| 1. |
- Bucchiarone, Antonio, et al.
(författare)
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On the Social Implications of Collective Adaptive Systems
- 2020
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Ingår i: IEEE technology & society magazine. - : IEEE. - 0278-0097 .- 1937-416X. ; 39:3, s. 36-46
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Tidskriftsartikel (refereegranskat)abstract
- Many Collect ive Adaptive Systems (CASs) exist in nature: think of ant colonies, where large collectives of ants operate autonomously but interact with other ants and the environment to provide resilient global behaviors that sustain their colony. Following scientific studies that were aimed at understanding and predicting the evolution of these systems, and fueled by technological advances, research has started to investigate CAS engineering: the methods, tools, and techniques for building CASs. This naturally leads to a vision where collectives of humans and computational elements, situated both in the digital and physical worlds, collaborate to give rise to "intelligent" collective behavior supporting novel kinds of applications and services. Humans can be involved in two ways: both as users and as components of the CAS, in the sense that human behaviors and limitations are often integral to the system description. This has significant social implications that need to be considered by CAS researchers: in this paper, we share a discussion that took place between some experts thinking about CAS engineering, focusing on the social implication of CASs and related open research challenges. We hope that this provides a useful context for future research projects, research grant proposals, and research directions.
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| 2. |
- Andersson, Jesper, 1970-, et al.
(författare)
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Architecting decentralized control in large-scale self-adaptive systems
- 2023
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Ingår i: Computing. - : Springer. - 0010-485X .- 1436-5057. ; 105, s. 1849-1882
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Tidskriftsartikel (refereegranskat)abstract
- Architecting a self-adaptive system with decentralized control is challenging. Indeed, architects shall consider several different and interdependent design dimensions and devise multiple control loops to coordinate and timely perform the correct adaptations. To support this task, we propose Decor, a reasoning framework for architecting and evaluating decentralized control. Decor provides (i) multi-paradigm modeling support, (ii) a modeling environment for MAPE-K style decentralized control, and (iii) a co-simulation environment for simulating the decentralized control together with the managed system and estimating the quality attributes of interest. We apply the Decor in three case studies: an intelligent transportation system, a smart power grid, and a cloud computing application. The studies demonstrate the framework’s capabilities to support informed architectural decisions on decentralized control and adaptation strategies.
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| 3. |
- Caporuscio, Mauro, 1975-, et al.
(författare)
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Decentralized Architecture for Energy-Aware Service Assembly
- 2020
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Ingår i: Software Architecture. - Cham : Springer. - 9783030589226 - 9783030589233 ; , s. 57-72
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Konferensbidrag (refereegranskat)abstract
- Contemporary application domains make more and more appealing the vision of applications built as a dynamic and opportunistic assembly of autonomous and independent resources. However, the adoption of such paradigm is challenged by: (i) the openness and scalability needs of the operating environment, which rule out approaches based on centralized architectures and, (ii) the increasing concern for sustainability issues, which makes particularly relevant, in addition to QoS constraints, the goal of reducing the application energy footprint. In this context, we contribute by proposing a decentralized architecture to build a fully functional assembly of distributed services, able to optimize its energy consumption, paying also attention to issues concerning the delivered quality of service. We suggest suitable indexes to measure from different perspectives the energy efficiency of the resulting assembly, and present the results of extensive simulation experiments to assess the effectiveness of our approach.
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| 4. |
- Caporuscio, Mauro, et al.
(författare)
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Reinforcement Learning Techniques for Decentralized Self-adaptive Service Assembly
- 2016
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Ingår i: SERVICE-ORIENTED AND CLOUD COMPUTING, (ESOCC 2016). - Cham : Springer. - 9783319444826 - 9783319444819 ; , s. 53-68
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a self-organizing fully decentralized solution for the service assembly problem, whose goal is to guarantee a good overall quality for the delivered services, ensuring at the same time fairness among the participating peers. The main features of our solution are: (i) the use of a gossip protocol to support decentralized information dissemination and decision making, and (ii) the use of a reinforcement learning approach to make each peer able to learn from its experience the service selection rule to be followed, thus overcoming the lack of global knowledge. Besides, we explicitly take into account load-dependent quality attributes, which lead to the definition of a service selection rule that drives the system away from overloading conditions that could adversely affect quality and fairness. Simulation experiments show that our solution self-adapts to occurring variations by quickly converging to viable assemblies maintaining the specified quality and fairness objectives.
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| 5. |
- Cardellini, Valeria, et al.
