A analyzed model of gear with wheel hub, web and rim was derived from the Mindlin moderate plate theory. The gear was divided into three annular segments along the locations of the step variations. Traverse displaceme...A analyzed model of gear with wheel hub, web and rim was derived from the Mindlin moderate plate theory. The gear was divided into three annular segments along the locations of the step variations. Traverse displacement, rotation angle, shear force and fiexural moment were equal to ensure the continuity along the interface of the wheel hub, web and rim segments. The governing differential equations for harmonic vibration of annular segments were derived to solve the gear vibration problem. The influence of hole to diameter ratios, segment thickness ratios, segment location ratios, Poisson ratio on the vibration behavior of stepped circular Mindlin disk were calculated, tabletted and plotted. Comparisons were made with the frequencies arising from the presented method, finite elements method, and structure modal experiment. The result correlation among these three ways is very good. The largest error for all frequencies is 5.46%, and less than 5% for most frequencies.展开更多
An elastic vibration model for high length diameter ratio spinning rocket with attitude control system which can be used for trajectory simulation is established. The basic theory of elastic dynamics and vibration dy...An elastic vibration model for high length diameter ratio spinning rocket with attitude control system which can be used for trajectory simulation is established. The basic theory of elastic dynamics and vibration dynamics were both used to set up the elastic vibration model of rocket body. In order to study the problem more conveniently, the rocket's body was simplified to be an even beam with two free ends. The model was validated by simulation results and the test data.展开更多
As the first link element for the transmission of shaft vibration to the pedestal and even to the hull,water-lubricated bearing plays a key role in suppressing vibration.Although the porous structure is considered as ...As the first link element for the transmission of shaft vibration to the pedestal and even to the hull,water-lubricated bearing plays a key role in suppressing vibration.Although the porous structure is considered as one of the main methods for improving the wideband vibration and noise reduction performance of materials in many industrial fields,the studies in the field of water-lubricated bearing remain insufficient.To enhance vibration reduction performance,a fluid-saturated perforated slab is designed in this study,and via the establishment of a fluid-solid coupled vibration model,the influence law and impact levels were analyzed and verified by simulation and experiments.The results obtained verified that the total vibration amplitude of damping-enhanced stern bearing in the vertical direction was smaller than that of the normal stern bearing,and the reduction amplitude of the characteristic frequency agreed with the optimal value at approximately 0.1 of the volume fraction of the liquid phase when the solid-fluid phase was rubber–water.Additionally,the increase in fluid fraction did not enhance the damping effect,instead,it unexpectedly reduced the natural frequency of the raw material significantly.This research indicates that the design of the fluid-saturated perforated slab is effective in reducing the transmission of the vibration amplitude from the shaft,and presents the best volume fraction of the liquid phase.展开更多
This paper studies the coupling effect of the pipeline vibration on the seabed scour. A vertical two- dimensional model is applied to numerically investigate the local scour below a vibrating pipeline with different a...This paper studies the coupling effect of the pipeline vibration on the seabed scour. A vertical two- dimensional model is applied to numerically investigate the local scour below a vibrating pipeline with different amplitudes and periods. Using the scour underneath a fixed pipeline as a reference, this paper focuses on the impact of the pipeline vibration on the equilibrium scour depth. Generic relationships are established between the non-dimensional scour depth and the non-dimensional vibrating parameters, i.e., amplitude and frequency. The normalization process takes into account the influences of such parameters as the incoming flow velocity, pipe diameter, and Shields parameter. An empirical formula is proposed to quantify these relationships.展开更多
The FRF estimator based on the errors-in-variables （EV） model of multi-input multi-output （MIMO） system is presented to reduce the bias error of FRF HI estimator. The FRF HI estimator is influenced by the noises i...The FRF estimator based on the errors-in-variables （EV） model of multi-input multi-output （MIMO） system is presented to reduce the bias error of FRF HI estimator. The FRF HI estimator is influenced by the noises in the inputs of the system and generates an under-estimation of the true FRF. The FRF estimator based on the EV model takes into account the errors in both the inputs and outputs of the system and would lead to more accurate FRF estimation. The FRF estimator based on the EV model is applied to the waveform replication on the 6-DOF （degree-of-freedom） hydraulic vibration table. The result shows that it is favorable to improve the control precision of the MIMO vibration control system.展开更多
