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Double adaptive selection strategy for MOEA/D 预览
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作者 GAO Jiale XING Qinghua +1 位作者 FAN Chengli LIANG Zhibing 《系统工程与电子技术:英文版》 SCIE EI CSCD 2019年第1期132-143,共12页
Since most parameter control methods are based on prior knowledge, it is difficult for them to solve various problems. In this paper, an adaptive selection method used for operators and parameters is proposed and name... Since most parameter control methods are based on prior knowledge, it is difficult for them to solve various problems. In this paper, an adaptive selection method used for operators and parameters is proposed and named double adaptive selection (DAS) strategy. Firstly, some experiments about the operator search ability are given and the performance of operators with different donate vectors is analyzed. Then, DAS is presented by inducing the upper confidence bound strategy, which chooses suitable combination of operators and donates sets to optimize solutions without prior knowledge. Finally, the DAS is used under the framework of the multi-objective evolutionary algorithm based on decomposition, and the multi-objective evolutionary algorithm based on DAS (MOEA/D-DAS) is compared to state-of-the-art MOEAs. Simulation results validate that the MOEA/D-DAS could select the suitable combination of operators and donate sets to optimize problems and the proposed algorithm has better convergence and distribution. 展开更多
关键词 MULTI-OBJECTIVE optimization ADAPTIVE OPERATOR SELECTION ADAPTIVE NEIGHBOR SELECTION decomposition.
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Fixed-time adaptive model reference sliding mode control for an air-to-ground missile
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作者 Liang ZHANG Changzhu WEI +1 位作者 Rong WU Naigang CUI 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第5期1268-1280,共13页
This paper addresses the fixed-time adaptive model reference sliding mode control for an air-to-ground missile associated with large speed ranges, mismatched disturbances and un-modeled dynamics. Firstly, a sliding mo... This paper addresses the fixed-time adaptive model reference sliding mode control for an air-to-ground missile associated with large speed ranges, mismatched disturbances and un-modeled dynamics. Firstly, a sliding mode surface is developed by the tracking error of the state equation and the model reference state equation with respect to the air-to-ground missile. More specifically,a novel fixed-time adaptive reaching law is presented. Subsequently, the mismatched disturbances and the un-modeled dynamics are treated as the model errors of the state equation. These model errors are estimated by means of a fixed-time disturbance observer, and they are also utilized to compensate the proposed controller. Therefore, the fixed-time controller is obtained by an adaptive reaching law and a fixed-time disturbance observer. Closed-loop stability of the proposed controller is established. Finally, simulation results including Monte Carlo simulations, nonlinear six-DegreeOf-Freedom(6-DOF) simulations and different ranges are presented to demonstrate the efficacy of the proposed control scheme. 展开更多
关键词 ADAPTIVE controller Air-to-ground MISSILE Fixed-time ADAPTIVE REACHING law Fixed-time disturbance observer Model REFERENCE SLIDING mode control
