This work tries to remedy the practical part of teaching development of software for real-time systems. It does so by creation of a platform on which students can practically learn aspects of development of software for real-time systems. % (feedback control, low level programming). The resulting platform consists of a plant, a visualizer and a controller. The plant represents an industrial machine, the visualizer displays the current state of the plant. The controller drives the plant. Students learn by developing a program for the controller. The resulting platform is realized as a hardware-in-the-loop simulation -- the controller's processor and devices are real hardware, and the plant is a simulated device. The platform has a low cost, low space requirements and it is not easily breakable. Powered by TCPDF (www.tcpdf.org)

This thesis concerns blind source separation techniques using second order statistics and higher order statistics for reverberant environments. A focus of the thesis is algorithmic simplicity with a view to the algorithms being implemented in their online forms. The main challenge of blind source separation applications is to handle reverberant acoustic environments; a further complication is changes in the acoustic environment such as when human speakers physically move. A novel time-domain method which utilises a pair of finite impulse response filters is proposed. The method of principle angles is defined which exploits a singular value decomposition for their design. The pair of filters are implemented within a generalised sidelobe canceller structure, thus the method can be considered as a beamforming method which cancels one source. An adaptive filtering stage is then employed to recover the remaining source, by exploiting the output of the beamforming stage as a noise reference. A common approach to blind source separation is to use methods that use higher order statistics such as independent component analysis. When dealing with realistic convolutive audio and speech mixtures, processing in the frequency domain at each frequency bin is required. As a result this introduces the permutation problem, inherent in independent component analysis, across the frequency bins. Independent vector analysis directly addresses this issue by modeling the dependencies between frequency bins, namely making use of a source vector prior. An alternative source prior for real-time (online) natural gradient independent vector analysis is proposed. A Student's t probability density function is known to be more suited for speech sources, due to its heavier tails, and is incorporated into a real-time version of natural gradient independent vector analysis. The final algorithm is realised as a real-time embedded application on a floating point Texas Instruments digital signal processor platform. Moving sources, along with reverberant environments, cause significant problems in realistic source separation systems as mixing filters become time variant. A method which employs the pair of cancellation filters, is proposed to cancel one source coupled with an online natural gradient independent vector analysis technique to improve average separation performance in the context of step-wise moving sources. This addresses `dips' in performance when sources move. Results show the average convergence time of the performance parameters is improved. Online methods introduced in thesis are tested using impulse responses measured in reverberant environments, demonstrating their robustness and are shown to perform better than established methods in a variety of situations.

Les systèmes temps réel à contraintes temporelles strictes sont caractérisés par des ensembles de tâches pour lesquelles sont connus l'échéance, le modèle d'arrivée (fréquence) et la durée d'exécution pire cas (WCET). Nous nous intéressons à l'ordonnancement de ces systèmes sur plate-forme multiprocesseur. Garantir le respect des échéances pour un algorithme d'ordonnancement est l'une des problématiques majeures de cette thématique. Nous allons plus loin en nous intéressant à la sûreté temporelle, que nous caractérisons par les propriétés (i) de robustesse et (ii) de viabilité. La robustesse consiste à proposer un intervalle sur les augmentations(i-a) de WCET et (i-b) de fréquence tel que les échéances soient respectées. La viabilité consiste cette fois à garantir le respect des échéances lors du relâchement des contraintes (ii-a) de WCET (réduction), (ii-b) de fréquence (réduction) et (ii-c) d'échéance(augmentation). La robustesse revient alors à tolérer l'imprévu, tandis que la viabilité est la garantie que l'algorithme d'ordonnancement n'est pas sujet à des anomalies suite à un relâchement de contraintes. Nous considérons l'ordonnancement en priorités fixes, où chaque occurrence d'une tâche est ordonnancée avec la même priorité. Dans un premier temps, nous étudions la propriété de robustesse dans les approches d'ordonnancement hors-ligne et sans migration (partitionnement). Nous traitons le cas des tâches avec ou sans partage de ressources. Dans un second temps, nous étudions la propriété de viabilité d'une approche d'ordonnancement en ligne avec migrations restreintes et sans partage de ressources / The hard real-time systems are characterized by sets of tasks for which are known the deadline, the arrival model (frequency) and the Worst-Case Execution Time (WCET). We focus on the scheduling of these systems on multiprocessor platforms. One of the main issues of this topic is to ensure that all deadlines are met. We go further by focusing on the temporal safety which we characterized by the properties of (i) robustness and (ii) sustainability. The robustness consists in providing an interval on the increases of (i-a) WCET and (i-b) frequency in such a way that the deadlines are met. The sustainability consists in ensuring that no deadline is missed when the following constraints are relaxed : (ii-a) WCET (decreasing), (ii-b) frequency (decreasing) and (ii-c) deadline (increasing). The robustness amounts to tolerate unexpected behaviors while the sustainability is the guarantee that the scheduling algorithm does not suffer from anomalies because of a relaxation of constraints. We consider fixed-priority scheduling for which any job of a task is scheduled with the same priority. Firstly, we study the property of robustness in off-line scheduling approaches without migration (partitioning). We deal with the case of tasks with or without shared resources. Secondly, we study the property of sustainability of an online restricted-migration scheduling approach without shared resources

