Vibration mode shape description of an aero-engine casing structure using Zernike moment descriptor(ZMD) was introduced in this paper.The mode shapes of the aero-engine casing structure can be decomposed as a linear c...Vibration mode shape description of an aero-engine casing structure using Zernike moment descriptor(ZMD) was introduced in this paper.The mode shapes of the aero-engine casing structure can be decomposed as a linear combination of a series of Zernike polynomials,with the feature of each Zernike polynomial reflecting a part of characteristic of mode shapes,based on Zernike moment transformation.Meanwhile,the reconstruction of mode shapes with ZMD was explored and its ability to filtering the noise contaminated in the mode shapes was studied.Simulation of the aero-engine casing structure indicated the advantage of this method to depict the mode shapes of a symmetric structure.Results demonstrate that the Zernike moment description of the mode shapes can effectively describe the double modes in the symmetric structure and also has the ability to remove or significantly reduce the influence of noise in the mode shapes.Such feature shows great practical value for further research on the correlation,model updating and model validation of the symmetric structure's finite element model.展开更多
The existence of rolling deformation area in the rolling mill system is the main characteristic which dis- tinguishes the other machinery. In order to analyze the dynamic property of roll system＇s flexural deformatio...The existence of rolling deformation area in the rolling mill system is the main characteristic which dis- tinguishes the other machinery. In order to analyze the dynamic property of roll system＇s flexural deformation, it is necessary to consider the transverse periodic movement of stock in the rolling deformation area which is caused by the flexural deformation movement of roll system simul- taneously. Therefore, the displacement field of roll system and flow of metal in the deformation area is described by kinematic analysis in the dynamic system. Through intro- ducing the lateral displacement function of metal in the deformation area, the dynamic variation of per unit width rolling force can be determined at the same time. Then the coupling law caused by the co-effect of rigid movement and flexural deformation of the system structural elements is determined. Furthermore, a multi-parameter coupling dynamic model of the roll system and stock is established by the principle of virtual work. More explicitly, the cou- pled motion modal analysis was made for the roll system. Meanwhile, the analytical solutions for the flexural defor- mation movement＇s mode shape functions of rolls are discussed. In addition, the dynamic characteristic of the lateral flow of metal in the rolling deformation area has been analyzed at the same time. The establishment ofdynamic lateral displacement function of metal in the deformation area makes the foundation for analyzing the coupling law between roll system and rolling deformation area, and provides a theoretical basis for the realization of the dynamic shape control of steel strip.展开更多
This paper proposes an approach to extract the mode shapes of beam-like structures from the dynamic response of a moving mass. When a mass passes through a beam containing several artificially installed humps, its ver...This paper proposes an approach to extract the mode shapes of beam-like structures from the dynamic response of a moving mass. When a mass passes through a beam containing several artificially installed humps, its vertical acceleration can be recorded. After applying fast Fourier transformation to the dynamic response, one can extract the mode shapes of the beam. The surface roughness was neglected compared to the humps and its adverse effect on the extraction was reduced. The passing mass performs as both “exciter” and “massage receiver”;therefore, this method requires only one single accelerometer, making it more convenient and time saving in practice. Moreover, to estimate the possible error in extracting mode shapes, a wavenumber domain filtering technique is used to reconstruct the general profiles of mode shapes. Experimental validation of this approach in laboratory scale was conducted. The experimental results show that the proposed method performs well in extracting lower order mode shapes. It should also be noted that the passing mass can not have a very high velocity (e.g. 80 mm/s), otherwise the mass may jump and separate from the beam, and the proposed method may fail to identify mode shapes.展开更多
A new method for structural damage identification is presented based on perturbations of curvature mode shape and frequency.Firstly,the structure's mass and stiffness matrices are expressed as functions of its ele...A new method for structural damage identification is presented based on perturbations of curvature mode shape and frequency.Firstly,the structure's mass and stiffness matrices are expressed as functions of its elements'physical parameters,which reflect their damage states. According to differences in the curvature mode shape of the structure in undamaged and damaged states,possible damage equations and determined damage equations are established and used to solve for the elements'damage parameters.Then,to ensure the accuracy of the recognition result,a reasonable solution is substituted into a damage-checking equation based on the change of frequency of the damaged structure.Numerical examples are used to show that,to identify the damage,only one order mode needs to be tested.When the degree of damage is low, first-order perturbation equations can be used to recognize the damage with sufficient accuracy. If the extent of the damage is high,second-order perturbation equations can be used to provide more accurate identification results.展开更多
