[article-cris] Sähkötekniikan korkeakoulu / ELEC

Permanent URI for this collectionhttps://aaltodoc.aalto.fi/handle/123456789/21538

Browse

Recent Submissions

Now showing 1 - 20 of 4763
  • MMIC Design for Radiometer Receiver at 240 GHz in 0.13 μm SiGe BiCMOS Technology
    (2024) Najmussadat, M.; Tawfik, Y.; Ahamed, R.; Varonen, M.; Parveg, D.; Lamminen, A.; Pursula, P.; Halonen, K. A.I.
     A4 Artikkeli konferenssijulkaisussa
    This paper introduces an MMIC radiometer receiver designed for integration into a 240 GHz radiometer receiver system using a 130-nm SiGe BiCMOS technology. The detector features an on-chip dipole antenna, an SPDT switch, a Low Noise Amplifier (LNA), a mixer, an IF amplifier, and a power detector. The resonator switch exhibits a measured minimum insertion loss of 4.2 dB, maximum isolation of 29 dB, and minimum input and output reflection coefficients of 16 dB and 20 dB, respectively. The LNA utilizes a 5 -stage cascode design, achieving a simulated gain of 28 dB at 240 GHz. The mixer, designed as a single-balanced second harmonic mixer, provides a simulated conversion gain of 0 dB. The IF amplifier, a 3 -stage differential cascode amplifier, can provide a simulated gain of 45 dB at its IF frequency. The power detector is designed using the Meyer topology for a high dynamic range contributing to the chip's ability to enhance radiometer resolution. Additionally, this paper also presents a free-space measurement conducted to verify the radiometer receiver's functionality. In the measurement, with a LO frequency set at 112 GHz, the detector provides an output voltage of 650 mV in response to an IF current of 43 mA, demonstrating its effective performance.
  • Simultaneous Planning of PV and DSTATCOM for Combined Mitigation of Voltage Deviation and Unbalance
    (2025-01-28) Mousa, Hossam H. H.; Mahmoud, Karar; Lehtonen, Matti
     A4 Artikkeli konferenssijulkaisussa
    The increased integration of photovoltaic systems (PVs) and unbalanced loads in low-voltage (LV) distribution systems has negative consequences on the overall performance of the utility grid (UG), resulting in voltage imbalance, power losses, line overheating, and various power quality issues. To enhance the hosting capacity (HC) of such distribution systems for accommodating increased capacities of PVs, the reactive power control (RPC) techniques, such as distribution static compensators (DSTATCOMs) are utilized to regulate voltage profiles and address voltage unbalances. In this regard, this study focuses on coordinating the sizing and placement of PVs and DSTATCOMs to mitigate voltage unbalances and maintain acceptable limits for other power quality metrics, particularly in unbalanced three-phase systems. By accounting for fluctuations in both load demand and solar irradiance, a multi-objective grey wolf optimization (MOGWO) algorithm verifies the planning method within the IEEE 123-bus unbalanced distribution system, employing the co-simulation between MATLAB and OpenDSS platforms. As a result of this proposed planning approach, voltage unbalances, power losses, and voltage deviations are reduced by 21%, 42%, and 23%, respectively, under 100% overloading conditions, alongside a 215% penetration level of PVs. Furthermore, the proposed planning strategy underscores that the combination of PVs and DSTATCOMs can alleviate voltage unbalances, consequently reducing power losses and thermal line overloading effectively.
