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Results 571 to 600 of 610:

Insekticidní účinky výtažků z mrkve (Daucus carota) a libečku (Levisticum officinale) (Apiaceae) proti Tribolium confusum Jacquelin du Duval, 1868 (Coleoptera, Tenebrionidae)

Eva Hrudová, Blanka Kocourková, Vladimíra Zelená

Acta Univ. Agric. Silvic. Mendelianae Brun. 2006, 54(1), 165-168 | DOI: 10.11118/actaun200654010165

Extracts from Daucus carota and Levisticum officinale in different concentrations were tested for insecticidal effect against Tribolium confusum (Coleoptera, Tenebrionidae). The efficacy of treatment was evaluated after 24, 48 and 72 h. The required data were statistically analysed using the Henderson-Tilton method. The Daucus carota IPM extract in a dose of 1ml, D. carota IPM extract diluted with water in a ratio of 1:1 (dose 1 ml) and Levisticum officinale extract in a dose of 2 ml were highly efficient.

CITLIVOST RŮSTOVÝCH SIMULAČNÍCH MODELŮ NA VYPOČTENÉ HODNOTY GLOBÁLNÍHO SLUNEČNÍHO ZÁŘENÍ

Pavel Kapler, Miroslav Trnka, Zdeněk Žalud, Josef Eitzinger

Acta Univ. Agric. Silvic. Mendelianae Brun. 2006, 54(4), 21-32 | DOI: 10.11118/actaun200654040021

The results of the previous studies have suggested that the estimated RG values are loaded with an error, which might compromise the precision of the subsequent crop model applications. Therefore a detailed analysis of the error propagation was made using two crop models i.e. CERES-Barley and CERES-Wheat. Database of meteorological data originating from 8 stations in Austria and Czech Republic was used in order to carry out the analysis. It has been found that even application of the method based on sunshine duration that yield the lowest bias in RG estimates significantly influences number of key crop model outputs. It has been also noted that in 5-6 seasons out of 100 cases the deviation greater than ±10 % is to be expected whilst the occurrence of ±25% could not be also ruled out. The precision of the yield estimates and other crop model outputs is lower then expected but still acceptable for most application with mean bias error in range of 2.0-4.1% when estimates based on the diurnal temperature range and cloud cover are used. In this case yield deviations over ±10% occurred in about 20% cases (depending on the crop) whilst the probability of significant yield departure (±25%) doubled of that found for the previous method. The methods based on the diurnal temperature range and daily precipitation sum showed an increase of the systematic bias of yield of winter wheat and considerably higher number of seasons with yield departures over ±25%. Utilisation of the methods based on the diurnal temperature range only for the purposes of seasonal yield forecasting or climate change impact assessment is questionable as the probability of significant yield departure is very high (as well as the systematic error). These findings should act as an incentive to the further research aimed at development of more precise and widely applicable methods of estimating daily RG based more on the underlying physical principles and/or remote sensing approach. Overall decrease of the existing uncertainties in the RG estimates would clearly result into increase of the reliability of subsequent applications that use RG as input variable.

MOŽNOSTI MODELOVÁNÍ ČASOVÉ ŘADY INDEXU PRŮMYSLOVÉ PRODUKCE

Veronika Blašková

Acta Univ. Agric. Silvic. Mendelianae Brun. 2006, 54(6), 13-18 | DOI: 10.11118/actaun200654060013

Aim of this work is modelling index industrial performance. In work will be constructed model on base results from business tendency surveys. Business tendency surveys open opportunity for various hypotheses (e.g. that participants be subject to inertia and estimate future according to actual situation). Problem will by examined on variously time delay (0 as far as 6 months). Results from these models will be confronted with results gained by using other method, for example autoregression analysis and Box-Jenkins methodology.

Konečně-prvková studie mechanické odezvy bočnice lůžka

Petr Koňas, Milan Šimek

Acta Univ. Agric. Silvic. Mendelianae Brun. 2006, 54(2), 59-66 | DOI: 10.11118/actaun200654020059

According to non-existence of mechanical material properties for selected combination of materials it is appropriate to give a notice, that suggested solution should be examined in test-room of furniture by related norms. The suggested verification was finally realized on furniture test-room by Departure of Furniture, Design and habitation and approved availability of suggested numerical solution for defined tasks. If we take into account large amount of variants, which were modelled by this method (and which are not mentioned in this project) without requirements of experimental testing for each suggestion it is appropriate to remind the significant financial saving, due to realized numerical simulations which allowed to find efficient solution and which may not be attainable by experimental way (mainly with regard to financial severity).

