Spherical objects are widely used in target localization applications,and the existing sphere localization methods with cameras or total stations both have some limitations.A new high-precision sphere localization met...Spherical objects are widely used in target localization applications,and the existing sphere localization methods with cameras or total stations both have some limitations.A new high-precision sphere localization method with a theodolite is proposed in this paper.From the view point of the theodolite,the contour points of a sphere with a known radius are measured as latitude-longitude coordinates.It is observed that the center of the target sphere is located on a cylindrical surface constructed with the latitude-longitude coordinates,and therefore the latitude-longitude coordinates of at least three contour points can be used to construct a set of ternary quadratic equations.The Gröbner basis method is used to compute at most four real solutions of the sphere center coordinates.To distinguish the only meaningful solution from the other possible real solutions,a pre-processing of the measured longitude values is also proposed.The factors affecting the positioning accuracy of the sphere center are evaluated in simulation experiments,which are used to obtain an empirical estimation model of the positioning error.Real data experiments are also performed and the results show that the proposed method can achieve high localization precision.展开更多
Well-designed airfoil is very important for high-performance rotor.This paper developed an efficient multi-objective and multi-constraint optimization design system for rotor airfoils based on RANS analysis,and verifi...Well-designed airfoil is very important for high-performance rotor.This paper developed an efficient multi-objective and multi-constraint optimization design system for rotor airfoils based on RANS analysis,and verified the performance of the optimized airfoil.Using CRA09-A as the baseline rotor airfoil,the CRA09-B optimized rotor airfoil was designed successfully.Combined with the foundation of high-precision rotor airfoil stationary test technology,the CRA09-B and CRA09-A rotor airfoils were tested in the S3 MA high-speed wind tunnel of ONERA.In order to correct the aerodynamic data,a single parameter linear wall pressure method is used to consider the tunnel effects.The results indicate that multi-objective and multi-constraint optimization design method developed in this study is reliable,and that CRA09-B optimized airfoil provides better stationary performance than CRA09-A airfoil in terms of maximum lift coefficient and lift-to-drag ratio.展开更多
The accuracy of historical situation values is required for traditional network security situation prediction(NSSP).There are discrepancies in the correlation and weighting of the various network security elements.To ...The accuracy of historical situation values is required for traditional network security situation prediction(NSSP).There are discrepancies in the correlation and weighting of the various network security elements.To solve these problems,a combined prediction model based on the temporal convolution attention network(TCAN)and bi-directional gate recurrent unit(BiGRU)network is proposed,which is optimized by singular spectrum analysis(SSA)and improved quantum particle swarmoptimization algorithm(IQPSO).This model first decomposes and reconstructs network security situation data into a series of subsequences by SSA to remove the noise from the data.Furthermore,a prediction model of TCAN-BiGRU is established respectively for each subsequence.TCAN uses the TCN to extract features from the network security situation data and the improved channel attention mechanism(CAM)to extract important feature information from TCN.BiGRU learns the before-after status of situation data to extract more feature information from sequences for prediction.Besides,IQPSO is proposed to optimize the hyperparameters of BiGRU.Finally,the prediction results of the subsequence are superimposed to obtain the final predicted value.On the one hand,IQPSO compares with other optimization algorithms in the experiment,whose performance can find the optimum value of the benchmark function many times,showing that IQPSO performs better.On the other hand,the established prediction model compares with the traditional prediction methods through the simulation experiment,whose coefficient of determination is up to 0.999 on both sets,indicating that the combined prediction model established has higher prediction accuracy.展开更多
