| 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
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Ingår i: HRI '19. - : IEEE. - 9781538685556 ; , s. 371-371
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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. |
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| 4. |
- 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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| 5. |
- Bousquet, J. Jean, et al.
(författare)
-
Next-generation ARIA care pathways for rhinitis and asthma : a model for multimorbid chronic diseases
- 2019
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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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| 6. |
- Bruno, Barbara, et al.
(författare)
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Knowledge Representation for Culturally Competent Personal Robots : Requirements, Design Principles, Implementation, and Assessment
- 2019
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Ingår i: International Journal of Social Robotics. - : Springer. - 1875-4791 .- 1875-4805. ; 11:3, s. 515-538
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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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| 7. |
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| 8. |
- 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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| 9. |
- Faragardi, Hamid Reza, et al.
(författare)
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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
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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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| 10. |
- Faragardi, Hamid Reza, 1987-
(författare)
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Optimizing Timing-Critical Cloud Resources in a Smart Factory
- 2018
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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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| 11. |
- 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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| 12. |
- Filieri, Antonio, et al.
(författare)
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Software Engineering Meets Control Theory
- 2015
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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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| 13. |
- Frasheri, Mirgita, et al.
(författare)
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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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| 14. |
- Friebe, Anna, et al.
(författare)
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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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| 15. |
- Gulisano, Vincenzo, et al.
(författare)
-
Elasticity
- 2019
-
Ingår i: Encyclopedia of Big Data Technologies. - Sweden : Cham: Springer International Publishing. - 9783319775265
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 16. |
- Gulisano, Vincenzo Massimiliano, 1984, et al.
(författare)
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Performance modeling of stream joins
- 2017
-
Ingår i: DEBS 2017 - Proceedings of the 11th ACM International Conference on Distributed Event-Based Systems. - New York, NY, USA : ACM. - 9781450350655 ; , s. 191-202
-
Konferensbidrag (refereegranskat)abstract
- Streaming analysis is widely used in a variety of environments, from cloud computing infrastructures up to the network's edge. In these contexts, accurate modeling of streaming operators' performance enables fine-grained prediction of applications' behavior without the need of costly monitoring. This is of utmost importance for computationally-expensive operators like stream joins, that observe throughput and latency very sensitive to rate-varying data streams, especially when deterministic processing is required. In this paper, we present a modeling framework for estimating the throughput and the latency of stream join processing. The model is presented in an incremental step-wise manner, starting from a centralized non-deterministic stream join and expanding up to a deterministic parallel stream join. The model describes how the dynamics of throughput and latency are influenced by the number of physical input streams, as well as by the amount of parallelism in the actual processing and the requirement for determinism. We present an experimental validation of the model with respect to the actual implementation. The proposed model can provide insights that are catalytic for understanding the behavior of stream joins against different system deployments, with special emphasis on the influences of determinism and parallelization.
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| 17. |
- Ilyushkin, Alexey, et al.
(författare)
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An Experimental Performance Evaluation of Autoscalers for Complex Workflows
- 2018
-
Ingår i: ACM Transactions on Modeling and Performance Evaluation of Computing Systems. - : Association for Computing Machinery (ACM). - 2376-3639 .- 2376-3647. ; 3:2
-
Tidskriftsartikel (refereegranskat)abstract
- Elasticity is one of the main features of cloud computing allowing customers to scale their resources based on the workload. Many autoscalers have been proposed in the past decade to decide on behalf of cloud customers when and how to provision resources to a cloud application based on the workload utilizing cloud elasticity features. However, in prior work, when a new policy is proposed, it is seldom compared to the state-of-the-art, and is often compared only to static provisioning using a predefined quality of service target. This reduces the ability of cloud customers and of cloud operators to choose and deploy an autoscaling policy, as there is seldom enough analysis on the performance of the autoscalers in different operating conditions and with different applications. In our work, we conduct an experimental performance evaluation of autoscaling policies, using as application model workflows, a popular formalism for automating resource management for applications with well-defined yet complex structures. We present a detailed comparative study of general state-of-the-art autoscaling policies, along with two new workflow-specific policies. To understand the performance differences between the seven policies, we conduct various experiments and compare their performance in both pairwise and group comparisons. We report both individual and aggregated metrics. As many workflows have deadline requirements on the tasks, we study the effect of autoscaling on workflow deadlines. Additionally, we look into the effect of autoscaling on the accounted and hourly based charged costs, and we evaluate performance variability caused by the autoscaler selection for each group of workflow sizes. Our results highlight the trade-offs between the suggested policies, how they can impact meeting the deadlines, and how they perform in different operating conditions, thus enabling a better understanding of the current state-of-the-art.
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| 18. |
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| 19. |
- Ilyushkin, Alexey, et al.
