Search results for " network"
showing 10 items of 6428 documents
Relay selection in FDD amplify-and-forward cooperative networks
2017
In this paper, the problems of relay selection and distributed beamforming are investigated for bi-directional dual-hop amplify-and-forward frequency-division duplex cooperative wireless networks. When using individual per-relay maximum transmission power constraint, it has been proven that the relay selection and beamforming optimization problem becomes NP hard and requires exhaustive search to find the optimal solution. Therefore, we propose a computationally affordable sub-optimal multiple relay selection and beamforming optimization scheme based on the l1 norm squared relaxation. The proposed scheme performs the selection for the two transmission directions, simultaneously, while aiming…
Enable concurrent transmissions with beamforming for broadband wireless access in CSMA/CA-based WLANs
2014
In CSMA/CA based wireless local networks, two stations are not allowed to transmit at the same time due to interference generated to each other, resulting in degraded throughput. Concurrent transmission, which enables simultaneous transmission of two or more stations under certain conditions, is able to overcome this problem, leading to enhanced channel utilization efficiency. Different from earlier work on this topic which focuses on omni-direction concurrent transmission, we introduce in this paper beamforming into a co-channel concurrent transmission scheme and investigate the benefits of concurrency with beamforming. The circumstances for concurrent transmission and frame scheduling are…
Stochastic Collaborative Beamforming in Wireless Sensor Networks
2018
Wireless Sensor Networks (WSNs) are composed of spatially distributed autonomous sensor devices, named motes. These devices are constituted by a microcontroller, sensors, and they have the ability to communicate in the ISM frequency band using the IEEE 802.15.4 standard. They have their own power supply, AA or AAA batteries, processing unit, sensors and wireless communications. Usually, the motes exchange packets using a multihop routing, and the maximum communication distance emitter-receiver is around 100m. At least one mote acts as a gateway, and the data gathered by the sensors of each mote have to be sent to this mote that is named sink or Base Station (BS). In a WSN the BS is within t…
The use of steel angles for the connection of laminated glass beams: Experiments and modelling
2012
Abstract In the present paper the experimental results relative to three-point bending tests on multilayer glass beams and on semi-rigid connections realised with stainless double web angles are presented and discussed. Small and medium size glass beams were tested and load–deflection curves and crack patterns at failure were recorded. The laminated glass specimens, of equal cross-section, were characterised by three different combinations of annealed float and fully thermally tempered glass plies and different interlayers. Steel joints constituted by double web angles to connect two glass beams were tested adopting several geometrical configurations and using stainless steel bolts preloade…
Predicting mobile apps spread: An epidemiological random network modeling approach
2017
[EN] The mobile applications business is a really big market, growing constantly. In app marketing, a key issue is to predict future app installations. The influence of the peers seems to be very relevant when downloading apps. Therefore, the study of the evolution of mobile apps spread may be approached using a proper network model that considers the influence of peers. Influence of peers and other social contagions have been successfully described using models of epidemiological type. Hence, in this paper we propose an epidemiological random network model with realistic parameters to predict the evolution of downloads of apps. With this model, we are able to predict the behavior of an app…
Social network and addiction.
2009
In recent decades, the rapid development of innovative Internet-based communication technologies created a new field of academic study among scholars. Particularly, the attention of researchers is focusing on new ways to form relationship-thought social web. Social Network sites constitute a new form of web communities, where people meet and share interests and activities. Due to exponential growth of these sites, an increasing number of scholars are beginning to study the emergent phenomena in order to identify any psychopathological risk related to use of social web, such as addiction. This article examines the recent literature about this issue. In recent decades, the rapid development o…
Entrepreneurship on Social Networking Sites: The Roles of Attitude and Perceived Usefulness
2023
Background: Social media platforms are a significant growth opportunity for enterprises, especially for microenterprises, due to the possibility of establishing direct contact with their customers. We investigate the psychological reasons that drive entrepreneurs towards the use of social networking sites (SNSs) for their business, following two important social psychology theories: the theory of planned behaviour and the technology acceptance model. We also tested for two personality traits: openness to experience and dominance. Methods: Data were acquired by examining 325 microentrepreneurs who decided to use either SNSs or traditional sales methods for their businesses. Results and concl…
An approach for influence estimatation in complex networks : application to the social network Twitter
2019
Influence in complex networks and in particular Twitter has become recently a hot research topic. Detecting most influential users leads to reach a large-scale information diffusion area at low cost, something very useful in marketing or political campaigns. In this thesis, we propose a new approach that considers the several relations between users in order to assess influence in complex networks such as Twitter. We model Twitter as a multiplex heterogeneous network where users, tweets and objects are represented by nodes, and links model the different relations between them (e.g., retweets, mentions, and replies).The multiplex PageRank is applied to data from two datasets in the political…
Social capital development of rural community based on social networking activities in Lithuania
2018
The scholar literature on simultaneous using of social capital explore knowledge and identity resources as well as actions and interactions benefiting the community through personal bonds of individuals; issues of common trust; and adapting the current understanding in new situations. In this article, we instead examine rural community influence on social capital building of adult person in a virtual community. A quantitative survey was done in 246 local rural communities in Lithuania which reflected their community activities on a virtual basis. From the data of 500 informants we found that rural community (human social network) members were also active in the virtual communities. Research…
Un análisis bibliométrico en el área de la Medicina: colaboración científica entre Brasil y España (2002-2011)
2016
[EN]: This study analyzes the development of Spanish-Brazilian collaborative scientific production in the field of medical research between 2002 and 2011, identifying the most productive institutions, the proportion of researchers from each country and bi-lateral collaborative networks. Data were gathered from the Scopus database, which offers broad, international coverage of multidisciplinary research. A study sample of 1,121 original scientific articles signed by 13,906 researchers were retrieved, on the basis of which the annual growth rate of Spanish-Brazilian medical research was calculated. A remarkably high degree of internationalization was found, with 121 countries participating in…