Efficient multi-response adaptive sampling algorithm for construction of variable-fidelity aerodynamic tables
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作者 Maxim TYAN Jae-Woo LEE 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第3期547-558,共12页
Adaptive sampling is an iterative process for the construction of a global approximation model. Most of engineering analysis tools computes multiple parameters in a single run. This research proposes a novel multi-res... Adaptive sampling is an iterative process for the construction of a global approximation model. Most of engineering analysis tools computes multiple parameters in a single run. This research proposes a novel multi-response adaptive sampling algorithm for simultaneous construction of multiple surrogate models in a time-efficient and accurate manner. The new algorithm uses the Jackknife cross-validation variance and a minimum distance metric to construct a sampling criterion function. A weighted sum of the function is used to consider the characteristics of multiple surrogate models. The proposed algorithm demonstrates good performance on total 22 numerical problems in comparison with three existing adaptive sampling algorithms. The numerical problems include several two-dimensional and six-dimensional functions which are combined into singleresponse and multi-response systems. Application of the proposed algorithm for construction of aerodynamic tables for 2 D airfoil is demonstrated. Scaling-based variable-fidelity modeling is implemented to enhance the accuracy of surrogate modeling. The algorithm succeeds in constructing a system of three highly nonlinear aerodynamic response surfaces within a reasonable amount of time while preserving high accuracy of approximation. 展开更多
关键词 Adaptive sampling Aerodynamic DATABASE Multi-response system Surrogate MODELING VARIABLE FIDELITY MODELING
自适应边界层非奇异快速终端滑模控制
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作者 张贝贝 赵东亚 +1 位作者 高守礼 张佳舒 《控制工程》 CSCD 北大核心 2019年第4期717-723,共7页
针对传统非奇异快速终端滑模在平衡点附近收敛速率比经典终端滑模收敛速率慢的问题,提出了一种非线性不确定系统改进型非奇异快速终端滑模,在平衡点附近获得比经典终端滑模更快的收敛速率。其次,设计了一种自适应边界层非奇异快速终端... 针对传统非奇异快速终端滑模在平衡点附近收敛速率比经典终端滑模收敛速率慢的问题,提出了一种非线性不确定系统改进型非奇异快速终端滑模,在平衡点附近获得比经典终端滑模更快的收敛速率。其次,设计了一种自适应边界层非奇异快速终端滑模算法,使系统状态能有限时间收敛到一个剩余集。自适应边界层的应用进一步提高了系统控制精度,改善了系统鲁棒性。同时,根据Lyapunov理论证明系统的闭环稳定性。最后,通过Matlab仿真表明,对非线性不确定系统,该算法能大大提高系统的控制精度,改善系统鲁棒性。 展开更多
关键词 非奇异快速终端滑模 剩余集 自适应 边界层 非线性不确定系统
基于模糊自适应算法的航天器姿态控制 预览
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作者 周湛杰 王新生 王岩 《电机与控制学报》 EI CSCD 北大核心 2019年第2期123-128,共6页
在研究航天器飞行姿态控制问题上,为避免大范围跟踪时出现奇点情况,采用欧拉参数四元数来对刚体航天器的姿态进行描述。基于自适应控制算法设计航天器姿态稳定控制的控制器,将扰动力矩考虑到自适应控制率的设计过程中,并结合模糊算法进... 在研究航天器飞行姿态控制问题上,为避免大范围跟踪时出现奇点情况,采用欧拉参数四元数来对刚体航天器的姿态进行描述。基于自适应控制算法设计航天器姿态稳定控制的控制器,将扰动力矩考虑到自适应控制率的设计过程中,并结合模糊算法进行参数的在线优化处理。利用李雅普诺夫稳定性理论证明控制系统的稳定性及在有限时间内的收敛性,该控制器的参数易于调节和实现,且由于没有对航天器的动力学方程进行线性化处理,故极大程度上保证了该控制系统的控制精确度。仿真结果表明,当存在外部干扰力矩和参数抖动情况时,所设计的姿态控制器具有良好的稳定性。 展开更多
关键词 姿态控制 模糊 自适应 李雅普诺夫稳定性
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自适应α-shapes平面点云边界提取方法 预览
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作者 廖中平 陈立 +1 位作者 白慧鹏 丁美青 《长沙理工大学学报:自然科学版》 CAS 2019年第2期15-21,共7页
