共查询到19条相似文献，搜索用时 109 毫秒
1.
强迫Duffing—Van der Pol振子的混沌行为 总被引：1，自引：0，他引：1
用Melnikov-Holmes方法对如下强迫Duffing-Van der Pol振子进行了分析:给出其同宿轨道的Melnikov函数及系统产生混沌的阈值.通过数值计算,运用运动轨线的直接观察,相图分析和FFT功率谱分析方法,考察系统的周期和混沌行为.并着重研究了反馈周期驱动对系统混沌行为的影响.在小参数范围内,数值结果与理论结果符合较好.本文的研究结果将为解决非线性系统的噪声干扰问题以及获得在统计分析和Monte Carlo方法中极为有用的具有给定分布的随机信号等提供途径. 相似文献
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锅炉承压部件的爆漏是大型火电机组强迫停用的主要原因，占锅炉机组强迫停用次数的82%，强迫停用时间的78%。因而预防锅炉承压部件损坏，有其明显的经济效益。 相似文献
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图书馆集成化系统的发展，受多种因素制约，本身决定图书馆自动化管理系统存在一个应用周期。本文从技术、应用、功能等角度分析了各种因素对图书馆集成化管理系统的生存周期的影响。 相似文献
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本文设计了一种适用于直流升压斩波电路的晶闸管强迫关断电路,详细介绍了电路的工作原理,并给出了主要的参数设计。实验结果表明此方案可行,具有较好的实际应用价值。在综合考虑了大功率直流升压斩波器可靠性、系统成本等因素的基础上,提出了一种基于晶闸管的大功率直流升压斩波电路。晶闸管的强迫关断一般只在直流Buck电路或普通开关电路中得到应用。 相似文献
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本文借助MALABGUI实现了<信号与系统>课程中信号频谱分析系统,该系统可实现连续周期、连续非周期、离散周期、离散非周期等四类常见信号的频谱分析,通过键盘或鼠标能够很方便的修改信号时域的参数,并能实时的显示频域的对应变化趋势;通过具体实例对系绫各模块进行了说明.将该系统和教学实验结合,取得了良好的效果. 相似文献
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《中国科学院研究生院学报》2001,(2)
第 1期运行中的ＧＳＭ移动通信系统无线调优的探讨张敏洪 杨德庄 ( 1)……………………………………………………………………………具有强迫项的广义Ｌｏｔａｋａ Ｖｏｌｔｅｒｒａ竞争系统的正周期解 (英文 )李 林 ( 6 )……………………………………………………………………非对易场论中的孤子解和严格解 (英文 )朱传界 ( 12 )……………………………………………………………………………………………纳米ＴｉＯ2 对染料敏化纳米薄膜太阳电池的影响王瑞斌 戴松元 王孔嘉 ( 2 8)……………………………………………………………轴对… 相似文献
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史远军 《中国科学院研究生院学报》1997,(1)
在二阶系统一系列定理基础上,建立一个直接根据系统Lyapunov函数性质判定系统周期解存在性的定理,针对一类二阶非自治非线性系统构造了适当的Lyapunov函数,并研究了这类系统周期解的存在性。 相似文献
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电视节目后期制作的飞跃--多媒体非线性编辑系统的应用 总被引：4，自引：0，他引：4
从电视节目制作的设备和制作成本，制作周期，制作内容，制作质量等方面进行对比分析，阐述多媒体非线性编辑系统的应用是电视节目后期制作的极大飞跃。 相似文献
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Barry S. Thornton 《Journal of The Franklin Institute》1975,300(5-6)
A new method is presented for determining the stability and vibration modes of a class of parametric oscillations where the damping terms in the Mathieu-Hill type of differential equations are complex as well as periodic. The imaginary terms are converted to phase lagged terms in a set of simultaneous first-order differential equations used to express these equations with first-order derivatives treated as additional variables, thereby doubling the number of equations but allowing matrix methods to be conveniently used in a bifurcation procedure to obtain solutions and stability boundaries. The method has advantages over methods using series expansions in determining stability boundaries and vibration modes where convergence and summability become important considerations in the case of differential-difference equations with periodic damping terms. A particular example of a fluttering helicopter blade in slow forward flight is studied and stability boundaries shown to be displaced by up to 10% from those when the nature and extent of the rows of wakes below the rotor are neglected. The range of the parameters governing the stability are given for a specific numerical example. Application to an actual blade motion study shows reconciliation with previous experimental results and theory when the new method is applied. The importance of the effect of lagged arguments in simultaneous differential-difference equations is discussed with reference to two other examples in structural vibrations. 相似文献
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Robert G. Crawford 《Information processing & management》1977,13(4):235-245
A method for updating the dictionary in a dynamic information retrieval system is presented. It is shown that as a collection changes through addition and deletion of documents, the appropriate set of index terms may be determined without complete periodic regeneration of the dictionary. Results are presented for experiments involving a complete change in collection membership, with the dynamic dictionary updating methods shown to be effective. 相似文献
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This paper is concerned with the stability analysis of discrete-time linear systems with time-varying delays. The novelty of this paper lies in that a novel Lyapunov–Krasovskii functional that updates periodically along with the time is proposed to reduce the conservatism and eventually be able to achieve the non-conservativeness in stability analysis. It can be proved that the stability of a discrete-time linear delay system is equivalent to the existence of a periodic Lyapunov–Krasovskii functional. Two necessary and sufficient stability conditions in terms of linear matrix inequalities are proposed in this paper. Furthermore, the novel periodic Lyapunov–Krasovskii functional is employed to solve the ?2-gain performance analysis problem when exogenous disturbance is considered. The effectiveness of the proposed results is illustrated by several numerical examples. 相似文献
