AES for multiscale localization modeling in granular media

This work presents a multiscale strong discontinuity approach to tackle key challenges in modeling localization behavior in granular media: accommodation of discontinuities in the kinematic fields, and direct linkage to the underlying grain-scale information. Assumed enhanced strain (AES) concepts are borrowed to enhance elements for post-localization analysis, but are reformulated within a recently-proposed hierarchical multiscale computational framework. Unlike classical AES methods, where material properties are usually constants or assumed to evolve with some arbitrary phenomenological laws, this framework provides a bridge to extract evolutions of key material parameters, such as friction and dilatancy, based on grain scale computational or experimental data. More importantly, the phenomenological softening modulus typically used in AES methods is no longer required. Numerical examples of plane strain compression tests are presented to illustrate the applicability of this method and to analyze its numerical performance.     

Visualization using colour: Visual presentation of events in particle physics

This paper applies a model of colour vision to achieve optimal use of colour in a software system that visualizes the results of experiments in high energy physics. It shows how the elements of the visualization were designed and provides details of why particular colours were chosen. By grounding these findings in psychological research, it is able to show how other computer systems that use colour may profitably apply this methodology.     

Preference dynamics with multimodal user-item interactions in social media recommendation

Recommender systems elicit the interests and preferences of individuals and make recommendations accordingly, a main challenge for expert and intelligent systems. An essential problem in recommender systems is to learn users’ preference dynamics, that is, the constant evolution of the explicit or the implicit information, which is diversified throughout time according to the user actions. Also, in real settings data sparsity degrades the recommendation accuracy. Hence, state-of-the-art methods exploit multimodal information of users-item interactions to reduce sparsity, but they ignore preference dynamics and do not capture users’ most recent preferences. In this article, we present a Temporal Collective Matrix Factorization (TCMF) model, making the following contributions: (i) we capture preference dynamics through a joint decomposition model that extracts the user temporal patterns, and (ii) co-factorize the temporal patterns with multimodal user-item interactions by minimizing a joint objective function to generate the recommendations. We evaluate the performance of TCMF in terms of accuracy and root mean square error, and show that the proposed model significantly outperforms state-of-the-art strategies.     

How media choice affects learner interactions in distance learning classes

In this research we explore aspects of learning, social interaction and community across online learning, also known as distance learning, in higher education. We measure the impact of online social networking (OSN) software versus traditional learning management system (LMS) software. Guided by a theoretical model for how individuals learn and interact within online communities, we measure student perceptions of learning, social interaction and course community before and after our interventions. Survey instruments measure perceived learning, social interaction and community, which we further explore using social network analysis (SNA). Survey results identified that students experienced higher levels of perceived social interaction and course community and, overall, had higher levels of satisfaction with OSN software than those using LMS software. Along this line, SNA results corroborated that OSN software yielded a higher number of interactions, providing a more engaging learning experience.     

Visualizing particle/flow structure interactions in the small bronchial tubes

Particle deposition in the small bronchial tubes (generations six through twelve) is strongly influenced by the vortex-dominated secondary flows that are induced by axial curvature of the tubes. In this paper, we employ particle destination maps in conjunction with two-dimensional, finite-time Lyapunov exponent maps to illustrate how the trajectories of finite-mass particles are influenced by the presence of vortices. We consider two three-generation bronchial tube models: a planar, asymmetric geometry and a non-planar, asymmetric geometry. Our visualizations demonstrate that these techniques, coupled with judiciously seeded particle trajectories, are effective tools for studying particle/flow structure interactions.     

Situated interactions between audiovisual media and African herbal lore

We describe a rural African community’s interactions in recording and interpreting video on herb lore in our endeavours to design digital systems that extend sharing knowledge in a system of traditional medicine (TM). Designing for such a system involves reflecting on own narratives about medicine and media and recognising that narratives reflect “cultural logics” and media transforms narratives. We used video as sites to explore meaning-making in herb lore; anchor our dialogic with, and about users; and, elicit design ideas. Participants’ prioritise speech, gesture and bodily interaction, above other visual context. Further, recordings can embody nuances in social relations and depict temporal patterns that are integral to TM pedagogy. However, such embodiments and depictions are disrupted by affordances of, and associations with, media; our abstraction; and, non-local ontologies (such as chronologic or geographic point-based representation). Our insights produce new design patterns by orienting us towards representing herb lore within the social-relational spaces that contextualise knowing, doing and moving, linked to corporeal and felt-experiences. More generally, uncovering transformations when media and narrative interact can improve analysis and designing for logics and literacies that profoundly differ from those typifying ubicomp.     

