Real-time identification of rock strength and cuttability based on monitoring while cutting during excavation is essential for key procedures such as the precise adjustment of excavation parameters and the in-situ mod...Real-time identification of rock strength and cuttability based on monitoring while cutting during excavation is essential for key procedures such as the precise adjustment of excavation parameters and the in-situ modification of hard rocks.This study proposes an in-telligent approach for predicting rock strength and cuttability.A database comprising 132 data sets is established,containing cutting para-meters(such as cutting depth and pick angle),cutting responses(such as specific energy and instantaneous cutting rate),and rock mech-anical parameters collected from conical pick-cutting experiments.These parameters serve as input features for predicting the uniaxial compressive strength and tensile strength of rocks using regression fitting and machine learning methodologies.In addition,rock cuttabil-ity is classified using a combination of the analytic hierarchy process and fuzzy comprehensive evaluation method,and subsequently iden-tified through machine learning approaches.Various models are compared to determine the optimal predictive and classification models.The results indicate that the optimal model for uniaxial compressive strength and tensile strength prediction is the genetic algorithm-optimized backpropagation neural network model,and the optimal model for rock cuttability classification is the radial basis neural network model.展开更多
Water-weakening presents a promising strategy for the in-situ improvement of rock cuttability.This study unveils the influences of water saturation on the mechanical response and fragmentation characteristics of rock ...Water-weakening presents a promising strategy for the in-situ improvement of rock cuttability.This study unveils the influences of water saturation on the mechanical response and fragmentation characteristics of rock samples.A series of rock-cutting tests using conical pick indentation was conducted on three types of sandstone samples under both dry and water-saturated conditions.The relationships between cutting force and indentation depth,as well as typical cuttability indices are determined and compared for dry and water-saturated samples.The experimental results reveal that the presence of water facilitates shearing failure in rock samples,as well as alleviates the fluctuations in the cutting force-indentation depth curve Furthermore,the peak cutting force(F_(p)),cutting work(W_(p)),and specific energy(SE)undergo apparent decrease after water saturation,whereas the trend in the indentation depth at rock failure(D_(f))varies across different rock types.Additionally,the water-induced percentage reductions in F_(p)and SE correlate positively with the quartz and swelling clay content within the rocks,suggesting that the cuttability improvement due to water saturation is attributed to the combined effects of stress corrosion and frictional reduction.These findings carry significant implications for improving rock cuttability in mechanized excavation of hard rock formations.展开更多
The oil and gas stored in deep and ultra-deep carbonate reservoirs is the focus of future exploration and development.Conical PDC(Polycrystalline Diamond Compact)cutter,which is a new kind of PDC cutter,can significan...The oil and gas stored in deep and ultra-deep carbonate reservoirs is the focus of future exploration and development.Conical PDC(Polycrystalline Diamond Compact)cutter,which is a new kind of PDC cutter,can significantly improve the rate of penetration(ROP)and extend PDC bit life in hard and abrasive formations.However,the breakage characteristics and failure mode of the conical PDC cutter cutting carbonate rock is still masked.In this paper,a series of single-cutter cutting tests were carried out with the conical and conventional PDC cutters.The cutting force,rock-breaking process,surface morphology of cutting grooves and cuttings characteristic were analyzed.Based on the derived formula of the brittle fracture index,the failure model of carbonate rock was quantitatively analyzed under the action of conical and conventional cutter.The results show that the average cutting force of the conical cutter is less than that of the conventional cutter,which means greater stability of the cutting process using the conical cutter.Carbonate rock with calcite as the main component tends to generate blocky rock debris by conical cutter.The height of the cuttings generated by the conical cutter is 0.5 mm higher than that generated by the conventional cutter.The conical cutter exhibits enhanced penetration capabilities within carbonate rock.The accumulation of rock debris in front of the conventional cutter is obvious.Whereas,the conical cutter facilitates the cuttings transport,thereby alleviating drilling stickiness slip.At different cutting depths,the conical cutter consistently causes asymmetric jagged brittle tensile fracture zones on both sides of the cutting groove.Calculations based on the brittle fracture index demonstrate that the brittle fracture index of the conical cutter generally doubles that of the conventional cutter.For carbonate rock,the conical cutter displays superior utilization of brittle fracture abilities.The research findings of this work offer insights into the breakage process and failure mode of carbonate rock by the conical cutter.展开更多
