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
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
In Bangladesh, the use of machinery in agriculture production is fast rising. Researchers are developing technology to replace traditional hand weeding to manage weeds in rice fields. The present study has been taken ...In Bangladesh, the use of machinery in agriculture production is fast rising. Researchers are developing technology to replace traditional hand weeding to manage weeds in rice fields. The present study has been taken to increase weeding efficiency and reduce the drudgery in weeding and mulching. A line-to-line distance of 20 cm, the operation is push-pull, and field operating condition at 2 - 4 cm standing water (for softening the field) was the designed hypothesis. The weeder consists of a skid/float, float holder, float adjuster, main body frame, rotor, axel, bush, rotor holder, rotor holder adjuster, handle, handle griper, handle holder, handle height adjuster, nut, bolt, etc. The designed weeder was fabricated using MS sheet, MS pipe, MS flat bar, MS nut-bolt, etc. When the rotors perform back and forth, the weeder’s two conical rotors with six plain blades and six serrated blades work together to uproot and bury the weeds. It also contains a 2 mm thick float assembly with a precise angle of 22 degrees. Weeds are uprooted by the weeder’s blades and buried in the muddy soil. It causes topsoil disturbance and enhances aeration. The weeding efficiency and capacity of the conical weeder were 81.92% and 0.0203 ha/h respectively. With a push-pull operation, the weeder can uproot and bury the weeds in a single row at a time. The pushing force and weight of weeder were 43.42 N and 5.6 kg respectively. Farmers can use this weeder to increase their comfort and reduce the drudgery associated with weeding and mulching in their fields.展开更多
Buckling and postbuckling characteristics of laminated graphene-enhanced composite(GEC)truncated conical shells exposed to torsion under temperature conditions using finite element method(FEM)simulation are presented ...Buckling and postbuckling characteristics of laminated graphene-enhanced composite(GEC)truncated conical shells exposed to torsion under temperature conditions using finite element method(FEM)simulation are presented in this study.In the thickness direction,the GEC layers of the conical shell are ordered in a piece-wise arrangement of functionally graded(FG)distribution,with each layer containing a variable volume fraction for graphene reinforcement.To calculate the properties of temperaturedependent material of GEC layers,the extended Halpin-Tsai micromechanical framework is used.The FEM model is verified via comparing the current results obtained with the theoretical estimates for homogeneous,laminated cylindrical,and conical shells,the FEM model is validated.The computational results show that a piece-wise FG graphene volume fraction distribution can improve the torque of critical buckling and torsional postbuckling strength.Also,the geometric parameters have a critical impact on the stability of the conical shell.However,a temperature rise can reduce the crucial torsional buckling torque as well as the GEC laminated truncated conical shell’s postbuckling strength.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
The vibrator plate is the link between the vibroseis vehicle and the earth,as well as the core com-ponent of the vibrator vehicle.In this paper,the coupling effect between the vibrator plate and the earth is an-alyzed...The vibrator plate is the link between the vibroseis vehicle and the earth,as well as the core com-ponent of the vibrator vehicle.In this paper,the coupling effect between the vibrator plate and the earth is an-alyzed from two aspects of reaction tooth arrangement and reaction tooth conical angle,and three groups of experimental models are optimized and designed.The model construction and numerical analysis of the shear wave vibroseis vibrator plate are carried out with ANSYS software.The motion law between the vibration plate and the earth at work was studied,the strain energy of the three experimental models in operation,the maximum displacement of particle at the same position and other reference indices were compared and ana-lyzed,with 28 conical reaction teeth were arranged on both sides.The coupling effect between the vibration plate and the earth was best when the tooth angle was 60°.Compared with the toothless vibration plate,the energy efficiency is improved by about 20%,and the coupling effect between the vibrator plate and the earth is effectively enhanced.It is found that the coupling effect is enhanced through increasing the number of reac-tion teeth of the vibration plate by increasing the coupling area between the vibration plate and the earth.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.
