect of the surface topography can be ignored, and the SEY almost has no change as the dimension D increases. Then,the multipactor thresholds of a C-band rectangular impedance transfer and an ultrahigh-frequency-band coaxial impedance transfer are predicted by the relationship between the SEY and the fractal parameters. It is verified that for practical microwave devices, the larger the parameter G is, the higher the multipactor threshold is. Also, the larger the value of D,the higher the multipactor threshold.     

老年慢性心力衰竭患者血清D-二聚体水平与心力衰竭的相关性分析

老年慢性心力衰竭患者血清D-二聚体水平(D-dimer)与心力衰竭的相关性分析。以2018年4月至2019年7月为时间段,选择兰州市第二人民医院收治的100例老年慢性心力衰竭患者,入院次日清晨,空腹状态下,采集4ml静脉血,采用酶联免疫吸附法(ELISA)检测D-dimer水平,且根据检测结果分成两组,D-dimer≥0.45 mg/L设为D-dimer升高组,<0.45 mg/L则设为D-dimer正常组,另外,采用电化学发光法,检测患者氨基末端B型脑钠肽前体(NT-ProBNP)并且对比观察。(1)根据NYHA分级,Ⅳ级组D-dimer、NT-proBNP水平比Ⅱ级组、Ⅲ级组高,Ⅲ级组高于Ⅱ级组,差异有统计学意义(P<0.05);Ⅱ级组LVEF水平高于Ⅲ级组、Ⅳ级组,差异有统计学意义(P<0.05)。(2)相关性分析,老年慢性心力衰竭患者的血清D-dimer与NT-ProBNP水平之间存在正相关关系。(3)D-dimer正常组心血管事件发生率低于D-dimer升高组,数据分析,差异有统计学意义(P<0.05)。老年慢性心力衰竭患者根据血清D-dimer,可判...