Since grass is abundant on our planet it plays an important role in the rendering of many different outdoor scenes. This study focuses on the real-time rendering of many individual grass blades with geometry. As a grass blade in real life is very thin and have a simple shape it can be represented with only a handful of vertices. The challenge is introduced when a meadow of grass is to be rendered as it can contain billions of grass blades. Two different algorithms were developed; one which use traditional vertex buffers to store and render the grass blades while the other makes use of textures. Quantitative data was generated from these algorithms. Among this data were images of the scene. These images were subjected to a questionnaire to collect qualitative information about the grass. All the generated data was then analyzed and interpreted to find advantages and disadvantages of the algorithms. The buffer-based algorithm was found to be slightly more computationally efficient compared to the texture-based algorithm. The quality of the visual result was perceived to be towards good while the realism was perceived as mediocre at best. The advantage of the texture-based algorithm is that it allows more options to handle the grass blades data when rendering. Using the terrain data to generate the grass blades was concluded to be advantageous. The realism of the grass could have been improved by using a grass blade texture as well as introducing variety in density and grass species. / Eftersom gräs är rikligt på vår planet spelar den en viktig roll vid renderingen av många olika utomhusscener. Denna studie fokuserar på realtidsrendering av många individuella gräsblad med geometri. Eftersom ett gräsblad i verkligheten är mycket tunnt och har en enkel form kan den representeras med endast en handfull vertiser. Utmaningen introduceras när en äng av gräs ska renderas eftersom som den kan innehålla miljarder gräsblad. Två olika algoritmer utvecklades, en som använder traditionella vertex buffrar för att lagra och rendera gräsbladen medan den andra använder sig av texturer. Kvantitativ data genererades från dessa algoritmer. Bland denna data fanns bilder av scenen. Dessa bilder utsattes för ett frågeformulär för att samla in kvalitativ information om gräset. All den data som genereras analyserades och tolkades för att hitta fördelar och nackdelar med algoritmerna. Den bufferbaserade algoritmen upptäcktes vara beräkningsmässigt effektivare jämfört med den texturbaserade algoritmen. Den upplevda kvalitén på det visuella resultatet ansågs vara närmare bra medan realismen uppfattades som medioker i bästa fall. Fördelen med den texturen-baserad algoritm är att den tillåter fler möjligheter att hantera gräsblads-data vid rendering. Slutsatsen av att använda terrängens data för att generera gräsbladen sågs vara fördelaktigt. Realismen av gräset kunde förbättrats genom att använda en gräsblads-textur, samt variation i densitet och gräsarter.

An event monitor is a part of a real-time system that can be used to check if the system follows the specifications posed on its behavior. This dissertation covers an approach to event monitoring where such specifications (represented by time constraints) are represented by graphs. Not much work has previously been done on designing and implementing constraint graph-based event monitors. In this work, we focus on presenting an extensible design for such an event monitor. We also evaluate different data structure types (linked lists, dynamic arrays, and static arrays) that can be used for representing the constraint graphs internally. This is done by creating an event monitor implementation, and conducting a number of benchmarks where the time used by the monitor is measured. The result is presented in the form of a design specification and a summary of the benchmark results. Dynamic arrays are found to be the generally most efficient, but advantages and disadvantages of all the data structure types are discussed.

In this work an investigation is performed in whether the algorithms Simultaneous Perturbation Stochastic Approximation (SPSA) and Virtual Force Algorithm (VFA) are suitable for real-time strategic placement of sensors in a dynamic environment. An evaluation of these algorithms is conducted and compared to Simulated Annealing (SA), which has been used before in similar applications. For the tests, a computer based model of the sensors and the environment in which they are used, is implemented. The model handles sensors, moving objects, specifications for the area the sensors are supposed to monitor, and all interaction between components within the model. It was the belief of the authors that SPSA and VFA are suited for this kind of problem, and that they have advantages over SA in complex scenarios. The results shows this to be true although SA seems to perform better when it comes to smaller number of sensors to be placed

