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Influence of biodiesel on injection, fuel spray, and engine characteristics
Breda Kegl, Stanislav Pehan, 2008, izvirni znanstveni članek

Opis: This paper discusses the influence of biodiesel on the injection, spray, and engine characteristics with the aim to reduce harmful emissions. The considered engine is a bus diesel engine with injection M system. The injection, fuel spray, and engine characteristics, obtained with biodiesel, are compared to those obtained with mineral diesel under peak torque and ratedconditions. The considered fuel is neat biodiesel from rapeseed oil. Its density, viscosity, surface tension, and sound velocity are determined experimentally and compared to those of mineral diesel. The experimentally obtained results are used to analyze the most important injection, fuel spray, and engine characteristics. Furthermore, the influence of biodiesel usage on lubrication is presented briefly. The results indicate that, by using biodiesel, harmful emissions (NOx, CO, HC, smoke, and PM) can be reduced to some extent by adjusting the injection pump timing properly while keeping other engine characteristics within acceptable limits. Furthermore, the results indicate better lubrication conditions when biodiesel is used.
Ključne besede: biodiesel, diesel engine, injection characteristics, fuel spray, emission, lubrication
Objavljeno: 31.05.2012; Ogledov: 1193; Prenosov: 233
.pdf Celotno besedilo (1,50 MB)
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Experimental analysis of injection characteristics using biodiesel fuel
Breda Kegl, Aleš Hribernik, 2006, izvirni znanstveni članek

Opis: This paper deals with injection characteristics using different fuels at different fuel temperatures. The fuels under consideration are neat biodiesel from rapeseed oil and some blends with diesel as well as neat mineral diesel D2. The fuel and fuel temperature influences are investigated experimentally in the mechanically controlled diesel fuel injection M system. At first, attention is focused on the injection characteristics, especially on fuelling, mean injection rate, mean injection pressure, injection timing, injection delay, and injection duration, which influence the most important engine characteristics. Furthermore, the influence of fuel temperature is investigated. On the basis of the measurements of pressure drop through the fuel filter, the minimum fuel temperature for safe engine operation is determined.
Ključne besede: internal combustion engines, fuel blends, biodiesel fuel, temperature influence, injection characteristics
Objavljeno: 31.05.2012; Ogledov: 1157; Prenosov: 57
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Impact of magnetic saturation on the steady-state operation of the controlled induction motor
Petar Ljušev, Drago Dolinar, Gorazd Štumberger, 2003, izvirni znanstveni članek

Opis: The paper presents a method for determination of the steady-state torque characteristics of the induction motor in the case of rotor field-oriented control (RFOC) with nonlinear magnetizing characteristic of the iron core included. The torque characteristics are determined for the constant stator current and the constant d-axis stator current. The characteristics obtained at a constant stator current are used to maximize the torque capability of the RFOC induction motor. The aim of the presented work is to obtain required steady-state torque with minimal stator current. Experiments show that the proposed selection of a magnetizing reference is promising.
Ključne besede: induction motor, torque characteristics, magentic saturation
Objavljeno: 01.06.2012; Ogledov: 1000; Prenosov: 14
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Energy metabolism, growth performance, body composition, meat quality and boar taint compounds in immunocastrated pigs
Nina Batorek Lukač, 2015, doktorsko delo/naloga

Opis: In recent years, immunocastration, a vaccination against gonadotropin releasing hormone, has been proposed as an alternative to surgical castration of intact male pigs without anaesthesia. However, the effects of immunocastration on metabolic changes, nutritional requirements and growth potential have not been quantified. Thus in the present thesis, the meta-analytical approach was used to quantitatively synthesize the effects of immunocastration and four studies were conducted to evaluate the effects of quantitative and qualitative feed restriction on growth performance, heat production and energy metabolism, carcass and meat quality. Results show that boar taint compounds are dramatically reduced in immunocastrates, still they remain slightly higher than in surgical castrates. Immunocastrates are less feed efficient, fatter but grow more rapidly and may have better meat quality than entire males. Compared to surgical castrates, immunocastrates have superior performance with no difference in meat quality. It is more economical to fatten immunocastrates than surgical castrates, but production costs and carcass quality are less favourable than in entire males because of the huge increase in voluntary feed intake during the weeks preceding slaughter. Applying quantitative feed restriction after active immunization did not significantly affect growth performance or carcass composition; however, restrictively fed immunocastrates were closer to entire males, whereas ad libitum fed immunocastrates were closer to surgical castrates. Meat quality is also unchanged by the restriction. However, higher incidence of carcass lesions in restricted immunocastrates together with higher plasma cortisol level indicates more aggression prior to slaughter and can be considered as a negative aspect of the quantitative restriction. Total heat production, assumed to be the major factor contributing to the differences in feed efficiency of pigs, is changed after the immunocastration. Additional energy retained due to higher feed intake is directed towards lipid deposition. Increased fatness of immunocastrates is a result of increased daily lipid deposition caused by higher energy intake, lower fasting heat production and improved energy retention. Hence, dietary energy intake should be limited after immunocastration. Moreover, according to the results of the nitrogen balance study, dietary crude protein content could also be decreased. By reducing net energy concentration of the diet up to 10 % using higher fibre content, similar energy efficiency (gain to net energy intake ratio) may be achieved, with an advantage in terms of reduced lipid deposition, and no effect on growth rate after effective immunization. This is particularly important when immunocastrated pigs are fattened to higher body weights, i.e. when longer delays between full immunization and slaughter are practiced.
Ključne besede: pig, immunocastration, growth performance, carcass characteristics, meat quality, heat production, lipid metabolism, fat deposition, feed restriction
Objavljeno: 27.07.2015; Ogledov: 1516; Prenosov: 117
.pdf Celotno besedilo (19,44 MB)

