1.
Blanch, Krister, 1991
(författare)
Beyond-application datasets and automated fair benchmarking
2023
Licentiatavhandling (övrigt vetenskapligt/konstnärligt) abstract
Beyond-application perception datasets are generalised datasets that emphasise the fundamental components of good machine perception data. When analysing the history of perception datatsets, notable trends suggest that design of the dataset typically aligns with an application goal. Instead of focusing on a specific application, beyond-application datasets instead look at capturing high-quality, high-volume data from a highly kinematic environment, for the purpose of aiding algorithm development and testing in general. Algorithm benchmarking is a cornerstone of autonomous systems development, and allows developers to demonstrate their results in a comparative manner. However, most benchmarking systems allow developers to use their own hardware or select favourable data. There is also little focus on run time performance and consistency, with benchmarking systems instead showcasing algorithm accuracy. By combining both beyond-application dataset generation and methods for fair benchmarking, there is also the dilemma of how to provide the dataset to developers for this benchmarking, as the result of a high-volume, high-quality dataset generation is a significant increase in dataset size when compared to traditional perception datasets. This thesis presents the first results of attempting the creation of such a dataset. The dataset was built using a maritime platform, selected due to the highly dynamic environment presented on water. The design and initial testing of this platform is detailed, as well as as methods of sensor validation. Continuing, the thesis then presents a method of fair benchmarking, by utilising remote containerisation in a way that allows developers to present their software to the dataset, instead of having to first locally store a copy. To test this dataset and automatic online benchmarking, a number of reference algorithms were required for initial results. Three algorithms were built, using the data from three different sensors captured on the maritime platform. Each algorithm calculates vessel odometry, and the automatic benchmarking system was utilised to show the accuracy and run-time performance of these algorithms. It was found that the containerised approach alleviated data management concerns, prevented inflated accuracy results, and demonstrated precisely how computationally intensive each algorithm was.
2.
Westin, Jonathan, 1980, et al.
(författare)
Digitising Sensitive Heritage Monuments In Antarctica
2024
Ingår i: The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLVIII-2/W4-2024. 10th International Workshop 3D-ARCH "3D Virtual Reconstruction and Visualization of Complex Architectures, 21–23 February 2024, Siena, Italy / editor(s): S. Campana, F. Fassi, and F. Remondino. - : International Society for Photogrammetry and Remote Sensing. - 1682-1750.
Konferensbidrag (refereegranskat) abstract
During the Antarctica expedition CHAQ2020, several cultural heritage sites – remains from the Swedish South Polar Expedition (1901–1903) – were documented using a range of different techniques and technologies. These physical monuments and environments are for all intents and purposes unavailable for most researchers due to their remote location and are also threatened by the effects of climate change. Hence, the deployed documentation techniques and technologies were selected both as a consequence of the inherently difficult conditions in Antarctica, where their reliance, durability, and speed were key considerations, but also for their perceived ability to document the unique and fragile environment. The documentation was carried out with the double intention of both allowing for observations in situ through processes of analytical drawings and data capture, but also capturing the environment as broadly and deeply as possible, in essence making a copy of it open for studies of unknown unknowns, that could serve as a source material for research questions still undefined. Hence, with the documentation of the winter station on Snow Hill Island as a case study, and with a perspective on documentation as a method through which to process, preserve, and disseminate information, this article serves to critically detail, compare, and evaluate the digital techniques and technologies that the expedition deployed to capture architectural elements and spatial contexts, and the data that could be obtained through these.
3.
Zhang, Kewei
(författare)
Secure GNSS-based Positioning and Timing : Distance-Decreasing attacks, fault detection and exclusion, and attack detection with the help of opportunistic signals
2021
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
With trillions of devices connected in large scale systems in a wired or wireless manner, positioning and synchronization become vital. Global Navigation Satellite System (GNSS) is the first choice to provide global coverage for positioning and synchronization services. From small mobile devices to aircraft, from intelligent transportation systems to cellular networks, and from cargo tracking to smart grids, GNSS plays an important role, thus, requiring high reliability and security protection. However, as GNSS signals propagate from satellites to receivers at distance of around 20 000 km, the signal power arriving at the receivers is very low, making the signals easily jammed or overpowered. Another vulnerability stems from that civilian GNSS signals and their specifications are publicly open, so that anyone can craft own signals to spoof GNSS receivers: an adversary forges own GNSS signals and broadcasts them to the victim receiver, to mislead the victim into believing