Study on early warning index of spatial deformation for high concrete dam

Owing to the deficiency in early warning for high concrete dam,a formula was established to characterize the deformation behavior of high concrete dam as a whole.The early warning index of spatial deformation was calculated by low probability principle on the basis of the deformation entropy formula proposed.The steps were as follows.Firstly,the probability method was utilized to define the degree of order and degree of chaos for each survey point.Secondly,the weight distribution among the survey points was...     

基于神经网络与遗传算法的锅炉系统的优化

传统热工控制系统DCS在锅炉运行中存在多变量之间相关关系难以全面协调以及期望性能指标难以达到的问题。针对参数难以全面协调问题,采用BP神经网络来解决多变量间的非线性关系。针对性能指标的优化,在神经网络预测功能的基础上,采用遗传算法优化锅炉参数间的比值,并将优化后的风煤比在线监测数据作为反馈信号引入锅炉性能优化系统中,改进后的方法优化处理了热工控制系统问题。以青岛市某循环流化床锅炉为例,通过Matlab与C#语言编写的可视化界面曲线得出,预测与优化的综合方法能够将锅炉效率提高0.5%~3%。     

Numerical investigation on flow and convective heat transfer of aviation kerosene at supercritical conditions

In this paper,characteristics of flow and convective heat transfer of China RP-3 kerosene in straight circular pipe were numerically studied.Navier-Stokes equations were solved using RNG k-turbulence model with low Reynolds number correction.The thermophysical and transport properties of the China RP-3 kerosene were calculated with a 10-species surrogate and the extended corresponding state method(ECS) combined with Benedict-Webb-Rubin equation.The independence of grids was first studied and the numerical results were then compared with experimental data for validation.Under flow conditions given in the paper,the results show that deterioration of convective heat transfer occurs when the wall temperature is slightly higher than the pseudo-critical temperature of kerosene for cases with wall heat flux of 1.2 and 0.8 MW/m 2.The degree of the heat transfer deterioration is weakened as the heat flux decreases.The deterioration,however,does not happen when the heat flux on the pipe wall is reduced to 0.5 MW/m 2.Based on the analysis of the near-wall turbulent properties,it is found that the heat transfer deterioration and then the enhancement are attributed partly to the change in the turbulent kinetic energy in the vicinity of pipe wall.The conventional heat transfer relations such as Sieder-Tate and Gnielinski formulas can be used for the estimation of kerosene heat convection under subcritical conditions,but they are not capable of predicting the phenomenon of heat transfer deterioration.The modified Bae-Kim formula can describe the heat transfer deterioration.In addition,the frictional drag would increase dramatically when the fuel transforms to the supercritical state.     

Microstructures of laser cladding of intermetallic-ceramic composite coatings

The microstructures of laser cladding of (Ni-24.5%(atom fraction)Al)+5O%(mass haction)WC coatingsbefore and after aging was comparetively studied by using SEM and TEM. It is shown that dissolving of WC and reprecipitating in the forms of WC and W,Coccurred during laser cladding, and intermetallic γ' (Ni3Al) orderly precipitatefrom metastable supersaturant Ni-matrix solid solution after heat treatment. The structures are favorable for coating'sproperties.     

数据处理常用数表的替代公式

数据处理与统计中查各种系数的数表很不方便,建立了一系列简化公式以替代这些数表.     

基于B/S模式的高校仪器设备管理系统的设计

根据高校仪器设备管理的特点和存在的问题,介绍了一种基于B/S模式的高校仪器设备管理系统.提出了系统的实现方法,描述了系统的主要技术、结构、功能和特点.     

基于过程的英语专业学生口译能力培养教学方法

口译工作在经济发展中扮演着重要角色,但国内口译教学和口译人才培养尚存在各种问题。在研究口译教学理论和口译教学实践的基础上,以基于过程的口译教学理论为支撑,以口译专题实习的反思教学为基础,以口译技能训练为中心,构建一个符合经济社会发展需要的,面向市场、面向实践、实用性强的口译训练的教学方法。     

铁素体区轧制技术及应用于攀钢生产的可行性

讨论了铁素体区轧制技术的优势,特点及其在国内外生产厂家的应用现状,分析限铁素体区轧制工艺在攀钢实施的可行性。     

Ti-15Mo-2.7Nb-3Al-0.25Si合金表面改性及腐蚀性研究

采用恒电位极化法研究了Ti-15Mo-2.7Nb-3Al-0.25Si合金的表面改性工艺,并测试了该合金在Ring′s模拟体液中的体外耐腐蚀性能。结果表明,随极化电压升高,氧化膜稳定速度加快,氧化膜电阻值随电解液浓度的增加呈单峰曲线变化,且随处理时间的延长逐渐达到稳态;在处理电压为10V、处理时间为30min、HF酸浓度为2%时,合金表面所形成的氧化膜稳定,其结构为网状并形成微米孔隙,表现出良好的耐腐蚀性。