共查询到20条相似文献，搜索用时 31 毫秒
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通过构建网络型企业概念模型,并设定其属性及知识传播的规则,利用系统仿真方法对网络型企业知识传播的系统动态行为进行了研究。结果表明,网络规模、知识存量离散程度与知识传播效率成反比相关关系,知识传播意愿的离散程度与知识获取效率成阶段性相关关系,即由0~0.35的离散系数范围内,知识传播效率增大,由0.35~1的离散系数范围内,知识传播效率减小;此外,知识传播意愿离散系数为0.35条件下,知识传播意愿提高后,传播效率提高,表明提高知识传播意愿可以促进知识传播效率。依据此结果,可以对网络型企业知识传播效率进行评估,并作为效率改进的理论性依据。 相似文献
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设计了一种接地板上蚀刻新型PBG结构单元的微带线滤波器，利用仿真软件HFSS分析了该滤波器的传输特性，并讨论了随着PBG结构尺寸的变化，其传输特性的变化情况，结果表明此结构作为滤波器的可行性。 相似文献
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Herbert J. Carlin Pier Paolo Civalleri Jeffrey C. Hantgan 《Journal of The Franklin Institute》1981,311(4):209-230
A general procedure is outlined for obtaining single or coupled transmission line models to represent the propagation of surface wave modes in conductively unshielded dielectric waveguides. The procedure uses a homogeneous electrically or magnetically walled waveguide having the same dimensions as the dielectric of the surface waveguide, to produce a set of orthogonal eigenfunctions. These eigenfunctions are projected upon Maxwell's equations resulting in a system of transmission lines coupled together through a wave immittance, which represents the ratio of a longitudinal and a transverse field component at the dielectric-air interface. Examples are given for various modes of the dielectric slab and the dielectric rod, in particular the HE1n modes for the latter. The transmission line models derived for these examples consist of a single trasmission line found directly by projection or reduced from a coupled transmission line model by port elimination, or of two transmission lines coupled together. All circuit models derived preserve the basic properties of surface waves (e.g. no solution below cut-off), and any of the single line models can be solved to give explicit approximate algebraic formulae for the propagation constant as a function of frequency. Numerical results show that the dispersion curves calculated from the models versus exact values are generally excellent over the entire frequency spectrum. 相似文献
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This paper focuses on the filtering problem for nonlinear networked systems with event-triggered data transmission and correlated noises. An event-triggered data transmission mechanism is introduced to reduce excessive measurements transmitted over a bandwidth-constrained network. Considering that process noise and measurement noise are one-step cross-correlated, an UKF-based filtering algorithm which depends on correlation parameter and trigger threshold is presented. Then sufficient conditions are established to ensure stability of the designed filter, where a critical value of the correlation parameter exists. Finally, the effectiveness of the proposed filtering algorithm is demonstrated by comparative simulations. 相似文献
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《Journal of The Franklin Institute》2022,359(11):5458-5487
In this paper, a novel fast attitude adaptive fault-tolerant control (FTC) scheme based on adaptive neural network and command filter is presented for the hypersonic reentry vehicles (HRV) with complex uncertainties which contain parameter uncertainties, un-modeled dynamics, actuator faults, and external disturbances. To improve the performance of closed-loop FTC, command filter and neural network are introduced to reconstruct system nonlinearities that are related to complex uncertainties. Compared with the FTC scheme with only neural network, the FTC scheme with command filter and neural network has fewer controller design parameters so that the computational complexity is decreased and the control efficiency is improved, which is of great significance for HRV. Then, the adaptive backstepping fault-tolerant controller based on command filter and neural network is designed, which can solve the complexity explosion problem in the standard backstepping control and the small uncertainty problem in the backstepping control only containing command filter. Moreover, to improve the approximation accuracy of the neural network-based universal approximator, an adaptive update law of neural network weights is designed by using the convex optimization technique. It is proved that the presented FTC scheme can ensure that the closed-loop control system is stable and the tracking errors are convergent. Finally, simulation results are carried out to verify the superiority and effectiveness of the presented FTC scheme. 相似文献