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
Water jet thruster, which is a marine system that creates a jet of water for propulsion, has several advantages such as low noise, good anti-cavitation characteristics and maneuvering characteristics. The reaction thr...Water jet thruster, which is a marine system that creates a jet of water for propulsion, has several advantages such as low noise, good anti-cavitation characteristics and maneuvering characteristics. The reaction thrust characteristics of water jet for conical nozzles directly determine the speed of autonomous underwater vehicles (AUV). Theoretical, numerical and experimental studies have been, carried out to investigate the effects of the nozzle geometries as well as inlet conditions on the reaction thrust of water jet in this paper. The experimental results show that: 1) the reaction thrust is proportional to inlet pressure, the square of flow rate and 2/3 power exponent of input power; 2) the diameter of cylinder column for conical nozzle has great influence on the reaction thrust characteristics; 3) the best values of the half cone angle and the cylinder column length exist to make the reaction thrust coefficient to reach the maximum under the same inlet conditions. Those provide a basis for nozzles design and have significant value, especially for developing high performance and efficiency water jet propulsion unit.展开更多
New plasticity solutions to the drained stability of conical slopes in homogeneous cohesive-frictional soils were investigated by axisymmetric finite element limit analysis. Three parameters were studied,i.e. excavate...New plasticity solutions to the drained stability of conical slopes in homogeneous cohesive-frictional soils were investigated by axisymmetric finite element limit analysis. Three parameters were studied,i.e. excavated height ratios, slope inclination angles, and soil friction angles. The influences of these parameters on the stability factor and predicted failure mechanism of conical slopes were discussed. A new design equation developed from a nonlinear regression of the lower bound solution was proposed for drained stability analyses of a conical slope in practice. Numerical examples were given to demonstrate a practical application of the proposed equation to stability evaluations of conical slopes with both associated and non-associated flow rules.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
Based on B-spline wavelet on the interval (BSWI), two classes of truncated conical shell elements were constructed to solve axisymmetric problems, i.e. BSWI thin truncated conical shell element and BSWI moderately t...Based on B-spline wavelet on the interval (BSWI), two classes of truncated conical shell elements were constructed to solve axisymmetric problems, i.e. BSWI thin truncated conical shell element and BSWI moderately thick truncated conical shell element with independent slopedeformation interpolation. In the construction of wavelet-based element, instead of traditional polynomial interpolation, the scaling functions of BSWI were employed to form the shape functions through the constructed elemental transformation matrix, and then construct BSWI element via the variational principle. Unlike the process of direct wavelets adding in the wavelet Galerkin method, the elemental displacement field represented by the coefficients of wavelets expansion was transformed into edges and internal modes via the constructed transformation matrix. BSWI element combines the accuracy of B-spline function approximation and various wavelet-based elements for structural analysis. Some static and dynamic numerical examples of conical shells were studied to demonstrate the present element with higher efficiency and precision than the traditional element.展开更多
The problem of ice induced vibration is common to ocean engineering of cold region countries. To study the ice induced vibration of a compliant conical structure, a series of model tests have been performed and some b...The problem of ice induced vibration is common to ocean engineering of cold region countries. To study the ice induced vibration of a compliant conical structure, a series of model tests have been performed and some breakthrough progresses made. The ice sheet before the compliant conical structure is found to fail by two-time breaking in the tests. The process of two-time breaking behaves in two modes, and the general control of the ice and structural conditions determine the mode in which the ice force would behave. Two dynamic ice force functions are established respectively for the two modes of two-time breaking process in this paper. The numerical simulation results are in good agreement with the measured results, indicating that the dynamic ice force functions given in this paper can fully reflect the real situation of the dynamic ice force on a compliant conical structure.展开更多
We prove that, under a semi-ampleness type assumption on the twisted canonical line bundle, the conical Kahler-Ricci flow on a minimal elliptic Kahler surface converges in the sense of currents to a generalized conica...We prove that, under a semi-ampleness type assumption on the twisted canonical line bundle, the conical Kahler-Ricci flow on a minimal elliptic Kahler surface converges in the sense of currents to a generalized conical Kahler-Einstein on its canonical model. Moreover, the convergence takes place smoothly outside the singular fibers and the chosen divisor.展开更多
