Interactive simulation of fire, burn and decomposition

This work presents an approach to effectively integrate into one unified modular fire simulation framework the major processes related to fire, namely: a burning process, chemical combustion, heat distribution, decomposition and deformation of burning solids, and rigid body simulation of the residue. Simulators for every stage are described, and the modular structure enables switching to different simulators if more accuracy or more interactivity is desired. A “Stable Fluids” based three gas system is used to model the combustion process, and the heat generated during the combustion is used to drive the flow of the hot air. Objects, if exposed to enough heat, ignite and start burning. The decomposition of the burning object is modeled as a level set method, driven by the pyrolysis process, where the burning object releases combustible gases. Secondary deformation effects, such as bending burning matches and crumpling burning paper, are modeled as a proxy based deformation. Physically based simulation, done at interactive rates, enables the user to ef- ficiently test different setups, as well as interact and change the conditions during the simulation. The graphics card is used to generate additional frames for real-time visualization. This work further proposes a method for controlling and directing high resolution simulations. An interactive coarse resolution simulation is provided to the user as a “preview” to control and achieve the desired simulation behavior. A higher resolution “final” simulation that creates all the fine scale behavior is matched to the preview simulation such that the preview and final simulations behave in a similar manner. In this dissertation, we highlighted a gap within the CG community for the simulation of fire. There has not previously been a physically based yet interactive simulation for fire. This dissertation describes a unified simulation framework for physically based simulation of fire and burning. Our results show that our implementation can model fire, objects catching fire, burning objects, decomposition of burning objects, and additional secondary deformations. The results are plausible even at interactive frame rates, and controllable

Real-world efficacy and safety of Ledipasvir plus Sofosbuvir and Ombitasvir/Paritaprevir/Ritonavir +/- Dasabuvir combination therapies for chronic hepatitis C: A Turkish experience

Background/Aims: This study aimed to evaluate the real-life efficacy and tolerability of direct-acting antiviral treatments for patients with chronic hepatitis C (CHC) with/without cirrhosis in the Turkish population.Material and Methods: A total of 4,352 patients with CHC from 36 different institutions in Turkey were enrolled. They received ledipasvir (LDV) and sofosbuvir (SOF)+/- ribavirin (RBV) ombitasvir/paritaprevir/ritonavir +/- dasabuvir (PrOD)+/- RBV for 12 or 24 weeks. Sustained virologic response (SVR) rates, factors affecting SVR, safety profile, and hepatocellular cancer (HCC) occurrence were analyzed.Results: SVR12 was achieved in 92.8% of the patients (4,040/4,352) according to intention-to-treat and in 98.3% of the patients (4,040/4,108) according to per-protocol analysis. The SVR12 rates were similar between the treatment regimens (97.2%-100%) and genotypes (95.6%-100%). Patients achieving SVR showed a significant decrease in the mean serum alanine transaminase (ALT) levels (50.90 +/- 54.60 U/L to 17.00 +/- 14.50 U/L) and model for end-stage liver disease (MELD) scores (7.51 +/- 4.54 to 7.32 +/- 3.40) (p<0.05). Of the patients, 2 were diagnosed with HCC during the treatment and 14 were diagnosed with HCC 37.0 +/- 16.0 weeks post-treatment. Higher initial MELD score (odds ratio [OR]: 1.92, 95% confidence interval [CI]: 1.22-2.38; p=0.023]), higher hepatitis C virus (HCV) RNA levels (OR: 1.44, 95% CI: 1.31-2.28; p=0.038), and higher serum ALT levels (OR: 1.38, 95% CI: 1.21-1.83; p=0.042) were associated with poor SVR12. The most common adverse events were fatigue (12.6%), pruritis (7.3%), increased serum ALT (4.7%) and bilirubin (3.8%) levels, and anemia (3.1%).Conclusion: LDV/SOF or PrOD +/- RBV were effective and tolerable treatments for patients with CHC and with or without advanced liver disease before and after liver transplantation. Although HCV eradication improves the liver function, there is a risk of developing HCC.Turkish Association for the Study of The Liver (TASL

Interactive physically-based cloud simulation

Artificial clouds play an important role in the computer generation of natural outdoor scenes. Realistic modeling and rendering of such scenes is important for applications in games, military training simulations, flight simulations, and even in the creation of digital artistic media. We propose a model for simulating cloud formation based on an efficient computational fluid solver. We combine the fluid solver with a model of the natural processes of cloud formation, including buoyancy, relative humidity, and condensation. This allows us to simulate the formation and growth of clouds at interactive rates.

