136 research outputs found
Automated measuring system for studying the properties of porous materials under complex loading paths
Наведений аналіз експериментальних досліджень механіки деформування та установок для проведення експериментальних досліджень. Приведено опис вимірювального комплексу для дослідження механічних і фізичних властивостей порошкових матеріалі. Представлені засоби вимірювання силових і деформаційних параметрів та їх тарувальні залежності. Розроблена електрична схема узгодження тензометрів. Побудована модель автоматизованої системи регулювання силових параметрів навантаження з подальшою реєстрацією деформаційних характеристик з використанням нечіткої логіки.Purpose. Development of hardware-software complex based on IR 5047-50 tensile machine, model building automated control systems elongation details, modeling and forecasting the behavior of porous materials under complex loading trajectories with the use of fuzzy logic. Design/methodology/approach.. The authors reviewed the methods of deformation of structural materials neodnorodnyh and installation for studying deformation and strength properties of powder materials. The developed device for lifting strength and deformation characteristics of a tenzometric sensors. Constructed taruvalni dependence. Models of porous materials based on fuzzy logic. We recommend using the method of fuzzy logic to predict material behavior under complex loading paths. Findings. Developed a model plant and automated control systems of power load parameters, followed by registration of deformation characteristics using fuzzy logic Originality/value Appropriate use of fuzzy logic method for modeling the behavior of porous materials.Приведен анализ экспериментальных исследований механики деформирования и установок для проведения экспериментальных исследований. Приведено описание измерительного комплекса для исследования механических и физических свойств порошковых материале. Представлены средства измерения силовых и деформационных параметров и их тарировочной зависимости. Разработана электрическая схема согласования тензометров. Построенная модель автоматизированной системы регулирования силовых параметров нагрузки с последующей регистрацией деформационных характеристик с использованием нечеткой логики
First analysis of anisotropic flow with Lee--Yang zeroes
We report on the first analysis of directed and elliptic flow with the new
method of Lee--Yang zeroes. Experimental data are presented for Ru+Ru reactions
at 1.69 AGeV measured with the FOPI detector at SIS/GSI. The results obtained
with several methods, based on the event-plane reconstruction, on Lee--Yang
zeroes, and on multi-particle cumulants (up to 5th order) applied for the first
time at SIS energies, are compared. They show conclusive evidence that
azimuthal correlations between nucleons and composite particles at this energy
are largely dominated by anisotropic flow.Comment: 5 pages, 3 figures, submitted to Phys. Rev. C Rapid Co
Isospin dependence of relative yields of and mesons at 1.528 AGeV
Results on and meson production in Ru +
Ru and Zr + Zr collisions at a beam kinetic
energy of 1.528 GeV, measured with the FOPI detector at GSI-Darmstadt, are
investigated as a possible probe of isospin effects in high density nuclear
matter. The measured double ratio ()/() is
compared to the predictions of a thermal model and a Relativistic Mean Field
transport model using two different collision scenarios and under different
assumptions on the stiffness of the symmetry energy. We find a good agreement
with the thermal model prediction and the assumption of a soft symmetry energy
for infinite nuclear matter while more realistic transport simulations of the
collisions show a similar agreement with the data but also exhibit a reduced
sensitivity to the symmetry term.Comment: 5 pages, 3 figures. accepted for publication in Phys. Rev.
Strange meson production in Al+Al collisions at 1.9A GeV
The production of K, K and (1020) mesons is studied in Al+Al
collisions at a beam energy of 1.9A GeV which is close or below the production
threshold in NN reactions. Inverse slopes, anisotropy parameters, and total
emission yields of K mesons are obtained. A comparison of the ratio of
kinetic energy distributions of K and K mesons to the HSD transport
model calculations suggests that the inclusion of the in-medium modifications
of kaon properties is necessary to reproduce the ratio. The inverse slope and
total yield of mesons are deduced. The contribution to K production
from meson decays is found to be [17 3 (stat) (syst)]
%. The results are in line with previous K and data obtained for
different colliding systems at similar incident beam energies.Comment: 16 pages, 11 figure
Identification of baryon resonances in central heavy-ion collisions at energies between 1 and 2 AGeV
The mass distributions of baryon resonances populated in near-central
collisions of Au on Au and Ni on Ni are deduced by defolding the spectra
of charged pions by a method which does not depend on a specific resonance
shape. In addition the mass distributions of resonances are obtained from the
invariant masses of pairs. With both methods the deduced mass
distributions are shifted by an average value of -60 MeV/c relative to the
mass distribution of the free resonance, the distributions
descent almost exponentially towards mass values of 2000 MeV/c^2. The observed
differences between and pairs indicate a contribution
of isospin resonances. The attempt to consistently describe the
deduced mass distributions and the reconstructed kinetic energy spectra of the
resonances leads to new insights about the freeze out conditions, i.e. to
rather low temperatures and large expansion velocities.Comment: 30 pages, 13 figures, Latex using documentstyle[12pt,a4,epsfig], to
appear in Eur. Phys. J.
Two-proton small-angle correlations in central heavy-ion collisions: a beam-energy and system-size dependent study
Small-angle correlations of pairs of protons emitted in central collisions of
Ca + Ca, Ru + Ru and Au + Au at beam energies from 400 to 1500 MeV per nucleon
are investigated with the FOPI detector system at SIS/GSI Darmstadt.
Dependences on system size and beam energy are presented which extend the
experimental data basis of pp correlations in the SIS energy range
substantially. The size of the proton-emitting source is estimated by comparing
the experimental data with the output of a final-state interaction model which
utilizes either static Gaussian sources or the one-body phase-space
distribution of protons provided by the BUU transport approach. The trends in
the experimental data, i.e. system-size and beam energy dependences, are well
reproduced by this hybrid model. However, the pp correlation function is found
rather insensitive to the stiffness of the equation of state entering the
transport model calculations.Comment: 9 pages, 8 figures, accepted at Eur. Phys. Journ.
Direct comparison of phase-space distributions of K- and K+ mesons in heavy-ion collisions at SIS energies - evidence for in-medium modifications of kaons ?
The ratio of K- to K+ meson yields has been measured in the systems RuRu at
1.69 A GeV, Ru+Zr at 1.69 A GeV, and Ni+Ni at 1.93 A GeV incident beam kinetic
energy. The yield ratio is observed to vary across the measured phase space.
Relativistic transport-model calculations indicate that the data are best
understood if in-medium modifications of the kaons are taken into account.Comment: 14 pages including 3 figure
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