Frakcionace humusu a optické vlastnosti humínových kyselin izolovaných z různých půdních typů

Ľubica Pospíšilová, Naděžda Fasurová, Lubomír Jurica

Acta Univ. Agric. Silvic. Mendelianae Brun. 2006, 54(4), 45-52 | DOI: 10.11118/actaun200654040045

Assesment of soil organic matter quality is one of the urgent problems of contemporary agriculture. Determination of humic acids (HAs) optical properties using spectroscopic techniques could be a reliable step for this evaluation. We followed differences in the functional groups of HAs preparations and showed correlation between optical indexes and fractional composition of humus. UV-VIS and SFS spectral lines and indexes were measured in mixture 0.1M pyrophosphate sodium solution and 0,1M NaOH, after filtration and appropriate dilution. Differences in the structural composition of HAs originating from different soil types were studied after isolation of HAs preparations using FTIR spectroscopy (KBr + HAs pellets, SRATR FTIR method). Results showed that studied HAs preparations could be divided into two groups. First group included HAs isolated from Chernozem and Haplic Luvisol with higher content of aromatic constituents and condensation degree. The second group were HAs isolated from Eutric Cambisol and Fluvi-Eutric Gleysol. They reflected lower content of aromatic compounds, lower condensation degree and more aliphatic structural groups in the HAs molecule. Linear correlation between fractional composition of humus and optical indexes (I501/I487, Q4/6) was found.

Vliv použítí polovlhké krmné směsi na převod rychleného plůdku candáta obecného (Sander lucioperca) do podmínek intenzivního chovu

Vít Baránek, Jan Mareš, Jiří Jirásek, Miroslav Prokeš, Petr Spurný

Acta Univ. Agric. Silvic. Mendelianae Brun. 2007, 55(1), 17-24 | DOI: 10.11118/actaun200755010017

Conversion success of pond-reared zander (Sander lucioperca) fry was evaluated using three different converting methods: direct conversion to dry feed (Bio-Optimal Start 0.8 mm; variant A), three-day application of semimoist feeding mixture on the base of fish (variant B) and three-day application of semimoist mixture + three-day co-feeding of semimoist mixture and dry feed (variant C). Two replicates per treatment were applied. These three methods were evaluated regarding specific growth rate (SGR), condition coefficient (K), survival and cannibalism. Mean initial total length (TL) of fish was 35.22 ± 2.15 mm and mean individual weight (w) was 0.31 ± 0.05 g. There were 600 individuals in each circular tank. The initial stock density was 2 fish.l-1. Fish survival during a 14-day period of rearing ranged from 34.33 % (variant C) to 50.33 % (variant A). Significantly (P < 0.05) better conversion performance was achieved with variants A and B than with the variant C regarding all parameters.

Vztah geometrie profilu lomové plochy a rázové houževnatosti kompozitních materiálů na bázi dřeva

Eva Přemyslovská, Petr Koňas

Acta Univ. Agric. Silvic. Mendelianae Brun. 2006, 54(2), 91-96 | DOI: 10.11118/actaun200654020091

The aim of this work is description of geometry of fracture surfaces of wood composite materials (cement-bonded particleboard, gypsum-bonded fibreboard and wood particleboard) using fractal analysis and exploration relation between fractal dimension and impact work. Fractal dimension determinated by filtration, volumetric and robust Box-Counting methods and Richardson method is different considering type of material and method. Proportional relationship between fractal dimension (computed by robust BC method) and impact work of mentioned materials was found in other cases non-proportional relationships were founded.

HODNOCENÍ NAPADENÍ GLOEOSPORIOVOU HNILOBOU U ODRŮD JABLEK IDARED A GOLDEN DELICIOUS REINDERS POMOCÍ NIR SPEKTROSKOPIE

Jana Růžičková, Táňa Lužová, Anna Němcová, Pavla Mýlová, Květoslava Šustová

Acta Univ. Agric. Silvic. Mendelianae Brun. 2006, 54(4), 53-60 | DOI: 10.11118/actaun200654040053

The aim of our work was to observe the possibility of application of near-infrared spectroscopy for monitoring of internal changes in stored apples inficated by Gloeosporium album (Osterw) [Pezicula malicorticis (H. S. Jackson)]. The cultivars Idared and Golden Delicious Reinders were used in this work. Two groups of infected and non-infected apples of both cultivars each containing twenty pieces and stored in cold-storage room (± 3 °C) were observed for seven weeks. The apples were measured in reflectance mode with resolution 8 and number of scans 100. Each fruit was analysed 4 times and the average spectrum was used for evaluation. The discriminate analysis was applied to separate into clusters. This method was used for distinguishing infected and non-infected apples of both cultivars during the first week from the application of Gloeosporium album. According to spectra, the infection was more evident in Golden Delicious Reinders which was also confirmed by a stronger visual exposure. Although Idared displays weaker symptoms of the attack, NIR spectroscopy was still able to detect infected fruits.

