首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 46 毫秒
1.
为了解决电厂中热力参数失效和优化运行的问题,提出了一种基于稀疏高斯过程的软测量建模方法,它基于Bayes在线学习算法,通过构造序列的相关子样本来给出高斯过程的预测输出.通过利用参数化和再生核Hilbert空间范数的投影技巧,得到优化后的参数和后验过程的稀疏高斯逼近.高斯过程的稀疏表达使得基于高斯过程的软仪表能够满足大规模数据集的实时应用需要,所提出的热力参数软仪表对于电厂经济运行有着重要的意义.  相似文献   

2.
INTRODUCTIONThefermentationprocesshasgreatscientificandpracticalimportance.Forseveralreasons,qua-litycontrol,forexample,itisimportanttoincludeallkindsoftechnologicaladvancesintheindustrialprocesses.Thisisthemainaimofourresearch,whichisverycomplexduetothenon-linearityofthestudiedphenomena.Themathematicalmodelsfoundinliteratureincludeonlylaboratoyconditions.Amathematicalmodelhasbeendevelopedforthebeerfermentationprocessbecauseoftheadvantagesthatitprovides.Itallowssimulatingwhatcanhappenwhe…  相似文献   

3.
This paper describes empirical research on the model, optimization and supervisory control of beer fermentation. Conditions in the laboratory were made as similar as possible to brewery industry conditions. Since mathematical models that consider realistic industrial conditions were not available, a new mathematical model design involving industrial conditions was first developed. Batch fermentations are multiobjective dynamic processes that must be guided along optimal paths to obtain good results. The paper describes a direct way to apply a Pareto set approach with multiobjective evolutionary algorithms (MOEAs). Successful finding of optimal ways to drive these processes were reported. Once obtained, the mathematical fermentation model was used to optimize the fermentation process by using an intelligent control based on certain rules.  相似文献   

4.
Localization of the sensor nodes is a key supporting technology in wireless sensor networks (WSNs). In this paper, a real-time localization estimator of mobile node in WSNs based on extended Kalman filter (KF) is proposed. Mobile node movement model is analyzed and online sequential iterative method is used to compute location result. The detailed steps of mobile sensor node self-localization adopting extended Kalman filter (EKF) is designed. The simulation results show that the accuracy of the localization estimator scheme designed is better than those of maximum likelihood estimation (MLE) and traditional KF algorithm.  相似文献   

5.
In the paper,an iterative method is presented to the optimal control of batch processes.Generally it is very difficult to acquire an accurate mechanistic model for a batch process.Because support vector machine is powerful for the problems characterized by small samples,nonlinearity,high dimension and local minima,support vector regression models are developed for the optimal control of batch processes where end-point properties are required.The model parameters are selected within the Bayesian evidence framework.Based on the model,an iterative method is used to exploit the repetitive nature of batch processes to determine the optimal operating policy.Numerical simulation shows that the iterative optimal control can improve the process performance through iterations.  相似文献   

6.
Sensor localization is crucial for the configuration and applications of wireless sensor network (WSN). A novel distributed localization algorithm, MDS-DC was proposed for wireless sensor network based on multidimensional scaling (MDS) and the shortest path distance correction. In MDS-DC, several local positioning regions with reasonable distribution were firstly constructed by an adaptive search algorithm, which ensures the mergence between the local relative maps of the adjacent local position regions and can reduce the number of common nodes in the network. Then, based on the relationships between the estimated distances and actual distances of anchors, the distance estimation vectors of sensors around anchors were corrected in each local positioning region. During the computations of the local relative coordinates, an iterative process, which is the combination of classical MDS algorithm and SMACOF algorithm, was applied. Finally, the global relative positions or absolute positions of sensors were obtained through merging the relative maps of all local positioning regions. Simulation results show that MDS-DC has better performances in positioning precision, energy efficiency and robustness to range error, which can meet the requirements of applications for sensor localization in WSN.  相似文献   

7.
~~identificationis7-7-1,where3nm==,andtheRPEalgorithmisusedtoupdatetheweightingofPNN.Thewholetrainingprocessuses800iterations.InordertoovercometheinaccuracyofPNNmodel,thecontrollerstructureisacompositeoneasfbff()()()ututut=+,(37)wherefb()utistheoutputoffeedbackcontroller,ff()utistheoutputofpredictivecontrollerdescribedbyEq.(14),with0.20=,0.40=,andmax5K=.Insimulatedclosedloopcontrol,ufb(t)isaproportionalcontroller,fb()()Putket=and5.0Pk=.Theset-pointofthesystemisd0.15,if040,and120()0.24,if4…  相似文献   

