国产化控制系统平台在CAP1400核电站样机中的应用

核电站数字化仪控系统是整个核电站的"神经中枢",标志着一个国家在大型核电装备领域的现代化程度,长期以来中国在这一领域的产品绝大部分依赖进口。若国产化的平台升级改造完成,我国的三代核电站在控制系统上将彻底摆脱现有被国外垄断的局面,并且大大降低控制系统的投入成本。成本的降低、技术和可靠性提高使得后续机组都会采用该控制系统平台,并使其成为一个标准设计。完成升级改造后,其生产制造收入和国家所省下的投入被计算为经济效益时是不可估量的。     

核电站安全壳在外来事件作用下的安全防护性能研究进展

核电站安全壳是核反应堆的最后一道屏障,其结构的安全性直接关系到核电站周围人员和环境的安全问题。介绍了核电站安全壳的功能及其分类,基于核电站安全壳特殊的防护功能要求,对安全壳结构在地震、飞机撞击和爆炸等外来事件作用下的安全防护性能进行了探讨,并对安全壳结构防护措施的改善给予了相应建议。     

永磁无刷电动机在自动排线系统中的应用

概述了自动排线系统的开发与设计.通过对自动排线系统特点、功能分析,阐述了自动排线系统的基本原理.针对传统绕线机控制精度低、速度低和产品质量差等缺点,以无刷直流电动机为核心,采用速度环和电流环组成双闭环控制系统.详细描述自动排线系统的硬件结构以及程序的总体设计.该设计结构简单、调整方便,已应用于实际电线生产线中.     

核电站电气贯穿芯棒热老化寿命评定技术的研究

介绍了电气设备单一绝缘结构与复合绝缘结构热老化寿命的评定技术,阐述了核电站电气贯穿件复合绝缘结构热老化寿命试验样品和老化温度的选取、失效判据及试验方法.试验结果表明,在相同的使用环境温度下,采用均压旋锻复合绝缘密封结构的核电站电气贯穿芯棒热老化寿命明显高于对照产品,其热失效的主要因素是机械性能而不是电气性能.     

基于TRIZ的锤击剪切复合式秸秆微粉碎机概念设计

为了提高秸秆微粉碎效率、降低粉碎粒度,文章应用发明问题解决理论(TRIZ)指导秸秆微粉碎机的概念设计。基于功能需求分析和科学效应确定秸秆微粉碎方法;通过因果链分析、九屏幕法、理想解IFR、系统功能分析、矛盾分析、功能裁剪和资源分析等TRIZ工具对粉碎机构、分级机构和入料机构进行创新设计。基于系统化结构化的TRIZ工具辅助产品概念设计,可以提供多维度的解题方向,提高设计质量和效率。     

一步法制二甲醚双功能催化剂研究进展

从合成气一步法制二甲醚工艺出发,介绍了合成反应机理、双功能催化剂的改性研究和失活研究现状,阐述了双功能催化剂的研究发展趋势.Cu-Zn-Al-Li甲醇合成催化剂的活性及稳定性较好,应将其应用于双功能催化剂中.胶体沉积法、完全液相法分别是制备固定床、浆态床双功能催化剂的最佳方法.双功能催化剂的失活方式及失活原因仍处于研究中,目前还没有结论,是今后研究的一个重点.     

基于子结构法的汽轮发电机组模型轴系及弹簧基础模态分析

针对有限元法分析大型汽轮发电机组轴系及弹簧基础模态时节点数多、求解困难的问题,在计算中引入了子结构模态综合法(CMS)。以某轴系及弹簧基础模型试验台为研究对象,建立了三维有限元模型,应用CMS法进行了联合模态分析;同时采用锤击法对试验台顶台板进行了模态测试。研究结果表明:采用CMS法与直接有限元法在单独计算弹簧基础模态频率时误差极小,在0.13%以内;基于CMS法的顶台板拓展结果与顶台板模态实测结果较为吻合,模态频率误差在工程允许范围内;CMS法作为一种解决复杂结构动力学问题的方法可以有效地应用于轴系及弹簧基础的模态分析。     

核电站DCS应用软件测试用例设计研究

DCS应用软件测试是核电厂数字化控制系统开发过程中一项重要的VV活动,而应用软件测试的核心则在于测试用例的设计。为了更有效地从软件中发现缺陷,主要研究测试用例的设计技术。通过等价类划分、边界值分析及因果图等方法,总结了1套适用于核电站DCS应用软件测试用例设计的方法,为工程应用软件更好的服务于核电站的运行提供基本保障。     

价值工程在空调冷热源方案选择上的应用

介绍了价值工程原理和价值工程的一般运用程序 ,以沈阳某空调机房冷热源方案的选择为例 ,说明建筑工程产品的功能评分方法、功能评价系数和成本系数的确定 ,并利用价值工程进行冷热源组合方案的优选 ,分析中力求功能分析和成本计算的全面准确。强调具体问题具体分析     

