836 resultados para Research networks


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In recent years, there has been an enormous growth of location-aware devices, such as GPS embedded cell phones, mobile sensors and radio-frequency identification tags. The age of combining sensing, processing and communication in one device, gives rise to a vast number of applications leading to endless possibilities and a realization of mobile Wireless Sensor Network (mWSN) applications. As computing, sensing and communication become more ubiquitous, trajectory privacy becomes a critical piece of information and an important factor for commercial success. While on the move, sensor nodes continuously transmit data streams of sensed values and spatiotemporal information, known as ``trajectory information". If adversaries can intercept this information, they can monitor the trajectory path and capture the location of the source node. This research stems from the recognition that the wide applicability of mWSNs will remain elusive unless a trajectory privacy preservation mechanism is developed. The outcome seeks to lay a firm foundation in the field of trajectory privacy preservation in mWSNs against external and internal trajectory privacy attacks. First, to prevent external attacks, we particularly investigated a context-based trajectory privacy-aware routing protocol to prevent the eavesdropping attack. Traditional shortest-path oriented routing algorithms give adversaries the possibility to locate the target node in a certain area. We designed the novel privacy-aware routing phase and utilized the trajectory dissimilarity between mobile nodes to mislead adversaries about the location where the message started its journey. Second, to detect internal attacks, we developed a software-based attestation solution to detect compromised nodes. We created the dynamic attestation node chain among neighboring nodes to examine the memory checksum of suspicious nodes. The computation time for memory traversal had been improved compared to the previous work. Finally, we revisited the trust issue in trajectory privacy preservation mechanism designs. We used Bayesian game theory to model and analyze cooperative, selfish and malicious nodes' behaviors in trajectory privacy preservation activities.

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En base a los resultados obtenidos en investigaciones efectuadas por el grupo de investigación del Instituto de Investigaciones en Humanidades y Ciencias Sociales (UNLP-CONICET) sobre redes sociales en distintos tipos de bibliotecas (de investigación, universitarias y populares) en Argentina, se efectúa un balance sobre su uso en este tipo de instituciones y se proponen lineamientos para la formulación de una política comunicacional que las contemple y forme parte del plan de gestión de estas unidades de información. Los mismos apuntan a considerar cabalmente todos los aspectos vinculados a los alcances, limitaciones, usos, riesgos y demás que implica la adopción y la apropiación de diferentes redes sociales (tales como Facebook, Twitter, entre otras), su convivencia, gestión y sustentabilidad a lo largo del tiempo

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With the eye-catching advances in sensing technologies, smart water networks have been attracting immense research interest in recent years. One of the most overarching tasks in smart water network management is the reduction of water loss (such as leaks and bursts in a pipe network). In this paper, we propose an efficient scheme to position water loss event based on water network topology. The state-of-the-art approach to this problem, however, utilizes the limited topology information of the water network, that is, only one single shortest path between two sensor locations. Consequently, the accuracy of positioning water loss events is still less desirable. To resolve this problem, our scheme consists of two key ingredients: First, we design a novel graph topology-based measure, which can recursively quantify the "average distances" for all pairs of senor locations simultaneously in a water network. This measure will substantially improve the accuracy of our positioning strategy, by capturing the entire water network topology information between every two sensor locations, yet without any sacrifice of computational efficiency. Then, we devise an efficient search algorithm that combines the "average distances" with the difference in the arrival times of the pressure variations detected at sensor locations. The viable experimental evaluations on real-world test bed (WaterWiSe@SG) demonstrate that our proposed positioning scheme can identify water loss event more accurately than the best-known competitor.

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From a pragmatic point of view, it is the people who make an organisation, but organisations are both people and structures, and not least organisations develop culture. One of the significant features of the European Educational Research Association (EERA) as an organisation is that many of its activities are run by people on a voluntary basis. Apart from a small office, now in Berlin, which oversees and handles the everyday management, participation on Council, reviewing and programming for ECER (European Conference on Educational Research), managing networks, etc. are all undertaken as voluntary work by academics from across Europe (and beyond). From the large group of people who are currently sustaining these activities, many have participated from the beginning, but many others, after having been once at the conference, returned and got engaged in the work, for instance within one of the networks. Among the many who participate in EERA activities, there is a diversity of reasons for doing so, but there seems to be something which is recurring in what people say about why they do it. One of these recurring ideas is that the discursive norms of the organisation are enforced in the context of welcoming people and ideas, and second, there exists an intellectual generosity and egalitarianism which encourages newcomers to participate rather than protect themselves. We believe that this tells something about what EERA and ECER are about.

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In the scope of the discussions about microgeneration (and microgrids), the avoided electrical losses are often pointed out as an important value to be credited to those entities. Therefore, methods to assess the impact of microgeneration on losses must be developed in order to support the definition of a suitable regulatory framework for the economic integration of microgeneration on distribution networks. This paper presents an analytical method to quantify the value of avoided losses that microgeneration may produce on LV networks. Intervals of expected avoided losses are used to account for the variation of avoided losses due to the number, size and location of microgenerators, as well as for the kind of load distribution on LV networks.

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The emergence of microgeneration has recently lead to the concept of microgrid, a network of LV consumers and producers able to export electric energy in some circumstances and also to work in an isolated way in emergency situations. Research on the organization of microgrids, control devices, functionalities and other technical aspects is presently being carried out, in order to establish a consistent technical framework to support the concept. The successful development of the microgrid concept implies the definition of a suitable regulation for its integration on distribution systems. In order to define such a regulation, the identification of costs and benefits that microgrids may bring is a crucial task. Actually, this is the basis for a discussion about the way global costs could be divided among the different agents that benefit from the development of microgrids. Among other aspects, the effect of microgrids on the reliability of the distribution network has been pointed out as an important advantage, due to the ability of isolated operation in emergency situations. This paper identifies the situations where the existence of a microgrid may reduce the interruption rate and duration and thus improve the reliability indices of the distribution network. The relevant expressions necessary to quantify the reliability are presented. An illustrative example is included, where the global influence of the microgrid in the reliability is commented.

