| 1. |
- Stefanizzi, Maria Laura, et al.
(författare)
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COIN : Opening the internet of things to people's mobile devices
- 2017
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Ingår i: IEEE Communications Magazine. - : Institute of Electrical and Electronics Engineers Inc.. - 0163-6804 .- 1558-1896. ; 55:2, s. 20-26
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Tidskriftsartikel (refereegranskat)abstract
- People's interaction with IoT devices such as proximity beacons, body-worn sensors, and controllable light bulbs is often mediated through personal mobile devices. Current approaches usually make applications operate in separate silos, as the functionality of IoT devices is fixed by vendors and typically accessed only through low-level proprietary APIs. This limits the flexibility in designing applications and requires intense wireless interactions, which may impact energy consumption. COIN is a system architecture that breaks this separation by allowing developers to flexibly run a slice of a mobile app's logic onto IoT devices. Mobile apps can dynamically deploy arbitrary tasks implemented as loosely coupled components. The underlying runtime support takes care of the coordination across tasks and of their real-time scheduling. Our prototype indicates that COIN both enables increased flexibility and improves energy efficiency at the IoT device, compared to traditional architectures.
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| 2. |
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| 3. |
- Afanasov, Mikhail, et al.
(författare)
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Battery-less zero-maintenance embedded sensing at the mithræum of circus maximus
- 2020
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Ingår i: SenSys 2020 - Proceedings of the 2020 18th ACM Conference on Embedded Networked Sensor Systems. - New York, NY, USA : Association for Computing Machinery, Inc. - 9781450375900 ; , s. 368-381
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Konferensbidrag (refereegranskat)abstract
- We present the design and evaluation of a 3.5-year embedded sensing deployment at the Mithræum of Circus Maximus, a UNESCO-protected underground archaeological site in Rome (Italy). Unique to our work is the use of energy harvesting through thermal and kinetic energy sources. The extreme scarcity and erratic availability of energy, however, pose great challenges in system software, embedded hardware, and energy management. We tackle them by testing, for the first time in a multi-year deployment, existing solutions in intermittent computing, low-power hardware, and energy harvesting. Through three major design iterations, we find that these solutions operate as isolated silos and lack integration into a complete system, performing suboptimally. In contrast, we demonstrate the efficient performance of a hardware/software co-design featuring accurate energy management and capturing the coupling between energy sources and sensed quantities. Installing a battery-operated system alongside also allows us to perform a comparative study of energy harvesting in a demanding setting. Albeit the latter reduces energy availability and thus lowers the data yield to about 22% of that provided by batteries, our system provides a comparable level of insight into environmental conditions and structural health of the site. Further, unlike existing energy-harvesting deployments that are limited to a few months of operation in the best cases, our system runs with zero maintenance since almost 2 years, including 3 months of site inaccessibility due to a COVID19 lockdown
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| 4. |
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| 5. |
- Afanasov, M., et al.
(författare)
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Flyzone : A testbed for experimenting with aerial drone applications
- 2019
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Ingår i: MobiSys 2019 - Proceedings of the 17th Annual International Conference on Mobile Systems, Applications, and Services. - New York, NY, USA : Association for Computing Machinery, Inc. - 9781450366618 ; , s. 67-78
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Konferensbidrag (refereegranskat)abstract
- FlyZone is a testbed architecture to experiment with aerial drone applications. Unlike most existing drone testbeds that focus on low-level mechanical control, FlyZone offers a high-level API and features geared towards experimenting with application-level functionality. These include the emulation of environment influences, such as wind, and the automatic monitoring of developer-provided safety constraints, for example, to mimic obstacles. We conceive novel solutions to achieve this functionality, including a hardware/software architecture that maximizes decoupling from the main application and a custom visual localization technique expressly designed for testbed operation. We deploy two instances of FlyZone and study performance and effectiveness. We demonstrate that we realistically emulate the environment influence with a positioning error bound by the size of the smallest drone we test, that our localization technique provides a root mean square error of 9.2cm, and that detection of violations to safety constraints happens with a 50ms worst-case latency. We also report on how FlyZone supported developing three real-world drone applications, and discuss a user study demonstrating the benefits of FlyZone compared to drone simulators.
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| 6. |
- Afanasov, Mikhail, et al.
(författare)
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Programming Support for Time-sensitive Adaptation in Cyberphysical Systems
- 2018
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Ingår i: ACM SIGBED Review. - : Association for Computing Machinery (ACM). - 1551-3688. ; 14:4, s. 27-32
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Tidskriftsartikel (refereegranskat)abstract
- Cyberphysical systems (CPS) integrate embedded sensors,actuators, and computing elements for controlling physicalprocesses. Due to the intimate interactions with thesurrounding environment, CPS software must continuouslyadapt to changing conditions. Enacting adaptation decisionsis often subject to strict time requirements to ensure controlstability, while CPS software must operate within the tightresource constraints that characterize CPS platforms. Developersare typically left without dedicated programmingsupport to cope with these aspects. This results in either toneglect functional or timing issues that may potentially ariseor to invest significant efforts to implement hand-crafted solutions.We provide programming constructs that allow developersto simplify the specification of adaptive processingand to rely on well-defined time semantics. Our evaluationshows that using these constructs simplifies implementationswhile reducing developers’ effort, at the price of a modestmemory and processing overhead.
