Artistic vision: painterly rendering using computer vision techniques

Journal ArticleWe present a method that takes a raster image as input and produces a painting-like image composed of strokes rather than pixels. Unlike previous automatic painting methods, we attempt to keep the number of brush-stroke small. This is accomplished by first segmenting the image into features, finding the medial axes points of these features, converting the medial axes points into ordered lists of image tokens, and finally rendering these lists as brush strokes. Our process creates images reminiscent of modern realist painters who often want an abstract or sketchy quality in their work

Hierarchical Image Segmentation using The Watershed Algorithim with A Streaming Implementation

We have implemented a graphical user interface (GUI) based semi-automatic hierarchical segmentation scheme, which works in three stages. In the first stage, we process the original image by filtering and threshold the gradient to reduce the level of noise. In the second stage, we compute the watershed segmentation of the image using the rainfalling simulation approach. In the third stage, we apply two region merging schemes, namely implicit region merging and seeded region merging, to the result of the watershed algorithm. Both the region merging schemes are based on the watershed depth of regions and serve to reduce the over segmentation produced by the watershed algorithm. Implicit region merging automatically produces a hierarchy of regions. In seeded region merging, a selected seed region can be grown from the watershed result, producing a hierarchy. A meaningful segmentation can be simply chosen from the hierarchy produced. We have also proposed and tested a streaming algorithm based on the watershed algorithm, which computes the segmentation of an image without iterative processing of adjacent blocks. We have proved that the streaming algorithm produces the same result as the serial watershed algorithm. We have also discussed the extensibility of the streaming algorithm to efficient parallel implementations

Numerical Calculation of Transport Properties of Rock with Geometry Obtained Using Synchrotron X-ray Computed Microtomography

Macroscopic properties of rocks are functions of pore-scale geometry and can be determined from laboratory experiments using rock samples. Macroscopic properties can also be determined from computer simulations using 3D pore geometries derived from various imaging techniques. Using 3D imagery and computer simulations, we can calculate the porosity, permeability, formation resistivity factor and cementation exponent in reservoir drill cores. The objective of this thesis was to develop a workflow using Synchrotron X-ray Computed Microtomography (CMT) images and commercially available software in order to determine the macroscopic properties in reservoir drill cores for Midale Marly (M0) and Vuggy Shoal (V6) rocks. The workflow started by using CMT data that provided three-dimensional images of the reservoir rocks taken from drill cores in the Weyburn oil field. The resulting CMT grey scale images were used to isolate the pore space in the rock image. A three-dimensional mesh, representing the pore space, was then used to obtain the solution of the Navier-Stokes equations for an incompressible fluid and Laplace's equation for electrical current flow. Solutions of the Navier-Stokes equations were computed with different inlet pressures for the same pore geometry in order to confirm a direct proportionality between the mass fluid flux and pressure gradient as Darcy’s Law specifies. Previously measured laboratory transport properties were compared with my calculated transport properties on a smaller sub-volume of the same rock core imaged using 0.78 µm resolution CMT images. For the Midale Marly rock, the calculated permeability ranged from 0.01 to 3.53 mD. The formation resistivity factor ranged from 29.3 to 309.43 and the cementation exponent ranged from 1.99 to 2.10. The sample was verified to be nearly isotropic as the permeability was similar for three orthogonal fluid flow directions. Even though the sub-volume analyzed was smaller than a Representative Elementary Volume (REV), the results are within an order of magnitude of the previously calculated laboratory results as completed by Glemser (2007) and fall on the same power law trend. A Vuggy (V6) sample was investigated after the sample had been exposed to CO2, and dissolution within the rock matrix resulted in large visible pore spaces. Using 7.45 µm resolution CMT images, the permeability for a large isolated pore could not be calculated using the previous workflow due to computer memory limitations. Resampling enabled the data to fit into the available computer memory. The permeability values ranged from 2.66x10^5 to 8.59x10^5 mD for resampling the CMT images from 2x to 10x

