Using Texture Synthesis for Non-Photorealistic Shading from Paint Samples

This paper presents several methods for shading meshes from scanned paint samples that represent dark to light transitions. Our techniques emphasize artistic control of brush stroke texture and color. We first demonstrate how the texture of the paint sample can be separated from its color gradient. We demonstrate three methods, two real-time and one off-line for producing rendered, shaded images from the texture samples. All three techniques use texture synthesis to generate additional paint samples. Finally, we develop metrics for evaluating how well each method achieves our goal in terms of texture similarity, shading correctness and temporal coherence

Physical and mathematical modeling of wave propagation in the Ariane 5 VEB structure

The separation of the lower stage of the ARIANE 5 Vehicle Equipment Bay (VEB) Structure is to be done using a pyrotechnic device. The wave propagation effects produced by the explosion can affect the electronic equipment, so it was decided to analyze, using both physical and numerical modeling, a small piece of the structure to determine the distribution of the accelerations and the relative importance of damping, stiffness, connections, etc. on the response of the equipment

ToMRobot 2.0: real mobility mechanism in MANET testbed using mobile robot

This paper is a continuation of our previous paper under the same topic, ToMRobot 1.0. Our main goal of developing ToMRobot 2.0 is to improve the ToMRobot 1.0 that we developed earlier. ToMRobot was developed because we think mobile robot technology is more practical than other approaches as a real world mobility mechanism in MANET testbed. But to develop our own mobile robot at low cost and at the same time not complex is very challenging. The challenge is overcome through the use of easy-to-use components, self-built components using 3D printers and the use of mobile robot designs that have proven to be easily developed, cheap and effective. The use of the Robot Operating System (ROS) as the main robot software framework greatly helps to reduce the complexity of developing control system for mobile robot

Acid-Base Catalyzed Activation of n-Alkanes: Isomerization of n-Butane

Due to its unique activity for skeletal isomerization of short alkanes at low temperature, sulfated zirconia (SZ) is generally recognized as the most promising alternative for the zeolite based hydroisomerization catalysts. However, despite the large amount of investigations, several important topics related to SZ are still discussed controversially. Here we report on our detailed investigation of the mechanism of butane skeletal isomerization on SZ. Typically, SZ had an induction period followed by a period of virtually constant activity. The selectivity to isobutene was higher than 96%, the byproducts being propane and pentanes. The induction period can be related to the formation and accumulation of reactive intermediates on the catalyst surface. We show that the alkane activation is initiated via stoichiometric oxidative dehydrogenation of butane by sulphate species to butane, water and SO2. For the first time, direct experimental evidence is given for all reaction products formed by oxidative dehydrogenation. In situ IR spectroscopy and density functional calculations indicate that pyrosulfate or re-adsorbed SO3 species are the active species for the oxidation. Butene formed interacts with Bronsted acid sites and forms sec-butoxy groups which isomerize mono-molecularly to tert-butoxy groups, as deduced from the 100% selectivity to isobutane at zero conversion. The tert-butoxy group undergoes hydride transfer from n-butane, forming a new sec-butoxy group and isobutane. The lower selectivity to isobutane with increasing conversion is explained by the higher isobutene concentration which triggers a bimolecular pathway. Note that isobutane is kinetically a primary product, while propane and pentanes are secondary products formed in sequential reactions. The larger amount of propane with respect to pentanes for conversion above 40% is attributed to multiple alkylation reactions followed by cracking. Transient experiments showed conclusively that the isomerization of the carbenium ion is the rate-determining step in the chain sequence and that hydride transfer is in quasi equilibrium. A kinetic model for butane isomerization under differential conditions is presented showing that the overall rate of butane conversion is proportional to the rate constant of the monomolecular isomerization of the carbenium ion, the concentration of Bronsted acid sites, the partial pressure of the alkane and the concentration of the labile sulfate-based redox sites. We show here that the key to successful catalysts for skeletal isomerization does not lie in high acid strength, but that a subtle balance between redox and acid sites is necessary

Mobile ad hoc network testbed using mobile robot technology

MANET (Mobile Ad Hoc Network) researchers have shown increased interest in using mobile robot technology for their testbed platforms. Thus, the main motivation of this paper is to review various robot-based MANET testbeds that have been developed in previously reported research. Additionally, suggestions to heighten mobility mechanisms by using mobile robots to be more practical, easy and inexpensive are also included in this paper, as we unveils ToMRobot, a low-cost MANET robot created from an ordinary remote control car that is capable of performing a real system MANET testbed with the addition of only a few low-cost electronic components. Despite greatly reduced costs, the ToMRobot does not sacrifice any of the necessary MANET basic structures and will still be easily customizable and upgradeable through the use of open hardware technology like Cubieboard2 and Arduino, as its robot controller. This paper will also include guidelines to enable technically limited MANET researchers to design and develop the ToMRobot. It is hoped that this paper achieves its two pronged objectives namely (i) to facilitate other MANET researchers by providing them with a source of reference that eases their decision making for selecting the best and most suitable MANET mobile robots for real mobility in their MANET testbeds (ii) to provide MANET researchers with a prospect of building their own MANET robots that can be applied in their own MANET testbed in the future

4D and 5D phase-space tomography using slowing-down physics regularization

We compute reconstructions of 4D and 5D fast-ion phase-space distribution functions in fusion plasmas from synthetic projections of these functions. The fast-ion phase-space distribution functions originating from neutral beam injection (NBI) at TCV and Wendelstein 7-X (W7-X) at full, half, and one-third injection energies can be istinguished and particle densities of each component inferred based on 20 synthetic spectra of projected velocities at TCV and 680 at W7-X. Further, we demonstrate that an expansion into a basis of slowing-down distribution functions is equivalent to regularization using slowing-down physics as prior information. Using this technique in a Tikhonov formulation, we infer the particle density fractions for each NBI energy for each NBI beam from synthetic measurements, resulting in six unknowns at TCV and 24 unknowns at W7-X. Additionally, we show that installing 40 LOS in each of 17 ports at W7-X, providing full beam coverage and almost full angle coverage, produces the highest quality reconstructions

Analysis of Sample Correlations for Monte Carlo Rendering

Modern physically based rendering techniques critically depend on approximating integrals of high dimensional functions representing radiant light energy. Monte Carlo based integrators are the choice for complex scenes and effects. These integrators work by sampling the integrand at sample point locations. The distribution of these sample points determines convergence rates and noise in the final renderings. The characteristics of such distributions can be uniquely represented in terms of correlations of sampling point locations. Hence, it is essential to study these correlations to understand and adapt sample distributions for low error in integral approximation. In this work, we aim at providing a comprehensive and accessible overview of the techniques developed over the last decades to analyze such correlations, relate them to error in integrators, and understand when and how to use existing sampling algorithms for effective rendering workflows.publishe

Compressed Suffix Arrays for Massive Data

We present a fast space-efficient algorithm for constructing compressed suffix arrays (CSA). The algorithm requires O(n log n) time in the worst case, and only O(n) bits of extra space in addition to the CSA. As the basic step, we describe an algorithm for merging two CSAs. We show that the construction algorithm can be parallelized in a symmetric multiprocessor system, and discuss the possibility of a distributed implementation. We also describe a parallel implementation of the algorithm, capable of indexing several gigabytes per hour