  • Evaluating an Analog Main Memory Architecture for All-Analog In-Memory Computing Accelerators
    (2024) Adam, Kazybek; Monga, Dipesh; Numan, Omar; Singh, Gaurav; Halonen, Kari; Andraud, Martin
     A4 Artikkeli konferenssijulkaisussa
    Analog in memory Computing (IMC) has emerged as a promising method to accelerate deep neural networks (DNNs) on hardware efficiently. Yet, analog computation typically focuses on the multiply and accumulate operation, while other operations are still being computed digitally. Hence, these mixed-signal IMC cores require extensive use of data converters, which can take a third of the total energy and area consumption. Alternatively, all-analog DNN computation is possible but requires increasingly challenging analog storage solutions, due to noise and leakage of advanced technologies. To enable all-analog DNN acceleration, this work demonstrates a feasible IMC architecture using an efficient analog main memory (AMM) cell. The proposed AMM cell is 42x and 5x more power and area efficient than a baseline analog storage cell. An all-analog architecture using this cell achieves potential efficiency gains of 15x compared with a mixed-signal IMC core using data converters.
  • A Droop-Based Frequency Controller for Parallel Operation of VSCs and SG in Isolated Microgrids
    (2023-01-26) Hafez, Wessam Arafa; Mahmoud, Karar; Ali, Abdelfatah; Shaaban, Mostafa F.; Astero, Poria; Lehtonen, Matti
     A4 Artikkeli konferenssijulkaisussa
    Microgrids are a novel concept for modern power distribution networks that integrate renewable power sources and increase power control capabilities. This system's essential problem is controlling the frequency in island mode. Using the synchronous generator (SG) control approach, the microgrid frequency is more stable due to the inertial features of the SG. In this regard, this paper presents a control algorithm for voltage source converters (VSC)-based distributed generators (DGs), which emulates the principal behavior of synchronous machines and can support inertia to the grid and reduce frequency gradients considering the parallel operation of the SG. The controller is designed based on droop control theory, and a supervisory center controller is implemented to maintain system frequency close to a nominal value of the whole microgrid. The simulation results demonstrate that the system frequency is stabilized even in different and sudden load changes in the island mode where the microgrid is fed by multiple VSC units and a SG. The Simulink model of the system is designed using MATLAB Simulink Software.
  • Percolation-Based Metal−Insulator Transition in Black Phosphorus Field Effect Transistors
    (2023-03-15) Ali, Nasir; Lee, Myeongjin; Ali, Fida; Ngo, Tien Dat; Park, Hyokwang; Shin, Hoseong; YOO, Won Jong
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The existence of a novel phenomenon, such as the metal-insulator transition (MIT) in two-dimensional (2D) systems, affords emerging functional properties that provide new aspects for future electronics and optoelectronics. Here, we report the observation of the MIT in black phosphorus field effect transistors by tuning the carrier density (n) controlled by back-gate bias. We find that the conductivity follows an n dependence as σ(n) ∝ n α with α ∼ 1, which indicates the presence of screened Coulomb impurity scattering at high carrier densities in the temperature range of 10-300 K. As n decreases, the screened Coulomb impurity scattering breaks down, developing strong charge density inhomogeneity leading to a percolation-based transition at the critical carrier density (n C). At low carrier densities (n < n C), the system is in the insulating regime, which is expressed by Mott variable range hopping that demonstrates the role of disorder in the system. In addition, the extracted average values of critical exponent δ are ∼1.29 ± 0.01 and ∼1.14 ± 0.01 for devices A and B, respectively, consistent with the 2D percolation exponent of 4/ 3, confirming the 2D percolation-based MIT in BP devices. Our findings strongly suggest that the 2D MIT observed in BP is a classical percolation-based transition caused by charge inhomogeneity induced by screened Coulomb charge impurity scattering around a transition point controlled by n through back-gate bias.
  • Finite Element Modeling of Induction Machine Coupled with Three-Mass Mechanical System
    (2023) Far, Mehrnaz Farzam; Pippuri-Makelainen, Jenni; Keranen, Janne; Belahcen, Anouar; Laine, Sampo; Viitala, Raine
     A4 Artikkeli konferenssijulkaisussa
    Electrical drivetrains consist of an electrical machine drive connected to a mechanical system. Single-mass models are commonly used in electromechanical finite-element analyses to study various aspects of these drivetrains such as the output torque of the electrical machine or the transient performance. Nevertheless, single-mass models are inherently insufficient for the analysis of torsional vibrations. Higher degree-of-freedom mechanical models should be employed to inspect the behavior of the electric drives connected to flexible torsional systems. This paper presents a comprehensive finite element model of an induction machine coupled with a three-mass lumped-element model. The single-mass and three-mass models are compared in terms of stator current, produced torque, speed, and losses. It is shown that neglecting torsional oscillations results in underestimating the characteristics of electrical machines.
