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1.
《International Journal of Hydrogen Energy》2022,47(85):36216-36231
The fuel cell/battery durability and hybrid system stability are major considerations for the power management of fuel cell hybrid electric bus (FCHEB) operating on complicated driving conditions. In this paper, a real time nonlinear adaptive control (NAC) with stability analyze is formulated for power management of FCHEB. Firstly, the mathematical model of hybrid power system is analyzed, which is established for control-oriented design. Furthermore, the NAC-based strategy with quadratic Lyapunov function is set up to guarantee the stability of closed-loop power system, and the power split between fuel cell and battery is controlled with the durability consideration. Finally, two real-time power management strategies, state machine control (SMC) and fuzzy logic control (FLC), are implemented to evaluate the performance of NAC-based strategy, and the simulation results suggest that the guaranteed stability of NAC-based strategy can efficiently prolong fuel cell/battery lifespan and provide better fuel consumption economy for FCHEB. 相似文献
2.
诱导式卫星欺骗干扰可诱导航空器逐渐偏离预定航迹,难以被发现,因此及时有效地检测干扰是飞行安全的保障。在现有紧组合导航体制基础上,设计了一种基于误差估值累加开环校正的紧组合导航结构,并证明了其性能与传统闭环校正紧组合导航性能等效。在此结构中,将紧组合导航系统与自适应序贯概率比检测方法结合,提出了一种基于误差估值累加开环校正的诱导式欺骗检测方法,融合紧组合导航信息与其他不受欺骗影响的导航信息,构建欺骗检测统计量进行诱导式欺骗检测。仿真结果表明,开环校正结构可避免随时间累加的惯性导航系统误差所导致的组合导航滤波器发散问题,同时欺骗检测方法可进一步提高算法对“最坏”情形下微小诱导式欺骗的检测效果。 相似文献
3.
4.
Nirupaplava Metta Rohit Ramachandran Marianthi Ierapetritou 《American Institute of Chemical Engineers》2021,67(2):e17095
Identification of feasible region of operations in multivariate processes is a problem of interest in several fields. This is particularly challenging when the process model is black-box in nature and/or is computationally expensive, as analytical solutions are not available and the number of possible model evaluations is limited. An efficient methodology is required to identify samples where the model is evaluated for developing a computationally efficient surrogate model. In this work, an artificial neural network based surrogate model is proposed which is integrated with a statistical-based approach (Jack-knifing) to estimate the variance of the surrogate model prediction. This allows implementation of an adaptive sampling approach where new samples are identified close to the feasible region boundary or in regions of high prediction uncertainty. The proposed approach performs better than a previously published kriging based method for different dimensionality case studies. 相似文献
5.
针对基于局部熵进行加密图像视觉安全性评估存在块效应的局限性,引入图像的边缘特征,通过共有边缘来衡量加密图像与原始图像的边缘相似度,消除了块效应。由于局部熵对加密等级低的图像不敏感,边缘相似度对加密等级高的图像不敏感,将两个评估方法进行自适应融合,提出[SLEES](Local Entropy and Edge Similarity,[SLEES])指标。通过改变图像像素位置和图像像素值的加密方式处理图像和视频帧进行测试,实验结果表明,[SLEES]指标相比传统评估指标有更好的鲁棒性,评估范围更广。 相似文献
6.
5G standard uses millimeter wave band to realize communication. In order to cover more reasonable in 5G communication
system, beamforming technology must be adopted. To speed up the convergence, a novel algorithm based on the SWO criterion is
proposed which can be applied in millimeter wave communication. The simulation results show that compared with other beamform-
ing algorithms, the proposed algorithm can achieve higher convergence speed and is more realizable. 相似文献
7.
