Linköping Electronic Conference Proceedings
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Convolutional Neural Network for Detection and Quantification of Pilot-Induced Oscillations
Full text linkPilot-induced oscillations (PIO) are a long-standing challenge in aircraft handling, characterized by destabilizing oscillatory behaviour resulting from closed-loop interactions between the pilot and the aircraft. Traditionally, PIO identification and quantification rely on the subjective PIO Rating Scale (PIOR), used by pilots during handling qualities evaluations in aircraft testing and certification. This paper presents a data-driven approach to objectively identify PIO using flight data collected from a fixed-base simulator during a flight test campaign. The data were labelled according to the PIOR scale, preprocessed using the Wavelet Transform, and used to train a Convolutional Neural Network (CNN). This approach enables objective detection and quantification of PIO while maintaining alignment with the pilot-assessed evaluative framework. A k-fold cross-validation strategy yielded an average validation accuracy of 52.8\%, with the best-performing model achieving 63.1\%. The reduced overall accuracy is attributed to challenges in classifying low-to-intermediate PIO ratings (PIOR 2 and 3). Despite this limitation, the proposed model shows potential for further improvement and demonstrates promise as a complementary tool in handling qualities evaluations, providing a quantitative counterpart to traditional pilot assessments
Steady State and Transient Modelling of A Three-Core Once-Through Steam Generator
Full text linkTo reduce emissions and save fuel in offshore power production using gas turbines, one can use the gas turbine exhaust as a heat source for a bottoming cycle for heat and power production. This can replace about one in four gas turbines. In offshore applications weight and size become more important and thus a once-through steam generator (OTSG) is a way to achieve low weight for the bottoming cycle. To reduce the size and weight of the OTSG further, one can reduce the tube diameter in the tube bundles. In this work a three-core OTSG, representing the economizer, evaporator, and superheater, was modelled and the design optimized to achieve minimum weight, while producing a certain amount of power and keeping within constraints of flue gas and steam pressure losses. This was done for varying tube diameters in each of the cores, in steady state. Afterwards transient simulations were performed for each optimized design to find their response times to a step change in the gas turbine load. The evaporator has the biggest impact on both the weight and the response time, while the superheater and economizer had similar and smaller impacts on both the weight and response time
An Enhanced Federated Content Search Infrastructure for the Humanities and Social Sciences
Full text linkThe general idea and implementation of a federated search infrastructure component that allows querying both full text resources and their linguistic annotations is a prominent part of the CLARIN project and is closely interconnected with the other components of its decentralised European-scale research data infrastructure. Since its beginnings, the Federated Content Search (FCS) has been continuously improved and by now fulfils its original goals that were formulated more than 12 years ago. During the last years, development of the FCS has accelerated massively with newly formulated application scenarios, newly opened up user groups and newly developed tools and user interfaces. This paper gives a summary of the developments of recent years and the topics that are currently being worked on. In addition to the further development of existing modules, this includes in particular the consideration and implementation of new requirements reflecting a rapidly evolving research infrastructure landscape
Choosing the Right Tool for You: Informed Evaluation of Text Analysis Tools
Full text linkNatural Language Processing (NLP) research showcases many promising tools and methods for text analysis. Scholars from diverse fields who want to use NLP for their research are confronted with a wide availability of ready-to-use models that claim excellent performance on standard benchmarks. Consequently, choosing an appropriate tool has become a task on its own. Our goal is to exemplify a methodology that stimulates critical evaluation and detailed analysis of automatic outputs of NLP tools. Particularly, we analyze the case of choosing the best Named Entity Recognition (NER) tool for a corpus of Dutch biographies. Our use case is an example of how to make informed decisions by considering different aspects of custom datasets at the instance and aggregated levels, improving the outcomes of the original research question
CLARIN.SI, the Slovenian node of CLARIN: ten years on
