Category Theory and Model-Driven Engineering: From Formal Semantics to Design Patterns and Beyond

There is a hidden intrigue in the title. CT is one of the most abstract mathematical disciplines, sometimes nicknamed "abstract nonsense". MDE is a recent trend in software development, industrially supported by standards, tools, and the status of a new "silver bullet". Surprisingly, categorical patterns turn out to be directly applicable to mathematical modeling of structures appearing in everyday MDE practice. Model merging, transformation, synchronization, and other important model management scenarios can be seen as executions of categorical specifications. Moreover, the paper aims to elucidate a claim that relationships between CT and MDE are more complex and richer than is normally assumed for "applied mathematics". CT provides a toolbox of design patterns and structural principles of real practical value for MDE. We will present examples of how an elementary categorical arrangement of a model management scenario reveals deficiencies in the architecture of modern tools automating the scenario.Comment: In Proceedings ACCAT 2012, arXiv:1208.430

Towards numerical simulation of yarn insertion on air-jet weaving looms

In this research a structural solver and flow solver are coupled to simulate the motion of a nylon yarn as it is launched into the atmosphere by a main nozzle of an air-jet weaving loom. The high-speed air flow, large displacements of the yarn, 3D-nature of the problem and the contact between yarn and nozzle wall pose substantial challenges to both solvers. Furthermore, the large displacements necessitate a two-way coupling which drastically increases the computational time required. In fluid-structure interaction simulations, the flexible structure is often modelled using continuum elements. However, in this work, the use of beam theory to model the yarn is investigated. Switching to beam theory allows reducing the computational time required for the structural solver, but requires adaptations to the fluid-structure interaction code so that forces are projected onto the centreline and centreline displacements are converted into 3D displacements of the surface nodes. To validate the use of beam elements, a structural simulation is performed in which a section of the yarn is mechanically pulled through the main nozzle. Afterwards the correct functioning of the beam elements is tested by performing a fluid-structure interaction simulation on a 3D, cantilevered beam in cross-flow. Finally, a simulation is performed in which a nylon yarn (diameter 0.72 mm) is unwound by the main nozzle air flow (5 bar gauge) and launched into the atmosphere. The gain in computational time by switching to beam elements is evaluated

Modeling reinforcement structures in textile aimed at biomechanical purposes

While sporting, muscles, tendons and the body in general come under extreme loads which may lead to wrong movements and injuries which impact the performance or lead to mandatory rest. As athletes often wear compression garments, we investigate how reinforcement structures such as elastic bands, yarns or fabric strips with a given pretension, or rigid structures can be added to compression garments to prevent incorrect sport movements. This paper discusses how an existing simulation tool (DySiFil) can be adapted to be able to extract supportive forces and pressures and validates the findings for the case of overextension of the fingers and the thumb

Derivation of Continuum Traffic Model for Weaving Sections on Freeways.

This paper presents a new continuum model describing the dynamics of multiclass traffic flow on multilane freeways including weaving sections. In this paper, we consider a specific freeway weaving type, which is formed when an on ramp is near to an off ramp and these two ramps are joined by an auxiliary lane. Traffic interactions in this weaving zone are very complex due to the involvement of weaving flows and non-weaving flows in the so-called mandatory lane-changing process. To handle this complexity, it is essential to have a good understanding of the (microscopic) driving behavior within the weaving zones. These behaviors are modeled based on a gap-acceptance model. The methodology to obtain a weaving continuum traffic model is thus twofold. On the one hand, we develop a (macroscopic) model to determine the mandatory lane-changing probability based on a renewal process. On the other hand, we implement the lane-changing model into a current gas-kinetic traffic flow model for heterogeneous traffic flow on multilane roadways. From this, corresponding macroscopic model is obtained based on the method of moments

Early aspects: aspect-oriented requirements engineering and architecture design

This paper reports on the third Early Aspects: Aspect-Oriented Requirements Engineering and Architecture Design Workshop, which has been held in Lancaster, UK, on March 21, 2004. The workshop included a presentation session and working sessions in which the particular topics on early aspects were discussed. The primary goal of the workshop was to focus on challenges to defining methodical software development processes for aspects from early on in the software life cycle and explore the potential of proposed methods and techniques to scale up to industrial applications