135 research outputs found
Investigations about the impact of the sowing time and rate of the biomass yield and quality of industrial hemp
ArticleThe aim of this study was to find the optimum sowing rate of industrial hemp
(Cannabis sativa L.) and to clarify the impact of the sowing rate on the production of biofuel
from hemp biomass in Latvia. Field trials were carried out at the Research and Study Farm
‘Pēterlauki’ of the Latvia University of Agriculture in 2012–2014. The industrial hemp (Cannabis
sativa L.) ‘Futura 75’ was sown in a Luvic Endogleyic Stagnosol soil: pHKCl 6.7; P – 52 mg kg-1
;
K – 128 mg kg-1
; the organic matter content – 21–25 g kg-1
. Hemp was sown in 10-m2 plots,
triplicate, on May 8 and 17. The total sowing rate was 20 (100), 30 (150), 40 (200), 50 (250),
60 (300), 70 (350), 80 (400), 90 (450), and 100 (500) kg ha-1
(germinating seeds per 1 m2
). The
plots were fertilised as follows: N – 120 kg ha-1
; P2O5 – 80 kg ha-1
; and K2O – 112 kg ha-1
. Hemp
was harvested when the first matured seeds appeared. The biometrical indices (height and stem
diameter), harvesting time, the amount of fresh and dry biomass, and the fibre content were
evaluated. Depending on the sowing rate, the yield of dry matter was on average 9.2–12.1 t ha-1
when hemp was sown at the beginning of May, and 7.9–10.0 t ha-1 when hemp was sown in the
middle of May
A mathematical model of the plane-parallel movement of an asymmetric machine-and-tractor aggregate
Technological peculiarities of cultivation and harvesting of some agricultural crops make it necessary to use asymmetric machine-and-tractor aggregates. However, for the time being there is no sufficiently complete, analytical study of the steady movement of such machine-and-tractor aggregates. This necessitates the development of a theory of stable movement of the aggregates which would allow choosing their optimal kinematic and design parameters. On the basis of the results of mathematical simulation, a system of linear differential equations of the second order is obtained describing transverse displacement of the center of masses of the aggregating wheeled tractor and turning of its longitudinal axis of symmetry by some angle around the indicated center of mass, as well as the deviation angle of the rear-trailed harvester from the longitudinal axis of the tractor at any arbitrary moment of time. This system of differential equations can be applied for numerical calculations on the PC, which will make it possible to evaluate the stability of the movement of the asymmetric machine-and-tractor aggregate when it performs the technological process
Assessment of the greenhouse gas emissions and energy inputs applying different weed control methods for wheat growing
Received: January 25th, 2023 ; Accepted: May 21st, 2023 ; Published: June 17th, 2023 ; Correspondence: [email protected] indicators are often used to evaluate and select technologies, determining the
production costs of the product. However, according to the EU's green course, the ecological
assessment of technologies is increasingly important. The purpose of the article is to comparatively
evaluate two winter wheat weed control methods, which are widely used in Latvia, according to
two ecological indicators - the amount of the GHG emissions and the energy consumption, to find
out whether these indicators can serve as a criterion for the selection of technologies. These two
methods are HA (harrowing), in which weeds are controlled by harrowing and herbicides, HE
(herbicides), in which weeds are controlled only by herbicides. The methodology for calculating the
mentioned indicators was developed by analyzing several studies by other authors. The total GHG
emissions generated are calculated as the sum of five components: emissions, generated for the
manufacture and delivery of the machinery used; emissions, generated by the fuel, consumed for
implementation of the technology; emissions, generated for the production, delivery and installation
of fertilizers; emissions, generated for the production, delivery and installation of pesticides, seed
production, delivery and installation emissions. Analogously, the total energy consumption is
calculated by summing the components The technologies were implemented on a specific farm,
with the machinery of this farm, labor, fertilizers and the plant protection products. It has been
established that the technologies differ by the calculated ecological indicators within the range of
1.2–2.6%; moreover, these indicators are lower for the technology with the herbicide spraying, and
the technology is simpler to implement. Therefore, it is also more widely used. Since the coefficients