Swimming behaviour of a flagellated alga in Newtonian and complex fluids

Many microscopic swimmers in nature navigate through complex fluids, such as worm type swimmers in muds, and spermatozoa in cervical mucus. An understanding of the swimming response to such fluids is gaining increasing attention with the hope they will aid in the development of artificial microswimmers and in enhancing processes involving natural bioswimmers, such as fertility treatments. In this work, the swimming behaviour of a swimming green algae, Dunaliella salina, is examined experimentally. Fluids with different rheological properties have been used to study the e�ects of increasing viscosity, shear thinning properties and viscoelasticity of the surrounding medium on the algae swimming characteristics, such as velocity, beating frequencies and stroke velocities. In a water-like medium akin to their natural environment, the algae were found to swim with a velocity of Vnet = 49:55 µms⁻¹ while beating at a frequency of fBF = 29:97 Hz. With the addition of a viscous enhancing agent (Ficoll PM400) the algae swimming velocity followed an essentially monotonic decrease as viscosity increased, based on a power-law relationship (V x ƞ⁻¹). This was attributed to the constant drag produced by the algae and limited variations in the stroke dynamics, which was confirmed by analysis of the power and recovery strokes. Compared to the Newtonian cases, when the surrounding fluid exhibited shear thinning properties, achieved by addition of Xanthan gum, the swimmer displayed reduced stroke times for comparable displacements in the Newtonian cases. This lead to an overall boost in the recovery stroke over the power stroke. Polyacrylamide was used to analyse the viscoelastic response of the algae. However, for this particular case it was apparent that due to the confounding effects of elasticity and shear thinning, it was difficult to define an elastic response. Furthermore, the wall interactions of Dunaliella salina was quantified, with a preference to bounce from a wall observed. The approach dynamics to the wall were found to hold little influence on the escape, with only a slight tendency for increased reverse bounces at high approach angles and slower velocities.Many microscopic swimmers in nature navigate through complex fluids, such as worm type swimmers in muds, and spermatozoa in cervical mucus. An understanding of the swimming response to such fluids is gaining increasing attention with the hope they will aid in the development of artificial microswimmers and in enhancing processes involving natural bioswimmers, such as fertility treatments. In this work, the swimming behaviour of a swimming green algae, Dunaliella salina, is examined experimentally. Fluids with different rheological properties have been used to study the e�ects of increasing viscosity, shear thinning properties and viscoelasticity of the surrounding medium on the algae swimming characteristics, such as velocity, beating frequencies and stroke velocities. In a water-like medium akin to their natural environment, the algae were found to swim with a velocity of Vnet = 49:55 µms⁻¹ while beating at a frequency of fBF = 29:97 Hz. With the addition of a viscous enhancing agent (Ficoll PM400) the algae swimming velocity followed an essentially monotonic decrease as viscosity increased, based on a power-law relationship (V x ƞ⁻¹). This was attributed to the constant drag produced by the algae and limited variations in the stroke dynamics, which was confirmed by analysis of the power and recovery strokes. Compared to the Newtonian cases, when the surrounding fluid exhibited shear thinning properties, achieved by addition of Xanthan gum, the swimmer displayed reduced stroke times for comparable displacements in the Newtonian cases. This lead to an overall boost in the recovery stroke over the power stroke. Polyacrylamide was used to analyse the viscoelastic response of the algae. However, for this particular case it was apparent that due to the confounding effects of elasticity and shear thinning, it was difficult to define an elastic response. Furthermore, the wall interactions of Dunaliella salina was quantified, with a preference to bounce from a wall observed. The approach dynamics to the wall were found to hold little influence on the escape, with only a slight tendency for increased reverse bounces at high approach angles and slower velocities

Parallel three-dimensional acoustic and elastic wave simulation methods with applications in nondestructive evaluation

In this dissertation, we present two parallelized 3D simulation techniques for three-dimensional acoustic and elastic wave propagation based on the finite integration technique. We demonstrate their usefulness in solving real-world problems with examples in the three very different areas of nondestructive evaluation, medical imaging, and security screening. More precisely, these include concealed weapons detection, periodontal ultrasography, and guided wave inspection of complex piping systems. We have employed these simulation methods to study complex wave phenomena and to develop and test a variety of signal processing and hardware configurations. Simulation results are compared to experimental measurements to confirm the accuracy of the parallel simulation methods