(författare)
-
An Experimental Performance Evaluation of Autoscaling Algorithms for Complex Workflows
- 2017
-
Ingår i: ICPE '17 Proceedings of the 8th ACM/SPEC on International Conference on Performance Engineering. - New York, NY, USA : ACM. - 9781450344043 ; , s. 75-86
-
Konferensbidrag (refereegranskat)abstract
- Simplifying the task of resource management and scheduling for customers, while still delivering complex Quality-of-Service (QoS), is key to cloud computing. Many autoscaling policies have been proposed in the past decade to decide on behalf of cloud customers when and how to provision resources to a cloud application utilizing cloud elasticity features. However, in prior work, when a new policy is proposed, it is seldom compared to the state-of-the-art, and is often compared only to static provisioning using a predefined QoS target. This reduces the ability of cloud customers and of cloud operators to choose and deploy an autoscaling policy. In our work, we conduct an experimentalperformance evaluation of autoscaling policies, using as application model workflows, a commonly used formalism for automating resource management for applications with well-defined yet complex structure. We present a detailed comparative study of general state-of-the-art autoscaling policies, along with two new workflow-specific policies. To understand the performance differences between the 7 policies, we conduct various forms of pairwise and group comparisons. We report both individual and aggregated metrics. Our results highlight the trade-offs between the suggested policies, and thus enable a better understanding of the current state-of-the-art.
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| 20. |
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| 21. |
- Ioli, D., et al.
(författare)
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A compositional modeling framework for the optimal energy management of a district network
- 2019
-
Ingår i: Journal of Process Control. - : Elsevier Ltd. - 0959-1524 .- 1873-2771. ; 74, s. 160-176
-
Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a compositional modeling framework for the optimal energy management of a district network. The focus is on cooling of buildings, which can possibly share resources to the purpose of reducing maintenance costs and using devices at their maximal efficiency. Components of the network are described in terms of energy fluxes and combined via energy balance equations. Disturbances are accounted for as well, through their contribution in terms of energy. Different district configurations can be built, and the dimension and complexity of the resulting model will depend both on the number and type of components and on the adopted disturbance description. Control inputs are available to efficiently operate and coordinate the district components, thus enabling energy management strategies to minimize the electrical energy costs or track some consumption profile agreed with the main grid operator.
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| 22. |
- Johansson, Bjarne, et al.
(författare)
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Classification of PROFINET I/O Configurations utilizing Neural Networks
- 2019
-
Ingår i: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728103037 ; , s. 1321-1324
-
Konferensbidrag (refereegranskat)abstract
- In process automation installations, the I/O system connect the field devices to the process controller over a fieldbus, a reliable, real-time capable communication link with signal values cyclical being exchanged with a 10-100 millisecond rate. If a deviation from intended behaviour occurs, analyzing the potentially vast data recordings from the field can be a time consuming and cumbersome task for an engineer. For the engineer to be able to get a full understanding of the problem, knowledge of the used I/O configuration is required. In the problem report, the configuration description is sometimes missing. In such cases it is difficult to use the recorded data for analysis of the problem.In this paper we present our ongoing work towards using neural network models as assistance in the interpretation of an industrial fieldbus communication recording. To show the potential of such an approach we present an example using an industrial setup where fieldbus data is collected and classified. In this context we present an evaluation of the suitability of different neural net configurations and sizes for the problem at hand.
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| 23. |
- Johansson, Bjarne, et al.
(författare)
-
Concurrency defect localization in embedded systems using static code analysis : An evaluation
- 2019
-
Ingår i: Proceedings - 2019 IEEE 30th International Symposium on Software Reliability Engineering Workshops, ISSREW 2019. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728151380 ; , s. 7-12
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Konferensbidrag (refereegranskat)abstract
- Defects with low manifestation probability, such as concurrency defects, are difficult to find during testing. When such a defect manifests into an error, the low likelihood can make it time-consuming to reproduce the error and find the root cause. Static Code Analysis (SCA) tools have been used in the industry for decades, mostly for compliance checking towards guidelines such as MISRA. Today, these tools are capable of sophisticated data and execution flow analysis. Our work, presented in this paper, evaluates the feasibility of using SCA tools for concurrency defect detection and localization. Earlier research has categorized concurrency defects. We use this categorization and develop an object-oriented C++ based test suite containing defects from each category. Secondly, we use known and real defects in existing products' source code. With these two approaches, we perform the evaluation, using tools from some of the largest commercial actors in the field. Based on our results, we provide a discussion about how to use static code analysis tools for concurrency defect detection in complex embedded real-Time systems.
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| 24. |
- Konstantinos, Angelopoulos, et al.