Conical cam mechanism has been widely used in modern machinery and equipment.However,the commonly used planar expansion methods for the design of spatial cam contour produce significant errors,because these methods in...Conical cam mechanism has been widely used in modern machinery and equipment.However,the commonly used planar expansion methods for the design of spatial cam contour produce significant errors,because these methods incorrectly use the distance from the axis of the follower to the main conical cam to replace the corresponding arc length on the conical cam.HSIEH,et al,used analytical methods to achieve higher accuracy,but these analytical methods have their own drawbacks since they are too complicated for practical use.Through the analysis of the errors created during the generation of conical cam contour using the existing expansion methods,this paper proposes to include diverge angle in the calculation of conical cam rotation angle in the equation of conical cam contour expansion.This correction eliminates the error generated by the commonly used methods.Based on the expression of the follower's 3D trajectory and the spatial geometry of conical cam,this paper has deduced the planar polar curve equation for determining polar coordinates for the curve of planar expansion outline.Furthermore,this paper provides an example of conical cam contour design based on sinusoidal acceleration variation.According to polar coordinates and the movement of curve equation function expression,this paper applies MATLAB software to solve coordinates for the cam expansion curve and uses AutoCAD software to generate conical cam expansion contour that meets the requirement of the law of motion.The proposed method provides a design process that is simple,intuitive and easy to master and implement.It also avoids the design error in the traditional methods for generating contour of conical cam with oscillating follower that requires high precision.展开更多
Duty-cycle modulation alternately blowing from two opposite-facing plasma actu- ators on the leeward surface near the apex of a cone with a 10° semi-apex angle is adopted to control mean lateral force and moment,...Duty-cycle modulation alternately blowing from two opposite-facing plasma actu- ators on the leeward surface near the apex of a cone with a 10° semi-apex angle is adopted to control mean lateral force and moment, and the flow control mechanisms are presented. Pressure distributions over the forebody of the cone are measured by steady pressure tappings. The experiments are performed in a 3.0×1.6 m open-circuit wind tunnel at a wind speed of 20 m/s, a 45° angle of attack and a Reynolds number of 2×10^5, based on the diameter of the base of the cone. Almost linearly proportional control of the lateral forces and moments over a slender conical forebody at a high angle of attack has been demonstrated by employing a pair of single dielectric barrier discharge plasma actuators near the apex of the cone, combined with a duty-cycle tech- nique. The pressure distribution measurements indicate that the hi-stable vortex pattern appears to be shifted in the opposite direction when the port or starboard actuator is activated, while the other is kept off during the test. It is shown that the reduced pulse-repetition frequency based on the local diameter at the plasma actuator equal to one yields the highest effectiveness among the cases considered.展开更多
In order to solve the problem of broadband field probes calibration with only selected discrete frequencies above 1 GHz, a sweep-frequency calibration technology based on a coaxial conical(co-conical) cell is resear...In order to solve the problem of broadband field probes calibration with only selected discrete frequencies above 1 GHz, a sweep-frequency calibration technology based on a coaxial conical(co-conical) cell is researched. Existing research is only qualitative because of the complexity of theoretical calculations. For designing a high performance cell, a mathematic model of high-order modes transmission is built according to the geometrical construction of co-conical. The associated Legendre control functions of high-order modes are calculated by using recursion methodology and the numerical calculation roots are presented with different half angles of inner and outer conductor. Relationship between roots and high-order modes transmission is analyzed, when the half angles of inner conductor and outer conductor are θ1=1.5136° and θ2=8° respectively, the co-conical cell has better performance for fewer transmitting high-order modes. The propagation process of the first three transmitting modes wave is simulated in CST-MWS software from the same structured co-conical. The simulation plots show that transmission of high-order modes appears with electromagnetic wave reflection, then different high-order mode transmission has different cut-off region and each cut-off region is determined by its cut-off wavelength. This paper presents numerical calculation data and theoretical analysis to design key structural parameters for the co-conical transverse electromagnetic wave cell(co-conical TEM cell).展开更多