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Chaouki Aouiti Imen Ben Gharbia Jinde Cao Ahmed Alsaedi 《Journal of The Franklin Institute》2019,356(4):2294-2324
In this letter, the existence and the global exponential stability of piecewise pseudo almost periodic solutions (PAPT) for bidirectional associative memory neural networks (BAMNNs) with time-varying delay in leakage (or forgetting) terms and impulsive are investigated by applying contraction mapping fixed point theorem, the exponential dichotomy of linear differential equations and differential inequality techniques. Furthermore, we give an explanatory example to illustrate the efficiency of the theoretical predictions. 相似文献
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在国际金融危机环境下,中小企业贷款困难尤其突出,有很多企业因为资金链的断裂而被迫破产。同时,从银行方面针对中小企业信用评级方面来看,在方法、效率和成本方面又是按照国有大型企业同样的方法和标准来做,这些方法和标准对于中小企业并不很合适。在考察了我国中小企业目前面临较为困难的融资情况之后,开发出了一套智能化的、信息化的,专门针对中小企业的信用评价系统,Smart Credit Evaluation System for SMEs（SCEC）。 相似文献
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《Journal of The Franklin Institute》2022,359(18):10849-10866
This paper considers neural network solutions of a category of matrix equation called periodic Sylvester matrix equation (PSME), which appear in the process of periodic system analysis and design. A linear gradient-based neural network (GNN) model aimed at solving the PSME is constructed, whose state is able to converge to the unknown matrix of the equation. In order to obtain a better convergence effect, the linear GNN model is extended to a nonlinear form through the intervention of appropriate activation functions, and its convergence is proved through theoretical derivation. Furthermore, the different convergence effects presented by the model with various activation functions are also explored and analyzed, for instance, the global exponential convergence and the global finite time convergence can be realized. Finally, the numerical examples are used to confirm the validity of the proposed GNN model for solving the PSME considered in this paper as well as the superiority in terms of the convergence effect presented by the model with different activation functions. 相似文献
17.
The inputs to mathematical models of library operations require periodic updating. The data collection effort necessary for such updating can be quite expensive. However, if the data collected can serve multiple purposes, the costs can perhaps be justified. A management information system offers a vehicle for multiple uses of data and thus, offers an appropriate environment for implementation of models of library operations. Within this paper, the design of a model-based management information system is discussed in terms of mathematical /statistical, information processing, and human factors issues. A prototype system for interlibrary loan networks is discussed. 相似文献
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基于非期望产出的不同职能城市土地利用效率分异及驱动因素探究 总被引：1，自引：0，他引：1
研究非期望产出条件下不同职能城市土地利用效率分异特征及其驱动因素,对于城市可持续发展具有重要意义。本文采用DEA中改进的EBM模型,测度了2004—2015年中国五大类268个城市的土地利用效率,并运用灰色关联模型探究了其主要驱动因素。结果发现：①忽视城市土地利用过程中的生态负效应,会引起对土地利用效率的高估,而考虑非期望产出,能更加真实地测算出土地利用效率;各职能城市的土地利用效率均存在较大差异,说明按城市职能类型来测度土地利用效率的科学性。②在不考虑非期望产出条件下,各职能城市的土地利用效率值曲线相对陡峭且周期性变化较多,而在考虑非期望产出条件下,效率值曲线变化相对平缓且周期性变化较少。③综合型城市主要受产业结构、土地市场化程度和环境治理能力的影响,资源型城市主要受产业结构、对外依赖程度和政府规制的影响,工业型城市主要受产业结构、土地市场化程度和地区能源结构的影响,文娱型城市主要受城镇化水平、经济发展水平和环境治理能力的影响,地方型城市主要受经济发展水平、城镇化水平和政府规制的影响。鉴于此,在提升城市土地利用效率时,应充分考虑土地的非期望产出和城市的异质性,制定出差异化的土地管理政策。 相似文献
19.
Relationships between risetime, settling time, bandwidth and Q are presented for the class of TEM-mode delay line filters whose impulsive response is a train of uniformly spaced, but unequally weighted impulses. Conventional measures of bandwidth for these systems are undefined because the energy spectrum is a periodic function of frequency. It is shown, however, that with careful interpretation one may derive a useful inverse relationship between bandwidth and risetime via a suitably modified autocorrelation function; the relationship is a risetime-bandwidth product equaling a constant derived by an equivalent area measure. It is also shown that a useful estimate of the settling time of a system can be obtained in terms of the moments of the impulse response which weight heavily the contributions of the remote time domain residues. Examples are presented to demonstrate the application of the theory. 相似文献