Many components of Cyber-Physical Systems (CPS) are designed based on models that represent the assumed behavior of the CPS at the time of deployment. However, significant or continuous small changes in the CPS, as well as wear and tear reduce the effectiveness of the CPS and its model and may lead to a total failure of the overall system. In this paper, we propose a novel lifecycle-based view of CPS models. First, we define the model's lifespan as the period from the initial conception of the model until it is no longer fit to represent the system behavior. For better differentiation, a lifespan is divided into the initial, operation, and adaptation phases. In the initial phase, a known-good baseline performance metric is established for the model's suitability to reflect the system behavior. In the operation phase, the model is used for CPS analysis, data smoothing, and fault location while its suitability is monitored. The adaptation phase is intended for necessary adaptations to the model and to the CPS itself, which lead to new iterations. To implement these lifecycle augmentations of the CPS, we use formal modeling in the form of Hidden Markov Models extended by unobservable transitions (Є-HMMT) to represent the assumed system behavior and compare the data of the observed system behavior with this modeling. In addition, we are testing our proposed formalism by designing a CPS model based on smart home systems and running a simulation for validation. The simulation covers unforeseen system changes and corrupted data.

In this paper, we present a novel approach for identifying various bike types and e-scooters using sensor readings from the cyclist’s smartphone. Bike type identification is necessary to provide context-aware navigation services that consider e-scooter- and bike-specific road conditions in route planning and improve safety and comfort by suggesting roads suitable for the cyclist’s bike type. In addition, the idea of bike type identification is useful for advertising purposes or for improving VPA (Virtual Personal Assistants) capabilities with non-intrusive, bike or e-scooter specific suggestions. We employ a CNN (Convolutional Neural Network) deep learning approach to differentiate between various bike-types and e-scooters. The evaluation includes various roads, cyclists, bike types and smartphones. The results show that bike types are identified with average F1-scores, Accuracy and AUC of up to 0.92, 0.90 and 0.98 respectively.

We present a method for recognizing a video that is playing on a TV screen by sampling the ambient light sensor of a user's smartphone. This improves situation awareness in pervasive systems because the phone can determine what the user is currently watching on TV. Our method works even if the phone has no direct line of sight to the TV screen, since ambient light reflected from walls is sufficient. Our evaluation shows that a 100% recognition ratio of the current TV channel is possible by sampling a sequence of 15 to 120 seconds length, depending on more or less favorable measuring conditions. In addition, we evaluated the recognition ratio when the user is watching video-on-demand, which exhibits a large set of possible videos. Recognizing professional YouTube videos resulted in a 92% recognition ratio; amateur videos were recognized correctly with 60% because these videos have fewer cuts. Our method focuses on detecting the time difference between video cuts because the light emitted by the screen changes instantly with most cuts and this is easily measurable with the ambient light sensor. Using the ambient light sensor instead of the camera greatly benefits energy consumption, bandwidth usage and raises less privacy concerns. Hence, it is feasible to run the measurement in the background for a longer time without draining the battery and without sending camera shots to a remote server for analysis.