The internal turbulent flow in conical diffuser is a very complicated adverse pressure gradient flow.DLR k-ε turbulence model was adopted to study it.The every terms of the Laplace operator in DLR k-ε turbulence mod...The internal turbulent flow in conical diffuser is a very complicated adverse pressure gradient flow.DLR k-ε turbulence model was adopted to study it.The every terms of the Laplace operator in DLR k-ε turbulence model and pressure Poisson equation were discretized by upwind difference scheme.A new full implicit difference scheme of 5-point was constructed by using finite volume method and finite difference method.A large sparse matrix with five diagonals was formed and was stored by three arrays of one dimension in a compressed mode.General iterative methods do not work wel1 with large sparse matrix.With algebraic multigrid method(AMG),linear algebraic system of equations was solved and the precision was set at 10-6.The computation results were compared with the experimental results.The results show that the computation results have a good agreement with the experiment data.The precision of computational results and numerical simulation efficiency are greatly improved.展开更多
Conical vascular tubes are of strong demand owing to their formed shape and excellent characters to mimic human blood vessels. In this study,the automatic shuttle loom and computer aided design( CAD) system were custo...Conical vascular tubes are of strong demand owing to their formed shape and excellent characters to mimic human blood vessels. In this study,the automatic shuttle loom and computer aided design( CAD) system were customized to prepare a conical vascular graft. Meanwhile, the weaving principle of a conical vascular graft was identified in terms of the lift-drop front rest,and the geometrical relations were established among the cloth fell,front rest and back rest. Also,the change of weft density from the liftdrop motion of the front rest was analyzed,and a strategy was established to compensate the offset of weft density by changing the taken-up length. Afterwards,the proposed weaving principles were demonstrated by weaving a conical vascular graft on the customized shuttle loom.展开更多
An analytical solution for buckling of an eccentrically stiffened sandwich truncated conical shell is investigated. The shell consists of two functionally graded material (FGM) coating layers and a core layer which ...An analytical solution for buckling of an eccentrically stiffened sandwich truncated conical shell is investigated. The shell consists of two functionally graded material (FGM) coating layers and a core layer which are metal or ceramic subjected to an axial compressive load and an external uniform pressure. Shells are reinforced by stringers and rings, in which the material properties of shells and stiffeners are graded in the thickness direction following a general sigmoid law distribution. Two models of coated shell-stiffener arrangements are investigated. The change of the spacing between stringers in the meridional direction is taken into account. A couple set of three-variable- coefficient partial differential equations in terms of displacement components are solved by the Galerkin method. A closed-form expression for determining the buckling load is obtained. The numerical examples are presented and compared with previous works.展开更多
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In Bangladesh, the use of machinery in agriculture production is fast rising. Researchers are developing technology to replace traditional hand weeding to manage weeds in rice fields. The present study has been taken to increase weeding efficiency and reduce the drudgery in weeding and mulching. A line-to-line distance of 20 cm, the operation is push-pull, and field operating condition at 2 - 4 cm standing water (for softening the field) was the designed hypothesis. The weeder consists of a skid/float, float holder, float adjuster, main body frame, rotor, axel, bush, rotor holder, rotor holder adjuster, handle, handle griper, handle holder, handle height adjuster, nut, bolt, etc. The designed weeder was fabricated using MS sheet, MS pipe, MS flat bar, MS nut-bolt, etc. When the rotors perform back and forth, the weeder’s two conical rotors with six plain blades and six serrated blades work together to uproot and bury the weeds. It also contains a 2 mm thick float assembly with a precise angle of 22 degrees. Weeds are uprooted by the weeder’s blades and buried in the muddy soil. It causes topsoil disturbance and enhances aeration. The weeding efficiency and capacity of the conical weeder were 81.92% and 0.0203 ha/h respectively. With a push-pull operation, the weeder can uproot and bury the weeds in a single row at a time. The pushing force and weight of weeder were 43.42 N and 5.6 kg respectively. Farmers can use this weeder to increase their comfort and reduce the drudgery associated with weeding and mulching in their fields.