The ability to predict tunnel deformation holds great significance for ensuring the reliability, safety, and sustainability of tunnel struc-tures. However, existing deformation prediction models often simplify or over...The ability to predict tunnel deformation holds great significance for ensuring the reliability, safety, and sustainability of tunnel struc-tures. However, existing deformation prediction models often simplify or overlook the impact of spatial characteristics on deformationby treating it as a time series prediction issue. This study utilizes monitoring data from the Grand Canyon Tunnel and introduces aneffective data-driven method for predicting tunnel deformation based on the spatio-temporal characteristics of the historical deformationof adjacent sections. The proposed model, a combination of graph attention network (GAT) and bidirectional long and short-term mem-ory network (Bi-LSTM), is equipped with robust spatio-temporal predictive capabilities. Additionally, the study explores other possiblespatial connections and the scalability of the model. The results indicate that the proposed model outperforms other deep learning mod-els, achieving favorable root mean square error (RMSE), mean absolute error (MAE), and coefficient of determination (R^(2)) values of0.34 mm, 0.23 mm, and 0.94, respectively. The graph structure based on intuitive spatial connections proves more suitable for meetingthe challenges of predicting deformation. Integrating GAT-LSTM with transfer learning technology, remains stable performance whenextended to other tunnels with limited data.展开更多
Correction to:Radiation Detection Technology and Methods(2024)8:1-1105.https://doi.org/10.1007/s41605-024-00463-y.In this article all authors name was missing in the springer link.It has been corrected.The original ar...Correction to:Radiation Detection Technology and Methods(2024)8:1-1105.https://doi.org/10.1007/s41605-024-00463-y.In this article all authors name was missing in the springer link.It has been corrected.The original article has been corrected.展开更多
Water-soil leakage due to the longitudinal dislocation opening of tunnel segments in high-permeable soil strata is crucial for ensuring the longevity of underground tunnel infrastructures.This research delves into thi...Water-soil leakage due to the longitudinal dislocation opening of tunnel segments in high-permeable soil strata is crucial for ensuring the longevity of underground tunnel infrastructures.This research delves into this complex phenomenon employing coupled computational fluiddynamics(CFD),discrete element method(DEM),and finiteelement method(FEM),considering varied tunnel buried depths and dislocation opening sizes.Two critical areas susceptible to water-soil leakage have been identified,including an‘ellipsoid’shaped area at the tunnel top and a soil sliding area perpendicular to the tunneling direction.With a narrow segment opening(3 d_(50)),the fineloss remains below 2%across various buried depths,whereas it escalates to 7.4%-30%with increasing buried depth under a slightly wider opening(3.8d_(50)).The proposed three-dimensional(3D)ellipsoid model is used to delineate the leakage region and quantify over 98%ground soil loss due to dislocation opening.Furthermore,the research reveals that soil sliding induced by water-soil leakage significantly decreases the structural shear stress on the waists and inverts of the tunnel segment,while the soil arching at the top of the tunnel would mitigate the stress release,particularly at the lower dislocated tunnel segment.展开更多
Background Low-intensity focused ultrasound stimulation(LIFUS)has been developed to enhance neurological repair and remodelling during the late acute stage of ischaemic stroke in rodents.However,the cellular and molec...Background Low-intensity focused ultrasound stimulation(LIFUS)has been developed to enhance neurological repair and remodelling during the late acute stage of ischaemic stroke in rodents.However,the cellular and molecular mechanisms of neurological repair and remodelling after LIFUS in ischaemic stroke are unclear.Methods Ultrasound stimulation was treated in adult male mice 7 days after transient middle cerebral artery occlusion.Angiogenesis was measured by laser speckle imaging and histological analyses.Electromyography and fibre photometry records were used for synaptogenesis.Brain atrophy volume and neurobehaviour were assessed 0–14 days after ischaemia.iTRAQ proteomic analysis was performed to explore the differentially expressed protein.scRNA-seq was used for subcluster analysis of astrocytes.Fluorescence in situ hybridisation and Western blot detected the expression of HMGB1 and CAMK2N1.Results Optimal ultrasound stimulation increased cerebral blood flow,and improved neurobehavioural outcomes in ischaemic mice(p<0.05).iTRAQ proteomic analysis revealed that the expression of HMGB1 increased and CAMK2N1 decreased in the ipsilateral hemisphere of the brain at 14 days after focal cerebral ischaemia with ultrasound treatment(p<0.05).scRNA-seq revealed that this expression pattern belonged to a subcluster of astrocytes after LIFUS in the