Using LabVIEW in a flow parameters study
Gorazd Bombek, Matej Fike, 2012, objavljeni znanstveni prispevek na konferenci

Opis: The results of numerical simulations can be validated experimentally, but usually only the aggregate characteristics are compared. If the aggregate and partial characteristics can be compared at the same time, the level of trust is increased and the physics can be studied in detail. This paper presents a modular measurement system incorporating several devices, including a PIV, traverse system, NI CompactRIO and/or a DAQ, which are synchronized and enable the simultaneous acquisition of aggregate and partial parameters at various sampling frequencies. The modular concept allows for easy configuration and adjustments as needed. The high DI sampling frequency achieved by the CompactRIO system enabled the analysis of trigger delay and significantly increased the AI capability of the PIV system.
Ključne besede: flow parameter study, velocity profile, measurements, local partial characteristics
Objavljeno: 10.07.2015; Ogledov: 602; Prenosov: 27
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Ring opening metathesis polymerisation (ROMP) as a tool for polyhipes with extraordinary mechanical properties
Sebastijan Kovačič, 2013, strokovni članek

Opis: PolyHIPE materials have been prepared by Ring Opening Metathesis Polymerisation (ROMP) of dicyclopentadiene. Two characteristic features for successful stabilization of high internal phase emulsions (HIPEs) were tuned in order to achieve improvements regarding mechanical properties of polyHIPEs.Mechanical properties of the new materials were related to variations of the surfactant concentration and the volume ratio of the internal phase in HIPEs. Values for Youngʼs moduli were about a hundred times higher than in standard polyHIPE materials with the same level of porosity, which represents a major improvement for highly porous cellular polymeric materials. Moreover, fully interconnected macroporous morphology was found forpolyHIPEs, where respective HIPEs were stabilized with only 0.25 v% of surfactant.
Ključne besede: emulsion templating, ring opening metathesis polymerization, dicyclopentadiene, ROMP, mechanical characteristics, polyHIPEs
Objavljeno: 21.12.2015; Ogledov: 869; Prenosov: 56
.pdf Celotno besedilo (490,09 KB)
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Danube Region Entrepreneurship Observatory
Polona Tominc, Miroslav Rebernik, Barbara Bradač Hojnik, Karin Širec, znanstvena monografija

Opis: There is no doubt about the importance of multi-country studies of entrepreneurial activity in enabling the comparison and replication of research and generating meaningful contributions to scholarship, practice and policy. This international comparison perspective is especially important when processes in each single economy are analysed against the broader global, European or regional environment. Since entrepreneurship is a complex social phenomenon, several dependencies can be understood only with comprehensive research that includes continuous positioning of national entrepreneurship in the European and global perspectives. Within Global Entrepreneurship Monitor (GEM) it is possible to compare data for more than 100 countries not only in the field of early-stage entrepreneurial activity but also in areas such as general attitudes of the adult population towards entrepreneurship, entrepreneurial intentions, etc. In this scientific monograph publication, we analyse the entrepreneurial profiles of Danube region countries, entrepreneurial intentions in the region and investigate the competition and aspirations of early-stage entrepreneurs in these countries.
Ključne besede: enterprises, entrepreneurship, business environment, characteristics, activities, economic development, human capital, competitivity, international comparisons, Global Entrepreneurship Monitor, Danube Region, Entrepreneurial Intentions, Entrepreneurial Growth Aspirations
Objavljeno: 18.01.2017; Ogledov: 879; Prenosov: 76
.pdf Celotno besedilo (2,97 MB)
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The examination of factors relating to the leadership style of nursing leaders in hospitals
Mateja Lorber, Sonja Treven, Damijan Mumel, 2016, izvirni znanstveni članek

Opis: Theories often describe leadership with different classifications, based on personality and behaviour, and have been used to establish the traits and behaviours that determine an effective leadership style. We used the quantitative methodology to investigate the determinants of the leadership style among nursing leaders in Slovene hospitals. Based on the results, we determined that demographic characteristics such as gender, age, length of employment, and level of education do not affect the choice of the leadership style. Internal organizational characteristics such as job position, emotional intelligence, communication, personal characteristics, and the decision-making process are positively associated with the leadership style. Personal characteristics are considered important when it comes to using specific leadership styles, regardless of the choice of the leadership style, which also depends on the situation and external influences.
Ključne besede: decision-making process, personal characteristics, communication, emotional intelligence, leadership style
Objavljeno: 03.04.2017; Ogledov: 600; Prenosov: 288
.pdf Celotno besedilo (476,79 KB)
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