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| 7. |
- Afanasov, Mikhail, et al.
(författare)
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Software Adaptation in Wireless Sensor Networks
- 2018
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Ingår i: ACM Transactions on Autonomous and Adaptive Systems. - : Association for Computing Machinery (ACM). - 1556-4665 .- 1556-4703. ; 12:4
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Tidskriftsartikel (refereegranskat)abstract
- We present design concepts, programming constructs, and automatic verification techniques to support the development of adaptive Wireless Sensor Network (WSN) software. WSNs operate at the interface between the physical world and the computing machine and are hence exposed to unpredictable environment dynamics. WSN software must adapt to these dynamics to maintain dependable and efficient operation. However, developers are left without proper support to develop adaptive functionality in WSN software. Our work fills this gap with three key contributions: (i) design concepts help developers organize the necessary adaptive functionality and understand their relations, (ii) dedicated programming constructs simplify the implementations, (iii) custom verification techniques allow developers to check the correctness of their design before deployment. We implement dedicated tool support to tie the three contributions, facilitating their practical application. Our evaluation considers representative WSN applications to analyze code metrics, synthetic simulations, and cycle-accurate emulation of popular WSN platforms. The results indicate that our work is effective in simplifying the development of adaptive WSN software; for example, implementations are provably easier to test and to maintain, the run-time overhead of our dedicated programming constructs is negligible, and our verification techniques return results in a matter of seconds.
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| 8. |
- Afanasov, Mikhail, et al.
(författare)
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The FlyZone Testbed Architecture for Aerial Drone Applications
- 2020
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Ingår i: GetMobile. - : Association for Computing Machinery (ACM). - 2375-0529 .- 2375-0537. ; 24:1
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Tidskriftsartikel (refereegranskat)abstract
- Aerial drones represent a new breed of mobile computing. Compared to mobile phones and connected cars that only opportunistically sense or communicate, aerial drones offer direct control over their movements. They can thus implement functionality that were previously beyond reach, such as collecting high-resolution imagery, exploring near-inaccessible areas, or inspecting remote areas to gather fine-grain environmental data.
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| 9. |
- Ahmed, Saad, et al.
(författare)
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Demystifying Energy Consumption Dynamics in Transiently Powered Computers
- 2020
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Ingår i: ACM Transactions on Embedded Computing Systems. - : Association for Computing Machinery. - 1539-9087 .- 1558-3465. ; 19:6
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Tidskriftsartikel (refereegranskat)abstract
- Transiently powered computers (TPCs) form the foundation of the battery-less Internet of Things, using energy harvesting and small capacitors to power their operation. This kind of power supply is characterized by extreme variations in supply voltage, as capacitors charge when harvesting energy and discharge when computing. We experimentally find that these variations cause marked fluctuations in clock speed and power consumption. Such a deceptively minor observation is overlooked in existing literature. Systems are thus designed and parameterized in overly conservative ways, missing on a number of optimizations.We rather demonstrate that it is possible to accurately model and concretely capitalize on these fluctuations. We derive an energy model as a function of supply voltage and prove its use in two settings. First, we develop EPIC, a compile-time energy analysis tool. We use it to substitute for the constant power assumption in existing analysis techniques, giving programmers accurate information on worst-case energy consumption of programs. When using EPIC with existing TPC system support, run-time energy efficiency drastically improves, eventually leading up to a 350% speedup in the time to complete a fixed workload. Further, when using EPIC with existing debugging tools, it avoids unnecessary program changes that hurt energy efficiency. Next, we extend the MSPsim emulator and explore its use in parameterizing a different TPC system support. The improvements in energy efficiency yield up to more than 1000% time speedup to complete a fixed workload.
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| 10. |
- Ahmed, Saad, et al.
(författare)
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Efficient intermittent computing with differential checkpointing
- 2019
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Ingår i: Proceedings of the ACM SIGPLAN Conference on Languages, Compilers, and Tools for Embedded Systems (LCTES). - New York, NY, USA : Association for Computing Machinery. - 9781450367240 ; , s. 70-81
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Konferensbidrag (refereegranskat)abstract
- Embedded devices running on ambient energy perform computations intermittently, depending upon energy availability. System support ensures forward progress of programs through state checkpointing in non-volatile memory. Checkpointing is, however, expensive in energy and adds to execution times. To reduce this overhead, we present DICE, a system design that efficiently achieves differential checkpointing in intermittent computing. Distinctive traits of DICE are its software-only nature and its ability to only operate in volatile main memory to determine differentials. DICE works with arbitrary programs using automatic code instrumentation, thus requiring no programmer intervention, and can be integrated with both reactive (Hibernus) or proactive (MementOS, HarvOS) checkpointing systems. By reducing the cost of checkpoints, performance markedly improves. For example, using DICE, Hibernus requires one order of magnitude shorter time to complete a fixed workload in real-world settings.
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