In this paper, we try to use the coating of effective electrode surface and change the direction of polarization to design the mode shape piezoelectric motors of the first three modes. We also com-pare the gain of the...In this paper, we try to use the coating of effective electrode surface and change the direction of polarization to design the mode shape piezoelectric motors of the first three modes. We also com-pare the gain of the mode shape piezoelectric motors with respect to the normal shape piezoelectric motor, including rotational speed, loading ability, torque, phase angle conversion and efficiency. According to the results of theoretical and simulation analysis, we have found that the gain of the mode shape piezoelectric stators are larger than the normal shape piezoelectric stator on average. According to the results of experiments, we found that the gain of the rotational speed, loading ability, torque, driving phase angle conversion and efficiency of the mode shape (MS1 - 3) piezoelectric motors are higher than the normal shape piezoelectric motor (NS) under driving condition of the second vibration mode. Also, the gain of the rotational speed and loading ability of the mode shape 2 (MS2) piezoelectric motor are higher than other shapes piezoelectric motors (NS, MS1 and MS3) under driving condition of the second vibration mode. The used maximum rotational speed of the mode shape 2 (MS2) piezoelectric motor is up to 946 rpm under conditions of 180 Vp-p driving voltage, 10.7 kHz driving frequency, 0o driving phase angle and 13.0 gw net weight. The maximum loading ability and torque of the mode shape 2 (MS2) piezoelectric motor is respectively 451 gw and 0.91 mkgw-m under conditions of 180 Vp-p driving voltage, 10.7 kHz driving frequency, 0o driving phase angle and 173 rpm rotational speed. And the gain of efficiency (output power) and maximum loading ability (torque) of the mode shape 2 (MS2) piezoelectric motor are respectively 2.28 and 1.54 with respect to the normal shape piezoelectric motor under conditions of 180 Vp-p driving voltage, 10.7 kHz driving frequency and 0o driving phase angle. According to the results of the experiments, we have finally found that the piezoelectric motors (NS and MS1 - 3) can be driven only by the second vibration mode because the stator can produce elliptical motion and allows the rotor to generate orientation rotation. However, the first vibration mode can allow the rotor to be rotated very fast but it can’t make the rotation of the rotor orientation. Furthermore, we also found that the rotor can’t rotate by the third vibration mode because its vibration energy is absorbed by the structure itself, so causing the rotor stagnation.展开更多
A temperature-insensitive sensor for glucose brix measurement based on compact spindle-shaped structure with two-mode fiber(TMF) is proposed. Due to the bending of optical fiber caused by flame baking, some of the lig...A temperature-insensitive sensor for glucose brix measurement based on compact spindle-shaped structure with two-mode fiber(TMF) is proposed. Due to the bending of optical fiber caused by flame baking, some of the light energy transmitted in the core leaks into the cladding area as an evanescent wave, which excites the higher-order cladding mode of the sensor. The experimental results show that when the length of TMF is 3 cm and the bending diameter is 4 mm, the maximum glucose brix sensitivity of the sensor is 0.368 nm/% from 0 to 21%. The sensor is insensitive to temperature from 10 °C to 50 °C, which can avoid the problem of temperature cross-sensitivity. A compact spindle-shaped sensor is a potential effective sensor with a simple structure, easy fabrication and low cost. The sensor can be used to detect glucose content in areas such as crops quality assessment and the research of pharmacy and bioengineering.展开更多
We numerically investigate the formation and interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser. Based on a lumped model, the parabolic-shaped pulse pair is obtained by contro...We numerically investigate the formation and interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser. Based on a lumped model, the parabolic-shaped pulse pair is obtained by controlling the intercavity average dispersion and gain saturation energy, Moreover, pulse repulsive and attractive motion are also achieved with different pulse separations. Simulation results show that the phase shift plays an important role in pulse interaction, and the interaction is determined by the inter-cavity average dispersion and gain saturation energy, i.e., the strength of the interaction is proportional to the gain saturation energy, a stronger gain saturation energy will result in a higher interaction intensity. On the contrary, the increase of the inter-cavity dispersion will counterbalance some interaction force. The results also show that the interaction of a parabolic-shaped pulse pair has a larger interaction distance compared to conventional solitons.展开更多
Compared to traditional mode shape identification methods such as eigensystem realization algorithm(ERA),this article proposes a mode shape identification method based on estimated residues of measured data and the th...Compared to traditional mode shape identification methods such as eigensystem realization algorithm(ERA),this article proposes a mode shape identification method based on estimated residues of measured data and the theoretical relationship between the estimated residues and the mode shapes from the state space model is obtained by defining a coefficient matrix.A mass-spring model with five degrees of freedom(DOFs) is utilized to demonstrate the approach.The numerical results indicate that the estimated residues are the mode shapes of structures,but with a coefficient matrix to maintain consistency with the mode shapes from the ERA.Using MATLAB a complicated numerical jacket platform is built to further study the proposed method.The results show that mode shapes consistent with those from the ERA could be obtained by taking the defined coefficient matrix into account,which is also demonstrated by a physical beam model that was built at Ocean University of China.展开更多
