bluuebunny/crossref_metadata_2025_split huggingface dataset:
Advanced object‐oriented methods and concepts for simulations of multi‐body systems
Authors: Kühn Volker , Müller Wolfgang 
Published: November 2006

AbstractA common way to simulate the motion and behaviour of a complex system is to approximate it with a multi‐body system based on particles, and to evaluate the particle interactions over time. Normally, the calculations require such a large amount of computer power that methods have been developed to decrease computation time by taking advantage of new computer architectures.These methods have been in use since the early 1980s, but there is still a lack of concepts supporting the application of these methods, to build highly efficient simulation systems with reusable entities.In this paper we describe a new approach for the development of flexible, efficient methods and techniques to control multi‐body systems. The major goal of our concept is the integration of advanced modern simulation techniques such as particle‐based modelling and simulated annealing, and efficient data structures such as octrees and the Greengard algorithm. We introduce high‐level concepts represented by agents, environments, and controllers based on and supported by the object‐oriented paradigm.We demonstrate the flexibility of our new simuation system for applications related to environmental research and air quality control.
Building blocks for goal‐directed motion
Authors: van Overveld C. W. A. M. 
Published: November 2006

AbstractAn approach for the integration of intelligent goal directed motion within an interactive real‐time computer animation environment is sketched. The approach is based on a cause‐and‐effect model for intelligent goal direction motion which gives rise to types of motion primitives: one is the application of a so called multi‐track recording paradigm for direction motion manipulation; the second is an algorithm to mimic a control system for goal directed motion of joints in a multi‐link structure. The techniques described here are features of the procedure based animation system which is described in Reference 1.
Visual simulation of botanical trees based on virtual heliotropism and dormancy break
Authors: Chiba Norishige , Ohkawa Shunichi , Muraoka Kazunobu , Miura Mamoru 
Published: November 2006

AbstractRealistic image synthesis of botanical trees has many applications. Since the generation of ‘tree skeletons’ having natural visual impressions is essential to realistic image synthesis, various methods of modelling skeletons, especially growth models, have been presented. However, no one has succeeded in simulating natural tree features which appear in a growth process, such as generation of a round tree crown, a weeping bough, an irregular branching pattern, or regeneration of a crown.This paper demonstrates, by showing several simulated examples, that a growth model having the abilities of heliotropism and dormancy break, which produces shapes of trees adapted to changes in the light environment, is effective in the CG simulation of realistic tree skeletons.
Two‐dimensional visual simulation of flames, smoke and the spread of fire
Authors: Chiba Norishige , Muraoka Kazunobu , Takahashi Hiromichi , Miura Mamoru 
Published: November 2006

AbstractSince CG simulation of natural phenomena on the basis of their forms and motions has many applications, such as various landscape designs and special effects in films, it is very important and interesting to develop efficient techniques for their visual simulation. It is especially interesting to produce realistic images and animations of flames and smoke, on account of their complicated patterns of behaviour.Effective simulation methods for flames and smoke are expected to satisfy the following requirements:

The motion of flames or smoke produced in an interaction with obstacles can be simulated.
The motion of flames and smoke can be easily controlled according to scenarios.
The spread of fire can be simulated.
Although several useful representation methods have been proposed so far, simulating flames and smoke still remains a challenging problem. In this paper, we first describe our basic two‐dimensional visual simulation method based on particle‐based simulation, but not based on exact physical simulation. Roughly speaking, our method assumes that the images of flames and smoke are basically obtained by visualizing turbulence, that is, the particles of flames and smoke play the role of tracers in the field of turbulence. Next, we present an improved method for simulating the spread of fire and the appearance of smoke produced in an incomplete combustion. Simultaneously, we show several examples of the simulation. Finally, we will touch slightly on further problems for extending the model to one which works in three‐dimensional space.
Direct volume rendering of multiple scalar fields
Authors: Giertsen Christopher 
Published: November 2006

