Characterization of Failure Mechanisms of Duplex and Graded Thermal Barrier Coatings Exposed to Thermal Shock Test

The beginning of failure of a (ZrO2-7%Y2O3)/(Ni-22%Co-17%Cr-12.5%Al-0.6%Y) duplex andgraded coating systems on lnconel 617 and IN738LC in burner rig tests has been characterized.The test conditions are 40 s heating up to 75O℃ substrate temperature followed by 80 s aircooling. Failure is considered at the appearance of the first bright spot during heating period.Stresses due to thermal expansion mismatch strains on cooling are the probable cause of life-limiting in this conditions of testing.

Effects of a Graded Brisk Walking Test with Different Intensity Levels on Elderly Patients with Essential Hypertension:A Prospective Study in Shanghai,China

Background:This study aimed to clarify the effects of a Graded Brisk Walking Test(GBWT)program on blood pressure(BP)control in elderly patients with essential hypertension and to determine its appropriate degree of intensity for elderly people.Methods:In total,421 out of 620 participants were randomly sampled from a community health center in Shanghai,China.Among them,200 and 221 patients were assigned to the intervened and control groups,respectively.They were all treated with the GBWT program for 8 weeks,16 weeks,and 24 weeks.Results:Based on ANOVA,there was no significant time main effect,condition main effect,or time by condition interaction both in heart rate and body mass index indicators(P>0.05).There were significant condition main effects,time by condition interaction,or time main effects in blood pressure(F=21.875,33.457,65.342,respectively;All P<0.05).After the intervention,significant differences in systolic blood pressure(SBP)and diastolic blood pressure(DBP)values were also observed in the two groups(P<0.05);the average values of the baseline and second phases of the intervention group were significantly lower than those of the control group(P<0.05).Significant differences in blood pressure values after the first two phases were also observed when compared with those before the intervention.Similarly,a significant difference in the first phase and second phase was also found between the BP group and intervention group.However,after the third phase(24 weeks,high-intensity exercise),no significant differences existed both in SBP and DBP groups compared with those before the intervention(P=0.07).Conclusion:GBWT is an effective exercise prescription to mitigate the essential hypertension in elderly Chinese patients,and the intensity,walking distance,and target number of steps can be adjusted according to the age of the patients.

Compound Rejuvenation of Polymer Modified Asphalt Binder

The objective of this research was to show a way to conduct rejuvenation of aged polymer modified asphalt binder（PMB） successfully.To fully evaluate and understand the rejuvenation of aged PMB,the Penetration grade tests including penetration,soften point,ductility and elastic recovery and SuperpaveTM PG grade tests including DSR,BBR and DDT were conducted.The rejuvenation effect of aged PMB by utilizing a fluid recycling agent in common use for binder rejuvenation was evaluated.And then the compound rejuvenation effect of aged PMB by utilizing the recycling agent with a new modifying additive for binder modification was evaluated.The experimental results indicated that the recycling agent in common use currently does not apply to polymer modified asphalt binder rejuvenation.But the recycling agent together with the modifying additive can restore the characteristics of aged polymer modified binder very well.Therefore,compound rejuvenation of polymer modified asphalt binder is recommended.

A numerical test method of California bearing ratio on graded crushed rocks using particle flow modeling

In order to better understand the mechanical properties of graded crushed rocks （GCRs） and to optimize the relevant design, a numerical test method based on the particle flow modeling technique PFC2D is developed for the California bearing ratio （CBR） test on GGRs. The effects of different testing conditions and micro-mechanical parameters used in the model on the CBR numerical results have been systematically studied. The reliability of the numerical technique is verified. The numerical results suggest that the influences of the loading rate and Poisson＇s ratio on the CBR numerical test results are not significant. As such, a loading rate of 1.0-3.0 mm/min, a piston diameter of 5 cm, a specimen height of 15 cm and a specimen diameter of 15 cm are adopted for the CBR numerical test. The numerical results reveal that the GBR values increase with the friction coefficient at the contact and shear modulus of the rocks, while the influence of Poisson＇s ratio on the GBR values is insignificant. The close agreement between the CBR numerical results and experimental results suggests that the numerical simulation of the CBR values is promising to help assess the mechanical properties of GGRs and to optimize the grading design. Be- sides, the numerical study can provide useful insights on the mesoscopic mechanism.