The effects of the shape of a nanowire terminus on the excited surface plasmon polariton （SPP） modes are investigated. The conical terminus and terminus cut at a certain angle are studied. For the first time, the qu...The effects of the shape of a nanowire terminus on the excited surface plasmon polariton （SPP） modes are investigated. The conical terminus and terminus cut at a certain angle are studied. For the first time, the quantitative mode decompositions are carried out to derive the full information about excited SPP modes. It is demonstrated that tuning the shape of the terminus provides an effective method to control the composition of excited SPP modes on metal nanowires. It is especially found that some important patterns, such as the pure TM0 mode and the superposition of TM0 and HE＋1 or HE-1 modes, can be generated by some specific shapes of the terminus, whereas there is no way to produce these patterns using flat-end nanowires.展开更多
Elastic critical buckling load of a column depends on various parameters,such as boundary conditions,material,and crosssection geometry.The main purpose of this work is to present a new method for investigating the bu...Elastic critical buckling load of a column depends on various parameters,such as boundary conditions,material,and crosssection geometry.The main purpose of this work is to present a new method for investigating the buckling load of tapered columns subjected to axial force.The proposed method is based on modified buckling mode shape of tapered structure and perturbation theory.The mode shape of the damaged structure can be expressed as a linear combination of mode shapes of the intact structure.Variations in length in piecewise form can be positive or negative.The method can be used for single-span and continuous columns.Comparison of results with those of finite element and Timoshenko methods shows the high accuracy and efficiency of the proposed method for detecting buckling load.展开更多
An exact analysis of the modes Ⅱ and Ⅲ problems of a penny- shaped crack in a transversely isotropic piezoelectric medium is performed in this paper.The potential theory method is employed based on the general solut...An exact analysis of the modes Ⅱ and Ⅲ problems of a penny- shaped crack in a transversely isotropic piezoelectric medium is performed in this paper.The potential theory method is employed based on the general solution of three-dimensional piezoelasticity and the four harmonics involved are represented by one complex potential.Previous results in potential theory are then utilized to obtain the exact solution that is expressed in terms of elementary functions.Comparison is made between the current results with those published and good agreement is obtained.展开更多
In this paper, we will try to find a universal theoretical model and approximate solutions which can be applied to both mode shape and normal shape actuators and sensors, and which can be predicted the gain of the fir...In this paper, we will try to find a universal theoretical model and approximate solutions which can be applied to both mode shape and normal shape actuators and sensors, and which can be predicted the gain of the first three modes of the mode shape and normal shape actuators and sensors, finally through computer simulation analysis to validate. In order to prove the feasibility of the theory and as well as convenient to use on the electro-mechanical engineering, we will try to simplify the three-dimension structure problem into an one-dimension structure problem. Furthermore we will design one kind of bimorph type piezoelectric cantilever beam, so that it can be used as with the actuator and sensor simultaneously, but also conducive to the theory and simulation analysis. As for the simulation analysis, we will use the ANSYS code.展开更多
In this paper, we want to make a new type linear piezoelectric motor by mode shape coating or effective electrode surface coating. The mode shape is derived from the mechanical boundary conditions of the linear piezoe...In this paper, we want to make a new type linear piezoelectric motor by mode shape coating or effective electrode surface coating. The mode shape is derived from the mechanical boundary conditions of the linear piezoelectric motor. We only have access to the first three modes of formas, the effective electrode surface coating basis, as well as with the linear piezoelectric motor of normal shape do comparison. Next, we will inspect their gain or axial velocity through theoretical analysis, simulation and experiment. According to the results of the theoretical analysis, we have found that the gain or axial velocity of the linear piezoelectric motors of mode shape is much larger than the linear piezoelectric motors of normal shape. However, according to the results of simulation and experiments, we have found that the gain or axial velocity of the linear piezoelectric motors of mode shape is much greater than the linear piezoelectric motors of normal shape, which is about 1.2 to 1.4 times. The linear piezoelectric motor of mode shape 3 has the fastest axial velocity, which is about -48 mm/s and 48 mm/s under conditions of 180 Vp-p driving voltage, 21.2 kHz driving frequency (the third vibration modal), 25 gw loading and the position of loading or mass at x = 5 mm & 45 mm respectively. And its axial velocity is about 1.4 times the linear piezoelectric motor of normal shape under the same conditions. Overall, the mode shape coating helps to enhance the gain or axial velocity of the linear piezoelectric motor.展开更多
An experimental program was undertaken to test the feasibility to detect the occurrence of structural damage using a modified mode shape difference technique. The vibration response of a steel beam fixed at one end an...An experimental program was undertaken to test the feasibility to detect the occurrence of structural damage using a modified mode shape difference technique. The vibration response of a steel beam fixed at one end and hinged at the other was obtained for the intact and damage conditions. Modal analysis was performed to extract the frequencies and mode shapes. The method shows a good potential in detection of occurrence and location of damage.展开更多
