Backscatter-Aided NOMA V2X Communication under Channel Estimation Errors

Scientific Conference (2022, June 20)

Backscatter communications (BC) has emerged as a promising technology for providing low-powered transmissions in nextG (i.e., beyond 5G) wireless networks. The fundamental idea of BC is the possibility of ... [more ▼]

Backscatter communications (BC) has emerged as a promising technology for providing low-powered transmissions in nextG (i.e., beyond 5G) wireless networks. The fundamental idea of BC is the possibility of communications among wireless devices by using the existing ambient radio frequency signals. Non-orthogonal multiple access (NOMA) has recently attracted significant attention due to its high spectral efficiency and massive connectivity. This paper proposes a new optimization framework to minimize total transmit power of BC-NOMA cooperative vehicle-to-everything networks (V2XneT) while ensuring the quality of services. More specifically, the base station (BS) transmits a superimposed signal to its associated roadside units (RSUs) in the first time slot. Then the RSUs transmit the superimposed signal to their serving vehicles in the second time slot exploiting decode and forward protocol. A backscatter device (BD) in the coverage area of RSU also receives the superimposed signal and reflect it towards vehicles by modulating own information. Thus, the objective is to simultaneously optimize the transmit power of BS and RSUs along with reflection coefficient of BDs under perfect and imperfect channel state information. The problem of energy efficiency is formulated as non-convex and coupled on multiple optimization variables which makes it very complex and hard to solve. Therefore, we first transform and decouple the original problem into two sub-problems and then employ iterative sub-gradient method to obtain an efficient solution. Simulation results demonstrate that the proposed BC-NOMA V2XneT provides high energy efficiency than the conventional NOMA V2XneT without BC. [less ▲]

Emission-aware Resource Optimization Framework for Backscatter-enabled Uplink NOMA Networks

Poster (2022, June 19)

In the last decade, a sharp surge in the number of user proximity wireless devices (UPWDs) has been observed. This has increased the level of electromagnetic field (EMF) exposure of the users ... [more ▼]

In the last decade, a sharp surge in the number of user proximity wireless devices (UPWDs) has been observed. This has increased the level of electromagnetic field (EMF) exposure of the users substantially and hence, the possible physiological effects. Ambient backscatter communications (ABC) has appeared to be a promising solution to reduce the power consumption of UPWDs by converting ambient radio frequency (RF) signals into useful signals while non-orthogonal multiple access (NOMA) is a compelling multiplexing scheme for enhanced spectral efficiency. This paper utilises a novel combination of ABC and NOMA to reduce the EMF in the uplink of wireless communication systems. This contemporary approach of EMF-aware resource optimization is based on k-medoids and Silhouette analysis. To curtail the uplink EMF, a power allocation strategy is also derived by converting a non-convex problem to a convex one and solving accordingly. The numerical results exhibit that the proposed ABC, NOMA, and unsupervised learning based scheme achieves a reduction in the EMF by at least 75% in comparison to the existing solutions. [less ▲]

Area-Power Analysis of FFT Based Digital Beamforming for GEO, MEO, and LEO Scenarios

in Area-Power Analysis of FFT Based Digital Beamforming for GEO, MEO, and LEO Scenarios (2022, June 19)

Satellite communication systems can provide seamless wireless coverage directly or through complementary ground terrestrial components and are projected to be incorporated into future wireless networks ... [more ▼]

Satellite communication systems can provide seamless wireless coverage directly or through complementary ground terrestrial components and are projected to be incorporated into future wireless networks, particularly 5G and beyond networks. Increased capacity and flexibility in telecom satellite payloads based on classic radio frequency technology have traditionally translated into increased power consumption and dissipation. Much of the analog hardware in a satellite communications payload can be replaced with highly integrated digital components that are often smaller, lighter, and less expensive, as well as software reprogrammable. Digital beamforming of thousands of beams simultaneously is not practical due to the limited power available onboard satellite processors. Reduced digital beamforming power consumption would enable the deployment of a full digital payload, resulting in comprehensive user applications. Beamforming can be implemented using matrix multiplication, hybrid methodology, or a discrete Fourier transform (DFT). Implementing DFT via fast Fourier transform (FFT) reduces the power consumption, process time, hardware requirements, and chip area. Therefore, in this paper, area-power efficient FFT architectures for digital beamforming are analyzed. The area in terms of look up tables (LUTs) is estimated and compared among conventional FFT, fully unrolled FFT, and a 4-bit quantized twiddle factor (TF) FFT. Further, for the typical satellite scenarios, area, and power estimation are reported. [less ▲]

Jewish History and the Politics of Digitisation

Scientific Conference (2022, June 17)

Personalized neurofeedback: a systematic comparison of self- and externally-paced training in healthy adults

Poster (2022, June 16)

Climate Risk and Price Jumps

Scientific Conference (2022, June 13)

Tagungs-Resümee

Scientific Conference (2022, June 11)

A new R package for Finite Mixture Models with an application to clustering countries with respect to COVID data

Scientific Conference (2022, June 10)

Unsupervised Learning for User Scheduling in Multibeam Precoded GEO Satellite Systems

Scientific Conference (2022, June 09)

Future generation SatCom multibeam architectures will extensively exploit full-frequency reuse schemes together with interference management techniques, such as precoding, to dramatically increase ... [more ▼]

Future generation SatCom multibeam architectures will extensively exploit full-frequency reuse schemes together with interference management techniques, such as precoding, to dramatically increase spectral efficiency performance. Precoding is very sensitive to user scheduling, suggesting a joint precoding and user scheduling design to achieve optimal performance. However, the joint design requires solving a highly complex optimization problem which is unreasonable for practical systems. Even for suboptimal disjoint scheduling designs, the complexity is still significant. To achieve a good compromise between performance and complexity, we investigate the applicability of Machine Learning (ML) for the aforementioned problem. We propose three clustering algorithms based on Unsupervised Learning (UL) that facilitate the user scheduling decisions while maximizing the system performance in terms of throughput. Numerical simulations compare the three proposed algorithms (K-means, Hierarchical clustering, and Self-Organization) with the conventional geographic scheduling and identify the main trade-offs. [less ▲]

Development of an HPC Multi-Physics Biomass Furnace Simulation and Integration in a Cloud-based Workflow

Scientific Conference (2022, June 09)

Biomass combustion offers a credible alternative to reduce the consumption of fossil fuels. To optimize the biomass combustion process and improve the design of biomass furnaces numerical simulation is a ... [more ▼]

