The purpose of this thesis is to create an indoor rescue scenario with multiple self-localizing robots that are able to collaborate for a victim search. Victims are represented by RFID tags and detecting them combined with an accurate enough location data is considered as a successful finding. This setup is created for use in a laboratory assignment at Linköping University. We consider the indoor localization problem by trying to use as few sensors as possible and implement three indoor localization methods - odometry based, passive RFID based, and our approach by fusing both sensor data with particle filter.The Results show that particle filter based localization performs the best in comparison to the two other implemented methods and satisfies the accuracy requirements stated for the scenario. The victim search problem is solved by an ant mobility (pheromone-based) approach which integrates our localization method and provides a collaborative navigation through the rescue area. The purpose of the pheromone mobility approach is to achieve a high coverage with an acceptable resource consumption.Experiments show that area is covered with approximately 30-40% overhead in traveled distance comparing to an optimal path.

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This thesis investigates modeling and simulation of hybrid electric vehicles with particular emphasis on transient modeling and real-time simulation. Three different computer models, i.e. a steady state model, a fully-detailed transient model and a reduced-intensity transient model, are developed for a hybrid drive-train in this study. The steady-state model, which has low computational intensity, is used to determine the optimal battery size and chemistry for a plug-in hybrid drive-train. Simulation results using the developed steady state model show the merits of NiMH and Li-ion battery technologies. Based on the obtained results and the reducing cost of Li-ion batteries, this battery chemistry is used throughout this research. A fully-detailed transient model is developed to simulate the vehicle behaviour under different driving conditions. This model includes the dynamics of the power train components such as the engine, the power-electronic converters and vehicle controllers of all levels. The developed transient model produces an accurate representation of the drive-train including the switching behaviour of the power electronic converters. A reduced-intensity transient model (also referred to as a dynamic average model) is developed for real-time hardware-in-loop simulation of the vehicle. By reducing the computational demand of the detailed transient model using averaging techniques, the reduced-intensity model is implemented on a real-time simulator and is interfaced to an external subsystem such as an actual battery. The setup can be used to test existing and emerging battery technologies, which may not have an accurate mathematical model. Extensive tests are performed to verify the accuracy and validity of the results obtained from the developed hardware-in-loop simulation setup.

Shade tree incorporation is beneficial in coffee cropping systems under sub-optimal conditions. This study was performed in lowland Costa Rica, at a 12-year-old experimental coffee farm. The main objective was to compare the effect of a nitrogen fixing shade tree, Erythrina poeppigiana, on nutrient availability in the rhizosphere of coffee under conventional fertilization. Accumulation of nutrients (mineral N, available P, and exchangeable base cations) in rhizosphere relative to bulk soil was greater under shade than full sun. Low nitrate availability in rhizosphere soil of full sun coffee was explained by root-induced acidification relative to bulk soil, as abundance of ammonia-oxidizing bacteria (AOB), which mediate nitrification, were positively correlated with pH. Organic fertilization enhanced AOB abundance and altered soil bacterial community structure relative to conventional fertilization. This study indicates clear effects of shade-tree presence on nutrient availability at the micro-scale, management of which is critical for stability of coffee agroforestry systems.

Shade tree incorporation is beneficial in coffee cropping systems under sub-optimal conditions. This study was performed in lowland Costa Rica, at a 12-year-old experimental coffee farm. The main objective was to compare the effect of a nitrogen fixing shade tree, Erythrina poeppigiana, on nutrient availability in the rhizosphere of coffee under conventional fertilization. Accumulation of nutrients (mineral N, available P, and exchangeable base cations) in rhizosphere relative to bulk soil was greater under shade than full sun. Low nitrate availability in rhizosphere soil of full sun coffee was explained by root-induced acidification relative to bulk soil, as abundance of ammonia-oxidizing bacteria (AOB), which mediate nitrification, were positively correlated with pH. Organic fertilization enhanced AOB abundance and altered soil bacterial community structure relative to conventional fertilization. This study indicates clear effects of shade-tree presence on nutrient availability at the micro-scale, management of which is critical for stability of coffee agroforestry systems.

People make mistakes. Software engineers are no exception to this fact. When software engineers make mistakes, these manifest in the form of buggy software - a major problem in today's industry. The existence of bugs is commonly detected using testing, the process of executing the software and checking if its behaviour complies with the specification. As limitations in time make testing of the entire software behaviour impracticable, testers need to make informed decisions on how to test the software to detect as many bugs as possible. In the realm of real-time systems (RTSs), software testing is made more difficult by non-deterministic factors such as interaction with the surrounding environment, (pseudo)parallelism, and timing requirements. Furthermore, RTS testing suffers from behaviour-altering perturbation from the instrumentation inserted in the system to keep track of test progress (i.e., probe effects). In our work, we analyse the main test criteria used for traditional software testing in order to see which of these scale to, and assist in, system-level testing of multi-tasking RTSs. We focus on one of these criteria, the all definition-use paths coverage criterion, as it highlights a central aspect of non-deterministic task interaction, and investigate what is specifically required for applying this criterion to testing of multi-tasking RTSs. Further, we examine the possibility of using execution replay for probe effect-free test monitoring. We evaluate this approach in real industrial settings by means of case studies. The contributions of this thesis are twofold: First, the use of structural test criteria in RTS system-level testing is facilitated by two different analysis methods. Second, the probe effect is handled by recording non-deterministic events during run-time, and by using this recording to create a monitorable deterministic replica of the first execution. By these contributions, this thesis shows how the non-determinism of multi-tasking RTSs can be handled during system-level testing.

In this thesis we propose a technique to preserve the temporal properties of realtime components during their integration and reuse. We propose a new concept of runnable virtual node which is a coarse-grained real-time component that provides functional and temporal isolation with respect to its environment. A virtual node’s interaction with the environment is bounded by both a functional and a temporal interface, and the validity of its internal temporal behaviour is preserved when integrated with other components or when reused in a new environment.   The first major contribution of this thesis is the implementation of a Hierarchical Scheduling Framework (HSF) on an open source real-time operating system (FreeRTOS) with the emphasis of doing minimal changes to the underlying FreeRTOS kernel and keeping its API intact to support the temporal isolation between a numbers of applications, on a single processor. Temporal isolation between the components during runtime prevents failure propagation between different components.   The second contribution of the thesis is with respect to the integration of components, where we first illustrate how the concept of the runnable virtual node can be integrated in several component technologies and, secondly, we perform a proof-of-concept case study for the ProCom component technology where we demonstrate the runnable virtual node’s real-time properties for temporal isolations and reusability.   We have performed experimental evaluations on EVK1100 AVR based 32-bit micro-controller and have checked the system behaviour during heavy-load and over-load situations by visualizing execution traces in both hierarchical scheduling and virtual node contexts. The results for the case study demonstrate temporal error containment within a runnable virtual node as well as reuse of the node in a new environment without altering its temporal behaviour. / PROGRESS