Methods for scaling mode shapes determined by operational modal analysis(OMA)have been extensively investigated in the last years.A recent addition to the range of methods for scaling OMA mode shapes is the so-called ...Methods for scaling mode shapes determined by operational modal analysis(OMA)have been extensively investigated in the last years.A recent addition to the range of methods for scaling OMA mode shapes is the so-called OMAH technique,which is based on exciting the structure by harmonic forces applied by an actuator.By applying harmonic forces in at least one degree-of-freedom(DOF),and measuring the response in at least one response DOF,while using at least as many frequencies as the number of mode shapes to be scaled,the mode shape scaling(modal mass)of all modes of interest may be determined.In previous publications on the method the authors have proven that the technique is easy and robust to apply to both small scale and large scale structures.Also,it has been shown that the technique is capable of scaling highly coupled modes by using an extended multiple reference formulation.The present paper summarizes the theory of the OMAH method and gives recommendations of how to implement the method for best results.It is pointed out,as has been shown in previous papers,that the accuracy of the mode scaling is increased by using more than one response DOF,and by selecting DOFs with high mode shape coefficients.To determine the harmonic force and responses,it is recommended to use the three-parameter sine fit method.It is shown that by using this method,the measurement time can be kept short by using high sampling frequency and bandpass filtering whereas spectrum based methods require long measurement times.This means that even for structures with low natural frequencies,the extra measurement time for scaling the mode shapes can be kept relatively short.展开更多
Dipole coupled nanomagnets controlled by the static Zeeman field can form various magnetic logic interconnects.However, the corner wire interconnect is often unreliable and error-prone at room temperature. In this stu...Dipole coupled nanomagnets controlled by the static Zeeman field can form various magnetic logic interconnects.However, the corner wire interconnect is often unreliable and error-prone at room temperature. In this study, we address this problem by making it into a reliable type with trapezoid-shaped nanomagnets, the shape anisotropy of which helps to offer the robustness. The building method of the proposed corner wire interconnect is discussed,and both its static and dynamic magnetization properties are investigated. Static micromagnetic simulation demonstrates that it can work correctly and reliably. Dynamic response results are reached by imposing an ac microwave field on the proposed corner wire. It is found that strong ferromagnetic resonance absorption appears at a low frequency. With the help of a very small ac field with the peak resonance frequency, the required static Zeeman field to switch the corner wire is significantly decreased by ~21 m T. This novel interconnect would pave the way for the realization of reliable and low power nanomagnetic logic circuits.展开更多
The random decrement technique is an averaging technique that can be used to extract the free decay response of the structure from its random stationary vibratory response. The free decay response can then be used to ...The random decrement technique is an averaging technique that can be used to extract the free decay response of the structure from its random stationary vibratory response. The free decay response can then be used to identify the vibratory characteristics of the structure. The main advantage of the technique is that the identification of the parameters of the structure is achieved without previous knowledge of the excitation forces. This paper extends the random decrement technique to obtain the mode shapes of the structure using the concept of a multichannel random decrement technique （MCRD）. This technique is based on extracting simultaneous random decrement records from measurements made at several points on the structure. The method is very efficient and simple. Numerical examples are solved and compared with the exact mode shapes extracted using classical modal analysis. An excellent agreement between the extracted modes shapes using the MCRD and those obtained from the classical modal analysis techniques is achieved. The vibration of an offshore structure excited by white noise excitation is used to illustrate the method.展开更多
This work introduces special states for light in multimode fibers featuring strongly enhanced or reduced correlations be-tween output fields in the presence of environmental temperature fluctuations.Using experimental...This work introduces special states for light in multimode fibers featuring strongly enhanced or reduced correlations be-tween output fields in the presence of environmental temperature fluctuations.Using experimentally measured multi-tem-perature transmission matrix,a set of temperature principal modes that exhibit resilience to disturbances caused by tem-perature fluctuations can be generated.Reversing this concept also allows the construction of temperature anti-principal modes,with output profiles more susceptible to temperature influences than the unmodulated wavefront.Despite changes in the length of the multimode fiber within the temperature-fluctuating region,the proposed approach remains capable of robustly controlling the temperature response within the fiber.To illustrate the practicality of the proposed spe-cial state,a learning-empowered fiber specklegram temperature sensor based on temperature anti-principal mode sensi-tization is proposed.This sensor exhibits outstanding superiority over traditional approaches in terms of resolution and accuracy.These novel states are anticipated to have wide-ranging applications in fiber communication,sensing,imaging,and spectroscopy,and serve as a source of inspiration for the discovery of other novel states.展开更多