针对基于微切面的点云边界提取方法在LiDAR点云边界提取中效率低,难以保证边界提取的精细度和完整性问题,提出了一种可调节滚动圆半径的α-shapes平面点云边界提取算法.该算法首先将点云数据栅格化,排除非边界点,并通过计算P点的K个邻... 针对基于微切面的点云边界提取方法在LiDAR点云边界提取中效率低,难以保证边界提取的精细度和完整性问题,提出了一种可调节滚动圆半径的α-shapes平面点云边界提取算法.该算法首先将点云数据栅格化,排除非边界点,并通过计算P点的K个邻近点平均距离和增设调节因子,设置滚动圆半径α,最后采用α-shapes算法提取点云边界.对近邻K值、点云形状和点云密度等分析,证明近邻K值与调节因子ω之间具有函数关系,及调节因子与点云密度和点云形状无关的结论.结果证明:该算法在准确提取点云边界情况下,能够快速提取完整点云边界,提高后续点云重建速度与效率,该算法具有良好的稳健性. 展开更多
关键词 点云重建 边界提取 α-shapes 自适应 邻近点
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自适应非线性频率压缩技术在儿童助听器验配中的有效性初探 预览
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作者 刘媛媛 戴瑞邦 杨欣怡(编译) 《中国听力语言康复科学杂志》 2019年第2期150-153,共4页
目的探讨助听器自适应非线性频率压缩技术在儿童中的应用效果和获益情况。方法对14例听力损失为低频轻度到中度、高频重度到极重度,已有助听器使用非线性频率压缩(non-linearfrequencycompression,NLFC)技术的儿童,选配相同品牌和型号... 目的探讨助听器自适应非线性频率压缩技术在儿童中的应用效果和获益情况。方法对14例听力损失为低频轻度到中度、高频重度到极重度,已有助听器使用非线性频率压缩(non-linearfrequencycompression,NLFC)技术的儿童,选配相同品牌和型号并具有自适应NLFC的助听器,采用个性化调试并进行3种不同NLFC设置(NLFC-1、NLFC-2A和NLFC-2B)的助听器配戴,采用安静环境下的西安大略大学(the University of Western Ontario,UWO)复数测试、辅-核-辅(consonant-nucleus-consonant,CNC)单音节词识别测试和峰力音素感知测试(phonakphonemeperception test,PPT)进行效果评估并分析结果。结果在配戴4~6周后,NLFC-2B的UWO复数测试正确率高于NLFC-1(P<0.05);给声强度为50 dB (A)和60 dB (A)的CNC单音节词识别率,NLFC-2A和NLFC-2B均显著高于NLFC-1(P<0.01);不同NLFC设置的PPT觉察阈和识别阈均无显著性差异(P>0.05)。结论自适应NLFC可有效改善儿童的高频言语声识别和CNC单音节词识别,并有适应性好、适应期短的特点。 展开更多
关键词 助听器 儿童 频率压缩技术 自适应
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机器人自适应模糊阻抗控制方法 预览
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作者 徐天雄 刁燕 +1 位作者 罗华 杨少令 《机械工程师》 2019年第1期84-87,共4页
针对机械臂在未知环境或环境参数存在变化的情况下无法有效跟踪目标接触力,提出一种在线调节参考轨迹自适应阻抗控制算法,该方法能够实现精确力控制,并保证机械臂系统的运动稳定。根据力误差信息调整参考轨迹以实现力跟踪。同时引入模... 针对机械臂在未知环境或环境参数存在变化的情况下无法有效跟踪目标接触力,提出一种在线调节参考轨迹自适应阻抗控制算法,该方法能够实现精确力控制,并保证机械臂系统的运动稳定。根据力误差信息调整参考轨迹以实现力跟踪。同时引入模糊调整器实时调整控制算法参数,优化机械臂运动性能。以RRR型三自由度机械臂为例对算法进行仿真验证。仿真结果表明,该方法提高了力控制精度与动态响应,其自适应算法有效增强了机械臂在与外界环境接触时对接触环境参数变换的鲁棒性。 展开更多
关键词 力跟踪 阻抗控制 自适应 模糊 未知环境
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Cloud Service Security Adaptive Target Detection Algorithm Based on Bio-Inspired Performance Evaluation Process Algebra
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作者 ZHAO Guosheng QU Xiaofeng +2 位作者 LIAO Yuting WANG Tiantian ZHANG Jingting 《武汉大学学报:自然科学英文版》 CAS CSCD 2019年第3期185-193,共9页
Combining the principle of antibody concentration with the idea of biological evolution, this paper proposes an adaptive target detection algorithm for cloud service security based on Bio-Inspired Performance Evaluati... Combining the principle of antibody concentration with the idea of biological evolution, this paper proposes an adaptive target detection algorithm for cloud service security based on Bio-Inspired Performance Evaluation Process Algebra(Bio-PEPA). The formal modelling of cloud services is formally modded by Bio-PEPA and the modules are transformed between cloud service internal structures and various components. Then, the security adaptive target detection algorithm of cloud service is divided into two processes, the short-term optimal action selection process which selects the current optimal detective action through the iterative operation of the expected function and the adaptive function, and the long-term detective strategy realized through the updates and eliminations of action planning table. The combination of the two processes reflects the self-adaptability of cloud service system to target detection. The simulating test detects three different kinds of security risks and then analyzes the relationship between the numbers of