Linköping Electronic Conference Proceedings
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Preface
Get PDFWe are very pleased to introduce the proceedings of the 6th International Conference on Historical Cryptology (HISTOCRYPT 2023), held at the Deutsches Museum in Munich, Germany from June 20–22, 2023
A Playground for the Modelica Language
Get PDFThis paper introduces a Modelica playground which allows users to experiment with the Modelica language without having to install any specific Modelica tools. This web-based application also contains content and lessons that provide users with a guided tour of the language and the opportunity for advanced users to create domain specific content built on top of this same infrastructure. This paper will explain the various open source technologies employed in creating this application and discuss potential future work to further enhance the experience for the user as well as the reach for Modelica itself
Fast Charge Algorithm Development for Battery Packs under Electrochemical and Thermal Constraints with JModelica.org
Get PDFStrict operating boundaries on commercial lithium ion cells are defined to mitigate the effect of aging (loss of capacity and increase in internal resistance), as well as avoiding safety hazards, like the appearance of lithium plating during charge, which can lead to internal short circuit and subsequent thermal runnaway. Therefore, to develop fast charge algorithms that maximize charging speeds, electrochemical and thermal constraints must be considered. Most studies so far have focused on the single cell problem, whereas pack-level fast charge challenge has been tackled directly by the industry. The reason is that the temperature difference between cells within a battery pack is often considered small, and therefore that optimal charging profiles can be extrapolated from single cell investigations. In practice, temperature spread can reach up to 10 K from coldest to warmest points in the pack, and at least 5 K between same position of different cells. With this in mind, a Nonlinear Model Predictive Control (NLMPC) scheme is proposed that considers both electrochemical and thermal constraints at pack level, establishing, at least on a theoretical basis, the practical limits of fast charge. We demonstrate how active thermal management, i.e., controlling the fluid inlet temperature, is critical to reducing charging times below 40 min (from 0% to 80% state of charge), and discuss some challenges when using online optimization-based control technique
Testing the verification and validation capability of a DCP based interface for distributed real-time applications
Get PDFCyber-physical systems are composed of a variety of elements developed by different vendors that are often geographically distributed. Therefore, its development process presents a double challenge: each element has to be developed individually and, at the same time, a correct interaction with the rest of the elements has to be ensured. In a previous work, we proposed and developed an interface, based on the non-proprietary Distributed Co-simulation Protocol standard, to ease the interaction between these elements. In this paper, we improve it to be applicable in a variety of hardware platforms and we test its applicability for the verification and validation process. To do so, firstly, we prove that our interface is hardware agnostic, demonstrating its easy implementation on different platforms. Secondly, we test its applicability in different X-in-the-Loop simulations. Finally, we also test its behaviour in distributed real-time executions, a necessary requirement for linking elements from different suppliers and helping to preserve their Intellectual Property
Steady State and Dynamic Simulation of a Small-Scale Hollow Fiber Membrane Humidifier
Get PDFMembrane humidifiers are often used in mobile Proton Exchange Membrane (PEM) fuel cell systems to humidify the supply air of the fuel cell. The purpose of a humidifier in a PEM fuel cell system is to prevent a dry-out of the fuel cell membrane. In this paper, a humidifier model based on the number of transfer units (NTU) approach is set-up in Modelica, calibrated and validated using measurement of a test rig. In a first step, the model is evaluated for steady state operating conditions. Second the developed membrane humidifier model is simulated with dynamically changing operating conditions that are typical for mobile applications. Those simulation results are then compared to measurements. The aim of our study is to evaluate the accuracy of the NTU humidifier model under various operating scenarios. Our results indicate that the NTU model is suitable to predict the water transfer under steady state as well as dynamically changing operating conditions with low deviations to measurements
MultiGED-2023 shared task at NLP4CALL: Multilingual Grammatical Error Detection
Get PDFThis paper reports on the NLP4CALL shared task on Multilingual Grammatical Error Detection (MultiGED-2023), which included five languages: Czech, English, German, Italian and Swedish. It is the first shared task organized by the Computational SLA1 working group, whose aim is to promote less represented languages in the fields of Grammatical Error Detection and Correction, and other related fields. The MultiGED datasets have been produced based on second language (L2) learner corpora for each particular language. In this paper we introduce the task as a whole, elaborate on the dataset generation process and the design choices made to obtain MultiGED datasets, provide details of the evaluation metrics and CodaLab setup. We further briefly describe the systems used by participants and report the results
Two Neural Models for Multilingual Grammatical Error Detection
Get PDFThis paper presents two neural models for multilingual grammatical error detection and their results in the MultiGED-2023 shared task. The first model uses a simple, purely supervised character-based approach. The second model uses a large language model which is pretrained on 100 different languages and fine-tuned on the provided datasets of the shared task. Despite simple approaches, the two systems achieved promising results. One system has the second best F-score; the other is in the top four of participating systems
Heat Demand Modelling for a Sustainable Urban Development Project: A Case Study of Kopparlunden in Västerås, Sweden.