Future parallel computer systems for embedded real-time applications,where each node in itself can be a parallel computer, are predicted to havevery high bandwidth demands on the interconnection network. Otherimportant properties are time-deterministic latency and guarantees to meetdeadlines. In this thesis, a fiber-optic passive optical star network with amedium access protocol for packet switched communication in distributedreal-time systems is proposed. By using WDM (Wavelength DivisionMultiplexing), multiple channels, each with a capacity of several Gb/s, areobtained. A number of protocols for WDM star networks have recently been proposed.However, the area of real-time protocols for these networks is quiteunexplored. The protocol proposed in this thesis is based on TDMA (TimeDivision Multiple Access) and uses a new distributed slot-allocationalgorithm with real-time properties. Services for both guarantee-seekingmessages and best-effort messages are supported for single destination,multicast, and broadcast transmission. Slot reserving can be used toincrease the time-deterministic bandwidth, while still having an efficientbandwidth utilization due to a simple slot release method. By connecting several clusters of the proposed WDM star network by abackbone star, thus forming a star-of-stars network, we get a modular andscalable high-bandwidth network. The deterministic properties of thenetwork are theoretically analyzed for both intra-cluster and inter-clustercommunication, and computer simulations of intra-cluster communicationare reported. Also, an overview of high-performance fiber-opticcommunication systems is presented.

The mixed-criticality toolbox promises system architects a powerful framework for consolidating real-time tasks with different safety properties on a single computing platform. Thanks to the research efforts in the mixed-criticality field, guarantees provided to the highest criticality level are well understood. However, lower-criticality job execution depends on the condition that all high-criticality jobs complete within their more optimistic low-criticality execution time bounds. Otherwise, no guarantees are made. In this paper, we add to the mixed-criticality toolbox by providing a probabilistic analysis method for low-criticality tasks. While deterministic models reduce task behavior to constant numbers, probabilistic analysis captures varying runtime behavior. We introduce a novel algorithmic approach for probabilistic timing analysis, which we call symbolic scheduling. For restricted task sets, we also present an analytical solution. We use this method to calculate per-job success probabilities for low-criticality tasks, in order to quantify, how low-criticality tasks behave in case of high-criticality jobs overrunning their optimistic low-criticality reservation.

During recent years, the importance of utilizing more computational power in smaller computersystems has increased. The utilization of more computational power in smaller packages, the abil-ity to combine more than one type of processor unit has become more popular in the industry. By combining, one achieves more power efficiency as well as gain more computational power insmaller area. However, heterogeneous programming has proved to be difficult, and that makes soft-ware developers diverge from learning heterogeneous programming languages. This has motivatedHSA foundation to develop a new hardware architecture, called Heterogeneous System Architecture(HSA). This architecture brings features that make the process of heterogeneous programming de-velopment more accessible, efficient, and easier to the software developers. The purpose of thisthesis is to investigate this new architecture, to learn and observe the timing characteristics of atask running a parallel region (a kernel) on a GPU in an HSA compliant system. With an objectiveto gain more knowledge, four test cases have been developed to collect time data and to analyzethe time of the code executed on the GPU. These are: comparison between CPU and GPU, tim-ing predictability of parallel periodic tasks, schedulability in HSA, and memory copy. Based onthe results of the analysis, it has been concluded that the HSA has potential to be very attractivefor developing heterogeneous programs due to its more streamlined infrastructure. It is easier toadapt, requires less knowledge regarding the underlying hardware, and the software developers canuse their preferred programming languages, instead of learning new programming framework, suchas OpenCL. However, since the architecture is new, there are bugs and HSA features that are yetto be incorporated into the drivers. Performance wise, HSA is faster compared to legacy methods,but lacks in providing consistent time predictability, which is important for real-time systems.