AbstractRendering of volume data without forming geometric objects is often termed direct volume rendering. Most of the previously developed methods for this purpose are restricted to display of one scalar variable. This paper presents methods for direct volume rendering of several scalar variables defined at discrete points in three‐dimensional space. Typical requirements for the rendering of such data are proposed and then used as a basis for the derivation of a computational model. The proposed model uses a classification technique to composite specific types of information from different scalar fields. The visual display of the composite information is controlled through a set of rendering parameters.
Super TEX‐SIM: Interactive textile design and simulation
Authors: Kambe Hisashi , Yamasaki Nobuhiko , Lee Myeong Won 
Published: November 2006

AbstractThis paper presents an interactive tool for designing and simulating textile images. It comprises a yarn editor, a textile editor and a texture mapper. These subsystems share a colour editor that can modify the colours of yarn and textile images interactively. We describe how yarn and textile images are generated, and how they are mapped to a target picture read from an image scanner. The user interface in the tool has many useful functions so that users can design textile images without knowledge of computer graphics and programming languages. Several examples of texture mapping are included.
The modelling of large waterfalls using string texture
Authors: Mallinder Hugh 
Published: November 2006

AbstractParticle systems have been extensively used for modelling fluid flow. But if a large number of particles are required, this can lead to unreasonably large amounts of memory usage. This is because the position and velocity is stored explicitly for each particle. Solid texture, on the other hand, stores parameters implicitly, by means of addressing small look‐up tables. This paper presents a method of implicitly storing particles, and illustrates its use with the modelling of large waterfalls.
Application paper. Applying ray casting to the flow visualization data using linear and B‐spline hyperpatch interpolation
Authors: Semwal Sudhanshu Kumar , Swann Paul Gene 
Published: November 2006

AbstractVisualizing the flow of air or fluids is especially challenging because of their transparency and possible high velocity. Complex patterns are created when the flow is over or around an object. Our aim is to visualize the flow in three dimensions, eliminating the need for mentally piecing the flow from two‐dimensional slices. We have applied the well‐known ray casting technique to visualize the flow around an aircraft wing. During ray casting, when the ray does not intercept the lattice points, linear and B‐spline hyperpatch interpolations are used to estimate the colour. We describe the shading equation, and compare the linear and the B‐spline hyperpatch interpolation schemes during ray casting. Several images are produced to show the difference in the image quality of these two methods, and their image generation time.
Combining physically‐based simulation of colliding objects with trajectory control
Authors: Lamouret Alexis , Gascuel Marie‐Paule , Gascuel Jean‐Dominique 
Published: November 2006

AbstractThis paper describes a method that facilitates the use of physically‐based models by animators. The main point is to give the animator a familiar interface, while providing a simulation module which detects collisions, thus enhancing realism.The user gives a set of key‐frames to guide motion, but does not have to address problems such as interpenetration avoidance, deformations due to collisions, or realism of motion. The simulator will correct the trajectories and compute deformations according to each object's physical properties (such as mass, inertia, stiffness) as well as the collisions and contacts automatically detected during motion. To achieve this, objects are provided with actuators capable of generating forces and torques computed via generalized proportional‐derivative controllers. When deflected by external actions, actuated objects try to return to their initial path. Speed variations over time are computed during the simulation, and depend on the complexity of the paths, on the objects models, and on the events such as collisions occurring during motion. In addition simulations are generated at interactive rates, even in the case of complex articulated objects. This facilitates the fine tuning of an animation sequence.
An L‐systems approach to the modelling of fungal growth
Authors: Tunbridge Andrew , Jones Huw 
Published: November 2006

AbstractA parametric L‐system is developed to model the growth and structure of the fungus Aspergillus nidulans. The model uses biological understanding of the flow of nutrients through the fungus to control the simulation of growth, with L‐systems productions being dependent on the levels of nutrients, stored as parameters, in various parts of the model. This produces a structural model that is consistent with previous observations of the natural fungus. Visual interpretation of the L‐systems string uses a turtle graphics method. When stochastic rules are implemented to model specific features of Aspergillus nidulans, the simulation is convincing both visually and structurally. Other potential applications for the method are suggested.
An integrated approach to motion and sound
Authors: Hahn James K. , Geigel Joe , Lee Jong Won , Gritz Larry , Takala Tapio , Mishra Suneil 
Published: November 2006