Get PDFAs cities grow and develop, urban planners face an increasing challenge to create more sustainable and environment friendly communities. The Kopparlunden district in Västerås, Sweden, is no exception, with plans underway to transition the area to a more sustainable neighborhood. To assist this effort, this paper presents a simple grey box modeling approach to predict the heat demand of eight buildings in the area. As the city transforms from a historical industrial district to a mixed district with residential buildings, shops, and offices, the model will allow urban planners to predict their new heat demand. The model is calibrated using a genetic algorithm, then validated using real historical data. The results show a good accuracy of the model and highlight the importance of increasing the insulation efficiency of the walls in the modelled buildings. The model can be used to predict the heat demand variations, with minimum error of 2.49 kW and up to 16.6 kW for large buildings. The model highlights the importance of energy modeling for urban development projects and shows its significance as a tool to aid in decision-making towards sustainable and more efficient urban areas
The Effect of Climate and Orientation on the Energy Performance of a Prefab House in Norway
Get PDFNorway has a wide range of climatic conditions throughout the country. The climate varies from coastal to inland areas. Geographic latitude and longitude, as well as the gulf stream oceanic flow, account for this phenomenon. Different climate types can certainly affect residential building heating energy demands and make overheating more likely. On the other hand, a building's orientation has an impact on its heating energy requirements. A building's orientation affects how much solar gain it receives and how much wind it receives over the course of the year. Employing DesignBuilder® software, This study examines how different orientations affect the energy performance of a pre-designed house with and without solar photovoltaic panels in typical Norwegian climates. The results confirm that in different locations, the optimal situation is South-East and the lowest energy consumption without and with photovoltaic panels belongs to Bergen with 83305 Wh/m2 and Oslo with 29442 Wh/m2 respectively. This comparative study will be helpful to stakeholders in the building ecosystem (municipalities, engineers, and designers, building companies, suppliers, and residents) in making more informed decisions
A Python-based code for modeling the thermodynamics of the vapor compression cycle applied to residential heat pumps
Get PDFHeat pumps are an attractive heating system in residential buildings. They operate based on the vapor compression cycle used in refrigeration systems. Design questions surrounding heat pumps can be investigated and answered using modelling tools that incorporate the necessary thermodynamics, fluid mechanics, and machinery component efficiency. Several modelling tools are available, however there is a need for more open-source, script-based programs that are competitive to those already available. This work presents a Python-based code for modeling the thermodynamics of the vapor compression cycle (VCC) in typical heat pumps. The main contribution of this work is an openly available online code, complete with a few examples to show its functionality, that provides the basic thermodynamic model of a heat pump for researchers or development engineers to use, modify, and extend. Its current features include choice of refrigerant, heat exchanger size and characteristics, compressor, and other design parameters such as heating load, and fluid temperatures in and out of the heat exchangers. Simulation outputs include the P-h and T-s diagrams and coefficient of performance (COP). The code is flexible and suggestions for future code development are given