Tilting pair is a key concept in the tilting theory.Let F be an additive subfunctor of the functor Ext_(A)^(1)(-,-).In this paper,we introduce the note of n-F-tilting pair,which is a natural generalization of n-tiltin...Tilting pair is a key concept in the tilting theory.Let F be an additive subfunctor of the functor Ext_(A)^(1)(-,-).In this paper,we introduce the note of n-F-tilting pair,which is a natural generalization of n-tilting pair in the sense of Miyahita.Some propositions and a simplified characterization on n-F-tilting pairs are given.展开更多
Aiming at the requirement for high-precision tilt monitoring in the field of structural health monitoring(SHM),this paper proposes a sensitivity-enhanced tilt sensor based on a femtosecond fiber Bragg grating(FBG).Fir...Aiming at the requirement for high-precision tilt monitoring in the field of structural health monitoring(SHM),this paper proposes a sensitivity-enhanced tilt sensor based on a femtosecond fiber Bragg grating(FBG).Firstly,structural design of the tilt sensor was conducted based on static mechanics principles.By positioning the FBG away from the beam’s neutral axis,linear strain enhancement in the FBG was achieved,thereby improving sensor sensitivity.The relationship between FBG strain,applied force,and the offset distance from the neutral axis was established,determining the optimal distance corresponding to maximum strain.Based on this optimization scheme,a prototype of the tilt sensor was designed,fabricated,and experimentally tested.Experimental results show that the FBG offset distance yielding maximum sensitivity is 4.4 mm.Within a tilt angle range of−30°to 30°,the sensor achieved a sensitivity of 129.95 pm/°and a linearity of 0.9997.Compared to conventional FBG-based tilt sensors,both sensitivity and linearity were significantly improved.Furthermore,the sensor demonstrated excellent repeatability(error<0.94%),creep resistance(error<0.30%),and temperature stability(error<0.90%).These results demonstrate the sensor’s excellent potential for SHM applications.The sensor has been successfully deployed in an underground pipeline project,conducting long-term monitoring of tilt and deformation in the steel support structures,further proving its value for engineering safety monitoring.展开更多
Topochemical fluorination introduces significant structural distortions and emerging properties in perovskite oxides via substituting oxygen with fluorine.However,the rapid fluorination process and the similarity betw...Topochemical fluorination introduces significant structural distortions and emerging properties in perovskite oxides via substituting oxygen with fluorine.However,the rapid fluorination process and the similarity between F and O render the O/F site occupation and local lattice evolution during fluorination unclear.Here we investigated the atomic-scale O/F exchange in La2CoO4and quantified the lattice distortion of three ordered structures:La_(2)CoO_(3.5)F,La_(2)CoO_(3)F_(2),and La_(2)CoO_(2.5)F_(3)by utilizing aberration-corrected electron microscopy.Atomic-resolved elemental mapping provides direct evidence for the O/F occupancy in interstitial and apical sites.We revealed that apical F ions induce significant octahedral tilting from 178°to 165°,linearly proportional to the occupancy rate;and cause the obvious change in the fine structure O K edge,meanwhile apical O is exchanged into interstitial sites.The strong octahedral tilt leads to the in-plane elongation of the[CoO_(4)F_(2)]octahedra.These findings elucidate the atomic-scale mechanisms of the entire fluorination process and highlight the significant role of F in tuning the octahedral tilt of functional oxides.展开更多
Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is p...Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is proposed.The electric field applied between the template and the substrate drives the contact,tilting,filling,and holding processes.By accurately controlling the introduced included angle between the flexible template and the substrate,tilted nanostructures with a controllable angle are imprinted onto the substrate,although they are vertical on the template.By flexibly adjusting the electric field intensity and the included angle,large-area uniform-tilted,gradient-tilted,and high-angle-tilted nanostructures are fabricated.In contrast to traditional replication,the morphology of the nanoimprinting structure is extended to customized control.This work provides a cost-effective,efficient,and versatile technology for the fabrication of various large-area tilted metasurface structures.As an illustration,a tilted nanograting with a high coupling efficiency is fabricated and integrated into augmented reality displays,demonstrating superior imaging quality.展开更多