for the calculation of the ecological indicators can be applied by the methodology of this article, the
characteristics of the technique and the doses of fertilizers and the plant protection agents, used on
the farms, are known, the ecological indicators can be used as an additional criterion for the selection
of technologies on the farms. The ratio of the energy value and energy consumption of the produced
product (the output and the input ratio) was also determined, this indicator for technologies HA and
HE being, respectively, 8.30 and 8.41. In comparison with the research by the authors in other
countries, from the point of view of the amount of the generated CO2-eq emissions and rational
consumption of energy, the analysed winter wheat production technologies are evaluated as
moderately efficient, but from the point of view of the energy value of the product produced and the
ratio of the energy consumption (the output and the input ratio) - as efficient
The efficiency of nitrogen fertilizer on the dry matter yield of tall fescue and festulolium grown as feedstock for combustion
ArticleGrass biomass grows during one vegetation season and can be cultivated and consumed
at the place of breeding. Grass biomass can be used not only in traditional feed, but, recently, also
for energy production (biogas, solid fuels). The most important economic indicator for any crop
is its productivity. The study found that it is important to use nitrogen fertilizer to increase the
productivity of tall fescue and festulolium. A significant increase (p < 0.05) in the yield of tall
fescue was observed starting from the nitrogen norm of 60 kg ha-1 N. Further increase in nitrogen
fertilizer norm provides a significant increase in dry mater yield of tall fescue (reaching
8.64 t ha-1
) and festulolium (reaching 8.11 t ha-1
) at 180 kg ha-1 N. The analysis of linear
regression coefficients of polynomials showed that the highest nitrogen efficiency in the first year
of the use of tall fescue was achieved at the norm of 180 kg ha-1 N, but for festulolium – at the
norm of 120 kg ha-1 N. In the following years of tall fescue use, the highest efficiency of nitrogen
norms differed: in the 2nd and 4th year of use – at 60 kg ha-1 N, in the 3rd year of use – at
30 kg ha-1 N, and in the 5th year of use – at 120 kg ha-1 N. In contrast, for festulolium, in the 2nd
year of use, the highest nitrogen efficiency was reached at the norm of 30 kg ha-1 N, and in the
3rd–5th year of use – at the norm of 60 kg ha-1 N
Research in dynamic transitional processes of functioning of combine harvester hydraulic drives
An analysis of perspective methods is made for diagnosing hydraulic drives, based on the on-board automated tools. Prospects are substantiated for the development of technical diagnostics of agricultural machinery on the basis of on-board electronic means. Special attention is paid to the need for significant research in the direction of creating new diagnostic parameters, adapted to these means, and methods of their measurement. The parameters of the characteristics of changes in the pressure of the working fluid in the hydraulic aggregates in transitional modes of operation of the hydraulic drives are advisable to be used as diagnostic, since the veracity (accuracy) of the parameters, based on them, is not less than 95%. As an example, a method of diagnosing on dynamic transitional modes of operation of the hydraulic drives is given, which is the basis for the development and use of built-in and portable electronic means for conducting CIP diagnostics, which will provide 2-3 times decrease in the labour intensity and the cost of work with at least 85% veracity of diagnosis and the permissible error measurements no more than ± 4%. The novelty of this work lies in the method we have developed for diagnosing the dynamic transient modes of operation of hydraulic drives
Theoretical research of force interaction of a flexible cleaning blade with a beet root head
ArticleThe most common technology of removing the sugar beet haulm in the world is a
continuous cut of the entire mass of the green haulm with further additional removal of the upper
parts of the sugar beet heads, which is carried out without extracting the roots from the ground.
This is the scheme according to which most top harvesting machines, manufactured in the world,
now operate. However, we have found in our studies that, due to additional cutting off the upper
parts of the root crop heads, up to 10% of the sugar-bearing mass is lost. Besides, there is an
urgent need for immediate processing of the sugar beet root crops, as losses of the sugar juice
occur, and bacteria enter inside of the root crop through the cut-off part, causing rotting.
