The Experts below are selected from a list of 3393 Experts worldwide ranked by ideXlab platform
Danijela Ristic - One of the best experts on this subject based on the ideXlab platform.
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feedback structures as a key requirement for robustness case studies in image processing
ris, 2008Co-Authors: Axel Graser, Danijela RisticAbstract:Natural as well as technical systems owe their robustness to a large extent to feedback structures. To use feedback, it is necessary to define a measurement, an Actuator in the system, and a setpoint or reference—the measurement is compared with the reference and an Actuator Action is derived from the difference between them. This simple but powerful structure is responsible for providing the system with robustness against external influences. For a detailed discussion, the image processing system is chosen. The robustness of an image processing system is considered here to be the ability of an algorithm to achieve the desired output independently of numerous external influences such as illumination conditions, the imaging system, and imaged objects characteristics. Because of a number of problems, such as the absence of feedback from the higher to the lower processing levels, a traditional image processing system is of low robustness. This chapter presents the novel idea of the inclusion of feedback control at different processing levels to overcome the above problems of traditional image processing. The main idea behind this is to change the processing parameters in a closed-loop manner so that the current processing result at a particular processing level is driven to a reference result, providing the subsequent higher processing level with reliable input data. Presenting image processing as a new control application field, the chapter focuses on the specific features of image processing that make closed-loop control in this area different from conventional industrial control. The advantage of feedback for this advanced, prominent, and important application area is demonstrated through two examples.
Mi Dong - One of the best experts on this subject based on the ideXlab platform.
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model predictive control with finite control set for variable speed wind turbines
Energy, 2017Co-Authors: Dongran Song, Jian Yang, Mi DongAbstract:Abstract The existing model predictive control (MPC) algorithm for variable-speed wind turbines (WTs) is using continuous control set and solved by a quadratic programming method. Its main drawbacks are the heavily computational burden and the difficulty to implement. This paper introduces an alternative MPC method by using finite control set, which is used in controlling WTs at the first attempt. To do this, first of all, the WT's nonlinear model is linearized with information provided by a non-standard extended Kalman filter. Secondly, a discrete-time linear model of the system is used to predict the future value of the interested state variable for possible control sets. In view of the fact that control objectives are different within two operation zones partitioned by wind speed, two quality functions are predefined. One quality function evaluates the optimal generator speed tracking error together with the penalty of torque Actuator Action at below rated wind speed, while the other evaluates the rated generator speed tracking error and the penalty of pitch Actuator Action at above rated wind speed. Then, the corresponding control set which minimizes the quality function is selected. Finally, some simulation results are demonstrated to visualize the effectiveness and feasibility of the proposed method.
Philippe Joly - One of the best experts on this subject based on the ideXlab platform.
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automatic textual description of interActions between two objects in surveillance videos
SN Applied Sciences, 2021Co-Authors: Wael F Youssef, Siba Haidar, Philippe JolyAbstract:The purpose of our work is to automatically generate textual video description schemas from surveillance video scenes compatible with police incidents reports. Our proposed approach is based on a generic and flexible context-free ontology. The general schema is of the form [Actuator] [Action] [over/with] [actuated object] [+ descriptors: distance, speed, etc.]. We focus on scenes containing exactly two objects. Through elaborated steps, we generate a formatted textual description. We try to identify the existence of an interAction between the two objects, including remote interAction which does not involve physical contact and we point out when aggressivity took place in these cases. We use supervised deep learning to classify scenes into interAction or no-interAction classes and then into subclasses. The chosen descriptors used to represent subclasses are keys in surveillance systems that help generate live alerts and facilitate offline investigation.
Axel Graser - One of the best experts on this subject based on the ideXlab platform.
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feedback structures as a key requirement for robustness case studies in image processing
ris, 2008Co-Authors: Axel Graser, Danijela RisticAbstract:Natural as well as technical systems owe their robustness to a large extent to feedback structures. To use feedback, it is necessary to define a measurement, an Actuator in the system, and a setpoint or reference—the measurement is compared with the reference and an Actuator Action is derived from the difference between them. This simple but powerful structure is responsible for providing the system with robustness against external influences. For a detailed discussion, the image processing system is chosen. The robustness of an image processing system is considered here to be the ability of an algorithm to achieve the desired output independently of numerous external influences such as illumination conditions, the imaging system, and imaged objects characteristics. Because of a number of problems, such as the absence of feedback from the higher to the lower processing levels, a traditional image processing system is of low robustness. This chapter presents the novel idea of the inclusion of feedback control at different processing levels to overcome the above problems of traditional image processing. The main idea behind this is to change the processing parameters in a closed-loop manner so that the current processing result at a particular processing level is driven to a reference result, providing the subsequent higher processing level with reliable input data. Presenting image processing as a new control application field, the chapter focuses on the specific features of image processing that make closed-loop control in this area different from conventional industrial control. The advantage of feedback for this advanced, prominent, and important application area is demonstrated through two examples.
Dongran Song - One of the best experts on this subject based on the ideXlab platform.
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model predictive control with finite control set for variable speed wind turbines
Energy, 2017Co-Authors: Dongran Song, Jian Yang, Mi DongAbstract:Abstract The existing model predictive control (MPC) algorithm for variable-speed wind turbines (WTs) is using continuous control set and solved by a quadratic programming method. Its main drawbacks are the heavily computational burden and the difficulty to implement. This paper introduces an alternative MPC method by using finite control set, which is used in controlling WTs at the first attempt. To do this, first of all, the WT's nonlinear model is linearized with information provided by a non-standard extended Kalman filter. Secondly, a discrete-time linear model of the system is used to predict the future value of the interested state variable for possible control sets. In view of the fact that control objectives are different within two operation zones partitioned by wind speed, two quality functions are predefined. One quality function evaluates the optimal generator speed tracking error together with the penalty of torque Actuator Action at below rated wind speed, while the other evaluates the rated generator speed tracking error and the penalty of pitch Actuator Action at above rated wind speed. Then, the corresponding control set which minimizes the quality function is selected. Finally, some simulation results are demonstrated to visualize the effectiveness and feasibility of the proposed method.
