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An active material system may be generalized as an electro-mechanical network because of the incorporation of the actuators (electrically driven) and sensors (that convert mechanical energy into electrical energy). This paper summ...
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An active material system may be generalized as an electro-mechanical network because of the incorporation of the actuators (electrically driven) and sensors (that convert mechanical energy into electrical energy). This paper summarizes most of our research in the area of the electro- mechanical impedance (EMI) modeling of active material systems. In this paper, a generic electro-mechanical impedance model to describe the electro-mechanical network behavior (time domain and frequency domain) of active material systems is discussed. The focus of the discussion is on the methodology and basic components of the EMI modeling technique and its application to assist in the design of efficient active control structures. This paper first introduces the basic concept of the electro-mechanical impedance modeling and its general utilities in the area of active material systems. The methodology of the EMI modeling technique is illustrated using an example of PZT actuator-driven mechanical systems. The basic components in the EMI modeling are discussed. Finally, some applications of the EMI modeling approach are presented.
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This paper presents a novel approach for multi-objective optimization under both aleatory and epistemic sources of uncertainty. Given samples of the inputs and outputs from a model, a Bayesian network (BN) is built to incorporate ...
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This paper presents a novel approach for multi-objective optimization under both aleatory and epistemic sources of uncertainty. Given samples of the inputs and outputs from a model, a Bayesian network (BN) is built to incorporate all the available information. Gaussian copula assumption is adopted for efficient conditional sampling of BN. The proposed approach is applied formulated in the context of reliability-based design optimization (RBDO). The joint distribution of multiple outputs is adopted as the constraint. Estimation of the joint probability is efficient since the Gaussian copula is able to model the conditional distribution analytically. A vehicle side impact problem is employed to demonstrate the proposed methodology.
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摘要 :
This paper presents a novel approach for multi-objective optimization under both aleatory and epistemic sources of uncertainty. Given samples of the inputs and outputs from a model, a Bayesian network (BN) is built to incorporate ...
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This paper presents a novel approach for multi-objective optimization under both aleatory and epistemic sources of uncertainty. Given samples of the inputs and outputs from a model, a Bayesian network (BN) is built to incorporate all the available information. Gaussian copula assumption is adopted for efficient conditional sampling of BN. The proposed approach is applied formulated in the context of reliability-based design optimization (RBDO). The joint distribution of multiple outputs is adopted as the constraint. Estimation of the joint probability is efficient since the Gaussian copula is able to model the conditional distribution analytically. A vehicle side impact problem is employed to demonstrate the proposed methodology.
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A GIS-based gradient analysis is a useful tool for exploring spatiotemporal dynamics of urban land-use. Although some case studies have been conducted confirming the efficacy of this approach, the gradient analysis of large-scale ...
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A GIS-based gradient analysis is a useful tool for exploring spatiotemporal dynamics of urban land-use. Although some case studies have been conducted confirming the efficacy of this approach, the gradient analysis of large-scale regional urbanization has still been seldom documented, and the urbanization of satellite cities and their interactions with a central city in regional urbanization have also been poorly explored. In this study, a combination of remotely sensed data, urbanization metrics and GIS-based buffer gradient analysis is employed to analyze the overall spatiotemporal characteristics of urban expansion in the Shanghai region, China, and to explore the urbanization of its major satellite cities and their interactions. The results show the overall spatiotemporal changes in the urbanization gradient are largely influenced by the distance from the urban center, yet there are distinct spatial variations mainly resulting from the interactions of the urbanization of the central city with that of satellite cities. The urbanization within the urban-suburb transitional zones generally had a specific rhythm of intensity and weakness, which can function as the spatial signatures to analyze and demonstrate similar or other types of urbanization processes. The major satellite cities of the Shanghai region showed their distinct temporal-spatial characteristics in their urban expansion behaviors, and thus can be categorized as autonomous, passive, steady and irregular modes of urbanization.
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摘要 :
A GIS-based gradient analysis is a useful tool for exploring spatiotemporal dynamics of urban land-use. Although some case studies have been conducted confirming the efficacy of this approach, the gradient analysis of large-scale ...
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A GIS-based gradient analysis is a useful tool for exploring spatiotemporal dynamics of urban land-use. Although some case studies have been conducted confirming the efficacy of this approach, the gradient analysis of large-scale regional urbanization has still been seldom documented, and the urbanization of satellite cities and their interactions with a central city in regional urbanization have also been poorly explored. In this study, a combination of remotely sensed data, urbanization metrics and GISbased buffer gradient analysis is employed to analyze the overall spatiotemporal characteristics of urban expansion in the Shanghai region, China, and to explore the urbanization of its major satellite cities and their interactions. The results show the overall spatiotemporal changes in the urbanization gradient are largely influenced by the distance from the urban center, yet there are distinct spatial variations mainly resulting from the interactions of the urbanization of the central city with that of satellite cities. The urbanization within the urban-suburb transitional zones generally had a specific rhythm of intensity and weakness, which can function as the spatial signatures to analyze and demonstrate similar or other types of urbanization processes. The major satellite cities of the Shanghai region showed their distinct temporal-spatial characteristics in their urban expansion behaviors, and thus can be categorized as autonomous, passive, steady and irregular modes of urbanization. Key words: Urban expansion;; Spatiotemporal;; Buffer analysis;; Satellite city;; Shanghai;; China
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Self-training achieves enormous success in various semi-supervised and weakly-supervised learning tasks. The method can be interpreted as a teacher-student framework, where the teacher generates pseudo-labels, and the student make...