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Cryosurgery is the destruction of undesired biological tissues by freezing. Modern cryosurgery is frequently performed as a minimally-invasive procedure, where multiple hypodermic, needle-shaped cryoprobes are inserted into the target area to be treated. The aim of the cryosurgeon is to maximize cryoinjury within a target region, while minimizing damage to healthy surrounding tissues. There is an undisputed need for temperature-field reconstruction during minimally invasive cryosurgery to help the cryosurgeon achieve this aim. The work presented in this thesis is a part of ongoing project at the Biothermal Technology Laboratory (BTTL), to develop hardware and software tools to accomplish real-time temperature field reconstruction. The goal in this project is two-fold: (i) to develop the hardware necessary for miniature, wireless, implantable temperature sensors, and (ii) to develop mathematical techniques for temperature-field reconstruction in real time, which is the focus of the work presented in this thesis. To accomplish this goal, this study proposes a computational approach for real-time temperature-field reconstruction, combining data obtained from various sensing modalities such as medical imaging, cryoprobe-embedded sensors, and miniature, wireless, implantable sensors. In practice, the proposed approach aims at solving the inverse bioheat transfer problem during cryosurgery, where spatially distributed input data is used to reconstruct the temperature field. Three numerical methods have been developed and are evaluated in the scope of this thesis. The first is based on a quasi-steady approximation of the transient temperature field, which has been termed Temperature Field Reconstruction Method (TFRM). The second method is based on analogy between the fields of temperature and electrical potential, and is thus termed Potential Field Analogy Method (PFAM). The third method is essentially a hybrid of TFRM and PFAM, which has shown superior results. Each of these methods has been benchmarked against a full-scale finite elements analysis using the commercial code ANSYS. Benchmarking results display an average mismatch of less than 2 mm in 2D cases and less than 3 mm in 3D cases for the location of the clinically significance isotherms of -22°C and -45°C. In an advanced stage of numerical methods evaluation, they have been validated against experimental data, previously obtained at the BTTL. Those experiments were conducted on a gelatin solution, using proprietary liquid-nitrogen cryoprobes and a cryoheater to simulate urethral warming. The design of the experiment was aimed at creating a 2D heat-transfer problem. Validation results against experimental data suggest an average mismatch of less than 2 mm, for the hybrid of TFRM + PFAM method, which is of the order of uncertainty in estimating the freezing front location based on ultrasound imaging.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Robert L. Larson / Bradley J. White / Applying systems methods to cattle production requires investigators to think about whole systems when addressing study objectives. The research conducted for this dissertation emphasized studying whole systems using different methods. We studied cattle production systems through mathematical simulation and new indirect monitoring technologies. While the methods used for the research in this dissertation may be very different, all utilized systems methods to address the study objectives. Firstly, we applied systems thinking methods and developed a dynamic, deterministic systems simulation of cow-calf production over a 10-year horizon. This model was used to investigate the effects the duration of postpartum anestrus (dPPA) has on reproductive performance. A large range of dPPA have been reported, so various primiparous cow and multiparous cow dPPA were simulated. We found that increasing the dPPA for primiparous and multiparous cows had a negative impact on herd performance and that the dPPA is an important factor in determining cow-calf performance success. We then used the cow-calf simulation to explore the effects of breeding nulliparous cows prior to the rest of the herd, known as providing Heifer Lead Time (tHL). We found that increasing tHL improved herd performance, especially with longer dPPA for primiparous cows. Secondly, real-time location systems (RTLS) were used to indirectly monitor cattle behavior. These systems have been used to determine the amount of time cattle spend at eating and drinking locations. We modeled the probability of cattle participating in eating and drinking behavior when determined to be at these locations by RTLS and found that significant differences exist between individual calves and period of the day. Finally, we explored associations between bovine respiratory disease (BRD) and animal-to-animal contacts as determined by RTLS in beef cattle. We found that the probability of BRD diagnosis was associated with the amount of time 4 days’ ago that a calf was in calf-contact with calves assumed to be shedding BRD pathogens.

