Zernike moments (ZMs) are widely used in many image analysis and pattern recognition problems because of their superiority compared with other moments. However, they suffer from high computation cost and inherent erro...
详细信息
Zernike moments (ZMs) are widely used in many image analysis and pattern recognition problems because of their superiority compared with other moments. However, they suffer from high computation cost and inherent error. Previous researches have shown that the algorithm, computing ZMs in polar system, improves the ZMs accuracy of the reconstruction and invariance properties dramatically. In this study, the authors firstly modify a direct method for computing ZMs in polar coordinates and present a recursive relation. Then, this study presents an algorithm for fast computation of ZMs, based on the improved polar pixel tiling scheme. Owing to the symmetrical property, ZMs can be obtained by computing only one-sixteenth circle of the radial polynomials, which means that the number of pixels involved in the computation of ZMs is only 6.25% of the previous method. This leads to a significant reduction in the computational complexity requirements. A comparison with the other conventional method is performed in detail. The obtained results show the superiority of the proposed method.
Pneumatic muscle (PM) has many advantages such as light weight, high power to weight ratio and low price. However, it has strong time varying characteristic. The complex nonlinear dynamics of PM system poses some chal...
详细信息
Pneumatic muscle (PM) has many advantages such as light weight, high power to weight ratio and low price. However, it has strong time varying characteristic. The complex nonlinear dynamics of PM system poses some challenges for achieving accurate modeling and control. To solve these problems, we propose nonlinear internal model control (IMC) using echo state network (ESN) for PM system in this paper. The ESN based IMC is termed ESNBIMC, which fully embodies the virtues of ESN and IMC. In ESNBIMC, the dynamic model of PM system is identified by an ESN. The other ESN is trained to learn the inverse dynamics of the system, and then it can be used as a nonlinear controller. Recursive Least Square (RLS) algorithm can be applied to online training the ESN without affecting the previous weight structure, which is very suitable for real-time control problems. By using the identification ability of ESN and RLS, high accurate plant model of PM system without detailed model information can be built. In addition, strong robustness also can be attained by online self-tuning of controller and internal model. Experiment demonstrates the effectiveness of the proposed control algorithm. The results show that ESNBIMC achieves satisfactory tracking performance for PM system.
Recently, experiments have demonstrated that simple binary arithmetic and logical operations can be computed by the process of self- assembly of DNA tiles. In this paper, we show how the tile assembly process can be u...
详细信息
Recently, experiments have demonstrated that simple binary arithmetic and logical operations can be computed by the process of self- assembly of DNA tiles. In this paper, we show how the tile assembly process can be used for subtraction and division. In order to achieve this aim, four systems, including the comparator system, the duplicator system, the subtraction system, and the division system, are pro- posed to compute the difference and quotient of two input numbers using the tile assembly model. This work indicates that these systems can be carried out in polynomial time with optimal O(1) distinct tile types in parallel and at very low cost. Furthermore, we provide a scheme to factor the product of two prime numbers, and it is a breakthrough in basic biological operations using a molecular computer by self-assembly.
Membrane proteins are an important kind of proteins embedded in the membranes of cells and play crucial roles in living organisms, such as ion channels,transporters, receptors. Because it is difficult to determinate t...
详细信息
Membrane proteins are an important kind of proteins embedded in the membranes of cells and play crucial roles in living organisms, such as ion channels,transporters, receptors. Because it is difficult to determinate the membrane protein's structure by wet-lab experiments,accurate and fast amino acid sequence-based computational methods are highly desired. In this paper, we report an online prediction tool called Mem Brain, whose input is the amino acid sequence. Mem Brain consists of specialized modules for predicting transmembrane helices, residue–residue contacts and relative accessible surface area of a-helical membrane proteins. Mem Brain achieves aprediction accuracy of 97.9% of ATMH, 87.1% of AP,3.2 ± 3.0 of N-score, 3.1 ± 2.8 of C-score. Mem BrainContact obtains 62%/64.1% prediction accuracy on training and independent dataset on top L/5 contact prediction,respectively. And Mem Brain-Rasa achieves Pearson correlation coefficient of 0.733 and its mean absolute error of13.593. These prediction results provide valuable hints for revealing the structure and function of membrane *** Brain web server is free for academic use and available at ***/bioinf/Mem Brain/.