Skríning vybraných startovacích bakteriálních kultur na přítomnost DNA sekvencí kódujících dekarboxylázu tyrosinu

Radka Burdychová

Acta Univ. Agric. Silvic. Mendelianae Brun. 2006, 54(5), 7-12 | DOI: 10.11118/actaun200654050007

Here, seven different starter cultures used in the production of fermented sausages were screened for the presence or absence of specific DNA sequences coding for tyrosine decarboxylase. PCR with the a set of specific primers TDC2/TDC5 (COTON et al., 2004) was used. The PCR analysis of DNA from two starter cultures confirmed the presence of DNA sequences for tyrosine decarboxylase. A detailed analysis of the starter cultures showed that DNA sequences for tyrosine decarboxylase are contained in genomic DNA of Lactobacillus curvatus and Lactobacillus sakei.
These results show suitability of the described PCR method for the screening of starter cultures for the presence of the gene for tyrosine decarboxylase that is responsible for the production of the biogenic amine tyramine.

Analýza ovčího mléka FT NIR spektrometrem; měření vzorků na Petriho misce reflektanční kyvetou

Květoslava Šustová, Jan Kuchtík, Stanislav Kráčmar

Acta Univ. Agric. Silvic. Mendelianae Brun. 2006, 54(2), 131-138 | DOI: 10.11118/actaun200654020131

Our work deals with a possibility of determination of basic composition (dry matter, fat, protein, casein, lactose and urea nitrogen) of ewe's milk and colostrum by FT NIR spectroscopy. Samples of milk were warmed to 40 °C, agitated, cooled to 20 °C, transferred into Petri dishes and analysed by reference methods and by FT NIR in reflectance mode. The measured area was spaced by a metallic mirror. Statistically significant differences between the reference values and the calculated values of NIR were not found (p=0.05). Results of calibration for ewe's milk determined the highest correlation coefficients: dry matter 0.983, fat 0.989, true protein 0.997, casein 0.977, lactose 0.980 and urea nitrogen 0.973. The study showed that NIRS method, when samples of milk are measured on Petri dishes, is a useful technique for the prediction of dry matter, fat, protein and casein in ewe's milk.

VLIV ZPŮSOBU MĚŘENÍ A ODPOČTU TLOUŠŤKY KŮRY NA VÝslednou hodnotu OBJEMU KULATINY PŘI JEJÍ PŘEJÍMCE

Veronika Hunková, Karel Janák

Acta Univ. Agric. Silvic. Mendelianae Brun. 2006, 54(5), 37-48 | DOI: 10.11118/actaun200654050037

Thickness of the bark has serious influence on the round wood volume inside bark, if the diameter is measured over bark. The measured value of the bark thickness depends on measuring method. To analyse the possible bark thickness differences of spruce, given by different measuring methods and Peintinger's bark thickness tables and to calculate the corresponding round wood volume differences, given by different bark thickness deduction compared with the Czech Standard is the principle goal of presented research.
Three ways of bark thickness measuring were realized: by using bark gauge, increment hammer and slide caliper. Bark gauge gives the highest bark thickness values - 2,2 mm higher compared with our standard, corresponding volume decrease is 3,4%. Measuring by this method is very carefully to the bark and it gives the real values of the thickness of the undamaged bark layer. It is close to the results of electronic diameter measuring. Slide caliper give the values 0,9 mm higher compared with our standard, corresponding volume decrease is 1,5%. Slide caliper partly damages the surface layer of the bark. Increment hammer gives 0,1 mm higher values of the bark thickness compared with our standard thanks to the destruction of the surface bark layer. Corresponding volume decrease can be approx. 0,1%. Peintinger's bark thickness tables give 1,3 mm higher spruce bark thickness, it means to 1,9 % lower round wood volume. It means, Peintingers tables correspond better with the measured values than with the Czech Standard.
We can recommend the using of Peintinger's table for deduction of spruce bark thickness in electronic measuring of the round wood over bark and to use the bark gauge for test measuring. Both two methods gave the closest results to real values while our tests and it is very simple to use this instrument.

Enzym superoxid dismutasa v zrnu ječmene a sladu

Natálie Belcrediová, Jaroslava Ehrenbergerová, Pavla Havlová

Acta Univ. Agric. Silvic. Mendelianae Brun. 2006, 54(2), 7-14 | DOI: 10.11118/actaun200654020007

The aim of the work was modification of superoxide dismutase enzyme (SOD, EC 1.15.1.1) activity analysis in barley grain and identical malts with using of the Ransod set. This set from company Randox were used for enzyme determination in blood samples. This method employs xanthine and xanthine oxidase to generate superoxide radicals, which react with tetrazolium chloride to form a red formazan dye. SOD is classified as natural antioxidants and enzyme plays a significant role at detoxication of products of molecular oxygen degradation. The largest rate of SOD occurs in embryo of barley grain. Its presence in barley grain and malt thus inhibits rancidity of grain during storage and undesirable beer flavour. The line Wabet x Washonubet (in grain-104,93 and malt 152,42 U/g dry matter) and the variety Annabell (104,65 a 147,21 U/g dry matter) had the highest activity of SOD in grain and malt of barley while the lowest activity was measured in the line KM 1910 (73,15 a 88,16 U/g dry matter) and variety Tolar (74,34 a 96,44 U/g dry matter).