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[研究目的]网络舆情中信息间的竞争传播更符合社交网络的真实情境,研究舆情事件中多元信息竞争传播的演化机制有助于政府和媒体有效监控舆情、引导舆论。[研究方法]结合舆情事件多信息传播特点,加入信息犹豫者和信息接触率,构建二元信息竞争的SH2IR模型,仿真同步和异步情景下二元信息的竞争演化过程。[研究结论]研究表明,在同步传播模式下,单独增强信息接触率、传播转化率、犹豫转化率以及置换率,都可以扩大信息的传播;在异步传播模式下,信息发布的越早,传播范围越广,但单独增强传播参数对传播效果影响较弱,同时提高信息的传播参数时传播行为明显加强。 相似文献
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This paper introduces a polynomial operator called the DT-polynomial as a novel approach to network flow problems. The class of networks dealt with is time-varying in the sense that the capacity, cost, and travel-time of each edge may vary in discrete time. The Dt-polynomial is a polynomial in two operators, D (delay) and T (time), which is used for describing the time-varying transmission characteristics. The paper starts with the mathematics involving the DT-polynomials. A new shortest arrival route algorithm is presented, and its computational complexity is found to be favorable in comparison with others such as Dijkstra's method and the potential method derived from Ford-Fulkerson's technique. Furthermore, a dynamic flow problem is formulated and analyzed in terms of DT-polynomials, and a latest-departure earliest-arrival schedule is given. Finally, a modified DT-polynomial is applied to digital filter networks. 相似文献
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《Journal of The Franklin Institute》2019,356(14):7731-7753
Since being postulated more than a decade ago, inerters have been successfully employed to enhance the dynamic performance of mechanical systems in several applications. Their ability to lend a high dynamic mass presence to systems that employ them with only a relatively small static device mass makes them unique among mechanical elements. This study explores the mechanical wave manipulation characteristics of nonlinear inertant acoustic metamaterial (NLIAM) configurations using analysis and simulations for their one-dimensional discrete element lattice representations. Firstly, based on notional concepts for nonlinear inertant devices, potential frequency-dependent and acceleration-dependent nonlinear inertant models are identified. Using an effective mass model for the NLIAM with frequency-dependent inertance in the local resonator attachment, the dispersion characteristics of inverse square law and power law inertance models are examined and contrasted with those for an acoustic metamaterial with frequency invariant inertance. While a tuned inverse square law inertance model ensures the existence of a band gap over almost the entire frequency bandwidth of interest even encompassing the extremely low frequency regime, the low and high frequency limits for this inertance law would not be realizable in practice. A potentially more practical power law approximation is proposed and shown to deliver a widening of the band gap by more than 100% towards frequencies below the lower bound of the band gap for the acoustic metamaterial with frequency invariant inertance. Further, drawing inspiration from the Duffing-type stiffness, an acceleration-dependent cubically nonlinear inertance model is proposed. First order corrections to the dispersion characteristics are obtained for an NLIAM with acceleration-dependent inertance using a perturbation approach. For weakly nonlinear cases, excitation amplitude-activated shifts in the dispersion curves are found to enable this NLIAM to act as a passive adaptive filter for mechanical waves based solely on their excitation amplitude. Practical manifestations of such NLIAM could therefore provide a means to realize extraordinary wave manipulation capabilities especially suitable for low frequency structural dynamic applications. 相似文献
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[目的/意义]研究在互联网环境下舆情信息传播路径及传播规律,使社会网络分析法在今后的舆情信息研究中能够更好地被应用,使其理论和方法更加完善,也能对移动环境下舆情传播监管对策具有一定的借鉴意义。[方法/过程]在对研究对象界定的基础上,利用社会网络分析法（Gephi软件）结合新浪微博"大学生理财"的话题所采集的基础数据,对移动网络环境下舆情传播特征、过程、规律进行实证研究,参考研究结论提出具体监管对策。[结果/结论]验证了社会网络分析方法对于移动环境下网络舆情信息传播研究的有效性和实用性,说明了移动环境下网络舆情信息传播的大致特点,并且为今后进行此项研究提供了新的思路,为实践层面监管网络舆情信息传播提供了借鉴模式。 相似文献
