To guarantee safe and efficient tunneling of a tunnel boring machine(TBM),rapid and accurate judgment of the rock mass condition is essential.Based on fuzzy C-means clustering,this paper proposes a grouped machine lea...To guarantee safe and efficient tunneling of a tunnel boring machine(TBM),rapid and accurate judgment of the rock mass condition is essential.Based on fuzzy C-means clustering,this paper proposes a grouped machine learning method for predicting rock mass parameters.An elaborate data set on field rock mass is collected,which also matches field TBM tunneling.Meanwhile,target stratum samples are divided into several clusters by fuzzy C-means clustering,and multiple submodels are trained by samples in different clusters with the input of pretreated TBM tunneling data and the output of rock mass parameter data.Each testing sample or newly encountered tunneling condition can be predicted by multiple submodels with the weight of the membership degree of the sample to each cluster.The proposed method has been realized by 100 training samples and verified by 30 testing samples collected from the C1 part of the Pearl Delta water resources allocation project.The average percentage error of uniaxial compressive strength and joint frequency(Jf)of the 30 testing samples predicted by the pure back propagation(BP)neural network is 13.62%and 12.38%,while that predicted by the BP neural network combined with fuzzy C-means is 7.66%and6.40%,respectively.In addition,by combining fuzzy C-means clustering,the prediction accuracies of support vector regression and random forest are also improved to different degrees,which demonstrates that fuzzy C-means clustering is helpful for improving the prediction accuracy of machine learning and thus has good applicability.Accordingly,the proposed method is valuable for predicting rock mass parameters during TBM tunneling.展开更多
Rigid blocking masses are located in the typical base structure of a power cabin based on the impedance mismatch principle.By combining the acoustic-structural coupling method and statistical energy analysis,the full-...Rigid blocking masses are located in the typical base structure of a power cabin based on the impedance mismatch principle.By combining the acoustic-structural coupling method and statistical energy analysis,the full-band vibration and sound radiation reduction effect of vibration isolation masses located in a base structure was researched.The influence of the blocking mass’ cross-section size and shape parameters and the layout location of the base isolation performance was discussed.Furthermore,the effectiveness of rigid vibration isolation design of the base structure was validated.The results show that the medium and high frequency vibration and sound radiation of a power cabin are effectively reduced by a blocking mass.Concerning weight increment and section requirement,suitably increasing the blocking mass size and section height and reducing section width can result in an efficiency-cost ratio.展开更多
The artificial neutral network(ANN) has the ability that self-study and self-remember, its 3 layers BP network has been applied extensively, but sometimes because of serious multi-correlation between the variables, an...The artificial neutral network(ANN) has the ability that self-study and self-remember, its 3 layers BP network has been applied extensively, but sometimes because of serious multi-correlation between the variables, and a few observations while many variables, there usually will result into paralyzing in study, and the neutral network further development is restricted in the system to some extent. The partial least square regression(PLS) has its advantage of building the calculation model between the variables with strong multi-correlation, especially much effective on a few data and many variables. So a new and effective method-improved neutral network has been introduced-the neutral network based on the PLS. The results of example show the improved method has a few calculations and high accuracy, and provide a new way for valuing the rock mass mechanical parameters.展开更多
Sampling ports were firstly drilled on a ZGM95 coal mill in the power plant in China, and the coal samples from various points in the pulverizer were collected under the different operation conditions. The prop- erty ...Sampling ports were firstly drilled on a ZGM95 coal mill in the power plant in China, and the coal samples from various points in the pulverizer were collected under the different operation conditions. The prop- erty of the sampling material from the mill was analyzed, applying the float-sink test, size distribution analysis, proximate analysis and so on. It was indicated that the ＋250 I^m fraction in the pulverized fuel accounted for only 0.02%, while it was 83.2% in the new feed. The circulating ratio and coal flow in the separator and the cone zone were calculated using the mass balance of the circulating load. So, the cir- culating ratio in the separator of the pulverizer was between 8 and 13, and the circulating ratio, the feed flow of separator and cone zone all raised with the increase of the air volume. Furthermore, the parameters of the separation functions were obtained based on the fitting method. It was shown that the mean value of the shape factor B was 0.7617, and the parameter D which is the particle size at 50% cumulative yield in the separator almost kept unchanged.展开更多
