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Quadratic stabilization of a nonlinear aeroelastic system using a novel Neural-Network-based controller

Science China(Technological Sciences) 2011年第5期54卷 1126-1133页

作者： D. SFFKER Chair of Dynamics and Control University of Duisburg-Essen

This contribution proposes a novel neural-network-based control approach to stabilize a nonlinear aeroelastic wing section. With the prerequisite that all the states of the system are available, the proposed controller requires no comprehensive information about structural nonlinearity of the wing section. Furthermore, the proposed control approach requires no human intervention of designing goal dynamics and formulating control input function, which is difficult to be realized by the typical neural-network-based control following an inverse control scheme. Simulation results show that the proposed controller can stabilize the aeroelastic system with different nonlinearities.

关键词： quadratic stabilization neural-network nonlinear aeroelastic control cognition

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Pointwise constraints for scalar conservation laws with positive wave velocity

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Zeitschrift für angewandte Mathematik und Physik 2025年第3期76卷 1-17页

作者： De Nitti, Nicola Serre, Denis Zuazua, Enrique EPFL Institut de Mathématiques Lausanne Switzerland UMPA Ecole Normale Supérieure de Lyon Lyon Cedex 07 France Department of Mathematics Chair for Dynamics Control Machine Learning and Numerics (Alexander von Humboldt Professorship) Friedrich-Alexander-Universität Erlangen-Nürnberg Erlangen Germany Chair of Computational Mathematics Fundación Deusto Bilbao Spain Departamento de Matemáticas Ciudad Universitaria de Cantoblanco Universidad Autónoma de Madrid Madrid Spain

We consider a conservation law with strictly positive wave velocity and study the well-posedness of a suitable notion of solution for the associated initial value problem under a flux constraint active in the half-line $${\mathbb {R}}_+$$ . The strict positivity of the wave velocity allows for the dynamics in the unconstrained region $${\mathbb {R}}_-$$ to be fully determined by the restriction of the initial data to $${\mathbb {R}}_-$$ . On the other hand, the solution in the constrained region is dictated by the assumption that the total mass of the initial datum is conserved along the evolution. We formulate the transmission condition at the interface $$\{x=0\}$$ in such a way that the boundary datum for the initial boundary value problem posed on $${\mathbb {R}}_+$$ is given by the largest incoming flux that is admissible under the constraint, while the exceeding mass is accumulated in a “buffer” (as an atomic measure concentrated at the interface).

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Experimental study on the micro-mechanism and compressive strength of concrete with calcined coal gangue coarse aggregate

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Case Studies in Construction Materials 2025年 22卷

作者： Hao, Shengpeng Xu, Wenyu May, Bambesiwe M. Zhang, Zhenyu Zhang, Yuyu State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing University Chongqing400044 China Research Group Chongqing University Chongqing400044 China African Rainbow Minerals Geometallurgy Chair Department of Earth Sciences Stellenbosch University Stellenbosch7600 South Africa Department of Civil Geological and Mining Engineering Polytechnique Montréal MontréalQCH3T 1J4 Canada

Coal gangue, a byproduct of coal beneficiation, has low strength and high carbon content, which negatively affects the mechanical properties of concrete when used as a substrate for natural gravel. However, high temperature calcination can activate its pozzolanic properties, improving its suitability for concrete production. This study investigates the microstructural and mechanical property of concrete incorporated with calcined coal gangue coarse aggregate at different temperatures (500°C, 600°C, 700°C, and 800°C). The experimental results indicate that metakaolin in coal gangue begins to decompose at 500°C, increasing the content of reactive SiO2 and Al2O3, which participate in secondary hydration reactions with calcium hydroxide (CH). This process forms additional calcium silicate hydrate (C-S-H) gel, ettringite (AFT) crystals, and afwillite, enhancing the concrete microstructure. Notably, coal gangue concrete calcined at 800°C exhibited a porosity of 1.29 % and a compressive strength of 38 MPa after 28 days of curing, meeting the C30 concrete standard. Furthermore, the correlation between the compressive strength of CCGC and its microstructure exceeded 0.72, indicating that fractal dimension analysis is an effective method for predicting concrete strength. © 2025 The Authors