Full text linkThe paper presents the organisation and services offered by the Slovenian research infrastructure for language resources and technologies CLARIN.SI. We introduce the governance, organisational structure, and technical components of the infrastructure, followed by a description of its web applications with a focus on the repository and concordancers. Next, we provide an overview of support activities offered by CLARIN.SI, which includes services of the CLASSLA knowledge centre for processing South Slavic languages, financial support for projects, and facilitation of conferences and workshops. We also present the involvement of CLARIN.SI in national and European projects, with its sister national infrastructure nodes of DARIAH and CESSDA, and in the work of CLARIN ERIC
The Value of Enforcing a Strict Modeling Methodology within Modelica
Full text linkSelf-restriction to a certain modeling style can enable themodeling of large-scale systems and the robust modeling ofcomplex system architectures. This paper discusses how sucha self-restriction can be achieved within the Modelicalanguage and provides a corresponding example
Resizable Arrays in Object-Oriented Modeling
Full text linkThe Modelica language (Modelica.org) makes it easy to buildlarge, complex models by allowing the instantiation ofreusable component models. Modelica tools typically expandarrays of variables, equations and components and performsymbolic transformations on the scalar elements. Thisreduces the efficiency of the translation process and makesit difficult to change array dimensions after translation.Scalarization can be avoided by imposing certainrestrictions on the way models are written. This paperdescribes such restrictions, and the algorithms needed tobe applied during the translation. As a result, arrays areresizable after translation and also during simulation.Several examples demonstrate the approach with the Web AppModiator. As a side effect, it is also shown how to providemeaningful diagnostics for erroneous models
OpenIWPI: Open-Instance Wave-Phasor Interface Library for Power System Simulation Studies in Modelica
Full text linkIn the past decades, a large number of power electronicconverter-based energy resources have been connected togrids around the world. The increasing number of suchdevices is pushing for both electromechanical andelectromagnetic dynamic simulations to be part of routinestability studies for transmission planning studies. Hybridwave-phasor simulations have been proposed in theliterature to address this challenge. This paper describesOpen-Instance Wave-Phasor Interface (OpenIWPI), a Modelicalibrary used to couple phasor-based and electromagneticpower system models, allowing simulation and linearizationof such hybrid models to be performed altogether. Examplesare presented to describe how the library can be useful inpower system studies
Modelling, Simulation and Validation of thermal propagation for 3D discretized battery cells in Modelica
Full text linkThis publication presents models for dynamic, 3-dimensionalsimulation of the thermal runa-way, thermal propagation andthe electro-thermal behaviour of battery cells. An optionaland replaceable electrical equivalent circuit diagramdescribes the electrical behaviour of the battery cell.Coupled with the 3-dimensional, thermal equivalent circuitdia-gram, consisting of a resistance-capacitance network,the thermo-electric behaviour is repre-sented. A specialfeature of the battery cell model is the optional,replaceable and physical model of the thermal runaway basedon Arrhe-nius equations and the associated mass loss. Thismeans that either the thermo-electric or the thermalrunaway behaviour or both can be simulated in combinationif required. The ani-sotropic thermal conductivity of thebattery cell and the modelling of relevant heat conductionpaths, such as the path across the housing of the batterycell, is made possible by 3D dis-cretization of the batterycell
Zero-Shot Parameter Estimation of Modelica Models using Patch Transformer Networks
Full text linkThis paper introduces a transformer-based generativenetwork for rapid parameter estimation of Modelica buildingmodels using simulation data from a Functional Mock-up Unit(FMU). Utilizing the \texttt{MixedAirCO2} model from theModelica Buildings library, we simulate a single-zonemixed-air volume with detailed thermal and \cotwo dynamics.By varying eight physical parameters and randomizingoccupancy profiles across 100 simulated systems, wegenerate a comprehensive dataset. The transformer encoder,informed by room temperature and \cotwo concentrationoutputs, predicts the underlying physical parameters withhigh accuracy and without re-tuning (hence, ``zero-shot'').This approach eliminates the need for iterativeoptimization or can be used to warm-start suchoptimization-based approaches, enabling real-time control,monitoring, and fault detection in FMU-based workflows