MFB50 on-board estimation methodology for combustion control

Due to the increasing request for pollutant emissions reduction, modern closed-loop combustion control strategies require the on-board evaluation of the center of combustion (MFB50), i.e. the angular position where 50% of the injected fuel mass is burned. This work presents an MFB50 estimation algorithm based on engine speed measurement, that can be performed using the same toothed wheel already present on-board. Therefore, this approach is compatible with on-board application and requires no additional hardware cost. The complete methodology has been applied to a Diesel engine mounted on-board a vehicle and the accuracy of the obtained results is compatible with on-board requirements.     

软件可靠性估计的不确定性分析

在软件开发早期阶段,为分析组件的可靠性和组件间的转移概率的不确定时软件可靠性估计的影响,在基于体系结构的可靠性模型基础上,采用贝叶斯方法对参数的不确定性进行分析.将组件间的转移概率视为随机变量,分析中选用Dirichlet分布的概率密度函数作为先验密度函数,通过MonteCarlo模拟得到系统可靠性的后验估计.实验结果表明,该方法可在早期阶段发现不确定性因素对于系统可靠性的影响,为一些重要的资源分配提供依据.     

混沌系统参数估计结果的不确定性分析*

针对混沌系统参数估计研究中由于随机观测噪声影响而导致的参数估计结果不确定性问题,基于贝叶斯定理提出了一种客观评价混沌系统参数估计结果不确定性的统计方法;进而以典型的Lorenz系统为例进行了数值仿真,分析了不同大小噪声背景下各未知参数估计结果的不确定性;最后基于仿真结果提出了一种在有噪声干扰时估计混沌系统参数的有效方法——后验均值法。相同仿真条件下与前人方法的比较结果表明,该方法可有效抑制噪声影响、约束参数估计结果的不确定性,是一种有噪声情形下估计混沌系统参数的稳健方法。     

Fuel gas blending benchmark for economic performance evaluation of advanced control and state estimation

A simulation of a fuel gas blending process and its measurement system is proposed as a benchmark test case for advanced control and state estimation. The simulation represents an industrial facility and employs a well-established software environment. The objective is to maintain four controlled variables within specified bounds while minimizing an economic performance index. The controlled variables are the fuel gas pressure and three measures of gas quality. Six feed gas flow rates may be adjusted to achieve the objective. Each has a limited availability.The benchmark consists of three reproducible scenarios, each a 46-h period during which 23 discrete upsets occur and the feed gas compositions vary gradually with time. A benchmark multi-loop feedforward–feedback structure is described, tested, and compared to an estimate of optimal performance. The operating cost provided by the benchmark controller is from 1.19 to 1.71 times higher than the estimated minimum.Readers are challenged to download the simulation model, benchmark controller and estimated optimal performance from the URL given in this paper, and to devise case studies of advanced state estimation and control strategies to better the proposed benchmark controller.     

Uncertainty analysis of EQeau,a remote sensing based model for snow water equivalent estimation

This paper is dedicated to the application of uncertainty analysis on the EQeau model. EQeau is a semi‐empirical model that uses satellite C‐band SAR data to estimate Snow Water Equivalent. The uncertainty issues of this model's application have not yet been addressed. The uncertainty analysis permits the evaluation of the impact of input data and model parameters on the model outputs and the assessment of the implications and limitations of the model's application.     

Using combustion net torque for estimation of combustion properties from measurements of crankshaft torque

Two methods, both based on the concept of combustion net torque, for estimation of combustion properties using measurements of crankshaft torque data are investigated in this work. The first of the proposed methods estimates entire burned mass fraction traces from corresponding combustion net torque traces. This is done by solving a convex optimization problem that is based on a derived analytical relation between the two quantities. The other proposed estimation method estimates the well established combustion phasing measure referred to as 50% burned mass fraction directly from combustion net torque using a nonlinear black-box mapping. The methods are assessed using both simulations and experimental data gathered from a 5-cylinder light-duty diesel engine equipped with a crankshaft torque sensor and cylinder pressure sensors that are used for reference measurements. The results indicate that both methods work well but the method that estimates entire burned mass fraction traces is more sensitive to torque data quality. Based on the experimental crankshaft torque data, the direct combustion phasing estimation method delivers estimates with a bias of less than 1 CAD and a cycle-to-cycle standard deviation of less than 2.7 CAD for all cylinders.     