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Prostate cancer is the most common non-dermatological cancer amongst men in the developed world. The current definitive diagnosis is core needle biopsy guided by transrectal ultrasound. However, this method suffers from low sensitivity and specificity in detecting cancer. Recently, a new ultrasound based tissue typing approach has been proposed, known as temporal enhanced ultrasound (TeUS). In this approach, a set of temporal ultrasound frames is collected from a stationary tissue location without any intentional mechanical excitation. The main aim of this thesis is to implement a deep learning-based solution for prostate cancer detection and grading using TeUS data. In the proposed solution, convolutional neural networks are trained to extract high-level features from time domain TeUS data in temporally and spatially adjacent frames in nine in vivo prostatectomy cases. This approach avoids information loss due to feature extraction and also improves cancer detection rate. The output likelihoods of two TeUS arrangements are then combined to form our novel decision support system. This deep learning-based approach results in the area under the receiver operating characteristic curve (AUC) of 0.80 and 0.73 for prostate cancer detection and grading, respectively, in leave-one-patient-out cross-validation. Recently, multi-parametric magnetic resonance imaging (mp-MRI) has been utilized to improve detection rate of aggressive prostate cancer. In this thesis, for the first time, we present the fusion of mp-MRI and TeUS for characterization of prostate cancer to compensates the deficiencies of each image modalities and improve cancer detection rate. The results obtained using TeUS are fused with those attained using consolidated mp-MRI maps from multiple MR modalities and cancer delineations on those by multiple clinicians. The proposed fusion approach yields the AUC of 0.86 in prostate cancer detection. The outcomes of this thesis emphasize the viable potential of TeUS as a tissue typing method. Employing this ultrasound-based intervention, which is non-invasive and inexpensive, can be a valuable and practical addition to enhance the current prostate cancer detection.

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The presence of Lusitanian amphorae in the region of Carthago Nova (Cartagena, Spain) has been known for a few years, and yet it has never been the subject of a monographic study. Integrated in the commercial networks of the western Mediterranean, these products circulated within the harbour system of this city between the 1st and the 5th century AD. This paper aims to present a synthesised review of the main Lusitanian imports that were detected: Dressel 14 and Almagro 50, Almagro 51a-b and Almagro 51c. The difficulty in identifying the ceramic fabrics and the scarce documentation regarding some finds pose complex problems. This study extends to the hinterland of the colony and to other nearby settlements, such as Portmán and Puerto de Mazarrón.

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In the 16th century, merchants and bankers gained a social influence and political relevance, due to their capacity of ‘faire travailler l’argent des autres’ (Benassar 1972:50). For the success of their activity, they built evolving networks with cooperative partners. These networks were much more than the sum of all partners. In the case study of the Castilian merchant Simon Ruiz, the network functioned in an unique way and independent from any formal institutional control. Its functioning varied in how different partners were associated and the particular characteristics and contents of these social ties. Being a self-organized network, since the formal institutions of trade regulation and the Crown control didn’t influence the network functioning, the Simon Ruiz network was deeply embedded in the economic and financial performance of the Hispanic Empires, in two different ways. The first, purely commercial. The monopolistic regime which was applied by the two crowns in the trade of certain colonial goods was insufficient to the costs of imperial maintenance. In such manner, particulars tried to rent a contract of exploration of trade, paying an annual sum to the crown, as in the Portuguese trade. Some of these agents also moved along Simon Ruiz’s network. But others were involved in relations with the imperial crowns on a second way, the finance. Maintaining Empires implied a lot of human, technical but also financial means, and most of the times Kings were forced to recur to these merchants, as we will demonstrate. What were the implications of these collaborative relations in both parts? The main goal of this paper is to comprehend the evolution of informal norms within Simon Ruiz’s network and how they influenced cooperative behavior of the agents, particularly analyzing mechanisms of sanctioning, control, punishment and reward, as well as their consequences in different dimensions: future interactions, social repercussions and in agent’s economic health and activity. The research is based in the bills of exchange and commercial correspondence of the private archive of Simon Ruiz, located in the Provincial Archive of Valladollid, Spain.

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Xenakis’s first electroacoustic pieces (Diamorphoses, 1957; Concret PH, 1958; Analogique B, 1959; Orient-Occident, 1960; and Bohor, 1962) can be called musique concrète. Indeed, these works use the concrète musique tape techniques. But their spirit and aesthetic is very different from those set forth in Pierre Schaeffer’s theories. In fact, these works are quite particular in their whole conception. The two authors of this article are researching this period of Xenakis’s electroacoustic music. In this article, they offer a brief survey of the issues these works raised. To illustrate some of these issues, they use Diamorphoses and Bohor as examples.

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Nelore is the major beef cattle breed in Brazil with more than 130 million heads. Genome-wide association studies (GWAS) are often used to associate markers and genomic regions to growth and meat quality traits that can be used to assist selection programs. An alternative methodology to traditional GWAS that involves the construction of gene network interactions, derived from results of several GWAS is the AWM (Association Weight Matrices)/PCIT (Partial Correlation and Information Theory). With the aim of evaluating the genetic architecture of Brazilian Nelore cattle, we used high-density SNP genotyping data (~770,000 SNP) from 780 Nelore animals comprising 34 half-sibling families derived from highly disseminated and unrelated sires from across Brazil. The AWM/PCIT methodology was employed to evaluate the genes that participate in a series of eight phenotypes related to growth and meat quality obtained from this Nelore sample.