可变因素

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 three-phase full-wave rectifier charging system is composed of 3 silicon-controlled rectifiers and 3 diodes, and a variable resistor is used to adjust the trigger level such that the power factor of generator can be raised, the current harmonic content can be reduced, and the operational efficiency of generator can be improved.

本研究之整流充电系统，为利用三颗矽控整流器和三颗二极体组成的三相全波矽控整流充电系统，利用VR可变电阻调整元件来做触发机能，可使发电机端功率因素提高，降低电流谐波含量，得到稳定的直流链电压，提高发电机的运转效率。

ABSTRACT Development of internal combustion engine has been directed by energy saving and environment protection for a long time. Because lean burn technique has great potential to improve fuel consumption and emissions, it has been paid much attention. Variable induction and twice injection [patent no. 98107693. 9] , which have been developed in recent years, have also shown good effect on engine performance.

能源与环境现已成为内燃机技术发展的主导因素，稀薄燃烧由于其能够很好地改善发动机燃油经济性和排放特性而受到广泛重视；可变进气、二次喷油[专利号：98107693.9]等近年来发展起来的技术也表现出良好地改善发动机性能的能力。

In the system board in the course of a number of variable factors of instability.

在制板过程中有许多可变的不稳定因素。

The main research methods are:(1)Theory analysis:from the 2D plane geometry analysis, dots continuity characteristics are found. The first time irrational fraction algorithm is used in FM program.(2)Experiments reaearch:experiments of condition halftone function are designed under the cross-experiment principles. The first time variable information printer and C# language are used in experiment.(3)Data processing:new type digital density apparatus is used to measure data. Compare is used in processing data and error cause are explained. The main works as follows:The dot area percentage has been gained and new condition halftone function has been set up.(2)After being corrected, speed of irrational fraction algorithm has been compared with multiplicative congruence algorithm's.

本文的主要研究方法有：(1)理论分析：运用数字加网原理，从二维平面几何分析入手，借助实验验证研究网点连续特性；首次系统地把无理数取尾法随机数生成器引入到调频加网系统中，根据实验修正生成器的模型，运用统计假设检验理论，对生成的随机数序列进行统计假设检验；(2)实验研究：根据正交实验法则设计实验，首次采用可变信息印刷机(HP Laser PS印刷机)输出实验样张，克服了用传统胶印机作实验影响因素多的缺陷；采用新型数字式密度仪测量密度值，提高了数据精度；采用最新编程语言编写调频加网程序；(3)数据处理与分析：利用平均值比较法处理数据，对误差产生的原因进行讨论。

Research in these two streams has identified three categories of variables that are linked to export performance: management behavior, environmental factors and firm characteristics Leoni J.H.

对这 二条小河的研究辨认了连接出口表现可变物的三个类别：管理行为，环境因素和牢固的特征Leoni J.H。

The author provides a solution based on added-on restraint zone to the problem of TA saturation. The distance protection is another important content. The thesis compares the relays based on operation equation with relays based on distance measuring. And then puts forward some viewpoints in changeable characteristics Mho relay, grounding fault distance relay, delta-Z relay and the power system swing and protection blocking.

距离保护是本项目的另一个重要内容，论文对常用的动作方程式与测距式距离继电器作了分析对比，对可变姆欧特性距离继电器、接地距离继电器、工频变化量距离继电器的性能、距离保护的振荡闭锁问题谈了一些看法，确定了装置距离保护的若干关键因素。

Raise awareness of and promote action to reduce the main modifiable risk factors for type 2 diabetes.

提高认识和促使行动，以减少2型糖尿病的主要的可变危险因素。

In addition, the working principle of the instrument for measuring spherical curvature is described, and the scheme of structure base on this working principle is designed, and then the accuracy analysis of it is proved in details.

文中详细阐述了可变径球面曲率测量仪器的工作原理、系统选型、结构设计，并详细对测量仪器进行了精度分析及精度综合，指出了影响仪器测量精度的重要因素。

Using the distortion-compensated roentgen analysis method, disc height, dorsoventral displacement, and lordosis were measured in 212 unfused segments from 62 patients, on digitized standing radiographs taken before fusion surgery and after a mean follow-up of 7.5 years (range, 4-11 years).

在标准数字化X光片上，比较术前和术后平均7.5年（4－11年）后62个病人212个未融合节段的椎间盘高度、椎体滑脱及脊柱前凸的情况，可变的影响因素如年齡、随访时间的长度、融合水平、融合节段数、融合节段上下方向和手术前后椎管的改变，用重复测量模型进行分析。

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。