On the Elastic Vibration Model for High Length-Diameter Ratio Rocket with Attitude Control System

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.

APPLICATION OF FRF ESTIMATOR BASED ON ERRORS-IN-VARIABLES MODEL IN MULTI-INPUT MULTI-OUTPUT VIBRATION CONTROL SYSTEM

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.

Vibration Reduction Performance of Damping-Enhanced Water-Lubricated Bearing Using Fluid-Saturated Perforated Slabs

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.

Scour depth beneath a pipeline undergoing forced vibration

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.

STUDY ON THE VIBRATION CHARACTERISTIC OF THE METAL PUSHING BELT CONTINUOUSLY VARIABLE TRANSMISSION

The solid and finite element model of metal pushing type continuously variable transmission are established at speed ratio of i =0 5 and i=2 0. In order to solve the problem of the complicated of structure,the node node rod discrete finite element model is put forward and the whole system is simplified and established.The natural frequency and mode shape of system are solved by iterative Lanczos reduce method for sensitivity analysis in finite element model.The new method and the result can be used to improve the smoothness of the variable transmission system and to propose the theory for reducing noise at operation.

Modeling and Experiment of a Morphing Wing Integrated with a Trailing Edge Control Actuation System

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.

A MODEL IDENTIFICATION METHOD OF VIBRATING STRUCTURES FROM INCOMPLETE MODAL INFORMATION

The accurate mathematical models for complicated structures are very difficult to construct.The work presented here provides an identification method for estimating the mass.damping,and stiffness matrices of linear dynamical systems from incomplete experimental data.The mass,stiffness and damping matrices are assumed to be real,symmetric,and positive definite The partial set of experimental complex eigenvalues and corresponding eigenvectors are given.In the proposed method the least squares algorithm is combined with the iteration technique to determine systems identified matrices and corresponding design parameters.Seeveral illustative examples,are presented to demonstrate the reliability of the proposed method .It is emphasized that the mass,damping and stiffness matrices can be identified simultaneously.

A NEW MODELING METHOD FOR MACHINE-FOUNDATION COUPLING SYSTEM AND ITS APPLICATION TO THE CONTROL OF POWER FLOW

A new concept, namely, the equivalent mobility matrix of coupling subsystem is proposed, and the corresponding threesubsystem coupling progressive approach is explored. With the new efficient approach presented, the complexity in dealing with a more complicated dynamic coupling system is greatly reduced. The new modeling method is then combined with the theory of power flow to investigate the dynamics of the overall non rigid isolation system from the viewpoint of energy. The interaction between the resilient machine of its main modes and the resonant behavior of the flexible foundation on power flow transmission is studied. Taking a machine tool mounted on a multi story working plant as an example, the dynamic characteristics of the machine foundation coupling system are analyzed, and their effects on power flow transmission are revealed under various service frequency bands. Some advisable control strategies and the design principle for machinery mounted on flexible structure are proposed.

MODELLING OF TWO-FLEXIBLE-ARM MECHANISM WITH ELASTIC JOINTS

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.

Dynamic Analysis of the Configuration of Lead Curves of Turnouts

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.

PARAMETRIC MATCHING SELECTION OF MULTI-MEDIUM COUPLING SHOCK ABSORBER

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.

New Properties of HM16 Ether, with Submicroparticles as Self-Functional Cells Interacting through Percussion Forces, Establishing Nature of Electrical Charges, including Gravitation

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 +, −u/+, −v vibrations, and rotations at speeds +Ω/−Ω. 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 +FL21/–FL21, which correspond to the completed Coulomb force FCC including gravitation. The resultant FRL21 will form an oriented field of forces, which is a quasielectric field QE, equivalent to actual E electric field. Considering transversal FVT, was obtained the vibratory forces +, −FT21, whose resultant forms an vibrating field of forces, QHs, a quasimagnetic special field, which may explain some of the quantum properties of SMPs. Considering a mobile SMP, two new γ strains in ETH appear. Strains γL are created by the displacement of SMP with velocity V, whose force +, −FT12 is the support of a component of the magnetic field H (quasimagnetic field QH), giving the QHL component. Strains γR are created by the rotation of SMP with speed Ω, whose force +, −FR12 constitutes physical support of the component QHR of magnetic field H (i.e. QH). 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 c based on the HS hypothesis of screwing in ETH, with frequency ν.

Dynamic behavior of gas bubble in single bubble sonoluminescence—vibrator model

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.

CRISPR/Cas9 mediated somatic gene therapy for insertional mutations:the vibrator mouse model

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.

An improved method for evaluating the rotational speed stability of a hydro-viscous clutch in mixed lubrication

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.

Calculation of the Neutron Direct Inelastic Scattering cross Section of ~ (238) U

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.

Optimization Design for Drum of Prepress Device

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.