A space coupling vibration model of the system of wheel and lead curve rails of turnouts is presented, in which the vibration of the straight and curved rails are taken into account and the variations of the elastici...A space coupling vibration model of the system of wheel and lead curve rails of turnouts is presented, in which the vibration of the straight and curved rails are taken into account and the variations of the elasticity of roadbed with the length of switch ties are considered. It is used to investigate the dynamic characteristics of different configuration of lead curve, such as circular curve, cubic spiral and high order transition curves. Based on the numerical analysis, some advantageous configurations of lead curve are suggested.展开更多
Morphing wing has attracted many research attention and effort in aircraft technology development because of its advantage in lift to draft ratio and flight performance.Morphing wing technology combines the lift and c...Morphing wing has attracted many research attention and effort in aircraft technology development because of its advantage in lift to draft ratio and flight performance.Morphing wing technology combines the lift and control surfaces into a seamless wing and integrates the primary structure together with the internal control system.It makes use of the wing aeroelastic deformation induced by the control surface to gain direct force control through desirable redistribution of aerodynamic forces.However some unknown mechanical parameters of the control system and complexity of the integrated structure become a main challenge for dynamic modeling of morphing wing.To solve the problem,a method of test data based modal sensitivity analysis is presented to improve the morphing wing FE model by evaluating the unknown parameters and identifying the modeling boundary conditions.An innovative seamless morphing wing with the structure integrated with a flexible trailing edge control system is presented for the investigation.An experimental model of actuation system driven by a servo motor for the morphing wing is designed and established.By performing a vibration test and the proposed modal sensitivity analysis,the unknown torsional stiffness of the servo motor and the boundary condition of the actuation mechanism model is identified and evaluated.Comparing with the test data,the average error of the first four modal frequency of the improved FE model is reduced significantly to less than 4%.To further investigate the morphing wing modeling,a wing box and then a whole morphing wing model including the skin and integrated with the trailing edge actuation system are established and tested.By using the proposed method,the FE model is improved by relaxing the constraint between the skin and actuation mechanism.The results show that the average error of the first three modal frequency of the improved FE model is reduced to less than 6%.The research results demonstrate that the presented seamless morphing wing integrated with a flexible trailing edge control surface can improve aerodynamic characteristics.By using the test data based modal sensitivity analysis method,the unknown parameter and boundary condition of the actuation model can be determined to improve the FE model.The problem in dynamic modeling of high accuracy for a morphing wing can be solved in an effective manner.展开更多
To achieve the dual demand of resisting violent impact and attenuating vibration in vibration-impact-safety of protection for precision equipment such as MEMS packaging system, a theo- retical mathematical model of mu...To achieve the dual demand of resisting violent impact and attenuating vibration in vibration-impact-safety of protection for precision equipment such as MEMS packaging system, a theo- retical mathematical model of multi-medium coupling shock absorber is presented. The coupling of quadratic damping, linear damping, Coulomb damping and nonlinear spring are considered in the model. The approximate theoretical calculating formulae are deduced by introducing transformation-tactics. The contrasts between the analytical results and numerical integration results are developed. The resisting impact characteristics of the model are also analyzed in progress. In the meantime, the optimum model of the parameters matching selection for design of the shock absorber is built. The example design is illustrated to confirm the validity of the modeling method and the theoretical solution.展开更多