This paper presents a biosensor utilizing a whispering gallery mode(WGM)resonator characterized by azimuthal symmetry and crescent-shaped coatings of silver.The study investigates the impact of the coupling gap on the...This paper presents a biosensor utilizing a whispering gallery mode(WGM)resonator characterized by azimuthal symmetry and crescent-shaped coatings of silver.The study investigates the impact of the coupling gap on the extinction ratio and Q-factor of the setup.The resonator is coated with silver in crescent shapes,ranging from 40 nm to 65 nm in thickness.Coupling is achieved with a silica waveguide,simulating the tapered fiber coupling method.Notably,the resonator exhibits a maximum sensitivity of 220 nm/RIU when coated with 55-nm-thick silver in conjunction with a 4-nm-thick layer of thiol-tethered deoxyribonucleic acid(DNA).This biosensor holds promise for biomolecule detection applications.展开更多
基金Supported by Research Fund for the Doctoral Program of Higher Education of China(20093218110008)The SRF for ROCS,SPM(No.R0861-21)+1 种基金Jiangsu Research Foundation of Talented Scholars in Six Fields(No.P0951-021)The Nanjing University of Aeronautics and Astronautics Postgraduate Innovation Fund
文摘Vibration mode shape description of an aero-engine casing structure using Zernike moment descriptor(ZMD) was introduced in this paper.The mode shapes of the aero-engine casing structure can be decomposed as a linear combination of a series of Zernike polynomials,with the feature of each Zernike polynomial reflecting a part of characteristic of mode shapes,based on Zernike moment transformation.Meanwhile,the reconstruction of mode shapes with ZMD was explored and its ability to filtering the noise contaminated in the mode shapes was studied.Simulation of the aero-engine casing structure indicated the advantage of this method to depict the mode shapes of a symmetric structure.Results demonstrate that the Zernike moment description of the mode shapes can effectively describe the double modes in the symmetric structure and also has the ability to remove or significantly reduce the influence of noise in the mode shapes.Such feature shows great practical value for further research on the correlation,model updating and model validation of the symmetric structure's finite element model.
基金Supported by National Natural Science Foundation of China(Grant No.51375424)
文摘The existence of rolling deformation area in the rolling mill system is the main characteristic which dis- tinguishes the other machinery. In order to analyze the dynamic property of roll system＇s flexural deformation, it is necessary to consider the transverse periodic movement of stock in the rolling deformation area which is caused by the flexural deformation movement of roll system simul- taneously. Therefore, the displacement field of roll system and flow of metal in the deformation area is described by kinematic analysis in the dynamic system. Through intro- ducing the lateral displacement function of metal in the deformation area, the dynamic variation of per unit width rolling force can be determined at the same time. Then the coupling law caused by the co-effect of rigid movement and flexural deformation of the system structural elements is determined. Furthermore, a multi-parameter coupling dynamic model of the roll system and stock is established by the principle of virtual work. More explicitly, the cou- pled motion modal analysis was made for the roll system. Meanwhile, the analytical solutions for the flexural defor- mation movement＇s mode shape functions of rolls are discussed. In addition, the dynamic characteristic of the lateral flow of metal in the rolling deformation area has been analyzed at the same time. The establishment ofdynamic lateral displacement function of metal in the deformation area makes the foundation for analyzing the coupling law between roll system and rolling deformation area, and provides a theoretical basis for the realization of the dynamic shape control of steel strip.
文摘This paper proposes an approach to extract the mode shapes of beam-like structures from the dynamic response of a moving mass. When a mass passes through a beam containing several artificially installed humps, its vertical acceleration can be recorded. After applying fast Fourier transformation to the dynamic response, one can extract the mode shapes of the beam. The surface roughness was neglected compared to the humps and its adverse effect on the extraction was reduced. The passing mass performs as both “exciter” and “massage receiver”;therefore, this method requires only one single accelerometer, making it more convenient and time saving in practice. Moreover, to estimate the possible error in extracting mode shapes, a wavenumber domain filtering technique is used to reconstruct the general profiles of mode shapes. Experimental validation of this approach in laboratory scale was conducted. The experimental results show that the proposed method performs well in extracting lower order mode shapes. It should also be noted that the passing mass can not have a very high velocity (e.g. 80 mm/s), otherwise the mass may jump and separate from the beam, and the proposed method may fail to identify mode shapes.
基金National Natural Science Foundation of China (No.11402090)Key Scientific Research Projects in Colleges and Universities of Henan Province (No.17B130001,No.19A560014)Science and Technology Project of Henan Province (No.182102310890).
文摘A new method for structural damage identification is presented based on perturbations of curvature mode shape and frequency.Firstly,the structure's mass and stiffness matrices are expressed as functions of its elements'physical parameters,which reflect their damage states. According to differences in the curvature mode shape of the structure in undamaged and damaged states,possible damage equations and determined damage equations are established and used to solve for the elements'damage parameters.Then,to ensure the accuracy of the recognition result,a reasonable solution is substituted into a damage-checking equation based on the change of frequency of the damaged structure.Numerical examples are used to show that,to identify the damage,only one order mode needs to be tested.When the degree of damage is low, first-order perturbation equations can be used to recognize the damage with sufficient accuracy. If the extent of the damage is high,second-order perturbation equations can be used to provide more accurate identification results.
