检索结果-内蒙古大学图书馆

Analysis of thermal boundary layer of thermal effects on flow characteristics of small sonic nozzles

Jixie Gongcheng Xuebao/Journal of Mechanical engineering 2015年第16期51卷 164-170页

作者： Wang, Chao Wang, Gang Ding, Hongbing School of Electrical Engineering and Automation Tianjin University Tianjin300072 China Tianjin Key Laboratory of Process Measurement and Control Tianjin300072 China

The gas temperature will drop greatly when flowing through the nozzle. The heat exchange between the cold gas and the wall will produce a series of complex effects which are called "thermal effect". The small-diameter nozzles used in the field of small flow measurement will be influenced by the thermal effect seriously. The laws of temperature variation of sonic nozzles are analyzed by the thermal boundary layer theory with different inlet pressure, locations and throat diameters. According to the experimental data, the dynamic interaction between the wall temperature distribution and the thermal boundary layer thickness is analyzed theoretically. The changes of boundary layer thickness are studied in detail by the CFD method and a formula of discharge coefficient deviation is fitted. It is indicated that the discharge coefficient increases by 0.195% with the wall temperature decreasing by 15 K caused by the thinning of the boundary layer which is necessary to pay more attention. ©, 2015, Journal of Mechanical engineering. All right reserved.

关键词： Boundary layers

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Measurement of Phase Fraction in Oil-Water Two-Phase Flow Using Ultrasound Attenuation Method

Measurement of Phase Fraction in Oil-Water Two-Phase Flow Us...

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Chinese automation Congress

作者： Qian Su Chao Tan Feng Dong Key Laboratory of Process Measurement and Control School of Electrical Engineering and Automation Tianjin University

ISBN: (纸本)9781467371902

Ultrasonic technology has potential application prospect in measurement of phase fraction in oil-water two-phase flow. An ultrasound attenuation method is discussed in the oil-water two-phase flow. Geometric simulation models of oil-water two-phase flow with different fractions are set up based on the finite element analysis method. Simulation results show that phase fraction and distribution jointly affect on the ultrasound attenuation coefficient. Test results give good agreement with the trend of the simulation results. The feasibility and effectiveness can be achieved to use the ultrasound attenuation testing method. This is a basic work for ultrasound attenuation method adopted to test the phase fraction of oil-water two-phase flow. A predicted model of phase fraction with different flow patterns can be effectively established combined with physically experimental data.

关键词： Ultrasonic sensor Oil-water two-phase flow Phase fraction Ultrasound attenuation Flow parameter

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A three-level batching strategy for the planning of steelmaking-continuous casting production 16

A three-level batching strategy for the planning of steelmak...

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16th IFAC Workshop on control Applications of Optimization, CAO 2015

作者： Sun, Liangliang Luan, Fangjun Ma, Tianmu Department of Information and Control Engineering Shenyang Jianzhu University Shenyang Liaoning Province110004 China Key Laboratory of Integrated Automation of Process Industry Ministry of Education Northeastern University Shenyang Liaoning Province110004 China

This paper focuses on the optimal planning of steelmaking-continuous casting production in real steelmaking plant. The tasks of steelmaking planning are to make the decisions as how to determine the relation between slabs and charges, the sequence of charges in casts and the casting width of slabs while considering the known information about the contract properties, the size properties and processing properties, etc. Effective planning can satisfy the capacity of downstream and continuously casting the steel molten. A three-level batching policy consisting of charge planning, tundish planning, cast planning is proposed in this paper. The different requirement of width in charge planning, tundish planning, cast planning are considered as the performance indicators and constraints equations respectively to formulate the problems. A hybrid optimal strategy combined with the iterated local search (ILS), variable neighborhood search (VNS), and the hybrid optimal strategy with ant colony optimization is adopted. Numerical experiments are done to verify the effectiveness of the three-level batching strategy by using practical data set collected from the steelmaking plant in Baosteel which is one of the most advanced iron and steel enterprises in China. Computational experiments demonstrate that the models and algorithms developed can make an optimal planning in a computationally efficient manner to improve the steel production. © 2015, IFAC Hosting by Elsevier Ltd.

关键词： Steelmaking

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Observer-Based Fault Tolerant Consensus of Linear Multi-Agent Systems

Observer-Based Fault Tolerant Consensus of Linear Multi-Agen...