Proceedings /5th International Symposium on Industrial Engineering – SIE2012, June 14-15, 2012., Belgrade

editors Dragan D. Milanović, Vesna Spasojević-Brkić, Mirjana Misit

Proceedings /5th International Symposium on Industrial Engineering – SIE2012, June 14-15, 2012., Belgrade

editors Dragan D. Milanović, Vesna Spasojević-Brkić, Mirjana Misit

Establishing an anatomically and clinically relevant tissue engineered tendon-bone model of the flexor digitorum profundus insertion

Avulsion of the flexor digitorum profundus (FDP) tendon from the distal phalanx (DP) in the finger is a common and distinct clinical injury of the hand (‘jersey finger’) with considerable functional morbidity. Multiple surgical techniques are employed to reattach the tendon to the bone, but no single technique has emerged as the optimal treatment method. Issues such as reduced range of movement, infection, nail deformity and cost complicate the requirement for strong fixation and prevention of re-rupture. Crucially, repair of avulsion injuries does not regenerate the enthesis, the region of graded multiphasic microanatomy at the tendon-bone insertion. The enthesis allows uniform muscle force transmission between the mechanically distinct tendon and bone through specialised adaptations to dissipate stress foci. Avulsion repair is scar-mediated and of low mechanical strength, prone to re-rupture at the tendon-bone interface. Interfacial tissue engineering provides the opportunity to create an in vitro tendon-bone model with potential to re-establish the enthesis through co-culture of tendon and bone cells, which could be used to evaluate repair techniques or as a composite tissue graft for clinical use. The aim of this project was to establish an in vitro model system that was anatomically representative and clinically applicable to the investigation and treatment of FDP avulsion injury. The 2 main objectives were to thoroughly evaluate the native anatomy of the human FDP insertion, and to design and develop a relevant 3-dimensional (3D) in vitro tendon-bone co-culture model. Human cadaveric tissue was dissected and photographed for image analysis to determine gross shape and dimension morphometrics of the FDP-DP tendon-bone interface, FDP tendon and DP bone. Finger and gender differences were found to significantly influence measurement values, with data groupings informing design guidelines for ‘small’, ‘medium’ and ‘large’ model sizes. Cadaveric tissue was also histologically processed to qualitatively describe the fibrocartilaginous FDP enthesis for the first time. Quantitative analysis of tendon fibres revealed a mean angle of insertion across the soft-hard tissue interface of 30o, providing a guide to the angled attachment of the tendon and bone model components. Development of the in vitro model enhanced an existing multi-tissue fibrin scaffold soft tissue-bone anchor design into an FDP tendon analogue-DP bone anchor single species co-culture construct. Rat fibroblast and osteoblast cultures were established and characterised in standard growth medium, mineralising medium and a 50:50 media mix. Formation and maturation of the fibroblast-seeded fibrin tendon analogue was analysed histologically in single and multi-strand cultures for morphological development and collagen deposition. Long term tendon analogues were cultured with different anchor sizes, fibrin constituent volumes, cell numbers and growth media for width comparison with cadaveric tendon data, and assessment of 3D morphology with optical coherence tomography. Investigation of the bone anchor component focused on brushite, a phosphate mineral-based bone scaffold material, including assessment of attachment and proliferation of seeded osteoblasts. Model assembly required development of a novel 3D printed mold and silicone impression system for guided tendon analogue culture and angled bone anchor attachment. Optimal design elements and in vitro culture materials ultimately combined to produce a fibroblast-seeded tendon analogue and osteoblast-seeded bone anchor 3D model, co-cultured in 3 anatomical sizes clinically relevant to FDP tendon avulsion. These models can be used as the basis to study enthesis formation and further optimised towards a clinical product for use in FDP avulsion repair