There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Imagined communities: Reflections on the origin and spread of nationalism

The modern science of networks has brought significant advances to our understanding of complex systems. One of the most relevant features of graphs representing real systems is community structure, or clustering, i. e. the organization of vertices in clusters, with many edges joining vertices of the same cluster and comparatively few edges joining vertices of different clusters. Such clusters, or communities, can be considered as fairly independent compartments of a graph, playing a similar role like, e. g., the tissues or the organs in the human body. Detecting communities is of great importance in sociology, biology and computer science, disciplines where systems are often represented as graphs. This problem is very hard and not yet satisfactorily solved, despite the huge effort of a large interdisciplinary community of scientists working on it over the past few years. We will attempt a thorough exposition of the topic, from the definition of the main elements of the problem, to the presentation of most methods developed, with a special focus on techniques designed by statistical physicists, from the discussion of crucial issues like the significance of clustering and how methods should be tested and compared against each other, to the description of applications to real networks.

/pdf/community-detection-in-graphs-34rogm3r6p.pdf

Community detection in graphs

We study the problem of building low-cost city-wide location tracking systems with the intention to provide a platform for large-scale human mobility data collection. We take the city-bikes as our first target, motivated by several social networking applications, and choose Cambridge in the UK as our pilot case. We highlight the main application requirements, discuss the practical design issues, and propose a system architecture based on a hybrid sensor network.

/pdf/sentient-bikes-for-collecting-mobility-traces-in-4o6j0c5kg4.pdf

Sentient bikes for collecting mobility traces in opportunistic networks

This demonstration presents a novel software defined platform for achieving collaborative and energy-aware WiFi offloading. The platform consists of an extensible central controller, programmable offloading agents, and offloading extensions on mobile devices. Driven by our extensive measurements of energy consumption on smartphones, we propose an effective energy-aware offloading algorithm and integrate it to our platform. By enabling collaboration between wireless networks and mobile users, our solution can make optimal offloading decisions that improve offloading efficiency for network operators and achieve energy saving for mobile users. To enhance deployability, we have released our platform under open-source licenses on GitHub.

Demo: An Open-source Software Defined Platform for Collaborative and Energy-aware WiFi Offloading

The World Wide Web WWW is a global information system which is set to revolutionize the world of information search, retrieval and browsing via the Internet 

The World Wide Web

The Future Internet will provide seamless connectivity via heterogeneous networks. The Y-Comm Architecture is a reference model that has been developed to build future mobile systems for heterogeneous environments. However, the emergence of Software Defined Networking and Network Functional Virtualization will allow the implementation of advanced mobile architectures such as Y-Comm to be prototyped and explored in more detail. This paper proposes an implementation model for the Y-Comm architecture based on these mechanisms. A key component is the design of the Core Endpoint which connects various peripheral wireless networks to the core network. This paper also proposes the development of a Network Management Control Protocol which allows the management routines running in the Cloud to control the underlying networking infrastructure. The system being proposed is flexible and modular and will allow current and future wireless technologies to be seamlessly integrated into the overall system.

/pdf/developing-an-implementation-framework-for-the-future-3upn8ekj26.pdf

Developing an implementation framework for the Future Internet using the Y-Comm architecture, SDN and NFV

In recent years, much work has been done on attempting to scale multicast data transmission to hundreds or thousands of receivers. There are, however, many situations where an application might involve transmission to just ten or twenty sites. Today's grid environments, for example, see high energy physicists carry out multi-gigabyte bulk data transfers to a handful of destinations. In this project, we are investigating how TCP-XM, a modified version of TCP that supports multicast, can be integrated with Globus to to provide grid users with a reliable multicast transport protocol. Our approach has been to use Globus XIO - an extensible input/output library for Globus that provides a POSIX-like API to swappable I/O implementations. We have wrapped TCP-XM in XIO to extend Globus to support multicast transmission. This paper describes the implementation and operation of our Globus XIO multicast driver, reviews the TCP-XM protocol design, and provides some experimental results.

/pdf/a-multicast-transport-driver-for-globus-xio-2gsvinw1ik.pdf

Jon Crowcroft

Papers

Sentient bikes for collecting mobility traces in opportunistic networks

Demo: An Open-source Software Defined Platform for Collaborative and Energy-aware WiFi Offloading

The World Wide Web

Developing an implementation framework for the Future Internet using the Y-Comm architecture, SDN and NFV

A multicast transport driver for Globus XIO