879,777 research outputs found
Process-Oriented Parallel Programming with an Application to Data-Intensive Computing
We introduce process-oriented programming as a natural extension of
object-oriented programming for parallel computing. It is based on the
observation that every class of an object-oriented language can be instantiated
as a process, accessible via a remote pointer. The introduction of process
pointers requires no syntax extension, identifies processes with programming
objects, and enables processes to exchange information simply by executing
remote methods. Process-oriented programming is a high-level language
alternative to multithreading, MPI and many other languages, environments and
tools currently used for parallel computations. It implements natural
object-based parallelism using only minimal syntax extension of existing
languages, such as C++ and Python, and has therefore the potential to lead to
widespread adoption of parallel programming. We implemented a prototype system
for running processes using C++ with MPI and used it to compute a large
three-dimensional Fourier transform on a computer cluster built of commodity
hardware components. Three-dimensional Fourier transform is a prototype of a
data-intensive application with a complex data-access pattern. The
process-oriented code is only a few hundred lines long, and attains very high
data throughput by achieving massive parallelism and maximizing hardware
utilization.Comment: 20 pages, 1 figur
3D Imaging of a Phase Object from a Single Sample Orientation Using an Optical Laser
Ankylography is a new 3D imaging technique, which, under certain
circumstances, enables reconstruction of a 3D object from a single sample
orientation. Here, we provide a matrix rank analysis to explain the principle
of ankylography. We then present an ankylography experiment on a microscale
phase object using an optical laser. Coherent diffraction patterns are acquired
from the phase object using a planar CCD detector and are projected onto a
spherical shell. The 3D structure of the object is directly reconstructed from
the spherical diffraction pattern. This work may potentially open the door to a
new method for 3D imaging of phase objects in the visible light region.
Finally, the extension of ankylography to more complicated and larger objects
is suggested.Comment: 22 pages 5 figure
From Topology to Noncommutative Geometry: -theory
We associate to each unital -algebra a geometric object---a diagram
of topological spaces representing quotient spaces of the noncommutative space
underlying ---meant to serve the role of a generalized Gel'fand spectrum.
After showing that any functor from compact Hausdorff spaces to a suitable
target category can be applied directly to these geometric objects to
automatically yield an extension which acts on all unital
-algebras, we compare a novel formulation of the operator functor to
the extension of the topological -functor.Comment: 14 page
UML-F: A Modeling Language for Object-Oriented Frameworks
The paper presents the essential features of a new member of the UML language
family that supports working with object-oriented frameworks. This UML
extension, called UML-F, allows the explicit representation of framework
variation points. The paper discusses some of the relevant aspects of UML-F,
which is based on standard UML extension mechanisms. A case study shows how it
can be used to assist framework development. A discussion of additional tools
for automating framework implementation and instantiation rounds out the paper.Comment: 22 pages, 10 figure
Cylindrical Wiener processes
In this work cylindrical Wiener processes on Banach spaces are defined by
means of cylindrical stochastic processes, which are a well considered
mathematical object. This approach allows a definition which is a simple
straightforward extension of the real-valued situation. We apply this
definition to introduce a stochastic integral with respect to cylindrical
Wiener processes. Again, this definition is a straightforward extension of the
real-valued situation which results now in simple conditions on the integrand.
In particular, we do not have to put any geometric constraints on the Banach
space under consideration. Finally, we relate this integral to well-known
stochastic integrals in literature
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