| 1. |
- Bruno, Barbara, et al.
(författare)
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Paving the Way for Culturally Competent Robots : a Position Paper
- 2017
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Ingår i: 2017 26th IEEE International Symposium on Robot and Human Interactive Communication (RO-MAN). - New York : Institute of Electrical and Electronics Engineers (IEEE). - 9781538635186 - 9781538635193 ; , s. 553-560
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Konferensbidrag (refereegranskat)abstract
- Cultural competence is a well known requirementfor an effective healthcare, widely investigated in thenursing literature. We claim that personal assistive robotsshould likewise be culturally competent, aware of generalcultural characteristics and of the different forms they take indifferent individuals, and sensitive to cultural differences whileperceiving, reasoning, and acting. Drawing inspiration fromexisting guidelines for culturally competent healthcare and thestate-of-the-art in culturally competent robotics, we identifythe key robot capabilities which enable culturally competentbehaviours and discuss methodologies for their developmentand evaluation.
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| 2. |
- Sgorbissa, Antonio, et al.
(författare)
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CARESSES : The Flower that Taught Robots about Culture
- 2019
-
Ingår i: HRI '19. - : IEEE. - 9781538685556 ; , s. 371-371
-
Konferensbidrag (refereegranskat)abstract
- The video describes the novel concept of "culturally competent robotics", which is the main focus of the project CARESSES (Culturally-Aware Robots and Environmental Sensor Systems for Elderly Support). CARESSES a multidisciplinary project whose goal is to design the first socially assistive robots that can adapt to the culture of the older people they are taking care of. Socially assistive robots are required to help the users in many ways including reminding them to take their medication, encouraging them to keep active, helping them keep in touch with family and friends. The video describes a new generation of robots that will perform their actions with attention to the older person's customs, cultural practices and individual preferences.
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| 3. |
- Al-Dulaimy, Auday, et al.
(författare)
-
Fault Tolerance in Cloud Manufacturing : An Overview
- 2023
-
Ingår i: Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST. - : Springer Science and Business Media Deutschland GmbH. - 9783031318900 ; , s. 89-101
-
Konferensbidrag (refereegranskat)abstract
- Utilizing edge and cloud computing to empower the profitability of manufacturing is drastically increasing in modern industries. As a result of that, several challenges have raised over the years that essentially require urgent attention. Among these, coping with different faults in edge and cloud computing and recovering from permanent and temporary faults became prominent issues to be solved. In this paper, we focus on the challenges of applying fault tolerance techniques on edge and cloud computing in the context of manufacturing and we investigate the current state of the proposed approaches by categorizing them into several groups. Moreover, we identify critical gaps in the research domain as open research directions. © 2023, ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering.
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| 4. |
- Al-Dulaimy, Auday, et al.
(författare)
-
LOOPS : A Holistic Control Approach for Resource Management in Cloud Computing
- 2021
-
Ingår i: ICPE 2021 - Proceedings of the ACM/SPEC International Conference on Performance Engineering. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450381949 ; , s. 117-124
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Konferensbidrag (refereegranskat)abstract
- In cloud computing model, resource sharing introduces major benefits for improving resource utilization and total cost of ownership, but it can create technical challenges on the running performance. In practice, orchestrators are required to allocate sufficient physical resources to each Virtual Machine (VM) to meet a set of predefined performance goals. To ensure a specific service level objective, the orchestrator needs to be equipped with a dynamic tool for assigning computing resources to each VM, based on the run-Time state of the target environment. To this end, we present LOOPS, a multi-loop control approach, to allocate resources to VMs based on the service level agreement (SLA) requirements and the run-Time conditions. LOOPS is mainly composed of one essential unit to monitor VMs, and three control levels to allocate resources to VMs based on requests from the essential node. A tailor-made controller is proposed with each level to regulate contention among collocated VMs, to reallocate resources if required, and to migrate VMs from one host to another. The three levels work together to meet the required SLA. The experimental results have shown that the proposed approach can meet applications' performance goals by assigning the resources required by cloud-based applications.
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| 5. |
- Al-Dulaimy, Auday, et al.
(författare)
-
TOLERANCER : A fault tolerance approach for cloud manufacturing environments
- 2022
-
Ingår i: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA. - : Institute of Electrical and Electronics Engineers Inc.. - 9781665499965
-
Konferensbidrag (refereegranskat)abstract
- The paper presents an approach to solve the software and hardware related failures in edge-cloud environments, more precisely, in cloud manufacturing environments. The proposed approach, called TOLERANCER, is composed of distributed components that continuously interact in a peer to peer fashion. Such interaction aims to detect stress situations or node failures, and accordingly, TOLERANCER makes decisions to avoid or solve any potential system failures. The efficacy of the proposed approach is validated through a set of experiments, and the performance evaluation shows that it responds effectively to different faults scenarios.
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| 6. |
- Alhashimi, Anas, et al.
(författare)
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Change-Point and Model Estimation with Heteroskedastic Noise and Unknown Model Structure
- 2023
-
Ingår i: Int. Conf. Control, Decis. Inf. Technol., CoDIT. - : Institute of Electrical and Electronics Engineers Inc.. - 9798350311402 ; , s. 2126-2132
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we investigate the problem of modeling time-series as a process generated through (i) switching between several independent sub-models; (ii) where each sub-model has heteroskedastic noise, and (iii) a polynomial bias, describing nonlinear dependency on system input. First, we propose a generic nonlinear and heteroskedastic statistical model for the process. Then, we design Maximum Likelihood (ML) parameters estimation method capable of handling heteroscedasticity and exploiting constraints on model structure. We investigate solving the intractable ML optimization using population-based stochastic numerical methods. We then find possible model change-points that maximize the likelihood without over-fitting measurement noise. Finally, we verify the usefulness of the proposed technique in a practically relevant case study, the execution-time of odometry estimation for a robot operating radar sensor, and evaluate the different proposed procedures using both simulations and field data.
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| 7. |
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| 8. |
- Ameri, Afshin, et al.
(författare)
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Interplay of Human and AI Solvers on a Planning Problem
- 2023
-
Ingår i: Conf. Proc. IEEE Int. Conf. Syst. Man Cybern.. - : Institute of Electrical and Electronics Engineers Inc.. - 9798350337020 ; , s. 3166-3173
-
Konferensbidrag (refereegranskat)abstract
- With the rapidly growing use of Multi-Agent Systems (MASs), which can exponentially increase the system complexity, the problem of planning a mission for MASs became more intricate. In some MASs, human operators are still involved in various decision-making processes, including manual mission planning, which can be an ineffective approach for any non-trivial problem. Mission planning and re-planning can be represented as a combinatorial optimization problem. Computing a solution to these types of problems is notoriously difficult and not scalable, posing a challenge even to cutting-edge solvers. As time is usually considered an essential resource in MASs, automated solvers have a limited time to provide a solution. The downside of this approach is that it can take a substantial amount of time for the automated solver to provide a sub-optimal solution. In this work, we are interested in the interplay between a human operator and an automated solver and whether it is more efficient to let a human or an automated solver handle the planning and re-planning problems, or if the combination of the two is a better approach. We thus propose an experimental setup to evaluate the effect of having a human operator included in the mission planning and re-planning process. Our tests are performed on a series of instances with gradually increasing complexity and involve a group of human operators and a metaheuristic solver based on a genetic algorithm. We measure the effect of the interplay on both the quality and structure of the output solutions. Our results show that the best setup is to let the operator come up with a few solutions, before letting the solver improve them.
