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Vesicle Migration and Spatial Organization Driven by Flow Line Curvature

Physical Review Letters 2011年第2期106卷 028101-028101页

作者： Giovanni Ghigliotti Abtin Rahimian George Biros Chaouqi Misbah Université Joseph Fourier and CNRS (UMR5588) Laboratoire de Spectrométrie Physique 140 Avenue de la Physique 38402 Saint Martin d’Hères France Georgia Institute of Technology School of Computational Science and Engineering and Department of Biomedical Engineering 1324 Klaus Advanced Computing Building 266 Ferst Drive Atlanta Georgia 30332-0765 USA

Cross-streamline migration of deformable entities is essential in many problems such as industrial particulate flows, DNA sorting, and blood rheology. Using two-dimensional numerical experiments, we have discovered that vesicles suspended in a flow with curved flow lines migrate towards regions of high flowline curvature, which are regions of high shear rates. The migration velocity of a vesicle is found to be a universal function of the normal stress difference and the flow curvature. This finding quantitatively demonstrates a direct coupling between a microscopic quantity (migration) and a macroscopic one (normal stress difference). Furthermore, simulations with multiple vesicles revealed a self-organization, which corresponds to segregation, in a rim closer to the inner cylinder, resulting from a subtle interaction among vesicles. Such segregation effects could have a significant impact on the rheology of vesicle flows.

关键词： Shear flow

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Fast active-set-type algorithms for L1-regularized linear regression

Fast active-set-type algorithms for L1-regularized linear re...

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13th International Conference on Artificial Intelligence and Statistics, AISTATS 2010

作者： Kim, Jingu Park, Haesun School of Computational Science and Engineering College of Computing Georgia Institute of Technology United States

In this paper, we investigate new active-settype methods for l 1-regularized linear regression that overcome some difficulties of existing active set methods. By showing a relationship between l 1-regularized linear regression and the linear complementarity problem with bounds, we present a fast active-set-type method, called block principal pivoting. This method accelerates computation by allowing exchanges of several variables among working sets. We further provide an improvement of this method, discuss its properties, and also explain a connection to the structure learning of Gaussian graphical models. Experimental comparisons on synthetic and real data sets show that the proposed method is significantly faster than existing active set methods and competitive against recently developed iterative methods.

关键词： Linear regression

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iVisClassifier: An interactive visual analytics system for classification based on supervised dimension reduction

iVisClassifier: An interactive visual analytics system for c...

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1st IEEE Conference on Visual Analytics science and technology, VAST 10

作者： Choo, Jaegul Lee, Hanseung Kihm, Jaeyeon Park, Haesun School of Computational Science and Engineering Georgia Institute of Technology United States School of Electrical and Computer Engineering Georgia Institute of Technology United States School of Interactive Computing Georgia Institute of Technology United States

ISBN: (纸本)9781424494866

We present an interactive visual analytics system for classification, iVisClassifier, based on a supervised dimension reduction method, linear discriminant analysis (LDA). Given high-dimensional data and associated cluster labels, LDA gives their reduced dimensional representation, which provides a good overview about the cluster structure. Instead of a single two- or three-dimensional scatter plot, iVisClassifier fully interacts with all the reduced dimensions obtained by LDA through parallel coordinates and a scatter plot. Furthermore, it significantly improves the interactivity and interpretability of LDA. LDA enables users to understand each of the reduced dimensions and how they influence the data by reconstructing the basis vector into the original data domain. By using heat maps, iVisClassifier gives an overview about the cluster relationship in terms of pairwise distances between cluster centroids both in the original space and in the reduced dimensional space. Equipped with these functionalities, iVisClassifier supports users' classification tasks in an efficient way. Using several facial image data, we show how the above analysis is performed. ©2010 IEEE.

关键词： Clustering algorithms

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Skel: Generative software for producing skeletal I/O applications

Skel: Generative software for producing skeletal I/O applica...

