339,529 research outputs found
Adiabatic elimination-based coupling control in densely packed subwavelength waveguides.
The ability to control light propagation in photonic integrated circuits is at the foundation of modern light-based communication. However, the inherent crosstalk in densely packed waveguides and the lack of robust control of the coupling are a major roadblock toward ultra-high density photonic integrated circuits. As a result, the diffraction limit is often considered as the lower bound for ultra-dense silicon photonics circuits. Here we experimentally demonstrate an active control of the coupling between two closely packed waveguides via the interaction with a decoupled waveguide. This control scheme is analogous to the adiabatic elimination, a well-known procedure in atomic physics. This approach offers an attractive solution for ultra-dense integrated nanophotonics for light-based communications and integrated quantum computing
The LCG POOL Project, General Overview and Project Structure
The POOL project has been created to implement a common persistency framework
for the LHC Computing Grid (LCG) application area. POOL is tasked to store
experiment data and meta data in the multi Petabyte area in a distributed and
grid enabled way. First production use of new framework is expected for summer
2003. The project follows a hybrid approach combining C++ Object streaming
technology such as ROOT I/O for the bulk data with a transactionally safe
relational database (RDBMS) store such as MySQL. POOL is based a strict
component approach - as laid down in the LCG persistency and blue print RTAG
documents - providing navigational access to distributed data without exposing
details of the particular storage technology. This contribution describes the
project breakdown into work packages, the high level interaction between the
main pool components and summarizes current status and plans.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 5 pages. PSN MOKT00
Development and application of unified algorithms for problems in computational science
A framework is presented for developing computationally unified numerical algorithms for solving nonlinear equations that arise in modeling various problems in mathematical physics. The concept of computational unification is an attempt to encompass efficient solution procedures for computing various nonlinear phenomena that may occur in a given problem. For example, in Computational Fluid Dynamics (CFD), a unified algorithm will be one that allows for solutions to subsonic (elliptic), transonic (mixed elliptic-hyperbolic), and supersonic (hyperbolic) flows for both steady and unsteady problems. The objectives are: development of superior unified algorithms emphasizing accuracy and efficiency aspects; development of codes based on selected algorithms leading to validation; application of mature codes to realistic problems; and extension/application of CFD-based algorithms to problems in other areas of mathematical physics. The ultimate objective is to achieve integration of multidisciplinary technologies to enhance synergism in the design process through computational simulation. Specific unified algorithms for a hierarchy of gas dynamics equations and their applications to two other areas: electromagnetic scattering, and laser-materials interaction accounting for melting
CEDAR: tools for event generator tuning
I describe the work of the CEDAR collaboration in developing tools for tuning
and validating Monte Carlo event generator programs. The core CEDAR task is to
interface the Durham HepData database of experimental measurements to event
generator validation tools such as the UCL JetWeb system - this has
necessitated the migration of HepData to a new relational database system and a
Java-based interaction model. The "number crunching" part of JetWeb is also
being upgraded, from the Fortran HZTool library to the new C++ Rivet system and
a generator interfacing layer named RivetGun. Finally, I describe how Rivet is
already being used as a central part of a new generator tuning system, and
summarise two other CEDAR activities, HepML and HepForge.Comment: 13 pages, prepared for XI International Workshop on Advanced
Computing and Analysis Techniques in Physics Research, Amsterdam, April 23-27
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Computers from plants we never made. Speculations
We discuss possible designs and prototypes of computing systems that could be
based on morphological development of roots, interaction of roots, and analog
electrical computation with plants, and plant-derived electronic components. In
morphological plant processors data are represented by initial configuration of
roots and configurations of sources of attractants and repellents; results of
computation are represented by topology of the roots' network. Computation is
implemented by the roots following gradients of attractants and repellents, as
well as interacting with each other. Problems solvable by plant roots, in
principle, include shortest-path, minimum spanning tree, Voronoi diagram,
-shapes, convex subdivision of concave polygons. Electrical properties
of plants can be modified by loading the plants with functional nanoparticles
or coating parts of plants of conductive polymers. Thus, we are in position to
make living variable resistors, capacitors, operational amplifiers,
multipliers, potentiometers and fixed-function generators. The electrically
modified plants can implement summation, integration with respect to time,
inversion, multiplication, exponentiation, logarithm, division. Mathematical
and engineering problems to be solved can be represented in plant root networks
of resistive or reaction elements. Developments in plant-based computing
architectures will trigger emergence of a unique community of biologists,
electronic engineering and computer scientists working together to produce
living electronic devices which future green computers will be made of.Comment: The chapter will be published in "Inspired by Nature. Computing
inspired by physics, chemistry and biology. Essays presented to Julian Miller
on the occasion of his 60th birthday", Editors: Susan Stepney and Andrew
Adamatzky (Springer, 2017
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