The characteristics of combustion process of diesel engine using vegetable oil methyl esters

Biodiesel is one of the promising renewable, alternative, and environmentally friendly biofuels that can be used in Diesel engine with little or no modification in the engine. The present paper investigates the combustion characteristics of single cylinder, naturally aspirated, air cooled, Diesel engine fueled with pure (100%) methyl ester of rapeseed oil, comparing to the corresponding characteristics when it was driven by diesel fuel. Combustion process analysis for both fuels was done at constant engine speed and at two load levels corresponding to the mean effective pressure of three and six bar. It was also concluded that the test engine can operate without problems, both with that fuel and with a lot of other biofuels and their mixtures that were used during long laboratory research

The characteristics of combustion process of diesel engine using vegetable oil methyl esters

Biodiesel is one of the promising renewable, alternative, and environmentally friendly biofuels that can be used in Diesel engine with little or no modification in the engine. The present paper investigates the combustion characteristics of single cylinder, naturally aspirated, air cooled, Diesel engine fueled with pure (100%) methyl ester of rapeseed oil, comparing to the corresponding characteristics when it was driven by diesel fuel. Combustion process analysis for both fuels was done at constant engine speed and at two load levels corresponding to the mean effective pressure of three and six bar. It was also concluded that the test engine can operate without problems, both with that fuel and with a lot of other biofuels and their mixtures that were used during long laboratory research

Study of microstructure and magnetic properties of optimally annealed R/Q Nd4.5Fe77B18.5 alloy

The rapid-quenched (R/Q) and subsequently optimally annealed Nd-Fe-B alloy with 12 wt% Nd was characterized using the X-Ray diffractometry (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HREM) and superconducting quantum interference device (SQUID) magnetometer. It was found that microstructure of the investigated alloy mainly consist of Fe3B, Nd2Fe14B phases and minor content of α-Fe phase, with mean crystal grain sizes being below 30 nm. The ferromagnetic exchange coupling between the grains of identified hard and soft magnetic phases has direct influence on the magnetic properties as it is illustrated by SQUID hysteresis loop. Correlation of the measured magnetic properties with results of microstructure analysis indicates that the investigated rapid-quenched Nd-Fe-B alloy has the nanocomposite structure in optimal magnetic state

Thermomagnetic analysis of nanocrystalline Nd4.5Fe 77B18.5 alloy

Changes in the phase composition and crystallite size of a rapid quenched Nd4.5Fe77B18.5 alloy, caused by thermomagnetic measurements (TM) have been studied using XRD methods of phase analysis, crystallite size and lattice microstrain determination. Structural changes in regard to optimal magnetic state were additionally analyzed by TEM. Magnetic properties in optimal magnetic state and after TM were observed using room temperature SQUID measurements. The obtained experimental results suggest the Fe3B/Nd2Fe14B and partly α-Fe nanocomposite structure of the alloy in the optimized magnetic state, with mean crystallite size (< 30 nm). After TM, an increased amount of α-Fe phase, presence of different oxide and Fe-B phases as well as growth of crystallites are found to be the main reasons for the observed quality loss of hard magnetic properties

Study of microstructure and magnetic properties of optimally annealed R/Q Nd4.5Fe77B18.5 alloy

The rapid-quenched (R/Q) and subsequently optimally annealed Nd-Fe-B alloy with 12 wt% Nd was characterized using the X-Ray diffractometry (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HREM) and superconducting quantum interference device (SQUID) magnetometer. It was found that microstructure of the investigated alloy mainly consist of Fe3B, Nd2Fe14B phases and minor content of α-Fe phase, with mean crystal grain sizes being below 30 nm. The ferromagnetic exchange coupling between the grains of identified hard and soft magnetic phases has direct influence on the magnetic properties as it is illustrated by SQUID hysteresis loop. Correlation of the measured magnetic properties with results of microstructure analysis indicates that the investigated rapid-quenched Nd-Fe-B alloy has the nanocomposite structure in optimal magnetic state

