It is inevitable to encounter fault zones in tunnel construction.These faults can lead to significant deformations and potential collapses of the surrounding rock in the tunnel.Therefore,it is crucial to study the inf...It is inevitable to encounter fault zones in tunnel construction.These faults can lead to significant deformations and potential collapses of the surrounding rock in the tunnel.Therefore,it is crucial to study the influence of different fault angles on tunnel deformation.The Tabaiyi Tunnel,located in Yunnan Province of China passes through a multi-stage fault zone.The dynamic response characteristics of the surrounding rock in the Tabaiyi Tunnel were studied under various fault dip angles and the most unfavorable angle was identified.Physical model tests were conducted using two types of anchor cables with specific parameters.Additionally,a relationship between the engineering rock mass and energy absorption by the anchor cables was established,demonstrating the advantages of negative Poisson's ratio(NPR)anchor cables.Experimental results indicate that stress concentration tends to occur at the junctions between faults and the surrounding rock mass.Tunnels supported by NPR anchor cables effectively mitigate amplification effects,achieving energy absorption increases of up to 87%compared to positive Poisson's ratio(PR)anchor cables.Furthermore,the highest acceleration amplification was observed at a fault dip angle of 45°,with peak acceleration reaching twice that of the original input wave,indicating that this angle should be avoided in tunnel design.These findings provide valuable insights for the safe management of tunnels traversing fault zones.展开更多
Solar energy,a renewable resource,can be harnessed instead of fossil fuels to generate power and heat.One effective method for converting solar energy into heat is through a solar air heating(SAH)system.The theoretica...Solar energy,a renewable resource,can be harnessed instead of fossil fuels to generate power and heat.One effective method for converting solar energy into heat is through a solar air heating(SAH)system.The theoretical investigation focused on the thermal performance of various V-groove angles on a corrugated absorber plate.The researchers maintained the exterior dimensions and constraints of the absorber plate while increasing its surface area by using a corrugated absorber surface.For the simulation,three different V-groove angles were employed:45°,30°,and 15°.The temperature and air flow rate into the system had been set at 30℃ and 0.15 m/s,respectively four various solar radiation intensities have been examined for each of the variables.The governing equations associated with the standard design,including the turbulent kinetic energy(k)and dissipation rates model(ε),were solved using the ANSYS 2020 R2 program.The results indicated that Utilizing corrugated absorber plates resulted in a rise in the Nusselt number.,surpassing the performance of flat plate absorbers.Among the different configurations,the V-grooved 45°plate demonstrated the best results under the same conditions.Furthermore,it was observed that the efficiency values improved with increasing solar irradiance.The investigation also showed that the employing of V-grooved 45°,V-grooved 30°,and V-grooved 15°absorbers led to efficiency improvements of about 20.8%,26.3%,and 36.14%,respectively,when compared to a flat plate at a solar irradiation of 900 W/m2.展开更多
In rock mass and mining engineering,shock waves induced by engineering disturbances significantly affect rock mass stability.To explore the dynamic mechanical behavior and energy dissipation mechanisms of single-fract...In rock mass and mining engineering,shock waves induced by engineering disturbances significantly affect rock mass stability.To explore the dynamic mechanical behavior and energy dissipation mechanisms of single-fractured composite rock masses under impact loading,a series of tests were conducted using a split Hopkinson pressure bar(SHPB)system with a 50 mm rod diameter.Specimens containing a single inclined fracture with seven different dip angles and located in different lithological layers were tested.The results show that both peak stress and peak strain exhibit a non-monotonic trend with increasing dip angleα-first decreasing,then increasing,reaching a minimum atα=45°.This behavior is attributed to enhanced energy concentration and dissipation in the fracture zone,where shear-dominated failure leads to more effective crack propagation and stress redistribution.Moreover,the proportion of crushing energy dissipation is significantly affected by the fracture dip angle,reaching a minimum atα=45°and a maximum atα=90°,indicating a transition from shear to tensile failure modes with increasing angle.Lithology also plays a crucial role:grey sandstone specimens absorbed more energy compared to yellow sandstone,implying higher impact resistance due to differences in microstructural cohesion.The evolution of fragment fractal dimension with increasing dip angle follows an"M-shaped"trend,reflecting changes in fragmentation intensity and failure mode.Notably,yellow sandstone tends to produce higher fractal dimensions,with larger mass but smaller volume of powdered debris,indicating more intense fragmentation.This study reveals the coupling effect of fracture dip angle and lithology on dynamic mechanical response and energy evolution,providing new insights into the failure mechanisms of layered composite rock masses under impact loading.展开更多
