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The importance of feature selection in online signature verification

Neural Computing and Applications 2024年 1-13页

作者： Szucs, Cintia Lia Kovari, Bence Department of Automation and Applied Informatics Budapest University of Technology and Economics Budapest Hungary

Handwritten signatures are one of the most commonly used biometrics. Because signatures are widely accepted, their verification is a fundamental problem. Online signature verification applies different electronic devices to capture the signatures, which allow the use of dynamic information, such as the pressure or inclination angle of the pen. Therefore, it is much more challenging to forge online signatures. Further derived features can be defined and calculated based on the captured features. The selection of applied features is a crucial step of signature verification. This work aims to analyse the importance of feature selection by comparing the usability of common derived function features using dynamic time warping (DTW) based and Siamese bidirectional long short-term memory (BiLSTM)-based solutions. This paper comprehensively studies the most common function features and their literature background, presents several feature sets including pairs and triplets, compares their effectiveness using different classification approaches, and presents a DTW-based classifier and four Siamese BiLSTM models using two different loss functions. © The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature 2024.

关键词： Long short-term memory

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Mask R-CNN Outperforms U-Net in Instance Segmentation for Overlapping Cells

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Current Directions in Biomedical Engineering 2023年第1期9卷 335-338页

作者： Rettenberger, Luca Rieken Münke, Friedrich Bruch, Roman Reischl, Markus Institute for Automation and Applied Informatics Karlsruhe Institute of Technology Eggenstein-Leopoldshafen Germany

U-Net is the go-to approach for biomedical segmentation applications. However, it is not designed to segment overlapping objects, a challenge Mask R-CNN has shown to have great potential in. Yet, Mask R-CNN receives little attention in biomedicine. Hence, we evaluate both approaches on a publicly available biomedical dataset. We find that Mask RCNN outperforms U-Net in segmenting overlapping cells and achieves comparable performance if they do not intersect. Our study provides valuable decision support to practitioners in selecting an appropriate method when solving instance segmentation tasks using deep learning, as well as important insights into enhancing the accuracy of such approaches in biomedical image analysis. © 2023 the author(s), published by Walter de Gruyter Berlin/Boston.

关键词： Computer vision

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A Self-adapting Pixel Antenna - Substrate Lens System for Infrared Frequencies

Periodica Polytechnica Electrical Engineering and Computer S...

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Periodica Polytechnica Electrical Engineering and Computer Science 2025年第1期69卷 14-25页

作者： Shubbar, Mustafa Rakos, Balázs Department of Automation and Applied Informatics Faculty of Electrical Engineering and Informatics Budapest University of Technology and Economics Műegyetem rkp. 3. BudapestH-1111 Hungary

In this work, we propose a concentrator lens - antenna arrangement, potentially suitable for infrared sensing and energy harvesting rectenna systems. The structure consists of a pixel antenna, self-adapting for the direction of the incident infrared radiation, and a concentrator lens, both optimized for the mid-infrared spectrum. The silicon substrate lens is situated above the pixel antenna, enabling the concentration of the incident light on the antenna;silicon was chosen due to its transparency in the IR spectrum. We examine how various parameters of the lens, in conjunction with the different states of the pixel antenna, affects the performance of the system. The simulations show that the gain of the arrangement increases considerably in correlation with the radius of the lens. The results suggest that the energy conversion efficiency of infrared rectenna systems can be enhanced by several orders of magnitude with the utilization of the proposed arrangement. © 2025 Budapest University of Technology and Economics. All rights reserved.

关键词： Rectennas

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PIDE: Photovoltaic integration dynamics and efficiency for autonomous control on power distribution grids

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Energy informatics 2025年第1期8卷 1-25页

作者： Demirel, Gökhan Fernengel, Natascha Grafenhorst, Simon Förderer, Kevin Hagenmeyer, Veit Institute for Automation and Applied Informatics Karlsruhe Institute of Technology Hermann-von-Helmholtz-Platz 1 Eggenstein-Leopoldshafen76344 Germany

With a focus on larger rooftop or utility-scale solar systems, there is a lack of research on the potential impact of mini photovoltaic (MPV) systems, often referred to as balcony power plants. This work analyzes the impact of varying concentrations of MPV systems, on the stability and control of low-voltage (LV) grids. We offer a comprehensive technical assessment of MPV within a distribution grid and quantify their effects on power quality, losses, transformer loading, and the performance of other inverter-based voltage-regulation devices. For this purpose, this paper introduces the open-source Python-based framework PIDE (Photovoltaic Integration Dynamics and Efficiency), a tool for simulating the integration of distributed energy resources (DER)s and evaluating their impact on autonomous reactive power control in the distribution grid. Our case studies include a one-year sensitivity analysis based on Monte Carlo simulations, compare distributed and decentralized DER control strategies, and demonstrate the role of autonomous inverters in providing ancillary services. With the growing use of battery energy storage (BES) systems in LV grids for these services, the need for adaptable DER control strategies becomes increasingly evident. Our results show that high MPV penetration increases mean transformer load by up to 3%, line load by 2.5% and total power losses by around 17%. © The Author(s) 2025.