This study investigates the consensus problem of second-order multi-agent systems (MASs) via impulsive control using position-only information with communication delays. The communication delays between any two distin...
详细信息
Presently pneumatic muscles (PMs) are used in various applications due to their simple construction, lightweight and high force to weight ratio. However, pneumatic muscles are facing various problems due to their nonl...
详细信息
High-precision semantic segmentation methods require global information and more detailed local features. It is difficult for ordinary convolutional neural networks to efficiently use this information. In response to ...
详细信息
High-precision semantic segmentation methods require global information and more detailed local features. It is difficult for ordinary convolutional neural networks to efficiently use this information. In response to the above issues, this paper uses the attention to scale method and proposes a novel attention model for semantic segmentation, which aggregates multi-scale and context features to refine prediction. Specifically, the skeleton convolutional neural network framework takes in multiple different scales inputs, by which means the CNN can get representations in different scales. The proposed attention model will handle the features from different scale streams respectively and integrate them. Then location attention branch of the model learns to softly weight the multi-scale features at each pixel location. Moreover, we add an recalibrating branch, parallel to where location attention comes out, to recalibrate the score map per class. We achieve quite competitive results on PASCAL VOC 2012 and ADE20K datasets, which surpass baseline and related works.
This paper focuses on the discrete-time automatic pipeline, inventory and order-based production control system (APIOBPCS), a well-established production and inventory control model. The feedback mechanism within the ...
详细信息
This paper focuses on the discrete-time automatic pipeline, inventory and order-based production control system (APIOBPCS), a well-established production and inventory control model. The feedback mechanism within the replenishment rule enables the model to mitigate the bullwhip effect, but introduces a stability problem. In this research, a comprehensive stability analysis is conducted for arbitrary lead times using difference equation theory. On the basis of stability, a state space approach is advocated to analyse the impact of replenishment parameters, demand processes, and lead times on the robustness of the bullwhip effect. The stability results demonstrate that the production control system can easily be destabilised without incorporating the work-in-progress (WIP) feedback loop. Furthermore, it reveals that the stability problem for long lead times can be simplified with the stability condition independent of the lead time. The results obtained in this study provide useful guidelines for the selection of replenishment parameters to guarantee stability and mitigate the bullwhip effect.
AC-DC-AC converter-fed induction motor (IM) drive is mainly realized by back-to-back three-phase converters. However, fault in a single semiconductor switch will make it inoperative. To enable continued controllable o...
详细信息
AC-DC-AC converter-fed induction motor (IM) drive is mainly realized by back-to-back three-phase converters. However, fault in a single semiconductor switch will make it inoperative. To enable continued controllable operation in case of the faults occurring in the converter, the five-leg converter with a shared leg between the grid and load sides is a possible solution. However, this topology poses an inherent two-objective control problem, because its grid and load sides should be controlled simultaneously. More importantly, the potential increase of the shared-leg current may destroy the converters. In this paper, a new control scheme based on the FCS-MPC combined with intrinsic characteristic of the five-leg converter is proposed for independent control of the rectifier and inverter subsystem with the shared-leg overcurrent constraint. The condition for independent control is analyzed. In order to give a complete evaluation of the proposed control scheme, the conventional pulsewidth modulation (PWM) control scheme is conducted for comparison. Experimental results are provided to validate the effectiveness of the proposed scheme.
A novel fault-tolerant system for a multi-motor drive with one-leg, two-leg, and secondary faults is designed in this study. Fault tolerance is realized from pre-fault to post-fault via a topology reconstruction schem...
详细信息
A novel fault-tolerant system for a multi-motor drive with one-leg, two-leg, and secondary faults is designed in this study. Fault tolerance is realized from pre-fault to post-fault via a topology reconstruction scheme and an integrated control law. The scheme develops a reconstructible topology and its reconstruction algorithm. The multi-motor drive can be reconstructed into appropriate tolerant topologies on the basis of the diagnosis results. The control law based on the predictive torque control method is universal under any topology by designing a unified voltage vector model and an optimal switching state decision. The proposed system can cope with more types of faults and effectively switch from a healthy state to a fault-tolerant state under any fault. The effectiveness and performance of the fault-tolerant system are verified and demonstrated by simulation and experiment results.
暂无评论