Objective To investigate the changing regularity of thoracic pedicle screw channel (PSC) in different transverse screw angle(TSA).Methods CT scan images of thoracic vertebrae of a healthy adult ware digitally analyzed...Objective To investigate the changing regularity of thoracic pedicle screw channel (PSC) in different transverse screw angle(TSA).Methods CT scan images of thoracic vertebrae of a healthy adult ware digitally analyzed by Mimics 10.01展开更多
Investigated is the coupled response of a tension leg platform （TLP） for random waves. Inferred are the mass matrix, coupling stiffness matrix, damping matrix in the vibration differential equation and external load...Investigated is the coupled response of a tension leg platform （TLP） for random waves. Inferred are the mass matrix, coupling stiffness matrix, damping matrix in the vibration differential equation and external load of TLP in moving coordinating system. Infinitesimal method is applied to divide columns and pontoons into small parts. Time domain motion equation is solved by Runge-Kutta integration scheme. Jonswap spectrum is simulated in the random wave, current is simulated by linear interpolation, and NPD spectrum is applied as wind spectrum. The Monte Carlo method is used to simulate random waves and fluctuated wind. Coupling dynamic response, change of tendon tension and riser tension in different sea conditions are analyzed by power spectral density （PSD）. The influence of approach angle on dynamic response of TLP and tendon tension is compared.展开更多
We report a tunable quasi-phase-matched optical parametric generator （OPG） with different wedge angles, pumped by a commercially available Q-switched diode-pumped Nd：YVO4 laser with a repetition of 50 kHz. The nonl...We report a tunable quasi-phase-matched optical parametric generator （OPG） with different wedge angles, pumped by a commercially available Q-switched diode-pumped Nd：YVO4 laser with a repetition of 50 kHz. The nonlinear crystal is a periodically poled MgO-doped LiNbO3 （PPMgOLN） with a period of 30 μm. A congruent bulk LiNbO3 （LN） with three different wedge angles of 0°, 4°, and 9° is placed in front of PPMgOLN. Rapid tuning has been achieved by simply moving the LN crystal along its lateral direction and over 60-mW average signal output power was obtained in the whole wavelength tuning range of 1539-1570 nm.展开更多
For the joint time difference of arrival（TDOA） and angle of arrival（AOA） location scene,two methods are proposed based on the rectangular coordinates and the polar coordinates,respectively.The problem is solved pe...For the joint time difference of arrival（TDOA） and angle of arrival（AOA） location scene,two methods are proposed based on the rectangular coordinates and the polar coordinates,respectively.The problem is solved perfectly by calculating the target position with the joint TDOA and AOA location.On the condition of rectangular coordinates,first of all,it figures out the radial range between target and reference stations,then calculates the location of the target.In the case of polar coordinates,first of all,it figures out the azimuth between target and reference stations,then figures out the radial range between target and reference stations,finally obtains the location of the target.Simultaneously,simulation analyses show that the theoretical analysis is correct,and the proposed methods also provide the application of the joint TDOA and AOA location algorithm with the theoretical basis.展开更多
During the diagenetic processes of compaction and cementation,shale forms multiple beddings,significantly effecting the rock anisotropy.Therefore,it is important to study the effect of bedding on the mechanical proper...During the diagenetic processes of compaction and cementation,shale forms multiple beddings,significantly effecting the rock anisotropy.Therefore,it is important to study the effect of bedding on the mechanical properties of shale to guide fracturing engineering.To study the failure mode and fracture morphology of shale with bedding planes under different bedding dip angles,Brazilian disc splitting tests andfinite element numerical simulations are performed for shale samples and the results are compared.(1)The bedding angle has a significant effect on the failure mode and tensile strength of shale,and the tensile strength tends to increase with increasing bedding angle.(2)The failure modes of shale under different bedding dip angles can be divided into three types:tensile failure along the bedding plane;comprehensive shear and tensile failure of the matrix and the bedding plane;and matrix tensile failure.(3)The direction of secondary cracks is mostly perpendicular to the bedding plane,and a smaller angle between the load application direction and the bedding direction results in a larger number of generated cracks with more complex shapes.(4)When the loading angle of the bedding is 30,the tensile strength is low and the matrix and the bedding plane are comprehensively destroyed by shear and tension,resulting in a more complex joint mesh;conversely,when the bedding angle is greater than 60,the tensile strength increases and the complexity of the seam mesh decreases.Thesefindings can provide guidance for the selection of the bedding angle and the design of fracturing schemes in fracturing engineering.展开更多