Aiming at the paddle tilt angle of the spray-blowing agitation composite process,the four-blade stirring and blowing composite desulfurization agitator was chosen as the research object,and the computational fluid dyn...Aiming at the paddle tilt angle of the spray-blowing agitation composite process,the four-blade stirring and blowing composite desulfurization agitator was chosen as the research object,and the computational fluid dynamics numerical simulation was used to investigate the changes in flow field velocity,turbulent kinetic energy magnitude,and distribution caused by the blade tilt angle.Furthermore,the impact of blade tilt angle on the flow fragmentation behavior of individual bubbles and the coalescence process of multiple bubbles at different positions was studied.Under the same stirring and blowing process parameters,with the increase in the blade tilt angle of the agitator,the velocity of the flow field and the average turbulent kinetic energy inside the agitator decreased,and the bubble fragmentation speed decreased while the merging speed accelerated.The turbulent kinetic energy at the agitator bottom was greater when the blade tilt angle was 3.2°compared to when it was 13.2°,while the turbulent kinetic energy at the agitator upper part was relatively smaller.The results for single bubbles represented the state and trajectory of the bubble fragmentation process,and the results for multiple bubbles illustrated the state and trajectory of the bubble aggregation process.展开更多
Pressure and tilt data are jointly inverted to simultaneously map the orientation and dimensions of a hydraulic fracture.The deformation induced by a fracture under internal pressure is modeled using the distributed d...Pressure and tilt data are jointly inverted to simultaneously map the orientation and dimensions of a hydraulic fracture.The deformation induced by a fracture under internal pressure is modeled using the distributed dislocation technique.The planar fracture is represented by four quarter ellipses,joined at the center and sharing semi-axes.This configuration provides a straightforward model for characterizing asymmetric fracture geometry.The inverse problem of mapping the fracture geometry is formulated using the Bayesian probabilistic method,combining the a priori information on the fracture model with updated information from pressure and tilt data.Solving the nonlinear inverse problem is achieved by pseudo-randomly sampling the posterior probability distribution through the Markov chain Monte Carlo method.The resulting posterior probability distribution is then explored to assess uncertainty,resolution,and correlation between model parameters.Numerical experiments are conducted to verify the accuracy and validity of the proposed analysis method in mapping the fracture geometry using synthetic pressure and tilt data.展开更多
The transmission line tower will be affected by bad weather and artificial subsidence caused by the foundation and other factors in the power transmission.The tower’s tilt and severe deformation will cause the buildi...The transmission line tower will be affected by bad weather and artificial subsidence caused by the foundation and other factors in the power transmission.The tower’s tilt and severe deformation will cause the building to collapse.Many small changes caused the tower’s collapse,but the early staff often could not intuitively notice the changes in the tower’s state.In the current tower online monitoring system,terminal equipment often needs to replace batteries frequently due to premature exhaustion of power.According to the need for real-time measurement of power line tower,this research designed a real-time monitoring device monitoring the transmission tower attitude tilting and foundation state based on the inertial sensor,the acceleration of 3 axis inertial sensor and angular velocity raw data to pole average filtering pre-processing,and then through the complementary filtering algorithm for comprehensive calculation of tilt angle,the system meets the demand for inclined online monitoring of power line poles and towers regarding measurement accuracy,with low cost and power consumption.The optimization multi-sensor cooperative detection and correction measured tilt angle result relative accuracy can reach 1.03%,which has specific promotion and application value since the system has the advantages of unattended and efficient calculation.展开更多
For the quad tilt rotor aircraft, a computational fluid dynamics method based on multiple reference frames (MRF) was used to analyze the influence of aerodynamic layout parameters on the aerodynamic characteristics of...For the quad tilt rotor aircraft, a computational fluid dynamics method based on multiple reference frames (MRF) was used to analyze the influence of aerodynamic layout parameters on the aerodynamic characteristics of the quad tilt rotor aircraft. Firstly, a numerical simulation method for the interference flow field of the quad tilt rotor aircraft is established. Based on this method, the aerodynamic characteristics of isolated rotors, rotor combinations at different lateral positions on the wing, and rotor rotation directions under different inflow velocities were calculated and analyzed, in order to grasp their aerodynamic interference laws and provide reference for the design and control theory research of such aircraft.展开更多