Parallel Newton-Krylov-Schwarz algorithms for the three-dimensional Poisson-Boltzmann equation in numerical simulation of colloidal particle interactions

We investigate fully parallel Newton-Krylov-Schwarz (NKS) algorithms for solving the large sparse nonlinear systems of equations arising from the finite element discretization of the three-dimensional Poisson-Boltzmann equation (PBE), which is often used to describe the colloidal phenomena of an electric double layer around charged objects in colloidal and interfacial science. The NKS algorithm employs an inexact Newton method with backtracking (INB) as the nonlinear solver in conjunction with a Krylov subspace method as the linear solver for the corresponding Jacobian system. An overlapping Schwarz method as a preconditioner to accelerate the convergence of the linear solver. Two test cases including two isolated charged particles and two colloidal particles in a cylindrical pore are used as benchmark problems to validate the correctness of our parallel NKS-based PBE solver. In addition, a truly three-dimensional case, which models the interaction between two charged spherical particles within a rough charged micro-capillary, is simulated to demonstrate the applicability of our PBE solver to handle a problem with complex geometry. Finally, based on the result obtained from a PC cluster of parallel machines, we show numerically that NKS is quite suitable for the numerical simulation of interaction between colloidal particles, since NKS is robust in the sense that INB is able to converge within a small number of iterations regardless of the geometry, the mesh size, the number of processors. With help of an additive preconditioned Krylov subspace method NKS achieves parallel efficiency of 71% or better on up to a hundred processors for a 3D problem with 5 million unknowns.     

生物信息学中基因数据可视化

科学可视化技术是进行生物数据挖掘的重要手段。本文综合介绍了主要的基因数据可视化技术：各种基因调控网、层次树显示、信息壁技术、语义镜。     

生物信息学中基因数据可视化

科学可视化技术是进行生物数据挖掘的重要手段。本文综合介绍了主要的基因数据可视化技术 :各种基因调控网、层次树显示、信息壁技术、语义镜     

Parallel Godunov smoothed particle hydrodynamics (SPH) with improved treatment of Boundary Conditions and an application to granular flows

Smoothed Particle Hydrodynamics has been successfully used for various fluid-dynamics problems, such as breaking-waves, flooding etc., since it was originally proposed. While the Lagrangian approach is naturally suitable for free-surface flows, enforcing boundary conditions and poor approximations in the presence of discontinuities in the solution are major difficulties with the method. In this paper we present an enhanced conservative Godunov SPH based on the work of Inutsuka [S. Inutsuka, Reformulation of smoothed particle hydrodynamics with Riemann solver, Journal of Computational Physics 179 (2002) 238–267] that accurately resolves discontinuities without the need to use artificial viscosity, preserves partition of unity everywhere in the domain, correctly and flexibly enforces necessary essential and frictional slip boundary conditions to approximately solve free-surface granular flows. The development is motivated by the need to improve upon depth averaged grid based models of large scale debris flows and avalanches often characterized as granular flows. Simple validation of the results is obtained by comparison to table-top experiments.     

Visualization in biomedical computing

Visualizable objects in biology and medicine extend across a vast range of scale, from individual molecules and cells, to the varieties of tissue and interstitial interfaces, to complete organs, organ systems and body parts, and include functional attributes of these systems, such as biophysical, biomechanical and physiological properties. Medical applications include accurate anatomy and function mapping, enhanced diagnosis, accurate treatment planning and rehearsal, and education/training. However, the greatest potential for revolutionary innovation in the practice of medicine lies in direct, fully immersive, real-time multisensory fusion of real and virtual information data streams into online, real-time visualizations available during an actual clinical procedure. Current high-performance computers and advanced image processing capabilities have facilitated major progress toward realization of this goal. With these advances in hand, there are several important applications possible to be delivered soon that will have a significant impact on the practice of medicine and on biological research.     

Visualization in process control

The problem of analytical assessment of visualization is separated into a problem of information mapping and a problem of cognitive and perceptual support. These problems are analyzed and discussed in this article. It is argued that presentational modalities (i.e., semantic invariants) must be identified to be able to construct a taxonomy of graphical displays and their potential to visualize certain types of information. The problem of assessing displays analytically is illustrated by two new displays developed for a water treatment plant. In these displays, one graphical type is embedded into another. Common graphical modalities are identified from displays used in the process industry in general. © 1999 John Wiley & Sons, Inc.     

Analysis of particle interaction in particle swarm optimization

In this paper, we analyze the behavior of particle swarm optimization (PSO) on the facet of particle interaction. We firstly propose a statistical interpretation of particle swarm optimization in order to capture the stochastic behavior of the entire swarm. Based on the statistical interpretation, we investigate the effect of particle interaction by focusing on the social-only model and derive the upper and lower bounds of the expected particle norm. Accordingly, the lower and upper bounds of the expected progress rate on the sphere function are also obtained. Furthermore, the sufficient and necessary condition for the swarm to converge is derived to demonstrate the PSO convergence caused by the effect of particle interaction.     

