304不锈钢晶间腐蚀的研究

实验使用化学腐蚀法对304不锈钢进行晶间腐蚀测定,通过在不同的腐蚀条件下对304不锈钢进行侵蚀,并进行金相拍照,利用SPSS软件进行了蚀刻宽度数据的统计分析,采用K-S单样本检验分析晶间腐蚀沟槽宽度的统计特性。结果表明:304不锈钢在稀硫酸溶液中的晶间腐蚀沟槽宽度符合正态分布;敏化热处理会加重304不锈钢的晶间腐蚀程度,晶间腐蚀沟槽宽度随敏化热处理时间增长而增大。     

316不锈钢的晶间腐蚀行为的研究

用化学腐蚀法对316不锈钢进行晶间腐蚀测定,对试样进行了溶态化处理和不同程度的敏化处理;通过实验确定了一种既能够最大限度地浸蚀316不锈钢晶界又不腐蚀到晶粒的最佳蚀刻溶液和蚀刻条件.同时采用柯尔莫哥洛夫-斯米尔诺夫(K-s)检验法检验晶问腐蚀沟槽宽度的统计特性.结果表明:316不锈钢在H2SO4溶液中的晶间腐蚀沟槽宽度符合正态分布;敏化热处理会加重316不锈钢的晶问腐蚀程度,晶间腐蚀沟槽宽度随敏化热处理时间增长而增大.     

逐时风速概率分布研究

风速概率分布及其参数是体现风能资源统计特性的最重要指标之一。以山东省4个风电场测风塔和气象站测风年的逐时风速为样本,采用正态分布、指数分布、威布尔分布、伽马分布和Logistics分布对逐时风速概率分布进行研究,以Akaike信息准则判断概率分布的适用性。研究结果表明,威布尔分布、伽马分布和Logistics分布能更好的拟合小时风速的实际情况。     

曲轴疲劳试验及其数据统计分析方法的研究

介绍了曲轴疲劳试验中常用的几种方法,讨论了这些方法的基本原理、特点以及实际应用中存在的一些问题。从工程实用的角度出发并结合长期的实践,给出了这些方法的优劣对比。在失效数据的处理方法方面,较为详细地论述、对比了目前常用的几种分布函数的形式以及参数估计方法。以曲轴弯曲疲劳试验的实测数据为例,进行了正态分布、对数正态分布、威布尔分布下的数据统计回归分析,并对比分析了各种分布在曲轴失效数据的合理性。     

省煤器磨损寿命分布可靠性模型研究

描述金属磨损失效寿命的分布包括正态分布和威布尔分布。给出了这两种分布的表现形式，根据省煤器磨损故障数据，确定了具体的分布形式，并指出威布尔分布比较适合于工程实际，是定量分析省煤器磨损失效可靠性的一种可行方法。     

黑龙江地区风速与风电出力的特征分析与概率分布最优建模

基于黑龙江地区不同区域风电场的大量实测数据,对该地区的风速与风电出力特性进行全面分析,并引入威布尔分布、伽马分布、正态分布和对数正态分布4种概率模型,采用极大似然估计法估算各模型参数,对4处不同地区风电场的风速与风电出力进行模拟并比较,确定不同地理位置风电场的最佳拟合概率分布模型。研究表明黑龙江地区的风速具有明显的季节性、时域性和地域性,各场点风电出力具有一定相关性,其自身的随机波动性受时域和地域的影响。     

利用威布尔分布模型对球磨机可靠性分析

介绍了威布尔分布模型及其优点,对某热电厂B磨煤机的缺陷数据进行分类整理,利用二参数威布尔模型和三参数威布尔模型计算时,分别使用MATLAB软件及采用相关系数优化法进行拟合,对数据计算的结果进行比较分析,三参数威布尔分布模型与常用的二参数威布尔分布模型很相似,由于三参数威布尔分布模型考虑了位置参数而更加的符合实际,所以在球磨机状态检修的实际分析中采用三参数威布尔分布模型.可靠性分析技术的具体应用是利用三参数威布尔分布的数学期望公式求取平均无故障工作时间(MTBF),运用检测周期与MTBF的关系求取设备的状态检测周期以及基于失效率函数的故障类型的诊断.     

结构可靠度分析中小子样概型的拟合检验

本文通过理论分析,证明了A-D(Anderson-Darling)法对水工建筑物中的常见随机变量:如正态分布变量、对数正态分布变量及极值Ⅰ型分布变量的概型检验,识别力强、精度高,并适于小子样概型统计。本文还将A-D法和K-S法进行对比分析。     

基于PPCC检验法的坝前年最高水位统计特性分析

以漳河流域岳城水库为例,采用PPCC检验法对坝前年最高水位常用的几种分布线型进行对比分析.结果表明,实测值和理论值的拟合效果中耿贝尔分布最差、P-Ⅲ型与LP-Ⅲ型分布较好、三参数对数正态分布最好,建议将三参数对数正态分布作为岳城水库坝前年最高水位的分布线型.     

双参数威布尔分布函数的确定及曲线拟合

双参数威布尔分布函数能准确地描述风速的实际分布。通过威布尔分布函数实际数学模型的建立,利用计算机软件（MATLAB）对其函数模型进行曲线拟合,并将拟合曲线应用到实际中,对风资源做初步评价。     

评定焊接材料的晶间腐蚀敏感性应注意的问题

本文通过对几个原材料母材和焊接试样的对比试验,结合国家标准中关于焊接材料试样尺寸的规定,进行计算与理论分析,得知焊接材料在晶间腐蚀敏感性试验中不适合进行弯曲评定的特性,并且依据国家标准中相关说明,重点指出了晶间腐蚀敏感性试验应该注意的问题,为试样的选择、制备及相关检测过程提出了合理化建议.     

