*Wednesday, 16 December 2020, at 11.00*
*Online seminar*
*Nechaevskiy A.V.*
*Methods and tools for simulating distributed data storage and
processing systems based on the monitoring results*
(based on the PhD thesis)
Modern data storage and processing systems represent composite
distributed software and hardware complexes built using grid and cloud
technologies. Simulation modeling allows one to detect bottlenecks in
the architecture of data centers, to conduct experiments with changing
the topology and replacing resources to check the proposed system
solutions without directly interfering with the functioning of working
setups and to test algorithms for task management and resource
allocation among user groups. At present, the processes of simulation
and monitoring are considered as independent tasks, not related to each
other. To enhance the accuracy of the results, it is required to use the
statistics accumulated during work using monitoring systems as input
data for simulation. This entails the development of software tools that
combine the processes of simulation and monitoring. The presented
software complex SyMSim for simulating data storage and processing
systems implements the synthesis of modeling and monitoring and allows
one to carry out preliminary studies of different options for organizing
the IT infrastructure, to evaluate the capacities of the existing
architecture in solving data storage and processing tasks and to give
recommendations for its optimization. SyMSim was used to simulate the
computing centers of the BM@N and MPD experiments at the NICA
accelerator complex, MPI calculations and the IHEP computing center in
Beijing.
/More information on the seminar and the link to connect via *Webex* are
available at Indico:/https://indico-hlit.jinr.ru/event/217/
В четверг, 26 ноября, состоится Онлайн семинар:
Семинар научного отдела вычислительной физики
Четверг, 26 ноября 2020г., 15.00
Онлайн семинар
I. Hristov1, R. Hristova1, S. Dimova1, P. Armyanov1, N. Shegunov1,
I. Puzynin2, T. Puzynina2, Z. Sharipov2, Z.Tukhliev2
1.Sofia University, Faculty of Mathematics and Informatics, Bulgaria
2.JINR, Laboratory of Information Technologies, Dubna, Russia
“Parallelizing multiple precision Taylor series method for integrating
the Lorenz system”
A hybrid MPI+OpenMP strategy for parallelizing multiple precision Taylor
series method is proposed, realized and tested. To parallelize the
algorithm, we combine MPI and OpenMP parallel techniques together with
the GMP library (GNU multiple precision library) and the tiny MPIGMP
library. The details of the parallelization are explained on the
paradigmatic model of the Lorenz system. We succeeded to compute a
reliable trajectory for the Lorenz attractor in the rather long time
interval [0, 7000]. The solution was checked by comparing the results
for 2700-th order Taylor series method and precision ~ 3374 decimal
digits with those with 2800-th order and precision ~ 3510 decimal
digits. With 192 CPU cores, the 2800-th order computation lasted ~148
hours with a speedup ~103.
Информация о семинаре и ссылка на подключение размещены в Indico:
https://indico-hlit.jinr.ru/event/211/
=========================
Подключение к семинару:
https://meet.google.com/sqi-nmmu-cjs
Friday, 23 October 2020, 11.00, Conference-Hall LIT
Online via Webex
Sapozhnikov A.A.
“Magnetic system modelling using method of volume integral equations with
piecewise-linear approximation of the field within ferromagnetic”
(Materials of a PhD thesis)
We consider the application of the volume integral method to the
magnetic system calculations. The major stages of modelling process are
discussed: the discretization of initial equations, the description of
the algorithm for dividing the area into elements, the calculation of
matrix elements for discretization problem and the solution for the
obtained system of non-linear equations. The results of modelling of
magnetic systems using the discussed method are presented and compared
with calculations performed by other programs.
FLNP SEMINAR
October 09, 2020 (Friday), 11-00
FLNP Conference hall (3rd floor)
https://jinr.webex.com/jinr/j.php?MTID=m47850dc820c62cf16fb69e1ca88fc3e2
The IBR-3 pulsed research reactor – optimization of parameters “Method
of reducing the level of power fluctuations in pulsed reactors”
Shabalin E.P., Hassan A.A., Rzyanin M.V., Kulikov S.A.
Thursday, 1 October 2020, 11.00, Room 310
Online via Webex
E.E. Perepelkin abcd , B.I. Sadovnikov b, N.G. Inozemtseva cd,
E.V. Burlakov bd, R.V. Polyakova a
a Joint Institute for Nuclear Research
b Lomonosov Moscow State University
c Dubna State University
d Moscow Technical University of Communications and Informatics
“EFFECTIVE NUMERICAL ALGORITHM FOR CONSTRUCTING THE WIGNER FUNCTION OF A QUANTUM SYSTEM WITH A POLYNOMIAL POTENTIAL IN THE PHASE SPACE”
When considering quantum systems in the phase space, the Wigner
function is used as a function of the quasi-probability density. Finding
the Wigner function is related to the calculation of the Fourier
transform of a certain composition of wave functions of the
corresponding quantum system. As a rule, the knowledge of the Wigner
function is not the ultimate goal, and computations of the average
values of different quantum characteristics of a system are required.
An explicit solution of the Schrödinger equation can be obtained only
for a narrow class of potentials; therefore, numerical methods to find
wave functions are used in most cases. Consequently, finding the Wigner
function is associated with the numerical integration of grid wave
functions. When considering a one-dimensional system, it is obligatory
to calculate N2 Fourier integrals of the grid wave function. To provide
the required accuracy for the wave functions corresponding to the higher
states of a quantum system, a larger number of grid nodes is needed.