Botrytis species affect over 300 host plants in all climate areas of the world, at both pre and post-harvest stages, leading to significant losses in agricultural produce. Therefore, the development of a rapid, sensitive and reliable method to assess the pathogen load of infected crops can help to prescribe an effective curing regime. Growers would then have the ability to predict and manage the full storage potential of their crops and thus provide an effective disease control and reduce post-harvest losses. A highly sensitive electrochemical immunosensor based on a screen-printed gold electrode (SPGE) with onboard carbon counter and silver / silver chloride (Ag/AgCl) pseudo-reference electrode was developed in this work for the detection and quantification of Botrytis species. The sensor utilised a direct sandwich enzyme-linked immunosorbent assay (ELISA) format with a monoclonal antibody against Botrytis immobilised on the gold working electrode. Two immobilisation strategies were investigated for the capture antibody, and these included adsorption and covalent immobilisation after self-assembled monolayer formation with 3-dithiodipropionic acid (DTDPA). A polyclonal antibody conjugated to the electroactive enzyme horseradish peroxidase (HRP) was then applied for signal generation. Electrochemical measurements were conducted using 3,3’, 5,5’-tetramethylbenzidine dihydrochloride / hydrogen peroxide (TMB/H2O2) as the enzyme substrate system at a potential of -200 mV. The developed biosensor was capable of detecting latent Botrytis infections 24 h post inoculation with a linear range from 150 to 0.05 μg fungal mycelium ml-1 and a limit of detection (LOD) as low as 16 ng ml-1 for covalent immobilisation and 58 ng ml-1 for adsorption, respectively. Benchmarked against the commercially available Botrytis ELISA kits, the optimised immuno-electrochemical biosensor showed strong correlation of the quantified samples (R2=0.998) ... [cont.].

We describe quality and performance enhancements, which work in real-time, to all well-known Non-photorealistic (NPR) rendering styles for use in an interactive context. These include Comic rendering, Sketch rendering, Hatching and Painterly rendering, but we also attempt and justify a widening of the established definition of what is considered NPR. In the individual Chapters, we identify typical stylistic elements of the different NPR styles. We list problems that need to be solved in order to implement the various renderers. Standard solutions available in the literature are introduced and in all cases extended and optimised. In particular, we extend the lighting model of the comic renderer to include a specular component and introduce multiple inter-related but independent geometric approximations which greatly improve rendering performance. We implement two completely different solutions to random perturbation sketching, solve temporal coherence issues for coal sketching and find an unexpected use for 3D textures to implement hatch-shading. Textured brushes of painterly rendering are extended by properties such as stroke-direction and texture, motion, paint capacity, opacity and emission, making them more flexible and versatile. Brushes are also provided with a minimal amount of intelligence, so that they can help in maximising screen coverage of brushes. We furthermore devise a completely new NPR style, which we call super-realistic and show how sample images can be tweened in real-time to produce an image-based six degree-of-freedom renderer performing at roughly 450 frames per second. Performance values for our other renderers all lie between 10 and over 400 frames per second on homePC hardware, justifying our real-time claim. A large number of sample screen-shots, illustrations and animations demonstrate the visual fidelity of our rendered images. In essence, we successfully achieve our attempted goals of increasing the creative, expressive and communicative potential of individual NPR styles, increasing performance of most of them, adding original and interesting visual qualities, and exploring new techniques or existing ones in novel ways. / KMBT_363 / Adobe Acrobat 9.54 Paper Capture Plug-in

Device-free locators allow the user to interact with a system without the burden of being physically in contact with some input device or without being connected to the system with cables. This thesis presents a device-free locator that uses computer vision techniques to recognize and track the user's hand. The system described herein uses a video camera to capture live video images of the user, which are segmented and processed to extract features that can be used to locate the user's hand within the image. Two types of features, namely moment based invariants and Fourier descriptors, are compared experimentally. An important property of both these techniques is that they allow the recognition of hand-shapes regardless of affine transformation, e.g. rotation within the plane or scale changes. A neural network is used to classify the extracted features as belonging to one of several hand signals, which can be used in the locator system as 'button clicks' or mode indicators. The Siltrack system described herein illustrates that the above techniques can be implemented in real-time on standard hardware. / Dissertation (MSc (Computer Science))--University of Pretoria, 2007. / Computer Science / unrestricted

Our goal is to develop a flexible, customizable, and practical multi-core testbed based on an Intel desktop computer that can be utilized to assist the theoretical research on power/thermal aware resource management in design of computer systems. By integrating different modules, i.e. thread mapping/scheduling, processor/core frequency and voltage variation, temperature/power measurement, and run-time performance collection, into a systematic and unified framework, our testbed can bridge the gap between the theoretical study and practical implementation. The effectiveness for our system was validated using appropriately selected benchmarks. The importance of this research is that it complements the current theoretical research by validating the theoretical results in practical scenarios, which are closer to that in the real world. In addition, by studying the discrepancies of results of theoretical study and their applications in real world, the research also aids in identifying new research problems and directions.