关键词： Coal tailings

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Virtual Sensors for Diagnosis and Prognosis Purposes in the Context of Elastic Mechanical Structures

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IEEE Sensors Journal 2009年第11期9卷 1577-1588页

作者： Heidtmann, Frank Söffker, Dirk Chair of Dynamics and Control Engineering Faculty University of Duisburg-Essen Germany

—This contribution deals with a model-based approach for diagnosis and prognosis tasks in the context of elastic mechanical structures in conjunction with the Safety and Reliability control Engineering (SRCE) concept. In elastic mechanical structures, faults are given by structural changes in mass and/or stiffness, caused by cracks, loss of material or, for example, by the internal delamination processes of carbon fiber laminate materials. The latter affects modern light weighted structures which are more and more used for example in aircraft constructions. Especially for such safety-critical systems, online and in-situ fault diagnosis are desired. Structural health monitoring (SHM) concepts deal with different tools to realize safe systems, applying fault monitoring, and repair mechanism in combination with approaches for monitoring the hazard rate of complete complex systems. The contribution provides new results for the application of the proportional-integral-observer (PIO) for the fault localization in elastic mechanical systems. At this, the PIO works as a virtual sensor. Moreover, the PIO can be applied for fault detection and estimation. Therewith it can provide inputs for the SRCE concept. That one gives a framework and strategy to calculate the actual reliability of a system under operation what may be used for the purpose of predictive/condition-based maintenance in the context of SHM concepts. © 2009, IEEE. All rights reserved.

关键词： Condition monitoring (CM) fault diagnosis prognosis proportional-integral-observer (PIO) reliability safety structural-health-monitoring (SHM)

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Identification of human driver critical behaviors and related reliability evaluation in real time 32nd

Identification of human driver critical behaviors and relate...

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32nd European Safety and Reliability Conference, ESREL 2022

作者： He, Chao Soffker, Dirk Chair of Dynamics and Control University of Duisburg-Essen Germany

ISBN: (纸本)9789811851834

The role played by humans is becoming more and more important as the proportion of human-related accidents is increasing in industry and traffic. Human error taxonomies and their applications in driving context improve the understanding of human error mechanisms in situated driving context. In previous works, the authors provide a human performance reliability score (HPRS) which can be applied to driving data using the modified fuzzy-based CREAM (cognitive reliability and error analysis method) approach. The data clustering approach FN-DBSCAN (fuzzy neighborhood density-based spatial clustering of application with noise) with genetic algorithm is applied to automatically generate membership functions characterizing the driving behaviors individually. The driving behaviors and the mechanism of human error to the corresponding HPRS numbers are not analyzed in previous works. In this contribution, the classification of human driver error and its application in driving context is reviewed. The driving behaviors and the different human errors with continuously calculated values are analyzed to investigate what really happens. Human driver reliability is evaluated especially in situated context, this means dynamically changing situations (on a second-timescale). The newly developed approach provides a dynamic measure and therefore allows to dynamically identify critical situations during operation in real time. As example the supervision of an interacting human driver is shown. © 2022 ESREL2022 Organizers. Published by Research Publishing, Singapore.

关键词： Membership functions

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Situated and personalized monitoring of human operators during complex situations 32nd

Situated and personalized monitoring of human operators duri...