that it is at an adversary desired location or follows a false trajectory, or adjusts its clock to a time dictated by the adversary. Another type of attack is replaying GNSS signals: an adversary transmits a pre-recorded GNSS signal stream to the victim receiver, so that the receiver calculates an erroneous position and time. Recent incidents reported in press show that the GNSS functionalities in a certain area, e.g., Black Sea, have been affected by cyberattacks composed of the above-mentioned attack types. This thesis, thus, studies GNSS vulnerabilities and proposes detection and mitigation methods for GNSS attacks, notably spoofing and replay attacks. We analyze the effectiveness of one important and powerful replay attack, the so-called Distance-decreasing (DD) attacks that were previously investigated for wireless communication systems, on GNSS signals. DD attacks are physical layer attacks, targeting time-of-flight ranging protocols, to shorten the perceived as measured distance between the transmitter and receiver. The attacker first transmits an adversary-chosen data bit to the victim receiver before the signal arrives at the attacker; upon receipt of the GNSS signal, the attacker estimates the data bit based on the early fraction of the bit period, and then switches to transmitting the estimate to the victim receiver. Consequently, the DD signal arrives at the victim receiver earlier than the genuine GNSS signals would have, which in effect shortens the pseudorange measurement between the sender (satellite) and the victim receiver, consequently, affecting the calculated position and time of the receiver. We study how the DD attacks affect the bit error rate (BER) of the received signals at the victim, and analyze its effectiveness, that is, the ability to shorten pseudorange measurements, on different GNSS signals. Several approaches are considered for the attacker to mount a DD attack with high probability of success (without being detected) against a victim receiver, for cryptographically unprotected and protected signals. We analyze the tracking output of the DD signals at the victim receiver and propose a Goodness of Fit (GoF) test and a Generalized Likelihood Ratio Test (GLRT) to detect the attacks. The evaluation of the two tests shows that they are effective, with the result being perhaps more interesting when considering DD attacks against Galileo signals that can be cryptographically protected. Moreover, this thesis investigates the feasibility of validating the authenticity of the GNSS signals with the help of opportunistic signals, which is information readily available in modern communication environments, e.g., 3G, 4G and WiFi. We analyze the time synchronization accuracy of different technologies, e.g., Network Time Protocol (NTP), WiFi and local oscillator, as the basis for detecting a discrepancy with the GNSS-obtained time. Two detection approaches are proposed and one testbench is designed for the evaluation. A synthesized spoofing attack is used to verify the effectiveness of the approaches. Beyond attack detection, we develop algorithms to detect and exclude faulty signals, namely the Clustering-based Solution Separation Algorithm (CSSA) and the Fast Multiple Fault Detection and Exclusion (FM-FDE). They both utilize the redundant available satellites, more than the minimum a GNSS receiver needs for position and time offset calculation. CSSA adopts data clustering to group subsets of positions calculated with different subsets of available satellites. Basically, these positions, calculated with subsets not containing any faulty satellites, should be close to each other, i.e., in a dense area; otherwise they should be scattered. FM-FDE is a more efficient algorithm that uses distances between positions, calculated with fixed-size subsets, as test statistics to detect and exclude faulty satellite signals. As the results show, FM-FDE runs faster than CSSA and other solution-separation fault detection and exclusion algorithms while remaining equally effective.
4.
Kersten, Anton, 1991, et al.
(författare)
Measuring and Separating Conducted Three-Wire Emissions from a Fault-Tolerant, NPC Propulsion Inverter with a Split-Battery Using Hardware Separators Based on HF Transformers
2021
Ingår i: IEEE Transactions on Power Electronics. - 0885-8993 .- 1941-0107. ; 36:1, s. 378-390
Tidskriftsartikel (refereegranskat) abstract
Conducted emissions on the traction battery's power cables in EVs must be limited to avoid unwanted electromagnetic interference (EMI). When designing an EMI filter, it is advantageous to have information of the common mode (CM) and differential mode (DM) noise levels. This article deals with the measurement and separation of the dc side's three-wire DM/CM noise of a fault-tolerant three-level neutral-point-clamped (NPC) inverter with a split-battery system. Two hardware separators, based on small-circuit highfrequency transformers, were developed to identify the dc side's CM, line-DM, and phase-DM noise levels. Their characterized CM and DM rejection ratios for the frequency range from 150 kHz to 110 MHz are at least -33 and -21 dB, respectively. The separated noise of the NPC inverter was measured, using an inductive load, when operating the inverter with three-level and two-level modulation, resembling normal operation and a possible operation under fault, respectively. A simple three-wire CM model of the used testbed and the DM power module oscillation were derived to validate the separated noise's resonance peaks/valleys. It has been seen that the CM noise is dominant, especially below 10 MHz, except for the power module oscillations. Furthermore, when using the two-level modulation, in the case of a clamping diode fault, the noise levels are increased by about 3 dB.
5.
