The Edlén empirical equations and the two-color method are the commonly used approaches to converting a length measured in air to the corresponding length in vacuum to eliminate the influence of the refractive in...The Edlén empirical equations and the two-color method are the commonly used approaches to converting a length measured in air to the corresponding length in vacuum to eliminate the influence of the refractive index of air. However, it is not well known whether the two-color method is superior to empirical equations in refractive index compensation. We investigated the uncertainties of these approaches via numerical calculations of their sensitivity coefficients of environmental parameters. On the basis of a comparison of their uncertainties, we found that in a 0% humidity environment, the two-color method had potential to provide greater measurement accuracy than the empirical equations.展开更多
Three-hundred and thirty-one sediment cores,including six sediment types(clayey-and sandy-silt,silty-and sandy-clay,clayey-and silty-sand)were collected from the shallow and semi-deep seas of the South China Sea,and t...Three-hundred and thirty-one sediment cores,including six sediment types(clayey-and sandy-silt,silty-and sandy-clay,clayey-and silty-sand)were collected from the shallow and semi-deep seas of the South China Sea,and the P-wave velocities and physical properties of core sediments were measured under standard laboratory conditions.To eliminate the influence of environ-mental factors,the empirical sound speed ratio equations were established.Compared with several equations from literature,the po-rosity and wet bulk density empirical equations established in this paper agree well with Richardson and Briggs(2004)’s in-situ equations,which implies that our empirical equations can be used in the similar region of world’s oceans under certain conditions and will be useful in areas lacking first-hand P-wave speed data.However,the mean grain size equations established in this study,similar to the previous studies,have low accuracy,which may be due to the different particle arrangements and degrees of compac-tion in sediments.The results also show that for different sediment types,the equation based on all sediment data is in good agree-ment with the measured data in the study area,as there are both siliciclastic and carbonate sediments on the studied seabed.It is sug-gested that appropriate empirical equations should be selected according to sediment types and sedimentary environment in future works,and the empirical equation of porosity or the two-parameter equation of porosity and grain size should be preferred.展开更多
Great efforts had been made to use indirect non-destructive tests in the geotechnical evaluation of rocks, especially sandstones, employing different empirical equations. However, most of these equations have been der...Great efforts had been made to use indirect non-destructive tests in the geotechnical evaluation of rocks, especially sandstones, employing different empirical equations. However, most of these equations have been derived from hard and compacted sandstones data</span><span style="font-family:"">;</span><span style="font-family:"">therefore, the focus of this research is on weak and weakly compacted sandstones, aiming firstly to obtain empirical equations for estimating their characteristics, secondly to demonstrate and visualize the correlations between the studied variables, and finally to cluster <span>the studied samples based on their characteristics. To attain these aims</span></span><span style="font-family:"">,</span><span style="font-family:""> twenty</span><span style="font-family:""> oriented block samples were collected from Nubia sandstone, central Eastern Desert, Golden Triangle area, Egypt. These samples were prepared and tested according to standard test methods, including uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), Schmidt rebound number (SRN), porosity (<i><i>n</i></i>), bulk density (<span>ρ</span>), and ultrasonic P-wave velocity (UPV). The loss on ignition (LOI) was also employed as a physicochemical test for classifying the studied samples and indicating pores filling materials. The results revealed that these sandstones are characterized mainly by high <i><i>n</i></i>, low <span>ρ</span>, and low UPV values and these give an indication of weakly compacted and weakly cemented sandstone with shallow burial diagenetic conditions. Based on UCS and elastic modulus values, these sandstones are mainly classified as very low strength and highly yielding rocks. The results of regression analysis show satisfactory correlations between physical and mechanical characteristics, indicating the suitability of obtained empirical equations to deduce these properties. Principal component analysis revealed that the LOI, BTS, SRN, and USC have a positive correlation to each other and weakly correlated with <i><i>ρ</i></i> and UPV, which positively correlated to each other and negatively correlated to <i><i>n</i></i>. The results of agglomerative hierarchical clustering revealed that the studied samples can group into three main clusters depending on their USC, LOI, and <i><i>n</i></i><span> </span>values.展开更多