Molekulární markery genetické variability u odrůd tritikale registrovaných v České republice

Tomáš Vyhnánek, Jan Bednář

Acta Univ. Agric. Silvic. Mendelianae Brun. 2006, 54(5), 149-154 | DOI: 10.11118/actaun200654050149

Genetic variability was detected in 15 varieties of triticale (XTriticosecale Wittmack., 2n = 6x = 42, BBAARR) registered in the Czech Republic by means of polymorphism of DNA using the RAPD method and the SSR method. For detection we used 80 RAPD primers. The lower reproducibility of the RAPD markers was resolved by means of repeated analyses (3-4 times). On the basis of statistical evaluation a dendrogram was set up, which allows highly significantly to differentiate the varieties Kolor, Modus and Tornado. The remaining 12 analysed varieties formed 4 clusters. In addition to the RAPD markers a protocol of detection of DNA polymorphism was elaborated and optimised with microsatellite (SSR) markers. For the analyses we used 2 SSR markers (1A chromosome [Xpsp2999] and 1B chromosome [Xpsp3000]), which have been discovered in wheat (T. aestivum L.). Basing on these two SSR markers the only variety Triamant was distinguished from the clusters of the other analysed varieties.

SPOLEČENSTVA SEKÁČŮ (OPILIONIDA) LUŽNÍHO LESA V NPR RANŠPURK A JEJICH FLUKTUACE

Hana Šejnohová

Acta Univ. Agric. Silvic. Mendelianae Brun. 2005, 53(2), 155-162 | DOI: 10.11118/actaun200553020155

During the years 1993-2001 the monitoring of the soil surface fauna was carried out in a floodplain forest in the Ranšpurk National Nature Reserve (south Moravia). The harvestmen assemblages fluctuation is described in detail in this paper. The method of pitfall traps was used. A total of 3174 individuals of seven harvestmen species were collected. The species composition was very similar to other research results from the southern Moravian floodplain forest. Only the dominance values differ from the values in the other localities. All of the registered species prefer moisture and shadow places. The highest abundance was observed in Astrobunus laevipes (Canestrini, 1872), Nemastoma lugubre (Müller, 1776), Oligolophus tridens (C. L. Koch, 1936) and Rilaena triangularis (Herbst, 1799). The dynamics of harvestmen occurrence during the year had a different development than in other groups of invertebrates. Harvestmen mostly occurred in pitfall traps in autumn and winter months. The highest abundance of harvestmen in traps was observed in December and January. In July 1997, disastrous flood affected all groups of invertebrates. The flood had a minimal impact on the abundance of harvestmen in pitfall traps.

Vliv teploty na sorpční chování vlhkých zemědělských produktů

Jiří Štencl

Acta Univ. Agric. Silvic. Mendelianae Brun. 2005, 53(4), 177-184 | DOI: 10.11118/actaun200553040177

The paper demonstrates importance of temperature influence on dehydration processes using drying model equations in introductory part and further presents results of water sorption tests of parsley leaves. Measurements were carried out under laboratory conditions in the temperature range of 10-40 °C and relative air humidity from 30 to 100%. Moisture sorption isotherms were tested using a gravimetric dynamic method with continuous recording of changes in sample weight. Five mathematical models available in the literature (Chung-Pfost, GAB, Halsey, Henderson, and Oswin) were statistical evaluated. The Henderson equation was found to be a good model both for moisture adsorption and desorption. Part of the sorption isotherms measured in parsley leaves show the type II BET classification shape. An increase in temperature causes an increase in water activity for the same moisture content and, if water activity is kept constant, an increase in temperature causes a decrease in the amount of absorbed water.

Vliv rozdílného hospodaření se slámou a zpracování půdy na výskyt plevelů

Ivana Remešová

Acta Univ. Agric. Silvic. Mendelianae Brun. 2005, 53(5), 133-142 | DOI: 10.11118/actaun200553050133

The weed infestation was assessed in a field experiment at the Research Institute for Folder Crops Ltd., Troubsko near Brno in 2001-2004. Numbers of individual weed species were determined using a counting method on the area of 0.25 m2 in winter wheat stands within the 6-crop rotation (peas, winter wheat, spring barley, oilseed rape, winter wheat, winter wheat) in different variants of soil tillage and straw management. The highest weed infestation in all variants was found when winter wheat followed winter wheat. The highest number of weeds was assessed in the variant with stubble tillage to the depth of 0.12-0.15 m, planting with a precision drill and straw chopping. The lowest number of weeds was found in winter wheat after peas in the variant with incorporation of chopped straw using a tiller to 0.12-0.15 m and planting with a drilling combination, and in the variant where chopped straw was sprayed with the BETA-LIQ preparation, incorporation with a tiller to 0.12-0.15 m and planting with a drilling combination.