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| 9. |
- Angelopoulos, Konstantinos, et al.
(författare)
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Model predictive control for software systems with CobRA
- 2016
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Ingår i: Proceedings - 11th International Symposium on Software Engineering for Adaptive and Self-Managing Systems, SEAMS 2016. - New York, NY, USA : ACM. - 9781450341875 ; , s. 35-46
-
Konferensbidrag (refereegranskat)abstract
- Self-adaptive software systems monitor their operation and adapt when their requirements fail due to unexpected phenomena in their environment. This paper examines the case where the environment changes dynamically over time and the chosen adaptation has to take into account such changes. In control theory, this type of adaptation is known as Model Predictive Control and comes with a well-developed theory and myriads of successful applications. The paper focuses on modelling the dynamic relationship between requirements and possible adaptations. It then proposes a controller that exploits this relationship to optimize the satisfaction of requirements relative to a cost-function. This is accomplished through a model-based framework for designing self-adaptive software systems that can guarantee a certain level of requirements satisfaction over time, by dynamically composing adaptation strategies when necessary. The proposed framework is illustrated and evaluated through a simulation of the Meeting-Scheduling System exemplar.
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| 10. |
- Ayala, I., et al.
(författare)
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ProDSPL : Proactive self-adaptation based on Dynamic Software Product Lines
- 2021
-
Ingår i: Journal of Systems and Software. - : Elsevier Inc.. - 0164-1212 .- 1873-1228. ; 175
-
Tidskriftsartikel (refereegranskat)abstract
- Dynamic Software Product Lines (DSPLs) are a well-accepted approach to self-adaptation at runtime. In the context of DSPLs, there are plenty of reactive approaches that apply countermeasures as soon as a context change happens. In this paper we propose a proactive approach, PRODSPL, that exploits an automatically learnt model of the system, anticipates future variations of the system and generates the best DSPL configuration that can lessen the negative impact of future events on the quality requirements of the system. Predicting the future fosters adaptations that are good for a longer time and therefore reduces the number of reconfigurations required, making the system more stable. PRODSPL formulates the problem of the generation of dynamic reconfigurations as a proactive controller over a prediction horizon, which includes a mapping of the valid configurations of the DSPL into linear constraints. Our approach is evaluated and compared with a reactive approach, DAGAME, also based on a DSPL, which uses a genetic algorithm to generate quasi-optimal feature model configurations at runtime. PRODSPL has been evaluated using a strategy mobile game and a set of randomly generated feature models. The evaluation shows that PRODSPL gives good results with regard to the quality of the configurations generated when it tries anticipate future events. Moreover, in doing so, PRODSPL enforces the system to make as few reconfigurations as possible.
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| 11. |
- Ayala, Inmaculada, et al.
(författare)
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ProDSPL : Proactive Self-Adaptation Based on Dynamic Software Product Lines
- 2021
-
Ingår i: Proceedings of the 25th ACM International Systems and Software Product Line Conference - Volume A. - New York, NY, USA : Association for Computing Machinery. - 9781450384698
-
Konferensbidrag (refereegranskat)abstract
- This is an extended abstract of the article: Inmaculada Ayala, Alessandro V. Papadopoulos, Mercedes Amor, Lidia Fuentes, ProDSPL: Proactive self-adaptation based on Dynamic Software Product Lines, Journal of Systems and Software, Volume 175, 2021, 110909, ISSN 0164-1212, https://doi.org/10.1016/j.jss.2021.110909.
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| 12. |
- Ayala, Inmaculada, et al.
(författare)
-
Self-adapting Industrial Augmented Reality applications with proactive Dynamic Software Product Lines
- 2021
-
Ingår i: 26th IEEE International Conference on Emerging Technologies and Factory Automation ETFA 2021. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781728129891
-
Konferensbidrag (refereegranskat)abstract
- Industrial Augmented Reality (IAR) is a key enabling technology for Industry 4.0. However, its adoption poses several challenges because it requires the execution of computing-intensive tasks in devices with poor computational resources, which contributes to a faster draining of the device batteries. Proactive self-adaptation techniques could overcome these problems that affect the quality of experience by optimizing computational resources and minimizing user disturbance. In this work, we propose to apply ProDSPL, a proactive Dynamic Software Product Line, for the self-adaptation of IAR applications to satisfy the quality requirements. ProDSPL is compared against MODAGAME, a multi-objective DSPL approach that uses a genetic algorithm to generate quasi-optimal feature model configurations at runtime. The evaluation with randomly generated feature models running on mobile devices shows that ProDSPL gives results closer to the Pareto optimal than MODAGAME.
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| 13. |
- Bettegowda, Chetan, et al.
(författare)
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Detection of circulating tumor DNA in early- and late-stage human malignancies
- 2014
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Ingår i: Science Translational Medicine. - : American Association for the Advancement of Science (AAAS). - 1946-6234 .- 1946-6242. ; 6:224, s. 224ra24-
-
Tidskriftsartikel (refereegranskat)abstract
- The development of noninvasive methods to detect and monitor tumors continues to be a major challenge in oncology. We used digital polymerase chain reaction-based technologies to evaluate the ability of circulating tumor DNA (ctDNA) to detect tumors in 640 patients with various cancer types. We found that ctDNA was detectable in >75% of patients with advanced pancreatic, ovarian, colorectal, bladder, gastroesophageal, breast, melanoma, hepatocellular, and head and neck cancers, but in less than 50% of primary brain, renal, prostate, or thyroid cancers. In patients with localized tumors, ctDNA was detected in 73, 57, 48, and 50% of patients with colorectal cancer, gastroesophageal cancer, pancreatic cancer, and breast adenocarcinoma, respectively. ctDNA was often present in patients without detectable circulating tumor cells, suggesting that these two biomarkers are distinct entities. In a separate panel of 206 patients with metastatic colorectal cancers, we showed that the sensitivity of ctDNA for detection of clinically relevant KRAS gene mutations was 87.2% and its specificity was 99.2%. Finally, we assessed whether ctDNA could provide clues into the mechanisms underlying resistance to epidermal growth factor receptor blockade in 24 patients who objectively responded to therapy but subsequently relapsed. Twenty-three (96%) of these patients developed one or more mutations in genes involved in the mitogen-activated protein kinase pathway. Together, these data suggest that ctDNA is a broadly applicable, sensitive, and specific biomarker that can be used for a variety of clinical and research purposes in patients with multiple different types of cancer.
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| 14. |
- Bini, E., et al.
(författare)
-
Optimal Reference Tracking for Sampled-Data Control Systems
- 2022
-
Ingår i: Proceedings of the IEEE Conference on Decision and Control. - : Institute of Electrical and Electronics Engineers Inc.. - 9781665467612 ; , s. 7141-7148
-
Konferensbidrag (refereegranskat)abstract
- It is a standard engineering practice to design feedback-based control to have a system follow a given trajectory. While the trajectory is continuous-time, the sequence of references is varied at discrete times as it is normally computed by digital systems.In this work, we propose a method to determine the optimal discrete-time references to be applied over a time window of a given duration. The optimality criterion is the minimization of a weighted L2 norm between the achieved trajectory and a given target trajectory which is desired to be followed. The proposed method is then assessed over different simulation results, analyzing the design parameters' effects, and over a UAV use case. The code to reproduce the results is publicly available.
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| 15. |
- Bousquet, Jean, et al.
