离散

Many new detection techniques are proposed, that include: To overcome the faults of cross-terms and short unambiguity range for the common Wigner-Ville Distribution , short-time Fourier transform and Gabor transform are applied to SAR moving target detection. To improve the detection performance of WVD in noise environment, a new technique based on the Cross-WVD is proposed. The application of fractional Fourier transform to chirp signal detection is analyzed and extended to SAR moving target detection. To eliminate the restriction of chirp-Fourier transform, a new modified definition is proposed and applied to SAR moving target detection. To detect multiple moving targets whose scattering intensities are different heavily, the CLEAN technique is combined with the above techniques and the ideal detection performance is achieved. At last, the whole dissertation is concluded.

具体的研究成果如下：针对常用的Wigner-Ville分布在多目标情况下存在交叉项，并且多普勒不模糊范围小的缺点，提出将短时Fourier变换和Gabor变换应用于SAR运动目标检测，分析了其优势所在；为进一步提高Wigner-Ville分布低信噪比条件下的信号检测能力，提出基于互Wigner-Ville分布的运动目标检测方法；分析了分数阶Fourier变换在线性调频信号检测中的应用，提出基于分数阶Fourier变换的运动目标检测算法；对离散Chirp-Fourier变换的定义进行了修正，提出修正的离散Chirp-Fourier变换，克服了限制其应用的约束条件，并用于SAR运动目标检测当中；强度相差较大的多运动目标检测历来是机载SAR技术的一个重点和难点，我们将CLEAN思想融入上述多种算法当中，良好地解决了该问题。

The unfeasibility of discrete event driven simulation for high-speed network is discussed; two simulation algorithm based on time driven simulation are given, one of which is as precise as that based on discrete event simulation, but is faster, and the other gets less precision, but is much faster than the former. Comparing with the algorithm based on time driven fluid simulation, both of the proposed algorithms support the succeeding simulation for high-level protocol.

其中一种算法在精度上与离散事件驱动仿真算法一致，但仿真速度明显加快，另一种算法存在一定的仿真误差，但仿真速度要高得多；与时间驱动的流体仿真相比，这两种方法都是针对离散系统的仿真，能提供对上层协议仿真的支持。

In the following chapters, a set of three-dimensional mathematical models involving the heat transfer of the coolant turbulent flow and heat conduction coupling, which is applicable in engineering, was established according to currency N-S control equation, the SIMPLER algorithm in an unstaggered grid system, SMART scheme and k- e turbulence model are used in the flowfield ; The method of whole-field dispersed and solved are appled in the temperature field.

流场计算中，采用同位网格上的SIMPLER算法和低雷诺数κ-ε湍流模型，对流扩散项采用SMART格式离散；温度场计算中采用整场离散，整场求解。

The time interval between two discrete instants is taken to be sufficiently short so that the data for the time between these discrete instants can be approximated by simple interpolation.

两个离散时刻之间的时间间隔应取得足够短，时刻之间的时间间隔应取得足够短，以使这些离散时刻之间的数据可以用简单的插值法来近似。

The thesis adduces a discrete adaptive sliding mode algorithm for nonlinear discrete uncertain systems, and use adaptive laws to estimate uncertainty of the algorithm. So it largely reduces the priori information of the systems and become a simple easy method.

本文针对非线性离散不确定系统的变结构控制，提出了一种离散自适应滑模控制方法，利用自适应率对算法的不确定部分进行了估计，从而减少了先验知识，设计简单，容易实现。

Discrete sliding mode theory has been applied to electrostatic levitation system in which general discrete state space expressions with parameter variation have been set up based on gyro rotor electrostatic force equation and other annuluses including high-voltage amplifier, position sensor and time delay.

本文将离散滑模控制理论应用于静电陀螺悬浮系统，根据陀螺转子静电力方程以及各环节特性(包括高压放大器、测量环节和数字控制器的滞后环节)，建立考虑系统参数变化的广义被控对象离散状态空间表达式。

The nonlinear mechanical model of contact between soil particles was established based on the effects of liquid bridges on mechanical microstructure of soil and the basic Distinct Element Method theory. The dynamic behaviors of dry soil ahead of the bulldozing plate with different cutting angles were simulated by DEM.

根据液桥对土壤微观力学结构的影响，在传统离散单元法理论的基础上，建立了土壤颗粒接触非线性力学模型，并对不同切土角推土板前端干土壤的动态行为进行了离散元模拟。

Then FFT based DCT can be used to compute substrate impedance quickly. Once the DCT has been computed, it can be stored as a DCT matrix, and need not be recomputed for different substrate port configurations.

本论文把子端口之间的阻抗表示成二维离散余弦变换的形式，用基于快速富利叶变换的离散余弦变换快速地计算。

At first, setting up the arith relation between the signal input and the signal output of the generalized multi-carrier system of the Discrete Fourier Test spread-spectrum; then setting equilibria parameters of the frequency field equilibria subcarrier of the generalized multi-carrier system of the DFT spread-spectrum according to channel frequency response, channel noise variance and equilibria method; then calculating average power of useful signal, interferential average power between signals as well as noise variance of the generalized multi-carrier system receiving terminal of the DFT spread-spectrum according to the arith relation as well as the frequency field equilibria parameter, and recomputing available signal information noise ratio, so as to calculate the available signal information noise ratio of the generalized multi-carrier transmission system accurately, the method for estimating the available signal information noise ratio can be used for link self-adapting transmission solution of the generalized multi-carrier system based on Discrete Fourier Test spread-spectrum and radio material management.

一种DFT扩频的广义多载波系统的SINR估计方法，其通过首先建立所述离散傅立叶变换扩频的广义多载波传输系统的信号输入输出之间的数学关系，然后根据信道频率响应、信道噪声方差和均衡方法，设定所述DFT扩频的广义多载波传输系统的频域均衡子载波的均衡系数，再根据所述数学关系及所述频域均衡系数分别计算所述DFT扩频的广义多载波传输系统接收端有用信号的平均功率、信号间干扰的平均功率以及噪声方差，再计算有效信干噪比，如此以实现对广义多载波传输系统的有效信干噪比的准确计算，该有效信干噪比估计方法可用于基于离散傅立叶变换扩频的广义多载波传输系统的链路自适应传输方案和无线资源管理方面。

Traditionally, a surface is usually scatted in an array of 3D data points which are topologically connected by rows and columns to form a rectangular mesh. This method can't meet the requirement of description and measurement for some complex surfaces. On the basis of tracing border points, a new method is proposed to deliver 3D data points of surfaces, which are topologically constructed with optimum rectangular and triangular mesh. In order to measure surface efficiently and safely with NC machine, an optimization of measurement paths is proposed to avoid interference between the measuring tool and the surface with holes. The curve design is the basis of surface modeling.

数控测量技术的发展为测量自动化、集成化、智能化提供了可能，而对于复杂曲面的自动测量规划则是测量技术中的难点问题，平行截面等数目测点分布和四边拓扑测点分布规划方法，不论在测点分布的合理性上还是在网格结构的优化方面，均难以满足形状或边界较复杂曲面的离散化描述和曲面造型的要求，为了实现任意拓扑曲面的自动测量，本文对复杂曲面的合理离散化描述和自动测量问题进行了研究，提出了基于边界跟踪、优化网格的测点自动分布规划和四边、三角混合网格的生成方法：同时对具有孔洞或测量干涉凸台等非完整曲面的测量路径优化问题进行了研究，提出了路径优化方法。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。