ANALÝZA ODLOŽENÉ DANĚ Z PŘÍJMŮ A JEJÍ VLIV NA UKAZATELE CHARAKTERIZUJÍCÍ EKONOMICKOU VÝKONNOST PODNIKU

Hana Bohušová, Patrik Svoboda

Acta Univ. Agric. Silvic. Mendelianae Brun. 2005, 53(6), 33-44 | DOI: 10.11118/actaun200553060033

Category of deferred income tax is a complex topic including the whole accounting system and the income tax. Calculation method can be time-consuming and demanding a high quality system of analytical evidence and a system of valuation and demanding the high level of accountants' knowledge. The aim in the theoretical level was to analyze process of calculation and recording of deferred tax. Importance of recording of deferred tax and the impact on financial analysis ratios was analyzed. Fourteen business entities were examined. Deferred tax recording is a legal way to reduce retained earnings a to protect of its careless alocation.

Vliv ošetření desikanty na kvalitu fenyklu obecného (Foeniculum vulgare var. vulgare Mill.)

Gabriela Růžičková, Blanka Kocourková, Jitka Sedláková, Jana Hajšlová

Acta Univ. Agric. Silvic. Mendelianae Brun. 2005, 53(5), 143-150 | DOI: 10.11118/actaun200553050143

Fennel (Foeniculum vulgare var. vulgare Mill.) is an perennial herb, it is cultivated for the essential oil in the fruits. The quality criteria are essential oil content, microbiological contamination and residua of pesticides. The important part of the cultivation technology is ununiform maturity of the fruits. The aim of this work was to find out the influence of the desiccants on quality and yield characteristics of fennel fruits produced in field conditions in the first years of growing. Three preparations were applied: glufosinate-NH4, 150 g.l-1 (2 l.ha-1), diquat dibromide, 200 g.l-1 (3 l.ha-1) and glyphosate-IPA, 480 g.l-1 (3 l.ha-1) in three repetitions. The non treated control variant was also repetited three times. The samples were analysed for quantitative and qualitative parameters: the fruit yield (t.ha-1), the essential oil content (%, V/m), the essential oil yield (kg.ha-1), the essential oil composition and the residua content.

Učení n-vrstvé neuronové sítě

Vladimír Konečný, Anděla Matiášová, Ivana Rábová

Acta Univ. Agric. Silvic. Mendelianae Brun. 2005, 53(6), 75-84 | DOI: 10.11118/actaun200553060075

In the last decade we can observe increasing number of applications based on the Artificial Intelligence that are designed to solve problems from different areas of human activity. The reason why there is so much interest in these technologies is that the classical way of solutions does not exist or these technologies are not suitable because of their robustness. They are often used in applications like Business Intelligence that enable to obtain useful information for high-quality decision-making and to increase competitive advantage.
One of the most widespread tools for the Artificial Intelligence are the artificial neural networks. Their high advantage is relative simplicity and the possibility of self-learning based on set of pattern situations.
For the learning phase is the most commonly used algorithm back-propagation error (BPE). The base of BPE is the method minima of error function representing the sum of squared errors on outputs of neural net, for all patterns of the learning set.
However, while performing BPE and in the first usage, we can find out that it is necessary to complete the handling of the learning factor by suitable method. The stability of the learning process and the rate of convergence depend on the selected method.
In the article there are derived two functions: one function for the learning process management by the relative great error function value and the second function when the value of error function approximates to global minimum.
The aim of the article is to introduce the BPE algorithm in compact matrix form for multilayer neural networks, the derivation of the learning factor handling method and the presentation of the results.

Vliv rozdílné technologie zpracování půdy na druhové spektrum plevelů v ozimé řepce

Jan Winkler, Věra Zelená

Acta Univ. Agric. Silvic. Mendelianae Brun. 2005, 53(5), 187-194 | DOI: 10.11118/actaun200553050187