(författare)
-
Adaptive predictive control for software systems
- 2015
-
Ingår i: Proceedings of the 1st International Workshop on Control Theory for Software Engineering. - New York, NY, USA : ACM. - 9781450338141 ; , s. 17-21
-
Konferensbidrag (refereegranskat)abstract
- Self-adaptive software systems are designed to support a number of alternative solutions for fulfilling their requirements. These define an adaptation space. During operation, a self-adaptive system monitors its performance and when it finds that its requirements are not fulfilled, searches its adaptation space to select a best adaptation. Two major problems need to be addressed during the selection process: (a) Handling environmental uncertainty in determining the impact of an adaptation; (b) maintain an optimal equilibrium among conflicting requirements. This position paper investigates the application of Adaptive Model Predictive Control ideas from Control Theory to design self-adaptive software that makes decisions by predicting its future performance for alternative adaptations and selects ones that minimize the cost of requirement failures using quantitative information. The technical details of our proposal are illustrated through the meeting-scheduler exemplar.
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| 25. |
- Konstantinos, Angelopoulos, et al.
(författare)
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Engineering Self-Adaptive Software Systems : From Requirements to Model Predictive Control
- 2018
-
Ingår i: ACM Transactions on Autonomous and Adaptive Systems. - : Association for Computing Machinery (ACM). - 1556-4665 .- 1556-4703. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- Self-adaptive software systems monitor their operation and adapt when their requirements fail due to unexpected phenomena in their environment. This article 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 myriad successful applications. The article focuses on modeling 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 two simulated systems, namely, the Meeting-Scheduling exemplar and an E-Shop.
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| 26. |
- Lager, Anders, et al.
(författare)
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Towards Reactive Robot Applications in Dynamic Environments
- 2019
-
Ingår i: The 24th IEEE Conference on Emerging Technologies and Factory Automation ETFA2019. - 9781728103037 ; , s. 1603-1606
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Konferensbidrag (refereegranskat)abstract
- Traditionally, industrial robots have been deployed in fairly static environments, to perform highly dedicated tasks. These robots perform with very high precision and throughput. However, nowadays there is an increasing demand for utilizing robots in more dynamic environments, also performing more flexible and less specialized operations — high mix/low volume. Both traditional industrial robots and force-limited robots are used in collaborative, dynamic environments. Such robot applications introduce new challenges when it comes to efficiency and robustness. In this paper, we propose an architecture for reactive multi-robot applications in the context of dynamic environments, and we analyze the main research challenges that must be tackled for its realization. A logistics use case, with robots picking customer orders from the shelves of a warehouse, is used as a running example to support the description of the key challenges.
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| 27. |
- Lakew, Ewnetu Bayuh, et al.
(författare)
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KPI-agnostic Control for Fine-Grained Vertical Elasticity
- 2017
-
Ingår i: 2017 17TH IEEE/ACM INTERNATIONAL SYMPOSIUM ON CLUSTER, CLOUD AND GRID COMPUTING (CCGRID). - : IEEE. - 9781509066117 ; , s. 589-598
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Konferensbidrag (refereegranskat)abstract
- Applications hosted in the cloud have become indispensable in several contexts, with their performance often being key to business operation and their running costs needing to be minimized. To minimize running costs, most modern virtualization technologies such as Linux Containers, Xen, and KVM offer powerful resource control primitives for individual provisioning - that enable adding or removing of fraction of cores and/or megabytes of memory for as short as few seconds. Despite the technology being ready, there is a lack of proper techniques for fine-grained resource allocation, because there is an inherent challenge in determining the correct composition of resources an application needs, with varying workload, to ensure deterministic performance.This paper presents a control-based approach for the management of multiple resources, accounting for the resource consumption, together with the application performance, enabling fine-grained vertical elasticity. The control strategy ensures that the application meets the target performance indicators, consuming as less resources as possible. We carried out an extensive set of experiments using different applications – interactive with response-time requirements, as well as non-interactive with throughput desires – by varying the workload mixes of each application over time. The results demonstrate that our solution precisely provides guaranteed performance while at the same time avoiding both resource over- and under-provisioning.
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| 28. |
- Leva, Alberto, et al.
(författare)
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Disturbance rejection in autotuners: an assessment method and a rule proposal
- 2015
-
Ingår i: American Control Conference (ACC), 2015. - 9781479986842 ; , s. 2876-2881
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Konferensbidrag (refereegranskat)abstract
- Disturbance rejection is a primary objective in many industrial control loops, thus a relevant goal for autotuning controllers. Nonetheless, autotuning has invariantly to cope with a reduced amount of process information. As a consequence, with the standard single-loop structure typically adopted in the addressed context, effective disturbance rejection calls for strong feedback, and therefore the solutions available to date fall sometimes short of perfection. This paper discusses the matter basically from a methodological standpoint, evidencing some structural reasons for the observed shortcomings. The result is a synthesis approach improving rejection performance with respect to existing and well established tuning rules, on a rigorously sound basis. Simulation examples are presented to support the proposal.
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| 29. |
- Leva, Alberto, et al.