Biomass combustion offers a credible alternative to reduce the consumption of fossil fuels. To optimize the biomass combustion process and improve the design of biomass furnaces numerical simulation is a less expensive and time-effective approach as opposed to the experimental method. However, the combustion in a biomass furnace involves intricate physical phenomena that must be modeled (and validated) carefully, in the fuel bed (with particle motion and shrinking, heat transfer, drying, pyrolysis, gasification) and in the surrounding gas (with turbulence, combustion, radiation). With this level of complexity, and to be conducted in a reasonable time, the simulation of industrial biomass furnaces requires the use of High-Performance Computing (HPC) platforms and expertise, which is usually not affordable for manufacturing SMEs. To address this issue, we developed a configurable digital twin of a biomass furnace running on HPC and we designed a cloudified easy-to-use end-to-end workflow. This fully automated workflow, from user input to results analysis, has been integrated into the digital marketplace of the CloudiFacturing EU project and is now directly available to SMEs via a Cloud portal. With this presentation, we want to offer a glance at the internal details and enabling technologies used in our parallel coupled application and scientific workflow. Our parallel simulation tool for biomass furnaces combines OpenFOAM (for the gas phase) parallelized with MPI and XDEM (for the solid wood particles) parallelized with OpenMP. The two libraries are coupled in parallel using an original approach based on the co-located partitioning strategy which has been tailored to minimize communications. As for the cloud workflow, it is based on an all-in-one Singularity image containing all the software, scripts, and data required to prepare the simulation input, execute the computation-intensive simulation, and analyze the results. Finally, we present the lessons learned from the development of this complex workflow and highlight the remaining challenges related to HPC multi-physics coupled simulations. [less ▲]

A survey of EMI lecturer training programmes: content, delivery, ways forward.

Scientific Conference (2022, June 09)

This talk will provide insights into designing and delivering English Medium Instruction (EMI) lecturer training by surveying published initiatives worldwide (Deroey, 2021). Although EMI is not a recent ... [more ▼]

This talk will provide insights into designing and delivering English Medium Instruction (EMI) lecturer training by surveying published initiatives worldwide (Deroey, 2021). Although EMI is not a recent phenomenon, many higher education institutions are only now beginning to organize specific support for EMI lecturers. EAP practitioners are often tasked with providing such support, since the perception commonly is that language is the main issue requiring improvement. However, the efficient design and delivery of EMI lecturing training and support is a complex challenge. First, most literature highlights the need for pedagogical and communication training in addition to language work. Second the varied EMI context means training should be adapted to the local cultural, educational, linguistic and institutional contexts (Herington, 2020; Martinez & Fernandes, 2020; Tuomainen, 2018). Third, we need to be sensitive to lecturers’ attitudes towards EMI and EMI training (Tsui, 2018). Fourth, there are practical considerations such as the timely provision of support (Guarda & Helm, 2017); promoting participation; facilitating learning transfer to lectures; and working with what are usually heterogeneous participant groups in terms of English proficiency, (EMI) lecturing experience and discipline (Ball & Lindsay, 2013). Finally, the design of these programmes typically needs to happen with very limited institutional resources, few (if any) published materials and relatively little published research on lecture discourse and EMI lecturer training. Having surveyed the main components, formats and work forms of the programmes, the conclusion highlights ways forward in EMI lecturer training that emerge from this analysis. References Ball, P., & Lindsay, D. (2013). Language demands and support for English-medium instruction in tertiary education. Learning from a specific context In A. Doiz, D. Lasagabaster, & J. M. Sierra (Eds.), English-medium instruction at universities: Global challenges (pp. 44-61). Multilingual Matters. Deroey, K. L. B. (2021). Lecturer training for English Medium Instruction: what and how? In B. D. Bond, A. & M. Evans (Ed.), Innovation, exploration and transformation. Proceedings of the 2019 BALEAP Conference (pp. 245-253). Garnet. Guarda, M., & Helm, F. (2017). A survey of lecturers’ needs and feedback on EMI training. In K. Ackerley, M. Guarda, & F. Helm (Eds.), Sharing perspectives on English-medium instruction (pp. 167-194). Peter Lang. Herington, R. (2020). Observation as a tool to facilitate the professional development of teaching faculty involved in English as a Medium of Instruction: trainer and trainee perspectives. In M. L. Carrió-Pasto (Ed.), Internationalising Learning in Higher Education (pp. 65-82). IGI Global. Martinez, R., & Fernandes, K. (2020). Development of a teacher training course for English medium instruction for higher education professors in Brazil. In M. Del Mar Sánchez-Pérez (Ed.), Teacher Training for English-Medium Instruction in Higher Education (pp. 125-152). IGI Global. Tuomainen, S. (2018). Supporting non-native university lecturers with English-medium instruction. Journal of Applied Research in Higher Education, 10(3), 230-242. [less ▲]

A CutFEM Method for a Mechanistic Modelling of Astrocytic Metabolism in 3D Physiological Morphologies

Scientific Conference (2022, June 07)

Investigating neurodegenerative diseases can be done complementary through biological and computational experiments. A good computational approach describing a simplification of the reality and focusing ... [more ▼]

Investigating neurodegenerative diseases can be done complementary through biological and computational experiments. A good computational approach describing a simplification of the reality and focusing only on some features of the problem can help getting insights on the field. The question addressed in our work is the role of astrocytes in neurodegeneration. These cells have two interesting characteristics that we want to investigate in our model: first, their role as metabolic mediator between neurons and blood vessels and second, their peculiar morphology. In fact, metabolic dysfunctions and morphological changes have been noticed in astrocyte affected by neuropathology. Computationally the main difficulty arising from solving a metabolic model into cellular shape comes from the complexity of the domain. The shape of astrocytes are very ramified, with thin branches and sharp edges. As shown in our previous work \cite{Farina}, a \cutfem{} \cite{Burman} approach is a suitable tool to deal with this issue. In our latest work we use real human three-dimensional astrocyte morphologies obtained via microscopy \cite{Salamanca} as domain to solve our system. The performed simulations highlight the effect of morphological changes on the system output. Suggesting that our model can be crucial in understanding the morphological-dependency in neuropathologies and that the spatial component cannot be neglected. [less ▲]

Data Protection and Consenting Communication Mechanisms: Current Proposals and Challenges

in IEEE eXplore (2022, June 06)

Data Protection and Consenting Communication Mechanisms (DPCCMs) have the potential of becoming one of the most fundamental means of protecting humans’ privacy and agency. However, they are yet to be ... [more ▼]

Data Protection and Consenting Communication Mechanisms (DPCCMs) have the potential of becoming one of the most fundamental means of protecting humans’ privacy and agency. However, they are yet to be improved, adopted and enforced. In this paper, based on the results of a technical document analysis and an expert study, we we identify some of the main technical factors that can be comparison factors between some of the main interdisciplinary challenges of a Human-centric, Accountable, Lawful, and Ethical practice of personal data processing on the Internet and discuss whether the current DPCCMs proposal can contribute towards their resolution. In particular, we discuss the two current open specifications, i.e. the Advanced Data Protection Control (ADPC) and the Global Privacy Control (GPC) based on the identified challenges. [less ▲]

Predicting depression in old age: Combining life course data with machine learning

Scientific Conference (2022, June 03)

Latent classes of workplace bullying exposure and perpetration and their links to personality, power and social status

Scientific Conference (2022, June 03)

Just like many school aggression researchers (see the review of studies in Olivier et al., 2021; Smith & Steffgen, 2013), many scholars investigating workplace bullying assume the existence of four ... [more ▼]