A community of weeds and crops is affected by a number of factors, including, among other things, also tillage. In the years 2000-2002, the composition of weed species in rape stands was evaluated on the fields with the total area of 551 hectares (1 hectar equals to some 2.47 acres). The evaluation was carried out with the application of methodology developed by Kühn (1982). On the fields located in the cadastral area of Olomouc - Holice, which had been cultivated in a traditional manner, 115 relevés were recorded. On the fields in the cadastral area of Bohuňovice, which had been cultivated with the application of reduced tillage, 97 relevés were recorded and evaluated. All of the above fields were subjected to the application of chemical agents reducing the occurrence of weeds. The data thus received were processed by means of multidimensional analysis of ecological data with the application of a RDA method (Redundancy Analysis). In the course of three years, 75 weed species were found on the fields under conventional tillage, on the average, 8.2 species per a relevé, while 66 weed species were found during the same period of time on the fields cultivated by means of reduced tillage, on the average, 8.6 species per a relevé. The application of RDA analysis enabled us to sort out the selected species of weeds (i.e. those the frequency of occurrence of which exceeded 15 %) into three groups. The conditions provided by the conventional tillage appeared to be more satisfactory for the weed species included in the first group (Arctium tomentosum, Elytrigia repens, Helianthus tuberosus, Chenopodium album, Lolium perenne and Papaver rhoeas). The species included in the second group, i.e. Alsinula media, Apera spica-venti, Atriplex patula, Bromus sterilis, Capsella bursa-pastoris, Equisetum arvense, Fallopia convolvulus, Myosotis arvensis and Thlaspi arvense., responded to reduced tillage by the increase in cover or by increased frequency of occurrence. The third group consists of species such as: Cirsium arvense, Chamomilla recutita, Galium aparine, Lactuca serriola, Matricaria maritima, Triticum aestivum and Viola arvensis. Their cover and frequency of occurrence were in a more degree influenced by factors different from the type of tillage. The manner of tillage appears to be only one of a number of factors that affect the occurrence of weed species. It influences them together with other factors and it is a factor of polyfunctional nature.

O viskoelastických vlastnostech hovězího masa při tlakovém zatěžování

Jaroslav Buchar, Jana Simeonovová

Acta Univ. Agric. Silvic. Mendelianae Brun. 2005, 53(5), 7-14 | DOI: 10.11118/actaun200553050007

A method for the characterising of the behaviour of the beef meat at compressive loading was investigated. Both compressive and relaxation tests have been used. Results of the relaxation tests have shown that the boiled beef can be described in terms of the Maxwell model of the strain behaviour. Parameters of this model are dependent on the values of the loading force. The description of the observed behaviour of the beef under compressive loading thus needs some other model. It is shown that the obtained results on the compressive loading of the beef can be explained in the framework of the hyperelastic - viscous body.

ZOBRAZENÍ NAPĚTÍ A DEFORMACE S VYUŽITÍM AE

Michal Černý, Pavel Mazal, Josef Filípek

Acta Univ. Agric. Silvic. Mendelianae Brun. 2005, 53(2), 63-74 | DOI: 10.11118/actaun200553020063

The work is focused on the use of acoustic emission (AE) in technical practice. AE is a relatively new non-destructive experiment method, which is broadly developing mainly at the end of 20th and beginning of 21st century. The aim of the work is to monitor stress and strain initiation area until yield point. The yield point is a final stress-strain limit for machine parts application. Actual σ - ε state should be detected by material acoustic response. It enables determining of machine usable life. Uniaxial tensile test has been performed to achieve this goal. By use of AE method, the whole A2 screw deformation, all the way to breakdown, has been observed. The record from AE has been compared with force-time (F - t) record. In order of completeness the record has been also compared with another screw types - ČSN 021143.50. The comparison clearly confirmed the conclusion about acoustic activity in connecting element - screw.

Vliv přídavku propylenglykolu na tělesnou kondici krav, jejich mléčnou užitkovost a kvalitu mleziva

Robert Kupczyński, Maciej Adamski, Gustav Chládek

Acta Univ. Agric. Silvic. Mendelianae Brun. 2005, 53(4), 51-60 | DOI: 10.11118/actaun200553040051

The research was executed on 24 high yield dairy cows divided into three groups (n = 8). There was the control group (I) that the propylene glycol wasn't given to cows, group II - the cows received 250 ml/day/per head of the propylene glycol, and the group III ─ the cows received 500 ml/day per head of the propylene glycol. The preparation was administered to cows per os beginning from 2 weeks before parturition to the end of the third week of lactation. During the research the condition of animals was estimated by BCS method, the daily yield was recorded, and analyses of the milk and colostrum composition were performed. The propylene glycol lightened the decrease of cows' condition during entering at the peak of lactation. The higher dose (500 ml) was more profitable, because it had an influence on the content of the colostrum components, low urea level in milk as well as on daily yield, which was higher of about 3.64 kg while the preparation was given, in comparison to the control group. In the 3rd week of lactation the low level of somatic cells in milk of cows that received the preparation was stated. In conclusion, our study revealed a great positive effect of propylene glycol given to the cows shortly before and after parturition on their body condition and a less significant effect on colostrum quality and milk yield.

HODNOCENÍ STABILIZACE POVRCHOVÉ KOROZE Oceli NÁTĚROVÝMI HMOTAMI

Aleš Dvořák, Marta Ščerbejová

Acta Univ. Agric. Silvic. Mendelianae Brun. 2005, 53(5), 31-38 | DOI: 10.11118/actaun200553050031

This article deals with laboratory experiments focused on protective and stabilizing effects of paints designed to protect rusted steel surfaces. Two well-known paints (the Hammerite No.1 Rustbeater synthetic paint and the Antirezin water-soluble paint) have been evaluated. The standardized tests according to ČSN have been used for the evaluation. Stabilization of rusted steel surface hasn't been demonstrated during the tests. The SEM test method that covers micro-analysis of elements has been used for the evaluation as well.

