Linköping Electronic Conference Proceedings
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Deciphering Secrets Throughout History: An Interdisciplinary Linguistics and Cryptology Course
Get PDFThis paper describes an interdisciplinary approach to teaching a linguistics and cryptology course. The authors, a Classics professor and a Mathematics professor, co-taught a three-week course, entitled “Deciphering Secrets Throughout History,” to undergraduate students of varying backgrounds in mathematics and the humanities. Students were taught to apply tools from linguistics, statistics, and cryptanalysis to examine ancient texts, languages, and ciphers. The course culminated in an extended analysis of the fifteenth-century Voynich Manuscript, where students proposed their own original analyses of the text
Simulating Cryptologic History
Get PDFTeaching the history of cryptology depends on access to extant devices, not just their documentation and interpretation. Yet the devices that show major steps in the history of cryptology are rare. Replicas, emulators, and simulations are pivotal for the history of cryptology
Guidelines and Use Cases for Power Systems Dynamic Modeling and Model Verification using Modelica and OpenIPSL
Get PDFThis paper offers systematic guidelines for modeling power systems components in the phasor time-domain using the Modelica language and their verification. It aims to share the authors’ experience in power system modeling with Modelica and the approaches used to meet the high expectations of the power industry w.r.t. to the models’ simulation results. While the modeling guidelines are generic, the verification procedure includes the validation against a domain-specific commercial software tool called PSS®E that is the de facto tool used for power system transmission planning and analysis. To formalize the proposed approaches, a schematic description of the processes of model implementation and validation is elicited through flowcharts. Challenging use cases are presented to point out some of the major difficulties that can be faced in the modeling steps because of unclear or missing documentation of the models’ dynamics in the reference tool. Finally, unique features of the Modelica language that allow for power system modeling and verification unavailable in traditional tools are illustrated
Development of a novel quasi-2D PEM Electrolyzer Model in Modelica
Get PDFTo increase the efficiency of PEM electrolysis, simulation models are required that accurately describe the system's electrochemical and thermal behavior in a computationally efficient manner and are thus suitable for developing control strategies. Therefore, a pseudo-2D PEM electrolyzer model is presented in this paper, which is a compromise between the previously developed models regarding their model complexity. The electrochemical behavior is described with equations commonly used in the literature and the thermal behavior with correlations for gas-liquid heat transfer. Preliminary validation indicates that the model can describe the electrochemical behavior and thermal dynamics of a PEM electrolysis stack with good accuracy
Distributed Parameter Pneumatics
Get PDFPneumatics is a branch of engineering that deals with the use of pressurized air or gases to create mechanical motion. It involves the study and application of systems and components such as air compressors, valves, cylinders, and actuators to control and transmit power through the use of compressed air. For highly dynamic events in pneumatic systems, such as fast switching processes in automation technology, lumped-parameter simulation is not sufficient to correctly calculate the pressure build-up in pipes. The propagation and reflections of different pressure waves and refraction waves cannot be accounted for by the zero-dimensional models provided by the Modelica.Fluid library. Therefore, a method for calculating such events using the finite volume method is presented in this paper. The library presented in this work, uses Gudonov's scheme and an arbitrary Riemann-solver and gas model to calculate the time evolution inside 1D or 2D discretized pneumatic components as well as systems composed of these components
Modeling and simulation of dynamically constrained objects for limited structurally variable systems in Modelica
Get PDFThis work introduces a new solution for the modeling and simulation of dynamically constrained objects for limited structurally variable systems purely in Modelica. A combination of a collision detection algorithm, the limitation of collisions, and a method to constrain objects based on forces leads to a constraint network in Modelica. It allows a stable and accurate simulation of applications such as robot tool changers in a flexible way without the need for predefined connections in the model
HVAC and Control Templates for the Modelica Buildings Library
Get PDFThis article reports on our experience in creating Modelica models for systems with thousands of configurations and closed-loop controls. The development of such templates required exploration of class parameterization techniques and data structures for handling large sets of equipment parameters. By describing these issues and the approach taken, we show how the Modelica language can support advanced templating logic. The main limitation we encountered relates to parameter assignment and propagation. The interpretation of parameter attributes at user interface runtime, or the handling of non-trivial constructs involving record classes at compile time is not consistently supported by Modelica tools. This leads to choices that are difficult to make when looking for a generic implementation
Dialectic Mechanics: Extension for Real-Time Simulation
Get PDFDialectic mechanics was introduced as an approximative modeling alternative to the classic Newtonian formulation of mechanics. It allows for additional freedom in placing a systems eigenvalues to facilitate simulation of systems, that are not suitable for most integration methods, when modeled according to the classic approach. The original idea of dialectic mechanics enables the suppression of high frequencies, but may still yield very stiff systems unsuitable for explicit integration methods. An additional term is added to enable real-time simulation with explicit methods. The goal of this paper is an analysis of the resulting equations and a comparison to the classic Newtonian formulation, aiming for an understanding of which applications most benefit from using dialectic mechanics
Exploiting Modelica and the OpenIPSL for University Campus Microgrid Model Development
Get PDFThe need for modeling different aspects of microgrid design and operation has seen the development of various tools over time for different analysis purposes. In this study, Modelica has been adopted as the language of choice to construct a University Campus Microgrid model, utilizing the Modelica Standard Library and the OpenIPSL library. This paper explores the advantages of utilizing Modelica for campus microgrid modeling, emphasizing its benefits and unique features. Modelica features, such as the use of record structures and replaceable templates prove to be particularly advantageous for the modeling task, enabling flexibility and efficiency in the modeling process. Furthermore, comprehensive validation tests are conducted to ensure the accuracy and reliability of sub-systems (e.g. specific power generator systems), before assembling the microgrid network model as a whole. The results demonstrate the efficacy of Modelica in accurately modeling and simulating microgrids, highlighting its potential for advancing microgrid research and development
Low-order aquifer thermal energy storage model for geothermal system simulation
Get PDFThis paper presents a low order aquifer thermal energy storage (ATES) model for simulation of combined subsurface and above-surface energy systems. The model is included in the Modelica IBPSA Library, which is a free open-source library with basic models for building and district energy and control systems. The model uses a lumped-component method, in which the transient conductive-convective heat and mass transfer equation is radially discretized. To verify the accuracy of the model, we present an intra-model comparison from a simulation test suite. Results show that the Modelica ATES model is in good agreement, with a normalized mean bias error for yearly variation of aquifer temperatures of 1.6×10−2 and 9×10−5 at 1 m and 10 m distance from the well