This essay concentrates on two key procedures of image mosaic--image registration and imagefusion.Becauseof the character of geometric transformation invariance of edge points, wecalculate the angle difference of the ...This essay concentrates on two key procedures of image mosaic--image registration and imagefusion.Becauseof the character of geometric transformation invariance of edge points, wecalculate the angle difference of the direction vector ofedge points in different images anddraw an angle difference histogramto adjust the rotationproblem. Through this way, algorithm based on gray information is expandedandcan be used in images withdisplacementand rotation. Inthe term of image fusion, wavelet multi-scale analysis is used to fuse spliced images. In order to choose the best method of imagefusion,weevaluate the results of different methods of image fusion by cross entropy.展开更多
Phasor measurement units(PMUs)provide useful data for real-time monitoring of the smart grid.However,there may be time-varying deviation in phase angle differences(PADs)between both ends of the transmission line(TL),w...Phasor measurement units(PMUs)provide useful data for real-time monitoring of the smart grid.However,there may be time-varying deviation in phase angle differences(PADs)between both ends of the transmission line(TL),which may deteriorate application performance based on PMUs.To address that,this paper proposes two robust methods of correcting time-varying PAD deviation with unknown parameters of TL(ParTL).First,the phenomena of time-varying PAD deviation observed from field PMU data are presented.Two general formulations for PAD estimation are then established.To simplify the formulations,estimation of PADs is converted into the optimal problem with a single ParTL as the variable,yielding a linear estimation of PADs.The latter is used by second-order Taylor series expansion to estimate PADs accurately.To reduce the impact of possible abnormal amplitude data in field data,the IGG(Institute of Geodesy&Geophysics,Chinese Academy of Sciences)weighting function is adopted.Results using both simulated and field data verify the effectiveness and robustness of the proposed methods.展开更多
基金funded by the National Natural Science Foundation of China(Grant No.42377154).
文摘It is inevitable to encounter fault zones in tunnel construction.These faults can lead to significant deformations and potential collapses of the surrounding rock in the tunnel.Therefore,it is crucial to study the influence of different fault angles on tunnel deformation.The Tabaiyi Tunnel,located in Yunnan Province of China passes through a multi-stage fault zone.The dynamic response characteristics of the surrounding rock in the Tabaiyi Tunnel were studied under various fault dip angles and the most unfavorable angle was identified.Physical model tests were conducted using two types of anchor cables with specific parameters.Additionally,a relationship between the engineering rock mass and energy absorption by the anchor cables was established,demonstrating the advantages of negative Poisson's ratio(NPR)anchor cables.Experimental results indicate that stress concentration tends to occur at the junctions between faults and the surrounding rock mass.Tunnels supported by NPR anchor cables effectively mitigate amplification effects,achieving energy absorption increases of up to 87%compared to positive Poisson's ratio(PR)anchor cables.Furthermore,the highest acceleration amplification was observed at a fault dip angle of 45°,with peak acceleration reaching twice that of the original input wave,indicating that this angle should be avoided in tunnel design.These findings provide valuable insights for the safe management of tunnels traversing fault zones.
文摘Solar energy,a renewable resource,can be harnessed instead of fossil fuels to generate power and heat.One effective method for converting solar energy into heat is through a solar air heating(SAH)system.The theoretical investigation focused on the thermal performance of various V-groove angles on a corrugated absorber plate.The researchers maintained the exterior dimensions and constraints of the absorber plate while increasing its surface area by using a corrugated absorber surface.For the simulation,three different V-groove angles were employed:45°,30°,and 15°.The temperature and air flow rate into the system had been set at 30℃ and 0.15 m/s,respectively four various solar radiation intensities have been examined for each of the variables.The governing equations associated with the standard design,including the turbulent kinetic energy(k)and dissipation rates model(ε),were solved using the ANSYS 2020 R2 program.The results indicated that Utilizing corrugated absorber plates resulted in a rise in the Nusselt number.,surpassing the performance of flat plate absorbers.Among the different configurations,the V-grooved 45°plate demonstrated the best results under the same conditions.Furthermore,it was observed that the efficiency values improved with increasing solar irradiance.The investigation also showed that the employing of V-grooved 45°,V-grooved 30°,and V-grooved 15°absorbers led to efficiency improvements of about 20.8%,26.3%,and 36.14%,respectively,when compared to a flat plate at a solar irradiation of 900 W/m2.
