Positive solutions for (n−1,1) three-point boundary value problems with coefficient that changes sign

In this paper, we establish existence results for positive solutions for the (n−1,1) three-point boundary value problems consisting of the equation

     

Twin solutions to singular boundary value problems

In this paper we establish the existence of two nonnegative solutions to singular and singular focal boundary value problems. Our nonlinearity may be singular at , and/or .

     

The Fredholm Alternative for Functional Differential Equations of Mixed Type

We prove a Fredholm alternative theorem for a class of asymptotically hyperbolic linear differential difference equations of mixed type. We also establish the cocycle property and the spectral flow property for such equations, providing an effective means of calculating the Fredholm index. Such systems can arise from equations which describe traveling waves in a spatial lattice.     

交流电桥的示波器测量方法

传统的交流电桥教学采用毫伏表,本文给出了一种采用示波器的电桥教学与测量方法,能更直观展示电桥的幅、相关系,有更好的教学效果。     

Some existence results for a simplified two fluid system in plasma theory

In this paper, we consider a simplified two fluid system in plasma theory. Some multiple existence results for this system are obtained by variational methods and topological degree methods.     

Positive solutions of Neumann problems with singularities

In this paper, we study the existence of positive solutions to second order singular equations with Neumann boundary conditions. The proof of the main result relies on a nonlinear alternative principle of Leray-Schauder, together with a truncation technique.     

一类椭圆型随机偏微分方程弱解的存在性

设$D$是$R^N$ ($N>1$)中有界开集,$(\Omega, {\cal F}, P)$是一个完备的概率空间.该文研究了下列随机边值问题弱解的存在性问题\[\left\{\begin{array}{ll}-{\rm div} A(x,\omega,u, \nabla u)=f(x,\omega, u),\,\, &;(x,\omega)\in D\times \Omega,\\u=0, &;(x,\omega)\in \partial D\times \Omega,\end{array}\right.\]其中, div与 $\nabla $ 表示仅对 $x$求微分. 首先,作者引入了弱解的概念; 然后,作者转化随机问题为高维确定性问题;最后,作者证明了该问题弱解的存在性.     

As(III) Determination in the Presence of Pb(II) by Differential Alternative Pulses Voltammetry

Differential Alternative Pulses Voltammetry (DAPV), introduced by the authors earlier, was applied with HMDE for direct As(III) determination in the presence of Pb(II) in natural water without sample pretreatment. Distinguishable peaks of As(III) and Pb(II) were registered in 1 M HCl supporting electrolyte at a concentration ratio as high as 1 : 6, while complete peak overlapping occurs applying DPP at any concentration ratio at the same experimental conditions. In‐situ As(III) determinations in the presence of Pb(II) in contaminated ground waters in Mexico were performed, using especially designed disposable safe mercury drop electrodes.