Kersten, Anton, 1991
(författare)
Modular Battery Systems for Electric Vehicles based on Multilevel Inverter Topologies - Opportunities and Challenges
2021
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Modular battery systems based on multilevel inverter (MLI) topologies can possibly overcome some shortcomings of two-level inverters when used for vehicle propulsion. The results presented in this thesis aim to point out the advantages and disadvantages, as well as the technical challenges, of modular vehicle battery systems based on MLIs in comparison to a conventional, two-level IGBT inverter drivetrain. The considered key aspects for this comparative investigation are the drive cycle efficiency, the inverter cost, the fault tolerance capability of the drivetrain and the conducted electromagnetic emissions. Extensive experiments have been performed to support the results and conclusions. In this work, it is shown that the simulated drive cycle efficiency of different low-voltage-MOSFET-based, cascaded seven-level inverter types is improved in comparison to a similarly rated, two-level IGBT inverter drivetrain. For example, the simulated WLTP drive cycle efficiency of a cascaded double-H-bridge (CDHB) inverter drivetrain in comparison to a two-level IGBT inverter, when used in a small passenger car, is increased from 94.24% to 95.04%, considering the inverter and the ohmic battery losses. In contrast, the obtained efficiency of a similar rated seven-level cascaded H-bridge (CHB) drivetrain is almost equal to that of the two-level inverter drivetrain, but with the help of a hybrid modulation technique, utilizing fundamental selective harmonic elimination at lower speeds, it could be improved to 94.85%. In addition, the CDHB and CHB inverters’ cost, in comparison to the two-level inverter, is reduced from 342€ to 202€ and 121€, respectively. Furthermore, based on a simple three-level inverter with a dual battery pack, it is shown that MLIs inherently allow for a fault tolerant operation. It is explained how the drivetrain of a neutral point clamped (NPC) inverter can be operated under a fault condition, so that the vehicle can drive with a limited maximum power to the next service station, referred to as limp home mode. Especially, the detection and localization of open circuit faults has been investigated and verified through simulations and experiments. Moreover, it is explained how to measure the conducted emissions of an NPC inverter with a dual battery pack according to the governing standard, CISPR 25, because the additional neutral point connection forms a peculiar three-wire DC source. To separate the measured noise spectra into CM, line-DM and phase-DMquantities, two hardware separators based on HF transformers are developed and utilized. It is shown that the CM noise is dominant. Furthermore, the CM noise is reduced by 3dB to 6dB when operating the inverter with three-level instead of two-level modulation.
6.
Kersten, Anton, 1991, et al.
(författare)
Online and On-Board Battery Impedance Estimation of Battery Cells, Modules or Packs in a Reconfigurable Battery System or Multilevel Inverter
2020
Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2162-4704 .- 2577-1647. ; 2020-October, s. 1884-1891
Konferensbidrag (refereegranskat) abstract
This paper shows two approaches to determine the battery impedance of battery cells or battery modules when used in a reconfigurable battery system (RBS) or in any type of modular multilevel converter (MMC) for electric drive applications. A generic battery model is used and the concepts of the recursive time and frequency-domain parameter extraction, using a current step and an electrochemical impedance spectroscopy, are explained. Thus, it is shown and demonstrated that the balancing current of neighboring cells/modules ,when in parallel operation, can be used, similar to the time-domain parameter extraction utilizing a current step, to determine the battery parameters. Furthermore, it is shown and demonstrated that a part of the inverter can be used as variable AC voltage source to control a sinusoidal current through the motor inductances of the drive train, which can be injected to the inserted battery cells/modules of an adjacent phase to perform an on-board impedance spectroscopy. Using either of the two presented approaches, the individual battery impedances can be easily determined, yielding the state of health (SOH) and the power capability of individual battery cells/modules. Nonetheless, the analyzed approaches were just considered to be applied at machine standstill, which is not suitable for grid-tied applications.
7.
Theliander, Oskar, et al.
(författare)
Battery Modeling and Parameter Extraction for Drive Cycle Loss Evaluation of a Modular Battery System for Vehicles Based on a Cascaded H-Bridge Multilevel Inverter
2020
Ingår i: IEEE Transactions on Industry Applications. - 0093-9994 .- 1939-9367. ; 56:6, s. 6968-6977
Tidskriftsartikel (refereegranskat) abstract
This article deals with the modeling and the parameterization of the battery packs used in cascaded H-bridge multilevel propulsion inverters. Since the battery packs are intermittently conducting the motor currents, the battery cells are stressed with a dynamic current containing a substantial amount of low-order harmonic components up to a couple of kHz, which is a major difference in comparison to a traditional two-level inverter drive. Different models, such as pure resistive and dynamic RC -networks, are considered to model the energy losses for different operating points (OPs) and driving cycles. Using a small-scale setup, the models’ parameters are extracted using both a low-frequency, pulsed current, and an electrochemical impedance spectroscopy (EIS) sweep. The models are compared against measurements conducted on the small-scale setup at different OPs. Additionally, a drive cycle loss comparison is simulated. The simple resistive model overestimates the losses by about 20% and is, thus, not suitable. The dynamic three-time-constant model, parameterized by a pulsed current, complies with the measurements for all analyzed OPs, especially at low speed, with a maximum deviation of 3.8%. Extracting the parameters using an EIS seems suitable for higher speeds, though the losses for the chosen OPs are underestimated by 1.5%–7.9%.
8.