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32nd European Safety and Reliability Conference, ESREL 2022

作者： He, Chao Bejaoui, Abderahman Soffker, Dirk Chair of Dynamics and Control University of Duisburg-Essen Germany

ISBN: (纸本)9789811851834

Human behavior monitoring classically refers to the detection of human movements or a simple recognition of activities in limited known space. The monitoring of human activities in the context of concrete operating tasks often focuses on the detection of operating errors, unauthorized actions, or implicitly on the violation of protection goals. This contribution uses a qualitative description approach (situation-operator-modeling(SOM)) with which the logic of human interaction in given formalized context as action sequences as well as the situational, i.e. contextual, application of individual single actions can be realized. However, human performance reliability in action sequences is not clear and the optimal action sequence can not be defined. To solve this problem, the concept of human performance reliability score (HPRS) proposed in previous works is calculated with the modified fuzzy-based CREAM (cognitive reliability and error analysis method) approach. Therefore, situated and personalized HPRS values could be assigned to the action sequences in SOM action space. In this case, an event-discretized behavior model situated and personalized monitoring human performance with human reliability values could be generated. Using the example of human driving behavior for driving situations on highways, the application of the method is presented in detail. The monitoring of concrete example driver in real time will be demonstrated. The examples show that a direct warning or assistance will be helpful. © 2022 ESREL2022 Organizers. Published by Research Publishing, Singapore.

关键词： Behavioral research

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Adaptive situated and reliable prediction of object trajectories 32nd

Adaptive situated and reliable prediction of object trajecto...

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32nd European Safety and Reliability Conference, ESREL 2022

作者： Thind, Navreet S. Ameyaw, Daniel A. Söffker, Dirk Chair of Dynamics and Control University of Duisburg-Essen Germany

ISBN: (纸本)9789811851834

Autonomous vehicles like inland vessels require reliable information from on-board systems and surrounding objects like encountering vessels in the environment. Besides the detection of objects, the prediction of encountering object’s trajectory is one of the most crucial tasks to realize safe operation of autonomous systems. In this contribution, a situated model approach for trajectory prediction as well as an evaluation approach of this model using the Probability of Detection (POD) approach are developed. The reliability of this newly developed prediction model relative to the prediction time is evaluated using the POD approach. The goal is to define the time interval beyond which the reliability is less than the 90/95 (90% detection probability at 95% confidence interval) criterion. The decision threshold is defined by the distance needed to avoid collision for the safe sailing of the vessel. The used POD approach provides a new certification standard for prediction approaches and is therefore useful in safetycritical systems. The situated prediction algorithm allows predicting the trajectory of waterway objects for a safetyrelevant period of time (minutes) using a simple parameter-based approach where some parameters are globally trained and a local parameter is adapted based on past data using a sliding window approach. The past data consider all local environmental and hydrodynamical effects affecting object’s motion in the next minutes. The predictions are assumed as dependent on the different geometry trajectories like straight, curved, and sharp curved paths. The approach uses the position data of vessels (known from AIS or radar data). Experimental data from a German research inland vessel are used to validate the approach. Using the POD-based approach, it can be shown that the local model predictions are reliable in defined time intervals and the reliability of the prediction horizon relative to the locations of the waterways can be defined. © 2022 ESRE

关键词： Prediction models

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Periodic propagation of singularities for heat equations with time delay

arXiv

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arXiv 2025年

作者： Wang, Gengsheng Yu, Huaiqiang Zhang, Yubiao Center for Applied Mathematics KL-AAGDM Tianjin University Tianjin300072 China School of Mathematics KL-AAGDM Tianjin University Tianjin300350 China Radon Institute for Computational and Applied Mathematics Austrian Academy of Sciences Altenbergerstraße 69 Upper Austria Linz4040 Austria Chair for Dynamics Control Machine Learning and Numerics Department of Mathematics Friedrich-Alexander-Universität Erlangen-Nürnberg Erlangen91058 Germany

This paper presents two remarkable phenomena associated with the heat equation with a time delay: namely, the propagation of singularities and periodicity. These are manifested through a distinctive mode of propagation of singularities in the solutions. Precisely, the singularities of the solutions propagate periodically in a bidirectional fashion along the time axis. Furthermore, this propagation occurs in a stepwise manner. More specifically, when propagating in the positive time direction, the order of the joint derivatives of the solution increases by 2 for each period;conversely, when propagating in the reverse time direction, the order of the joint derivatives decreases by 2 per period. Additionally, we elucidate the way in which the initial data and historical values impact such a propagation of singularities. The phenomena we have discerned not only corroborate the pronounced differences between heat equations with and without time delay but also vividly illustrate the substantial divergence between the heat equation with a time delay and the wave equation, especially when viewed from the point of view of singularity *** Codes 35K05 45K05 58J47 © 2025, CC BY.

