Journal of Engineering & Processing Management (EPM)
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TRANSIENT VIBRATION ANALYSIS OF A TURNING MACHINE, S SPINDLE
Full text linkSpindle is one of the most important member in turning machines, so that its precision determines the dimensional tolerances of machined parts. In this paper, the spindle’s response to standard input parameters has been analyzed via Finite Element Method (FEM).From this point of view, the spindle of LZ330VS turning type machine is modeled with Solid Works software. Then, the model is meshed via Msc-Patran software and analyzed by ANSYS. Four values which are the same for all inputs are applied to each one to study the affection of input parameters on the model, simultaneously. The results show that increasing in applied loads increases the oscillating dominations. The value of applied forces has also more affection than the applying time and input type on the oscillating dominations
HEAT TRANSFER THROUGH FLAT WALLS COMPLEX PROMBLEMS SOLVING BY ELECTRICAL ANALOGY
Full text linkStarting from the Fourier's law for stationary heat transfer and Ohm's law for DC through the resistor, the paper presents the analogy between thermodynamic and electrical quantities. Based on this analogy, has been used knowledge of circuit theory for of the heat transfer through walls in the multilayer characteristic positions to derive the schematic representation of corresponding heat resistors. At the end of paper, has been shown two typical examples of calculation heat transfer to the complex multi-layer walls in different positions, by applied electrical analogy.Heat transfer, Electrical analogy, Heat resistance, Electrical resistance, Equivalent systems
A FUNCTION PROPERTY OF POLYTROPHIC PROCESS WITH ASPECT OF TANGENT CONSTRUCTION
Full text linkIn this paper, starting from general tangent equation in arbitrary point of specified curve, using principles of differential geometry and given mathematical transformation tangent equation of polytrophic function in p – v diagram was obtained. This form is convenient for solving numerous practical and theoretical problems in engineering thermodynamic by means of graphical method. It was shown that tangent can be constructed easily, using polytrophic equation only, but it is not example with other functions appearing in thermodynamics. Later, in this paper, we have given some methods, which refer to more exact construction of polytrophic and graphical analyze of polytrophic process
PRESSURE INFLUENCE TO EXTRACTION SYSTEM HELICHRYSUM ITALICUM – SUPERCRITICAL CARBON DIOXIDE
Full text linkSupercritical fluid extraction (SFE) is an efficient extraction technique for the separation of various organic compounds from herbs, or more generally, from plant materials. As cultivate plant (plant from plantation) Helichrysum italicum from municipality Novi Grad was used in this research. The influence of pressure on total extract yield at flow rate 53.5 dm3 /h (calculated at normal state), for extraction time 3 h was investigated. Extraction was performed by supercritical carbon dioxide at different pressures (80, 150, 250 and 350 bar) and constant temperature of 40°C. The extraction yield increase from 0.35 to 5.71% (g/100g drug) by pressure increasing of supercritical extraction by carbon dioxide (isothermal process, t = 40°C). Essential oil content in obtained CO2 extracts was from 6.70 to 31.12%. The highest content of essential oil was in CO2 extract obtained by extraction of drug at p = 80 bar and t = 40°C (31.12%). Qualitative and quantitative determination of CO2 extracts obtained at pressure of 80 and 350 bar as well as of essential oils obtained from extracts, were performed using GC - MS method. The main component were tritriacontane (27.13%) and nonacosane (13.28%). The dominant component in essential oils obtained from extracts was γ – curcumene (28.27 and 27.42%, respectively)
CONTEMPORARY SUPERCONDUTIVITY MATERIALS
Full text linkIn this paper will be introduced the newest research in high-temperature superconducting materials. In the first part of the paper will be analyzed discovery of superconductivity and the phenomena and effects related with this topic and the superconducting materials as well. In the second part of the paper will be analyzed our research of nanostructure superconductivity, where we will introduce the model of the ultra-thin films, quantum wires and quantum dots. In the end, we will analyze thermodynamic and transport properties, achieved results and perspectives for the future research
SELF-STRUCTURED SILVER ALLOY COATINGS AND THEIR PROPERTIES
Full text linkThe co-deposition of silver with less noble metals results at low current densities in pure silver coatings or solid solutions of these metals in silver. At high current densities, after saturation of the silver lattice with the alloying metal a new richer in this element phase is formed and heterogeneous coatings are obtained. The spontaneous deposition of different phases is sometimes connected with electrochemical instabilities and oscillation phenomena leading to formation of periodically ordered spatio-temporal structures on the surface of the electrode. The spreading of waves of different metal composition over the electrode could result in the spontaneous formation of multilayered coatings, which combine the properties of the phases of the different sublayer. The possibility of spontaneous formation of heterogeneous periodic self-structured coatings in microand nano-scale, based on silver alloys with antimony, bismuth, indium, tin, cadmium and other metals without applying external pulses is shown. The effect of electrolysis conditions on the morphology, internal stress, microhardness, electrical contact resistance, wear resistance, roughness and friction properties of the obtained alloy coatings is studied and some properties of the deposited layers are compared and discussed
THE DETERMINATIONS OF TOTAL ACIDS IN RED WINE
Full text linkThe amount of total acids in must is in most number of cases between 5 and 8 g/dm3 . Wines in general possess a little fewer acids than must, by Regulation the least acidity, expressed as tartaric acid is for all kinds of wine 4.5 g/dm3 , because a part of tartaric acids sediments as salt (tartar) in the process of the alcohol fermentation. For wines that possess less than 4 g/dm3 of total acids there is a doubt are they of natural background. Because of that the aim of this work was determination of total acids in diferent sorts of red wines and to determinate their background using gained data. For determinating total acids in white wine neutralization method was used. As potentiometric titration for pH 7.00 is precise and accurate method and values of content of total acids in wine, exppressed by tartaric acid, are given by these results. The analisys of differential potentiometric curves indicates that these curves can give the answer to the questions: are there inorganic supstances, amino groups and phenols present in analised samples