Cellular space modeling is becoming an increasingly important modeling paradigm for modeling complex systems with spatial-temporal behaviors. The growing demand for cellular space models has directed researchers to use different modeling formalisms, among which Discrete Event System Specification (DEVS) is widely used due to its formal modeling and simulation framework. The increasing complexity of systems to be modeled asks for cellular space models with large number of cells for modeling the systems¡¯ spatial-temporal behavior. Improving simulation performance becomes crucial for simulating large scale cellular space models. In this dissertation, we proposed a framework for improving simulation performance for large scale DEVS-based cellular space models. The framework has a layered structure, which includes modeling, simulation, and network layers corresponding to the DEVS-based modeling and simulation architecture. Based on this framework, we developed methods at each layer to overcome performance issues for simulating large scale cellular space models. Specifically, to increase the runtime and memory efficiency for simulating large number of cells, we applied Dynamic Structure DEVS (DSDEVS) to cellular space modeling and carried out comprehensive performance measurement. DSDEVS improves simulation performance by making the simulation focus only on those active models, and thus be more efficient than when the entire cellular space is loaded. To reduce the number of simulation cycles caused by extensive message passing among cells, we developed a pre-schedule modeling approach that exploits the model behavior for improving simulation performance. At the network layer, we developed a modified time-warp algorithm that supports parallel simulation of DEVS-based cellular space models. The developed methods have been applied to large scale wildfire spread simulations based on the DEVS-FIRE simulation environment and have achieved significant performance results.

Thesis (M.C.S.)--Miami University, Dept. of Computer Science and Systems Analysis, 2009. / Title from first page of PDF document. Includes bibliographical references (p. 72-75).

General purpose graphics processing units (GP-GPU), owing to their enormous thread-level parallelism, can significantly improve the power consumption at the near-threshold (NTC) operating region, while offering close to a super-threshold performance. However, process variation (PV) can drastically reduce the GPU performance at NTC. In this work, choke points—a unique device-level characteristic of PV at NTC—that can exacerbate the warp criticality problem in GPUs have been explored. It is shown that the modern warp schedulers cannot tackle the choke point induced critical warps in an NTC GPU. Additionally, Choke Point Aware Warp Speculator, a circuit-architectural solution is proposed to dynamically predict the critical warps in GPUs, and accelerate them in their respective execution units. The best scheme achieves an average improvement of ∼39% in performance, and ∼31% in energy-efficiency, over one state-of-the-art warp scheduler, across 15 GPGPU applications, while incurring marginal hardware overheads.

No description available.

In this study we looked into an existing textile baby stroller seat and investigated whether there can be any advantage in changing the material to a spacer fabric from perspectives such as functionality, comfort, and sustainability. The subject of 3D knitting, and advanced knitting is being researched more and more because of its versatility in producing and changing parameters of knitted high quality products, but there is a lack of studies done on comfort for children when it comes to knitted spacer fabrics and not many studies have been done on spacer fabrics used for baby seats in strollers or other types of seats for children. A reason for further development and research in the area of 3D knitting is that it could be giving products a better appearance, functionality or potential for more sustainable pro-duction which could lead to better possibilities of producing more attractive advanced textile products. This could in turn make the producer more attractive among customers as well as stand out more amongst competitors on the market. Recently there has been attention on the use of warp knitted spacer fabrics in the application of cushioning to protect against impact. Thermoregulation, compression, air permeability and good energy absorption are some characteristics of spacer fabrics which are being further investigated in this study (Gokarneshan 2015). Another reason for further investigation of spacer fabrics, and their good cushioning properties, in child products is that it was shown in a previous study that children who are transported in carriers for bicycles are exposed to more vibration compared to children who are transported in automotive rides (Rothhamel 2023). A reason for examining the possibilities of replacing polyurethane foam with spacer fabric is that PU foams generally have lower air permeability in com-bination with higher heat resistance which can lead to problems regarding comfort. (Gokarneshan 2015). Testing of different spacer fabric samples was carried out based on air permeability, burst strength, and moisture management. These tests were then evaluated to determine the optimal parameters of a spacer fabric for increased comfort and functionality in an outdoor child product. Other tests that were carried out were specific tests for child products such bite test, finger probe test, and pulling test to examine the safety of each sample. We concluded that the optimal spacer fabric should be constructed of polyester rather than cotton to have as good wicking properties as possible. The fabric should have one side of the spacer fabric that does not consist of mesh so that the requirements from the finger probe test will be fulfilled. The other side of the spacer fabric should be constructed of a mesh structure to ensure good properties of air permeability. The holes should, however, not be too big since this might be less comfortable against the skin. The mesh structure recommended for this purpose is a hexagonal mesh which results in both good permeability of both water and air flow. The fabric should also be constructed with a multifilament for the spacer yarn for safety reasons.