文摘Buckling and postbuckling characteristics of laminated graphene-enhanced composite(GEC)truncated conical shells exposed to torsion under temperature conditions using finite element method(FEM)simulation are presented in this study.In the thickness direction,the GEC layers of the conical shell are ordered in a piece-wise arrangement of functionally graded(FG)distribution,with each layer containing a variable volume fraction for graphene reinforcement.To calculate the properties of temperaturedependent material of GEC layers,the extended Halpin-Tsai micromechanical framework is used.The FEM model is verified via comparing the current results obtained with the theoretical estimates for homogeneous,laminated cylindrical,and conical shells,the FEM model is validated.The computational results show that a piece-wise FG graphene volume fraction distribution can improve the torque of critical buckling and torsional postbuckling strength.Also,the geometric parameters have a critical impact on the stability of the conical shell.However,a temperature rise can reduce the crucial torsional buckling torque as well as the GEC laminated truncated conical shell’s postbuckling strength.
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Supported by National Key Research and Development Program(No.20220101172JC).
文摘The vibrator plate is the link between the vibroseis vehicle and the earth,as well as the core com-ponent of the vibrator vehicle.In this paper,the coupling effect between the vibrator plate and the earth is an-alyzed from two aspects of reaction tooth arrangement and reaction tooth conical angle,and three groups of experimental models are optimized and designed.The model construction and numerical analysis of the shear wave vibroseis vibrator plate are carried out with ANSYS software.The motion law between the vibration plate and the earth at work was studied,the strain energy of the three experimental models in operation,the maximum displacement of particle at the same position and other reference indices were compared and ana-lyzed,with 28 conical reaction teeth were arranged on both sides.The coupling effect between the vibration plate and the earth was best when the tooth angle was 60°.Compared with the toothless vibration plate,the energy efficiency is improved by about 20%,and the coupling effect between the vibrator plate and the earth is effectively enhanced.It is found that the coupling effect is enhanced through increasing the number of reac-tion teeth of the vibration plate by increasing the coupling area between the vibration plate and the earth.
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.
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.
基金supported by the National Natural Science Foundation of China(Grant No.50775081)the National High Technology Research and Development Program of China(863 Program,Grant No.2006AA09Z238)
文摘Water jet thruster, which is a marine system that creates a jet of water for propulsion, has several advantages such as low noise, good anti-cavitation characteristics and maneuvering characteristics. The reaction thrust characteristics of water jet for conical nozzles directly determine the speed of autonomous underwater vehicles (AUV). Theoretical, numerical and experimental studies have been, carried out to investigate the effects of the nozzle geometries as well as inlet conditions on the reaction thrust of water jet in this paper. The experimental results show that: 1) the reaction thrust is proportional to inlet pressure, the square of flow rate and 2/3 power exponent of input power; 2) the diameter of cylinder column for conical nozzle has great influence on the reaction thrust characteristics; 3) the best values of the half cone angle and the cylinder column length exist to make the reaction thrust coefficient to reach the maximum under the same inlet conditions. Those provide a basis for nozzles design and have significant value, especially for developing high performance and efficiency water jet propulsion unit.
文摘New plasticity solutions to the drained stability of conical slopes in homogeneous cohesive-frictional soils were investigated by axisymmetric finite element limit analysis. Three parameters were studied,i.e. excavated height ratios, slope inclination angles, and soil friction angles. The influences of these parameters on the stability factor and predicted failure mechanism of conical slopes were discussed. A new design equation developed from a nonlinear regression of the lower bound solution was proposed for drained stability analyses of a conical slope in practice. Numerical examples were given to demonstrate a practical application of the proposed equation to stability evaluations of conical slopes with both associated and non-associated flow rules.
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Project supported by the National Natural Science Foundation of China (Nos. 50335030, 50505033 and 50575171)National Basic Research Program of China (No. 2005CB724106)Doctoral Program Foundation of University of China(No. 20040698026)
文摘Based on B-spline wavelet on the interval (BSWI), two classes of truncated conical shell elements were constructed to solve axisymmetric problems, i.e. BSWI thin truncated conical shell element and BSWI moderately thick truncated conical shell element with independent slopedeformation interpolation. In the construction of wavelet-based element, instead of traditional polynomial interpolation, the scaling functions of BSWI were employed to form the shape functions through the constructed elemental transformation matrix, and then construct BSWI element via the variational principle. Unlike the process of direct wavelets adding in the wavelet Galerkin method, the elemental displacement field represented by the coefficients of wavelets expansion was transformed into edges and internal modes via the constructed transformation matrix. BSWI element combines the accuracy of B-spline function approximation and various wavelet-based elements for structural analysis. Some static and dynamic numerical examples of conical shells were studied to demonstrate the present element with higher efficiency and precision than the traditional element.