Just like many school aggression researchers (see the review of studies in Olivier et al., 2021; Smith & Steffgen, 2013), many scholars investigating workplace bullying assume the existence of four classes of employees: Uninvolved employees, victims, perpetrator, and provocative victims (also called ‘bully-victims’; e.g., Zapf & Einarsen, 2020). Yet, empirical evidence supporting these four classes is lacking so far. Instead, studies on workplace bullying mostly focused solely on the victim perspective (Einarsen et al., 2020; see also the review of studies in Gupta et al., 2020), while far less studies investigate the perpetrator perspective (see the enumerated studies in Nielsen & Einarsen, 2018). Only some studies include both perspectives (e.g., Baillien et al., 2016; Fernández-del-Río et al., 2021; Sischka et al., 2021). However, these studies applied a variable-centered approach and treated workplace bullying exposure and perpetration as separate variables. Thus, they tell us little about the interplay of workplace bullying exposure and perpetration. The current study employs a person-centered approach (i.e., latent class analysis) to identify groups of employees that show different patterns of workplace bullying involvement. Moreover, the current study aims to identify predictors of latent class membership. We investigate the individual disposition hypothesis (Nielsen & Einarsen, 2018), assuming that individual characteristics such as personality traits may be related to being involved in bullying and could therefore be typifying features of workplace bullying groups. Moreover, according to some researchers in workplace bullying, individual characteristics such as certain personality traits (big five dimensions, trait aggression, dominance) are particularly appropriate to identify and distinguish workplace bullying subgroups (Matthiesen & Einarsen, 2007; see also Nielsen et al., 2017). On the other hand, power and social status represent enabling structures (Salin, 2003) of workplace bullying, and power imbalance is often seen as a defining feature of workplace bullying (Einarsen et al., 2020). To test our hypotheses, we recruited participants via Amazon’s Mechanical Turk (MTurk; Buhrmester et al., 2011; Crump et al., 2013) to participate in an online survey. The final sample contained 1,492 respondents (53.8% females, n = 802), with ages ranging from 19 to 77 (M = 40.2, SD = 10.8). Most respondents worked full time (91.2%, n = 1,360). The survey contained the Short-Negative Acts Questionnaire (S-NAQ; Notelaers et al., 2019) that was applied from the victim as well as from the perpetrator perspective. Furthermore, we assessed the big five with the Mini-IPIP (Donnellan et al., 2006), trait aggression with the brief aggression questionnaire (Webster et al., 2014), and dominance with the domineering subscale of the Inventory of Interpersonal Problems (Soldz et al., 1995). Moreover, power and social status were assessed with a newly developed bipartite measure of social hierarchy (Yu et al, 2019). Latent class analysis was employed. Statistical fit indices, substantive interpretability and utility, as well as classification diagnostics were jointly considered to determine the number of workplace bullying classes. To explore the relationships between the latent categorical variable and the other variables (i.e., personality traits, power and social status), we followed the three-step procedure (e.g., Asparouhov & Muthén, 2014). Latent class analysis revealed four classes, i.e., (1) mild bullying involvement, (2) bully-victims (3) non-involved and (4) victims. These classes were meaningfully linked with the big five dimensions, trait aggression, dominance, power and social status. Specifically, bully-victims scored high on extraversion, neuroticism, trait aggression, dominance, power and low on status, agreeableness, conscientiousness and openness. Victims on the other hand scored also high on neuroticism and – compared with non-involved – lower on agreeableness, conscientiousness and openness and higher on trait aggression and dominance. Victims showed the lowest levels of extraversion and status. The present study implements a cross-sectional design precluding a causal interpretation. Moreover, only self-reported measures were employed. Thus, especially indicators of workplace bullying perpetration might be influence by social desirability. Scholars and policy makers need to be aware of different patterns of being involved in workplace bullying in order to create effective interventions. Personality factors as well as power and social status are important correlates of workplace bullying involvement. The current study is the first that investigates workplace bullying from a target and a perpetrator perspective by employing a person-centered approach (i.e., latent class analysis). [less ▲]

Exploring the History of Digital History: Setting an Agenda

Scientific Conference (2022, June 02)

See attached.

Unlocking web archives through metadata, seed lists and derived data

Scientific Conference (2022, June 01)

This presentation addresses the use, re-use, access and dissemination of data related to web archives. Web archives (Brügger, 2018) have been for several years in a hybrid position regarding access ... [more ▼]

This presentation addresses the use, re-use, access and dissemination of data related to web archives. Web archives (Brügger, 2018) have been for several years in a hybrid position regarding access, depending on the institutions that were preserving them. While Internet Archive has made its collections available online since 2001 through the Wayback Machine (but with limited features for scholars willing to conduct a distant reading based on data, WARC files, etc.), most national libraries only allowed an onsite access due to authors rights restrictions (and in some cases the frame of legal deposits), while starting to provide interesting metadata for research projects willing to explore them. However, the situation is currently evolving in the frame of several research projects that allow to access a vast amount of (international) metadata and datasets. Taking two research projects in progress as case studies, WARCnet and AWAC2, this paper aims to present the move towards the use of metadata and derived data related to huge collections of web archives of the COVID crisis. WARCnet (Web ARChive studies network researching web domains and events) is a network whose activities (funded by the Independent Research Fund Denmark | Humanities (grant no 9055-00005B)) run in 2020-2023. The networking activities are guided by overarching research questions, one of them being “How transnational events developed on the European web?” (and notably the COVID crisis which is explored in WG2 (https://cc.au.dk/en/warcnet/working-groups)). AWAC2 (Analysing Web Archives of the COVID Crisis through the IIPC Novel Coronavirus dataset) is a project part of the Archives Unleashed Cohort Program, that supports and facilitates research engagement with web archives. It aims to explore a unique collection of web material (https://archive-it.org/collections/13529) related to the pandemic, with contributions from over 30 members of IIPC (International Internet Preservation Consortium) as well as public nominations from over 100 individuals/institutions. May it be in terms of access or tools, both projects are currently exploring new methodologies based on broad datasets (i.e. 5,3 TB for the IIPC collection related to the COVID crisis; 9.4 GB and 8,738,751 lines for the CSV related to plain text webpages). Starting with the WARCnet project, the presentation will explain how its WG2 gathered and accessed several national European datasets of COVID web archives, their specificities as well as their heterogeneity, the first analysis conducted through a datathon on January- February 2021 (Aasman et al. 2021) and the limits and assets of such access. Within the AWAC2 project (2021-2022) the access to the international IIPC COVID collection, through Archive-It and through the cohort program developed by the Archives Unleashed Team (Netpreserve, 2021; Ruest et al., 2021), is then a new opportunity to access data through mediated interfaces (ARCH) and to go further into them. Here again the presentation will demonstrate new opportunities and show a few examples of the analysis conducted by the team. Both examples aim to present the way web archiving institutions, libraries and researchers are developing new ways of accessing and exploring web archives, while also increasing their value(s) (Schafer and Winters, 2021). References Aasman, S., Bingham, N., Brügger, N., de Wild, K., Gebeil S. & Schafer V. (2021). Chicken and Egg: Reporting from a Datathon Exploring Datasets of the COVID- 19 Special Collections, WARCnet paper, Aarhus, https://cc.au.dk/fileadmin/dac/Projekter/WARCnet/Aasman_et_al_Chicken_and_Egg.pdf Brügger, N. (2018). The Archived Web. Doing History in the Digital Age. Cambridge, MA: The MIT Press. IIPC (2021), A Retrospective with the Archives Unleashed Project, netpreserve blog, https://netpreserveblog.wordpress.com/2021/04/01/a-retrospective-with-the-archives-unleashed-project/ Ruest, N., Fritz, S., Deschamps, R. Lin, J. & Milligan, I. (2021) From archive to analysis: accessing web archives at scale through a cloud-based interface. International Journal of Digital Humanities, https://paperity.org/p/260049927/from-archive-to-analysis-accessing-web-archives-at-scale-through-a-cloud-based-interface Schafer V. & Winters J. (2021). The values of web archives, International Journal of Digital Humanities, 1-10, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8190571/ [less ▲]

Designing for Qualitative Interfaces: Experiences from Studio Education

Scientific Conference (2022, June)

Comparison of UVC and Solar-based Processes for the Simultaneous Removal of Microcontaminants and Microorganism from Urban Wastewater Effluents I.