(författare)
-
Explicit Model-Based Real PID Tuning for Efficient Load Disturbance Rejection
- 2019
-
Ingår i: Industrial & Engineering Chemistry Research. - : AMER CHEMICAL SOC. - 0888-5885 .- 1520-5045. ; 58:51, s. 23211-23224
-
Tidskriftsartikel (refereegranskat)abstract
- In the process control, many PID loops are primarily devoted to rejecting load disturbances, and some of them are crucial for the quality of the overall plant operation. In such a scenario, automatic tuning is highly desired. However, load disturbance rejection calls for strong feedback up to quite high frequencies with respect to the dominant plant dynamics, on which most tuning rules are centered. As such it is difficult for a rule to yield good and, above all, uniform results in the face of all the various process structures it can be confronted with. In this paper, we propose an explicit model-based PID tuning rule specifically targeted at the problem just evidenced. The rule minimizes the magnitude of the nominal disturbance-to-output frequency response, at the same time preventing that magnitude to exhibit a peak or a plateau around its maximum. This characteristic, together with tuning the PID derivative filter, leads to sharp disturbance rejection without incurring in an excessive control sensitivity to high-frequency measurement noise and mitigates the problems caused by heterogeneous process dynamics. The proposed approach is assessed by comparing the rule with selected counterparts, on a literature benchmark with different process structures. A laboratory experiment is finally presented to show that our rule can withstand real-world operating conditions.
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| 30. |
- Leva, Alberto, et al.
(författare)
-
High-Precision Low-Power Wireless Nodes' Synchronization via Decentralized Control
- 2016
-
Ingår i: IEEE Transactions on Control Systems Technology. - United States : IEEE. - 1063-6536 .- 1558-0865. ; 24:4, s. 1279-1293
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract: Time synchronization is crucial for wireless sensor networks (WSNs), where operations often rely on time ordering of events. WSNs are deployed in different scenarios, and therefore their timing requirements are often related to the peculiar characteristics of the specific environment they have to act in. Synchronization is anyway always an issue: transactional applications need monotonicity of the nodes' clocks to avoid time reversal, ultralow power applications call for minimal overhead to allow for low-duty-cycle operation, applications facing extreme environments have to maintain the needed precision in the presence of unforeseen thermal drift, and so on. Specially, control applications on battery-powered devices, where timing is an issue and low-power operation is highly desired, benefit from synchronization. However, to date, the problem of synchronization has been differently faced depending on the application domain. This paper proposes a general solution to the problem of synchronization in WSNs, which seamlessly integrates with the radio stack. In addition, it guarantees monotonic and continuous node clocks with low overhead for the infrastructure. The solution is based on a decentralized control scheme that is stable and robust to thermal stress, without the need for temperature measurements. The control scheme is simulated and implemented on real WSN nodes. The efficiency of the scheme is evaluated with simulations and experiments, providing insights on the maximum synchronization error between nodes, on the communication overhead, and on the limited nodes' power consumption. The solution is also compared with state-of-the-art alternatives.
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| 31. |
- Leva, Alberto, et al.
(författare)
-
Modelling and Control of Big Data Frameworks
- 2017
-
Ingår i: IFAC-PapersOnLine, Vol. 50. - : Elsevier BV. ; , s. 6110-6115
-
Konferensbidrag (refereegranskat)abstract
- We present a model library conceived to design and assess critical components of big data frameworks, with a control-centric approach. The library adopts the object-oriented paradigm, using the Modelica language. Continuous-time and algorithmic models can be mixed, allowing to represent control code with high fidelity, and to reduce the simulation effort to the minimum required. We discuss the used modelling principles, describe the library, and show some design examples.
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| 32. |
- Leva, Alberto, et al.
(författare)
-
Progress Rate Control for Computer Applications
- 2018
-
Ingår i: 17th annual European Control Conference ECC18. - Limassol, Cyprus. - 9783952426982 ; , s. 3173-3178
-
Konferensbidrag (refereegranskat)abstract
- Self-adaptive software applications often include some form of progress rate control. Various frameworks were proposed to measure progress and provision resources to govern it, hence - in control terms - for sensors and actuators. The same is not true for control laws, however. In this paper we address this part of the overall problem, proposing a standard control structure that can be easily configured and tuned to match a variety of progress control needs. We completely analyse the simplest case, namely a single application under fixed rate control, and spend a few words on extensions to multiple application and event-based realisation. Simulation examples are reported to support the proposal.
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| 33. |
- Maggio, Martina, et al.
