Search results for "Network"

Trust-based framework for security enhancement of P2PSIP communication systems

2009

Today, Peer-to-Peer SIP based communication systems have attracted much attention from both academia and industry. The decentralized nature of P2P might provide the distributed peer-to-peer communication system without help of the traditional SIP server. However, it comes to the cost of reduced trustworthiness and may cause security problems, e.g. privacy leaks, unpredictable availability, etc. In this paper, we investigate on P2PSIP security issues and propose a subjective based trust model that offers trust services during P2PSIP session establishment. The main issues considered in this model include opinion calculation, opinion maintenance, data confidentiality and integrity, message rou…

Demo - Dynamic Adaptations of WiFi Channel Widths Without TX/RX Coordination

2017

Most modern standards for wireless communications support physical layer adaptations, in terms of dynamic selection of channel central frequency, transmission power, modulation format, etc., in order to increase link robustness under time-varying propagation and interference conditions. In this demo, we demonstrate that another powerful solution for extending physical layer flexibility in OFDM-based technologies is the dynamic adaptation of the channel width. Although some standards already define the possibility of utilizing multiple channel widths (e.g. 20MHz, 10MHz, 5MHz for IEEE 802.11a standards), such an utilization is limited to a static configuration of a value defined during the ne…

Side Effects of Ambient Noise Immunity Techniques on Outdoor IEEE 802.11 Deployments

2008

A very common conclusion of many experimental studies about IEEE 802.11 outdoor network deployments is that their poor performance results derive from the unfavorable interference and multi-path signals in which the WLAN-cards are required to operate. Goal of this paper is to show that this condition does not always hold, and unexpected and inaccurated PHY layer implementations can be a primary cause of packet losses. With the support of extensive measurement campaigns led in our campus, we provide the performance evidence that IEEE 802.11 outdoor performance impairments are strongly affected by proprietary interference mitigation techniques that adaptively adjust the WLAN-card receiver sen…

Combining similarity measures in content-based image retrieval

2008

The purpose of content based image retrieval (CBIR) systems is to allow users to retrieve pictures from large image repositories. In a CBIR system, an image is usually represented as a set of low level descriptors from which a series of underlying similarity or distance functions are used to conveniently drive the different types of queries. Recent work deals with combination of distances or scores from different and usually independent representations in an attempt to induce high level semantics from the low level descriptors of the images. Choosing the best method to combine these results requires a careful analysis and, in most cases, the use of ad-hoc strategies. Combination based on or…

Restricted Neighborhood Search Clustering Revisited: An Evolutionary Computation Perspective

2013

Protein-protein interaction networks have been broadly studied in the last few years, in order to understand the behavior of proteins inside the cell. Proteins interacting with each other often share common biological functions or they participate in the same biological process. Thus, discovering protein complexes made of groups of proteins strictly related, can be useful to predict protein functions. Clustering techniques have been widely employed to detect significative biological complexes. In this paper, we integrate one of the most popular network clustering techniques, namely the Restricted Neighborhood Search Clustering (RNSC), with evolutionary computation. The two cost functions in…

Accuracy of stereotactic coordinate transformation using a localisation frame and computed tomographic imaging

1999

The accuracy of coordinate transformation from a CT image to a stereotactic frame was investigated for stereotactic systems using a localisation frame and matrix-based coordinate transformation. The main source of error influencing calculation was input data, due to inaccurate calculation of the centres of the rods of the localisation frame in the CT image, and the propagation of this input error during subsequent matrix calculation. Systemic errors during matrix calculation do not exist, and rounding off errors were of subordinate importance compared to the input data error. The influence of input data error on coordinate transformation was studied by geometric methods, computer simulation…

Employing fuzzy logic in the diagnosis of a clinical case

2010

Fuzzy logic is a logical calculus which operates with many truth values (while classical logic works with the two values of true and false). Since fuzzy logic considers the truth of scientific statements like something softened, it is fruitfully applied to the study of biological phenomena, biology is indeed considered the field of complexity, uncertainty and vagueness. In this paper fuzzy logic is successfully applied to the clinical diagnosis of a patient who suffers from different diseases bound by a complex causal chain. In this work it is presented a mathematical foundation of fuzzy logic (with connectives and inference rules) and then the application of fuzzy reasoning to the study of…

TEACHER TEAMS AND SCHOOLS BECOME LEADERS TO DISSEMINATE INNOVATIVE PRACTICE

2016

We will introduce a study about teachers taking part in networking for personal development and becoming teacher leaders. In 2011 a multilevel national joint collaboration network of schools with innovative experience was created to foster dissemination of new teaching and learning experiences among teachers. In order to organize learning for teachers, a lesson based collaborative continuous teacher professional learning model was implemented. The research shows that conducting and analyzing lessons has helped participants become more competent professionals and develop skills that are crucial for a good leader. Categories characterizing teacher leaders and lead schools were identified. Fac…

Genres of participation in social networking systems: A study of the 2009 Norwegian parliamentary election

2010

Published version of a chapter in the book: Electronic Participation. Also available at http://dx.doi.org/10.1007/978-3-642-15158-3_9 In the Norwegian context, eParticipation in the form of online campaigning has been on the agenda since 2001. After Obama’s successful presidential campaign in 2008, expectations about the use of SNS in the Norwegian parliamentary election were high. This study explores genres of participation in the early stages of the 2009 Norwegian parliamentary election campaign. The main finding is that the political parties have seen the need for a presence in SNS’, and that a genre repertoire for political communication through SNS is beginning to evolve. However, ther…

Two-Step Flow of Communication

2008