Scientific Conference (2022, June)

Currently, the presence of microcontaminats (MCs) and pathogens in secondary municipal wastewater treatment plant effluents entails a challenge to be addressed before water discharge or reuse. In this ... [more ▼]

Currently, the presence of microcontaminats (MCs) and pathogens in secondary municipal wastewater treatment plant effluents entails a challenge to be addressed before water discharge or reuse. In this work UVC (UVC/S2O82-, UVC/H2O2) and solar-based processes (solar/S2O82- and solar/H2O2) are proposed as tertiary treatments for the simultaneous removal of both, MCs and pathogens, comparing their efficiency aiming to find the most suitable solution. The microorganisms studied were Escherichia coli, Enterococcus faecalis and Salmonella enteritidis in a concentration of 103 CFU mL-1 each and a mixture of 6 MCs (acetaminophen, caffeine, carbamazepine, trimethoprim, sulfamethoxazole and diclofenac) each at 100 μg L-1 of initial concentration, using simulated wastewater treatment plant effluent as water matrix. The concentrations of oxidants studied were 25 and 50 mg L-1 of each, respectively. Results revealed that UVC/H2O2 at 25 mg L-1 presented the most satisfactory solution considering treatment time and addition of reagents for complete inactivation of target pathogens and 80% removal of the sum of MCs. [less ▲]

Approximating WCRT through the aggregation of short simulations with different initial conditions: application to TSN

in 30th International Conference on Real-Time Networks and Systems (RTNS ’22) (2022, June)

Assessing traversal times is the main concern in the verification of embedded real-time networks. Schedulability analysis, as it provides firm guarantees, is the preferred technique for the designers of ... [more ▼]

Assessing traversal times is the main concern in the verification of embedded real-time networks. Schedulability analysis, as it provides firm guarantees, is the preferred technique for the designers of critical systems. There are however contexts where it is not economically or technically feasible to develop one, typically when the software and hardware components have not been designed with predictability in mind, e.g. as soon as TCP-based traffic is involved in network communication or when the hardware platform is too complex (e.g. heterogeneous System-on-Chips). In this paper, we study if it is possible to improve the ability of simulation to observe large traversal times, by running many short simulations with appropriately chosen simulation time and varying initial offsets of the stations on the network. The de-facto standard approach to assess maximal traversal times is to run a single long simulation with synchronized node start offsets and to use randomized node clock drifts inside an acceptable range. This approach is known to yield high traversal times but is not parallelizable. We propose an alternative approach consisting in splitting the simulation time over multiple shorter simulations with, optionally, randomized node start offsets. We evaluate the optimization potential of this simple approach on several realistic network configurations by comparing long simulations to aggregated short simulations, with and without synchronized node start offsets. We observe, considering all flows, that this allows a median improvement of up to 21.3% in terms of maximum traversal time observed, for the same simulation time budget. Additional randomization of the node start offsets showed further improvements of up to 4.8% in our experiments. Results from this line of work can be used to estimate the pessimism of schedulability analyses and verify systems for which no analysis is available. [less ▲]

Relative State Estimation for LEO Formations with Large Inter-satellite Distances Using Single-Frequency GNSS Receivers

Scientific Conference (2022, June)

Relative baseline estimation is an integral part of satellite formation flying missions. GNSS-based relativepositioning has been a dominating technology for formation missions in LEO, where very precise ... [more ▼]

Relative baseline estimation is an integral part of satellite formation flying missions. GNSS-based relativepositioning has been a dominating technology for formation missions in LEO, where very precise estimatescould be obtained for formations with small inter-satellite distances (1 − 10 km). Larger baselines betweenthe satellites (> 10 km) pose the problem of considerable differences in the ionospheric delays experiencedby the signals received by each receiver. This problem could be mitigated by using precise ionospheric-freecombinations that could only be obtained by dual-frequency receivers, which is not a cost-efficient optionfor modern low-cost miniature missions. In this paper, the problem of relative baseline vector estimation isaddressed for formation missions with large inter-satellite distances equipped with single-frequency receivers.The problem is approached using the space-proven relatively simple Extended Kalman Filter with anadvantageous setting for the observation vector [less ▲]

Konzept, Methodik und Perspektiven eines digitalen historischen Stadtatlas - das Beispiel Luxemburg

Scientific Conference (2022, June)

The historical atlas of the city of Luxembourg has been accessible on the internet since 2019. Since then, it has been continuously expanded, revised and improved, both technically and in terms of content ... [more ▼]

The historical atlas of the city of Luxembourg has been accessible on the internet since 2019. Since then, it has been continuously expanded, revised and improved, both technically and in terms of content. Users currently have the opportunity to view a large number of historical old maps and aerial photographs from Luxembourg archives for the period between 1560 and 2017 at zoom levels of their choice and to compare them with each other on transparent layers, precisely fitting one above the other. In addition, historical photos and views as well as explanatory texts on the city's history and on selected buildings or other infrastructure elements can be displayed. In order to realise the advantages of a web publication in the best possible way, the Luxatlas is based on open source software. This enables the development of customised WebGIS applications for the specific requirements of the project.In addition to the project presentation, the presentation will also highlight the methodological and source-critical challenges and put them up for discussion. [less ▲]

Die zweifache Rechtfertigung des ‚Bösewichts‘: Figurationen des Bösen bei Schiller

Scientific Conference (2022, June)

LuxemBERT: Simple and Practical Data Augmentation in Language Model Pre-Training for Luxembourgish

in Proceedings of the Language Resources and Evaluation Conference, 2022 (2022, June)

Pre-trained Language Models such as BERT have become ubiquitous in NLP where they have achieved state-of-the-art performance in most NLP tasks. While these models are readily available for English and ... [more ▼]

Pre-trained Language Models such as BERT have become ubiquitous in NLP where they have achieved state-of-the-art performance in most NLP tasks. While these models are readily available for English and other widely spoken languages, they remain scarce for low-resource languages such as Luxembourgish. In this paper, we present LuxemBERT, a BERT model for the Luxembourgish language that we create using the following approach: we augment the pre-training dataset by considering text data from a closely related language that we partially translate using a simple and straightforward method. We are then able to produce the LuxemBERT model, which we show to be effective for various NLP tasks: it outperforms a simple baseline built with the available Luxembourgish text data as well the multilingual mBERT model, which is currently the only option for transformer-based language models in Luxembourgish. Furthermore, we present datasets for various downstream NLP tasks that we created for this study and will make available to researchers on request. [less ▲]

