Comparability of the biodynamic production system regarding agronomic, environmental and quality parametersMatjaž Turinek
, 2011, doktorska disertacija
Opis: Biodynamic (BD) agriculture became the subject of research efforts during the last decades, whereas a part of the scientific community looks at the BD method with skepticism and marks it as dogmatic. Summarized data of published research studies showed that further research is needed in the field of food quality comparison/determination, food safety and the environmental performance (e.g. foot prints). In this sense, yields, agronomic efficiency (AE) in relation to yields in some crops and the earthworm populations depending on those crops remain to be explored under the BD production system (PS). Therefore wheat, cabbage and oil pumpkins (rotation 1) and spelt, red beet and false flax (rotation 2) were produced in three successive years (2008-2010) under 4 PS (conventional (CON), integrated (INT), organic (ORG) and BD) + control plots in a field trial near Maribor, Slovenia. Earthworms were determined in rotation 1 in October 2009 and 2010 using the „hot“mustard-extraction method. Yields in the BD PS amounted to 99, 113 and 124 percent of the average yields of all PS for wheat, cabbage and oil pumpkin seeds, respectively. Also AE of N, Nmin, P and K of the BD system for the production of all crops studied in rotation 1 was in the upper half of all PS under investigation. Moreover, earthworm populations and biomass were highest and on a similar level in the BD and ORG systems in all three crops investigated, where most were found in oil pumpkins. In the second step the ecological footprint of PS under study was calculated for wheat and spelt production and interpreted using the SPIonExcel tool. Three-year results show a markedly lower ecological footprint of the ORG and BD systems in production of both crops, mainly due to non-use of external production factors. When yields are added to the equation, the ORG and BD systems also have a lower overall footprint per product unit and ecological efficiency of production. Thus, ORG and BD systems present viable alternatives in facing environmental degradation and climate change in cereal production. However, room for improvement exists in the area of machinery use in all systems studied and yield improvement in the ORG farming system. Moreover, the importance of food quality has increased, but there remains a lack of research in this field, including sensory quality. Thus, in the third step, yields and sensory properties of white cabbage and red beet were examined in 2008 and 2009. Yields did not differ significantly among PS. A total of 167 consumers scored four attributes (color, odor, taste, and willingness to buy) using a nine-point hedonic scale. Results show significant differences between PS for both crops, where INT and control cabbage was preferred over CON cabbage samples (BD and ORG in-between), whereas BD and control red beet was preferred over CON and INT samples (ORG in-between). Lastly, the contents of sugars, organic acids, total phenolic content and the antioxidant activity were quantified in the flesh of red beet samples from 2009 using established methods. Significant differences were measured for malic acid, total phenolic content (TPC) and total antioxidant activity, where malic acid content ranged from 2.39 g kg-1 FW (control) to 1.63 g kg-1 FW (CON, ORG and INT). Highest TPC was measured in BD and control samples (0.677 and 0.672 mg GAE g-1, respectively), lowest in CON samples (0.511 mg GAE g-1). Antioxidant activity was positively correlated with TPC (r2=0.6187) and ranged from 0.823 µM TE g-1 FW to 1.270 µM TE g-1 FW in CON and BD samples, respectively, whereas total sugar content ranged from 21.03 g kg-1 FW (CON) to 31.58 g kg-1 FW (BD). The importance of the measured constituents for human health, as well as for plant resilience and health is discussed and put into perspective. Thus, the BD PS presents a viable alternative to the nowadays predominant CON and INT PS for the production of the studied crops under the Slovene subcontinental temperate climate.
Ključne besede: biodynamic farming, agronomic efficiency, earthworms, ecological footprint, sensory quality, chemical composition
Objavljeno: 31.03.2011; Ogledov: 3586; Prenosov: 445
Polno besedilo (1,03 MB)
The impact of mineral composition on compressibility of saturated soilsBojana Dolinar
, 2006, izvirni znanstveni članek
Opis: This article analyses the impact of soils` mineral composition on their compressibility. Physical and chemical properties of minerals which influence the quantity of intergrain water in soils and, consequently, the compressibility of soils are established by considering the previous theoretical findings. Test results obtained on artificially prepared samples are used to determine the analytical relationship between the water content and stress state, depending on the mineralogical properties of the soils. A practical applicability of the established interdependence is verified on fiverandomly selected samples of natural soils. The selected approach to the analysis of the influence of soils composition on the water content at different stress states allows for the first time to establish generally validcriteria for determining such relationship.
