When launching a satellite a separation system is used to keep the satellite attached to a launch vehicle during ascent and to separate it from the launch vehicle while in space. In separation analysis the separation is studied by simulations to see if requirements on the system can be fulfilled. The purpose of this master’s thesis is to investigate if separation analysis can be done using the modeling program OpenModelica and to evaluate OpenModelica and compare it to other modeling programs. OpenModelica is free software implementing the Modelica language, which is an object-oriented language for modeling and simulation of complex physical systems. Modelica uses equation-based modeling, this means that the physical behaviour of a model is described by differential, algebraic and discrete equations and no particular variable needs to be solved manually. The work is divided into two parts. The main part is to implement a mathematical model of a separation system in OpenModelica, simulate it and study the behaviour of the system. A Monte Carlo method, which randomly generates values for uncertain model parameters, is used when simulating the model. The other part of the work is to evaluate OpenModelica and compare it with other modeling programs, such as Matlab/Simulink, C/C++ and JAVA to see advantages and disadvantages with OpenModelica.

Mathematical models possible to simulate are of great importance in order to make successful projects in the aircraft manufacturing industry. An aircraft fuel system is very complex, containing pipes, tanks, orifices, valves and pumps. The principal of this thesis is using the tool Easy5, which no longer is considered reliable enough in terms of development and support. This thesis tries to evaluate the Modelica language as a possible alternative to Easy5. To make this evaluation, the components concerned in the fuel library in Easy5 are implemented to the Modelica language. Small hydraulic systems are built up in Dymola, and verified against Easy5 through simulation with high accuracy. A model of the fuel system of an unmanned aerial vehicle (UAV) is built from the implemented Modelica components to examine how Dymola manage a large model. The simulation made in Dymola was considerably more time efficient than the one made in Easy5, in the range of minutes instead of hours. Thus, much time can be saved if Dymola is used instead of Easy5. Finally, the components in the fuel library handle a two phase flow of fuel and air. Modeling a two phase flow is not trivial and discontinuous mass flow and pressure values are also implemented and discussed. / För att driva framgångsrika projekt inom flygindustrin är det av stor vikt att ha matematiska modeller som kan simuleras. Ett bränslesystem till ett flygplan kan ses som ett komplext system bestående av bl.a. rör, tankar, ventiler och pumpar. För närvarande använder uppdragsgivaren till detta examensarbete modeller till dessa komponenter i verktyget Easy5, vars framtid anses osäker med avseende på nyutveckling och support. Syftet med detta examensarbete är därför att utvärdera modelleringsspråket Modelica som möjligt alternativ till Easy5. För att kunna göra en utvärdering implementeras berörda komponenter i Modelica med utgångspunkt från Easy5s bränslebibliotek. Mindre hydrauliska system skapas i verktyget Dymola, och dessa verifieras mot Easy5 genom simuleringar. Simuleringsresultaten visar på hög överensstämmelse mellan de båda verktygen. För att undersöka hur verktyget Dymola hanterar en stor modell skapas bränslesystemet till ett obemannat flygplan (UAV) utifrån de implementerade Modelicakomponenterna. Resultat tyder på att simuleringstiden kan kortas betydligt om Dymola används gentemot Easy5; storleksordningen minuter istället för timmar. Avslutningsvis hanterar komponenterna i bränslebiblioteket ett massflöde av både bränsle och luft. Att modellera ett 2-fasflöde stöter på vissa simuleringstekniska komplikationer i form av diskontinuerliga massflöden och tryck, vilket visas och diskuteras.

The current OpenModelica Complier (OMC) translates Modelica models into executable Ccodethrough several stages. The Code Generator is the final stage of the compiler whichgenerates target C-code from the optimized sorted equations. Recently, the Code Generator inOMC has been rewritten using the OpenModelica text template language. This gives a moreconcise and easier to understand code generator. Modeling and simulation is becomingincreasingly used in several application areas. There is demand for the OpenModelicaComplier (OMC) to generate code in languages like C#, CSharp, XML, JAVA and so on. Inthis thesis work, we implement a Java code generator to translate the internal equation-basedmodels in OpenModelica and its extension MetaModelica into a Java code representation. Tocreate the Java code generator we used the OpenModelica text template language, also calledSusan. This work is an important step on the way to finalize a full version of a Java CodeGenerator for the OpenModelica Complier (OMC).

