1,282 research outputs found
GraphStream: A Tool for bridging the gap between Complex Systems and Dynamic Graphs
The notion of complex systems is common to many domains, from Biology to
Economy, Computer Science, Physics, etc. Often, these systems are made of sets
of entities moving in an evolving environment. One of their major
characteristics is the emergence of some global properties stemmed from local
interactions between the entities themselves and between the entities and the
environment. The structure of these systems as sets of interacting entities
leads researchers to model them as graphs. However, their understanding
requires most often to consider the dynamics of their evolution. It is indeed
not relevant to study some properties out of any temporal consideration. Thus,
dynamic graphs seem to be a very suitable model for investigating the emergence
and the conservation of some properties. GraphStream is a Java-based library
whose main purpose is to help researchers and developers in their daily tasks
of dynamic problem modeling and of classical graph management tasks: creation,
processing, display, etc. It may also be used, and is indeed already used, for
teaching purpose. GraphStream relies on an event-based engine allowing several
event sources. Events may be included in the core of the application, read from
a file or received from an event handler
An algorithm to evaluate routing conditions in smartphones-based wireless networks
The increasing penetration of smartphones, i.e., smart devices with multiple sensing and communication interfaces, creates the possibility to build novel types of networks. Opportunistic networking and Content- Based networking strongly rely on the use of such devices. Smartphones tend to have an ON/OFF status that strongly depends on the user activity, mobility pattern and energy saving approach. Wireless adaptors are, after the terminal screen, the strongest source of power consumption. It is therefore common for a node to occasionally turn off the networking device to save energy. The impact on routing of the presence of nodes in the off-state must therefore be thoroughly evaluated. We propose an analyticalmodelbasedon evolving graphs,whichprovides an exhaustive evaluationof routing conditions with the aim to determine the best recurring strategy and parameters when dealing with enddevices that show an ON-OFF behavior. Computational results are given, both on static and dynamic scenarios. 2013 Elsevier Ltd. All rights reserved.This work was partially supported by the Ministerio de Ciencia e Innovacion, Spain, under Grant TIN2011-27543-C03-01.Soler Fernández, D.; Albiach Vicent, J.; MartÃnez Molada, E.; Manzoni, P. (2013). An algorithm to evaluate routing conditions in smartphones-based wireless networks. Expert Systems with Applications. 40(13):5033-5048. https://doi.org/10.1016/j.eswa.2013.02.035S50335048401
Next Generation Cloud Computing: New Trends and Research Directions
The landscape of cloud computing has significantly changed over the last
decade. Not only have more providers and service offerings crowded the space,
but also cloud infrastructure that was traditionally limited to single provider
data centers is now evolving. In this paper, we firstly discuss the changing
cloud infrastructure and consider the use of infrastructure from multiple
providers and the benefit of decentralising computing away from data centers.
These trends have resulted in the need for a variety of new computing
architectures that will be offered by future cloud infrastructure. These
architectures are anticipated to impact areas, such as connecting people and
devices, data-intensive computing, the service space and self-learning systems.
Finally, we lay out a roadmap of challenges that will need to be addressed for
realising the potential of next generation cloud systems.Comment: Accepted to Future Generation Computer Systems, 07 September 201
A Survey on the Application of Evolutionary Algorithms for Mobile Multihop Ad Hoc Network Optimization Problems
Evolutionary algorithms are metaheuristic algorithms that provide quasioptimal solutions in a reasonable time. They have been
applied to many optimization problems in a high number of scientific areas. In this survey paper, we focus on the application of
evolutionary algorithms to solve optimization problems related to a type of complex network likemobilemultihop ad hoc networks.