Article continues and complements our previous articles on the HM16 ether (ETH) model. Here, we describe the mechanism of occurrence of the submicroparticle (SMP). A general hypothesis, HFVI, is introduced for the mod...Article continues and complements our previous articles on the HM16 ether (ETH) model. Here, we describe the mechanism of occurrence of the submicroparticle (SMP). A general hypothesis, HFVI, is introduced for the modalities of interaction between two SMPs, based on periodic mechanical percussion forces, produced by fundamental vibrations FVs. A mechanism for describing the interaction between a SMPs and the ETH is presented. Positive and negative particles are defined by their membrane types of movement, such as +, <span style="white-space:nowrap;">−</span><em>u</em>/+, <span style="white-space:nowrap;">−</span><em>v</em> vibrations, and rotations at speeds +<span style="white-space:nowrap;">Ω</span>/<span style="white-space:nowrap;">−</span><span style="white-space:nowrap;">Ω</span>. The process of creating a pair of SMPs is discussed. Applying HFVI to the interaction between pairs of SMPs immobile in ETH, and considering longitudinal FVL, was obtained the forces of attraction/repulsion +<em>F</em><sub><em>L</em>21</sub>/–<em>F<sub>L</sub></em><sub>21</sub>, which correspond to the completed Coulomb force<em> F<sub>CC</sub></em> including gravitation. The resultant <em>F</em><sub>RL21</sub> will form an oriented field of forces, which is a quasielectric field <em>QE</em>, equivalent to actual <em>E</em> electric field. Considering transversal FVT, was obtained the vibratory forces +, <span style="white-space:nowrap;">−</span><em>F<sub>T</sub></em><sub>21</sub>, whose resultant forms an vibrating field of forces, <em>QHs</em>, a quasimagnetic special field, which may explain some of the quantum properties of SMPs. Considering a mobile SMP, two new<em> <span style="white-space:nowrap;">γ</span></em> strains in ETH appear. Strains <em><span style="white-space:nowrap;">γ</span><sub>L</sub></em> are created by the displacement of SMP with velocity<em> V</em>, whose force +, <span style="white-space:nowrap;">−</span><em>F<sub>T</sub></em><sub>12</sub> is the support of a component of the magnetic field <em>H</em> (quasimagnetic field <em>QH</em>), giving the <em>QH<sub>L</sub></em> component. Strains <em>γ</em><sub>R</sub> are created by the rotation of SMP with speed <span style="white-space:nowrap;">Ω</span>, whose force +, <span style="white-space:nowrap;">−</span><em>F</em><sub>R12</sub> constitutes physical support of the component <em>QH<sub>R</sub></em> of magnetic field <em>H </em>(<em>i.e. QH)</em><em></em>. The creation of a photon PH is modelled as a special ESMP containing two zones of opposed rotations, and a mechanism is presented for its movement in the ETH with speed <em>c</em> based on the HS hypothesis of screwing in ETH, with frequency <em>ν</em>.展开更多
The dynamic model of two-flexible-arm mechanism with elastic joints is studied.The transmission problem of the joint which connects two flexible links is successfully solved. The mechanical model is proposed for the j...The dynamic model of two-flexible-arm mechanism with elastic joints is studied.The transmission problem of the joint which connects two flexible links is successfully solved. The mechanical model is proposed for the joint, and a practical vibration analysis method of lumped parameter transfer matrix modal analysis is developed for two flexible arms with an elastic joint.展开更多
Rotational speed stability is an important evaluation indicator of the performance of a hydro-viscous clutch(HVC).To improve the rotational speed stability of HVCs in mixed lubrication and the running condition of the...Rotational speed stability is an important evaluation indicator of the performance of a hydro-viscous clutch(HVC).To improve the rotational speed stability of HVCs in mixed lubrication and the running condition of the friction pairs,the speed stability of an HVC in mixed lubrication was studied.To this end,the friction coefficients of both copper-based and paper-based friction pairs were experimentally tested using an MM1000-III wet friction machine.Theoretically,a torsional vibration model of the system is presented.The phase plane analysis method is applied to evaluate the stability of the torsional vibration model,where a critical negative gradient(CNG)is defined.The results show that the friction coefficient in mixed lubrication is an important parameter for the stability of the rotational speed.The system will be unstable when the negative gradient of the friction coefficient-slip speed is larger than the CNG.According to the definition of the CNG,suggestions regarding choice of friction pairs are made to improve the rotational speed stability of an HVC in mixed lubrication.展开更多
Single bubble sonoluminescence is a process of energy transformation from sound to light. Therefore the motion equations of near spherical vibration of a gas bubble in an incompressible and viscous liquid can be deduc...Single bubble sonoluminescence is a process of energy transformation from sound to light. Therefore the motion equations of near spherical vibration of a gas bubble in an incompressible and viscous liquid can be deduced by Lagrangian Equation with dissipation function when the bubble is considered as a vibrator surrounded by liquid. The analytical solutions in the bubble expanding, collapsing and rebounding stages can be obtained by solving these motion equations when some approximations are adopted. And the dynamic behaviors of the bubble in these three stages are discussed.展开更多
