2018, Vol. 16, No. 4

Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/5377

Sirvi

Nüüd näidatakse 1 - 20 33

Additional concentrates do not affect feeding times of cows, but social positions of cows do
(2018) Soonberg, Maria; Kass, Marko; Kaart, Tanel; Leming, Ragnar; Arney, David R.; Estonian University of Life Sciences. Department of Animal Nutrition; Estonian University of Life Sciences. Department of Animal Breeding and Biotechnology
In robotic milking dairy systems lack of control over intakes can be problematic for balancing the forage and concentrate portions of diets. This can lead to proble ms associated with high concentrate intakes and concomitant low forage intakes. To check this as a problem, the feeding behaviour of cows was observed: the number of daily visits to the feed barrier, the duration of these visits and actual feeding, of high and low yielding cows. The cows were robot - milked and fed a ration comprising, separately, concentrate feed from a robot and a feeder, and a grass/clover silage mix forage at the feed barrier. Individual variation in visiting times and times spent at the feed barrier were greater than the effect of level of production. There was no evidence that cows with higher milk yields are differentially motivated to feed from forage. But more dominant cows spent more time feeding than submissive cows.
Agronomic evaluation of a Colombian passion fruit (Passiflora edulis Sims) germplasm collection
(2018) Galeano Mendoza, C.H.; Cerón-Souza, I.; Arango, L.V.
Passion fruit (Passiflora edulis Sims) is one of the most promissory crops in Colombia with approximately 7,400 ha cultivated, an average production of 89,000 t and an average yield of 15 t ha-1. However, low yields as well as harvest problems including fruit quality, generate important losses, mainly due to lack of improved cultivars with particular characteristics for each market (fresh consumption, agroindustry) and specific adaptations to biotic and abiotic stress factors in producer areas. Therefore, as a pre-breeding phase, this study aimed at characterizing preliminary the production and physiochemical characteristics of 60 passion fruit germplasm accessions maintained in Corporación Colombiana de Investigación Agropecuaria (AGROSAVIA). We cultivated these accessions in the field for 22 months between 2014 and 2015, measuring 17 variables associated to both yield production and fruit quality. We analysed data using phenetic and multivariate methods to establish levels of genetic diversity. Additionally, we constructed a selection index (SI) with the most informative variables to select individuals according to fruit weight, shape and colour, as well as juice percentage. Results of genetic grouping and principal components showed a broad genetic diversity across the working collection, without any population substructure. Fruit volume, pulp and seed weight were the variables that explained 80% of the phenotypic variation. Finally, we identified 30 promissory accessions as parental for the first cycle of recurrent selection using the SI. We conclude that this core collection represents the diversity included in the working collection with promissory accessions to initiate an intra-population recurrent selection program.
Analysis of indoor temperature in the workshop building during the summer: a pilot study
(2018) Cao, D.V.; Kic, P.
The aim of this paper is the presentation of measurements' results and the calculation method for analysis and evaluation of climate conditions as well for using of natural illuminance in two large simple buildings during summer which could be used to calc ulate power demand for the air cooling to reduce the indoor temperature caused by solar radiation. In this research, we carried out experiments of measuring the indoor temperature at level of working place which is 1.1 m, in two similar large workshops wit h floor area 260 m 2 and height 6.5 m, during several hot summer days. The indoor conditions were strongly influenced by the solar radiation as the buildings have large wall and roof windows. The indoor air temperatures in the first building achieved 39.5 ° C, which caused the heat stress for workers. The indoor air temperatures in the second building achieved only 29.5 °C. The calculated power demand for the air cooling to reduce the indoor temperature to 25 °C is 25 . 6 kW in the first building, the cooling p ower for second building is 14 . 9 kW. We investigated measured construction of the workshop and we set up the formula in order to calculate thermal balance. The measurement results and calculated results in two buildings are compared and summarized in the t ables and in the graphs for analysis. As a general conclusion, it must be said that solar radiation has a big influence on the air temperature and methods of passive air - conditioning should be more applied also on the production buildings in industry, agri culture and other branches of civil engineering to release heat increasing air temperature inside the building.
Application of conversion model for designing hydrodynamic pumps in turbine mode
(2018) Polák, M.