COMPETITION AND COOPERATION BETWEEN SUPPLIERS IN MULTIMODAL NETWORK DESIGN PROBLEMS

Scientific Conference (2022, June)

Robust Approach for Urban Road Surface Extraction Using Mobile Laser Scanning Data

in Robust Approach for Urban Road Surface Extraction Using Mobile Laser Scanning Data (2022, June)

Road surface extraction is crucial for 3D city analysis. Mobile laser scanning (MLS) is the most appropriate data acquisition system for the road environment because of its efficient vehicle-based on-road ... [more ▼]

Road surface extraction is crucial for 3D city analysis. Mobile laser scanning (MLS) is the most appropriate data acquisition system for the road environment because of its efficient vehicle-based on-road scanning opportunity. Many methods are available for road pavement, curb and roadside way extraction. Most of them use classical approaches that do not mitigate problems caused by the presence of noise and outliers. In practice, however, laser scanning point clouds are not free from noise and outliers, and it is apparent that the presence of a very small portion of outliers and noise can produce unreliable and non-robust results. A road surface usually consists of three key parts: road pavement, curb and roadside way. This paper investigates the problem of road surface extraction in the presence of noise and outliers, and proposes a robust algorithm for road pavement, curb, road divider/islands, and roadside way extraction using MLS point clouds. The proposed algorithm employs robust statistical approaches to remove the consequences of the presence of noise and outliers. It consists of five sequential steps for road ground and non-ground surface separation, and road related components determination. Demonstration on two different MLS data sets shows that the new algorithm is efficient for road surface extraction and for classifying road pavement, curb, road divider/island and roadside way. The success can be rated in one experiment in this paper, where we extract curb points; the results achieve 97.28%, 100% and 0.986 of precision, recall and Matthews correlation coefficient, respectively. [less ▲]

Real-time large deformations: A probabilistic deep learning approach

in The 8th European Congress on Computational Methods in Applied Sciences and Engineering (2022, June)

Semantic and Interactive Search in an Advanced Note-Taking App for Learning Material

in Proceedings of the 24th International Conference on Human-Computer Interaction (HCI International) (2022, June)

Note-taking apps on tablets are increasingly becoming the go-to space for managing learning material as a student. In particular, digital note-taking presents certain advantages over traditional pen-and ... [more ▼]

Note-taking apps on tablets are increasingly becoming the go-to space for managing learning material as a student. In particular, digital note-taking presents certain advantages over traditional pen-and-paper approaches when it comes to organizing and retrieving a library of notes thanks to various search functionalities. This paper presents improvements to the classic textual-input-based search field, by introducing a semantic search that considers the meaning of a user’s search terms and an automatic question-answering process that extracts the answer to the user’s question from their notes for more efficient information retrieval. Additionally, visual methods for finding specific notes are proposed, which do not require the input of text by the user: through the integration of a semantic similarity metric, notes similar to a selected document can be displayed based on common topics. Furthermore, a fully interactive process allows one to search for notes by selecting different types of dynamically generated filters, thus eliminating the need for textual input. Finally, a graph-based visualization is explored for the search results, which clusters semantically similar notes closer together to relay additional information to the user besides the raw search results. [less ▲]

Feasibility of Advanced Oxidation Processes as an upgrade for Microcontaminants removal at municipal Wastewater Treatment Plants

Scientific Conference (2022, June)

Benzotriazole, carbamazepine, clarithromycin and diclofenac have been identified as microcontaminants of concern in Luxembourgish wastewaters, thus the implementation of photo-Fenton processes at natural ... [more ▼]

Benzotriazole, carbamazepine, clarithromycin and diclofenac have been identified as microcontaminants of concern in Luxembourgish wastewaters, thus the implementation of photo-Fenton processes at natural pH has been proposed for their removal. In the present work, the effectiveness of a pilot scale photo-Fenton system (500W Medium Pressure) has been evaluated according to the reagent dosage and toxicity of the treated effluent. With this treatment, 80% degradation is achieved in 15 minutes even with 5 and 3 mg/L of iron (40 mg/L H2O2), but 5 mg/L can have a negative effect on the growth of Sorghum saccharatum in Phytotoxicity tests. In comparison UV-C/H2O2 (40W Low Pressure; 40 mg/L H2O2) process needs longer treatment time and generates degradation by-products causing a growth inhibition of Sorghum saccharatum. The combination of both lamps can lead to a better performance of the reagents allowing to reach the 80% target in less time and to reduce the dosage. [less ▲]

Multicultural conviviality in the context of active ageing in Luxembourg

Scientific Conference (2022, June)

Luxembourg’s population has not only become more culturally diverse in the past years but is also growing older. Almost 20 per cent of the total population of Luxembourg is over 60 years old, of which one ... [more ▼]

Luxembourg’s population has not only become more culturally diverse in the past years but is also growing older. Almost 20 per cent of the total population of Luxembourg is over 60 years old, of which one third are non-Luxembourgers. Active ageing can make an important contribution to the quality of life of older people and promote social inclusion, whereas the feeling of not belonging can be a psychological barrier to participation in activities. This was the starting point of the PAN-VAL project on active ageing of Luxembourgers and non-Luxembourgers, which was funded by the Luxembourg Ministry of Family and Integration and carried out in collaboration between a team from the University of Luxembourg and GERO – Kompetenzzenter fir den Alter. A total of N = 1000 people over 50 (51% women, 49% men) participated in a nationally representative online and telephone survey, and a number of n = 39 in-depth qualitative interviews were carried out with participants from four selected municipalities in different parts of the Grand Duchy: Differdange in the south, Mersch in the centre and Ettelbrück and Clervaux in the north. Based on our quantitative data, we will first present a model on the relations between sense of belonging, social inclusion, loneliness and participation in social activities. Drawing on our qualitative interviews, we will further analyze how the participants describe the processes how they developed a sense of belonging to the places they live in through mundane encounters with people from their municipalities and neighborhoods. We will also explore, how older people experience conviviality with regard to the offers for active ageing, focusing in particular on barriers and facilitators for participation in such offers. Policy implications and lessons learnt about how to adapt social offers to the diverse needs of an increasingly heterogeneous target group will be discussed. [less ▲]

On the Reduction of Computational Costs for Tungsten Powder Bed Processes

Scientific Conference (2022, May 31)

During the Discrete Element Method (DEM) representation of powder bed processes (e.g. tungsten oxide reduction, tungsten carbide synthesis, selective laser sintering) a numerical solution for each single ... [more ▼]

