一类薛定谔-泊松系统多重解的存在性

研究薛定谔-泊松系统{-Δu+V(x)u+φu=f(u),x∈R^(3),-Δφ=u^(2),x∈R^(3)多重解的存在性,其中位势函数V(x)是可变号的.当f和V满足适当条件时,利用变分法和Morse理论得到了该系统多个非平凡解的存在性.

外部轴向激励作用下螺旋桨桨叶动应变频域变化特性试验研究

为了研究外部轴向激励作用对螺旋桨桨叶动应变频域特性的影响,采用应变片和特制的水下数据采集仪对七叶大侧斜螺旋桨桨叶动应变的频域变化特性进行了试验测量研究。试验结果显示,在非均匀来流条件下,螺旋桨桨叶动应变的频域特性能明显反映出非均匀流场的主角频特征与螺旋桨轴频的耦合振动特性。在螺旋桨桨叶的三个不同径向位置处,桨叶的动应变频域变化特性均能够反映出螺旋桨的轴频及其谐频特征。其中,0.6倍螺旋桨半径位置处的动应变特性最为明显,0.8倍螺旋桨半径位置处次之,0.4倍螺旋桨半径位置处的变化最小;当激励频率fe=42Hz和fe=60Hz的两个外部轴向激励分别作用于螺旋桨-轴系时,螺旋桨桨叶动应变频域均会对其产生一个频率响应,其响应频率与激励频率始终保持一致。

一类带有不定位势Kirchhoff方程多重解的存在性

研究R~N中一类带有不定位势的Kirchhoff方程,其中位势函数是可变号的.利用Morse理论和变分学原理,得到方程多重解的存在性.

A STUDY ON THE MEASURING TECHNIQUES FOR EXCITING FORCE IN CAVITATION TUNNEL

A multi-function sampling system has been set up in Shanghai Ship & Shipping Research Institute (SSSRI) where a test on the fluctuating pressure of two propeller models were carried out. This paper deals with a study on the technical problems concerning the measurement and analysis techniques involved in the test. The sampling and processing procedure of signal is one of the major factors affecting the ac- curacy and stability of the prediction of fluctuating pressure induced by propeller. Integral-peri- od sampling, high enough sampling frequency and suitable resolution must be kept in sampling and processing. The procedure of sampling and processing should be validated by standard signal corresponding to the blade frequency of different orders in comparative tests.