June 2013
Issue 55
Atmospheric
Aerosols Meeting (reminder)
The
Optical Characterization of Atmospheric Aerosols workshop will take place at
the Congress Centre Smolenice SAS, Slovak Republic in
November 5-7 2013.
The
main goal of the workshop is to present an opportunity for scientists in
different fields to meet and form efficient collaborations in the research of
atmospheric aerosols, including aerosol characterization, remote sensing,
instrumentation, and optical modeling. Abstract submission due is June 30, 2013.
Meeting
website is http://www.ocaa2013.sav.sk/
ADDA
new version (1.2) has been released
Below the most important changes in this release are
summarized. For a more detailed list please see
http://code.google.com/p/a-dda/wiki/ReleaseNotes
.
* Sparse mode is now fully integrated into ADDA and
significantly improved. It is designed for very porous particles.
* Linked to new OpenCL FFT
library from AMD, it is now the default one in OpenCL
mode. Speed improvement is a few times depending on the GPU.
* New iterative solver BCGS2 - an improved version of
BICGSTAB.
* New command line option argument '-init_field read <filenameY>
[<filenameX>]' to initialize an iterative
solver by the field read from file.
* Finally removed deprecated options -Cpr_mat and '-sg_format ddscat'.
* Several wiki pages were added and documentation was
improved.
* Several improvements to Makefile.
You are advised to upgrade to a new version, which can
be downloaded (both main package and, if needed, executable for 32- and 64-bit
Windows) from: http://code.google.com/p/a-dda/downloads/
Finally, please note that ADDA is an open-source
project which development relies on the community around it. There are many
ways to help:
* Using ADDA and advocating its use through publications
and conference presentations.
* Active participation in the discussion group -
http://groups.google.com/group/adda-discuss, in particular, sharing your
experience with other users.
* Commenting and improving wiki pages ( http://code.google.com/p/a-dda/w/list ) and other
documentation.
* Locating bugs and proposing new features for ADDA,
using the issue tracker - http://code.google.com/p/a-dda/issues
.
* Contributing and improving the source code -
http://code.google.com/p/a-dda/wiki/InstructionCommitters .
Best regards,
Maxim Yurkin.
======================================================
DDSCAT
7.3.0
New
release of the discrete-dipole approximation scattering code
DDSCAT 7.3.0 adds new capabilities, and corrects a few
bugs in the previous release (DDSCAT 7.2.2) that affected a few applications.
New Features
1. DDSCAT 7.3.0 can now efficiently calculate both E
and B throughtout a user-specified rectangular volume
containing the target. The polarization P, and nearfield E (and B, if desired) are saved as files. The nearfield volume, and whether to calculate and store B as
well as E, is easily specified in the parameter file ddscat.par .
2. DDSCAT 7.3.0 includes the "Filtered Coupled
Dipole" method as an option that can be selected by the user.
3. DDSCAT 7.3.0 can now use and store results for up
to 10^6 target orientations. (For some applications, at least one user wanted
more than the previous limit of 10^3 orientations.)
4. DDSCAT 7.3.0 now reports the *macroscopic* E field
within the target, rather than the "microscopic" E field as in the
past. (The relationship between the macroscopic and microscopic fields is
explained in the UserGuide.)
5. The DDSCAT 7.3.0 distribution includes a separate
F90 code, DDPOSTPROCESS.f90, designed to read the stored P and E (and B) and
perform postprocessing calculations (e.g.,
calculating the Poynting flux). DDPOSTPROCESS.f90 can
be modified by the user to do additional postprocessing
calculations, or to output results in other formats.
6. As with DDSCAT 7.2.2, the DDSCAT 7.3.0 distribution
includes VTRCONVERT.f90 to support visualization of the target geometry using
the Visualization Toolkit (VTK) and ParaView.
All of these features are described in the UserGuide.
Bug Fixes. DDSCAT 7.3.0 corrects the following problems in 7.2.2:
1. DDSCAT 7.3.0 should now be able to correctly
calculate absorption and scattering for incident waves with arbitrary
elliptical polarizations.
2. DDSCAT 7.3.0 corrects bugs that affected some
calculations using OpenMP.
3. Calculations with anisotropic targets were affected
by a bug in subroutine unreduce.f90. This has been corrected.
Obtaining
DDSCAT 7.3.0
The complete DDSCAT 7.3.0 package can be downloaded
from http://code.google.com/p/ddscat
The code distribution (including the UserGuide) is in the gzipped tarfile ddscat7.3.0_130326.tgz
You can also download the set of "worked
examples" that are referred to in the UserGuide:
ddscat7.3.0_examples_130326.tgz
Windows executables can be
downloaded from http://code.google.com/p/ddscat/wiki/Windows
(this should be available in the near future).
DDSCAT 7.3 is gratis, subject to the GNU General
Public License. [You may copy, distribute, and/or modify the software
identified as under this agreement. If you distribute copies of this software,
you must give the recipients all the rights that you have.]
As always, please let us know if you encounter
problems downloading DDSCAT, or if you have trouble using DDSCAT (but
**please** read the manual carefully, and try running the examples, before
reporting problems!!).
Version 7.2 is no longer supported, although it will continue
to be available on the google code site. If you have
been using Version 7.2 (or an earlier version) please switch to Version 7.3.
We hope that DDSCAT 7.3 will prove useful in your
research. If you publish papers using DDSCAT 7.3, please cite
1. Draine, B.T., & Flatau,
P.J. 1994, "Discrete dipole approximation for scattering
calculations", JOSA A, 11, 1491-1499 and relevant papers describing the
DDA and its implementation in DDSCAT, e.g.,
2.Goodman, J.J., Draine, B.T., & Flatau,
P.J. 1991, "Application of FFT Techniques to the Discrete Dipole
Approximation", Optics Letters, 16, 1198-1200
3. Draine, B.T., & Flatau,
P.J. 2008, "Discrete-dipole approximation for periodic targets: theory and
tests", JOSA A, 25, 2693-2703
4. Flatau, P.J., &
Draine, B.T. 2012, "Fast near-field calculations in the discrete dipole
approximation on regular rectilinear grids", Optics Express, 20, 1247-1252
======================================================================================
See recently
indexed and summarized papers on the optics of particles and dispersions in TPDSci: http://www.tpdsci.com/Sv_.phplist=SvPdo
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