Because of their remarkable properties,room-temperature ionic liquids(RTILs)are used widely in electrochemistry,fuel cells,supercapacitors,and even DNA sequencing,and many of these applications involve the transport o...Because of their remarkable properties,room-temperature ionic liquids(RTILs)are used widely in electrochemistry,fuel cells,supercapacitors,and even DNA sequencing,and many of these applications involve the transport of RTILs in nanoscale media.Particularly for single-molecule detection,the RTIL must be mixed with a solvent(e.g.,water)so that the electrolyte has both high viscosity and conductivity to obtain excellent signals.If a RTIL contains a quantity of water in bulk,this has a significant effect on its properties(e.g.,the electrochemical window),thereby limiting some applications.However,the physicochemical properties of RTILs containing water in nanoconfined spaces remain unclear,especially their ionic transport behavior.Therefore,reported here is a study of the ionic transport behavior of mixed RTIL/water solutions at the nanoscale using a single conical nanochannel as a nanofluidic platform.The conductivity of the mixtures in the nanoconfined space was closely related to the nanochannel size,and highly diluted mixed solutions resulted in a nonlinear rectificationreversed current,which was possibly due to the adsorption of cations on the nanochannel wall.The maximum rectification ratio was 114,showing excellent rectification that could be used to realize newly conceptualized nanofluidic diodes.In summary,this work provides an exhaustive understanding of the nonlinear ion transport of RTIL/water mixtures and a theoretical foundation for applying RTILs in energy storage and conversion and bio-sensing.展开更多
This paper investigates the active traveling wave vibration control of an elastic supported rotating porous aluminium conical shell(CS)under impact loading.Piezoelectric smart materials in the form of micro fiber comp...This paper investigates the active traveling wave vibration control of an elastic supported rotating porous aluminium conical shell(CS)under impact loading.Piezoelectric smart materials in the form of micro fiber composites(MFCs)are used as actuators and sensors.To this end,a metal pore truncated CS with MFCs attached to its surface is considered.Adding artificial virtual springs at two edges of the truncated CS achieves various elastic supported boundaries by changing the spring stiffness.Based on the first-order shear deformation theory(FSDT),minimum energy principle,and artificial virtual spring technology,the theoretical formulations considering the electromechanical coupling are derived.The comparison of the natural frequency of the present results with the natural frequencies reported in previous literature evaluates the accuracy of the present approach.To study the vibration control,the integral quadrature method in conjunction with the differential quadrature approximation in the length direction is used to discretize the partial differential dynamical system to form a set of ordinary differential equations.With the aid of the velocity negative feedback method,both the time history and the input control voltage on the actuator are demonstrated to present the effects of velocity feedback gain,pore distribution type,semi-vertex angle,impact loading,and rotational angular velocity on the traveling wave vibration control.展开更多
Based on the finite-discrete element method,a three-dimensional numerical model for axial impact rock breaking was established and validated.A computational method for energy conversion during impact rock breaking was...Based on the finite-discrete element method,a three-dimensional numerical model for axial impact rock breaking was established and validated.A computational method for energy conversion during impact rock breaking was proposed,and the effects of conical tooth forward rake angle,rock temperature,and impact velocity on rock breaking characteristics and energy transfer laws were analyzed.The results show that during single impact rock breaking with conical tooth bits,merely 7.52%to 12.51%of the energy is utilized for rock breaking,while a significant 57.26%to 78.10%is dissipated as frictional loss.An insufficient forward rake angle increases tooth penetration depth and frictional loss,whereas an excessive forward rake angle reduces penetration capability,causing bit rebound and greater energy absorption by the drill rod.Thus,an optimal forward rake angle exists.Regarding environmental factors,high temperatures significantly enhance impact-induced rock breaking.Thermal damage from high temperatures reduces rock strength and inhibits its energy absorption.Finally,higher impact velocities intensify rock damage,yet excessively high velocities increase frictional loss and reduce the proportion of energy absorbed by the rock,thereby failing to substantially improve rock breaking efficiency.An optimal impact velocity exists.展开更多
Light-induced conical intersections(LICIs)present a distinctive mechanism for nonadiabatic coupling,thereby facilitating ultrafast chemical reactions,including the indirect photodissociation of diatomic molecules.In c...Light-induced conical intersections(LICIs)present a distinctive mechanism for nonadiabatic coupling,thereby facilitating ultrafast chemical reactions,including the indirect photodissociation of diatomic molecules.In contrast to static conical intersections,LICIs are dynamically tunable,providing a pathway for precise control of molecular dissociation.In this study,we employ the time-dependent quantum wave packet method to investigate the dissociation dynamics of the OH molecule,focusing on its ground state X^(2)Πand repulsive state 1^(2)Σ~-.By varying laser field parameters(intensity,full width at half maximum(FWHM),and wavelength),we elucidate how nonadiabatic coupling governs selective dissociation channel control.Our findings reveal that the choice of initial vibrational states and the tailoring of laser conditions significantly influence dissociation pathways,providing theoretical insights into manipulating molecular dynamics via LICIs.These results provide a foundation for future experimental studies and the development of advanced molecular control techniques.展开更多
