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
This special topic on high-dimensional statistical inference is dedicated to the memory of Professor Xiru Chen, commemorating the twentieth anniversary of his passing.Professor Chen was a renowned statistician in Chin...This special topic on high-dimensional statistical inference is dedicated to the memory of Professor Xiru Chen, commemorating the twentieth anniversary of his passing.Professor Chen was a renowned statistician in China and made significant contributions to various areas in statistics. He conducted in-depth and systematic research on linear statistical models, resolving the issues of strong and weak consistency for M-estimators under general loss functions.展开更多
Particulate pollution was a critical challenge to the promise of good air quality during the 2008 Beijing Olympic Games,which took place from August 8th to 24th.To ensure good air quality for the Games,several tempora...Particulate pollution was a critical challenge to the promise of good air quality during the 2008 Beijing Olympic Games,which took place from August 8th to 24th.To ensure good air quality for the Games,several temporary emission control measures were implemented in Beijing and surrounding areas.Ambient particulate matter concentration decreased significantly during the Olympic period;however,it is difficult to distinguish the effectiveness of those control measures since meteorology also affects ambient PM_(2.5) concentration.In this work,a multiple linear regression model based on continuous field monitoring at a roadside site was conducted to evaluate the effects of meteorology and emission control measures on the reduction of PM_(2.5) during the 2008 Olympic Games.The hourly data set was divided into two time periods,the no control period,June 22nd to July 4th,and the control period,July 28th to August 21st.The response variable was PM_(2.5) and the meteorology covariates used in the model were hourly temperature,dew point temperature,wind speed and precipitation.Wind direction was not a significant predictor of PM_(2.5) levels in either the control or the no control period.Using the meteorologically-based regression coefficients from the two time periods,meteorology was found to contribute to at least a 16%reduction in PM_(2.5) levels in the roadside microenvironment;while the pollution control measures contributed to at least a 43%reduction in PM_(2.5) levels.展开更多
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.
文摘This special topic on high-dimensional statistical inference is dedicated to the memory of Professor Xiru Chen, commemorating the twentieth anniversary of his passing.Professor Chen was a renowned statistician in China and made significant contributions to various areas in statistics. He conducted in-depth and systematic research on linear statistical models, resolving the issues of strong and weak consistency for M-estimators under general loss functions.
基金The research described in this paper is supported by the National Natural Science Foundation of China(Grant Nos.50908121 and 20521140077).
文摘Particulate pollution was a critical challenge to the promise of good air quality during the 2008 Beijing Olympic Games,which took place from August 8th to 24th.To ensure good air quality for the Games,several temporary emission control measures were implemented in Beijing and surrounding areas.Ambient particulate matter concentration decreased significantly during the Olympic period;however,it is difficult to distinguish the effectiveness of those control measures since meteorology also affects ambient PM_(2.5) concentration.In this work,a multiple linear regression model based on continuous field monitoring at a roadside site was conducted to evaluate the effects of meteorology and emission control measures on the reduction of PM_(2.5) during the 2008 Olympic Games.The hourly data set was divided into two time periods,the no control period,June 22nd to July 4th,and the control period,July 28th to August 21st.The response variable was PM_(2.5) and the meteorology covariates used in the model were hourly temperature,dew point temperature,wind speed and precipitation.Wind direction was not a significant predictor of PM_(2.5) levels in either the control or the no control period.Using the meteorologically-based regression coefficients from the two time periods,meteorology was found to contribute to at least a 16%reduction in PM_(2.5) levels in the roadside microenvironment;while the pollution control measures contributed to at least a 43%reduction in PM_(2.5) levels.
