电子出版物和电子图书馆的发展

本文以大量实例叙述了九十年代以来, 在世界范围内出现的各种电子读物和电子图书馆。论文首先以单媒体电子读物、多媒体电子读物及电子图书馆三个不同的类别分别论述它们各自的特点, 而后引入网络和信息高速公路, 并以清华大学图书馆的多媒体阅览室、光盘联网联机检索数据库、Internet 检索及图书馆网络化建设为实例, 具体论述电子出版物在中国图书情报领域的应用。     

What do they know?: An assessment of undergraduate library skills

This article, which examines variables affecting scores on a test of library skills, finds that the frequency with which students receive assignments requiring library research is the best predictor of a score. The unevenness is students' research skills has implications for bibliographic instruction.     

基于三螺旋理论的女子竞技足球运动共建模式研究

分析新时期女子竞技足球运动发展现状和需要导向,基于三螺旋理论提出了高校、女子竞技足球运动俱乐部和政府的共建模式,阐释了模式内容、三螺旋互动与角色定位,为女子竞技足球运动建设发展提供了新的理论视角借鉴.     

Rapid and cost-effective fabrication of selectively permeable calcium-alginate microfluidic device using ��modified�� embedded template method

In this paper, we have presented a non-lithographic embedded template method for rapid and cost-effective fabrication of a selectively permeable calcium-alginate (Ca-alginate) based microfluidic device with long serpentine delay channel. To demonstrate the versatility of the presented method, we have demonstrated two different strategies to fabricate serpentine long delay channels without using any sophisticated microfabrication techniques, in formal lab atmosphere. The procedure presented here, also, enables the preparation of a multilayered microfluidic device with channels of varying dimensions, in a single device without using any sophisticated micromachining instrumentation. In addition, we have also qualitatively studied the diffusion of small and large molecules from a Ca-alginate based microfluidic device and proposed a method to effectively control the out-flow of macro biomolecules from the crosslinked Ca-alginate matrix to create a selectively permeable matrix required for various biological and biomimetic applications, as mentioned in the Introduction section of this work.     

Gravity-oriented microfluidic device for uniform and massive cell spheroid formation

We propose a simple method for forming massive and uniform three-dimensional (3-D) cell spheroids in a multi-level structured microfluidic device by gravitational force. The concept of orienting the device vertically has allowed spheroid formation, long-term perfusion, and retrieval of the cultured spheroids by user-friendly standard pipetting. We have successfully formed, perfused, and retrieved uniform, size-controllable, well-conditioned spheroids of human embryonic kidney 293 cells (HEK 293) in the gravity-oriented microfluidic device. We expect the proposed method will be a useful tool to study in-vitro 3-D cell models for the proliferation, differentiation, and metabolism of embryoid bodies or tumours.     

Adaptive controller design for spacecraft formation flying using sliding mode controller and neural networks

A spacecraft formation flying controller is designed using a sliding mode control scheme with the adaptive gain and neural networks. Six-degree-of-freedom spacecraft nonlinear dynamic model is considered, and a leader–follower approach is adopted for efficient spacecraft formation flying. Uncertainties and external disturbances have effects on controlling the relative position and attitude of the spacecrafts in the formation. The main benefit of the sliding mode control is the robust stability of the closed-loop system. To improve the performance of the sliding mode control, an adaptive controller based on neural networks is used to compensate for the effects of the modeling error, external disturbance, and nonlinearities. The stability analysis of the closed-loop system is performed using the Lyapunov stability theorem. A spacecraft model with 12 thrusts as actuators is considered for controlling the relative position and attitude of the follower spacecraft. Numerical simulation results are presented to show the effectiveness of the proposed controller.     

A new approach to average consensus problems with multiple time-delays and jointly-connected topologies

This paper investigates average consensus problem in networks of continuous-time agents with delayed information and jointly-connected topologies. A lemma is derived by extending the Barbalat's Lemma to piecewise continuous functions, which provides a new analysis approach for switched systems. Then based on this lemma, a sufficient condition in terms of linear matrix inequalities (LMIs) is given for average consensus of the system by employing a Lyapunov approach, where the communication structures vary over time and the corresponding graphs may not be connected. Finally, simulation results are provided to demonstrate the effectiveness of our theoretical results.