In this work, Rotation model and rotation vibration coupled channel optical model (CCOM) were first used to carry out systematic calculation of neutron direct inelastic scattering cross section (DISCS) for the reacti...In this work, Rotation model and rotation vibration coupled channel optical model (CCOM) were first used to carry out systematic calculation of neutron direct inelastic scattering cross section (DISCS) for the reaction 238 U (n,n′) with an incident energy from 0 01 MeV to 20 0 MeV . The number of coupled energy levels involved in this calculation increased to eight at the first time, namely 0 +, 2 +, 4 +, 6 +, 8 + in the ground rotation band of 238 U and 1 -, 3 -, 5 - in the octupole vibration band with K=0 -. Some physical problems, such as how to get the optical model parameters of deformed nuclei and phonon amplitudes, are discussed.展开更多
Somatic gene therapy remains technically challenging,especially in the central nervous system(CNS).Efficiency of gene delivery,efficacy in recipient cells,and proportion of cells required for overall benefit are the k...Somatic gene therapy remains technically challenging,especially in the central nervous system(CNS).Efficiency of gene delivery,efficacy in recipient cells,and proportion of cells required for overall benefit are the key points needed to be considered in any therapeutic approach.Recent efforts have demonstrated the efficacy of RNA-guided nucleases such as CRISPR/Cas9 in correcting point mutations or removing dominant mutations.Here we used viral delivered Cas9 plasmid and two guide RNAs to remove a recessive insertional mutation,vibrator(vb),in the mouse brain.The vb mice expressed∼20%of normal levels of phosphatidylinositol transfer protein,α(PITPα)RNA and protein due to an endogenous retrovirus inserted in intron 4,resulting in early-onset tremor,degeneration of brainstem and spinal cord neurons,and juvenile death.The in situ CRISPR/Cas9 viral treatment effectively delayed neurodegeneration,attenuated tremor,and bypassed juvenile death.Our studies demonstrate the potential of CRISPR/Cas9-mediated gene therapy for insertional mutations in the postnatal brain.展开更多
Structural design for a drum of a CTP device and modal analysis by means of ANSYS workbench have been done to get the first four natural frequencies and vibration models.Natural frequency and maximum deformation of dr...Structural design for a drum of a CTP device and modal analysis by means of ANSYS workbench have been done to get the first four natural frequencies and vibration models.Natural frequency and maximum deformation of drum as the optimization goal,three kinds of proposals are put forward based on the weak area of the drum.By means of adjusting static balance and adding thickness,an optimal project 3 is determined the best in the three kinds of proposals.The first natural frequency of the drum optimized is increased by 33.1% than that before optimization,the maximum displacement is reduced by 23.2%.Testing the result of simulation meets image high quality requirements,dynamics analysis and structural optimization are realized.展开更多
基金Foundation item： Project（50975191） supported by the National Natural Science Foundation of China Project（20113027） supported by the Outstanding Innovation Project of Shanxi Province Foundation for Graduate Student
文摘A analyzed model of gear with wheel hub, web and rim was derived from the Mindlin moderate plate theory. The gear was divided into three annular segments along the locations of the step variations. Traverse displacement, rotation angle, shear force and fiexural moment were equal to ensure the continuity along the interface of the wheel hub, web and rim segments. The governing differential equations for harmonic vibration of annular segments were derived to solve the gear vibration problem. The influence of hole to diameter ratios, segment thickness ratios, segment location ratios, Poisson ratio on the vibration behavior of stepped circular Mindlin disk were calculated, tabletted and plotted. Comparisons were made with the frequencies arising from the presented method, finite elements method, and structure modal experiment. The result correlation among these three ways is very good. The largest error for all frequencies is 5.46%, and less than 5% for most frequencies.
文摘An elastic vibration model for high length diameter ratio spinning rocket with attitude control system which can be used for trajectory simulation is established. The basic theory of elastic dynamics and vibration dynamics were both used to set up the elastic vibration model of rocket body. In order to study the problem more conveniently, the rocket's body was simplified to be an even beam with two free ends. The model was validated by simulation results and the test data.
基金Supported by State Key Program Grant of National Natural Science Foundation of China(Grant No.51579198)Key Laboratory of High Performance Ship Technology Opening Foundation(Grant No.2016gxnc04).
