查询词典 iterative method

At the same time, combining with the actual condition of delivery pipeline of our country and some prevalent leak detection and location methods, this paper raised a method, which is based on wavelet analysis and negative- pressure-wave to detect and locate the leakage. Jobs in the paper are as follows:As affected by gas density, pressure, specific heat and pipe material, the velocity of negative-pressure-wave improved depending on the energy conservation. At one time, taking the affection of velocity of gas flow, the location formula was modified in some degree.When locating the leaks with location formula, the iterative approach algorithm was adopted as a new method to increase the location accuracy level of system.Multi-scale decomposition and reconstruction of wavelet transform is utilized to filter the noise of negative-pressure-wave, which was brought by leakage. With the capacity to detect the signal singularity fast and accurately, wavelet transform was used to catch the break point of pressure signal. The work improved the accuracy of At in location formula, accordingly improved the location accuracy.Wavelet is a suitable tool for signal analysis. The distinct character is that the mother-wavelet is of optional. That means choosing different mother-wavelet will get different analysis result. So we studied how to choose mother-wavelet and its scale for signal singularity detection. The method is to choose a wavelet by regularities of the wavelet and the signal.Finally, a plan, which bases on SCADA system for inspection and detection of natural gas leakage, is proposed in the article.

其中，主要进行了以下几方面的工作：针对泄漏产生的负压波在管道中的传播速度受媒介的密度、压力、比热及材质等因素的影响，而非声波在空气中传播的速度，本文利用能量守恒原理，对其进行了修正；考虑到管内气体流速对压力波速的影响，对原始的负压波定位公式进行了一定程度的改进，并在利用定位公式进行泄漏点定位时采用逐步迭代逼近算法，提高了系统的定位精度；利用小波变换的多分辨率分解和重构技术，对采集到的管道发生泄漏时产生的负压波信号进行了降噪处理；并利用小波变换技术对信号奇异点的快速、准确的识别能力，对经上述消噪后的负压波信号进行了奇异点捕捉，精确捕捉的结果提高了定位公式中上下游站点采集到的负压波奇异点的时间差△t的精度，从而进一步提高了定位的精度；考虑到小波变换是一种基波可变的信号分析工具，也就是说，不同的小波基波对信号分析的结果将有很大差别，这势必影响最终的处理结果，因此，我们又对比分析了本课题中小波基及尺度的选择问题，依据规则性系数相似性原理对母小波的选择进行了探索性研究；最后，还提出了基于SCADA的泄漏检测与定位系统的软件开发构想及系统的嵌入方案。

The examples indicate that the algorithm has strong pertinence and high efficiency, hi the discrete variable optimization, the problem is solved in the relative quotient method On the base of analyzing the relative quotient method, the conjugate gradient direction is used to modify the old search directions, the iterative matrix of the algorithm, and the method to resolve the discrete variable optimization, the relative conjugate difference quotient algorithm is presented.

离散变量优化算法是从相对差商法开始的，在详细分析相对差上法的基础上，用共轭梯度方向修正原有的搜索方向，并对算法的迭代矩阵进行相关的修改，最终形成一种用于求解离散变量优化问题的RCDQ法。

The method based upon semi-infinite slopes is intended to approximate the prescribed transfer function. In order to minimize the error function, the least square method is adopted. The method of correction with term by term is used to avoid the divergent difficulties in iterative design.

本文提出以折线法来构造网络的逼近函数，并利用最小二乘法和逐项修正法相结合的办法来达到最优逼近，然后依据网络综合的理论，用RC网络的综合步骤来计算出实际元件值。

In image processing, method as follows will be introduced in this paper: a method combining image threshold iterative segmentation with threshold interpolation, edge detection operator Sobel and LoG, edge linking method using delation operator based on mathematical morphology, using boundary tracking and projection method in edge distill process. Through this method, measurement of wheelset will be met precision demand.

本文阐明了图像的分通道自动采集过程，以及对采集到的原始图像进行预处理过程，达到图像去噪声的目标，本课题采用了阈值分割中迭代阈值和阈值插值相结合的方法，Sobel算子、LoG算子边缘检测算法，基于数学形态学的膨胀运算子进行边缘断点连接以及目标提取中的投影法和边缘跟踪方法，使得提取轮对图像边缘达到测量精度的要求。

It solves the grid equations with domain decomposing multigrid parallel method and precondithoners as elimination method.From the discussion of the iterative property of Gauss elimination method,it can improve the parallel efficiency by overcoming the obstacle in the information passing.

对网格方程组作多重网格区域分裂并行计算，以消去法为预条件，讨论了Gauss消去法的迭代性质，指出该迭代法有效改善通常迭代在子域信息传递过程中的障碍性问题，提高多重网格区域分裂并行计算效率。

This dissertation firstly introduces the principles of four kinds of simple gridding methods, which are"Linear interpolation based on triangulation","Inverse distance weighted and averaged method","Modified Shepard's method"and"Multiquardirc method". Secondly, it researches the Ordinary Kriging method for geophysical irregular data, which mainly includes the base knowledge of region change and variogram and the principle of Ordinary Kriging method. Thirdly, it researches the Inverse Interpolation for geophysical irregular data, which mainly includes the principle of inverse interpolation and its iterative algorithm, and the principle of Inverse Interpolation to realize the gridding of geophysical data. Finally, it uses these gridding methods to grid theoretical model data of potential field and raw aeromagnetic data, and compares and analyzes the gridding results.