Wood is a major construction material that is used in many contexts, and for different purposes. Serious problems may arise, however, when moisture related deformations as twist occur in wood used in different types of building structures, joinery and furniture. Twist can be explained to a great degree by the helical deviation of the grain angle in relation to the longitudinal direction of the log or the sawn board. Wood fibres form a spiral within the tree, and this is a natural occurrence that is named spiral grain. The wood fibres close to the pith in Norway spruce form a left-handed spiral. In most trees the grain angle turns over to be right-handed with time. Sawn timber that exhibits large grain angles lead to problems of shape stability and stiffness in finished constructions. In this thesis the spiral grain in Norway spruce (Picea abies (L.) Karst.) was stated as well as the effect on sawn timber. The material was based on sample trees from Sweden and Finland. Samples were taken in twenty-two stands at different heights in tree. From six stands studs were sawn and dried for measuring twist and other deformations. The spiral grain was measured with the method scribe test on 390 log discs taken at the top-end of the logs. Account was given concerning changes in grain angle from pith to bark, regarding both increasing annual ring numbers and distance from pith. The development of grain angle over tree age was utilized to study whether annual growth, size of tree, height in tree as well as silvicultural treatments affected spiral grain. Moreover, the relation between grain angle and distance to pith (in mm) was used to forecast twist in sawn timber. The left-handed grain angle was at its greatest between the fourth and eighth annual rings. Thereafter for most trees the grain angle turned from left-handed to right-handed in a linear fashion, in a manner that was unique for each individual tree. The pattern of spiral grain differed significantly between different stands, regarding change of inclination with increasing age or distance from pith. The culmination of the grain angle close to the pith occurred at somewhat higher age higher up in the trunk. The grain angle decreased faster in top logs than it did in the butt logs. The largest trees within a stand had a grain angle that turned to right in a slower way than smaller ones. The thinning strength and type of thinning regime also affected the character of spiral grain in the remaining trees in a stand. There was an indication that strong thinnings, where fast growing trees are retained, may lead to more individuals in a stand that exhibit high grain angles under bark. With knowledge of the size and direction of the grain angle under bark, and the diameter of the log, calculations can be made that show how twisted the sawn timber will be after drying. This can be used for deciding whether an individual log can profitably be sawn and processed further or not. The grain angle under bark can be used to remove trees showing the greatest degree of spiral grain already in the first thinning. Silvicultural methods aiming at even and dense Norway spruce stands, which normally is practised in Scandinavia, will probably result in timber with relatively low risk concerning large grain angle and subsequent risk for twist in sawn wood.

Mit multiaxialen Gelegen auf Basis der Kettenwirktechnik stehen hervorragende textile Halbzeuge für die Weiterverarbeitung als Verstärkungskomponente in Faser-Kunststoff-Verbunden zur Verfügung. Die bisherige Konfiguration der für die Herstellung dieser Textilien verwendeten Nähwirkmaschinen führt verfahrensbedingt zu einem unsymmetrischen Produktaufbau mit üblicherweise nur einer Fadenlage in Gelegelängsrichtung und ebenso zu Einschränkungen bei der Anordnung des Bindefadens im Textil. Durch die Erweiterung des Nähwirkprozesses wird es möglich, Nähwirkstoffe mit einer beliebigen Abfolge der Einzellagen herzustellen, zum Beispiel in symmetrischer Anordnung. Die neuen Varianten der Lagenanordnung und der Bindungskonstruktion bilden den Ausgangspunkt für die Produktentwicklung am Beispiel zweier Anwendungen aus den Bereichen der Faser-Kunststoff-Verbunde und des textilbewehrten Betons. Hier wird deutlich, dass über die Herstellung symmetrischer Gelege hinaus der Einsatz des erweiterten Wirkprozesses die Eigenschaften der Gelege und der Endprodukte vorteilhaft beeinflussen kann. Aus den untersuchten Beispielen und grundsätzlichen Betrachtungen leitet sich ab, unter welchen maschinentechnischen Voraussetzungen der Einsatz des erweiterten Wirkprozesses sinnvoll ist. Es wird ein Konzept entwickelt, auf dessen Grundlage Nähwirkstoffe mit variabler Lagenanordnung auf Nähwirkmaschinen gefertigt werden können. / Multiaxial multi-ply fabrics made by warp knitting are excellently suited for the application in fiber reinforced composites. The usual configuration of the stitch-bonding machines, which are used to produce these fabrics, necessarily leads to composite laminates with an asymmetric layer arrangement and only one layer of yarns in the zero degree direction of the fabric. The variability of patterning with the binding yarn is also limited. By completing the stitch-bonding process with an additional work step it is possible to produce stitch-bonded fabrics without any restrictions concerning the arrangement of the individual layers in the fabric, for example with a symmetric composition. This is the basis for the development of two exemplary products in the fields of textile reinforced plastics and textile reinforced concrete. It can be shown that the application of the extended stitch-bonding process is advantageous beyond the layer arrangement, positively affecting the mechanical properties of the fabric and the composite. From these examples, conclusions are drawn regarding the configuration of future stitch-bonding machines.

