HAVLÍČEK, M., NEDOMOVÁ, Š., SIMEONOVOVÁ, J., SEVERA, L., KŘIVÁNEK, I.: On the evaluation of chicken egg shape variability. Acta univ. agric. et silvic. Mendel. Brun., 2008, LVI, No. 5, pp. 69-74 Although recently reported models for determining egg shape are highly accurate, certain com pli cated measurements or computations are to be performed. Thus relatively simple and attainable analysis methods of chicken egg shape variability were chosen and used for the purpose of presented research. Sample of 250 eggs of ISA BROWN strain was examined. Geometrical parameters were measured and calculated with following expression of their coeffi cient of variation -namely egg length 3.56 %, egg maximum width 2.84 %, shape index 3.80 %, surface area 5.08 %, and egg volume 7.23 %. The second method consisted in shape quantitative measuring by the score of the principal components of elliptic Fourier descriptors (EFDs). The fi rst four principles components which could explain over 99 % of the egg shape variations were found to be very good measures of the monitored phenomenon. It was found that 87.41 % of the total shape variation can be accounted to length to width ratio. Usefulness and relevance of the shape index usage was confi rmed. chicken egg, shape variability, elliptic Fourier analysis

The objective of this study is to measure how the viscosity of engine oil changes with temperature. Six different commercially distributed engine oils (primarily intended for motorcycle engines) of 10W–40 viscosity grade have been evaluated. Four of the oils were of synthetic type, two of semi–synthetic type. All oils have been assumed to be Newtonian fluids, thus flow curves have not been determined. Oils have been cooled to below zero temperatures and under controlled temperature regulation, kinematic viscosity (mm2 / s) have been measured in the range of −5 °C and +115 °C. Anton Paar digital viscometer with concentric cylinders geometry has been used. In accordance with expected behavior, kinematic viscosity of all oils was decreasing with increasing temperature. Viscosity was found to be independent on oil’s density. Temperature dependence has been modeled using se­ve­ral mathematical models – Vogel equation, Arrhenius equation, polynomial, and Gaussian equation. The best match between experimental and computed data has been achieved for Gaussian equation (R2 = 0.9993). Knowledge of viscosity behavior of an engine oil as a function of its temperature is of great importance, especially when considering running efficiency and performance of combustion engines. Proposed models can be used for description and prediction of rheological behavior of engine oils.

Standard chemical analysis was performed to characterise six samples of bottled wines from South Moravia. Temperature influence (range from 20 °C to 50 °C). Density data processing led to determination of the expansibility coefficients at 25 °C and their temperature dependence. It was found that, viscosity of wine decreases non-linearly with increasing temperature. Fitting of the experimental data in some theoretical models was performed in order to describe the temperature dependence of the viscosity of wine. A modified Andrade equation was found to best describe this dependence. The activation energy for viscous flow of wine, calculated by Arhenius relation, varied from 18.50 kJ.mol–1 to 20.15 kJ. mol–1. Correlations between the activation energy for viscous flow and the concentrations of solutes other than ethanol were estimated.

MORAVEC, A., VÍTĚZ, T., HAVLÍČEK, M.: Evaluation of one year of operation of the biogas plant in Suchohrdly u Miroslavi. Acta univ. agric. et silvic. Mendel. Brun., 2011, LIX, No. 6, pp. 235-238 The manner of designing biogas plants is eagerly described by each and every seller or supplier of the respective technology. Numerous feasibility studies comprising forecasts of future operation featuring diff erent quality levels have been written. However, it is rarely possible to obtain information comparing the anticipated future numbers and real values. Nevertheless, an evaluation of past operation of BGP is of utmost importance for calibration of the calculation methods used for designing of future BGPs. Information obtained on the basis of an evaluation is also useful for the purpose of verifi cation of correct functionality of the equipment as well as optimisation of its operation with the objective of achieving the planned (or even better) values of profi tability of each respective project. A comprehensive analysis of a biogas plant is a project sensitive to accuracy of inputs. Measurements of amounts and quality of the feed substrate throughout the whole year, which comprises numerous criteria, is highly demanding and complicated, and therefore the objective of this evaluation is to analyze the performance, production and consumption of the biogas plant in the course of a calendar year (Schulz et al., 2004). Power measuring tasks are performed using calibrated gauges (which are mostly used for invoicing purposes), thus ensuring accuracy and credibility of the input data.biogas, anaerobic fermentation, biogas plant Functionality of our society is currently dependent on exploiting of the limited amount of non-renewable resources of energy. The everincreasing energy demands force us to look for a replacement of the non-renewable resources of energy by other (renewable) resources. One of the available alternatives pertains to use of biomass within the process of anaerobic fermentation resulting in creation of biogas that may be further used for energy-related purposes. Anaerobic technologies off er an attractive manner of use of biomass resources for the purpose of partial satisfying of the energy needs of our society (Yadvika et al., 2004). Anaerobic fermentation is a process typical for decomposition of organic matter without in an environment in which air is not present. The total production of biogas comprises mainly transformation of acetic acid to methane and carbon dioxide (70%) while 30% represents transformation of hydrogen and carbon dioxide to methane and water (M. Kaltschmitt et al., 2009;Tirumale and Nand, 1994; Tatar et al., 1998).The analyzed BGP represents a construction project completed on a green fi eld located in the close vicinity of a former livestock production premises. The premises were vacated at the time of construction (2007). At the time of designing of BGP the farmer was fully aware of the synergies pertaining to interconnection of the operation of BGP with livestock produ...

Anaerobic fermentation is a process in which almost any organic mass may be transformed into an energetically rich biogas and a fermentation residue. Only strictly anaerobic microorganisms enter into the process; thus the process may take place only in a hermetically sealed environment. With regard to the world wide situation, where the increase in the proportion of energy from sustainable sources is in demand, anaerobic fermentation offers the possibility of transforming farm waste, farm products and municipality waste of biological character into electricity. This electricity may subsequently become an interesting source of income. The system may be proposed to agricultural companies as well as to municipality corporations. The process of fermentation may be carried out as dry fermentation or as liquid fermentation. Dry fermentation, working with materials where the percentage of dry matter exceeds 15 %, is the topic of this paper. This method has been frequently discussed as a method of processing organic material without waste water and thus the volume of material as well as the size of the biogas plant considerably decreases. To enable progress in the process, it is necessary to use a biologically active liquid solution containing the essential micro-organisms, often termed “percolate”. To activate a fresh substrate, fermented material adulterant containing cultivated microorganisms from previous processes is used; the ratio in which it is used is approximately one third to one fifth. “Percolate strategy” is another phrase used for sustaining the anaerobic fermentation; material is sprinkled on the percolate in the precisely defined cycles. In addition, the biologically active liquid solution contains organic substances washed out from the fermented material. With regard to its amount, this paper has become an impulse for the research in the amount of biogas which may be subsequently produced from the percolate in the so-called biofilm reactor. An external reactor with a cultivated bacterial biofilm on an immovable carrier with the percolate flowing through it has been constructed in laboratory conditions for this purpose. The choice of suitable percolate strategy (this means the frequency of sprinkling) and the amount of percolate directly influences the process of anaerobic fermentation.