594 research outputs found
Forest Machinery Crane Compound Scheme Synthesis: Optimization of Hydraulic Cylinder Operating Mechanisms
Previously we published some results of the procedure for the improvement of intermediate technology and machinery performance criteria. The aim of the present paper is to describe the model of the middle level of hierarchy - the optimization of the hydraulic cylinder operating mechanisms. Drive and transmission mechanisms for forest machinery crane synthesis are discussed as optimizations for boom operating mechanisms and outboom operating mechanisms. Concentration is on the static part of this problem. Although the speed of movement of the crane elements affects productivity, it is not taken into account in this study. Future studies will take into consideration a dynamic analysis and output of machinery.
The results of this study show the necessity to separate the design of different types of forest machine cranes. For example, for the parallel crane type, a modification of the proposed algorithms is necessary.
This paper may be useful for forest machine designers as well as university students, who take courses in forest machine design
Bjorken Sum Rule and pQCD frontier on the move
The reasonableness of the use of perturbative QCD notions in the region close
to the scale of hadronization, i.e., below \lesssim 1 \GeV is under study.
First, the interplay between higher orders of pQCD expansion and higher twist
contributions in the analysis of recent Jefferson Lab (JLab) data on the
Generalized Bjorken Sum Rule function at is studied. It is shown that the inclusion of the higher-order
pQCD corrections could be absorbed, with good numerical accuracy, by change of
the normalization of the higher-twist terms. Second, to avoid the issue of
unphysical singularity (Landau pole at Q=\Lambda\sim 400 \MeV ), we deal with
the ghost-free Analytic Perturbation Theory (APT) that recently proved to be an
intriguing candidate for a quantitative description of light quarkonia spectra
within the Bethe-Salpeter approach. The values of the twist coefficients
extracted from the mentioned data by using the APT approach provide
a better convergence of the higher-twist series than with the common pQCD. As
the main result, a good quantitative description of the JLab data down to
350 MeV is achieved.Comment: 10 pages, 3 figures, minor change
On zero-divisors in group rings of groups with torsion
Nontrivial pairs of zero-divisors in group rings are introduced and
discussed. A problem on the existence of nontrivial pairs of zero-divisors in
group rings of free Burnside groups of odd exponent is solved in the
affirmative. Nontrivial pairs of zero-divisors are also found in group rings of
free products of groups with torsion.Comment: 8 pages, to appear in Canadian Math. Bul
Let’s groove : Attachment techniques of Eurasian elk (Alces alces) tooth pendants at the Late Mesolithic cemetery Yuzhniy Oleniy Ostrov (Lake Onega, Russia)
More than 4300 Eurasian elk (Alces alces) incisors, most of them pendants, were found in 84 burials in the Late Mesolithic cemetery of Yuzhniy Oleniy Ostrov, Northwest Russia. We analysed the manufacture techniques of elk teeth (4014), in the collection of the Peter the Great Museum of Anthropology and Ethnography, St Petersburg. A striking observation is that the manufacture of these pendants is similar in all burials. Teeth were worked by carving one or several grooves around the root tip. In addition to grooved ones, a number of teeth were not worked at all. The uniformity of the chosen species, tooth and techniques indicates that strict norms prevailed in the pendant industry. Despite the overall similarity, our study shows some variation in making pendants. A groove can cut the whole circumference of the root, or several distinct grooves can mark opposite sides of the root. Sometimes the grooves are deep and made carefully, and sometimes they are weak and made hastily. A typology of various groove types was created. In many graves, one groove type dominates. We interpret that this inter-burial variation and domination of one type resulted from personal choice and taste based on practicality. Such variation could also be associated with kin identifiers, but we did not find clear support for that in our study. Our study indicates that the groove types as such had no connection with particular ornaments, garments or hanging positions.Peer reviewe
M-Theory of Matrix Models
Small M-theories unify various models of a given family in the same way as
the M-theory unifies a variety of superstring models. We consider this idea in
application to the family of eigenvalue matrix models: their M-theory unifies
various branches of Hermitean matrix model (including Dijkgraaf-Vafa partition
functions) with Kontsevich tau-function. Moreover, the corresponding duality
relations look like direct analogues of instanton and meron decompositions,
familiar from Yang-Mills theory.Comment: 12 pages, contribution to the Proceedings of the Workshop "Classical
and Quantum Integrable Systems", Protvino, Russia, January, 200
Search for NN-decoupled dibaryons using the process below the pion production threshold
The energy spectrum for high energy -rays ( MeV)
from the process emitted at in the laboratory
frame has been measured at an energy below the pion production threshold,
namely, at 216 MeV. The resulting photon energy spectrum extracted from
coincidence events consists of a narrow peak at a photon energy
of about 24 MeV and a relatively broad peak in the energy range of (50 - 70)
MeV. The statistical significances for the narrow and broad peaks are
5.3 and 3.5, respectively. This behavior of the photon energy
spectrum is interpreted as a signature of the exotic dibaryon resonance
with a mass of about 1956 MeV which is assumed to be formed in the
radiative process followed by its electromagnetic
decay via the mode. The experimental spectrum is
compared with those obtained by means of Monte Carlo simulations.Comment: 14 pages, LaTex, 6 eps-figures, accepted for publication in
Phys.Rev.
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