We introduce CURDIS,a template for algorithms to discretize arcs of regular curves by incrementally producing a list of support pixels covering the arc.In this template,algorithms proceed by finding the tangent quadra...We introduce CURDIS,a template for algorithms to discretize arcs of regular curves by incrementally producing a list of support pixels covering the arc.In this template,algorithms proceed by finding the tangent quadrant at each point of the arc and determining which side the curve exits the pixel according to a tailored criterion.These two elements can be adapted for any type of curve,leading to algorithms dedicated to the shape of specific curves.While the calculation of the tangent quadrant for various curves,such as lines,conics,or cubics,is simple,it is more complex to analyze how pixels are traversed by the curve.In the case of conic arcs,we found a criterion for determining the pixel exit side.This leads us to present a new algorithm,called CURDIS-C,specific to the discretization of conics,for which we provide all the details.Surprisingly,the criterion for conics requires between one and three sign tests and four additions per pixel,making the algorithm efficient for resource-constrained systems and feasible for fixed-point or integer arithmetic implementations.Our algorithm also perfectly handles the pathological cases in which the conic intersects a pixel twice or changes quadrants multiple times within this pixel,achieving this generality at the cost of potentially computing up to two square roots per arc.We illustrate the use of CURDIS for the discretization of different curves,such as ellipses,hyperbolas,and parabolas,even when they degenerate into lines or corners.展开更多
Seismic isolation effectively reduces seismic demands on building structures by isolating the superstructure from ground vibrations during earthquakes.However,isolation strategies give less attention to acceleration-s...Seismic isolation effectively reduces seismic demands on building structures by isolating the superstructure from ground vibrations during earthquakes.However,isolation strategies give less attention to acceleration-sensitive systems or equipment.Meanwhile,as the isolation layer’s displacement grows,the stiffness and frequency of traditional rolling and sliding isolation bearings increases,potentially causing self-centering and resonance concerns.As a result,a new conical pendulum bearing has been selected for acceleration-sensitive equipment to increase self-centering capacity,and additional viscous dampers are incorporated to enhance system damping.Moreover,the theoretical formula for conical pendulum bearings is supplied to analyze the device’s dynamic parameters,and shake table experiments are used to determine the proposed device’s isolation efficiency under various conditions.According to the test results,the newly proposed devices have remarkable isolation performance in terms of minimizing both acceleration and displacement responses.Finally,a numerical model of the isolation system is provided for further research,and the accuracy is demonstrated by the aforementioned experiments.展开更多
The free vibration analysis of a rotating sandwich conical shell with a reentrant auxetic honeycomb core and homogenous isotropic face layers reinforced with a ring support is studied.The shell is modeled utilizing th...The free vibration analysis of a rotating sandwich conical shell with a reentrant auxetic honeycomb core and homogenous isotropic face layers reinforced with a ring support is studied.The shell is modeled utilizing the first-order shear deformation theory(FSDT)incorporating the relative,centripetal,and Coriolis accelerations alongside the initial hoop tension created by the rotation.The governing equations,compatibility conditions,and boundary conditions are attained using Hamilton’s principle.Utilizing trigonometric functions,an analytical solution is derived in the circumferential direction,and a numerical one is presented in the meridional direction via the differential quadrature method(DQM).The effects of various factors on the critical rotational speeds and forward and backward frequencies of the shell are studied.The present work is the first theoretical work regarding the dynamic analysis of a rotating sandwich conical shell with an auxetic honeycomb core strengthened with a ring support.展开更多
Conical picks are important tools for rock mechanical excavation.Mean cutting force(MCF)of conical pick determines the suitability of the target rock for mechanical excavation.Accurate evaluation of MCF is important f...Conical picks are important tools for rock mechanical excavation.Mean cutting force(MCF)of conical pick determines the suitability of the target rock for mechanical excavation.Accurate evaluation of MCF is important for pick design and rock cutting.This study proposed hybrid methods composed of boosting trees and Bayesian optimization(BO)for accurate evaluation of MCF.220 datasets including uniaxial compression strength,tensile strength,tip angle(θ),attack angle,and cutting depth,were collected.Four boosting trees were developed based on the database to predict MCF.BO optimized the hyper-parameters of these boosting trees.Model evaluation suggested that the proposed hybrid models outperformed many commonly utilized machine learning models.The hybrid model composed of BO and categorical boosting(BO-CatBoost)was the best.Its outstanding performance was attributed to its advantages in dealing with categorical features(θincluded 6 types of angles and could be considered as categorical features).A graphical user interface was developed to facilitate the application of BO-CatBoost for the estimation of MCF.Moreover,the influences of the input parameters on the model and their relationship with MCF were analyzed.Whenθincreased from 80°to 90°,it had a significant contribution to the increase of MCF.展开更多
In this paper,based on the mean value theorem of differential,a new method of generating conics such as circles and parabolas is given,and the related algorithm for generating conics is designed.