关键词： Sensitivity analysis

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A fuzzy logic approach for economic energy-efficient heat pump operation in thermal building control

A fuzzy logic approach for economic energy-efficient heat pu...

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2024 IEEE PES Innovative Smart Grid Technologies Europe Conference, ISGT EUROPE 2024

作者： Kovačević, Jovana Süß, Anne-Christin Çakmak, Hüseyin K. Hagenmeyer, Veit Karlsruhe Institute of Technology Institute for Automation and Applied Informatics Germany

ISBN: (纸本)9789531842976

Advanced thermal control has great potential to decrease energy consumption in buildings. Thereby, encountering the balance between thermal comfort, and electricity load reduction is a challenge. For this, advanced control systems need to be developed that can respond to external signals such as electricity prices and are robust to different types of buildings to be widely utilized. In this paper, we propose and investigate two fuzzy control systems, an economic-energy-efficient controller and a comfort controller. The comfort controller focuses on thermal comfort, whereas the economic-energy-efficient controller is attentive to electricity prices and the energy efficiency of the heat pump. For the simulation, we use a reduced-order building model identified by measurements of a real-world building. Furthermore, we compare the proposed controllers with a hysteresis controller as a lower benchmark control strategy. Simulation results reveal that an economic-energy-efficient controller can reduce electricity consumption by 14.92% and costs by 18.41 % when compared to a benchmark controller and with mean thermal discomfort of 0.216 °C over an evaluation period of two months. The comfort controller has slightly smaller costs and electricity consumption than the hysteresis one, but less zone temperature fluctuations, enhancing the quality of controlled zone temperature and occupants' comfort. © 2024 IEEE.

关键词： Fuzzy control

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Optimization-based Model Predictive Tube Control for Autonomous Ground Vehicles with Minimal Tuning Parameters

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无人系统（英文） 2023年第1期11卷 93-108页

作者： Adorjan Kovacs Istvan Vajk Department of Automation and Applied Informatics Faculty of Electrical Engineering and InformaticsBudapest University of Technology and EconomicsMegyetem rkp.3H-1111 BudapestHungary

The trajectory planning and tracking problem are critical points of intelligent vehicles concerning their safety and *** these parts are separated,interactions should be made between them,especially when sudden changes and disturbances *** paper presents a method that integrates the two parts using a cascade ***,the proposed method deals with the interaction between the lateral and the longitudinal trajectory based on dynamical *** whole problem is handled using the model predictive method based on online *** system receives the path borders as input and generates the control requests for the actuators on its *** configuration space of the system can be maximized to gain stability by handling the lateral-longitudinal parts and the trajectory planning and tracking in one complex *** main advantage of the proposed approach is that the optimization problem in the predictive method is formulated so that the path and dynamics are considered equality and inequality constraints,and the cost function includes only a physical phenomenon to be minimized without tuning *** evaluation of the proposed algorithm is presented in this paper based on simulation and real-time measurements results.

关键词： Path planning path following autonomous car convex optimization model predictive control internal model control

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Application of Model-Free Control to Reduce the Total Harmonic Distortion of Inverters 8

Application of Model-Free Control to Reduce the Total Harmon...

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8th IEEE Workshop on the Electronic Grid, eGRID 2023

作者： Wachter, Jan Groll, Lutz Hagenmeyer, Veit Institute for Automation and Applied Informatics Karlsruhe Germany

ISBN: (纸本)9798350327007

With the fast rising number of power electronic devices in the electric grid, the harmonic emissions of those devices can lead to significant power quality issues. This is reflected in the recent addition of harmonic stability as one of the grid stability types. The reduction of harmonic emissions is an important task in the development of resilient carbon neutral grids. This paper describes the application of the model-free control concept for grid-Tied inverters as an easily implementable extension for dq0-frame based current control loops, which are often used in cascaded control schemes. The approach incorporates the information contained in the output current derivative. To balance phase-error and measurement noise suppression, the derivative is obtained using an algebraic numerical differentiator. The reduction of the total harmonic distortion (THD) is demonstrated for two use-cases in simulation, in order to show the transferability of the results. Further, measurement data from a hardware implementation of the concept is studied to verify the behavior under real-world conditions. For this, the influence of the tuning parameters is discussed along with limitations of the approach. © 2023 IEEE.