(författare)
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ARIA digital anamorphosis : Digital transformation of health and care in airway diseases from research to practice
- 2021
-
Ingår i: Allergy. European Journal of Allergy and Clinical Immunology. - : John Wiley & Sons. - 0105-4538 .- 1398-9995. ; 76:1, s. 168-190
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Forskningsöversikt (refereegranskat)abstract
- Digital anamorphosis is used to define a distorted image of health and care that may be viewed correctly using digital tools and strategies. MASK digital anamorphosis represents the process used by MASK to develop the digital transformation of health and care in rhinitis. It strengthens the ARIA change management strategy in the prevention and management of airway disease. The MASK strategy is based on validated digital tools. Using the MASK digital tool and the CARAT online enhanced clinical framework, solutions for practical steps of digital enhancement of care are proposed.
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| 16. |
- Bousquet, J. Jean, et al.
(författare)
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Next-generation ARIA care pathways for rhinitis and asthma : a model for multimorbid chronic diseases
- 2019
-
Ingår i: Clinical and Translational Allergy. - : BMC. - 2045-7022. ; 9
-
Forskningsöversikt (refereegranskat)abstract
- Background: In all societies, the burden and cost of allergic and chronic respiratory diseases are increasing rapidly. Most economies are struggling to deliver modern health care effectively. There is a need to support the transformation of the health care system into integrated care with organizational health literacy.Main body: As an example for chronic disease care, MASK (Mobile Airways Sentinel NetworK), a new project of the ARIA (Allergic Rhinitis and its Impact on Asthma) initiative, and POLLAR (Impact of Air POLLution on Asthma and Rhinitis, EIT Health), in collaboration with professional and patient organizations in the field of allergy and airway diseases, are proposing real-life ICPs centred around the patient with rhinitis, and using mHealth to monitor environmental exposure. Three aspects of care pathways are being developed: (i) Patient participation, health literacy and self-care through technology-assisted "patient activation", (ii) Implementation of care pathways by pharmacists and (iii) Next-generation guidelines assessing the recommendations of GRADE guidelines in rhinitis and asthma using real-world evidence (RWE) obtained through mobile technology. The EU and global political agendas are of great importance in supporting the digital transformation of health and care, and MASK has been recognized by DG Sante as a Good Practice in the field of digitally-enabled, integrated, person-centred care.Conclusion: In 20 years, ARIA has considerably evolved from the first multimorbidity guideline in respiratory diseases to the digital transformation of health and care with a strong political involvement.
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| 17. |
- Bruno, Barbara, et al.
(författare)
-
Knowledge Representation for Culturally Competent Personal Robots : Requirements, Design Principles, Implementation, and Assessment
- 2019
-
Ingår i: International Journal of Social Robotics. - : Springer. - 1875-4791 .- 1875-4805. ; 11:3, s. 515-538
-
Tidskriftsartikel (refereegranskat)abstract
- Culture, intended as the set of beliefs, values, ideas, language, norms and customs which compose a person's life, is an essential element to know by any robot for personal assistance. Culture, intended as that person's background, can be an invaluable source of information to drive and speed up the process of discovering and adapting to the person's habits, preferences and needs. This article discusses the requirements posed by cultural competence on the knowledge management system of a robot. We propose a framework for cultural knowledge representation that relies on (i) a three-layer ontology for storing concepts of relevance, culture-specific information and statistics, person-specific information and preferences; (ii) an algorithm for the acquisition of person-specific knowledge, which uses culture-specific knowledge to drive the search; (iii) a Bayesian Network for speeding up the adaptation to the person by propagating the effects of acquiring one specific information onto interconnected concepts. We have conducted a preliminary evaluation of the framework involving 159 Italian and German volunteers and considering 122 among habits, attitudes and social norms.
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| 18. |
- Bujosa Mateu, Daniel, et al.
(författare)
-
Clock Synchronization in Integrated TSN-EtherCAT Networks
- 2020
-
Ingår i: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728189567 ; , s. 214-221
-
Konferensbidrag (refereegranskat)abstract
- Moving towards new technologies, such as Time Sensitive Networking (TSN), in industries should be gradual with a proper integration process instead of replacing the existing ones to make it beneficial in terms of cost and performance. Within this context, this paper identifies the challenges of integrating a legacy EtherCAT network, as a commonly used technology in the automation domain, into a TSN network. We show that clock synchronization plays an essential role when it comes to EtherCAT-TSN network integration with important requirements. We propose a clock synchronization mechanism based on the TSN standards to obtain a precise synchronization among EtherCAT nodes, resulting to an efficient data transmission. Based on a formal verification framework using UPPAAL tool we show that the integrated EtherCAT-TSN network with the proposed clock synchronization mechanism achieves at least 3 times higher synchronization precision compared to not using any synchronization.
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| 19. |
- Bujosa Mateu, Daniel
(författare)
-
Enhancing TSN Adoption by Industry : Tools to Support Migrating Ethernet-based Legacy Networks into TSN
- 2023
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- New technologies present opportunities and challenges for industries. One major challenge is the ease, or even feasibility, of its adoption. The Time-Sensitive Networking (TSN) standards offer a range of features relevant to various applications and are key for the transition to Industry 4.0. These features include deterministic zero-jitter, low-latency data transmission, transmission of traffic with various levels of time-criticality on the same network, fault tolerance mechanisms, and advanced network management allowing dynamic reconfiguration.This thesis aims to develop tools that enable the industry to adopt TSN easily and efficiently. Specifically, we create tools that facilitate the migration of legacy networks to TSN, enabling the preservation of most of the legacy systems and solutions while reducing costs and adoption time. Firstly, we introduce LETRA (Legacy Ethernet-based Traffic Mapping Tool), a tool for mapping Ethernet-based legacy traffic to the new TSN traffic classes. Secondly, we develop HERMES (Heuristic Multi-queue Scheduler), a heuristic Time-Triggered (TT) traffic scheduler that can meet the characteristics of legacy systems and provide quick results suitable for reconfiguration. Thirdly, we develop TALESS (TSN with Legacy End-Stations Synchronization), a mechanism to avoid adverse consequences caused by the lack of synchronization between legacy systems and TSN-based ones, as not all legacy systems need to support the TSN synchronization mechanisms. Finally, we improve Stream Reservation Protocol (SRP) to enhance Audio-Video Bridging (AVB) traffic configuration in terms of termination and consistency.
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| 20. |
- Bujosa Mateu, Daniel, et al.
(författare)
-
HERMES : Heuristic Multi-queue Scheduler for TSN Time-Triggered Traffic with Zero Reception Jitter Capabilities
- 2022
-
Ingår i: ACM International Conference Proceeding Series. - New York, NY, USA : Association for Computing Machinery. - 9781450396509 ; , s. 70-80
-
Konferensbidrag (refereegranskat)abstract
- The Time-Sensitive Networking (TSN) standards provide a toolbox of features to be utilized in various application domains.The core TSN features include deterministic zero-jitter and low-latency data transmission and transmitting traffic with various levels of time-criticality on the same network. To achieve a deterministic transmission, the TSN standards define a time-aware shaper that coordinates transmission of Time-Triggered (TT) traffic. In this paper, we tackle the challenge of scheduling the TT traffic and we propose a heuristic algorithm, called HERMES. Unlike the existing scheduling solutions, HERMES results in a significantly faster algorithm run-time and a high number of schedulable networks. HERMES can be configured in two modes of zero or relaxed reception jitter while using multiple TT queues to improve the schedulability. We compare HERMES with a constraint programming (CP)-based solution and we show that HERMES performs better than the CP-based solution if multiple TT queues are used, both with respect to algorithm run-time and schedulability of the networks.
