Output reachable set estimation for discrete-time switched systems with persistent dwell-time

This paper is concerned with the output reachable set estimation for discrete-time switched systems. The switching signal is considered as persistent dwell-time (PDT), which is more general and flexible compared with the common dwell-time and average dwell-time switching. The estimation of output reachable set is determined by a collection of bounding ellipsoids based on a family of quasi-time-dependent (QTD) Lyapunov functions. Furthermore, a set of non-fragile QTD controllers is designed. Finally, two examples are employed to illustrate the potentials of proposed methods.     

风险投资声誉、智力资本与企业价值

风险资本与智力资本的有效协同能够实现创业企业知识、资本、管理与创新的完美结合,而拥有高声誉背景的风投在利用其经验和广泛的社会关系帮助企业快速成长方面作用更加突出。本文将创业企业的智力资本划分为人力资本、结构资本、创新资本与社会资本四个组成部分,基于风险投资声誉的视角,探讨风险资本与智力资本的协同关系。结果显示：高声誉风险投资在创业企业人力资本和结构资本两方面的协同效应并不显著,而与创新资本和社会资本两方面的协同效应突出,尤其与社会资本的协同效应能够显著提升创业企业的内在价值。该结论表明高声誉的风险投资机构亟需对目标企业的人力资源、战略规划等方面积极关注,并提供更多的增值服务。     

社交网络中网络口碑与购买意愿的动力学机制分析

网络口碑对消费者的购买意愿有重要的影响。采用系统的观点来研究社交网络中网络口碑与消费者购买意愿的动力学机制。从社会资本的角度出发,采用系统动力学,建立社会资本——网络口碑——购买意愿的动力学模型。模型的仿真结果表明,社会资本在社会化电子商务平台中,能够很好地提升网络口碑的传播效果,进而影响消费者的购买意愿。     

联合分析方法在个人信息隐私研究中的机会分析

[目的/意义]为更全面地了解联合分析方法在个人信息隐私研究中的应用以及发现潜在的研究机会,为信息隐私保护的深入研究提供参考和借鉴,有必要对采用联合分析方法研究个人信息隐私的文献进行回顾总结。[方法/过程]研究个人信息隐私且采用联合分析方法的20篇文献被选出来,重点对这些文献的研究主题、采用的研究理论以及协同使用的其他研究方法进行了总结和分析。[结果/结论]结果发现：第一,现有相关研究主要集中在数据共享意愿和产品采纳两个方面;第二,这些文献很少采用用户隐私披露意向和行为研究中的相关理论来指导属性的选择和结果的解释;第三,联合分析与焦点小组访谈、聚类分析、问卷调查等方法相结合可以提供更多的理论和实践启示。     

Increased foot-stretcher height improves rowing performance: evidence from biomechanical perspectives on water

Abstract

The aim of this study was to investigate whether changes on foot-stretcher height were associated with characteristics of better rowing performance. Ten male rowers performed a 200 m rowing trial at their racing rate at each of three foot-stretcher heights. A single scull was equipped with an accelerometer to collect boat acceleration, an impeller with embedded magnets to collect boat speed, specially designed gate sensors to collect gate force and angle, and a compact string potentiometer to collect leg drive length. All sensor signals were sampled at 50 Hz. A one-way repeated measures ANOVA showed that raising foot-stretcher position had a significant reduction on total gate angle and leg drive length. However, a raised foot-stretcher position had a deeper negative peak of boat acceleration at the catch, a lower boat fluctuation, a faster leg drive speed, a larger gate force for the port and starboard side separately. This could be attributed to the optimisation of the magnitude and direction of the foot force with a raised foot-stretcher position. Although there was a significant negative influence of a raised foot-stretcher position on two kinematic variables, biomechanical evidence suggested that a raised foot-stretcher position could contribute to the improvement of rowing performance.     

基于创新扩散理论的学术论文影响力广度研究

[目的/意义]采用被引次数衡量学术论文影响力存在诸多弊端。本文认为学术论文影响力包括其传播的深度、速度和广度3个方面，熵可用于衡量学术论文影响力传播的广度。[方法/过程]选择1901-2017年生物医学领域的诺贝尔奖论文作为最具影响力的论文纳入实验组，并根据1：1配对原则设立对照组，比较两组论文发表后5年内其施引文献所属学科数量、熵以及熵与被引次数的相关性。[结果/结论]实验组中65%以上的论文施引文献学科数量高于对照组；实验组熵的均值介于0.552-0.772，对照组介于0.251-0.481，有显著性差异（P<0.05）；两组论文的被引次数与熵的相关性较弱，均小于0.3。结果表明：①70%以上的高影响力论文在发表早期能够影响较多的学科；②采用熵对论文影响力广度进行识别具有可行性。     

公众参与视域下公共档案馆微信平台互动研究

公众参与是衡量现代民主政治发展的重要指标,公共机构与社会公众双方良性互动显得至关重要。从档案微信公众平台建设上看,存在公众参与地域不均、公众参与程度不高、档案部门回应力度不够、微信公号吸引性不足的问题。提出应加强档案宣传教育,转变档案部门服务意识,提高公号内容质量和拓宽互动形式等建议,以期提高双方互动效率,实现档案服务质量和档案价值的提升。     

High-resolution mapping of brain vasculature and its impairment in the hippocampus of Alzheimer's disease mice

Accumulating evidence indicates the critical importance of cerebrovascular dysfunction in the pathogenesis of Alzheimer''s disease (AD). However, systematic comparative studies on the precise brain vasculature of wild-type and AD model mice are still rare. Using an image-optimization method for analysing Micro-Optical Sectioning Tomography (MOST) data, we generated cross-scale whole-brain 3D atlases that cover the entire vascular system from large vessels down to smallest capillaries at submicron resolution, for both wild-type mice and a transgenic (APP/PS1) mouse model of AD. In addition to distinct vascular patterns in different brain regions, we found that the main vessels of the molecular layer of the hippocampal dentate gyrus (DG-ml) undergo abrupt changes in both diameter and branch angle, spreading a unique comb-like pattern of capillaries. By using a quantitative analysis workflow, we identified in the hippocampus of AD mice an overall reduction of the mean vascular diameter, volume fraction and branch angle, with most significant impairment in the DG-ml. In addition, virtual endoscopy revealed irregular morphological features in the vessel lumen of the AD mice, potentially contributing to the impairment of blood flow. Our results demonstrate the capability of high-resolution cross-scale evaluation of brain vasculature and underscore the importance of studying hippocampal microcirculation for understanding AD pathogenesis.     

英语新闻标题中的隐喻及其传播功能

本文以China Daily（《中国日报》）为例,分析英语新闻标题制作中的隐喻现象,重点揭示了英语新闻标题中使用隐喻的特点及其功能。     

虚拟现实:关于未来媒体的一种猜想

本文参照虚拟现实的含义和特征,提出了它在大众传播中的作用,并指出,只要虚拟现实逐步成熟完善起来并得到充分应用而承担了新一代媒体重任的时候,它已经在全部意义上实现了媒体发展的终极目标。