共查询到20条相似文献，搜索用时 31 毫秒
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Sajad Ahmadian Majid Meghdadi Mohsen Afsharchi 《Information processing & management》2018,54(4):707-725
Recommender systems are techniques to make personalized recommendations of items to users. In e-commerce sites and online sharing communities, providing high quality recommendations is an important issue which can help the users to make effective decisions to select a set of items. Collaborative filtering is an important type of the recommender systems that produces user specific recommendations of the items based on the patterns of ratings or usage (e.g. purchases). However, the quality of predicted ratings and neighbor selection for the users are important problems in the recommender systems. Selecting suitable neighbors set for the users leads to improve the accuracy of ratings prediction in recommendation process. In this paper, a novel social recommendation method is proposed which is based on an adaptive neighbor selection mechanism. In the proposed method first of all, initial neighbors set of the users is calculated using clustering algorithm. In this step, the combination of historical ratings and social information between the users are used to form initial neighbors set for the users. Then, these neighbor sets are used to predict initial ratings of the unseen items. Moreover, the quality of the initial predicted ratings is evaluated using a reliability measure which is based on the historical ratings and social information between the users. Then, a confidence model is proposed to remove useless users from the initial neighbors of the users and form a new adapted neighbors set for the users. Finally, new ratings of the unseen items are predicted using the new adapted neighbors set of the users and the interested items are recommended to the active user. Experimental results on three real-world datasets show that the proposed method significantly outperforms several state-of-the-art recommendation methods. 相似文献
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This paper deals with chained form systems with strongly nonlinear disturbances and drift terms. The objective is to design robust nonlinear output feedback laws such that the closed-loop systems are globally exponentially stable. The systematic strategy combines the input-state-scaling technique with the so-called backstepping procedure. A dynamic output feedback controller for general case of uncertain chained system is developed with a filter of observer gain. Furthermore, two special cases are considered which do not use the observer gain filter. In particular, a switching control strategy is employed to get around the smooth stabilization issue (difficulty) associated with nonholonomic systems when the initial state of system is known. 相似文献
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对于非严格重复线性时变连续系统,初始迭代条件和参考轨迹在一定带宽范围内都是迭代变化的.提出一种非严格的迭代学习方法来控制跟踪整流.通过该方法所获得的控制器,能保证闭环系统的所有信号是全局有界的,能够使超出初始时间间隔的输出跟踪误差收敛到一个小的残差集内,该残差集大小取决于输入矩阵的估测误差.尤其是当输入矩阵已知的情况下,能够让超出的初始时间间隔输出跟踪误差趋近于零. 相似文献
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遗留系统演化是企业信息化建设中无法回避的重要环节,采取何种演化策略,取决于科学的系统综合评价。指标体系的构建是遗留系统综合评价的基础。本文从业务价值、系统质量和企业基础设施三个评价视点构建了遗留系统的综合评价指标体系。 相似文献
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Alberto Paucar-Caceres Gillian Wright 《International Journal of Information Management》2011,31(6):593-598
We propose a framework to reflect on the development of four information systems (IS) paradigms, arguing that this field has followed a similar path to that of Management Sciences (MS). The framework comprises four IS paradigms/discourses: (1) positivist/normative; (2) soft/interpretive; (3) critical/pluralistic; and (4) constructivist/2nd order cybernetics. The paper characterizes these approaches to IS by using four key terms: System; Organisation; Management and Information, exploring the way these concepts are perceived through the lens of the four paradigms. The paper reports on the nature of current IS trends, from an initial survey of six top IS journals identifying articles adhering to the interpretive, critical and constructivist paradigms published between 1999 and 2009. Results indicate that IS is moving towards research practice in which interpretive, critical and constructivist discourses are utilised. Implications of the proposed framework and publication trends, together with some points for further research, are offered. 相似文献
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研究了开放量子系统的状态转移问题.利用刘维尔超算符将其矩阵动力学模型转换为向量形式.给定一个耗散的量子系统的动力学模型,在一个随时变化的外部控制场中,以系统状态和目标状态的密度矩阵的误差平方作为性能指标,推导出改进的状态转移最优控制律.在数值仿真实验中,我们研究了一个热浴中的自旋1/2粒子系统在单个外部控制场作用下的动力学特性.在所提出的最优控制作用下,分别选择本征态、纯态和混合态作为系统的初始状态和目标状态.对此系统中状态转移的实验结果进行了性能对比分析. 相似文献
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从现实世界到MAS世界--基于MAS理论的复杂系统建模思想探讨 总被引：6，自引：0，他引：6
首先对Agent及MAS的本质特性进行分析,指出Agent在本质上是具有一定理性的意识系统,MAS则是一种基于涌现的分布式问题求解模式。其次,重点讨论了MAS与复杂系统的关系,指出MAS与其在本质上的相关性。最后,通过揭示MAS建模思想所反映出的世界观,将MAS建模的意义扩展到自然系统、社会系统、生态系统等广泛的现实世界,从而得出,在对各类复杂系统进行分析的过程中,从现实世界映射到MAS世界是直观、合理、可行的。 相似文献
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This paper is concerned with the problem of observer design for a class of discrete-time Lipschitz nonlinear state delayed systems with, or without parameter uncertainty. The nonlinearities are assumed to appear in both the state and measured output equations. For both the cases with and without norm-bounded time-varying parameter uncertainties, a design method is proposed, which involves solving a linear matrix inequality (LMI). When a certain LMI is satisfied, the explicit expression of a desired nonlinear observer is also presented. An example is provided to demonstrate the applicability of the proposed approach. 相似文献
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Aaron D. Schutte 《Journal of The Franklin Institute》2010,347(1):208-227