文摘The problem of ice induced vibration is common to ocean engineering of cold region countries. To study the ice induced vibration of a compliant conical structure, a series of model tests have been performed and some breakthrough progresses made. The ice sheet before the compliant conical structure is found to fail by two-time breaking in the tests. The process of two-time breaking behaves in two modes, and the general control of the ice and structural conditions determine the mode in which the ice force would behave. Two dynamic ice force functions are established respectively for the two modes of two-time breaking process in this paper. The numerical simulation results are in good agreement with the measured results, indicating that the dynamic ice force functions given in this paper can fully reflect the real situation of the dynamic ice force on a compliant conical structure.
基金supported by the Science and Technology Development Fund(Macao S.A.R.),Grant FDCT/016/2013/A1the Project MYRG2015-00235-FST of the University of Macao
文摘We prove that, under a semi-ampleness type assumption on the twisted canonical line bundle, the conical Kahler-Ricci flow on a minimal elliptic Kahler surface converges in the sense of currents to a generalized conical Kahler-Einstein on its canonical model. Moreover, the convergence takes place smoothly outside the singular fibers and the chosen divisor.
基金supported by National Natural Science Foundation of China(Grant No.50645032)Zhejiang Provincial Natural Science Foundation of China(Grant No.Y105686)Ningbo Municipal Natural Science Foundation of China(Grant No.2008A610038)
文摘Conical cam mechanism has been widely used in modern machinery and equipment.However,the commonly used planar expansion methods for the design of spatial cam contour produce significant errors,because these methods incorrectly use the distance from the axis of the follower to the main conical cam to replace the corresponding arc length on the conical cam.HSIEH,et al,used analytical methods to achieve higher accuracy,but these analytical methods have their own drawbacks since they are too complicated for practical use.Through the analysis of the errors created during the generation of conical cam contour using the existing expansion methods,this paper proposes to include diverge angle in the calculation of conical cam rotation angle in the equation of conical cam contour expansion.This correction eliminates the error generated by the commonly used methods.Based on the expression of the follower's 3D trajectory and the spatial geometry of conical cam,this paper has deduced the planar polar curve equation for determining polar coordinates for the curve of planar expansion outline.Furthermore,this paper provides an example of conical cam contour design based on sinusoidal acceleration variation.According to polar coordinates and the movement of curve equation function expression,this paper applies MATLAB software to solve coordinates for the cam expansion curve and uses AutoCAD software to generate conical cam expansion contour that meets the requirement of the law of motion.The proposed method provides a design process that is simple,intuitive and easy to master and implement.It also avoids the design error in the traditional methods for generating contour of conical cam with oscillating follower that requires high precision.
基金supported by the Specialized Research Fund for Doctoral Program of Higher Education,SPFDP-200806990003the Foundation for Fundamental Research of the Northwestern Polytechnical University,NPU-FFR-W018102
文摘Duty-cycle modulation alternately blowing from two opposite-facing plasma actu- ators on the leeward surface near the apex of a cone with a 10° semi-apex angle is adopted to control mean lateral force and moment, and the flow control mechanisms are presented. Pressure distributions over the forebody of the cone are measured by steady pressure tappings. The experiments are performed in a 3.0×1.6 m open-circuit wind tunnel at a wind speed of 20 m/s, a 45° angle of attack and a Reynolds number of 2×10^5, based on the diameter of the base of the cone. Almost linearly proportional control of the lateral forces and moments over a slender conical forebody at a high angle of attack has been demonstrated by employing a pair of single dielectric barrier discharge plasma actuators near the apex of the cone, combined with a duty-cycle tech- nique. The pressure distribution measurements indicate that the hi-stable vortex pattern appears to be shifted in the opposite direction when the port or starboard actuator is activated, while the other is kept off during the test. It is shown that the reduced pulse-repetition frequency based on the local diameter at the plasma actuator equal to one yields the highest effectiveness among the cases considered.
