Nonlinear Resonant Responses, Mode Interactions, and Multitime Periodic and Chaotic Oscillations of a Cantilevered Pipe Conveying Pulsating Fluid under External Harmonic Force

The nonlinear resonant responses, mode interactions, and multitime periodic and chaotic oscillations of the cantilevered pipe conveying pulsating fluid are studied under the harmonic external force in this research. According to the nonlinear dynamic model of the cantilevered beam derived using Hamilton’s principle under the uniformly distributed external harmonic excitation, we combine Galerkin technique and the method of multiple scales together to obtain the average equation of the cantilevered pipe conveying pulsating fluid under 1 : 3 internal resonance and principal parametric resonance. Based on the average equation in the polar form, several amplitude-frequency response curves are obtained corresponding to the certain parameters. It is found that there exist the hardening-spring type behaviors and jumping phenomena in the cantilevered pipe conveying pulsating fluid. The nonlinear oscillations of the cantilevered pipe conveying pulsating fluid can be excited more easily with the increase of the flow velocity, external excitation, and coupling degree of two order modes. Numerical simulations are performed to study the chaos of the cantilevered pipe conveying pulsating fluid with the external harmonic excitation. The simulation results exhibit the existence of the period, multiperiod, and chaotic responses with the variations of the fluid velocity or excitation. It is found that, in the cantilevered pipe conveying pulsating fluid, there are the multitime nonlinear vibrations around the left-mode and the right-mode positions, respectively. We also observe that there exist alternately the periodic and chaotic vibrations of the cantilevered pipe conveying pulsating fluid in the certain range.

An Approach for Generating an Average Bone Template With Semantic Parameters

To facilitate the design of the serialized implants and to satisfy the requirements of the population, a novel method is put forward for constructing an average bone model (ABM) with semantic parameters as a template. First, the ABM is created from the existing bone models, among which each bone has an equal contribution to the ABM. Second, combined with medical semantics, some characteristic points and semantic parameters are defined on the ABM, and then, parameter values for each bone can be automatically obtained through its registration and deformation to the ABM. Finally, an average bone template (ABT) is constructed by configuring the semantic parameters and by building the constraints between parameters. Taking 100 femur models as samples, we construct the ABT, and the template can be easily extended to generate a new average template through the given average equation.

Hypernormal Form at Cubic of Honeycomb Sandwich Plate Dynamics Model

Honeycomb sandwich plate have been widly applied in industry design in recent years. In this paper, we study the cubic hypernormal form (the simplest normal form and the unique normal form) for honeycomb sandwich plate dynamics model with the help of Maple symbolic computation. Firstly, we get the average equation of four dimensional cartesian form by using the method of multiple scales perturbation analysis. Based on the method combined new grading function with multiple Lie brackets, we obtain the hypernormal form of cubic truncated. The results will further enrich the research for dynamics of honeycomb sandwich plate model, and is also the basis for higher order normal form research.

Experimental Research on Acoustic Parameters and Saturation of Gas Hydrate-Bearing Sediments

It's very important to control the sensors of ultrasonic and Time Domain Reflectometry when study the relationship between gas hydrate saturation and acoustic parameters in sediments. We combined Ultrasonic Wave and Time Domain Reflectometry in one apparatus to study the acoustic parameters of gas hydrate-bearing sediments in different saturation. The experimental results show that the apparatus is well designed and can work smoothly. Subsequently, we compare the calculated data by time-average equation, Woods equation, Lees weighted equation and Biot-Gassmann Theory by Lee (BGTL) with the observed data in experiments. It suggests that the Lees weighted equation and BGTL are more applicable in our experiments and various sediments.

Bifurcation Analysis of Parametrically Excited Moving String With Aerodynamic Forces

Considering the large deformation of the string, A prototypical model of a elastic moving string with aerodynamic forces is studied. The equation of motion is obtained by Newton’s second law. Then the Perturbation method is used to obtain the average equation and bifurcation equation. Based on the average equation, the stable region of this system is discussed. Based on the bifurcation equation, the multivalued property of response amplitude is studied. At last, the flutter effects of aerodynamic force are discussed by the parametric analysis.

Paleo-Formation Pressure in Storage Layer and its Influence on Hydrocarbon Migration in Dongying Depression

The study of storage layer paleo-pressure in hydrocarbon accumulation period reveals the oil migration direction in Dongying depression. By using of stratum back-stripping method and porosity evolutionary function, the paleo-depth and paleo-porosity of storage layer during Ed, Ng and Nm periods are restored firstly, then the paleo-formation pressure is further recovered by the help of Fillippone formula and time-average equation. The study shows that pressure coefficient is increasing gradually over the 3 periods and overpressure distribution is due to the opening faults. Relations between paleo-pressure and hydrocarbon migration have been analyzed to deduce oil migration direction in storage layer.

Bifurcation Control for a Kind of Non-Autonomous System with Time Delay

A forced van der Pol system with two time-delays is studied. The central aim is analyzing primary resonance of this system. Perturbation method is used to obtain the average equation and bifurcation equation with time-delays. Based on the average equation, the stable region of this system is discussed. Based on the bifurcation equation, the multivalued property of response amplitude is studied. The result indicates that this system can be well controlled with time delays.