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摘要: This paper is focussed on the extremum seeking online tuning of a shunted piezoelectric vibration absorber for the broadband control of the resonant response of a mechanical system subject to a stationary stochastic excitation. Two shunt circuits are considered, which are formed by a resistor and an inductor connected either in series or in parallel. The two components are tuned in such a way as to maximise the time-averaged electric power absorbed by the shunt, that is the time-averaged electri关键词: Extremum seeking control algorithm;Vibration power maximisation;Adaptive vibration absorber;Piezoelectric vibration absorber;Online tuning;Broadband vibration control
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Journal
Niu Xiaopeng;Zhu Shun-Peng;He Jin-Chao;Liao Ding;Correia José A.F.O.;Berto Filippo;Wang Qingyuan;
International Journal of FatigueVolume 160, Issue , 2022, PP
摘要: Despite the significant advantages such as rapid prototyping of complex structures, engineering application of Additive Manufacturing (AM) technique has been limited due to the weak fatigue performance and lacking of fatigue design rules of AM parts. Particularly, this application relies on the improvement of AM processing technique and integrity assessment of AM parts, the latter usually demands costly and time-consuming fatigue tests, especially for full-scale tests. Accordingly, the size effe关键词: Extremum value statistics;Size effect;Fatigue strength;Additive manufacturing;Defect-tolerant assessment
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摘要: The maximum resistance rate principle (MRRP) is proposed to characterise the unstable of quasi-brittle fracture. Under quasi-static loading conditions, the unstable fracture of quasi-brittle materials occurs when the resistance rate reaches its maximum value. Firstly, the whole fracture process of the single edge cracked specimen was calculated, and the MRRP was elaborated based on the calculated fracture resistance and resistance rate curve. Then, the MRRP was verified by existing experimental 关键词: Quasi-brittle fracture;Fracture resistance;Resistance curve;Resistance rate;Fracture extremum theory
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Journal
摘要: The extremum probability density evolution method (EPDEM) was introduced for the life-cycle risk analysis of the roofs of low-rise buildings subjected to typhoons. This method can use small sample sizes to account for the uncertainties of winds during the entire track of a typhoon and the changes in resistance of structures over time. This study generated typhoons in Shanghai, China using the Yan Meng wind field model. The EPDEM-based wind load analysis combined with a wind tunnel test was used 关键词: Extremum probability density evolution method (EPDEM);Low-rise buildings;Typhoon;Wind loads;Risk analysis
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Book Chapter
摘要: On-board acceleration measurements bear significant potential for the early detection of damage to railway infrastructure components. Condition assessment forms a complex problem in this case, due to the mobile nature of the On Board monitoring (OBM) solution, and the uncertainties associated with the rail-wheel contact dynamics, a lack of knowledge on the excitation sources (track, rail and wheel irregularities, parameter and self excitation) and the variability of the environmental and operati关键词: Extreme value analysis;Regression analysis;Axle box accelerations
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Journal
摘要: A semi-autogenous grinding mill is simulated with gradient and non-gradient based extremum seeking controllers to maximize the mill performance using grind curves. Grind curves map the essential performance measures of a grinding mill to the mill load and rotational speed. The curves vary with the changes in the feed ore characteristic but show generic parabolic features with extremums. The extremum seeking controllers search along the unknown input–output map to steer the process towards an unk关键词: Comminution;Extremum seeking control;Grind curves;Grinding mill;Modelling;Process control;Simulation
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Book Chapter
摘要: This chapter presents a number of lifetime distributions, including the exponential, Weibull, gamma, lognormal, and log‐logistic. It considers some distributions that are related to these, such as the extreme value distribution. The choice of a lifetime distribution is important, because these distributions have different properties, especially in the left and right tails. The simplest model for lifetimes is the exponential distribution. The Weibull distribution has two parameters and is more fl关键词: exponential distribution;gamma distribution;location‐scale distribution;log‐logistic distributions;lognormal distribution;smallest extreme value distribution;Weibull distribution
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Book Chapter