关键词： Power quality

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Vibrational Control for Energy Balancing in Modular Multilevel Converters 65

Vibrational Control for Energy Balancing in Modular Multilev...

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65th IEEE Annual International Scientific Conference on Power and Electrical Engineering of Riga Technical University, RTUCON 2024

作者： Kastner, Adam Groll, Lutz Hagenmeyer, Veit Institute for Automation and Applied Informatics Karlsruhe Institute of Technology Karlsruhe Germany

ISBN: (纸本)9798350365771

In order to balance the stored energy between the branches of a modular multilevel converter, an output-invisible control allocation strategy is used. A vibrational control approach, modeled via higher-order averaging methods, is applied to provide additional input variables that enable controlling the one-period average of all branch energies at the same time. Stability analysis of the linearized control loop including the moving average filter is performed using a delay model approach, for which careful handling of a removable singularity at zero is necessary. A finite-order discrete-time approximation of the delay system is used for optimization of the controller parameters. The potential of the proposed control scheme is demonstrated in simulation. © 2024 IEEE.

关键词： Delay control systems

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Gossen’s first law in the modeling for demand side management: a thorough heat pump case study with deep learning based partial time series data generation

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Energy informatics 2024年第1期7卷 47页

作者： Li, Chang Brecher, Gina Kovačević, Jovana Çakmak, Hüseyin K. Förderer, Kevin Matthes, Jörg Hagenmeyer, Veit Institute for Automation and Applied Informatics Karlsruhe Institute of Technology Hermann-von-Helmholtz-Platz 1 Eggenstein-Leopoldshafen76344 Germany

Gossen’s First Law describes the law of diminishing marginal utility. This paper aims to further verify the proposed hypothesis that Gossen’s First Law also holds in the modeling for Demand Side Management (DSM) with a thorough heat pump case study. The proposed hypothesis states that in general the complexity-utility relationship in the field of DSM modeling could be represented by a diminishing marginal utility curve. On the other hand, in data based modeling, when utilizing a large dataset for validation, the data integrity is critical to the reliability of the results. However, the absence of partial time series data may occur during the measurement due to missing sensors or IT related issues. In this work, an extensive real-world open dataset of a ground source heat pump is utilized for the case study. In the raw data, one key variable namely the flow rate is missing. Thus, three different algorithms based on machine learning and deep learning architectures namely Random Forest (RF), Long Short-Term Memory (LSTM) and Transformer are applied to predict the flow rate by utilizing an open loop forecasting. The raw data are first pre-processed with a time interval of one hour and then used for training, validation and forecast. Furthermore, a modified persistence model as the baseline is also defined. The predicted flow rate using LSTM yields the lowest error of 7.47% nMAE and 10.56% nRMSE respectively. The forecast results are then utilized in the following step of modeling of a heat pump use case. With the introduced quantification method for complexity and a modified version for utility, we further verify the proposed hypothesis with a longer time horizon of 7 days. © The Author(s) 2024.

关键词： Forecasting

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Grid Aware Portfolio Optimization of a Multi-Energy DER

Grid Aware Portfolio Optimization of a Multi-Energy DER

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2024 IEEE Sustainable Power and Energy Conference, iSPEC 2024

作者： Grafenhorst, Simon Demirel, Gökhan Förderer, Kevin Hagenmeyer, Veit Karlsruhe Institute of Technology Institute for Automation and Applied Informatics Karlsruhe Germany

ISBN: (纸本)9798350395075

With the rapid increase in distributed generation and demanding loads such as heat pumps and electric vehicle chargers, the distribution grid is increasingly congested, and devices must be curtailed. In many cases, this can be avoided by installing a flexibility providing Distributed Energy Resource (DER) and considering the congestion of the grid in the planning process of the DER. Although previous studies have examined the design and com-position of DERs, the surrounding electrical grid is often not considered. The present paper extends these studies and shows how the portfolio of a complex multi-energy DER can be designed to be cost-optimal for a specific location i n t he grid while simultaneously providing grid-supporting services. For this purpose, an algorithm is outlined that minimizes the total cost of the D ER, i.e., investment and operation, while relieving the surrounding electrical grid. Two case studies demonstrate the effectiveness of using such a multi-energy DER to reduce line utilization in the distribution system, thereby preventing curtailment of renewable generation at minimal cost. © 2024 IEEE.

关键词： Distributed energy

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