Grabowski, Alexander, 1993
(författare)
VCSEL Equivalent Circuits and Silicon Photonics Integration
2022
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
The vertical-cavity surface-emitting laser (VCSEL) is a light source of great importance for numerous industrial and consumer products. The main application areas are datacom and sensing. The datacom industry uses GaAs-based VCSELs for optical interconnects, the short-reach fiber optical communication links used to transfer large amounts of data at high rates between units within data centers and supercomputers. In the area of sensing, VCSELs are largely used in consumer products such as smart phones (e.g. face ID and camera auto focus), computer mice, and automobiles (e.g. gesture recognition and LIDAR for autonomous driving). In this work, an advanced physics-based equivalent circuit model for datacom VCSELs has been developed. The model lends itself to co-design and co-optimization with driver and receiver ICs, thereby enabling higher data rate transceivers with bandwidth limited VCSELs and photodiodes. The model also facilitates an understanding of how each physical process within the VCSEL affects the VCSEL static and dynamic performance. It has been applied to study the impact of carrier transport and capture on VCSEL dynamics. The work also includes micro-transfer-printing of GaAs-based single-mode VCSELs on silicon nitride photonic integrated circuits (PICs). Such PICs are increasingly used for e.g. compact and highly functional bio-photonic sensors. Transfer printing of VCSELs enables the much-needed on-PIC integration of power efficient light sources. The bottom-emitting VCSELs are printed above grating couplers on the PIC and optical feedback is used to control the polarization for efficient coupling to the silicon nitride waveguide. Wavelength tuning, as required by the bio-sensing application, is achieved by direct current modulation.
9.
Kruglov, Dmitrii, 1994, et al.
(författare)
Enhancing mmWave On-Chip-Antennas Using In-Package Electromagnetic Bandgap Structures
2021
Ingår i: European Microwave Conference. - 1527-3342 .- 1557-9581. - 9782874870637 ; , s. 885-888
Konferensbidrag (refereegranskat) abstract
We propose a silicon on-Chip-in-Package antenna design featuring a simulated radiation efficiency of > 70% and an S11 matching better than −10 dB in the 112–125 GHz frequency range. High radiation performance is achieved by: (i) thinning the silicon substrate down to 100 μm through wafer-level grinding; (ii) embedding the IC in-between two PCBs, one of which forms an electromagnetic bandgap structure that attenuates the EM leakage inside the silicon substrate. Furthermore, since the die-embedding concept employs the gap-waveguide packaging technology, a universal contactless waveguide interconnect is realized between the IC and the radiating gap waveguide in the package. This will also enable modular antenna designs.
10.
Mahdavi, Mojtaba
(författare)
Baseband Processing for 5G and Beyond: Algorithms, VLSI Architectures, and Co-design
2021
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
In recent years the number of connected devices and the demand for high data-rates have been significantly increased. This enormous growth is more pronounced by the introduction of the Internet of things (IoT) in which several devices are interconnected to exchange data for various applications like smart homes and smart cities. Moreover, new applications such as eHealth, autonomous vehicles, and connected ambulances set new demands on the reliability, latency, and data-rate of wireless communication systems, pushing forward technology developments. Massive multiple-input multiple-output (MIMO) is a technology, which is employed in the 5G standard, offering the benefits to fulfill these requirements. In massive MIMO systems, base station (BS) is equipped with a very large number of antennas, serving several users equipments (UEs) simultaneously in the same time and frequency resource. The high spatial multiplexing in massive MIMO systems, improves the data rate, energy and spectral efficiencies as well as the link reliability of wireless communication systems. The link reliability can be further improved by employing channel coding technique. Spatially coupled serially concatenated codes (SC-SCCs) are promising channel coding schemes, which can meet the high-reliability demands of wireless communication systems beyond 5G (B5G). Given the close-to-capacity error correction performance and the potential to implement a high-throughput decoder, this class of code can be a good candidate for wireless systems B5G. In order to achieve the above-mentioned advantages, sophisticated algorithms are required, which impose challenges on the baseband signal processing. In case of massive MIMO systems, the processing is much more computationally intensive and the size of required memory to store channel data is increased significantly compared to conventional MIMO systems, which are due to the large size of the channel state information (CSI) matrix. In addition to the high computational complexity, meeting latency requirements is also crucial. Similarly, the decoding-performance gain of SC-SCCs also do come at the expense of increased implementation complexity. Moreover, selecting the proper choice of design parameters, decoding algorithm, and architecture will be challenging, since spatial coupling provides new degrees of freedom in code design, and therefore the design space becomes huge. The focus of this thesis is to perform co-optimization in different design levels to address the aforementioned challenges/requirements. To this end, we employ system-level characteristics to develop efficient algorithms and architectures for the following functional blocks of digital baseband processing. First, we present a fast Fourier transform (FFT), an inverse FFT (IFFT), and corresponding reordering scheme, which can significantly reduce the latency of orthogonal frequency-division multiplexing (OFDM) demodulation and modulation as well as the size of reordering memory. The corresponding VLSI architectures along with the application specific integrated circuit (ASIC) implementation results in a 28 nm CMOS technology are introduced. In case of a 2048-point FFT/IFFT, the proposed design leads to 42% reduction in the latency and size of reordering memory. Second, we propose a low-complexity massive MIMO detection scheme. The key idea is to exploit channel sparsity to reduce the size of CSI matrix and eventually perform linear detection followed by a non-linear post-processing in angular domain using the compressed CSI matrix. The VLSI architecture for a massive MIMO with 128 BS antennas and 16 UEs along with the synthesis results in a 28 nm technology are presented. As a result, the proposed scheme reduces the complexity and required memory by 35%–73% compared to traditional detectors while it has better detection performance. Finally, we perform a comprehensive design space exploration for the SC-SCCs to investigate the effect of different design parameters on decoding performance, latency, complexity, and hardware cost. Then, we develop different decoding algorithms for the SC-SCCs and discuss the associated decoding performance and complexity. Also, several high-level VLSI architectures along with the corresponding synthesis results in a 12 nm process are presented, and various design tradeoffs are provided for these decoding schemes.