文摘As the first link element for the transmission of shaft vibration to the pedestal and even to the hull,water-lubricated bearing plays a key role in suppressing vibration.Although the porous structure is considered as one of the main methods for improving the wideband vibration and noise reduction performance of materials in many industrial fields,the studies in the field of water-lubricated bearing remain insufficient.To enhance vibration reduction performance,a fluid-saturated perforated slab is designed in this study,and via the establishment of a fluid-solid coupled vibration model,the influence law and impact levels were analyzed and verified by simulation and experiments.The results obtained verified that the total vibration amplitude of damping-enhanced stern bearing in the vertical direction was smaller than that of the normal stern bearing,and the reduction amplitude of the characteristic frequency agreed with the optimal value at approximately 0.1 of the volume fraction of the liquid phase when the solid-fluid phase was rubber–water.Additionally,the increase in fluid fraction did not enhance the damping effect,instead,it unexpectedly reduced the natural frequency of the raw material significantly.This research indicates that the design of the fluid-saturated perforated slab is effective in reducing the transmission of the vibration amplitude from the shaft,and presents the best volume fraction of the liquid phase.
基金supported by the National Natural Science Foundation of China(51479111) the Open Fund at the State Key Laboratory of Hydraulics and Mountain River Engineering, China(SKHL1404)
文摘This paper studies the coupling effect of the pipeline vibration on the seabed scour. A vertical two- dimensional model is applied to numerically investigate the local scour below a vibrating pipeline with different amplitudes and periods. Using the scour underneath a fixed pipeline as a reference, this paper focuses on the impact of the pipeline vibration on the equilibrium scour depth. Generic relationships are established between the non-dimensional scour depth and the non-dimensional vibrating parameters, i.e., amplitude and frequency. The normalization process takes into account the influences of such parameters as the incoming flow velocity, pipe diameter, and Shields parameter. An empirical formula is proposed to quantify these relationships.
基金This project is supported by Program for New Century Excellent Talents in University,China(No.NCET-04-0325).
文摘The FRF estimator based on the errors-in-variables （EV） model of multi-input multi-output （MIMO） system is presented to reduce the bias error of FRF HI estimator. The FRF HI estimator is influenced by the noises in the inputs of the system and generates an under-estimation of the true FRF. The FRF estimator based on the EV model takes into account the errors in both the inputs and outputs of the system and would lead to more accurate FRF estimation. The FRF estimator based on the EV model is applied to the waveform replication on the 6-DOF （degree-of-freedom） hydraulic vibration table. The result shows that it is favorable to improve the control precision of the MIMO vibration control system.
文摘A space coupling vibration model of the system of wheel and lead curve rails of turnouts is presented, in which the vibration of the straight and curved rails are taken into account and the variations of the elasticity of roadbed with the length of switch ties are considered. It is used to investigate the dynamic characteristics of different configuration of lead curve, such as circular curve, cubic spiral and high order transition curves. Based on the numerical analysis, some advantageous configurations of lead curve are suggested.
基金supported by National Natural Science Foundation of China (Grant No. 11102019)
文摘Morphing wing has attracted many research attention and effort in aircraft technology development because of its advantage in lift to draft ratio and flight performance.Morphing wing technology combines the lift and control surfaces into a seamless wing and integrates the primary structure together with the internal control system.It makes use of the wing aeroelastic deformation induced by the control surface to gain direct force control through desirable redistribution of aerodynamic forces.However some unknown mechanical parameters of the control system and complexity of the integrated structure become a main challenge for dynamic modeling of morphing wing.To solve the problem,a method of test data based modal sensitivity analysis is presented to improve the morphing wing FE model by evaluating the unknown parameters and identifying the modeling boundary conditions.An innovative seamless morphing wing with the structure integrated with a flexible trailing edge control system is presented for the investigation.An experimental model of actuation system driven by a servo motor for the morphing wing is designed and established.By performing a vibration test and the proposed modal sensitivity analysis,the unknown torsional stiffness of the servo motor and the boundary condition of the actuation mechanism model is identified and evaluated.Comparing with the test data,the average error of the first four modal frequency of the improved FE model is reduced significantly to less than 4%.To further investigate the morphing wing modeling,a wing box and then a whole morphing wing model including the skin and integrated with the trailing edge actuation system are established and tested.By using the proposed method,the FE model is improved by relaxing the constraint between the skin and actuation mechanism.The results show that the average error of the first three modal frequency of the improved FE model is reduced to less than 6%.The research results demonstrate that the presented seamless morphing wing integrated with a flexible trailing edge control surface can improve aerodynamic characteristics.By using the test data based modal sensitivity analysis method,the unknown parameter and boundary condition of the actuation model can be determined to improve the FE model.The problem in dynamic modeling of high accuracy for a morphing wing can be solved in an effective manner.