文摘In this paper, we try to use the coating of effective electrode surface and change the direction of polarization to design the mode shape piezoelectric motors of the first three modes. We also com-pare the gain of the mode shape piezoelectric motors with respect to the normal shape piezoelectric motor, including rotational speed, loading ability, torque, phase angle conversion and efficiency. According to the results of theoretical and simulation analysis, we have found that the gain of the mode shape piezoelectric stators are larger than the normal shape piezoelectric stator on average. According to the results of experiments, we found that the gain of the rotational speed, loading ability, torque, driving phase angle conversion and efficiency of the mode shape (MS1 - 3) piezoelectric motors are higher than the normal shape piezoelectric motor (NS) under driving condition of the second vibration mode. Also, the gain of the rotational speed and loading ability of the mode shape 2 (MS2) piezoelectric motor are higher than other shapes piezoelectric motors (NS, MS1 and MS3) under driving condition of the second vibration mode. The used maximum rotational speed of the mode shape 2 (MS2) piezoelectric motor is up to 946 rpm under conditions of 180 Vp-p driving voltage, 10.7 kHz driving frequency, 0o driving phase angle and 13.0 gw net weight. The maximum loading ability and torque of the mode shape 2 (MS2) piezoelectric motor is respectively 451 gw and 0.91 mkgw-m under conditions of 180 Vp-p driving voltage, 10.7 kHz driving frequency, 0o driving phase angle and 173 rpm rotational speed. And the gain of efficiency (output power) and maximum loading ability (torque) of the mode shape 2 (MS2) piezoelectric motor are respectively 2.28 and 1.54 with respect to the normal shape piezoelectric motor under conditions of 180 Vp-p driving voltage, 10.7 kHz driving frequency and 0o driving phase angle. According to the results of the experiments, we have finally found that the piezoelectric motors (NS and MS1 - 3) can be driven only by the second vibration mode because the stator can produce elliptical motion and allows the rotor to generate orientation rotation. However, the first vibration mode can allow the rotor to be rotated very fast but it can’t make the rotation of the rotor orientation. Furthermore, we also found that the rotor can’t rotate by the third vibration mode because its vibration energy is absorbed by the structure itself, so causing the rotor stagnation.
基金supported by the National Natural Science Foundation of China(No.62003237)the Tianjin Enterprise Technology Commissioner Project(No.20YDTPJC01700)+1 种基金the State Key Laboratory of Applied Optics(No.SKLA02020001A02)the Tianjin Municipal Education Commission Scientific Research Project(No.2017ZD15)。
文摘A temperature-insensitive sensor for glucose brix measurement based on compact spindle-shaped structure with two-mode fiber(TMF) is proposed. Due to the bending of optical fiber caused by flame baking, some of the light energy transmitted in the core leaks into the cladding area as an evanescent wave, which excites the higher-order cladding mode of the sensor. The experimental results show that when the length of TMF is 3 cm and the bending diameter is 4 mm, the maximum glucose brix sensitivity of the sensor is 0.368 nm/% from 0 to 21%. The sensor is insensitive to temperature from 10 °C to 50 °C, which can avoid the problem of temperature cross-sensitivity. A compact spindle-shaped sensor is a potential effective sensor with a simple structure, easy fabrication and low cost. The sensor can be used to detect glucose content in areas such as crops quality assessment and the research of pharmacy and bioengineering.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60372061)the Scientific Forefront and Interdisciplinary Innovation Project of Jilin University, China (Grant No. 200903296)
文摘We numerically investigate the formation and interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser. Based on a lumped model, the parabolic-shaped pulse pair is obtained by controlling the intercavity average dispersion and gain saturation energy, Moreover, pulse repulsive and attractive motion are also achieved with different pulse separations. Simulation results show that the phase shift plays an important role in pulse interaction, and the interaction is determined by the inter-cavity average dispersion and gain saturation energy, i.e., the strength of the interaction is proportional to the gain saturation energy, a stronger gain saturation energy will result in a higher interaction intensity. On the contrary, the increase of the inter-cavity dispersion will counterbalance some interaction force. The results also show that the interaction of a parabolic-shaped pulse pair has a larger interaction distance compared to conventional solitons.