Seismic prediction of cracks is of great significance in many disciplines,for which the rock physics model is indispensable.However,up to now,multitudinous analytical models focus primarily on the cracked rock with th...Seismic prediction of cracks is of great significance in many disciplines,for which the rock physics model is indispensable.However,up to now,multitudinous analytical models focus primarily on the cracked rock with the isotropic background,while the explicit model for the cracked rock with the anisotropic background is rarely investigated in spite of such case being often encountered in the earth.Hence,we first studied dependences of the crack opening displacement tensors on the crack dip angle in the coordinate systems formed by symmetry planes of the crack and the background anisotropy,respectively,by forty groups of numerical experiments.Based on the conclusion from the experiments,the analytical solution was derived for the effective elastic properties of the rock with the inclined penny-shaped cracks in the transversely isotropic background.Further,we comprehensively analyzed,according to the developed model,effects of the crack dip angle,background anisotropy,filling fluid and crack density on the effective elastic properties of the cracked rock.The analysis results indicate that the dip angle and background anisotropy can significantly either enhance or weaken the anisotropy degrees of the P-and SH-wave velocities,whereas they have relatively small effects on the SV-wave velocity anisotropy.Moreover,the filling fluid can increase the stiffness coefficients related to the compressional modulus by reducing crack compliance parameters,while its effects on shear coefficients depend on the crack dip angle.The increasing crack density reduces velocities of the dry rock,and decreasing rates of the velocities are affected by the crack dip angle.By comparing with exact numerical results and experimental data,it was demonstrated that the proposed model can achieve high-precision estimations of stiffness coefficients.Moreover,the assumption of the weakly anisotropic background results in the consistency between the proposed model and Hudson's published theory for the orthorhombic rock.展开更多
The tilt of a Raman laser beam is a major systematic error in precision gravity measurement using atom interferometry.The conventional approach to evaluating this tilt error involves modulating the direction of the Ra...The tilt of a Raman laser beam is a major systematic error in precision gravity measurement using atom interferometry.The conventional approach to evaluating this tilt error involves modulating the direction of the Raman laser beam and conducting time-consuming gravity measurements to identify the error minimum.In this work,we demonstrate a method to expediently determine the tilt of the Raman laser beam by transforming the tilt angle measurement into characterization of parallelism,which integrates the optical method of aligning the laser direction,commonly used in freely falling corner-cube gravimeters,into an atom gravimeter.A position-sensing detector(PSD)is utilized to quantitatively characterize the parallelism between the test beam and the reference beam,thus measuring the tilt precisely and rapidly.After carefully positioning the PSD and calibrating the relationship between the distance measured by the PSD and the tilt angle measured by the tiltmeter,we achieved a statistical uncertainty of less than 30μrad in the tilt measurement.Furthermore,we compared the results obtained through this optical method with those from the conventional tilt modulation method for gravity measurement.The comparison validates that our optical method can achieve tilt determination with an accuracy level of better than 200μrad,corresponding to a systematic error of 20μGal in g measurement.This work has practical implications for real-world applications of atom gravimeters.展开更多
The conventional approach to optimizing tilt angles for fixed solar panels aims to maximize energy generation over the entire year. However, in the context of a supply controlled electric grid, where solar energy avai...The conventional approach to optimizing tilt angles for fixed solar panels aims to maximize energy generation over the entire year. However, in the context of a supply controlled electric grid, where solar energy availability varies, this criterion may not be optimal. This study explores two alternative optimization criteria focused on maximizing baseload supply potential and minimizing required storage capacity to address seasonality in energy generation. The optimal tilt angles determined for these criteria differed significantly from the standard approach. This research highlights additional factors crucial for designing solar power systems beyond gross energy generation, essential for the global transition towards a fully renewable energy-based electric grid in the future.展开更多
基金Supported by the National Natural Science Foundation of China(Grant No.12101003)the Natural Science Foundation of Anhui Province(Grant No.2108085QA07).