AbstractUntil recently, sound has been given little attention in computer graphics and related domains of computer animation and virtual environments, although sounds which are properly synchronized to motion provide a great deal of information about events in the environment. Sounds are often not properly synchronized because the sounds and the phenomena that caused the sounds are not considered in an integrated way. In this paper, we present an integrated approach to motion and sound as it applies to computer animation and virtual environments. The key to this approach is synchronization by mapping the motion parameters to sound parameters so that the sound changes as a result of changes in the motion. This is done by representing sounds using a technique for functional composition analogous to the ‘shade trees’ which we calltimbre trees.These timbre trees are used as a part of a sound description language that is analogous to scene description languages such as RenderMan. Using this methodology, we have produced convincing sound effects for a wide variety of animated scenes including the automatic generation of background music.
Visualization of connectivity in octree based models
Authors: Fedenczuk Leon L. , Wyvill Brian 
Published: November 2006

AbstractAn interesting problem in the oil and gas industry is the visualization of the movement of oil and gas in porous media. An example of such a medium is a rock sample with some distribution of holes (pores) connected by channels (pore throats), the solid parts of the rock are called grains. In our work we have simulated the porous medium using a pointer‐based octree, representing these pores and grains. This data structure allows us to model the connectivity of the pores and thus visualize fluid penetration within the medium. Whereas earlier models represent a serious simplifications or two dimensional homogeneous layers, our model provides us with a statistically accurate distribution in three dimensions and a more accurate representation of the connectivity.In this paper we present our data structure and the techniques which were used to create models of porous media and their porous networks. Next, we present algorithms for connectivity in octrees and we show how to apply them to modelling and visualization of fluid penetration in porous media.
Subvolume projection: A full exploitation of function coherence for volume rendering
Authors: Zhou Yong , Tang Zesheng 
Published: November 2006

AbstractDirect volume rendering techniques present a huge potential for displaying a great amount of information in 3D data sets within one image. However, generating such an image is extremely expensive, and rendering for high quality pictures is far from interactive. Traditional volume rendering approaches are based on a cell‐by‐cell model. They consider cells as the smallest manipulation object. The time complexity of the volume rendering is determined by the number of cells, and the image quality, to some extent, is affected by the cell tessellation of volumes. Many scientists and technicians rarely venture to research the exploitation of coherence of function distribution over scalar fields through partition of data volumes. This paper proposes a new volume rendering approach: subvolume projection. It not only exploits the spatial coherence of cells but employs fully the spatial coherence of function distribution to partition a volume into a number of subvolumes, so that the function varies slowly over each subvolume. Each newly generated subvolume can be considered as containing a single material and treated as the smallest unit instead of cells in the processing. Based on the subdivision of the volume, this paper discusses the calculation of intensity contributed by the subvolumes in detail. Theoretical analysis and a variety of experimental results show that the new approach improves image quality and reduces rendering time period. (Usually the new algorithm is three to four times faster than the traditional volume rendering algorithms).
A radiosity solution for random fractal surfaces
Authors: Wu En‐Hua 
Published: November 2006

AbstractFractal geometry provides an outstanding mathematical tool for simulating natural phenomena. However, the recursive process of stochastic modelling in generating random fractals puts forward difficult problems in the rendering. At present, only some special ray tracing methods have been provided to render fractals, mainly producing specular illumination. This paper proposes a radiosity solution for rendering random fractals, in which diffuse interreflection can be calculated in the process of stochastic modelling. By this solution, the recursive process of fractal generation is naturally incorporated into the progressive refinement procedure of the radiosity solution. Particularly, it becomes possible for fractal surfaces to participate in the energy shooting process of the radiosity solution.The key problem in the proposed approach is in calculating the radiosity redistribution for fractal subdivision. An algorithm for solving the problem has been proposed and implemented. Test examples show that the method is quite efficient. The technique may improve the visual realism of the radiosity image and promote the practical value of the radiosity solution.
Regime shifts: catastrophic responses of ecosystems to human impacts
Authors: Genkai‐Kato Motomi 
Published: November 2006