基金Supported by State Administration of Science Technology and Industry for National Defense,China(Grant No.JSJC2013204B301)
文摘In order to solve the problem of broadband field probes calibration with only selected discrete frequencies above 1 GHz, a sweep-frequency calibration technology based on a coaxial conical(co-conical) cell is researched. Existing research is only qualitative because of the complexity of theoretical calculations. For designing a high performance cell, a mathematic model of high-order modes transmission is built according to the geometrical construction of co-conical. The associated Legendre control functions of high-order modes are calculated by using recursion methodology and the numerical calculation roots are presented with different half angles of inner and outer conductor. Relationship between roots and high-order modes transmission is analyzed, when the half angles of inner conductor and outer conductor are θ1=1.5136° and θ2=8° respectively, the co-conical cell has better performance for fewer transmitting high-order modes. The propagation process of the first three transmitting modes wave is simulated in CST-MWS software from the same structured co-conical. The simulation plots show that transmission of high-order modes appears with electromagnetic wave reflection, then different high-order mode transmission has different cut-off region and each cut-off region is determined by its cut-off wavelength. This paper presents numerical calculation data and theoretical analysis to design key structural parameters for the co-conical transverse electromagnetic wave cell(co-conical TEM cell).
基金Projects(59375211,10771178,10676031) supported by the National Natural Science Foundation of ChinaProject(07A068) supported by the Key Project of Hunan Education CommissionProject(2005CB321702) supported by the National Key Basic Research Program of China
文摘The internal turbulent flow in conical diffuser is a very complicated adverse pressure gradient flow.DLR k-ε turbulence model was adopted to study it.The every terms of the Laplace operator in DLR k-ε turbulence model and pressure Poisson equation were discretized by upwind difference scheme.A new full implicit difference scheme of 5-point was constructed by using finite volume method and finite difference method.A large sparse matrix with five diagonals was formed and was stored by three arrays of one dimension in a compressed mode.General iterative methods do not work wel1 with large sparse matrix.With algebraic multigrid method(AMG),linear algebraic system of equations was solved and the precision was set at 10-6.The computation results were compared with the experimental results.The results show that the computation results have a good agreement with the experiment data.The precision of computational results and numerical simulation efficiency are greatly improved.
基金Biomedical Textile Materials Science and Technology(111 Project),China(No.B07024)
文摘Conical vascular tubes are of strong demand owing to their formed shape and excellent characters to mimic human blood vessels. In this study,the automatic shuttle loom and computer aided design( CAD) system were customized to prepare a conical vascular graft. Meanwhile, the weaving principle of a conical vascular graft was identified in terms of the lift-drop front rest,and the geometrical relations were established among the cloth fell,front rest and back rest. Also,the change of weft density from the liftdrop motion of the front rest was analyzed,and a strategy was established to compensate the offset of weft density by changing the taken-up length. Afterwards,the proposed weaving principles were demonstrated by weaving a conical vascular graft on the customized shuttle loom.
基金supported by the Vietnam National Foundation for Science and Technology Development(No.107.02-2015.11)
文摘An analytical solution for buckling of an eccentrically stiffened sandwich truncated conical shell is investigated. The shell consists of two functionally graded material (FGM) coating layers and a core layer which are metal or ceramic subjected to an axial compressive load and an external uniform pressure. Shells are reinforced by stringers and rings, in which the material properties of shells and stiffeners are graded in the thickness direction following a general sigmoid law distribution. Two models of coated shell-stiffener arrangements are investigated. The change of the spacing between stringers in the meridional direction is taken into account. A couple set of three-variable- coefficient partial differential equations in terms of displacement components are solved by the Galerkin method. A closed-form expression for determining the buckling load is obtained. The numerical examples are presented and compared with previous works.