Dieser Beitrag bietet einen Überblick über die in zwölf Jahren Forschungsarbeit am Institut für Textilmaschinen und Textile Hochleistungswerkstofftechnik (ITM) erzielten Ergebnisse auf dem Gebiet textiler Betonbewehrungen unter Einsatz der Nähwirktechnik. Standen zunächst die Weiterentwicklung der Nähwirk- bzw. Multiaxial-Kettenwirktechnik und die Integration zusätzlicher Prozessschritte im Mittelpunkt, so wurde dies mit der Einführung neuer Faserwerkstoffe durch die Beantwortung grundlegender Fragen zum Materialverhalten von Glas- und Carbonfasern unter verschiedensten Belastungsszenarien ergänzt. Aufbauend auf den gewonnen Erkenntnissen stehen heute Multiaxialgelege als Bewehrung für Beton zur Verfügung, die ein weites Anforderungsspektrum abdecken können, mit hoher Qualität und Produktivität herstellbar sind und damit den praktischen Einsatz des Textilbetons auf breiter Basis ermöglichen. / This paper provides an overview on the results of textile concrete achieved in twelve years of research at the Institute of Textile Machinery and High Performance Material Technology (ITM) in the field of textile reinforcements for concrete based on the multiaxial stitch-bonding technology. During the early years the research focused on the development of the textile manufacturing process and the integration of additional functions in stitch-bonding machines. With the introduction of new fiber materials this was shifted towards the description of the material behavior of glass and carbon fibers under different load scenarios. Based on the results of this research, multiaxial multi-ply fabrics are available now as reinforcements for concrete, covering a broad range of applications. These fabrics can be produced with high quality and productivity and enable the practical usage of textile reinforced concrete.

Le rendu photo-réaliste traditionnel exige un effort manuel et des calculs intensifs pour créer des scènes et rendre des images réalistes. C'est principalement pour cette raison que la création de contenus pour l’imagerie numérique de haute qualité a été limitée aux experts et le rendu hautement réaliste nécessite encore des temps de calcul significatifs. Le rendu basé image (IBR) est une alternative qui a le potentiel de rendre les applications de création et de rendu de contenus de haute qualité accessibles aux utilisateurs occasionnels, puisqu'ils peuvent générer des images photo-réalistes de haute qualité sans subir les limitations mentionnées ci-dessus. Nous avons identifié trois limitations importantes des méthodes actuelles de rendu basé image : premièrement, chaque algorithme possède des forces et faiblesses différentes, en fonction de la qualité de la reconstruction 3D et du contenu de la scène, et un seul algorithme ne permet souvent pas d’obtenir la meilleure qualité de rendu partout dans l’image. Deuxièmement, ces algorithmes présentent de forts artefacts lors du rendu d’objets manquants ou partiellement reconstruits. Troisièmement, la plupart des méthodes souffrent encore d'artefacts visuels significatifs dans les régions de l’image où la reconstruction est de faible qualité. Dans l'ensemble, cette thèse propose plusieurs améliorations significatives du rendu basé image aussi bien en termes de vitesse de rendu que de qualité d’image. Ces nouvelles solutions sont basées sur le rendu sélectif, la substitution de modèle basé sur l'apprentissage, et la prédiction et la correction des erreurs de profondeur. / Traditional photo-realistic rendering requires intensive manual and computational effort to create scenes and render realistic images. Thus, creation of content for high quality digital imagery has been limited to experts and highly realistic rendering still requires significant computational time. Image-Based Rendering (IBR) is an alternative which has the potential of making high-quality content creation and rendering applications accessible to casual users, since they can generate high quality photo-realistic imagery without the limitations mentioned above. We identified three important shortcomings of current IBR methods: First, each algorithm has different strengths and weaknesses, depending on 3D reconstruction quality and scene content and often no single algorithm offers the best image quality everywhere in the image. Second, such algorithms present strong artifacts when rendering partially reconstructed objects or missing objects. Third, most methods still result in significant visual artifacts in image regions where reconstruction is poor. Overall, this thesis addresses significant shortcomings of IBR for both speed and image quality, offering novel and effective solutions based on selective rendering, learning-based model substitution and depth error prediction and correction.

Pattern speed is an important parameter of the density wave theory for spiral galaxies. In this thesis we have determined the pattern speed for warped galaxies (flat galaxies being a special case of this generalization) using the observable data of the surface brightness and line-of-sight velocity distribution of the galaxy. We have also extracted the transverse velocity field for the warped galaxy using the same data. Here we have simulated the data and applied our method to it and we found that our method works well in warped galaxy. We assume a parameterized model of the warp and by the method of minimizing χ2 error we can determine the parameters of the model also and thus we can construct the warp equation. We have also discussed the implications and the limitations of this method.