This study was conducted on the analytic tree and got the fitting empirical equation of tree growth, in which the tree growth rate was used as the variable and time as the independent variable. The arithmetical operat...This study was conducted on the analytic tree and got the fitting empirical equation of tree growth, in which the tree growth rate was used as the variable and time as the independent variable. The arithmetical operation to the function got the mature age of tree growth, and the mature ages of the timer forest, the protection forest and the special-purpose forest of Platycladus orientalis were 71, 111 and 141 a, respectively. In addition, the application as well as the research direction and matters needing attention were proposed.展开更多
This study was conducted on the analytic tree and got the fitting empirical equation of tree growth, in which the tree growth rate was used as the variable and time as the independent variable. The arithmetical operat...This study was conducted on the analytic tree and got the fitting empirical equation of tree growth, in which the tree growth rate was used as the variable and time as the independent variable. The arithmetical operation to the function got the mature age of tree growth, and the practical and ideal mature ages of Pinus densiflora were 58 and 123.5 a, respectively. In addition, the application research direction and matters needing attention were proposed.展开更多
This study was conducted on the analytic tree and got the fitting empirical equation of tree growth, in which the tree increment was used as the variable and time as the independent variable. The arithmetical operatio...This study was conducted on the analytic tree and got the fitting empirical equation of tree growth, in which the tree increment was used as the variable and time as the independent variable. The arithmetical operation to the function gave the mature age of tree growth, and the practical mature age of Pinus thunbergii×P. densiflora was 41 a. In addition, the application as well as the research direction and matters needing attention were proposed.展开更多
Modeling and prediction of bed loads is an important but difficult issue in river engineering.The introduced empirical equations due to restricted applicability even in similar conditions provide different accuracies ...Modeling and prediction of bed loads is an important but difficult issue in river engineering.The introduced empirical equations due to restricted applicability even in similar conditions provide different accuracies with each other and measured data.In this paper,three different artificial neural networks(ANNs)including multilayer percepterons,radial based function(RBF),and generalized feed forward neural network using five dominant parameters of bed load transport formulas for the Main Fork Red River in Idaho-USA were developed.The optimum models were found through 102 data sets of flow discharge,flow velocity,water surface slopes,flow depth,and mean grain size.The deficiency of empirical equations for this river by conducted comparison between measured and predicted values was approved where the ANN models presented more consistence and closer estimation to observed data.The coefficient of determination between measured and predicted values for empirical equations varied from 0.10 to 0.21 against the 0.93 to 0.98 in ANN models.The accuracy performance of all models was evaluated and interpreted using different statistical error criteria,analytical graphs and confusion matrixes.Although the ANN models predicted compatible outputs but the RBF with 79%correct classification rate corresponding to 0.191 nctwork error was outperform than others.展开更多
Precast concrete structures have developed rapidly in the last decades due to the advantages of better quality,non-pollution and fast construction with respect to conventional cast-in-place structures.In the present s...Precast concrete structures have developed rapidly in the last decades due to the advantages of better quality,non-pollution and fast construction with respect to conventional cast-in-place structures.In the present study,a theoretical model and nonlinear 3D model are developed and established to assess the dynamic behavior of precast concrete slabs under blast load.At first,the 3D model is validated by an experiment performed by other researchers.The verified model is adopted to investigate the blast performance of fabricated concrete panels(FCPs)in terms of parameters of the explosive charge,panel thickness,and reinforcement ratio.Finally,a simplified theoretical model of the FCP under blast load is developed to predict the maximum deflection.It is indicated that the theoretical model can precisely predict the maximum displacement of FCP under blast loads.The results show that the failure modes of the panels varied from bending failure to shear failure with the mass of TNT increasing.The thickness of the panel,reinforcement ratio,and explosive charges have significant effects on the anti-blast capacity of the FCPs.展开更多
文摘The Edlén empirical equations and the two-color method are the commonly used approaches to converting a length measured in air to the corresponding length in vacuum to eliminate the influence of the refractive index of air. However, it is not well known whether the two-color method is superior to empirical equations in refractive index compensation. We investigated the uncertainties of these approaches via numerical calculations of their sensitivity coefficients of environmental parameters. On the basis of a comparison of their uncertainties, we found that in a 0% humidity environment, the two-color method had potential to provide greater measurement accuracy than the empirical equations.