POROVNÁNÍ STRAVITELNOSTI ORGANICKÝCH ŽIVIN V KRMNÝCH DÁVKÁCH S OBSAHEM LUPINY A HRACHU U KONÍ

Pavel Šajdler, Ladislav Zeman

Acta Univ. Agric. Silvic. Mendelianae Brun. 2005, 53(2), 83-88 | DOI: 10.11118/actaun200553020083

The aim of this study was to find out and compare organic nutrients digestibility in feed rations containing different forage legumes in balance trials on horses. The trials were always performed on a group of six sports horses (weight of 495 to 742 kg). Six feed rations were tested, which contained different proportion of certain forage legume in empirical feed mixtures. Three feed mixtures contained white lupine seeds (WLS) - Lu 0 (0.01% WLS), Lu 7 (7% WLS), Lu 14 (14% WLS) and surplus three feed mixtures contained field pea seeds (FPS) - Hr 0 (0.01% FPS), Hr 10 (10% FPS), Hr 20 (20% FPS). Amount of WLS in feed mixtures Lu 0 and Lu 7 was completed with starch to value 14% and amount of FPS in feed mixtures Hr 0 and Hr 10 was completed with starch to value 20%. Indicator method was used to predict dietary nutrients digestibility. Apparent digestibility values of all organic nutrients were higher at the feed rations with the content of FPS. Average values of apparent digestibility coefficient of those feed rations were: dry matter (77.79%; SD = 2.91), organic matter (78.43%; SD = 2.78), crude protein (79.89%; SD = 3.43), fat (66.57%; SD = 2.40), crude fiber (68.97%; SD = 3.21) and nitrogen-free extract (83.30%; SD = 2.71).

Kombinace faktorové analýzy a Fourierovy transformace při hodnocení jakosti surové vody

Petra Nováková, Milada Šťastná

Acta Univ. Agric. Silvic. Mendelianae Brun. 2005, 53(4), 95-102 | DOI: 10.11118/actaun200553040095

The applied method - combination of the factor analysis and Fourier transformation is not routinely used in the water management. Due to the fact that the statistic program Prognost is able to do the analysis only from limited number of the quantities, only selected surface water quality indicators were included in the analysis. Therefore it wasn't possible to prove the influence of all eventual natural and anthropogenic impacts in the catchment area that affect the water quality in the reservoir Vranov nad Dyjí. By the selected indicators it was possible to cover especially the effects of the intensive agriculture, the settlement, the recreation (especially from the point of the view of the draining and cleaning of the waste water), climatic influences (precipitation) and partly the nature background. The selected indicators don't evaluate for example the impact of the industry. The water quality in the reservoir is influenced by the water quality from the tributaries and by the biochemical processes in the reservoir itself.

Modelování růstu vykrmovaných prasat a vliv stresových faktorů na spotřebu krmiva

Ludvík Novák, Ladislav Zeman, Pavel Novák, Petr Mareš

Acta Univ. Agric. Silvic. Mendelianae Brun. 2005, 53(5), 105-116 | DOI: 10.11118/actaun200553050105

Modeling the body mass growth in fattened pigs by means of the exponential growth function enables to simulate the growth curve from three constants of the gender's, or the hybrid's combination, represented by their body mass phenotype: body mass at birth (G0) genetic limit of body mass (GLi) and the maximum body mass increase reached in the inflexion of the growth curve (dG max). However the expression of animal's genome to its body mass phenotype depends on the amount and quality of the feed mixture consumed and mainly on the fact how much of the net energy gained remains left for production (NEp), after the mandatory needs of the body maintenance functions are saturated. Only this amount of net energy for production may be deposited into the proteins and fats of the body mass increase (dG/dt). The net energy for production (NEp) is restricted; if a greater amount of net energy gained (NE) is spend, for compensation of the stressors impact (NE stx). The sum of particular stressor's action is expressed by stressor's index (STX) and indicates the proportional increase of net energy (NE) spend for the maintenance requirement of the animal (NEm). This contribution extends, the classic method of modeling the body mass growth, by the simultaneous modeling of the daily feed mixture intake (DFI) with the content of metabolizable energy (SMEF). The daily feed intake is calculated with respect to the impact of stressors on the net energy consumption. The setting of the model automatically increases the amount of the daily feed intake, so that the adequate amount of net energy for production will not be disturbed. The basic equation for the appropriate daily feed intake sounds as follow
DFI = (NEp + (STX + 1). BM) / (0,6 SMEF) [kg/d]. the BM=0,3.G3/4 [MJ/d]
Details for calculation, of the net energy for production (NEp) from the input values of the body mass phenotype (G0, GLi, dG max), the content of the metabolizable energy in the feed (SMEF) and of the stressors index value (STX), are described. The validation of the method developed has been approved using the experimental data gained in the fattening of 33 pigs, both sexes, of PIC hybrid combination. The animals were fattened with the standard feed mixture TESTA in a controlled condition of stable's climate and appropriate stockbreeder's and veterinary care.