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7th IEEE International Conference on e-science Workshops, escienceW 201

作者： Logan, Jeremy Klasky, Scott Lofstead, Jay Abbasi, Hasan Ethier, Stéphane Grout, Ray Ku, Seung-Hoe Liu, Qing Ma, Xiaosong Parashar, Manish Podhorszki, Norbert Schwan, Karsten Wolf, Matthew Oak Ridge National Laboratory Oak Ridge TN United States Sandia National Laboratories Albuquerque NM United States National Institute for Computational Sciences University of Tennessee Oak Ridge TN United States Department of Electrical and Computer Engineering Rutgers the State University of New Jersey Piscataway NJ United States Courant Institute of Mathematical Sciences New York University New York NY United States Department of Computer Science North Carolina State University Raleigh NC United States Plasma Physics Laboratory Princeton University Princeton NJ United States National Renewable Energy Laboratory Golden CO United States College of Computing Georgia Tech. Atlanta GA United States

ISBN: (纸本)9780769545981

Massively parallel computations consist of a mixture of computation, communication, and I/O. Of these three components, implementing an effective parallel I/O solution has often been overlooked by application scientists and has typically been added to large scale simulations only when existing serial techniques have failed. As scientists' teams scaled their codes to run on hundreds of processors, it was common to call on an I/O expert to implement a set of more scalable I/O routines. These routines were easily separated from the calculations and communication, and in many cases, an I/O kernel was derived from the application which could be used for testing I/O performance independent of the application. These I/O kernels developed a life of their own used as a broad measure for comparing different I/O techniques. Unfortunately, as years passed and computation and communication changes required changes to the I/O, the separate I/O kernel used for benchmarking remained static, no longer providing an accurate indicator of the I/O performance of the simulation, and making I/O research less relevant for the application scientists. In this paper we describe a new approach to this problem where I/O kernels are replaced with skeletal I/O applications that are automatically generated from an abstract set of simulation I/O parameters. We realize this abstraction by leveraging the ADIOS [1] middleware's XML I/O specification with additional runtime parameters. Skeletal applications offer all of the benefits of I/O kernels including allowing I/O optimizations to focus on useful I/O patterns. Moreover, since they are automatically generated, it is easy to produce an updated I/O skeleton whenever the simulation's I/O changes. In this paper we analyze the performance of automatically generated I/O skeletal applications for the S3D and GTS codes. We show that these skeletal applications achieve performance comparable to that of the production applications. We wrap up the paper with

关键词： Benchmarking

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Distance-based multiple paths quantization of vocabulary tree for object and scene retrieval

Distance-based multiple paths quantization of vocabulary tre...

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作者： Yang, Heng Wang, Qing Do, Ellen Yi-Luen School of Computer Science and Engineering Northwestern Polytechnical University China College of Computing Georgia Institute of Technology United States

The state of the art in image retrieval on large scale databases is achieved by the work inspired by the text retrieval approaches. A key step of these methods is the quantization stage which maps the high-dimensional feature vectors to discriminatory visual words. This paper mainly proposes a distance-based multiple paths quantization (DMPQ) algorithm to reduce the quantization loss of the vocabulary tree based methods. In addition, a more efficient way to build a vocabulary tree is presented by using sub-vectors of features. The algorithm is evaluated on both the benchmark object recognition and the location recognition databases. The experimental results have demonstrated that the proposed algorithm can effectively improve image retrieval performance of the vocabulary tree based methods on both the databases. © 2010 Information Processing Society of Japan.

关键词： Image retrieval

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On processing location based top-k queries in the wireless broadcasting system 10

On processing location based top-k queries in the wireless b...

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25th Annual ACM Symposium on Applied computing, SAC 2010

作者： Jung, HaRim Cho, ByungKu Chung, Yon Dohn Liu, Ling Department of Computer Science and Engineering Korea University Seoul Korea Republic of College of Computing Georgia Institute of Technology United States

ISBN: (纸本)9781605586380

In this paper, we explore the problem of processing a novel type of location based queries, named the location based top-k query, which involves both of spatial and non-spatial specifications for data objects in the wireless broadcasting system. We introduce two methods for processing location based top-k queries on the broadcast stream. In the first method, the search algorithm runs on the broadcast aggregate R-tree (aR-tree). However, the aR-tree may deteriorate the search performance, especially in terms of the tuning time. With this problem in mind, we propose a novel index structure, called the bit-vector R-tree (bR-tree), which stores additional bit-vector information to facilitate processing of location based top-k queries. The search algorithm on the broadcast bR-tree is also described. Our simulation experiments demonstrate that the bR-tree method clearly outperforms the aR-tree method in terms of the tuning time, while maintaining similar or better performance in terms of the access time. © 2010 ACM.

关键词： Location based services

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Port-bonded zone collaboration information system based on SOA

Port-bonded zone collaboration information system based on S...