基金the financial support of the National Natural Science Foundation of China(Grant Nos.51379197 and 51522906)the Excellent Youth Foundation of Shandong Scientific Committee(Grant No.JQ201512)
文摘Compared to traditional mode shape identification methods such as eigensystem realization algorithm(ERA),this article proposes a mode shape identification method based on estimated residues of measured data and the theoretical relationship between the estimated residues and the mode shapes from the state space model is obtained by defining a coefficient matrix.A mass-spring model with five degrees of freedom(DOFs) is utilized to demonstrate the approach.The numerical results indicate that the estimated residues are the mode shapes of structures,but with a coefficient matrix to maintain consistency with the mode shapes from the ERA.Using MATLAB a complicated numerical jacket platform is built to further study the proposed method.The results show that mode shapes consistent with those from the ERA could be obtained by taking the defined coefficient matrix into account,which is also demonstrated by a physical beam model that was built at Ocean University of China.
基金Project supported by the National Basic Research Program of China(Grant No.2010CB923202)
文摘The effects of the shape of a nanowire terminus on the excited surface plasmon polariton （SPP） modes are investigated. The conical terminus and terminus cut at a certain angle are studied. For the first time, the quantitative mode decompositions are carried out to derive the full information about excited SPP modes. It is demonstrated that tuning the shape of the terminus provides an effective method to control the composition of excited SPP modes on metal nanowires. It is especially found that some important patterns, such as the pure TM0 mode and the superposition of TM0 and HE＋1 or HE-1 modes, can be generated by some specific shapes of the terminus, whereas there is no way to produce these patterns using flat-end nanowires.
文摘Elastic critical buckling load of a column depends on various parameters,such as boundary conditions,material,and crosssection geometry.The main purpose of this work is to present a new method for investigating the buckling load of tapered columns subjected to axial force.The proposed method is based on modified buckling mode shape of tapered structure and perturbation theory.The mode shape of the damaged structure can be expressed as a linear combination of mode shapes of the intact structure.Variations in length in piecewise form can be positive or negative.The method can be used for single-span and continuous columns.Comparison of results with those of finite element and Timoshenko methods shows the high accuracy and efficiency of the proposed method for detecting buckling load.
基金The project supported by the National Natural Science Foundation of China(No.19872060)
文摘An exact analysis of the modes Ⅱ and Ⅲ problems of a penny- shaped crack in a transversely isotropic piezoelectric medium is performed in this paper.The potential theory method is employed based on the general solution of three-dimensional piezoelasticity and the four harmonics involved are represented by one complex potential.Previous results in potential theory are then utilized to obtain the exact solution that is expressed in terms of elementary functions.Comparison is made between the current results with those published and good agreement is obtained.
文摘In this paper, we will try to find a universal theoretical model and approximate solutions which can be applied to both mode shape and normal shape actuators and sensors, and which can be predicted the gain of the first three modes of the mode shape and normal shape actuators and sensors, finally through computer simulation analysis to validate. In order to prove the feasibility of the theory and as well as convenient to use on the electro-mechanical engineering, we will try to simplify the three-dimension structure problem into an one-dimension structure problem. Furthermore we will design one kind of bimorph type piezoelectric cantilever beam, so that it can be used as with the actuator and sensor simultaneously, but also conducive to the theory and simulation analysis. As for the simulation analysis, we will use the ANSYS code.
文摘In this paper, we want to make a new type linear piezoelectric motor by mode shape coating or effective electrode surface coating. The mode shape is derived from the mechanical boundary conditions of the linear piezoelectric motor. We only have access to the first three modes of formas, the effective electrode surface coating basis, as well as with the linear piezoelectric motor of normal shape do comparison. Next, we will inspect their gain or axial velocity through theoretical analysis, simulation and experiment. According to the results of the theoretical analysis, we have found that the gain or axial velocity of the linear piezoelectric motors of mode shape is much larger than the linear piezoelectric motors of normal shape. However, according to the results of simulation and experiments, we have found that the gain or axial velocity of the linear piezoelectric motors of mode shape is much greater than the linear piezoelectric motors of normal shape, which is about 1.2 to 1.4 times. The linear piezoelectric motor of mode shape 3 has the fastest axial velocity, which is about -48 mm/s and 48 mm/s under conditions of 180 Vp-p driving voltage, 21.2 kHz driving frequency (the third vibration modal), 25 gw loading and the position of loading or mass at x = 5 mm & 45 mm respectively. And its axial velocity is about 1.4 times the linear piezoelectric motor of normal shape under the same conditions. Overall, the mode shape coating helps to enhance the gain or axial velocity of the linear piezoelectric motor.
文摘An experimental program was undertaken to test the feasibility to detect the occurrence of structural damage using a modified mode shape difference technique. The vibration response of a steel beam fixed at one end and hinged at the other was obtained for the intact and damage conditions. Modal analysis was performed to extract the frequencies and mode shapes. The method shows a good potential in detection of occurrence and location of damage.