ischaemic brain.LIFUS upregulated HMGB1 expression,accompanied by VEGFA elevation compared with the control group(p<0.05).Inhibition of HMGB1 expression in astrocytes decreased microvessels counts and cerebral blood flow(p<0.05).LIFUS reduced CAMK2N1 expression level,accompanied by increased extracellular calcium ions and glutamatergic synapses(p<0.05).CAMK2N1 overexpression in astrocytes decreased dendritic spines,and aggravated neurobehavioural outcomes(p<0.05).Conclusion Our results demonstrated that LIFUS promoted angiogenesis and synaptogenesis after focal cerebral ischaemia by upregulating HMGB1 and downregulating CAMK2N1 in a subcluster of astrocytes,suggesting that LIFUS activated specific astrocyte subcluster could be a key target for ischaemic brain therapy.展开更多
The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 3...The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.展开更多
Clogging is a major geohazards risk in mechanized tunnelling through cohesive soils.Clay clogging results from the high adhesion between the clay and metal.Based on the water film theory and Reynolds fluid equation,th...Clogging is a major geohazards risk in mechanized tunnelling through cohesive soils.Clay clogging results from the high adhesion between the clay and metal.Based on the water film theory and Reynolds fluid equation,the interfacial adhesion between metal and soil is simplified in this study as viscous hydrodynamic behavior between planes.Considering the influence of capillary force and the viscous force of water film at the interface between metal and soil,a theoretical calculation model of interfacial adhesion between metal and soil is established.The influence of water film thickness and separation rate on the interfacial adhesion between metal and soil is qualitatively analyzed.Then,the adhesion stress between the clay and the metal surface was tested with a pullout test and the influence of moisture content,pullout rates and types of clay minerals on the adhesion stress was analyzed.Finally,the calculation model of adhesion force was compared with the experimental results.The calculation model of soil adhesion stress established in this paper can quantitatively describe the relationship between soil adhesion force and moisture content and can also qualitatively reveal the influence mechanism of soil moisture content on adhesion stress.展开更多
Considering the B mesonic wave function φ_(B2),B→PV decays are re studied in the leading order for three scenarios using the perturbative QCD approach within the standard model,where P=π and K,and V denotes the gro...Considering the B mesonic wave function φ_(B2),B→PV decays are re studied in the leading order for three scenarios using the perturbative QCD approach within the standard model,where P=π and K,and V denotes the ground SU(3) vector mesons.It is found that contributions from φ_(B2) can enhance most branching ratios and are helpful for improving the overall consistency of branching ratios between the updated calculations and available data,although there are still several discrepancies between the experimental and theoretical results.展开更多
The Bu→ψM decays are studied with the perturbative QCD approach, where the psion ψ=ψ（2S）, ψ（3770）, ψ（4040） and ψ（4160）, and the light meson M = π, K, ρ and K^＊. The factorizable and non-factorizable ...The Bu→ψM decays are studied with the perturbative QCD approach, where the psion ψ=ψ（2S）, ψ（3770）, ψ（4040） and ψ（4160）, and the light meson M = π, K, ρ and K^＊. The factorizable and non-factorizable contributions, and the S-D wave mixing effects on the psions, are considered in the calculation. With appropriate inputs, the branching ratios for the Bu→ψM decays are generally coincident with the experimental data within errors. However, due to the large theoretical and experimental errors, it is impossible for the moment to give a severe constraint on the S-D wave mixing angles.展开更多
Although J/ψ weak decays are rare,they are possible within the standard model of elementary particles.Inspired by the potential prospects of the future intensity frontier,the C parity violating J/ψ→πη^(′),ηη′...Although J/ψ weak decays are rare,they are possible within the standard model of elementary particles.Inspired by the potential prospects of the future intensity frontier,the C parity violating J/ψ→πη^(′),ηη′decays and the strangeness changing J/ψ→πK,Kη^(′)decays are studied via the perturbative QCD approach.It is determined that the J/ψ→ηη^(′) decays have relatively large branching ratios,approximately on the order of 10^(11),which might be within the measurement capability and sensitivity of the future STCF experiment.展开更多
基金supported in part by the National Natural Science Foundation of China under Grants 61703373,61873246,U1504604in part by the Key research project of Henan Province Universities under Grant 19A413014.