(författare)
-
Automated Control of Multiple Software Goals using Multiple Actuators
- 2017
-
Ingår i: ESEC/FSE 2017 Proceedings of the 2017 11th Joint Meeting on Foundations of Software Engineering. - New York, NY, USA : ACM. - 9781450351058 ; , s. 373-384
-
Konferensbidrag (refereegranskat)abstract
- Modern software should satisfy multiple goals simultaneously: it should provide predictable performance, be robust to failures, handle peak loads and deal seamlessly with unexpected conditions and changes in the execution environment. For this to happen, software designs should account for the possibility of runtime changes and provide formal guarantees of the software's behavior. Control theory is one of the possible design drivers for runtime adaptation, but adopting control theoretic principles often requires additional, specialized knowledge. To overcome this limitation, automated methodologies have been proposed to extract the necessary information from experimental data and design a control system for runtime adaptation. These proposals, however, only process one goal at a time, creating a chain of controllers. In this paper, we propose and evaluate the first automated strategy that takes into account multiple goals without separating them into multiple control strategies. Avoiding the separation allows us to tackle a larger class of problems and provide stronger guarantees. We test our methodology's generality with three case studies that demonstrate its broad applicability in meeting performance, reliability, quality, security, and energy goals despite environmental or requirements changes.
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| 34. |
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| 35. |
- Maggio, Martina, et al.
(författare)
-
Self-Adaptive Video Encoder : Comparison of Multiple Adaptation Strategies Made Simple
- 2017
-
Ingår i: Proceedings - 2017 IEEE/ACM 12th International Symposium on Software Engineering for Adaptive and Self-Managing Systems, SEAMS 2017. - Buenos Aires, Argentina. - 9781538615508 ; , s. 123-128
-
Konferensbidrag (refereegranskat)abstract
- This paper presents an adaptive video encoder that can be used to compare the behavior of different adaptation strategies using multiple actuators to steer the encoder towards a global goal, composed of multiple conflicting objectives. A video camera produces frames that the encoder manipulates with the objective of matching some space requirement to fit a given communication channel. A second objective is to maintain a given similarity index between the manipulated frames and the original ones. To achieve the goal, the software can change three parameters: the quality of the encoding, the noise reduction filter radius and the sharpening filter radius. In most cases, the objectives - small encoded size and high quality - conflict, since a larger frame would have a higher similarity index to its original counterpart. This makes the problem difficult from the control perspective and makes the case study appealing to compare different adaptation strategies.
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| 36. |
- Miloradović, Branko, et al.
(författare)
-
Extended colored traveling salesperson for modeling multi-agent mission planning problems
- 2019
-
Ingår i: ICORES 2019 - Proceedings of the 8th International Conference on Operations Research and Enterprise Systems. - : SciTePress. - 9789897583520 ; , s. 237-244
-
Konferensbidrag (refereegranskat)abstract
- In recent years, multi-agent systems have been widely used in different missions, ranging from underwater to airborne. A mission typically involves a large number of agents and tasks, making it very hard for the human operator to create a good plan. A search for an optimal plan may take too long, and it is hard to make a time estimate of when the planner will finish. A Genetic algorithm based planner is proposed in order to overcome this issue. The contribution of this paper is threefold. First, an Integer Linear Programming (ILP) formulation of a novel Extensive Colored Traveling Salesperson Problem (ECTSP) is given. Second, a new objective function suitable for multi-agent mission planning problems is proposed. Finally, a reparation algorithm to allow usage of common variation operators for ECTSP has been developed.
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| 37. |
- Miloradović, Branko, et al.
(författare)
-
TAMER : Task Allocation in Multi-robot Systems Through an Entity-Relationship Model
- 2019
-
Ingår i: PRIMA 2019. - Cham : Springer International Publishing. - 9783030337919 ; , s. 478-486
-
Konferensbidrag (refereegranskat)abstract
- Multi-robot task allocation (MRTA) problems have been studied extensively in the past decades. As a result, several classifications have been proposed in the literature targeting different aspects of MRTA, with often a few commonalities between them. The goal of this paper is twofold. First, a comprehensive overview of early work on existing MRTA taxonomies is provided, focusing on their differences and similarities. Second, the MRTA problem is modelled using an Entity-Relationship (ER) conceptual formalism to provide a structured representation of the most relevant aspects, including the ones proposed within previous taxonomies. Such representation has the advantage of (i) representing MRTA problems in a systematic way, (ii) providing a formalism that can be easily transformed into a software infrastructure, and (iii) setting the baseline for the definition of knowledge bases, that can be used for automated reasoning in MRTA problems.
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| 38. |
- Moreno, Gabriel, et al.