11.
Ranisch, Robert, et al.
(författare)
Ethics of digital contact tracing apps for the Covid-19 pandemic response
2020
Rapport (övrigt vetenskapligt/konstnärligt) abstract
There is a growing interest in contact tracing apps (CT apps) for pandemic man- agement. These apps raise significant moral concerns. It is therefore crucial to consider ethical requirements before and while implementing such apps. Public trust is of major importance for population uptake of contact tracing apps. Hasty, ill-prepared or badly communicated implementations of CT apps will likely under- mine public trust, and as such, risk impeding general effectiveness. In response to these demands, to meet ethical requirements and find a basis for justified trust, this background introduces an ethical framework for a responsible design and implementation of CT apps. However, even prudently chosen measures of digital contact tracing carry moral costs, which makes it necessary address different trade-offs. This background paper aims to inform developers, researchers and decision-makers be- fore and throughout the process of implementing contact tracing apps.
12.
Ivashina, Marianna, 1975, et al.
(författare)
Antenna Technologies for Beyond-5G Wireless Communication : Challenges and Opportunities
2021
Ingår i: 2021 International Symposium on Antennas and Propagation, ISAP 2021. - : Institute of Electrical and Electronics Engineers (IEEE).
Konferensbidrag (refereegranskat) abstract
This paper provides an overview of the Sweden-Taiwan collaborative research framework project 'Antenna Technologies for Beyond-5G Wireless Communication' that has been recently established to develop robust and energy-efficient integrated antenna solutions for frequencies beyond 100 GHz as future enabling technologies for the 5G+ applications. Technological challenges in manufacturing and integration with electronics as well as available opportunities are discussed.
13.
Petersson, Jesper, 1974, et al.
(författare)
Off the record: The invisibility work of doctors in a patient-accessible electronic health record information service.
2021
Ingår i: Sociology of health & illness. - : Wiley. - 1467-9566 .- 0141-9889. ; 43:5, s. 1270-1285
Tidskriftsartikel (refereegranskat) abstract
In this article, we draw on Michael Lipsky's work on street-level bureaucrats and discretion to analyse a real case setting comprising an interview study of 30 Swedish doctors regarding their experiences of changes in clinical work following patients being given access to medical records information online. We introduce the notion of invisibility work to capture how doctors exercise discretion to preserve the invisibility of their work, in contrast to the well-established notion of invisible work, which denotes work made invisible by parties other than those performing it. We discuss three main forms of invisibility work in relation to records: omitting information, cryptic writing and parallel note writing. We argue that invisibility work is a way for doctors to resolve professional tensions arising from the political decision to provide patients with online access to record information. Although invisibility work is understood by doctors as a solution to government-initiated visibility, we highlight how it can create difficulties for doctors concerning accountability towards patients, peers and authorities.
14.
Han, Weiji, 1987, et al.
(författare)
Next-Generation Battery Management Systems: Dynamic Reconfiguration
2020
Ingår i: IEEE Industrial Electronics Magazine. - 1941-0115 .- 1932-4529. ; 14:4, s. 20-31
Tidskriftsartikel (refereegranskat) abstract
Batteries are widely applied to the energy storage and power supply in portable electronics, transportation, power systems, communication networks, etc. They are particularly demanded in the emerging technologies of vehicle electrification and renewable energy integration for a green and sustainable society. To meet various voltage, power, and energy requirements in large-scale applications, multiple battery cells have to be connected in series and/or parallel. While battery technology has advanced significantly in the past decade, existing battery management systems (BMSs) mainly focus on state monitoring and control of battery systems packed in fixed configurations. In fixed configurations, though, the battery system performance is in principle limited by the weakest cells, which can leave large parts severely underutilized. Allowing dynamic reconfiguration of battery cells, on the other hand, allows individual and flexible manipulation of the battery system at cell, module, and pack levels, which may open up a new paradigm for battery management. Following this trend, this paper provides an overview of next-generation BMSs featuring dynamic reconfiguration. Motivated by numerous potential benefits of reconfigurable battery systems (RBSs), the hardware designs, management principles, and optimization algorithms for RBSs are sequentially and systematically discussed. Theoretical and practical challenges during the design and implementation of RBSs are highlighted in the end to stimulate future research and development.
15.
Behdadi, Dorna, 1988, et al.
