CRML (the Common Requirement Modeling Language)

is a new language for the formal expression of require-

ments. The ambition is to release the language as an

open standard integrated into the open source modeling

and simulation tool OpenModelica and interoperable with

the open systems engineering standard SysMLv2. CRML

allows to express requirements as multidisciplinary spa-

tiotemporal constraints that can be verified against system

design by co-simulating requirements models with behav-

ioral models. Particular attention is paid to the follow-

ing aspects. The requirements models must be easily legi-

ble and sharable between disciplines and stakeholders and

must capture realistic constraints on the system, including

time-dependent constraints with probabilistic criteria, in

recognition of the fact that no constraint can be fulfilled

at any time at any cost. The theoretical foundation of the

language lies on 4-valued Boolean algebra, set theory and

function theory. The coupling of the requirements models

to the behavioral models is obtained through the specifi-

cation of bindings, the automatic generation of Modelica

code from the CRML model and use of the FMI and SSP

standards. CRML and the proposed methodology is com-

patible with SysMLv2, forming a comprehensive work-

flow and tool-chain encompassing requirement analysis,

system design and V&V. The final objective is to facil-

itate the demonstration of correctness of system behavior

against assumptions and requirements by building a work-

flow around Model-Driven Engineering and Open Stan-

dards for automating the creation of verification simula-

tors.

This article outlines a new approach of the experimental open-source modeling and simulation system Modia to simulate systems where the number of variables and equations can be changed after compilation and also during simulation, without having to re-generate and rec-ompile the code.

Details are given for heat transfer in an insulated rod, where the discretisation of the rod is completely hidden from the symbolic engine.

It is discussed how this approach could also be used in a future version of Modelica and/or FMI.

Furthermore, this feature is also used in various variants to speed up collision handling in 3D mechanical systems.

For example, by rigidly fixing an object after it has been gripped, with or without calculating the elastic response, and thereby dynamically changing the number of degrees of freedom.

Modelica enables an object-oriented approach to model complex systems in product development and research, and, thus, the development of various model libraries. Library development requires collaborative development in a team of multiple developers. A typical challenge in collaborative development, especially in the area of open source, is to create models of uniform quality despite different levels of knowledge among developers. Techniques such as Continuous Integration (CI) from the field of software development, can help to solve these challenges. However, the adaptation of CI for the area of Modelica model development currently requires the manual creation of complex templates and a high degree of manual configuration. In this paper we present MoCITempGen, an open source tool for automated generation of CI structures for the widely used modeling language Modelica. The tool is succesfully applied on two Modelica libraries to demonstrate the functionality.