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3D reconstruction of single rising bubble in water using digital image processing and characteristic matrix

Particuology 2013年第2期11卷 170-183页

作者： Yuchen Bian Feng Dong Weida Zhang Hongyi Wang Chao Tan Zhiqiang Zhang Tianjin Key Laboratory of Process Measurement and Control School of Electrical Engineering and AutomationTianjin University School of Electrical Engineering and Automation Tianjin Polytechnic University

Reconstructing the shape of a bubble will lay a firm foundation for further description of the dynamic characteristics of bubbly flow, especially for a single rising bubble or separate bubbles whose interaction could be neglected. In this case, the rising bubble is usually simulated as an ellipsoid consisting of two semi-eUipsoids up and down. Thus the projected image of a bubble consists of two semi-ellipses. In this paper, a method for reconstructing the ellipsoid bubble model is described following digital image processing, using the Hough transform in 2D ellipse parameter extraction which could cover most of the bubble edge points in the image. Then a method based on characteristic symmetric matrix is described to detect 3D bubble ellipsoid model parameters from 2D ellipse parameters of projection planes. This method can be applied to bubbles rising with low-velocity in static flow field much in conformity with the projection theory and the shape variation of the rising bubble. This method does not need to solve nonlinear equation sets and provides an easy way to calculate the characteristic matrix of a space ellipsoid model for deformed bubble. For bubble application, two assumed conditions and a calibration factor are proposed to simplify calculation and detection. Errors of ellipsoid center and three axes are minor. Errors of the three rotation angles have no negative effect on further study on bubbly flow.

关键词： Bubble Digital image processing Parameter extraction Ellipsoid model Reconstruction Characteristic matrix

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A Survey of Recent Results in Quantized and Event-based Nonlinear Control

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International Journal of automation and computing 2015年第5期12卷 455-466页

作者： Zhong-Ping Jiang Teng-Fei Liu Polytechnic School of Engineering New York University State Key Laboratory of Synthetical Automation for Process Industries Northeastern University

Constructive nonlinear control design has undergone rapid and significant progress over the last three decades. In this paper, a review of recent results in this important field is presented with a focus on interdisciplinary topics at the interface of control,computing and communications. In particular, it is shown that the nonlinear small-gain theory provides a unified framework for solving problems of quantized feedback stabilization and event-triggered control for nonlinear systems. Some open questions in quantized and networked nonlinear control systems are discussed.

关键词： Nonlinear systems nonlinear control quantized cont

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Robust fault detection filter design for a class of time-delay systems via equivalent transformation

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控制理论与应用（英文版） 2013年第1期11卷 54-60页

作者： Jilie ZHANG Huaguang ZHANG Feisheng YANG Shenquan WANG School of Information Science and Engineering Northeastern University State Key Laboratory of Synthetical Automation for Process Industries (Northeastern University)

This paper is concerned with the robust fault detection filter （RFDF） design for a class of linear time- invariant systems （LTISs） with output state time delays. Although existing results in literatures study the RFDF for time- delay systems, few is concerned with the output state time-delay systems. The basic idea of our study is to eliminate the time delays of system and transform it to a delay-free system （i.e., a linear time-invariant system without time delays） by the bicausal change of coordinates approach. Then, we design the RFDF for the delay-free LTIS, which is equivalent to the original system with time delays. We first introduce a class of systems with output state time delays, whose fault can be detected by using the RFDF design approach for delay-free systems. Then, since the RFDF design problem can be formulated as a standard H-infinity-model matching problem, it is solved by using H-infinity-optimization LMI techniques. In the last, the adaptive threshold of fault detection is chosen and an illustrative design example is used to demonstrate the validity of the design approach.

关键词： Equivalent transformation Robust fault detection filter Output state time-delay system

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Fault detection and diagnosis of components of the vehicle vertical dynamics

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MECCANICA 1997年第5期32卷 459-472页

作者： Weispfenning, T Darmstadt University of Technology Institute of Automatic Control Laboratory of Control Engineering and Process Automation D-64283 Darmstadt Germany

In this paper, model and signal-based methods for supervision of suspension elements of a car are presented. A model-based approach using parameter estimation is used to determine the current parameters of a vehicle suspension. Exploiting the analytical redundancy, different faults, like weak dampers or sensor faults, can be distinguished. For fault detection the use of parity equations is shown. In addition, a signal-based approach is presented which makes a detection of tire pressure loss possible. All presented results were drawn from a test rig or from a driving car.

关键词： vehicle dynamics diagnostics suspension signal analysis automotive applications

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Circle formation control for multi-agent systems with a leader

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Control Theory and Technology 2015年第1期13卷 82-88页

作者： Lianjie ZHAO Dan MA College of Information Science and Engineering Northeastern University State Key Laboratory of Synthetical Automation for Process Industries Northeastern University

In this paper, we focus on circle formation control of multi-agent systems （MAS） with a leader. The circle formation is achieved based on the lead-following and the artificial potential field method. A distributed control law is given to make a group of agents form a circle and consequently achieve an expected angle. Finally, simulation results show that the proposed circle formation strategies are effective.

关键词： Circle formation artificial potential field method multi-agent systems distributed control

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A Non-canonical Example to Support P Is Not Equal to NP

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Transactions of Tianjin University 2011年第6期17卷 446-449页

作者：杨正瓴 School of Electrical Engineering and Automation Tianjin University Tianjin Key Laboratory of Process Measurement and Control

The more unambiguous statement of the P versus NP problem and the judgement of its hardness, are the key ways to find the full proof of the P versus NP problem. There are two sub-problems in the P versus NP problem. The first is the classifications of different mathematical problems (languages), and the second is the distinction between a non-deterministic Turing machine (NTM) and a deterministic Turing machine (DTM). The process of an NTM can be a power set of the corresponding DTM, which proves that the states of an NTM can be a power set of the corresponding DTM. If combining this viewpoint with Cantor's theorem, it is shown that an NTM is not equipotent to a DTM. This means that "generating the power set P(A) of a set A" is a non-canonical example to support that P is not equal to NP.