文摘Tilting pair is a key concept in the tilting theory.Let F be an additive subfunctor of the functor Ext_(A)^(1)(-,-).In this paper,we introduce the note of n-F-tilting pair,which is a natural generalization of n-tilting pair in the sense of Miyahita.Some propositions and a simplified characterization on n-F-tilting pairs are given.
文摘Aiming at the requirement for high-precision tilt monitoring in the field of structural health monitoring(SHM),this paper proposes a sensitivity-enhanced tilt sensor based on a femtosecond fiber Bragg grating(FBG).Firstly,structural design of the tilt sensor was conducted based on static mechanics principles.By positioning the FBG away from the beam’s neutral axis,linear strain enhancement in the FBG was achieved,thereby improving sensor sensitivity.The relationship between FBG strain,applied force,and the offset distance from the neutral axis was established,determining the optimal distance corresponding to maximum strain.Based on this optimization scheme,a prototype of the tilt sensor was designed,fabricated,and experimentally tested.Experimental results show that the FBG offset distance yielding maximum sensitivity is 4.4 mm.Within a tilt angle range of−30°to 30°,the sensor achieved a sensitivity of 129.95 pm/°and a linearity of 0.9997.Compared to conventional FBG-based tilt sensors,both sensitivity and linearity were significantly improved.Furthermore,the sensor demonstrated excellent repeatability(error<0.94%),creep resistance(error<0.30%),and temperature stability(error<0.90%).These results demonstrate the sensor’s excellent potential for SHM applications.The sensor has been successfully deployed in an underground pipeline project,conducting long-term monitoring of tilt and deformation in the steel support structures,further proving its value for engineering safety monitoring.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52322212,52025025,5225040212474001)the National Key R&D Program of China(Grant Nos.2022YFA1403203 and 2023YFA1406300)。
文摘Topochemical fluorination introduces significant structural distortions and emerging properties in perovskite oxides via substituting oxygen with fluorine.However,the rapid fluorination process and the similarity between F and O render the O/F site occupation and local lattice evolution during fluorination unclear.Here we investigated the atomic-scale O/F exchange in La2CoO4and quantified the lattice distortion of three ordered structures:La_(2)CoO_(3.5)F,La_(2)CoO_(3)F_(2),and La_(2)CoO_(2.5)F_(3)by utilizing aberration-corrected electron microscopy.Atomic-resolved elemental mapping provides direct evidence for the O/F occupancy in interstitial and apical sites.We revealed that apical F ions induce significant octahedral tilting from 178°to 165°,linearly proportional to the occupancy rate;and cause the obvious change in the fine structure O K edge,meanwhile apical O is exchanged into interstitial sites.The strong octahedral tilt leads to the in-plane elongation of the[CoO_(4)F_(2)]octahedra.These findings elucidate the atomic-scale mechanisms of the entire fluorination process and highlight the significant role of F in tuning the octahedral tilt of functional oxides.
基金supported by National Natural Science Foundation of China(No.52025055 and 52275571)Basic Research Operation Fund of China(No.xzy012024024).
文摘Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is proposed.The electric field applied between the template and the substrate drives the contact,tilting,filling,and holding processes.By accurately controlling the introduced included angle between the flexible template and the substrate,tilted nanostructures with a controllable angle are imprinted onto the substrate,although they are vertical on the template.By flexibly adjusting the electric field intensity and the included angle,large-area uniform-tilted,gradient-tilted,and high-angle-tilted nanostructures are fabricated.In contrast to traditional replication,the morphology of the nanoimprinting structure is extended to customized control.This work provides a cost-effective,efficient,and versatile technology for the fabrication of various large-area tilted metasurface structures.As an illustration,a tilted nanograting with a high coupling efficiency is fabricated and integrated into augmented reality displays,demonstrating superior imaging quality.