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| 21. |
- Bujosa Mateu, Daniel, et al.
(författare)
-
Improved Clock Synchronization in TSN Networks with Legacy End-Stations
- 2023
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In order to enable the adoption of Time Sensitive Networking (TSN) by the industry and be more environmentally sustainable, it is necessary to develop tools to integrate legacy systems with TSN. In this paper, we propose a solution for the coexistence of different time domains from different legacy systems with their corresponding synchronization protocols in a single TSN network. To this end, we experimentally identified the effects of replacing the communications subsystem of a legacy Ethernet-based network with TSN in terms of synchronization. Based on the results, we propose a solution called TALESS (TSN with Legacy End-Stations Synchronization). TALESS is able to identify the drift between the TSN communications subsystem and the integrated legacy devices (end-stations) and modify the TSN schedule to adapt to the different time domains to avoid the effects of the lack of synchronization between them. We validate TALESS through both simulations and experiments on a prototype. Thereby we demonstrate that thanks to TALESS, legacy systems are able to synchronize through TSN and even improve features such as their reception jitter or their integrability with other legacy systems.
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| 22. |
- Bujosa Mateu, Daniel, et al.
(författare)
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Introducing Guard Frames to Ensure Schedulability of All TSN Traffic Classes
- 2023
-
Ingår i: IEEE Int. Conf. Emerging Technol. Factory Autom., ETFA. - : Institute of Electrical and Electronics Engineers Inc.. - 9798350339918
-
Konferensbidrag (refereegranskat)abstract
- Offline scheduling of Scheduled Traffic (ST) in Time-Sensitive Networks (TSN) without taking into account the quality of service of non-ST traffic, e.g., time-sensitive traffic such as Audio-Video Bridging (AVB) traffic, can potentially cause deadline misses for non-ST traffic. In this paper, we report our ongoing work to propose a solution that, regardless of the ST scheduling algorithm being used, can ensure meeting timing requirements for non-ST traffic. To do this, we define a frame called Guard Frame (GF) that will be scheduled together with all ST frames. We show that a proper design for the GFs will leave necessary porosity in the ST schedules to ensure that all non-ST traffic will meet their timing requirements.
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| 23. |
- Bujosa Mateu, Daniel, et al.
(författare)
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LETRA : Mapping Legacy Ethernet-Based Traffic into TSN Traffic Classes
- 2021
-
Ingår i: 26th IEEE International Conference on Emerging Technologies and Factory Automation ETFA 2021. - Västerås, Sweden : IEEE. - 9781728129891
-
Konferensbidrag (refereegranskat)abstract
- This paper proposes a method to efficiently map the legacy Ethernet-based traffic into Time Sensitive Networking (TSN) traffic classes considering different traffic characteristics. Traffic mapping is one of the essential steps for industries to gradually move towards TSN, which in turn significantly mitigates the management complexity of industrial communication systems. In this paper, we first identify the legacy Ethernet traffic characteristics and properties. Based on the legacy traffic characteristics we presented a mapping methodology to map them into different TSN traffic classes. We implemented the mapping method as a tool, named Legacy Ethernet-based Traffic Mapping Tool or LETRA, together with a TSN traffic scheduling and performed a set of evaluations on different synthetic networks. The results show that the proposed mapping method obtains up to 90% improvement in the schedulability ratio of the traffic compared to an intuitive mapping method on a multi-switch network architecture.
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| 24. |
- Bujosa Mateu, Daniel, et al.
(författare)
-
The Effects of Clock Synchronization in TSN Networks with Legacy End-Stations
- 2022
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we present our ongoing work on proposing solutions to integrate legacy end-stations into Time-Sensitive Network (TSN) communication systems where the legacy end-stations are synchronized via their legacy clock synchronization protocol. To this end, we experimentally identify the effects of lacking synchronization or partial synchronization in TSN networks. In the experiments we show the effects of clock synchronization in different scenarios on jitter and clock drifts. Based on the experiments, we propose preliminary solutions to overcome the identified effects.
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| 25. |
- Camara Moreno, Javier, et al.
(författare)
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Towards Bridging the Gap between Control and Self-Adaptive System Properties
- 2020
-
Ingår i: SEAMS '20. - New York, NY, USA : ACM. - 9781450379625 ; , s. 78-84
-
Konferensbidrag (refereegranskat)abstract
- Two of the main paradigms used to build adaptive software employ different types of properties to capture relevant aspects of the system’s run-time behavior. On the one hand, control systems consider properties that concern static aspects like stability, as well as dynamic properties that capture the transient evolution of variables such as settling time. On the other hand, self-adaptive systems consider mostly non-functional properties that capture concerns such as performance, reliability, and cost. In general, it is not easy to reconcile these two types of properties or identify under which conditions they constitute a good fit to provide run-time guarantees. There is a need of identifying the key properties in the areas of control and self-adaptation, as well as of characterizing and mapping them to better understand how they relate and possibly complement each other. In this paper, we take a first step to tackle this problem by: (1) identifying a set of key properties in control theory, (2) illustrating the formalization of some of these properties employing temporal logic languages commonly used to engineer self-adaptive software systems, and (3) illustrating how to map key properties that characterize self-adaptive software systems into control properties, leveraging their formalization in temporal logics. We illustrate the different steps of the mapping on an exemplar case in the cloud computing domain and conclude with identifying open challenges in the area.
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| 26. |
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| 27. |
- Desmeurs, David, et al.
(författare)
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Event-Driven Application Brownout : Reconciling High Utilization and Low Tail Response Times
- 2015
-
Ingår i: 2015 International Conference on Cloud and Autonomic Computing (ICCAC). - New York : IEEE Computer Society. - 9781467395663 ; , s. 1-12
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Konferensbidrag (refereegranskat)abstract
- Data centers currently waste a lot of energy, due to lack of energy proportionality and low resource utilization, the latter currently being necessary to ensure application responsiveness. To address the second concern we propose a novel application-level technique that we call event-driven Brownout. For each request, i.e., in an event-driven manner, the application can execute some optional code that is not required for correct operation but desirable for user experience, and does so only if the number of pending client requests is below a given threshold. We propose several autonomic algorithms, based on control theory and machine learning, to automatically tune this threshold based on measured application 95th percentile response times. We evaluate our approach using the RUBiS benchmark which shows a 11-fold improvement in maintaining response-time close to a set-point at high utilization compared to competing approaches. Our contribution is opening the path to more energy efficient data-centers, by allowing applications to keep response times close to a set-point even at high resource utilization.
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| 28. |
- Diniz Caldas, Ricardo, 1994, et al.
(författare)
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Towards Mapping Control Theory and Software Engineering Properties using Specification Patterns
- 2021
-
Ingår i: 2021 IEEE International Conference on Autonomic Computing and Self-Organizing Systems Companion (ACSOS-C). - Washington DC, United States : IEEE. - 9781665443937
-
Konferensbidrag (refereegranskat)abstract
- A traditional approach to realize self-adaptation in software engineering (SE) is by means of feedback loops. The goals of the system can be specified as formal properties that are verified against models of the system. On the other hand, control theory (CT) provides a well-established foundation for designing feedback loop systems and providing guarantees for essential properties, such as stability, settling time, and steady state error. Currently, it is an open question whether and how traditional SE approaches to self-adaptation consider properties from CT. Answering this question is challenging given the principle differences in representing properties in both fields. In this paper, we take a first step to answer this question. We follow a bottom up approach where we specify a control design (in Simulink) for a case inspired by Scuderia Ferrari (F1) and provide evidence for stability and safety. The design is then transferred into code (in C) that is further optimized. Next, we define properties that enable verifying whether the control properties still hold at code level. Then, we consolidate the solution by mapping the properties in both worlds using specification patterns as common language and we verify the correctness of this mapping. The mapping offers a reusable artifact to solve similar problems. Finally, we outline opportunities for future work, particularly to refine and extend the mapping and investigate how it can improve the engineering of self-adaptive systems for both SE and CT engineers.