The coupled dynamic characteristics of the conical electromagnetic bearing are presented and their definitions are given. On the basis of the analyses of the characteristics, the dynamic model of five degrees of freed...The coupled dynamic characteristics of the conical electromagnetic bearing are presented and their definitions are given. On the basis of the analyses of the characteristics, the dynamic model of five degrees of freedom (five-DOF) rotor-conical electromagnetic bearing system is made, and the influence of the coupled characteristics on the system optimal controller is analyzed.展开更多
A modified U-tube conical bubble sonoluminescence device is used to study the conical bubble photoluminescence. The spectra of conical bubble sonoluminescence at different concentrations of rhodamine 6G （Rh6G） solut...A modified U-tube conical bubble sonoluminescence device is used to study the conical bubble photoluminescence. The spectra of conical bubble sonoluminescence at different concentrations of rhodamine 6G （Rh6G） solution in 1,2- propanediol have been measured. Results show that the sonoluminescence from the conical bubbles can directly excite Rh6G, which in turn can fluoresce. The light emission of this kind is referred to as conical bubble photoluminescence. The maximum of fluorescence spectral line intensity in the conical bubble photoluminescence has a red shift in relative to that of the standard photo-excited fluorescence, which is due to the higher self-absorption of Rh6G, and the spectral line of conical bubble photoluminescence is broadened in width compared with that of photo-excited fluorescence.展开更多
The ultrafast dynamics through conical intersections in 2,6-dimethylpyridine has been studied by femtosecond time-resolved photoelectron imaging coupled with time-resolved mass spectroscopy. Upon absorption of 266 nm ...The ultrafast dynamics through conical intersections in 2,6-dimethylpyridine has been studied by femtosecond time-resolved photoelectron imaging coupled with time-resolved mass spectroscopy. Upon absorption of 266 nm pump laser, 2,6-dimethylpyridine is excited to the S2 state with a ππ character from So state. The time evolution of the parent ion signals consists of two exponential decays. One is a fast component on a timescale of 635 fs and the other is a slow component with a timescale of 4.37 ps. Time-dependent photo- electron angular distributions and energy-resolved photoelectron spectroscopy are extracted from time-resolved photoelectron imaging and provide the evolutive information of S2 state. In brief, the ultrafast component is a population transfer from S2 to S1 through the S2/S1 conical intersections, the slow component is attributed to simultaneous IC from the S2 state and the higher vibrational levels of S1 state to So state, which involves the coupling of S2/S0 and S1/So conical intersections. Additionally, the observed ultrafast S2--＋S1 transition occurs only with an 18% branching ratio.展开更多
The water-lubricated conical bearing has attracted attentions of researchers for its simple structure, easily adjusted gap （fdm thickness ）, lower friction loss, and less pollution in application. A mathematic model...The water-lubricated conical bearing has attracted attentions of researchers for its simple structure, easily adjusted gap （fdm thickness ）, lower friction loss, and less pollution in application. A mathematic model with consideration of the effects of turbulence, two-phase flow, and temperature on the pressure field at bearing surface is proposed here. Using this model, the Reynolds＇ equation and energy equation are solved in which the thermo- physical properties of the water as lubricant are taken into account. The dependency of characteristics of bearing, such as load-earrying capacity, flow rate （pumping losses ）, and frictional losses, on angular velocity, conical angle, and radial eccentricities, is presented. The research results are beneficial to the improvement of the efficiency of conical bearing and the environmental protection.展开更多
This paper concerns the sonic-supersonic structures of the transonic crossflow generated by the steady supersonic flow past an infinite cone of arbitrary cross section.Under the conical assumption,the three-dimensiona...This paper concerns the sonic-supersonic structures of the transonic crossflow generated by the steady supersonic flow past an infinite cone of arbitrary cross section.Under the conical assumption,the three-dimensional(3-D)steady Euler equations can be projected onto the unit sphere and the state of fluid can be characterized by the polar and azimuthal angles.Given a segment smooth curve as a conical-sonic line in the polar-azimuthal angle plane,we construct a classical conical-supersonic solution near the curve under some reasonable assumptions.To overcome the difficulty caused by the parabolic degeneracy,we apply the characteristic decomposition technique to transform the Euler equations into a new degenerate hyperbolic system in a partial hodograph plane.The singular terms are isolated from the highly nonlinear complicated system and then can be handled successfully.We establish a smooth local solution to the new system in a suitable weighted metric space and then express the solution in terms of the original variables.展开更多
In this paper, a new derivative free trust region method is developed based on the conic interpolation model for the unconstrained optimization. The conic interpolation model is built by means of the quadratic model f...In this paper, a new derivative free trust region method is developed based on the conic interpolation model for the unconstrained optimization. The conic interpolation model is built by means of the quadratic model function, the collinear scaling formula, quadratic approximation and interpolation. All the parameters in this model are determined by objective function interpolation condition. A new derivative free method is developed based upon this model and the global convergence of this new method is proved without any information on gradient.展开更多
Conical spiral tube bundle are universally used in heat transfer enhancement in heat exchangers.The heat transfer and resistance of the tube bundle are affected greatly by the conical structure,so the analysis of it i...Conical spiral tube bundle are universally used in heat transfer enhancement in heat exchangers.The heat transfer and resistance of the tube bundle are affected greatly by the conical structure,so the analysis of it is necessary.In order to a further evaluation,the heat transfer and resistance characteristics of conical spiral tube bundle are investigated with regression analysis based on numerical simulation data.The correlations of heat transfer and pressure drop of conical spiral tube bundle are proposed both in laminar and turbulent fluid flow.On the based of the field synergy principle,the synergy of four vectors,the velocity,the velocity gradient,the temperature gradient and the pressure gradient,are calculated and discussed via the user defined function（UDF） program.The synergy angles β and θ,which respectively denote the performance of heat transfer enhancement and pressure drop of the conical spiral tube bundle,are analyzed.Finally,the comprehensive performance of the conical spiral tube is evaluated by the synergy angle γ and all of the three synergy angles of conical spiral tube bundle are compared to both bare tube and thin cylinder-interpolated tube.The analysis of the synergy angles shows that the heat transfer enhancement and pressure drop of conical spiral tube bundle are smaller than that of the thin cylinder-interpolated tube,while the comprehensive performance of conical spiral tube bundle is greater.The analysis of the heat transfer and pressure drop of conical spiral tube is valuable and instructional on the design and optimum of conical spiral tube bundle heat exchangers.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52174099 and 52474168)the Science and Technology Innovation Program of Hunan Province,China(No.2023RC3050)+1 种基金the Natural Science Foundation of Hunan,China(No.2024JJ4064)the Open Fund of the State Key Laboratory of Safety Technology of Metal Mines(No.kfkt2023-01).