(författare)
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A Decentralized Approach to Network-Aware Service Composition
- 2015
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Ingår i: Service Oriented and Cloud Computing - 4th European Conference, ESOCC 2015, Taormina, Italy, September 15-17, 2015. Proceedings. - Cham : Springer. - 9783319240725 - 9783319240718 ; , s. 34-48
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Konferensbidrag (refereegranskat)abstract
- Dynamic service composition represents a key feature for service-based applications operating in dynamic and large scale network environments, as it allows leveraging the variety of offered services, and to cope with their volatility. However, the high number of services and the lack of central control pose a significant challenge for the scalability and effectiveness of the composition process. We address this problem by proposing a fully decentralized approach to servicecomposition, based on the use of a gossip protocol to support information dissemination and decision making. The proposed system builds and maintains acomposition of services that fulfills both functional and non functional requirements. For the latter, we focus in particular on requirements concerning the composite service completion time, taking into account both the response time and the impact of network latency. Simulation experiments show that our solution converges quickly to a feasible composition and can self-adapt to dynamic changes concerning both service availability and network latency.
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| 6. |
- D'Angelo, Mirko, et al.
(författare)
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CyPhEF : A Model-driven Engineering Framework for Self-adaptive Cyber-physical Systems
- 2018
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Ingår i: Proceedings of the 40th International Conference on Software Engineering. - New York, NY, USA : ACM Press. - 9781450356633 ; , s. 101-104
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Konferensbidrag (refereegranskat)abstract
- Self-adaptation is nowadays recognized as an effective approach to deal with the uncertainty inherent to cyber-physical systems, which are composed of dynamic and deeply intertwined physical and software components interacting with each other. Engineering a self-adaptive cyber-physical system is challenging, as concerns about both the physical and the control system should be jointly considered. To this end, we present CyPhEF, a Model-Driven Engineering framework supporting the development and validation of self-adaptive cyber-physical systems.Demo video: https://youtu.be/nmg-w2kfKEA.
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| 7. |
- D'Angelo, Mirko, et al.
(författare)
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Decentralized learning for self-adaptive QoS-aware service assembly
- 2020
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Ingår i: Future Generation Computer Systems. - : Elsevier. - 0167-739X .- 1872-7115. ; 108, s. 210-227
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Tidskriftsartikel (refereegranskat)abstract
- The highly dynamic nature of future computing systems, where applications dynamically emerge as opportunistic aggregation of autonomous and independent resources available at any given time, requires a radical shift in the adopted computing paradigms. Indeed, they should fully reflect the decentralized perspective of the execution environment and consider QoS, scalability and resilience as key objectives. In this context, the everything-as-a-service (XaaS) paradigm, which envisions the creation of new services as an assembly of independent services available within the environment, can greatly help in tackling the challenges of developing future applications. However, in order to be effective, XaaS paradigm requires self-adaptive service assembly solutions able to cope with the unpredictable variability and scalability of the execution environment, the lack of global knowledge, and the QoS requirements of services to be built. We contribute in this direction by designing a fully decentralized and collective self-adaptive service assembly framework whose main features are: (i) self-assembly, i.e., the ability to operate autonomously, (ii) online-learning, i.e., the ability to dynamically learn from experience, (iii) QoS-awareness, i.e., the inclusion of QoS requirements as driving forces for self-assembly, (iv) scalability, i.e., the ability to cope with a large number of services, and (v) resilience, i.e., the ability to maintain the persistence of service delivery when facing unexpected changes (e.g., in the number and/or QoS of services). Simulation experiments show that our solution makes the system able to quickly converge to viable assemblies that improve and maintain over time the social welfare of the system, despite the local perspective of each participating service.
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| 8. |
- D'Angelo, Mirko
(författare)
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Decentralized Self-Adaptive Computing at the Edge
- 2018
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Ingår i: 2018 IEEE/ACM 13TH International Symposium on Software Engineering for Adaptive and Self-Managing Systems (SEAMS). - New York, NY, USA : IEEE. - 9781450357159 ; , s. 144-148
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Konferensbidrag (refereegranskat)abstract
- Nowadays, computing infrastructures are usually deployed in fully controlled environments and managed in a centralized fashion. Leveraging on centralized infrastructures prevent the system to deal with scalability and performance issues, which are inherent to modern large-scale data-intensive applications. On the other hand, we envision fully decentralized computing infrastructures deployed at the edge of the network providing the required support for operating data-intensive systems. However, engineering such systems raises many challenges, as decentralization introduces uncertainty, which in turn may harm the dependability of the system. To this end, self-adaptation is a key approach to manage uncertainties at runtime and satisfy the requirements of decentralized data-intensive systems. This paper shows the research directions and current contributions towards this vision by (i) evaluating the impact of the distribution of computational entities, (ii) engineering decentralized computing through self-adaptation and, (iii) evaluating decentralized and self-adaptive applications.