摘要: Presently, due to change in the climatic scenario, India is witnessing increase in intensity/frequency of the extreme tropical cyclonic events and its associated disasters not only on the east coast of Indian peninsula but also on west coast, on the remote islands situated in the Arabian Sea. As such coastal structures situated on remote islands in Arabian Sea are also likely to get exposed to intensified extreme events in near future which may lead to damage/collapse of the structures, if they 关键词: Extreme wave heights;Generalized extreme value distribution;Hindcast;Storm surges
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Book Chapter
摘要: Analysis of trend in rainfall is one of the important aspects to study about the temporal and spatial variations in nature, and assessment of extreme rainfall is a pre-requisite for planning, design and management of civil and hydraulic structures. For this purpose, Mann–Kendall (MK) test is applied for detecting a trend in rainfall data whereas Extreme Value Analysis (EVA) by fitting probability distributions such as Extreme Value Type-1, 2-parameter log normal and log Pearson type-3 (LP3) to t关键词: Chi-square;D-index;Extreme Value Type-1;Kolmogorov-Smirnov;Log Normal;Log Pearson Type-3;Mann–Kendall;Rainfall;Trend analysis
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Journal
摘要: The improvement in battery pack efficiency and battery equalization is critical for the Lithium-ion battery system. However, the strategy designed for the improvement still suffers from problems such as unknown efficiency for each cell and complex operation conditions. In this paper, a model-free and adaptive optimization method, extremum seeking control (ESC), for improving the efficiency and the battery equalization of the battery pack under different power loads and different external conditi关键词: Extremum seeking control;Lithium-ion battery;Efficiency;Battery equalization;Optimization
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Journal
摘要: With the continuous development of human society, people's over-exploitation of nature leads to frequent environmental problems. A large number of floating objects appear on lakes, rivers, reservoirs and other water surfaces. Water floats have seriously damaged the ecological environment and directly threatened the survival and development of human beings. Therefore, for the sustainable development of human beings, we must solve the problem of water pollution. The detection of floating pollutant关键词: Floating pollutant image;Immune extremum region;Pollutant image target extraction
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Journal
摘要: This article studies the extremum seeking control (ESC) problem for a class of constrained nonlinear systems. Specifically, we focus on a family of constraints that allows to reformulate the original nonlinear system in the so‐called input–output normal form. To steer the system to optimize a performance function without knowing its explicit form, we propose a novel numerical optimization‐based extremum seeking control (NOESC) design consisting of a constrained numerical optimization method and 关键词: constrained numerical optimization;extremum seeking control;finite‐time state transition;output constraints
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Book Chapter
摘要: The prediction of magnitude of extreme flood events for a given return period is crucial for planning and designing of hydraulic structures. The most common method of estimating design flood value at a site for a given return period is by frequency analysis. As the method is based on the limited historical discharge data, the estimated design flood is associated with uncertainty. This uncertainty is represented by the confidence interval. In this paper, the annual maximum flow series for period 关键词: Bootstrap method;Design flood;Confidence interval;Extreme value Type-I;Log Pearson Type-III
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Book Chapter
摘要: As researchers are increasingly interested in natural disasters and economic problems, developing solutions to predict that is highly recommended. In this paper, we focus on the use of the Extreme Values Theory (EVT) especially the Gumbel distribution, for modelling and predicting the maximum data of extreme events in a time series. To achieve this goal, first we have to demonstrate that the time series formed by the maximum values converges to the Gumbel distribution. Then by applying several f关键词: Extreme value theory;Gumbel distribution;Linear curve fitting;Fitting methods;Manual fitting;Automation fitting
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Book Chapter
摘要: This chapter describes first the preprocessing of the image necessary for a successful edge detection. It consists of noise reduction with the Sigma filter and of sharpening the edges with the extreme filter. A new algorithm for edge detection is described. It is faster and more precise than the known algorithms.关键词: Edge detection;Preprocessing;Drawbacks of Median;Sigma filter;Extreme value filter;New method of edge detection;Color difference;Comparison with Canny edge detection;Edges in color images;Applications of edge detection;Recognition of bicycles