文摘Real-time identification of rock strength and cuttability based on monitoring while cutting during excavation is essential for key procedures such as the precise adjustment of excavation parameters and the in-situ modification of hard rocks.This study proposes an in-telligent approach for predicting rock strength and cuttability.A database comprising 132 data sets is established,containing cutting para-meters(such as cutting depth and pick angle),cutting responses(such as specific energy and instantaneous cutting rate),and rock mech-anical parameters collected from conical pick-cutting experiments.These parameters serve as input features for predicting the uniaxial compressive strength and tensile strength of rocks using regression fitting and machine learning methodologies.In addition,rock cuttabil-ity is classified using a combination of the analytic hierarchy process and fuzzy comprehensive evaluation method,and subsequently iden-tified through machine learning approaches.Various models are compared to determine the optimal predictive and classification models.The results indicate that the optimal model for uniaxial compressive strength and tensile strength prediction is the genetic algorithm-optimized backpropagation neural network model,and the optimal model for rock cuttability classification is the radial basis neural network model.
基金supported by financial grants from the National Natural Science Foundation of China(Grant Nos.52334003 and 52104111)the National Key R&D Program of China(Grant No.2022YFC2905600)。
文摘Water-weakening presents a promising strategy for the in-situ improvement of rock cuttability.This study unveils the influences of water saturation on the mechanical response and fragmentation characteristics of rock samples.A series of rock-cutting tests using conical pick indentation was conducted on three types of sandstone samples under both dry and water-saturated conditions.The relationships between cutting force and indentation depth,as well as typical cuttability indices are determined and compared for dry and water-saturated samples.The experimental results reveal that the presence of water facilitates shearing failure in rock samples,as well as alleviates the fluctuations in the cutting force-indentation depth curve Furthermore,the peak cutting force(F_(p)),cutting work(W_(p)),and specific energy(SE)undergo apparent decrease after water saturation,whereas the trend in the indentation depth at rock failure(D_(f))varies across different rock types.Additionally,the water-induced percentage reductions in F_(p)and SE correlate positively with the quartz and swelling clay content within the rocks,suggesting that the cuttability improvement due to water saturation is attributed to the combined effects of stress corrosion and frictional reduction.These findings carry significant implications for improving rock cuttability in mechanized excavation of hard rock formations.
基金supported by the NSFC Key International(Regional)Cooperative Research Projects(No.52020105001)National Natural Science Foundation of China(52304014)+2 种基金China Postdoctoral Science Foundation funded project(2023M733873)the Science Foundation of China University of Petroleum,Beijing(No.2462023SZBH003)General Program of National Natural Science Foundation of China(52374016,52274016)。
文摘The oil and gas stored in deep and ultra-deep carbonate reservoirs is the focus of future exploration and development.Conical PDC(Polycrystalline Diamond Compact)cutter,which is a new kind of PDC cutter,can significantly improve the rate of penetration(ROP)and extend PDC bit life in hard and abrasive formations.However,the breakage characteristics and failure mode of the conical PDC cutter cutting carbonate rock is still masked.In this paper,a series of single-cutter cutting tests were carried out with the conical and conventional PDC cutters.The cutting force,rock-breaking process,surface morphology of cutting grooves and cuttings characteristic were analyzed.Based on the derived formula of the brittle fracture index,the failure model of carbonate rock was quantitatively analyzed under the action of conical and conventional cutter.The results show that the average cutting force of the conical cutter is less than that of the conventional cutter,which means greater stability of the cutting process using the conical cutter.Carbonate rock with calcite as the main component tends to generate blocky rock debris by conical cutter.The height of the cuttings generated by the conical cutter is 0.5 mm higher than that generated by the conventional cutter.The conical cutter exhibits enhanced penetration capabilities within carbonate rock.The accumulation of rock debris in front of the conventional cutter is obvious.Whereas,the conical cutter facilitates the cuttings transport,thereby alleviating drilling stickiness slip.At different cutting depths,the conical cutter consistently causes asymmetric jagged brittle tensile fracture zones on both sides of the cutting groove.Calculations based on the brittle fracture index demonstrate that the brittle fracture index of the conical cutter generally doubles that of the conventional cutter.For carbonate rock,the conical cutter displays superior utilization of brittle fracture abilities.The research findings of this work offer insights into the breakage process and failure mode of carbonate rock by the conical cutter.
基金supported by the Guangdong high level Innovation Research Institute(Grant No.2021B0909050006).