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| 9. |
- D'Angelo, Mirko
(författare)
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Engineering Decentralized Learning in Self-Adaptive Systems
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Future computing environments are envisioned to be populated by myriads of pervasive real-world things, which collaborate to offer boundless opportunities to industry and society -- e.g., smart cities, and intelligent transportation systems. In this setting, an application can be considered as a network-based system where applications dynamically emerge as opportunistic assemblies of services. This class of applications is likely characterized by high dynamism, with services joining and leaving the network and changing their quality attributes. Indeed, dynamic introduces uncertainty, which in turn may alter the system's functionalities and harm the system's quality of service. Although self-adaptation and machine learning techniques are proposed as viable approaches to address run-time uncertainties and support resilience, engineering effectively these systems is undoubtedly complex, since their peculiarities demand decentralized solutions. To this end, this thesis addresses the critical challenges for engineering decentralized learning in self-adaptive systems in three steps. First, it examines, classifies, and distills knowledge from research related to self-adaptive systems using learning techniques as means of addressing uncertainty. Then, it presents a reasoning framework that supports architecting and implementation activities with capabilities to evaluate architectural decisions. Finally, leveraging the solutions devised by addressing the aforementioned challenges, it proposes an approach to build and maintain over time a resilient assembly of services that are collectively able to deliver quality of service.Evaluation is performed through an extensive set of simulation experiments to assess the effectiveness of the approach. The results show that the devised solution, including self-adaptation and reinforcement learning as key elements, can cope with unpredictably variable operating environments and guarantee quality of service and resilience.
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| 10. |
- D'Angelo, Mirko, 1989-, et al.
(författare)
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Learning to Learn in Collective Adaptive Systems : Mining Design Patterns for Data-driven Reasoning
- 2020
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Ingår i: IEEE International Conference on Autonomic Computing and Self-Organizing Systems Companion (ACSOS-C). - : IEEE. - 9781728184142 ; , s. 121-126
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Konferensbidrag (refereegranskat)abstract
- Engineering collective adaptive systems (CAS) with learning capabilities is a challenging task due to their multidimensional and complex design space. Data-driven approaches for CAS design could introduce new insights enabling system engineers to manage the CAS complexity more cost-effectively at the design-phase. This paper introduces a systematic approach to reason about design choices and patterns of learning-based CAS. Using data from a systematic literature review, reasoning is performed with a novel application of data-driven methodologies such as clustering, multiple correspondence analysis and decision trees. The reasoning based on past experience as well as supporting novel and innovative design choices are demonstrated.
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| 11. |
- D'Angelo, Mirko, et al.
(författare)
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Model-driven Engineering of Decentralized Control in Cyber-Physical Systems
- 2017
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Ingår i: Proceedings of the 2nd International Workshop on Foundations and Applications of Self* Systems (FAS*W). - : IEEE. - 9781509065585 ; , s. 7-12
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Konferensbidrag (refereegranskat)abstract
- Self-Adaptation is nowadays recognized as an effective approach to manage the complexity and dynamics inherent to cyber-physical systems, which are composed of deeply intertwined physical and software components interacting with each other. A self-Adaptive system typically consists of a managed subsystem and a managing subsystem that implements the adaptation logic by means of the well established MAPE-K control loop. Since in large distributed settings centralized control is hardly adequate to manage the whole system, self-Adaptation should be achieved through collective decentralized control, that is multiple cyber-physical entities must adapt in order to address critical runtime conditions. Developing such systems is challenging, as several dimensions concerning both the cyber-physical system and the decentralized control loop should be considered. To this end, we promote MAPE-K components as first-class modeling abstractions and provide a framework supporting the design, development, and validation of decentralized self-Adaptive cyber-physical systems.
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| 12. |
- D'Angelo, Mirko, et al.
