Motrusca : interactive model transformation use case repository

Modeling and model transformations tools are maturing and are being used in larger and more complex projects. The advantage of a modeling environment and its transformation tools cannot be easily exploited by non-expert users as many subtle intricacies determine the efficiency of transformation languages and their tools. We introduce transformation use case examples that highlight such language/tooling properties. These simple, non-trivial examples have been extracted from an experiment with transformations of Design Space Exploration models. These examples show some typical modeling patterns and we give some insight how to address the examples. We make a case for initiating an interactive, on-line repository for model transformation use cases. This repository is aimed to be example-centric and should facilitate the interaction between end-users and tooling developers, while providing a means for comparing the applicability, expressivity, and efficiency of transformation tools

Motrusca : interactive model transformation use case repository

Modeling and model transformations tools are maturing and are being used in larger and more complex projects. The advantage of a modeling environment and its transformation tools cannot be easily exploited by non-expert users as many subtle intricacies determine the efficiency of transformation languages and their tools. We introduce transformation use case examples that highlight such language/tooling properties. These simple, non-trivial examples have been extracted from an experiment with transformations of Design Space Exploration models. These examples show some typical modeling patterns and we give some insight how to address the examples. We make a case for initiating an interactive, on-line repository for model transformation use cases. This repository is aimed to be example-centric and should facilitate the interaction between end-users and tooling developers, while providing a means for comparing the applicability, expressivity, and efficiency of transformation tools

Quantitative and qualitative evaluation of model transformation approaches for design space exploration

We investigate whether current model transformation tools are suitable for use in a high performance design space exploration environment. Performance, scalability, maintainability, initial implementation effort, environment compatibility and traceability are conflicting properties in model transformations for such environments. This paper compares several model transformation approaches and provides an overview of their characteristics in the context of design space exploration for software-intensive embedded systems. We characterize several transformation approaches for exogenous model transformations in a real industrial use case. The result shows that, in the chosen approaches, the maintainability cannot significantly improve without losing performance. We recognize, however, the maturation of promising techniques that design space exploration may benefit from. We investigate whether current model transformation tools are suitable for use in a high performance design space exploration environment. Performance, scalability, maintainability, initial implementation effort, environment compatibility and traceability are conflicting properties in model transformations for such environments. This paper compares several model transformation approaches and provides an overview of their characteristics in the context of design space exploration for software-intensive embedded systems. We characterize several transformation approaches for exogenous model transformations in a real industrial use case. The result shows that, in the chosen approaches, the maintainability cannot significantly improve without losing performance. We recognize, however, the maturation of promising techniques that design space exploration may benefit from

Optimization of product flows in flexible manufacturing systems

Efficient merging of streams of sheets in industrial printer

Parametric critical path analysis for event networks with minimal and maximal timelags

High-end manufacturing systems are cyber-physical systems where productivity depends on the close cooperation of mechanical (physical) and scheduling (cyber) aspects. Mechanical and control constraints impose minimal and maximal time differences between events in the product flow. Sequence-dependent constraints are used by a scheduler to optimize system productivity while satisfying operational requirements. The numerous constraints in a schedule are typically related to a relatively small set of parameters, such as speeds, lengths, or settling times. We contribute a parametric critical path algorithm that identifies bottlenecks in terms of the feasible parameter combinations. This algorithm allows analysis of schedules to identify bottlenecks in terms of the underlying cause of constraints. We also contribute a way to find Pareto-optimal cost-performance trade-offs and their associated parameter combinations. These results are used to quantify the impact of relaxing constraints that hinder system productivity

A heuristic for variable re-entrant scheduling problems

Flexible Manufacturing Systems (FMSs) need a scheduler to provide timing instructions for the operations of different products. Previous work has presented heuristics for fixed-order 2-re-entrant scheduling problems [1], [2]; where products visit a re-entrant machine exactly two times for production. We propose an extension to this scheduling model, and an extension to the scheduling heuristic, that allows jobs to move along different flows on re-entrant machines; i.e. jobs can (re)visit the re-entrant machine once or twice. An FMS that requires such variable re-entrance with fixed-order output is a Large Scale Printer (LSP). The scheduling problem in an LSP is modeled as a variable re-entrance flowshop with relative due dates and sequence-dependent setup times. We identify the impact of the fixed order requirement on the variable re-entrance scheduling problem. We show that out-of-order input of products can be beneficial to the scheduling quality in variable re-entrance scheduling. The fixed re-entrant heuristic of [1] is extended with a method to order operations on the re-entrant machine to minimize the completion time of variable re-entrant job sets. The resulting heuristic produces good quality schedules for variable re-entrant job sets without losing schedule quality for fixed reentrant job set

Online scheduling of 2-re-entrant flexible manufacturing systems

Online scheduling of operations is essential to optimize productivity of flexible manufacturing systems (FMSs) where manufacturing requests arrive on the fly. An FMS processes products according to a particular flow through processing stations. This work focusses on online scheduling of re-entrant FMSs with flows using processing stations where products pass twice and with limited buffering between processing stations. This kind of FMS is modelled as a re-entrant flow shop with due dates and sequence-dependent set-up times. Such flow shops can benefit from minimization of the time penalties incurred from set-up times. On top of an existing greedy scheduling heuristic we apply a meta-heuristic that simultaneously explores several alternatives considering trade-offs between the used metrics by the scheduling heuristic. We identify invariants to efficiently remove many infeasible scheduling options so that the running time of online implementations is improved. The resulting algorithm is much faster than the state of the art and produces schedules with on average 4.6% shorter makespan

A fast estimator of performance with respect to the design parameters of self re-entrant flowshops

Self re-entrant flowshops consist of machines which process jobs several times. They are found in applications like TFT-LCD assembly, LED manufacturing and industrial printing. The structure of a self re-entrant flowshop influences its performance. To get better performance while reducing costs a fast performance estimation method can be used to explore the trade-offs between the structure and the performance during the design process. We present a novel performance estimator that uses the information in the jobs being processed to analyse the trade-offs. We study the impact of the design parameters of an industrial printer using the performance estimator with an average estimation time of 1.1 milliseconds per job and with an average accuracy of not less than 96%

xCPS : a tool to eXplore cyber physical systems

Cyber-Physical Systems (CPS) play an important role in the modern high-tech industry. Designing such systems is a challenging task due to the multi-disciplinary nature of these systems, and the range of abstraction levels involved. To facilitate hands-on experience with such systems, we develop a cyber-physical platform that aids in research and education on CPS. This paper describes this platform, which contains all typical CPS components. The platform is used in various research and education projects for bachelor, master, and PhD students. We discuss the platform and a number of projects and the educational opportunities they provide