文摘Because of their remarkable properties,room-temperature ionic liquids(RTILs)are used widely in electrochemistry,fuel cells,supercapacitors,and even DNA sequencing,and many of these applications involve the transport of RTILs in nanoscale media.Particularly for single-molecule detection,the RTIL must be mixed with a solvent(e.g.,water)so that the electrolyte has both high viscosity and conductivity to obtain excellent signals.If a RTIL contains a quantity of water in bulk,this has a significant effect on its properties(e.g.,the electrochemical window),thereby limiting some applications.However,the physicochemical properties of RTILs containing water in nanoconfined spaces remain unclear,especially their ionic transport behavior.Therefore,reported here is a study of the ionic transport behavior of mixed RTIL/water solutions at the nanoscale using a single conical nanochannel as a nanofluidic platform.The conductivity of the mixtures in the nanoconfined space was closely related to the nanochannel size,and highly diluted mixed solutions resulted in a nonlinear rectificationreversed current,which was possibly due to the adsorption of cations on the nanochannel wall.The maximum rectification ratio was 114,showing excellent rectification that could be used to realize newly conceptualized nanofluidic diodes.In summary,this work provides an exhaustive understanding of the nonlinear ion transport of RTIL/water mixtures and a theoretical foundation for applying RTILs in energy storage and conversion and bio-sensing.
基金Supported by the National Natural Science Foundation of China(Nos.12272056 and 11832002)。
文摘This paper investigates the active traveling wave vibration control of an elastic supported rotating porous aluminium conical shell(CS)under impact loading.Piezoelectric smart materials in the form of micro fiber composites(MFCs)are used as actuators and sensors.To this end,a metal pore truncated CS with MFCs attached to its surface is considered.Adding artificial virtual springs at two edges of the truncated CS achieves various elastic supported boundaries by changing the spring stiffness.Based on the first-order shear deformation theory(FSDT),minimum energy principle,and artificial virtual spring technology,the theoretical formulations considering the electromechanical coupling are derived.The comparison of the natural frequency of the present results with the natural frequencies reported in previous literature evaluates the accuracy of the present approach.To study the vibration control,the integral quadrature method in conjunction with the differential quadrature approximation in the length direction is used to discretize the partial differential dynamical system to form a set of ordinary differential equations.With the aid of the velocity negative feedback method,both the time history and the input control voltage on the actuator are demonstrated to present the effects of velocity feedback gain,pore distribution type,semi-vertex angle,impact loading,and rotational angular velocity on the traveling wave vibration control.
基金Supported by Major Instrument Project of National Natural Science Foundation of China(52327803)Major Project of National Natural Science Foundation of China(52192622).
文摘Based on the finite-discrete element method,a three-dimensional numerical model for axial impact rock breaking was established and validated.A computational method for energy conversion during impact rock breaking was proposed,and the effects of conical tooth forward rake angle,rock temperature,and impact velocity on rock breaking characteristics and energy transfer laws were analyzed.The results show that during single impact rock breaking with conical tooth bits,merely 7.52%to 12.51%of the energy is utilized for rock breaking,while a significant 57.26%to 78.10%is dissipated as frictional loss.An insufficient forward rake angle increases tooth penetration depth and frictional loss,whereas an excessive forward rake angle reduces penetration capability,causing bit rebound and greater energy absorption by the drill rod.Thus,an optimal forward rake angle exists.Regarding environmental factors,high temperatures significantly enhance impact-induced rock breaking.Thermal damage from high temperatures reduces rock strength and inhibits its energy absorption.Finally,higher impact velocities intensify rock damage,yet excessively high velocities increase frictional loss and reduce the proportion of energy absorbed by the rock,thereby failing to substantially improve rock breaking efficiency.An optimal impact velocity exists.
基金supported by the National Natural Science Foundation of China(Grant Nos.12134005 and 12334011)the Major Research Plan of the National Natural Science Foundation of China(Grant No.92461301)。
文摘Light-induced conical intersections(LICIs)present a distinctive mechanism for nonadiabatic coupling,thereby facilitating ultrafast chemical reactions,including the indirect photodissociation of diatomic molecules.In contrast to static conical intersections,LICIs are dynamically tunable,providing a pathway for precise control of molecular dissociation.In this study,we employ the time-dependent quantum wave packet method to investigate the dissociation dynamics of the OH molecule,focusing on its ground state X^(2)Πand repulsive state 1^(2)Σ~-.By varying laser field parameters(intensity,full width at half maximum(FWHM),and wavelength),we elucidate how nonadiabatic coupling governs selective dissociation channel control.Our findings reveal that the choice of initial vibrational states and the tailoring of laser conditions significantly influence dissociation pathways,providing theoretical insights into manipulating molecular dynamics via LICIs.These results provide a foundation for future experimental studies and the development of advanced molecular control techniques.
文摘We introduce CURDIS,a template for algorithms to discretize arcs of regular curves by incrementally producing a list of support pixels covering the arc.In this template,algorithms proceed by finding the tangent quadrant at each point of the arc and determining which side the curve exits the pixel according to a tailored criterion.These two elements can be adapted for any type of curve,leading to algorithms dedicated to the shape of specific curves.While the calculation of the tangent quadrant for various curves,such as lines,conics,or cubics,is simple,it is more complex to analyze how pixels are traversed by the curve.In the case of conic arcs,we found a criterion for determining the pixel exit side.This leads us to present a new algorithm,called CURDIS-C,specific to the discretization of conics,for which we provide all the details.Surprisingly,the criterion for conics requires between one and three sign tests and four additions per pixel,making the algorithm efficient for resource-constrained systems and feasible for fixed-point or integer arithmetic implementations.Our algorithm also perfectly handles the pathological cases in which the conic intersects a pixel twice or changes quadrants multiple times within this pixel,achieving this generality at the cost of potentially computing up to two square roots per arc.We illustrate the use of CURDIS for the discretization of different curves,such as ellipses,hyperbolas,and parabolas,even when they degenerate into lines or corners.