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| 29. |
- Dürango, Jonas, et al.
(författare)
-
Control-theoretical load-balancing for cloud applications with brownout
- 2014
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Ingår i: 2014 IEEE 53RD ANNUAL CONFERENCE ON DECISION AND CONTROL (CDC). - 9781467360906 - 9781479977468 ; , s. 5320-5327
-
Konferensbidrag (refereegranskat)abstract
- Cloud applications are often subject to unexpected events like flash crowds and hardware failures. Without a predictable behaviour, users may abandon an unresponsive application. This problem has been partially solved on two separate fronts: first, by adding a self-adaptive feature called brownout inside cloud applications to bound response times by modulating user experience, and, second, by introducing replicas - copies of the applications having the same functionalities - for redundancy and adding a load-balancer to direct incoming traffic. However, existing load-balancing strategies interfere with brownout self-adaptivity. Load-balancers are often based on response times, that are already controlled by the self-adaptive features of the application, hence they are not a good indicator of how well a replica is performing. In this paper, we present novel load-balancing strategies, specifically designed to support brownout applications. They base their decision not on response time, but on user experience degradation. We implemented our strategies in a self-adaptive application simulator, together with some state-of-the-art solutions. Results obtained in multiple scenarios show that the proposed strategies bring significant improvements when compared to the state-of-the-art ones.
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| 30. |
- Faragardi, Hamid Reza, et al.
(författare)
-
A Time-Predictable Fog-Integrated Cloud Framework : One Step Forward in the Deployment of a Smart Factory
- 2018
-
Ingår i: CSI International Symposium on Real-Time and Embedded Systems and Technologies REST'18. - 9781538614754 ; , s. 54-62
-
Konferensbidrag (refereegranskat)abstract
- This paper highlights cloud computing as one of the principal building blocks of a smart factory, providing a huge data storage space and a highly scalable computational capacity. The cloud computing system used in a smart factory should be time-predictable to be able to satisfy hard real-time requirements of various applications existing in manufacturing systems. Interleaving an intermediate computing layer-called fog-between the factory and the cloud data center is a promising solution to deal with latency requirements of hard real-time applications. In this paper, a time-predictable cloud framework is proposed which is able to satisfy end-to-end latency requirements in a smart factory. To propose such an industrial cloud framework, we not only use existing real-time technologies such as Industrial Ethernet and the Real-time XEN hypervisor, but we also discuss unaddressed challenges. Among the unaddressed challenges, the partitioning of a given workload between the fog and the cloud is targeted. Addressing the partitioning problem not only provides a resource provisioning mechanism, but it also gives us a prominent design decision specifying how much computing resource is required to develop the fog platform, and how large should the minimum communication bandwidth be between the fog and the cloud data center.
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| 31. |
- Faragardi, Hamid Reza, 1987-
(författare)
-
Optimizing Timing-Critical Cloud Resources in a Smart Factory
- 2018
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis addresses the topic of resource efficiency in the context of timing critical components that are used in the realization of a Smart Factory.The concept of the smart factory is a recent paradigm to build future production systems in a way that is both smarter and more flexible. When it comes to realization of a smart factory, three principal elements play a significant role, namely Embedded Systems, Internet of Things (IoT) and Cloud Computing. In a smart factory, efficient use of computing and communication resources is a prerequisite not only to obtain a desirable performance for running industrial applications, but also to minimize the deployment cost of the system in terms of the size and number of resources that are required to run industrial applications with an acceptable level of performance. Most industrial applications that are involved in smart factories, e.g., automation and manufacturing applications, are subject to a set of strict timing constraints that must be met for the applications to operate properly. Such applications, including underlying hardware and software components that are used to run the application, constitute a real-time system. In real-time systems, the first and major concern of the system designer is to provide a solution where all timing constraints are met. To do so we need a time-predictable IoT/Cloud Computing framework to deal with the real-time constraints that are inherent in industrial applications running in a smart factory. Afterwards, with respect to the time predictable framework, the number of required computing and communication resources can and should be optimized such that the deployed system is cost efficient. In this thesis, to investigate and present solutions that provide and improve the resource efficiency of computing and communication resources in a smart factory, we conduct research following three themes: (i) multi-core embedded processors, which are the key element in terms of computing components embedded in the machinery of a smart factory, (ii) cloud computing data centers, as the supplier of a massive data storage and a large computational power, and(iii) IoT, for providing the interconnection of computing components embedded in the objects of a smart factory. Each of these themes are targeted separately to optimize resource efficiency. For each theme, we identify key challenges when it comes to achieving a resource-efficient design of the system. We then formulate the problem and propose solutions to optimize the resource efficiency of the system, while satisfying all timing constraints reflected in the model. We then propose a comprehensive resource allocation mechanism to optimize the resource efficiency in the whole system while considering the characteristics of each of these research themes. The experimental results indicate a clear improvement when it comes to timing-critical IoT / Cloud Computing resources in a smart factory. At the level of multi-core embedded devices, the total CPU usage of a quad-core processor is shown to be improved by 11.2%. At the level of Cloud Computing, the number of cloud servers that are required to execute a given set of real-time applications is shown to be reduced by 25.5%. In terms of network components that are used to collect sensor data, our proposed approach reduces the total deployment cost of thesystem by 24%. In summary these results all contribute towards the realization of a future smart factory.
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| 32. |
- Filieri, Antonio, et al.
(författare)
-
Control Strategies for Self-Adaptive Software Systems
- 2017
-
Ingår i: ACM Transactions on Autonomous and Adaptive Systems. - : Association for Computing Machinery (ACM). - 1556-4665 .- 1556-4703. ; 11:4
-
Tidskriftsartikel (refereegranskat)abstract
- The pervasiveness and growing complexity of software systems are challenging software engineering to design systems that can adapt their behavior to withstand unpredictable, uncertain, and continuously changing execution environments. Control theoretical adaptation mechanisms have received growing interest from the software engineering community in the last few years for their mathematical grounding, allowing formal guarantees on the behavior of the controlled systems. However, most of these mechanisms are tailored to specific applications and can hardly be generalized into broadly applicable software design and development processes.This article discusses a reference control design process, from goal identification to the verification and validation of the controlled system. A taxonomy of the main control strategies is introduced, analyzing their applicability to software adaptation for both functional and nonfunctional goals. A brief extract on how to deal with uncertainty complements the discussion. Finally, the article highlights a set of open challenges, both for the software engineering and the control theory research communities.
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| 33. |
- Filieri, Antonio, et al.