基金financially supported by the National Natural Science Foundation of China(No.52204137)the Outstanding Young Scientific and Technological Talents Project of Liaoning University of Science and Technology(NO.2023YQ10)+3 种基金the Education Department Foundation of Liaoning Province(NO.LJKQZ20222317)the Natural Science Foundation of Shandong Province(Grant No.ZR2020QE121,ZR202211080074)the upport Program for Youth Innovation and Entrepreneurship in Higher Education Institutions of Shandong Province(Grant No.2022KJ101)the Support Program for Youth Innovation and Entrepreneurship in Higher Education Institutions of Shandong Province(Grant No.2022KJ101)。
文摘In rock mass and mining engineering,shock waves induced by engineering disturbances significantly affect rock mass stability.To explore the dynamic mechanical behavior and energy dissipation mechanisms of single-fractured composite rock masses under impact loading,a series of tests were conducted using a split Hopkinson pressure bar(SHPB)system with a 50 mm rod diameter.Specimens containing a single inclined fracture with seven different dip angles and located in different lithological layers were tested.The results show that both peak stress and peak strain exhibit a non-monotonic trend with increasing dip angleα-first decreasing,then increasing,reaching a minimum atα=45°.This behavior is attributed to enhanced energy concentration and dissipation in the fracture zone,where shear-dominated failure leads to more effective crack propagation and stress redistribution.Moreover,the proportion of crushing energy dissipation is significantly affected by the fracture dip angle,reaching a minimum atα=45°and a maximum atα=90°,indicating a transition from shear to tensile failure modes with increasing angle.Lithology also plays a crucial role:grey sandstone specimens absorbed more energy compared to yellow sandstone,implying higher impact resistance due to differences in microstructural cohesion.The evolution of fragment fractal dimension with increasing dip angle follows an"M-shaped"trend,reflecting changes in fragmentation intensity and failure mode.Notably,yellow sandstone tends to produce higher fractal dimensions,with larger mass but smaller volume of powdered debris,indicating more intense fragmentation.This study reveals the coupling effect of fracture dip angle and lithology on dynamic mechanical response and energy evolution,providing new insights into the failure mechanisms of layered composite rock masses under impact loading.
文摘Objective To investigate the changing regularity of thoracic pedicle screw channel (PSC) in different transverse screw angle(TSA).Methods CT scan images of thoracic vertebrae of a healthy adult ware digitally analyzed by Mimics 10.01
文摘Investigated is the coupled response of a tension leg platform （TLP） for random waves. Inferred are the mass matrix, coupling stiffness matrix, damping matrix in the vibration differential equation and external load of TLP in moving coordinating system. Infinitesimal method is applied to divide columns and pontoons into small parts. Time domain motion equation is solved by Runge-Kutta integration scheme. Jonswap spectrum is simulated in the random wave, current is simulated by linear interpolation, and NPD spectrum is applied as wind spectrum. The Monte Carlo method is used to simulate random waves and fluctuated wind. Coupling dynamic response, change of tendon tension and riser tension in different sea conditions are analyzed by power spectral density （PSD）. The influence of approach angle on dynamic response of TLP and tendon tension is compared.
基金This work was supported in part by the National Natural Science Foundation of China (No. 60278001 and 10474071)the Ministry of Education of China, the National Research Foundation for the Doctoral Program of Ministry of Education of China, and Tianjin Municipal Technological Development Plan.
文摘We report a tunable quasi-phase-matched optical parametric generator （OPG） with different wedge angles, pumped by a commercially available Q-switched diode-pumped Nd：YVO4 laser with a repetition of 50 kHz. The nonlinear crystal is a periodically poled MgO-doped LiNbO3 （PPMgOLN） with a period of 30 μm. A congruent bulk LiNbO3 （LN） with three different wedge angles of 0°, 4°, and 9° is placed in front of PPMgOLN. Rapid tuning has been achieved by simply moving the LN crystal along its lateral direction and over 60-mW average signal output power was obtained in the whole wavelength tuning range of 1539-1570 nm.