Procedural human motion generation is still an open area of research. Most research into procedural human motion focus on two problem areas: the realism of the generated motion and the computation time required to generate the motion. Realism is a problem because humans are very adept at spotting the subtle nuances of human motion and so the computer generated motion tends to look mechanical. Computation time is a problem because the complexity of the motion generation algorithms results in lengthy processing times for greater levels of realism. The balancing human problem poses the question of how to procedurally generate, in real-time, realistic standing poses of an articulated human body. This report presents the balancing human algorithm that addresses both concerns: realism and computation time. Realism was addressed by integrating two existing algorithms. One algorithm addressed the physics of the human motion and the second addressed the prediction of the next pose in the animation sequence. Computation time was addressed by identifying techniques to simplify or constrain the algorithms so that the real-time goal can be met. The research methodology involved three tasks: developing and implementing the balancing human algorithm, devising a real-time simulation graphics engine, and then evaluating the algorithm with the engine. An object-oriented approach was used to model the balancing human as an articulated body consisting of systems of rigid-bodies connected together with joints. The attributes and operations of the object-oriented model were derived from existing published algorithms.

A real-time simulator (RTS) with digital and analog input/output modules is used to conduct hardware-in-the-loop simulations to evaluate performance of power system equipment such as protective relays by exposing the equipment to the simulated realistic operating conditions. This work investigates the use of RTS to test relays with single-pole-switching (SPS) feature. Single-pole switching can cause misoperations due to fault arc during reclosing of the breakers. Through this investigation, a test procedure appropriate for the testing SPS relays has been developed. The test procedure includes power system modeling for real time simulation, relay test setup, and test plan. HYPERSIM real-time simulator was used to model an actual power system. Transmission lines, three-winding transformers, and induction motor were modeled with actual parameters. Models for fault arc in HYPERSIM real time simulator were developed. Test set-up for evaluating relay performance and wiring drawings for connecting relay in closed-loop to the simulator were developed.

Background. Real-time shadows in 3D applications have for decades been implemented with a solution called Shadow Mapping or some variant of it. This is a solution that is easy to implement and has good computational performance, nevertheless it does suffer from some problems and limitations. But there are newer alternatives and one of them is based on a technique called Voxel Cone-Tracing. This can be combined with a technique called Cascading to create Cascaded Voxel Cone-Tracing Shadows (CVCTS). Objectives. To measure the computational performance of CVCTS to get better insight into it and provide data and findings to help developers make an informed decision if this technique is worth exploring. And to identify where the performance problems with the solution lies. Methods. A simple implementation of CVCTS was implemented in OpenGL aimed at simulating a solution that could be used for outdoor scenes in 3D applications. It had several different parameters that could be changed. Then computational performance measurements were made with these different parameters set at different settings. Results. The data was collected and analyzed before drawing conclusions. The results showed several parts of the implementation that could potentially be very slow and why this was the case. Conclusions. The slowest parts of the CVCTS implementation was the Voxelization and Cone-Tracing steps. It might be possible to use the CVCTS solution in the thesis in for example a game if the settings are not too high but that is a stretch. Little time could be spent during the thesis to optimize the solution and thus it’s possible that its performance could be increased.

The purpose of this thesis was to investigate how potentials of Real-Time Location Systems (RTLS) in relation to Just In Time (JIT) management could be utilized within logistics management. For this, a framework, based on previous research of the interrelations of RTLS and JIT management, is proposed, to assess the effects of RTLS on logistics management, both on a managerial - as well as on an operational level. To answer the proposed research questions, the study followed a deductive and exploratory case study design, which was conducted at a company within the automotive industry. To understand the challenges within logistics management at the case company, interviews, observations, analysis of internal documents and a focus group were used, which allowed for a triangulation of the captured information. The findings and analysis of the data show that on an operational level the challenges within logistics management are related to complex logistic structures, pull strategies with partial push material flows, lack of information and – reliable data, as well as processes reliant on individuals. On the managerial level the findings suggest challenges related to high complexity and space constraints, time constraints, lack of transparency and – data connections, the company's improvement focus, employee attitude and a lack of reliable data. When the challenges were evaluated in relation to the proposed framework, it shows that these challenges would be resolved or counteracted by the benefits RTLS could provide in relation to JIT management. This study thereby supports the positive correlation between RTLS’s potential and JIT in logistics management.