Structural behavior of suspension bridge with a stabilizing cable

Suspended structures are commonly used in construction of motorway and pedestrian bridges. These structures allow wide spans without the need for intermediate supports. Suspension bridges are noted for lower structural stiffness as compared to beam bridges and arc bridges. The stiffness control depending on the environment and external effects (moving loads, wind, seismic forces, etc.) is a real-life challenge [1, 2]. The authors of this paper have evaluated the use of stabilizing cable installed in the central span under the stiffening girder as the means of stiffness control. A plane 3D model of a suspension bridge was developed using the ANSYS software. The study compared the stress deformed state and dynamic properties of the models with and without a stabilizing cable. The displacement in the model equipped with a stabilizing cable, as compared to the one without, was noted to be lower in all relevant sections: 2.6 times in the middle of the central span of the stiffening girder; 15 times in the middle of the end span; and displacement of the tower top was 3.5 times lower

Cooling Cyclic Air of Marine Engine with Water-Fuel Emulsion Combustion by Exhaust Heat Recovery Chiller

The fuel efficiency of marine diesel engine as any combustion engine falls with raising the temperature of air at the suction of its turbocharger. Therefore, cooling the engine turbocharger intake air by recovering exhaust gas heat to refrigeration capacity is a very perspective trend in enhancing the fuel efficiency of marine diesel engines. The application of water-fuel emulsion (WFE) combustion enables the reduction of a low-temperature corrosion, and, as a result, provides deeper exhaust gas heat utilization in the exhaust gas boiler (EGB) to the much lower temperature of 90–110 °C during WFE instead of 150–170 °C when combusting conventional fuel oil. This leads to the increment of the heat extracted from exhaust gas that is converted to refrigeration capacity by exhaust heat recovery chiller for cooling engine turbocharger sucked air accordingly. We experimentally investigated the corrosion processes on the condensation surfaces of EGB during WFE combustion to approve their intensity suppression and the possibility of deeper exhaust gas heat utilization. The fuel efficiency of cooling intake air at the suction of engine turbocharger with WFE combustion by exhaust heat recovery chiller was estimated along the voyage line Mariupol–Amsterdam–Mariupol. The values of available refrigeration capacity of exhaust heat recovery chiller, engine turbocharger sacked air temperature drop, and corresponding reduction in specific fuel consumption of the main low-speed diesel engine at varying actual climatic conditions on the voyage line were evaluated

Каркасные катализаторы системы Al2^O3^{- ZrO}2^{- CeO}2

Xerogels and powders of Al2O3 - ZrO2 - CeO2 systems with diferent pore structure and matrixes of ZrO 2 and Al2O3 were obtained. The speciic surface area of xerogels with ZrO 2 and Al2O3 matrix exceeds 200 m2/g and 90 m2/g respectively. After calcinations at 950 °C, the powders retain nanoscale, with the size of individual particles ranging from 70 to 28 nm. The main crystalline phase in these powders is a solid solution of tetragonal zirconia. Total ethanol conversion of xerogels with ZrO2 and Al2O3 matrix has similar values. Selectivity of to ethylene conversion is about 50 % and doesn’t depend on calcination temperature. For samples with an Al2O3 matrix, a 50 % ethylene selectivity was reached after heating at 950 °C. It was shown that the catalytic activity of ethanol conversion reaction is higher for samples with more crystallized phase based on solid solution of tetragonal zirconia, namely, for samples with the ZrO2 matrix calcinated at 950 °C.Получены наноразмерные ксерогели и наноразмерные порошки в системе Al 2O3 - ZrO2 - CeO2 с матрицами ZrO 2 и Al2O3 с различной пористой структурированностью. Удельная поверхность ксерогелей с матрицей ZrO 2 превышает 200 м 2/г, а с матрицей Al 2O3 составляет 90 м 2/г. Ксерогели как с матрицей ZrO2, так и Al2O3 являются рентгеноаморфными. После термообработки ксерогелей при температуре 950 °С порошки сохраняют наноразмерность, при этом размер индивидуальных частиц находится в интервале от 28 до 70 нм. Основная кристаллическая фаза в порошках представлена твердым раствором на основе тетрагонального диоксида циркония. Величины общей конверсии этанола для ксерогелей с 2 и Al2O3 близки. Селективность по выходу этилена для образцов с матрицей маZrOтрицами ZrO2 не зависит от температуры термообработки и превышает 50 %, а для образцов с матрицей Al 2O3 селективность 50 % достигается после термообработки при температуре 950 °С. Показано, что каталитическая активность в реакции превращений этанола выше у образцов с преобладающей и более закристаллизованной фазой твердого раствора ) после на основе тетрагонального диоксида циркония (в образцах с матрицей ZrO 2термообработки при температуре 950 °С