(författare)
-
Software Engineering Meets Control Theory
- 2015
-
Ingår i: 2015 10th International Symposium on Software Engineering for Adaptive and Self-Managing Systems. - Piscataway, NJ, USA : IEEE Press. - 9780769555676 ; , s. 71-82
-
Konferensbidrag (refereegranskat)abstract
- The software engineering community has proposed numerous approaches for making software self-adaptive. These approaches take inspiration from machine learning and control theory, constructing software that monitors and modifies its own behavior to meet goals. Control theory, in particular, has received considerable attention as it represents a general methodology for creating adaptive systems. Control-theoretical software implementations, however, tend to be ad hoc. While such solutions often work in practice, it is difficult to understand and reason about the desired properties and behavior of the resulting adaptive software and its controller. This paper discusses a control design process for software systems which enables automatic analysis and synthesis of a controller that is guaranteed to have the desired properties and behavior. The paper documents the process and illustrates its use in an example that walks through all necessary steps for self-adaptive controller synthesis.
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| 34. |
- Frasheri, Mirgita, et al.
(författare)
-
Adaptive Autonomy in a Search and Rescue Scenario
- 2018
-
Ingår i: International Conference on Self-Adaptive and Self-Organizing Systems, SASO, Volume 2018-September, 15 January 2019. - 9781538651728 ; , s. 150-155
-
Konferensbidrag (refereegranskat)abstract
- Adaptive autonomy plays a major role in the design of multi-robots and multi-agent systems, where the need of collaboration for achieving a common goal is of primary importance. In particular, adaptation becomes necessary to deal with dynamic environments, and scarce available resources. In this paper, a mathematical framework for modelling the agents' willingness to interact and collaborate, and a dynamic adaptation strategy for controlling the agents' behavior, which accounts for factors such as progress toward a goal and available resources for completing a task among others, are proposed. The performance of the proposed strategy is evaluated through a fire rescue scenario, where a team of simulated mobile robots need to extinguish all the detected fires and save the individuals at risk, while having limited resources. The simulations are implemented as a ROS-based multi agent system, and results show that the proposed adaptation strategy provides a more stable performance than a static collaboration policy.
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| 35. |
- Frasheri, Mirgita, et al.
(författare)
-
Adaptive Autonomy in Wireless Sensor Networks
- 2020
-
Ingår i: Proceedings of the International Joint Conference on Autonomous Agents and Multiagent Systems, AAMAS. - 9781450375184 ; , s. 375-383
-
Konferensbidrag (refereegranskat)abstract
- Moving nodes in a Mobile Wireless Sensor Network (MWSN) typically have two maintenance objectives: (i) extend the coverage of the network as long as possible to a target area, and (ii) extend the longevity of the network as much as possible. As nodes move and also route traffic in the network, their battery levels deplete differently for each node. Dead nodes lead to loss of connectivity and even to disengaging full parts of the network. Several reactive and rule-based approaches have been proposed to solve this issue by adapting redeployment to depleted nodes. However, in large networks a cooperative approach may increase performance by taking the evolution of node battery and traffic into account. In this paper, we present a hybrid agent-based architecture that addresses the problem of depleting nodes during the maintenance phase of a MWSN. Agents, each assigned to a node, collaborate and adapt their behaviour to their battery levels. The collaborative behavior is modeled through the willingness to interact abstraction, which defines when agents ask and give help to one another. Thus, depleting nodes may ask to be replaced by healthier counterparts and move to areas with less traffic or to a collection point. At the lower level, negotiations trigger a reactive navigation behaviour based on Social Potential Fields (SPF). It is shown that the proposed method improves coverage and extends network longevity in an environment without obstacles as compared to SPF alone.
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| 36. |
- Frasheri, Mirgita, et al.
(författare)
-
Cooperative Multi-agent Systems for the Multi-target κ -Coverage Problem
- 2021
-
Ingår i: Lect. Notes Comput. Sci.. - Cham : Springer Science and Business Media Deutschland GmbH. - 9783030711573 ; , s. 106-131
-
Konferensbidrag (refereegranskat)abstract
- When multiple robots are required to collaborate in order to accomplish a specific task, they need to be coordinated in order to operate efficiently. To allow for scalability and robustness, we propose a novel distributed approach performed by autonomous robots based on their willingness to interact with each other. This willingness, based on their individual state, is used to inform a decision process of whether or not to interact with other robots within the environment. We study this new mechanism to form coalitions in the on-line multi-object κ -coverage problem, and evaluate its performance through two sets of experiments, in which we also compare to other methods from the state-of-art. In the first set we focus on scenarios with static and mobile targets, as well as with a different number of targets. Whereas in the second, we carry out an extensive analysis of the best performing methods focusing only on mobile targets, while also considering targets that appear and disappear during the course of the experiments. Results show that the proposed method is able to provide comparable performance to the best methods under study.
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| 37. |
- Frasheri, Mirgita, et al.
(författare)
-
Ethics of autonomous collective decision-making : The caesar framework
- 2022
-
Ingår i: Science and Engineering Ethics. - : Springer Nature. - 1353-3452 .- 1471-5546. ; 28:6
-
Tidskriftsartikel (refereegranskat)abstract
- In recent years, autonomous systems have become an important research area and application domain, with a significant impact on modern society. Such systems are characterized by different levels of autonomy and complex communication infrastructures that allow for collective decision-making strategies. There exist several publications that tackle ethical aspects in such systems, but mostly from the perspective of a single agent. In this paper we go one step further and discuss these ethical challenges from the perspective of an aggregate of autonomous systems capable of collective decision-making. In particular, in this paper, we propose the Caesar approach through which we model the collective ethical decision-making process of a group of actors—agents and humans, as well as define the building blocks for the agents participating in such a process, namely Caesar agents. Factors such as trust, security, safety, and privacy, which affect the degree to which a collective decision is ethical, are explicitly captured in Caesar. Finally, we argue that modeling the collective decision-making in Caesar provides support for accountability.
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| 38. |
- Frasheri, Mirgita, et al.
(författare)
-
GLocal : A Hybrid Approach to the Multi-Agent Mission Re-Planning Problem
- 2020
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Multi-robot systems can be prone to failures during plan execution, depending on the harshness of the environment they are deployed in. As a consequence, initially devised plans may no longer be feasible, and a re-planning process needs to take place to re-allocate any pending tasks. Two main approaches emerge as possible solutions, a global re-planning technique using a centralized planner that will redo the task allocation with the updated world state information, or a decentralized approach that will focus on the local plan reparation, i.e., the re-allocation of those tasks initially assigned to the failed robots.The former approach produces an overall better solution, while the latter is less computationally expensive.The goal of this paper is to exploit the benefits of both approaches, while minimizing their drawbacks. To this end, we propose a hybrid approach {that combines a centralized planner with decentralized multi-agent planning}. In case of an agent failure, the local plan reparation algorithm tries to repair the plan through agent negotiation. If it fails to re-allocate all of the pending tasks, the global re-planning algorithm is invoked, which re-allocates all unfinished tasks from all agents.The hybrid approach was compared to planner approach, and it was shown that it improves on the makespan of a mission in presence of different numbers of failures,as a consequence of the local plan reparation algorithm.
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| 39. |
- Frasheri, M., et al.
