青海省黑泉水库混凝土面板坝的工程地质问题与工程处理措施

黑泉混凝土面板坝高 1 2 3.5 0m ,位居中国已建成的混凝土面板坝第四。坝址地形破碎 ,构造发育 ,工程地质条件复杂 ,河床第四纪砂卵砾石层存在不利于坝体稳定和变形的夹层 ,大坝设计采取了一些独具特色的结构措施 ,较好地适应了特殊的地质条件。本文重点分析了大坝的工程地质条件及相应的工程处理措施。     

LC–MS/MS method for the simultaneous determination of ethyl gallate and its major metabolite in rat plasma

A simple, rapid and sensitive liquid chromatography–tandem mass spectroscopy (LC–MS/MS) method was developed and validated for the determination of ethyl gallate, a pharmacologically active constituent isolated from Lagerstroemia speciosa (Linn.) Pers. This method was used to examine the pharmacokinetics of ethyl gallate and its major metabolite gallic acid in rat plasma using propyl gallate as an internal standard. After precipitation of the plasma proteins with acetonitrile, the analytes were separated on a Zorbax SB‐C₁₈ column (3.5 μm, 2.1 × 50 mm) with an isocratic mobile phase consisted of methanol–acetonitrile–10 mM ammonium acetate (10 : 25 : 65, v/v/v) containing 0.1% formic acid at a flow rate of 0.25 mL/min. The Agilent G6410A triple quadrupole LC/MS system was operated under the multiple‐reaction monitoring mode using the electrospray ionization technique in negative mode. The lower limits of quantification of gallic acid and ethyl gallate of the method were 0.5 and 1.0 ng/mL. The intra‐day and inter‐day accuracy and precision of the assay were less than 8.0%. This method has been applied successfully to a pharmacokinetic study involving the intragastric administration of ethyl gallate to rats. Copyright © 2009 John Wiley & Sons, Ltd.     

Dynamic analysis of unstable Hopfield networks

In this paper, the dynamic behaviors of unstable Hopfield neural networks (HNNs) with asymmetric connections are studied. It is found that the solution of the HNN is bounded and the HNN is a dissipative system. In addition, sufficient conditions for the instability of the equilibrium point and the existence of stable limit cycles are proposed. Some numerical simulations are given to illustrate the effectiveness of the proposed results. It is shown that some HNNs exhibit two independent limit cycles or chaotic attractors which are symmetric to each other with respect to the origin.     

A novel bounded 4D chaotic system

This paper presents a novel bounded four-dimensional (4D) chaotic system which can display hyperchaos, chaos, quasiperiodic and periodic behaviors, and may have a unique equilibrium, three equilibria and five equilibria for the different system parameters. Numerical simulation shows that the chaotic attractors of the new system exhibit very strange shapes which are distinctly different from those of the existing chaotic attractors. In addition, we investigate the ultimate bound and positively invariant set for the new system based on the Lyapunov function method, and obtain a hyperelliptic estimate of it for the system with certain parameters.     

电弧放电等离子体诱导激波的计算

基于电弧放电物理过程,分析气动激励机理,建立用于电弧放电等离子体诱导激波数值模拟的爆炸丝传热模型.主要结论有:电弧放电等离子体气动激励的主要机理是热等离子体的热阻塞效应,热电弧放电对于超声速来流而言就像-个具有-定斜坡角度的虚拟突起;理论分析只适用于纵坐标较小的阶段;当传热的功率设为放电功率的10%时,本文所建立的模型能够用于电弧放电等离子体诱导激波的仿真研究;等离子体虚拟斜坡角度及其诱导激波角都随来流总压和速度的增大而减小,随着放电功率的增大而增大,在总压、速度和放电功率较小的阶段这种变化较明显,在总压、速度和放电功率较大的阶段这种变化较缓慢.     

高压剪切作用下三水铝石的结构稳定性

利用旋转式金刚石对顶砧压机(RDAC)结合显微激光拉曼光谱和微区X射线衍射,研究了三水铝石(γ-Al(OH)₃)在高压剪切作用下的结构稳定性。常温加压至1.5 GPa,旋转180°后,γ-Al(OH)₃的结构开始转变。初始样品在高波数段的4个羟基伸缩振动峰(3363、3434、3524和3618 cm^-1)相继消失,出现3303和3560 cm^-12个新峰。低波数段拉曼谱强度明显减弱,无非晶态宽峰;Al-O-Al变形振动双峰(568、539 cm^-1)和Al-O伸缩振动肩峰(321和307cm^-1)分别融合为一个振动峰;4个羟基变形振动峰(1052、1018、981和922 cm^-1)仍然可见。继续加压至3.5 GPa,旋转360°后卸至常压,高波数段新出现的两个羟基伸缩振动峰、原Al-O-Al变形振动峰和Al-O伸缩振动峰仍然可见。对比准静水压条件下γ-Al(OH)₃高压相的拉曼谱和相转变压力(约2.7 GPa),认为常温高压剪切作用下γ-Al(OH)₃脱羟基生成了H₂O和H₃O^-₂。卸压样品微区的X射线衍射谱进一步揭示,在高压剪切作用下,γ-Al(OH)₃的(OH)-Al-(OH)配位八面体骨架被破坏,沿c轴方向原子叠加的层间距缩小,对称性增强。这种不同于准静水压实验的结构改变来自腔体内压力的不均匀分布(0.5~4.5 GPa)。高压剪切作用下,三水铝石的结构稳定性研究对查明板块冷俯冲带中含水矿物的稳定性,推演俯冲板片的物理化学性质以及板块俯冲的速率具有重要意义。     

Generalized Halanay inequalities for dissipativity of Volterra functional differential equations

This paper is concerned with the dissipativity of theoretical solutions to nonlinear Volterra functional differential equations (VFDEs). At first, we give some generalizations of Halanay's inequality which play an important role in study of dissipativity and stability of differential equations. Then, by applying the generalization of Halanay's inequality, the dissipativity results of VFDEs are obtained, which provides unified theoretical foundation for the dissipativity analysis of systems in ordinary differential equations (ODEs), delay differential equations (DDEs), integro-differential equations (IDEs), Volterra delay-integro-differential equations (VDIDEs) and VFDEs of other type which appear in practice.     

求解非线性中立型延迟微分方程一类线性多步方法的收敛性

本文致力于带有Lagrang插值的一类线性多步法求解非线性中立型延迟微分方程的误差分析.证明了一个p′阶的线性多步方法配上一个q阶的Lagrang插值导致一个minf[p′,q 1]阶的E-(或EB-)收敛的非线性中立型延迟微分方程数值方法.     

GLOBAL BEHAVIOR IN A RATIONAL RECURSIVE SEQUENCE

In this paper, we study the global stability, and the periodic character of the rational recursive sequence. We show that the positive equilibrium of the sequence is a global attractor with a basin which depends on certain conditions posed on the coefficients.