曲轴校直工艺分析

本文重点分析了曲轴弯曲的原因，围绕两种校直工艺－－压力校直和滚压校直在球墨铸铁曲轴生产上的应用，进行试验研究，为球墨铸铁曲轴采用校直工艺生产，取得了理论依据，并在大批量生产中得到验证。     

曲轴校直T艺分析

本文重点分析了曲轴弯曲的原因,围绕两种校直工艺--压力校直和滚压校直在球墨铸铁曲轴生产上的应用,进行试验研究,为球墨铸铁曲轴采用校直工艺生产,取得了理论依据,并在大批量生产中得到验证.     

气门校直原理探讨

气门校直无非是指气门的杆部和盘部的校正,就现阶段我国气门行业的发展状况,气门毛坯绝大多数是采用电热镦粗,挤压成型的方法获得,且经调质处理后毛坯杆部及锥面园跳动量分别为0.30～0.50、0.30～0.60范围内,象这种精度的毛坯如果不进行校直处理,势必是加大机加工的切削量和机加工精度,给机加工增加困难,从而影响气门成品的质量.目前,气门毛坯调质后大多数是采用手工敲击的方法进行校直,工人劳动强度大,生产率低,且效果比较差,采用机械的方法进行校直已势在必行.现就气门校直原理和校直方案作如下探讨.     

组合试验法推求混凝土拉伸软化曲线的研究

针对混凝土拉伸软化曲线测定难度大、成功率低的问题,提出了一种新的确定混凝土拉伸软化曲线的方法——组合试验法,即通过两种简易的混凝土基本试验混凝土轴心抗拉强度试验和三点弯曲断裂试验,结合简单的数值计算,确定混凝土拉伸软化曲线。为验证组合试验法的准确性,通过算例获得了混凝土拉伸软化曲线,并与混凝土直接拉伸试验获得的拉伸软化曲线进行了对比分析。结果表明,组合试验法获得的拉伸软化曲线的精度满足工程要求,且该方法简便,具有较广的应用前景。     

顶块校直,氮化炉氮化处理：一种修复严重弯曲曲轴的新方法

作为１９０柴油机心脏部件的曲轴,在柴油机使用过程中,因受到复杂的交变应力与恶劣的工作环境的影响,势必会产生或多或少的弯曲变形。而弯曲变形的曲轴若不经修理直接使用,必将会严重影响到柴油机的正常使用与大修寿命。我厂作为全国１９０系列柴油机大修厂家之一,在...     

双对数平面内砂岩颗粒料孔隙比-应力曲线变化规律

为探究灰白砂岩颗粒料在侧限压缩情形下孔隙比—应力(e-p)曲线变化规律及其数学表达,设置砂泥配比、干密度及含水率三因素共11种方案,得到各方案下砂岩颗粒料的e-p曲线,并将e-p曲线与双对数坐标指数模型曲线进行对比,评价模型理论e-p曲线与砂岩颗粒料试验曲线吻合程度。试验结果及模型分析表明,不同砂泥配比时,双对数坐标指数模型颗粒料e-p曲线变化趋势与试验曲线一致;不同干密度时,当轴向应力处于0~0.8MPa时,该模型曲线与试验曲线吻合程度较高;不同含水率作用下砂岩颗粒料试验e-p曲线呈相互穿插形态,当应力处于0.4~1.6 MPa且含水率高于6%时,模型孔隙比理论值大于试验值。可见基于标准砂不同初始孔隙比建立的双对数坐标指数模型对不同干密度砂岩颗粒料e-p曲线数学表述吻合度较高,与不同砂泥配比及初始含水率的e-p曲线吻合度较低。     

车用发动机冷却系统匹配优化方法研究

通过大量数据研究分析,总结出发动机进气流量的计算公式;基于发动机台架热平衡试验,探讨了车用发动机冷却系统匹配方法,并通过整车试验进行了验证;研究了整车冷却系统优化匹配方法,并进行了验证。     

高速柴油机曲轴的校直

本文详尽阐述了高速柴油机曲轴严重磨损和弯曲的直接原因及校直实例。     

基于试验数据的汽轮机通用曲线的绘制

针对采用理论计算方法绘制汽轮机通用曲线涉及的变量太多,计算比较繁琐的问题,研究利用试验数据处理得到汽轮机的通用曲线.文中探讨了基于试验数据绘制汽轮机通用曲线过程中存在的问题,进行改进,并应用改进的方法处理试验数据得到汽轮机通用曲线.该方法简单实用,易于掌握,便于电厂运行人员和管理人员能够方便快捷地得到汽轮机的通用曲线,及时掌握因机组背压变化而引起的功率变化量.     

A new technique of estimating anodic and cathodic charge transfer coefficients from SOFC polarization curves

A new technique is presented for estimating cathodic and anodic transfer coefficients from SOFC voltage–current curves. The new technique for charge transfer coefficients is based on integral characteristics of fuel cell polarization curves. Experimental data from literature are used to illustrate the parameter estimation from SOFC current–voltage curves.     

The utilizability method with hourly vs daily insolation data

The significant difference between using hourly vs daily insolation data in the utilizability method is demonstrated for both the specific case of Bet Dagan, Israel and the more general case of utilizability curves that are generated from hourly and daily insolation correlations. For the annual utilizability curves for flat-plate collectors, the curves based on daily insolation data are shown to be significantly different from the corresponding curves based on hourly data, with the differences between the curves increasing with increasing threshold. A simple explanation for this observation is presented and the importance of the need for accurate utilizability curves at high thresholds is discussed.     

