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Ítem Software platform for services in Colombian cities using the Living Labs approach(Ieee, 2011-12-05) Navarro Cadavid, AndrésComponent Based Software Engineering is a way to improve software modularization and to embed architectural concerns in the source code. Making explicit the architectural concerns in code helps to mitigate the problem of architectural erosion. The restructuring of legacy code with components in mind requires the use of tools to assess compliance with component programming principles. The property of communication integrity is one of the major principles for implementing software architectures. However, there is a paucity of tools for assessing the quality of code components. To cope with this issue, we define a component model in Java and a tool for identifying component types, which relies on a set of rules to statically check potential violations of the communication integrity property in Java source code. We illustrate its application with a case study and report the results of our experiments with it.Ítem SNR estimation for on body communications in MB OFDM Ultra Wide Band communications(Ieee Computer Society, 2010-04-12) Navarro Cadavid, AndrésIn this paper a new signal to noise ratio estimator algorithm based on the moments of the received signal is presented. The novel algorithm has been designed for Ultra Wide Band communications based on Multi Band Orthogonal Frequency Division Multiplexing (MB-OFDM) communication systems. In this proposal, we analyze the behavior of ultra wide band channels when the time and frequency fading have fast changes. Hence, different time coherence values were considered and all the frequency fading models are based in real measurements made in an anechoic chamber. It is remarkable that all the measurement campaigns were focused on body communications. We conclude that the proposed model can be used for SNR estimation in adaptive modulation and channel estimation and link quality control in MB OFDM systems. The performance of the proposed SNR estimation algorithm and its comparison with other SNR estimators was achieved through simulations based on real channel measurements.Ítem Statistical adjustment of empirical propagation path loss models to the COST 2100 Cali reference scenario(Antennas and Propagation Society International Symposium (APSURSI), 2012 IEEE, 2012-11-12) Navarro Cadavid, AndrésPropagation models used to plan outdoor wireless networks on urban environment, tend to include a high degree of empirical component. These are derived from the difficulties of accurately estimate the influence of obstacles, buildings and terrain in the signal path loss. Therefore, the final equation usually contains constants, and coefficients for the different terms, mainly obtained by statistical analysis of measurement sets, collected during drive tests on large areas of the city. Unfortunately, such results are only truly valid for the city or parts of the city on which the measurements were taken. They can also be considered appropriate for similar areas or cities at the most. If the areas are not similar enough however, a process of adjustment is necessary, leading to the finding of new constants and coefficients. The purpose of this paper is to discuss some of the findings during the process of statistically adjust the Okumura-Hata and Walfisch-Bertoni models to the Cali scenario, using measurements.Ítem The UWB-OFDM Channel Analysis in Frequency(IEEE, 2009-06-12) Llano Ramírez, GonzaloIn this paper, the ultra-wideband channel with orthogonal frequency division multiplexing (UWB-OFDM) is analyzed in the frequency domain. For UWB-OFDM channels with log-normal fading in the time domain, we show that the amplitude of each subcarrier can be approximated by a Nakagami-m random variable, where the fading parameter, the mean power and the correlation coefficient are expressed in terms of the following parameters: time arrival of the clusters, inter-arrival time of rays inside clusters, and power decay constants of rays and clusters.Ítem Effects of diffuse and specular reflections on the perceived age of facial skin(Springer Verlag, 2012-05-01) Arce Lopera, Carlos AlbertoAge perception is a better biomarker of skin aging than chronological age. However, the optical cues that determine the perception of human skin age are difficult to assess given the complex interactions between light and the multi layered structure of the skin. The aim of the present study is to clarify the independent contribution of both diffuse and specular reflection components to the skin age perceptionÍtem Image statistics on the age perception of human skin(Wiley, 2013-02-01) Arce Lopera, Carlos AlbertoRecent research on the age-dependent changes of facial skin has analyzed their correlation with changes in image and colorimetric properties using mainly first- and second-order statistics. The aim of this study is to reveal the importance of third-order statistics and relate those image properties to skin age perception.Ítem Implementación de OpenFlow sobre NetFPGA(Universidad Surcolombiana, 2014-04-30) Machado, JohnnathanLas redes tradicionales están diseñadas e implementadas con diferentes dispositivos de red, como routers, switches y firewalls; cada uno tiene unas funciones asociadas y es configurado con diferentes estándares y protocolos para realizar la trasmisión de paquetes. Pero este modelo tradicional no es el único que existe, hoy en día se está empezando a imponer un nuevo modelo de red definida por software [SDN por Software Define Networks]. Si bien este modelo usa los mismos dispositivos de red, es diferente pues utiliza las ventajas del software de programación, el cual mediante una inter- faz universal controla los dispositivos de red y programa los servicios de envío o enrutamiento de paquetes. Este artículo presenta las ventajas de las SDN respecto de las redes tradicionales y muestra pruebas de desempeño básicas realizadas en un ambiente de laboratorio con una tarjeta NetFPGA implementando OpenFlow, en contraste con pruebas de desempeño realizadas con dispositivos de red comerciales.Ítem Runtime Evolution of Highly Dynamic Software(Springer,, 2014-01-01) Villegas Machado, Norha MilenaHighly dynamic software systems are applications whose operations are particularly affected by changing requirements and uncertainty in their execution environments. Ideally such systems must evolve while they execute. To achieve this, highly dynamic software systems must be instrumented with self-adaptation mechanisms to monitor selected requirements and environment conditions to assess the need for evolution, plan desired changes, as well as validate and verify the resulting system. This chapter introduces fundamental concepts, methods, and techniques gleaned from self-adaptive systems engineering, as well as discusses their application to runtime evolution and their relationship with off-line software evolution theories. To illustrate the presented concepts,