针对现有SMTP(simple mail transfer protocol)中接收方被动接收信息的缺点,设计一种新型反垃圾邮件系统。该系统通过设计改进型DMTP(differentiated mail transfer protocol),减少不必要的网络流量;通过引入云计算机制,减小传统反垃圾邮件系统负荷,从而降低用户时间消耗。研究结果表明:与现有邮件系统相比,该系统的用户处理时间、网络流量、垃圾邮件发送方获益均降低。
In Fourier transform profilometry (FTP), we must restrain spectrum overlapping caused by the nonlinearity of the charge coupled device (CCD) and increase the measurement accuracy of the object shape. Firstly, the causes of producing higher-order spectrum components and inducing spectrum overlapping are analysed theoretically, and a simple physical explanation and analytical deduction are given. Secondly, aiming to suppress spectrum overlapping and improve measurement accuracy, the influence of spatial carrier frequency of projection grating on them is analysed. A method of increasing the spatial carrier frequency of projection grating to restrain or reduce the spectrum overlapping significantly is proposed. We then analyze the mechanism of how the spectrum overlapping is reduced. Finally, the simulation results and experimental measurements verify the correction of the proposed theory and method.