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功率放大器是现代通信系统中的关键模块,宽带是目前功率放大器的主要发展趋势。文章介绍了30MHz-512MHz放大器的整体设计方案,根据宽带功率放大器的设计原理,应用宽带传输线变压器和微带线相结合的方法来匹配,采用负反馈网络来提高放大器的稳定性。利用ADS仿真,最终实现全频段80W功率输出。给出了测试结果,满足设计要求。 相似文献
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传送网作为基础性网络,承担着传送各类业务的功能。随着移动通信向着第三代通信模式的发展,建设一个能够支撑3G业务发展的宽频带、多功能、高可靠性的基础性光传送网络显得尤为重要。本文在介绍3G业务主要特征和3G业务对传送网新的要求的基础上,主要阐述了3G传送网可选的组网技术。 相似文献
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[目的/意义]在新技术环境下,图书情报学领域期刊影响力评价与排名的需求正在发生变化。为了完善学科排名体系,文章基于社会网络分析法提出一种新的排名思路--从知识传播角度考虑期刊排名。[方法/过程]文章以近十年的中文社会科学引文索引(CSSCI)数据库中图书馆、情报与文献学(简称LIS)专业的来源期刊为研究对象,应用社会网络分析的研究方法,运用UCINET软件,对这些期刊的知识传播模式进行分析,在知识传播网络中按不同特性对期刊进行排名,并且探究了LIS期刊在知识传播网络中子群的构成。[结果/结论]LIS各个期刊知识传播的出度与入度差距较大,少数的期刊传播领域内大量知识。按照LIS期刊在知识网络中的不同特性排名与按照影响因子排名有差异,在知识传播网络中也可提取出具有相似的出度入度的LIS期刊的子群,以便对LIS期刊影响力进行更好的研究。 相似文献
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通过使用功能等价法，实现了传统文献到网络文献的迁移。从表面上看，该方法是一种类似功能的传递，实质上它是传统文献在网络环境中的嫁接。它既适应了网络文献灵活多变的特征，又满足了传统文献引用价值的平衡，是网络文献引用规范化的一个有益的尝试。 相似文献
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This paper is concerned with the event-based fault detection for the networked systems with communication delay and nonlinear perturbation. We propose an event-triggered scheme, which has some advantages over existing ones. The sensor data is transmitted only when the specified event condition involving the sampled measurements of the plant is violated. An event-based fault detection model is firstly constructed by taking the effect of event-triggered scheme and the network transmission delay into consideration. The main purpose of this paper is to design an event-based fault detection filter such that, for all unknown input, communication delay and nonlinear perturbation, the error between the residual signal and the fault signal is made as small as possible. Sufficient conditions for the existence of the desired fault detection filter are established in terms of linear matrix inequalities. Based on these conditions, the explicit expression is given for the designed fault detection filter parameters. A numerical example is employed to illustrate the advantage of the introduced event-triggered scheme and the effectiveness of the proposed method. 相似文献
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复杂工程项目相较于一般工程项目,常常会面临更为错综复杂的风险演化情景,风险要素之间的传递过程很大程度上导致了复杂工程项目风险管理的困境。本文首先采用文献综述法与头脑风暴法等方法全方位、全阶段识别复杂工程项目中的风险要素;然后运用专家调查法搭建风险要素之间的关联,进而构建复杂工程项目风险要素网络。结合网络可视化分析工具Netminer,重点分析了复杂工程项目风险网络的整体特征参数与局部特征参数,并以此为着眼点剖析了复杂工程项目中的风险传递现象。在此基础上,本文借助厦门市城市地下综合管廊案例来验证该网络模型的有效性。本论文的研究意义在于：识别出了复杂工程项目中的关键起始风险要素与传导风险要素,揭示了复杂网络风险传递的内在规律;并在此基础上提出了有效遏制风险传递的措施,为复杂工程项目的风险传递机理研究提供了理论依据与实践指导。 相似文献
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This paper investigates an H2/H∞ filter designing for networked systems perturbed by multiple noises. The measurement transmission from the sensor to the remote filter is completed via a communication network in simultaneously presenting of data transmission time-varying delays, data packet dropout and data sequence disorder. Since the filter will receive delayed and disordered information, a zero-order-hold (ZOH) or a logical-ZOH (LZOH) is firstly employed for resorting the chaos data sequence. Afterwards, a hybrid H2/H∞ filtering scheme is designed for accurately estimating the target output. By Itô formula and a novel free-weight method, the almost surely mean square exponentially stable (ASMSES) condition of the error system is conveniently obtained and the corresponding filter design method is finally presented. By the proposed method, not only the ASMSES with a pre-scheduled H2/H∞ performance can be achieved, but also the convergence rate of overall system is pre-regulable. In addition, it has been point out the dynamic filtering performance of LZOH scheme should be better than ZOH ones due to less time-varying delays are introduced and more latest measurement information are employed. Numerical examples are provided to demonstrate the effectiveness of the proposed methods. 相似文献
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基于大学生网络舆论引导的“思政类微博”建设研究 总被引：1，自引：0，他引：1
随着越来越多的大学生使用微博,微博改变着大学生网络舆论的传播生态。＂思政类＂微博作为高校思想政治工作在＂微博＂时代下引导大学生网络舆论的主要平台,通过建设＂微博红军＂队伍、构建分层分类引导体系、强化议程设置功能等手段,引导大学生网络舆论朝着高校思想政治工作的预期目标发展。 相似文献