Simulation experiment on anti-penetration capability of anchored rock mass

In order to solve the problem of experimental research on the penetration process of projectile into anchored rock mass, we derived the essential similarity conditions for the physical simulation experi- ment according to the similarity theory, carried out the experiment on the penetration process of a kind of penetrating bomb into the anchored rock mass of type III, and compared the experimental results with the values computed by the professional Young's empirical formula. The test results show that the phys- ical simulation experiment can represent the actual penetration process of projectile into anchored rock mass. The research method proposed in this paper provides technical support for the experimental research on the design and reconstruction of underground protection works.

Comparison of the effects of intravitreal bevacizumab and dexamethasone in experimental posterior penetrating eye injury

AIM： To compare the effects of intravitreal anti-vascular endothelial growth factor（VEGF） and dexamethasone in an experimental rabbit model of posterior penetrating ocular injury.METHODS： Thirty white New Zealand rabbits were included in the study. A posterior penetrating ocular injury was performed at the superotemporal quadrant. They were randomly divided into three groups. The rabbits in group 1 received intravitreal dexamethasone, in group 2 they received intravitreal bevacizumab and those in group 3 received intravitreal physiological saline solution in both eyes. All eyes were examined ophthalmologically on the 1^st, 3^rd, 7^th, 14^th and 28^th days following the injury and the clinical findings were scored. On the day 28, the eyes were enucleated, evaluated and scored macroscopically, histopathologically and scanning electron microscopically.RESULTS： The median clinical score on the 14 th and 28 th days and the median macroscopic score of the dexamethasone group was significantly better than that of control（P=0.004, 0.018）. Dexamethasone group was also better than that of bevacizumab group but the differences did not reach statistical significance. Retinal detachment rate was 8.3%, 16.6% and 12.5% in the dexamethasone group, bevacizumab group and control group, respectively（P=0.476）. More extensive fibrocelluler proliferations were observed in controls compared with dexamethasone and bevacizumab groups. But these differences did not reach the statistical significance（P=0.538）. In scanning electron microscopy all groups showed fibreous stalk and dense collagen fibrils in vitreous. CONCLUSION： This study shows that intravitreal injection of both dexamethasone and bevacizumab may reduce the intraocular fibrous proliferation after an experimental posterior penetrating ocular injury in rabbits.

CMAS corrosion resistance characteristics of RE_(50)Ta_(x)Zr_(50-x)O_(175+0.5x)thermal barrier oxides in RE_(2)Zr_(2)O_(7)-RETaO_(4)systems

The corrosion resistance characteristics of RE-rich RE_(50)Ta_(x)Zr_(50-x)O_(175+0.5x)oxides in RE_(2)Zr_(2)O_(7)-RETaO_(4)systems to calcium-magnesium-alumino-silicate(CMAS)at 1300°C,and the influence of RE^(3+)and Ta^(5+)on chemical reactions and reactive crystallization of CMAS melts were investigated.The results show that following the thermochemical reactions,apatite,pyrochlore,reprecipitated fluorite and residual Yb(Y)TaO4phases were the predominant reaction products.Formation abilities of apatite and pyrochlore were found to be proportional to the ionic radius of RE^(3+).The increase of Ta^(5+)amount can decrease the number of available RE^(3+)to form apatite.Moreover,the resistance characteristic to CMAS corrosion in RE_(50)Ta_(x)Zr_(50-x)O_(175+0.5x)systems was decided by the combined action of apatite and pyrochlore phases.The cohesive mixture of apatite and pyrochlore phases can generate a dense layer near the reaction front,which had a positive effect on suppressing CMAS infiltration.The ability of the fluorite+RETaO4two-phase field was determined to be sufficient to mitigate CMAS corrosion.

SPH-BASED NUMERICAL ANALYSIS FOR GRANULAR MATERIAL MODEL OF SAND AND REGOLITH

The development of an innovative drilling system makes it necessary to model the material of extra-terrestrial soil , i.e.regolith or lunar soil.And then the drilling process is numerically simulated.Since real regolith is very scarce and costly , sand properties are investigated by means of experiments and sand model is constructed with the capability of partly reflecting these properties.With the use of smooth particle hydrodynamics ( SPH ) method in LS-DYNA , data analysis and modeling process are presented to reach the following achievements :( 1 ) Develop ageneral model approach of sand using SPH method ;( 2 ) Compare SPH results with experimental data to validate it ;( 3 ) Adapt the sand model to lunar soil while fitting the simulation of dual-reciprocating drilling ( DRD ) process.