基金This study was funded by the State Key Laboratory of Acoustics,Chinese Academy of Sciences(No.SKLA202007)the National Natural Science Foundation of China(Nos.41706045,42076082,41706062)+3 种基金the Director Fund of Qingdao National Laboratory for Marine Science and Technology(No.QNLM201713),the Guangdong Natural Science Foundation(No.2017A030313237)the Taishan Scholar Project Funding(No.tspd20161007)the Strate-gic Priority Research Program of the Chinese Academy of Sciences(No.XDA13010102)the Key Special Pro-ject for Introduced Talents Team of Southern Marine Sci-ence and Engineering Guangdong Laboratory(Guangzhou)(No.GML2019ZD0104).
文摘Three-hundred and thirty-one sediment cores,including six sediment types(clayey-and sandy-silt,silty-and sandy-clay,clayey-and silty-sand)were collected from the shallow and semi-deep seas of the South China Sea,and the P-wave velocities and physical properties of core sediments were measured under standard laboratory conditions.To eliminate the influence of environ-mental factors,the empirical sound speed ratio equations were established.Compared with several equations from literature,the po-rosity and wet bulk density empirical equations established in this paper agree well with Richardson and Briggs(2004)’s in-situ equations,which implies that our empirical equations can be used in the similar region of world’s oceans under certain conditions and will be useful in areas lacking first-hand P-wave speed data.However,the mean grain size equations established in this study,similar to the previous studies,have low accuracy,which may be due to the different particle arrangements and degrees of compac-tion in sediments.The results also show that for different sediment types,the equation based on all sediment data is in good agree-ment with the measured data in the study area,as there are both siliciclastic and carbonate sediments on the studied seabed.It is sug-gested that appropriate empirical equations should be selected according to sediment types and sedimentary environment in future works,and the empirical equation of porosity or the two-parameter equation of porosity and grain size should be preferred.
文摘Great efforts had been made to use indirect non-destructive tests in the geotechnical evaluation of rocks, especially sandstones, employing different empirical equations. However, most of these equations have been derived from hard and compacted sandstones data</span><span style="font-family:"">;</span><span style="font-family:"">therefore, the focus of this research is on weak and weakly compacted sandstones, aiming firstly to obtain empirical equations for estimating their characteristics, secondly to demonstrate and visualize the correlations between the studied variables, and finally to cluster <span>the studied samples based on their characteristics. To attain these aims</span></span><span style="font-family:"">,</span><span style="font-family:""> twenty</span><span style="font-family:""> oriented block samples were collected from Nubia sandstone, central Eastern Desert, Golden Triangle area, Egypt. These samples were prepared and tested according to standard test methods, including uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), Schmidt rebound number (SRN), porosity (<i><i>n</i></i>), bulk density (<span>ρ</span>), and ultrasonic P-wave velocity (UPV). The loss on ignition (LOI) was also employed as a physicochemical test for classifying the studied samples and indicating pores filling materials. The results revealed that these sandstones are characterized mainly by high <i><i>n</i></i>, low <span>ρ</span>, and low UPV values and these give an indication of weakly compacted and weakly cemented sandstone with shallow burial diagenetic conditions. Based on UCS and elastic modulus values, these sandstones are mainly classified as very low strength and highly yielding rocks. The results of regression analysis show satisfactory correlations between physical and mechanical characteristics, indicating the suitability of obtained empirical equations to deduce these properties. Principal component analysis revealed that the LOI, BTS, SRN, and USC have a positive correlation to each other and weakly correlated with <i><i>ρ</i></i> and UPV, which positively correlated to each other and negatively correlated to <i><i>n</i></i>. The results of agglomerative hierarchical clustering revealed that the studied samples can group into three main clusters depending on their USC, LOI, and <i><i>n</i></i><span> </span>values.