(författare)
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On learning in collective self-adaptive systems : state of practice and a 3D framework
- 2019
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Ingår i: 2019 IEEE/ACM 14th International Symposium on Software Engineering for Adaptive and Self-Managing Systems (SEAMS). - : IEEE. - 9781728133683 - 9781728133690 ; , s. 13-24
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Konferensbidrag (refereegranskat)abstract
- Collective self-adaptive systems (CSAS) are distributed and interconnected systems composed of multiple agents that can perform complex tasks such as environmental data collection, search and rescue operations, and discovery of natural resources. By providing individual agents with learning capabilities, CSAS can cope with challenges related to distributed sensing and decision-making and operate in uncertain environments. This unique characteristic of CSAS enables the collective to exhibit robust behaviour while achieving system-wide and agent-specific goals. Although learning has been explored in many CSAS applications, selecting suitable learning models and techniques remains a significant challenge that is heavily influenced by expert knowledge. We address this gap by performing a multifaceted analysis of existing CSAS with learning capabilities reported in the literature. Based on this analysis, we introduce a 3D framework that illustrates the learning aspects of CSAS considering the dimensions of autonomy, knowledge access, and behaviour, and facilitates the selection of learning techniques and models. Finally, using example applications from this analysis, we derive open challenges and highlight the need for research on collaborative, resilient and privacy-aware mechanisms for CSAS.
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| 13. |
- D'Angelo, Mirko, et al.
(författare)
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Pure Edge Computing Platform for the Future Internet
- 2016
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Ingår i: Software Technologies: Applications and Foundations (STAF 2016). - Vienna : Springer. - 9783319502298 - 9783319502304 ; , s. 458-469
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Konferensbidrag (refereegranskat)abstract
- Future Internet builds upon three key pillars – namely, Internet of Things, Internet of Services, and Internet of Contents – and is considered as a worldwide execution environment that interconnects myriad heterogeneous entities over time, supports information dissemination, enables the emergence of promising application domains, and stimulate new business and research opportunities. In this paper we analyse the challenges towards the actualisation of the Future Internet. We argue that the mobile nature inherent to modern communications and interactions requires a radical shift towards new computing paradigms that fully reflect the network-based perspective of the emerging environment. Indeed, we position the adoption of a Pure Edge Computing platform that offers designing and programming abstractions to specify, implement and operate Future Internet applications.
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| 14. |
- D'Angelo, Mirko, et al.
(författare)
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SA-Chord : A Self-Adaptive P2P Overlay Network
- 2018
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Ingår i: Proceedings. 2018 IEEE 3rd International Workshops on Foundations and Applications of Self* Systems. - Los Alamitos, CA : IEEE. - 9781538651759 ; , s. 118-123
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Konferensbidrag (refereegranskat)abstract
- Pure Edge Computing relies on peer-to-peer overlay networks to realize the communication backbone between participating entities. In these settings, entities are characterized by high heterogeneity, mobility, and variability, which introduce runtime uncertainty and may harm the dependability of the network. Departing from state-of-the-art solutions, overlay networks for Pure Edge Computing should take into account the dynamics of the operating environment and self-adapt their topology accordingly, in order to increase the dependability of the communication. To this end, this paper discusses the preliminary development and validation of SA-Chord, a self-adaptive version of the wellknown Chord protocol, able to adapt the network topology according to a given global goal. SA-Chord has been validated through simulation against two distinct goals: (i) minimize energy consumption and, (ii) maximize network throughput. Simulation results are promising and show how SA-Chord efficiently and effectively achieves a given goal.
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| 15. |
- D'Angelo, Mirko, et al.
(författare)
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Towards a Continuous Model-Based Engineering Process for QoS-Aware Self-adaptive Systems
- 2020
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Ingår i: International Conference on Software Engineering and Formal Methods SEFM 2019. - Cham : Springer. - 9783030575052 - 9783030575069 ; , s. 69-76
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Konferensbidrag (refereegranskat)abstract
- Modern information systems connecting software, physical systems, and people, are usually characterized by high dynamism. These dynamics introduce uncertainties, which in turn may harm the quality of service and lead to incomplete, inaccurate, and unreliable results. In this context, self-adaptation is considered as an effective approach for managing run-time uncertainty. However, classical approaches for quality engineering are not suitable to deal with run-time adaptation, as they are mainly used to derive the steady-state solutions of a system at design-time. In this paper, we envision a Continuous Model-based Engineering Process that makes use of architectural analysis in conjunction with experimentation to have a wider understanding of the system under development. These two activities are performed incrementally, and jointly used in a feedback loop to provide insights about the quality of the system-to-be. © 2020, Springer Nature Switzerland AG.
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| 16. |
- Flammini, Francesco, Senior Lecturer, 1978-, et al.