  • Direct DC-Bus Control for Grid-Forming Converters: Towards the Concept of Dual-Voltage-Forming Converters
    (2025) Mourouvin, Rayane; Nurminen, Tuure; Hinkkanen, Marko; Routimo, Mikko
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    A control method for regulating both DC- and AC-side voltages, based on a disturbance observer, is presented. This method provides a voltage-source behavior from the AC-side perspective, a key functionality of grid-forming converters. A dynamic model is derived to develop the control law using feedback linearization. The control method is able to maintain the DC- and AC-side voltages without any cascaded loops. The method is therefore named the dual-voltage forming method to differentiate it from the recent definitions of grid-forming converters. The use of a disturbance observer provides integral action and also inherent synchronization. A transparent current controller is implemented to protect the converter from over-currents. Small-signal stability of the proposed method is studied analytically and design guidelines are drawn from the analysis. Furthermore, the asymmetric behavior of the converter in different operating modes is analytically assessed. The performance of the method is tested in experimental conditions using a 12.5-kVA test setup. The control method exhibits robust performance in both strong and weak grids in terms of DC- bus voltage reference tracking as well as the capacity to survive large external power variations with power-flow direction changes. Moreover, the effect of a grid voltage sag is studied.
  • MIP-Based Electrochemical Sensors in the Detection of Opioids, Benzodiazepines and Psychoactive Compounds
    (2024-10-25) Nekoueian, Khadijeh; Laurila, Tomi
     A3 Kirjan tai muun kokoomateoksen osa
    The introduction of modern molecular imprinting technology into electrochemical sensors has resulted in a new era of smart diagnostic sensors. Molecularly imprinted polymers (MIPs) are a specialized group of polymers engineered to contain precise “artificial receptors” or “artificial antibodies” capable of highly selective recognition of target analytes. Adding this unique molecular recognition property to the advantages of electrochemical sensors has paved the way for developing advanced sensing platforms to selectively interact with a diverse range of target analytes, spanning from small biomolecules to organic macromolecules, even within complicated environments. These electrochemical (bio)sensors have extraordinary sensitivity, allowing them to detect trace concentrations of target analytes, and establishing them as key players in advancing health assessment and ecological surveillance, among other applications. Furthermore, their potential for miniaturization paves the way for the design of lab-on-a-chip, biomedical assays, and wearable sensors. As the advancements in this field continue to progress, the potential for these smart diagnostic assays to revolutionize various industrial sectors becomes increasingly evident. The MIP-based electrochemical sensors hold immense promise for the future, offering unprecedented opportunities for precise, rapid, and accessible diagnostics in diverse scientific domains. This chapter discusses the latest developments in the use of MIP-based electrochemical (bio)sensors for detecting and monitoring opioids and psychoactive compounds, with a focus on biofluids including saliva, urine, sweat and blood as well as synthetic samples and beyond.
  • Architecture of a Feedback System for Human-Machine Interaction in a Collaborative Environment
    (2023) Kolesnikov, Mikhail V.; Blech, Jan Olaf; Atmojo, Udayanto Dwi; Vyatkin, Valeriy; Afanasev, Maxim Ya
     A4 Artikkeli konferenssijulkaisussa
    We present a methodology for measuring and increasing labor productivity using data collection and its analysis for optimizing production task management. Presented socio-cyber-physical system architecture and its technical implementation comprises a decision-making system that is integrated with a collaborative automated manufacturing system. This novel approach enables the implementation of flexible planning of all processes of an employee's work time by dynamically adjusting the environment and applying individual methods of influencing an employee's physical and psychological condition, as well as maintaining the employee's productive and relaxation phases and ensuring smooth transitions between them, using the collected in real-time data. As a result of this work, a system architecture is designed, enabling real-time task scheduling according to the laborer's condition. A description of the structural elements, components, and protocols used is provided. Early work on a prototype system used in the 'Aalto Factory of the Future' laboratory is presented.