基金supported by the National Natural Science Foundation of China(No.51904069)the Fundamental Research Funds for the Central Universities(No.N2223026)+1 种基金the Development Fund of State Key Laboratory for Clean Utilization of Complex Nonferrous Metal Resources(No.CNMRCUKF2302)the Scientific Research Fund Project of Northeastern University at Qinhuangdao(No.XNY201808).
文摘Aiming at the paddle tilt angle of the spray-blowing agitation composite process,the four-blade stirring and blowing composite desulfurization agitator was chosen as the research object,and the computational fluid dynamics numerical simulation was used to investigate the changes in flow field velocity,turbulent kinetic energy magnitude,and distribution caused by the blade tilt angle.Furthermore,the impact of blade tilt angle on the flow fragmentation behavior of individual bubbles and the coalescence process of multiple bubbles at different positions was studied.Under the same stirring and blowing process parameters,with the increase in the blade tilt angle of the agitator,the velocity of the flow field and the average turbulent kinetic energy inside the agitator decreased,and the bubble fragmentation speed decreased while the merging speed accelerated.The turbulent kinetic energy at the agitator bottom was greater when the blade tilt angle was 3.2°compared to when it was 13.2°,while the turbulent kinetic energy at the agitator upper part was relatively smaller.The results for single bubbles represented the state and trajectory of the bubble fragmentation process,and the results for multiple bubbles illustrated the state and trajectory of the bubble aggregation process.
基金supported by the National Natural Science Foundation of China under Grant Nos.52374033 and U23A20596.
文摘Pressure and tilt data are jointly inverted to simultaneously map the orientation and dimensions of a hydraulic fracture.The deformation induced by a fracture under internal pressure is modeled using the distributed dislocation technique.The planar fracture is represented by four quarter ellipses,joined at the center and sharing semi-axes.This configuration provides a straightforward model for characterizing asymmetric fracture geometry.The inverse problem of mapping the fracture geometry is formulated using the Bayesian probabilistic method,combining the a priori information on the fracture model with updated information from pressure and tilt data.Solving the nonlinear inverse problem is achieved by pseudo-randomly sampling the posterior probability distribution through the Markov chain Monte Carlo method.The resulting posterior probability distribution is then explored to assess uncertainty,resolution,and correlation between model parameters.Numerical experiments are conducted to verify the accuracy and validity of the proposed analysis method in mapping the fracture geometry using synthetic pressure and tilt data.
基金This work was supported by the National Natural Science Foundation of China(Nos.62172242,51901152)Industry University Cooperation Education Program of the Ministry of Education(No.2020021680113)Shanxi Scholarship Council of China.
文摘The transmission line tower will be affected by bad weather and artificial subsidence caused by the foundation and other factors in the power transmission.The tower’s tilt and severe deformation will cause the building to collapse.Many small changes caused the tower’s collapse,but the early staff often could not intuitively notice the changes in the tower’s state.In the current tower online monitoring system,terminal equipment often needs to replace batteries frequently due to premature exhaustion of power.According to the need for real-time measurement of power line tower,this research designed a real-time monitoring device monitoring the transmission tower attitude tilting and foundation state based on the inertial sensor,the acceleration of 3 axis inertial sensor and angular velocity raw data to pole average filtering pre-processing,and then through the complementary filtering algorithm for comprehensive calculation of tilt angle,the system meets the demand for inclined online monitoring of power line poles and towers regarding measurement accuracy,with low cost and power consumption.The optimization multi-sensor cooperative detection and correction measured tilt angle result relative accuracy can reach 1.03%,which has specific promotion and application value since the system has the advantages of unattended and efficient calculation.