Parametrizace numerické simulace procesu sušení v atypické komorové kondenzační sušárně řeziva

Jiří Zejda, Petr Koňas

Acta Univ. Agric. Silvic. Mendelianae Brun. 2004, 52(1), 169-174 | DOI: 10.11118/actaun200452010169

This work deal with modelling of the process of drying, air flow, temperature and moisture distribution in a condensation lumber kiln. This model was made and solved in the computing system ANSYS with the use of the finite element method. There are comparationes of the 2D and 3D models, shape of wood stacks and variability of their parameters (height, width, length, cross section) in the work. The flow velocity and orientation, pressure and temperature field were observed.

Homogenita fenotypu vykrmovaných prasaT a metodika jejího stanovení

Ludvík Novák, Ladislav Zeman, Pavel Novák, Petr Mareš

Acta Univ. Agric. Silvic. Mendelianae Brun. 2004, 52(2), 53-64 | DOI: 10.11118/actaun200452020053

New method for evaluation of the ideal growth performance in pigs has been proved in the experimental stable room of MZLU in ŠZP Žabčice. This method is based on the biological interpretation of the exponential growth function of Gompertz. This solution defines the dynamic of the animal's phenotype by the body mass at the begin of the fattening (G0), by the animal's race standard body mass (Gli) which is equal to the value of the growth curve asymptote and by the value of the daily maximum body mass increase (dGmax) given by the genotype of the animal. This phenotype definition yields the possibility to define the exponential growth curve of the animal from birth until to the body mass maturity by the equation in which (t) represents the age of the animal:
Gt = Gli.exp(-ln(Gli/G0).exp(-(e.dGmax/Gli).t)) [kg] (1)
The value of the real daily body mass increase is than estimated by the best approximation of the experimental body mass values by the growth curve defined in the equation (1). The distribution of animals in three groups, according to the calculated daily maximum body mass increase: the thin growing animas, by default growing animals and the most growing animals, demonstrated the dynamic of the relation between the value of the daily maximum body mass increase (dGmax) and the body mass of the animals (Gt). In animals aged 37 days the clear correlation between the daily maximum body mass increase and the body mass reached:
Y = 21.486x - 14.826 (R2 = 0.69); and Y = 28.609x2 - 45.21x + 23.868 (R2 = 0.70).
In animals of the age 150 days the correlation is a little bit looser:
Y = 54.316x +39.146 (R2 = 0.31); and Y = 8.203x2 + 35.192x + 50.241 (R2 = 0.31).
The presented original methodology for evaluation of the animal's individuality by means of the biological version of Gompertz exponential growth functions has been proved as a tool for direct evaluation of expression of the genotype body mass into its phenotype values, already during the experiment or the fattening process.

Využití denních teplotních extrémů a úhrnu srážek k odhadu globálního slunečního záření

Miroslav Trnka

Acta Univ. Agric. Silvic. Mendelianae Brun. 2004, 52(5), 13-28 | DOI: 10.11118/actaun200452050013

Two methods for estimating daily global solar radiation (RG) based on the daily temperature extremes and precipitation sum are compared in the study. All parameters necessary for application of both methods were derived either from literature or from climatic characteristics easily available at the given meteorological stations excluding need for measured RG data. The performance of both methods was assessed with a help of meteorological database including 4 stations in the Czech Republic (data were provided by the Czech Hydrometeorological Institute) and 6 in Austria (data provided by the Austrian Weather Service) containing in total 41 640 observational day. For each day in the database observed daily sum of RG, daily maximum and minimum temperatures and precipitation sum were available. Coefficient of determination, slope of regression line forced through origin, mean bias error (MBE) and root mean square error (RMSE) were used as performance indicators. The first method proposed by Winslow et al. (2001) - Eq. (1) is capable to explain 86% of daily RG variability, with systematic error represented by MBE equaling to 0.19 MJ.m-2.day-1 and random error indicated by RMSE reaching up to 3.09. The second method published by Thornton and Running (1999)-Eq. (2) was found to be in almost all parameters inferior to the Eq. (1) and thus the Eq. (1) is recommended to be used in the Central European region (up to 600 m above the sea level). This method might be recommended for stations where neither measured RG or sunshine duration hours exist. However, one should take into consideration that relative MBE and RMSE are in some months higher than 10% and 30% respectively, which may compromise results of subsequent calculations made with use of estimated solar radiation data and alter the order of the method suitability.

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