components with time in the service process. The performance of this method is compared with random detection method and three anomaly detection methods by the cloud service detection experiment. The detection time of this method is 50.1% of three kinds of detection methods and 86.3% of the random detection method. The service success rate is about 15% higher than that of random detection methods. The experimental results show that the algorithm has good time performance and high detection hit rate. 展开更多
关键词 cloud service SECURITY BIO-INSPIRED Performance Evaluation Process ALGEBRA (Bio-PEPA) ADAPTIVE detection biological immunity EVOLUTIONARY mechanism
基于Canny边缘检测思想的改进遥感影像道路提取方法 预览
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作者 黄巍 黄辉先 +1 位作者 徐建闽 刘嘉婷 《国土资源遥感》 CSCD 北大核心 2019年第1期65-70,共6页
基于边缘特征的提取方法被广泛应用于遥感影像道路识别当中,针对传统方法抗噪性较差且易误判和漏判的缺点,基于Canny边缘检测思想,采用一种平滑尺度自适应的高斯滤波对遥感影像降噪,降低噪声干扰,同时保留了边缘细节。在进行双阈值的边... 基于边缘特征的提取方法被广泛应用于遥感影像道路识别当中,针对传统方法抗噪性较差且易误判和漏判的缺点,基于Canny边缘检测思想,采用一种平滑尺度自适应的高斯滤波对遥感影像降噪,降低噪声干扰,同时保留了边缘细节。在进行双阈值的边缘判断环节根据像素点目标尺度范围内的局部特性选取高、低阈值,提高边缘的准确判断能力。实验结果表明,该方法能有效改善边缘检测的准确度和定位精度,提取的道路边缘误判明显减少,完整度和连续性显著增强,且自动化程度高。 展开更多
关键词 遥感影像 道路边缘 CANNY算法 高斯滤波 自适应 双阈值
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Treatment of central sleep apnea in patients with heart failure:Now and future 预览
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作者 Azusa Murata Takatoshi Kasai 《世界呼吸病学杂志》 2019年第1期1-7,共7页
Heart failure(HF) is known to be associated with sleep-disordered breathing(SDB). In addition to disturbing patients’ sleep, SDB is also associated with a deterioration in the cardiac function and an increased mortal... Heart failure(HF) is known to be associated with sleep-disordered breathing(SDB). In addition to disturbing patients’ sleep, SDB is also associated with a deterioration in the cardiac function and an increased mortality and morbidity.Central sleep apnea(CSA), typically characterized by Cheyne-Stokes breathing(CSB), is increasingly found in patients with HF compared to the general population. An important pathogenetic factor of CSA seen in HF patients is an instability in the control of the respiratory system, characterized by both hypocapnia and increased chemosensitivity. Sympathetic overactivation,pulmonary congestion and increased chemosensitivity associated with HF stimulate the pulmonary vagal irritant receptor, resulting in chronic hyperventilation and hypocapnia. Additionally, the repetitive apnea and arousal cycles induce cyclic sympathetic activation, which may worsen the cardiac prognosis. Correcting CSB may improve both patient’s quality of life and HF syndrome itself. However, a treatment for HF in patients also experiencing CSA is yet to be found. In fact, conflicting results from numerous clinical studies investigating sleep apnea with HF guide to a troubling question, that is whether(or not) sleep apnea should be treated in patients with HF? This editorial attempts to both collect the current evidence about randomized control trials investigating CSA in patients with HF and highlight the effect of specific CSA treatments on cardiovascular endpoints. 展开更多
关键词 Central SLEEP APNEA OBSTRUCTIVE SLEEP APNEA Heart failure Positive AIRWAY pressure Adaptive servo-ventilation
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一种新型自适应直流母线电压控制器的研究 预览