文摘For the quad tilt rotor aircraft, a computational fluid dynamics method based on multiple reference frames (MRF) was used to analyze the influence of aerodynamic layout parameters on the aerodynamic characteristics of the quad tilt rotor aircraft. Firstly, a numerical simulation method for the interference flow field of the quad tilt rotor aircraft is established. Based on this method, the aerodynamic characteristics of isolated rotors, rotor combinations at different lateral positions on the wing, and rotor rotation directions under different inflow velocities were calculated and analyzed, in order to grasp their aerodynamic interference laws and provide reference for the design and control theory research of such aircraft.
基金We would like to acknowledge all the reviewers and editors and the sponsorship of National Natural Science Foundation of China(42030103)the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(2021QNLM020001-6)the Laoshan National Laboratory of Science and Technology Foundation(LSKJ202203400).
文摘Seismic prediction of cracks is of great significance in many disciplines,for which the rock physics model is indispensable.However,up to now,multitudinous analytical models focus primarily on the cracked rock with the isotropic background,while the explicit model for the cracked rock with the anisotropic background is rarely investigated in spite of such case being often encountered in the earth.Hence,we first studied dependences of the crack opening displacement tensors on the crack dip angle in the coordinate systems formed by symmetry planes of the crack and the background anisotropy,respectively,by forty groups of numerical experiments.Based on the conclusion from the experiments,the analytical solution was derived for the effective elastic properties of the rock with the inclined penny-shaped cracks in the transversely isotropic background.Further,we comprehensively analyzed,according to the developed model,effects of the crack dip angle,background anisotropy,filling fluid and crack density on the effective elastic properties of the cracked rock.The analysis results indicate that the dip angle and background anisotropy can significantly either enhance or weaken the anisotropy degrees of the P-and SH-wave velocities,whereas they have relatively small effects on the SV-wave velocity anisotropy.Moreover,the filling fluid can increase the stiffness coefficients related to the compressional modulus by reducing crack compliance parameters,while its effects on shear coefficients depend on the crack dip angle.The increasing crack density reduces velocities of the dry rock,and decreasing rates of the velocities are affected by the crack dip angle.By comparing with exact numerical results and experimental data,it was demonstrated that the proposed model can achieve high-precision estimations of stiffness coefficients.Moreover,the assumption of the weakly anisotropic background results in the consistency between the proposed model and Hudson's published theory for the orthorhombic rock.
基金Project was supported by the National Key Research and Development Program of China(Grant No.2021YFB3900204)。
文摘The tilt of a Raman laser beam is a major systematic error in precision gravity measurement using atom interferometry.The conventional approach to evaluating this tilt error involves modulating the direction of the Raman laser beam and conducting time-consuming gravity measurements to identify the error minimum.In this work,we demonstrate a method to expediently determine the tilt of the Raman laser beam by transforming the tilt angle measurement into characterization of parallelism,which integrates the optical method of aligning the laser direction,commonly used in freely falling corner-cube gravimeters,into an atom gravimeter.A position-sensing detector(PSD)is utilized to quantitatively characterize the parallelism between the test beam and the reference beam,thus measuring the tilt precisely and rapidly.After carefully positioning the PSD and calibrating the relationship between the distance measured by the PSD and the tilt angle measured by the tiltmeter,we achieved a statistical uncertainty of less than 30μrad in the tilt measurement.Furthermore,we compared the results obtained through this optical method with those from the conventional tilt modulation method for gravity measurement.The comparison validates that our optical method can achieve tilt determination with an accuracy level of better than 200μrad,corresponding to a systematic error of 20μGal in g measurement.This work has practical implications for real-world applications of atom gravimeters.
文摘The conventional approach to optimizing tilt angles for fixed solar panels aims to maximize energy generation over the entire year. However, in the context of a supply controlled electric grid, where solar energy availability varies, this criterion may not be optimal. This study explores two alternative optimization criteria focused on maximizing baseload supply potential and minimizing required storage capacity to address seasonality in energy generation. The optimal tilt angles determined for these criteria differed significantly from the standard approach. This research highlights additional factors crucial for designing solar power systems beyond gross energy generation, essential for the global transition towards a fully renewable energy-based electric grid in the future.
