This work presents a novel mathematical model, formed by modifying the conventional Slab Model, to predict the behaviors of tube drawing with a floating plug in the hollow copper tubes. FEM and experimentation are employed to verify the analytical solution. The model incorporates some parameters, including as die semi-angle, plug semi-angle, friction coefficient and wall thickness reduction ratio. The Self Lock Effect is simulated using FEM, and the effect is useful in estimating the critical drawing force. The results of this work reveal that the new model is more accurate than the conventional Slab Model especially at reduction ratios of up to 40%.

In this paper, we present the optimization works of two disk-type piezoelectric transformers (PTs), the single-output PT and the dual-output PT, by using the elite Genetic Algorithm (GA) and the finite-element solver, NTUPZE. The goal of optimization is to maximize the efficiency under the constraint that the voltage gain is greater than 50 for igniting CCFL. The design parameters are the radii of the outputelectrode sections and the electrode areas, as well as the dimensions of the device structure. With different electrical loading impedances, the voltage gain and the efficiency were computed using the NTUPZE. The results were also validated with measured data. The optimization process is parallelized by the MPI library and a PC cluster for improving the computation efficiency. The characteristics of the optimal designs with different loads are also calculated. The optimized voltage gain and the efficiency for the PT with single output electrode are about 53 and 91.9%, respectively. Also, the voltage gains and the efficiency of PT with dual output electrodes are above 57 and 91%, respectively.

Performance of an improved shock absorber designed for absorbing and isolating the oil test pipe vibration is researched in this paper. 3D finite element model is established for the analysis of the shock absorber system accurately by the FEA software ANSYS/LS-DYNA. Numerical simulations show that the effect of the shock absorber can be greatly improved by optimizing the plastic material parameter. In the practice petroleum well test, the new designed shock absorber showed good shock absorption effect and no damage on the detecting instruments was observed even after ten times loading.

The main purpose of this paper is to investigate the pressure-stream function formulation to solve 2D and 3D Stokes flows by the meshless numerical scheme of the method of fundamental solutions (MFS). The MFS can be regarded as a truly scattered, grid-free (or meshless) and non-singular numerical scheme. By the proposed algorithm, the stream function is governed by the bi-harmonic equation while the pressure is governed by the Laplace equation. The velocity field is then obtained by the curl of the stream function for 2D flows and curl of the vector stream function for 3D flows. We can simultaneously solve the pressure, velocity, vorticity, stream function and traction forces fields. Furthermore during the present numerical procedure no pressure boundary condition is needed which is a tedious and forbidden task. The developed algorithm is used to test several numerical experiments for the benchmark examples, including (1) the driven circular cavity, (2) the circular cavity with eccentric rotating cylinder, (3) the square cavity with traction boundary conditions and (4) the uniform flow past a sphere. The results compare very well with the solutions obtained by analytical or other numerical methods such as finite element method (FEM). It is found that the meshless MFS will give a simpler and more efficient and accurate solutions to the Stokes flows investigated in this study.

The flow of a viscous still fluid disturbed by an oscillating porous plate with an arbitrary initial phase is investigated. Using the Laplace transform, the exact solution of the velocity profile is revisited. Subsequently, the wall stress implying the required driving force is derived in this study. The solutions are valid not only for large times but also for small times. Four special cases are discussed to investigate the influences of four parameters on the development of the flow. A dimensionless analysis for general cases is also provided. Our analyses significantly stress on the following subjects. Firstly, the porous velocity and the decay factor affecting the development of the flow are studied. Secondly, the occurrence time of separation and the corresponding critical condition are investigated. The period of the transient velocity influenced by the Reynolds number and the initial phase is discussed. Present study includes many existing solutions as special cases. Results can be also applied to many engineering problems with the same PDE form and boundary conditions. In conclusion, this study presents the detailed discussions and the magnitude of the required driving force which were missed in previous works.

This study investigates the problem of non-Newtonian liquid evaporation from an impermeable vertical plate in a porous medium under mixed convection conditions. The analysis examines the effects of non-Darcian flow phenomena on the evaporation process and investigates the heat and mass transfer characteristics under a range of flow conditions in the aiding and opposing flow types. The parameters of interest include Rak,non, Pex,non, Pr and Sc. The data required for the calculations include a fixed wall temperature of Tw = 45°C, a free flow temperature of T∞ = 20°C and an air free flow rate of u∞ = 4m/sec and the corresponding humidity of 50% flows over fixed temperature and moist wall.

The results indicate that an increasing buoyancy force enhances the mixing effect and therefore improves the rate of heat transfer, the latent heat flux is the primary mode of heat transfer in evaporation processes and the velocity gradient at the wall increases with an increasing buoyancy effect. Furthermore, the evaporation rate increases with a reducing flow index and an increasing buoyancy effect.

