We study a corpus of 100 years of newspaper articles to see if we can nd evidence to support the popular intuition that as news cycles have sped up the public's attention span has gotten shorter. We nd no such evidence: to the contrary, we find that the typical length of time that a person's name stays in the news has not changed over time, and celebrities now stay in the news for longer than ever before. We also investigate a new kind of community on Twitter called a group chat, where members have regular meetings to discuss a broad range of topics, from medical conditions to hobbies. We find that the phenomenon is growing over time, and paint a broad picture of the topics which one could find a group chat to discuss. With a view to helping connect new participants to group chats they may not have been able to nd or might not have been aware of, we design an algorithm to rank group chats in the context of a topic given as a query.

关键词：电报;Twitter

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关键词：信息披露;信息不对称

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We present a cost-efficient and reproducible technique for assembling 3D components to mechanically bendable low glass transition temperature (Tg) polymeric interposers. First, we propose localized soldering using a focused hot air gun. Second, we use eutectic solders, which permit reflow at temperatures close to the Tg of the interposer. Then, we adopt differential heating and cooling in order to enable rapid heat dissipation through the interposer during soldering. Furthermore, we apply a metal jig as a load to maintain contact between the interposer and the 3D component during soldering. Also, the jig serves as a shield to protect the interposer surface outside the soldering zone from thermal loading, and more importantly as a passive heat sink. We showcase our approach by manufacturing a test vehicle on a polyethylene terephthalate (PET) interposer having a Tg of 71 deg. C. We solder a 30 mA DC current SMD LED by means of a eutectic compound of 48 w. % Sn and 52 w. % In at 118 deg. C.

关键词：共晶焊接；低Tg聚合物

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Rich client-side applications written in HTML5 proliferate diverse platforms such as mobile devices, commodity PCs, and the web platform. These client-side HTML5 applications are increasingly accessing sensitive data, including users' personal and social data, sensor data, and capability-bearing tokens. Instead of the classic client/server model of web applications, modern HTML5 applications are complex client-side applications that may call some web services, and run with ambient privileges to access sensitive data or sensors. The goal of this work is to enable the creation of higher-assurance HTML5 applications. We propose two major directions: rst, we present the use of formal methods to analyze web protocols for errors. Second, we use existing primitives to enable practical privilege separation for HTML5 applications. We also propose a new primitive for complete mediation of HTML5 applications. Our proposed designs considerably ease analysis and improve auditability.

关键词：HTML5；应用程序；移动设备；网络协议

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The research developed in this grant lead to a significant body of interrelated results that are relevant for the design and analysis of performance of networked control systems. These results may have an impact on the design and provable performance certification of networks of semi- autonomous systems that are required to execute safety critical missions with high precision in the presence of communication constraints.

关键词：通信和广播系统；可替换主体系统；控制系统；性能分析

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Software bugs are inevitable in software-defined networking control software, and troubleshooting is a tedious, time-consuming task. In this thesis we discuss how to improve control software troubleshooting by presenting a technique for automatically identifying a minimal sequence of inputs responsible for triggering a given bug, without making assumptions about the language or instrumentation of the software under test. We apply our technique to five open source SDN control platforms—Floodlight, NOX, POX, Pyretic, ONOS—and illustrate how the minimal causal sequences our system found aided the troubleshooting process.

关键词：SDN控制软件；因果序列；软件缺陷；网络控制软件

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The American transportation landscape is changing. Americans, especially young people, are driving less for the first time in recorded history, and this trend is expected to continue in the foreseeable future (Davis and Baxandall 2013). This shift has been accompanied by a corresponding increase in popularity of alternative transportation models such as carsharing and ridesharing (Shaheen 2013). Presently, these models only focus on dense urban areas, and current research (Martin and Shaheen 2011) suggests that carsharing and ridesharing programs work best when paired with existing public transportation infrastructure. However, large suburban master planned communities (MPCs) are also increasing in popularity in the United States (Spivak 2012), and the majority of these communities have limited transit options (Mercedes-Benz R&D North America). We explored opportunities for new transportation solutions in these large communities by evaluating existing solutions, interviewing potential users, and analyzing interview and survey data from residents in a specific community. We found that there is an unmet need for a shared transportation solution in a large MPC and designed and implemented a mobile application to demonstrate such a solution. Our application has comparable performance, functionality, and ease of use to other transportation applications and, once implemented, will help residents save time, money, and the environment.

关键词：汽车;Web应用程序;流动性解决方案

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In this work, we conduct a numerical investigation of the structural feasibility of a flexible, monolithic and planar optoelectronic system based on low Tg polymers using ANSYS?. In particular, we explore the effectiveness of two eutectic compounds 52w.%In 48w.%Sn and 58w.%Bi 42w.%Sn to solder light sources and sinks to multimode light waveguides. First, we analyze the warpage of the optical structures due to eutectic soldering. Furthermore, we study the spectrum of mechanical stresses within the eutectic layer. Then, we investigate the possibility of roll-to-roll mass production. Finally, we establish design guidelines for decreasing the system warpage, and consequently preserving optical alignment, while complying with the ultimate shear strength of the eutectic material.

关键词：共晶焊接；低Tg聚合物；多模光波导

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Two guided wave SHM approaches were developed in this project. The first approach is based on a guided wave tomographic technique, in which the region surrounded by a sparse sensor array is monitored. The second one is a phased array approach, in which sensors are attached to a structure in a compact format to form an array. The region subjected to inspection and monitoring is the region outside the array. Both techniques have shown an excellent capability of determining damage size, location, and severity. The importance of guided wave mode and frequency control has been demonstrated for both the tomography and the phased array approach. Guided wave annular arrays have been successfully developed as a means of mode and frequency control. Phased annular array transducers with excellent flexibility on guided wave mode tuning have also been investigated. Guided wave tomography with improved robustness to environmental conditions was demonstrated via the application of specially designed annular arrays. Damage detection using phased array beamforming was also achieved. Unique beamformer transducers were developed and applied to both isotropic and anisotropic multilayer composite structures.

关键词：通信检测；组合结构；结构健康监测；波束形成；相控阵

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关键词：数据库系统；数据存储；磁盘；内存

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