Solar radiation utilizability

The nonlinear behaviour of many solar energy systems requires consideration of the fluctuating nature of solar radiation. Utilizability curves constructed for this purpose consider the radiation fluctuation on the basis of hourly or daily insolation values. Solar collectors, however, do not see radiation fluctuations in terms of hourly or daily insolation values, but respond to instantaneous radiation fluctuations caused by clouds. The fluctuation of instantaneous and short-time integrated radiation has been shown to differ significantly from that of daily insolation. This paper presents utilizability curves constructed from the cumulative probability distribution of instantaneous terrestrial insolation values. It is shown that hourly and daily utilizability curves give a conservative estimate of long-term performance. Experimental measurements of the collector performance further suggest the use of instantaneous utilizability curves in place of daily curves. The effect of the collector time constant on utilizability is discussed.     

Pressure transient analysis of non-planar asymmetric fractures connected to vertical wellbores in hydrocarbon reservoirs

The paper developed a new constant-rate solution for non-planar asymmetric fracture connected to a vertical wellbore in hydrocarbon reservoirs. The non-planar asymmetric fracture has been modeled by combination of two unequal length wings with varied intersection angles. The type curves were drawn in the case of varied fracture conductivities, non-planar angles, and asymmetric factors. The results indicated that fracture conductivity, non-planar angle, and asymmetric factor have coefficient effects on the pressure response, which makes the dimensionless wellbore pressure and pressure derivative curves deviate from the conventional type curves of vertical fractured wells. The dimensionless wellbore pressure and pressure derivative curves are divided into five flow periods. The non-planar angle and asymmetry factor have their unique influences on the shape of type curves during different periods under the different fracture conductivities. The termination of bilinear flow and formation linear flow happened increasingly early with the decrease of non-planar angle or the increase of asymmetry factor. As the fracture conductivity increases, the effect of non-planar angle on the curves moves from the early flow period to the late flow period while the trend of effect of asymmetric factor is quite opposite. The new method lays the foundation of the pressure analysis of the complicated fracture system in developing hydrocarbon reservoirs.     

Fractal modeling of capillary pressure curves for The Geysers rocks

Capillary pressure curves of The Geysers rocks have unique features because of their microfractures. The frequently used Brooks–Corey (1964) model does not match these capillary pressure curves. It would be useful to represent these curves mathematically, to provide a model for use in reservoir performance calculations. A general model developed from fractal modeling of a porous medium was applied and found to match the capillary pressure curves of The Geysers rocks satisfactorily. Capillary pressures were measured using a mercury intrusion technique. The values of fractal dimension, which is a representation of rock heterogeneity, were inferred from the match of the general capillary pressure model to the experimental data. The results demonstrate that the heterogeneity of The Geysers rocks can be determined quantitatively using the values of fractal dimension.     

瓦锡兰RT-flex主机校中与安装的技术要领

船舶主机是船舶动力装置中的重要组成部分,主机安装质量和轴系校中的好坏直接关系到动力装置的正常运行和船舶的航行性能。介绍了瓦锡兰RT-flex主机校中与安装工艺,并进一步分析了安装和校中的各项技术要领,可对主机的实船安装和制定瓦锡兰RT-flex主机安装和校中的工艺标准起到指导作用。     

径向销钉式隔板找中方法

本文介绍了径向销钉式隔板的找中方法，采用这种找中方法可以大大提高找中效率．减轻劳动强度．     

Supply-cost curves for geographically distributed renewable-energy resources

The supply-cost curves of renewable-energy sources are an essential tool to synthesize and analyze large-scale energy-policy scenarios, both in the short and long terms. Here, we suggest and test a parametrization of such curves that allows their representation for modeling purposes with a minimal set of information. In essence, an economic potential is defined based on the mode of the marginal supply-cost curves; and, using this definition, a normalized log-normal distribution function is used to model these curves. The feasibility of this proposal is assessed with data from a GIS-based analysis of solar, wind and biomass technologies in Spain. The best agreement is achieved for solar energy.     

The frequency distribution of daily insolation values

Frequency distributions of insolation values are needed in order to derive simple correlations for predicting the performance of solar energy systems. In this paper the frequency distribution of daily total hemispherical solar irradiation values on the horizontal surface is derived from measured data for 90 locations in the U.S. The results can be approximated by generalized distribution curves which depend only on the clearness index, defined as ratio of terrestrial over extraterrestrial insolation. The results agree well with the curves originally derived by Liu and Jordan, except for a correction at high insolation values. The deviation of individual locations from the generalized curves is examined. A breakdown according to time of year reveals some seasonal variation. The theoretical distribution corresponding to random insolation sequences is also derived; it agrees very well with the generalized frequency distribution curves.     

基于NWAPSO参数全局寻优的LS-SVM电站风机性能预测

风机的性能曲线是风机选型和优化运行的重要依据.通常该曲线通过试验试验数据和性能图表上的数据进行曲线拟合获得.由于该曲线非线性很强,传统方法复杂昂贵,而且拟合精度不高。针对以上不足,提出了一种基于非线性权重自适应粒子群优化(NWAPSO)参数全局寻优的最小二乘支持向量机(LS-SVM)风机性能预测方法。通过最小二乘支持向量机建模,并应用非线性权重自适应粒子群优化算法对模型参数进行全局寻优,得到具有较高精度的风机性能曲线。计算结果表明,根据本文方法建立的模型很简洁,只需要知道少量的训练样本就能建立,可以比较精确的预测风机性能,具有较显著的工程应用价值。