Multi-variable selection of the main mine shaft location

Selecting the location of the main mine shaft is a demanding multi-criteria task. The solution does not depend only on identification of the potential location for the construction and the criteria conditions set for the selection, but also on the applied procedure in the analysis. Since there is no general scientific agreement on the selection of the most suitable quantitative method for the support to decision making for this type of analyses, the problem is becoming even more complex. In terms of the Velenje Mine shaft location, the authors describe the approach that can be an exit from this situation. The idea of an approach is not the selection of the most suitable decision making support method but a multi-model procedure where several multi-criteria methods are being used simultaneously. In case when the techniques do not yield the same order of alternatives, it is advised to generate the final order using the method of ponderation.     

Extracting information from the molten salt database

Molten salt technology is a catchall phrase that includes some very diverse technologies; electrochemistry, heat transfer, chemical oxidation/reduction baths, and nuclear reactors. All of these technologies are linked by the general characteristics of molten salts that can function as solvents, have good heat-transfer characteristics, function like a fluid, can attain very high temperatures, can conduct electricity, and also may have chemical catalytic properties. The Janz molten salt database is the most comprehensive compilation of property data about molten salts available today and is widely used for both fundamental and applied purposes. Databases are traditionally viewed as “static” documents that are used in a “search and retrieval” mode. These static data can be transformed by informatics and data mining tools into a dynamic dataset for analysis of the properties of the, materials and for making predictions. While this approch has been successful in the chemical and biochemical sciences in searching for and establishing structure-property relationships, it is not widely used in the materials science community. Because the design of the original molten salt database was not oriented toward this informatics goal, it was essential to evaluate this dataset in terms of data mining standards. Two techniques were used—a projection (principal components analysis (PCA)) and a predictive method (partial least squares (PLS))—in conjunction with fundamental knowledge acquired from the long-term practice of molten salt chemistry. This article is based on a presentation made in the symposium entitled “Fourth International Alloy Conference,” which occurred in Kos, Greece, from June 26 to July 1, 2005, and was Sponsored by Engineering Conferences International (ECI) and co-sponsored by Lawrence Livermore National Laboratory and Naval Research Laboratory, United Kingdom.     

Intrinsic Equilibrium Constants of beta;-Silicon Carbide Obtained from Surface Charge Data

The surface charge behavior of β-SiC in KNO₃ electrolyte solutions is reported as a function of pH and ionic strength. The surface charge densities were obtained by potentiometric titration, and the point of zero charge of β-SiC was determined by the batch equilibration method. The intrinsic equilibrium constants, describing association-dissociation of surface groups, were calculated using the site-binding model.     

Supercritical carbon dioxide extraction of antioxidant fractions from selected Lamiaceae herbs and their antioxidant capacity

Antioxidant fractions from four herb spices belonging to the Lamiaceae family: rosemary (Rosmarinus officinalis), sage (Salvia officinalis), thyme (Thymus vulgaris) and hyssop (Hyssop officinalis) were isolated using supercritical CO₂ at 35 MPa and 100 °C. The antioxidant fractions were characterized chemically by HPLC-DAD/ESI-ToF-MS. Antioxidant activity of obtained extracts was determined by measuring their ability to scavenge stable 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical and reactive hydroxyl radical during the Fenton reaction trapped by 5,5-dimethyl-1-pyroline-N-oxide (DMPO), using electron spin resonance (ESR) spectroscopy. The antioxidant activity of the extracts was compared to the activity of butylated hydroxyanisole (BHA) and Flavor' Plus? water-soluble rosemary extract. In DPPH radical assay the order from the strongest to the weakest antioxidant activity was: BHA, thyme extract, Flavor' Plus?, rosemary and sage extracts, and hyssop extract, while in hydroxyl radical assay order was: Flavor' Plus?, sage extract, rosemary extract, hyssop extract, BHA and thyme extract.Industrial relevanceSpices and herbs have been used not only for flavoring food but also for improving the overall quality of the product and to extend the shelf-life of foods. The present investigation relates to the field of food additives, and particularly to an antioxidant fractions from four herb spices which belong to the Lamiaceae family: rosemary (Rosmarinus officinalis), sage (Salvia officinalis), thyme (Thymus vulgaris) and hyssop (Hyssop officinalis). Butylated hydroxyanisole (BHA) and Flavor' Plus? are used in food industry as antioxidants due to their ability to prolong the shelf-life of foodstuffs by protecting them against deterioration caused by oxidation, such as fat rancidity, colour changes, degradation of the flavor and loss of nutrient value. Synthetic antioxidants such as BHA now being replaced by natural antioxidants because of their possible toxicity and due to a suspected action as promoters of carcinogens. The present study confirms that investigated herb spices belonging to the Lamiaceae family present important sources for the production of food additives.     

