Search results for "Computer network"
showing 10 items of 1634 documents
An OFDM Receiver Exploiting Multipath Diversity
2008
We propose a novel receiver structure, to be employed with standard Orthogonal Frequency Division Multiplexing transmitters, capable of exploiting the multipath diversity of wireless channels. The proposed technique is based on cancellation of inter-block interference arising in the guard interval and linear detection techniques. It features a low implementation complexity and is easily generalized to MIMO systems and non-linear detection techniques.
Impact of incentives on tourist activity in space-time
2020
Abstract No tourism study to date, has examined the ability of incentives to shape the spatio-temporal behaviour of tourists. Data collected from the port of Palermo in Sicily (Italy), using traditional survey instruments as well as GPS technology, was employed to investigate the effect of incentives on cruise passengers' space-time activities. The results show the incentives' clear and significant impact in influencing the space-time activities of cruise passengers' while visiting the city. Understanding the movement patterns of visitors at destinations can give destination managers information that can assist in dealing with the negative effects of overtourism that are caused due to high …
DiDuSoNet: A P2P architecture for Ditributed Dunbar-based Social Networks,
2015
Online Social Networks (OSNs) are becoming more and more popular on the Web. Distributed Online Social Networks (DOSNs) are OSNs which do not exploit a central server for storing users data and enable users to have more control on their profile content, ensuring a higher level of privacy. In a DOSN there are some technical challenges to face. One of the most important challenges is the data availability problem when a user is offline. In this paper we propose DiDuSoNet, a novel P2P Distributed Online Social Network where users can exercise full access control on their data. Our system exploits trust relationships for providing a set of important social services, such as trustness, informati…
Trusted dynamic storage for dunbar-based P2P online social networks
2014
Online Social Networks (OSNs) are becoming more and more popular in today's Internet. Distributed Online Social Networks (DOSNs), are OSNs which do not exploit a central server for storing users' data and enable users to have more control on their profile content, ensuring a higher level of privacy. The main challenge of DOSNs comes from guaranteeing availability of the data when the data owner is offline. In this paper we propose a new P2P dynamic approach to the problem of data persistence in DOSNs. By following Dunbar's approach, our system stores the data of a user only on a restricted number of friends which have regular contacts with him/her. Users in this set are chosen by considerin…
Epidemic diffusion of social updates in Dunbar-based DOSN
2014
Distributed Online Social Networks (DOSNs) do not rely on a central repository for storing social data so that the users can keep control of their private data and do not depend on the social network provider. The ego network, i.e. the network made up of an individual, the ego, along with all the social ties she has with other people, the alters, may be exploited to define distributed social overlays and dissemination protocols. In this paper we propose a new epidemic protocol able to spread social updates in Dunbar-based DOSN overlays where the links between nodes are defined by considering the social interactions between users. Our approach is based on the notion of Weighted Ego Betweenne…
Investigating the impact of virtual tourism on travel intention during the post-COVID-19 era: evidence from China
2022
This study explores the mechanism that contributes to travel intention in the field of virtual tourism. The overall research method is based on the "Stimulus-Organism-Response" theory. In the research model, the effects of content quality, system quality, and interaction quality in virtual tourism on tourism experience and travel intention are explored, as well as the role of virtual attachment and travel intention. A total of 390 respondents were invited to participate in a virtual tourism experience, and provide feedback through a questionnaire. SmartPLS 3.3.2 was used to validate the causal model, and most of the study hypotheses were supported. The findings show that virtual tourism sig…
Decentralized Lightweight Group Key Management for Dynamic Access Control in IoT Environments
2020
Rapid growth of Internet of Things (IoT) devices dealing with sensitive data has led to the emergence of new access control technologies in order to maintain this data safe from unauthorized use. In particular, a dynamic IoT environment, characterized by a high signaling overhead caused by subscribers' mobility, presents a significant concern to ensure secure data distribution to legitimate subscribers. Hence, for such dynamic environments, group key management (GKM) represents the fundamental mechanism for managing the dissemination of keys for access control and secure data distribution. However, existing access control schemes based on GKM and dedicated to IoT are mainly based on ce…
Optimized Parallel Implementation of Face Detection based on GPU component
2015
Display Omitted An algorithm for face detection has been implemented on CPU.An acceleration of this algorithm on GPU migration.Performance of GPU implementation shows the effectiveness of this implementation.Another optimization method on GPU are operated. Face detection is an important aspect for various domains such as: biometrics, video surveillance and human computer interaction. Generally a generic face processing system includes a face detection, or recognition step, as well as tracking and rendering phase. In this paper, we develop a real-time and robust face detection implementation based on GPU component. Face detection is performed by adapting the Viola and Jones algorithm. We hav…
A distributed genetic algorithm for restoration of vertical line scratches
2008
This paper reports a distributed algorithm for the restoration of still frames corrupted by vertical line scratches. The restoration is here approached as an optimisation problem, and is solved using an ad-hoc Genetic Algorithm. The distributed algorithm is designed following a pipeline logical structure. The front end is a network of standard workstations with heterogeneous operating systems. The quality of image is appreciable and the computational time is quite low with respect the sequential version.
The complexity of graph languages generated by hyperedge replacement
1990
Although in many ways, hyperedge replacement graph grammars (HRGs) are, among all graph generating mechanisms, what context-free Chomsky grammars are in the realm of string rewriting, their parsing problem is known to be, in general, NP-complete. In this paper, the main difficulty in HRG parsing is analysed and some conditions on either grammar or input graphs are developed under which parsing can be done in polynomial time. For some of the cases, the parsing problem is shown to be log-space reducible to context-free string parsing.