(författare)
-
GLocal : A Hybrid Approach to the Multi-Agent Mission Re-Planning Problem
- 2023
-
Ingår i: IEEE Symposium Series on Computational Intelligence, SSCI. - : IEEE. - 9781665430654 ; , s. 1696-1703
-
Konferensbidrag (refereegranskat)abstract
- Multi-agent systems can be prone to failures during the execution of a mission, depending on different circumstances, such as the harshness of the environment they are deployed in. As a result, initially devised plans for completing a mission may no longer be feasible, and a re-planning process needs to take place to re-allocate any pending tasks. There are two main approaches to solve the re-planning problem (i) global re-planning techniques using a centralized planner that will redo the task allocation with the updated world state and (ii) decentralized approaches that will focus on the local plan reparation, i.e., the re-allocation of those tasks initially assigned to the failed robots, better suited to a dynamic environment and less computationally expensive. In this paper, we propose a hybrid approach, named GLocal, that combines both strategies to exploit the benefits of both, while limiting their respective drawbacks. GLocal was compared to a planner-only, and an agent-only approach, under different conditions. We show that GLocal produces shorter mission make-spans as the number of tasks and failed agents increases, while also balancing the tradeoff between the number of messages exchanged and the number of requests to the planner.
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| 40. |
- Frasheri, Mirgita, et al.
(författare)
-
Modeling the willingness to interact in cooperative multi-robot systems
- 2020
-
Ingår i: ICAART 2020 - Proceedings of the 12th International Conference on Agents and Artificial Intelligence, VOL 1. - : SciTePress. - 9789897583957 ; , s. 62-72
-
Konferensbidrag (refereegranskat)abstract
- When multiple robots are required to collaborate in order to accomplish a specific task, they need to be coordinated in order to operate efficiently. To allow for scalability and robustness, we propose a novel distributed approach performed by autonomous robots based on their willingness to interact with each other. This willingness, based on their individual state, is used to inform a decision process of whether or not to interact with other robots within the environment. We study this new mechanism to form coalitions in the on-line multiobject κ-coverage problem, and compare it with six other methods from the literature. We investigate the trade-off between the number of robots available and the number of potential targets in the environment. We show that the proposed method is able to provide comparable performance to the best method in the case of static targets, and to achieve a higher level of coverage with respect to the other methods in the case of mobile targets.
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| 41. |
- Frasheri, Mirgita
(författare)
-
Modelling and Control of the Collaborative Behavior of Adaptive Autonomous Agents
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Research on autonomous agents and vehicles has gained momentum in the past years, which is reflected in the extensive body of literature and the investment of big players of the industry in the development of products such as self-driving cars. Additionally, these systems are envisioned to continuously communicate and cooperate with one another in order to adapt to dynamic circumstances and unforeseeable events, and as a result will they fulfil their goals even more efficiently.The facilitation of such dynamic collaboration and the modelling of interactions between different actors (software agents, humans) remains an open challenge.This thesis tackles the problem of enabling dynamic collaboration by investigating the automated adjustment of autonomy of different agents, called Adaptive Autonomy (AA). An agent, in this context, is a software able to process and react to sensory inputs in the environment in which it is situated in, and is additionally capable of autonomous actions. In this work, the collaborative adaptive autonomous behaviour of agents is shaped by their willingness to interact with other agents, that captures the disposition of an agent to give and ask for help, based on different factors that represent the agent's state and its interests.The AA approach to collaboration is used in two different domains: (i) the hunting mobile search problem, and (ii) the coverage problem of mobile wireless sensor networks. In both cases, the proposed approach is compared to state-of-art methods.Furthermore, the thesis contributes on a conceptual level by combining and integrating the AA approach -- which is purely distributed -- with a high-level mission planner, in order to exploit the ability of dealing with local and contingent problems through the AA approach, while minimising the requests for a re-plan to the mission planner.
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| 42. |
- Friebe, Anna, et al.
(författare)
-
Adaptive Runtime Estimate of Task Execution Times using Bayesian Modeling
- 2021
-
Ingår i: Proceedings - 2021 IEEE 27th International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2021. - : Institute of Electrical and Electronics Engineers Inc.. - 9781665441889 ; , s. 1-10
-
Konferensbidrag (refereegranskat)abstract
- In the recent works that analyzed execution-time variation of real-time tasks, it was shown that such variation may conform to regular behavior. This regularity may arise from multiple sources, e.g., due to periodic changes in hardware or program state, program structure, inter-task dependence or inter-task interference. Such complexity can be better captured by a Markov Model, compared to the common approach of assuming independent and identically distributed random variables. However, despite the regularity that may be described with a Markov model, over time, the execution times may change, due to irregular changes in input, hardware state, or program state. In this paper, we propose a Bayesian approach to adapt the emission distributions of the Markov Model at runtime, in order to account for such irregular variation. A preprocessing step determines the number of states and the transition matrix of the Markov Model from a portion of the execution time sequence. In the preprocessing step, segments of the execution time trace with similar properties are identified and combined into clusters. At runtime, the proposed method switches between these clusters based on a Generalized Likelihood Ratio (GLR). Using a Bayesian approach, clusters are updated and emission distributions estimated. New clusters can be identified and clusters can be merged at runtime. The time complexity of the online step is $O(N^{2}+ NC)$ where N is the number of states in the Hidden Markov Model (HMM) that is fixed after the preprocessing step, and C is the number of clusters.
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| 43. |
- Friebe, Anna, et al.
(författare)
-
Continuous-Emission Markov Models for Real-Time Applications : Bounding Deadline Miss Probabilities
- 2023
-
Ingår i: Proc. IEEE Real Time Embedded Technol. Appl. Symp. RTAS. - : Institute of Electrical and Electronics Engineers Inc.. - 9798350321760 ; , s. 14-26
-
Konferensbidrag (refereegranskat)abstract
- Probabilistic approaches have gained attention over the past decade, providing a modeling framework that enables less pessimistic analysis of real-time systems. Among the different proposed approaches, Markov chains have been shown effective for analyzing real-time systems, particularly in estimating the pending workload distribution and deadline miss probability. However, the state-of-the-art mainly considered discrete emission distributions without investigating the benefits of continuous ones. In this paper, we propose a method for analyzing the workload probability distribution and bounding the deadline miss probability for a task executing in a reservation-based server, where execution times are described by a Markov model with Gaussian emission distributions. The evaluation is performed for the timing behavior of a Kalman filter for Furuta pendulum control. Deadline miss probability bounds are derived with a workload accumulation scheme. The bounds are compared to 1) measured deadline miss ratios of tasks running under the Linux Constant Bandwidth Server with SCHED-DEADLINE, 2) estimates derived from a Markov Model with discrete-emission distributions (PROSIT), 3) simulation-based estimates, and 4) an estimate assuming independent execution times. The results suggest that the proposed method successfully upper bounds actual deadline miss probabilities. Compared to the discrete-emission counterpart, the computation time is independent of the range of the execution times under analysis, and resampling is not required.
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| 44. |
- Friebe, Anna, et al.
(författare)
-
Estimating Deadline Miss Probabilities of Continuous-Emission Markov Chain Tasks
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Estimating the response times of real-time tasks and applications is important for the analysis and implementation of real-time systems. Probabilistic approaches have gained attention over the past decade, as they provide a modeling framework that allows for less pessimism for the analysis of real-time systems.Among the different proposed approaches, Markov chains have been shown to be effective for the analysis of real-time systems, in particular, in the estimate of the pending workload probability distribution and of the deadline miss probability. However, this has been analyzed only for discrete emission distributions, but not for continuous ones.In this paper, we propose a method for analyzing the workload probability distribution and bounding the deadline miss probability for a task executing in a Constant Bandwidth Server, where execution times are described by a Markov model with Gaussian emission distributions.In the evaluation, deadline miss probability bounds and estimates are derived with a workload accumulation scheme. The results are compared to simulation and measured deadline miss ratios from tasks under the Linux Constant Bandwidth Server implementation SCHED_DEADLINE.