(författare)
A Normative Approach to Artificial Moral Agency
2020
Ingår i: Minds and Machines. - : Springer Science and Business Media LLC. - 0924-6495 .- 1572-8641. ; 30:2, s. 195-218
Tidskriftsartikel (refereegranskat) abstract
This paper proposes a methodological redirection of the philosophical debate on artificial moral agency (AMA) in view of increasingly pressing practical needs due to technological development. This “normative approach” suggests abandoning theoretical discussions about what conditions may hold for moral agency and to what extent these may be met by artificial entities such as AI systems and robots. Instead, the debate should focus on how and to what extent such entities should be included in human practices normally assuming moral agency and responsibility of participants. The proposal is backed up by an analysis of the AMA debate, which is found to be overly caught in the opposition between so-called standard and functionalist conceptions of moral agency, conceptually confused and practically inert. Additionally, we outline some main themes of research in need of attention in light of the suggested normative approach to AMA.
16.
Nedic, Mitja, et al.
(författare)
Herglotz functions and applications in electromagnetics
2020
Ingår i: Advances in Mathematical Methods for Electromagnetics. - : Institution of Engineering and Technology. - 9781785613845 - 9781785613852 ; , s. 491-514
Bokkapitel (övrigt vetenskapligt/konstnärligt) abstract
Herglotz functions inevitably appear in pure mathematics, mathematical physics, and engineering with a wide range of applications. In particular, they are the pertinent functions to model passive systems, and thus appear in modeling of electromagnetic phenomena in circuits, antennas, materials, and scattering. In this chapter, we review the basic theory of Herglotz functions and its applications to determine sum rules and physical bounds for passive systems.
17.
Shahroozi, Zahra, 1992-
(författare)
Survivability control using data-driven approaches and reliability analysis for wave energy converters
2024
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Wave energy, with five times the energy density of wind and ten times the power density of solar, offers a compelling carbon-free electricity solution. Despite its advantages, ongoing debates surround the reliability and economic feasibility of wave energy converters (WECs). To address these challenges, this doctoral thesis is divided into four integral parts, focusing on optimizing the prediction horizon for power maximization, analyzing extreme waves' impact on system dynamics, ensuring reliability, and enhancing survivability in WECs.Part I emphasizes the critical importance of the prediction horizon for maximal power absorption in wave energy conversion. Using generic body shapes and modes, it explores the effect of dissipative losses, noise, filtering, amplitude constraints, and real-world wave parameters on the prediction horizon. Findings suggest achieving optimal power output may be possible with a relatively short prediction horizon, challenging traditional assumptions.Part II shifts focus to WEC system dynamics, analyzing extreme load scenarios. Based on a 1:30 scaled wave tank experiment, it establishes a robust experimental foundation, extending into numerical assessment of the WEC. Results underscore the importance of damping to alleviate peak forces. Investigating various wave representations highlights conservative characteristics of irregular waves, crucial for WEC design in extreme sea conditions.Part III explores the computational intricacies of environmental design load cases and fatigue analyses for critical mechanical components of the WEC. The analysis is conducted for hourly sea state damage and equivalent two-million-cycle loads. Finally, a comparison of safety factors between the ultimate limit state and fatigue limit state unfolds, illustrating the predominant influence of the ultimate limit state on point-absorber WEC design.Part IV, centers on elevating survivability strategies for WECs in extreme wave conditions. Three distinct controller system approaches leverage neural networks to predict and minimize the line force. Distinct variations emerge in each approach, spanning from rapid detection of optimal damping to integrating advanced neural network architectures into the control system with feedback. The incorporation of a controller system, refined through experimental data, showcases decreases in the line force, providing a practical mechanism for real-time force alleviation.This thesis aims to contribute uniquely to the goal of advancing wave energy conversion technology through extensive exploration.
18.
Rebolledo Salgado, Israel, 1992, et al.
(författare)
Active Feedback Stabilization of Super-efficient Microcombs
2023
Ingår i: 2023 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC). - : Institute of Electrical and Electronics Engineers (IEEE). - 2833-1052. - 9798350345995
Konferensbidrag (refereegranskat) abstract
We report the long-term operation of a super-efficient microcomb. We use the soliton power to maintain a fixed pump detuning. The microcomb operates over 25 hours using a thermal control in a packaged module.
19.
Pang, Xiaodan, Dr., et al.
(författare)
Bridging the Terahertz Gap : Photonics-assisted Free-Space Communications from the Submillimeter-Wave to the Mid-Infrared
2022
Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers Inc.. - 0733-8724 .- 1558-2213. ; 40:10, s. 3149-3162
Tidskriftsartikel (refereegranskat) abstract
Since about one and half centuries ago, at the dawn of modern communications, the radio and the optics have been two separate electromagnetic spectrum regions to carry data. Differentiated by their generation/detection methods and propagation properties, the two paths have evolved almost independently until today. The optical technologies dominate the long-distance and high-speed terrestrial wireline communications through fiber-optic telecom systems, whereas the radio technologies have mainly dominated the short- to medium-range wireless scenarios. Now, these two separate counterparts are both facing a sign of saturation in their respective roadmap horizons, particularly in the segment of free-space communications. The optical technologies are extending into the mid-wave and long-wave infrared (MWIR and LWIR) regimes to achieve better propagation performance through the dynamic atmospheric channels. Radio technologies strive for higher frequencies like the millimeter-wave (MMW) and sub-terahertz (sub-THz) to gain broader bandwidth. The boundary between the two is becoming blurred and intercrossed. During the past few years, we witnessed technological breakthroughs in free-space transmission supporting very high data rates, many achieved with the assistance of photonics. This paper focuses on such photonics-assisted free-space communication technologies in both the lower and upper sides of the THz gap and provides a detailed review of recent research and development activities on some of the key enabling technologies. Our recent experimental demonstrations of high-speed free-space transmissions in both frequency regions are also presented as examples to show the system requirements for device characteristics and digital signal processing (DSP) performance.