Каркасные катализаторы системы Al2^O3^{- ZrO}2^{- CeO}2

Xerogels and powders of Al2O3 - ZrO2 - CeO2 systems with diferent pore structure and matrixes of ZrO 2 and Al2O3 were obtained. The speciic surface area of xerogels with ZrO 2 and Al2O3 matrix exceeds 200 m2/g and 90 m2/g respectively. After calcinations at 950 °C, the powders retain nanoscale, with the size of individual particles ranging from 70 to 28 nm. The main crystalline phase in these powders is a solid solution of tetragonal zirconia. Total ethanol conversion of xerogels with ZrO2 and Al2O3 matrix has similar values. Selectivity of to ethylene conversion is about 50 % and doesn’t depend on calcination temperature. For samples with an Al2O3 matrix, a 50 % ethylene selectivity was reached after heating at 950 °C. It was shown that the catalytic activity of ethanol conversion reaction is higher for samples with more crystallized phase based on solid solution of tetragonal zirconia, namely, for samples with the ZrO2 matrix calcinated at 950 °C.Получены наноразмерные ксерогели и наноразмерные порошки в системе Al 2O3 - ZrO2 - CeO2 с матрицами ZrO 2 и Al2O3 с различной пористой структурированностью. Удельная поверхность ксерогелей с матрицей ZrO 2 превышает 200 м 2/г, а с матрицей Al 2O3 составляет 90 м 2/г. Ксерогели как с матрицей ZrO2, так и Al2O3 являются рентгеноаморфными. После термообработки ксерогелей при температуре 950 °С порошки сохраняют наноразмерность, при этом размер индивидуальных частиц находится в интервале от 28 до 70 нм. Основная кристаллическая фаза в порошках представлена твердым раствором на основе тетрагонального диоксида циркония. Величины общей конверсии этанола для ксерогелей с 2 и Al2O3 близки. Селективность по выходу этилена для образцов с матрицей маZrOтрицами ZrO2 не зависит от температуры термообработки и превышает 50 %, а для образцов с матрицей Al 2O3 селективность 50 % достигается после термообработки при температуре 950 °С. Показано, что каталитическая активность в реакции превращений этанола выше у образцов с преобладающей и более закристаллизованной фазой твердого раствора ) после на основе тетрагонального диоксида циркония (в образцах с матрицей ZrO 2термообработки при температуре 950 °С

The Influence of Co Additive on the Sintering, Mechanical Properties, Cytocompatibility, and Digital Light Processing Based Stereolithography of 3Y-TZP-5Al2O3 Ceramics

Nanocrystalline 3 mol% yttria-tetragonal zirconia polycrystal (3Y-TZP) ceramic powder containing 5 wt.% Al2O3 with 64 m2/g specific area was synthesized through precipitation method. Different amounts of Co (0–3 mol%) were introduced into synthesized powders, and ceramic materials were obtained by heat treatment in the air for 2 h at 1350–1550 °C. The influence of Co addition on the sintering temperature, phase composition, microstructure, mechanical and biomedical properties of the obtained composite materials, and on the resolution of the digital light processing (DLP) printed and sintered ceramic samples was investigated. The addition of a low amount of Co (0.33 mol%) allows us to decrease the sintering temperature, to improve the mechanical properties of ceramics, to preserve the nanoscale size of grains at 1350–1400 °C. The further increase of Co concentration resulted in the formation of both substitutional and interstitial sites in solid solution and appearance of CoAl2O4 confirmed by UV-visible spectroscopy, which stimulates grain growth. Due to the prevention of enlarging grains and to the formation of the dense microstructure in ceramic based on the tetragonal ZrO2 and Al2O3 with 0.33 mol% Co the bending strength of 720 ± 33 MPa was obtained after sintering at 1400 °C. The obtained materials demonstrated the absence of cytotoxicity and good cytocompatibility. The formation of blue CoAl2O4 allows us to improve the resolution of DLP based stereolithographic printed green bodies and sintered samples of the ceramics based on ZrO2-Al2O3. The developed materials and technology could be the basis for 3D manufacturing of bioceramic implants for medicine