(författare)
-
Comparing Model-Based Predictive Approaches to Self-Adaptation : CobRA and PLA
- 2017
-
Ingår i: 12th International Symposium on Software Engineering for Adaptive and Self-Managing Systems SEAMS 17. ; , s. 42-53
-
Konferensbidrag (refereegranskat)abstract
- Modern software-intensive systems must often guarantee certain quality requirements under changing run-time conditions and high levels of uncertainty. Self-adaptation has proven to be an effective way to engineer systems that can address such challenges, but many of these approaches are purely reactive and adapt only after a failure has taken place. To overcome some of the limitations of reactive approaches (e.g., lagging behind environment changes and favoring short-term improvements), recent proactive self-adaptation mechanisms apply ideas from control theory, such as model predictive control (MPC), to improve adaptation. When selecting which MPC approach to apply, the improvement that can be obtained with each approach is scenario-dependent, and so guidance is needed to better understand how to choose an approach for a given situation. In this paper, we compare CobRA and PLA, two approaches that are inspired by MPC. CobRA is a requirements-based approach that applies control theory, whereas PLA is architecture-based and applies stochastic analysis. We compare the two approaches applied to RUBiS, a benchmark system for web and cloud application performance, discussing the required expertise needed to use both approaches and comparing their run-time performance with respect to different metrics.
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| 39. |
- Mubeen, Saad, et al.
(författare)
-
Management of Service Level Agreements for Cloud Services in IoT : A Systematic Mapping Study
- 2018
-
Ingår i: IEEE Access. - United States : IEEE. - 2169-3536. ; 6, s. 30184-30207
-
Tidskriftsartikel (refereegranskat)abstract
- Cloud computing and Internet of Things (IoT) are computing technologies that provide services to consumers and businesses, allowing organizations to become more agile and flexible. Therefore, ensuring Quality of Service (QoS) through Service Level Agreements (SLAs) for such cloud-based services is crucial for both the service providers and service consumers. As SLAs are critical for cloud deployments and wider adoption of cloud services, the management of SLAs in cloud and IoT has thus become an important and essential aspect. This paper investigates the existing research on the management of SLAs in IoT applications that are based on cloud services. For this purpose, a Systematic Mapping study (a well-defined method) is conducted to identify the published research results that are relevant to SLAs. The paper identifies 328 primary studies and categorizes them into seven main technical classifications: SLA management, SLA definition, SLA modeling, SLA negotiation, SLA monitoring, SLA violation and trustworthiness, and SLA evolution. The paper also summarizes the research types, research contributions, and demographic information in these studies. The evaluation of the results show that most of the approaches for managing SLAs are applied in academic or controlled experiments with limited industrial settings rather than in real industrial environments. Many studies focus on proposal models and methods to manage SLAs, and there is a lack of focus on the evolution perspective and a lack of adequate tool support to facilitate practitioners in their SLA management activities. Moreover, the scarce number of studies focusing on concrete metrics for qualitative or quantitative assessment of QoS in SLAs urges the need for in-depth research on metrics definition and measurements for SLAs.
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| 40. |
- Papadopoulos, Alessandro, et al.
(författare)
-
A Dynamic Modelling Framework for Control-based Computing System Design
- 2015
-
Ingår i: Mathematical and Computer Modelling of Dynamical Systems. - United Kingdom : Taylor & Francis. - 1387-3954 .- 1744-5051. ; 21:3, s. 251-271
-
Tidskriftsartikel (refereegranskat)abstract
- This manuscript proposes a novel viewpoint on computing systems’ modelling. The classical approach is to consider fully functional systems and model them, aiming at closing some external loops to optimize their behaviour. On the contrary, we only model strictly physical phenomena, and realize the rest of the system as a set of controllers. Such an approach permits rigorous assessment of the obtained behaviour in mathematical terms, which is hardly possible with the heuristic design techniques, that were mainly adopted to date. The proposed approach is shown at work with three relevant case studies, so that a significant generality can be inferred from it.
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| 41. |
- Papadopoulos, Alessandro, et al.
(författare)
-
AdaptMC : A control-theoretic approach for achieving resilience in mixed-criticality systems
- 2018
-
Ingår i: Leibniz International Proceedings in Informatics, LIPIcs. - : Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing. - 9783959770750
-
Konferensbidrag (refereegranskat)abstract
- A system is said to be resilient if slight deviations from expected behavior during run-time does not lead to catastrophic degradation of performance: minor deviations should result in no more than minor performance degradation. In mixed-criticality systems, such degradation should additionally be criticality-cognizant. The applicability of control theory is explored for the design of resilient run-time scheduling algorithms for mixed-criticality systems. Recent results in control theory have shown how appropriately designed controllers can provide guaranteed service to hardreal- time servers; this prior work is extended to allow for such guarantees to be made concurrently to multiple criticality-cognizant servers. The applicability of this approach is explored via several experimental simulations in a dual-criticality setting. These experiments demonstrate that our control-based run-time schedulers can be synthesized in such a manner that bounded deviations from expected behavior result in the high-criticality server suffering no performance degradation and the lower-criticality one, bounded performance degradation.
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| 42. |
- Papadopoulos, Alessandro, et al.