基金This project is supported by National Defense Science Foundation of China (No.00J16.2.5.DZ0502)Foundation for Qualified Personnel of Jiangsu University, China(No.04JDG027)Provincial Natural Science Foundation of Guangxi. China(No.0339037, No.0141042).
文摘To achieve the dual demand of resisting violent impact and attenuating vibration in vibration-impact-safety of protection for precision equipment such as MEMS packaging system, a theo- retical mathematical model of multi-medium coupling shock absorber is presented. The coupling of quadratic damping, linear damping, Coulomb damping and nonlinear spring are considered in the model. The approximate theoretical calculating formulae are deduced by introducing transformation-tactics. The contrasts between the analytical results and numerical integration results are developed. The resisting impact characteristics of the model are also analyzed in progress. In the meantime, the optimum model of the parameters matching selection for design of the shock absorber is built. The example design is illustrated to confirm the validity of the modeling method and the theoretical solution.
文摘Article continues and complements our previous articles on the HM16 ether (ETH) model. Here, we describe the mechanism of occurrence of the submicroparticle (SMP). A general hypothesis, HFVI, is introduced for the modalities of interaction between two SMPs, based on periodic mechanical percussion forces, produced by fundamental vibrations FVs. A mechanism for describing the interaction between a SMPs and the ETH is presented. Positive and negative particles are defined by their membrane types of movement, such as +, <span style="white-space:nowrap;">−</span><em>u</em>/+, <span style="white-space:nowrap;">−</span><em>v</em> vibrations, and rotations at speeds +<span style="white-space:nowrap;">Ω</span>/<span style="white-space:nowrap;">−</span><span style="white-space:nowrap;">Ω</span>. The process of creating a pair of SMPs is discussed. Applying HFVI to the interaction between pairs of SMPs immobile in ETH, and considering longitudinal FVL, was obtained the forces of attraction/repulsion +<em>F</em><sub><em>L</em>21</sub>/–<em>F<sub>L</sub></em><sub>21</sub>, which correspond to the completed Coulomb force<em> F<sub>CC</sub></em> including gravitation. The resultant <em>F</em><sub>RL21</sub> will form an oriented field of forces, which is a quasielectric field <em>QE</em>, equivalent to actual <em>E</em> electric field. Considering transversal FVT, was obtained the vibratory forces +, <span style="white-space:nowrap;">−</span><em>F<sub>T</sub></em><sub>21</sub>, whose resultant forms an vibrating field of forces, <em>QHs</em>, a quasimagnetic special field, which may explain some of the quantum properties of SMPs. Considering a mobile SMP, two new<em> <span style="white-space:nowrap;">γ</span></em> strains in ETH appear. Strains <em><span style="white-space:nowrap;">γ</span><sub>L</sub></em> are created by the displacement of SMP with velocity<em> V</em>, whose force +, <span style="white-space:nowrap;">−</span><em>F<sub>T</sub></em><sub>12</sub> is the support of a component of the magnetic field <em>H</em> (quasimagnetic field <em>QH</em>), giving the <em>QH<sub>L</sub></em> component. Strains <em>γ</em><sub>R</sub> are created by the rotation of SMP with speed <span style="white-space:nowrap;">Ω</span>, whose force +, <span style="white-space:nowrap;">−</span><em>F</em><sub>R12</sub> constitutes physical support of the component <em>QH<sub>R</sub></em> of magnetic field <em>H </em>(<em>i.e. QH)</em><em></em>. The creation of a photon PH is modelled as a special ESMP containing two zones of opposed rotations, and a mechanism is presented for its movement in the ETH with speed <em>c</em> based on the HS hypothesis of screwing in ETH, with frequency <em>ν</em>.
文摘The dynamic model of two-flexible-arm mechanism with elastic joints is studied.The transmission problem of the joint which connects two flexible links is successfully solved. The mechanical model is proposed for the joint, and a practical vibration analysis method of lumped parameter transfer matrix modal analysis is developed for two flexible arms with an elastic joint.
