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08:40 | Accomplishing Ground Moving Innovations through Modeling, Simulation, and Optimal Control SPEAKER: Lars Eriksson ABSTRACT. The presentation will collect and summarize a set results from a project on applied optimal control of wheel loaders where numerical optimal control has been used to evaluate and guide design changes in the vehicles. The first part introduces the tool chain with modeling, numerical optimal control and evaluations that allows us to analyze complex systems with many states and significant non-linearities. The results achieved from applying the toolchain that will be discussed are three innovations ranging from hardware changes, software changes, and driver instructions. One is the evaluation of torque converter selection, showing that a stiff torque converter is better than a weak. The other is the benefits of designing the mechatronics of the transmission and brake by wire system with a system called “intelligent braking”. The last result has impact on the instruction that are given as guidelines to drivers, while working on a site. All in all this illustrates that Optimal Control has evolved beyond a controls engineer tool and can now be used in the engineering design and innovation of complex mechatronic products. |

09:20 | INTO-CPS: An well-founded integrated tool chain for comprehensive Model-Based Design of Cyber-Physical Systems SPEAKER: Peter Gorm Larsen |

10:30 | Effects of Pulsating Flow on Mass Flow Balance and Surge Margin in Parallel Turbocharged Engines SPEAKER: unknown ABSTRACT. The paper extends a mean value model of a parallel turbocharged internal combustion engine with a crank angle resolved cylinder model. The result is a 0D engine model that includes the pulsating flow from the intake and exhaust valves. The model captures variations in turbo speed and pressure, and therefore variations in the compressor operating point, during an engine cycle. The model is used to study the effect of the pulsating flow on mass flow balance and surge margin in parallel turbocharged engines, where two compressors are connected to a common intake manifold. This configuration is harder to control compared to single turbocharged systems, since the compressors interact and can work against each other, resulting in co-surge. Even with equal average compressor speed and flow, the engine pulsations introduce an oscillation in the turbo speeds and mass flow over the engine cycle. This simulation study use the developed model to investigates how the engine pulsations effect the in cycle variation in compressor operating point and the sensitivity to co-surge. It also shows how a short circuit pipe between the two exhaust manifolds could increase surge margin at the expense of less available turbine energy. |

10:55 | Simulation of improved absorption configurations for CO2 capture SPEAKER: unknown ABSTRACT. The most well-known technology for post combustion CO2 capture from exhaust gas is absorption in an amine-based solvent followed by desorption. The drawback of this method is the high heat consumption required for desorption. Reduction of the energy consumption can be achieved by using alternative configurations. In this work, the standard process, vapour recompression and vapour recompression combined with split-stream configurations have been simulated using Aspen HYSYS version 8.0 for 85% amine-based CO2 removal in search for optimum process. Energy optimisation has also been performed by varying the most important parameters. This study shows that it is possible to reduce energy consumption with both the vapour recompression and the vapour recompression combined with split-stream processes. The vapour recompression process has been calculated to be the energy optimum alternative among the configurations investigated. |

11:20 | Optimal Operation of the Peat Drying Process in Steam Tube Dryers SPEAKER: unknown ABSTRACT. Ukraine is an energy-dependent country and aims to reduce the import of natural gas, heat, and power in general. This implies extracting fuel from her own natural resources; one relevant and readily available energy carrier for such extraction is peat (bio mass). Currently, the operating regimes of the drying of peat are not energy efficient; these operating regime maps were developed in the 1970s and aimed only to get dry peat of required quality, without taking into account the cost of heat and electric energy in the drying process. The current quality of dried peat in the dryer does not always satisfy the necessary quality; e.g. parts of the peat may be insufficiently dried, or it may be over-dried. This affects the energy performance of peat briquette production. To improve the quality and energy efficiency of the peat drying process, an analysis of the drying process is carried out: an empirical mathematical model of the drying process is developed using the GMDH principle [1, 2, 3], mapping input parameters and disturbances to output qualities based on available experimental data. Next, with known (measured) disturbances, optimal input parameters for the drying process are found. Changing the operational parameters too fast leads to insufficient drying or over-drying of parts of the peat. Thus, to avoid changing the operational conditions too fast, the operational conditions are classified into a number of classes corresponding to a certain range of values for the operational parameters. Finally, an iterative procedure for changing the input parameters from the past values to new values is introduced. The resulting algorithm for finding the optimal operation of peat drying is based on mathematical models developed from experimental data, and aims to ensure improved quality and energy efficiency in the peat drying process. Reference [1] Ivakhnenko, A.G. (1971). “Polynomial Theory of Complex Systems”. IEEE Transactions on Systems, Man, and Cybernetics. Vol. SMC-1, No. 4, October 1971, pp. 364-378. [2] Farlow, S.J. (1981). “The GMDH Algorithm of Ivakhnenko”. The American Statistician, Vol. 35, No. 4 (Nov. 1981), pp. 210-215. [3] Anastasakis, L., and Mort, N. (2001). “The Development of Self-organization Techniques in Modelling: a Review of the Group Method of Data Handling (GMDH)”. Research Report No. 813, October 2001, Department of Automatic Control & Systems Engineering, The University of Sheffield, UK. |