  • Evaluation of Printed Coplanar Capacitive Sensors for Reliable Quantification of Fluids in Adult Diaper
    (2024) Tanweer, Muhammad; Gillan, Liam; Sepponen, Raimo; Tanzer, Ihsan Oguz; Halonen, Kari A.
     A4 Artikkeli konferenssijulkaisussa
    Advancements in printed technology have led to the development of economical and sustainable electronic solutions for wearable medical devices in the healthcare sector. Printed capacitive sensors in planar geometry are widely used in the development of smart diapers for detecting urination events, quantifying detection, and quantifying voided volumes. However, factors such as the effect of sodium electrolyte variation, body weight effect on a wet diaper and gravitational effect on wet diapers impair the quantification of voided volume with capacitive sensors. In this study, a printed capacitive sensor for quantifying human body fluids in adult diaper was evaluated to analyze these effects. Silver and carbon inks were used to print the parallel-plate capacitive electrodes on a flexible substrate in a coplanar geometry. In-diaper quantification measurements were performed at various concentration levels in pseudo urine with small incremental levels at the adult human urination flow rate. The impact of human body weight on quantification measurements using a wet diaper was studied. The gravitational pull effect of wetness was evaluated for on-human-torso use in both standing and lying positions. It was observed that a printed coplanar capacitive sensor alone is insufficient to reliably quantify the voided volume in diapers.
  • A Review of Applications of Machine Learning for Emissions Estimation in Diesel Engines
    (2024) Nguyen Khac, Hoang; Linh Nguyen, Thuy
     A4 Artikkeli konferenssijulkaisussa
    There has been an increasing demand to reduce the emissions of diesel engines, especially in maritime applications. Moreover, emission regulations are becoming stricter every year. This has led to an urge for more complex engine control systems with more accurate emissions estimators included. Machine learning methods have been long adopted to create models with high complexity to estimate the engine’s emissions and to rely less on conventional physical measurement devices. This paper presents a brief review of the development of engine emissions estimation using machine learning methods over the last 20 years. The review will however mainly focus on emissions prediction from engine in-cylinder pressure and engine functional vibration signal.
  • Deformable Wire Media Resonators
    (2024) Khobzei, M.; Tkach, V.; Haliuk, S.; Samila, A.; Bobrovs, V.; Ginzburg, P.; Simovski, C.; Vovchuk, D.
     A4 Artikkeli konferenssijulkaisussa
    Temporal degree of freedom opens new capabilities to control electromagnetic interactions with structured media. While fast, comparable to the carrier oscillation period, changes in effective material susceptibilities suggest emerging new peculiar phenomena, experimental realizations of lag theoretical predictions. However, phenomena, inspired by slow practically realizable parametric changes in effective media, have both fundamental interest and immediate practical applications. Here we perform comprehensive studies of modal hierarchy in a deformable Fabry-Perot resonator, constructed from a wire array, hosted in a compressible dielectric host. The lattice parameter of the wire media can be controlled over a 5 -fold range (between 10 and 50 mm), leading to superior electromagnetic tunability. Furthermore, the resonator response demonstrates an extreme sensitivity to mechanical deformation as resonance hierarchy in metamaterial assembly strongly depends on the lattice constant. Specifically, a 0.3 mm change in the lattice constant, being as small as ∼ 0.002 λ, shifts the Fabry-Perot resonance frequency around 1.9 GHz. Owing to their extraordinary responsivity, deformable electromagnetic metamaterials can find use as elements in adaptive user-controlled devices.