(författare)
-
Control-based load-balancing techniques : Analysis and performance evaluation via a randomized optimization approach
- 2016
-
Ingår i: Control Engineering Practice. - : Elsevier. - 0967-0661 .- 1873-6939. ; 52, s. 24-34
-
Tidskriftsartikel (refereegranskat)abstract
- Cloud applications are often subject to unexpected events like flashcrowds and hardware failures. Users that expect a predictable behavior may abandon an unresponsive application when these events occur. Researchers and engineers addressed this problem on two separate fronts: first, they introduced replicas - copies of the application with the same functionality - for redundancy and scalability; second, they added a self-adaptive feature called brownout inside cloud applications to bound response times by modulating user experience. The presence of multiple replicas requires a dedicated component to direct incoming traffic: a load-balancer. Existing load-balancing strategies based on response times interfere with the response time controller developed for brownout-compliant applications. In fact, the brownout approach bounds response times using a control action. Hence, the response time, that was used to aid load-balancing decision, is not a good indicator of how well a replica is performing. To fix this issue, this paper reviews some proposal for brownout-aware load-balancing and provides a comprehensive experimental evaluation that compares them. To provide formal guarantees on the load balancing performance, we use a randomized optimization approach and apply the scenario theory. We perform an extensive set of experiments on a real machine, extending the popular lighttpd web server and load-balancer, and obtaining a production-ready implementation. Experimental results show an improvement of the user experience over Shortest Queue First (SQF)-believed to be near-optimal in the non-adaptive case. The improved user experience is obtained preserving the response time predictability.
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| 43. |
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| 44. |
- Papadopoulos, Alessandro, et al.
(författare)
-
Hard Real-Time Guarantees in Feedback-based Resource Reservations
- 2015
-
Ingår i: Real-Time Systems RTSJ. - United States : Springer US. - 0922-6443 .- 1573-1383. ; 51:3, s. 221-246
-
Tidskriftsartikel (refereegranskat)abstract
- Resource reservation is a technique that allows isolating applications from interfering among each other. In the most classic setting, this method requires the periodic allocation of a given budget of resource over time. However, in reality, the actual budget allocation may deviate from its ideal value. Examples of causes of this deviation are: the presence of a system tick, the usage of shared resources, the self-blocking on I/O operations, etc. Since control techniques are an effective mean to deal with uncertainties and disturbances, unknown at design time but bounded, in this paper we propose to use feedback to achieve the target budget allocation, which may have deviated due to on-line events. The proposed scheme, called Self-Adaptive Server (SAS), is described and analyzed. We prove that the controller gain, which maximizes the resource delivered to the application, is (3-sqrt(5))/2. We also implemented the scheduler on a lightweight operating system for a microcontroller. Thanks to the extremely simple implementation, SAS servers are well suited for low-overhead resource isolation mechanisms with proved real-time guarantees.
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| 45. |
- Papadopoulos, Alessandro, et al.
(författare)
-
Model reduction of switched affine systems
- 2016
-
Ingår i: Automatica. - United States : Elsevier. - 0005-1098 .- 1873-2836. ; 70, s. 57-65
-
Tidskriftsartikel (refereegranskat)abstract
- This paper addresses model reduction and extends balanced truncation to the class of switched affine systems with endogenous switching. The switched affine system is rewritten as a switched linear one with state resets that account for the affine terms. Balanced truncation can then be applied to each mode dynamics, independently. As a result, different reduced state vectors are associated with the different modes, and reset maps are here appropriately redefined so as to account and compensate for this mismatch, possibly preserving the continuity of the output. The overall behavior of the reduced switched system is determined by both the selected reduction per mode and the adopted reset maps. In this paper, we consider a stochastic setting and propose a randomized method for the selection of the reduced order. The performance of the proposed approach is illustrated through a multi-room temperature control example.
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| 46. |
- Papadopoulos, Alessandro, et al.
(författare)
-
PEAS : A Performance Evaluation framework for Auto-Scaling strategies in cloud applications
- 2016
-
Ingår i: ACM Transactions on Modeling and Performance Evaluation of Computing Systems. - United States : Association for Computing Machinery (ACM). - 2376-3639 .- 2376-3647. ; :4
-
Tidskriftsartikel (refereegranskat)abstract
- Numerous auto-scaling strategies have been proposed in the last few years for improving various Quality of Service (QoS)indicators of cloud applications, e.g., response time and throughput, by adapting the amount of resources assigned to theapplication to meet the workload demand. However, the evaluation of a proposed auto-scaler is usually achieved throughexperiments under specific conditions, and seldom includes extensive testing to account for uncertainties in the workloads, andunexpected behaviors of the system. These tests by no means can provide guarantees about the behavior of the system in generalconditions. In this paper, we present PEAS, a Performance Evaluation framework for Auto-Scaling strategies in the presenceof uncertainties. The evaluation is formulated as a chance constrained optimization problem, which is solved using scenariotheory. The adoption of such a technique allows one to give probabilistic guarantees of the obtainable performance. Six differentauto-scaling strategies have been selected from the literature for extensive test evaluation, and compared using the proposedframework. We build a discrete event simulator and parameterize it based on real experiments. Using the simulator, each auto-scaler’s performance is evaluated using 796 distinct real workload traces from projects hosted on the Wikimedia foundations’servers, and their performance is compared using PEAS. The evaluation is carried out using different performance metrics,highlighting the flexibility of the framework, while providing probabilistic bounds on the evaluation and the performance of thealgorithms. Our results highlight the problem of generalizing the conclusions of the original published studies and show thatbased on the evaluation criteria, a controller can be shown to be better than other controllers.