Visualization in teleimmersive environments

In collaborative virtual reality (VR), the goal is to reproduce a face-to-face meeting in minute detail. Teleimmersion moves beyond this idea, integrating collaborative VR with audio- and video-conferencing that may involve data mining and heavy computation. In teleimmersion, collaborators at remote sites share the details of a virtual world that can autonomously control computation, query databases and gather results. They don't meet in a room to discuss a car engine; they meet in the engine itself. The University of Illinois at Chicago's Electronic Visualization Laboratory (EVL) has hosted several applications that demonstrate rudimentary teleimmersion. All users are members of Cavern (CAVE Research Network) [] $a collection of participating industrial and research institutions equipped with CAVE (Cave Automated Virtual Environment), ImmersaDesk VR systems and high-performance computing resources, including high-speed networks. There are more than 100 CAVE and ImmersaDesk installations worldwide. The pressing challenge now is how to support collaborative work among Cavern users without having them worry about the details of sustaining a collaboration. Another problem is providing both synchronous and asynchronous collaboration. The authors detail how they've built new display devices to serve as more convenient teleimmersion end-points and to support their international networking infrastructure with sufficient bandwidth to support the needs of teleimmersive applications     

科学计算可视化

科学计算可视化(V_isc)是正在兴起的崭新技术领域。V_isc把数据信息转换成可视信息,是分析与解释大体积数据的有力工具。本文阐述了V_isc技术的若干重要方面,指出研制可视化应用开发环境VadE的主要目标,即与学科无关性和可视驾驭计算功能。     

The Visualization Input Pipeline - Enabling Semantic Interaction in Scientific Visualization

Scientific Visualization systems are primarily output-oriented, Users can specify and change parameters that are controlling the visualization process, which will result in different data representations or images respectively. But no mechanism is provided to really interact with the application data (semantic interaction) that has been changed step by step by the process of visualization. In this paper general concepts are elaborated and presented to achieve semantic interaction in dataflow environments for Scientific Visualization.     

Coupling of rigid body dynamics and moving particle semi-implicit method for simulating isothermal multi-phase fluid interactions

The moving particle semi-implicit (MPS) method does not require grids for simulating fluid motions. Therefore, the MPS method can easily handle a large deformation of fluid. However, the MPS method has some difficulties in simulating transfer of momentum caused by a physical collision between different fluids because fluid particles have no mass or volume and only have weights for interacting with other particles. To overcome this inherent defect of the MPS method, rigid body dynamics is explicitly coupled with the MPS method in this study. In the first step, the MPS calculation is performed with particles which are considered to have no mass or volume. In the second step, rigid body dynamics comes into the calculation and considers the particles to have a slightly lesser diameter than the initial distance between particles. Then, physical contacts between particles are simulated with the dynamic energy conserved while the incompressibility of fluids is effectively maintained. In the single fluid region, the coupled method deals with the behavior of the particles. For the interface of the different fluids, only rigid body dynamics is used to simulate the transfer of the momentum caused by physical collisions of fluids. Through this coupling of rigid body dynamics and the MPS method, the overall stability related with the incompressibility of a fluid is comparatively increased in the single-phase fluid simulation. For the calculation of the multi-phase fluids behavior, fluids interactions can be easily treated with improving stability of the MPS calculation. In this study, collapse of water column and the isothermal fuel–coolant interaction (FCI), in which a water jet is directed into a denser fluid pool, were simulated to validate the coupling method of the MPS method and rigid body dynamics.     

Visualization of fluid mixing in microchannels

The development of a microchannel for fluid-mixing applications comes from the recent interest in microfluidic device applications in biology. Microfluidics refers to fluid flow and transport phenomena associated with these devices. The basic idea of developing microfluidic devices is to shrink the physical dimensions of most commonly used processors - that is, using miniaturization and function integration to create the so-called lab on a chip. The development of microfabrication procedures and the associated fundamental theories requires computer analysis and simulation techniques. Computer modeling not only reduces the experiment costs - such as data acquisition devices and control - but also expedites a certain design concept's evaluation process. More importantly, computer modeling results will help gain a better understanding of the flow field through flow visualization, and the information drawn from the results of computer simulations will in turn improve the design. This is especially important during the conceptual design phase.     

可视化设计中的色彩应用

在可视化设计中,使用色彩对数据编码是十分常见且重要的方法.色彩的合理使用可以使可视化更加准确、高效地传达信息;色彩的属性与用户个体的差异共同作用,决定用户感知到的色彩.文中从可视化设计的美学出发,讨论了突显性、差异性、可读性等色彩特点,以及色彩使用数量、色彩与记忆的关系等,并分析了视觉缺陷对色彩感知的影响,阐述了可视化中有关色彩的基本理论与使用原则.