Zugl.: Neubiberg, Universiẗat der Bundeswehr München, Diss., 2008.

“OPENMODELICA is an open-source Modelica-based modeling and simulation environment intended for industrial and academic usage. Its long-term development is supported by a non-profit organization – the Open Source Modelica Consortium (OSMC).” OpenModelica aims to provide an enhanced, Open Source Modelica modeling and simulation environment and this thesis is an addition in this direction.  The purpose of this thesis is to create a web based graphical connection editor. There are other open-source connection editors available, but these editors were desktop applications. There is one web based editor but it is a textual editor. Desktop applications need installation and space on the local system. OMWeb connection editor is the first web based graphical connection editor that runs on a web browser. It’s a web platform for OpenModelica and provides the environment for modeling and simulation in the Modelica Modeling Language. The OMWeb connection editor can run on any system without the need for an OpenModelica installation. If a system is connected to the internet, and contains a web browser, it can run the OMWeb connection editor. The OMWeb connection editor uses Java Runtime Environment to run an applet in the browser. The user can create models graphically; but they can also be viewed in the textual format. The user can simulate and plot his models. The plot file generated for the model can be downloaded from the server.  The OMWeb Connection Editor uses Servlet to handle requests from the client. The servlet is responsible for the communication with OpenModelica Compiler. It also gets the results from OMC and sends them back to the client. In our case the browser is the client.

OpenModelica is an open-source based development environment for Modelica coordinated by the Programming Environments Laboratory (PELAB) at Linköpings Universitet. Previously an external tool, PtPlot, has been used to create graphics from simulation data. This tool is poorly integrated with OMNotebook, the OpenModelica Notebook, which is a tool for creating interactive documents where Modelica code can be edited and evaluated. This thesis develops and implements a plotting API accessible from Modelica algorithmic code and extends OMNotebook to allow creation of diagrams and other forms of graphics without an external application.These diagrams are more customizable than those generated by PtPlot and allow for example logarithmic scaling. The new Modelica API for graphic programming allows access of graphic functionality from within Modelica models and Modelica functions.

Simulations are very important for many reasons, and finding ways of accelerating simulations are therefore interesting. In this thesis the feasibility of automatically generating simulation code for a limited set of Modelica models that can be executed on NVIDIAs CUDA architecture is studied. The OpenModelica compiler, an open-source Modelica compiler, was for this purpose extended to generate CUDA code. This thesis presents an overview of the CUDA architecture, and looks at the problems that need to be solved to generate efficient simulation code for this architecture. Methods of finding parallelism in models that can be used on the highly parallel CUDA architecture are shown, and methods of efficiently using the available memory spaces on the architecture are also presented. This thesis shows that it is possible to generate CUDA simulation code for the set of Modelica models that were chosen. It also shows that for models with a large amount of parallelism it is possible to get significant speedups compared with simulation on a normal processor, and a speedup of 4.6 was reached for one of the models used in the thesis. Several suggestions on how the CUDA architecture can be used even more efficiently for Modelica simulations are also given.

In today’s fast paced changing technology world, it is essential to adapt the new technologies and standards in order to stay compliant with the market. Software development is one of those key areas that have been growing highly fast and thus the need for staying up to date needs to be acknowledged by everyone in the area. The technology focused in this project is called ModelicaML[1] which is an integrated system modeling environment based on standardized languages such as UML[2] and Modelica[3]. Modelica Modeling Language (ModelicaML) is a graphical modeling language used for the description of time-continuous and time-discrete/event-based system dynamics. Currently, a ModelicaML code generator – that generates Modelica code from UML models – is implemented using the old Acceleo framework[4]. Within this thesis, the ModelicaML code generator was re-factored and implemented by using the latest Acceleo version 3.X[5]. The differences between the old and new Acceleo framework was also given an evaluation in the study in order to provide a hint of its future use for further improvements of the code generator.

