In chapter one , we propose a new mixed method called characteristics mixed finite element method for a convection - dominated diffusion problems with small parameter e : we handle the convection part whth backward difference scheme along the characteristics , obtain much smaller time - trunction errors and avoid numerical dispersion on the front of the peak curve of the flow : we use a lowest order mixed finite element method to deal with the diffusion part , so this scheme can approximate the unknow function and its following vector with high accuracy at the same time 第一章中我们对小参数对流占优扩散问题提出了新的数值方法? ?特征混合有限元方法，即对方程的对流部分采用沿特征线的后退差分格式求解，以保证较小的截断误差限并避免了在流动的锋线前沿数值弥散现象的出现；对流动的扩散部分采用最低次混合元方法求解，以保证格式对未知函数及伴随向量的同时高精度逼近。由于该方法中检验函数可取分片常数，此格式在某种意义上具有局部守恒性质。
The paper , too , does with the corresponding argumentation of all kinds of boundary conditions . the above content improves the no preciseness of disposing of the character line method of current water hammer calculation , namely translates " ds / g = + adt / g multiplies the character equation " into " ds / g = ( v + a ) dt / g multiplies the character equation " 而且在上述中改善了当前水击计郑州大学工学硕士论文算的特征线法具体处理中的不严谨性，即改“用ds / g =士adt / g乘以特征方程后进行积分”为“用ds / g二( 。
In the situation of the rarefaction chasing after the shock wave , both the analysis solve and the important relation as to the characteristics of the wave form are obtained in the use of the characteristic line method before the rarefaction catching ip with the shock wave ; after thai , qualitatively , two kinds of wave forms , reflection shock wave and incidence shock wave , or reflection shock wave and incidence rarefaction , may be obtained as well as the corresponding conditions for their occurrence 对稀疏波追赶冲击波的情况，在稀疏波赶上冲击波以前，利用特征线方法，得到了此问题的解析解及有关波形特性的重要关系；在稀疏波赶上冲击波以后，不仅定性地得到二者经过相互作用以后，可能产生的两种不同波形，即反射的冲击波和入射的冲击波或者反射的冲击波和入射的稀疏波，而且给出了产生不同波形所对应的条件。
In the end of this paper , we introduce that in the context of weather radar observations the enhancement of thin - line features in meteorological radar reflectivity images is addressed using a wavelet - based analysis . passing the thin line highlighted image into forecast system to complete the feature identification , we can get basis element for thunderstorm forecasting 本文最后介绍了采用小波变换的方法对滨州雷达资料的反射率图像进行处理，得到特征线增强后的图像，将其输入自动预报系统实现特征识别，可为雷暴预报等提供某些初步识别判据。