20.
Zarifi, D., et al.
(författare)
A Gap Waveguide-Based D-Band Slot Array Antenna with Interdigital Feed Network
2023
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 71:9, s. 7124-7131
Tidskriftsartikel (refereegranskat) abstract
This work presents a high gain D-band slot array antenna with a corporate-fed distribution network designed by the gap waveguide. The gap waveguide technology is employed for overcoming the challenge of appropriate electrical contact related to the mechanical assemblage of the antenna feed network and the radiation layer. The antenna includes 24×16 slots and the basis of the antenna interdigital feeding network includes the ridge and groove gap waveguides. A standard WR-6 waveguide flange at the bottom is used to excite the presented antenna. To understand the fabrication challenges and tolerance issues around 140GHz, an antenna prototype was made by standard CNC milling techniques. The results show that an impedance bandwidth of 5.5% (141.8-149.8 GHz), efficiency higher than 78%, and a peak gain of 33.8 dBi are achieved for the proposed 24×16-element array antenna. According to the results, the presented planar array is a good option for D-band applications and can be used as the building block to develop high efficiency and high gain upper mm-wave antennas.
21.
Berbyuk, Viktor, 1953
(författare)
Structural Dynamics Control, Third Edition
2020
Bok (övrigt vetenskapligt/konstnärligt) abstract
Structural dynamics and especially one of its main problems, vibrations and vibration control, appear in vehicle engineering, high precision machines and mechanisms, robotics, civil engineering, wind turbines, biomechanics, and others. Over the last decades there has been much work concerned with the vibration control of different dynamical systems. The texbook “Structural Dynamics Control” aims at providing knowledge on modern methods and concepts of passive, semi-active and active vibration control, to cross the bridge between structural dynamics and control engineering, while providing an overview of the potential of smart materials, (magnetorheological fluids, magnetostrictive materials, and others), for sensing and actuating purposes in active vibration control. One of the aims of this textbook is to provide students and engineers with opportunity of becoming familiar with the standard methods of the classical calculus of variations, the linear quadratic regulator optimization methods, and modern optimal control theory with focus on their applications in structural dynamics for vibration attenuation and vibration suppression problems. The textbook consists of four main parts: Vibration dynamics, Passive and semi-active vibration control, Active and hybrid vibration control, and Applications. The textbook ends with the supplementary mathematics, list of Matlab codes and answers and hints for the exercises. The list of references consists of only those books and scientific papers which were used during preparation of the textbook or which have been recommended to stundents for additional information on a studied topic. The textbook is aimed at first towards graduate and postgraduate students following Master and PhD programmes related to structural dynamics, mechatronics, control engineering, automotive engineering, noise and vibrations. The only prerequisite for reading this book is basic knowledge in mechanics and some familiarity with vibrations, state space models and automatic control.
22.
Holstein, Tobias, et al.
(författare)
Steps Towards Real-world Ethics for Self-driving Cars: Beyond the Trolley Problem
2021
Ingår i: Machine Law, Ethics, and Morality in the Age of Artificial Intelligence. - Hershey, Pennsylvania : IGI Global. - 9781799848943 - 9781799848950 ; , s. 85-107
Bokkapitel (övrigt vetenskapligt/konstnärligt) abstract
Research on self-driving cars is transdisciplinary and its different aspects have attracted interest in general public debates as well as among specialists. To this day, ethical discourses are dominated by the Trolley Problem, a hypothetical ethical dilemma that is by construction unsolvable. It obfuscates much bigger real-world ethical challenges in the design, development, and operation of self-driving cars. We propose a systematic approach that connects processes, components, systems, and stakeholders to analyze the real-world ethical challenges for the ecology of socio-technological system of self-driving cars. We take a closer look at the regulative instruments, standards, design, and implementations of components, systems, and services and we present practical social and ethical challenges that must be met and that imply novel expectations for engineering in car industry.
23.
Asplund, Fredrik, 1977-, et al.
(författare)
Knowing too much? : On bias due to domain-specific knowledge in internal crowdsourcing for explorative ideas
2021
Ingår i: R&D Management. - : John Wiley & Sons. - 0033-6807 .- 1467-9310.