The use of the smallest water resources has been coming again to the centre of interest in recent years. A water engine – turbine, is the heart of these power plants. This is usually the highest expense for the investor, in terms of cost. The effort is therefore to seek investment less demanding alternatives. One of them is the use of hydrodynamic pumps in reverse turbine operation. This paper provides a methodology for conversion of parameters of the smallest power pumps (micro hydro sites) to turbine operation. The conversion model is based on the results of experimental research at the author's workplace and is suitable for pumps with low specific speeds and outputs. The pump design process for turbine mode is complemented by a practical example for a specific deployment site. This example also serves to verify the accuracy of the conversion model.
Assessment of Calotropis natural dye extracts on the efficiency of dye-sensitized solar cells
(2018) Alami, A.H.; Aokal, K.; Zhang, D.; Tawalbeh, M.; Alhammadi, A.; Taieb, A.
This work presents the construction and testing of solar cells sensitized with natural dyes extracted from plants indigenous to the desert. Calotropis plants are self - sufficient as they grow in very harsh environments, and yet are not consumed by humans or livestock due to their irritating agents to the skin and eyes. The energy generators of these plants are the leaves, which are crushed and processed to produce the dye solution. Also, the Calotropis leaves are covered in a white powder that is thought to aid in mitigating the heat by scattering incident radiation. This powder material is examined and added to the dye as it proved advantageous for the o verall cell efficiency, which reached 0.214% compared with 0.108% for cells with no powder. The produced cells are also compared with ones sensitized by spinach, another common natural sensitizer for dye - sensitized solar cells, and the performance proved t o be significantly better. The fact that Calotropis is a non - food plant is an added advantage to utilizing it as a dye source, along with its intrinsic heat resistance that allows it to survive the harsh desert conditions all year round.
Assessment of potato plant development from Minitubers
(2018) Dimante, I.; Gaile, Z.
In production of minitubers, mani pulation of their weight by modifying production method is common. Under field conditions plant development from minitubers can be affected by their weight, as well as cultivar. This objective of this study was to compare plant development from four minitu ber weight classes (MtC) (3 to 4.99 g, 5 to 9.99 g, 10 to 19.99 g, and > 20 g) with broken apical dominance of cultivars ‘Monta’, ‘Prelma’ and ‘Mandaga’. ‘Prelma’ and ‘Mandaga’ had a similar development pattern, and minitubers > 20 g required significantly less growing degree days (GDD) to emerge than minitubers from the lightest classes. The heaviest minitubers needed on average 176 GDD for 50% emergence and 207 GDD were needed for the lightest class. The difference in GDD between the marginal MtC was more pronounced in period between 50 and 80% emergence. MtC did not affect the final rate of emergence. Number of above ground stems (1.4 – 4.0) was significantly affected by MtC. ‘Monta’ had significantly different development – delayed emergence, lower emergen ce rate, less above ground stems, faster canopy closure. Our study showed that plant development was significantly affected by MtC and cultivar. Differences between MtC were more pronounced under adverse meteorological condi tions.
Assessment of the actual hand position on the steering wheel for drivers of passenger cars while driving
(2018) Hruška, M.
This work deals with the assessment of the actual position of the hands on the steering wheel of drivers of passenger cars in specific driving modes. The findings are compared with the location that is generally considered to be optimal in terms of both active and passive safety, and the long - term effects on the health of the driver. The research desc ribed in this work was carried out on a sample of randomly selected drivers in the Czech Republic. For all of the measurements, one identical neutral passenger middle - class vehicle, with which none of the test subjects had previous experience, was selected . The reason for this research was to model a normal situation where the driver controls a vehicle with his hands on the steering wheel in a position that is only the result of his or her own intuition and the subjective sense of the driver’s comfort. On t he basis, of a statistical evaluation of the obtained data, it was found that the introductory hypothesis, which states that a significant part of the tested sample of drivers holds the steering wheel in an unsuitable manner, can be confirmed. This fact ne gatively impacts not only on the reduction of active and passive safety, but also affects the health of drivers who drive a large amount of kilometres annually. The results of this work can be used in the design of cabs and modern passenger car systems tha t will be able to motivate the driver to hold the steering wheel in an optimal way. This will directly affect road safety and positively influence the health of drivers.