基金supported by the National Natural Science Foundation of China(6107210761271300)+4 种基金the Shaanxi Industry Surmount Foundation(2012K06-12)the Arm and Equipment Pre-research Foundationthe Fundamental Research Funds for the Central Universities of China(K0551302006K5051202045K50511020024)
文摘For the joint time difference of arrival（TDOA） and angle of arrival（AOA） location scene,two methods are proposed based on the rectangular coordinates and the polar coordinates,respectively.The problem is solved perfectly by calculating the target position with the joint TDOA and AOA location.On the condition of rectangular coordinates,first of all,it figures out the radial range between target and reference stations,then calculates the location of the target.In the case of polar coordinates,first of all,it figures out the azimuth between target and reference stations,then figures out the radial range between target and reference stations,finally obtains the location of the target.Simultaneously,simulation analyses show that the theoretical analysis is correct,and the proposed methods also provide the application of the joint TDOA and AOA location algorithm with the theoretical basis.
基金supported by the NationalKeyR&D Program of China(No.2020YFA 0711800)the National Natural Science Foundation of China(No.41972171)+1 种基金Fundamental Research Funds for the Central Universities(No.2020CXNL11)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘During the diagenetic processes of compaction and cementation,shale forms multiple beddings,significantly effecting the rock anisotropy.Therefore,it is important to study the effect of bedding on the mechanical properties of shale to guide fracturing engineering.To study the failure mode and fracture morphology of shale with bedding planes under different bedding dip angles,Brazilian disc splitting tests andfinite element numerical simulations are performed for shale samples and the results are compared.(1)The bedding angle has a significant effect on the failure mode and tensile strength of shale,and the tensile strength tends to increase with increasing bedding angle.(2)The failure modes of shale under different bedding dip angles can be divided into three types:tensile failure along the bedding plane;comprehensive shear and tensile failure of the matrix and the bedding plane;and matrix tensile failure.(3)The direction of secondary cracks is mostly perpendicular to the bedding plane,and a smaller angle between the load application direction and the bedding direction results in a larger number of generated cracks with more complex shapes.(4)When the loading angle of the bedding is 30,the tensile strength is low and the matrix and the bedding plane are comprehensively destroyed by shear and tension,resulting in a more complex joint mesh;conversely,when the bedding angle is greater than 60,the tensile strength increases and the complexity of the seam mesh decreases.Thesefindings can provide guidance for the selection of the bedding angle and the design of fracturing schemes in fracturing engineering.
基金Supported by National Natural Science Foundation of China(No.11001017)
文摘This essay concentrates on two key procedures of image mosaic--image registration and imagefusion.Becauseof the character of geometric transformation invariance of edge points, wecalculate the angle difference of the direction vector ofedge points in different images anddraw an angle difference histogramto adjust the rotationproblem. Through this way, algorithm based on gray information is expandedandcan be used in images withdisplacementand rotation. Inthe term of image fusion, wavelet multi-scale analysis is used to fuse spliced images. In order to choose the best method of imagefusion,weevaluate the results of different methods of image fusion by cross entropy.
基金This work was supported by the National Key Research and Development Program of China(2017YFB0902901)National Natural Science Foundation of China(51627811).
文摘Phasor measurement units(PMUs)provide useful data for real-time monitoring of the smart grid.However,there may be time-varying deviation in phase angle differences(PADs)between both ends of the transmission line(TL),which may deteriorate application performance based on PMUs.To address that,this paper proposes two robust methods of correcting time-varying PAD deviation with unknown parameters of TL(ParTL).First,the phenomena of time-varying PAD deviation observed from field PMU data are presented.Two general formulations for PAD estimation are then established.To simplify the formulations,estimation of PADs is converted into the optimal problem with a single ParTL as the variable,yielding a linear estimation of PADs.The latter is used by second-order Taylor series expansion to estimate PADs accurately.To reduce the impact of possible abnormal amplitude data in field data,the IGG(Institute of Geodesy&Geophysics,Chinese Academy of Sciences)weighting function is adopted.Results using both simulated and field data verify the effectiveness and robustness of the proposed methods.