AbstractEvidence of abrupt changes in ecosystem states, such as sudden eutrophication in lakes, has been increasingly reported in a variety of aquatic and terrestrial systems. Ecosystems may have more than one state with a self‐stabilizing mechanism, so that a shift between states does not occur frequently and is not readily reversible. These big changes are termed regime shifts where often one state is preferred over another. Thus, regime shifts are problematic for ecosystem managers, and the need exists for studies that lead to the identification of thresholds of key variables that trigger regime shifts. Regime shifts are currently difficult to predict and in many cases may be caused by the human pursuit of efficiency in land and water productivity in the last few decades. Here I briefly introduce a theoretical approach to predict the shift between a clear‐water state and a turbid state in lakes, the best‐studied example of regime shifts. This paper also discusses alternative states in other natural systems besides ecosystems to draw more attention to the research currently being performed on regime shifts.
Preparation and properties of a new type of carbohydrate‐based cationic surfactant
Authors: Kirk Ole , Pedersen Flemming D. , Fuglsang Claus C. 
Published: November 2006

AbstractA new type of cationic surfactant, 6‐O‐monoesters of 3‐(trimethylammonio)propyl d‐glucopyranoside, was prepared in high yield by a simple chemoenzymatic synthesis. Surface‐active properties of the compounds were found to be highly dependent on the fatty acyl chain length in the 6‐O‐position with the dodecanoyl and tetradecanoyl esters exhibiting the highest ability to lower surface tension as well as having the lowest critical micelle concentration values. Furthermore, the dodecanoyl ester had excellent foaming properties. The new surfactants also showed antimicrobial activity. Thus, the most potent compound, the dodecanoyl ester, was able to inhibit growth of both bacterial (Gram‐positive as well as Gram‐negative) and fungal test strains. The antimicrobial effect was somewhat weaker compared to benzalkonium chloride, one of the most frequently used cationics for topical disinfection. However, compared to benzalkonium chloride, the new cationics exhibit a highly improved compatibility with anionic surfactants, as no precipitation took place even in highly concentrated solutions thereby providing a much more robust antimicrobial system. Finally, the new surfactants are expected to be readily biodegradable because they are carbohydrate ester‐based.
Carbohydrate‐alkyl ester derivatives as biosurfactants
Authors: Allen Douglas K. , Tao Bernard Y. 
Published: November 2006

AbstractReaction of carbohydrates with long‐chain plantderived lipids yields carbohydrate‐alkyl ester surfactants with a polyol structure. Their renewability, low cost, and environmental acceptability make carbohydrate‐alkyl ester surfactants an excellent alternative to petrochemically derived products. This article reviews developments in the synthesis and surface‐active properties of carbohydrate‐alkyl ester surfactants
Role of dietary calcium and dairy products in modulating adiposity
Authors: Zemel Michael B. 
Published: November 2006