Hamidreza Jafarnejadsani Neng Wan Naira Hovakimyan Petros G. Voulgaris 《国际强度与非线性控制杂志
》2020,30(3):1071-1097
》2020,30(3):1071-1097
Autonomous systems are rapidly becoming an integrated part of the modern life. Safe and secure navigation and control of these systems present significant challenges in the presence of uncertainties, physical failures, and cyber attacks. In this paper, we formulate a navigation and control problem for autonomous systems using a multilevel control structure, in which the high‐level reference commands are limited by a saturation function, whereas the low‐level controller tracks the reference by compensating for disturbances and uncertainties. For this purpose, we consider a class of nested, uncertain, multiple‐input–multiple‐output systems subject to reference command saturation, possibly with nonminimum phase zeros. A multirate output‐feedback adaptive controller is developed as the low‐level controller. The sampled‐data (SD) design of this controller facilitates the direct implementation on digital computers, where the input/output signals are available at discrete time instances with different sampling rates. In addition, stealthy zero‐dynamics attacks become detectable by considering a multirate SD formulation. Robust stability and performance of the overall closed‐loop system with command saturation and multirate adaptive control are analyzed. Simulation scenarios for navigation and control of a fixed‐wing drone under failures/attacks are provided to validate the theoretical findings. 相似文献
8.
R. Gardinal G.D. Calomeni F. Zanferari T.H.A. Vendramini C.S. Takiya H.G. Bertagnon C.F. Batista A.M.M.P. Della Libera F.P. Renno 《Journal of dairy science》2018,101(1):661-674
The objective of this study was to evaluate different durations of whole raw soybean (WS) supplementation (diet rich in n-6 fatty acid) during the prepartum period on cellular immune function of dairy cows in the transition period and early lactation. Thirty-one Holstein cows were used in a completely randomized design and assigned to 4 experimental groups (G) [G90, G60, G30, and G0 (control)] supplemented with a diet containing 12% of WS from 90, 60, 30 and 0 d relative to the calving date, respectively. Cows were dried off 60 d before the expected calving date. After parturition, all cows were fed a diet containing 12% of WS until 84 DIM. Blood samples were collected before the morning feeding (d ?56 ± 2, ?28 ± 2, ?14 ± 2, ?7 ± 2, at the day of partum, 7 ± 2, 14 ± 2, 28 ± 2, and 56 ± 2 relative to parturition). Cell phenotyping and phagocytosis assays were carried out using monoclonal antibodies and flow cytometry technique. Duration of WS supplementation linearly increased the percentage of blood CD3+ cells, as well as increased the percentage of blood CD8+ cells in the postpartum period, notably in G30, whereas the lowest values were observed in G0. Further, the duration of WS supplementation linearly increased the reactive oxygen species median fluorescence intensity of CH138+ cells after phagocytizing Staphylococcus aureus in the postpartum period. Longer periods of WS supplementation linearly increased phagocytosis median fluorescence intensity of CH138+ cells in the prepartum period of cows. Duration of WS supplementation linearly increased the percentage of blood CD14+ cells producing reactive oxygen species when stimulated either by Staph. aureus or Escherichia coli in the postpartum period. In conclusion, longer periods of WS supplementation during late lactation and the dry period (beginning on d 90 of the expected calving date) alter the leukocyte population and improve neutrophil immune response in the postpartum period with no detrimental effects on cow performance. 相似文献
9.
针对低信噪比(SNR)环境下传统方法对声信号降噪的局限性,提出了一种联合自适应阈值活动语音检测(VAD)算法和最小均方误差对数谱幅度估计(MMSE-LSA)的实时降噪算法。首先,在VAD算法中通过基于能量概率最大值的概率统计来对背景噪声进行估计,对得到的背景噪声进行实时更新并保存;然后,将实时更新的背景噪声作为MMSE-LSA的参考噪声,并对噪声幅度谱进行自适应更新,最后进行降噪处理。通过在真实场景中对四类声信号进行实验,结果表明,该算法在保证对低SNR声信号的实时处理的情况下,相较于传统MMSE-LSA算法,降噪信号的SNR能够提高10~15 dB,且不存在信号过减的情况,可应用于实际工程。 相似文献
10.
ABSTRACTFeature selection is an important task to improve the classifier’s accuracy and to decrease the problem size. A number of methodologies have been presented for feature selection problems using metaheuristic algorithms. In this paper, an improved self-adaptive inertia weight particle swarm optimisation with local search and combined with C4.5 classifiers for feature selection algorithm is proposed. In this proposed algorithm, the gradient base local search with its capacity of helping to explore the feature space and an improved self-adaptive inertia weight particle swarm optimisation with its ability to converge a best global solution in the search space. Experimental results have verified that the SIW-APSO-LS performed well compared with other state of art feature selection techniques on a suit of 16 standard data sets. 相似文献