Biostability of cotton fibers with different natural colors and selection
(2018) Kotomenkova, O.; Vinogradova, A.
Biodamageability is one of the weak sides of the cotton - plant fiber. Economic loss from the cotton damage caused by microorganisms is significant. Toxic chemical compounds are used to preserve the cotton fiber. This has a negative impact on environment and cotton consumer s. The degree of the cotton biodamage depends on selection variety, types of cultivation, storage conditions and other factors. One of the directions in cotton planting is selection of the boll - stained cotton. It was established that naturally colored cott on of different varieties has high biostability. It allows to product hypoallergenic, eco - friendly textile and reduces impact on the environment. The purpose of the work is stability evaluation for microbiological damage of different cotton varieties inclu ding those naturally colored during long - term storage in different temperature and humidity conditions. The research lasted for 10 years. The species composition of the cotton microflora was determined, the impact of fiber on microorganisms and dynamics of samples biodamage was studied in the work. The results obtained show preservation of microflora viability on cotton fiber when storing it under normal conditions for a long - term period. With an increase in temperature and humidity necessary for microorgan isms’ growth, the fiber destruction processes are amplified. It was established that cotton damage degree depends on the regimes and terms of its storage as well as the color of the fiber. Nature - colored cotton is more resistant for microorganisms, some va rieties inhibit the growth of mold fungi.
Concentration of air-borne microorganisms in sport facilities
(2018) Kic, P.; Ruzek, L.; Popelarova, E.
This paper is focused on the microclimatic research in several buildings and ro oms used for sport at the University. The attention is paid mainly to the problems of dimensions of space, capacity and activity of sportsmen, and influence of space ventilation. The air samples for microbiological analyses were taken by the microbial air sampler Merck Mas - 100 Eco and cultivated by potato - dextrose agar and nutrient agar. Captured microorganisms, are expressed as colony forming units per m 3 (CFU m - 3 ). Measurement results showed that bacteria average quantity was statistically significantly less without students (562 CFU m - 3 ) than with students (1,024 CFU m - 3 ). The students inside the rooms increased the bacteria concentration. From this point of view th e ventilation is not adequate for the removal of bacteria from ventilated spaces. From the results we can conclude that the great importance on the air quality in terms of a specific bacteria concentration has the specific volume of the room per one athlet e. The worst situation is in rooms with the smallest volume, which has the largest biological load of the space. The lowest quantity of bacteria was in the swimming pool all year round (152 to 300 CFU m - 3 ). The opposite situation was in average quantity of filamentous fungi, which was with students and ventilation (57 CFU m - 3 ) and without students but without ventilation (109 CFU m - 3 ). The pollution of air by fungi was higher without ventilation.
Effect of drying technologies on bioactive compounds maintenance in pumpkin by-products
(2018) Kļava, D.; Kampuse, S.; Tomsone, L.; Kince, T.; Ozola, L.
During the pumpkin processing large amounts of waste material as a combination of pumpkin peel, seeds and the flesh between seeds has produced. Therefore it is important to investigate the possibilities for using the pumpkin residues. The aim of this resea rch was to investigate the effect of different drying technologies on maintenance of bioactive compounds in pumpkin by - products. Two pumpkin residue products of Hubard group pumpkins were used to obtain pumpkin powder: residue products formed in the proces s of extracting industrial pumpkin purée by heating it in a heat exchanger and treating through a sieve of pulpier; residues resulting from pumpkin juice extraction process mechanically pressed from fresh, chopped pumpkins. In order to be able to choose th e most suitable drying technology pumpkin by - products were dried in the microwave - vacuum, convective (at 40, 50, 70 and 80 °C ) and freeze - drying type dryers. For all samples total carotenes, the ascorbic acid, total phenols content (TPC) and antiradical ac tivity (DPPH ̇, ABTS ̇+ ) were determined by using standard methods. The highest total carotenes content was retained in freeze - dried pumpkin powders. The most suitable drying method for obtaining pumpkin powder with the highest ascorbic acid, total phenolic content and antiradical activity is drying in convective type drying at 80 °C temperature.
