In this study,different influence mechanisms associated with temperatures and pH values were investigated through cemented paste backfill(CPB)systems.CPB samples were prepared with temperatures ranging from 10 to 50℃...In this study,different influence mechanisms associated with temperatures and pH values were investigated through cemented paste backfill(CPB)systems.CPB samples were prepared with temperatures ranging from 10 to 50℃ in 10℃ increments and pH values of 3,7,and 13.Then,the CPB mixture were subjected to rheological tests,thermogravimetric analysis(TG),derivative thermogravimetry analysis(DTG),Fourier-transform infrared spectroscopy(FT-IR),and scanning electron microscopy(SEM).Results demonstrated that the temperatures had significant effects on the rheological properties of CPB,whereas the effects of pH values were relatively unapparent.Higher temperatures(over 20℃)were prone to bring higher shear stress,yield stress,and apparent viscosity with the same pH value condition.However,an overly high temperature(50℃)cannot raise the apparent viscosity.Non-neutral conditions,for pH values of 3 and 13,could strengthen the shear stress and apparent viscosity at the same temperature.Two different yield stress curves could be discovered by uprising pH values,which also led to apparent viscosity of two various curves under the same temperatures(under 50℃).Microscopically,rheological properties of CPB were affected by temperatures and pH values which enhanced or reduced the cement hydration procedures,rates,products and space structures.展开更多
In the application of persistent scatterer interferometry(PSI),deformation information is extracted from persistent scatterer(PS)points.Thus,the density and position of PS points are critical for PSI.To increase the P...In the application of persistent scatterer interferometry(PSI),deformation information is extracted from persistent scatterer(PS)points.Thus,the density and position of PS points are critical for PSI.To increase the PS density,a time-series InSAR chain termed as"super-resolution persistent scatterer interferometry"(SR-PSI)is proposed.In this study,we investigate certain important properties of SR-PSI.First,we review the main workflow and dataflow of SR-PSI.It is shown that in the implementation of the Capon algorithm,the diagonal loading(DL)approach should be only used when the condition number of the covariance matrix is sufficiently high to reduce the discontinuities between the joint images.We then discuss the density and positioning accuracy of PS when compared with traditional PSI.The theory and experimental results indicate that SR-PSI can increase the PS density in urban areas.However,it is ineffective for the rural areas,which should be an important consideration for the engineering application of SR-PSI.Furthermore,we validate that the positioning accuracy of PS can be improved by SRPSI via simulations.展开更多
基金Project(2019zzts678)supported by the Fundamental Research Funds for the Central Universities,China。
文摘In this study,different influence mechanisms associated with temperatures and pH values were investigated through cemented paste backfill(CPB)systems.CPB samples were prepared with temperatures ranging from 10 to 50℃ in 10℃ increments and pH values of 3,7,and 13.Then,the CPB mixture were subjected to rheological tests,thermogravimetric analysis(TG),derivative thermogravimetry analysis(DTG),Fourier-transform infrared spectroscopy(FT-IR),and scanning electron microscopy(SEM).Results demonstrated that the temperatures had significant effects on the rheological properties of CPB,whereas the effects of pH values were relatively unapparent.Higher temperatures(over 20℃)were prone to bring higher shear stress,yield stress,and apparent viscosity with the same pH value condition.However,an overly high temperature(50℃)cannot raise the apparent viscosity.Non-neutral conditions,for pH values of 3 and 13,could strengthen the shear stress and apparent viscosity at the same temperature.Two different yield stress curves could be discovered by uprising pH values,which also led to apparent viscosity of two various curves under the same temperatures(under 50℃).Microscopically,rheological properties of CPB were affected by temperatures and pH values which enhanced or reduced the cement hydration procedures,rates,products and space structures.
基金supported by the National Natural Science Foundation of China(62101284)the State Key Laboratory of Geo-Information Engineering and Key Laboratory of Surveying and Mapping Science and Geospatial Information Technology of Ministry of Natural Resources+4 种基金China Academy of Surveying and Mapping(2021-03-11)the Natural Science Project of Jiangsu Province(21KJB420003)Nanjing University of Posts and Telecommunications Start-up Fund(NY221033,NY220168)the Foundation of Jiangsu Province Shuangchuang Doctor Grant(JSSCBS20210543)Beijing Key Laboratory of Urban Spatial Information Engineering(20210215)。
文摘In the application of persistent scatterer interferometry(PSI),deformation information is extracted from persistent scatterer(PS)points.Thus,the density and position of PS points are critical for PSI.To increase the PS density,a time-series InSAR chain termed as"super-resolution persistent scatterer interferometry"(SR-PSI)is proposed.In this study,we investigate certain important properties of SR-PSI.First,we review the main workflow and dataflow of SR-PSI.It is shown that in the implementation of the Capon algorithm,the diagonal loading(DL)approach should be only used when the condition number of the covariance matrix is sufficiently high to reduce the discontinuities between the joint images.We then discuss the density and positioning accuracy of PS when compared with traditional PSI.The theory and experimental results indicate that SR-PSI can increase the PS density in urban areas.However,it is ineffective for the rural areas,which should be an important consideration for the engineering application of SR-PSI.Furthermore,we validate that the positioning accuracy of PS can be improved by SRPSI via simulations.