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第27届中国控制与决策会议

作者： Zhiqiang Zuo Jun Zhang Yijing Wang Tianjin Key Laboratory of Process Measurement and Control School of Electrical Engineering and AutomationTianjin University

ISBN: (纸本)9781479970186

This paper considers the consensus problem of linear multi-agent systems with actuator *** communication topology is undirected ***,an observer is designed to estimate each agent's states and *** on the general faulty agent model and the observer's states,we then propose fault tolerant control protocol and the corresponding conditions to achieve ***,numerical examples are given to illustrate the theoretical results.

关键词： Observer-based protocol Multi-agent systems Consensus Actuator fault

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Frequency Identification for MIT Detection of EEG Based on Wavelet Energy

Frequency Identification for MIT Detection of EEG Based on W...

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IEEE International Instrumentation and Measurement Technology Conference

作者： Zhili Xiao Yan Fu Chao Tan Feng Dong Tianjin Key Laboratory of Process Measurement and Control School of Electrical Engineering and Automation Tianjin University Tianjin China

ISBN: (纸本)9781479961153

In current applications of magnetic induction tomography (MIT) in brain functional imaging, brain tissue is assumed as medium with homogeneous conductivity, and the electroencephalogram (EEG) is neglected. In order to study the effects of EEG signals on MIT detection results, a 2-D four-layer brain model is established by finite element simulation. Izhikevich neuron model is employed to simulate electrical activities of neurons. Three kinds of typical neurons electrical activities are discussed as internal signals. They are regular spiking, fast-spiking, thalamo-cortical for depolarization, respectively. Wavelet energy combined with FFT method is used to analyze the identification of the detection results for the signal with different patterns. The results show that, EEG is detectable by MIT. According to processing results by the wavelet energy combined with FFT method, the patterns of neurons activity signals can be identified through the frequency components.

关键词： magnetic induction tomography signal recognition electroencephalogram Izhikevich neuron model wavelet energy

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Robust output feedback NMPC with guaranteed constraint satisfaction

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IFAC-PapersOnLine 2015年第14期48卷 326-331页

作者： Sankaranarayanan Subramanian Sergio Lucia Radoslav Paulen Sebastian Engell Process Dynamics and Operations Group TU Dortmund Otto-von-Guericke-University Magdeburg Laboratory for Systems Theory and Automatic Control Institute of Automation Engineering Germany

Nonlinear Model Predictive control (NMPC) employs a plant model to compute a sequence of optimal control inputs for a finite horizon. As, in reality, there always exists a plant-model mismatch and not all states of the plant can be measured, the NMPC scheme must be robust to plant uncertainties and to estimation errors. Different robust NMPC strategies have been proposed to deal with these uncertainties. Among them, a multi-stage NMPC, which is based upon a scenario tree of future plant evolutions, is less conservative compared to worst-case open-loop approaches because the presence of feedback at future sampling instants is explicitly considered. In multi-stage output feedback NMPC, additional scenarios are created by sampling the innovations that are used to estimate the future states of the plant along the scenario tree. In this paper, we refine our previously published approach to include state estimation errors. Moreover we extend the scheme to guarantee robust constraint satisfaction by calculating reachable sets using Taylor models. The method is demonstrated for a nonlinear chemical process example.

关键词： Predictive control Robust control Output feedback Nonlinear control systems

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Multi-source information fusion model in rule-based Gaussian-shaped fuzzy control inference system incorporating Gaussian density function

Multi-source information fusion model in rule-based Gaussian...

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作者： Li, Zairan He, Ting Cao, Luying Wu, Tunhua McCauley, Pamela Balas, Valentina E. Shi, Fuqian Tianjin Key Laboratory of Process Measurement and Control School of Electrical Engineering and Automation Tianjin University Tianjin China Wenzhou Vocational and Technical College Wenzhou China College of Information and Engineering Wenzhou Medical University Wenzhou325035 China Department of Industrial Engineering and Management Systems University of Central Florida OrlandoFL United States Department of Automation and Applied Informatics Aurel Vlaicu University of Arad Romania

An increasing number of applications require the integration of data from various disciplines, which leads to problems with the fusion of multi-source information. In this paper, a special information structure formalized in terms of three indices (the central presentation, population or scale, and density function) is proposed. Single and mixed Gaussian models are used for single source information and their fusion results, and a parameter estimation method is also introduced. Furthermore, fuzzy similarity computing is developed for solving the fuzzy implications under a Mamdani model and a Gaussian-shaped density function. Finally, an improved rule-based Gaussian-shaped fuzzy control inference system is proposed in combination with a nonlinear conjugate gradient and a Takagi-Sugeno (T-S) model, which demonstrated the effectiveness of the proposed method as compared to other fuzzy inference systems. © 2015 - IOS Press and the authors. All rights reserved.

