Catálogo de publicaciones - libros

Sports nets and hammocks are usually not pre-tensioned and too slack and flexible to resist compressive forces, which the high pre-stressing would counterbalance in tension structures. Due to this incompressibility, the low-tension nets may exhibit extreme sags in the deformed configuration, which may be one computational problem in analysis. The present study is concerned with this particular, but interesting issue and proposes some modelling ideas to simulate the static and dynamic response of flexible and incompressible nets, which are not frequently treated in engineering applications. Special attention is paid to dynamics of hexagon-mesh goal nets used in FIFA World Cup 2002 in Japan and South Korea. In numerical examples, it is illustrated that the hexagon-mesh net is much better than the square-mesh net, especially for more enthusiasm in stadium and also for better visual effects in TV.

In this paper, the authors analyse the aerodynamic properties of soccer ball. Using ADVENTURE System, the finite element flow analysis around soccer ball is performed to figure out the coefficient of drag of soccer ball, the critical Reynolds number of drag crisis, the track of curveball.

The performance of a twin-screw supercharger is influenced more by the internal air leakages than by any other thermo-fluid aspect of its behaviour. The distribution of leakage through the various leakage paths within the machine is, thus, important for the improvement of the performance. The numerical analysis is conducted using a Computational Fluid Dynamics (CFD) software commercially available, FLUENT. The main innovation in this research is to integrate this advanced CFD modelling technique, which is used for modelling complex airflow behaviour in the complex supercharger passages, with an advanced CAD module, which is used for design of new supercharger rotors and manifolds. This has allowed creating a new innovative fully integrated CAD/CFD supercharger design environment, which can address all aspects of fluid and geometry requirements for the future supercharger designs. This approach will insure the production of the highest quality designs at the lowest manufacturing cost and in the shortest turn around time.

This paper presents a numerical study on the transport of ions and ionic solution in human corneas and their influences on the corneal hydration. The transport equations for ions and ionic solution within the cornea are derived based on transport processes in electrolytic solutions, whereas the transport across epithelial and endothelial membranes is described by using phenomenological equations derived on the thermodynamics of irreversible processes. Numerical examples are given for a typical human cornea from which some important features are highlighted.

In this paper, the method of fundamental solutions (MFS) for solving the eigenfrequencies of multiply connected plates is proposed. The coefficients of influence matrices are easily determined when the fundamental solution is known. True and spurious eigensolutions appear at the same time. It is found that the spurious eigensolution using the MFS depends on the location of the inner boundary where the fictitious sources are distributed. To verify this finding, mathematical analysis for the appearance of spurious eigenequations using degenerate kernels and circulants is done by demonstrating an annular plate with a discrete model. In order to obtain the true eigensolution, the Burton & Miller method is utilized to filter out the spurious eigensolutions. One example is demonstrated analytically and numerically to see the validity of the present method.

We describe a two-grid finite element discretization scheme which can be used to trace solution branches as well as to detect bifurcation points of certain second order semilinear elliptic eigenvalue problems. Sample numerical results are reported.

We study two grid centered-difference discretization schemes for both linear and nonlinear eigenvalue problems, where the Lanczos type algorithms, namely MINRES and SYMMLQ are used as linear solvers. Numerical experiments on some test problems are reported.

This paper describes a valve gear vibrational analysis. In order to calculate the kinematic and dynamic values and to assess the minimum oil film thickness in the valve gear, the vibrational mathematical multidegree of freedom model of valve gear was used. In addition, the comparison of the results between the polysine cam and the new MULTICAM cam design was made. By means of the new cam design the Hertz pressures were reduced at the point of contact between the cam and the cam follower and the lubrication properties at the top of the cam improved.

A new method for estimating the fundamental matrix is proposed. Using eigenvectors corresponding to the two smallest eigenvalues obtained by the orthogonal least-squares technique, we construct a 3 × 3 generalized eigenvalue problem. Its solution gives not only the fundamental matrix but also the corresponding epipoles. The new method performs well as compared with several existing linear methods.

An exact solution for the free vibration of a tapered beam with elastic end rotational restraints problem is obtained using the Euler–Bernoulli theory of beam vibrations by programming them in FORTRAN 90. Natural frequencies and mode shape details of an Euler–Bernoulli beam with ends on elastically support are derived. Free vibration of uniform and tapered beam with elastic restraint is studied using free vibration equation and the well-known Bessel functions. In this way exact results can be obtained for the entire cross sectional laws which allow one to reduce the equation of motion to a couple second-order Bessel equations. The resulting displacement is then expressed in terms of Bessel functions. Natural frequencies and mode shapes are determined using governed boundary conditions (spring-free) and obtaining the matrix of coefficient. By equaling the matrix determinant to zero and finding the roots actually natural frequencies are derived. The paper ends with numerical examples, which confirm the usefulness of the proposed method, and in good agreement with some previously known results from journal papers and finite element methods. The accuracy of the method considering simplicity of it is very precious.