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[0,1]-拟阵模糊基的进一步研究
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作者 林福宁 李生刚 杨小飞 《吉林大学学报(理学版)》 CAS CSCD 北大核心 2016年第6期1300-1306,共7页
进一步研究保证[0,1]-拟阵模糊基具有存在性、等势性和交换性的条件,通过引入有界性、饱和性和强基好性的概念,给出有界性与闭性、饱和性与正则性、强基好性与基好性之间的关系.
关键词 [0 1]-拟阵 模糊基 有界性 饱和性 强基好性
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抑制尾流扰动的舰载机纵向自动着舰预测控制 被引量:2
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作者 王立鹏 王立辉 +1 位作者 张智 朱齐丹 《计算机仿真》 北大核心 2019年第3期50-55,60,共7页
针对舰载机着舰过程中舰尾流扰动引发的航迹跟踪精度下降问题,设计了有效抑制舰尾流的纵向自动着舰引导律。以F/A-18舰载机为研究对象,根据其气动参数建立含扰动变量的非线性着舰模型,建立着舰平衡点处的线性小扰动模型,对模型的系统及... 针对舰载机着舰过程中舰尾流扰动引发的航迹跟踪精度下降问题,设计了有效抑制舰尾流的纵向自动着舰引导律。以F/A-18舰载机为研究对象,根据其气动参数建立含扰动变量的非线性着舰模型,建立着舰平衡点处的线性小扰动模型,对模型的系统及扰动矩阵扩展化处理,采用正不变集和二次有界系统的相关理论,阐述抑制舰尾流扰动理论和算法的实现过程,推导相应的线性矩阵不等式,得出有效抑制有界扰动的自动着舰预测控制算法。将自动着舰引导律作用于半物理仿真平台的非线性着舰模型上,验证了抑制扰流和自动着舰有效性。 展开更多
关键词 舰载机 舰尾流 自动着舰 二次有界 正不变集
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英汉形状表量结构界限灵活性的认知建构研究
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作者 李勇忠 尹利鹏 《外语学刊》 CSSCI 北大核心 2020年第3期33-37,共5页
语言界限的设置是人类主观能动地认知世界的产物,是对认知客体有无边界的感知。英汉两种语言中形状表量结构是对客体名词的有界化,即为语言界限设置的具体表现形式之一。该结构对认知客体的赋界有明显的灵活性和多样性特点,同一形状表... 语言界限的设置是人类主观能动地认知世界的产物,是对认知客体有无边界的感知。英汉两种语言中形状表量结构是对客体名词的有界化,即为语言界限设置的具体表现形式之一。该结构对认知客体的赋界有明显的灵活性和多样性特点,同一形状表量结构既可界化具体认知客体,亦可界化抽象不定之物;且对不同类别客体边界的设置也形态各异。本文旨在对英汉形状表量结构的赋界灵活性进行探究,分析该现象的认知建构成因,主要体现在3个方面:形状表量结构的构式意义、表形状量词的概念潜能以及被界化主体的概念识解方式。对其成因进行分析有助于为英汉表量结构的认知和识解提供新的视角,进而更深入地发掘表量构式生动的神韵美。 展开更多
关键词 有界与无界 英汉形状表量结构 灵活性 认知建构成因
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事件驱动多关节机械臂轨迹跟踪自适应鲁棒控制 被引量:10
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作者 钱前 张爱华 孙艺瑕 《兵工学报》 EI CAS CSCD 北大核心 2019年第8期1732-1739,共8页
针对具有不确定干扰和建模误差的多关节机械臂轨迹跟踪控制问题,基于自适应鲁棒控制算法提出事件驱动跟踪控制器。通过自适应鲁棒控制保证多关节机械臂轨迹跟踪精度,处理不确定干扰和建模误差带来的不确定性影响。利用事件驱动控制框架... 针对具有不确定干扰和建模误差的多关节机械臂轨迹跟踪控制问题,基于自适应鲁棒控制算法提出事件驱动跟踪控制器。通过自适应鲁棒控制保证多关节机械臂轨迹跟踪精度,处理不确定干扰和建模误差带来的不确定性影响。利用事件驱动控制框架,以当前跟踪误差和期望状态等变量作为输入定义事件驱动系统的变量。根据Lyapunov稳定性理论获得了驱动条件,且证明了无Zeno现象发生,使系统在满足驱动条件时更新控制指令,从而减少系统能耗与通信频率,提高系统的可靠性,保证多关节机械臂跟踪控制系统半全局最终一致有界。通过仿真验证了理论结果的有效性。 展开更多
关键词 多关节机械臂 轨迹跟踪 事件驱动 鲁棒自适应 半全局最终一致有界
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Improved third-order nonlinear effect in graphene based on bound states in the continuum 被引量:3
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作者 TIECHENG WANG XIANGDONG ZHANG 《Photonics Research》 SCIE EI 2017年第6期148-158,共11页
The scattering matrix theory has been developed to calculate the third-order nonlinear effect in sphere-grapheneslab structures. By designing structural parameters, we have demonstrated that the incident electromagnet... The scattering matrix theory has been developed to calculate the third-order nonlinear effect in sphere-grapheneslab structures. By designing structural parameters, we have demonstrated that the incident electromagnetic wave can be well confined in the graphene in these structures due to the formation of a bound state in the continuum(BIC) of radiation modes. Based on such a bound state, third-harmonic(TH) generation and four-wave mixing(FWM) have been studied. It is found that the efficiency of TH generation in monolayer graphene can be enhanced about 7 orders of magnitude. It is interesting that we can design structure parameters to make all beams(the pump beam, probe beam, and generated FWM signal) be BICs at the same time. In such a case, the efficiency of FWM in monolayer graphene can be enhanced about 9 orders of magnitude. Both the TH and FWM signals are sensitive to the wavelength, and possess high Q factors, which exhibit very good monochromaticity. By taking suitable BICs, the selective generation of TH and FWM signals for S-and P-polarized waves can also be realized,which is beneficial for the design of optical devices. 展开更多
关键词 FWM Improved third-order nonlinear effect in graphene based on bound states in the continuum
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Coexistence of bound soliton and harmonic mode-locking soliton in an ultrafast fiber laser based on MoS2-deposited microfiber photonic device 被引量:2
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作者 Meng Liu Aiping Luo +1 位作者 Wencheng Xu and Zhichao Luo 《Chinese Optics Letters》 SCIE EI CAS CSCD 2018年第2期64-68,共5页
As the typical material of two-dimensional transition metal dichalcogenides(TMDs), few-layered MoS2 possesses broadband saturable absorption and a large nonlinear refractive index, which could be regarded as a promi... As the typical material of two-dimensional transition metal dichalcogenides(TMDs), few-layered MoS2 possesses broadband saturable absorption and a large nonlinear refractive index, which could be regarded as a promising candidate for dual-function photonic device fabrication. In this work, the coexistence of a bound soliton and harmonic mode-locking soliton was demonstrated in an ultrafast fiber laser based on a MoS2-deposited microfiber photonic device. Through a band-pass filter, each multi-soliton state was investigated separately. The bound soliton has periodic spectral modulation of 1.55 nm with a corresponding pulse separation of 5.16 ps.The harmonic mode-locking soliton has the repetition rate of 479 MHz, corresponding to the 65th harmonic of the fundamental repetition rate. The results indicated that there exist more possibilities of different multi-soliton composites, which would enhance our understanding of multi-soliton dynamics. 展开更多
关键词 Coexistence of bound soliton and harmonic mode-locking soliton in an ultrafast fiber laser based on MoS2-deposited microfiber photonic device
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