324,123 research outputs found
Energy/Latency Trade-offs in Geographic Routing for Ultrawideband Wireless Sensor Networks
No full textWireless Sensor Networks (WSNs) may exploit accurate localization capabilities of ultrawideband (UWB) transceivers to improve performance of high layer protocols. We analyze power consumption of a WSN accommodating both communication and positioning into the same UWB transceiver and implementing a geographic routing algorithm, either the Greedy Perimeter Stateless Routing (GPSR) or its energy aware version, the e-GPSR. Power consumption depends on beacon rate for positions' updates, the number of hops to reach the destination and the number of neighbors per node. On the other hand, the beacon rate impacts the reliability of the neighbor lists; the number of hops impacts on the end-to-end latency; the number of neighbors, i.e. the network connectivity, impacts on routing performance. The presented analysis assesses, by means of both theoretical investigations and simulation results, the main trade-offs between power consumption and latency that can be applied to obtain the best achievable performance
A Framework for High-Level Event Detection in a Social Network Context Via an Extension of ISEQL
No full textWe develop a framework for the detection of high-level events in a social network context, allowing us to identify abnormal or malicious behavior such as spamming. Additionally, we can classify users by analyzing their typical behavior while logged into a social network site. The processing of (real-time) events in our framework is done via an event detection language called ISEQL, which we adapt and extend to fit the requirements of a social network setting. We evaluate our framework experimentally, showing its effectiveness and efficiency
An event detection framework supported by a smart graphical user interface
No full textWe develop a graphical user interface for defining events in a framework for detecting high-level surveillance events from a video stream, as the language used for the events may be too complex for an ordinary user. The language is based on relational algebra extended by intervals, introducing operators whose temporal constraints are described using the well-known Allen's interval relationships. The user interface captures intervals in a descriptive way, supporting the user in providing the missing parameters in a step-bystep manner. In the background, the system checks the user input for consistency and automatically transforms it into relational algebra expressions
High-Level Automatic Event Detection and User Classification in a Social Network Context
No full textWe present a framework for high-level automatic event detection and user classification in a social network context based on a novel temporal extension of relational algebra, which improves and extends our earlier work in the video surveillance context. By means of intuitive and interactive graphical user interfaces, a user is able to gain insights into the inner workings of the system as well as create new event models and user categories on the fly and track their processing through the system in both offline and online modes. Compared to an earlier version, we extended our relational algebra framework with operators suited for processing data from a social network context. As a proof-of-concept we have predefined events and user categories, such as spamming and fake users, on both a synthetic and a real data set containing data related to the interactions of users with Facebook over a 2-year period
Routing Design for UWB Sensor Networks in Industrial and Logistics Scenarios
No full textUWB technology enables accurate positioning. The integration of communication and location-tracking capabilities will strongly enhance performance and enlarge the application field of UWB systems. Location-based routing protocols may be more efficient and robust than other routing strategies. In this
paper we propose an enhanced “energy-aware” version of a well established location-based reactive multi-hop protocol, namely the Greedy Perimeter Stateless Routing (GPSR) algorithm. The performance of this novel routing scheme is investigated by means of extensive dynamic system simulations. The design parameters
of the e-GPSR are optimized for industrial and logistics scenarios
High-Level Surveillance Event Detection Using an Interval-Based Query Language
No full textWe propose a language based on relational algebra extended by intervals for detecting high-level surveillance events from a video stream. The operators we introduce for describing temporal constraints are based on the well-known Allen's interval relationships. The semantics of our language are clearly defined and we illustrate its usefulness by expressing typical events in it and showing the promising results of an experimental evaluation
An interval-based query language for high-level surveillance event detection
No full textWe propose a language based on relational algebra extended by intervals for detecting high-level surveillance events from a video stream. The operators we introduce for describing temporal constraints are based on the well-known Allen's interval relationships. The semantics of our language are clearly defined and we illustrate its usefulness by expressing typical events in it and showing the promising results of an experimental evaluation
Orientalist representations of Persia in the works of Spenser, Marlowe, Milton, Moore and Morier
No full textThis study aims at investigating the representations of Persia in a number of canonical and non-canonical texts in English literature. The theoretical framework comes from Edward Said’s analysis of orientalism. It is argued that the case of Persia instances the heterogeneous and striated character of orientalism (‘representations’ rather than ‘representation’ in the title). It is shown that while a number of relatively similar set of motifs and topoi, mainly derived from classical tradition and contemporary travel writing, circulate in the works of the three Renaissance authors included (Spenser, Marlowe, Milton), they are differently inflected and serve different thematic and ideological purposes. It is also suggested that the somewhat nascent orientalism of these authors develops into a more fully-fledged one in Thomas Moore’s Lalla Rookh where a basically Romantic notion of Persia as an exotic land is overridden by its construction as a realm fallen to foreign domination and cultural dispossession so as to displace the poet’s radical political views. Finally, it is shown how the motifs and topoi teased out in the analysis of the matter of Persia in the works of the authors preceding James Morier find their characteristic form and their most effective articulation in his fiction, especially the Hajji Baba novels which arrogate the representation of the ‘real’ Persia. Central to the analysis is the point that though Said’s theorisation of orientalism is immensely useful, and essential, to any consideration of the orientalist canon, issues such as masquerading and displacing as well as the specificities of each text, of its context, and of the object of representation, compound the notion of orientalism as merely a mode of Western domination and hegemony
Evaluation of Post-license Advanced Driver Training in Italy
No full textAbstractPost-license advanced driver training addresses different categories of road users such as: novice drivers, professional drivers, company employers and recidivists. These training courses can be carried out on-track or on the road. On-track courses allow participants to gain knowledge on driving physics and experience limits in a safe road environment. On-road courses are more focused on hazard perception and situation awareness.Although extensive research has been done in this field, knowledge of the effects of these courses on road accident risk remains unclear. Previous evaluation of on-track courses did not always show a positive effect on crash rate. For example, post-license training focused on mastery of driving skills can lead to an increase of accident risk, especially on young males.However, research identified several factors that may enhance the effectiveness of driving training. In Europe a new framework for driver education and training has been proposed based on a safe driver hierarchical model (the GADGET model) and the development of a strategy for continuous learning.According to this framework, an evaluation study of on-track post-license advanced driver training has been undertaken in Italy with the main goal of assessing the safety effects of these courses and identifying training aspects to be improved. Besides crash rate, the study aims at assessing also driver behavior, knowledge of risks, self-evaluation and training quality.This paper presents the results of the possible effects of advanced driver training on driving behavior, considering in particular the number and type of violations. For each driver, data on age, gender and driving violations history were extracted from the platform and the national violations database.Three cases were addressed through a before-after analysis with control group. Case 1 considers all drivers who attended an ADT course. Case 2 aimed at understanding the effects of the courses on a specific target group: the traffic violators. Case 3 is similar to Case 2, however the control group was selected in a way that drivers characteristics and the violation rate was similar to the violation rate of the treatment group in the before period.The significance of the differences highlighted was assessed through appropriate statistical tests (i.e. paired t-test and the Wilcoxon signed-rank test).The study showed in general a higher propensity to commit traffic violations after attending an ADT course. These results are in contrast to what expected and show the necessity to diversify the training classes according to the different needs of participants
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