Effects of Heat Treatment on Phase Formation in Cytocompatible Sulphate-Containing Tricalcium Phosphate Materials

Powders based on β-tricalcium phosphate (β-TCP) containing sulphate groups at up to 12.0 mol.% were synthesised by chemical precipitation from aqueous solutions. The obtained materials were characterised by X-ray phase analysis, Fourier transform infrared spectroscopy, measurement of specific surface area, scanning electron microscopy, energy dispersive analysis, synchronous thermal analysis, mass spectra investigations and biological assays. It was established that during the synthesis, the obtained materials lose the sulphate groups in the course of heat treatment at 900 or 1200 °C. These groups stabilise low-temperature β-TCP, but when introduced at a high concentration, the sulphate groups contribute to the formation of hydroxyapatite during the heat treatment. Specific surface area of the powders proved to be in the range 81.7–96.5 m2/g. Results of biological assays showed cytocompatibility of both pure β-TCP and samples of sulphate-containing β-TCP. Additionally, matrix properties in the culture of MG-63 cells were revealed in all samples. Thus, the obtained materials are promising for biomedical applications

Effects of Heat Treatment on Phase Formation in Cytocompatible Sulphate-Containing Tricalcium Phosphate Materials

Powders based on β-tricalcium phosphate (β-TCP) containing sulphate groups at up to 12.0 mol.% were synthesised by chemical precipitation from aqueous solutions. The obtained materials were characterised by X-ray phase analysis, Fourier transform infrared spectroscopy, measurement of specific surface area, scanning electron microscopy, energy dispersive analysis, synchronous thermal analysis, mass spectra investigations and biological assays. It was established that during the synthesis, the obtained materials lose the sulphate groups in the course of heat treatment at 900 or 1200 °C. These groups stabilise low-temperature β-TCP, but when introduced at a high concentration, the sulphate groups contribute to the formation of hydroxyapatite during the heat treatment. Specific surface area of the powders proved to be in the range 81.7–96.5 m2/g. Results of biological assays showed cytocompatibility of both pure β-TCP and samples of sulphate-containing β-TCP. Additionally, matrix properties in the culture of MG-63 cells were revealed in all samples. Thus, the obtained materials are promising for biomedical applications

Effects of Various Ripening Media on the Mesoporous Structure and Morphology of Hydroxyapatite Powders

Mesoporous hydroxyapatite (HA) materials demonstrate advantages as catalysts and as support systems for catalysis, as adsorbent materials for removing contamination from soil and water, and as nanocarriers of functional agents for bone-related therapies. The present research demonstrates the possibility of the enlargement of the Brunauer–Emmett–Teller specific surface area (SSA), pore volume, and average pore diameter via changing the synthesis medium and ripening the material in the mother solution after the precipitation processes have been completed. HA powders were investigated via chemical analysis, X-ray diffraction analysis, Fourier-transform IR spectroscopy, transmission electron microscopy (TEM), and scanning (SEM) electron microscopy. Their SSA, pore volume, and pore-size distributions were determined via low-temperature nitrogen adsorption measurements, the zeta potential was established, and electron paramagnetic resonance (EPR) spectroscopy was performed. When the materials were synthesized in water–ethanol and water–acetone media, the SSA and total pore volume were 52.1 m2g−1 and 116.4 m2g−1, and 0.231 and 0.286 cm3g−1, respectively. After ripening for 21 days, the particle morphology changed, the length/width aspect ratio decreased, and looser and smaller powder agglomerates were obtained. These changes in their characteristics led to an increase in SSA for the water and water–ethanol samples, while pore volume demonstrated a multiplied increase for all samples, reaching 0.593 cm3g−1 for the water–acetone sample