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| 47. |
- Papadopoulos, Alessandro, et al.
(författare)
-
Power-aware cloud brownout : Response time and power consumption control
- 2017
-
Ingår i: 2017 IEEE 56th Annual Conference on Decision and Control (CDC). - : IEEE. - 9781509028733 - 9781509028726 - 9781509028740 ; , s. 2686-2691
-
Konferensbidrag (refereegranskat)abstract
- Cloud computing infrastructures are powering most of the web hosting services that we use at all times. A recent failure in the Amazon cloud infrastructure made many of the website that we use on a hourly basis unavailable1. This illustrates the importance of cloud applications being able to absorb peaks in workload, and at the same time to tune their power requirements to the power and energy capacity offered by the data center infrastructure. In this paper we combine an established technique for response time control — brownout — with power capping. We use cascaded control to take into account both the need for predictability in the response times (the inner loop), and the power cap (the outer loop). We execute tests on real machines to determine power usage and response times models and extend an existing simulator. We then evaluate the cascaded controller approach with a variety of workloads and both open- and closed-loop client models.
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| 48. |
- Papadopoulos, Alessandro, et al.
(författare)
-
SLAs for Industrial IoT : Mind the Gap
- 2017
-
Ingår i: The 4th International Symposium on Inter-cloud and IoT (ICI 2017) ICI'17. - 9781538632819 ; , s. 75-78
-
Konferensbidrag (refereegranskat)abstract
- Cloud computing and Internet of Things (IoT) are computing technologies that provide services to consumers and businesses, allowing organizations to become more agile and flexible. The potential business values that cloud consumers can achieve depend a lot on the quality of service in the provided cloud services. Therefore, ensuring the quality of service through service-level agreements (SLA) for such cloud-based services is crucial for both the service providers and service consumers. As SLA is critical for cloud deployments and wider adoption of cloud services, the management of SLA in cloud and IoT has thus become an important and essential issue. In this paper we provide an understanding of the current status and maturity level of SLA management in industrial IoT and academic efforts in this field. We also conduct a preliminary survey of current research on SLA management in order to identify open challenges and gaps that need to be addressed in future research directions. In particular, we investigate how to provide useful SLA management support adapted to the maturity level and current industrial practices, and shorten the gap between academia and industry.
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| 49. |
- Papadopoulos, Alessandro, et al.
(författare)
-
Switched Control for Quantized Feedback Systems : Invariance and Limit Cycle Analysis
- 2018
-
Ingår i: IEEE Transactions on Automatic Control. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9286 .- 1558-2523. ; 63:11, s. 3775-3786
-
Tidskriftsartikel (refereegranskat)abstract
- We study feedback control for a discrete-time integrator with unitary delay in the presence of quantization both in the control action and in the measurement of the controlled variable. In some applications the quantization effects can be neglected, but when high precision is needed, they have to be explicitly accounted for in control design. In this paper, we propose a switched control solution for minimizing the effect of quantization of both the control and controlled variables for the considered system, that is quite common in the computing systems domain, for example, in thread scheduling, clock synchronization, and resource allocation. We show that the switched solution outperforms the one without switching, designed by neglecting quantization, and analyze necessary and sufficient conditions for the controlled system to exhibit periodic solutions in the presence of an additive constant disturbance affecting the control input. Simulation results provide evidence of the effectiveness of the approach.
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| 50. |
- Papadopoulos, Alessandro Vittorio, et al.
(författare)
-
A control-theoretical approach to thread scheduling for multicore processors
- 2015
-
Ingår i: [Host publication title missing].
-
Konferensbidrag (refereegranskat)abstract
- Feedback control has been applied to computing systems, usually taking a designed system and closing a loop to adjust some of its parameters. However, the design of computing systems components as controllers have shown advantages with respect to state-of-the-art techniques, especially in the scheduling domain, where uniprocessor schedulers have been designed as discrete-time control structures. However, the most recent computing devices (from smartphone to personal computers) have more than one core and the devised techniques cannot be applied to this context directly. This paper provides the necessary foundation to address the multicore scheduling problem as a control problem, as an extension of the uniprocessor case. We qualify the quantities to be measured and used as feedback signals for tackling the extension. We also present some control solutions and compare them using a simulator, publicly available to foster the research on the topic. The comparison shows that the devised policies have low computational complexity but achieves very good results in terms of scalability.
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