风冷非道路柴油机排放特性研究

利用车载排放检测仪(SEMTECH)和电子低压冲击仪(ELPI)进行了某非道路风冷非增压柴油机的气态污染物的测量和排放颗粒物粒径及质量分布特征研究.试验按照非道路柴油机排放标准规定的工况进行测量.试验结果表明:试验用非道路柴油机气态污染物中NOx的排放较差;微粒数量排放均成单峰对数正态分布,积聚模态微粒数浓度随负荷增加而增大,随负荷的减小积聚模态的粒径分布向小粒径方向移动,变化规律与车用柴油机相似,但粒径整体要大于车用柴油机;不同粒径微粒的质量呈双峰分布,分别对应积聚模态和粗粒子模态,积聚模态微粒对总质量排放的贡献较大,但与车用柴油机相比分担率有所不同.     

Hazard Model Reliability Analysis Based on a Wind Generator Condition Monitoring System

This paper presents an application of the hazard model reliability analysis on wind generators, based on a condition monitoring system. The hazard model techniques are most widely used in the statistical analysis of the electric machine＇s lifetime data. The model can be utilized to perform appropriate maintenance decision-making based on the evaluation of the mean time to failures that occur on the wind generators due to high temperatures. The knowledge of the condition monitoring system is used to estimate the hazard failure, and survival rates, which allows the preventive maintenance approach to be performed accurately. A case study is presented to demonstrate the adequacy of the proposed method based on the condition monitoring data for two wind turbines. Such data are representative in the generator temperatures with respect to the expended operating hours of the selected wind turbines. In this context, the influence of the generator temperatures on the lifetime of the generators can be determined. The results of the study can be used to develop the predetermined maintenance program, which significantly reduces the maintenance and operation costs.     

Wind characterization analysis incorporating genetic algorithm: A case study in Taiwan Strait

In this paper, the genetic algorithm (GA) is originally applied to compute the Weibull parameters for wind characterization analysis, in which an objective function required in GA for searching optimization solution has been first defined as well. Wind data analyzed are observed at a wind farm in the Taiwan Strait from 2006 to 2008. To accurately describe wind speed distribution three kinds of probability density functions are compared, i.e. the Weibull, logistic and lognormal functions. Statistical parameters including the max error in the Kolmogorov-Smirnov test, root mean square error, Chi-square error and relative error of wind power density are considered as judgment criterions. The results show that GA is a useful method, there is about 33% time saving when compared with conventional iteration method. Weibull function describes best the wind distribution, regardless of time periods. Accordingly, wind power density, availability factor and electrical energy output from an ideal turbine are assessed using the Weibull parameters; utilization rate of wind energy for the currently used turbine is discussed. Further the wind energy compensates very well with solar energy; when solar radiation is down in winter and spring, the wind power becomes greater; energy ratios for each month are calculated lastly.     

锅炉再热器管腐蚀与防止

介绍了某电厂锅炉高温再热器发生失效的基本情况，通过化学元素分析、力学性能试验、宏观检查、金相分析和电子探针微区成分分析等试验表明，管子外表面存在较明显的结垢现象，氧化物下的金属金相组织出现深2～3个的沿晶腐蚀裂纹，沿晶腐蚀产物中存在S元素综合分析认为，其失效类型为高温硫腐蚀，并提出了预防措施。     

Effect of ammonium chloride on corrosion behavior of Ni-based alloys and stainless steel in supercritical water gasification process

The corrosion behavior of 316 SS and three Ni-based alloys 625, 600 and 800 was evaluated by exposing in SCW at 400 °C and 24 MPa with 6000 ppm NH₄Cl for 70 h. Various of analytical techniques were used for corrosion analysis. 316 SS underwent severe corrosion attack for general corrosion, pitting corrosion and intergranular attack. Inconel 625 showed the best corrosion resistance in the test environment. Fe oxides and spinel were identified by XRD on all of the SCW-exposed samples. Trace amounts of NiO was also identified on the surface of samples, however, Ni was selectively dissolved and depleted in oxide films, and nickel ammine may form at the relatively low temperature during the heating and cooling process.     

Evaluation of material degradation in in-service high temperature structural component by a chemical etching test

An etching test using a picric acid solution with a wetting agent was found to have great potential for the nondestructive evaluation of grain boundary embrittlement caused by phosphorus segregation in both CrMo and CrMoV steels, and by carbide or sigma phase precipitation in austenitic stainless steel. A line pipe (CrMo) and a steam turbine rotor (CrMoV) were tested on-site to demonstrate whether the etching test would be a useful tool. The ΔFATT value estimated by the etching test agreed reasonably well with the ΔFATT determined by an electrochemical method for the turbine rotor steel. A good correlation was found between the degree of intergranular corrosion and the material deterioration of SUS316 stainless steel used as a superheater of a fossil fuel boiler.     

Prediction of the failure pressure for complex corrosion defects

A new method for predicting the failure pressure of corrosion defects in pipelines has been developed. The failure pressure of a plain pipe represents an upper limit for the failure pressure of a pipe with a corrosion defect. The failure pressure of a uniform depth, infinitely long groove, where the depth is equal to the maximum depth of the corrosion defect, represents a lower limit for the failure pressure of a pipe with a natural corrosion defect. The predicted failure pressure can be calculated from these limits using the weighted depth difference (WDD) method, which accounts for the defect geometry and any interaction with adjacent defects. The WDD method has been validated using the results of 40 burst tests of pipe sections containing real corrosion defects. The results indicate that this method provides more accurate burst pressure predictions than the currently accepted corrosion defect assessment procedures.