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作者 孙士杰 李文荣 +1 位作者 闫海城 张研 《电力电子技术》 CSCD 北大核心 2019年第3期114-116,共3页
针对两级式单相并网逆变器中直流母线电压控制器暂态性能差的问题,提出了一种基于下垂控制理论的自适应直流母线电压控制器。控制器能够实时追踪系统的稳态工作点,在暂态期间能够提供瞬时并网电流参考值,使系统能够快速而稳定地运行。... 针对两级式单相并网逆变器中直流母线电压控制器暂态性能差的问题,提出了一种基于下垂控制理论的自适应直流母线电压控制器。控制器能够实时追踪系统的稳态工作点,在暂态期间能够提供瞬时并网电流参考值,使系统能够快速而稳定地运行。对控制器进行了详细的理论推导和稳定性验证,并依托两级式单相光伏并网逆变器对控制器进行了对比仿真验证,验证了控制器在暂态响应能力方面的优势和可实现性。 展开更多
关键词 电压控制器 下垂控制 自适应
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基于主成分分析的不同品种柑橘制汁适应性研究 预览
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作者 王靓钰 夏其乐 +3 位作者 陈剑兵 曹艳 张俊 关荣发 《果树学报》 CAS CSCD 北大核心 2019年第4期504-513,共10页
【目的】为了筛选出适合生产NFC果汁的柑橘品种,以浙江地区主栽的19个柑橘品种为原料,进行了各个品种的制汁适应性研究。【方法】采用常规方法分析了各个柑橘品种的出汁率、果肉率等品质特性,以及柑橘汁的维生素C、可溶性固形物、可滴... 【目的】为了筛选出适合生产NFC果汁的柑橘品种,以浙江地区主栽的19个柑橘品种为原料,进行了各个品种的制汁适应性研究。【方法】采用常规方法分析了各个柑橘品种的出汁率、果肉率等品质特性,以及柑橘汁的维生素C、可溶性固形物、可滴定酸、可溶性糖、总酚、总黄酮等营养理化指标,对比了不同品种柑橘之间的差异,然后采用主成分分析法(PCA)建立了柑橘品质评价体系,作为评价不同品种柑橘汁综合品质的依据。【结果】不同柑橘品种的品质存在显著差异,‘红美人’‘山下红’‘宫川’‘天草’‘尾张温州蜜柑’等品种出汁率高,具有较大的果汁加工潜力,但其总黄酮、总酚、维生素C这3项指标含量略低,因此口感有所欠缺。经由主成分分析,从9项原始指标提取出3个主成分,累计方差贡献率达到86.728%。以3个主成分及单个主成分所对应的特征值占所提取主成分总的特征值之和的比例作为权重,构建了柑橘综合品质评价模型,作为筛选适合制作柑橘汁的柑橘品种的方法。【结论】根据该评价模型计算浙江地区19个柑橘品种的综合得分,可将不同品种的柑橘分为三类。分值较高的是‘冰糖橙’‘纽荷尔脐橙’‘瓯柑’,分值较合适的是‘丽椪2号’‘山下红’‘满头红’‘鸡尾葡萄柚’‘中育橙’。通过该评价体系,可以较为便捷地选取出营养价值较高且风味口感较好的柑橘品种。同时考虑果肉率、出汁率等因素,可以提供直观的柑橘品质评价,为企业选取适合柑橘汁制备原料品种提供依据。 展开更多
关键词 柑橘 制汁 筛选 理化指标 主成分分析(PCA) 适应性 评价体系
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Quality Assessment and Measurement for Internet Video Streaming 预览
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作者 ZHANG Xinggong XIE Lan GUO Zongming 《中兴通讯技术:英文版》 2019年第1期12-17,共6页
Benefiting from the improvements of Internet infrastructure and video coding technology,online video services are becoming a new favorite form of video entertainment.However,most of the existing video quality assessme... Benefiting from the improvements of Internet infrastructure and video coding technology,online video services are becoming a new favorite form of video entertainment.However,most of the existing video quality assessment methods are designed for broadcasting/cable televisions and it is still an open issue how to assess and measure the quality of online video services.In this paper,we survey the state-of-the-art video streaming technologies,and present a framework of quality assessment and measurement for Internet video streaming.This paper introduces several metrics for user’s quality of experience (QoE).These QoE metrics are classified into two categories: objective metrics and subjective metrics.It is different for service participators to measure objective and subjective metrics.The QoE measurement methodologies consist of client-side,server-side,and in-network measurement. 展开更多
关键词 Internet VIDEO STREAMING QOE QOE ASSESSMENT and MEASUREMENT HTTP ADAPTIVE STREAMING
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Automating QoS and QoE Evaluation of HTTP Adaptive Streaming Systems 预览
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作者 Christian Timmerer Anatoliy Zabrovskiy 《中兴通讯技术:英文版》 2019年第1期18-24,共7页