Tidskriftsartikel (refereegranskat) abstract
Internal crowdsourcing utilizes a firm’s employees, of which many have a strong understanding of the domains in which the firm operates, for contributing with, developing and evaluating ideas. On the one hand, these employees can use their domain-specific knowledge to identify the value of what may seem a far-fetched solution to the average employee. On the other hand, previous research has shown that employees typically evaluate ideas in their domains less favorably if they do not align with ongoing exploitation activities. Hence, this study focuses on whether a higher degree of relevant domain-specific knowledge makes employees participating in internal crowdsourcing prefer exploitative solutions when evaluating ideas. An empirical study of an online platform for firm-internal innovation in a multinational engineering company showed that employees who only infrequently participated in internal crowdsourcing mostly contributed to and evaluated ideas within their own domain. Employees who frequently participated also contributed to and evaluated ideas outside their own domains. By statistically analyzing group differences during idea evaluation, we show that employees participating infrequently favor exploitable solutions, whereas employees participating frequently are more uncertain. The former difference is only seen concerning ideas that require domain-specific knowledge to understand, but the latter is observed for all types of ideas. This study makes three substantial contributions. First, employees with domain-specific knowledge, through their preference for exploitative solutions, bias the outcome of internal crowdsourcing when idea evaluation requires domain-specific knowledge. Second, this bias is aggravated by the overall higher level of uncertainty displayed by employees participating frequently in internal crowdsourcing and thereby tend to reach out to other domains. Third, in order to mitigate this, bias management can build engagement in internal crowdsourcing through idea challenges that do not require domain-specific knowledge and consider avoiding employees with a strongly associated domain knowledge for idea evaluation.
24.
Kang, Jeongwan, et al.
(författare)
Optimized Switching Between Sensing and Communication for mmWave MU-MISO Systems
2022
Ingår i: 2022 Ieee International Conference On Communications Workshops (Icc Workshops). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 498-503
Konferensbidrag (refereegranskat) abstract
In this paper, we propose a scheme optimizing the per-user channel sensing duration in millimeter-wave (mmWave) multi-user multiple-input single-output (MU-MISO) systems. For each user, the BS predicts the effective rate to be achieved after pilot transmission. Then, the channel sensing duration of each user is optimized by ending the pilot transmission when the predicted rate is lower than the current rate. The robust regularized zero-forcing (RRZF) precoder and equal power allocation (EPA) are adopted to transmit sensing pilots and data. Numerical results show that the more severe the interference among users, the longer channel sensing duration is required. Moreover, the proposed scheme results in a higher sum rate compared to benchmark schemes.
25.
Jiang, Yuning, 1993-
(författare)
Vulnerability Analysis for Critical Infrastructures
2022
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
The rapid advances in information and communication technology enable a shift from diverse systems empowered mainly by either hardware or software to cyber-physical systems (CPSs) that are driving Critical infrastructures (CIs), such as energy and manufacturing systems. However, alongside the expected enhancements in efficiency and reliability, the induced connectivity exposes these CIs to cyberattacks exemplified by Stuxnet and WannaCry ransomware cyber incidents. Therefore, the need to improve cybersecurity expectations of CIs through vulnerability assessments cannot be overstated. Yet, CI cybersecurity has intrinsic challenges due to the convergence of information technology (IT) and operational technology (OT) as well as the crosslayer dependencies that are inherent to CPS based CIs. Different IT and OT security terminologies also lead to ambiguities induced by knowledge gaps in CI cybersecurity. Moreover, current vulnerability-assessment processes in CIs are mostly subjective and human-centered. The imprecise nature of manual vulnerability assessment operations and the massive volume of data cause an unbearable burden for security analysts. Latest advances in machine-learning (ML) based cybersecurity solutions promise to shift such burden onto digital alternatives. Nevertheless, the heterogeneity, diversity and information gaps in existing vulnerability data repositories hamper accurate assessments anticipated by these ML-based approaches. Therefore, a comprehensive approach is envisioned in this thesis to unleash the power of ML advances while still involving human operators in assessing cybersecurity vulnerabilities within deployed CI networks.Specifically, this thesis proposes data-driven cybersecurity indicators to bridge vulnerability management gaps induced by ad-hoc and subjective auditing processes as well as to increase the level of automation in vulnerability analysis. The proposed methodology follows design science research principles to support the development and validation of scientifically-sound artifacts. More specifically, the proposed data-driven cybersecurity architecture orchestrates a range of modules that include: (i) a vulnerability data model that captures a variety of publicly accessible cybersecurity-related data sources; (ii) an ensemble-based ML pipeline method that self-adjusts to the best learning models for given cybersecurity tasks; and (iii) a knowledge taxonomy and its instantiated power grid and manufacturing models that capture CI common semantics of cyberphysical functional dependencies across CI networks in critical societal domains. This research contributes data-driven vulnerability analysis approaches that bridge the knowledge gaps among different security functions, such as vulnerability management through related reports analysis. This thesis also correlates vulnerability analysis findings to coordinate mitigation responses in complex CIs. More specifically, the vulnerability data model expands the vulnerability knowledge scope and curates meaningful contexts for vulnerability analysis processes. The proposed ML methods fill information gaps in vulnerability repositories using curated data while further streamlining vulnerability assessment processes. Moreover, the CI security taxonomy provides disciplined and coherent support to specify and group semanticallyrelated components and coordination mechanisms in order to harness the notorious complexity of CI networks such as those prevalent in power grids and manufacturing infrastructures. These approaches learn through interactive processes to proactively detect and analyze vulnerabilities while facilitating actionable insights for security actors to make informed decisions.