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Book Chapter
摘要: Human activity recognition (HAR) is the method for identifying a person’s activity using sensors that sense and capture movements during activity. HAR is an evolving area of research in computing, applied to sensors found in smartphones, smartwatches, and cameras. This paper illustrates how to identify some types of human activities using a BioStamp sensor that consists of an inertial sensors-based smart patch. Our dataset has five activities: stair climbing, jogging, skipping, kettlebell liftin关键词: Human activity recognition;Accelerometer;Gyroscope;Electrode values;Classification;Feature extraction
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Book Chapter
摘要: Extreme rainfall values are required by hydrologist and water resources professional for designing various water structures specifically for urban drainage, small and medium hydraulic structures, irrigation drainage works, etc. This study estimates annual one-day point maximum rainfall using extreme value (EV-I) distribution (Gumbel) of a small town in the foothills of the Himalayas. The parameters of the EV-I distributions are estimated using three different estimation methods, i.e. method of L关键词: Extreme rainfall;Extreme value distribution;L-moment;Frequency factor;Return period;Drainage
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Journal
摘要: This paper is concerned with a novel stochastic bifurcation and its discrimination of stochastic dynamical system. A new kind of stochastic response—called extremely possible response and a novel stochastic bifurcation—called stochastic extremum bifurcation is defined for the first time. An entirely new method for discriminating stochastic bifurcation is proposed based on the new definition mentioned above. In addition, the classical Van der Pol oscillator is used as the illustrative example to 关键词: Stochastic bifurcation;Stochastic dynamic system;Bifurcation discrimination;Stochastic extremum bifurcation
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Journal
摘要: In the presented paper it is investigated the influence of the subjective perception of the objectively existing security values upon the security measures and indicators in the framework of the subjective entropy maximum principle. The subjective analysis theory entropy paradigm makes it possible to consider the security system based upon dynamic parameters as an active system governed by an individual (active element of the managerial system) with the help of her/his individual subjective pref关键词: Security;Object;Subject;Functional;Entropy;Uncertainty;Optimization;Preference function;Extremum
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Book Chapter
摘要: We consider a control problem associated with a mathematical model of temperature control in industrial greenhouses. It is based on a one-dimensional non-self-adjoint parabolic equation with variable coefficients. Defining the optimal control as the minimizer quadratic functional with point observation, we prove the existence of the minimizer and obtain necessary conditions.关键词: Parabolic equation;Extremum problem;Quadratic functional;Minimizer;Necessary condition;35Q93;49J20;49K20
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Journal
摘要: In this paper, we consider a class of nonlinear time-varying systems that are subject to uncontrolled inputs. Those inputs may represent, for instance, disturbances, time-varying parameters, or model uncertainties. Exploiting the stability properties of an extended system, a so-called Lie-bracket system, we derive stability properties of the original system. Those stability results, in the spirit of input-to-state stability, are then applied to the case where the dynamical system is an extremum 关键词: Lie-bracket approximation;Input-to-state stability;Extremum seeking;Time-varying optimum;Noise
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Journal
摘要: We investigate robustness and averaging properties of an extremum seeking scheme which employs oscillatory dither signals with sufficiently large amplitudes and frequencies. Our study takes both input and output disturbances into account. We consider general L∞-disturbances, which may correlate with the oscillatory dither signals. A suitable change of variables followed by an averaging procedure reveals that the closed-loop system approximates the behavior of an averaged system. The disturbances关键词: Extremum seeking control;Robustness;Averaging;Practical stability
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Journal
