Applied Mechanics and Materials Vols. 152-154

Abstract: The preparation and application of polyurethane immobilized nitrifying bacteria pellets for surface water treatment was studied. The removal of ammonia nitrogen from micro-polluted source water by polyurethane immobilized nitrobacteria pellets with a stuffing ratio of 10% in volume in an up-flow inner circulation reactor was investigated with the system operated continuously under the following conditions: temperature 20°C--30°C, DO 3--5 mg/L, and pH 7.1--7.3. The continuous removal rates of NH⁴⁺-N remain above 90% and ⁴⁺-N concentration in the produced water was less than 0.5 mg/L with the hydraulic reaction time (HRT) controlled at 0.5 h. The results verified that polyurethane immobilized nitrobacteria pellets have a great potential for micro-polluted source water treatment applications.

Abstract: Self-sterilized complex coatings obtained by Ag@TiO₂incorporation into styrene-acrylic latex, extensively used in interior wall coatings, are prepared via a coupling agent modification process. A microscopy (TEM) study shows that the complex latexs obtained are highly homogeneous at the nanometric scale, exhibiting an intimate contact between both the organic and inorganic components. Ag@TiO₂incorporation into this polymer matrix renders self-sterilized nanocomposite materials upon light excitation, which are tested against Escherichia coli and Staphylococcus aureus. the complex coatings display an impressive performance in the killing of all micro-organisms with a maximum for an oxide content between 2-5 wt %.

Abstract: The qualitative condition and development of the environment in the Košice region is clearly affected by any activity within social development. Anthropogenic activities, especially in the manufacturing industry, negatively impact on the individual components of the environment in particular emissions of contaminants into air, water, soil and rock environment, also due to accidents, waste production and also by remote of agricultural land. It should be noted that among various components of the environment are very tight feedback and mutually influence each other and therefore any decrease in quality of one component as a result of contaminants introduction leading to disruption of ecological balance is automatically reflected in other components of the environment. Increasing the intensity of anthropogenic activities is taking place on one side an increase of environmental burdens through the issuance of a wide range of contaminating substances and exploitation through natural resources which is a manifestation of deterioration of the productivity of the country, of its hygienic and aesthetic values, and on the other side increase in economies may foster environmental protection to finance any corrective measures or to help prevent pollution by using more environmental technologies. The paper deals with the evolution and analysis of the mentioned problems within the Košice region.

Abstract: One way to save fuel is to use renewable energy, including solar, wind, hydro, geothermal and biomass. The use of renewable and alternative energy sources is contributing to environmental protection and nature conservation as a whole and provides a perspective of sustainable development. The aim of this paper is to compare the possibility of increasing the use of alternative and renewable energy sources in Slovakia with neighboring countries. It determines and also identifies the level of the Slovak Republic in the use of renewable energy sources because it is expected to increase by 2020 in each country. This paper is also devoted to the theoretical base of renewable and alternative forms of energy. One part of the paper deals with an analysis and comparison of the state of the use of renewable energy sources in Slovakia and in selected EU countries. Latest part deals with the overall national objectives set by the European Union for the proportion of energy from RES, which will be achieved by 2020. The paper is a partial result of the research project on RES realized at Technical University of Košice (Slovakia).

Abstract: By drop tube and melt spinning techniques, rapid growth of Fe₇Co₃ intermetallic compound has been realized. The microstructures and nucleation characteristics under different cooling rates are investigated. With the increase of cooling rate, Fe₇Co₃ intermetallic compound grains are refined in both rapid growth manners. Experimental observation and theoretical analysis indicate that the nucleation rate in single-roller quenching is much greater than that in free-fall method when the cooling rate is under a same level. The comparison of magnetic property between the alloy ribbons and other dimensional magnetic material were made. The superior soft magnetic properties of Fe-Co alloy ribbons changes sensitively with the cooling rate, which is mainly decided by the wheel velocity.