Since its origin, mobile multihop ad hoc network has evolved causing new types of multihop networks to appear such as vehicular
ad hoc networks and delay tolerant networks, leading to the solution of new issues and optimization problems. In this survey, we
review the main work presented for each type of mobile multihop ad hoc network and we also present some innovative ideas and
open challenges to guide further research in this topic
Fast community structure local uncovering by independent vertex-centred process
This paper addresses the task of community detection and proposes a local
approach based on a distributed list building, where each vertex broadcasts
basic information that only depends on its degree and that of its neighbours. A
decentralised external process then unveils the community structure. The
relevance of the proposed method is experimentally shown on both artificial and
real data.Comment: 2015 IEEE/ACM International Conference on Advances in Social Networks
Analysis and Mining, Aug 2015, Paris, France. Proceedings of the 2015
IEEE/ACM International Conference on Advances in Social Networks Analysis and
Minin
Hybrid routing in delay tolerant networks
This work addresses the integration of today\\u27s infrastructure-based networks with infrastructure-less networks. The resulting Hybrid Routing System allows for communication over both network types and can help to overcome cost, communication, and overload problems. Mobility aspect resulting from infrastructure-less networks are analyzed and analytical models developed. For development and deployment of the Hybrid Routing System an overlay-based framework is presented
Effective and Efficient Communication and Collaboration in Participatory Environments
Participatory environments pose significant challenges to deploying real applications. This dissertation investigates exploitation of opportunistic contacts to enable effective and efficient data transfers in challenged participatory environments.
There are three main contributions in this dissertation:
1. A novel scheme for predicting contact volume during an opportunistic contact (PCV);
2. A method for computing paths with combined optimal stability and capacity (COSC) in opportunistic networks; and
3. An algorithm for mobility and orientation estimation in mobile environments (MOEME).
The proposed novel scheme called PCV predicts contact volume in soft real-time. The scheme employs initial position and velocity vectors of nodes along with the data rate profile of the environment. PCV enables efficient and reliable data transfers between opportunistically meeting nodes.
The scheme that exploits capacity and path stability of opportunistic networks is based on PCV for estimating individual link costs on a path. The total path cost is merged with a stability cost to strike a tradeoff for maximizing data transfers in the entire participatory environment. A polynomial time dynamic programming algorithm is proposed to compute paths of optimum cost.
We propose another novel scheme for Real-time Mobility and Orientation Estimation for Mobile Environments (MOEME), as prediction of user movement paves way for efficient data transfers, resource allocation and event scheduling in participatory environments. MOEME employs the concept of temporal distances and uses logistic regression to make real time estimations about user movement. MOEME relies only on opportunistic message exchange and is fully distributed, scalable, and requires neither a central infrastructure nor Global Positioning System.
Indeed, accurate prediction of contact volume, path capacity and stability and user movement can improve performance of deployments. However, existing schemes for such estimations make use of preconceived patterns or contact time distributions that may not be applicable in uncertain environments. Such patterns may not exist, or are difficult to recognize in soft-real time, in open environments such as parks, malls, or streets
Hybrid Routing in Delay Tolerant Networks
This work addresses the integration of today\u27s infrastructure-based networks with infrastructure-less networks. The resulting Hybrid Routing System allows for communication over both network types and can help to overcome cost, communication, and overload problems. Mobility aspect resulting from infrastructure-less networks are analyzed and analytical models developed. For development and deployment of the Hybrid Routing System an overlay-based framework is presented
Towards efficacy and efficiency in sparse delay tolerant networks
The ubiquitous adoption of portable smart devices has enabled a new way of communication via Delay Tolerant Networks (DTNs), whereby messages are routed by the personal devices carried by ever-moving people. Although a DTN is a type of Mobile Ad Hoc Network (MANET), traditional MANET solutions are ill-equipped to accommodate message delivery in DTNs due to the dynamic and unpredictable nature of people\u27s movements and their spatio-temporal sparsity. More so, such DTNs are susceptible to catastrophic congestion and are inherently chaotic and arduous. This manuscript proposes approaches to handle message delivery in notably sparse DTNs. First, the ChitChat system [69] employs the social interests of individuals participating in a DTN to accurately model multi-hop relationships and to make opportunistic routing decisions for interest-annotated messages. Second, the ChitChat system is hybridized [70] to consider both social context and geographic information for learning the social semantics of locations so as to identify worthwhile routing opportunities to destinations and areas of interest. Network density analyses of five real-world datasets is conducted to identify sparse datasets on which to conduct simulations, finding that commonly-used datasets in past DTN research are notably dense and well connected, and suggests two rarely used datasets are appropriate for research into sparse DTNs. Finally, the Catora system is proposed to address congestive-driven degradation of service in DTNs by accomplishing two simultaneous tasks: (i) expedite the delivery of higher quality messages by uniquely ordering messages for transfer and delivery, and (ii) avoid congestion through strategic buffer management and message removal. Through dataset-driven simulations, these systems are found to outperform the state-of-the-art, with ChitChat facilitating delivery in sparse DTNs and Catora unencumbered by congestive conditions --Abstract, page iv
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