Effect of environmental temperature on bending strength of the finger jointed aspen lumber
(2018) Iejavs, J.; Spulle, U.; Jakovlevs, V.; Buksans, E.; Zelmenis, A.
Glued sauna wall boards are used as non-load-bearing structures. These products are subject to aggressive microclimate impact and very often for the gluing in length and width thermoplastic polyvinyl acetate adhesives (PVAC) are used. In the performed research sauna wall boards made of common aspen (Populus tremula L.) with mean wood moisture content 8% were used. For the gluing in length with finger joint PVAC glue of D4 (LVS EN 204) group was used. The aim of the research is identifying the impact of the environmental temperature on the strength of finger jointed aspen timber in 4 point static bending (in compliance with standard LVS EN 408). As a result of the study it was established, that after holding the finger jointed testing pieces visible in flat wise for 3 hours at the temperature of 100°C , the mean bending strength decreased by 56% or 31.7 MPa in comparison to that held in the standard atmosphere. In case of the aspen timber with finger joints visible in edge wise held for 3 hours at the temperature of 100°C , the bending strength decreased by 60% or 29.3 MPa in comparison to the testing pieces of the same type held in the standard atmosphere.
Effect of PTO-driven tillage machines on soil particles transfer
(2018) Buřič, M.; Novák, P.; Hůla, J.
Displacement of soil particles by erosion can be seen as a major threat to the quali ty of agricultural land in the conditions of Czech Republic. While the effects of water and wind erosion have long been investigated and reported, the effect of soil tillage technology on soil particles translocation are relatively new area of agriculture research. Soil tillage may contribute to the undesirable translocation of soil particles towards lower - lying parts of fields especially on slopes. The effect of soil tillage implements on soil particle translocation has not been sufficiently explained yet. The object of this research was to assess the influence of PTO (power takeoff) - driven tillage machines on soil particle translocation during secondary tillage (soil preparation). Measurements to determine the displacement of soil particles were performed in location Nesperská Lhota in the Central Bohemia Region. Measurements were performed on a sandy loam cambisol after harvest winter cereals (winter wheat). To indicate displacement of soil particles was used grit of white limestone (size 10 – 16 mm). Limest one was put down into the trench with known position orthogonal to the direction of working operations. Subsequently were performed working operations in the specified sequence. Limestone particles were counted and weighed in each section. It was detected by measuring the different nature of displacement for each machine. Statistical significance of differences in the weight of translocated particles was evaluated for different type of machines.
Efficiency of the use of field beans in fattening lambs
(2018) Kairisa, D.; Aplocina, E.
The breeding and feeding of self produced pulses to livestock is one of the important directions of research for reducing the production costs of livestock products. Experiment on the effective using of the field beans to lambs for fattening was arranged in three replications using the Latvian Da rk - headed breed male lambs. The mixture of concentrated feed consisted of 50% of bean and 50% of oat. Lambs were weighed at the starting and ending of the trial. Carcass quality was assessed according to the European standard for the classification of carc asses of sheep. The fattening period lasted from 37 to 94 days, on average 63 ± 3.6 days. The average live weight gain per day was 247.4 ± 13.85 g, and live weight increased on average by 15.3 ± 0.94 kg. Significantly higher ( P < 0.05) growth rate during fattening period reached lambs of 3rd group, where lambs started fattening above 27 kg of live weight, reaching a 276.8 ± 26.26 g daily live weight gain. The quality of the obtained carcasses was an average, and score for musculatu re was from R to O class, but the average score for fat deposition was from 3 to 4 points. The mixture of field beans and oats provided 19.3% of crude protein and 12.1 MJ of metabolizable energy per 1kg of dry matter, and its unlimited feeding provided med ium lamb's growth rate. The level of feed conversion was 7.56 kg of dry matter .
Ergonomic modelling parameters and the influence of ergonomics on planning workplaces
(2018) Maksimov, D.G.; Kalkis, H.