核电站常规岛主厂房结构抗震性能设计

核电站常规岛主厂房结构布置受限于工艺流程,含较多的错层、跃层,使结构的刚度与质量分布严重不均匀,往往超过了规范的适用条件,地震期间若出现功能中断或设备受损都将造成巨大的损失。基于性能的抗震设计应用于主厂房结构的抗震设计与评估中,在承载力和变形能力两个方面量化其抗震水平,确保主厂房的抗震能力满足预期设防目标。承载力依据现行抗震规范设计,变形能力的评估细化到构件的层次进行,在此基础上选取了5条地震波记录对典型常规岛主厂房结构进行弹塑性分析。结果表明:核电站常规岛主厂房结构能够在地震作用下保持不倒塌,结构具有较大冗余度,能保证核岛安全。     

基于小波函数的陶瓷烧成温度预测函数控制研究

针对陶瓷烧成生产过程的复杂性,提出一种基于小波函数的陶瓷烧成温度的预测函数控制方法。给出陶瓷烧成温度预测函数控制的基本原理;利用小波的多尺度分析和紧支局部特性,选取小波函数作为基函数,根据逼近要求灵活设置小波基函数的个数及位置分布,在保证系统整体优化性能的同时又兼顾了局部重点要求;理论分析和仿真表明,该控制方法与普通PFC方法相比,在动态特性、控制精度、抗干扰等方面具有明显的改善作用。     

矩阵在循环函数法中的应用研究

循环函数法是电厂热力系统性能分析的重要方法之一,但是其运算比较繁琐,其应用也越来越受到限制。基于循环函数法的主导思想,通过对“加热单元”列能量平衡方程,构建了循环函数法的矩阵表达式,并对矩阵填写规则进行了详细阐述。通过对算例进行分析计算,证明该矩阵正确可靠,计算速度快、精度高。同时通过该矩阵也便于计算带疏水泵的汇集式加热器混合点后的焓值,在生产实践中有较强的通用性和实用性。     

A novel computational approach to study proton transfer in perfluorosulfonic acid membranes

Density functional theory (DFT) calculations were done to obtain the energies of two perfluorosulfonic acid membranes at low humidity conditions. For the first time, an artificial neural network (ANN) approach along with statistical methods were employed for modeling, prediction, and analysis of the energies derived by the DFT method. The ANN method substantially does speed up the ab initio electronic structure calculations and has superior accuracy to mimic the results of such calculations. The designed ANNs for modeling the total and binding energies had high performance since the computed R² values were 0.99998 and 0.990, and the calculated root mean squared error (RMSE) values were 0.612173 Ha and 0.084901 Ha in predicting the total and binding energies, respectively. Statistical analysis of binding energies per water molecule using analysis of means (ANOM) and analysis of variance (ANOVA) methods showed that the hydration level has significant influence on the proton transfer in the perfluorosulfonic acid membranes. ANOM and ANOVA methods were also employed to determine the quantitative effect of other parameters (i.e., temperature and total charge of the system) as well as the combined effect of these parameters. The ease of the proton transfer was also assessed with the aid of the obtained potential energy surfaces.     

A model for optimal sizing of photovoltaic irrigation water pumping systems

The previous methods for optimal sizing of photovoltaic (PV) irrigation water pumping systems separately considered the demand for hydraulic energy and possibilities of its production from available solar energy with the PV pumping system. Unlike such methods, this work approaches the subject problem systematically, meaning that all relevant system elements and their characteristics have been analyzed: PV water pumping system, local climate, boreholes, soil, crops and method of irrigation; therefore, the objective function has been defined in an entirely new manner. The result of such approach is the new mathematical hybrid simulation optimization model for optimal sizing of PV irrigation water pumping systems, that uses dynamic programming for optimizing, while the constraints were defined by the simulation model. The model was tested on two areas in Croatia, and it has been established that this model successfully takes into consideration all characteristic values and their relations in the integrated system. The optimal nominal electric power of PV generator, obtained in the manner presented, are relatively smaller than when the usual method of sizing is used. The presented method for solving the problem has paved the way towards the general model for optimal sizing of all stand-alone PV systems that have some type of energy storage, as well as optimal sizing of PV power plant that functions together with the storage hydroelectric power plant.     

A direct method to determine transfer function parameters in case of hydrogen evolution reaction

Electrochemical impedance spectroscopy is one of the efficient methods for studying reaction mechanisms. In case of hydrogen evolution reaction, the transfer function involved is very complex. It is therefore usually obtained through indirect methods. First, a simple equivalent circuit is usually fitted to the experimental data using complex non-linear least square methods. The circuit parameters thus obtained are then transformed to transfer function parameters. In the present approach, the procedure for obtaining transfer function has been simplified through its piecewise definition in various frequency ranges. A direct method to obtain transfer function using asymptotic analysis has been presented. The method to reduce error involved in the analysis has also been discussed. It has been shown that the approach will also be applicable for other systems.     