  • Enhancing Renewable Energy Hosting Capacity in Unbalanced Microgrids via Empowering Smart Inverters
    (2025) Mousa, Hossam H. H.; Mahmoud, Karar; Lehtonen, Matti
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    This article presents a coordinated planning strategy for renewable energy sources (RESs) and energy storage systems (ESSs) in unbalanced microgrids. The approach aims to mitigate voltage unbalance, reduce power losses, alleviate feeder congestion, and maximize the hosting capacity (HC) of RESs in grid-connected unbalanced microgrids. By employing smart inverter control for photovoltaic (PV) and ESS inverters, the strategy enhances the integration of additional RESs while minimizing power exchange between operational zones and the utility grid (UG). To achieve such an ambitious goal, smart inverter control functions are employed, including combined mode, volt-var (VV), volt-watt (VW) for Photovoltaic (PV) inverters, and VW for ESS inverters. The IEEE 123-bus test system, divided into six operational zones, is used as a case study, incorporating plug-in electric vehicle (PEV) demand and wind-based distributed generation (DG). A metaheuristic algorithm is developed for optimal DG and ESS deployment using MATLAB and OpenDSS. The results demonstrate significant improvements, including a 16% reduction in feeder congestion, a 150% increase in PV penetration, a 13% reduction in power losses, and decreased reliance on the UG, ensuring enhanced power quality and system reliability.
  • Harnessing HARQ Retransmissions for Fast Average Consensus Over Unreliable Communication Channels
    (2023) Makridis, Evagoras; Charalambous, Themistoklis; Hadjicostis, Christoforos N.
     A4 Artikkeli konferenssijulkaisussa
    In this work, we introduce a new consensus mechanism by incorporating a Hybrid Repeat reQuest (HARQ) error control protocol into the Ratio Consensus (RC) algorithm to achieve fast discrete-time asymptotic average consensus in the presence of packet retransmissions (information delays), and packet-dropping links (information loss) over directed networks. Using this consensus mechanism (hereinafter referred to as HARQ-RC), each transmitting node decides whether to retransmit packets (containing values of consensus variables) to its out-neighbors by utilizing their HARQ feedback signals. Under this protocol, each receiving node may detect the corrupted part of the received packet, and by combining successfully received information from previous retransmission trials, it may recover the information of the packet. This mechanism leads in a lower number of retransmission trials compared to standard ARQ mechanism, and hence the consensus iterations converge faster to the average consensus value. By introducing the weighted adjacency matrix that models the HARQ-based information exchange between nodes, we show that the nodes are guaranteed to reach asymptotic average consensus using the HARQ-RC mechanism despite the information delays and losses. The effectiveness of the HARQ-RC over bad communication links, with respect to achieving faster convergence to the average consensus value, is demonstrated under different simulation scenarios.
  • Interoperability in Software-Defined Process Automation Using the Open Process Automation Standard and IEC 61499: Adapter Connections of IEC 61499 and OPAS Enable Plug-and-Play Integration
    (2024) Jhunjhunwala, Pranay; Stephen Bitar, S.; Zhukovskii, Kirill; Atmojo, Udayanto Dwi; Vyatkin, Valeriy
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The increasing demand for flexibility in factory automation has led to the need for high interoperability between controllers, sensors, and actuators. This paper demonstrates how the interoperability provisions developed by the Open Process Automation Standard (OPAS) can be used to improve the interchangeability and interoperability of controller function blocks in cascade control. We also show how this development enables easier integration of IIoT devices into process automation applications. This article demonstrates how OPAS development improved interoperability between controllers and IIoT devices while reducing on-floor system integration efforts by bringing the required transparency between the OT and IT layers in the factory.