本文首先简单介绍了地球物理不规则分布数据的四种简单网格化方法(即基于三角网的线性插值法、反距离加权平均法、改进的Shepard方法和多元二次函数法)的方法原理；接着，重点研究了地球物理不规则分布数据网格化的普通克里金法，主要研究了区域变化量、变差函数的基础知识和普通克里金法的方法原理；之后，重点研究了地球物理不规则分布数据网格化的反插值法，主要研究了反插值法的方法原理和迭代求解算法，以及反插值法实现地球物理数据网格化的原理；最后，应用这些方法对理论位场模型和实际航磁数据进行了试验、对比和分析。

Based on the isoperimetric graph partitioning method, we propose several practical segmentation algorithms. The first is the iterative two-way cut method which can segment an image into pieces with particular characteristics each other by iteration. The second is simultaneous K-way cut method which divides the image into K parts synchronously. The last is an interactive method separating objects of interest from the background by the user's input specifying the object of interest manually.

基于等周分割方法，我们提出了几种实用的分割算法：第一种是迭代2分方法，它通过迭代的方法将图像分割成各具特征的小区域；第二种是同时直接K分法，同时将图像分割成K个部分；最后一种方法是交互分割法，它依赖人工输入来指定所要分割的感兴趣目标，将图像目标从背景中分离出来。

The paper describes a new iterative decoding algorithm for the product codes, its feedback method is completed by a linear combination of soft output of encoder and the receipt information is different with the traditional turbo iterative decode. When decoder obtains the soft output matrix built -1 and +1, the complexity can be reduced greatly and the performance can be lost utile by reducing the number of candidate code words and omitting the complicated operation of LLR.

针对乘积码提出一种新的迭代解码算法，该算法的反馈方式有别於Turbo码的传统迭代译码，是通过输出软信息与接收软信息进行线性叠加来实现的，此时子译码器的候选码字个数将大为降低，同时译码输出也无须做复杂的LLR计算，直接映射为由-1，+1组成的软输出矩阵，从而在牺牲较小性能的情况下很大程度地降低了译码复杂度。

Second, Unexpectable situation such as bad weather or apparatus problems will cause some other cases, for example, tidal level data cant be measured completely or contains great errors. Aim at these cases, according to multiple harmonic analysis method, this paper presents a new method for the iterative harmonic analysis of tides based on the least square method of continuous function, as well as the condition when this method converges.

第二、针对恶劣天气或仪器等意外情况导致潮位数据缺测或者具有重大误差等情况发生时，根据多次调和分析方法的思想，给出了基于连续函数最小二乘法的潮汐迭代调和分析方法，给出了方法收敛的条件。

3D-CTM (Coupled Thermo-Mechanical Forming Simulation) software for precision forging process of aero-engine blade was developed. The key technologies of 3D coupled rigid-viscoplastic thermo-mechanical FEM simulation of blade forging process were studied systematically. By using the remeshing method of contracting from the boundary to the inner, new mesh system from old distorted mesh system can be obtained. A method of modifying the position of nodes touching on the die according to its original normal was proposed to avoid "dead lock" problem due to uncontinuity of normal of scatted die meshes. The pseudo-static iterative algorithm was used to simplify the coupled thermo-mechanical computation. In particular, formulations to determine relaxation factor β was established for rigid viscoplastic FEM adopting penalty function method, and an improved cubic factor rapid algorithm derived from these formulations was proposed by combining with the advantage of advance and retreat search method.

采用基于边界构形的内缩法，实现了三维畸变网格的重新划分；提出了初矢修正法对触模节点的位置进行修正，解决了由于离散的模具网格的法矢不连续造成的&死锁&问题；采用准静态迭代法简化了速度场和温度场耦合计算过程；特别是针对减速因子β的选取，建立了适用于三维复杂成形过程刚粘塑性罚函数法有限元三次因子法的计算公式，并结合进退搜索法提出了改进的三次因子快速算法，提高了模拟计算效率和稳定性，在此基础之上，开发了面向叶片精锻过程的三维刚粘塑性热力耦合有限元模拟分析系统(3D-CTM)，系统的可靠性得到了圆柱体镦粗的验证。

This one mode pays close attention to network credence foundation of the businessman very much.

这一模式非常关注商人的网络信用基础。

Cell morphology of bacterial ghost of Pasteurella multocida was observed by scanning electron microscopy and inactivation ratio was estimated by CFU analysi.

扫描电镜观察多杀性巴氏杆菌细菌幽灵和菌落形成单位评价遗传灭活率。