AbstractDietary calcium plays a pivotal role in the regulation of energy metabolism. High‐calcium diets attenuate adipocyte lipid accretion and weight gain during overconsumption of an energy‐dense diet and increase lipolysis and preserve thermogenesis during caloric restriction, thereby markedly accelerating weight loss. Our studies of the agouti gene demonstrate a key role for intracellular Ca2+ in regulating adipocyte lipid metabolism and TG storage. Increased intracellular Ca2+ resulting in stimulation of lipogenic gene expression, and lipogenesis and suppression of lipolysis resulting in adipocyte lipid filling and increased adiposity. Moreover, we recently demonstrated that the increased calcitriol produced in response to lowcalcium diets stimulates adipocyte Ca2+ influx and, consequently, promotes adiposity. Accordingly, suppressing calcitriol levels by increasing dietary calcium is an attractive target for obesity intervention. In support of this concept, transgenic mice expressing the agouti gene specifically in adipocytes (a human‐like pattern) respond to low‐calcium diets with accelerated weight gain and fat accretion, whereas high‐calcium diets markedly inhibit lipogenesis, accelerate lipolysis, increase thermogenesis, and suppress fat accretion and weight gain in animals maintained at identical caloric intakes. Further, low‐calcium diets impede body fat loss, whereas high‐calcium diets markedly accelerate fat loss in transgenic mice subjected to caloric restriction. Dairy sources of calcium exert markedly greater effects in attenuating weight and fat gain and accelerating fat loss. This augmented effect of dairy products is likely due to additional bioactive compounds in dairy that act synergistically with calcium to attenuate adiposity. These concepts are confirmed by both epidemiological and clinical data, which demonstrate that increasing dietary calcium results in significant reductions in adipose tissue mass in obese humans in the absence of caloric restriction and markedly accelerates the weight and body fat loss secondary to caloric restriction, whereas dairy products exert significantly greater effects. These data indicate an important role for dairy products in both the prevention and treatment of obesity.
Isoprenoids: Remarkable diversity of form and function
Authors: Holstein Sarah A. , Hohl Raymond J. 
Published: November 2006

AbstractThe isoprenoid biosynthetic pathway is the source of a wide array of products. The pathway has been highly conserved throughout evolution, and isoprenoids are some of the most ancient biomolecules ever identified, playing key roles in many life forms. In this review we focus on C‐10 mono‐, C‐15 sesqui‐, and C‐20 diterpenes. Evidence for interconversion between the pathway intermediates farnesyl pyrophosphate and geranylgeranly pyrophosphate and their respective metabolites is examined. The diverse functions of these molecules are discussed in detail, including their ability to regulate expression of the β‐HMG‐CoA reductase and Ras‐related proteins. Additional topics include the mechanisms underlying the apoptotic effects of select isoprenoids, antiulcer activities, and the disposition and degradation of isoprenoids in the environment. Finally, the significance of pharmacological manipulation of the isoprenoid pathway and clinical correlations are discussed.
An isocaloric PUFA diet enhances lipid uptake and weight gain in aging rats
Authors: Woudstra Trudy D. , Drozdowski Laurie A. , Wild Gary E. , Clandinin M. T. , Agellon Luis B. , Thomson Alan B. R. 
Published: November 2006

AbstractAging is associated with a change in the morphology and absorptive capacity of the small intestine. In young rats, feeding a semisynthetic diet containing saturated FA (SFA) increases nutrient uptake, as compared with an isocaloric diet containing polyunsaturated FA (PUFA). We tested the hypotheses that (i) aging is associated with a decline in lipid absorption in the Fischer 344 rat; (ii) this decline can be corrected by manipulating the fat composition of the diet; and (iii) the age‐and diet‐associated variations in lipid uptake are associated with changes in the ileal lipid‐binding protein (ILBP) or the intestinal or liver FA‐binding proteins (l‐or L‐FABP, respectively) in the cytosol of the enterocyte. In rats fed SFA or PUFA, aging was associated with a decline in the in vitro uptake of stearic acid (18∶0) when expressed on the basis of intestinal or mucosal weight. In contrast, age had no effect on lipid uptake when expressed on the basis of serosal surface area, whereas lipid uptake increased with age when expressed on the basis of mucosal surface area. The age‐associated variations in lipid uptake were not associated with changes in protein abundance and/or expression of ILBP, I‐FABP, or L‐FABP. In 24‐mon‐old rats, when uptake of lipids was expressed on the basis of mucosal surface area, feeding PUFA enhanced lipid uptake and body weight gain as compared with rats fed SFA. Future studies must determine whether the enhanced lipid uptake and body weight gain observed in older animals fed PUFA have any therapeutic benefit.