<div>With the United States being the world’s second largest consumer of primary energy, research into areas of significant consumption can provide large impacts in terms of the global energy consumption. Buildings account for 41% of U.S. total energy consumption with the residential sector making up a majority. Household appliances account for the second largest site energy consumption at 27%, after the HVAC system for the U.S. residential sector. Federal appliance standards have been instrumental in improving efficiencies but have been increasing aggressively to where it is unknown what suitable technologies can support this rate of increase. Thermally integrating residential appliances by leveraging waste heat recovery goes outside standards and has not been adequately explored by connecting all residential appliances. Limited studies exist focused only on single appliances connected to waste heat recovery or being thermally integrated. Preliminary modeling on waste heat availability from five major appliances, namely refrigerator-freezer, clothes dryer, clothes washer, dishwasher, and cooking oven was conducted. Conservative estimates predict the total amount of heat recovery to be around 2,000 kWh/year; clothes dryer - 137 kWh/year, clothes washer - 60 kWh/year, 1,500 kWh/year- refrigerator-freezer, 27 kWh/year – dishwasher, and 178 kWh/year – cooking oven. The cooking oven presents technical challenges coupled with safety concerns. The clothes dryer and refrigerator-freezer can deliver useful water temperatures and reduce compressor power consumption, up to 20%. The dishwasher has better opportunity as a heat sink to offset the internal heater, 0.17 kWh of electricity/cycle for heating wash water. The clothes washer drains large volumes of water available for heat recovery and can offset the impact of using high temperature washes with improved wash performance. </div><div>Modelica appliance models have been developed for four of these five appliances. The Modelica models capture individual use and the predictions of the RF and DW were compared against available experimental data. The individual models have been connected to a simple storage tank model to simulate the integrated appliance system. An integrated appliance prototype was designed and fabricated for the collection of experimental data. Comparisons made between the experimental data and the integrated appliance simulation results adjusted the modeling approach and improved agreement with collected data. After tuning, ideal modifications to each appliance are made and reflected in a new integrated model. A parametric study is conducted on ideal improved, thermally capable appliances under a 1-week schedule for two different tank sizes. For 300L and 150 L tank sizes, the appliance total energy for the week is roughly 30.5 kWh compared to a baseline appliance system with no thermal resource sharing at 33.8 kWh. At an electricity cost of $0.15/kWh, the cost savings for the integrated system is a little over $0.40/week. Furthermore, the savings is completely diminished when considering the required auxiliary power to support the exchange of heat between each appliance and storage tank. The impact of tank size should be explored further to identify a critical tank size where the system savings is no longer available. Accounting for all the domestic hot water needs of the home would generate an improved picture where integrated appliances have technical feasibility. </div><div><br></div>

In this thesis we investigate techniques and methods for parallel simulation of equation-based, object-oriented (EOO) Modelica models on graphics processing units (GPUs). Modelica is being developed through an international effort via the Modelica Association. With Modelica it is possible to build computationally heavy models; simulating such models however might take a considerable amount of time. Therefor techniques of utilizing parallel multi-core architectures for simulation are desirable. The goal in this work is mainly automatic parallelization of equation-based models, that is, it is up to the compiler and not the end-user modeler to make sure that code is generated that can efficiently utilize parallel multi-core architectures. Not only the code generation process has to be altered but the accompanying run-time system has to be modified as well. Adding explicit parallel language constructs to Modelica is also discussed to some extent. GPUs can be used to do general purpose scientific and engineering computing. The theoretical processing power of GPUs has surpassed that of CPUs due to the highly parallel structure of GPUs. GPUs are, however, only good at solving certain problems of data-parallel nature. In this thesis we relate several contributions, by the author and co-workers, to each other. We conclude that the massively parallel GPU architectures are currently only suitable for a limited set of Modelica models. This might change with future GPU generations. CUDA for instance, the main software platform used in the thesis for general purpose computing on graphics processing units (GPGPU), is changing rapidly and more features are being added such as recursion, function pointers, C++ templates, etc.; however the underlying hardware architecture is still optimized for data-parallelism.