Staged combustion control design for aero engines

This paper discusses the findings of an analysis of an aero engine staged combustion fuel distribution control system design in the framework of the LECCAGT research project. The paper outlines the motivation for developing a staged combustion system and highlights the control-related issues of such an approach for a civil aerospace application. Findings of an analysis of the emission minimisation are presented and control-related issues of optimal fuel distribution are addressed in the paper. Multi-objective genetic algorithms are implemented for the automation of the engine fuel distribution optimisation. Bumpless transfer techniques for priming and purging of burner stages during transient manoeuvres are analysed and presented.     

Beta control charts for monitoring fraction data

p-Charts and np-Charts are commonly used in monitoring variables of the fraction type and these charts assume that the monitored variables are binomially distributed. In this paper we propose a new control chart called Beta Charts, for monitoring fraction data (p). The Beta Chart presents the control limits based on the Beta probability distribution. It was applied for monitoring the variables in three real studies, and it was compared to the control limits with three schemes. The comparative analysis showed that: (i) Beta approximation to the Binomial distribution was more appropriate with values confined in the [0, 1]-interval; and (ii) the charts proposed were more sensitive to the average run length (ARL), in both in-control and out-of-control processes monitoring. The Beta Charts outperform the control charts analyzed for monitoring fraction data.     

脉冲大电流源校准装置测量不确定度评定

脉冲测试法是半导体器件参数测试中普遍采用的测试方法,脉冲大电流源是半导体分立器件测试系统的重要组成部分。本文介绍了半导体器件测试系统校准装置,在解决其校准问题的基础上,对影响脉冲电流幅度测量结果的要素进行了分析,并最终对该校准装置的测量不确定度进行了评定。     

应用椭圆齿轮流量计的内燃机油耗测量系统

介绍一种用于测量内燃机耗油的流量计,以实现对动力机械的燃油控制,达到节能减排的目的.采用椭圆齿轮的测量形式,开发了二次仪表.利用一台喷油泵试验台进行了系统性能验证实验,根据内燃机的实际工作状况,在内燃机三种工况下进行了实验,即最大扭矩转速、最大功率转速以及起动转速.实验结果表明,该测量系统工作稳定,在最大扭矩转速和最大...     

An adaptive algorithm for control of combustion instability

We propose an adaptive algorithm for control of combustion instability suitable for reduction of acoustic pressure oscillations in gas turbine engines, and main burners and augmentors of jet engines over a large range of operating conditions, and supply an experimental demonstration of oscillation attenuation, the first for a large industrial-scale gas turbine combustor. The algorithm consists of an Extended Kalman Filter based frequency tracking observer to determine the in-phase component, the quadrature component, and the magnitude of the acoustic mode of interest, and a phase shifting controller actuating fuel-flow, with the controller phase tuned using extremum-seeking. The paper also identifies a closed-loop model with phase-shifting control of combustion instability from experimental data; supplies stability analysis of the adaptive scheme based upon the identified model, and stable extremum-seeking designs used in experiments.     

Fitting nonlinear low-order models for combustion instability control

Tools for fitting low-complexity nonlinear models based on experimental data are examined through the example problem of finding a reduced-order model suitable for control of a combustion instability operating in a limit cycle. This proceeds in four parts; physical modeling, linear system identification, nonlinear analysis, and validation test design. It is shown how the nonlinear tools of describing functions, bifurcation methods and manifold analysis assist in developing a simple nonlinear model capable of describing the data and consistent with physical understanding. The system being modeled is a lean gas turbine combustor which exhibits a sustained mid-range (100–1000 Hz) limit cycle instability. The closed-loop experimental data does not contain a sufficiently rich spectrum for confident modeling in the first linear system identification phase. Despite the paucity of information quality, a grey-box nonlinear model is created and parametrized which provides an explanation both of the limit-cycle fundamental oscillation and of a high frequency nonharmonic signal also present. The model structure is explored and various operating conditions simulated to understand the model better.

The validation and/or refinement of this model is then considered. The model validation problem is important because of the poor information content of the periodic limit cycle data. The challenge is to provide a practically feasible, small excitation to the loop to improve identifiability and to provide qualitative tests of model performance. We examine this problem by considering the nonlinear dynamics of the model class and feasible excitation mechanisms.     