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International Conference on Mechatronics and Automation

作者： Xu, Hongxia Du, Yanhua Xiong, Pengcheng Logistics Engineering Department University of Science and Technology Beijing Beijing 100083 China College of Computing Georgia Institute of Technology Atlanta GA 30332 United States

ISBN: (纸本)9781424451418

Port-Bonded Zone Collaboration (PBZC) plays a significant role in international trade and logistics, it is the prelude toward Free Trade Zone as being widely operated abroad. With diverse heterogeneous application systems concerned, PBZC information system runs with low interoperability and interactivity. Recently, SOA has evolved to become a promising technology for seamless integration of heterogeneous systems, which can enhance reuse possibilities to a variety of legacy systems. It can be exactly applied as an efficient solution on PBZC information system. In this paper, firstly we propose a brief introduction for the business patterns of PBZC and diverse systems concerned;Secondly an integrated framework of PBZC information system based on SOA is presented, and the functions for each layer is discussed in details;Thirdly, the web service encapsulation of diverse systems involving PBZC is illustrated;In the end, we validate the framework and approach through a real-life case. © 2010 IEEE.

关键词： Information systems

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The social honeypot project: Protecting online communities from spammers 10

The social honeypot project: Protecting online communities f...

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19th International World Wide Web Conference, WWW2010

作者： Lee, Kyumin Caverlee, James Webb, Steve Department of Computer Science and Engineering Texas A and M University College Station TX United States College of Computing Georgia Institute of Technology Atlanta GA United States

ISBN: (纸本)9781605587998

We present the conceptual framework of the Social Honeypot Project for uncovering social spammers who target online communities and initial empirical results from Twitter and MySpace. Two of the key components of the Social Honeypot Project are: (1) The deployment of social honeypots for harvesting deceptive spam profiles from social networking communities;and (2) Statistical analysis of the properties of these spam profiles for creating spam classifiers to actively filter out existing and new spammers. © 2010 Copyright is held by the author/owner(s).

关键词： Social networking (online)

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Uncovering social spammers: Social honeypots + machine learning

Uncovering social spammers: Social honeypots + machine learn...

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33rd Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, SIGIR 2010

ISBN: (纸本)9781605588964

Web-based social systems enable new community-based opportunities for participants to engage, share, and interact. This community value and related services like search and advertising are threatened by spammers, content polluters, and malware disseminators. In an effort to preserve community value and ensure long-term success, we propose and evaluate a honeypot-based approach for uncovering social spammers in online social systems. Two of the key components of the proposed approach are: (1) The deployment of social honeypots for harvesting deceptive spam profiles from social networking communities;and (2) Statistical analysis of the properties of these spam profiles for creating spam classifiers to actively filter out existing and new spammers. We describe the conceptual framework and design considerations of the proposed approach, and we present concrete observations from the deployment of social honeypots in MySpace and Twitter. We find that the deployed social honeypots identify social spammers with low false positive rates and that the harvested spam data contains signals that are strongly correlated with observable profile features (e.g., content, friend information, posting patterns, etc.). Based on these profile features, we develop machine learning based classifiers for identifying previously unknown spammers with high precision and a low rate of false positives. © 2010 ACM.

关键词： Malware

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Fast facial fitting based on mixture appearance model with 3D constraint

Fast facial fitting based on mixture appearance model with 3...

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Chinese Conference on Pattern Recognition

作者： Huang, Xiangsheng Gong, Lujin Wang, Xiaoyan Institute of Automation Chinese Academy of Sciences Beijing 100190 China State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing AMSS Beijing 100190 China College of Computer Science and Technology Zhejiang University of Technology Hangzhou 310023 China

ISBN: (纸本)9781424472109

Fast facial points fitting plays an important role in applications such as Human-Computer Interaction, entertainment, surveillance, and is highly relevant to the techniques of facial expression analysis, face recognition, 3D face model generation, etc. Active Appearance Models (AAMs) are generative models commonly used to fit face. They are sensitive to illumination and expression changes because they use only raw intensity to build observation models. In this paper, a real time facial points fitting approach using mixture observation models is presented. Furthermore, the 3D modes are used to constrain the AAM so that it can only generate model instances that can also be generated with the 3D modes. Finally, we give a derivative process for fast energy minimization using the inverse compositional algorithm. A coarse-to-fine fitting strategy is used for realtime and robust facial points fitting. We apply this algorithm to facial expression cloning of 3D Avatar system. Experimental results demonstrate that fitting the AAM with mixture observation models and 3D constraint outperforms other classical algorithms. ©2010 IEEE.

关键词： Mixtures

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