Modern economic research divides all economics into structural levels: mega - economics, macroeconomics, meso - economics, micro - economics, and nano - economics. From the point of such traditional divisions, the research is topical in the primary economic struct ure of society – nano - economics – and thanks to this work operations can be subdivided into workplaces in the form of transformation processes. The aim of the research is to develop ergonomic modelling parameters and to discover the influence of ergonomics on the planning of workplaces ba sed on a case study. The research involved a study of workplace ergonomic planning methods and principles. Solutions for a series of problems which are related to the improvement of workplace ergonomics may be discovered in the following ways: improving wo rk organisation in every workplace by using work process - related micro - elemental methods and a determination of work expenditure, the levels of physical strenuousness involved in the work, the complexity of the work, and the social importance of the workpl ace. These parameters will allow the workplace quantity characteristics to be discovered, such as in terms of a generalised parameter which conforms to the requirements which describe a workplace, and in terms of operational management via the condition of workplaces and the salary systems being utilised. The research provides a case study in which ergonomic modelling parameters are developed and concrete workplace interventions are introduced.
Evaluation of greenhouse gas emissions and area of organic soils in cropland and grassland in Latvia – integrated National forest inventory data and soil maps approach
(2018) Petaja, G.; Okmanis, M.; Polmanis, K.; Stola, J.; Spalva, G.; Jansons, J.
The aim of the research was to assess distribution of organic soils in farmlands for the time period between 1990 and 2015, as well as to carry out a recalculation of GHG emissions from organic soils in grassland and cropland. We evaluated the area of typical organic soils using digitized soil maps created between 1960s and 1980s there were 183,000 ha of cropland and grassland on organic soils. A selected number of areas on organic soils intersecting with the National forest inventory (NFI) plots were surveyed. We found that 66 ± 10% of surveyed plots still conforms to criteria for organic soils according to Intergovernmental Panel on Climate Change (IPCC) guidelines; in the rest of plots soil organic matter has been mineralized and these areas do not conform to IPCC criteria of organic soils. The following distributionof organic soils was estimated in cropland – 6.3 ± 3.3% in 1990 and 4.1 ± 3.4% in 2015, but in grassland – 11.6 ± 3.6% in 1990 and 7.7 ± 3.9% in 2015. The annual reduction of GHG emissions due to reduction of area of organic soils in cropland in 2015 corresponds to 1,400,000 tonnes CO2 eq. in comparison to 1990 and in grassland – to 1,100,000 tonnes CO2 eq. The estimated reduction of the GHG emissions due to conversion of organic soils into mineral soils, comparing the average value in 2005–2009 with the projection for 2021–2030 on average will correspond to 313,000 tonnes CO2 eq. annually, however LULUCF sector still won’t become a net CO2 sink according to the GHG inventory data on other land use categories and carbon pools.
Extended use of Sphagnum peat as a biosorbent for Zn(II): repetiti ous sorption-desorption process
(2018) Denisova, V.; Tihomirova, K.; Mezule, L.
In this study, continuous biosorption - desorption cycles in a fixed - bed column were performed to evaluate the extended use of sphagnum peat as biosorbent material to remove Zn(II) ions from aqueous solutions. Biosorption - desorption studies revealed that the sphagnum peat as biosorbent could be regenerated using 0.1M HCl as eluting agent with more than 70% recovery in four successive biosorption - desorption cycles. The results showed that the sphagnum peat should be used as an alternative, effective and low - cost biosorbent for Zn(II) ions removal from polluted aqueous solution.
Farm manure amount calculation using statistical data in Latvia
(2018) Priekulis, J.; Aboltins, A.; Laurs, A.; Melece, L.
To calculate ammonia emissions caused by production, storage and application of farm manure, it is necessary to know the amount of farm manure obtained in the country and also the kinds of manure. For this purpose, methodology and computer software are dev eloped to calculate the amount of farm manure based on the data of the Central Statistical Bureau, the technology of farm animal handling in the country and the respective valid normative documents. Upon calculating the amount of farm manure produced in La tvia in 2016, it was stated that approximately a half of the manure is litter manure, one third – liquid manure, and one fifth – manure left in the pastures. The most of manure in Latvia (69% of the total amount) is obtained from milk cows, their calves an d young stock.
Faults and the physical workload in sawing and packing-related woodworking processes when considering potential ergonomic solutions
(2018) Kalkis, H.; Roja, Z.; Babris, S.