Melt rheology of aliphatic hyperbranched polyesters

Rheological behavior in melt of aliphatic hyperbranched polyesters (AHBP), synthesized using pseudo‐one‐step and one‐step procedure, was investigated in this work. Three commercially available AHBP were also examined. Because of the presence of relatively strong hydrogen bonds between numerous end hydroxyl groups, AHBP of lower generation number, as well as the sample of tenth pseudo generation, show non‐Newtonian behavior in the entire investigated frequency and temperature region. However, for other examined AHBP, the slope of the frequency dependence of complex viscosity (η* = f(ω)) becomes smaller with the temperature increase. Therefore, samples of fourth, fifth, and sixth pseudo generations show Newtonian behavior at temperatures higher than 70°C. Value of glass transition temperature, melt flow activation energy, fractional free volume, and thermal expansion coefficient were determined for the investigated AHBP. The influence of the type of end groups on rheological properties of AHBP was also examined. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Leakage quantification of compressed air using ultrasound and infrared thermography

With the leakage elimination in compressed air systems, it is possible to save up to 40% of energy. With appropriate inspection and maintenance of compressed air systems, leakage elimination should be a routine. This paper describes and compares two different noncontact methods for compressed air leakage quantification, ultrasound and infrared thermography. The potentials and limitations of these technologies are analyzed, as well as the reliability and accuracy of results thus obtained. From the results presented in this paper, it can be concluded that thermography offers good results for the leakage quantification from the orifices greater than 1.0 mm and ultrasound should be used for leakage detection for all the dimensions of orifices, but for the quantification purposes only for smaller leaks. As a support for leakage quantification, we proposed diagrams of a leak flow as a function of sound level and as a function of detected temperature change.     

Optimized planar printed UCA configurations for OAM waves and the associated OAM mode content at the receiver

Utilization of planar printed uniform circular antenna arrays (UCA) to generate the orbital angular momentum (OAM) carrying waves in the millimeter-wave (mmWave) frequency band is advantageous from the viewpoints of easy signal modulation and mode reconfiguration, low cost, low profile, and straightforward integration with the existing broadband wireless infrastructure. The OAM mmWave UCA are highly promising as the enablers of very high transmission data rates required by hybrid 5G/6G optical and wireless communication systems by complementing and enhancing other technologies currently in use. Therefore, we here contribute a detailed electromagnetic analysis of important constraints of such antenna arrangements aimed at short-range multimode OAM wave transmission. We investigate (i) the required antenna array dimensions and optimized UCA arrangements for a particular link range and (ii) the corresponding mode structure of OAM waves in the plane of receiving arrays. Four relatively simple antenna configurations operating in the 60-GHz band are compared. Theoretical assumptions based on ideal OAM modes are critically assessed and, using state-of-the-art numerical electromagnetic analysis, compared to realistically generated OAM waves. The proposed “cyclic transmission setup” resulted in much lower unwanted field components in the region of receiving arrays. RMS magnitudes of unwanted modes are on average about 64% of the received mode, in comparison with 80% (up to 94%) for sequential transmission. The observed mode impurities and mode mixing effects at the receiver indicate the need to dedicate more attention to the system-level design, the development of efficient receiving arrays, the MIMO processing, and the stream separation.     

Precocial rodents as new experimental model to study the effects of altered gravitational conditions on fetal development

So far the experiments in altered gravitational conditions on the prenatal development have used altricial rodent species. The aim of this study is to explore the differences in the intrauterine development of locomotor system in precocial (guinea pig, spiny mouse) and altricial (rat, mouse, and golden hamster) rodent species and to determine which of these mammalian groups represent a better study model to conduct research on the influence of altered gravitational conditions on human fetal development. Findings suggest that the influence of altered gravitational conditions on development of locomotor system significantly vary according to the maturity of mammals. By the characteristics of maturity at birth precocial rodents are more similar to a human than altricial species. Since precocial species have similar maturity of locomotor system to human, the changes caused by altered gravity among them should be similar as opposed to altricial species.