基金Scientific Research Fund of Institute of Engineering Mechanics,CEA under Grant No.2019A03Scientific Research Fund of Institute of Engineering Mechanics,CEA under Grant No.2021D12National Key R&D Program of China under No.2018YFC1504404。
文摘Seismic isolation effectively reduces seismic demands on building structures by isolating the superstructure from ground vibrations during earthquakes.However,isolation strategies give less attention to acceleration-sensitive systems or equipment.Meanwhile,as the isolation layer’s displacement grows,the stiffness and frequency of traditional rolling and sliding isolation bearings increases,potentially causing self-centering and resonance concerns.As a result,a new conical pendulum bearing has been selected for acceleration-sensitive equipment to increase self-centering capacity,and additional viscous dampers are incorporated to enhance system damping.Moreover,the theoretical formula for conical pendulum bearings is supplied to analyze the device’s dynamic parameters,and shake table experiments are used to determine the proposed device’s isolation efficiency under various conditions.According to the test results,the newly proposed devices have remarkable isolation performance in terms of minimizing both acceleration and displacement responses.Finally,a numerical model of the isolation system is provided for further research,and the accuracy is demonstrated by the aforementioned experiments.
文摘The free vibration analysis of a rotating sandwich conical shell with a reentrant auxetic honeycomb core and homogenous isotropic face layers reinforced with a ring support is studied.The shell is modeled utilizing the first-order shear deformation theory(FSDT)incorporating the relative,centripetal,and Coriolis accelerations alongside the initial hoop tension created by the rotation.The governing equations,compatibility conditions,and boundary conditions are attained using Hamilton’s principle.Utilizing trigonometric functions,an analytical solution is derived in the circumferential direction,and a numerical one is presented in the meridional direction via the differential quadrature method(DQM).The effects of various factors on the critical rotational speeds and forward and backward frequencies of the shell are studied.The present work is the first theoretical work regarding the dynamic analysis of a rotating sandwich conical shell with an auxetic honeycomb core strengthened with a ring support.
基金Project(52374153)supported by the National Natural Science Foundation of ChinaProject(2023zzts0726)supported by the Fundamental Research Funds for the Central Universities of Central South University,China。
文摘Conical picks are important tools for rock mechanical excavation.Mean cutting force(MCF)of conical pick determines the suitability of the target rock for mechanical excavation.Accurate evaluation of MCF is important for pick design and rock cutting.This study proposed hybrid methods composed of boosting trees and Bayesian optimization(BO)for accurate evaluation of MCF.220 datasets including uniaxial compression strength,tensile strength,tip angle(θ),attack angle,and cutting depth,were collected.Four boosting trees were developed based on the database to predict MCF.BO optimized the hyper-parameters of these boosting trees.Model evaluation suggested that the proposed hybrid models outperformed many commonly utilized machine learning models.The hybrid model composed of BO and categorical boosting(BO-CatBoost)was the best.Its outstanding performance was attributed to its advantages in dealing with categorical features(θincluded 6 types of angles and could be considered as categorical features).A graphical user interface was developed to facilitate the application of BO-CatBoost for the estimation of MCF.Moreover,the influences of the input parameters on the model and their relationship with MCF were analyzed.Whenθincreased from 80°to 90°,it had a significant contribution to the increase of MCF.
文摘In this paper,based on the mean value theorem of differential,a new method of generating conics such as circles and parabolas is given,and the related algorithm for generating conics is designed.
文摘The coupled dynamic characteristics of the conical electromagnetic bearing are presented and their definitions are given. On the basis of the analyses of the characteristics, the dynamic model of five degrees of freedom (five-DOF) rotor-conical electromagnetic bearing system is made, and the influence of the coupled characteristics on the system optimal controller is analyzed.
基金Project supported by the National Science Foundation of China（Grant No 1993340041）, the State Key Development Program for Basic Research of China（Grant No 2002CCA03400）, the Institute of 0pto-Electronics, Harbin Institute of Technology of China（Grant No 51472080304ZK0501）, and the Science Foundation of Hebei University, China（Grant No 2005Q06）.
文摘A modified U-tube conical bubble sonoluminescence device is used to study the conical bubble photoluminescence. The spectra of conical bubble sonoluminescence at different concentrations of rhodamine 6G （Rh6G） solution in 1,2- propanediol have been measured. Results show that the sonoluminescence from the conical bubbles can directly excite Rh6G, which in turn can fluoresce. The light emission of this kind is referred to as conical bubble photoluminescence. The maximum of fluorescence spectral line intensity in the conical bubble photoluminescence has a red shift in relative to that of the standard photo-excited fluorescence, which is due to the higher self-absorption of Rh6G, and the spectral line of conical bubble photoluminescence is broadened in width compared with that of photo-excited fluorescence.
