上海交通大学数字图书馆雏型   总被引：14，自引：2，他引：14  

杨宗英  叶爱芬  王榕榕  郑巧英 《现代图书情报技术》1998,14(5):3-6

简要介绍上海交通大学数字图书馆雏型产生背景和概念模型, 它包括五个模块: 各种载体数字化, 大容量数据储存和管理, 数据访问, 数字化资料传递, 权限管理和版权保护; 上海交通大学数字图书馆雏型的体系结构包括网络拓扑结构、主干网的缚线系统和硬软件环境等; SJTUDL 的实用服务模式由数字化图书馆的特种馆藏, 商用网上联机电子出版物和Internet 文献信息资源三部分组成, 将用一个统一的界面向读者提供服务。  相似文献   

一流学科建设视角下的情报实证研究与服务策略探析     

杨眉  潘卫  董珏  陈天天 《图书情报工作》2022,66(5):72-79

[目的/意义]提出高校图书馆情报实证研究与服务策略,推动服务的普及和拓展,为高校图书馆开展类似服务提供服务范式与方法路径参考.[方法/过程]主要运用实证研究法、归纳法、文献调研法等多种方法开展研究.以学科建设进程中的"队伍建设""创新引领"和"绩效提升"三大应用场景为核心,提出与之相适应的三大服务模块:助力一流师资队伍...  相似文献   

Hybrid event-based asynchronous finite-time control for cyber-physical switched systems under denial-of-service attacks     

《Journal of The Franklin Institute》2023,360(2):1036-1057

This paper investigates the event-based asynchronous finite-time control for a class of cyber-physical switched systems under Denial-of-Service (DoS) attacks. Considering the attack’s characteristics, we put forward a novel attack-instant-constrained hybrid event-triggered scheme (HETS), which can not only contribute to reducing the network transmission overload, but also well descibe the network denial service behavior under attack interference. An asynchronous and ZOH-based controller is delicately constructed to mitigate the influence of DoS attacks and network-induced delay. A double-mode dependent Lyapunov–Krasovskii functional (LKF) is developed to set up some sufficient finite-time stability criteria for the concerned systems in view of the asynchronous switching effect. Finally, an application example of the urban railway system is offered to verify the proposed control algorithm.  相似文献   

Distributed state estimator-based consensus tracking of multi-agent systems with exogenous disturbance     

《Journal of The Franklin Institute》2023,360(12):9139-9158

The consensus tacking problem for multi-agent systems with a leader of none control input and unknown control input is studied in this paper. By virtue of the relative state information of neighboring agents, state estimator and disturbance estimator are designed for each follower to estimate the system states and exogenous disturbance, respectively. Meanwhile, a novel control protocol based on two estimators is designed to make tracking error eventually converge to zero. Furthermore, the obtained results are further extended to the leader with unknown control input. A novel state estimator with adaptive time-varying gain is proposed such that consensus tracking condition is independent of the Laplacian matrix with regard to the communication topology. Finally, two examples are presented to verify the feasibility of the proposed control protocol.  相似文献   

Distributed filtering algorithm based on local outlier factor under data integrity attacks     

《Journal of The Franklin Institute》2023,360(12):9290-9306

Network security is becoming a prominent issue for the development of information technology, and intelligent network attacks pose great challenges to system security due to its strong concealment. The existence of these attacks threatens the operation process of the complicated control system. Motivated by such a security problem, we study the secure distributed filtering algorithm under a kind of complex data integrity attack which can attack in two forms. We design a detection mechanism based on local outlier factor to distinguish the rightness of exchanged data, which determines whether to fuse the estimates by comparing the local density (LD) of the estimation of each sensor. Such a detection mechanism does not need the sensor to transmit redundant data information, thus greatly saving calculation cost and improving transmission efficiency. Meanwhile, we optimize the distributed filtering algorithm and obtain a suboptimal estimation gain. Finally, we demonstrate a numerical example to verify the availability of the filtering algorithm, and explore the influence of detector parameters on the performance of the estimation system.  相似文献   

False data injection attacks on sensors against state estimation in cyber-physical systems     

《Journal of The Franklin Institute》2023,360(9):6110-6130

In this paper, the problem about the false data injection attacks on sensors to degrade the state estimation performance in cyber-physical systems(CPSs) is investigated. The attack strategies for unstable systems and stable ones are both designed. For unstable systems, based on the idea of zero dynamics, an unbounded attack strategy is proposed which can drive the state estimation error variations to infinity. The proposed method is more general than existing unbounded attack strategies since it relaxes the requirement for the initial value of the estimation error. For stable systems, it is difficult to bring unbounded impacts on the estimation error variations. Therefore, in this case, an attack strategy with adjustable attack performance which makes the estimation error variations track predesigned target values is proposed. Furthermore, a uniform attack strategy which aims to deteriorate state estimation for both stable systems and unstable ones is derived. Finally, simulations are provided to illustrate the effectiveness of the proposed attack strategies.  相似文献   