文摘Methods for scaling mode shapes determined by operational modal analysis(OMA)have been extensively investigated in the last years.A recent addition to the range of methods for scaling OMA mode shapes is the so-called OMAH technique,which is based on exciting the structure by harmonic forces applied by an actuator.By applying harmonic forces in at least one degree-of-freedom(DOF),and measuring the response in at least one response DOF,while using at least as many frequencies as the number of mode shapes to be scaled,the mode shape scaling(modal mass)of all modes of interest may be determined.In previous publications on the method the authors have proven that the technique is easy and robust to apply to both small scale and large scale structures.Also,it has been shown that the technique is capable of scaling highly coupled modes by using an extended multiple reference formulation.The present paper summarizes the theory of the OMAH method and gives recommendations of how to implement the method for best results.It is pointed out,as has been shown in previous papers,that the accuracy of the mode scaling is increased by using more than one response DOF,and by selecting DOFs with high mode shape coefficients.To determine the harmonic force and responses,it is recommended to use the three-parameter sine fit method.It is shown that by using this method,the measurement time can be kept short by using high sampling frequency and bandpass filtering whereas spectrum based methods require long measurement times.This means that even for structures with low natural frequencies,the extra measurement time for scaling the mode shapes can be kept relatively short.
基金Supported by the National Natural Science Foundation of China under Grant No 61302022
文摘Dipole coupled nanomagnets controlled by the static Zeeman field can form various magnetic logic interconnects.However, the corner wire interconnect is often unreliable and error-prone at room temperature. In this study, we address this problem by making it into a reliable type with trapezoid-shaped nanomagnets, the shape anisotropy of which helps to offer the robustness. The building method of the proposed corner wire interconnect is discussed,and both its static and dynamic magnetization properties are investigated. Static micromagnetic simulation demonstrates that it can work correctly and reliably. Dynamic response results are reached by imposing an ac microwave field on the proposed corner wire. It is found that strong ferromagnetic resonance absorption appears at a low frequency. With the help of a very small ac field with the peak resonance frequency, the required static Zeeman field to switch the corner wire is significantly decreased by ~21 m T. This novel interconnect would pave the way for the realization of reliable and low power nanomagnetic logic circuits.
文摘The random decrement technique is an averaging technique that can be used to extract the free decay response of the structure from its random stationary vibratory response. The free decay response can then be used to identify the vibratory characteristics of the structure. The main advantage of the technique is that the identification of the parameters of the structure is achieved without previous knowledge of the excitation forces. This paper extends the random decrement technique to obtain the mode shapes of the structure using the concept of a multichannel random decrement technique （MCRD）. This technique is based on extracting simultaneous random decrement records from measurements made at several points on the structure. The method is very efficient and simple. Numerical examples are solved and compared with the exact mode shapes extracted using classical modal analysis. An excellent agreement between the extracted modes shapes using the MCRD and those obtained from the classical modal analysis techniques is achieved. The vibration of an offshore structure excited by white noise excitation is used to illustrate the method.
基金financial supports from the National Natural Science Foundation of China (62075132 and 92050202)Natural Science Foundation of Shanghai (22ZR1443100)
文摘This work introduces special states for light in multimode fibers featuring strongly enhanced or reduced correlations be-tween output fields in the presence of environmental temperature fluctuations.Using experimentally measured multi-tem-perature transmission matrix,a set of temperature principal modes that exhibit resilience to disturbances caused by tem-perature fluctuations can be generated.Reversing this concept also allows the construction of temperature anti-principal modes,with output profiles more susceptible to temperature influences than the unmodulated wavefront.Despite changes in the length of the multimode fiber within the temperature-fluctuating region,the proposed approach remains capable of robustly controlling the temperature response within the fiber.To illustrate the practicality of the proposed spe-cial state,a learning-empowered fiber specklegram temperature sensor based on temperature anti-principal mode sensi-tization is proposed.This sensor exhibits outstanding superiority over traditional approaches in terms of resolution and accuracy.These novel states are anticipated to have wide-ranging applications in fiber communication,sensing,imaging,and spectroscopy,and serve as a source of inspiration for the discovery of other novel states.
基金supported by the Airlangga University through Mandate Research Grant(Nos.216/UN3.15/PT/2022 and 217/UN3.15/PT/2022)。
文摘This paper presents a biosensor utilizing a whispering gallery mode(WGM)resonator characterized by azimuthal symmetry and crescent-shaped coatings of silver.The study investigates the impact of the coupling gap on the extinction ratio and Q-factor of the setup.The resonator is coated with silver in crescent shapes,ranging from 40 nm to 65 nm in thickness.Coupling is achieved with a silica waveguide,simulating the tapered fiber coupling method.Notably,the resonator exhibits a maximum sensitivity of 220 nm/RIU when coated with 55-nm-thick silver in conjunction with a 4-nm-thick layer of thiol-tethered deoxyribonucleic acid(DNA).This biosensor holds promise for biomolecule detection applications.