Preview-based Sampling for Controlling Gaseous Simulations

In this work, we describe an automated method for directing the control of a high resolution gaseous fluid simulation based on the results of a lower resolution preview simulation. Small variations in accuracy between low and high resolution grids can lead to divergent simulations, which is problematic for those wanting to achieve a desired behavior. Our goal is to provide a simple method for ensuring that the high resolution simulation matches key properties from the lower resolution simulation. We first let a user specify a fast, coarse simulation that will be used for guidance. Our automated method samples the data to be matched at various positions and scales in the simulation, or allows the user to identify key portions of the simulation to maintain. During the high resolution simulation, a matching process ensures that the properties sampled from the low resolution simulation are maintained. This matching process keeps the different resolution simulations aligned even for complex systems, and can ensure consistency of not only the velocity field, but also advected scalar values. Because the final simulation is naturally similar to the preview simulation, only minor controlling adjustments are needed, allowing a simpler control method than that used in prior keyframing approaches

Function Based Flow Modeling and Animation

This paper summarizes a function-based approach to model and animate 2D and 3D flows. We use periodic functions to create cyclical animations that represent 2D and 3D flows. These periodic functions are constructed with an extremely simple algorithm from a set of oriented lines. The speed and orientation of the flow are described directly by the orientation and the lengths of these oriented lines. The resulting cyclical animations are then obtained by sampling the constructed periodic functions. Our approach is independent of dimension, i.e. for 2D and 3D flow the same types of periodic functions are used. Rendering images for 2D and 3D flows are slightly different. In 2D function values directly are mapped to color values. On the other hand, in 3D function values first mapped to color and opacity and then the volume is rendered by our volume renderer. Modeled and animated flows are used to improve the visualization of operations of rolling piston and rotary vane compressors

Visualization of fibrous and thread-like data

Abstract — Thread-like structures are becoming more common in modern volumetric data sets as our ability to image vascular and neural tissue at higher resolutions improves. The thread-like structures of neurons and micro-vessels pose a unique problem in visualization since they tend to be densely packed in small volumes of tissue. This makes it difficult for an observer to interpret useful patterns from the data or trace individual fibers. In this paper we describe several methods for dealing with large amounts of thread-like data, such as data sets collected using Knife-Edge Scanning Microscopy (KESM) and Serial Block-Face Scanning Electron Microscopy (SBF-SEM). These methods allow us to collect volumetric data from embedded samples of whole-brain tissue. The neuronal and microvascular data that we acquire consists of thin, branching structures extending over very large regions. Traditional visualization schemes are not sufficient to make sense of the large, dense, complex structures encountered. In this paper, we address three methods to allow a user to explore a fiber network effectively. We describe interactive techniques for rendering large sets of neurons using self-orienting surfaces implemented on the GPU. We also present techniques for rendering fiber networks in a way that provides useful information about flow and orientation. Third, a global illumination framework is used to create high-quality visualizations that emphasize the underlying fiber structure. Implementation details, performance, and advantages and disadvantages of each approach are discussed. Index Terms—neuron visualization, GPU acceleration, global illumination, orientation filtering

Polymerization Strategy for the Compression, Segmentation, and Modeling of Volumetric Data

We present a data structure for the representation of volumetric data. The data structure is designed to allow for easy compression, storage, segmentation, and reconstruction of volumetric data. We call our data structure the L-block, abstracting many of the properties of Lego ® blocks, and refer to the process of creating and manipulating L-blocks as the polymerization strategy. The concept of an enhanced volume data set (EVDS) is introduced, where the data set is enhanced by explicitly introducing Boolean labeling of edges between adjacent voxels of the volume data. This enhancement, by “polymerizing ” adjacent connected voxels into connected components, facilitates real-time data compression and segmentation of embedded objects within the volume data set. These connected components are packaged in the new container type, the L-block, with the intention of efficiently packaging the connected components with a minimum of adjacent unconnected voxels. We present the L-block data structure in detail. We describe methods for compressing volume data using the L-block structure, intersecting and merging L-blocks, and segmenting data. While the L-block data structure is general, it was developed to represent scanned brain microstructure at a neuronal level of detail. We highlight the performance of our implementation of the polymerization strategy on a set of sampled neuronal data