We have considered a hot neutron star with a quark core, a mixed phase of quark-hadron matter, and a hadronic matter crust and have determined the equation of state of the hadronic phase and the quark phase. We have t...We have considered a hot neutron star with a quark core, a mixed phase of quark-hadron matter, and a hadronic matter crust and have determined the equation of state of the hadronic phase and the quark phase. We have then found the equation of state of the mixed phase under the Gibbs conditions. Finally, we have computed the structure of a hot neutron star with a quark core and compared our results with those of the neutron star without a quark core. For the quark matter calculations, we have used the MIT bag model in which the total energy of the system is considered as the kinetic energy of the particles plus a bag constant. For the hadronic matter calculations, we have used the lowest order constrained variational formalism. Our calculations show that the results for the maximum gravitational mass of a hot neutron star with a quark core are substantially different from those of a neutron star without the quark core.展开更多
A generalized scheme for the construction of coherent states in the context of position-dependent effective mass systems has been presented. This formalism is based on the ladder operators and associated algebra of th...A generalized scheme for the construction of coherent states in the context of position-dependent effective mass systems has been presented. This formalism is based on the ladder operators and associated algebra of the system which are obtained using the concepts of supersymmetric quantum mechanics and the property of shape invariance. In order to exemplify the general results and to analyze the properties of the coherent states, several examples have been considered.展开更多
The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods fo...The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods for centroid measurement often necessitate custom equipment and specialized positioning devices,leading to high costs and limited accuracy.Here,we present a centroid measurement method that integrates 3D scanning technology,enabling accurate measurement of centroid across various types of objects without the need for specialized positioning fixtures.A theoretical framework for centroid measurement was established,which combined the principle of the multi-point weighing method with 3D scanning technology.The measurement accuracy was evaluated using a designed standard component.Experimental results demonstrate that the discrepancies between the theoretical and the measured centroid of a standard component with various materials and complex shapes in the X,Y,and Z directions are 0.003 mm,0.009 mm,and 0.105 mm,respectively,yielding a spatial deviation of 0.106 mm.Qualitative verification was conducted through experimental validation of three distinct types.They confirmed the reliability of the proposed method,which allowed for accurate centroid measurements of various products without requiring positioning fixtures.This advancement significantly broadened the applicability and scope of centroid measurement devices,offering new theoretical insights and methodologies for the measurement of complex parts and systems.展开更多
In this work, we first obtain the hydrostatic equilibrium equation in dilaton gravity. Then, we examine some of the structural characteristics of a strange quark star in dilaton gravity in the context of Einstein grav...In this work, we first obtain the hydrostatic equilibrium equation in dilaton gravity. Then, we examine some of the structural characteristics of a strange quark star in dilaton gravity in the context of Einstein gravity. We show that the variations of dilaton parameter do not affect the maximum mass, but variations in the cosmological constant lead to changes in the structural characteristics of the quark star. We investigate the stability of strange quark stars by applying the MIT bag model with dilaton gravity. We also provide limiting values for the dilaton field parameter and cosmological constant. We also study the effects of dilaton gravity on the other properties of a quark star such as the mean density and gravitational redshift.We conclude that the last reported value for the cosmological constant does not affect the maximum mass of a strange quark star.展开更多
The objective of this work is to study a comprehensive performance of three types of structured parking in CO2 absorption application. One of them was developed in Mexican National Institute of Nuclear Research （ININ...The objective of this work is to study a comprehensive performance of three types of structured parking in CO2 absorption application. One of them was developed in Mexican National Institute of Nuclear Research （ININ abbreviation in Spanish of Instituto Nacional de lnvestigaciones Nucleates）, and the other two, Sulzer BX and Mellapak 250Y, by Sulzer Brothers Ltd. Aqueous solution of 30 weight % Monoethanolamine was employed as absorption solvent. The performance of the structured packing was evaluated in terms of the pressure drop, holds up, volumetric overall mass transfer coefficient and height of a global transfer unit of gas and liquid side as a function of the process operating parameters including gas and liquid load, by using hydrodynamic and mass transfer models. The pressure drop of ININ packing was higher than Sulzer BX and Mellapak 250Y, and volumetric overall mass transfer coefficient values are similar of Sulzer BX values and higher than Mellapak 250Y, although Sulzer BX and ININI 8 packing had less height of a global transfer unit of gas side values than Mellapak 250Y packing. The above-mentioned are consequences of the geometric characteristics and operational behavior for each packing.展开更多