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Self-training achieves enormous success in various semi-supervised and weakly-supervised learning tasks. The method can be interpreted as a teacher-student framework, where the teacher generates pseudo-labels, and the student makes predictions. The two models are updated alternatingly. However, such a straightforward alternating update rule leads to training instability. This is because a small change in the teacher may result in a significant change in the student. To address this issue, we propose DRIFT, short for differentiable self-training, that treats teacher-student as a Stackelberg game. In this game, a leader is always in a more advantageous position than a follower. In self-training, the student contributes to the prediction performance, and the teacher controls the training process by generating pseudo-labels. Therefore, we treat the student as the leader and the teacher as the follower. The leader procures its advantage by acknowledging the follower's strategy, which involves differentiable pseudo-labels and differentiable sample weights. Consequently, the leader-follower interaction can be effectively captured via Stackelberg gradient, obtained by differentiating the follower's strategy. Experimental results on semi-and weakly-supervised classification and named entity recognition tasks show that our model outperforms existing approaches by large margins.
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Most of the existing GPS spoofing detection schemes are vulnerable to the complex generative GPS spoofing attack, and require additional auxiliary equipments and extensive signal processing capabilities, leading to defects such as...
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Most of the existing GPS spoofing detection schemes are vulnerable to the complex generative GPS spoofing attack, and require additional auxiliary equipments and extensive signal processing capabilities, leading to defects such as low real-time performance and large communication overhead which may not be available for the unmanned aerial vehicle (UAV, also known as drone) system. Motivated by the limitations of prior work, we propose a GPS spoofing detection scheme that requires minimal prior configuration and employs information fusion based on the GPS receiver and inertial measurement unit (IMU). We use a realtime model of tracking and calculating to derive the current location of the drones which are then contrasted with the location information received by the GPS receiver to judge whether the UAV system is under spoofing attack. Experiments show that, while the accuracy meets the requirements of detection, the proposed method can accurately determine whether the system is attacked within 8 s, with a detection rate of 98.6%. Compared with the existing schemes, the performance of realtime detecting is improved in our method while the detection rate is ensured. Even in our worst-case, we detect GPS spoofing attack within 28 s after the UAV system starts its mission.
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摘要 :
Most of the existing GPS spoofing detection schemes are vulnerable to the complex generative GPS spoofing attack, and require additional auxiliary equipments and extensive signal processing capabilities, leading to defects such as...
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Most of the existing GPS spoofing detection schemes are vulnerable to the complex generative GPS spoofing attack, and require additional auxiliary equipments and extensive signal processing capabilities, leading to defects such as low real-time performance and large communication overhead which may not be available for the unmanned aerial vehicle (UAV, also known as drone) system. Motivated by the limitations of prior work, we propose a GPS spoofing detection scheme that requires minimal prior configuration and employs information fusion based on the GPS receiver and inertial measurement unit (IMU). We use a realtime model of tracking and calculating to derive the current location of the drones which are then contrasted with the location information received by the GPS receiver to judge whether the UAV system is under spoofing attack. Experiments show that, while the accuracy meets the requirements of detection, the proposed method can accurately determine whether the system is attacked within 8 s, with a detection rate of 98.6%. Compared with the existing schemes, the performance of realtime detecting is improved in our method while the detection rate is ensured. Even in our worst-case, we detect GPS spoofing attack within 28 s after the UAV system starts its mission.
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This paper introduces the system structure of the kilometer-level superconducting cable demonstration project of Shanghai and presents an overall scheme of relay protection configuration for superconducting lines. The scheme takes...
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This paper introduces the system structure of the kilometer-level superconducting cable demonstration project of Shanghai and presents an overall scheme of relay protection configuration for superconducting lines. The scheme takes differential protection and quench protection as the primary protection for quick isolation of the internal faults, and takes over-current protection as the back-up protection for timely removal of superconducting cables when there are line faults or external faults after the differential protection is out of service, ensuring the safety of the superconducting cable equipment. Also, the feasibility of application of reclosure and inverse time over-current is discussed. Aiming at the wiring method of the kilometer-level superconducting cable demonstration project of Shanghai, this paper introduces the tripping and closing logic and matching mode of breakers on both sides of the superconducting line, so as to realize a consistent supply of electricity when the superconducting cable is in fault. Non-electric quantity information such as temperature, pressure, flow rate, etc. is an important monitoring indicator for the state of the superconducting cable. The application of non-electric quantity status information on both ends of the kilometer-level superconducting cable line in relay protection device is introduced.
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This paper introduces the system structure of the kilometer-level superconducting cable demonstration project of Shanghai and presents an overall scheme of relay protection configuration for superconducting lines. The scheme takes...
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This paper introduces the system structure of the kilometer-level superconducting cable demonstration project of Shanghai and presents an overall scheme of relay protection configuration for superconducting lines. The scheme takes differential protection and quench protection as the primary protection for quick isolation of the internal faults, and takes over-current protection as the back-up protection for timely removal of superconducting cables when there are line faults or external faults after the differential protection is out of service, ensuring the safety of the superconducting cable equipment. Also, the feasibility of application of reclosure and inverse time over-current is discussed. Aiming at the wiring method of the kilometer-level superconducting cable demonstration project of Shanghai, this paper introduces the tripping and closing logic and matching mode of breakers on both sides of the superconducting line, so as to realize a consistent supply of electricity when the superconducting cable is in fault. Non-electric quantity information such as temperature, pressure, flow rate, etc. is an important monitoring indicator for the state of the superconducting cable. The application of non-electric quantity status information on both ends of the kilometer-level superconducting cable line in relay protection device is introduced.
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