61,229 research outputs found
Palgol: A High-Level DSL for Vertex-Centric Graph Processing with Remote Data Access
Pregel is a popular distributed computing model for dealing with large-scale
graphs. However, it can be tricky to implement graph algorithms correctly and
efficiently in Pregel's vertex-centric model, especially when the algorithm has
multiple computation stages, complicated data dependencies, or even
communication over dynamic internal data structures. Some domain-specific
languages (DSLs) have been proposed to provide more intuitive ways to implement
graph algorithms, but due to the lack of support for remote access --- reading
or writing attributes of other vertices through references --- they cannot
handle the above mentioned dynamic communication, causing a class of Pregel
algorithms with fast convergence impossible to implement.
To address this problem, we design and implement Palgol, a more declarative
and powerful DSL which supports remote access. In particular, programmers can
use a more declarative syntax called chain access to naturally specify dynamic
communication as if directly reading data on arbitrary remote vertices. By
analyzing the logic patterns of chain access, we provide a novel algorithm for
compiling Palgol programs to efficient Pregel code. We demonstrate the power of
Palgol by using it to implement several practical Pregel algorithms, and the
evaluation result shows that the efficiency of Palgol is comparable with that
of hand-written code.Comment: 12 pages, 10 figures, extended version of APLAS 2017 pape
Density matrix renormalization group study of conjugated polymers with transverse pi-conjugation
We report accurate numerical studies of excited state orderings in long
hypothetical pi-conjugated oligomers in which the hydrogen atoms of
trans-polyacetylene are replaced with conjugated sidegroups, within modified
Hubbard models. There exists a range of the bare Coulomb repulsion for which
the excited state ordering is conducive to photoluminescence in the substituted
systems, even as this ordering is opposite in the unsubstituted polyenes of the
same lengths. Our work provides motivation to study real pi-conjugated polymers
with transverse conjugation and small optical gaps.Comment: 5 pages, 4 fig
Human gait recognition with matrix representation
Human gait is an important biometric feature. It can be perceived from a great distance and has recently attracted greater attention in video-surveillance-related applications, such as closed-circuit television. We explore gait recognition based on a matrix representation in this paper. First, binary silhouettes over one gait cycle are averaged. As a result, each gait video sequence, containing a number of gait cycles, is represented by a series of gray-level averaged images. Then, a matrix-based unsupervised algorithm, namely coupled subspace analysis (CSA), is employed as a preprocessing step to remove noise and retain the most representative information. Finally, a supervised algorithm, namely discriminant analysis with tensor representation, is applied to further improve classification ability. This matrix-based scheme demonstrates a much better gait recognition performance than state-of-the-art algorithms on the standard USF HumanID Gait database
A multi-agent based evolutionary algorithm in non-stationary environments
This article is posted here with permission of IEEE - Copyright @ 2008 IEEEIn this paper, a multi-agent based evolutionary algorithm (MAEA) is introduced to solve dynamic optimization problems. The agents simulate living organism features and co-evolve to find optimum. All agents live in a lattice like environment, where each agent is fixed on a lattice point. In order to increase the energy, agents can compete with their neighbors and can also acquire knowledge based on statistic information. In order to maintain the diversity of the population, the random immigrants and adaptive primal dual mapping schemes are used. Simulation experiments on a set of dynamic benchmark problems show that MAEA can obtain a better performance in non-stationary environments in comparison with several peer genetic algorithms.This work was suported by the Key Program of National Natural Science Foundation of China under Grant No. 70431003, the Science Fund for Creative Research Group of the National Natural Science Foundation of China under Grant No. 60521003, the National Science and Technology Support Plan of China under Grant No. 2006BAH02A09, and the Engineering and Physical Sciences Research Council of the United Kingdom under Grant No. EP/E060722/1
Anisotropic Flow and Viscous Hydrodynamics
We report part of our recent work on viscous hydrodynamics with consistent
phase space distribution f(x,\p) for freeze out. We develop the gradient
expansion formalism based on kinetic theory, and with the constraints from the
comparison between hydrodynamics and kinetic theory, viscous corrections to
f(x,\p) can be consistently determined order by order. Then with the obtained
f(x,\p), second order viscous hydrodynamical calculations are carried out for
elliptic flow .Comment: 8 pages, 2 figures. Proceedings for the 28th Winter Workshop on
Nuclear Dynamics, Dorado Del Mar, Puerto Rico, United States Of America, 7 -
14 Apr 201
Palmatine inhibits TRIF-dependent NF-kB pathway against inflammation induced by LPS in goat endometrial epithelial cells
A novel approach to modelling and simulating the contact behaviour between a human hand model and a deformable object
A deeper understanding of biomechanical behaviour of human hands becomes fundamental for any human hand-operated Q2 activities. The integration of biomechanical knowledge of human hands into product design process starts to play an increasingly important role in developing an ergonomic product-to-user interface for products and systems requiring high level of comfortable and responsive interactions. Generation of such precise and dynamic models can provide scientific evaluation tools to support product and system development through simulation. This type of support is urgently required in many applications such as hand skill training for surgical operations, ergonomic study of a product or system developed and so forth. The aim of this work is to study the contact behaviour between the operators’ hand and a hand-held tool or other similar contacts, by developing a novel and precise nonlinear 3D finite element model of the hand and by investigating the contact behaviour through simulation. The contact behaviour is externalised by solving the problem using the bi-potential method. The human body’s biomechanical characteristics, such as hand deformity and structural behaviour, have been fully modelled by implementing anisotropic hyperelastic laws. A case study is given to illustrate the effectiveness of the approac
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