文摘Spherical objects are widely used in target localization applications,and the existing sphere localization methods with cameras or total stations both have some limitations.A new high-precision sphere localization method with a theodolite is proposed in this paper.From the view point of the theodolite,the contour points of a sphere with a known radius are measured as latitude-longitude coordinates.It is observed that the center of the target sphere is located on a cylindrical surface constructed with the latitude-longitude coordinates,and therefore the latitude-longitude coordinates of at least three contour points can be used to construct a set of ternary quadratic equations.The Gröbner basis method is used to compute at most four real solutions of the sphere center coordinates.To distinguish the only meaningful solution from the other possible real solutions,a pre-processing of the measured longitude values is also proposed.The factors affecting the positioning accuracy of the sphere center are evaluated in simulation experiments,which are used to obtain an empirical estimation model of the positioning error.Real data experiments are also performed and the results show that the proposed method can achieve high localization precision.
基金supported by the National Natural Science Foundation of China(No.11902335)。
文摘Well-designed airfoil is very important for high-performance rotor.This paper developed an efficient multi-objective and multi-constraint optimization design system for rotor airfoils based on RANS analysis,and verified the performance of the optimized airfoil.Using CRA09-A as the baseline rotor airfoil,the CRA09-B optimized rotor airfoil was designed successfully.Combined with the foundation of high-precision rotor airfoil stationary test technology,the CRA09-B and CRA09-A rotor airfoils were tested in the S3 MA high-speed wind tunnel of ONERA.In order to correct the aerodynamic data,a single parameter linear wall pressure method is used to consider the tunnel effects.The results indicate that multi-objective and multi-constraint optimization design method developed in this study is reliable,and that CRA09-B optimized airfoil provides better stationary performance than CRA09-A airfoil in terms of maximum lift coefficient and lift-to-drag ratio.
基金This work is supported by the National Science Foundation of China(61806219,61703426,and 61876189)by National Science Foundation of Shaanxi Provence(2021JM-226)by the Young Talent fund of the University,and the Association for Science and Technology in Shaanxi,China(20190108,20220106)by and the Innovation Capability Support Plan of Shaanxi,China(2020KJXX-065).
文摘The accuracy of historical situation values is required for traditional network security situation prediction(NSSP).There are discrepancies in the correlation and weighting of the various network security elements.To solve these problems,a combined prediction model based on the temporal convolution attention network(TCAN)and bi-directional gate recurrent unit(BiGRU)network is proposed,which is optimized by singular spectrum analysis(SSA)and improved quantum particle swarmoptimization algorithm(IQPSO).This model first decomposes and reconstructs network security situation data into a series of subsequences by SSA to remove the noise from the data.Furthermore,a prediction model of TCAN-BiGRU is established respectively for each subsequence.TCAN uses the TCN to extract features from the network security situation data and the improved channel attention mechanism(CAM)to extract important feature information from TCN.BiGRU learns the before-after status of situation data to extract more feature information from sequences for prediction.Besides,IQPSO is proposed to optimize the hyperparameters of BiGRU.Finally,the prediction results of the subsequence are superimposed to obtain the final predicted value.On the one hand,IQPSO compares with other optimization algorithms in the experiment,whose performance can find the optimum value of the benchmark function many times,showing that IQPSO performs better.On the other hand,the established prediction model compares with the traditional prediction methods through the simulation experiment,whose coefficient of determination is up to 0.999 on both sets,indicating that the combined prediction model established has higher prediction accuracy.
基金supported by the Sichuan Pro-vince Natural Science Foundation Innovative Research Group Project(Grant No.2024NSFTD0013).
文摘The ability to predict tunnel deformation holds great significance for ensuring the reliability, safety, and sustainability of tunnel struc-tures. However, existing deformation prediction models often simplify or overlook the impact of spatial characteristics on deformationby treating it as a time series prediction issue. This study utilizes monitoring data from the Grand Canyon Tunnel and introduces aneffective data-driven method for predicting tunnel deformation based on the spatio-temporal characteristics of the historical deformationof adjacent sections. The proposed model, a combination of graph attention network (GAT) and bidirectional long and short-term mem-ory network (Bi-LSTM), is equipped with robust spatio-temporal predictive capabilities. Additionally, the study explores other possiblespatial connections and the scalability of the model. The results indicate that the proposed model outperforms other deep learning mod-els, achieving favorable root mean square error (RMSE), mean absolute error (MAE), and coefficient of determination (R^(2)) values of0.34 mm, 0.23 mm, and 0.94, respectively. The graph structure based on intuitive spatial connections proves more suitable for meetingthe challenges of predicting deformation. Integrating GAT-LSTM with transfer learning technology, remains stable performance whenextended to other tunnels with limited data.