Hamiltonian walks on Sierpinski and n-simplex fractals

We study Hamiltonian walks (HWs) on Sierpinski and $n$--simplex fractals. Via numerical analysis of exact recursion relations for the number of HWs we calculate the connectivity constant $\omega$ and find the asymptotic behaviour of the number of HWs. Depending on whether or not the polymer collapse transition is possible on a studied lattice, different scaling relations for the number of HWs are obtained. These relations are in general different from the well-known form characteristic of homogeneous lattices which has thus far been assumed to hold for fractal lattices too.Comment: 22 pages, 6 figures; final versio

Polymer-Bonded Magnetic Materials with Various Nd-Fe-B Filler Content

One of the more important developments in magnetic materials, polymer bonded magnets, have opened a new world of application opportunities. The Nd-Fe-B/polymer composite materials offer an excellent combination of strong magnetic and dynamical-mechanical properties. However, the transition temperatures of filler and matrix should be selected carefully considering the future application. Uniform particle distribution and good adhesion between Nd-Fe-B powder particles and polymer are essential for the quality of the composite, while stiffness of polymer matrix is one of the influencing factors as well. The damping properties of Nd-Fe-B/polymer composites with 15 wt.%, 50 wt.% and 75 wt.% of Nd-Fe-B powder were studied by dynamic mechanical analysis and compared with a pure polymer sample. Thermal stability was analyzed using a simultaneous differential scanning calorimetric and thermogravimetric analysis technique.11th Annual Conference of the Materials-Research-Society-of-Serbia (YUCOMAT 2009), Aug 31-Sep 04, 2009, Herceg Novi, Montenegr

No systematic effects of sampling direction on climate-growth relationships in a large-scale, multi-species tree-ring data set

Ring-width series are important for diverse fields of research such as the study of past climate, forest ecology, forest genetics, and the determination of origin (dendro-provenancing) or dating of archaeological objects. Recent research suggests diverging climate-growth relationships in tree-rings due to the cardinal direction of extracting the tree cores (i.e. direction-specific effect). This presents an understudied source of bias that potentially affects many data sets in tree-ring research. In this study, we investigated possible direction-specific growth variability based on an international (10 countries), multi-species (8 species) tree-ring width network encompassing 22 sites. To estimate the effect of direction-specific growth variability on climate-growth relationships, we applied a combination of three methods: An analysis of signal strength differences, a Principal Component Gradient Analysis and a test on the direction-specific differences in correlations between indexed ring-widths series and climate variables. We found no evidence for systematic direction-specific effects on tree radial growth variability in high-pass filtered ring-width series. In addition, direction-specific growth showed only marginal effects on climate-growth correlations. These findings therefore indicate that there is no consistent bias caused by coring direction in data sets used for diverse dendrochronological applications on relatively mesic sites within forests in flat terrain, as were studied here. However, in extremely dry, warm or cold environments, or on steep slopes, and for different life-forms such as shrubs, further research is advisable.</p

Nutritional and sensory properties of frankfurters made of culled goat meat

The aim of this research was to evaluate the nutritional and sensory properties of frankfurters with different ratios of culled goat meat as beef replacement during a 6-week storage period. Five treatments of frankfurters were prepared: control treatment (CON) with beef, while in other treatments beef was replaced with 25% (G25), 50% (G50), 75% (G75) and 100% (G100) of culled goat meat. Formulation (and storage) had no influence on energetic values, which were within the interval of 193-200 kcal/100 g, representing more than 30% lower values than those reported for frankfurters with the regular fat content. With the increase of goat meat content, the atherogenic and thrombogenic indices were lower, indicating more favorable fatty acid profiles. Moreover, the ratio of essential and nonessential amino acids increased with the higher goat meat content (from 0.62 in CON to 0.71 in G100) indicating better nutritional properties. Frankfurter formulation and storage (and their interaction) did not significantly influence any of the observed sensory properties, which indicates that culled goat meat can be used as the sole meat in frankfurter preparation