Performance comparison of six numerical methods in estimating Weibull parameters for wind energy application

Two-parameter Weibull function has been widely applied to evaluate wind energy potential. In this paper, six kinds of numerical methods commonly used for estimating Weibull parameters are reviewed; i.e. the moment, empirical, graphical, maximum likelihood, modified maximum likelihood and energy pattern factor method. Their performance is compared through Monte Carlo simulation and analysis of actual wind speed according to the criterions such as Kolmogorov–Smirnov test, parameter error, root mean square error, and wind energy error. The results show that, in simulation test of random variables, the graphical method’s performance in estimating Weibull parameters is the worst one, followed by the empirical and energy pattern factor methods, if data number is smaller. The performance for all the six methods is improved while data number becomes larger; the graphical method is even better than the empirical and energy pattern factor methods. The maximum likelihood, modified maximum likelihood and moment methods present relatively more excellent ability throughout the simulation tests. From analysis of actual data, it is found that if wind speed distribution matches well with Weibull function, the six methods are applicable; but if not, the maximum likelihood method performs best followed by the modified maximum likelihood and moment methods, based on double checks including potential energy and cumulative distribution function.     

Approaches for developing a sizing method for stand-alone PV systems with variable demand

Accurate sizing is one of the most important aspects to take into consideration when designing a stand-alone photovoltaic system (SAPV). Various methods, which differ in terms of their simplicity or reliability, have been developed for this purpose. Analytical methods, which seek functional relationships between variables of interest to the sizing problem, are one of these approaches.A series of rational considerations are presented in this paper with the aim of shedding light upon the basic principles and results of various sizing methods proposed by different authors. These considerations set the basis for a new analytical method that has been designed for systems with variable monthly energy demands.Following previous approaches, the method proposed is based on the concept of loss of load probability (LLP)—a parameter that is used to characterize system design. The method includes information on the standard deviation of loss of load probability (σ_LLP) and on two new parameters: annual number of system failures (f) and standard deviation of annual number of failures (σ_f).The method proves useful for sizing a PV system in a reliable manner and serves to explain the discrepancies found in the research on systems with LLP<10⁻². We demonstrate that reliability depends not only on the sizing variables and on the distribution function of solar radiation, but on the minimum value as well, which in a given location and with a monthly average clearness index, achieves total solar radiation on the receiver surface.     

A thermomechanical model for the analysis of disc brake using the finite element method in frictional contact

Abstract

In this work, a numerical simulation of the transient thermal analysis and the static structural one was performed here sequentially, with the coupled thermo-structural method using the ANSYS software. Numerical procedure of calculation relies on important steps such that the CFD thermal analysis has been well illustrated in 3D, showing the effects of heat distribution over the brake disc. This CFD analysis helped in the calculation of the values of the thermal coefficients (h) that have been exploited in the 3D transient evolution of the brake disc temperatures. Three different brake disc materials were selected in this simulation and comparative analysis of the results was conducted in order, to derive the one with the best thermal behavior. Finally, the resolution of the coupled thermomechanical model allows to visualize other important results of this research such as; the deformations, and the equivalent stresses of Von Mises of the disc, as well as the contact pressure of the brake pads. Following our analysis and results we draw from it, we derive several conclusions. The choice makes it possible to deliver the best brake rotor so as to ensure and guarantee the good braking performance of the vehicles.     

Applied statistics for extreme wind estimate

The assessment of extreme wind speeds is a crucial issue for securing structural safety of wind turbines and inquiring largest loads to which turbines must be prepared to undergo. International standards suggest applying the Gumbel method of fitting the annual maxima to their theoretic probability distribution. Yet, often, wind databases are too short to apply such methods with statistical significance, and other procedures are commonly adopted [such as peaks over threshold (POT) and independent storms], which involve dependency on arbitrary thresholds for filtering data and issues of sub‐asymptocity, i.e. how well the selected dataset fits to density functions describing the distribution of peaks or extreme values. The present paper aims at contributing to such currently ongoing debate, providing a statistical analysis of the application of POT and independent storms methods on wind time series of various lengths from different geographical areas. The CERN data analysis framework ROOT has been employed for guaranteeing excellent standards of computational precision and wealth of statistical information. Analysis of uncertainties in the wind speeds estimates and tests of the goodness of fit of the datasets to the proper distributions have been carried on. An algorithm for choosing the optimum thresholds was developed, which encapsules and compromises the statistical complexity of the methods. A declustering procedure has been carried on for discriminating proper peaks in the POT method: it has been tested that such declustering provides a dramatic improvement of the statistical quality of the method. Copyright © 2014 John Wiley & Sons, Ltd.     

An easy parameter estimation procedure for modeling a HT-PEMFC

Fuel cells are a very complex system in which many phenomena of different nature occur simultaneously and within a small space, so a truthful measurement of some variables is not feasible using state-of-the-art technology. If a deep knowledge of the unit is desired, modeling can be of great help when it is properly used as it is possible to calculate the value of the variables of interest by adjusting experimental data. However, when models are complicated, it is not trivial to identify in which way a certain parameter alters the model results and then it is necessary to resort to sensitivity analysis before approaching an adequate parameter estimation procedure. In this work, a parameter estimation procedure has been proposed with the results obtained from the sensitivity analysis applied to a high temperature proton exchange membrane fuel cell (HT-PEMFC) model. The procedure has been demonstrated to be straightforwardly applicable as well as effective, which makes it suitable to be used as engineering tool to obtain a first consistent value of the parameters that define the main characteristics of a HT-PEMFC.