  • Single-Phase Transformerless Buck-Boost PV-Inverter For Leakage Current Minimization
    (2025) Ali, Ahmed; Hemeida, Ahmed; Hassan, Alaa; Saeed, Mahmoud; Belahcen, Anouar
     A4 Artikkeli konferenssijulkaisussa
    This paper presents a novel transformerless buck-boost single-stage topology with a single energy storage inductor, designed for single-phase grid-connected PV applications. The symmetrical operation of the proposed topology, considering a single inductor, effectively minimizes the DC-current injection into the grid. The buck-boost capability of this design enables Maximum Power Point Tracking (MPPT) even under large variations in PV voltage, which make this structure applicable for wide range of input voltage variations. Operating at a frequency of 85 kHz, the topology employs five controllable devices, with only one functioning at high frequency, resulting in low switching losses. Using a single SiC fast device for high-frequency operation contributes to a cost-effective solution. Additional benefits of high switching frequency include increased power density, enhanced efficiency, and reduced filter size. MPPT, buck or boost functionality, and DC-AC inversion are all achieved within a single power stage. The proposed topology also exhibits a low leakage current. The paper provides a detailed analysis of the operating principle, supported by simulation results.
  • Applicability of Physical Optics for Predicting the Diffraction Pattern of Binary Metasurfaces
    (2024) Shabanpour, J.; Tretyakov, S.; Simovski, C.
     A4 Artikkeli konferenssijulkaisussa
    In this paper, we outline the domain of adequacy for the well-known approximation of physical optics (PO) for binary metasurfaces (MSs). First, we show that beyond the approximation of so-called reflection locality (RL) PO cannot be applied for practical reflecting MSs. Next, in the framework of RL approximation we derive a closed-form expression for the diffraction pattern of a finite-size binary MS and compare the results with full-wave simulations. We show that PO may be applied for a binary MS if and only if the incident and deflection angles are sufficiently small, i.e. the MS period is sufficiently large. In this case, the desired anomalous reflection is due to one of the two first-order diffraction lobes, whose magnitudes are adequately predicted by PO.
  • Optimization of Printed Synchronous Reluctance Rotor Based on Bézier Curves
    (2024) Michieletto, Daniele; Alberti, Luigi; Belahcen, Anouar
     A4 Artikkeli konferenssijulkaisussa
    This paper deals with the optimization of a multi-barrier synchronous reluctance rotor, in which the flux barriers are parameterized using Bézier curves. With this type of modeling, it is possible to explore more complex geometries that can be realized with new additive manufacturing techniques. A two-step optimization based on the NSGA-II genetic algorithm is proposed in the paper. In the first part, barriers are optimized using a simplified analytical model. In the second part, the rotor geometry is optimized using finite element analysis. Finally, a more detailed investigation is performed to calculate the overall performance of the optimized solution and compare them with those of a previously manufactured prototype.
  • Framework for Faster-Than-Real-Time Testing of IEC 61499 Applications with Embedded Process Simulation
    (2024) Vyatkin, Valeriy; Rumiantsev, Roman
     A4 Artikkeli konferenssijulkaisussa
    This paper presents a novel framework for testing automation applications compliant with the international standard IEC 61499 and including process simulation. The framework enables automation programs to be run in testing mode faster than real time, validated by an external tester program. Application of the approach is illustrated on example of a simple component-based system.
  • Radial Lumped-parameter Model of a Ball Bearing for Simulated Fault Signatures
    (2023) Bouharrouti, Nada El; Martin, Floran; Belahcen, Anouar
     A4 Artikkeli konferenssijulkaisussa
    In the literature, lumped-parameter models of ball bearing have been widely developed to provide vibration data for condition monitoring purposes. These are generic models which consider the contacts occurring between the two rings and all the balls in the bearing thanks to Hertzian contact stress theory. In this paper, a radial lumped-parameter model is developed on MATLAB/Simulink for a single ball in contact with the bearing races under a load distribution as a function of its angular position on the races. This simplified radial model identifies fault signatures in frequency domain for inner and outer ring defects. Afterward, the model is evaluated in contrast with the experimental data for OR faults provided by the Case Western Reserve University open-source dataset. The radial lumped- parameter model is able to reproduce the fault signatures for the same working conditions as the experimental data for OR defects of several geometries.