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Haowei Zhang Junwei Xie Jiaang Ge Zhaojian Zhang Binfeng Zong 《European Journal of Operational Research》2019,272(3):868-878
A phased array radar (PAR) is used to detect new targets and update the information of those detected targets. Generally, a large number of tasks need to be performed by a single PAR in a finite time horizon. In order to utilize the limited time and the energy resources, it is necessary to provide an efficient task scheduling algorithm. However, the existing radar task scheduling algorithms can't be utilized to release the full potential of the PAR, because of those disadvantages such as full PAR task structure ignored, only good performance in one aspect considered and just heuristic or the meta-heuristic method utilized. Aiming at above issues, an optimization model for the PAR task scheduling and a hybrid adaptively genetic (HAGA) algorithm are proposed. The model considers the full PAR task structure and integrates multiple principles of task scheduling, so that multi-aspect performance can be guaranteed. The HAGA incorporates the improved GA to explore better solutions while using the heuristic task interleaving algorithm to utilize wait intervals to interleave subtasks and calculate fitness values of individuals in efficient manners. Furthermore, the efficiency and the effectiveness of the HAGA are both improved by adopting chaotic sequences for the population initialization, the elite reservation and the mixed ranking selection, as well as designing the adaptive crossover and the adaptive mutation operators. The simulation results demonstrate that the HAGA possesses merits of global exploration, faster convergence, and robustness compared with three state-of-art algorithms—adaptive GA, hybrid GA and highest priority and earliest deadline first heuristic (HPEDF) algorithm. 相似文献
915.
为解决空中编队目标跟踪过程中航迹关联的难题,提出一种基于目标运动状态的自适应相关波门算法。首先通过分析编队目标的运动特征,完成编队分割和编队速度的估计;然后将编队目标的速度方向作为约束自适应波门的条件,在跟踪过程中根据目标运动方向确定波门方向,并基于前一时刻编队中各目标的距离来选择波门尺寸,同时考虑测量误差和预测误差的影响。仿真结果表明:相对于传统的固定波门算法,在编队目标跟踪过程中,自适应波门算法在避免编队内目标航迹相互交错和保证跟踪稳定性方面可以达到较好的跟踪效果。 相似文献
916.
通过拉大端射天线阵元间距到1.5λ,可以获得组阵高增益,但是引入了栅瓣问题。提出了一种基于最小二乘估计的虚拟内插阵元算法来实现栅瓣抑制。虚拟端射阵列的阵元间距减小到(或者小于)0.5λ,这样栅瓣得到抑制。最后进行试验验证算法的可行性和正确性。试验结果表明:随着虚拟内插端射天线阵元个数的增加,栅瓣明显被抑制,峰值副瓣电平降低。在相邻两个实阵元间内插3个虚拟阵元,虚拟端射阵列保持了实端射阵列高增益,而实阵列峰值副瓣电平为-8.35dB,下降到虚拟阵列峰值副瓣电平为-18.25dB,栅瓣得到有效抑制。试验结果验证了基于最小二乘估计的虚拟内插阵元算法的可行性和正确性。 相似文献
917.
Tae-Wook Kim Nathan Cernetic Yan Gao Sukang Bae Sanghyun Lee Hong Ma Hongzheng Chen Alex K.-Y. Jen 《Organic Electronics》2014,15(11):2775-2782
Low voltage organic field effect memory transistors are demonstrated by adapting a hybrid gate dielectric and a solution processed graphene oxide charge trap layer. The hybrid gate dielectric is composed of aluminum oxide (AlOx) and [8-(11-phenoxy-undecyloxy)-octyl]phosphonic acid (PhO-19-PA) plays an important role of both preventing leakage current from gate electrode and providing an appropriate surface energy to allow for uniform spin-casting of graphene oxide (GO). The hybrid gate dielectric has a breakdown voltage greater than 6 V and capacitance of 0.47 μF/cm2. Graphene oxide charge trap layer is spin-cast on top of the hybrid dielectric and has a resulting thickness of approximately 9 nm. The final device structure is Au/Pentacene/PMMA/GO/PhO-19-PA/AlOx/Al. The memory transistors clearly showed a large hysteresis with a memory window of around 2 V under an applied gate bias from 4 V to −5 V. The stored charge within the graphene oxide charge trap layer was measured to be 2.9 × 1012 cm−2. The low voltage memory transistor operated well under constant applied gate voltage and time with varying programming times (pulse duration) and voltage pulses (pulse amplitude). In addition, the drain current (Ids) after programming and erasing remained in their pristine state after 104 s and are expected to be retained for more than one year. 相似文献
918.
Anirban Chatterjee Gautam Kumar Mahanti Gourab Ghatak 《International Journal of Satellite Communications and Networking》2014,32(1):25-47
A pattern synthesis method based on Firefly Algorithm (FA) and Artificial Bee Colony (ABC) optimization has been presented to generate satellite footprint patterns from a rectangular planar array of isotropic antennas by modifying the amplitude, phase, and the state of the array elements. Three cases comprising three different footprints of rectangular, square, and circular boundary are generated from the same array by using two different swarm‐based optimization algorithms FA and ABC. Both the algorithms, following the proposed procedures are able to generate the three different footprint patterns while maintaining a satisfactory lower peak side lobe level and ripple. A comparative analysis has been carried out between FA, ABC, and Genetic Algorithm (GA) for the presented problem in terms of fitness value for the three different cases. The superiority of FA and ABC over GA has been established in terms of finding better solutions for all the three cases of the proposed problem. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
919.
最大功率点跟踪控制的目的是为了将光伏阵列发出的最大能量实时地提供给负载,使光伏发电系统的能量利用率达到最大。在光伏阵列产生电能的应用中,有许多不确定因素,如太阳光照强度、光伏阵列温度的变化、负载的变化、光伏阵列输出特性的非线性,则建立模型分析光伏阵列输出最大功率要考虑很多的因素。从模糊控制技术的分析中知道,模糊控制不需要对被控对象建立精确的数学模型,是一种相对简单的智能控制方法,对处理非线性问题有很好的效果。因此,用模糊控制法来实现MPPT可以得到比较好的效果。本文基于此研究了光伏阵列的非线性功率输出特性,建立了基于Matlab simulink/Power system的光伏阵列仿真模型,对基于模糊控制采用扰动观察法进行光伏发电最大功率点跟踪进行了仿真验证。 相似文献
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