We investigate the effects of strong magnetic fields upon the large-scale properties of neutron and protoneutron stars. In our calculations, the neutron star mat- ter was approximated by pure neutron matter. Using the...We investigate the effects of strong magnetic fields upon the large-scale properties of neutron and protoneutron stars. In our calculations, the neutron star mat- ter was approximated by pure neutron matter. Using the lowest order constrained vari- ational approach at zero and finite temperatures, and employing AV18 potential, we present the effects of strong magnetic fields on the gravitational mass, radius, and gravitational redshift of neutron and protoneutron stars. It is found that the equation of state for a neutron star becomes stiffer with an increase of magnetic field and tem- perature. This leads to larger values of the maximum mass and radius for the neutron stars.展开更多
基金Natural Science Foundation of Shandong Province,Grant/Award Number:ZR202103010903Doctoral Fund of Shandong Jianzhu University,Grant/Award Number:X21101Z。
文摘To guarantee safe and efficient tunneling of a tunnel boring machine(TBM),rapid and accurate judgment of the rock mass condition is essential.Based on fuzzy C-means clustering,this paper proposes a grouped machine learning method for predicting rock mass parameters.An elaborate data set on field rock mass is collected,which also matches field TBM tunneling.Meanwhile,target stratum samples are divided into several clusters by fuzzy C-means clustering,and multiple submodels are trained by samples in different clusters with the input of pretreated TBM tunneling data and the output of rock mass parameter data.Each testing sample or newly encountered tunneling condition can be predicted by multiple submodels with the weight of the membership degree of the sample to each cluster.The proposed method has been realized by 100 training samples and verified by 30 testing samples collected from the C1 part of the Pearl Delta water resources allocation project.The average percentage error of uniaxial compressive strength and joint frequency(Jf)of the 30 testing samples predicted by the pure back propagation(BP)neural network is 13.62%and 12.38%,while that predicted by the BP neural network combined with fuzzy C-means is 7.66%and6.40%,respectively.In addition,by combining fuzzy C-means clustering,the prediction accuracies of support vector regression and random forest are also improved to different degrees,which demonstrates that fuzzy C-means clustering is helpful for improving the prediction accuracy of machine learning and thus has good applicability.Accordingly,the proposed method is valuable for predicting rock mass parameters during TBM tunneling.
基金Supported by the International Cooperation Program under Grant No.2007DFR80340the National Natural Science Foundation of China under Grant No.50779007
文摘Rigid blocking masses are located in the typical base structure of a power cabin based on the impedance mismatch principle.By combining the acoustic-structural coupling method and statistical energy analysis,the full-band vibration and sound radiation reduction effect of vibration isolation masses located in a base structure was researched.The influence of the blocking mass’ cross-section size and shape parameters and the layout location of the base isolation performance was discussed.Furthermore,the effectiveness of rigid vibration isolation design of the base structure was validated.The results show that the medium and high frequency vibration and sound radiation of a power cabin are effectively reduced by a blocking mass.Concerning weight increment and section requirement,suitably increasing the blocking mass size and section height and reducing section width can result in an efficiency-cost ratio.
基金Supported by Henan Innovation Project for University Prominent Research Talents(2005KYCX015) Henan Innovation Talents Project for University
文摘The artificial neutral network(ANN) has the ability that self-study and self-remember, its 3 layers BP network has been applied extensively, but sometimes because of serious multi-correlation between the variables, and a few observations while many variables, there usually will result into paralyzing in study, and the neutral network further development is restricted in the system to some extent. The partial least square regression(PLS) has its advantage of building the calculation model between the variables with strong multi-correlation, especially much effective on a few data and many variables. So a new and effective method-improved neutral network has been introduced-the neutral network based on the PLS. The results of example show the improved method has a few calculations and high accuracy, and provide a new way for valuing the rock mass mechanical parameters.
基金The financial support from the Australian Government as Part of the Asia-Pacific Partnership on Clean Development and Climate,and the National Natural Science Foundation of China (Nos. 51074156 and 51274196)
文摘Sampling ports were firstly drilled on a ZGM95 coal mill in the power plant in China, and the coal samples from various points in the pulverizer were collected under the different operation conditions. The prop- erty of the sampling material from the mill was analyzed, applying the float-sink test, size distribution analysis, proximate analysis and so on. It was indicated that the ＋250 I^m fraction in the pulverized fuel accounted for only 0.02%, while it was 83.2% in the new feed. The circulating ratio and coal flow in the separator and the cone zone were calculated using the mass balance of the circulating load. So, the cir- culating ratio in the separator of the pulverizer was between 8 and 13, and the circulating ratio, the feed flow of separator and cone zone all raised with the increase of the air volume. Furthermore, the parameters of the separation functions were obtained based on the fitting method. It was shown that the mean value of the shape factor B was 0.7617, and the parameter D which is the particle size at 50% cumulative yield in the separator almost kept unchanged.
