Un modelo constituvo para el análisis de sólidos elastoplásticos sometidos a grandes deformaciones

En este trabajo se discute la implementación numérica de un modelo constitutivo para el análisis de sólidos elastoplásticos con grandes deformaciones. Dicho modelo se ha propuesto en la parte 1 de este trabajo. La integración de la ecuación constitutiva se basa en un algoritmo del tipo predictor elástico-corrector plástico. El algoritmo obtenido para las tensiones es muy simple y eficiente. El corrector plástico conduce a utilizar el algoritmo de retorno radial de la misma manera que en el problema de pequeñas deformaciones. A partir de un funcional de Hu-Washizu se obtiene la expresión del cálculo de las fuerzas internas. La discretización espacial se realiza mediante elementos finitos Ql/PO. Finalmente se resuelven varios ejemplos de aplicación.Peer Reviewe

Towards efficient intrusion detection systems based on machine learning techniques

Intrusion Detection System (IDS) have been the key in the network manager daily fight against continuous attacks. However, with the Internet growth, network security issues have become more difficult to handle. Jointly, Machine Learning (ML) techniques for traffic classification have been successful in terms of performance classification. Unfortunately, most of these techniques are extremely CPU time consuming, making the whole approach unsuitable for real traffic situations. In this work, a description of a simple software architecture for ML based is presented together with the first steps towards improving algorithms efficience in some of the proposed modules. A set experiments on the 199 DARPA dataset are conducted in order to evaluate two atribute selecting algorithms considering not only classsification perfomance but also the required CPU time. Preliminary results show that computadtioal effort can be reduced by 50% maintaining similar accuaracy levels, progressing towards a real world implementation of an ML based IDS.Presentado en el V Workshop Arquitectura, Redes y Sistemas Operativos (WARSO)Red de Universidades con Carreras en Informática (RedUNCI

Un modelo constituvo para el análisis de sólidos elastoplásticos sometidos a grandes deformaciones

En este trabajo se discute la implementación numérica de un modelo constitutivo para el análisis de sólidos elastoplásticos con grandes deformaciones. Dicho modelo se ha propuesto en la parte 1 de este trabajo. La integración de la ecuación constitutiva se basa en un algoritmo del tipo predictor elástico-corrector plástico. El algoritmo obtenido para las tensiones es muy simple y eficiente. El corrector plástico conduce a utilizar el algoritmo de retorno radial de la misma manera que en el problema de pequeñas deformaciones. A partir de un funcional de Hu-Washizu se obtiene la expresión del cálculo de las fuerzas internas. La discretización espacial se realiza mediante elementos finitos Ql/PO. Finalmente se resuelven varios ejemplos de aplicación.Peer Reviewe

Un modelo constitutivo para el análisis de sólidos elastoplásticos sometidos a grandes deformaciones

En el trabajo se presenta la formulación de un modelo constitutivo capaz de simular, de manera general, procesos elastoplásticos con grandes deformaciones. El desarrollo del modelo se basa en la descomposición multiplicativa del tensor gradiente de la deformación F = Fe. Fp. Luego, la energía libre y las variables internas se escriben en la configuración intermedia, en la que se desarrolla el modelo. Mediante el empleo de la fórmula de Doyle y Ericksen se obtiene la expresión espacial del modelo. Finalmente se aplica el modelo general al caso de metales. En este caso se utiliza a posteriori la hipótesis de pequeñas deformaciones elásticas, típica de estos materiales. En otro trabajo que continúa y acompaña al presente se trata la implementación numérica y se presentan ejemplos de aplicación.Peer Reviewe

LOGOS: Enabling Local Resource Managers for the Efficient Support of Data-Intensive Workflows within Grid Sites

In this study we discuss how to enable grid sites for the support of data-intensive workflows. Usually, within grid sites, tasks and resources are administrated by local resource managers (LRMs). Many of LRMs have been designed for managing compute-intensive applications. Therefore, data-intensive workflow applications might not perform well on such environments due to the number and size of data transfers between tasks. To improve the performance of such kind of applications it is necessary to redefine the scheduling policies integrated on LRMs. This paper proposes a novel scheme for efficiently supporting data-intensive workflows in LRMs within grid sites. Such scheme is partially implemented in our grid middleware LOGOS and used to improve the performance of a well known LRM: HTCondor. The core of LOGOS is a novel communication-aware scheduling algorithm (PPSA) capable of finding near-optimal solutions. Experiments conducted in this study showed that our approach leads to performance improvements up to 52 % in the management of data-intensive workflow applications

Observer effect: How Intercepting HTTPS traffic forces malware to change their behavior

During the last couple of years there has been an important surge on the use of HTTPs by malware. The reason for this increase is not completely understood yet, but it is hypothesized that it was forced by organizations only allowing web traffic to the Internet. Using HTTPs makes malware behavior similar to normal connections. Therefore, there has been a growing interest in understanding the usage of HTTPs by malware. This paper describes our research to obtain large quantities of real malware traffic using HTTPs, our use of man-in-the-middle HTTPs interceptor proxies to open and study the content, and our analysis of how the behavior of the malware changes after being intercepted. The research goal is to understand how malware uses HTTPs and the impact of intercepting its traffic. We conclude that the use of a interceptor proxy forces the malware to change its behavior and therefore should be carefully considered before being implemented.VI Workshop de Seguridad Informática (WSI).Red de Universidades con Carreras en Informática (RedUNCI

A cloud based WSN remote laboratory for user training

This paper presents a WSN remote laboratory prototype aimed at user training. The prototype has been deployed on a Cloud Computing infrastructure, in order to take advantage of the benefits that this technology can provide to remote laboratories. An analysis of the state of the art allows to specified the features required for a remote laboratory intended to be applyed in user training. In this paper, the main results of this analysis are presented. Then, the implementation of the main modules that compose the remote laboratory, and the analysis that led to chose a deployment based on Cloud Computing are presented. Some proof of concept experiments to test the applicability to user training were performed and the results are presented in this paper.Área: Tecnología en Educación.Red de Universidades con Carreras en Informática (RedUNCI

A cloud based WSN remote laboratory for user training

This paper presents a WSN remote laboratory prototype aimed at user training. The prototype has been deployed on a Cloud Computing infrastructure, in order to take advantage of the benefits that this technology can provide to remote laboratories. An analysis of the state of the art allows to specified the features required for a remote laboratory intended to be applyed in user training. In this paper, the main results of this analysis are presented. Then, the implementation of the main modules that compose the remote laboratory, and the analysis that led to chose a deployment based on Cloud Computing are presented. Some proof of concept experiments to test the applicability to user training were performed and the results are presented in this paper.Área: Tecnología en Educación.Red de Universidades con Carreras en Informática (RedUNCI