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Objective: Biomechanical methods were used to explore the influence of age and gender on children’s motor characteristics, and the internal muscle strength were calculated through simulation modeling, so as to provide ideas for the screening of children with diseases and promotion of motor development. Method: BTS motion capture system collects kinematics data; Kistler force platform collects dynamic data, the simulation software(Anybody 5.2)calculates the muscle strength of the lower limb, two-way ANOVA was performed for difference test. Results: gait: SB, SD, SDI and TA muscle strength increased gradually. GMIP muscle strength: 4 years old group is greater than 3-years-old group. SDI and TFL strength: boys’ were greater than girls’. Running: GM muscle strength: boys’ are greater than girls’. PB muscle strength: the 3-year-old group has smallest muscle strength. GMAS muscle strength: the 3-year-old group has the largest muscle strength, boys’ are greater than girls’. Conclusions: (1) Walking: At the striking time, the buffering capacity of ankle is enhanced gradually. At the moment of lifting off the ground, the range of ankle stretching increased gradually, The angular velocity characteristics has a gender difference. The development of hip flexor muscle strength was uneven between boys and girls. The cushioning muscle strength of the ankle was greater in the 5-year-old group.(2) There were gender differences in time parameters of running. The flexion angle of the ankle was larger at the striking time, which was related to different striking patterns. At the time off-the-ground, the 5-year-old group had the largest hip extension angle. Younger children used more frontal plane joint movement and more hip abductor force.

The search for suitable synthesis methods and parameters capable of controlling the length, diameter, and yield of silver nanowires (AgNWs) is still an emerging strategy today. Therefore, a method for high-yield synthesis of long AgNWs via chromic chloride and a stable reaction environment was proposed. The results show that Cr3+ could restore the adsorbed atomic oxygen quickly and provide a high efficiency in the prevention of the oxidative etching, for the ion of Cr2+ oxidized to Cr3+ has a lower standard electrode potential, and a more stable reaction environment provided by the coupling method could avoid disturbing the growth of the {111} reactive sites of the wires; then, the yield and length of the AgNWs were improved. The length of the AgNWs was over 75 μm and even 160 μm; the yield of the AgNWs was over 90%, which provides the referable basis for the synthesis of ultralong AgNWs.

(NH4)2RuCl6is an important precursor in the synthesis of Ru powder with high-purity requirement. In this study, high-purity (>99.999 wt%) micro-sized (NH4)2RuCl6pieces were synthesized by distillation and precipitation from crude Ru powder. Then, the thermal decomposition behavior of the (NH4)2RuCl6pieces was investigated. The decomposition process included two stages. First, (NH4)2RuCl6was decomposed from 255.0°C to 314.0°C, with the endothermic peak located at 309.4°C. At this stage, HCl and NH3were released, while the dense micro-pieces were transformed to loosened micro-pieces due to the thermal decomposition. Then, the solid phase [(NH3)4Ru3Cl12] kept decomposing from 314.0°C to 352.7°C, HCl and N2were released, and agglomerated Ru particles were achieved. Thermogravimetric analysis-differential thermal analysis-mass spectrum coupling (TG-DTA-MS) was used to monitor the thermal decomposition process and identify the released gaseous phases, respectively. The solid phases in different stages were characterized by high-temperature X-ray diffraction (HTXRD). A good understanding of the processing and thermal decomposition of (NH4)2RuCl6is crucial in the creation of Ru products.

(NH 4 ) 2 RuCl 6 is one of the most important precursors for the preparation of Ru powder with high-purity requirement. In this study, high-purity (> 99.999 wt%) micro-spherical (from 2.3 to 10.4 μm) (NH 4 ) 2 RuCl 6 particles with controllable surface were synthesized by chemical separation method combined with spray drying process. After the chemical separation, high-purity (NH 4 ) 2 RuCl 6 precipitation was achieved, while the morphology, size and surface of (NH 4 ) 2 RuCl 6 particles were controlled by the spray drying process. The detailed influencing mechanisms of spray drying process, including gas/liquid rate, drying temperature and solution concentration, were investigated. Both gas/liquid rate and drying temperature influence the morphology and size of spray dried particles, while solution concentration is directly proportional to size of spray dried particles. It should be noted that the powder technology in this study could be applied to synthesize other high-purity spherical particles.

With a rowing blade is simulated, and the wind tunnel test resistance, resistance coefficient, lift, the lift coefficient and the pressure coefficient values are compared. And the influence on flow state of the different attack angles, calculation model is discussed, the calculation domain, the key link of grid, turbulence models, discrete format and so on have great influence on the calculation results. Considering the computer performance and the computational time, the study on the problem of the sub area division grid is the best choice, in to the grid refinement and unstructured grid has a certain advantage in the aspects of using computing core area; in the flow region is not complicated place can consider the appropriate grid density. Angle of attack and the state of different turbulence models on the numerical simulation accuracy of the greatest impact, the flow state is not complicated small angle of attack, the velocity vector diagram of the difference is small, but the velocity contours appear differences in change of position specific reaction speed, the convergence speed of S-A mode SST k-ω model fast; calculation of 40-60 degree angle of attack results is relatively poor, the calculation of RNG k-e and SST k-ω model is close to the result of calculation. 70-80 degree angle of attack while the calculation of drag coefficient and lift coefficient compared with experiment data is close to the difference; 90 degree angle of attack SST k-ω model is a more ideal model. In the discussion of the computational domain can be chosen as the reference of the contents of the pressure coefficient. Computing grid and computational domain can be turbulent model, according to the above calculation reference fluid mechanics problems in the field of sports.

Nanoscale tungsten (W) powder is used in some special materials. In this study, a hollow superstructure W powder consisting of nanoparticles was synthesized by spray drying combined with two-step calcination from commercial (NH4)6W7O24·6H2O. The high-pressure gas (HPG) was the significant factor in spray drying process, which affect the BET surface area and average particles size of the spray-dried powders. The detailed influences of calcined steps and calcination temperature in the microstructure and average particles size of final W particles were investigated. The size distribution of as-synthesized nanoscale W particles with hollow superstructure was from 40 to 200 nm, and the average size was about 100 nm. The as-synthesized W powder shows good sintering properties. It should be noted that the powder technology in this study can be used to synthesize other powders with high-performance requirements. Graphical abstract .