Ključne besede: soil mechanics, clays, specific surface, compressibility, mineral composition
Objavljeno: 30.05.2012; Ogledov: 626; Prenosov: 4
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Bottle model of colour vision with the colour brown as an exampleMatej Erjavec
, Nataša Vaupotič
, 2006, izvirni znanstveni članek
Opis: In this paper, a model to teach colour vision is presented. Three different types of the cones that enable colour vision are visualized as bottles, and the amount the different bottles are filled is associated with the appearance of colour that is formed by the brain. It is shown that the appearance of colour depends both on the relative and the absolute filling of the bottles. We focus on the spectral composition of light reflected from brown surfaces and show that when we see brown, there is usually red, yellow, orange and green light falling into our eyes, but of low intensity. The same spectral composition of the incident light would give the impression of orange colour if the intensity of light were higher.
Ključne besede: colours, colour vision, brown colour, colour combinations, spectral composition
Objavljeno: 07.06.2012; Ogledov: 1192; Prenosov: 13
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UNITED NATIONS HUMAN RIGHTS COUNCIL - HISTORY, PRESENT, FUTUREKlementina Dolinšek
, 2014, diplomsko delo
Opis: While one of the greatest achievements of the United Nations has been the creation of international human rights norms and standards, its human rights protection mechanisms have failed to fulfil their mandate. In the early 2000’s, the Commission on Human Rights, as the major United Nations body working to promote and protect human rights, started to lose its credibility. It was criticised by a wide spectrum of the international community including states, non – governmental organizations and academics for its politicisation and polarisation, double standards, loss of focus, ineffectual decision making and a dubious membership composition. As a consequence of persistent negative responses, in June 2006 the Commission on Human Rights was replaced by the Human Rights Council, in an attempt to create a credible United Nations human rights body. This thesis focuses on the institutional differences between both bodies, their application in practice, and the advantages and disadvantages of the new human rights watchdog. In order to provide as comprehensive a comparison as possible, the research also includes examination of various United Nations documents, media postings, contributions made by non – governmental organizations, and academic studies.
Ključne besede: Commission on Human Rights, Human Rights Council, criticism, advantage, disadvantage, membership composition, politicisation, credibility, losing focus, Universal Periodic Review.
Objavljeno: 08.05.2014; Ogledov: 573; Prenosov: 55
Polno besedilo (1,16 MB)
Scenario development and application of basic art principles in the design of a children’s short storyTamara Domuzin
, 2014, magistrsko delo/naloga
Opis: The purpose of the Masther thesis is to gain more detailed insight into subjects of children's literature and theory of art. While researching the field of children's literature, a great importance has been given to finding the typical characters that form the cast of children stories, as well as the basic elements and development of the typical plot. These principles have been followed in the first section of empirical part - writing a children's short story. While researching the theory of art, the purpose was to gain knowledge of visual elements of composition and principles of design, that have been used in the second section of empirical part - creating illustrations for specific scenes of the story.
Ključne besede: children's literature, scenario development, art theory, composition
Objavljeno: 19.02.2015; Ogledov: 378; Prenosov: 19
Polno besedilo (5,60 MB)
Exergy analysis of a Brayton cycle with variable physical properties and variable composition of working substanceMarija Živić
, Antun Galović
, Jurij Avsec
, Mario Holik
, 2016, izvirni znanstveni članek
Opis: The exergy analysis of a Brayton cycle is performed in the paper. The four input variables: the ratio of the compressor exit and inlet pressures, the ratio of inlet temperature of gases in turbine and inlet temperature of air in compressor and the isentropic efficiencies of the compressor and turbine are analysed. The temperature ratio is varied in a way that the compressor inlet temperature of air is maintained constant, while the turbine inlet temperature of flue gases is varied from 900 to 1200°C. In the combustion chamber methane is completely combusted with excess air ratio which is determined by the temperature of flue gases at the turbine inlet. The analysis further includes variability of the molar heat capacities of air and flue gases with temperature and variability of their heat capacity ratios. The exergy destruction in turbine, compressor and combustion chamber and also total exergy efficiency of the cycle are considered in the analysis.
Ključne besede: Brayton cycle, variable physical properties, variable composition of working substance, maximum work output, maximum thermal efficiency
Objavljeno: 12.07.2017; Ogledov: 199; Prenosov: 6
Polno besedilo (789,62 KB)