文摘Correction to:Radiation Detection Technology and Methods(2024)8:1-1105.https://doi.org/10.1007/s41605-024-00463-y.In this article all authors name was missing in the springer link.It has been corrected.The original article has been corrected.
基金supported by the National Natural Science Foundation of China(Grant Nos.52090084 and 52208354)the Shenzhen Science and Technology Program(Grant No.KQTD20221101093555006).
文摘Water-soil leakage due to the longitudinal dislocation opening of tunnel segments in high-permeable soil strata is crucial for ensuring the longevity of underground tunnel infrastructures.This research delves into this complex phenomenon employing coupled computational fluiddynamics(CFD),discrete element method(DEM),and finiteelement method(FEM),considering varied tunnel buried depths and dislocation opening sizes.Two critical areas susceptible to water-soil leakage have been identified,including an‘ellipsoid’shaped area at the tunnel top and a soil sliding area perpendicular to the tunneling direction.With a narrow segment opening(3 d_(50)),the fineloss remains below 2%across various buried depths,whereas it escalates to 7.4%-30%with increasing buried depth under a slightly wider opening(3.8d_(50)).The proposed three-dimensional(3D)ellipsoid model is used to delineate the leakage region and quantify over 98%ground soil loss due to dislocation opening.Furthermore,the research reveals that soil sliding induced by water-soil leakage significantly decreases the structural shear stress on the waists and inverts of the tunnel segment,while the soil arching at the top of the tunnel would mitigate the stress release,particularly at the lower dislocated tunnel segment.
基金Scientific Research and Innovation Program of Shanghai Education Commission 2019-01-07-00-02-E00064(G-YY)National Natural Science Foundation of China 82271320(ZZ),82172529(WJ),81974179(ZZ),82071284(YT)+2 种基金Scientific and Technological Innovation Act Program of Shanghai Science and Technology Commission,20JC1411900(G-YY)National Key R&D Program of China 2022YFA1603604(ZZ),2019YFA0112000(YT),2018YFA0701400(WQ)and 2021ZD0200401(WQ)Shenzhen Foundation Grant JCYJ20200109114237902(WQ),SGDX2020110309400200(WQ).
文摘Background Low-intensity focused ultrasound stimulation(LIFUS)has been developed to enhance neurological repair and remodelling during the late acute stage of ischaemic stroke in rodents.However,the cellular and molecular mechanisms of neurological repair and remodelling after LIFUS in ischaemic stroke are unclear.Methods Ultrasound stimulation was treated in adult male mice 7 days after transient middle cerebral artery occlusion.Angiogenesis was measured by laser speckle imaging and histological analyses.Electromyography and fibre photometry records were used for synaptogenesis.Brain atrophy volume and neurobehaviour were assessed 0–14 days after ischaemia.iTRAQ proteomic analysis was performed to explore the differentially expressed protein.scRNA-seq was used for subcluster analysis of astrocytes.Fluorescence in situ hybridisation and Western blot detected the expression of HMGB1 and CAMK2N1.Results Optimal ultrasound stimulation increased cerebral blood flow,and improved neurobehavioural outcomes in ischaemic mice(p<0.05).iTRAQ proteomic analysis revealed that the expression of HMGB1 increased and CAMK2N1 decreased in the ipsilateral hemisphere of the brain at 14 days after focal cerebral ischaemia with ultrasound treatment(p<0.05).scRNA-seq revealed that this expression pattern belonged to a subcluster of astrocytes after LIFUS in the ischaemic brain.LIFUS upregulated HMGB1 expression,accompanied by VEGFA elevation compared with the control group(p<0.05).Inhibition of HMGB1 expression in astrocytes decreased microvessels counts and cerebral blood flow(p<0.05).LIFUS reduced CAMK2N1 expression level,accompanied by increased extracellular calcium ions and glutamatergic synapses(p<0.05).CAMK2N1 overexpression in astrocytes decreased dendritic spines,and aggravated neurobehavioural outcomes(p<0.05).Conclusion Our results demonstrated that LIFUS promoted angiogenesis and synaptogenesis after focal cerebral ischaemia by upregulating HMGB1 and downregulating CAMK2N1 in a subcluster of astrocytes,suggesting that LIFUS activated specific astrocyte subcluster could be a key target for ischaemic brain therapy.