Disturbance observer-based neural adaptive stochastic control for a class of kinetic kill vehicle subject to unmeasured states and full state constraints     

《Journal of The Franklin Institute》2023,360(13):9515-9536

This paper proposes a disturbance observer-based neural adaptive stochastic control approach for the attitude control system of a class of Kinetic Kill Vehicles (KKVs) with unmeasured states and full state constraints. First, a one-one mapping is applied to transform the attitude control system with state constraints into a nonlinear novel system without any constraint. As a result, the control objective is changed into the boundness of the novel system states. Furthermore, the disturbances existing in the system are effectively estimated and eliminated by the nonlinear disturbance observer as well as the radial basis function neural networks (RBFNNs). Moreover, due to the dynamic signal, the dynamic uncertainty induced by the unmeasured states with an unknown dynamic is compensated appropriately. Utilizing the stochastic Lyapunov process, the boundness of all the signals in the system can be proven and the state constraints are satisfied. Finally, two groups of simulations are conducted, which demonstrate the remarkable performance of the proposed algorithm under different working conditions and highlight the advantages compared with existing studies.  相似文献   

Fixed-time convergence integral-enhanced ZNN for calculating complex-valued flow matrix Drazin inverse     

《Journal of The Franklin Institute》2023,360(13):9707-9727

The complex-valued flow matrix Drazin inverse has recently attracted considerable interest from researchers due to its great academic value. In this paper, a fixed-time convergence integral-enhanced zeroing neural network (FTCIEZNN) model is proposed and investigated for calculating the Drazin inverse of complex-valued flow matrix. Since the FTCIEZNN model possesses fixed-time convergence, its upper limit of convergence time is irrelevant to initial conditions and can be adjusted by specified system parameters. Meanwhile, by adopting the newly designed reformed nonlinear activation function (RNAF) and variable parameters, the FTCIEZNN model converges rapidly in a relatively fast fixed-time and its robustness is dramatically strengthened. In addition, the upper limit of the convergence time in the absence of noise and the upper limit of the steady-state error in the presence of time-varying bounded noise are given by a scrupulous mathematical logic calculation. Furthermore, the outcomes of the numerical simulations demonstrate that the FTCIEZNN model outshines existing zeroing neural network models in calculating complex-valued flow matrix Drazin inverse. Finally, an application based on the FTCIEZNN model in image encryption fully illustrates the practical value of the FCIEZNN model.  相似文献   

A yaw stability-guaranteed hierarchical coordination control strategy for four-wheel drive electric vehicles using an unscented Kalman filter     

《Journal of The Franklin Institute》2023,360(13):9663-9688

A novel hierarchical coordination control strategy (HCCS) is offered to guarantee the stability of four-wheel drive electric vehicles (4WD-EVs) combining the Unscented Kalman filter (UKF). First, a dynamics model of the 4WD-EVs is established, and the UKF-based estimator of sideslip angle and yaw rate is constructed concurrently. Second, the equivalent cornering stiffness coefficients are jointly estimated to consider the impact of vehicle uncertainty parameters on the estimator design. Afterwards, a HCCS with two-level controller is presented. The sideslip angle and yaw rate are controlled by an adaptive backstepping-based yaw moment controller, and the computational burden is relieved by an improved adaptive neural dynamic surface control technology in the upper-level controller. Simultaneously, the optimal torque distribution controller of hub motors is developed to optimize the adhesion utilization ratio of tire in the lower-level controller. Finally, the proposed HCCS has shown effective improvement in the trajectory tracking capability and yaw stability of the 4WD-EVs under various maneuver conditions compared with the traditional Luenberger observer-based and the federal-cubature Kalman filter-based hierarchical controller.  相似文献   

Financial and knowledge barriers to innovation: Complementary and substitution effects on innovative effort     

《Research Policy》2023,52(7):104814

Innovation studies have thoroughly analysed how firms' perception of barriers affects their innovative behaviour. We contribute to this line of research by analysing complementary and substitution effects between financial barriers, internal knowledge barriers and external knowledge barriers on firms' innovative effort. Using a panel data set of Uruguayan firms between 2006 and 2015, we add to empirical studies on this topic by estimating both unconditional and conditional complementary and substitution effects between these innovation barriers. We apply an econometric two-step specification that includes an estimation of instrumental variables, which allows us to control for endogeneity biases in the supermodularity and submodularity tests. We find significant evidence that external and internal knowledge barriers reinforce each other's effects (complementary effects), conditional on the absence of financial barriers. We also find that financial and internal knowledge barriers mitigate each other's effects (substitution effects) conditional on the firm's perception of external knowledge barriers. Additionally, we find substitution effects between financial and external knowledge barriers, conditional on the firm's perception of internal knowledge barriers. We discuss these results against the backdrop of Uruguayan innovation policies during the period studied, and stress the necessary articulation between instruments that will help strengthen firms' innovation management to recognize and manage innovation barriers.  相似文献