2,504 research outputs found
Fuzzy simulation of forest road surface parameters
The problem of construction of forest roads with the use of local low-strength substandard materials and industrial waste is considered. To solve the problem, the primary task is to develop a method for estimating the parameters of road surfaces taking into account the conditions of uncertainties in the data. This technique allows us to reasonably clarify some of the regulatory parameters and improve the technology of construction of forest roads, which was the goal of the work. To formalize the task, experimental studies were performed and on the basis of these results, the statement of the task of fuzzy derivation of the function for estimating the bearing capacity of the coating was performed. The synthesis of the output function is performed by means of Matlab. © 2019 IOP Publishing Ltd. All rights reserved
Group analysis and renormgroup symmetries
An original regular approach to constructing special type symmetries for
boundary value problems, namely renormgroup symmetries, is presented. Different
methods of calculating these symmetries, based on modern group analysis are
described. Application of the approach to boundary value problems is
demonstrated with the help of a simple mathematical model.Comment: 17 pages, RevTeX LATeX file, to appear in Journal of Mathematical
Physic
Planning the forest transport systems based on the principles of sustainable development of territories
The article identifies a new method of dynamic modeling in the design of the transport system in the forest fund (TSFF), which is based on economic and mathematical modeling and fuzzy logic tools. The combination of the indicated methods is designed to reduce the disadvantages of their use and increase the benefits. The article substantiates the choice of assessing the forecast level of the impact of risks on the activities of forestry enterprises (the method of expert assessments), using the methodological tools of fuzzy logic. The indicated method makes it possible to take into account a large variety of risk factors of the internal and external environment. At the same time, methodological aspects of fuzzy logic make it possible to formulate a quantitative assessment of qualitative indicators. The article substantiates the choice of tools for economic and mathematical modeling in order to state the design problem of the planned TSFF. Since the indicated method enables the formalization of the functioning of the timber transport system in the given conditions. The article presents a developed model that correctly takes into account the influence of risk factors when planning a TSFF, through the combination of fuzzy logic methods and economic and mathematical modeling. The advantages of the developed model include: considering the multivariance of material flows, vehicles, points of overload, etc.; automated processing of input parameters and effective data; using the model for forecasting, i.e. the possibility of deriving a fuzzy estimate of the efficiency of the timber transport system by identifying cause-effect relationships between the modeling object and the influence of risk factors on its functioning. © 2019 IOP Publishing Ltd
Parsec-scale evolution of the gigahertz-peaked spectrum quasar PKS 0858-279
We conducted multi-epoch, multi-frequency parsec-scale studies on the
gigahertz-peaked spectrum quasar PKS 0858-279 with the Very Long Baseline Array
(VLBA). Our observations on 2005-11-26 elucidated a weak core, characterized by
an inverted spectrum, and a distinctly bent jet that exhibited a notable bright
feature in its Stokes I emission. Through comprehensive analysis of
polarization and spectral data, we inferred the formation of a shock wave
within this feature, stemming from interactions with a dense cloud in the
ambient medium. In this paper, VLBI-Gaia astrometry further reinforces the core
identification. With a deep analysis of six additional VLBA epochs spanning
from 2007 to 2018, we observed that while the quasar's parsec-scale structure
remained largely consistent, there were discernible flux density changes. These
variations strongly imply the recurrent ejection of plasma into the jet.
Complementing our VLBA data, RATAN-600 observations of the integrated spectra
suggested an interaction between standing and travelling shock waves in 2005.
Moreover, our multi-epoch polarization analysis revealed a drastic drop in
rotation measure values from 6000 rad/m^2 to 1000 rad/m^2 within a single year,
attributable to diminishing magnetic fields and particle density in an external
cloud. This change is likely instigated by a shock in the cloud, triggered by
the cloud's interaction with the jet, subsequently prompting its expansion.