基金Financial support from the Research Council of Islamic Azad University
文摘We have considered a hot neutron star with a quark core, a mixed phase of quark-hadron matter, and a hadronic matter crust and have determined the equation of state of the hadronic phase and the quark phase. We have then found the equation of state of the mixed phase under the Gibbs conditions. Finally, we have computed the structure of a hot neutron star with a quark core and compared our results with those of the neutron star without a quark core. For the quark matter calculations, we have used the MIT bag model in which the total energy of the system is considered as the kinetic energy of the particles plus a bag constant. For the hadronic matter calculations, we have used the lowest order constrained variational formalism. Our calculations show that the results for the maximum gravitational mass of a hot neutron star with a quark core are substantially different from those of a neutron star without the quark core.
文摘A generalized scheme for the construction of coherent states in the context of position-dependent effective mass systems has been presented. This formalism is based on the ladder operators and associated algebra of the system which are obtained using the concepts of supersymmetric quantum mechanics and the property of shape invariance. In order to exemplify the general results and to analyze the properties of the coherent states, several examples have been considered.
基金supported by National Natural Science Foundation of China(No.52176122).
文摘The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods for centroid measurement often necessitate custom equipment and specialized positioning devices,leading to high costs and limited accuracy.Here,we present a centroid measurement method that integrates 3D scanning technology,enabling accurate measurement of centroid across various types of objects without the need for specialized positioning fixtures.A theoretical framework for centroid measurement was established,which combined the principle of the multi-point weighing method with 3D scanning technology.The measurement accuracy was evaluated using a designed standard component.Experimental results demonstrate that the discrepancies between the theoretical and the measured centroid of a standard component with various materials and complex shapes in the X,Y,and Z directions are 0.003 mm,0.009 mm,and 0.105 mm,respectively,yielding a spatial deviation of 0.106 mm.Qualitative verification was conducted through experimental validation of three distinct types.They confirmed the reliability of the proposed method,which allowed for accurate centroid measurements of various products without requiring positioning fixtures.This advancement significantly broadened the applicability and scope of centroid measurement devices,offering new theoretical insights and methodologies for the measurement of complex parts and systems.
基金supported by the Research Institute for Astronomy and Astrophysics of Maragha
文摘In this work, we first obtain the hydrostatic equilibrium equation in dilaton gravity. Then, we examine some of the structural characteristics of a strange quark star in dilaton gravity in the context of Einstein gravity. We show that the variations of dilaton parameter do not affect the maximum mass, but variations in the cosmological constant lead to changes in the structural characteristics of the quark star. We investigate the stability of strange quark stars by applying the MIT bag model with dilaton gravity. We also provide limiting values for the dilaton field parameter and cosmological constant. We also study the effects of dilaton gravity on the other properties of a quark star such as the mean density and gravitational redshift.We conclude that the last reported value for the cosmological constant does not affect the maximum mass of a strange quark star.
文摘The objective of this work is to study a comprehensive performance of three types of structured parking in CO2 absorption application. One of them was developed in Mexican National Institute of Nuclear Research （ININ abbreviation in Spanish of Instituto Nacional de lnvestigaciones Nucleates）, and the other two, Sulzer BX and Mellapak 250Y, by Sulzer Brothers Ltd. Aqueous solution of 30 weight % Monoethanolamine was employed as absorption solvent. The performance of the structured packing was evaluated in terms of the pressure drop, holds up, volumetric overall mass transfer coefficient and height of a global transfer unit of gas and liquid side as a function of the process operating parameters including gas and liquid load, by using hydrodynamic and mass transfer models. The pressure drop of ININ packing was higher than Sulzer BX and Mellapak 250Y, and volumetric overall mass transfer coefficient values are similar of Sulzer BX values and higher than Mellapak 250Y, although Sulzer BX and ININI 8 packing had less height of a global transfer unit of gas side values than Mellapak 250Y packing. The above-mentioned are consequences of the geometric characteristics and operational behavior for each packing.
基金supported financially by the Center for Excellence in Astronomy and Astrophysics (CEAA-RIAAM)
文摘We investigate the effects of strong magnetic fields upon the large-scale properties of neutron and protoneutron stars. In our calculations, the neutron star mat- ter was approximated by pure neutron matter. Using the lowest order constrained vari- ational approach at zero and finite temperatures, and employing AV18 potential, we present the effects of strong magnetic fields on the gravitational mass, radius, and gravitational redshift of neutron and protoneutron stars. It is found that the equation of state for a neutron star becomes stiffer with an increase of magnetic field and tem- perature. This leads to larger values of the maximum mass and radius for the neutron stars.