11:45 | Improving the Mathematical Formulas for Identification of Bitumen's Viscoelastic Properties at Large Shear Strains SPEAKER: Magnus Komperød ABSTRACT. Bitumen is used as anticorrosion to protect steel armor wires of subsea cables and umbilicals. Because bitumen's viscoelastic behavior influences the mechanical properties of cables, it is desirable to include bitumen in mechanical cable analyses. For this purpose, the author and his colleagues have in a previous scientific paper presented a newly developed laboratory instrument for identification of bitumen's viscoelastic properties. The present paper derives an improved mathematical model for how to establish bitumen's viscoelastic properties from the sensor measurements of the laboratory instrument. It is proved mathematically that the model of the previous paper and the model of the present paper give identical results when bitumen has shear modulus of small magnitude. The difference between the two models grows with increasing magnitude. |

13:30 | A Framework for Early and Approximate Uncertainty Quantification of Large System Simulation Models SPEAKER: unknown ABSTRACT. Uncertainty Quantification (UQ) is vital to ensure credibility in simulation results and to justify model-based design decisions – especially in early development phases when system level measurement data for traditional model validation purposes are scarce. Central UQ challenges in industrial applications are computational cost and availability of information and resources for uncertainty characterization. In an attempt to meet these challenges, this paper proposes a framework for early and approximate UQ intended for large simulation models of dynamical systems. A Modelica simulation model of an aircraft environmental control system including a liquid cooling circuit is used to evaluate the industrial applicability of the proposed framework. |

13:55 | Modelica Classes of the Norwegian Grid for iTesla and Software-to-Software Validation SPEAKER: unknown ABSTRACT. This paper summarizes the continuation of the work performed in one of the work-package of the FP7 \textit{\textbf{i}Tesla} project. This work consisted in the development of power system component models of PSS/E models in Modelica. The PSS/E models selected for this work are used in different dynamic models of the Norwegian grid. The development of the Modelica models was done in progressive stages to validate all the models. The performance of the Modelica models was validated by comparing several simple grid models that were implemented in both PSS/E and Modelica. The grid models were built to integrate different kinds of perturbation to accurately validate the models. |

14:20 | Learning Modelica Models from Component Libraries SPEAKER: Gregory Provan ABSTRACT. The Modelica language is one of the most important languages for representing a large class of systems, ranging from vehicles to climate control systems in buildings. Component libraries, containing components like valves, motors, pumps, etc., have been built to facilitate the construction of complex systems, but at present model construction and parameter estimation are entirely manual. We have developed software for (i) automating the process of constructing models that optimise a range of metrics (e.g., model-simulation accuracy or diagnostics accuracy), and (ii) dynamically updating the model parameters due to dynamic changes in the observed data and/or health status of the modelled system. We assume that in these component libraries a component may be modeled at multiple levels of fidelity, e.g., as a non-linear system (high-fidelity model), linear system, or a qualitative system (low-fidelity model). Choosing the right component model for system simulation is a difficult task and requires a search in the space of all possible component type combinations. In this paper we propose a method that automates this task and computes a system model that optimizes a set of metrics in a set of simulation scenarios. We describe initial experimental results showing the trade-offs of accuracy and inference time. This software has the potential to revolutionise how industry uses Modelica, i.e., changing the use from an expensive manual process to a fully automated process that is adaptive to changing external conditions. |