Streaming audio and video content currently accounts for the majority of the Internet traffic and is typically deployed over the top of the existing infrastructure.We are facing the challenge of a plethora of media pl... Streaming audio and video content currently accounts for the majority of the Internet traffic and is typically deployed over the top of the existing infrastructure.We are facing the challenge of a plethora of media players and adaptation algorithms showing different behavior but lacking a common framework for both objective and subjective evaluation of such systems.This paper aims to close this gap by proposing such a framework,describing its architecture,providing an example evaluation,and discussing open issues. 展开更多
关键词 HTTP ADAPTIVE STREAMING DASH QOE performance EVALUATION
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主动容错云存储系统的信息自适应管理调度模型 预览
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作者 朱洁 《智能计算机与应用》 2019年第2期224-227,共4页
为了提高主动容错云存储系统的信息智能管理水平,需要进行信息调度优化设计,提出一种基于云存储信息传感融合的主动容错云存储系统的资源信息自适应调度算法。进行主动容错云存储系统的资源信息传感分布存储设计,提取主动容错云存储系... 为了提高主动容错云存储系统的信息智能管理水平,需要进行信息调度优化设计,提出一种基于云存储信息传感融合的主动容错云存储系统的资源信息自适应调度算法。进行主动容错云存储系统的资源信息传感分布存储设计,提取主动容错云存储系统的资源信息流的关联规则特征,构建云存储系统资源信息语义本体模型,计算信息自适应调度的加权系数,进行云存储信息传感融合识别,实现对云存储系统的信息管理和调度。仿真实验表明,该方法能提高主动容错云存储系统中资源信息的自适应调度能力,信息管理的智能性较好,均衡控制能力较强。 展开更多
关键词 主动容错 云存储系统 信息管理 自适应 调度
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Phylogenetic relationships of Cypriniformes and plasticity of pharyngeal teeth in the adaptive radiation of cyprinids
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作者 Wenjing Tao Lei Yang +1 位作者 Richard L.Mayden Shunping He 《中国科学:生命科学英文版》 SCIE CAS CSCD 2019年第4期553-565,共13页
The Cypriniformes comprise approximately 4,200 species accounting for 25% of the diversity of all freshwater fish,which is widely distributed across the world’s continents except Antarctica,South America,and Australi... The Cypriniformes comprise approximately 4,200 species accounting for 25% of the diversity of all freshwater fish,which is widely distributed across the world’s continents except Antarctica,South America,and Australia.The highest species diversity is found in Southeastern Asia.Despite its remarkable species diversity and broad-scale geographic patterns of distribution,the evolutionary history of this major freshwater fish group remains largely unresolved.To gain insight of the evolutionary history of Cypriniformes,we present a phylogeny of this group using 1 mitochondrial gene and 15 nuclear genes comprising a total of14,061 bp.Bayesian inference using all gene fragments yielded a well resolved phylogeny,which is mostly consistent with topologies obtained from Maximum Likelihood analyses.Our results further confirmed the monophyly of Cypriniformes and seven constituent subclades including Cyprinidae,Catostomidae,Gyrinocheilidae,Balitoridae,Cobitidae,Nemacheilidae,and Botiidae.Bayesian divergence time analysis indicated that the origin of the Cypriniformes was about 193 Mya during the early Jurassic,coinciding with the onset of the Pangaea breakup.The basal divergence of Cypriniformes is 154 Mya during the late Jurassic.Our findings from molecular divergence and biogeographical analysis indicate the most likely initial geographical range of the ancient Cypriniformes was both East and South Asia(Southeastern area of Mesozoic Laurasia).Moreover,the burst in species diversity in Cyprinidae afforded by the nearly worldwide colonization is possibly in response to the plasticity of pharyngeal dentition.The present study demonstrates that the Cypriniformes was about 193 Mya during the early Jurassic,coinciding with the onset of the Pangaea breakup.The plasticity of pharyngeal dentition of cyprinids might contribute to the burst and radiation of this lineage.The phylogenetic and biogeographic analyses in this study help to improve our understanding of the evolutionary history of this diverse and important freshwater fis 展开更多
