In this paper, a finite-time fault-tolerant control method is developed for attitude tracking of a nano-satellite with three magnetorquers and one reaction wheel in the presence of actuator faults, inertia uncertainti...
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In this paper, a finite-time fault-tolerant control method is developed for attitude tracking of a nano-satellite with three magnetorquers and one reaction wheel in the presence of actuator faults, inertia uncertainties, external distribution, and actuator constraints. For this purpose, the modified non-singular fast terminal sliding mode control is used due to the ability of robustness against uncertainties and finite-time convergence. In this approach, the modified sliding surface variable is constructed based on angular velocity and attitude error to converge the attitude error to zero in a finite time. In addition, three adaptive parameters are employed to reduce the adverse effect of uncertain expressions and to track the attitude commands with high control accuracy. The adaptive parameters and sliding surface variable are used in the reaching phase of the controller to decrease the chattering phenomenon. The dynamics of adaptive parameters, with regard to the angular velocities of the nano-satellite and reaction wheel and the sliding surface variable, are obtained during the stability proof of the closed-loop system. Also, the finite-time convergence of sliding surface and attitude variables are proved by the extended Lyapunov condition, and the convergence regions of attitude tracking errors are obtained. The simulations are accomplished and compared with an existing adaptive sliding mode control approach to evaluate the performance of the proposed controller. The results verify that the proposed controller performs better than the mentioned controller in terms of finite-time convergence, the accuracy of attitude tracking, and the reduction of the chattering phenomenon.(c) 2023 Elsevier Masson SAS. All rights reserved.
The traditional solid-state drive buffer management algorithm generally adopts fixed structures and parameters, leading to their poor adaptability. For example, after the underlying flash translation layer (FTL) or th...
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The traditional solid-state drive buffer management algorithm generally adopts fixed structures and parameters, leading to their poor adaptability. For example, after the underlying flash translation layer (FTL) or the upper workload is changed, the traditional algorithm's performance fluctuates significantly. Focusing on this problem, based on the cross-layer aware method, we propose an Advanced adaptive Least Recently Used buffer management algorithm (AALRU). The core idea of the AALRU is that by sensing the characteristics of the upper workload and the status of the underlying FTL, the AALRU adaptively adjusts its structure, parameters, and write-back strategy to optimize the buffer's performance. First, the AALRU divides the buffer into two parts: read buffer and write buffer, and their proportion is adjusted by sensing the read-write characteristics of the workload and the underlying read-write latency. Second, the AALRU employs different granularities to manage the buffer. On one hand, for data loading and migrating, the AALRU adopts page-level granularity, which can avoid the problem of hot and cold data page entanglement in block management, and thus improve the buffer hit ratio. On the other hand, for data writing back to the FTL, the AALRU adopts block-level granularity, which can enhance the continuity of write requests and thus reduce the underlying FTL's garbage collection overhead. Finally, when the clustered data are written back, by sensing the underlying FTL's garbage collection status, the AALRU adaptively adjusts the page-padding trigger threshold to reconstruct the continuity of the write-back data, which can mitigate the underlying FTL's garbage collection overhead. The experimental results show that the AALRU has the best adaptability to different FTLs and test workloads, and it can achieve optimal or near-optimal results.
In this paper,we consider a modified nonlinear dynamic diffusion(DD)method for convection-diffusion-reaction *** method is free of stabilization parameters and capable of precluding spurious *** develop a reliable and...
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In this paper,we consider a modified nonlinear dynamic diffusion(DD)method for convection-diffusion-reaction *** method is free of stabilization parameters and capable of precluding spurious *** develop a reliable and efficient residual-type a posteriori error estimator,which is robust with respect to the diffusivity ***,we propose a linearized adaptive DD algorithm based on the a posteriori ***,we perform numerical experiments to verify the theoretical analysis and the performance of the adaptive algorithm.
This paper addresses the problem of speech enhancement and acoustic noise reduction by partial and set-membership adaptive algorithms combined with the symmetric decorrelating adaptive (SAD) algorithm structure. In th...
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This paper addresses the problem of speech enhancement and acoustic noise reduction by partial and set-membership adaptive algorithms combined with the symmetric decorrelating adaptive (SAD) algorithm structure. In this paper, we propose two new adaptive algorithms based on set-membership principle that improve the original set-membership algorithm behavior in speech enhancement applications. The first proposed algorithm (called Proposed 1), is based on the combination of the SAD algorithm structure with a smart control that uses decorrelating properties between the output and the mixing signal to control and update the SAD adaptive filters. The second proposed algorithm (called Proposed 2) is a modification of Proposed 1 and based on a new regularization relations of the SAD adaptive filters that use a combination between the variance of the mixing and the output signals of the SAD structures. These two proposed algorithms (Proposed 1 and Proposed 2) aim to improve the convergence speed performance and the output signal-to-noise-ratio of the original SAD algorithm when no smart control of the adaptive filters is used. The proposed algorithms have very interesting properties with non-stationary signal like speech when the SAD algorithm is, used alone, fails. The simulation results that are obtained by the comparison between the proposed algorithms (Proposed 1 and Proposed 2) and the original two-channel set-membership NLMS algorithm have shown the best performances of Proposed 1 and Proposed 2 in terms of the following criteria: systems mismatch, segmental SNR and segmental men square error.
We propose a new method for multi-objective optimization, called Fuzzy adaptive Multi-objective Evolutionary algorithm (FAME). It makes use of a smart operator controller that dynamically chooses the most promising va...
