优缺点

In this paper, a carrier frequency synchronization algorithm based on autocorrelation has been introduced and realized in FPGA firstly, especially the Cordic algorithm and its realization. Secondly, two symbol synchronization algorithm based on crosscorrelation and autocorrelation are introduced and implemented in FPGA, then the comparison between them is made in the view of realization. Besides, the methods of area diplex and pipelining are embodied in implementation scheme of FPGA.

本文首先介绍了一种基于自相关的载波频率同步算法，给出了它的FPGA实现方案，重点讲述了其中用到的Cordic算法及其实现；然后介绍了分别基于互相关和自相关的两种符号同步算法，给出了各自的FPGA实现方案，从实现的角度比较了两种算法的优缺点，并且在FPGA设计中体现了面积复用和流水线操作的设计思想。

This paper reviews several control strategies of the direct current control of the PWM converter s.

总结了PWM 整流器直接电流控制的几种控制策略，分析了其工作原理和优缺点，展望了直接电流控制技术的发展趋势。

Several common description methods for rotational kinematics are discussed in control point, such as direction cosine matrix, Euler angles, quaternions and Rodrigues/Modified-Rodrigues parameters. Transformation relationships, advantages and disadvantages among those methods are discussed.

从控制角度综评方向余弦、欧拉角、四元数和Rodrigues/修正Rodrigues参数几种常用姿态描述动态方程，指出各种方法的优缺点，及相互转化。

The advantage and disadvantage of them,as well as the relationship between them were discussed in this paper.

并对4种方法的优缺点进行评价，讨论它们之间的关系。

Advantageous and disadvantageous of these three models are studied and compared to each other.

我们还就三种模型各自的优缺点和特性进行了比较。

That the use of the system and the advantages and disadvantages

说明了系统的使用方法及优缺点。

However,both of them have disadvantages.

这两种方式都有各自的优缺点。

Based on the review on the gas-particle two-phase models, the merits and drawbacks of various models were compared and analyzed. According to the characteristics of swirl-flow melting furnace, suitable gas turbulence model, gas-particle two-phase flow model and discrete phase model were chosen.

本文在总结气固两相流计算模型的基础上，结合旋风熔融炉内气固两相流的特点，分析对比了各类模型的优缺点，选择了适合于本文所研究的旋风熔融炉的气相湍流模型、气固两相流模型以及颗粒相的运动轨迹模型，并对旋风熔融炉内颗粒的受力进行了分析。

It compared the characteristics of the extracted features based on discriminability, robustness, and efficiency.Explained the strengths and weaknesses of different features.

从特征的可区分性、鲁棒性和提取效率三个方面比较了垃圾图像判别中的主要特征，分析了特征的优缺点。

Indicating the main characteristics of production technology in mail process center. Knowing in detail of the computer model and simulation method of discrete event system; investigation of computer simulation software; comparison and analysis the advantage and disdvantage of the simulation software. Modeling and simulating the package sorting production line in Xinjiang Newspapers and Periodicals Emitting Office and analyzing the simulation result. Modeling and simulating the hanging sorting -production line in Urmqi Mail Processing Center and analyzing the simulationresultProposes a simulation design method for the mail center auto product line, and made a simulation design for package emitting auto product line in Xinjiang Newspapers and Periodicals Emitting Office. Modeling a mathematical model and simulate for the construction of the sorting table of package sorting machine, and proposes a scheme of discriminatingly setting the buffers of sorting table.

本文的主要工作如下：针对邮政业务，特别是邮件处理中心的邮政业务作详细的调查分析，指出邮件处理中心生产工艺的主要特征；通过详细的了解离散事件系统计算机仿真技术的研究方法，并对计算机仿真软件作了周密的调查，借鉴、分析比较其功能特性的优缺点后，根据实际情况选购了本论文所需的仿真软件工具；对报刊发行局包件分拣生产线作计算机建模和仿真，将仿真结果作分析总结；对邮件处理中心转运中心的推推分拣生产线作计算机建模和仿真，得到仿真结果并作总结分析；提出邮件处理中心自动生产线的仿真设计方法，对报刊发行局期刊发行自动化生产线作仿真设计；最后对包件分拣机上包台结构建立数学模型和计算机仿真，提出多级上包台区别设置缓冲区的方案。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。