摘要: This paper proposes a Log-Power Proportional-Integral Extremum Seeking Control (LP-PIESC) framework for maximizing the power capture of a wind turbine operating at below-rated wind speeds, i.e., the so-called region-2 of a turbine’s power curve. Extremum seeking control (ESC) has emerged as a viable algorithm to maximize energy capture for a wind turbine operating in region-2. Despite the encouraging results of early ESC strategies, the basic algorithm suffers from slow and inconsistent converge关键词: wind turbine power maximization;proportional-integral extremum seeking control (PIESC);log-of-power (LP) feedback
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Journal
摘要: A nonlinear correction technique for finite element methods to anisotropic diffusion problems on general triangular and quadrilateral meshes are introduced. The classic linear or bi-linear finite element methods are modified, and then the resulting schemes satisfy the discrete strong extremum principle unconditionally, which means that it is unnecessary to impose the well-known restrictions on diffusion coefficients and geometry of mesh-cell (e.g. “acute angle” condition). Convergence rate for s关键词: Discrete extremum principle;Diffusion equation;Finite element method;Finite volume method
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Journal
摘要: In this paper, an extremum‐preserving finite volume scheme is constructed for the two‐dimensional three‐temperature (2D 3‐T) radiation diffusion equations. The harmonic averaging points located at cell edge are applied to define the auxiliary unknowns, and the primary unknowns are defined at cell center. This scheme has a fixed stencil and satisfies the local conservation condition and discrete extremum principle. The existence of discrete solution is proved by using the fixed point theorem. Mor关键词: distorted meshes;extremum‐preserving principle;finite volume scheme;three‐temperature radiation diffusion equations
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Journal
摘要: In this paper, we present a constructive approach to extremum seeking (ES) by using a time-delay approach to averaging. We consider gradient-based ES of static maps in the case of one and two variables, and we study two ES methods: the classical one and a more recent bounded ES method. By transforming the ES dynamics into a time-delay system where the delay is the period of averaging, we derive the practical stability conditions for the resulting time-delay system. The time-delay system stabilit关键词: Extremum seeking;Averaging;Time-delay
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摘要: In a seminal paper “Volumen und Oberfläche” (1903), Minkowski introduced the basic notion of mixed volumes and the corresponding inequalities that lie at the heart of convex geometry. The fundamental importance of characterizing the extremals of these inequalities was already emphasized by Minkowski himself, but has to date only been resolved in special cases. In this paper, we completely settle the extremals of Minkowski’s quadratic inequality, confirming a conjecture of R. Schneider. Our proof关键词: mixed volumes;Minkowski’s quadratic inequality;Alexandrov–Fenchel inequality;extremum problems;convex geometry
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摘要: In practice, data‐driven control and optimization techniques are applied to address problems in engineering systems of which the model is either unavailable or so complicated that a model‐based analytic design can be hardly carried. Among them, the extremum seeking (ES) is a popular model‐free or data‐driven optimization method that has been effectively applied to provide optimal solutions to various industrial control systems. In this article, a new design philosophy, called the model‐guided ES关键词: automotive engine;extremum seeking;LiDAR;model‐guided data‐driven optimization
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摘要: For the Gellerstedt equation with a singular coefficient in some mixed domain, when the ellipticity boundary coincides with the segment of the Oy axis and the normal curve of the equation, a problem with the Bitsadze–Samarskii conditions on the elliptic boundary and on the degeneration line is studied. The well-posedness of the formulated problem is proved.关键词: extremum principle;uniqueness of a solution;Tricomi singular integral equation;existence of a solution;kernel with a first-order singularity at an isolated singular point;Wiener–Hopf equation;index
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摘要: In this article we study two classical potential-theoretic problems in convex geometry. The first problem is an inequality of Brunn-Minkowski type for a nonlinear capacity, $\operatorname {Cap}_{\mathcal {A}},$ where $\mathcal {A}$-capacity is associated with a nonlinear elliptic PDE whose structure is modeled on the $p$-Laplace equation and whose solutions in an open set are called $ \mathcal {A}$-harmonic. \par In the first part of this article, we prove the Brunn-Minkowski inequality for this关键词: The Brunn-Minkowski inequality;nonlinear capacities;inequalities and extremum problems;potentials and capacities;$\mathcal{A}$-harmonic PDEs;Minkowski problem;variational formula;Hadamard variational formula
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