7,593 research outputs found
Enabling Practical IPsec authentication for the Internet
On the Move to Meaningful Internet Systems 2006: OTM 2006 Workshops (First International Workshop on Information Security (IS'06), OTM Federated Conferences and workshops). Montpellier, Oct,/Nov. 2006There is a strong consensus about the need for IPsec, although its use is not widespread for end-to-end communications. One of the main reasons for this is the difficulty for authenticating two end-hosts that do not share a secret or do not rely on a common Certification Authority. In this paper we propose a modification to IKE to use reverse DNS and DNSSEC (named DNSSEC-to-IKE) to provide end-to-end authentication to Internet hosts that do not share any secret, without requiring the deployment of a new infrastructure. We perform a comparative analysis in terms of requirements, provided security and performance with state-of-the-art IKE authentication methods and with a recent proposal for IPv6 based on CGA. We conclude that DNSSEC-to-IKE enables the use of IPsec in a broad range of scenarios in which it was not applicable, at the price of offering slightly less security and incurring in higher performance costs.Universidad de Montpellier IIPublicad
Paleoliquefaction in the Bajo Segura basin (eastern Betic Cordillera)
The Bajo Segura basin, in the eastern Betic Cordillera, displays a seismic activity characterized by small-magnitude earthquakes (1.5-4.5 mb), with some occasional moderate to high-magnitude events (> 5.0 mb). These earthquakes are produced by the activity of blind faults without surface ruptures. For this reason, the detection of paleoearthquakes in the geological record is limited to indirect evidence of paleoseismicity, mainly liquefaction features. Moreover, such evidence is abundant in the historical record of the 1829 Torrevieja earthquake, in some of its aftershocks and in the 1919 Jacarilla earthquake. In this study several layers of Holocene seismites previously described in the basin were analyzed, and correlated with various radiometric 14C datings. This analysis enabled a recurrence period of approx. 1000 yr to be established for the moderate to high-magnitude earthquakes in the Bajo Segura basin.La cuenca del Bajo Segura, localizada en la Cordillera BĂ©tica oriental, tiene una actividad sĂsmica caracterizada principalmente por terremotos de pequeña magnitud (1.5-4.5 mb), aunque ocasionalmente han ocurrido terremotos de magnitud moderada-alta (> 5 mb). Estos terremotos estĂĄn producidos por la actividad de fallas que no presentan ruptura en superficie (fallas ciegas). Por este motivo, el reconocimiento de paleoterremotos en el registro geolĂłgico se limita a las evidencias indirectas de paleosismicidad entre las que destacan las estructuras de licuefacciĂłn sĂsmica. AdemĂĄs se tiene constancia de numerosas manifestaciones de licuefacciĂłn en el terremoto histĂłrico de Torrevieja de 1829, en alguna de sus rĂ©plicas y en el terremoto de Jacarilla de 1919. En este trabajo se han analizado varios niveles de sismitas holocenas descritos previamente en la cuenca, y se han correlacionado con varias dataciones radiomĂ©tricas de 14 C . Este anĂĄlisis ha permitido establecer un periodo de recurrencia de terremotos de magnitud moderada-alta en la cuenca del Bajo Segura, de aproximadamente 1000 años
Homogenization on multi-materials' elements: application to printed circuit boards and warpage analysis
Multi-material domains are often found in industrial applications. Modelling them can be computationally very expensive due to meshing requirements. The finite element properties comprising different materials are hardly accurate. In this work, a new homogenization method that simplifies the computation of the homogenized Young modulus, Poisson ratio and thermal expansion coefficient is proposed, and applied to composite-like material on a printed circuit board. The results show a good properties correspondence between the homogenized domain and the real geometry simulation.This research is sponsored:
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by the Portugal Incentive System for Research and
Technological Development. Project in co
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promotion nÂș
36265/2013 (Project HMIExcel
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2013
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2015),
and
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by FCT with the reference project
UID/EEA/04436/2013, by FEDER funds through the
COMPETE 2020
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Programa Operacional
Competitividade e Internacionalização (POCI) with the
reference project POCI
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01
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0145
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FEDER
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006941info:eu-repo/semantics/publishedVersio
Enhancement of Student Learning Through the Use of a Hinting Computer e-Learning System and Comparison with Human Teachers
This paper reports the results of an experiment in a Computer Architecture Laboratory course classroom session, in which students were divided into two groups for interaction both with a hinting e-learning system and with human teachers generating hints. The results show that there were high learning gains for both groups, demonstrating the effectiveness of the human teachers as well as of the computer-based hinting e-learning system even without the use of adaptive and personalization capabilities. In addition, in the worst case, the difference in favor of human teachers (with a low student-to-teacher ratio of 13.5 students per teacher) would not be significant with respect to the e-learning system, so the computer-based system can replace teachers without a significant loss of effectiveness.This work was supported in part by the Learn3 project TIN2008-05163/TSI within the Spanish âPlan Nacional de I+D+I,â and by the Madrid regional community project eMadrid S2009/TIC-1650.Publicad