基金support from diverse funding sources,including the National Key Program for S&T Research and Development of the Ministry of Science and Technology(MOST),Yifang Wang's Science Studio of the Ten Thousand Talents Project,the CAS Key Foreign Cooperation Grant,the National Natural Science Foundation of China(NSFC)Beijing Municipal Science&Technology Commission,the CAS Focused Science Grant,the IHEP Innovation Grant,the CAS Lead Special Training Programthe CAS Center for Excellence in Particle Physics,the CAS International Partnership Program,and the CAS/SAFEA International Partnership Program for Creative Research Teams.
文摘The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.
基金financially supported by the National Natural Science Foundation of China(Grant No.52078428)the Sichuan Outstanding Young Science and Technology Talent Project(Grant No.2020JDJQ0032).
文摘Clogging is a major geohazards risk in mechanized tunnelling through cohesive soils.Clay clogging results from the high adhesion between the clay and metal.Based on the water film theory and Reynolds fluid equation,the interfacial adhesion between metal and soil is simplified in this study as viscous hydrodynamic behavior between planes.Considering the influence of capillary force and the viscous force of water film at the interface between metal and soil,a theoretical calculation model of interfacial adhesion between metal and soil is established.The influence of water film thickness and separation rate on the interfacial adhesion between metal and soil is qualitatively analyzed.Then,the adhesion stress between the clay and the metal surface was tested with a pullout test and the influence of moisture content,pullout rates and types of clay minerals on the adhesion stress was analyzed.Finally,the calculation model of adhesion force was compared with the experimental results.The calculation model of soil adhesion stress established in this paper can quantitatively describe the relationship between soil adhesion force and moisture content and can also qualitatively reveal the influence mechanism of soil moisture content on adhesion stress.
基金Supported by the National Natural Science Foundation of China (11705047,U1632109,11875122)the Natural Science Foundation of Henan Province(222300420479)+1 种基金the Excellent Youth Foundation of Henan Province (212300410010)the Youth Talent Support Program of Henan Province (ZYQR201912178)。
文摘Considering the B mesonic wave function φ_(B2),B→PV decays are re studied in the leading order for three scenarios using the perturbative QCD approach within the standard model,where P=π and K,and V denotes the ground SU(3) vector mesons.It is found that contributions from φ_(B2) can enhance most branching ratios and are helpful for improving the overall consistency of branching ratios between the updated calculations and available data,although there are still several discrepancies between the experimental and theoretical results.
基金Supported by the National Natural Science Foundation of China(11705047,U1632109,11547014,11475055)Open Research Program of Large Research Infrastructures(2017)Chinese Academy of Sciences
文摘The Bu→ψM decays are studied with the perturbative QCD approach, where the psion ψ=ψ（2S）, ψ（3770）, ψ（4040） and ψ（4160）, and the light meson M = π, K, ρ and K^＊. The factorizable and non-factorizable contributions, and the S-D wave mixing effects on the psions, are considered in the calculation. With appropriate inputs, the branching ratios for the Bu→ψM decays are generally coincident with the experimental data within errors. However, due to the large theoretical and experimental errors, it is impossible for the moment to give a severe constraint on the S-D wave mixing angles.
基金Supported by the National Natural Science Foundation of China(11705047,11981240403,U1632109,11547014,11875122)the Program for Innovative Research Team in University of Henan Province(19IRTSTHN018)+1 种基金the Excellent Youth Foundation of Henan Province(212300410010)the Chinese Academy of Sciences Large-Scale Scientific Facility Program(1G2017IHEPKFYJ01)。
文摘Although J/ψ weak decays are rare,they are possible within the standard model of elementary particles.Inspired by the potential prospects of the future intensity frontier,the C parity violating J/ψ→πη^(′),ηη′decays and the strangeness changing J/ψ→πK,Kη^(′)decays are studied via the perturbative QCD approach.It is determined that the J/ψ→ηη^(′) decays have relatively large branching ratios,approximately on the order of 10^(11),which might be within the measurement capability and sensitivity of the future STCF experiment.
