Taming Uncertainty in the Assurance Process of Self-Adaptive Systems: a Goal-Oriented Approach

Goals are first-class entities in a self-adaptive system (SAS) as they guide the self-adaptation. A SAS often operates in dynamic and partially unknown environments, which cause uncertainty that the SAS has to address to achieve its goals. Moreover, besides the environment, other classes of uncertainty have been identified. However, these various classes and their sources are not systematically addressed by current approaches throughout the life cycle of the SAS. In general, uncertainty typically makes the assurance provision of SAS goals exclusively at design time not viable. This calls for an assurance process that spans the whole life cycle of the SAS. In this work, we propose a goal-oriented assurance process that supports taming different sources (within different classes) of uncertainty from defining the goals at design time to performing self-adaptation at runtime. Based on a goal model augmented with uncertainty annotations, we automatically generate parametric symbolic formulae with parameterized uncertainties at design time using symbolic model checking. These formulae and the goal model guide the synthesis of adaptation policies by engineers. At runtime, the generated formulae are evaluated to resolve the uncertainty and to steer the self-adaptation using the policies. In this paper, we focus on reliability and cost properties, for which we evaluate our approach on the Body Sensor Network (BSN) implemented in OpenDaVINCI. The results of the validation are promising and show that our approach is able to systematically tame multiple classes of uncertainty, and that it is effective and efficient in providing assurances for the goals of self-adaptive systems

Cosmotic, Aquatic. Exploring the potential of computational design in the preservation of aquatic ecotones

This paper looks at the possible role of computational design ecologically in the fight against the loss of the aquatic Ecotone. As climate change keeps altering all the natural aspects of our planet, and as our kind continues to sabotage its ecologies, coral reefs come in focus. Aquatically, coral reefs count as a fertile zone for biodiversity. Usually being the Ecotone between land and sea, these barriers host many species and riches. However, due to the excessive abuse caused by human activity be it world-wide pollution or direct human contact, these reefs are constantly bleaching and breaking. In 2016, the Architecture Association gathered a group of international architecture students and professionals in a visiting school in Jordan titled “Hyperbolic Reefs” looking at the possibility of recruiting new computational methods to preserve and possibly regenerate the Ecotone. It was considered that new simulation techniques along with parametric design could contribute into the assessment and prevention of the catastrophic results. The two-week event was divided into chapters and was initiated by a series of lectures and discussions conducted by worldwide leading architects and experts who presented an important material to build upon. Then, the participants underwent a site visit to the coral reef of Al-Aqaba, collecting data, samples and media and recording insights and local testimonies. The third step of the experience was to assimilate the material and data and discuss openly the ways that computation could lead to a better coral life. Several software and tools were assigned to produce a design that would help attenuate the compromise of the coral reef through computation. An archive of data was produced and exhibited to the public. The results of this brief exercise was a number of suggestions and future aspirations triggered solely towards revitalizing the Ecotone. Issues such as the abundance of irresponsible snorkeling and diving, many governments’ indifferent policies towards the coral reefs, global warming, climate change, coral bleaching and aquatic architecture were confronted through parametric projects ranging from purely architectural to abstract human capsules. Computational tools allowed the reproduction of the whole system digitally, the precise tracing of the corals’ patterns, dimensions and colors, simulation software predicted the role of light and heat in certain zones, and parametric programs provided an incomparable flexibility in the designing process, going completely in sync with the fragile and intricate aspect of a coral unit. 3D printing was also an integral factor in the presentation and study of the presented models. This study’s scope was to expand the use of computation in a theoretical way to reach new and creative prospects, and to raise awareness to the situation of the coral reef and the risks facing its degradation

Relating Objective and Subjective Performance Measures for AAM-based Visual Speech Synthesizers

We compare two approaches for synthesizing visual speech using Active Appearance Models (AAMs): one that utilizes acoustic features as input, and one that utilizes a phonetic transcription as input. Both synthesizers are trained using the same data and the performance is measured using both objective and subjective testing. We investigate the impact of likely sources of error in the synthesized visual speech by introducing typical errors into real visual speech sequences and subjectively measuring the perceived degradation. When only a small region (e.g. a single syllable) of ground-truth visual speech is incorrect we find that the subjective score for the entire sequence is subjectively lower than sequences generated by our synthesizers. This observation motivates further consideration of an often ignored issue, which is to what extent are subjective measures correlated with objective measures of performance? Significantly, we find that the most commonly used objective measures of performance are not necessarily the best indicator of viewer perception of quality. We empirically evaluate alternatives and show that the cost of a dynamic time warp of synthesized visual speech parameters to the respective ground-truth parameters is a better indicator of subjective quality