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We propose a new method for multi-objective optimization, called Fuzzy adaptive Multi-objective Evolutionary algorithm (FAME). It makes use of a smart operator controller that dynamically chooses the most promising variation operator to apply in the different stages of the search. This choice is guided by a fuzzy logic engine, according to the contributions of the different operators in the past. FAME also includes a novel effective density estimator with polynomial complexity, called Spatial Spread Deviation (SSD). Our proposal follows a steady-state selection scheme and includes an external archive implementing SSD to identify the candidate solutions to be removed when it becomes full. To assess the performance of our proposal, we compare FAME with a number of state of the art algorithms (MOEA/D-DE, SMEA, SMPSOhv, SMS-EMOA, and BORG) on a set of difficult problems. The results show that FAME achieves the best overall performance. (C) 2018 Elsevier Inc. All rights reserved.
This paper proposes an SFNN-ADHDP algorithm to approximate the solution of the highly coupled HJB equation for the optimal consensus control problem of first-order nonlinear multi-agent systems. Optimal consensus cont...
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ISBN:
(数字)9789887581581
ISBN:
(纸本)9798350366907
This paper proposes an SFNN-ADHDP algorithm to approximate the solution of the highly coupled HJB equation for the optimal consensus control problem of first-order nonlinear multi-agent systems. Optimal consensus control of multi-agent systems is achieved by innovatively combining stochastic fuzzy neural networks with adaptive dynamic programming. The proposed SFNN-ADHDP algorithm only requires the topology information of multi-agent systems for optimal consensus *** theory related knowledge and consensus problem modeling for the optimal consensus control problem of multi-agent systems are firstly presented in this paper. Secondly, the specific algorithm structure and implementation details of the SFNN-ADHDP are proposed. Finally, a set of simulation experiments are conducted to demonstrate the excellent anti-interference ability and superiority of the proposed algorithm, comparing the SFNN network with the ANFIS network by attempting to incorporate Gaussian white noise and other methods into the network.
In warehousing logistics, most regions still use manual sorting with low efficiency and high cost. Especially in some special work areas, such as high temperatures, severe electronic radiation, urgent need for small r...
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In warehousing logistics, most regions still use manual sorting with low efficiency and high cost. Especially in some special work areas, such as high temperatures, severe electronic radiation, urgent need for small robots to replace manual labor. This design uses PID control algorithm to independently determine the weight of the goods, wait for receiving goods at a designated location, move forward at a constant speed, and transport its weight to the designated position and unload it. Constant speed can make the trolley travel more smoothly and load and unload goods more smoothly.
This article uses mathematical modeling methods to predict the trajectory of a free kick in football. The article calculates the parameters of the ball's trajectory and quantifies the power of direct free kick sho...
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This article uses mathematical modeling methods to predict the trajectory of a free kick in football. The article calculates the parameters of the ball's trajectory and quantifies the power of direct free kick shots. The article combines Kalman filter prediction and linear interpolation to supplement the position of the missed ball in the video. The experimental results show that the estimated result of this method is highly similar to the actual flight trajectory of football. This algorithm can be applied in practice.
Multi-exposure image fusion as a technical means to bridge the dynamic range gap between real scenes and image acquisition devices, which makes the fused images better quality and more realistic and vivid simulation o...
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Multi-exposure image fusion as a technical means to bridge the dynamic range gap between real scenes and image acquisition devices, which makes the fused images better quality and more realistic and vivid simulation of real scenes, has been widely concerned by scholars from various countries. In order to improve the adaptive fusion effect of multi-exposure images, this paper proposes a fusion algorithm based on multilayer perceptron (MLP) based on the perceptron model and verifies the feasibility of the algorithm by the peak signal-to-noise ratio (PSNR), correlation coefficient (PCC), structural similarity (SSMI) and HDR-VDR-2, an evaluation index of HDR image quality. Comparison with other algorithms revealed that the average PSNR of the MLP algorithm improved by 4.43% over the Ma algorithm, 7.88% over the Vanmail algorithm, 10.30% over the FMMR algorithm, 11.19% over the PMF algorithm, and 11.19% over the PMF algorithm. For PCC, the MLP algorithm improves by 20.14%, 17.46%, 2.31%, 11.24%, and 15.36% over the other algorithms in that order. For SSMI, the MLP algorithm improved by 16.99%, 8.96%, 17.17%, 14.41%, and 4.85% over the other algorithms, in that order. For HDR-VDR-2, the MLP algorithm improved by 3.02%, 2.79%, 6.84%, 4.90%, and 6.55% over the other algorithms, in that order. The results show that the MLP algorithm can avoid image artifacts while retaining more details. The MLP-based adaptive fusion method is a step further in the theoretical study of multi-exposure image fusion, which is of great significance for subsequent research and practical application by related technology vendors.
To avoid spectrum scarcity problems in wireless communications, cognitive radio concept used as reliable and effective solution. To use proper exploitation of white sources in cognitive radios required accurate, fast ...
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ISBN:
(纸本)9780738146379
To avoid spectrum scarcity problems in wireless communications, cognitive radio concept used as reliable and effective solution. To use proper exploitation of white sources in cognitive radios required accurate, fast and robust methods. In this paper, we proposed new method for detecting white spaces in spectrum. Based on this strategy, cognitive radio performs spectrum sensing via energy detection technique. Main novelty of this paper is adaptive algorithm i.e., error normalized least mean logarithmic square (ENLMLS), it contains the information of primary user presence or absence. Identification of white spaces depends on entity which is able to improve deflection coefficient significantly related with detector when compared to other adaptive algorithms. Simulation results shows that proposed ENLMLS algorithm performs well compared to LMS algorithm by means of convergence. Further by using clipping function, it reduces noise levels and yields missed detection probability is smaller by SNR values and predefined threshold value.
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