The forest sector is a high - risk economic sector in Latvia, one in which manual work, awkward postures, the tightening up of individual muscle groups, and work monotony still exists. The aim of this study was to analyse the physical workload and fault modes, and their effects on the sawing and packing proce sses in woodworking when considering potential ergonomic solutions. Results show that packing operators and saw operators alike are exposed to severe loads, and these results coincide with survey results in which employees in these professions complain abo ut the physical load and mention lower back pain. Fault modes and their effects on the sawing and packing processes were analysed using Failure Mode and Effects Analysis, and the main errors which were revealed in packing operations were related to machine ry and lifting equipment, as well as to ergonomics and errors involving the human factor. The risk priority was calculated in terms of a figure. Financial indices were compared before and after any potential improvement in the sawing and packing processes. Analysis proves that investments in the improvement of ergonomics in relation to the automation of the production process saves human resources and is economically favourable when it comes to ensuring the sustainable development of the business in questio n.
Field trajectories proposals as a tool for increasing work efficiency and sustainable land management
(2018) Kroulik, M.; Hula, J.; Brant, V.
Together with the requirement for higher productivity the average performance and the weight of agricultural machines are increasing. Agricultural land is increasingly exposed to pressures caused by agricultural machinery. The heavy agricultural machinery passes across a field are frequently associated with technogenic soil compaction. Soil compaction is one of the main problems of modern agriculture. From the previous measuring of the traffic intensity it was found 86.13 % of the total field area was run - o ver with a machine at least once a year, when using conventional tillage and 63.75 % of the total field area was run - over when using direct seeding technology, with dependence on the working width of the machines. Field passes are inevitable in present agri culture. As a result of the increase of total machines weight, it is necessary to optimize the traffic lines trajectories and limit the entries of the machines in the field. At present, the choice of traffic lines direction is based primarily on the experi ence of drivers or the practice of farmers. There are a number of influences that affect the machine work efficiency. Monitoring of the tractor, on an irregular 8 fields showed the following results. Eight - meter working width tiller or seeder brought short ening of total length of turns at headlands with the change in trajectory azimuth. For purposes of measuring the monitored tractors were equipped with monitoring units ITineris. An overview of the chosen directions of the trajectories and the lengths of wo rking and non - working passes was obtained. Based on the shape of the plot, the trajectory of the lines was also modelled. Suitable traffic lines directions in terms of the ratio of work and non - work passes were searched. Based on records of real trajectori es, the ratio of working and non - working path ranged between 6.3 and 15.2%. It was obvious from the results that the shortening of non - working passes and turns in comparison with the originally chosen trajectory directions was achieved by optimization. Thi s was especially valid for complex shapes of fields. Trajectory optimization leads to a reduction of total le n g th of path in all cases. The reduction in total length of path ranged from 69.7 m to 1 , 004.8 m. Changing the length of the working path ranged fr om 10.9 m to 264.9 m with the change in azimuth. The extension was observed in three cases. The highest part on the change of the overall length of the path presented nonworking rides.
Fodder beans and peas in the diet of dairy cows
(2018) Trūpa, A.; Ošmane, B.; Konošonoka, I.H.
The Holstein - Friesian Black - and - White cows were grouped into four treatments groups according to the analogue principle (n = 4 × 5). Lactating dairy cows were included in the trial in the initial lactation phase with the average milk yield of 23.00 kg per day, fat content 4.10% and 3.20% protein content in milk. The analyses of the chemical composition of legume grains show, that crude protein and undegraded intake protein (UIP) were higher in fodder beans than in peas, respectively 29.97% and 25.04% of dry matter but UIP content, respectively 40.51% and 39.69% of crude protein. There was a total of 17 amino acids detected in legume grains and soybean meal. The highest concentration of arginine, leucine, glutamic acid, aspartic acid and isoleucine was in fod der beans, respectively 0.76%, 0.58%, 0.67%, 0.42% and 0.29% more than in peas. Even though the daily milk yields decreased for all the cow groups during the experiment, which was normal during the lactation period, yet the milk yield decreases for the tri al groups. The highest total amount of amino acids in milk was detected in 3 rd and 2 nd trial cow groups, respectively, 4.00 g kg - 1 and 3.90 g kg - 1 which was fed fodder beans and peas. The milk sale and feed cost summary records for the trial that lasted 90 days show that economic efficency of peas plus beans has been positive.

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