Robustness-Driven Resilience Evaluation of Self-Adaptive Software Systems

An increasingly important requirement for certain classes of software-intensive systems is the ability to self-adapt their structure and behavior at run-time when reacting to changes that may occur to the system, its environment, or its goals. A major challenge related to self-adaptive software systems is the ability to provide assurances of their resilience when facing changes. Since in these systems, the components that act as controllers of a target system incorporate highly complex software, there is the need to analyze the impact that controller failures might have on the services delivered by the system. In this paper, we present a novel approach for evaluating the resilience of self-adaptive software systems by applying robustness testing techniques to the controller to uncover failures that can affect system resilience. The approach for evaluating resilience, which is based on probabilistic model checking, quantifies the probability of satisfaction of system properties when the target system is subject to controller failures. The feasibility of the proposed approach is evaluated in the context of an industrial middleware system used to monitor and manage highly populated networks of devices, which was implemented using the Rainbow framework for architecture-based self-adaptation

A RARE MUTUAL COURTSHIP DISPLAY IN A SOUTH AMERICAN PASSERIFORMES: BLUE-BILLED BLACK-TYRANT (KNIPOLEGUS CYANIROSTRIS) (TYRANNIDAE: FLUVICOLINAE)

Territorial displays are a common behavior in Knipolegus, but are only performed by males, while a mutual displays are unknown in this genus. In October 2012, in high-altitude grassland (Campos de Altitude), Espírito Santo state, south-east Brazil, a pair of Blue-billed Black Tyrant Knipolegus cyanirostris was filmed making very curious and subtle movements. Both individuals were silent, and perched facing each other 0.59–0.75 m apart, with the male slightly lower, at an angle of c. 21°–23° below the female. The male moved its head downwards, moving its bill in a pendulum-like, downward motion, then reassumed its upright stance, while the female, with its head slightly bent down, moved its bill in the same way as the male, before also reassuming her original stance. These movements were very fast and almost impossible to see with the human eye. This mutual display suggests that courtship behavior in Knipolegus may be much more complex than is currently believe

Self-Optimization of Low Coverage and High Interference in Real 3G/4G Radio Access Networks

This paper presents a new single cell multi-objectiveoptimization algorithm. The objective is to optimize areas oflow coverage and high interference simultaneously, through theadjustment of the antenna tilts and/or antenna orientation. Theprocess is achieved using a specific implementation of a ParticleSwarm Optimization (PSO) algorithm. Both the detection ofsub-optimal performance areas and its subsequent optimizationare supported by Drive Test (DT) data and network topologyinformation. The antenna optimization algorithm was tested withreal data in 3rd Generation (3G)/4th Generation (4G) networks.In this work, a 3G urban scenario is highlighted, achieving anaverage optimization gain of 78%