Journal of Mechanical Science and Technology - Particle damping is a passive control technology with strong nonlinearity whose damping effect is relative to the vibration intensity where a particle... 相似文献
A mathematical model of internal combustion engine is obtained based on the approximation of its speed characteristics, efficiency,
and toxicity of exhaust gases with the use of a feedforward artificial neural network. The dependence of the approximation
error of engine characteristics on the structure and parameters of the model is investigated. 相似文献
In this research, we proposed an electrochemical method for the recycling of carbon fibers from carbon fiber reinforced polymer (CFRP). Experiments were designed with different solution concentrations (3%, 10%, and 20% NaCl) and various levels of applied current (4 mA, 10 mA, 20 mA, and 25 mA) so as to identify the significant parameters that affect carbon fiber recycling efficiency. The recycled carbon fibers were characterized by using the single fiber tensile strength test, SEM, XRD, and XPS techniques. Test results showed that the maximum tensile strength of the reclaimed carbon fibers was 80% of the virgin carbon fibers (VCF). The increase in electrolyte concentration did not improve the recycling efficiency but resulted in severe oxidation and chlorination on the surface of recycled carbon fibers. From the experimental results, it can be concluded that the recycling of carbon fibers with electrochemical method is simple, effective, and economical. 相似文献
A new adjustable guide vane (AGV) is proposed in this paper. This vane can reduce hydraulic losses and improve the performance
of an axial flow pump. The formula of AGV adjustment was obtained after theoretical analysis. The fluid flow inside the axial
flow pump with a fixed guide vane and adjustable guide vane was simulated. The calculated Q-H curves for the fixed guide vane
agreed well with the experimental ones. The results show that the attack angle and flow separation have an important contribution
to the vortices which create hydraulic losses in the guide vane channel. The AGV can decrease hydraulic losses and significantly
enhance the pump head and efficiency by changing the guide vane angle. 相似文献
Accurate evaluation of transverse stresses in laminated composites and sandwich plates using 2D FE models involves cumbersome post-processing techniques. In this paper a simple and efficient method has been proposed for accurate evaluation of through-the-thickness distribution of transverse stresses in composites and sandwich laminates by using a displacement based C0 FE model (2D) derived from Refined Higher Order Shear Deformation Theory (RHSDT) and a Least Square Error (LSE) method. The C0 FE model satisfies the inter-laminar shear stress continuity conditions at the layer interfaces and zero transverse shear stress conditions at the top and bottom of the plate. In this model the first derivatives of transverse displacement have been treated as independent variables to circumvent the problem of C1 continuity associated with the above plate theory (RHSDT). The LSE method is applied to the 3D equilibrium equations of the plate problem at the post-processing stage, after in-plane stresses are calculated by using the above FE model based on RHSDT. Thus the proposed method is quite simple and elegant compared to the usual method of integrating the 3D equilibrium equations at the post-processing stage for calculation of transverse stresses in a composite laminate. In the proposed method, the first two equations of equilibrium are utilized to compute the transverse shear stress variation through the thickness of a laminated plate whereas the third equation of equilibrium gives the normal stress variation. Accuracy of the proposed method is demonstrated in the numerical examples through comparison of the present results with those obtained from different models based on higher order shear deformation theory (HSDT) and 3D elasticity solutions. 相似文献
The hydrodynamic behaviors of multi-bubble in a gas–liquid system which differs from that of a single bubble are found to be dependent on the complex hydrodynamic interactions between neighboring bubbles. It is observed that wake effect which leads to an increased rising velocity is responsible for bubble–bubble interactions. In this paper, a new drag force model was proposed to consider the wake acceleration effect on spherical bubbles. Key relation of the new model is the modeling of the relationship between the reduced drag force and the wake velocity, for which the concept of define a proper reference fluid velocity is applied. No artificial coefficient is employed in the current analysis. The proposed model was validated against experimental and numerical studies in which spherical bubble pairs are aligned in line vertically. It is illustrated that the performance of the proposed model in predicting the wake acceleration effect are promising for 3 ≤ Reb ≤ 200 and 2 ≤ s/d ≤ 15. The small discrepancies may be related to the wake velocity profile predicted by laminar boundary layer theory. 相似文献
The leader-following consensus problem for a class of second-order nonlinear multi-agent systems under Markovian switching topologies is studied. First, a discontinuous distributed adaptive nonlinear control law using the relative state information between neighboring agents is designed for heterogeneous multi-agent systems, which achieves almost sure leader-following consensus for the closed-loop system. Then, a smooth distributed control law is designed for homogeneous multi-agent systems. Compared with previous results, the nonlinear functions are not required to satisfy the globally Lipschitz condition and the adaptive consensus protocol is in a distributed fashion, i.e., using only the relative information. A practical example of ship course control system and simulation are provided to demonstrate the effectiveness of the control scheme.