(författare)
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Safety integrity through self-adaptation for multi-sensor event detection : Methodology and case-study
- 2020
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Ingår i: Future Generation Computer Systems. - : Elsevier. - 0167-739X .- 1872-7115. ; 112, s. 965-981
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Tidskriftsartikel (refereegranskat)abstract
- Traditional safety-critical systems are engineered in a way to be predictable in all operating conditions. They are common in industrial automation and transport applications where uncertainties (e.g., fault occurrence rates) can be modeled and precisely evaluated. Furthermore, they use high-cost hardware components to increase system reliability. On the contrary, future systems are increasingly required to be "smart"(or "intelligent") that is to adapt to new scenarios, learn and react to unknown situations, possibly using low-cost hardware components. In order to move a step forward to fulfilling those new expectations, in this paper we address run-time stochastic evaluation of quantitative safety targets, like hazard rate, in self-adaptive event detection systems by using Bayesian Networks and their extensions. Self-adaptation allows changing correlation schemes on diverse detectors based on their reputation, which is continuously updated to account for performance degradation as well as modifications in environmental conditions. To that aim, we introduce a specific methodology and show its application to a case-study of vehicle detection with multiple sensors for which a real-world data-set is available from a previous study. Besides providing a proof-of-concept of our approach, the results of this paper pave the way to the introduction of new paradigms in the dynamic safety assessment of smart systems. (c) 2020 Elsevier B.V. All rights reserved.
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| 17. |
- Najafi, Leyla, et al.
(författare)
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Hybrid Organic/Inorganic Photocathodes Based on WS2 Flakes as Hole Transporting Layer Material
- 2021
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Ingår i: Small Structures. - : John Wiley & Sons. - 2688-4062. ; 2:3
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Tidskriftsartikel (refereegranskat)abstract
- The efficient production of molecular hydrogen (H2) is a fundamental step toward an environmentally friendly economy. Photocathodes using organic bulk heterojunction (BHJ) films as light harvesters represent an attracting technology for low-cost photoelectrochemical water splitting. These photocathodes need charge transporting layers (CTLs) to efficiently separate and transport either holes or electrons toward the back-current collector and electrolyte, respectively. Therefore, it is pivotal to control the energy band edge levels and the work function (WF) of the CTLs to match the ones of the BHJ film, current collector, and electrolyte. Herein, the use of 2D p-doped WS2 flakes as hole transporting material for H2-evolving photocathodes based on the regioregular poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (rr-P3HT:PCBM) BHJ film is proposed. The WS2 flakes are produced through scalable liquid-phase exfoliation of the bulk crystal, whereas p-type chemical doping allows the tuning of the WS2 WF. This approach boosts the performances of the photocathodes, reaching photocurrent densities up to 4.14 mA cm−2 at 0 V versus reversible hydrogen electrode (RHE), an onset potential of 0.66 V versus RHE, and a ratiometric power-saved metric of 1.28% (under 1 sun illumination). To the best of the authors' knowledge, these performances represent the current record for 2D materials-based CTLs.
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| 18. |
- Pagliari, Lorenzo, et al.
(författare)
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Performance modelling of intelligent transportation systems : Experience report
- 2021
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Ingår i: ICPE '21. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450383318 ; , s. 155-160
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Konferensbidrag (refereegranskat)abstract
- Modern information systems connecting software, physical systems and people, are usually characterized by high dynamism. These dynamics introduce uncertainties, which in turn may harm the quality of systems and lead to incomplete, inaccurate, and unreliable results. To deal with this issue, in this paper we report our incremental experience on the usage of different performance modelling notations while analyzing Intelligent Transportation Systems. More specifically, Queueing Networks and Petri Nets have been adopted and interesting insights are derived.
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| 19. |
- Pagliari, Lorenzo, et al.
(författare)
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To what extent formal methods are applicable for performance analysis of smart cyber-physical systems?
- 2019
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Ingår i: ECSA '19: Proceedings of the 13th European Conference on Software Architecture. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450371421 ; , s. 139-144
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Konferensbidrag (refereegranskat)abstract
- The dynamic nature of complex Cyber-Physical Systems (CPS) introduces new research challenges since they need to smartly deal with changing situations in their environment. This triggers the usage of methodologies that keep track of changes and raise alarms whether extra-functional requirements (e.g., safety, reliability, performance) are violated. In this context, we investigate the usage of formal methods as support to provide a model-based performance evaluation of smart CPS. The main goal is to understand to what extent well-known performance models, specifically Queueing Networks, are suitable to represent these dynamic scenarios.
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