Fault Diagnosis for Non-linear System Based On Adaptive Fuzzy System

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Reliability assessment of embedded digital system using multi-state function

This work describes a combinatorial model for estimating the reliability of the embedded digital system by means of multi-state function. This model includes a coverage model for fault-handling techniques implemented in digital systems. The fault-handling techniques make it difficult for many types of components in digital system to be treated as binary state, good or bad. The multi-state function provides a complete analysis of multi-state systems as which the digital systems can be regarded. Through adaptation of software operational profile flow to multi-state function, the HW/SW interaction is also considered for estimation of the reliability of digital system. Using this model, we evaluate the reliability of one board controller in a digital system, Interposing Logic System (ILS), which is installed in YGN nuclear power units 3 and 4. Since the proposed model is a generalized combinatorial model, the simplification of this model becomes the conventional model that treats the system as binary state. This modeling method is particularly attractive for embedded systems in which small sized application software is implemented since it will require very laborious work for this method to be applied to systems with large software.     

机器学习方法的CO2并行压缩系统最优控制

为了研究一种高效的跨临界CO2并行压缩系统的控制方法,本文借助GT-SUITE仿真软件,建立了跨临界CO2并行压缩系统的动态仿真模型,基于仿真得到的系统性能数据集,建立并对比了二阶多项式模型和神经网络模型的系统性能预测模型,并基于神经网络模型开发了跨临界CO2并行压缩系统的模型预测控制器,研究控制器对系统控制稳定性、高效性、实时控制的性能。结果表明：在模型预测控制器作用下,不同制冷工况在150 s内系统能达到稳定运行状态;对比定值控制,采用模型预测控制的系统性能最大提升13.3%;仿真验证了提出的模型预测控制策略对于CO2并行压缩系统实时控制性能优化的可行性,在给定工况下相比对定值控制整体提升性能7.3%。     

基于温度突变模型的冷屏预冷时间计算

为了优化冷屏的预冷系统设计,引入了温度突变模型来分析冷屏的预冷问题。首先介绍了温度突变模型的基理,阐述了将冷屏简化成低温液体输运管的思想。然后对一个大型空间模拟环境试验舱的低温泵氦板预冷系统进行了研究,利用温度突变模型计算得到其理论预冷时间和实际测得的时间相吻合,证明了该模型是可行的。还提出为原始的温度突变模型添加一个修正系数的思想,以便让该模型更加适用于冷屏的预冷过程分析。     

降阶模型及其在大跨度屋盖结构风振中的应用研究

该文建立了一种适用于气弹系统中非线性结构的降阶模型及系统识别方法,并首次将结构降阶模型应用到大跨度屋盖风振结构模型的建立中。非线性结构采用降阶模型并通过高精度有限元模型的非线性系统识别来建立,该模型在结构的模态坐标中将应变能泛函表示为结构模态振幅的多项式函数,该多项式的系数由高精度有限元模型计算所得的模态和应变能信息确定。该方法对一大跨度屋盖的风振响应做了分析,计算结果与采用高精度模型所得结果和实验结果及用ANSYS计算结果进行了比较,结果符合良好。该文的结构降阶模型对于建立非线性结构模型是准确有效的。     

空调制冷系统的建模研究现状介绍

从部件模型和系统模型两个方面分析和总结了国内外制冷系统的建模研究及实际应用状况,认为将制冷系统模型与其它子系统模型相结合的方法能更好地实现空调系统性能优化的目标。     

双管道原油运输系统的着色赋时可控Petri网建模

针对双管道原油运输（高低凝固点原油）系统,利用着色赋时可控Petri网进行建模,分析多个关键约束,特别是高凝固点原油运输管道的约束。利用模块化建模方法,分层建模,结构严谨,描述系统行为完整,可作为观察系统物流信息和短期生产调度制定的辅助工具。     

Semi-empirical modeling and analysis of oil flooded R410A scroll compressors with liquid injection for use in vapor compression systems

Oil flooding is a technique that can be utilized in compression systems to achieve near-isothermal compression. This can lead to a boost in system efficiency and a reduction in compressor power consumption. In this paper a semi-empirical model for oil flooded compressors using liquid injection was developed. The model is validated with experimental data and integrated into a thermodynamic model of a vapor compression system with oil flooding and regeneration. The performance of the heat pump system is predicted and the semi-empirical model is used to identify and estimate the magnitude of the irreversibilities during the compression process. A method for generalizing the model for different working fluids is also presented. Using this model, design recommendations are made to improve the efficiency of the studied liquid flooded compressors for heat pump applications.     

基于可信性理论的模糊环境下再制造生产计划

针对再制造系统生产计划问题,分析了再制造系统的特点。以一般再制造系统为原型,在可回收产品数量、单位产品拆卸时间、单位零部件再制造加工时间以及客户需求不确定情况下,考虑回收、拆卸、再制造加工、重新装配的能力限制,以总成本最小化为目标,构建了模糊再制造系统混合整数规划模型。利用可信性理论给出了模糊模型的清晰等价形式。最后,通过算例分析了不同置信水平选取对再制造成本的影响,验证了模型对再制造企业生产计划制定的适用性。     

Multivariable control-oriented modeling of a direct expansion (DX) air conditioning (A/C) system

A dynamic mathematical model for a DX A/C system has been developed. The dynamic model, written in state-space representation which was suitable for designing multivariable control, was linearized at steady state operating points. The linearized model has been validated by comparing the model simulation results with the experimental data obtained from an experimental DX A/C system. The simulated results agreed well with the experimental data, suggesting that the model developed was able to capture the transient characteristics of the DX A/C system modeled. It is expected that the model developed can be useful in designing a multi-input multi-output (MIMO) controller to simultaneously control indoor air temperature and humidity in a space served by a DX A/C system.     