8.
INTRODUCTION Bilinear systems are a kind of important nonlinear systems with relatively simple structure, and many industrial processes can be described as a bilinear system. Thus research on the control of this kind of systems is very important. On the other hand, model predictive control (MPC) (Clarke et al., 1987) has been widely used in industrial applications and many predictive control methods focusing on bilinear systems are emerging (Bloemen et al., 2001; Fontes et al., 2004; He…  相似文献   

9.
INTRODUCTION With the rapid development of wireless com-munication technology, the combination of wireless communication and control systems becomes a new trend of networked control systems. Among the kinds of wireless technologies, wireless sensor network (WSN) has attracted a lot of interest and visibility due to its huge application space. WSN is a kind of wire-less ad-hoc network which connects embedded sen-sors, actuators, and processors and in which each node consists of a wireles…  相似文献   

10.
For the reasons of safety and economy,it is desirable to be able to makeon-line predictions of the catalyst deactivation curve in RDS reactor system.Sinceon-line prediction methods are based on models,it becomes neccssary to determine themodel parameters for the real system.In order to facilitate this estimation of parameters,an RDS model,which was obtained from detail mass and energy balances,isparameterized and simplified.The coking effect of catalyst deactivation in our model isdescribed by a simple function,in which the number of parameters involved can be re-duced,from the model's original fifteen,to ten.A method for determining the values of theparameters in the simplified model by the nonlinear programming method is proposed,and finally leading to an on-line deactivation curve forecast.  相似文献   

11.
Video object segmentation is important for video surveillance, object tracking, video object recognition and video editing. An adaptive video segmentation algorithm based on hidden conditional random fields (HCRFs) is proposed, which models spatio-temporal constraints of video sequence. In order to improve the segmentation quality, the weights of spatio-temporal con- straints are adaptively updated by on-line learning for HCRFs. Shadows are the factors affecting segmentation quality. To separate foreground objects from the shadows they cast, linear transform for Gaussian distribution of the background is adopted to model the shadow. The experimental results demonstrated that the error ratio of our algorithm is reduced by 23% and 19% respectively, compared with the Gaussian mixture model (GMM) and spatio-temporal Markov random fields (MRFs).  相似文献   

12.
A grating eddy current displacement sensor （GECDS） can be used in a watertight electronic transducer to realize long range displacement or position measurement with high accuracy in difficult industry conditions. The parameters optimization of the sensor is essential for economic and efficient production. This paper proposes a method to combine an artificial neural network （ANN） and a genetic algorithm （GA） for the sensor parameters optimization. A neural network model is developed to map the complex relationship between design parameters and the nonlinearity error of the GECDS, and then a GA is used in the optimization process to determine the design parameter values, resulting in a desired minimal nonlinearity error of about 0.11%. The calculated nonlinearity error is 0.25%. These results show that the proposed method performs well for the parameters optimization of the GECDS.  相似文献   

13.
讨论了投资和干扰下基于进入过程的风险模型的破产概率.分析得到该模型的盈余过程具有平稳独立增量性:并利用鞅方法获得了该模型破产概率的显式表达式以及它的一个上界估计.  相似文献   

14.
针对无线传感器网络中利用信号强度难以精确定位目标的问题,深入研究了传感器网络定位测量原理和方法。通过对传感器节点的分布情况和信号强度的衰减特点,要研究并提出了利用传感器网络节点,在理想状态下分布式状态估计算法,实现对静态目标和运动目标的准确定位及运动轨迹跟踪。给出了在节点定位过程中各种信号参数之间的关系式,并对所提出的定位原理进行了证明。最后分别给出了针对静态目标和运动目标的定位计算式。  相似文献   

