Applied Mechanics and Materials Vols. 226-228

Abstract: In order to improve the dynamic characteristics of scroll compressor, according to the crankshaft bearing characteristics of scroll compressor, based on the forces and moment equilibrium equations of the crankshaft and compressor frame body, used the frame body forces and crankshaft bearing loads as a variable, analyzed the frame body forces in the best of conditions by changing the counterweights installation angle to control the crankshaft bearing design formulas, thus obtained counterweights quality and phase angle and other parameters, ensured the service life of the bearing, and obtained effective control of the crankshaft bearing load and frame body force, improve the operation reliability of scroll compressor, prolonging the service life. This paper puts forward a set of formulas, which are derived based on analysis of the loads at crankshaft of scroll compressor. The formulas can be used to determine the parameters of installation angle of the counterweight and the forces of loads at crankshaft for scroll compressor.

Abstract: According to the lack of cylinder-model noise source localization technology based on near-field focused beam-forming, the paper aimed to find a near-field high-resolution method of the cylindrical noise source which is applied to measure the model as cylinder-models. This method established a near-field measurement model of noise sources using cylindrical measurement surface, and applied MVDR algorithm to noise sources localization. Reconstruct the cylinder measurement surface through the joint amplitude-phase compensation to achieve the noise source high-resolution localization and relative intensity estimates in the near-field. Verify the availability of this method through the simulations, which provided a theoretical basis for the next practical engineering application of the cylinder-model noise source localization based on near-field focused beam-forming.

Abstract: The basic array error correction method based on a single auxiliary vector hydrophone is proposed for the difficult problem of the basic array error correction and the constraint of the space size of the tank. This method used the single vector hydrophone by precisely correction to implement non-fuzzy joint estimation of the source orientation and the orientation dependence of the basic array amplitude-phase error, and correct the error of the array element location. The method of this paper is applied to the arbitrary array structure, which doesn't exist the local convergence problem of the joint parameter estimation, only needs one-dimensional search for parameters which make the computing time less and can complete online in real-time.At last, the computer simulation verified the effectiveness of this method.

Abstract: The generation of aerodynamic noise of aircraft in flight is due to dynamical system and aerodynamic .The response of aircraft subjected to High acoustic loads and aerodynamic loads can produce fatigue and damage. In this paper a new Aeroelastic- Acoustics which adds acoustic loads in aeroelastic is presented. The emphasis of the study is the discipline of displacement and load of the flexible structure under the unsteady aerodynamic, inertial, elastic and aero-acoustic. The CFD/CSD/CAA coupling is used to simulate rockets cabin. Sound generated by a rocker is predicted numerically from a Large Eddy simulation (LES) of unsteady flow field. The Lighthill acoustic analogy is used to model the propagation of sound. The structural response of rocket cabin was given. The boundary-layer transition on the pressure side of the cabin is visualized, by plotting to better illustrate the essential interaction between fluctuating pressure and structure.CFD/CSD/CAA coupling compute method is validated in low and middle frequency.

Abstract: Oscillations of cytosolic calcium concentration, known as calcium oscillations, play a vital role in providing the intracellular signalling. These oscillations are explained with a model based on calcium-induced calcium release (CICR). The nonlinear dynamics of the Kummer-Olsen calcium oscillation model is discussed by using the center manifold theorem and bifurcation theory, including the variation in classification and stability of equilibria with parameter value. It is concluded that the appearance and disappearance of calcium oscillations in this system is due to supercritical Hopf bifurcation of equilibria. Finally, numerical simulations are carried out to support the theoretical analysis of the research. By combining the existing numerical results with the theoretical analysis results in this paper, a complete description of the dynamics of the Kummer-Olsen calcium oscillation model has now been obtained.

Abstract: Calcium oscillations play a very important role in providing the intracellular signaling, and many mathematical models have been proposed to describe calcium oscillations. The Shen-Larter model presented here is based on calcium-induced calcium release (CICR) and the inositol trisphosphate cross-coupling (ICC). Nonlinear dynamics of this model is investigated by using the centre manifold theorem and bifurcation theory, including the variation in classification and stability of equilibria with different parameter values. The results show that the appearance and disappearance of calcium oscillations are due to subcritical Hopf bifurcation of equilibria. The numerical simulations are performed in order to illustrate the correctness of our theoretical analysis, including the bifurcation diagram of fixed points, the phase diagram of the system in two dimensional space and time series.

Abstract: In this paper, the attitude and dynamical characteristics of a kind of submerged buoy are studied. The attitude of the buoy system is calculated relatively accurately by mathematical derivations and programming, in which all the tangent and normal fluid drag forces and elastic deformation of the mooring cable are considered. Based on the ANSYS FEA software, the model of system in fluid is established, which takes the effects of fluid drag forces, pretension and additional mass into account. Then the analysis of the effect on dynamics characteristic of the system by considering the attitude or not is carried out. The results indicate that, for small-scale submerged buoy system, the completed fluid forces should not be ignored, and the vibration of mooring system of submerged buoy is most likely to be low-frequency vibration, which should be avoided in some ways.

Abstract: The Borghans-Dupont model of calcium oscillations based on both the calcium-induced calcium release and calcium-activated inositol trisphosphate concentration degradation is considered. Dynamical effect of the stimulation level on the calcium oscillation behavior is studied. The qualitative theory of differential equations is used to explain the mechanism of these oscillations. We investigate the existence, types, stability and bifurcations of the equilibria by applying the centre manifold theorem, stability theory and bifurcation theory and prove that oscillations are due to supercritical Hopf bifurcation. Finally, we perform numerical simulations, including time courses, phase portraits and bifurcation diagram, to validate the correctness and the effectiveness of our theoretical analysis. These results may be instructive for understanding the role of the stimulation level played in complex dynamics in this model.

Abstract: Ultrasonic guided wave provides a suitable fast screening technique that enables the localization of the defects and offers a rough estimation of the defect size in pipes. Using the ANSYS, the entity model of a pipe with defects such as cracks and holes was established in this paper. Then the L(0,2) mode guided wave was excited by exerting symmetric displacement loads on an end of the pipe model. By analyzing the incident wave and the reflected wave of defects, the axial location and circumferential location of the defects can be reached. Besides, by fitting the data with some certain formulas, the relationships between reflection coefficient and the defects extent can be acquired. This new technique is of great significance in nondestructive detection.

Abstract: This paper investigates the bifurcations of the periodic solutions in the piecewise linear systems. Firstly the equation about amplitude-frequency response is deduced by the averaging method. Then the bifurcation classification is conducted by applying the singularity theory. The effects of the two parameters, the mass and the excitation amplitude, are discussed. The balance position will be changed when the quality changed, So the system is divided into two kinds of state. The results show that the parameter plane is divided into thirteen regions where bifurcation types are different. At last, discussing the amplitude- frequency response of different regions. this paper provides some theoretical guidance for system of considering load variation, and it is significant to help research the change in amplitude-frequency characteristic of piecewise linear system.