The goal of the given work was to construct a numerical-analytical
method for finding the Wigner function, which would significantly reduce
the number of computational operations. Quantum systems with polynomial
potentials, for which the Wigner function is represented as a series in
some known functions, was considered.
The work was supported by the RFBR grant No. 18-29-10014.
https://webmail.jinr.ru/?_task=mail&_action=compose
Friday, 14 August 2020, at 15.00
Online seminar via Zoom
P.B. Kats*, K.V. Halenka*, O.O. Voskresenskaya**
*Brest State A.S. Pushkin University, Belarus
**Joint Institute for Nuclear Research, Dubna, Russia
“Numerical and analytical calculations of the normalized Mott cross
section, as well as of the Mott−Bloch and Lindhard−Sørensen corrections
to the Bethe formula at moderately relativistic energies”
The report presents the results of numerical and analytical calculations
of the normalized Mott scattering cross section using a number of
earlier methods and a method proposed by the authors of this work. It is
demonstrated that applying the given method, along with the method of
Lijian et al., is preferable for relevant calculations. The results of
the numerical calculation of the Lindhard−Sørensen correction and the
total Mott−Bloch correction to the Bethe stopping formula for heavy ion
ionization energy losses, which was obtained by three different methods,
are also presented for the ranges of a gamma factor of approximately 1 ≲
γ ≲ 10 and the ion nuclear charge number 6 ≤ Z ≤ 114. It is shown that
the accurate calculation of the Mott−Bloch corrections based on the
“Mott exact cross section” using a method previously proposed by one of
the authors gives excellent agreement between its values and the values
of the Lindhard−Sørensen corrections in the γ and Z ranges under
consideration. In addition, it is demonstrated that the results of
stopping power calculations obtained by the two above-mentioned rigorous
methods coincide with each other up to the seventh significant digit and
provide the best agreement with experimental data in contrast to the
results of some approximate methods, such as the methods of Ahlen,
Jackson−McCarthy, etc.
Thursday, 24 September 2020, 15.00, Conference-Hall LIT
Online via Webex
Indico: https://indico-hlit.jinr.ru/event/204/
Sapozhnikov A.A.
“Magnetic system modelling using method of volume integral equations with
piecewise-linear approximation of the field within ferromagnetic”
(Materials of a PhD thesis)
We consider the application of the volume integral method to the
magnetic system calculations. The major stages of modelling process are
discussed: the discretization of initial equations, the description of
the algorithm for dividing the area into elements, the calculation of
matrix elements for discretization problem and the solution for the
obtained system of non-linear equations. The results of modelling of
magnetic systems using the discussed method are presented and compared
with calculations performed by other programs.
Wednesday, 29 July 2020, 3:00 PM
Online seminar via Webex
https://indico-hlit.jinr.ru/event/198/
Igor Pelevanyuk
“Integration of geographically distributed heterogeneous resources based
on the DIRAC Interware”
The DIRAC Interware platform enables the integration of distributed
heterogeneous computing resources and storage systems into a unified
system. Since 2009, it has been developed as a versatile open-source
tool. DIRAC comprises a set of services related to load and data
management, a web interface, resource consumption accounting,
authorization and authentication, workflow management and some others.
Four interfaces, namely, a web interface, a command line interface, a
Python programming interface and a REST interface, are provided to
users.
At present, the DIRAC-based unified environment, which includes both
computing resources and data storage systems, is used to generate and
reconstruct events of the MPD experiment, to study the SARS-CoV-2 virus
within the Folding@Home project on available cloud resources and to
integrate clouds of the JINR Member States’ organizations into a
distributed platform.
The talk will cover the major aspects of using DIRAC to start jobs and
interact with data.
The information on the workshop and the link to connect via Webex are
available at Indico:
https://indico-hlit.jinr.ru/event/198/
18 June 2020 at 3:00 PM (online format)
“Information system for the tasks of radiation biology
(joint project of LIT and LRB)”
The workshop is dedicated to a joint project of LIT and LRB, which is
focused on the creation of an information system for analyzing
behavioral and pathomorphological changes in the central nervous system
in the study of the effects of ionizing radiation and other factors on
biological objects. The information system is based on computer vision
algorithms within machine and deep learning technologies, modern IT
solutions for data storage, processing and visualization. The
information system will allow one to accelerate and simplify work with
experimental data for different research groups, as well as to elaborate
effective methods of prevention and protection from ionizing radiation.
The information system is being created on the basis of the HybriLIT
heterogeneous platform of JINR.
Workshop program
• I. Kolesnikova (LRB JINR)
Setting tasks for the development of an information system to analyze
morphofunctional changes in the central nervous system when studying the
effects of ionizing radiation and other damaging factors.
• Yu. Severiukhin (LRB JINR)
Noldus Ethnovision XT for the analysis of behavioral responses of small
laboratory animals.
• Yu. Butenko (LIT JINR)
Development of a service for conducting radiobiological studies on the
HybriLIT platform.
• D. Marov (LIT JINR, Dubna State University)
Development of a web service for analyzing functional and morphological
changes in the central nervous system of irradiated animals.
• A. Stadnik (LIT JINR)
Algorithms for image segmentation based on the neural network approach
in the study of morphofunctional changes in the central nervous system.
• A. Bulatov (LIT JINR)
Algorithms of computer vision for the analysis of behavioral responses
of small laboratory animals.
More information on the workshop and the link to connect via Webex are
available at Indico:
https://indico-hlit.jinr.ru/event/196/