Applied Mechanics and Materials Vols. 110-116

Abstract: The effect of the wavy surface on the aerodynamic characteristics of an airfoil is studied using the large eddy simulations. A more gentle lift characteristic is obtained during stall. For angles of attack less than the baseline stall angle of a NACA0012 airfoil, a lift coefficient reduction was observed for the wavy airfoils, while the lift coefficient increases up to 23% greater than that of a NACA0012 airfoil when the angle of attack is larger than the baseline stall angle of the NACA0012 airfoil.

Abstract: This paper deals with the new method to design the optimum design for hospital bed, which can separate the left and or right leg for patient‘s leg splint. GAs as an optimization method was selected to search the minimum mass of bed structure whilst fulfilling some structure constraints such as stress, displacement and buckling. The GAs and FE code were developed to analyze the structure in MATLAB. This paper showed the success in searching the minimum mass whilst the stress and displacement were accepted. The optimum design for the hospital bed was 49.25 kg.

Abstract: This paper deals with a class of optimal control problems governed by linear Fredholm integral equations. A direct scheme based on the Taylor expansion and parametrization to calculate an approximate-analytical solution of the problem is proposed. This method produces an approximation with a controlled level of accuracy. Moreover, a hybrid algorithm to show the procedure of the scheme is given. The convergence of the proposed scheme is also discussed in detail. Some numerical examples illustrate the potential, efficiency and accuracy of the algorithm.

Abstract: Disposal of fly ash obtained from thermal power plants is a major environmental concern. Fly ash contains large proportions of silica and ferrites. Investigation of its prospects as an electronic material provides scope for enhanced fly ash utilization. This involves measurement of relative permittivity and loss tangent. Experiments are carried out at X band frequencies in TE₁₀ mode using standard klystron waveguide setup. Shorted Waveguide Method is used to determine the complex permittivity. The complex transcendental equation obtained is solved using Genetic Algorithm. Experimental results are compared with theoretical estimates based on Landau Lifshitz Looyenga (LLL) equation.

Abstract: In this study aeroelastic characteristics of long high aspect ratio wing models with structural nonlinearities in quasi-steady aerodynamics flows are investigated. The studied wing model is a cantilever wing with double bending and torsional vibrations and with large deflection ability in according to Dowell-Hodges wing model. This wing model is valid for long, straight and thin homogeneous isotropic beams. Aerodynamics model is based on quasi-steady aerodynamic which is valid for aerodynamic flows in low velocity and without wake, viscosity and compressibility effects. The effect of different parameters such as mass ratios and stiffness ratios on flutter and divergence velocities and limit cycle oscillation amplitudes are carefully studied.

Abstract: This paper considers the problem of designing cellular manufacturing systems (CMS) with the presence of alternate process plans, tools and workers. The objective is to minimize the total costs of machine installation, operations, tools and workers with a number of identified practical constraints. A genetic algorithm is designed in order to efficiently solve medium and large sized problems. Preliminary numerical results show the worth of implementing the suggested procedure.

Abstract: In this paper, a numerical model is developed to simulate single droplet heat and mass transfer in a two-pieces solution with a saturated solvent vapor environment. Finite volume method and transient SIMPLEC algorithm in spherical coordinates system used for simulation. For simulation of the mass transfer, dimensionless equations of motion, heat transfer and mass transfer (based on mass ratio) are solved simultaneously. All the thermodynamic and transitional solution properties have been considered as a function of temperature and concentration. Verification of method is done by compare these numerical results with analytical and numerical analysis of other studies. Evaporation, absorption and condensation contours in a water droplet at uniform temperature at superheated water vapor and Distribution of Droplet's Surface Temperature, Constant Temperature and concentration lines as the modeling results are presented. The results are shown that 0.5% increase of concentration of droplet cause increase 8 degree C of mean temperature of droplet.

Abstract: Mixed-model assembly line is known to be a special case of production lines where various and different models of the same products are inter-mixed to be assembled on the same line. Using mixed model assembly line involves not only the traditional problems of assembly line design (i.e., determining the line cycle time, the number and sequence of stations of the line, and balancing the line) but also determining the sequence in which products will be scheduled for assembly. In each station, some components are assembled in the final products. Under just in time (JIT) approach; an objective is to have a fairly constant usage rate for each component going into final assembly to facilitate the use of Kanban or other JIT shop-floor systems. In this paper, a mixed approach, the sequencing mixed-model assembly line problem with a JIT-supply of required materials, ‌is studied and a mathematical model is proposed for solving it. The results are compared with a traditional approach. Some experiments are used to evaluate the performance of the proposed model.

Abstract: In this study a CFD model of a spark ignition (SI) engine was prepared using KIVA-3V code and experimental data to investigate the in-cylinder flow field. The whole engine cycle was simulated and the validity of the model was ascertained by experimental result of in-cylinder bulk pressure and flow field visualization. The flow pattern inside the cylinder was investigated qualitatively to deepen our understanding of the formation and development of rotational flow prior to the ignition. Both tumble and swirl were observed in the flow field. The numerical results showed that turbulence intensity in the section with stronger vortex is higher.

Abstract: With the progressive development of photogrammetric technology, the digital photogrammetric method based on the basic principles of digital imaging and photogrammetry has replaced the traditional photogrammetric mapping method and has been widely promoted and applied. In this paper, it studies further the issues about the image processing and photogrammetric algorithms of common digital cameras based on some research results in the traditional field of close-range photogrammetry, and verifies with actual examples the application of using digital cameras to implement the close-range photogrammetric method to engineering is feasible.