With high - speed development of digital technology , especially the increasing use of digital computing and signal processing technology in applications such as medical imaging , instrumentation and telecommunications , it is becoming common to deal with analog signal with digital circuits 由于数字电子技术的迅速发展，尤其是数字计算和信号处理技术在医疗成像、仪器仪表、通讯等领域的广泛应用，用数字电路处理模拟信号的情况日益普遍。
Then we come to conclusions : ( 1 ) in the bull market , the firms with best earning character can have highest p / e ratio , then follow the ordinary firms , while the firms with worst earning character is on the floor , which means the earning character is related to the yield of stocks ( 2 )以预估盈余数字计算的市盈率做为选股指标时，其合理性及精确性都是较历史盈余的市盈率为高，具有较高的利用价值，说明当期的盈余与当期的股价具有显著相关。
This dissertation first discusses the two - dimension interpolation algorithm and coordinate rotation digital computer algorithm involved in the process of designing system . then the paper particularly probes into the research and development of b - mode digital scan converter , m - mode digital scan converter and graphic circuitry in the digital scan conversion system 本文首先对系统设计过程中引入的二维线性插值算法和坐标旋转数字计算算法进行了讨论，然后着重论述了数字扫描变换系统中的b型数字扫描变换器、 m型数字扫描变换器和图形界面电路的原理、设计与实现。
Introducing the theory and application of boundary element method on the sound radiation , giving the process of solving vibration noise radiation problem using boundary element analysis software ; presenting the coupling theory and the combination analysis of finite element method and boundary element method , and doing relevant analysis based on close drum shell ; programming the noise data simulation program using the numerical calculation software , simulating the acoustic and pressure data of a key point in the transient response acoustic field of the close drum shell , realizing the audibility of the noise , using the virtual reality tools to simulate the vibration noise of the drum shell ; combining the finite element method and boundary element method to analyze the vibration noise radiation of some gear box , and completing the whole simulation process of the vibration noise of the gear box 综合介绍了边界元法在声辐射问题上的理论及应用；并给出了运用边界元法分析软件求解振动声辐射问题的过程。阐述了有限元法和边界元法的耦合理论及组合分析方法，并以封闭鼓形薄壳为分析对象进行了相应的分析。利用数字计算软件编制了噪声数据模拟程序，并模拟了通过组合方法分析封闭鼓形薄壳瞬态响应声场而获得一关键点的声压数据，实现声音的可听化，随后通过虚拟现实工具实现了该情形下椭球壳振动噪声的虚拟仿真。
