Programming support for time-sensitive adaptation in cyberphysical systems

Cyberphysical systems (CPS) integrate embedded sensors, actuators, and computing elements for controlling physical processes. Due to the intimate interactions with the surrounding environment, CPS software must continuously adapt to changing conditions. Enacting adaptation decisions is often subject to strict time requirements to ensure control stability, while CPS software must operate within the tight resource constraints that characterize CPS platforms. De- velopers are typically left without dedicated programming support to cope with these aspects. This results in either to neglect functional or timing issues that may potentially arise or to invest significant efforts to implement hand-crafted so- lutions. We provide programming constructs that allow de- velopers to simplify the specification of adaptive processing and to rely on well-defined time semantics. Our evaluation shows that using these constructs simplifies implementations while reducing developers’ effort, at the price of a modest memory and processing overhead

Context-oriented programming for adaptive wireless sensor network software

We present programming abstractions for imple- menting adaptive Wireless Sensor Network (WSN) software. The need for adaptability arises in WSNs because of unpredictable environment dynamics, changing requirements, and resource scarcity. However, after about a decade of research in WSN programming, developers are still left with no dedicated support. To address this issue, we bring concepts from Context-Oriented Programming (COP) down to WSN devices. Contexts model the situations that WSN software needs to adapt to. Using COP, programmers use a notion of layered function to implement context-dependent behavioral variations of WSN code. To this end, we provide language-independent design concepts to organize the context-dependent WSN operating modes, decoupling the ab- stractions from their concrete implementation in a programming language. Our own implementation, called CONESC, extends nesC with COP constructs. Based on three representative applica- tions, we show that CONESC greatly simplifies the resulting code and yields increasingly decoupled implementations compared to nesC. For example, by model-checking every function in either implementations, we show a ≈50% reduction in the number of program states that programmers need to deal with, indicating easier debugging. In our tests, this comes at the price of a maximum 2.5% (4.5%) overhead in program (data) memory

The FlyZone Testbed Architecture for Aerial Drone Applications

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.This research was partially supported by the EU commission with H2020 project 5G-DIVE (grant agreement 85988), by the Italian Ministry of Education, University, and Research through the cluster project “ICT Solutions to Support Logistics and Transport Processes (ITS)”, and by the Swedish Innovation Agency through project “DePILOT”, “DePILOT Reloaded”, and “DepDrone”

Software Adaptation in Wireless Sensor Networks

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

Towards Context-Oriented Self-Adaptation in Resource-Constrained Cyberphysical Systems

We present programming abstractions for implementing adaptive Wireless Sensor Network (WSN) software. The need for adaptability arises in WSNs because of unpredictable environment dynamics, changing requirements, and resource scarcity. However, after about a decade of research in WSN programming, developers are still left with no dedicated support. To address this issue, we bring concepts from Context-Oriented Programming (COP) down to WSN devices. Contexts model the situations that WSN software needs to adapt to. Using COP, programmers use a notion of layered function to implement context-dependent behavioral variations of WSN code. To this end, we provide language-independent design concepts to organize the context-dependent WSN operating modes, decoupling the abstractions from their concrete implementation in a programming language. Our own implementation, called CONESC, extends nesC with COP constructs. Based on three representative applications, we show that CONESC greatly simplifies the resulting code and yields increasingly decoupled implementations compared to nesC. For example, by model-checking every function in either implementations, we show a ~50% reduction in the number of program states that programmers need to deal with, indicating easier debugging. In our tests, this comes at the price of a maximum 2.5% (4.5%) overhead in program (data) memory

Mössabauer spectroscopy of 119Sn probe cations on the surfaces of ZnO crystallites : valence state, local environment, and hyperfine interactions of tin additives

A synthesis procedure that allows us to obtain ZnO:0.3 at % 119Sn samples with Sn2+ ions on the surfaces of oxide particles containing structure-forming cations on tetrahedral sites is developed for the first time. Analysis of the 119Sn Mössbauer spectra of obtained samples does not confirm the existence of the localized magnetic moments at ZnO grain boundaries recently suggested in the literature

Mössbauer-spectroscopic characterization of the local surrounding of tin dopant cations in the bulk and on the surface of YCrO₃ crystallites

119Sn Mössbauer spectra of tin-doped YCrO3, obtained by annealing in air of an YCr(119Sn4+)0.003(OH)6·xH2O precursor, provide evidence for the location of Sn4+on the Cr3+site in the bulk of crystallites. Below the Néel point of YCrO3 (TN= 141 K), Sn4+ions are spin-polarized, the majority exhibiting a hyperfine field H of 80 kOe at 4.2 K. Analysis of the119Snspectra of another sample, obtained by impregnation of polycrystalline YCrO3 with a solution of119SnCl4, shows that annealing in H2results in the location of the dopant, in the divalent state, on the surface of the crystallites. The parameters of an in situ119Sn spectrum at 295 K (isomer shiftδ=2.76mms−1and quadrupole splitting EQ=1.95mms−1) reveal the presence of Sn2+ions on sites with a coordination number CN<6. At 100 K these Sn2+ions exhibit no spin polarization. Upon contact with air they are rapidly oxidized to the tetravalent state, as demonstrated by their modified isomer shift valueδ=0.06mms−1. For the large majority of both the residual “parent” Sn2+ions and the “daughter” Sn4+ones no spin polarization is observed down to 4.2 K. This means that surface-located tin dopant cations, regardless of their oxidation state, occupy the Y3+sites with an equal number of Cr3+neighbors having mutually opposite spin orientation

Mössbauer-spectroscopic characterization of the local surrounding of tin dopant cations in the bulk and on the surface of YCrO₃ crystallites

119Sn Mössbauer spectra of tin-doped YCrO3, obtained by annealing in air of an YCr(119Sn4+)0.003(OH)6·xH2O precursor, provide evidence for the location of Sn4+ on the Cr3+ site in the bulk of crystallites. Below the N'eel point of YCrO3 (TN = 141 K), Sn4+ ions are spinpolarized, the majority exhibiting a hyperfine field H of 80 kOe at 4.2 K. Analysis of the 119Sn spectra of another sample, obtained by impregnation of polycrystalline YCrO3 with a solution of 119SnCl4, shows that annealing in H2 results in the location of the dopant, in the divalent state, on the surface of the crystallites. The parameters of an in situ 119Sn spectrum at 295 K..

Interactions of Sn2+ dopant ions located on surface sites of anatase-type TiO2 with adsorbed H2S molecules studied using 119Sn Mössbauer spectroscopic probe

Information provided by 119Sn2+ Mössbauer probe ions, located on surface sites of anatase-type TiO2 microcrystals exposed, at room temperature, to a H2S/H2 mixture, has permitted to conclude that the interaction of H2S molecules with the substrate surface leads to the dissociation of a fraction of the absorbate molecules. This gives rise to the formation of elemental sulfur which oxidizes the neighboring Sn2+ ions, the produced Sn4+ ions being found coordinated only by S2− anions. Subsequent exposure to ambient air is shown to result in the oxidation of S2− ions, yielding both S0 and SO42−-like species, with concomitant stabilization of Sn4+ ions in coordination polyhedra where they are surrounded by only oxygen anions