Abstract
Aerospace systems software is developed taking into account some precautions to avoid dangerous situations. Usually the controllers of these systems are critical embedded real-time controllers and the respective software programs are developed in the C programming language. This paper is developed on the context of developing embedded critical real-time systems software, for aerospace systems applications, based on formalisms commonly used in the industrial automation field. More precisely, the approach proposed, in this paper, consists in translating a SFC specification to C programming language code considering also the behaviour of the controller device, where the specification will be implemented. An illustrative case study is presented in the end of the paper in order to facilitate the understanding of the proposed approach.

Abstract
This article's main goal is to present a review on the principles of ergonomics applied to tools used for e-learning. It is known that the errors in the application of these principles entail cognitive overload on users of these platforms, so the article tries to address the issue comprehensively. Thus, in the first section presents the most notable ergonomic principles as the foundations of Cognitive and Informational Ergonomics and then presents guidelines for the usability of information systems that can serve as support for academic interactions. In the second part, there will be a discussion about some aspects from collaborative learning experiences among teachers and students in research projects and extension. The methodology of this paper points to a research of qualitative nature, where the aim was to understand the interactions virtually experienced by users of systems whose goal is to encourage the construction of the academic knowledge. The results of this research appear as an additional form of analysis of issues related to ergonomics, so that the information systems always prioritize the different profiles of its users.

Abstract
Motivated by the need to formalize generation of fast running code for linear algebra applications, we show how an index-free, calculational approach to matrix algebra can be developed by regarding matrices as morphisms of a category with biproducts. This shifts the traditional view of matrices as indexed structures to a type-level perspective analogous to that of the pointfree algebra of programming. The derivation of fusion, cancellation and abide laws from the biproduct equations makes it easy to calculate algorithms implementing matrix multiplication, the kernel operation of matrix algebra, ranging from its divide-and-conquer version to the conventional, iterative one. From errant attempts to learn how particular products and coproducts emerge from biproducts, we not only rediscovered block-wise matrix combinators but also found a way of addressing other operations calculationally such as e.g. Gaussian elimination. A strategy for addressing vectorization along the same lines is also given.

Abstract
The current trend of increasingly larger Web-based applications makes scalability the key challenge when developing, deploying, and maintaining data centers. At the same time, the migration to the cloud computing paradigm means that each data center hosts an increasingly complex mix of applications, from multiple owners and in constant evolution. Unfortunately, managing such data centers in a cost-effective manner requires that the scalability properties of the hosted workloads to be accurately known, namely, to proactively provision adequate resources and to plan the most economical placement of applications. Obviously, stopping each of them and running a custom benchmark to asses its scalability properties is not an option. In this paper we address this challenge with a tool to measure the software scalability regarding CPU availability, to predict system behavior in face of varying resources and an increasing workload. This tool does not depend on a particular application and relies only on Linux's SystemTap probing infrastructure. We validate the approach first using simulation and then in an actual system. The resulting better prediction of scalability properties should allow improved (self-)management practices.

Abstract
Component's QoS constraints cannot be ignored when composing them to build reliable loosely-coupled, distributed systems. Therefore they should be explicitly taken into account in any formal model for component-based development. Such is the purpose of this paper: to extend a calculus of component composition to deal, in an effective way, with QoS constraints. Particular emphasis is put on how the laws that govern composition can be derived, in a calculational, pointfree style, in this new model.

Abstract