International Journal of Engineering
Volume:17 Issue: 4, Nov 2004

A heat transfer model was developed for a new non-electric infant’s transport incubator. The source of heat comprises a super saturated solution of Sodium Acetate and a metal disk (activator) in a plastic container. Estimating the number of the chemical bags required for different ambient temperature was the goal. First the quantity of heat generated by the chemical was appointed through experiments and use of a parameter estimation method. The number of the chemical bags were also estimated through a numerical-experimental method.

Lattice gas automata (LGA) model is developed to simulate polymer adsorption process by adding some collision rules. The simulation result of the model is matched with batch experiment and compared with accepted isothermal adsorption equations. They show that the model is viable to perform simulation of the polymer adsorption process. The LGA model is then applied for simulating continuous polymer solution flow through porous media. Some parameters such as concentration, surface area, and porosity are varied to examine their effects. The concentration and porosity parameters are found to affect adsorption rate at the transient period whereas the surface area affects the maximum number of adsorbed polymer molecules. Meanwhile, the polymer adsorption in porous media may decrease its permeability and fluid velocity.

In a hydroelectric power plant or in a pumping station in order to avoid sudden large increase of pressure due to instantaneous valve closure sometimes a surge tank is installed. The height of surge tank is designed by the highest possible water level during the operation. The theoretical treatment of oscillation in a surge tank is difficult because of the non-linearity of friction term in the governing differential equation of the system. The present study attempts to find a general solution for the surge oscillation in a simple surge tank in terms of non-dimensional parameters. Equations for the highest and the lowest water level in the tank, which are very important in the design of a surge tank have been found.

Experimental investigation of the ultimate resistance of slender, steel-plate girder web panels to combined shear-and-patch loading indicates significant interaction between shear loading and patch loading. However, an existing interaction formula is based on experimental results. Herein, an improved design procedure for slender plate girders subjected to combined shear and patch loading is proposed. A modified formula to evaluate shear resistance of plate girders in presence of patch loading is proposed that shows satisfactory correlation with the available test data and is acceptable for practical purposes.

Among the many parameters affecting the design of hydraulic structures on fissured rocks are orientation of principal permeability axes and degree of anisotropy of fissured rocks. Geological explorations rarely provide this type of information. If at all the information is available, methods employed are computationally cumbersome and inefficient. A new concept of simple equations and geometrical method termed as Permeability Circle similar to Mohr’s circle of stresses has been developed for determination of principal permeability and their orientation from the known characteristics of two-dimensional fissured rock mass.

One of the most important issues that we face in controlling delayed systems and non-minimum phase systems is to fulfill objective orientations simultaneously and in the best way possible. In this paper proposing a new method, an objective orientation is presented for controlling multi-objective systems. The principles of this method is based an emotional temporal difference learning, and has a neuro-fuzzy structure. The proposal method, regarding the present conditions, the system action in the part and the controlling aims, can control the system in a way that these objectives are attain in the least amount of time and the best way. To clarify the issue and verify the proposed the method, three well known control examples which are hard to handle through classic methods are handled by means of the proposed method.

In this paper, we analyze a distributed amplifier based on input/output attenuation compensation. The analysis is carried out for a HEMT transistor; and a constant-k section filter is used to calculate the amplifier’s characteristics such as attenuation factor, phase constant and gain. The proposed design approach enables us to examine the tradeoff among the variables, which include the type and the number of devices, and the impedance and cutoff frequency of the lines. Consequently, we arrive at a design which gives the desired frequency response with significant bandwidth enhancement of around 70% with about 10% increase in circuit size. The simulation carried out by Advance Design System (ADS) software. Excellent agreement is shown when the theoretically predicted response of a typical amplifier is compared with the result of the computer-aided analysis (simulation).

Radiation from monopole antennas on spherical-lossy earth is analyzed by the finitedifference time-domain (FDTD) method in spherical coordinates. A novel generalized perfectly matched layer (PML) has been developed for the truncation of the lossy soil. For having an accurate modeling with less memory requirements, an efficient "non-uniform" mesh generation scheme is used. Also in each time step, computation is limited to that part of the mesh where the radiated pulse is passing (computational window). In this manner, the values of radiated field at far distances can be obtained directly by the FDTD method. The spatial distribution of radiated field and the influence of the ground screen on monopole''s admittance are shown in illustrations.

Resin Transfer Molding (RTM) is a composite manufacturing process. A preformed fiber is placed in a closed mold and a viscous resin is injected into the mold. In this paper, a model is developed to predict the flow pattern, extent of reaction and temperature change during filling and curing in a thin rectangular mold. A numerical simulation is presented to predict the free surface and its interactions with heat transfer and cure for flow of a shear-thinning resin through the preformed fiber. Finite difference method with marker and cell procedure has been used for front flow position prediction. To verify the model results, the temperature profiles for preformed fiber have been calculated, and compared with the experimental results of the other researchers. The results showed that, to optimize the better quality of production of composite materials, and also considering the effect of curing on temperature distribution during the process, the heat dispersion term should not be neglected.

The flow field, velocity and pressure coefficient distribution of some 2-D ideal flows are presented. Conformal mapping is used to simulate two-dimensional ideal flow for a variety of complex internal and external configurations, based on the numerical integration of Schwarz-Christoffel transformation. The advantages of this method are simplicity and high accuracy. The method presented in this paper has been applied to flow problems for which established experimental results are available in the literature. The close agreement between the predictions of simulation program and experimental results shows that the present method is applicable to any 2-D ideal flow regardless of the system of coordinates.