关键词： Fuzzy control

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Robust Adaptive control Design for Rotorcraft Unmanned Aerial Vehicles Based on Sliding Mode Approach

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Transactions of Tianjin University 2014年第6期20卷 393-401页

作者：郭建川鲜斌 Tianjin Key Laboratory of Process Measurement and Control School of Electrical Engineering and AutomationTianjin University

This paper presents a nonlinear robust control design method for a generic rotorcraft unmanned aerial vehicle(RUAV). The control objective is to let the RUAV track some pre-defined time-varying position and heading trajectories. The proposed controller employs feedback linearization process to realize the dynamic decoupling control and applies adaptive sliding mode control to compensate for the parametric uncertainties and external disturbances. The global asymptotical stability is proved via stability analysis. Compared with the cascaded controller, the proposed controller demonstrates a superior tracking performance and robustness through numerical simulation in the presence of parametric uncertainties and unknown disturbances.

关键词： rotorcraft unmanned aerial vehicle (RUAV) nonlinear robust control sliding mode control parametricuncertainty wind gust disturbance

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Fuzzy Inference Algorithm based on Quantitative Association Rules

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Procedia Computer Science 2015年 61卷 388-394页

作者： Ling Wang Ji-Yuan Dong Shu-Lin Li School of Automation & Electrical Engineering University of Science and Technology Beijing 100083 China Key Laboratory of Advanced Control of Iron and Steel Process (Ministry of Education) Beijing 100083 China

In order to develop a data mining system to extract the fuzzy inference rules from the data, in this paper a fuzzy inference algorithm based on quantitative association rule (FI-QAR) is proposed. First, a discretization algorithm based on an improved clustering for each dimension data is adopted, and then the quantitative results are represented in the form of a Nominal variables matrix to compute the support and confidence level in the Apriori algorithm for quantitative association rules mining. On the basis of this, the quantitative association fuzzy rules are reconstructed by combing with TS fuzzy model to realize fuzzy inference, which can be applied to predict the output class and precise output. Experiment results demonstrated that the proposed algorithm is feasible and practical.

关键词： quantitative association rules apriori algorithm discretization TS fuzzy rules

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Sensitivity matrix construction based on ultrasound modulation for electrical resistance tomography

Sensitivity matrix construction based on ultrasound modulati...

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IEEE International Workshop on Imaging Systems and Techniques (IST)

作者： Xizi Song Yanbin Xu Feng Dong Tianjin Key Laboratory of Process Measurement and Control School of Electrical Engineering and Automation Tianjin University Tianjin P.R. China

Image reconstruction of electrical resistance tomography (ERT) is an inherently nonlinear inverse problem. Sensitivity matrix is widely adopted to make this inverse problem to be a linear one. Usually, the sensitivity matrix employed is calculated under a uniform conductivity distribution. However, it is different from the sensitivity matrix of the measured object with inclusions, and the difference between them affects the quality of reconstructed image. Aiming at improving the resolution of reconstructed images, a novel way of constructing the sensitivity matrix is proposed based on ultrasound modulation. With focused ultrasound perturbing the measured object, the conductivity in each focal region will be altered according to the acousto-electric effect. Measuring the boundary voltage change with the corresponding change of the conductivity, then the sensitivity matrix of the measured object will be approximately constructed. The sensitivity matrices constructed based on the ultrasound modulation and on the Geselowitz's sensitivity theorem are presented and analyzed. With the proposed construction method, sensitivity matrix is more sensitive to the inclusion, even in the center of the measured object. Besides, image reconstruction is carried out by sensitivity algorithm using these two kinds of sensitivity matrix. Simulation results indicate that the reconstructed images with higher quality can be obtained with sensitivity matrix constructed based on the ultrasound modulation.

关键词： Sensitivity Image reconstruction Ultrasonic imaging Conductivity Modulation Ultrasonic variables measurement Conductivity measurement

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