15.
A process model of writing development across the life span   总被引：4，自引：0，他引：4  
In this article, we provide an overview of writing development from a product perspective and from a process perspective. Then we discuss modifications of the most influential process model of skilled adult writing to explain beginning and developing writing, including a proposed developmental sequence of the emergence of cognitive processes in writing. Next we report the results of two recent dissertations by the second and third authors supervised by the first author aimed toward contrasting developmental issues: (a) specifying the algorithms or rules of thumb beginning and developing writers may use during on-line planning; and (b) investigating the further development of writing processes among skilled adult writers. In the first study, development was conceptualized as a linear process across age groups. In the second study, development was conceptualized as a horizontal process within skilled adult writers who expanded their expertise. Finally, we consider the developmental constraints and the instructional constraints on writing development and argue for a model of writing development in which endogenous and exogenous process variables interact to determine the outcome of the writing development process.  相似文献   

16.
Growth mixture modeling (GMM) is a useful statistical method for longitudinal studies because it includes features of both latent growth modeling (LGM) and finite mixture modeling. This Monte Carlo simulation study explored the impact of ignoring 3 types of time series processes (i.e., AR(1), MA(1), and ARMA(1,1)) in GMM and manipulated the separation of the latent classes, the strength of the time series process, and whether the errors conformed to the time series process in 1 or 2 latent classes. The results showed that omitting time series processes resulted in more serious bias in parameter estimation as the distance between classes increased. However, when the class distances were small, ignoring time series processes contributed to the selection of the correct number of classes. When the GMM models correctly specified the time series process, only models with an AR(1) time series process produced unbiased parameter estimates in most conditions. It was also found that among design factors manipulated, the distance between classes prominently affected the identification of the number of classes and parameter estimation.  相似文献   

17.
Because brushless direct current (BLDC) motors have the advantages of a compact size, high power density, high efficiency, and long operating life time, they are widely used in many industrial products and electric traction systems. It is known that the BLDC motors have no brushes for commutation. They are commutated with electronically commutation. So, the rotor position information of the BLDC motors must be known to understand which winding will be energized according to the energizing sequence. In most of the existing BLDC motor drivers, rotor position information is detected by Hall effect sensors. This kind of mechanical position sensors will bring additional connections and costs, reliability decrease and noise increase. In order to improve the control performance and extend the range of speed regulation for BLDC motors, a position sensorless control method is proposed in this paper. In the proposed control method, rotor position information of the BLDC motors is detected from the back electromagnetic forces (back-EMFs) which are estimated by an unknown-input observer with line to line currents and line to line voltages. For the purpose of verifying the effectiveness of the proposed control method, a model is built and simulated on the Matlab/Simulink platform. The simulation results show that the speed regulation performance of BLDC motors is improved compared with using Hall effect sensors. At the same time, the reliability of the BLDC motors is improved and the costs of them are reduced because the position sensor is eliminated.  相似文献   

18.
INTRODUCTION Wireless Sensor Network is one special type of wireless ad hoc networks without fixed infrastructure consisting of a collection of sensor nodes, and oper- ating on limited amount of battery energy consumed mostly in transmission and reception. In the WSNs described in Fig.1, every sensor node can sense, process data and communicate to base station (BS). WSNs have attracted much attention during the recent two years and some commercial implementations such as environmental …  相似文献   

19.
ＬｏｃａｔｉｏｎＤａｔａＦｕｓｉｏｎＢａｓｅｄｏｎＧｒｏｕｐＣｏｎｓｅｎｓｕｓＬｉＧｕｏｄｏｎｇ（李国栋）ＣｈｅｎＷｅｉｎａｎ（陈维南）（ＩｎｓｔｉｔｕｔｅｏｆＡｕｔｏｍａｔｉｏｎ，ＳｏｕｔｈｅａｓｔＵｎｉｖｅｒｓｉｔｙ，Ｎａｎｊｉｎｇ２１００１８...  相似文献   

20.
针对丁醇生产过程中发酵产物品质参量难以实时测量,现有测量方法精度不高、测量结果受不确定因素影响较大的问题,提出一种基于贝叶斯推断和支持向量回归（Support vector machine regression,SVR）的多层软测量建模方法。首先应用贝叶斯推断计算后验概率、筛选偏置数据,并对偏置数据校准,建立第一层SVR模型;然后利用贝叶斯推断进行二次校准,建立第二层SVR模型,对第一层SVR模型输出进行修正,得到最终预测结果,克服干扰和偏差引起的模型不准确问题。将基于贝叶斯推断的多层支持向量回归（Bi-SVR）预测模型应用于丁醇发酵过程,仿真及实验结果表明,相较于传统SVR预测模型,系统在低干扰的情况下预测精度提高了4.52%,在高干扰时预测精度提高了5.37%。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号