Therefore, a more favourable operation for harvesting root crop tops is not cutting off their heads
but cleaning them from the residues of the foliage. In addition, the operation of cleaning the sugar
beet roots from the residues of the foliage is subject to rather high requirements due to the absence
of the green and dry residues on the heads of the roots, as well as the losses and damage of the
root crops themselves. The purpose of this investigation is to develop a theory of the force
interaction of the flexible cleaning blade with the sugar beet head in the process of its cleaning
when the blade is mounted on the vertical driving shaft. The methods used of the investigation
are those of modelling, higher mathematics and theoretical mechanics, as well as programming
and numerical calculations on the computer. As a result of the research, an equivalent scheme
was developed and a mathematical model was constructed describing the force interaction of the
flexible cleaning blade with the surface of the sugar beet root
Approximate approach of research and assessment of crack resistance of cylindrical housings
In this work, we propose a procedure that allows us to quickly, without involving finite-element packages at the execution stage, evaluate the state of postulated cracks in cylindrical structural elements with internal anticorrosion cladding under pressure and unsteady temperature loading. The procedure contains three components. The first component of the procedure is based on the analytical solution of the unsteady thermal conductivity problem. The second component of the procedure is also analytical relations specifying circumferential and longitudinal stresses in a two-layer cylinder as a function of internal pressure and temperature distribution along the depth of the wall. In the third stage of the procedure, the coefficients of stress intensity along the crack front are determined by the method of influence functions using the known distribution of stresses. To implement this part of the procedure, the influence functions must first be calculated by the finite element method. In this work the example of calculating the functions of influence for longitudinal semi-elliptical cracks of 1/8 wall thickness depth and with the ratio of the principal half-diameters 0.3 and 0.7 is presented. As an example of the implementation of the procedure, comparative calculations were carried out and the elastic-plastic calculation of a cylindrical shell containing longitudinal cracks was given. Stress intensity coefficients along the part of the front located in the base metal were calculated. The results of analytical calculations were conservative until plastic deformations developed in the cladding. At significant plastic strains, the values of the stress intensity coefficients calculated by the proposed procedure, on the contrary, are significantly inferior. This demonstrates once again the fact that calculations in the framework of linear fracture mechanics are not always conservative in relation to calculations in the elastic-plastic formulation. The paper gives an explanation of the reason for the obtained effect
Results of experimental investigations of a flexible active harrow with loosening teeth
ArticleSoil tillage processes significantly affect the growth of cultivated plants; therefore,
improvement of various designs and combinations of ploughs is still an actual practical and
scientific task. This paper presents investigations of the design of a soil tillage machine consisting
of three plough bodies equipped from the lateral side with a module with a flexible active harrow
driven by a support wheel. The technological process of tillage by this machine is carried out in
such a way that the module of the flexible active harrow is installed at a certain depth of soil
tillage. The purpose of this work is an experimental comparative investigation of the quality
indicators of the work of a design of the soil tillage working body with a flexible active harrow
having loosening teeth. In the process of comparative experimental investigations of the operation
of ploughs with a standard flexible harrow and an experimental active harrow having loosening
teeth, the soil lumpiness (characterising the quality of crumbling) and water permeability of the
obtained soil structure were estimated. An experimental model of this working tool was tested
under the production conditions, and it showed advantages of loosening and crumpling the soil
compared to the conventional harrows. This can be explained by the fact that the harrow tines,
freely mounted on the axes of its links, ensure their oscillatory movements when moving in two
different planes, thereby creating conditions for more intense soil disintegration
Operational and technological properties of ploughing block-modular machine-and-tractor aggregate
One of the topical directions in the development of agricultural tractor construction can be the formation of machine-and-tractor units according to a modular principle, using technological modules with the driving wheels. The aim of this work is to study the possibilities how to increase the operational and technological indicators of the operation of an agricultural aggregate in a modular aggregation system due to the selection of rational parameters of an elastic-dissipative connection of the energy and the technological modules. The obtained data were processed by statistical methods on a PC, using correlation and dispersion analyses. It has been established by experimental investigation that the operation of a ploughing block-modular aggregate, while ensuring rational rigidity of the connection of its energy and technological modules, is achieved by throttling the hydraulic system of its rear suspension at the level of 75%, characterised by an increase in its performance by 6% and a decrease in the specific fuel consumption by 12.4%. In addition, the level of vertical vibration load of the operator corresponds to the allowed fatigue rate for 8 h of work
Theory of grain mixture particle motion during aspiration separation
The practice of separating grain mixtures with the use of the difference in the
aerodynamic properties of their components has proved that the process of separating mixtures
in the aspiration separator is the most promising one with regard to the improvement of quality
and intensification of production. The authors have developed a new improved design of
aspiration seed separators, in which the work process of separating seed material is performed
with the use of vibration processes. In this seed material separator, the constant force air flow that
acts on the sail members on the central pipe of the separator, when seeds are fed for processing,
generates self-excited oscillations in the pipe, which produces centrifugal forces of inertia in the
seed feeding system. As a result of the mentioned effect, the propelling force in the process under
study substantially increases, accelerating the seeds of different fractions, which differ in their
masses, to different velocities. The motion paths of the seed particles change accordingly, heavier
particles moving closer to the vertical axis of the aspiration channel, which provides for
increasing the efficiency of separation of the seeds of different fractions from each other. In this
paper, a new mathematical model is developed for the motion of a seed mixture material particle
in the operating space of the separator’s aspiration channel. The mathematical modelling of the
process of vibration and aspiration separation has indicated that the separation of the motion paths
of the medium and heavy fractions takes place within the range of 20–40 mm; the flying speed
of the particles is equal to 3.2–8.0 m s–1, respectively; and their acceleration is equal to 1.8–
3.3 m s–2, which provides the necessary conditions for the accurate and high quality separation
into the required fractions. In view of the found differences between the kinematic characteristics
of the separated fractions of the grain mixture, the diameter of the pipeline for the medium
fraction is to be within the range of 90–100 mm, for the heavy fraction – 50–70 mm
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