Linköping Electronic Conference Proceedings
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The first volume of the Venetian ciphers written by Agostino Amadi
Get PDFThe secret manuscript of Agostino Amadi contains hundreds of cipher methods and examples. The total manuscript in ten volumes is translated from old Italian into English and published for the first time since 1588. Some examples from the first volume are presented here
Applying Design of Experiments Method for the Verification of a Hydropower System
Get PDFToday, renewable energy plays a major role in the transition towards environment-friendly energy sources. Hydropower is one of the most important renewable energy sources leading to the high interest of research associated with the development of new technologies. These technologies aim to examine and predict the characteristics and behaviour of hydropower plants during different operating conditions and are often associated with simulation models. In the progress of creating accurate simulation models, it is necessary to have an organised and systematic method to verify and optimise the model with the help of available data. This is where the “Design of Experiments” (DoE) principles should be applied.
A simulation model of a reference hydropower plant located in Seljord municipality in the south-east of Norway was implemented using the modelling language Modelica. All parts of this hydropower plant model were tuned according to DoE procedure with the purpose of design verification and optimisation. The results of the experiments are a complete and optimised hydropower plant model that gives reliable simulation results
Efficient Global Multi Parameter Calibration for Complex System Models Using Machine-Learning Surrogates
Get PDFIn this work, we adress challenges associated with multi parameter calibration of complex system models of high computational expense. We propose to replace the Modelica Model for screening of parameter space by a computational effective Machine-Learning Surrogate, followed by a polishing with a gradient-based optimizer coupled to the Modelica Model. Our results show the superiority of this approach compared to common-used optimization strategies. We can resign on determining initial optimization values while using a small number of Modelica model calls, paving the path towards efficient global optimization. The Machine Learning Surrogate, namely a Physics Enhanced Latent Space Variational Autoencoder (PELS-VAE), is able to capture the impact of most influential parameters on small training sets and delivers sufficiently good starting values to the gradient-based optimizer. In order to make this paper self-contained, we give a sound overview to the necessary theory, namely Global Sensitivity Analysis with Sobol Indices and Variational Autoencoders
Introducing Dialectic Mechanics
Get PDFThis paper introduces a new method for mechanical systems with its own interface that enables the object-oriented formulation of very stiff contacts. It thereby suppresses high frequencies and yields stable replacement dynamics leading to an equivalent steady state. Potential applications are the efficient modeling and simulation of robotic manipulation or the easier handling of what formerly have been variable-structure systems
Hybrid data driven/thermal simulation model for comfort assessment
Get PDFMachine learning models improve the speed and quality of physical models. However, they require a large amount of data, which is often difficult and costly to acquire. Predicting thermal comfort, for example, requires a controlled environment, with participants presenting various characteristics (age, gender, ...). This paper proposes a method for hybridizing real data with simulated data for thermal comfort prediction. The simulations are performed using Modelica Language. A benchmarking study is realized to compare different machine learning methods. Obtained results look very promising with an F1 score of 0.999 obtained using the random forest model
Object-Oriented Formulation and Simulation of Models using Linear Implicit Equilibrium Dynamics
Get PDFNew robust and yet powerful Modelica libraries as the DLR ThermoFluid Stream library or the introduction of dialectic mechanics use a special modeling approach that uses linear implicit equilibrium dynamics. In this paper, we study the basic motivation of this approach, its benefits and drawbacks before finally showing how to get from the models to applicable simulation code
On the Characteristics of One-Dimensional Compressible Flow
Get PDFEigen decomposition of the governing equations that describe one-dimensional compressible flow has been presented. Analytical solution of the characteristics of the flow was derived. Simulation studies were conducted to support the theoretical analyses and wave propagation results were discussed in detail. It was found that acoustic effect due to the dynamic momentum led to a significant slowdown in the simulation and could be neglected in models without significant loss in accuracy for applications where energy transfer is of greater interest
LargeTESModelingToolkit: A Modelica Library for Large-scale Thermal Energy Storage Modeling and Simulation
Get PDFThis paper introduces the LargeTESModelingToolkit, a novel Modelica library for modeling and simulation of large-scale pit and tank thermal energy storage. This first comprehensive Modelica library in the field provides the flexibility and tools needed to develop new storage models tailored to the desired application. It also offers researchers and industrial users pre-built storage models for simulation studies to answer the relevant questions for an optimized design at storage and system level. In this paper we present the library’s key features and structure, and introduce the underlying physical and mathematical foundations and modeling approaches. Moreover, we discuss the validation of the models, present the first results, and show the library’s applicability using an exemplary simulation case study
Creating cardiovascular and respiratory models using Physiolibrary 3.0
Get PDFThe free open-source library called Physiolibrary (https://github.com/MarekMatejak/Physiolibrary) in version 3.0 recast components from physiological domains such as hydraulic (cardiovascular), thermal, osmotic and chemical into Modelica Standard Library (MSL) concept of Fluid/Media. Components are expanded to include gases transports, acid-base, electrolytes, nutrients delivery and endocrines by simple selecting pre-packaged media. They can be connected directly (the same medium) or across membranes (different media), allowing small physiological models to be easily coupled within more quantitative ones with minimal effort
Status of the ClaRa Library: Detailed Transient Simulation of Complex Energy Systems
Get PDFThis paper presents the current state of the open-source Modelica library ClaRa, which provides its users with the capability to proficiently tackle tasks in the disciplines of thermal hydraulics, instrumentation and control pertaining to power plants and other kind of energy systems. We provide a comprehensive overview of how the library has successfully broadened its scope over the years of its development, transcending the original focus on conventional power plants to encompass renewable power plants, waste heat utilization, general process plants, refrigeration cycles, heat pumps and beyond. The new version, ClaRa 1.8.1, brings an exciting addition to the already impressive suite of features - support for the utilization of various artificial intelligence models in Modelica simulation tools. Furthermore, the authors unveil ClaRa's ambition to serve as a potential publication platform for third-party models from a steadily growing community of ClaRa users. This is underscored by several application models. Finally, we also describe the funding scheme for maintenance of open source ClaRa by an extended commercial version, ClaRaPlus