基金supported by National Natural Science Foundation of China(Grant No.51275039)Tribology Science Fund of the State Key Laboratory of Tribology(Grant No.SKLTKF13B01).
文摘Rotational speed stability is an important evaluation indicator of the performance of a hydro-viscous clutch(HVC).To improve the rotational speed stability of HVCs in mixed lubrication and the running condition of the friction pairs,the speed stability of an HVC in mixed lubrication was studied.To this end,the friction coefficients of both copper-based and paper-based friction pairs were experimentally tested using an MM1000-III wet friction machine.Theoretically,a torsional vibration model of the system is presented.The phase plane analysis method is applied to evaluate the stability of the torsional vibration model,where a critical negative gradient(CNG)is defined.The results show that the friction coefficient in mixed lubrication is an important parameter for the stability of the rotational speed.The system will be unstable when the negative gradient of the friction coefficient-slip speed is larger than the CNG.According to the definition of the CNG,suggestions regarding choice of friction pairs are made to improve the rotational speed stability of an HVC in mixed lubrication.
基金This project is supported by the Key Program ofthe National Science Foundation ofChina(Grant 19934001 and 59738150)and Doctoral Foundation of Education Ministry of China.
文摘Single bubble sonoluminescence is a process of energy transformation from sound to light. Therefore the motion equations of near spherical vibration of a gas bubble in an incompressible and viscous liquid can be deduced by Lagrangian Equation with dissipation function when the bubble is considered as a vibrator surrounded by liquid. The analytical solutions in the bubble expanding, collapsing and rebounding stages can be obtained by solving these motion equations when some approximations are adopted. And the dynamic behaviors of the bubble in these three stages are discussed.
文摘In this work, Rotation model and rotation vibration coupled channel optical model (CCOM) were first used to carry out systematic calculation of neutron direct inelastic scattering cross section (DISCS) for the reaction 238 U (n,n′) with an incident energy from 0 01 MeV to 20 0 MeV . The number of coupled energy levels involved in this calculation increased to eight at the first time, namely 0 +, 2 +, 4 +, 6 +, 8 + in the ground rotation band of 238 U and 1 -, 3 -, 5 - in the octupole vibration band with K=0 -. Some physical problems, such as how to get the optical model parameters of deformed nuclei and phonon amplitudes, are discussed.
基金This research was funded by the National Natural Science Foundation of China(grant No.3201101229)Macao Science and Technology Development Fund(grant No.015/2017/AFJ)Natural Science Foundation of Guangdong Province(grant No.2020A1515010072).
文摘Somatic gene therapy remains technically challenging,especially in the central nervous system(CNS).Efficiency of gene delivery,efficacy in recipient cells,and proportion of cells required for overall benefit are the key points needed to be considered in any therapeutic approach.Recent efforts have demonstrated the efficacy of RNA-guided nucleases such as CRISPR/Cas9 in correcting point mutations or removing dominant mutations.Here we used viral delivered Cas9 plasmid and two guide RNAs to remove a recessive insertional mutation,vibrator(vb),in the mouse brain.The vb mice expressed∼20%of normal levels of phosphatidylinositol transfer protein,α(PITPα)RNA and protein due to an endogenous retrovirus inserted in intron 4,resulting in early-onset tremor,degeneration of brainstem and spinal cord neurons,and juvenile death.The in situ CRISPR/Cas9 viral treatment effectively delayed neurodegeneration,attenuated tremor,and bypassed juvenile death.Our studies demonstrate the potential of CRISPR/Cas9-mediated gene therapy for insertional mutations in the postnatal brain.
文摘Structural design for a drum of a CTP device and modal analysis by means of ANSYS workbench have been done to get the first four natural frequencies and vibration models.Natural frequency and maximum deformation of drum as the optimization goal,three kinds of proposals are put forward based on the weak area of the drum.By means of adjusting static balance and adding thickness,an optimal project 3 is determined the best in the three kinds of proposals.The first natural frequency of the drum optimized is increased by 33.1% than that before optimization,the maximum displacement is reduced by 23.2%.Testing the result of simulation meets image high quality requirements,dynamics analysis and structural optimization are realized.