During the Discrete Element Method (DEM) representation of powder bed processes (e.g. tungsten oxide reduction, tungsten carbide synthesis, selective laser sintering) a numerical solution for each single particle is impractical due to the extremely high number of particles (e.g. 10^12). However, in such processes, particles in the vicinity of each other observe low gradients concerning their thermodynamic state. This characteristic can be exploited to avoid solving repeatedly numerically equivalent equation systems. This contribution presents two numerical methods aiming to reduce the computational costs of DEM approaches for the thermochemical conversion of powder beds. In the two methods after an appropriated numerical treatment, a group of particles under similar boundary conditions is substituted by a single-effective-entity. Consequently, the entire powder space is divided into sub-domains to be solved. The methods result in considerable lower number of equations that increase computational efficiency and enable feasible time simulations. The applications of the industrial synthesis of tungsten powders and the selective laser sintering (SLS) of powder metals are presented and discussed. [less ▲]

MATERIAL MODELLING AND FINITE ELEMENT ANALYSIS IN METAL ADDITIVE MANUFACTURING

Poster (2022, May 31)

The additive manufacturing (AM) is competent method for the manufacturing of complex metal parts with wider process flexibility. During manufacturing, the metal part repetitively undergoes heating and ... [more ▼]

The additive manufacturing (AM) is competent method for the manufacturing of complex metal parts with wider process flexibility. During manufacturing, the metal part repetitively undergoes heating and cooling under the influence of laser passes and ambient conditions respectively. In turn, the material experiences the thermal strain and residual stress. The aim of the work is to predict them using certain material model. Where the solidified metal part from melt-pool is considered in current analysis. For numerical simulation, Finite Element Method (FEM) is chosen. The heat equation is first solved for thermal profile of AM Process. Afterwards, the structural analysis is performed with such thermal load. The non linear constitutive material model is utilised. For concerned material model, the temperature dependence upon the material properties is also implemented. The resulting Finite Element Analysis (FEA) platform offers the macro-scale thermal solution and the prediction of resulting plastic distortion in material. This prediction however has become more accurate when the variable material property, depending upon the temperature of analysis zone, is introduced. [less ▲]

Guiding Refugees Through European Bureaucracy: Designing a Trustworthy Mobile App for Document Management

in Drechsler, A.; Gerber, A.; Hevner, A. (Eds.) The Transdisciplinary Reach of Design Science Research. DESRIST 2022 (2022, May 25)

After being granted asylum in European countries, refugees need to go through a multitude of administrative processes before they can participate in society. However, these processes are often challenging ... [more ▼]

After being granted asylum in European countries, refugees need to go through a multitude of administrative processes before they can participate in society. However, these processes are often challenging, as refugees struggle to understand them, lack instructions for managing paperwork, and do not possess the required language skills. Prior research emphasizes the role of information and communication technologies to simplify and enable refugee-friendly administrative processes. However, recent research and existing applications mainly focus on information retrieval and do not offer assistance for understanding official letters, completing administrative forms, and managing corresponding documents. Furthermore, refugees are often reluctant to use existing applications as they do not trust their host country’s governments and public authorities. In this research, we aim to address this functional and trust gap. We follow a design science research approach to develop a design for a refugee-centric and trustworthy mobile application that assists refugees along administrative processes. In doing so, we identify three design principles that may guide the development of such applications for refugees. [less ▲]

A Cybersecurity Incident: Who You Gonna Call?

Scientific Conference (2022, May 25)

TriggerZoo: A Dataset of Android Applications Automatically Infected with Logic Bombs

in 19th International Conference on Mining Software Repositories, Data Showcase, (MSR 2022) (2022, May 23)

Many Android apps analyzers rely, among other techniques, on dynamic analysis to monitor their runtime behavior and detect potential security threats. However, malicious developers use subtle, though ... [more ▼]

Many Android apps analyzers rely, among other techniques, on dynamic analysis to monitor their runtime behavior and detect potential security threats. However, malicious developers use subtle, though efficient, techniques to bypass dynamic analyzers. Logic bombs are examples of popular techniques where the malicious code is triggered only under specific circumstances, challenging comprehensive dynamic analyses. The research community has proposed various approaches and tools to detect logic bombs. Unfortunately, rigorous assessment and fair comparison of state-of-the-art techniques are impossible due to the lack of ground truth. In this paper, we present TriggerZoo, a new dataset of 406 Android apps containing logic bombs and benign trigger-based behavior that we release only to the research community using authenticated API. These apps are real-world apps from Google Play that have been automatically infected by our tool AndroBomb. The injected pieces of code implementing the logic bombs cover a large pallet of realistic logic bomb types that we have manually characterized from a set of real logic bombs. Researchers can exploit this dataset as ground truth to assess their approaches and provide comparisons against other tools. [less ▲]

GraphCode2Vec: generic code embedding via lexical and program dependence analyses

in Proceedings of the 19th International Conference on Mining Software Repositories (2022, May 22)

Code embedding is a keystone in the application of machine learn- ing on several Software Engineering (SE) tasks. To effectively support a plethora of SE tasks, the embedding needs to capture program ... [more ▼]

Code embedding is a keystone in the application of machine learn- ing on several Software Engineering (SE) tasks. To effectively support a plethora of SE tasks, the embedding needs to capture program syntax and semantics in a way that is generic. To this end, we propose the first self-supervised pre-training approach (called GraphCode2Vec) which produces task-agnostic embedding of lexical and program dependence features. GraphCode2Vec achieves this via a synergistic combination of code analysis and Graph Neural Networks. GraphCode2Vec is generic, it allows pre-training, and it is applicable to several SE downstream tasks. We evaluate the effectiveness of GraphCode2Vec on four (4) tasks (method name prediction, solution classification, mutation testing and overfitted patch classification), and compare it with four (4) similarly generic code embedding baselines (Code2Seq, Code2Vec, CodeBERT, Graph- CodeBERT) and seven (7) task-specific, learning-based methods. In particular, GraphCode2Vec is more effective than both generic and task-specific learning-based baselines. It is also complementary and comparable to GraphCodeBERT (a larger and more complex model). We also demonstrate through a probing and ablation study that GraphCode2Vec learns lexical and program dependence features and that self-supervised pre-training improves effectiveness. [less ▲]

JuCify: A Step Towards Android Code Unification for Enhanced Static Analysis

in 44th International Conference on Software Engineering (ICSE 2022) (2022, May 21)

Native code is now commonplace within Android app packages where it co-exists and interacts with Dex bytecode through the Java Native Interface to deliver rich app functionalities. Yet, state-of-the-art ... [more ▼]

Native code is now commonplace within Android app packages where it co-exists and interacts with Dex bytecode through the Java Native Interface to deliver rich app functionalities. Yet, state-of-the-art static analysis approaches have mostly overlooked the presence of such native code, which, however, may implement some key sensitive, or even malicious, parts of the app behavior. This limitation of the state of the art is a severe threat to validity in a large range of static analyses that do not have a complete view of the executable code in apps. To address this issue, we propose a new advance in the ambitious research direction of building a unified model of all code in Android apps. The JuCify approach presented in this paper is a significant step towards such a model, where we extract and merge call graphs of native code and bytecode to make the final model readily-usable by a common Android analysis framework: in our implementation, JuCify builds on the Soot internal intermediate representation. We performed empirical investigations to highlight how, without the unified model, a significant amount of Java methods called from the native code are ``unreachable'' in apps' call-graphs, both in goodware and malware. Using JuCify, we were able to enable static analyzers to reveal cases where malware relied on native code to hide invocation of payment library code or of other sensitive code in the Android framework. Additionally, JuCify's model enables state-of-the-art tools to achieve better precision and recall in detecting data leaks through native code. Finally, we show that by using JuCify we can find sensitive data leaks that pass through native code. [less ▲]

Les archives du Web, des sources aux données

Scientific Conference (2022, May 20)

This keynote during Humanistica 2022 aimed to retrace 15 years of evolution of web archiving and web archives' studies. It also presented some research projects like the current Hivi, WARCnet and AWAC2 ... [more ▼]

This keynote during Humanistica 2022 aimed to retrace 15 years of evolution of web archiving and web archives' studies. It also presented some research projects like the current Hivi, WARCnet and AWAC2 projects. [less ▲]

Die unfreien Befreiten. Über die lange Heimkehr der sowjetischen ZwangsarbeiterInnen aus Luxemburg.

