Comparative analysis of the results of theoretical and experimental studies of freight wagon Sdggmrss-twin

This paper presents a comparative analysis based on the results from static strength calculation of wagon body, series Sdggmrss-twin, and on the results from the real wagon test. The verification of results from calculations and tests and their comparison was mandatory for client's commissioning of the wagon by notified body. Calculations based on the finite elements method were carried out in the Department of Railway Engineering at Technical University of Sofia. Experimental studies on real wagon construction were conducted at the facilities of Bulgarian National Transport Research Institute by testing team from Laboratory of rail vehicles at University of Belgrade. It was found that the obtained static stress results are similar, which proves that the proposed models are appropriate and they can help to solve a wide range of issues, for example those related to lightweight design of railway vehicles

Comparative analysis of the results of theoretical and experimental studies of freight wagon Sdggmrss-twin

This paper presents a comparative analysis based on the results from static strength calculation of wagon body, series Sdggmrss-twin, and on the results from the real wagon test. The verification of results from calculations and tests and their comparison was mandatory for client's commissioning of the wagon by notified body. Calculations based on the finite elements method were carried out in the Department of Railway Engineering at Technical University of Sofia. Experimental studies on real wagon construction were conducted at the facilities of Bulgarian National Transport Research Institute by testing team from Laboratory of rail vehicles at University of Belgrade. It was found that the obtained static stress results are similar, which proves that the proposed models are appropriate and they can help to solve a wide range of issues, for example those related to lightweight design of railway vehicles

Definition the technology method of apatite flotation concentration from the phosphate deposit 'Lisina'

This paper presents the importance of phosphate in the world, and the problems that arise in the process of preparing the low-grade phosphate ore for obtaining the phosphate concentrate using the flotation concentration. The apatite concentrates are obtained using the selective flotation from the silicate and oxide minerals while defining the process of selective flotation of apatite from carbonate deposits is the major problem worldwide. The experimental part of this paper presents the results of laboratory flotation tests of phosphate ore from the surface part of the location 'Panjevica' of the deposit 'Lisina'. The results have enabled definition of the flotation process in continuous conditions of work

Investigation the calcite hydrophobisation of different grain sizes

This paper presents the investigations of possibility of calcite hydrophobisation. Two samples of calcite of different size classes from the site 'Dobar kamen', Arandjelovac, Serbia, were used in the experimental work. Modifying the surface of calcite was carried out by stearic acid with 'dry' method. Concentrations of stearic acid in the modifying method were as follows: 0.3, 0.5, 0.8, 0.9, 1, 2, 2.5, 3 and 4%. The results showed that a complete hydrophobicity (I0=99.9%) of calcite sample with the medium diameter (d50) 10.87 μm was achieved at concentration of stearic acid of 0.8%, while for the sample with the mean grain diameter (d50) of 29.14 μm, it was achieved at concentration of stearic acid of 3%. These results were confirmed by the microscopic analysis

The isovalerate and 2-methylbutanoate of artemisia alcohol–new compounds from Artemisia annua L. essential oil

Artemisia annua L. (sweet wormwood) is an essential oil (EO)-rich, medicinally valuable plant species from the Asteraceae family [1]. During the analysis of the biologically active A. annua EO sample (hydrodistilled from the dry aboveground parts of the plants; oil yield 0.2%, w/w; the main components (relative abundance): artemisia ketone (35.7%), a-pinene (16.7%), 1,8-cineole (5.5%), artemisyl alcohol (4.8%), and trans-pinocarveol (4.8%) [1]), we have detected two minor compounds, AA1 and AA2 (0.06% and less than 0.05% of the total oil, with RI (DB5-MS) values of 1367 and 1373, respectively) with practically identical mass spectral (MS) fragmentation patterns (EI, 70 eV; m/z (rel. int.)): 169(15), 85(100), 57(38), 41(17). The comparison of GC (≈300 unit higher RI values) and MS data of AA1 and AA2 with those of artemisyl acetate (often present in EOs containing artemisia ketone and artemisia alcohol) suggested these might be esters of artemisia alcohol and (isomers of) pentanoic acids. To confirm this tentative identification, and possibly detect some additional AA1 and AA2 homologs, we prepared esters of artemisia alcohol and valeric, isovaleric, 2-methylbutanoic, butanoic, isobutanoic and propanoic acids (Steglich esterification; the starting alcohol was obtained by LiAlH4 reduction of artemisia ketone isolated from the EO). Co-injection of the EO sample with synthetic standards confirmed AA1 and AA2 were artemisyl isovalerate and artemisyl 2-methylbutanoate (diastereomer not determined), respectively (Fig. 1). Detailed re-analysis of the EO revealed the presence of initially undetected trace amounts of artemisyl acetate. The results of this work once again confirm the importance of natural product-inspired libraries of synthetic compounds in the analysis of EOs, especially when it comes to the detection and identification of trace constituents

Reactions of calcite in water in the presence of stearic acid

In the suspension of water and calcite, with pH 10.14, on the border of calcite / water was formed a double electric layer. Its structure, or hydrophilic properties of minerals, depended on the concentration of potential determination ions, Ca2+ i 2 CO3 , pH of the environment, and the adsorption of water molecules and ions (and molecules), formed in a suspension of calcite as a result of its solubility in alkaline media. The structure of such a way formed electrical double layer, influenced on interaction of minerals with stearic acid as a surface of active substance. In the presence of stearic acid, the pH value of slurry decreased to 8.72 due to the dissociation of stearic acid in alkaline medium and reaction of neutralization. As the result of dissociation, in the suspension, besides the un-dissociated acid molecules, there were also stearine ions CH3(CH2)16COO-, (St-), which have reacted with the surface of minerals, transforming it from hydrophilic to hydrophobic

Application of lime in the polyvinyl chloride industry

This paper presents the importance of limestone in a variety of industries with a special focus on the use of limestone as filler in the industry of polyvinyl chloride (PVC). Of Out of all fillers, used in the industry of PVC processing, calcium carbonate type of fillers are 80%. Fillers are used in order to improve various mechanical properties of polymer such as tensile and breaking properties, density, bending strength, hardness, thermal stability, viscosity and more. Latest trends of industrial development and demands of the processing industry for high quality carbonate fillers influenced the implementation process of surface modification limestone and calcite, which is the main constituent of fine micronized limestone in order to enhance its performance

Far infrared and transport properties of single crystal PBTE samples doped with Ce

Single crystal samples of lead telluride doped with cerium were made using the Bridgman technique. Single crystals could be easily cleaved parallel to the (002) plane. Room temperature far infrared reflectivity was measured on single crystal samples and a plasma minimum at about 180 cm(-1) and local modes of Ce were observed. A fitting procedure based on a modified four parameter model of plasmon - phonon interaction, was used to determine the values of optical parameters. Carrier concentration and their mobility were measured at room and liquid nitrogen temperatures.Romanian Conference on Advanced Materials (ROCAM 2000), Bucharest, ROMANIA, october 23-25th, 2000

Nutritional strategies in prevention of negative effects of mycotoxins in monogastric animals

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