关键词： Wave equations

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Comparison of CWRU Dataset-Based Diagnosis Approaches: Review of Best Approaches and Results

Comparison of CWRU Dataset-Based Diagnosis Approaches: Revie...

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European Workshop on Structural Health Monitoring, EWSHM 2020

作者： Wei, Xiao Söffker, Dirk Chair of Dynamics and Control University of Duisburg Essen Duisburg Germany

ISBN: (纸本)9783030645939

Bearings are the most common mechanical components in machines. Once a bearing fails (or components in it), other adjacent components or the machine itself are effected up to failure. Therefore, bearing health condition is of great interest in practice. Several benchmark datasets are developed to evaluate development in bearings health state (diagnosis) and remaining useful lifetime (prognosis). Among these datasets, Case Western Reserve University (CWRU) dataset is one of the most cited ones used to validate the performance of different diagnostic approaches. Over recent years, a significant amount of research approaches are developed using CWRU data. Most approaches are focused on specific performance parameters like detection rate or accuracy etc. The main problems in connection with CWRU dataset use are: no overview about latest results is available. Furthermore several results published are not complete, for example published accuracies rate without false alarm rates. In this contribution an overview about the development change over the last years, the approaches applied, and specifically the results obtained will be given. Additionally, the new approaches emerging in recent years like deep learning (DL) also in combination with fusion methods and related performance will be given in comparison with conventional machine learning (ML) methods. Special care will be given to the completeness of published results also in combination with shown robustness. As outcome of this contribution the newest and best results are noted, furthermore a recommendation how to complete research work using benchmark dataset will be given. Although most approaches using CWRU dataset as benchmark get high accuracy, for further bearing fault diagnosis research, more and more suitable measures as well as other datasets are needed for increased performance evaluation. © 2021, Springer Nature Switzerland AG.

关键词： Benchmarking

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False Alarm-Improved Detection Capabilities of Multi-sensor-Based Monitoring of Vibrating Systems

False Alarm-Improved Detection Capabilities of Multi-sensor-...

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European Workshop on Structural Health Monitoring, EWSHM 2020

作者： Ameyaw, Daniel Adofo Söffker, Dirk Chair of Dynamics and Control University of Duisburg-Essen Duisburg Germany

ISBN: (纸本)9783030645939

Monitoring the State-of-Health of vibrating mechanical systems is useful but complex. Besides challenges associated with dynamical behaviors of the systems monitored, supervision tasks are complex with respect data acquisition, feature extraction, and/or statistical modeling for feature classification. Data acquisition strategy addresses sensor types, quantities, and locations. Feature extraction task details the selection and processing of features sensitive to a change/fault present and if required the development of statistical models for change/fault classification. In this contribution, the above-mentioned challenges associated with supervision are explained and detailed using an elastic mechanical structure applying the Probability of Detection method. Previously solved problems relating to simultaneously accessing all mentioned challenges are briefly repeated for understanding. This serves as a prelude to the newly developed data driven noise analysis and improved detection procedure. An experimental example using different real sensor types in combination with mechanical modifications of an elastic beam is presented. The adapted Probability of Detection method helps to determine a suitable feature, sensor type, and position for least change/fault detection. In this article a new data driven noise analysis approach is introduced to ensure optimal sensor-specific flaw size detection. Optimality in this context is related to the selection of the appropriate feature and threshold values for desired false alarms. The noise analysis permits the selection of a decision threshold (threshold beyond which change/fault is considered present in a signal) with the corresponding detectable flaw size and related false alarm rate. Selecting different sensors implies changing the signal distribution character and the decision threshold. This change results in different values and hence can be exploited to decide the optimal sensor. The implemented noise analysis allows a tra

关键词： Feature extraction

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