基金This work was supported by the National Natural Science Foundation of China （No.10704083）,the Innovation Foundation of Chinese Academyof Sciences （No.KJCX1-YW-N30）, and the Public Science and Technology Program of Shenzhen （No.SY200806260026A）.
文摘The ultrafast dynamics through conical intersections in 2,6-dimethylpyridine has been studied by femtosecond time-resolved photoelectron imaging coupled with time-resolved mass spectroscopy. Upon absorption of 266 nm pump laser, 2,6-dimethylpyridine is excited to the S2 state with a ππ character from So state. The time evolution of the parent ion signals consists of two exponential decays. One is a fast component on a timescale of 635 fs and the other is a slow component with a timescale of 4.37 ps. Time-dependent photo- electron angular distributions and energy-resolved photoelectron spectroscopy are extracted from time-resolved photoelectron imaging and provide the evolutive information of S2 state. In brief, the ultrafast component is a population transfer from S2 to S1 through the S2/S1 conical intersections, the slow component is attributed to simultaneous IC from the S2 state and the higher vibrational levels of S1 state to So state, which involves the coupling of S2/S0 and S1/So conical intersections. Additionally, the observed ultrafast S2--＋S1 transition occurs only with an 18% branching ratio.
基金Natural Science Foundation of Heilongjiang Province of China (No.LC2009C05)
文摘The water-lubricated conical bearing has attracted attentions of researchers for its simple structure, easily adjusted gap （fdm thickness ）, lower friction loss, and less pollution in application. A mathematic model with consideration of the effects of turbulence, two-phase flow, and temperature on the pressure field at bearing surface is proposed here. Using this model, the Reynolds＇ equation and energy equation are solved in which the thermo- physical properties of the water as lubricant are taken into account. The dependency of characteristics of bearing, such as load-earrying capacity, flow rate （pumping losses ）, and frictional losses, on angular velocity, conical angle, and radial eccentricities, is presented. The research results are beneficial to the improvement of the efficiency of conical bearing and the environmental protection.
基金the two referees for very helpful comments and suggestions to improve the quality of the paper.This work was partially supported by the Natural Science Foundation of Zhejiang province of China(LY21A010017)the National Natural Science Foundation of China(12071106,12171130).
文摘This paper concerns the sonic-supersonic structures of the transonic crossflow generated by the steady supersonic flow past an infinite cone of arbitrary cross section.Under the conical assumption,the three-dimensional(3-D)steady Euler equations can be projected onto the unit sphere and the state of fluid can be characterized by the polar and azimuthal angles.Given a segment smooth curve as a conical-sonic line in the polar-azimuthal angle plane,we construct a classical conical-supersonic solution near the curve under some reasonable assumptions.To overcome the difficulty caused by the parabolic degeneracy,we apply the characteristic decomposition technique to transform the Euler equations into a new degenerate hyperbolic system in a partial hodograph plane.The singular terms are isolated from the highly nonlinear complicated system and then can be handled successfully.We establish a smooth local solution to the new system in a suitable weighted metric space and then express the solution in terms of the original variables.
基金This work was supported by the National Natural Science Foundation of China(10071037)
文摘In this paper, a new derivative free trust region method is developed based on the conic interpolation model for the unconstrained optimization. The conic interpolation model is built by means of the quadratic model function, the collinear scaling formula, quadratic approximation and interpolation. All the parameters in this model are determined by objective function interpolation condition. A new derivative free method is developed based upon this model and the global convergence of this new method is proved without any information on gradient.
基金supported by National Basic Research Program of China(973 Program,Grant No. 2007CB206900)Scholarship Award for Doctoral by Ministry of Education of China(Grant No. 10000071183646)
文摘Conical spiral tube bundle are universally used in heat transfer enhancement in heat exchangers.The heat transfer and resistance of the tube bundle are affected greatly by the conical structure,so the analysis of it is necessary.In order to a further evaluation,the heat transfer and resistance characteristics of conical spiral tube bundle are investigated with regression analysis based on numerical simulation data.The correlations of heat transfer and pressure drop of conical spiral tube bundle are proposed both in laminar and turbulent fluid flow.On the based of the field synergy principle,the synergy of four vectors,the velocity,the velocity gradient,the temperature gradient and the pressure gradient,are calculated and discussed via the user defined function（UDF） program.The synergy angles β and θ,which respectively denote the performance of heat transfer enhancement and pressure drop of the conical spiral tube bundle,are analyzed.Finally,the comprehensive performance of the conical spiral tube is evaluated by the synergy angle γ and all of the three synergy angles of conical spiral tube bundle are compared to both bare tube and thin cylinder-interpolated tube.The analysis of the synergy angles shows that the heat transfer enhancement and pressure drop of conical spiral tube bundle are smaller than that of the thin cylinder-interpolated tube,while the comprehensive performance of conical spiral tube bundle is greater.The analysis of the heat transfer and pressure drop of conical spiral tube is valuable and instructional on the design and optimum of conical spiral tube bundle heat exchangers.