Notably, we also observed a significant change in the magnetic field direction
of the jet, from being perpendicular post its observed bend to being
perpendicular prior to the bend - an alteration possibly induced by the
dynamics of shock waves.Comment: 14 pages, 10 figures, accepted for publication in MNRA
Patterns of load distribution among the legs in small water striders during standing and striding
Water striders (Gerris argentatus) move across the water surface by taking advantage of the surface tension, which supports their bodyweight without breaking. During locomotion, the midlegs are primarily responsible for generating thrust, whereas the other legs support the body. Although the aspects of standing and locomotion on the water surface are well understood, relatively fewer studies concerned the coordinated biomechanical movements of the legs. In order to maintain buoyancy of the body on the water surface, the leg positions must be adjusted to distribute the bodyweight appropriately. The present study investigates distribution of the bodyweight on the legs in relatively small water striders. We aimed to understand how loading on the legs changes during sculling that leads to sliding of the body on the water surface. The assistance of all legs at every moment enables the body to maintain its floating during standing and striding. Water striders can achieve a gentle striding through the midlegs driving phase in association with smooth load shifting among their legs, which are positioned in a specific configuration to support the insect on the water surface
Energy rationale for the Use of the Thermophilic Mode of Anaerobic Bioconversion of Liquid Organic Waste in the Climatic Conditions of the Russian Federation
The transition of livestock production to industrial processes and the concentration of animals associated with this process on large farms and complexes has caused a sharp increase in the volume of manure that must be disposed of without pollution. One of the ways of processing organic waste (biomass) is its anaerobic digestion in biogas plants through the vital activity of microorganisms (methanogenesis).Biogas obtained using microbiological processing of biomass can be used as a raw material for heat and electric energy. Annually, 0.17% of the total livestock manure produced at Russian agricultural enterprisesis used for biogas production.The main component of a biogas plant is a manure fermentation reactor, the required volume of which is determined by the daily output of manure from the livestock farm, the temperature and the hydraulic retention time of treatment. This research explored thermal energy consumption of biogas plants, using the example of a biogas plant of a modular design that depended on the average annual outdoor temperature. Based on the calculations, the thermophilic mode was found to be more energy-efficient than the mesophilic one; thus, with the thermophilic mode, the specific energy consumption needed for the plant was lower at the average annual outdoor temperatures of all the constituent entities of the Russian Federation. At the same time, the specific biogas yield in the thermophilic regime was 20-50%higher than in the mesophilic regime.
Keywords: anaerobic processing, agricultural waste, thermophilicmode, mesophilicmode, energy costs, energy rational
r-process Abundance Patterns in the Globular Cluster M92
Whereas light element abundance variations are a hallmark of globular
clusters, there is little evidence for variation in neutron-capture elements. A
significant exception is M15, which shows a star-to-star dispersion in
neutron-capture abundances of at least one order of magnitude. The literature
contains evidence both for and against a neutron-capture dispersion in M92. We
conducted an analysis of archival Keck/HIRES spectra of 35 stars in M92, 29 of
which are giants, which we use exclusively for our conclusions. M92 conforms to
the light element abundance variations typical of massive clusters. Like other
globular clusters, its neutron-capture abundances were generated by the
r-process. We confirm a star-to-star dispersion in the r-process. Unlike M15,
the dispersion is limited to "first-generation" (low Na, high Mg) stars, and
the dispersion is smaller for Sr, Y, and Zr than for Ba and the lanthanides.
This is the first detection of a relation between light element and
neutron-capture abundances in a globular cluster. We propose that a source of
the main r-process polluted the cluster shortly before or concurrently with the
first generation of star formation. The heavier r-process abundances were
inhomogeneously distributed while the first-generation stars were forming. The
second-generation stars formed after several crossing times (~0.8 Myr); hence,
the second generation shows no r-process dispersion. This scenario imposes a
minimum temporal separation of 0.8 Myr between the first and second
generations.Comment: 35 pages, 12 figures, accepted for publication in Ap
- …