Effects of Processing Technologies on Mechanical Properties of SiC Particulate Reinforced Magnesium Matrix Composites

Mg matrix composites with SiC particles ranging from 5vol%-25vol% were prepared using stirring casting method. Die casting, squeezing casting, and extrusion were applied for inhibiting or eliminating the defects such as gas porosity and shrinkage void. Through die casting and squeezing casting, most of the defects in Mg matrix composites could be eliminated, but the mechanical properties were improved limitedly. On the other hand, after hot extrusion, not only most of the defects of as-cast composites ingots were eliminated, but also the mechanical properties were improved markedly. With the addition of SiC, the tensile strength, yield strength and elastic modulus of as extrusion SiCp/AZ61 composites increased remarkably, and the elongation decreased obviously.

Development Trend and Prediction of Stem Cell Technology in China from the Perspective of Patent

Objective To provide new ideas for the effective treatment of many serious diseases and to solve many major medical problems faced by mankind.Methods In this paper,the invention patents in the field of stem cells in China from 2010 to 2020 were taken as the research object,and the technology status quo in the field of stem cells was analyzed to predict the future development direction through quantitative analysis method.Results and Conclusion The development of stem cell technology in China is in a period of growth with great potential.Therefore,it is necessary to strengthen the ability of Chinese universities to combine production,education and research.Nowadays,the hotspots in stem cell technology are using culture medium to improve cell proliferation ability,production efficiency,and to induce differentiated cells.Meanwhile,the production efficiency of embryonic stem cells should be improved,and the immunomodulatory effect of embryonic stem cells can be exerted to screen drugs.Besides,the function of hematopoietic stem cells should be enhanced and apply mesenchymal cells in therapy.Since the potential technological gaps are the improvement of therapy,induced differentiation and efficiency of pluripotent stem cells,the improvement of progenitor cell proliferation and the control of cost,we should strengthen R&D investment in culture medium,embryonic stem cells and other technical fields,and achieve the purpose of reducing R&D costs and improving R&D efficiency.

Towed line array sonar platform noise suppression based on spatial matrix filtering technology

The spatial matrix filter was designed and used for solving the problem to detect a weak target who was influenced by the strong nearby platform noise interference of the towed line array sonar. The MFP technology and the DOA estimation technology were combined together by using the sound propagation characteristics of both target and interference. The spatial matrix filter with platform noise zero response constraint was designed by the near-field platform noise normal modes copy vectors and the far-field plane wave bearing vectors together. The optimal solution of the optimization problem for designing the spatial matrix filter was deduced directly, and it was simplified by the generalized singular value decomposition. The total response error to the plane wave bearing vectors and the total response to the platform noise copy vectors were given. The phenomena that strong interferences existed in the bearing course and blind areas existed after filtering were analyzed by the correlation between the plat- form noise copy vectors and the plane wave bearing vectors. It could be found from simulations that it has less blind area and higher detection ability by using the spatial matrix filtering technology.

Evaluation of Electricity Generating System's Technology Mix Using 3E Indicator

For the purpose of the research, the technologies for electricity generation are classified in four categories: CO_2-free-desspatchable(hydro, nuclear, and biomass fired), CO_2-free-non-desspatchable(wind generators and photo voltaic), CO_2-dependent-despatchable and CO_2-dependent-non-despatchable ones. 3E indicator is introduced purposely to enable quantitative evaluation of the considered complex technology structures, as well as to provide support for decision making during the design and operation procedures of electricity generating systems. The application of the indicator is demonstrated with appropriate model numerical simulations for the general European conditions. In the model calculations are analyzed simplified technology mixes with CO_2 free, non-despatchable technologies in overall load, two technologies in base part of the residual load(lignite fired and nuclear), one technology in intermediate part of the residual load and one in the pick part of the residual load both CO_2 dependent, despatchable ones. The results show that the introduced 3E indicator is suitable for analysis of the technological combinations for electricity generation within considered countries. The results also show that increase participation of nuclear power plants in residual load domain contribute to better(lower) value of 3E indicator. The results obtained for technology structures in nine analyzed European countries(Germany, France, Austria, Greece, Serbia, Hungary, Bulgaria, Belgium and Netherlands) point out that the country with higher participation of CO_2 free despatchable and lower participation of CO_2 free non-despatchable technologies in electricity generation has tendency toward better i.e. lower value of 3E indicator. On the other hand the country with the higher participation of CO_2 free non-despatchable and lower to moderate participation of CO_2 free despatchable technologies has tendency toward the higher value of 3E indicator. These results are in accordance with the results obtained by numerical simulations with simplified technology mixes.