14:45 | A Software Architecture for Simulation and Visualisation based on the Functional Mock-up Interface and Web Technologies SPEAKER: unknown ABSTRACT. This paper presents a software architecture for a collaborative virtual environment (CVE) for simulation and visualisation based on the Functional Mock-up Interface (FMI) for co-simulation and web technologies. FMI has been chosen in order to have a standardised and independent interface to models created in different modelling tools. The user interface has been implemented using web technologies, which enables a very high degree of flexibility. The Web Graphics Library (WebGL) is used for interactive 3D visualisations, enabling native cross-platform rendering directly in the browser without the need of installing any additional plug-ins. Employing the bi-directional communication capabilities of the WebSocket protocol, multiple users can interact with the same simulation models simultaneously. A software prototype has been developed in order to demonstrate the applicability of the proposed architecture. As a case study, we have considered virtual prototyping of marine cranes, to illustrate the use on real world problems. |

15:30 | Recursive dynamic modelling in changing operating conditions SPEAKER: Esko Juuso ABSTRACT. Changing operating condition may require updates for the dynamic models. Recursive updates are needed when there are not sufficient information about the new situations. In machine diagnostics and prognostics, the analysis starts from good conditions and new phenomena, which activate with time, may change considerably the model. In biological wastewater treatment processes, the condition of the biomass changes drastically the dynamic operation of the treatment process. Direct measurements of the biomass condition are under development. Recursive modelling is clearly needed in these situations. The usual approachis to modify the model equations. However, the interactions do not necessarily change if the meanings of the variables are modified. This paper keeps the the model equations constant and modifies the nonlinear scaling of the variables by extending the data-driven scaling to recursive approach. The recursive methodology is tested in two applications: machine diagnostics and wastewater treatment. |

15:55 | Robust Simulation for Hybrid Systems: Chattering Bath Avoidance. SPEAKER: unknown ABSTRACT. The sliding mode approach is recognized as an efficient tool for treating the chattering behavior in hybrid systems. However, the amplitude of chattering, by its nature, is proportional to magnitude of discontinuous control. A possible scenario is that the solution trajectories may successively enter and exit as well as slide on switching manifolds of different dimension. Naturally, this arises in dynamical systems and control applications whenever there are multiple discontinuous control variables. The main aim of this paper is to provide a robust computational framework for the most general way to extend a flow map on the intersection of p transversally intersected (n-1)-dimensional switching manifolds in at least p dimensions for any finite (positive) integer p. We explore a new formulation to which we can define unique solutions for such particular behavior in hybrid systems. We illustrate the concepts with examples throughout the paper. |

16:20 | Job-Scheduling of Distributed Simulation-Based Optimization with Support for Multi-Level Parallelism SPEAKER: unknown ABSTRACT. In many organizations the utilization of available computer power is very low. If it could be harnessed for parallel simulation and optimization, valuable time could be saved. A framework monitoring available computer resources and running distributed simulations is proposed. Users build their models locally, and then let a job scheduler determine how the simulation work should be divided among remote computers providing simulation services. Typical applications include sensitivity analysis, co-simulation and design optimization. The latter is used to demonstrate the framework. Optimizations can be parallelized either across the algorithm or across the model. An algorithm for finding the optimal distribution of the different levels of parallelism is proposed. An initial implementation of the framework, using the Hopsan simulation tool, is presented. Three parallel optimization algorithms have been used to verify the method and a thorough examination of their parallel speed-up is included. |

16:45 | Validation Techniques Applied on the Saab Gripen Fighter Environmental Control System Model SPEAKER: unknown ABSTRACT. The Environmental Control System (ECS) of the Saab Gripen fighter provides a number of vital functions, such as provision of coolant air to the avionics, comfort air to the cockpit, and pressurization of the aircraft fuel system. To support system design, a detailed simulation model has been developed in the Modelica-based tool Dymola. The model needs to be a “good system representation”, during both steady-state operation and relevant dynamic events, if reliable predictions are to be made regarding cooling performance, static loads in terms of pressure and temperature, and various other types of system analyses. A framework for semi-automatic validation of the ECS model against measurements is developed and described in this paper. Applied methods for validating the model in steady-state operation and during relevant dynamic events are presented in detail. The developed framework includes automatic filtering of measurement points defined as steady-state operation and visualization techniques applied on validation experiments conducted in the previously mentioned points. The proposed framework both simplify continuous validation throughout the system development process and enables a smooth transition towards a more independent verification and validation process. |