20,452 research outputs found
Introduction to Library Trends 55 (3) Winter 2007: Libraries in Times of War, Revolution and Social Change
published or submitted for publicatio
Review of Bring on the books for everybody: how literary culture became popular culture by Jim Collins [2010]
Impact of pressure dissipation on fluid injection into layered aquifers
Carbon dioxide (CO2) capture and subsurface storage is one method for
reducing anthropogenic CO2 emissions to mitigate climate change. It is well
known that large-scale fluid injection into the subsurface leads to a buildup
in pressure that gradually spreads and dissipates through lateral and vertical
migration of water. This dissipation can have an important feedback on the
shape of the CO2 plume during injection, and the impact of vertical pressure
dissipation, in particular, remains poorly understood. Here, we investigate the
impact of lateral and vertical pressure dissipation on the injection of CO2
into a layered aquifer system. We develop a compressible, two-phase model that
couples pressure dissipation to the propagation of a CO2 gravity current. We
show that our vertically integrated, sharp-interface model is capable of
efficiently and accurately capturing water migration in a layered aquifer
system with an arbitrary number of aquifers. We identify two limiting cases ---
`no leakage' and `strong leakage' --- in which we derive analytical expressions
for the water pressure field for the corresponding single-phase injection
problem. We demonstrate that pressure dissipation acts to suppress the
formation of an advancing CO2 tongue during injection, resulting in a plume
with a reduced lateral extent. The properties of the seals and the number of
aquifers determine the strength of pressure dissipation and subsequent coupling
with the CO2 plume. The impact of pressure dissipation on the shape of the CO2
plume is likely to be important for storage efficiency and security
Rethinking Sanitation: Lessons and Innovation for Sustainability and Success in the New Millennium
human development, water, sanitation
An optimal factor analysis approach to improve the wavelet-based image resolution enhancement techniques
The existing wavelet-based image resolution enhancement techniques have many assumptions, such as limitation of the way to generate low-resolution images and the selection of wavelet functions, which limits their applications in different fields. This paper initially identifies the factors that effectively affect the performance of these techniques and quantitatively evaluates the impact of the existing assumptions. An approach called Optimal Factor Analysis employing the genetic algorithm is then introduced to increase the applicability and fidelity of the existing methods. Moreover, a new Figure of Merit is proposed to assist the selection of parameters and better measure the overall performance. The experimental results show that the proposed approach improves the performance of the selected image resolution enhancement methods and has potential to be extended to other methods
Decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation
We study the decuplet baryon magnetic moments in a QCD-based quark model
beyond quenched approximation. Our approach for unquenching the theory is based
on the heavy baryon perturbation theory in which the axial couplings for baryon
- meson and the meson-meson-photon couplings from the chiral perturbation
theory are used together with the QM moment couplings. It also involves the
introduction of a form factor characterizing the structure of baryons
considered as composite particles. Using the parameters obtained from fitting
the octet baryon magnetic moments, we predict the decuplet baryon magnetic
moments. The magnetic moment is found to be in good agreement with
experiment: is predicted to be compared to the
experimental result of (2.02 0.05) .Comment: 19 pages, 2 figure
Quality-based Multimodal Classification Using Tree-Structured Sparsity
Recent studies have demonstrated advantages of information fusion based on
sparsity models for multimodal classification. Among several sparsity models,
tree-structured sparsity provides a flexible framework for extraction of
cross-correlated information from different sources and for enforcing group
sparsity at multiple granularities. However, the existing algorithm only solves
an approximated version of the cost functional and the resulting solution is
not necessarily sparse at group levels. This paper reformulates the
tree-structured sparse model for multimodal classification task. An accelerated
proximal algorithm is proposed to solve the optimization problem, which is an
efficient tool for feature-level fusion among either homogeneous or
heterogeneous sources of information. In addition, a (fuzzy-set-theoretic)
possibilistic scheme is proposed to weight the available modalities, based on
their respective reliability, in a joint optimization problem for finding the
sparsity codes. This approach provides a general framework for quality-based
fusion that offers added robustness to several sparsity-based multimodal
classification algorithms. To demonstrate their efficacy, the proposed methods
are evaluated on three different applications - multiview face recognition,
multimodal face recognition, and target classification.Comment: To Appear in 2014 IEEE Conference on Computer Vision and Pattern
Recognition (CVPR 2014
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