This paper describes the combination of the method of fundamental solutions (MFS) and the dual reciprocity method (DRM) as a meshless numerical method to solve problems of thin plates resting on Winkler foundations under arbitrary loadings, where the DRM is based on the augmented polyharmonic splines constructed by splines and monomials. In the solution procedure, the arbitrary distributed loading is first approximated by the augmented polyharmonic splines (APS) and thus the desired particular solution can be represented by the corresponding analytical particular solutions of the APS. Thereafter, the complementary solution is solved formally by the MFS. In the mathematical derivations, the real coefficient operator in the governing equation is decomposed into two complex coefficient operators. In other words, the solutions obtained by the MFS-DRM are first treated in terms of these complex coefficient operators and then converted to real numbers in suitable ways. Furthermore, the boundary conditions of lateral displacement, slope, normal moment, and effective shear force are all given explicitly for the particular solutions of APS as well as the kernels of MFS. Finally, numerical experiments are carried out to validate these analytical formulas.

In this article the mass and heat transfer between fluid molecule and carbon tube is studied via molecular dynamic simulation based on Lennard-Jones Potentia and Bernner-Tersoff Potential model. Some valve holes are formed by removing different numbers of molecules from flank of (5, 5) armchair carbon tube (the hole area = 17.3 ∼ 116.9Å2). The results indicate that only diffusion behavior is not able to describe the phenomena, otherwise the atom release rate and valve hole size are interdependent. Meanwhile the variation of potential energy barrier, work function, energy gap arose from different valve geometrical size are observed. These variations can influence the dynamic behavior such as flow rate and velocity by molecule penetration.

By considering the total transverse displacement of a sandwich plate as the sum of the displacement due to bending of the plate and that due to shear deformation of the core, a high precision higher order triangular plate element is developed for the nonlinear panel flutter analysis of thermally buckled sandwich plates. Von Karman large deformation assumptions and quasi-steady aerodynamic theory are employed for the analysis. Newmark numerical time integration method is applied to solve the nonlinear governing equations in time domain. Results show that temperature will increase both the maximum displacement and motion speed of the plate. But the maximum displacement and velocity of the plate will not vary much with the aerodynamic pressure. Buckle pattern change phenomenon occurred in some specific case will increase the flutter boundary and change the flutter motion type of the plate. Temperature gradient increases the overall stiffness of the plate, which in turn stabilizes the sandwich panel and increases the flutter boundary of the plate.

This paper deals with the linear dynamic responses of beams with a flexible support under a moving load with a constant speed. The entire system is modeled as a two-span beam and each span of the continuous beams is assumed to obey the Euler-Bernoulli beam theory. Considering the compatibility requirements on the flexible constraint, the relationships between two segments can be obtained. By using a transfer matrix method, the characteristic equation of the entire system can then be determined. The forced responses of the system under a moving load can then be obtained through modal expansion theory. Some numerical results are presented to the effects of support stiffness and the different speeds of the moving load.

The aim of this paper is to investigate the mechanism of the fission process and the flow field of N-waves in the near-shore region. From the elaborate experimental analysis, a subsequence of a second soliton released during shoaling reigon is identified to realize the further evolution of N-waves over a sloping beach, in comparison with the non-fission case. The fission index is indicated by a dimensionless factor A0/d0, which is used to describe the nonlinearity as well. It is known that the reflecting wave and the breaking effect could easily initiate another soliton, especially for strong nonlinear case. A series of experiments were conducted in a super wave flume (300m × 5m × 5.2m) at Tainan Hydraulics Laboratory (THL), National Cheng Kung University (NCKU). The entire evolution of the leading and second solitons and the generation mechanism for the third soliton would be discussed in this paper.

The coefficient C1 in the displacement coefficient method of FEMA-273/356 is the modification factor to relate the expected maximum displacements of elasto-plastic inelastic SDOF systems to displacements calculated for linear response. It permits the estimation of maximum inelastic displacements from maximum elastic displacements for structures with known lateral strength (usually, the existing structures). Recently, an improved C1 has been presented in FEMA-440 because it was shown that the C1 in FEMA-273/356 underestimates the maximum inelastic displacement demands of structures significantly. However, the improved C1 in FEMA-440 was derived from the earthquake ground motions recorded in California. In addition, it was mentioned in FEMA-440 that “caution should be used when extrapolating the results presented in the report for ground motions and site conditions that differ”. Because the characteristics of earthquakes occurred in Taiwan are different from those occurred in California, the coefficient for used in Taiwan needs to be modified. The objective of this paper is to propose appropriate C1 for use in Taiwan.

Fluid flow and heat transfer in duct fan flows with a 90° rectangular-wing turbulator, mounted on the top duct wall, were experimentally studied and compared with the bottom-wall turbulator results. Threecomponent velocities were measured to characterize the flow structures and to obtain near-wall flow parameters. Temperatures on heat transfer surfaces were measured to obtain Nusselt number distributions. Results show that the turbulator has the effect to increase the near-wall axial mean velocity, axial vorticity and turbulent kinetic energy, and, consequently, augment the heat transfer. The axial mean velocity and axial vorticity play an influential role on the heat transfer distributions for the flows across the top-wall and bottom-wall turbulators, respectively.

In this study, an analysis has been performed for heat and mass transfer of a steady laminar boundarylayer flow of an electrically conducting fluid with radiation effect of second grade subject to suction and to a transverse uniform magnetic field past a stretching sheet. Parameters Gr, Gc, Nr, M, Sc represent the dominance of the buoyant effect, radiative effect, magnetic effect and mass transfer effect which have presented in governing equations, respectively. The similar transformation and the finite-difference method have been used to analyze the present problem.