This paper develops a unified approach for modeling and controlling mechanical systems that are constrained with general holonomic and nonholonomic constraints. The approach conceptually distinguishes and separates constraints that are imposed on the mechanical system for developing its physical structure between constraints that may be used for control purposes. This gives way to a general class of nonlinear control systems for constrained mechanical systems in which the control inputs are viewed as the permissible control forces. In light of this view, a new and simple technique for designing nonlinear state feedback controllers for constrained mechanical systems is presented. The general applicability of the approach is demonstrated by considering the nonlinear control of an underactuated system. 相似文献
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A problem of stabilization about uncertain networked control systems (NCSs) with random but bounded delays is discussed in this paper. By using augmented state-space method, this class of problems can be modeled as discrete-time jump linear systems governed by finite-state Markov chains. A new switched model based on probability is proposed to research problems of reliable control when actuators become ageing or partially disabled. Using improved V-K iteration algorithm, a class of reliable controllers are designed to make systems asymptotically mean square stable under several stochastic disturbances such as random time-delay and stochastic actuator failure and the maximal redundancy degree is given through this method. 相似文献
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系统思考及其在知识管理中应用分析 总被引：1，自引：0，他引：1
知识管理需要有效方法的支撑以更好地在组织中实施。本文首先对系统理论和方法的新发展-系统思考的提出背景、系统思考的内涵及其主要内容进行概括研究,结合知识管理中知识的整体性视角和知识管理本身发展需要,从理论借鉴、分析框架和方法运用三个方面提出系统思考为组织进行有效的知识管理提供了可操作性的方法支持。指出基于系统思考(系统方法论)的知识管理研究为未来整合研究的方向之一。 相似文献
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Giuseppe Grassi Author Vitae 《Journal of The Franklin Institute》2010,347(2):438-451
Projective synchronization is a type of chaos synchronization where the response system states are scaled replicas of the drive system states. This paper deals with the propagation of projective synchronization in a series connection of N chaotic discrete-time drive systems and N response systems. By exploiting an observer-based approach, the paper demonstrates that dead-beat projective synchronization (i.e., exact synchronization in finite time for any scaling factor) is achieved between the nth drive and nth response systems. In particular, it is shown that projective synchronization starts from the innermost (Nth) drive-response system pair and propagates toward the outermost (first) drive-response system pair. Only a single scalar synchronizing signal connects the cascaded drive and response systems. Finally, an example illustrates the propagation of different types of chaos synchronization in a series connection consisting of a Gingerbreadman map, a third order hyperchaotic Henon map and a Lozi map. 相似文献
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基于组织背景的管理控制系统设计:一个理论框架 总被引：6，自引：0，他引：6
管理控制系统作为确保资源有效利用以实现组织目标的一种组织系统，随着现代企业组织背景不确定性和复杂性程度的提高，其重要性日益凸现．本文以管理控制的权变理论为研究切入点，首先总结和分析了组织背景关键变量(外部环境、技术、结构、规模、战略和文化)对管理控制系统设计的影响作用，在此基础上，根据组织背景与管理控制系统之间的关系，提出以组织背景、管理控制系统模式和管理控制系统结果为维度，构建管理控制系统设计的理论框架。这一理论框架对于我国现代企业内部管理控制系统的建立具有重要的启示意义。 相似文献
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Since accurate decisions are required for effective management, much research has focused on information systems that support decision making. Recently, this research has engendered frameworks, such as the management support system (MSS), that are designed to provide comprehensive and integrated support for the decision making process. Few, if any, studies have empirically measured the effects of these frameworks on decision making. This article offers empirical evidence on MSS effectiveness. It overviews the decision making process, presents an MSS for supporting the process, and assesses the influences of the MSS on the process and outcomes of health care decision making. The paper also examines the implications of the analyses for information systems research and health care practice. 相似文献
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This paper proposes a time domain approach to deal with the regional eigenvalue-clustering robustness analysis problem of linear uncertain multivariable output feedback proportional-integral-derivative (PID) control systems. The robust regional eigenvalue-clustering analysis problem of linear uncertain multivariable output feedback PID control systems is converted to the regional eigenvalue-clustering robustness analysis problem of linear uncertain singular systems with static output feedback controller. Based on some essential properties of matrix measures, a new sufficient condition is proposed for ensuring that the closed-loop singular system with both structured and mixed quadratically-coupled parameter uncertainties is regular and impulse-free, and has all its finite eigenvalues retained inside the same specified region as the nominal closed-loop singular system does. Two numerical examples are given to illustrate the application of the presented sufficient condition. 相似文献
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In this paper we consider a problem of controllability of discrete time linear system with randomly jumping parameters which can be described by finite state Markov chain. Necessary and sufficient conditions for existence of control which governs the system from any initial conditions to zero, from zero initial condition to any final value and from any initial condition to any final value in given time and with probability one are given. The relations between such kinds of controllability and stochastic stabilizability are discussed. 相似文献
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评论式系统思考 (CST)以及全面系统干预 (TSI)是系统方法论的新进展。本文在介绍其主要思想的基础上 ,将CST和TSI引入战略方法论的研究 ,为战略研究方法论的综合集成与创新开辟了一条新的思路。 相似文献