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电动直升机关键性能指标及影响因素研究 被引量:4
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作者 何振亚 唐兴中 《航空科学技术》 2023年第3期16-24,共9页
本文基于电池、电机当前的技术水平和发展趋势,结合直升机性能估算方法,对某轻型直升机进行了全电化改型方案设计与性能计算,分析了改型前后续航能力和悬停升限等关键性能指标的变化,给出了电池能量密度、重量占比、电机功重比等对电动... 本文基于电池、电机当前的技术水平和发展趋势,结合直升机性能估算方法,对某轻型直升机进行了全电化改型方案设计与性能计算,分析了改型前后续航能力和悬停升限等关键性能指标的变化,给出了电池能量密度、重量占比、电机功重比等对电动直升机性能的影响规律,提出了现阶段直升机全电化改型的建议。结果表明,当前电动直升机的续航能力仅能达到油动直升机的8%左右,但其悬停升限明显优于油动直升机,可根据实际任务场景,选择增加电池重量占比、加装辅助升力装置等方式提高电动直升机的续航能力。 展开更多
关键词 电动直升机 电池能量密度 电机功重比 续航能力 悬停升限
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A NOVEL INTRUSION DETECTION MODE BASED ON UNDERSTANDABLE NEURAL NETWORK TREES 被引量:1
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作者 Xu Qinzhen Yang Luxi +1 位作者 Zhao Qiangfu he zhenya 《Journal of Electronics(China)》 2006年第4期574-579,共6页
Several data mining techniques such as Hidden Markov Model (HMM), artificial neural network, statistical techniques and expert systems are used to model network packets in the field of intrusion detection. In this pap... Several data mining techniques such as Hidden Markov Model (HMM), artificial neural network, statistical techniques and expert systems are used to model network packets in the field of intrusion detection. In this paper a novel intrusion detection mode based on understandable Neural Network Tree (NNTree) is pre-sented. NNTree is a modular neural network with the overall structure being a Decision Tree (DT), and each non-terminal node being an Expert Neural Network (ENN). One crucial advantage of using NNTrees is that they keep the non-symbolic model ENN’s capability of learning in changing environments. Another potential advantage of using NNTrees is that they are actually “gray boxes” as they can be interpreted easily if the num-ber of inputs for each ENN is limited. We showed through experiments that the trained NNTree achieved a simple ENN at each non-terminal node as well as a satisfying recognition rate of the network packets dataset. We also compared the performance with that of a three-layer backpropagation neural network. Experimental results indicated that the NNTree based intrusion detection model achieved better performance than the neural network based intrusion detection model. 展开更多
关键词 Intrusion detection Neural Network Tree (NNTree) Expert Neural Network (ENN) Decision Tree (DT) Self-organized feature learning
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载人多旋翼飞行器动力单元选型方法研究
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作者 陈思婧 朱清华 +2 位作者 何振亚 王永杰 刘佳 《航空工程进展》 CSCD 2021年第2期112-121,共10页
载人多旋翼飞行器具有结构尺寸大、载荷需求大、可选用的旋翼大小不等且数目不定的特点,快速确定此类飞行器的动力单元具有较强的工程实用性。以设计一款单人多旋翼飞行器为例,搜集品牌官网推荐的百余组匹配方案数据,采用穷举法计算并... 载人多旋翼飞行器具有结构尺寸大、载荷需求大、可选用的旋翼大小不等且数目不定的特点,快速确定此类飞行器的动力单元具有较强的工程实用性。以设计一款单人多旋翼飞行器为例,搜集品牌官网推荐的百余组匹配方案数据,采用穷举法计算并获得九组性能参数之间的关系;在此基础上,建立旋翼及等效电路模型,针对22款优选电机的最大工作电压,采用优化法计算可匹配的最大旋翼尺寸及需用旋翼个数。结果表明:优化选型所得方案更精准高效,该方法可用于快速获得大质量效率、高续航、低成本的动力单元方案。 展开更多
关键词 载人多旋翼飞行器 动力单元 穷举法 优化法 旋翼模型 等效电路模型
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Detecting deterministic dynamics of cardiac rhythm 被引量:1
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作者 PEI Wenjiang he zhenya +2 位作者 YANG Luxi S.S.Hull J.Y.Cheung 《Chinese Science Bulletin》 SCIE EI CAS 2001年第18期1568-1573,共6页
Under the acceptable hypothesis that cardiac rhythm is an approximately deterministic process with a small scale noise component, an available way is provided to construct a model that can reflect its prominent dynami... Under the acceptable hypothesis that cardiac rhythm is an approximately deterministic process with a small scale noise component, an available way is provided to construct a model that can reflect its prominent dynamics of the deterministic component. When applied to the analysis of 19 heart rate data sets, three main findings are stated. The obtained model can reflect prominent dynamics of the deterministic component of cardiac rhythm; cardiac chaos is stated in a reliable way; dynamical noise plays an important role in the generation of complex cardiac rhythm. 展开更多
关键词 CARDIAC RHYTHM NONLINEAR DYNAMICS BAYESIAN estimation.
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Sublinear Elliptic Equation on Fractal Domains
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作者 he zhenya 《Journal of Partial Differential Equations》 2011年第2期97-113,共17页
This paper investigates sub-linear elliptic equations on self-similar fractal sets. With an appropriately defined Laplacian, we obtain the existence of nontrivial solutions of sub-linear elliptic equations -△u=λu- a... This paper investigates sub-linear elliptic equations on self-similar fractal sets. With an appropriately defined Laplacian, we obtain the existence of nontrivial solutions of sub-linear elliptic equations -△u=λu- a(x)|u|q-1u-f(x,u),with zero boundary Dirichlet conditions. The results are obtained by using Mountain Pass Lemma and Saddle Point Theorem. 展开更多
关键词 Self-similar fractal saddle point theorem elliptic equation mountain pass lemma Laplacian operator.
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