Automatic towing operations for non-powered ships at sea constitute a fundamental step toward automating the towing mission at harbor. This paper is devoted to solve one of the sea maneuvering problems that uses an au...
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ISBN:
(数字)9798331542726
ISBN:
(纸本)9798331542733
Automatic towing operations for non-powered ships at sea constitute a fundamental step toward automating the towing mission at harbor. This paper is devoted to solve one of the sea maneuvering problems that uses an automatic leader tug. The proposed maneuver involves implementing of robust escorting system (also called towing system) of partially non-powered towed cargo ship for an automatic berthing. To enhance the maneuverability of the towed ship, its rudder system is made active throughout the mission. To address the problem of rejecting the time-varying disturbances induced by wind, current and system parametric uncertainties, an adaptive finite-time sliding mode disturbance observer is first proposed. Then, a composite controller with flexible prescribed performance is developed based on a novel unified towing tracking error, which can ensure the geometric state variables and its corresponding velocity meet the prescribed performance constraints at the same time. Stability analysis is conducted to prove finite-time convergence of the towing tracking errors. Finally, numerical simulations validate the proposed approach.
The dehydration occurs when the body loses more water than it takes in. The mild dehydration can lead to fatigue, cognitive impairments, and physical complications, while severe dehydration can cause life-threatening ...
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This work proposes a fully circuit-based method for modelling electrical transformers. This method not only offers the advantages of circuit-based methods and can be implemented in electromagnetic transient (EMT) type...
This work proposes a fully circuit-based method for modelling electrical transformers. This method not only offers the advantages of circuit-based methods and can be implemented in electromagnetic transient (EMT) type software, but it can also provide a detailed representation of transformers, comparable to the finite element method (FEM). The proposed method enables a detailed geometrical modelling, as well as representation of magnetic flux paths and consideration of iron core saturation. It can be implemented in EMT-type software to see the effect of power networks on transformers. In addition, the proposed method can represent internal faults in transformers. The problem is constrained to a 2-D domain, which is often used in FEMs to represent the magnetic behavior of power equipment. Finite element analysis based on ANSYS Maxwell is used to verify the proposed method.
This paper investigates a deep reinforcement learning (DRL)-based approach for managing channel access in wireless networks. Specifically, we consider a scenario in which an intelligent user device (iUD) shares a time...
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ISBN:
(数字)9798350303582
ISBN:
(纸本)9798350303599
This paper investigates a deep reinforcement learning (DRL)-based approach for managing channel access in wireless networks. Specifically, we consider a scenario in which an intelligent user device (iUD) shares a time-varying uplink wireless channel with several fixed transmission schedule user devices (fUDs) and an unknown-schedule malicious jammer. The iUD aims to harmoniously coexist with the fUDs, avoid the jammer, and adaptively learn an optimal channel access strategy in the face of dynamic channel conditions, to maximize the network's sum cross-layer achievable rate (SCLAR). Through extensive simulations, we demonstrate that when we appropriately define the state space, action space, and rewards within the DRL frame-work, the iUD can effectively coexist with other UDs and optimize the network's SCLAR. We show that the proposed algorithm outperforms the tabular Q-learning and a fully connected deep neural network approach.
In most scenarios, distributed denial of service (DDoS) attacks can be categorized into three distinct groups: (1) attacks targeting and consuming bandwidth, (2) attacks targeting selected applications and (3) attacks...
In most scenarios, distributed denial of service (DDoS) attacks can be categorized into three distinct groups: (1) attacks targeting and consuming bandwidth, (2) attacks targeting selected applications and (3) attacks targeting connection-layer exhaustion. This study discusses in depth our proposal of a unique, inclusive model that has the ability to precisely detect and categorize DDoS attacks with the help of comparing normal traffic and resource usage against the traffic and resource utilization reported during potential attack situations. Since the features from all three attack categories are dependent upon each other, we based the metrics of our detection model on data collected from all three types during each attack. Additionally, we utilized the cumulative sum algorithm for the sake of change detection in traffic and resource usage patterns.
This paper addresses the problem of estimating time-varying directions of arrival. It demonstrates how the concept of instantaneous frequency can be employed for this purpose. The proposed approach can localize more s...
This paper addresses the problem of estimating time-varying directions of arrival. It demonstrates how the concept of instantaneous frequency can be employed for this purpose. The proposed approach can localize more sources than the number of available sensors. It also theoretically allows the estimation of any angular time variation. Herein, we consider linear and hyperbolic time variations, which, in practice, take into account velocity and acceleration, respectively. Numerical experiments are conducted to validate the effectiveness of the proposed method.
The Graph Laplacian Mixture Model (GLMM) allows to infer multiple underlying graph structures from multivariate time series data. Given its effectiveness in identifying brain states from brain activity measured by fun...
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ISBN:
(数字)9798331520526
ISBN:
(纸本)9798331520533
The Graph Laplacian Mixture Model (GLMM) allows to infer multiple underlying graph structures from multivariate time series data. Given its effectiveness in identifying brain states from brain activity measured by functional magnetic resonance imaging (fMRI), we adapt GLMM for block-structured datasets, where data is organized into communities with strong intra-community interactions and relatively weak inter-community connections. This modification of the GLMM enables to capture the intricate structure inherent to block-structured datasets, such as fMRI data that simultaneously covers brain and cervical spinal cord, which both come with different properties. By integrating the prior knowledge on community structure into the GLMM framework, we proposed an approach that more accurately reflects the hierarchical organization and interaction patterns present in these complex networks. This enhancement offers a powerful tool for studying networked systems with distinct community structures, improving our ability to interpret patterns and dynamics in neural data with natural sub-structural organization.
As platforms increasingly rely on learning algorithms, collectives may form and seek ways to influence these platforms to align with their own interests. This can be achieved by coordinated submission of altered data....
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We analyze bounds to the electromagnetic local density of states achievable via material structuring, deriving novel results including finite bound saturation in the infinite susceptibility limit and sub-linear bandwi...
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ISBN:
(纸本)9781957171258
We analyze bounds to the electromagnetic local density of states achievable via material structuring, deriving novel results including finite bound saturation in the infinite susceptibility limit and sub-linear bandwidth scaling for lossy materials.
Understanding the variation of the optimal value with respect to change in the data is an old problem of mathematical optimisation. This paper focuses on the linear problem f(λ) = min ctx such that (A+λD′)x ≤ b, w...
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