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| 45. |
- Friebe, Anna, et al.
(författare)
-
Identification and validation of markov models with continuous emission distributions for execution times
- 2020
-
Ingår i: 2020 IEEE 26th International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2020. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728144030
-
Konferensbidrag (refereegranskat)abstract
- It has been shown that in some robotic applications, where the execution times cannot be assumed to be independent and identically distributed, a Markov Chain with discrete emission distributions can be an appropriate model. In this paper we investigate whether execution times can be modeled as a Markov Chain with continuous Gaussian emission distributions. The main advantage of this approach is that the concept of distance is naturally incorporated. We propose a framework based on Hidden Markov Model (HMM) methods that 1) identifies the number of states in the Markov Model from observations and fits the Markov Model to observations, and 2) validates the proposed model with respect to observations. Specifically, we apply a tree-based cross-validation approach to automatically find a suitable number of states in the Markov model. The estimated models are validated against observations, using a data consistency approach based on log likelihood distributions under the proposed model. The framework is evaluated using two test cases executed on a Raspberry Pi Model 3B+ single-board computer running Arch Linux ARM patched with PREEMPT_RT. The first is a simple test program where execution times intentionally vary according to a Markov model, and the second is a video decompression using the ffmpeg program. The results show that in these cases the framework identifies Markov Chains with Gaussian emission distributions that are valid models with respect to the observations.
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| 46. |
- Friebe, Anna
(författare)
-
Timing and Schedulability Analysis of Real-Time Systems using Hidden Markov Models
- 2022
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In real-time systems functional requirements are coupled to timing requirements, a specified event needs to occur at the appropriate time. In order to ensure that timing requirements are fulfilled, there are two main approaches, static and measurement-based. The static approach relies on modeling the hardware and software and calculating upper bounds for the timing behavior. On the other hand, measurement-based approaches use timing data collected from the system to estimate the timing behavior.The usability of static and measurement-based approaches is limited in many modern systems due to the increased complexity of hardware and software architectures. Static approaches to timing and schedulability analysis are often infeasible due to their complexity. Measurement-based approaches require that design-time measurements are representative of the timing behavior at runtime, which is problematic to ensure in many cases. Designing systems that guarantee the timing requirements without excessive resource overprovisioning is a challenge.A Hidden Markov Model (HMM) describes a system where the behavior is state-dependent. In this thesis, we model the execution time distribution of a periodic task as an HMM where the states are associated with continuous emission distributions. By modeling the execution times in this manner with a limited number of parameters, a step is taken on the path toward tracking and controlling timing properties at runtime. We present a framework for parameter identification of an HMM with Gaussian emission distributions from timing traces, and validation of the identified models. In evaluated cases, the parameterized models are valid in relation to timing traces.For cases where design-time measurements are not representative of the system at runtime we present a method for the online adaptive update of the emission distributions of an HMM. Evaluation with synthetic data shows that the estimate tracks the ground truth distribution. A method for estimating the deadline miss probability for a task with execution times modeled by an HMM with Gaussian emission distributions, in a Constant Bandwidth Server (CBS) is proposed. The method is evaluated with simulation and for a synthetic task with a known Markov Chain structure running on real hardware.
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| 47. |
- Friebe, Anna, et al.
(författare)
-
Work-in-progress : Validation of probabilistic timing models of a periodic task with interference - A case study
- 2019
-
Ingår i: Proceedings - Real-Time Systems Symposium. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728144030 ; , s. 524-527
-
Konferensbidrag (refereegranskat)abstract
- Probabilistic timing analysis techniques have been proposed for real-time systems to remedy the problems that deterministic estimates of the task's Worst-Case Execution Time and Worst-Case Response-Time can be both intractable and overly pessimistic. Often, assumptions are made that a task's response time and execution time probability distributions are independent of the other tasks. This assumption may not hold in real systems. In this paper, we analyze the timing behavior of a simple periodic task on a Raspberry Pi model 3 running Arch Linux ARM. In particular, we observe and analyze the distributions of wake-up latencies and execution times for the sequential jobs released by a simple periodic task. We observe that the timing behavior of jobs is affected by release events during the job's execution time, and of other processes running in between subsequent jobs of the periodic task. Using a data consistency approach we investigate whether it is reasonable to model the timing distribution of jobs affected by release events and intermediate processes as translations of the empirical timing distribution of non-affected jobs. According to the analysis, this paper shows that a translated distribution model of non-affected jobs is invalid for the execution time distribution of jobs affected by intermediate processes. Regarding the wake-up latency distribution with intermediate processes, a translated distribution model is improbable, but cannot be completely ruled out.
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| 48. |
- Gualandi, Gabriele, et al.
(författare)
-
Optimization-based attack against control systems with CUSUM-based anomaly detection
- 2022
-
Ingår i: 2022 30th Mediterranean Conference on Control and Automation, MED 2022. - : Institute of Electrical and Electronics Engineers Inc.. - 9781665406734 ; , s. 896-901
-
Konferensbidrag (refereegranskat)abstract
- Security attacks on sensor data can deceive a control system and force the physical plant to reach an unwanted and potentially dangerous state. Therefore, attack detection mechanisms are employed in cyber-physical control systems to detect ongoing attacks, the most prominent one being a threshold-based anomaly detection method called CUSUM. Literature defines the maximum impact of stealth attacks as the maximum deviation in the plant's state that an undetectable attack can introduce, and formulates it as an optimization problem. This paper proposes an optimization-based attack with different saturation models, and it investigates how the attack duration significantly affects the impact of the attack on the state of the plant. We show that more dangerous attacks can be discovered when allowing saturation of the control system actuators. The proposed approach is compared with the geometric attack, showing how longer attack durations can lead to a greater impact of the attack while keeping the attack stealthy. © 2022 IEEE.
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| 49. |
- Gualandi, Gabriele, et al.
(författare)
-
Worst-Case Impact Assessment of Multi-Alarm Stealth Attacks Against Control Systems with CUSUM-Based Anomaly Detection
- 2023
-
Ingår i: 2023 IEEE INTERNATIONAL CONFERENCE ON AUTONOMIC COMPUTING AND SELF-ORGANIZING SYSTEMS, ACSOS. - 9798350337440 ; , s. 117-126
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Manipulating sensor data can deceive cyber-physical systems (CPSs), leading to hazardous conditions in physical plants. An Anomaly Detection System (ADS) like CUSUM detects ongoing attacks by comparing sensor signals with those generated by a model. However, physics-based methods are threshold-based, which can result in both false positives and undetectable attacks. This can lead to undetected attacks impacting the system state and potentially causing large deviations from the desired behavior. In this paper, we introduce a metric called transparency that uniquely quantifies the effectiveness of an ADS in terms of its ability to prevent state deviation. While existing research focuses on designing optimal zero-alarm stealth attacks, we address the challenge of detecting more sophisticated multi-alarm attacks that generate alarms at a rate comparable to the system noise. Through our analysis, we identify the conditions that require the inclusion of multi-alarm scenarios in worst-case impact assessments. We also propose an optimization problem designed to identify multi-alarm attacks by relaxing the constraints of a zero-alarm attack problem. Our findings reveal that multi-alarm attacks can cause a more significant state deviation than zero-alarm attacks, emphasizing their critical importance in the security analysis of control systems.
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- Gulisano, Vincenzo, et al.
(författare)
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Elasticity
- 2019
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Ingår i: Encyclopedia of Big Data Technologies. - Sweden : Cham: Springer International Publishing. - 9783319775265
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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