文摘This study was conducted on the analytic tree and got the fitting empirical equation of tree growth, in which the tree growth rate was used as the variable and time as the independent variable. The arithmetical operation to the function got the mature age of tree growth, and the mature ages of the timer forest, the protection forest and the special-purpose forest of Platycladus orientalis were 71, 111 and 141 a, respectively. In addition, the application as well as the research direction and matters needing attention were proposed.
文摘This study was conducted on the analytic tree and got the fitting empirical equation of tree growth, in which the tree growth rate was used as the variable and time as the independent variable. The arithmetical operation to the function got the mature age of tree growth, and the practical and ideal mature ages of Pinus densiflora were 58 and 123.5 a, respectively. In addition, the application research direction and matters needing attention were proposed.
文摘This study was conducted on the analytic tree and got the fitting empirical equation of tree growth, in which the tree increment was used as the variable and time as the independent variable. The arithmetical operation to the function gave the mature age of tree growth, and the practical mature age of Pinus thunbergii×P. densiflora was 41 a. In addition, the application as well as the research direction and matters needing attention were proposed.
基金The authors greatly expressed their appreciate to Dr.Abbas Abbaszadeh Shahri for his expert advice and encouragement through this study.
文摘Modeling and prediction of bed loads is an important but difficult issue in river engineering.The introduced empirical equations due to restricted applicability even in similar conditions provide different accuracies with each other and measured data.In this paper,three different artificial neural networks(ANNs)including multilayer percepterons,radial based function(RBF),and generalized feed forward neural network using five dominant parameters of bed load transport formulas for the Main Fork Red River in Idaho-USA were developed.The optimum models were found through 102 data sets of flow discharge,flow velocity,water surface slopes,flow depth,and mean grain size.The deficiency of empirical equations for this river by conducted comparison between measured and predicted values was approved where the ANN models presented more consistence and closer estimation to observed data.The coefficient of determination between measured and predicted values for empirical equations varied from 0.10 to 0.21 against the 0.93 to 0.98 in ANN models.The accuracy performance of all models was evaluated and interpreted using different statistical error criteria,analytical graphs and confusion matrixes.Although the ANN models predicted compatible outputs but the RBF with 79%correct classification rate corresponding to 0.191 nctwork error was outperform than others.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51508148)China Postdoctoral Science Foundation Funded Project(Nos.2016T90563 and 2015M581980)+1 种基金open fund of Anhui Key Laboratory of Civil Engineering Structures and Materials in Hefei University of Technology,and State Key Laboratory of Structural Analysis for Industrial Equipment(Grant No.GZ19106)The authors also highly ppreciate the acknowledgment of the China Scholarship Council(CSC).
文摘Precast concrete structures have developed rapidly in the last decades due to the advantages of better quality,non-pollution and fast construction with respect to conventional cast-in-place structures.In the present study,a theoretical model and nonlinear 3D model are developed and established to assess the dynamic behavior of precast concrete slabs under blast load.At first,the 3D model is validated by an experiment performed by other researchers.The verified model is adopted to investigate the blast performance of fabricated concrete panels(FCPs)in terms of parameters of the explosive charge,panel thickness,and reinforcement ratio.Finally,a simplified theoretical model of the FCP under blast load is developed to predict the maximum deflection.It is indicated that the theoretical model can precisely predict the maximum displacement of FCP under blast loads.The results show that the failure modes of the panels varied from bending failure to shear failure with the mass of TNT increasing.The thickness of the panel,reinforcement ratio,and explosive charges have significant effects on the anti-blast capacity of the FCPs.