热风炉燃烧系统最优控制

热风炉燃烧系统是复杂多变量系统,基于最优控制策略,对具有耦合作用的多变量热风炉燃烧系统进行解耦.通过引入神经网络环节,将强耦合多变量系统转化成多个独立的单变量系统,对每个单变量系统进行预测函数控制,实现热风炉燃料流量的最优控制和拱顶温度及废气温度的平稳控制.解耦控制采用前馈补偿器解耦,解耦补偿器采用BP神经网络结构.现场实际应用结果表明,该控制策略具有较好的动态跟踪特性,能满足复杂多变量控制系统的实时控制要求.     

一种基于不确定方法的虚拟人眨眼控制模型*

针对采用确定性方法合成的虚拟人眨眼效果单一、重复、不能刻画眨眼表达深层信息的不确定性,提出一种基于正态云模型的虚拟人眨眼非确定性控制方法.设计了眨眼间隔云、眼皮旋转速度云、睁眼最大角度云和闭眼保持时间云.分别运用正向云生成算法产生眨眼间隔、眼皮旋转速度、睁眼最大角度和闭眼保持时间,且四个参数符合各自云模型的模糊性和随机...     

Error estimation and control for ODEs

This article is about the numerical solution of initial value problems for systems of ordinary differential equations. At first these problems were solved with a fixed method and constant step size, but nowadays the general-purpose codes vary the step size, and possibly the method, as the integration proceeds. Estimating and controlling some measure of error by variation of step size/method inspires some confidence in the numerical solution and makes possible the solution of hard problems. Common ways of doing this are explained briefly in the article.     

Automatic small blend recognition from B-rep models for analysis

The recognition and suppression of small features from B-rep models play an important role in effectively generating the qualified mesh for analysis. This paper presents a new algorithm for recognizing small blends automatically for the purpose of mesh generation. The algorithm first transforms the input B-rep model into an aggregation of faces. Then, each face is judged to be a blend or not based on matching conditions. At last, the blends with larger physical sizes than a threshold value are excluded. The innovations lie in the recognition conditions and the unique calculating procedure of the blend physical size. Several examples are given to demonstrate the validity and applicability of the algorithm.     

A maximum noise fraction transform with improved noise estimation for hyperspectral images

Feature extraction is often performed to reduce spectral dimension of hyperspectral images before image classification. The maximum noise fraction(MNF) transform is one of the most commonly used spectral feature extraction methods. The spectral features in several bands of hyperspectral images are submerged by the noise. The MNF transform is advantageous over the principle component(PC) transform because it takes the noise information in the spatial domain into consideration. However,the experiments describ...     

Hybrid intelligent control of combustion process for ore-roasting furnace

Because of its synthetic and complex characteristics, the combustion process of the shaft ore-roasting furnace is very difficult to control stably. A hybrid intelligent control approach is developed which consists of two systems： one is a cascade fuzzy control system with a temperature soft-sensor, and the other is a ratio control system for air flow with a compensation model for heating gas flow and air-fuel ratio. This approach combined intelligent control, soft-sensing and fault diagnosis with conventional control. It can adjust both the heating gas flow and the air-fuel ratio in real time. By this way, the difficulty of online measurement of the furnace temperature is solved, the fault ratios during combustion process is decreased, the steady control of the furnace temperature is achieved, and the gas consumption is reduced. The successful application in shaft furnaces of a mineral processing plant in China indicates its effectiveness.     

Fuel cell emulator for oxygen excess ratio estimation on power electronics applications

This paper proposes a real-time fuel cell emulator based on the Real-Time Windows Target from Matlab and a controlled power source. The emulator accurately reproduces both static and dynamic fuel cell behaviors, and its main features are the estimation of the oxygen excess ratio and its ability to safely interact with electrical loads such as switching converters. Consequently, the proposed emulator can be used to design and test devices prior to their connection to real fuel cells, preventing undesired phenomena. The emulator was adjusted to the Ballard NEXA 1.2 kW fuel cell, obtaining a satisfactory experimental validation. Finally, the emulator was used to design a hardware-in-the-loop test system to analyze the oxygen starvation effect generated by a DC/DC power converter.     

燃料电池用无刷直流电机控制系统设计

根据燃料电池风量需求，针对风量供给系统的非线性，滞后性等特点，设计了一套以DSP为核心的风量供给用无刷直流电机控制系统，包括主控电路，功率变换电路，IGBT驱动电路，硬件保护电路等；并将模糊控制和PID控制相结合，设计了模糊PID控制器．获得了较好的使用效果。