Scientific Conference (2022, May 17)

Inna Ganschow untersucht in ihrem Vortrag die verschiedenen Typen totaler Institutionen im Sinne Erving Goffmans auf dem Weg von ZwangsarbeiterInnen aus der Sowjetunion nach Luxemburg und zurück. Von den ... [more ▼]

Inna Ganschow untersucht in ihrem Vortrag die verschiedenen Typen totaler Institutionen im Sinne Erving Goffmans auf dem Weg von ZwangsarbeiterInnen aus der Sowjetunion nach Luxemburg und zurück. Von den nationalsozialistischen Durchgangs- und Kriegsgefangenenlagern über die luxemburgischen Werk- und Ostarbeiterlager bis hin zu den sowjetischen Sammel- und Filterlagern endete die lange Reise nach Hause oft nach einigen Monaten oder Jahren erneut in einem Lager oder einer Zwangsansiedlung. Die Repatriierung junger ukrainischer, weißrussischer und russischer Frauen wird anhand von erhaltenen Dokumenten aus erster Hand, verschiedenen Lager- und Betriebsunterlagen sowie Augenzeugenberichten rekonstruiert. Die Rückführung wird im Hinblick auf ihre Funktion analysiert, die eine Bestrafung, eine Belohnung oder ein Schutz sein konnte. [less ▲]

Traffic Steering for eMBB and uRLLC Coexistence in Open Radio Access Networks

in Traffic Steering for eMBB and uRLLC Coexistence in Open Radio Access Networks (2022, May 16)

Existing radio access network (RAN) architectures are lack of sufficient openness, flexibility, and intelligence to meet the diverse demands of emerging services in beyond 5G and 6G wireless networks ... [more ▼]

Existing radio access network (RAN) architectures are lack of sufficient openness, flexibility, and intelligence to meet the diverse demands of emerging services in beyond 5G and 6G wireless networks, including enhanced mobile broadband (eMBB) and ultra-reliable and low-latency (uRLLC). Open RAN (ORAN) is a promising paradigm that allows building a virtualized and intelligent architecture. In this paper, we focus on traffic steering (TS) scheme based on multi-connectivity (MC) and network slicing (NS) techniques to efficiently allocate heterogeneous network resources in “NextG” cellular networks. We formulate the RAN resource allocation problem to simultaneously maximize the weighted sum eMBB throughput and minimize the worst-user uRLLC latency subject to QoS requirements, and orthogonality, power, and limited fronthaul constraints. Since the formulated problem is categorized as a mixed integer … [less ▲]

The NIS 2.0 Directive - Lessons learnt or lagging behind? A legal perspective

Scientific Conference (2022, May 10)

Scanning the Past: A 3D Model of Trausch's Library

Scientific Conference (2022, May 05)

Today, modern geospatial technologies and methods are widely used in combination with the documentation and preservation of objects of importance to cultural heritage. In this setting, archeologists and ... [more ▼]

Today, modern geospatial technologies and methods are widely used in combination with the documentation and preservation of objects of importance to cultural heritage. In this setting, archeologists and historians alike benefit from the rapid technological developments over the past decades, which have resulted in instrumentation that allows the capture of real objects and the generation of accurate and precise three-dimensional (3D) digital representations, i.e. models, from these sensed data. Here, the object of interest is the villa of the late historian Professor Gilbert Trausch with its library, for which a virtual library should be created for the general public. The building is an 19th century townhouse located on Limpertsberg in the City of Luxembourg and contains a cellar, three floors as well as a loft. Of particular interest were the cellar, stair cases, the first (the location of Professor Trausch’s office) and second floors as most of the bookshelves are situated there. In line with state-of-the-art approaches for 3D building modelling, a broad spectrum of modern geospatial technologies including classical surveying, Global Navigation Satellite System (GNSS), digital close-range photogrammetry and terrestrial laser scanning were employed to capture the Villa Trausch and its 33 bookshelves, i.e. Trausch’s Library, in all its details, while providing all data in one homogeneous coordinate system. Models and more photo-realistic visualizations of the exterior and interior have been obtained using, e.g., indoor images captured during the scanning. These allowed us to explore different virtual reality (VR) pathways employed by the gaming industry, for the generation of a first VR experience of the building in the sense of a digital museum. Currently solutions for the development of a public virtual library using commercial providers are investigated. [less ▲]

The Best Space Resource is the One You Can Catch and Reuse

Poster (2022, May 03)

From the beginning of space exploration more than 60 years ago, only a few in-orbit objects have been removed or reused. In fact, the Kessler Syndrome states that the number of space debris is growing ... [more ▼]

From the beginning of space exploration more than 60 years ago, only a few in-orbit objects have been removed or reused. In fact, the Kessler Syndrome states that the number of space debris is growing exponentially [1], leaving unused uncooperative objects orbiting at high velocities at several altitudes, especially in Low-Earth Orbit (LEO). In other words, the situation brings up two main critical issues: not only a non-sustainable space environment for satellite missions, with orbit saturation, but also the creation of an unsafe place for future human-related space exploration missions. Active Debris Removal is a possible solution for tackling the problem of space debris. Despite being extremely challenging, catching autonomously and harmlessly an uncooperative object tumbling at high velocity demands reliability, compliance and robustness. The fruitful collaboration between industry and academia (Spacety Luxembourg - SnT-SpaceR research group at the University of Luxembourg), is leading to the cutting-edge concept of a two-step capturing mechanism. A first ‘soft capture’ ensures that the debris is received softly while dampening any vibrations generated during the contact. Then, a ‘hard capture’ secures the debris so that it would be deorbited or safely shipped for other orbits or space stations for reuse. Capturing debris and decommissioned in-orbit objects for recycling or reusing can be the anchor of new opportunities in space and beyond. Most of the objects in orbit can have aluminum parts, besides other beneficial materials among their subsystems, such as solar panels, antennas or electronics which can be reused. To maximize space resources reusability, it is important to not harm the target. Capturing solutions such as harpoons or rigid interfaces can cause damage to the targets, resulting in hardly exploitable resources, and even more smaller debris tumbling in orbit [2]. An application of the proposed capturing technology would be to collect defunct satellites and debris, thus contributing to a more sustainable environment in space, gathering those on a possible recycling orbit or to any future Space Station for recycling. References [1] Drmola J. and Hubik T., Kessler Syndrome: System Dynamics Model (2018), In-Space Policy, 44–45, 29–39 [2] Zhao P., Liu J. and Wu C., Survey on Research and Development of On-Orbit Active Debris Removal Methods (2020), Sci China Tech Sci, 63: 2188–2210 [less ▲]