Deciding on different hinting techniques in assessments for intelligent tutoring systems
Intelligent Tutoring Systems (ITSs) must take advantage of their high computing capabilities and capacity for information retrieval in order to provide the most effective methodologies for improving students' learning. One type of ITS provides assessments to students and some help as a hint, when they do not know how to solve a problem. Our thesis is that the type of hinting techniques used without changing the contents can influence the learning gains and aptitudes of students. We have implemented some hinting techniques as an extension to the XTutor ITS. We found that some hinting techniques can produce a signi cant increase in students' knowledge with respect to others, but the improvement and direction of the comparison depended on some other factors such as the topics to which it was applied. We conclude that proper adaptation of hinting techniques based on different information of the systems will imply better student learning gains. In addition, the results of a student survey, which includes the students' ratings of the different hinting features they interacted with, leads to high variances, which reinforce the idea of the importance of adaptation of hinting techniques in these types of systems.This work was supported in part by the MEC-CICYT Learn3 project TIN2008-05163/TSI (Spanish Ministry of Science and Education, Programa Nacional de TecnologĂas de la InformaciĂłn y de las Comunicaciones), and the e-Madrid project S2009/TIC-1650 (Madrid Regional Community).Publicad
Using bluetooth to implement a pervasive indoor positioning system with minimal requirements at the application level
Proyecto CCG10-UC3M/TIC-4992 de la Comunidad AutĂłnoma de Madrid y la Universidad Carlos III de MadridPublicad
Sending learning pills to mobile devices in class to enhance student performance and motivation in network services configuration courses
Teaching electrical and computer software engineers
how to configure network services normally requires the detailed
presentation of many configuration commands and their numerous
parameters. Students tend to find it difficult to maintain acceptable
levels of motivation. In many cases, this results in their not
attending classes and not dedicating enough time to acquire the
required competencies. This paper describes a successful experiment
that was able to improve student class attendance, performance,
and motivational patterns by using mobile devices in class
to provide students with contextualized learning pills. A learning
pill is a simple exercise that summarizes some of the key concepts
explained in class and promotes reflection and self-study. Each student
attending a particular lecture or laboratory session automatically
receives a learning pill on his or her mobile phone just after
the related concept has been presented. This paper details the scenario
used in the experiment and analyzes the performance and motivational patterns of 170 students at the Higher Polytechnic
School, Carlos III University of Madrid, Leganes, SpainThis work was supported by the ARTEMISA project TIN2009-
14378-C02-02 within the Spanish âPlan Nacional de I+D+Iâ and the Madrid regional community projects S2009/TIC-1650 and CCG10-UC3M/TIC-4992.Publicad
Exploring the Small Mass Limit of Stationary Black Holes in Theories with Gauss-Bonnet Terms
In this work we examine the small mass limit of black holes, with and without
spin, in theories with a scalar field non-minimally coupled to a Gauss-Bonnet
term. First, we provide an analytical example for a theory where a static
closed-form solution with a small mass limit is known, and later use analytical
and numerical techniques to explore this limit in standard scalar-Gauss-Bonnet
theories with dilatonic, linear and quadratic couplings. In most cases, we find
an inner singularity that overlaps with the event horizon of the static black
hole as the small mass limit is reached. Moreover, since solutions in this
limit possess a non-vanishing Hawking temperature, a naked singularity is
expected to be reached through evaporation, raising questions concerning the
consistency of these theories altogether. On the other hand, we provide for the
first time an example of a coupling where the small mass limit is never
reached, thus preferred from the point of view of cosmic censorship. Finally,
we consider black holes with spin and numerically investigate how this changes
the picture, using these to place the tightest upper bounds to date on the
coupling constant for the dilatonic and linear theories, with
km.Comment: 18 pages, 8 figure
Provision of awareness of learners' emotions through visualizations in a computer interaction-based environment
One of the challenges of intelligent systems for education is to use low-level data collected in computer environments in the form of events or interactions to infer information with high-level significance using artificial intelligence techniques, and present it through visualizations in a meaningful and effective way. Among this information, emotional data is gaining track in by instructors in their educational activities. Many benefits can be obtained if an intelligent systems can bring teachers with knowledge about their learner's emotions, learning causes, and learning relationships with emotions. In this paper, we propose and justify a set of visualizations for an intelligent system to provide awareness about the emotions of the learners to the instructor based on the learners' interactions in their computers. We apply these learner's affective visualizations in a programming course at University level with more than 300 students, and analyze and interpret the student's emotional results in connection with the learning process.Work partially funded by the EEE project, ââPlan Nacional de I+D+I TIN2011-28308-C03-01ââ and the ââEmadrid: InvestigaciĂłn y desarrollo de tecnologĂas para el e-learning en la Comunidad de Madridââ project (S2009/TIC-1650)ââ
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