关键词： P versus NP computational complexity theory Cantor＇s theorem power set continuum hypothesis

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Analytical Fitting Functions of Finite Sample Discrete Entropies of White Gaussian Noise

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Transactions of Tianjin University 2015年第4期21卷 299-303页

作者：杨正瓴冯勇熊定方陈曦张军 School of Electrical Engineering and Automation Tianjin University Tianjin Key Laboratory of Process Measurement and Control

In order to find the convergence rate of finite sample discrete entropies of a white Gaussian noise(WGN), Brown entropy algorithm is numerically *** the increase of sample size, the curves of these finite sample discrete entropies are asymptotically close to their theoretical *** confidence intervals of the sample Brown entropy are narrower than those of the sample discrete entropy calculated from its differential entropy, which is valid only in the case of a small sample size of WGN. The differences between sample Brown entropies and their theoretical values are fitted by two rational functions exactly, and the revised Brown entropies are more efficient. The application to the prediction of wind speed indicates that the variances of resampled time series increase almost exponentially with the increase of resampling period.

关键词： entropy non-stationary time series prediction white Gaussian noise sample size wind speed

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Robust H-infinity filtering for uncertain discrete-time systems using parameter-dependent Lyapunov functions

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控制理论与应用（英文版） 2013年第1期11卷 122-127页

作者： Xiaoheng CHANG Guanghong YANG College of Engineering Bohai University Key Laboratory of Integrated Automation for the Process Industry Ministry of Education and College of Information Science and Engineering Northeastern University

This paper deals with H-infinity filtering of discrete-time systems with polytopic uncertainties. The un- certain parameters are supposed to reside in a polytope. By using the parameter-dependent Lyapunov function approach and introducing some slack matrix variables, a new sufficient condition for the H-infinity filter design is presented in terms of solutions to a set of linear matrix inequalities （LMIs）. In contrast to the existing results for H-infinity filter design, the main advantage of the proposed design method is the reduced conservativeness. An example is provided to demonstrate the effectiveness of the proposed method.

关键词： Discrete-time systems H-infinity filtering Parameter-dependent Lyapunov function Linear matrix in- equalities （LMIs）

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Quadratic Radical Function Better Than Fisher z Transformation

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Transactions of Tianjin University 2013年第5期19卷 381-384页

作者：杨正瓴段志峰王晶晶王腾宋延文张军 School of Electrical Engineering and Automation Tianjin University Tianjin Key Laboratory of Process Measurement and Control

A new explicit quadratic radical function is found by numerical experiments,which is simpler and has only 70.778%of the maximal distance error compared with the Fisher z ***,a piecewise function is constructed for the standard normal distribution:if the independent variable falls in the interval(-1.519,1.519),the proposed function is employed;otherwise,the Fisher z transformation is *** with the Fisher z transformation,this piecewise function has only 38.206%of the total *** new function is more exact to estimate the confidence intervals of Pearson product moment correlation coefficient and Dickinson best weights for the linear combination of forecasts.

关键词： normal distribution cumulative distribution function error function confidence interval correlation coefficient combination of forecasts

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Distributed Online Convex Optimization with Time-Varying Constraints: Tighter Cumulative Constraint Violation Bounds under Slater's Condition

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IEEE Transactions on Automatic Control 2025年

作者： Yi, Xinlei Li, Xiuxian Yang, Tao Xie, Lihua Hong, Yiguang Chai, Tianyou Johansson, Karl H. National Key Laboratory of Autonomous Intelligent Unmanned Systems Shanghai Institute of Intelligent Science and Technology China Ministry of Education Frontiers Science Center for Intelligent Autonomous Systems China Massachusetts Institute of Technology Lab for Information & Decision Systems CambridgeMA02139 United States Northeastern University State Key Laboratory of Synthetical Automation for Process Industries Shenyang110819 China Nanyang Technological University School of Electrical and Electronic Engineering 50 Nanyang Avenue 639798 Singapore Kth Royal Institute of Technology Division of Decision and Control Systems School of Electrical Engineering and Computer Science Sweden Digital Futures Stockholm10044 Sweden

This paper considers distributed online convex optimization with time-varying constraints. In this setting, a network of agents makes decisions at each round, and then only a portion of the loss function and a coordinate block of the constraint function are privately revealed to each agent. The loss and constraint functions are convex and can vary arbitrarily across rounds. The agents collaborate to minimize static network regret and network cumulative constraint violation. A novel distributed online algorithm with a vanishing stepsize is proposed and it achieves an O(Tmax {c,1-c}) static network regret bound and an O(T1-c/2) network cumulative constraint violation bound, where T is the number of rounds and c∈ (0,1) is a user-defined trade-off parameter. When Slater's condition holds (i.e, there is a point that strictly satisfies the inequality constraints), the network cumulative constraint violation bound is reduced to O(T1-c). Moreover, if the loss functions are strongly convex, then static network regret bound is reduced to O(log (T)), and the network cumulative constraint violation bound is reduced to O(√log (T)T) and O(log (T)) without and with Slater's condition, respectively. To the best of our knowledge, this paper is the first to achieve tighter (network) cumulative constraint violation bounds for (distributed) online convex optimization with time-varying constraints under Slater's condition. Finally, the theoretical results are verified through numerical simulations. © 1963-2012 IEEE.

关键词： Convex optimization

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