关键词 PHYLOGENY biogeographic analyses CYPRINIFORMES PHARYNGEAL teeth adaptive radiation
基于自适应动态改变的粒子群优化算法
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作者 仝秋娟 赵岂 李萌 《微电子学与计算机》 北大核心 2019年第2期6-10,15共6页
粒子群算法在处理优化问题时缺乏有效的参数控制,易陷入局部最优,导致收敛精度低.提出一种新的改进粒子群优化算法,算法根据粒子的适应度值动态自适应地调整算法中惯性权重和学习因子的取值,其中惯性权重采用非线性指数递减,有利于平衡... 粒子群算法在处理优化问题时缺乏有效的参数控制,易陷入局部最优,导致收敛精度低.提出一种新的改进粒子群优化算法,算法根据粒子的适应度值动态自适应地调整算法中惯性权重和学习因子的取值,其中惯性权重采用非线性指数递减,有利于平衡算法的全局搜索与局部搜索能力,避免算法陷入局部极值;学习因子采用异步变化的策略,以增强算法的学习能力,进而提高算法的性能.数值实验结果表明,与SPSO、PSO-DAC算法相比较,改进后的算法无论在收敛速度、稳定性以及收敛精度上都有显著提高. 展开更多
关键词 粒子群算法 惯性权重 学习因子 自适应
基于自适应末端滑膜控制的无人机抖振抑制方法
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作者 刘炜 《国外电子测量技术》 2019年第2期19-24,共6页
无人机在飞行末端受到气流层的快速变化容易出现抖振,为了提高无人机飞行稳定性,提出一种基于自适应末端滑膜控制的无人机抖振抑制方法。采用自适应终端滑膜控制方法进行无人机末端轨迹飞行的抖振抑制,构建无人机末端轨迹飞行姿态稳定... 无人机在飞行末端受到气流层的快速变化容易出现抖振,为了提高无人机飞行稳定性,提出一种基于自适应末端滑膜控制的无人机抖振抑制方法。采用自适应终端滑膜控制方法进行无人机末端轨迹飞行的抖振抑制,构建无人机末端轨迹飞行姿态稳定控制的姿态参数模型和动力学模型,分析无人机末端轨迹飞行的约束参量,将无人机末端轨迹飞行的抖振抑制问题转化为高维C-空间中的多约束运动规划问题,有效实现无人机的巡航、滑翔、着落等运动规划控制,在惯性姿态空间内构造无人机末端轨迹飞行姿态控制的滑膜面,采用终端轨迹自适应调节方法进行抖振抑制,实现无人机末端轨迹飞行姿态调节的自适应控制。仿真结果表明,采用该方法进行无人机末端轨迹飞行姿态控制的稳定性较好,抖振抑制性较好,在末端轨迹飞行姿态调节过程中能实现鲁棒性控制,提高了末端轨迹飞行姿态调节的控制精度。 展开更多
关键词 自适应 末端滑膜控制 无人机 抖振抑制
Adaptive Numerical Approach for Optimal Control of a Single Train
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作者 WU Xiang ZHANG Kanjian CHENG Ming 《系统科学与复杂性学报:英文版》 SCIE EI CSCD 2019年第4期1053-1071,共19页
This paper considers the optimal control problem of a single train,which is formulated as an optimal control problem of nonlinear systems with switching controller.The switching sequence and the switching time are dec... This paper considers the optimal control problem of a single train,which is formulated as an optimal control problem of nonlinear systems with switching controller.The switching sequence and the switching time are decision variables to be chosen optimally.Generally speaking,it is very difficult to solve this problem analytically due to its nonlinear nature,the complexity of the controller,and the existence of system state and control input constraints.To obtain the numerical solution,by introducing binary functions for every value of the control input,relaxing the binary functions,and imposing a penalty function on the relaxation,the problem is transformed into a parameter optimization problem,which can be efficiently solved by using any gradient-based numerical approach.Then,the authors propose an adaptive numerical approach to solve this problem.Convergence results indicate that any optimal solution of the parameter optimization problem is also an optimal solution of the original problem.Finally,an optimal control problem of a single train illustrates that the adaptive numerical approach proposed by us is less time-consuming and obtains a better cost function value than the existing approaches. 展开更多
关键词 ADAPTIVE numerical approach nonlinear system optimal CONTROL SWITCHING CONTROLLER TRAIN CONTROL
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