Accurate prediction of performance decay law is an important basis for long-term planning of maintenance strategy.The statistical regression prediction model is the most widely employed method to calculate pavement pe...Accurate prediction of performance decay law is an important basis for long-term planning of maintenance strategy.The statistical regression prediction model is the most widely employed method to calculate pavement performance due to its advantages such as the small amount of calculation and good accuracy,but the traditional prediction model seems not applicable to the high maintenance level areas with excellent pavement conditions.In this paper,the service life and the cumulative number of the axle load were determined as the independent variables of prediction models of pavement performance.The pavement condition index(PCI)and rutting depth index(RDI)were selected as maintenance decision control indexes to establish the unified prediction model of PCI and RDI respectively by applying the cosine deterioration equation.Results reveal that the deterioration law of PCI presents an anti-S type or concave type and the deterioration law of RDI shows an obvious concave type.The prediction model proposed in this study added the pavement maintenance standard factor d,which brings the model parameterα(reflecting the road life)and the deterioration equations are more applicable than the traditional standard equations.It is found that the fitting effects of PCI and RDI prediction models with different traffic grades are relatively similar to the actual service state of the pavements.展开更多
This work was on non-activated and activated lateritic soil used in proportions of 0%to 30%,to replace fine sand by wt.%,in the production of lateritic concrete.A mix of 1:2:4 was used,and the cube samples were cured...This work was on non-activated and activated lateritic soil used in proportions of 0%to 30%,to replace fine sand by wt.%,in the production of lateritic concrete.A mix of 1:2:4 was used,and the cube samples were cured in four(4)curing media of water,sand,polythene,and sawdust.The aim was to evaluate the effects of these curing methods on the mechanical strengths,and other properties of lateritic concrete.The sensitivity of the generated data was characterized statistically and developing linear regression models for predictions.For the Non-Activated Laterite soil(NALS,control mix(0%)),the design strength of 20 MPa was achieved by all the curing methods(standard and non-standard).However,for other replacement levels,water curing was adequate for 10%and 30%,sand at 10%,and sawdust for 20%and 30%,respectively.On the other hand,for the Activated Laterite soil(ALS),the 20 MPa design strength was met only at 0%replacement for all curing methods.Sawdust medium at 10%also satisfied the 20 MPa strength.展开更多
A review of ten-year's practice in developing the improved simultaneous physical retrieval method(ISPRM)is given in the hope that some creative ideas can be drawn from it.The improvement upon the SPRM is associate...A review of ten-year's practice in developing the improved simultaneous physical retrieval method(ISPRM)is given in the hope that some creative ideas can be drawn from it.The improvement upon the SPRM is associated with the under-determinedness of this ill-posed inverse problem.In our experiment,the precondition is observed that prior information must be independent of the satellite measurements.The well-posed retrieval theory has told us that the forward process is fundamental for the retrieval,and it is the bridge between the input of satellite radiance and the output of retrievals.In order to obtain a better result from the forward process. the full advantage of every prior information available must be taken.It is necessary to turn the ill- posed inverse problem into the well-posed one.Then by using the Ridge regression or Bayes algorithm to find the optimal combination among the first guess,the theoretical analogue information and the satellite observations,the impact of the under-determinedness of this inverse problem on the numerical solution is minimized.展开更多
基金the National Key Research and Development Program of China with Grant No.2018YFB1600100the National Natural Science Foundation of China with Grant No.51978219 and No.51878228.
文摘Accurate prediction of performance decay law is an important basis for long-term planning of maintenance strategy.The statistical regression prediction model is the most widely employed method to calculate pavement performance due to its advantages such as the small amount of calculation and good accuracy,but the traditional prediction model seems not applicable to the high maintenance level areas with excellent pavement conditions.In this paper,the service life and the cumulative number of the axle load were determined as the independent variables of prediction models of pavement performance.The pavement condition index(PCI)and rutting depth index(RDI)were selected as maintenance decision control indexes to establish the unified prediction model of PCI and RDI respectively by applying the cosine deterioration equation.Results reveal that the deterioration law of PCI presents an anti-S type or concave type and the deterioration law of RDI shows an obvious concave type.The prediction model proposed in this study added the pavement maintenance standard factor d,which brings the model parameterα(reflecting the road life)and the deterioration equations are more applicable than the traditional standard equations.It is found that the fitting effects of PCI and RDI prediction models with different traffic grades are relatively similar to the actual service state of the pavements.
文摘This work was on non-activated and activated lateritic soil used in proportions of 0%to 30%,to replace fine sand by wt.%,in the production of lateritic concrete.A mix of 1:2:4 was used,and the cube samples were cured in four(4)curing media of water,sand,polythene,and sawdust.The aim was to evaluate the effects of these curing methods on the mechanical strengths,and other properties of lateritic concrete.The sensitivity of the generated data was characterized statistically and developing linear regression models for predictions.For the Non-Activated Laterite soil(NALS,control mix(0%)),the design strength of 20 MPa was achieved by all the curing methods(standard and non-standard).However,for other replacement levels,water curing was adequate for 10%and 30%,sand at 10%,and sawdust for 20%and 30%,respectively.On the other hand,for the Activated Laterite soil(ALS),the 20 MPa design strength was met only at 0%replacement for all curing methods.Sawdust medium at 10%also satisfied the 20 MPa strength.
基金Supported by NNSF of China under Grant(49794030#)National"973"Program No.4 (G1998040909#).
文摘A review of ten-year's practice in developing the improved simultaneous physical retrieval method(ISPRM)is given in the hope that some creative ideas can be drawn from it.The improvement upon the SPRM is associated with the under-determinedness of this ill-posed inverse problem.In our experiment,the precondition is observed that prior information must be independent of the satellite measurements.The well-posed retrieval theory has told us that the forward process is fundamental for the retrieval,and it is the bridge between the input of satellite radiance and the output of retrievals.In order to obtain a better result from the forward process. the full advantage of every prior information available must be taken.It is necessary to turn the ill- posed inverse problem into the well-posed one.Then by using the Ridge regression or Bayes algorithm to find the optimal combination among the first guess,the theoretical analogue information and the satellite observations,the impact of the under-determinedness of this inverse problem on the numerical solution is minimized.