Abstract: Microcontents of Cl- and SO42- in boric acid were determined by photoelectricity turbidimetry with acid as medium. The effects of stabilizer, acidity of solution, content of precipitant, heating time and temperature as well as measuring time on the turbidity of the solution were studied. After above experiment parameters were optimized, in the measurements to determine SO42- in boric acid, the stabilizer was glycerine-ethanol (1:4), the precipitant was acidic BaCl2. The solution was shaked and heated, as a result, the adding sequence of reagents had no effects on results. The detection limit was 0.10mg/L, relative standard deviation (RSD) was less than 3%, recovery rate was 98.85%~103.00%, and measuring time last over 40min. SO^42- concentration in the range of 0.33 mg/L ~0.83mg/L showed a linear relationship with turbidity. In the determination of chlorine, the stabilizer was glycerine, measuring time held in 40min, detection limit was 0.03mg/L, RSD was less than 4%, and recovery rate was 102.2%~106.5%. Cl^- concentration in the range of 0.10 mg/L ~0.25mg/L showed a linear relationship with turbidity. Photoelectricity turbidimetry improve the precision and accuracy of the measurements. The method of turbidimetry to determine Cl^- and SO^42- in boric acid is simple, reliable, innocuous and applicable in practice.

Abstract: Nanocrystalline silicon (nc-Si:H) grown by hot-wire chemical vapor deposition (HWCVD). We report on the effects of B2H6 doping ratio on the microstructural and optoelectrical properties of the p-type nc-Si:H thin films grown by HWCVD at low substrate temperature of 200 °C. An attempt has been made to elucidate the boron doping mechanism of the p-type nc-Si:H thin films deposited by HWCVD and the correlation between the B2H6 ratio, crystalline volume fraction, optical band gap and dark conductivity. Characterization of these films from Raman spectroscopy revealed that the high conductive film consists of mixed phase of nanocrystalline silicon embedded in an amorphous network. A small increase in B2H6 doping ratio showed marked effect on film microstructure. At the optimal condition, high dark conductivity (8 S/cm) with high optical band gap (~2.0 eV) was obtained.

Abstract: The mesoporous tungsten oxide (WO₃) films were derived from the peroxotungstic acid (PTA) sol with templates through sol-gel method. Polyethylene glycol (PEG) 400 and tri-block polymer P123 (HO(CH₂CH_2O)₂₀(CH₂CH(CH₃)O)₇₀(CH₂CH_2O)₂₀H) were chosen as templates. The structural, morphological, optical and electrochromic properties of the WO₃ thin films derived from different sols were studied. The composition and crystal phase of the films change at different annealing temperatures. The films derived from the sols containing templates have higher crystallization temperature than those without templates. And the morphologies are distinctly different from different sols. The addition of the templates can improve the electrochromic properties of the WO3 films, and those prepared from the 3% of P123 sol show the best electrochromic properties. The highest transmittance modulation is near 60%, and the largest ion inserted and deinserted diffusion coefficient can reach 5.706×10^-12 cm²/s and 1.271×10^-11 cm²/s, respectively.

Abstract: Because steel strips are covered with scales and water during hot-rolling, it is difficult to recognize the defects from images of hot-rolled strips through conventional methods. Principles and characteristics of fractal dimensions were studied, and computation of the fractal dimensions of the defect images with Peleg Covered Carpet is presented. Fractal dimensions of piecewise linearly transformed and smoothed images were used as features for classification of defects. These features were inputted to train the AdaBoost classifier. Experiments with samples of pimples, shells and scales from a real surface inspection system of hot-rolled strips showed that it is effective to recognized scales from other defects, and the total classification rate of this method is higher than 90%.

Abstract: This paper has done CAE analysis of hot stamping, and optimized the water-cooled system which takes the degree of uniform temperature of blank as the objective function of optimization. The aim is to find a method of optimizing hot stamping mold cooling system based on ANSYS Parametric Design Language (APDL) with ANSYS Mechanical/LS-DYNA software and lay the foundation for designing hot stamping mold. And the work mainly consists of three sections, building parametric finite element model, simulating the process of quenching and optimizing the location parameters and radiuses of each coolant duct. Finally, contrast the optimal result with the initial result and get the conclusion, and moreover, point out the future work.