6,551 research outputs found
Spectral theorem for the Lindblad equation for quadratic open fermionic systems
The spectral theorem is proven for the quantum dynamics of quadratic open
systems of n fermions described by the Lindblad equation. Invariant eigenspaces
of the many-body Liouvillean dynamics and their largest Jordan blocks are
explicitly constructed for all eigenvalues. For eigenvalue zero we describe an
algebraic procedure for constructing (possibly higher dimensional) spaces of
(degenerate) non-equilibrium steady states.Comment: 19 pages, no figure
Design study of a novel regenerative pump using experimental and numerical techniques
This paper presents a numerical and experimental analysis of a new regenerative pump design. The complex flow-field within regenerative pumps represents a significant challenge to previous published mathematical models. The new pump design incorporates a new axial inlet and outlet port. The experimental and numerical results demonstrate that it is not only possible to resolve the flowfield for this pump type but also demonstrates this pump as a viable alternative to other kinetic rotodynamic machines. The use of the latest rapid manufacturing techniques have enabled the production of the complex geometry of the axial ports required for the new configuration
On Some Positivity Properties of the Interquark Potential in QCD
We prove that the Fourier transform of the exponential e^{-\b V(R)} of the
{\bf static} interquark potential in QCD is positive. It has been shown by
Eliott Lieb some time ago that this property allows in the same limit of static
spin independent potential proving certain mass relation between baryons with
different quark flavors.Comment: 6 pages, latex with one postscript figur
A second eigenvalue bound for the Dirichlet Schroedinger operator
Let be the th eigenvalue of the Schr\"odinger
operator with Dirichlet boundary conditions on a bounded domain and with the positive potential . Following the spirit of the
Payne-P\'olya-Weinberger conjecture and under some convexity assumptions on the
spherically rearranged potential , we prove that . Here denotes the ball, centered at the
origin, that satisfies the condition .
Further we prove under the same convexity assumptions on a spherically
symmetric potential , that decreases
when the radius of the ball increases.
We conclude with several results about the first two eigenvalues of the
Laplace operator with respect to a measure of Gaussian or inverted Gaussian
density
\u3cem\u3eSWANCC\u3c/em\u3e\u27s Clear Statement: A Delimitation of Congress\u27s Commerce Clause Authority to Regulate Water Pollution
Perhaps the most controversial aspect of federal water pollution law is wetland regulation. Wetlands are typically marshy or swampy areas with hydrologic soils and vegetation. Their ecological value is widely recognized, but wetlands often stand in the way of lucrative commercial development projects. Thus, the battle over the validity of federal wetland regulation is a classic fight between environmentalists and industry. The wetlands controversy is also paradigmatic of the perpetual struggle to define the constitutional limits to federal regulation. The country\u27s main water pollution control law, the Clean Water Act (CWA), purports to regulate all navigable waters, which it defines as waters of the United States. Although wetlands are not themselves navigable, section 404 of the CW A requires obtaining a federal permit from the Army Corps of Engineers ( the Corps ) before discharging dredged or fill material into wetlands. The permit requirement applies to individual property owners and commercial developers alike, and is therefore a significant impediment to development projects that involve wetlands. In addition, critics have always maintained that Congress\u27s regulatory power does not extend to isolated wetlands because they are not navigable. The Federal Government\u27s constitutional authority to regulate water pollution arises from the Interstate Commerce Clause. Historically, Congress\u27s power over waters was tied to the national need to regulate navigation as an aspect of commerce. This authority has come to be known as the navigable waters doctrine and was expanded by Congress early on to serve environmental goals. In fact, Congress\u27s authority under the doctrine to regulate pollution of navigable-in-fact waters - waters that are actually navigable, as distinguished from navigable waters, which has become a term of art - has been well-settled for more than a century. However, the extent to which the federal government can constitutionally regulate waters that are not navigable-in-fact has never been clear, and is controversial to this day
\u3cem\u3eSWANCC\u3c/em\u3e\u27s Clear Statement: A Delimitation of Congress\u27s Commerce Clause Authority to Regulate Water Pollution
Perhaps the most controversial aspect of federal water pollution law is wetland regulation. Wetlands are typically marshy or swampy areas with hydrologic soils and vegetation. Their ecological value is widely recognized, but wetlands often stand in the way of lucrative commercial development projects. Thus, the battle over the validity of federal wetland regulation is a classic fight between environmentalists and industry. The wetlands controversy is also paradigmatic of the perpetual struggle to define the constitutional limits to federal regulation. The country\u27s main water pollution control law, the Clean Water Act (CWA), purports to regulate all navigable waters, which it defines as waters of the United States. Although wetlands are not themselves navigable, section 404 of the CW A requires obtaining a federal permit from the Army Corps of Engineers ( the Corps ) before discharging dredged or fill material into wetlands. The permit requirement applies to individual property owners and commercial developers alike, and is therefore a significant impediment to development projects that involve wetlands. In addition, critics have always maintained that Congress\u27s regulatory power does not extend to isolated wetlands because they are not navigable. The Federal Government\u27s constitutional authority to regulate water pollution arises from the Interstate Commerce Clause. Historically, Congress\u27s power over waters was tied to the national need to regulate navigation as an aspect of commerce. This authority has come to be known as the navigable waters doctrine and was expanded by Congress early on to serve environmental goals. In fact, Congress\u27s authority under the doctrine to regulate pollution of navigable-in-fact waters - waters that are actually navigable, as distinguished from navigable waters, which has become a term of art - has been well-settled for more than a century. However, the extent to which the federal government can constitutionally regulate waters that are not navigable-in-fact has never been clear, and is controversial to this day
Asymptotic Entanglement and Lindblad Dynamics: a Perturbative Approach
We consider an open bipartite quantum system with dissipative Lindblad type
dynamics. In order to study the entanglement of the stationary states, we
develop a perturbative approach and apply it to the physically significant case
when a purely dissipative perturbation is added to the unperturbed generator
which by itself would produce reversible unitary dynamics.Comment: 15 page
Self-supervised automated wrapper generation for weblog data extraction
Data extraction from the web is notoriously hard. Of the types of resources available on the web, weblogs are becoming increasingly important due to the continued growth of the blogosphere, but remain poorly explored. Past approaches to data extraction from weblogs have often involved manual intervention and suffer from low scalability. This paper proposes a fully automated information extraction methodology based on the use of web feeds and processing of HTML. The approach includes a model for generating a wrapper that exploits web feeds for deriving a set of extraction rules automatically. Instead of performing a pairwise comparison between posts, the model matches the values of the web feeds against their corresponding HTML elements retrieved from multiple weblog posts. It adopts a probabilistic approach for deriving a set of rules and automating the process of wrapper generation. An evaluation of the model is conducted on a dataset of 2,393 posts and the results (92% accuracy) show that the proposed technique enables robust extraction of weblog properties and can be applied across the blogosphere for applications such as improved information retrieval and more robust web preservation initiatives
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