基于模型设计方法的混合磁悬浮平台的控制设计及实现

基于模型的设计方法,利用Matlab/Simulink对磁悬浮系统进行浮点数字PID控制仿真,并结合定点控制器DSP2812,实现系统控制的快速构建,达到系统模型及控制设计、系统仿真和硬件实现的无缝集成,从而加速控制系统的快速开发.首先,在Matlab/Simulink环境中建立系统控制模型,并利用其自带的定点工具箱对数字控制器进行定点化处理,建立可以移植的带有数字平均滤波的Simulink代码模型.再通过RTDX功能进行算法的调试与验证,并进行代码模型的优化.最终自动生成可靠的C代码到控制器来实现对混合磁悬浮平台的控制,实现在模型仿真和系统实施的集成和统一.并由实物进行了验证．     

A generic method for estimating system reliability using Bayesian networks

This study presents a holistic method for constructing a Bayesian network (BN) model for estimating system reliability. BN is a probabilistic approach that is used to model and predict the behavior of a system based on observed stochastic events. The BN model is a directed acyclic graph (DAG) where the nodes represent system components and arcs represent relationships among them. Although recent studies on using BN for estimating system reliability have been proposed, they are based on the assumption that a pre-built BN has been designed to represent the system. In these studies, the task of building the BN is typically left to a group of specialists who are BN and domain experts. The BN experts should learn about the domain before building the BN, which is generally very time consuming and may lead to incorrect deductions. As there are no existing studies to eliminate the need for a human expert in the process of system reliability estimation, this paper introduces a method that uses historical data about the system to be modeled as a BN and provides efficient techniques for automated construction of the BN model, and hence estimation of the system reliability. In this respect K2, a data mining algorithm, is used for finding associations between system components, and thus building the BN model. This algorithm uses a heuristic to provide efficient and accurate results while searching for associations. Moreover, no human intervention is necessary during the process of BN construction and reliability estimation. The paper provides a step-by-step illustration of the method and evaluation of the approach with literature case examples.     

具有参数摄动的复杂柔性耦合隔振系统建模

针对目前复杂柔性隔振系统的数学模型与实际隔振系统之间存在的差异，将阻抗/导纳方法和矩阵传递法相结合，建立包括被隔离设备、多个电磁式主被动一体隔振器和柔性基础在内的复杂柔性耦合系统的状态空间模型。将相对于名义模型中隔振系统参数的变化量以虚拟回路增益的方式引入模型，建立具有参数摄动的隔振系统数学模型。在此基础上，通过矩阵变换的形式，推导出反映模态频率不确定的参数摄动的隔振系统模型，直观反映系统模态阻尼和模态频率的变化，为下一步复杂柔性耦合隔振系统的鲁棒控制器的设计提供依据。     

A Verification Model for Optimal Reliability Evaluation and Improvement

This article describes a logical verification model for evaluating, verifying and improving the reliability of a manufactured and assembled system. The proposed verification model is based on the analysis of the subsystems instead of the system as such, and results in an expression for the probability of no critical failures in the system after the verification. Two verification plans are considered, and the results of the model are utilized to find the optimal verification policy for evaluating and improving the reliability of the system.     

面向协调的区域"经济-环境"系统管理模型

从管理的动态性特征出发,用复合子f、协调机制c、评价标准g来描述面向协调的管理的概念模型.在此基础上,按照系统分析、系统评价、系统调控三个步骤建立了面向协调的区域"环境-经济"系统管理模型.提出了基于系统功能和效益(率)的系统发展状态评价指标体系,应用灰色关联分析法遴选出与该复合系统在发展过程中联系最紧密的系统要素.最后对西安市的经济-环境进行了实证分析.     

Model for Failure Point Process of a Repairable System and Application

A engineering system is usually repairable,and failure process of a repairable system is often described by a failure point process. The power law model is a commonly used approach to model the failure point process.This paper introduces the concept and model for the failure process of repairable system. The method of parameter estimation is developed,and failure observations are fitted into a power-law model by using the least square method. Two applications of the pressent model are discussed according to the practical failure data of the central cooling system of a nuclear power plant. One application is determining the optimal overhaul time,and the other is evaluating the quality of maintenance. This paper provides references for the overhaul decision making and maintenance quality evaluation in reality.     

Modeling of Non-uniformly Sampled Systems by Support Vector Regression with Applications

This paper presents a modeling method for a non-uniformly sampled system based on support vector regression (SVR).First,a lifted discrete-time state-space model for a non-uniformly sampled system is derived by using the lifting technique to reduce the modeling difficulty caused by multirate sampling.Then,the system is divided into several parallel subsystems and their input-output model is presented to satisfy the SVR model.Finally,an on-line SVR technique is utilized to establish the models of all subsyste...     

基于SysML的多学科设计建模与优化

目的 基于系统建模语言SysML,分析多学科设计建模与优化过程,在理解多学科设计与优化数学模型的基础上,构建系统设计优化模型。方法 通过分析多学科设计优化的数学模型,利用SysML语言对多学科优化对象模型进行元模型表征,将生成的SysML模型进行模型转化,转换成XML格式以便优化求解器进行求解。结论 提出了一种用于多学科设计建模与优化的SysML扩展优化建模方法。通过SysML系统建模语言的扩展版型,添加多学科优化相关的优化目标、优化约束、优化变量等优化元素的模型内容。提出了SysML优化信息的提取方法,以XML为中间格式,将提取的优化模型与优化求解器进行集成。通过系统设计与系统优化的集成求解为产品系统架构设计人员提供有效的决策支撑。