Spatio-Temporal Rainfall Estimation from Communication Satellite Data using Graph Neural Networks

Scientific Conference (2022, May)

Effective Rate of RIS-aided Networks with Location and Phase Estimation Uncertainty

in Proceedings of IEEE Wireless Communications and Networking Conference (WCNC) (2022, May)

MASS: A tool for Mutation Analysis of Space CPS

in 2022 IEEE/ACM 44st International Conference on Software Engineering (2022, May)

We present MASS, a mutation analysis tool for embedded software in cyber-physical systems (CPS). We target space CPS (e.g., satellites) and other CPS with similar characteristics (e.g., UAV). Mutation ... [more ▼]

We present MASS, a mutation analysis tool for embedded software in cyber-physical systems (CPS). We target space CPS (e.g., satellites) and other CPS with similar characteristics (e.g., UAV). Mutation analysis measures the quality of test suites in terms of the percentage of detected artificial faults. There are many mutation analysis tools available, but they are inapplicable to CPS because of scalability and accuracy challenges. To overcome such limitations, MASS implements a set of optimization techniques that enable the applicability of mutation analysis and address scalability and accuracy in the CPS context. MASS has been successfully evaluated on a large study involving embedded software systems provided by industry partners; the study includes an on-board software system managing a microsatellite currently on-orbit, a set of libraries used in deployed cubesats, and a mathematical library provided by the European Space Agency. A demo video of MASS is available at https://www.youtube.com/watch?v=gC1x9cU0-tU. [less ▲]

Preventing Frame Fingerprinting in Controller Area Network Through Traffic Mutation

in IEEE ICC 2022 Workshop - DDINS, Seoul 16-20 May 2022 (2022, May)

The continuous increase of connectivity in commercial vehicles is leading to a higher number of remote access points to the Controller Area Network (CAN) – the most popular in-vehicle network system. This ... [more ▼]

The continuous increase of connectivity in commercial vehicles is leading to a higher number of remote access points to the Controller Area Network (CAN) – the most popular in-vehicle network system. This factor, coupled with the absence of encryption in the communication protocol, poses serious threats to the security of the CAN bus. Recently, it has been demonstrated that CAN data can be reverse engineered via frame fingerprinting, i.e., identification of frames based on statistical traffic analysis. Such a methodology allows fully remote decoding of in-vehicle data and paves the way for remote pre-compiled vehicle-agnostic attacks. In this work, we propose a first solution against CAN frame fingerprinting based on mutating the traffic without applying modifications to the CAN protocol. The results show that the proposed methodology halves the accuracy of CAN frame fingerprinting. [less ▲]

Efficient Online Testing for DNN-Enabled Systems using Surrogate-Assisted and Many-Objective Optimization

in Proceedings of the 44th International Conference on Software Engineering (ICSE ’22) (2022, May)

With the recent advances of Deep Neural Networks (DNNs) in real-world applications, such as Automated Driving Systems (ADS) for self-driving cars, ensuring the reliability and safety of such DNN- enabled ... [more ▼]

With the recent advances of Deep Neural Networks (DNNs) in real-world applications, such as Automated Driving Systems (ADS) for self-driving cars, ensuring the reliability and safety of such DNN- enabled Systems emerges as a fundamental topic in software testing. One of the essential testing phases of such DNN-enabled systems is online testing, where the system under test is embedded into a specific and often simulated application environment (e.g., a driving environment) and tested in a closed-loop mode in interaction with the environment. However, despite the importance of online testing for detecting safety violations, automatically generating new and diverse test data that lead to safety violations present the following challenges: (1) there can be many safety requirements to be considered at the same time, (2) running a high-fidelity simulator is often very computationally-intensive, and (3) the space of all possible test data that may trigger safety violations is too large to be exhaustively explored. In this paper, we address the challenges by proposing a novel approach, called SAMOTA (Surrogate-Assisted Many-Objective Testing Approach), extending existing many-objective search algorithms for test suite generation to efficiently utilize surrogate models that mimic the simulator, but are much less expensive to run. Empirical evaluation results on Pylot, an advanced ADS composed of multiple DNNs, using CARLA, a high-fidelity driving simulator, show that SAMOTA is significantly more effective and efficient at detecting unknown safety requirement violations than state-of-the-art many-objective test suite generation algorithms and random search. In other words, SAMOTA appears to be a key enabler technology for online testing in practice. [less ▲]

Dynamic Bandwidth Allocation and Edge Caching Optimization for Nonlinear Content Delivery through Flexible Multibeam Satellites

in IEEE International Conference on Communications (2022, May)

The next generation multibeam satellites open up a new way to design satellite communication channels with the full flexibility in bandwidth, transmit power and beam coverage management. In this paper, we ... [more ▼]

The next generation multibeam satellites open up a new way to design satellite communication channels with the full flexibility in bandwidth, transmit power and beam coverage management. In this paper, we exploit the flexible multibeam satellite capabilities and the geographical distribution of users to improve the performance of satellite-assisted edge caching systems. Our aim is to jointly optimize the bandwidth allocation in multibeam and caching decisions at the edge nodes to address two important problems: i) cache feeding time minimization and ii) cache hits maximization. To tackle the non-convexity of the joint optimization problem, we transform the original problem into a difference-of-convex (DC) form, which is then solved by the proposed iterative algorithm whose convergence to at least a local optimum is theoretically guaranteed. Furthermore, the effectiveness of the proposed design is evaluated under the realistic beams coverage of the satellite SES-14 and Movielens data set. Numerical results show that our proposed joint design can reduce the caching feeding time by 50% and increase the cache hit ratio (CHR) by 10% to 20% compared to existing solutions. Furthermore, we examine the impact of multispot beams and multicarrier wide-beam on the joint design and discuss potential research directions. [less ▲]

A Collaborative System of Flying and Ground Robots with Universal Physical Coupling Interface (PCI), and the Potential Interactive Applications

in CHI EA '22: Extended Abstracts of the 2022 CHI Conference on Human Factors in Computing Systems (2022, April 28)

Flying and ground robots complement each other in terms of their advantages and disadvantages. We propose a collaborative system combining flying and ground robots, using a universal physical coupling ... [more ▼]

Flying and ground robots complement each other in terms of their advantages and disadvantages. We propose a collaborative system combining flying and ground robots, using a universal physical coupling interface (PCI) that allows for momentary connections and disconnections between multiple robots/devices. The proposed system may better utilize the complementary advantages of both flying and ground robots. We also describe various potential scenarios where such a system could be of benefit to interact with humans - namely, remote field works and rescue missions, transportation, healthcare, and education. Finally, we discuss the opportunities and challenges of such systems and consider deeper questions which should be studied in future work. [less ▲]